From Symmetry: “How to break a theory”

From Symmetry

DOE’s Fermi National Accelerator Laboratory(US) Wilson Hall.

DOE’s SLAC National Accelerator Laboratory campus with world’s first x-ray laser- the Linac Coherent Light Source (LCLS) unveiled in 2009.

03/08/22
Sarah Charley

When a theory breaks, you learn how to build it better.

In 1859, a French astronomer noticed that gradual changes to Mercury’s orbit could not be explained by Isaac Newton’s concept of gravity.

“Mercury is within the solar system, where Newton’s laws had worked perfectly, and continue to work perfectly, in almost all cases,” says Sophie Renner, a fellow in the CERN Theory Group. “But for some reason, they saw a discrepancy.”

Astronomers attributed the observation to a missing variable, such as an unseen planet slowly tugging Mercury off course. But Mercury’s mysterious playmate was never found.

That’s because their equations didn’t need a new variable; their theory needed a revolution.

Half a century later, scientists found the explanation for Mercury’s behavior: The sun was stretching spacetime and creating a gravity well that slowly changed Mercury’s path. This revelation brought to light the limits of Newtonian physics—and validated Albert Einstein’s theory of general relativity.

These fractures between prediction and observation are what physicists look for.

“We want to break theories for the same reason you want to break software,” says Cynthia Keeler, an assistant professor at Arizona State University. “You have to stress-test it and find out what its boundaries are. When a theory breaks, you learn how to build it better.”

When the CMS and ATLAS experiments at CERN saw an unexpected bump in their data in 2016, theorists submitted nearly 500 papers speculating about what new physics it might reveal. (When the experiments collected more data, the bump disappeared.)

The European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH)[CERN] Compact Muon Solenoid Detector.

The European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH)[CERN] ATLAS another view Image Claudia Marcelloni ATLAS CERN.

But rigorous experimental testing is only one of the many ways to break a theory. Physicists constantly run quality-control checks designed to crack, bend and extend their favorite mathematical models of the universe.

Ask weird questions

Einstein had a wild imagination. He asked himself questions like: What would he feel if he rode an elevator through outer space? What would he see if he chased a beam of light?

Other daydreamers might not have moved beyond wondering. But Einstein had a background in physics and friends with advanced degrees in mathematics. His thought experiments seeded deeper investigations that eventually showed the limitations of Newtonian mechanics.

“What Einstein did was expose internal paradoxes of the theory itself,” says Stephon Alexander, a physics professor at Brown University. “It’s like looking at a picture of something beautiful, but then finding a new angle and the picture isn’t as beautiful or elegant as you thought.”

Theorists must look for every possible angle, Alexander says. “As a theorist, you have the responsibility to strive for mastery and at the same time, be willing to look at things from the outside-in.”

Today’s thought experiments sound just as bizarre as Einstein’s from 100 years ago. The internal paradoxes they reveal are just as gnarly.

For example: “If I build a black hole out of a bunch of dictionaries, can I find the information in those dictionaries?” Keeler says. “Quantum mechanics says the information should be preserved—maybe it’s hard to get because it’s all mixed up, but it shouldn’t go away.

“Black holes seem to contradict that. We’ve had 50 years of discussions over this problem.”

Check the math

Theories tell stories. What are the smallest pieces of matter? What are their characteristics? What are their relationships? What is their destiny?

But unlike the stories of Shakespeare or Kurosawa, a physics theory is told in the language of mathematics. If the math doesn’t check out, neither does the theory.

“A lot if it is asking, ‘Is this legal?’” Keeler says. “You might write down something that seems mathematically consistent and then run into problems later. You have to ask, could any universe be constructed with this, or would it fall apart?”

Quantum field theory, which describes physics at subatomic scales, makes many mathematicians cringe because of its “algebraic shenanigans,” says Dorota Grabowska, a fellow in the CERN Theory Group. “If I had a conversation with a mathematician about quantum field theory, they would start crying. It’s like when your mom tells you to clean your room, so you shove everything in the closet. It looks fine, but please don’t open the closet.”

