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  • richardmitnick 4:35 pm on May 22, 2022 Permalink | Reply
    Tags: "CDWs": charge density waves-ripples in the density of electrons in the material, "Superconductivity and charge density waves caught intertwining at the nanoscale", "YBCO": yttrium barium copper oxide, , , DOE’s SLAC National Accelerator Laboratory, , , , , These LCLS experiments generated terabytes of data-a challenge for processing.,   

    From DOE’s SLAC National Accelerator Laboratory : “Superconductivity and charge density waves caught intertwining at the nanoscale” 

    From DOE’s SLAC National Accelerator Laboratory

    May 20, 2022
    Jennifer Huber


    Credit: Greg Stewart/SLAC National Accelerator Laboratory.

    Scientists discover superconductivity and charge density waves are intrinsically interconnected at the nanoscopic level, a new understanding that could help lead to the next generation of electronics and computers.

    Room-temperature superconductors could transform everything from electrical grids to particle accelerators to computers – but before they can be realized, researchers need to better understand how existing high-temperature superconductors work.

    Now, researchers from the Department of Energy’s SLAC National Accelerator Laboratory, the University of British Columbia, Yale University and others have taken a step in that direction by studying the fast dynamics of a material called yttrium barium copper oxide, or YBCO.

    The team reports May 20 in Science that YBCO’s superconductivity is intertwined in unexpected ways with another phenomenon known as charge density waves (CDWs), or ripples in the density of electrons in the material. As the researchers expected, CDWs get stronger when they turned off YBCO’s superconductivity. However, they were surprised to find the CDWs also suddenly became more spatially organized, suggesting superconductivity somehow fundamentally shapes the form of the CDWs at the nanoscale.

    “A big part of what we don’t know is the relationship between charge density waves and superconductivity,” said Giacomo Coslovich, a staff scientist at the Department of Energy’s SLAC National Accelerator Laboratory, who led the study. “As one of the cleanest high-temperature superconductors that can be grown, YBCO offers us the opportunity to understand this physics in a very direct way, minimizing the effects of disorder.”

    He added, “If we can better understand these materials, we can make new superconductors that work at higher temperatures, enabling many more applications and potentially addressing a lot of societal challenges – from climate change to energy efficiency to availability of fresh water.”


    The team aimed infrared laser pulses at the YBCO sample to switch off its superconducting state, then used X-ray laser pulses to illuminate the sample and examined the X-ray light scattered from it. Their results revealed that regions of superconductivity and charge density waves were arranged in unexpected ways. (Courtesy Giacomo Coslovich/SLAC National Accelerator Laboratory)

    Observing fast dynamics

    The researchers studied YBCO’s dynamics at SLAC’s Linac Coherent Light Source (LCLS) X-ray laser [below]. They switched off superconductivity in the YBCO samples with infrared laser pulses, and then bounced X-ray pulses off those samples. For each shot of X-rays, the team pieced together a kind of snapshot of the CDWs’ electron ripples. By pasting those together, they recreated the CDWs rapid evolution.

    “We did these experiments at the LCLS because we needed ultrashort pulses of X-rays, which can be made at very few places in the world. And we also needed soft X-rays, which have longer wavelengths than typical X-rays, to directly detect the CDWs,” said staff scientist and study co-author Joshua Turner, who is also a researcher at the Stanford Institute for Materials and Energy Sciences. “Plus, the people at LCLS are really great to work with.”

    These LCLS experiments generated terabytes of data-a challenge for processing. “Using many hours of supercomputing time, LCLS beamline scientists binned our huge amounts of data into a more manageable form so our algorithms could extract the feature characteristics,” said MengXing (Ketty) Na, a University of British Columbia graduate student and co-author on the project.

    The team found that charge density waves within the YBCO samples became more correlated – that is, more electron ripples were periodic or spatially synchronized – after lasers switched off the superconductivity.

    “Doubling the number of waves that are correlated with just a flash of light is quite remarkable, because light typically would produce the opposite effect. We can use light to completely disorder the charge density waves if we push too hard,” Coslovich said.


    Blue areas are superconducting regions, and yellow areas represent charge density waves. After a laser pulse (red), the superconducting regions are rapidly turned off and the charge density waves react by rearranging their pattern, becoming more orderly and coherent. (Greg Stewart/SLAC National Accelerator Laboratory)

    To explain these experimental observations, the researchers then modeled how regions of CDWs and superconductivity ought to interact given a variety of underlying assumptions about how YBCO works. For example, their initial model assumed that a uniform region of superconductivity when shut off with light would become a uniform CDW region – but of course that didn’t agree with their results.

    “The model that best fits our data so far indicates that superconductivity is acting like a defect within a pattern of the waves. This suggests that superconductivity and charge density waves like to be arranged in a very specific, nanoscopic way,” explained Coslovich. “They are intertwined orders at the length scale of the waves themselves.”

    Illuminating the future

    Coslovich said that being able to turn superconductivity off with light pulses was a significant advance, enabling observations on the time scale of less than a trillionth of a second, with major advantages over previous approaches.

    “When you use other methods, like applying a high magnetic field, you have to wait a long time before making measurements, so CDWs rearrange around disorder and other phenomena can take place in the sample,” he said. “Using light allowed us to show this is an intrinsic effect, a real connection between superconductivity and charge density waves.”

    The research team is excited to expand on this pivotal work, Turner said. First, they want to study how the CDWs become more organized when the superconductivity is shut off with light. They are also planning to tune the laser’s wavelength or polarization in future LCLS experiments in hopes of also using light to enhance, instead of quench, the superconducting state, so they could readily turn the superconducting state off and on.

    “There is an overall interest in trying to do this with pulses of light on very fast time scales, because that can potentially lead to the development of superconducting, light-controlled devices for the new generation of electronics and computing,” said Coslovich. “Ultimately, this work can also help guide people who are trying to build room-temperature superconductors.”

    This research is part of a collaboration between researchers from LCLS, SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL), UBC, Yale University, the Institut National de la Recherche Scientifique in Canada, North Carolina State University, Universita Cattolica di Brescia and other institutions. This work was funded in part by the DOE Office of Science. LCLS and SSRL are DOE Office of Science user facilities.

    See the full article here.


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    SLAC National Accelerator Laboratory originally named Stanford Linear Accelerator Center, is a United States Department of Energy National Laboratory operated by Stanford University under the programmatic direction of the U.S. Department of Energy Office of Science and located in Menlo Park, California. It is the site of the Stanford Linear Accelerator, a 3.2 kilometer (2-mile) linear accelerator constructed in 1966 and shut down in the 2000s, which could accelerate electrons to energies of 50 GeV.

    Today SLAC research centers on a broad program in atomic and solid-state physics, chemistry, biology, and medicine using X-rays from synchrotron radiation and a free-electron laser as well as experimental and theoretical research in elementary particle physics, astroparticle physics, and cosmology.

    Founded in 1962 as the Stanford Linear Accelerator Center, the facility is located on 172 hectares (426 acres) of Stanford University-owned land on Sand Hill Road in Menlo Park, California—just west of the University’s main campus. The main accelerator is 3.2 kilometers (2 mi) long—the longest linear accelerator in the world—and has been operational since 1966.

    Research at SLAC has produced three Nobel Prizes in Physics

    1976: The charm quark—see J/ψ meson
    1990: Quark structure inside protons and neutrons
    1995: The tau lepton

    SLAC’s meeting facilities also provided a venue for the Homebrew Computer Club and other pioneers of the home computer revolution of the late 1970s and early 1980s.

    In 1984 the laboratory was named an ASME National Historic Engineering Landmark and an IEEE Milestone.

    SLAC developed and, in December 1991, began hosting the first World Wide Web server outside of Europe.

    In the early-to-mid 1990s, the Stanford Linear Collider (SLC) investigated the properties of the Z boson using the Stanford Large Detector.

    As of 2005, SLAC employed over 1,000 people, some 150 of whom were physicists with doctorate degrees, and served over 3,000 visiting researchers yearly, operating particle accelerators for high-energy physics and the Stanford Synchrotron Radiation Laboratory (SSRL) for synchrotron light radiation research, which was “indispensable” in the research leading to the 2006 Nobel Prize in Chemistry awarded to Stanford Professor Roger D. Kornberg.

    In October 2008, the Department of Energy announced that the center’s name would be changed to SLAC National Accelerator Laboratory. The reasons given include a better representation of the new direction of the lab and the ability to trademark the laboratory’s name. Stanford University had legally opposed the Department of Energy’s attempt to trademark “Stanford Linear Accelerator Center”.

    In March 2009, it was announced that the SLAC National Accelerator Laboratory was to receive $68.3 million in Recovery Act Funding to be disbursed by Department of Energy’s Office of Science.

    In October 2016, Bits and Watts launched as a collaboration between SLAC and Stanford University to design “better, greener electric grids”. SLAC later pulled out over concerns about an industry partner, the state-owned Chinese electric utility.

    Accelerator

    The main accelerator was an RF linear accelerator that accelerated electrons and positrons up to 50 GeV. At 3.2 km (2.0 mi) long, the accelerator was the longest linear accelerator in the world, and was claimed to be “the world’s most straight object.” until 2017 when the European x-ray free electron laser opened. The main accelerator is buried 9 m (30 ft) below ground and passes underneath Interstate Highway 280. The above-ground klystron gallery atop the beamline, was the longest building in the United States until the LIGO project’s twin interferometers were completed in 1999. It is easily distinguishable from the air and is marked as a visual waypoint on aeronautical charts.

    A portion of the original linear accelerator is now part of the Linac Coherent Light Source [below].

    Stanford Linear Collider

    The Stanford Linear Collider was a linear accelerator that collided electrons and positrons at SLAC. The center of mass energy was about 90 GeV, equal to the mass of the Z boson, which the accelerator was designed to study. Grad student Barrett D. Milliken discovered the first Z event on 12 April 1989 while poring over the previous day’s computer data from the Mark II detector. The bulk of the data was collected by the SLAC Large Detector, which came online in 1991. Although largely overshadowed by the Large Electron–Positron Collider at CERN, which began running in 1989, the highly polarized electron beam at SLC (close to 80%) made certain unique measurements possible, such as parity violation in Z Boson-b quark coupling.

    Presently no beam enters the south and north arcs in the machine, which leads to the Final Focus, therefore this section is mothballed to run beam into the PEP2 section from the beam switchyard.

    The SLAC Large Detector (SLD) was the main detector for the Stanford Linear Collider. It was designed primarily to detect Z bosons produced by the accelerator’s electron-positron collisions. Built in 1991, the SLD operated from 1992 to 1998.

    SLAC National Accelerator Laboratory Large Detector

    PEP

    PEP (Positron-Electron Project) began operation in 1980, with center-of-mass energies up to 29 GeV. At its apex, PEP had five large particle detectors in operation, as well as a sixth smaller detector. About 300 researchers made used of PEP. PEP stopped operating in 1990, and PEP-II began construction in 1994.

    PEP-II

    From 1999 to 2008, the main purpose of the linear accelerator was to inject electrons and positrons into the PEP-II accelerator, an electron-positron collider with a pair of storage rings 2.2 km (1.4 mi) in circumference. PEP-II was host to the BaBar experiment, one of the so-called B-Factory experiments studying charge-parity symmetry.

    SLAC National Accelerator Laboratory BaBar

    Fermi Gamma-ray Space Telescope

    SLAC plays a primary role in the mission and operation of the Fermi Gamma-ray Space Telescope, launched in August 2008. The principal scientific objectives of this mission are:

    To understand the mechanisms of particle acceleration in AGNs, pulsars, and SNRs.
    To resolve the gamma-ray sky: unidentified sources and diffuse emission.
    To determine the high-energy behavior of gamma-ray bursts and transients.
    To probe dark matter and fundamental physics.