Quantum field theory is rife with something mathematicians can’t stand: unresolved infinities. In a 1977 essay, Nobel Laureate Steven Weinberg [The University of Texas-Austin (US)] wrote that “[Quantum field theory’s] reputation among physicists suffered frequent fluctuations… at times dropping so low that quantum field theory came close to be[ing] abandoned altogether.”

But quantum field theory survives because at the end of the day, it still makes predictions that check out with experiments, such as those at the Large Hadron Collider at CERN.

“The LHC is like our mother, and when she opens the closet, everything is magically organized,” Grabowska says.

Push it to extremes

Physics before the 20th century was mostly limited to the study of speeds, sizes and energies around the human scale. But then scientists started asking, what happens if we go faster? Or smaller? Or to a higher energy?

“A theory breaks when you try to calculate something new with the theory you have, and it gives you something absurd,” Renner says. “That’s what happened with the ultraviolet catastrophe of black-body radiation.”

Any blacksmith can attest that there is a link between the temperature of molten iron and the color and brightness of the light it emits. Classical physics did a pretty good job predicting the intensity of this light (hotter objects glow more brightly).

The trouble started when they pushed into the ultraviolet range.

Scientists calculated the amount of ultraviolet radiation an object burning at high temperature would emit. They found the prediction from classical physics in no way reflected reality, Renner says. “It went towards infinity at high frequencies, which is not what we see at all.”

The newly exposed edges of classical physics inspired Max Planck to reinterpret what energy actually is.

Planck proposed that unlike speed—which can be any value up to the speed of light—energy is more like a currency that comes in discrete bills called quanta. High-frequency light costs big quanta to shine, which explained the steep drop-off in the intensity of light radiating from an object in the ultraviolet range.

Today scientists are pushing far beyond the ultraviolet. UV light has around 3 to 30 electronvolts of energy; scientists at the Large Hadron Collider are currently studying the laws of physics at up to 13 trillion electronvolts.

The LHC’s enormous energy allowed physicists to finally find the legendary Higgs boson, which was theorized 50 years before its discovery and helps explain the origin of mass.

But this discovery illuminated what might be the limits of current theory in the form of the Standard Model, which physicists use to describe subatomic particles, forces and fields.

“If the Standard Model is valid across a large range of energies, we would expect the Higgs to have a much heavier mass than it does,” Renner says. “There’s no reason why the Higgs should be at the mass that it is, unless some new theory takes over at energies just out of our reach.”

Physicists are pushing the limits and searching for cracks that will let them see beyond the boundaries of the Standard Model’s effectiveness. Theory alone can go only so far, and many theorists are looking to experimentalists to light the way.

“Theoretical physics has always been driven by observations and detection,” Alexander says. “The field would be nothing without it. We’re relying on experimentalists to break the theory, and we’re really interested to see how they will surprise us.”

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Symmetry is a joint Fermilab/SLAC publication.

From Symmetry: “Argonaut project launches design effort for super-cold robotics”

From Symmetry

05/20/21
Brianna Barbu

Fermilab scientists are developing one of the most cold-tolerant robots ever made so they can monitor the interiors of particle detectors.

Illustration by Sandbox Studio, Chicago.

The Argonauts of Greek mythology braved sharp rocks, rough seas, magic and monsters to find the fabled Golden Fleece. A new robotics project at the Department of Energy’s Fermi National Accelerator Laboratory will share that same name and spirit of adventure.

Argonaut’s mission will be to monitor conditions within ultracold particle detectors by voyaging into a sea of liquid argon kept at minus 193 degrees Celsius—as cold as some of the moons of Saturn and Jupiter. The project, funded in March, aims to create one of the most cold-tolerant robots ever made, with potential applications not only in particle physics but also deep space exploration.

Argon, an element commonly found in the air around us, has become a key ingredient in scientists’ quests to better understand our universe. In its liquid form, argon is used to study particles called neutrinos in several Fermilab experiments, including MicroBooNE, ICARUS, SBND, and the next-generation international Deep Underground Neutrino Experiment. Liquid argon is also used in dark matter detectors like DEAP 3600, ARDM, MiniCLEAN, and DarkSide-50.

DOE’s Fermi National Accelerator Laboratory(US) MicrobooNE esperiment.