    KIPAC

    The Stanford PULSE Institute (PULSE) is a Stanford Independent Laboratory located in the Central Laboratory at SLAC. PULSE was created by Stanford in 2005 to help Stanford faculty and SLAC scientists develop ultrafast x-ray research at LCLS.

    The Linac Coherent Light Source (LCLS)[below] is a free electron laser facility located at SLAC. The LCLS is partially a reconstruction of the last 1/3 of the original linear accelerator at SLAC, and can deliver extremely intense x-ray radiation for research in a number of areas. It achieved first lasing in April 2009.

    The laser produces hard X-rays, 10^9 times the relative brightness of traditional synchrotron sources and is the most powerful x-ray source in the world. LCLS enables a variety of new experiments and provides enhancements for existing experimental methods. Often, x-rays are used to take “snapshots” of objects at the atomic level before obliterating samples. The laser’s wavelength, ranging from 6.2 to 0.13 nm (200 to 9500 electron volts (eV)) is similar to the width of an atom, providing extremely detailed information that was previously unattainable. Additionally, the laser is capable of capturing images with a “shutter speed” measured in femtoseconds, or million-billionths of a second, necessary because the intensity of the beam is often high enough so that the sample explodes on the femtosecond timescale.

    The LCLS-II [below] project is to provide a major upgrade to LCLS by adding two new X-ray laser beams. The new system will utilize the 500 m (1,600 ft) of existing tunnel to add a new superconducting accelerator at 4 GeV and two new sets of undulators that will increase the available energy range of LCLS. The advancement from the discoveries using this new capabilities may include new drugs, next-generation computers, and new materials.

    FACET

    In 2012, the first two-thirds (~2 km) of the original SLAC LINAC were recommissioned for a new user facility, the Facility for Advanced Accelerator Experimental Tests (FACET). This facility was capable of delivering 20 GeV, 3 nC electron (and positron) beams with short bunch lengths and small spot sizes, ideal for beam-driven plasma acceleration studies. The facility ended operations in 2016 for the constructions of LCLS-II which will occupy the first third of the SLAC LINAC. The FACET-II project will re-establish electron and positron beams in the middle third of the LINAC for the continuation of beam-driven plasma acceleration studies in 2019.

    The Next Linear Collider Test Accelerator (NLCTA) is a 60-120 MeV high-brightness electron beam linear accelerator used for experiments on advanced beam manipulation and acceleration techniques. It is located at SLAC’s end station B

    SSRL and LCLS are DOE Office of Science user facilities.

    Stanford University

    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members.

    Stanford University, officially Leland Stanford Junior University, is a private research university located in Stanford, California. Stanford was founded in 1885 by Leland and Jane Stanford in memory of their only child, Leland Stanford Jr., who had died of typhoid fever at age 15 the previous year. Stanford is consistently ranked as among the most prestigious and top universities in the world by major education publications. It is also one of the top fundraising institutions in the country, becoming the first school to raise more than a billion dollars in a year.

    Leland Stanford was a U.S. senator and former governor of California who made his fortune as a railroad tycoon. The school admitted its first students on October 1, 1891, as a coeducational and non-denominational institution. Stanford University struggled financially after the death of Leland Stanford in 1893 and again after much of the campus was damaged by the 1906 San Francisco earthquake. Following World War II, provost Frederick Terman supported faculty and graduates’ entrepreneurialism to build self-sufficient local industry in what would later be known as Silicon Valley.

    The university is organized around seven schools: three schools consisting of 40 academic departments at the undergraduate level as well as four professional schools that focus on graduate programs in law, medicine, education, and business. All schools are on the same campus. Students compete in 36 varsity sports, and the university is one of two private institutions in the Division I FBS Pac-12 Conference. It has gained 126 NCAA team championships, and Stanford has won the NACDA Directors’ Cup for 24 consecutive years, beginning in 1994–1995. In addition, Stanford students and alumni have won 270 Olympic medals including 139 gold medals.

    As of October 2020, 84 Nobel laureates, 28 Turing Award laureates, and eight Fields Medalists have been affiliated with Stanford as students, alumni, faculty, or staff. In addition, Stanford is particularly noted for its entrepreneurship and is one of the most successful universities in attracting funding for start-ups. Stanford alumni have founded numerous companies, which combined produce more than $2.7 trillion in annual revenue, roughly equivalent to the 7th largest economy in the world (as of 2020). Stanford is the alma mater of one president of the United States (Herbert Hoover), 74 living billionaires, and 17 astronauts. It is also one of the leading producers of Fulbright Scholars, Marshall Scholars, Rhodes Scholars, and members of the United States Congress.

    Stanford University was founded in 1885 by Leland and Jane Stanford, dedicated to Leland Stanford Jr, their only child. The institution opened in 1891 on Stanford’s previous Palo Alto farm.

    Jane and Leland Stanford modeled their university after the great eastern universities, most specifically Cornell University. Stanford opened being called the “Cornell of the West” in 1891 due to faculty being former Cornell affiliates (either professors, alumni, or both) including its first president, David Starr Jordan, and second president, John Casper Branner. Both Cornell and Stanford were among the first to have higher education be accessible, nonsectarian, and open to women as well as to men. Cornell is credited as one of the first American universities to adopt this radical departure from traditional education, and Stanford became an early adopter as well.

    Despite being impacted by earthquakes in both 1906 and 1989, the campus was rebuilt each time. In 1919, The Hoover Institution on War, Revolution and Peace was started by Herbert Hoover to preserve artifacts related to World War I. The Stanford Medical Center, completed in 1959, is a teaching hospital with over 800 beds. The DOE’s SLAC National Accelerator Laboratory(originally named the Stanford Linear Accelerator Center), established in 1962, performs research in particle physics.

    Land

    Most of Stanford is on an 8,180-acre (12.8 sq mi; 33.1 km^2) campus, one of the largest in the United States. It is located on the San Francisco Peninsula, in the northwest part of the Santa Clara Valley (Silicon Valley) approximately 37 miles (60 km) southeast of San Francisco and approximately 20 miles (30 km) northwest of San Jose. In 2008, 60% of this land remained undeveloped.

    Stanford’s main campus includes a census-designated place within unincorporated Santa Clara County, although some of the university land (such as the Stanford Shopping Center and the Stanford Research Park) is within the city limits of Palo Alto. The campus also includes much land in unincorporated San Mateo County (including the SLAC National Accelerator Laboratory and the Jasper Ridge Biological Preserve), as well as in the city limits of Menlo Park (Stanford Hills neighborhood), Woodside, and Portola Valley.

    Non-central campus

    Stanford currently operates in various locations outside of its central campus.

    On the founding grant:

    Jasper Ridge Biological Preserve is a 1,200-acre (490 ha) natural reserve south of the central campus owned by the university and used by wildlife biologists for research.
    SLAC National Accelerator Laboratory is a facility west of the central campus operated by the university for the Department of Energy. It contains the longest linear particle accelerator in the world, 2 miles (3.2 km) on 426 acres (172 ha) of land.
    Golf course and a seasonal lake: The university also has its own golf course and a seasonal lake (Lake Lagunita, actually an irrigation reservoir), both home to the vulnerable California tiger salamander. As of 2012 Lake Lagunita was often dry and the university had no plans to artificially fill it.

    Off the founding grant:

    Hopkins Marine Station, in Pacific Grove, California, is a marine biology research center owned by the university since 1892.
    Study abroad locations: unlike typical study abroad programs, Stanford itself operates in several locations around the world; thus, each location has Stanford faculty-in-residence and staff in addition to students, creating a “mini-Stanford”.

    Redwood City campus for many of the university’s administrative offices located in Redwood City, California, a few miles north of the main campus. In 2005, the university purchased a small, 35-acre (14 ha) campus in Midpoint Technology Park intended for staff offices; development was delayed by The Great Recession. In 2015 the university announced a development plan and the Redwood City campus opened in March 2019.

    The Bass Center in Washington, DC provides a base, including housing, for the Stanford in Washington program for undergraduates. It includes a small art gallery open to the public.

    China: Stanford Center at Peking University, housed in the Lee Jung Sen Building, is a small center for researchers and students in collaboration with Beijing University [北京大学](CN) (Kavli Institute for Astronomy and Astrophysics at Peking University(CN) (KIAA-PKU).

    Administration and organization

    Stanford is a private, non-profit university that is administered as a corporate trust governed by a privately appointed board of trustees with a maximum membership of 38. Trustees serve five-year terms (not more than two consecutive terms) and meet five times annually.[83] A new trustee is chosen by the current trustees by ballot. The Stanford trustees also oversee the Stanford Research Park, the Stanford Shopping Center, the Cantor Center for Visual Arts, Stanford University Medical Center, and many associated medical facilities (including the Lucile Packard Children’s Hospital).

    The board appoints a president to serve as the chief executive officer of the university, to prescribe the duties of professors and course of study, to manage financial and business affairs, and to appoint nine vice presidents. The provost is the chief academic and budget officer, to whom the deans of each of the seven schools report. Persis Drell became the 13th provost in February 2017.

    As of 2018, the university was organized into seven academic schools. The schools of Humanities and Sciences (27 departments), Engineering (nine departments), and Earth, Energy & Environmental Sciences (four departments) have both graduate and undergraduate programs while the Schools of Law, Medicine, Education and Business have graduate programs only. The powers and authority of the faculty are vested in the Academic Council, which is made up of tenure and non-tenure line faculty, research faculty, senior fellows in some policy centers and institutes, the president of the university, and some other academic administrators, but most matters are handled by the Faculty Senate, made up of 55 elected representatives of the faculty.

    The Associated Students of Stanford University (ASSU) is the student government for Stanford and all registered students are members. Its elected leadership consists of the Undergraduate Senate elected by the undergraduate students, the Graduate Student Council elected by the graduate students, and the President and Vice President elected as a ticket by the entire student body.

    Stanford is the beneficiary of a special clause in the California Constitution, which explicitly exempts Stanford property from taxation so long as the property is used for educational purposes.

    Endowment and donations

    The university’s endowment, managed by the Stanford Management Company, was valued at $27.7 billion as of August 31, 2019. Payouts from the Stanford endowment covered approximately 21.8% of university expenses in the 2019 fiscal year. In the 2018 NACUBO-TIAA survey of colleges and universities in the United States and Canada, only Harvard University, the University of Texas System, and Yale University had larger endowments than Stanford.

    In 2006, President John L. Hennessy launched a five-year campaign called the Stanford Challenge, which reached its $4.3 billion fundraising goal in 2009, two years ahead of time, but continued fundraising for the duration of the campaign. It concluded on December 31, 2011, having raised a total of $6.23 billion and breaking the previous campaign fundraising record of $3.88 billion held by Yale. Specifically, the campaign raised $253.7 million for undergraduate financial aid, as well as $2.33 billion for its initiative in “Seeking Solutions” to global problems, $1.61 billion for “Educating Leaders” by improving K-12 education, and $2.11 billion for “Foundation of Excellence” aimed at providing academic support for Stanford students and faculty. Funds supported 366 new fellowships for graduate students, 139 new endowed chairs for faculty, and 38 new or renovated buildings. The new funding also enabled the construction of a facility for stem cell research; a new campus for the business school; an expansion of the law school; a new Engineering Quad; a new art and art history building; an on-campus concert hall; a new art museum; and a planned expansion of the medical school, among other things. In 2012, the university raised $1.035 billion, becoming the first school to raise more than a billion dollars in a year.

    Research centers and institutes

    DOE’s SLAC National Accelerator Laboratory
    Stanford Research Institute, a center of innovation to support economic development in the region.
    Hoover Institution, a conservative American public policy institution and research institution that promotes personal and economic liberty, free enterprise, and limited government.
    Hasso Plattner Institute of Design, a multidisciplinary design school in cooperation with the Hasso Plattner Institute of University of Potsdam [Universität Potsdam](DE) that integrates product design, engineering, and business management education).
    Martin Luther King Jr. Research and Education Institute, which grew out of and still contains the Martin Luther King Jr. Papers Project.
    John S. Knight Fellowship for Professional Journalists
    Center for Ocean Solutions
    Together with The University of California- Berkeley and UC San Francisco, Stanford is part of the Biohub, a new medical science research center founded in 2016 by a $600 million commitment from Facebook CEO and founder Mark Zuckerberg and pediatrician Priscilla Chan.

    Discoveries and innovation

    Natural sciences

    Biological synthesis of deoxyribonucleic acid (DNA) – Arthur Kornberg synthesized DNA material and won the Nobel Prize in Physiology or Medicine 1959 for his work at Stanford.
    First Transgenic organism – Stanley Cohen and Herbert Boyer were the first scientists to transplant genes from one living organism to another, a fundamental discovery for genetic engineering. Thousands of products have been developed on the basis of their work, including human growth hormone and hepatitis B vaccine.
    Laser – Arthur Leonard Schawlow shared the 1981 Nobel Prize in Physics with Nicolaas Bloembergen and Kai Siegbahn for his work on lasers.
    Nuclear magnetic resonance – Felix Bloch developed new methods for nuclear magnetic precision measurements, which are the underlying principles of the MRI.

    Computer and applied sciences

    ARPANETStanford Research Institute, formerly part of Stanford but on a separate campus, was the site of one of the four original ARPANET nodes.

    Internet—Stanford was the site where the original design of the Internet was undertaken. Vint Cerf led a research group to elaborate the design of the Transmission Control Protocol (TCP/IP) that he originally co-created with Robert E. Kahn (Bob Kahn) in 1973 and which formed the basis for the architecture of the Internet.

    Frequency modulation synthesis – John Chowning of the Music department invented the FM music synthesis algorithm in 1967, and Stanford later licensed it to Yamaha Corporation.

    Google – Google began in January 1996 as a research project by Larry Page and Sergey Brin when they were both PhD students at Stanford. They were working on the Stanford Digital Library Project (SDLP). The SDLP’s goal was “to develop the enabling technologies for a single, integrated and universal digital library” and it was funded through the National Science Foundation, among other federal agencies.

    Klystron tube – invented by the brothers Russell and Sigurd Varian at Stanford. Their prototype was completed and demonstrated successfully on August 30, 1937. Upon publication in 1939, news of the klystron immediately influenced the work of U.S. and UK researchers working on radar equipment.

    RISCARPA funded VLSI project of microprocessor design. Stanford and UC Berkeley are most associated with the popularization of this concept. The Stanford MIPS would go on to be commercialized as the successful MIPS architecture, while Berkeley RISC gave its name to the entire concept, commercialized as the SPARC. Another success from this era were IBM’s efforts that eventually led to the IBM POWER instruction set architecture, PowerPC, and Power ISA. As these projects matured, a wide variety of similar designs flourished in the late 1980s and especially the early 1990s, representing a major force in the Unix workstation market as well as embedded processors in laser printers, routers and similar products.
    SUN workstation – Andy Bechtolsheim designed the SUN workstation for the Stanford University Network communications project as a personal CAD workstation, which led to Sun Microsystems.

    Businesses and entrepreneurship

    Stanford is one of the most successful universities in creating companies and licensing its inventions to existing companies; it is often held up as a model for technology transfer. Stanford’s Office of Technology Licensing is responsible for commercializing university research, intellectual property, and university-developed projects.

    The university is described as having a strong venture culture in which students are encouraged, and often funded, to launch their own companies.

    Companies founded by Stanford alumni generate more than $2.7 trillion in annual revenue, equivalent to the 10th-largest economy in the world.

    Some companies closely associated with Stanford and their connections include:

    Hewlett-Packard, 1939, co-founders William R. Hewlett (B.S, PhD) and David Packard (M.S).
    Silicon Graphics, 1981, co-founders James H. Clark (Associate Professor) and several of his grad students.
    Sun Microsystems, 1982, co-founders Vinod Khosla (M.B.A), Andy Bechtolsheim (PhD) and Scott McNealy (M.B.A).
    Cisco, 1984, founders Leonard Bosack (M.S) and Sandy Lerner (M.S) who were in charge of Stanford Computer Science and Graduate School of Business computer operations groups respectively when the hardware was developed.[163]
    Yahoo!, 1994, co-founders Jerry Yang (B.S, M.S) and David Filo (M.S).
    Google, 1998, co-founders Larry Page (M.S) and Sergey Brin (M.S).
    LinkedIn, 2002, co-founders Reid Hoffman (B.S), Konstantin Guericke (B.S, M.S), Eric Lee (B.S), and Alan Liu (B.S).
    Instagram, 2010, co-founders Kevin Systrom (B.S) and Mike Krieger (B.S).
    Snapchat, 2011, co-founders Evan Spiegel and Bobby Murphy (B.S).
    Coursera, 2012, co-founders Andrew Ng (Associate Professor) and Daphne Koller (Professor, PhD).

    Student body

    Stanford enrolled 6,996 undergraduate and 10,253 graduate students as of the 2019–2020 school year. Women comprised 50.4% of undergraduates and 41.5% of graduate students. In the same academic year, the freshman retention rate was 99%.

    Stanford awarded 1,819 undergraduate degrees, 2,393 master’s degrees, 770 doctoral degrees, and 3270 professional degrees in the 2018–2019 school year. The four-year graduation rate for the class of 2017 cohort was 72.9%, and the six-year rate was 94.4%. The relatively low four-year graduation rate is a function of the university’s coterminal degree (or “coterm”) program, which allows students to earn a master’s degree as a 1-to-2-year extension of their undergraduate program.

    As of 2010, fifteen percent of undergraduates were first-generation students.

    Athletics

    As of 2016 Stanford had 16 male varsity sports and 20 female varsity sports, 19 club sports and about 27 intramural sports. In 1930, following a unanimous vote by the Executive Committee for the Associated Students, the athletic department adopted the mascot “Indian.” The Indian symbol and name were dropped by President Richard Lyman in 1972, after objections from Native American students and a vote by the student senate. The sports teams are now officially referred to as the “Stanford Cardinal,” referring to the deep red color, not the cardinal bird. Stanford is a member of the Pac-12 Conference in most sports, the Mountain Pacific Sports Federation in several other sports, and the America East Conference in field hockey with the participation in the inter-collegiate NCAA’s Division I FBS.

    Its traditional sports rival is The University of California-Berkeley, the neighbor to the north in the East Bay. The winner of the annual “Big Game” between the Cal and Cardinal football teams gains custody of the Stanford Axe.

    Stanford has had at least one NCAA team champion every year since the 1976–77 school year and has earned 126 NCAA national team titles since its establishment, the most among universities, and Stanford has won 522 individual national championships, the most by any university. Stanford has won the award for the top-ranked Division 1 athletic program—the NACDA Directors’ Cup, formerly known as the Sears Cup—annually for the past twenty-four straight years. Stanford athletes have won medals in every Olympic Games since 1912, winning 270 Olympic medals total, 139 of them gold. In the 2008 Summer Olympics, and 2016 Summer Olympics, Stanford won more Olympic medals than any other university in the United States. Stanford athletes won 16 medals at the 2012 Summer Olympics (12 gold, two silver and two bronze), and 27 medals at the 2016 Summer Olympics.

    Traditions

    The unofficial motto of Stanford, selected by President Jordan, is Die Luft der Freiheit weht. Translated from the German language, this quotation from Ulrich von Hutten means, “The wind of freedom blows.” The motto was controversial during World War I, when anything in German was suspect; at that time the university disavowed that this motto was official.
    Hail, Stanford, Hail! is the Stanford Hymn sometimes sung at ceremonies or adapted by the various University singing groups. It was written in 1892 by mechanical engineering professor Albert W. Smith and his wife, Mary Roberts Smith (in 1896 she earned the first Stanford doctorate in Economics and later became associate professor of Sociology), but was not officially adopted until after a performance on campus in March 1902 by the Mormon Tabernacle Choir.
    “Uncommon Man/Uncommon Woman”: Stanford does not award honorary degrees, but in 1953 the degree of “Uncommon Man/Uncommon Woman” was created to recognize individuals who give rare and extraordinary service to the University. Technically, this degree is awarded by the Stanford Associates, a voluntary group that is part of the university’s alumni association. As Stanford’s highest honor, it is not conferred at prescribed intervals, but only when appropriate to recognize extraordinary service. Recipients include Herbert Hoover, Bill Hewlett, Dave Packard, Lucile Packard, and John Gardner.
    Big Game events: The events in the week leading up to the Big Game vs. UC Berkeley, including Gaieties (a musical written, composed, produced, and performed by the students of Ram’s Head Theatrical Society).
    “Viennese Ball”: a formal ball with waltzes that was initially started in the 1970s by students returning from the now-closed Stanford in Vienna overseas program. It is now open to all students.
    “Full Moon on the Quad”: An annual event at Main Quad, where students gather to kiss one another starting at midnight. Typically organized by the Junior class cabinet, the festivities include live entertainment, such as music and dance performances.
    “Band Run”: An annual festivity at the beginning of the school year, where the band picks up freshmen from dorms across campus while stopping to perform at each location, culminating in a finale performance at Main Quad.
    “Mausoleum Party”: An annual Halloween Party at the Stanford Mausoleum, the final resting place of Leland Stanford Jr. and his parents. A 20-year tradition, the “Mausoleum Party” was on hiatus from 2002 to 2005 due to a lack of funding, but was revived in 2006. In 2008, it was hosted in Old Union rather than at the actual Mausoleum, because rain prohibited generators from being rented. In 2009, after fundraising efforts by the Junior Class Presidents and the ASSU Executive, the event was able to return to the Mausoleum despite facing budget cuts earlier in the year.
    Former campus traditions include the “Big Game bonfire” on Lake Lagunita (a seasonal lake usually dry in the fall), which was formally ended in 1997 because of the presence of endangered salamanders in the lake bed.

    Award laureates and scholars

    Stanford’s current community of scholars includes:

    19 Nobel Prize laureates (as of October 2020, 85 affiliates in total)
    171 members of the National Academy of Sciences
    109 members of National Academy of Engineering
    76 members of National Academy of Medicine
    288 members of the American Academy of Arts and Sciences
    19 recipients of the National Medal of Science
    1 recipient of the National Medal of Technology
    4 recipients of the National Humanities Medal
    49 members of American Philosophical Society
    56 fellows of the American Physics Society (since 1995)
    4 Pulitzer Prize winners
    31 MacArthur Fellows
    4 Wolf Foundation Prize winners
    2 ACL Lifetime Achievement Award winners
    14 AAAI fellows
    2 Presidential Medal of Freedom winners

    Stanford University Seal

     
  • richardmitnick 9:34 am on February 3, 2021 Permalink | Reply
    Tags: "A new hands-off probe uses light to explore the subtleties of electron behavior in a topological insulator", , DOE’s SLAC National Accelerator Laboratory, HHG-high harmonic generation, , ,   

    From DOE’s SLAC National Accelerator Laboratory and : “A new hands-off probe uses light to explore the subtleties of electron behavior in a topological insulator” 

    From DOE’s SLAC National Accelerator Laboratory

    and

    Stanford University Name

    From Stanford University

    February 2, 2021
    Glennda Chui

    Just as pressing a guitar string produces a higher pitch, sending laser light through a material can shift it to higher energies and higher frequencies. Now scientists have discovered how to use this phenomenon to explore quantum materials in a new and much more detailed way.