DOE’s Fermi National Accelerator Laboratory(US) ICARUS experiment.

DOE’s Fermi National Accelerator Laboratory(US) Short-Baseline Near Detector under construction.

FNAL DUNE LBNF (US) from FNAL to Sanford Underground Research Facility, Lead, South Dakota, USA

DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB (CA) deep in Sudbury’s Creighton Mine

MiniCLEAN Dark Matter experiment at SNOLAB (CA), Canada

DarkSide-50 at Gran Sasso (IT)

Liquid argon has many perks. It’s dense, which increases the chance that notoriously aloof neutrinos will interact. It’s inert, so electrons knocked free by a neutrino interaction can be recorded to create a 3D picture of the particle’s trajectory. It’s transparent, so researchers can also collect light to “time stamp” the interaction. It’s also relatively cheap—a huge plus, since DUNE will use 70,000 tons of the stuff.

But liquid-argon detectors are not without their challenges. To produce quality data, the liquid argon must be kept extremely cold and extremely pure. That means the detectors must be isolated from the outside world to keep the argon from evaporating or becoming contaminated. With access restricted, diagnosing or addressing issues inside a detector can be difficult. Some liquid-argon detectors, such as the ProtoDUNE detectors at CERN, have cameras mounted inside to look for issues like bubbles or sparks.

“Seeing stuff with our own eyes sometimes is much easier than interpreting data from a sensor,” says Jen Raaf, a Fermilab physicist who works on liquid-argon detectors for several projects including MicroBooNE, LArIAT and DUNE.

The idea for Argonaut came when Fermilab engineer Bill Pellico wondered if it would be possible to make the interior cameras movable. A robotic camera may sound simple—but engineering it for a liquid-argon environment presents unique challenges.

All of the electronics have to be able to operate in an extremely cold, high-voltage environment. All of the materials have to withstand the cooling from room to cryogenic temperatures without contracting too much or becoming brittle and falling apart. Any moving pieces must move smoothly without grease, which would contaminate the detector.

“You can’t have something that goes down and breaks and falls off and shorts out something or contaminates the liquid argon, or puts noise into the system,” Pellico says.

Pellico received funding for Argonaut through the Laboratory Directed Research and Development program, an initiative established to foster innovative scientific and engineering research at Department of Energy national laboratories. At this early stage of the project, the team—Pellico, mechanical engineers Noah Curfman and Mayling Wong-Squires, and neutrino scientist Flavio Cavanna—is focused on evaluating components and basic design aspects. The first goal is to demonstrate that it’s possible to power, move and communicate with a robot in a cryogenic environment.

“We want to prove that we can have, at a bare minimum, a camera that can move around and pan and tilt in liquid argon, without contaminating the liquid argon or causing any bubbles, with a reliability that shows that it can last for the life of the detector,” Curfman says.

The plan is to power Argonaut through a fiber-optic cable so as not to interfere with the detector electronics. The fist-sized robot will only get about 5-10 watts of power to move and communicate with the outside world.

The motor that will move Argonaut along a track on the side of the detector will be situated outside of the cold environment. It will move very slowly, but that’s not a bad thing—going too fast would create unwanted disturbances in the argon.

“As we get more advanced, we’ll start adding more degrees of freedom and more rails,” Curfman says.

Other future upgrades to Argonaut could include a temperature probe or voltage monitor, movable mirrors and lasers for calibrating the light detectors, or even extendable arms with tools for minor electronics repair.

Much of the technology Argonaut is advancing will be broadly applicable for other cryogenic environments—including space exploration. The project has already garnered some interest from universities and NASA engineers.

Deep space robots “are going to go to remote locations where they have very little power, and the lifetime has to be 20-plus years just like in our detectors, and they have to operate at cryogenic temperatures,” Pellico says. The Argonaut team can build on existing robotics know-how along with Fermilab’s expertise in cryogenic systems to push the boundaries of cold robotics.

Even the exteriors of active interstellar space probes such as Voyager 1 and 2 don’t reach temperatures as low as liquid argon—they use thermoelectric heaters to keep their thrusters and science instruments warm enough to operate.