    1
    Researchers at SLAC National Accelerator Laboratory and Stanford University discovered that focusing intense, circularly polarized laser light on a topological insulator generates harmonics that can be used to probe electron behavior in the material’s topological surface, a sort of electron superhighway where electrons flow with no loss. The technique should be applicable to a wide range of quantum materials. Credit: Greg Stewart/SLAC.

    2
    Laser light is usually linearly polarized, meaning that its waves oscillate in only one direction – up and down, in the example at left. But it can also be circularly polarized, at right, so its waves spiral like a corkscrew around the direction the light is traveling. A new study from SLAC and Stanford predicts that this circularly polarized light can be used to explore quantum materials in ways that were not possible before. Cedit: Greg Stewart/SLAC.

    Topological insulators are one of the most puzzling quantum materials – a class of materials whose electrons cooperate in surprising ways to produce unexpected properties. The edges of a TI are electron superhighways where electrons flow with no loss, ignoring any impurities or other obstacles in their path, while the bulk of the material blocks electron flow.

    Scientists have studied these puzzling materials since their discovery just over a decade ago with an eye to harnessing them for things like quantum computing and information processing.

    Now researchers at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have invented a new, hands-off way to probe the fastest and most ephemeral phenomena within a TI and clearly distinguish what its electrons are doing on the superhighway edges from what they’re doing everywhere else.

    The technique takes advantage of a phenomenon called high harmonic generation, or HHG, which shifts laser light to higher energies and higher frequencies – much like pressing a guitar string produces a higher note – by shining it through a material. ­­By varying the polarization of laser light going into a TI and analyzing the shifted light coming out, researchers got strong and separate signals that told them what was happening in each of the material’s two contrasting domains.

    “What we found out is that the light coming out gives us information about the properties of the superhighway surfaces,” said Shambhu Ghimire, a principal investigator with the Stanford PULSE Institute at SLAC, where the work was carried out.

    “This signal is quite remarkable, and its dependence on the polarization of the laser light is dramatically different from what we see in conventional materials. We think we have a potentially novel approach for initiating and probing quantum behaviors that are supposed to be present in a broad range of quantum materials.”

    The research team reported the results today in Physical Review A.

    Light in, light out

    Starting in 2010, a series of experiments led by Ghimire and PULSE Director David Reis showed HHG can be produced in ways that were previously thought unlikely or even impossible: by beaming laser light into a crystal, a frozen argon gas or an atomically thin semiconductor material. Another study described how to use HHG to generate attosecond laser pulses, which can be used to observe and control the movements of electrons, by shining a laser through ordinary glass.

    In 2018, Denitsa Baykusheva, a Swiss National Science Foundation Fellow with a background in HHG research, joined the PULSE group as a postdoctoral researcher. Her goal was to study the potential for generating HHG in topological insulators – the first such study in a quantum material. “We wanted to see what happens to the intense laser pulse used to generate HHG,” she said. “No one had actually focused such a strong laser light on these materials before.”

    But midway through those experiments, the COVID-19 pandemic hit and the lab shut down in March 2020 for all but essential research. So the team had to think of other ways to make progress, Baykusheva said.

    “In a new area of research like this one, theory and experiment have to go hand in hand,” she explained. “Theory is essential for explaining experimental results and also predicting the most promising avenues for future experiments. So we all turned ourselves into theorists” – first working with pen and paper and then writing code and doing calculations to feed into computer models.

    An illuminating result

    To their surprise, the results predicted that circularly polarized laser light, whose waves spiral around the beam like a corkscrew, could be used to trigger HHG in topological insulators [above].

    “One of the interesting things we observed is that circularly polarized laser light is very efficient at generating harmonics from the superhighway surfaces of the topological insulator, but not from the rest of it,” Baykusheva said. “This is something very unique and specific to this type of material. It can be used to get information about electrons that travel the superhighways and those that don’t, and it can also be used to explore other types of materials that can’t be probed with linearly polarized light.”

    The results lay out a recipe for continuing to explore HHG in quantum materials, said Reis, who is a co-author of the study.

    “It’s remarkable that a technique that generates strong and potentially disruptive fields, which takes electrons in the material and jostles them around and uses them to probe the properties of the material itself, can give you such a clear and robust signal about the material’s topological states,” he said.

    “The fact that we can see anything at all is amazing, not to mention the fact that we could potentially use that same light to change the material’s topological properties.”

    Experiments at SLAC have resumed on a limited basis, Reis added, and the results of the theoretical work have given the team new confidence that they know exactly what they are looking for.

    Researchers from the Max Planck POSTECH/KOREA Research Initiative also contributed to this report. Major funding for the study came from the DOE Office of Science and the Swiss National Science Foundation.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Stanford University campus. No image credit

    Stanford University

    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

    Stanford University Seal

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

    SLAC National Accelerator Lab


    SLAC/LCLS


    SLAC/LCLS II projected view

    SLAC LCLS-II Undulators The Linac Coherent Light Source’s new undulators each use an intricately tuned series of magnets to convert electron energy into intense bursts of X-rays. The “soft” X-ray undulator stretches for 100 meters on the left side of this hall, with the “hard” x-ray undulator on the right. Credit: Alberto Gamazo/SLAC National Accelerator Laboratory.

    SSRL and LCLS are DOE Office of Science user facilities.

    3

     
  • richardmitnick 1:41 pm on February 1, 2021 Permalink | Reply
    Tags: "Squeezing a rock-star material could make it stable enough for solar cells", A promising lead halide perovskite is great at converting sunlight to electricity but it breaks down at room temperature., , , DOE’s SLAC National Accelerator Laboratory, Now scientists have discovered how to stabilize the lead halide perovskite with pressure from a diamond anvil cell., , , Simply place the useless version of the material in a diamond anvil cell and squeeze it at high temperature., , This is the first study to use pressure to control this stability and it really opens up a lot of possibilities.   

    From DOE’s SLAC National Accelerator Laboratory and Stanford University: “Squeezing a rock-star material could make it stable enough for solar cells” 

    From DOE’s SLAC National Accelerator Laboratory

    and

    Stanford University Name

    Stanford University

    January 21, 2021 [Just now in social media.]
    By Glennda Chui

    A promising lead halide perovskite is great at converting sunlight to electricity, but it breaks down at room temperature. Now scientists have discovered how to stabilize it with pressure from a diamond anvil cell.

    1
    Scientists at SLAC National Accelerator Laboratory and Stanford University discovered that squeezing a promising lead halide material in a diamond anvil cell (left) produces a so-called “black perovskite” (right) that’s stable enough for solar power applications.
    Credit: Greg Stewart/ SLAC National Accelerator Laboratory.

    Among the materials known as perovskites, one of the most exciting is a material that can convert sunlight to electricity as efficiently as today’s commercial silicon solar cells and has the potential for being much cheaper and easier to manufacture.

    There’s just one problem: Of the four possible atomic configurations, or phases, this material can take, three are efficient but unstable at room temperature and in ordinary environments, and they quickly revert to the fourth phase, which is completely useless for solar applications.

    Now scientists at Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory have found a novel solution: Simply place the useless version of the material in a diamond anvil cell and squeeze it at high temperature. This treatment nudges its atomic structure into an efficient configuration and keeps it that way, even at room temperature and in relatively moist air.

    The researchers described their results in Nature Communications.

    “This is the first study to use pressure to control this stability, and it really opens up a lot of possibilities,” said Yu Lin, a SLAC staff scientist and investigator with the Stanford Institute for Materials and Energy Sciences (SIMES).

    “Now that we’ve found this optimal way to prepare the material,” she said, “there’s potential for scaling it up for industrial production, and for using this same approach to manipulate other perovskite phases.”

    A search for stability

    Perovskites get their name from a natural mineral with the same atomic structure. In this case the scientists studied a lead halide perovskite that’s a combination of iodine, lead and cesium.

    One phase of this material, known as the yellow phase, does not have a true perovskite structure and can’t be used in solar cells. However, scientists discovered a while back that if you process it in certain ways, it changes to a black perovskite phase that’s extremely efficient at converting sunlight to electricity. “This has made it highly sought after and the focus of a lot of research,” said Stanford Professor and study co-author Wendy Mao.

    Unfortunately, these black phases are also structurally unstable and tend to quickly slump back into the useless configuration. Plus, they only operate with high efficiency at high temperatures, Mao said, and researchers will have to overcome both of those problems before they can be used in practical devices.

    There had been previous attempts to stabilize the black phases with chemistry, strain or temperature, but only in a moisture-free environment that doesn’t reflect the real-world conditions that solar cells operate in. This study combined both pressure and temperature in a more realistic working environment.

    Pressure and heat do the trick

    Working with colleagues in the Stanford research groups of Mao and Professor Hemamala Karunadasa, Lin and postdoctoral researcher Feng Ke designed a setup where yellow phase crystals were squeezed between the tips of diamonds in what’s known as a diamond anvil cell. With the pressure still on, the crystals were heated to 450 degrees Celsius and then cooled down.

    Under the right combination of pressure and temperature, the crystals turned from yellow to black and stayed in the black phase after the pressure was released, the scientists said. They were resistant to deterioration from moist air and remained stable and efficient at room temperature for 10 to 30 days or more.

    Examination with X-rays and other techniques confirmed the shift in the material’s crystal structure, and calculations by SIMES theorists Chunjing Jia and Thomas Devereaux provided insight into how the pressure changed the structure and preserved the black phase.

    The pressure needed to turn the crystals black and keep them that way was roughly 1,000 to 6,000 times atmospheric pressure, Lin said ­– about a tenth of the pressures routinely used in the synthetic diamond industry. So one of the goals for further research will be to transfer what the researchers have learned from their diamond anvil cell experiments to industry and scale up the process to bring it within the realm of manufacturing.

    Wendy Mao and Hemamala Karunadasa are also SIMES investigators. Parts of this work were performed at the Advanced Photon Source at Argonne National Laboratory and the Advanced Light Source at Lawrence Berkeley National Laboratory. It also used resources of the National Energy Research Scientific Computing Center (NERSC). All three are DOE Office of Science user facilities. Major funding came from the DOE Office of Science.

    ANL Advanced Photon Source.

    LBNL ALS .

    National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory

    NERSC Cray Cori II supercomputer, named after Gerty Cori, the first American woman to win a Nobel Prize in science.

    NERSC Hopper Cray XE6 supercomputer, named after Grace Hopper, One of the first programmers of the Harvard Mark I computer.

    NERSC Cray XC30 Edison supercomputer.

    NERSC GPFS for Life Sciences.


    The Genepool system is a cluster dedicated to the DOE Joint Genome Institute’s computing needs. Denovo is a smaller test system for Genepool that is primarily used by NERSC staff to test new system configurations and software.

    NERSC PDSF computer cluster in 2003.

    PDSF is a networked distributed computing cluster designed primarily to meet the detector simulation and data analysis requirements of physics, astrophysics and nuclear science collaborations.

    Future:

    Cray Shasta Perlmutter SC18 AMD Epyc Nvidia pre-exascale supeercomputer

    NERSC is a DOE Office of Science User Facility.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Stanford University campus. No image credit

    Stanford University

    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

    Stanford University Seal

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

    SLAC National Accelerator Lab


    SLAC/LCLS


    SLAC/LCLS II projected view

    SLAC LCLS-II Undulators The Linac Coherent Light Source’s new undulators each use an intricately tuned series of magnets to convert electron energy into intense bursts of X-rays. The “soft” X-ray undulator stretches for 100 meters on the left side of this hall, with the “hard” x-ray undulator on the right. Credit: Alberto Gamazo/SLAC National Accelerator Laboratory.

    SSRL and LCLS are DOE Office of Science user facilities.

     
  • richardmitnick 1:13 pm on February 1, 2021 Permalink | Reply
    Tags: "Study shows tweaking one layer of atoms on a catalyst’s surface can make it work better", , Building materials one atomic layer at a time., , Catalysts help molecules react without being consumed in the reaction so they can be used over and over., DOE’s SLAC National Accelerator Laboratory, , , Scientists crafting a nickel-based catalyst used in making hydrogen fuel built it one atomic layer at a time to gain full control over its chemical properties., Splitting water to make hydrogen fuel., Tuning a catalyst’s surface for better performance.   

    From DOE’s SLAC National Accelerator Laboratory: “Study shows tweaking one layer of atoms on a catalyst’s surface can make it work better” 

    From DOE’s SLAC National Accelerator Laboratory

    January 11, 2021 [Just now in social media.]
    Glennda Chui

    The surprising results offer a way to boost the activity and stability of catalysts for making hydrogen fuel from water.

    1
    Credit: SLAC.

    2
    An illustration combines two possible types of surface layers for a catalyst that performs the water-splitting reaction, the first step in making hydrogen fuel. The gray surface, top, is lanthanum oxide. The colorful surface is nickel oxide; a rearrangement of its atoms while carrying out the reaction made it twice as efficient, a phenomenon researchers hope to harness to design better catalysts. Lanthanum atoms are depicted in green, nickel in blue and oxygen in red. Credit: CUBE3D Graphic.

    3
    A new study shows how tweaking the surface layer of a catalyst can make it work better. This particular catalyst is used to split water, the first step in making hydrogen fuel. It consists of alternating layers of materials rich in nickel (blue spheres) and lanthanum (green spheres; the red spheres represent oxygen atoms). When the material is grown at relatively cool temperatures so a nickel-rich layer is on top (left), the atoms on that surface layer rearrange during the water-splitting reaction (middle) in a way that allows them to carry out the reaction more efficiently (right). This surprising result gives scientists a new way to tune catalytic activity and engineer better catalysts. Credit:Tomas Duchon/Jülich Research Centre [Forschungszentrum Jülichs] (FZJ)(DE)[DE]).

    Scientists crafting a nickel-based catalyst used in making hydrogen fuel built it one atomic layer at a time to gain full control over its chemical properties. But the finished material didn’t behave as they expected: As one version of the catalyst went about its work, the top-most layer of atoms rearranged to form a new pattern, as if the square tiles that cover a floor had suddenly changed to hexagons.

    But that’s ok, they reported today, because understanding and controlling this surprising transformation gives them a new way to turn catalytic activity on and off and make good catalysts even better.

    The research team, led by scientists from Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory, described their study in Nature Materials today.

    “Catalysts can change very quickly during the course of a reaction, and understanding how they transform from an inactive phase to an active one is crucial to designing more efficient catalysts,” said Will Chueh, an investigator with the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC who led the study. “This transformation gives us the equivalent of a knob we can turn to fine-tune their behavior.”

    Splitting water to make hydrogen fuel

    Catalysts help molecules react without being consumed in the reaction, so they can be used over and over. They’re the backbone of many green-energy devices.

    This particular catalyst, lanthanum nickel oxide or LNO, is used to split water into hydrogen and oxygen in a reaction powered by electricity. It’s the first step in generating hydrogen fuel, which has enormous potential for storing renewable energy from sunlight and other sources in a liquid form that’s energy-rich and easy to transport. In fact, several manufacturers have already produced electric cars powered by hydrogen fuel cells.

    But this first step is also the most difficult one, said Michal Bajdich, a theorist at the SUNCAT Center for Interface Science and Catalysis at SLAC, and researchers have been searching for inexpensive materials that will carry it out more efficiently.

    Since reactions take place on a catalyst’s surface, researchers have been trying to precisely engineer those surfaces so they promote only one specific chemical reaction with high efficiency.

    Building materials one atomic layer at a time

    The LNO investigated in this study belongs to a class of promising catalytic materials known as perovskites, named after a natural mineral with a similar atomic structure.

    Christoph Baeumer, who came to SLAC as a Marie Curie Fellow from RWTH Aachen University [Rheinisch-Westfälische Technische Hochschule Aachen] (DE) to carry out the study, prepared LNO in what’s known as an epitaxial thin film – a film grown in atomically thin layers in a way that creates an extraordinarily precise arrangement of atoms.

    Dividing his time between California and Germany, Baeumer made two versions of the film at different temperatures ­­– one with a nickel-rich surface and another with a lanthanum-rich surface. Then the research team ran all the versions through the water-splitting reaction to compare how well they performed.

    “We were surprised to discover that the films with nickel-rich surfaces carried out the reaction twice as fast,” Baeumer said.

    Tuning a catalyst’s surface for better performance

    To find out why, the team took the films to DOE’s Lawrence Berkeley National Laboratory, where a group led by Slavomír Nemšák looked at their atomic structure with X-rays at the Advanced Light Source.

    LBNL ALS .

    “It was surprising that the difference between the ‘good’ and the ‘bad’ catalyst was only in the last atomic layer of the films,” Nemšák said. Those investigations also revealed that in films with nickel-rich surface layers that were prepared at cooler temperatures, the top layer of atoms transformed at some point during the water-splitting reaction, and this new arrangement boosted the catalytic activity.

    Meanwhile, Jiang Li, a postdoctoral researcher and theorist at SUNCAT, performed computational studies of this very complex system using Berkeley Lab’s National Energy Research Scientific Computing Center (NERSC).

    National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory

    NERSC Cray Cori II supercomputer, named after Gerty Cori, the first American woman to win a Nobel Prize in science.

    NERSC Hopper Cray XE6 supercomputer, named after Grace Hopper, One of the first programmers of the Harvard Mark I computer.

    NERSC Cray XC30 Edison supercomputer.

    NERSC GPFS for Life Sciences.


    The Genepool system is a cluster dedicated to the DOE Joint Genome Institute’s computing needs. Denovo is a smaller test system for Genepool that is primarily used by NERSC staff to test new system configurations and software.

    NERSC PDSF computer cluster in 2003.

    PDSF is a networked distributed computing cluster designed primarily to meet the detector simulation and data analysis requirements of physics, astrophysics and nuclear science collaborations.

    Future:

    Cray Shasta Perlmutter SC18 AMD Epyc Nvidia pre-exascale supeercomputer

    NERSC is a DOE Office of Science User Facility.

    His conclusions agreed with the experimental results, predicting that the version of the catalyst with the transformed surface – from a cubic pattern to a hexagonal one – would be the most active and stable one.

    Bajdich said, “Is the transformation of the nickel-rich surface driven by the way the catalyst is prepared, or by changes it undergoes while it carries out the water-splitting reaction? That’s very hard to answer. It looks like both have to occur.”

    Although this particular catalyst is not the best in the world for splitting water into hydrogen and oxygen, he said, discovering how a surface transformation boosts its activity is important and could potentially apply to other materials too.

    “If we can unlock the secrets of this transformation so we can accurately tune it,” he said, “then we can leverage this phenomenon to make much better catalysts in the future.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

    SLAC National Accelerator Lab


    SLAC/LCLS


    SLAC/LCLS II projected view

    SLAC LCLS-II Undulators The Linac Coherent Light Source’s new undulators each use an intricately tuned series of magnets to convert electron energy into intense bursts of X-rays. The “soft” X-ray undulator stretches for 100 meters on the left side of this hall, with the “hard” x-ray undulator on the right. Credit: Alberto Gamazo/SLAC National Accelerator Laboratory.

    SSRL and LCLS are DOE Office of Science user facilities.

     
  • richardmitnick 2:13 pm on January 4, 2021 Permalink | Reply
    Tags: "First glimpse of polarons forming in a promising next-gen energy material", , , DOE’s SLAC National Accelerator Laboratory, Lead hybrid perovskite, , These materials have taken the field of solar energy research by storm.   

    From DOE’s SLAC National Accelerator Laboratory: “First glimpse of polarons forming in a promising next-gen energy material” 

    From DOE’s SLAC National Accelerator Laboratory

    January 4, 2021
    Glennda Chui

    1
    An illustration shows polarons – fleeting distortions in a material’s atomic lattice ––in a promising next-generation energy material, lead hybrid perovskite. Scientists at SLAC and Stanford observed for the first time how these “bubbles” of distortion form around charge carriers – electrons and holes that have been liberated by pulses of light – which are shown as bright spots here. This process may help explain why electrons travel so efficiently in these materials, leading to high solar cell performance. Credit: Greg Stewart/SLAC National Accelerator Laboratory.

    Polarons are fleeting distortions in a material’s atomic lattice that form around a moving electron in a few trillionths of a second, then quickly disappear. As ephemeral as they are, they affect a material’s behavior, and may even be the reason that solar cells made with lead hybrid perovskites achieve extraordinarily high efficiencies in the lab.

    Now scientists at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have used the lab’s X-ray laser to watch and directly measure the formation of polarons for the first time. They reported their findings in Nature Materials today.

    “These materials have taken the field of solar energy research by storm because of their high efficiencies and low cost, but people still argue about why they work,” said Aaron Lindenberg, an investigator with the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC and associate professor at Stanford who led the research.

    “The idea that polarons may be involved has been around for a number of years,” he said. “But our experiments are the first to directly observe the formation of these local distortions, including their size, shape and how they evolve.”

    Exciting, complex and hard to understand

    Perovskites are crystalline materials named after the mineral perovskite, which has a similar atomic structure. Scientists started to incorporate them into solar cells about a decade ago, and the efficiency of those cells at converting sunlight to energy has steadily increased, despite the fact that their perovskite components have a lot of defects that should inhibit the flow of current.

    These materials are famously complex and hard to understand, Lindenberg said. While scientists find them exciting because they are both efficient and easy to make, raising the possibility that they could make solar cells cheaper than today’s silicon cells, they are also highly unstable, break down when exposed to air and contain lead that has to be kept out of the environment.

    Previous studies at SLAC have delved into the nature of perovskites with an “electron camera” or with X-ray beams. Among other things, they revealed that light whirls atoms around in perovskites, and they also measured the lifetimes of acoustic phonons – sound waves ­– that carry heat through the materials.

    For this study, Lindenberg’s team used the lab’s Linac Coherent Light Source (LCLS) [below], a powerful X-ray free-electron laser that can image materials in near-atomic detail and capture atomic motions occurring in millionths of a billionth of a second. They looked at single crystals of the material synthesized by Associate Professor Hemamala Karunadasa’s group at Stanford.

    They hit a small sample of the material with light from an optical laser and then used the X-ray laser to observe how the material responded over the course of tens of trillionths of a second.

    3
    As this animation shows, polaronic distortions start very small and rapidly expand outward in all directions to a diameter of about 5 billionths of a meter, which is about a 50-fold increase. This nudges about 10 layers of atoms slightly outward within a roughly spherical area over the course of tens of picoseconds, or trillionths of a second. Credit: Greg Stewart/SLAC National Accelerator Laboratory.

    Expanding bubbles of distortion

    “When you put a charge into a material by hitting it with light, like what happens in a solar cell, electrons are liberated, and those free electrons start to move around the material,” said Burak Guzelturk, a scientist at DOE’s Argonne National Laboratory who was a postdoctoral researcher at Stanford at the time of the experiments.

    “Soon they are surrounded and engulfed by a sort of bubble of local distortion – the polaron – that travels along with them,” he said. “Some people have argued that this ‘bubble’ protects electrons from scattering off defects in the material, and helps explain why they travel so efficiently to the solar cell’s contact to flow out as electricity.”