“There’s never been a robotic system that operated at these temperatures,” Pellico says. “NASA’s never done it; we’ve never done it; nobody’s ever done it, as far as I can tell.”

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Symmetry is a joint Fermilab/SLAC publication.

From DOE’s Lawrence Berkeley National Laboratory (US): “Detector Technology Developed at Berkeley Lab Yields Unprecedented 3D Images Heralding Far Larger Application to Study Neutrinos”

From DOE’s Lawrence Berkeley National Laboratory (US)

May 13, 2021

Media Relations
media@lbl.gov
(510) 486-5183

Bill Schulz

A LArPix sensor with 4900 pixels under testing at Berkeley Lab before shipment to the University of Bern [Universität Bern](CH) for installation. Credit: Thor Swift, Berkeley Lab.

An experiment to capture unprecedented 3D images of the trajectories of charged particles has been demonstrated using cosmic rays as they strike and travel through a cryostat filled with a ton of liquid argon. The results confirm the capabilities of a novel detector technology for particle physics developed by researchers at Lawrence Berkeley National Laboratory (Berkeley Lab) in collaboration with several university and industrial partners.

Groundbreaking in scale for this new technology, the experiment at University of Bern [Universität Bern](CH) – directed remotely because of the COVID-19 pandemic – demonstrates readiness for a far larger and more ambitious project: the Fermi National Accelerator Laboratory DUNE/LBNF experiment (US), said Berkeley Lab scientist and team leader Dan Dwyer.

In just a few short years, the Berkeley Lab team has turned an ambitious concept called LArPix (liquid argon pixels) into a reality, Dwyer said. “We have overcome challenges in noise, power consumption, cryogenic compatibility, and most recently scalability/reliability by transferring many aspects of this technology to industrial fabrication.”

DUNE is a major new science facility being built by the U.S. Department of Energy (DOE) to study the properties of subatomic neutrinos that will be fired off underground from an accelerator at DOE’s Fermi National Accelerator Laboratory (Fermilab) near Chicago, Dwyer explained. Neutrinos are extremely light particles that interact weakly with matter ­– something researchers would like to understand better in their quest to answer fundamental questions about the universe.

Neutrinos produced by the Fermilab accelerator will pass through a near detector, instrumented with LArPix, on the Fermilab site before moving on to complete their 700-mile journey at a deep underground mine in South Dakota.

FNAL DUNE LBNF (US) from FNAL to Sanford Underground Research Facility, Lead, South Dakota, USA

LArPix is a leap forward in how to detect and record signals in liquid argon time projection chambers (LArTPCs), a technology of choice for future neutrino and dark matter experiments, Dwyer explained.

In a LArTPC, energetic subatomic particles enter the chamber and liberate or ionize electrons in the liquid argon. A strong, externally applied electric field drifts the electrons toward an anode side of the detector chamber where typically a plane of wires acts as sensitive antennae to read these signals and create stereoscopic 2D images of the event. But this technology is not enough to cope with the intensity and complexity of the neutrino events to be read for the DUNE Near Detector, Dwyer said.

“So, that’s where we at Berkeley Lab come in with this true 3D pixel readout provided by LArPix,” Dwyer said. “It will allow us to image DUNE neutrinos with high fidelity in a very busy environment.“

Using LArPix, he explained, the planes of wires are replaced with arrays of metallic pixels fabricated on standard electronic circuit boards, which can be readily manufactured. The low-power electronics, he said, are compatible with the demands of the cryogenic state of the liquid argon medium.

This latest achievement would not have been possible without the strong partnership with the ArgonCube Collaboration, a team of scientists focused on advancing LArTPC technology, centered at the University of Bern. For the Bern experiments, the researchers used a detector chamber with 80,000 pixels submerged in a ton of liquid argon at -330 degrees Fahrenheit. The system, he said, provided high fidelity, true 3D-imaging of cosmic ray showers as they traveled through the detector.

“This is a major milestone in the development of LArTPCs and the DUNE Near Detector,” said Michele Weber, Director of the Laboratory for High Energy Physics at the University of Bern who also serves as leader of the DUNE International Consortium responsible for building this detector.