    The hybrid perovskite lattice structure is flexible and soft ­– like “a strange combination of a solid and a liquid at the same time,” as Lindenberg puts it – and this is what allows polarons to form and grow.

    Their observations revealed that polaronic distortions start very small ­– on the scale of a few angstroms, about the spacing between atoms in a solid – and rapidly expand outward in all directions to a diameter of about 5 billionths of a meter, which is about a 50-fold increase. This nudges about 10 layers of atoms slightly outward within a roughly spherical area over the course of tens of picoseconds, or trillionths of a second.

    “This distortion is actually quite large, something we had not known before,” Lindenberg said. “That’s something totally unexpected.”

    He added, “While this experiment shows as directly as possible that these objects really do exist, it doesn’t show how they contribute to the efficiency of a solar cell. There’s still further work to be done to understand how these processes affect the properties of these materials.”

    See the full article here .


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    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

    SLAC National Accelerator Lab


    SLAC/LCLS


    SLAC/LCLS II projected view

    SLAC LCLS-II Undulators The Linac Coherent Light Source’s new undulators each use an intricately tuned series of magnets to convert electron energy into intense bursts of X-rays. The “soft” X-ray undulator stretches for 100 meters on the left side of this hall, with the “hard” x-ray undulator on the right. Credit: Alberto Gamazo/SLAC National Accelerator Laboratory.

    SSRL and LCLS are DOE Office of Science user facilities.

     
  • richardmitnick 2:36 pm on December 29, 2020 Permalink | Reply
    Tags: "The World's Largest Camera Has Taken the First 3200 Megapixel Images at SLAC.", DOE’s SLAC National Accelerator Laboratory, , , Scientists used the camera first on vegetables which they first took a snap of the first 3200 megapixel photos., The camera is as big as the SUV and has 189 individual light sensors that bring 16 megapixels of data or a total of 3200 megapixels., The camera is scheduled to be transferred in 2021 to the Rubin Observatory., The focal plan does not only contain 3.2 billion pixels but its pixels are also very small., The whole camera is designed in a way that imaging sensors could detect objects that are over 10 million times dimmer than objects that are visible to the naked eye., The world's largest digital camera is capable of taking 3.2 billion pixel photographs which is the largest single-shot photos ever taken., These properties make it possible for the camera to take sharp images of a full-frame consumer camera and large enough to take photos of a portion of the sky with 40 full moons.   

    From DOE’s SLAC National Accelerator Laboratory via Science Times: “The World’s Largest Camera Has Taken the First 3,200 Megapixel Images at SLAC” 

    From DOE’s SLAC National Accelerator Laboratory

    via

    Science Times

    Science Times

    Dec 28, 2020
    Erika P.

    The world’s largest digital camera is capable of taking 3.2 billion pixel photographs, which is the largest single-shot photos ever taken. This camera is scheduled to be transferred to the Vera C. Rubin Observatory, designed to survey the southern sky for the Legacy Survey of Space and Time (LSST).

    SLAC 3200 megapixel camera for Vera C Rubin Observatory

    NOIRLab Vera C. Rubin Observatory Telescope currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes, altitude 2,715 m (8,907 ft).

    This camera will help astronomers peer back into the universe and understand how galaxies evolve, and answer questions about how dark matter mesh with reality. This camera will also help scientists observe some of the dimmest light of the universe that hopefully could help them see far back of the universe’s history.

    But before using this to observing space, the scientists used the camera first on vegetables, which they first took a snap of the first 3,200 megapixel photos. Scientists at Stanford University’s SLAC Laboratory had to construct a bigger camera than the typical smartphone camera to produce ultra high definition photos.

    1
    Taking the first 3,200-megapixel images was an important first test for the focal plane. To do so without a fully assembled camera, the SLAC team used a 150-micron pinhole to project images onto the focal plane. Left: Schematic of a pinhole projector that projects images of a Romanesco’s detailed texture onto the focal plane. Right: SLAC’s Yousuke Utsumi and Aaron Roodman remove the pinhole projector from the cryostat assembly after projecting the first images onto the focal plane. Explore the test images in full resolution using the links at the bottom of this press release. Credit: Greg Stewart/Jacqueline Orrell/SLAC National Accelerator Laboratory.

    How Does the World’s Largest Camera Work?

    The camera is as big as the SUV and has 189 individual light sensors that bring 16 megapixels of data or a total of 3,200 megapixels, according to an article in Inverse. The 189 light sensors are grouped in nine sets, and their supporting electronics were constructed into square units called “science rafts.”

    The camera team inserted 21 of these science rafts and four additional non-imaging rafts to form the final camera. According to SLAC mechanical engineer Hannah Pollek, who worked on this project, this process was extremely delicate.

    “The combination of high stakes and tight tolerances made this project very challenging. But with a versatile team, we pretty much nailed it,” Pollek said.

    Moreover, the focal plan does not only contain 3.2 billion pixels, but its pixels are also very small, and the focal plane itself is extremely flat, measuring about ten microns wide and less than one-tenth of a human hair, respectively.

    These properties make it possible for the camera to take sharp images of a full-frame consumer camera and large enough to take photos of a portion of the sky with 40 full moons, SLAC’s press release stated.

    Lastly, the whole camera is designed in a way that imaging sensors could detect objects that are over 10 million times dimmer than objects that are visible to the naked eye. In other words, it can spot an object or let a person see a lit candle from thousands of miles away.

    What’s Next With the World’s Largest Digital Camera?

    The SLAC team captured a few photos using items found in the lab before taking the camera from Northern California to its final destination in Chile. They took a photo of the fractal-like romanesco broccoli and Vera Rubin’s photo, the namesake of the observatory conducting the LSST.

    These 3,200-megapixel photos are by far the largest, single-shot images ever taken that it would at least 378 4K ultra-high-definition TV screens to view its full size.

    The success of taking these initial photos plays a significant role in capturing and understanding the universe. It is a milestone that brings the scientists to s big step closer in exploring fundamental questions about the cosmos in ways that were not yet explored before, said SLAC’s chief research officer and associate lab director for fundamental physics, JoAnne Hewett.

    The camera is scheduled to be transferred in 2021 to the Rubin Observatory.


    Vera C. Rubin Observatory LSST Camera.

    See the full article here .

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    Sciencetimes.com prides itself in providing a complete informational and content package for science enthusiasts in the web who aim to remain updated and well-informed regarding a wide array of topics of their interest.

    We provide credible news & info., in-depth reference material about diverse subjects that matter to everyone. We are a source for original and timely science and research information as well as breaking news in the various fields we represent.

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

    SLAC National Accelerator Lab


    SLAC/LCLS


    SLAC/LCLS II projected view

    SLAC LCLS-II Undulators The Linac Coherent Light Source’s new undulators each use an intricately tuned series of magnets to convert electron energy into intense bursts of X-rays. The “soft” X-ray undulator stretches for 100 meters on the left side of this hall, with the “hard” x-ray undulator on the right. Credit: Alberto Gamazo/SLAC National Accelerator Laboratory.

    SSRL and LCLS are DOE Office of Science user facilities.

     
  • richardmitnick 9:36 am on November 17, 2020 Permalink | Reply
    Tags: "Gravitational lenses could hold the key to better estimates of the expansion of the universe", DOE’s SLAC National Accelerator Laboratory, , SLAC-Kavli Institute for Particle Physics and Astrophysics, Time-delay cosmography   

    From DOE’s SLAC National Accelerator Laboratory and Stanford University Kavli Institute for Particle Physics and Astrophysics: “Gravitational lenses could hold the key to better estimates of the expansion of the universe” 

    From DOE’s SLAC National Accelerator Laboratory

    and

    KIPAC bloc

    SLAC- KIPAC: Kavli Institute for Particle Astrophysics and Cosmology

    November 16, 2020
    Nathan Collins

    SLAC cosmologists are using multiple images of the same quasars, produced by massive galaxies’ gravitational pull, to calibrate cosmic distances. Their work may help resolve long-standing debates about how quickly the universe is expanding.

    The universe is expanding but astrophysicists aren’t sure exactly how fast that expansion is happening – not because there aren’t answers, but rather because the answers they could give don’t agree.

    Now, Simon Birrer, a postdoctoral fellow at Stanford University and the Kavli Institute for Particle Physics and Astrophysics at the Department of Energy’s SLAC National Accelerator Laboratory, and an international team of researchers have a new answer that may, once refined with more data, help resolve the debate.

    That new answer is the result of revisiting a decades-old method called time-delay cosmography with new assumptions and additional data to derive a new estimate of the Hubble constant, a measure of the expansion of the Universe. Birrer and colleagues published their results November 20 in the journal Astronomy and Astrophysics.

    “It’s a continuation of a large and successful decade-long effort by a large team, with a reset in certain key aspects of our analysis,” Birrer said, and a reminder that “we should always reconsider our assumptions. Our recent work is exactly in this spirit.”

    1
    If everything lines up just right, a galaxy’s gravitational pull can bend light from a distant quasar into four separate images. And if the light that forms those images has reached us along paths of slightly different lengths, researchers can measure the time delays between the paths and infer distances to the galaxy and the distant quasar. Credit: Martin Millon/Swiss Federal Institute of Technology Lausanne (CH). Galaxy and quasar image: Hubble Space Telescope/NASA.)

    Distance, speed and sound

    Cosmologists have known for nearly a century that the cosmos is expanding, and in that time they have settled on two main ways to measure that expansion. One method is the cosmic distance ladder, a series of steps that help estimate the distance to far-away supernovae.

    4
    Three Steps to Measuring the Hubble Constant. Credit: NASA.

    By examining the spectrum of light from these supernovae, scientists can calculate how quickly they’re receding from us, then divide by distance to estimate the Hubble constant. (The Hubble constant is usually measured in kilometers per second per megaparsec, reflecting the fact that space itself is growing, so that more distant objects recede from us faster than nearer objects.)

    Astrophysicists can also estimate the constant from ripples in the cosmic microwave background radiation, or CMB.

    CMB per ESA/Planck

    Those ripples result from sound waves traveling through plasma in the early universe. By measuring the ripples’ size they can infer how long ago and how far away the CMB light we see today was created. Drawing on well-established cosmological theory, researchers can then estimate how rapidly the universe is expanding.

    Both approaches, however, have drawbacks. Sound-wave methods rely heavily on how sound travelled in the early universe, which depends in turn on the particular mix of types of matter at the time, on how long sound waves travelled before leaving their imprint on the CMB, and on assumptions about the expansion of the universe since that time. Meanwhile, cosmic distance ladder methods chain together a series of estimates, starting with radar estimates of the distance to the sun and parallax estimates of the distance to pulsating stars called cepheids. That introduces a chain of calibrations and measurements, each of which needs to be precise and accurate enough to ensure a reliable estimate of the Hubble constant.

    2
    (Top) The gravitational pull of a massive galaxy (center object) bends the light from a distant quasar on four paths, resulting in four images of the same quasar (A–D). Because each path has a slightly different length, light takes different amounts of time to traverse the paths, so the images appear to twinkle slightly out of sync with each other. (Bottom) A graph of the magnitude, or brightness, of the four quasar images over time. Credit: M. Millon and F. Courbin/Swiss Federal Institute of Technology Lausanne (CH).

    A lens from the past

    But there is a way to measure distances more directly, based on what are called strong gravitational lenses.

    Gravitational Lensing

    Gravitational Lensing NASA/ESA.