“It’s vastly more complicated than anything that’s ever been built for LArTPCs,” said Brooke Russell, a postdoctoral fellow at Berkeley Lab and member of the LArPix team. With 80,000 channels, she said, the LArPix run at Bern far surpassed the previous state-of-the-art 15,000 channel LArTPC. “The level of complexity going from wires to pixels grew exponentially,” she said.

Partners from University of California at Berkeley (US), California Institute of Technology (US), Colorado State University (US), Rutgers University (US), University of California Davis (US), University of California Irvine (US), University of California Santa Barbara (US), University of Pennsylvania (US), and the University of Texas- Arlington (US) helped the researchers develop and test this much larger system.

For DUNE, Dwyer said, the system must scale to more than 10 million pixels that will sit in some 300 tons of liquid argon. He said this is doable both because of the modular nature of the detector chambers as well as the ability to tile LArPix boards made up of thousands of individual pixel detectors.

“This technology will enable the DUNE Near Detector to overcome signal pileup resulting from the high-intensity of the neutrino beam at the site,” Dwyer said. “It may also find use in the DUNE Far Detectors, other physics experiments, as well as non-physics applications,” he said.

At the DUNE Far Detectors, scientists will measure how the quantum flavor of the neutrinos changes in transit from the near detector.

By studying neutrinos, “we think we can learn something about the deeper mysteries of the universe – particularly such questions as why there’s more matter than antimatter in the universe,” Dwyer explained.

For DUNE to succeed, particle physicists “needed a level of thinking outside the box when it comes to detector technology,” Russell said. “For any breakthroughs in experimental particle physics of course you need novel ideas,” she added. “But if your hardware can’t deliver then you simply can’t make the measurement.”

This research is supported by the Department of Energy’s Office of Science, in part through the Office of Science Early Career Research Program.

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LBNL campus

LBNL Molecular Foundry

Bringing Science Solutions to the World

In the world of science, Lawrence Berkeley National Laboratory (Berkeley Lab) (US) is synonymous with “excellence.” Thirteen Nobel prizes are associated with Berkeley Lab. Seventy Lab scientists are members of the National Academy of Sciences (NAS), one of the highest honors for a scientist in the United States. Thirteen of our scientists have won the National Medal of Science, our nation’s highest award for lifetime achievement in fields of scientific research. Eighteen of our engineers have been elected to the National Academy of Engineering, and three of our scientists have been elected into the Institute of Medicine. In addition, Berkeley Lab has trained thousands of university science and engineering students who are advancing technological innovations across the nation and around the world.

Berkeley Lab is a member of the national laboratory system supported by the U.S. Department of Energy through its Office of Science. It is managed by the University of California(UC) and is charged with conducting unclassified research across a wide range of scientific disciplines. Located on a 202-acre site in the hills above the UC Berkeley campus that offers spectacular views of the San Francisco Bay, Berkeley Lab employs approximately 3,232 scientists, engineers and support staff. The Lab’s total costs for FY 2014 were $785 million. A recent study estimates the Laboratory’s overall economic impact through direct, indirect and induced spending on the nine counties that make up the San Francisco Bay Area to be nearly $700 million annually. The Lab was also responsible for creating 5,600 jobs locally and 12,000 nationally. The overall economic impact on the national economy is estimated at $1.6 billion a year. Technologies developed at Berkeley Lab have generated billions of dollars in revenues, and thousands of jobs. Savings as a result of Berkeley Lab developments in lighting and windows, and other energy-efficient technologies, have also been in the billions of dollars.

Berkeley Lab was founded in 1931 by Ernest Orlando Lawrence, a University of California, Berkeley(US) physicist who won the 1939 Nobel Prize in physics for his invention of the cyclotron, a circular particle accelerator that opened the door to high-energy physics. It was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab legacy that continues today.

History

1931–1941

The laboratory was founded on August 26, 1931, by Ernest Lawrence, as the Radiation Laboratory of the University of California, Berkeley, associated with the Physics Department. It centered physics research around his new instrument, the cyclotron, a type of particle accelerator for which he was awarded the Nobel Prize in Physics in 1939.

LBNL 88 inch cyclotron.

LBNL 88 inch cyclotron.