    Gravity bends spacetime itself and with it the path light takes through the cosmos. One special case is when a very massive object, such as a galaxy, bends the light of a distant object around such that light reaches us along multiple different paths, effectively creating multiple images of the same background object. A particularly beautiful example is when the distant object varies over time – for example, as accreting supermassive black holes, known as quasars, do. Because the light travels slightly different amounts of time along each path around the lensing galaxy, the result is multiple slightly out-of-sync images of the same flickering.

    This phenomenon is more than just pretty. Back in the 1960s, students of Einstein’s theory of gravity, general relativity, showed they could use strong gravitational lenses and the light they bend to more directly measure cosmic distances – if they could measure the relative timing along each path precisely enough and if they knew how matter in the lensing galaxy was distributed.

    Over the last decade, Birrer said, measurements became precise enough to take this method, time-delay cosmography, from idea to reality. Successive measurements and a dedicated effort by the H0LiCOW, COSMOGRAIL, STRIDES, and SHARP teams, now under the joint umbrella organization TDCOSMO, culminated in a precise Hubble constant measurement at around 73 kilometers per second per megaparsec with a precision of 2%. That’s in agreement with estimates made with the local distance ladder method, but in tension with the cosmic microwave background measurements under the standard cosmological model assumptions.

    Galaxy mass distribution assumptions

    But something didn’t sit right with Birrer: The models of galaxy structure previous studies relied on might not have been accurate enough to conclude that the Hubble constant was different from estimates based on the cosmic microwave background. “I went to my colleagues and said, ‘I want to conduct a study that does not rely on those assumptions,’” Birrer said.

    In their place, Birrer proposed to investigate a range of additional gravitational lenses to make more observationally grounded estimate of the mass and structure of the lensing galaxies to replace previous assumptions. The new avenue Birrer and the team, TDCOSMO, were undertaking was deliberately held blind – meaning the entire analysis was performed without knowing the resulting outcome on the Hubble constant – to avoid experimenter bias, a procedure established already in the previous analyses of the team and an integral part in moving forward, Birrer said.

    Based on this new analysis with significantly fewer assumptions applied to the seven lensing galaxies with time delays the team has analyzed in previous studies, the team arrived at a higher value of the Hubble constant, around 74 kilometers per second per megaparsec, but with greater uncertainty – enough so that their value was consistent with both high and low estimates of the Hubble constant.

    However, when Birrer and TDCOSMO added 33 additional lenses with similar properties – but without a variable source to work for time-delay cosmography directly – used to estimate galactic structure, the Hubble constant estimate went down to about 67 kilometers per second per megaparsec, with a 5% uncertainty, in good agreement with sound-wave estimates such as that from the CMB, but also statistically consistent with the previous determinations, given the uncertainties.

    That substantial shift does not mean the debate over the Hubble constant’s value is over – far from it, Birrer said. For one thing, his method introduces new uncertainty into the estimate associated with the 33 additional lenses being added into the analysis, and TDCOSMO will need more data to confirm their results, although that data may not be far off into the future. Birrer: “While our new analysis does not statistically invalidate the mass profile assumptions of our previous work, it demonstrates the importance of understanding the mass distribution within galaxies,” he said.

    “We are collecting now the data that will allow us to gain back most of the precision we previously had achieved based on stronger assumptions. Looking further ahead we’ll also have images from a lot more lensing galaxies from the Rubin Observatory Legacy Survey of Space and Time to draw on to improve our estimates. Our current analysis is only the first step and paves the way to utilizing these upcoming data sets to provide a definite conclusion on the remaining problem.”

    The research was supported by grants from the National Science Foundation, the National Aeronautics and Space Administration, the Packard Foundation, the Kavli Foundation, the Danish Council for Independent Research, the Villum Foundation, the Royal Astronomical Society, the European Research Council, the Hintze Family Charitable Foundation, the Max Planck Society, the World Premier International Research Center Initiative and the Japan Society for the Promotion of Science.

    See the full article here .


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    The Kavli Institute for Particle Astrophysics and Cosmology, or KIPAC, is an independent laboratory of Stanford University. Initiated with a generous grant from Fred Kavli and The Kavli Foundation, KIPAC is housed at the SLAC National Accelerator Laboratory and in the Varian Physics and Physics Astrophysics buildings on the Stanford campus. The lab is funded in part by Stanford University and the United States Department of Energy.

    SLAC National Accelerator Lab

    SLAC/LCLS

    SLAC/LCLS II projected view

    SLAC LCLS-II Undulators The Linac Coherent Light Source’s new undulators each use an intricately tuned series of magnets to convert electron energy into intense bursts of X-rays. The “soft” X-ray undulator stretches for 100 meters on the left side of this hall, with the “hard” x-ray undulator on the right. Credit: Alberto Gamazo/SLAC National Accelerator Laboratory.


    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

    SSRL and LCLS are DOE Office of Science user facilities.

     
  • richardmitnick 2:28 pm on November 12, 2020 Permalink | Reply
    Tags: "Scientists launch quest to develop quantum sensors for probing quantum materials", A scanning qubit microscope, A spectroscopy instrument that takes advantage of pairs of entangled electrons., DOE’s SLAC National Accelerator Laboratory, Exotic entangled states, SQUIDs-superconducting quantum interference devices, , This Center will create a veritable wealth of new quantum ideas and devices., Topological insulators which carry current with no loss along their edges., Understanding the atomic-level processes behind unconventional superconductors that conduct electricity with no resistance at relatively high temperatures., ,   

    From DOE’s SLAC National Accelerator Laboratory and Stanford University: “Scientists launch quest to develop quantum sensors for probing quantum materials” 

    From DOE’s SLAC National Accelerator Laboratory

    and

    Stanford University Name
    Stanford University

    October 29, 2020
    Glennda Chui

    SLAC and Stanford partner with two Illinois universities to create the Center for Quantum Sensing and Quantum Materials, which aims to unravel mysteries associated with exotic superconductors, topological insulators and strange metals.

    1
    When it comes to fully understanding the hidden secrets of quantum materials, it takes one to know one, scientists say: Only tools that also operate on quantum principles can get us there.A new Department of Energy research center will focus on developing those tools. Based at the University of Illinois at Urbana-Champaign, the Center for Quantum Sensing and Quantum Materials brings together experts from UIUC, DOE’s SLAC National Accelerator Laboratory, Stanford University and the University of Illinois-Chicago. Credit: Caitlin Kengle/UIUC.

    They’ll work on developing three cutting-edge quantum sensing devices: a scanning qubit microscope, a spectroscopy instrument that takes advantage of pairs of entangled electrons and another instrument that will probe materials with pairs of photons from SLAC’s X-ray free-electron laser, the Linac Coherent Light Source [below], which has recently reopened after an upgrade.

    These new techniques will allow researchers to see in much greater detail why quantum materials do the weird things they do, paving the way to discovering new quantum materials and inventing even more sensitive probes of their behavior.

    The work will focus on understanding the atomic-level processes behind unconventional superconductors that conduct electricity with no resistance at relatively high temperatures; topological insulators, which carry current with no loss along their edges; and strange metals, which superconduct when chilled but have strange properties at higher temperatures.

    “What is exciting is that this center gives us a chance to create some really new quantum measurement techniques for studying energy-relevant quantum materials,” center Director Peter Abbamonte, a professor of physics at UIUC, said in a press release.

    “We often get trapped in the cycle of using the same old measurements – not because we don’t need new kinds of information or knowledge, but because developing techniques is expensive and time consuming,” Abbamonte said. The new center, he said, will allow scientists to push the envelope of quantum measurement by tackling bigger problems.

    Exotic entangled states

    Quantum materials get their name from the fact that their exotic properties stem from the cooperative behavior of electrons and other phenomena that obey the rules of quantum mechanics, rather than the familiar Newtonian laws of physics that govern our everyday world. These materials could eventually have a huge impact on future energy technologies – for instance, by allowing people to transmit power with essentially no loss over long distances and making transportation much more energy efficient.

    But a quantum material may contain a confounding mixture of exotic, overlapping states of matter that are hard to sort out with conventional tools.

    “In the quantum world everything becomes entangled, so the boundaries of one object start to overlap with the boundaries of another,” said SLAC Professor Thomas Devereaux, one of six SLAC and Stanford researchers collaborating in the new center. “We’ll be probing this entanglement using various tools and techniques.”

    Quantum sensors are nothing new. They include superconducting quantum interference devices, or SQUIDs, invented half a century ago to detect extremely small magnetic fields, and superconducting transition edge sensors, which incorporate SQUIDS to detect exquisitely small signals in astronomy, nuclear non-proliferation, materials analysis and homeland defense.

    At a basic level, they operate by putting the sensor into a known quantum state and allowing it to interact with the object of interest. The interaction changes the state of the quantum system, and measuring the new state of the system reveals information about the object that could not be obtained with conventional approaches.

    Qubits on a tip

    In one of the technologies under development, the scanning qubit microscope, the quantum sensor would consist of one or more qubits placed on the tip of a probe and moved over the surface of a material. A qubit is a basic unit of quantum information, like the bits of ordinary computer memory that flip back and forth between zero and 1. But a qubit exists as a superposition of both zero and 1 states at once. The scanner’s qubit might consist of a single hydrogen atom, for instance, with the spin of its single electron simultaneously existing as up, down and all possible states in between.

    “You can try to entangle the qubit sensor with the quantum state of the material you’re studying so you can actually sense the entanglement of quantum states within the material,” said Kathryn Moler, Stanford’s vice provost and dean of research. “If we can do that, it will be really cool.”

    Other SLAC and Stanford researchers collaborating in research for the new center are Professors Zhi-Xun Shen and David Reis, Assistant Professor Ben Feldman and staff scientist Mariano Trigo.

    The center is one of 10 Energy Frontier Research Centers awarded $100 million by the DOE Office of Science.

    See the full article here .


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    Stanford University campus. No image credit

    Stanford University

    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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    SLAC National Accelerator Lab


    SLAC/LCLS


    SLAC/LCLS II projected view

    SLAC LCLS-II Undulators The Linac Coherent Light Source’s new undulators each use an intricately tuned series of magnets to convert electron energy into intense bursts of X-rays. The “soft” X-ray undulator stretches for 100 meters on the left side of this hall, with the “hard” x-ray undulator on the right. Credit: Alberto Gamazo/SLAC National Accelerator Laboratory.


    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

    SSRL and LCLS are DOE Office of Science user facilities.

     
  • richardmitnick 10:05 am on October 23, 2020 Permalink | Reply
    Tags: "A day in the life of a SLAC machine maker", , , , DOE’s SLAC National Accelerator Laboratory   

    From DOE’s SLAC National Accelerator Laboratory: “A day in the life of a SLAC machine maker” 

    From DOE’s SLAC National Accelerator Laboratory

    October 21, 2020
    Angela Anderson

    At the Machine Shop, Pete Franco crafts beautiful, intricate and precise parts for the lab’s latest scientific tools.

    Behind every clever scientific device – accelerator, detector, X-ray laser and more – at the Department of Energy’s SLAC National Accelerator Laboratory are the people who make their parts.

    “If you can dream it up, we can make it,” says Pete Franco, lead machinist at the lab’s machine shop. He and the other 10 machinists who work there take engineers’ plans and models of their inventions and craft the pipes, clamps, gears and other parts that make those inventions work.

    1
    Lead machinist Pete Franco has worked 19 years at the SLAC Machine Shop. Credit:Jacqueline Orrell/SLAC National Accelerator Laboratory.

    Making machines for science is a SLAC tradition, going back to the original accelerator that was designed and manufactured on site.

    Franco, who has been working at the SLAC machine shop for 19 years, feels a sense of pride in the parts he has crafted for machines, including the storage ring and magnets for the Stanford Synchrotron Radiation Lightsource, the Accelerator Structure Test Area and the superconducting X-ray laser upgrade currently under construction at the Linac Coherent Light Source (LCLS) – all used to help scientists explore and understand fundamental mechanics of the world around us.