Throughout the 1930s, Lawrence pushed to create larger and larger machines for physics research, courting private philanthropists for funding. He was the first to develop a large team to build big projects to make discoveries in basic research. Eventually these machines grew too large to be held on the university grounds, and in 1940 the lab moved to its current site atop the hill above campus. Part of the team put together during this period includes two other young scientists who went on to establish large laboratories; J. Robert Oppenheimer founded DOE’s Los Alamos Laboratory(US), and Robert Wilson founded Fermi National Accelerator Laboratory(US).

1942–1950

Leslie Groves visited Lawrence’s Radiation Laboratory in late 1942 as he was organizing the Manhattan Project, meeting J. Robert Oppenheimer for the first time. Oppenheimer was tasked with organizing the nuclear bomb development effort and founded today’s Los Alamos National Laboratory to help keep the work secret. At the RadLab, Lawrence and his colleagues developed the technique of electromagnetic enrichment of uranium using their experience with cyclotrons. The “calutrons” (named after the University) became the basic unit of the massive Y-12 facility in Oak Ridge, Tennessee. Lawrence’s lab helped contribute to what have been judged to be the three most valuable technology developments of the war (the atomic bomb, proximity fuse, and radar). The cyclotron, whose construction was stalled during the war, was finished in November 1946. The Manhattan Project shut down two months later.

1951–2018

After the war, the Radiation Laboratory became one of the first laboratories to be incorporated into the Atomic Energy Commission (AEC) (now Department of Energy(US). The most highly classified work remained at Los Alamos, but the RadLab remained involved. Edward Teller suggested setting up a second lab similar to Los Alamos to compete with their designs. This led to the creation of an offshoot of the RadLab (now the Lawrence Livermore National Laboratory(US)) in 1952. Some of the RadLab’s work was transferred to the new lab, but some classified research continued at Berkeley Lab until the 1970s, when it became a laboratory dedicated only to unclassified scientific research.

Shortly after the death of Lawrence in August 1958, the UC Radiation Laboratory (both branches) was renamed the Lawrence Radiation Laboratory. The Berkeley location became the Lawrence Berkeley Laboratory in 1971, although many continued to call it the RadLab. Gradually, another shortened form came into common usage, LBNL. Its formal name was amended to Ernest Orlando Lawrence Berkeley National Laboratory in 1995, when “National” was added to the names of all DOE labs. “Ernest Orlando” was later dropped to shorten the name. Today, the lab is commonly referred to as “Berkeley Lab”.

The Alvarez Physics Memos are a set of informal working papers of the large group of physicists, engineers, computer programmers, and technicians led by Luis W. Alvarez from the early 1950s until his death in 1988. Over 1700 memos are available on-line, hosted by the Laboratory.

The lab remains owned by the Department of Energy(US), with management from the University of California(US). Companies such as Intel were funding the lab’s research into computing chips.

Science mission

From the 1950s through the present, Berkeley Lab has maintained its status as a major international center for physics research, and has also diversified its research program into almost every realm of scientific investigation. Its mission is to solve the most pressing and profound scientific problems facing humanity, conduct basic research for a secure energy future, understand living systems to improve the environment, health, and energy supply, understand matter and energy in the universe, build and safely operate leading scientific facilities for the nation, and train the next generation of scientists and engineers.

The Laboratory’s 20 scientific divisions are organized within six areas of research: Computing Sciences; Physical Sciences; Earth and Environmental Sciences; Biosciences; Energy Sciences; and Energy Technologies. Berkeley Lab has six main science thrusts: advancing integrated fundamental energy science; integrative biological and environmental system science; advanced computing for science impact; discovering the fundamental properties of matter and energy; accelerators for the future; and developing energy technology innovations for a sustainable future. It was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab tradition that continues today.

Berkeley Lab operates five major National User Facilities for the DOE Office of Science(US):

The Advanced Light Source (ALS) is a synchrotron light source with 41 beam lines providing ultraviolet, soft x-ray, and hard x-ray light to scientific experiments.

LBNL/ALS

DOE’s Lawrence Berkeley National Laboratory(US)Advanced Light SourceAdvanced Light Source .