    SLAC/SSRL.

    SLAC LCLS-II Undulators The Linac Coherent Light Source’s new undulators each use an intricately tuned series of magnets to convert electron energy into intense bursts of X-rays. The “soft” X-ray undulator stretches for 100 meters on the left side of this hall, with the “hard” x-ray undulator on the right. Credit: Alberto Gamazo/SLAC National Accelerator Laboratory.

    That pride only grew with his return to the shop in June, when the lab brought back a portion of the workforce that had been ordered to shelter in place due to COVID-19 to continue work at facilities running experiments related to the virus. Franco and colleagues helped support the recent restart of LCLS, for example, which is hosting a number of experiments looking at the inner workings of the SARS-CoV-2 virus.

    7
    Over the past 18 months, the original LCLS undulator system (left) was removed and replaced with two totally new systems that offer dramatic new capabilities (right). Credit: Andy Freeberg/Alberto Gamazo/SLAC National Accelerator Laboratory.

    The new safety regulations that had been put in place were odd at first, but in no time “cleaning, social distancing and wearing a mask became second nature,” Franco said. “I was happy to come back, especially because our main focus at the time was on COVID-19-related work. It was nice to feel part of something aiming at a cure for all of this.”

    2
    A machinery handbook is among the tools used by SLAC’s machinists. Credit:Jacqueline Orrell/SLAC National Accelerator Laboratory.

    The machine shop crafts parts for facilities and for groups of scientists across the lab, which makes every day a little different, Franco said. A large machine like LCLS will be an ongoing focus, but Franco also assists with smaller tools for science. A recent project involved working with a Stanford doctor on modifications to treatment tools for ovarian cancer.

    Franco is the lead machinist and backup for machine shop supervisor Denise Larsen. He also manages the department’s software interface, MasterCam, giving classes on it and answering questions when people have problems. “It makes the code that talks to the machines in the machine shop and tells them what to make,” he explains.

    Part of what draws him to machining are the interesting materials he works with – tungsten, tantalum, cobalt, titanium and copper. Accuracy is paramount when shaping parts for a machine like a linear accelerator, where copper pieces graduate from square to oval to circle shapes in order to carry radio-frequency electrical currents.

    3
    An electrical discharge machine uses brass wire to burn through metal with heat from electrical sparks. Deionized water helps conduct electricity, keep the environment cool and flush away any debris from the cutting process. Credit: Jacqueline Orrell/SLAC National Accelerator Laboratory.

    One method the shop uses for cutting hard metals is called electrical discharge machining. Brass wire “burns” through metal with heat from electrical sparks. The tool can cut shapes, contours and cavities in any material that conducts electricity with an accuracy of within two ten-thousandths of an inch, Franco said. Division Director Lydia Young recently estimated that the shop used 1,250 miles of brass wire in one year to do the cutting in these machines.

    A second important machine in the shop is a computer controlled vertical mill, which uses rotary cutters to carve materials along an axis, and can be used to craft complex 3D surfaces.

    SLAC engineers provide printed and 3D computerized models for the designs they want, and the machine shop works closely with them to deliver. “I can set up as many as 25 different tools at a time to accomplish tasks such as milling, drilling, tapping threads – all at different depths,” Franco explains. “It just comes down to can we cut it?”

    4
    A computer controlled vertical mill, which uses rotary cutters to carve materials along an axis. Credit: Jacqueline Orrell/SLAC National Accelerator Laboratory.

    Franco credits his grandfather for passing down the maker genes: The elder Franco made everything he could in his own home and branded it “functional primitive” style. As a kid, the younger Franco was always building his own go-carts, and as an adult he has turned his three-bedroom, one-bath house into a six-bedroom, three-bathroom house, where he and his wife – KPIX CBS-5 traffic reporter and sports radio host Gianna Franco – live with their four children between the ages of 20 and 1.

    Somehow, Franco also finds time for music. The bass player has toured with the Bay Area band The Mother Truckers and continues to gig now and then.

    His work at the machine shop can be just as creative and rewarding.

    Franco recently designed a crane to lift the cryogenic chamber of a massive digital camera that will go into the telescope at the Vera C. Rubin Observatory in Chile. It took months to design and construct for this particular purpose.

    LSST Camera, being built at SLAC

    NOIRLab Vera C. Rubin Observatory Telescope currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes, altitude 2,715 m (8,907 ft).

    “It seems incredible to make such a device for this very specific use, but it might be repurposed in the future for another job,” he said.

    And that’s the beauty of a place like the SLAC machine shop: The machines and materials (and the people) are always in the process of becoming or making something new.

    5
    Pete Franco holds a copper radio-frequency chamber crafted for a septum magnet used at the Stanford Radiation Synchrotron Lightsource. Credit: Jacqueline Orrell/SLAC National Accelerator Laboratory.

    6
    Another machine tool, called a manual lathe, rotates the workpiece on an axis against the edge of a cutting tool. Credit: Jacqueline Orrell/SLAC National Accelerator Laboratory.

    7
    A collection of tool holders that load in and out of the manual milling machine’s spindle. Machinists chose the appropriate tool and holder based on the kind of job they are performing. Credit: Jacqueline Orrell/SLAC National Accelerator Laboratory.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    SLAC National Accelerator Lab


    SLAC/LCLS


    SLAC/LCLS II projected view

    SLAC LCLS-II Undulators The Linac Coherent Light Source’s new undulators each use an intricately tuned series of magnets to convert electron energy into intense bursts of X-rays. The “soft” X-ray undulator stretches for 100 meters on the left side of this hall, with the “hard” x-ray undulator on the right. Credit: Alberto Gamazo/SLAC National Accelerator Laboratory.


    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

    SSRL and LCLS are DOE Office of Science user facilities.

     
  • richardmitnick 11:43 am on October 15, 2020 Permalink | Reply
    Tags: "A new approach boosts lithium-ion battery efficiency and puts out fires too", , DOE’s SLAC National Accelerator Laboratory,   

    From DOE’s SLAC National Accelerator Laboratory and Stanford University: “A new approach boosts lithium-ion battery efficiency and puts out fires, too” 

    From DOE’s SLAC National Accelerator Laboratory

    and

    Stanford University Name
    Stanford University

    October 15, 2020
    Glennda Chui
    glennda@slac.stanford.edu
    (510) 507-2766

    Adding polymers and fireproofing to a battery’s current collectors makes it lighter, safer and about 20% more efficient.

    In an entirely new approach to making lithium-ion batteries lighter, safer and more efficient, scientists at Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory have reengineered one of the heaviest battery components ­– sheets of copper or aluminum foil known as current collectors ­– so they weigh 80% less and immediately quench any fires that flare up.

    If adopted, the researchers said, this technology could address two major goals of battery research: extending the driving range of electric vehicles and reducing the danger that laptops, cell phones and other devices will burst into flames. This is especially important when batteries are charged super-fast, creating more of the types of battery damage that can lead to fires.

    The research team described their work in Nature Energy today.

    “The current collector has always been considered dead weight, and until now it hasn’t been successfully exploited to increase battery performance,” said Yi Cui, a professor at SLAC and Stanford and investigator with the Stanford Institute for Materials and Energy Sciences (SIMES) who led the research.

    “But in our study, making the collector 80% lighter increased the energy density of lithium-ion batteries – how much energy they can store in a given weight – by 16-26%. That’s a big jump compared to the average 3% increase achieved in recent years.”

    1
    Scientists at Stanford and SLAC redesigned current conductors – thin metal foils that distribute current to and from electrodes – to make lithium-ion batteries lighter, safer and more efficient. They replaced the all-copper conductor, middle, with a layer of lightweight polymer coated in ultrathin copper (top right), and embedded fire retardant in the polymer layer to quench flames (bottom right). Credit: Yusheng Ye/Stanford University.

    Desperately seeking weight loss

    Whether they come in the form of cylinders or pouches, lithium-ion batteries have two current collectors, one for each electrode. They distribute current flowing in or out of the electrode, and account for 15% to as much as 50% of the weight of some high-power or ultrathin batteries. Shaving a battery’s weight is desirable in itself, enabling lighter devices and reducing the amount of weight electric vehicles have to lug around; storing more energy per given weight allows both devices and EVs to go longer between charges.

    Reducing battery weight and flammability could also have a big impact on recycling by making the transportation of recycled batteries less expensive, Cui said.

    Researchers in the battery industry have been trying to reduce the weight of current collectors by making them thinner or more porous, but these attempts have had unwanted side effects, such as making batteries more fragile or chemically unstable or requiring more electrolyte, which raises the cost, said Yusheng Ye, a postdoctoral researcher in Cui’s lab who carried out the experiments with visiting scholar Lien-Yang Chou.

    As far as the safety issue, he said, “People have also tried adding fire retardant to the battery electrolyte, which is the flammable part, but you can only add so much before it becomes viscous and no longer conducts ions well.”

    2
    A redesigned current collector for lithium-ion batteries makes batteries lighter, more energy efficient and safer. It could also cut costs by replacing copper with cheaper polymer and by reducing the cost of transporting batteries for recycling. Credit:Greg Stewart/SLAC National Accelerator Laboratory.

    Designing a polymer-foil sandwich

    After brainstorming the problem, Cui, Ye and graduate student Yayuan Liu designed experiments for making and testing current collectors based on a lightweight polymer called polyimide, which resists fire and stands up to the high temperatures created by fast battery charging. A fire retardant ­– triphenyl phosphate, or TPP – was embedded in the polymer, which was then coated on both surfaces with an ultrathin layer of copper. The copper would not only do its usual job of distributing current, but also protect the polymer and its fire retardant.

    Those changes reduced the weight of the current collector by 80% compared to today’s versions, Ye said, which translates to an energy density increase of 16-26% in various types of batteries, and it conducts current just as well as regular collectors with no degradation.

    3
    When exposed to open flame, lithium-ion pouch batteries made with today’s commercial current collectors (top row) caught fire and burned vigorously until all the electrolyte burned away. Batteries with the new flame-retardant collectors (bottom row) produced weak flames that went out within a few seconds, and did not flare up again even when the scientists tried to relight them. Credit: Yusheng Ye/Stanford University.

    When exposed to an open flame from a lighter, pouch batteries made with today’s commercial current collectors caught fire and burned vigorously until all the electrolyte burned away, Ye said. But in batteries with the new flame-retardant collectors, the fire never really got going, producing very weak flames that went out within a few seconds, and did not flare up again even when the scientists tried to relight it.

    One of the big advantages of this approach, Cui said, is that the new collector should be easy to manufacture and also cheaper, because it replaces some of the copper with an inexpensive polymer. So scaling it up for commercial production, he said, “should be very doable.” The researchers have applied for a patent through Stanford, and Cui said they will be contacting battery manufacturers to explore the possibilities.

    This work was supported by the DOE’s Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office under the eXtreme Fast Charge Cell Evaluation of Lithium-ion Batteries (XCEL) program.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Stanford University campus. No image credit

    Stanford University

    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

    Stanford University Seal

    SLAC National Accelerator Lab


    SLAC/LCLS


    SLAC/LCLS II projected view

    SLAC LCLS-II Undulators The Linac Coherent Light Source’s new undulators each use an intricately tuned series of magnets to convert electron energy into intense bursts of X-rays. The “soft” X-ray undulator stretches for 100 meters on the left side of this hall, with the “hard” x-ray undulator on the right. Credit: Alberto Gamazo/SLAC National Accelerator Laboratory.


    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

    SSRL and LCLS are DOE Office of Science user facilities.

     
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