The ALS is one of the world’s brightest sources of soft x-rays, which are used to characterize the electronic structure of matter and to reveal microscopic structures with elemental and chemical specificity. About 2,500 scientist-users carry out research at ALS every year. Berkeley Lab is proposing an upgrade of ALS which would increase the coherent flux of soft x-rays by two-three orders of magnitude.

The Joint Genome Institute (JGI) supports genomic research in support of the DOE missions in alternative energy, global carbon cycling, and environmental management. The JGI’s partner laboratories are Berkeley Lab, Lawrence Livermore National Lab (LLNL), DOE’s Oak Ridge National Laboratory(US)(ORNL), DOE’s Pacific Northwest National Laboratory(US) (PNNL), and the HudsonAlpha Institute for Biotechnology(US). The JGI’s central role is the development of a diversity of large-scale experimental and computational capabilities to link sequence to biological insights relevant to energy and environmental research. Approximately 1,200 scientist-users take advantage of JGI’s capabilities for their research every year.

The LBNL Molecular Foundry(US) [above] is a multidisciplinary nanoscience research facility. Its seven research facilities focus on Imaging and Manipulation of Nanostructures; Nanofabrication; Theory of Nanostructured Materials; Inorganic Nanostructures; Biological Nanostructures; Organic and Macromolecular Synthesis; and Electron Microscopy. Approximately 700 scientist-users make use of these facilities in their research every year.

The DOE’s NERSC National Energy Research Scientific Computing Center(US) is the scientific computing facility that provides large-scale computing for the DOE’s unclassified research programs. Its current systems provide over 3 billion computational hours annually. NERSC supports 6,000 scientific users from universities, national laboratories, and industry.

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

Cray Cori II supercomputer at National Energy Research Scientific Computing Center(US) at DOE’s Lawrence Berkeley National Laboratory(US), named after Gerty Cori, the first American woman to win a Nobel Prize in science.

NERSC Hopper Cray XE6 supercomputer.

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.

The DOE’s Energy Science Network(US) is a high-speed network infrastructure optimized for very large scientific data flows. ESNet provides connectivity for all major DOE sites and facilities, and the network transports roughly 35 petabytes of traffic each month.

Berkeley Lab is the lead partner in the DOE’s Joint Bioenergy Institute(US) (JBEI), located in Emeryville, California. Other partners are the DOE’s Sandia National Laboratory(US), the University of California (UC) campuses of Berkeley and Davis, the Carnegie Institution for Science(US), and DOE’s Lawrence Livermore National Laboratory(US) (LLNL). JBEI’s primary scientific mission is to advance the development of the next generation of biofuels – liquid fuels derived from the solar energy stored in plant biomass. JBEI is one of three new U.S. Department of Energy (DOE) Bioenergy Research Centers (BRCs).

Berkeley Lab has a major role in two DOE Energy Innovation Hubs. The mission of the Joint Center for Artificial Photosynthesis (JCAP) is to find a cost-effective method to produce fuels using only sunlight, water, and carbon dioxide. The lead institution for JCAP is the California Institute of Technology(US) and Berkeley Lab is the second institutional center. The mission of the Joint Center for Energy Storage Research (JCESR) is to create next-generation battery technologies that will transform transportation and the electricity grid. DOE’s Argonne National Laboratory(US) leads JCESR and Berkeley Lab is a major partner.

From CERN (CH) Courier: “HL-LHC magnets enter production in the US”

From CERN (CH) Courier

13 January 2021
Matthew Chalmers editor.

Next generation BNL technicians Ray Ceruti, Frank Teich, Pete Galioto, Pat Doutney and Dan Sullivan with the second US quadrupole magnet for the HL-LHC to have reached design performance. Credit: BNL.

The significant increase in luminosity targeted by the high-luminosity LHC (HL-LHC) demands large-aperture quadrupole magnets that are able to focus the proton beams more tightly as they collide. A total of 24 such magnets are to be installed on either side of the ATLAS and CMS experiments [both below] in time for HL-LHC operations in 2027, marking the first time niobium-tin (Nb3Sn) magnet technology is used in an accelerator.

Nb3Sn is a superconducting material with a critical magnetic field that far exceeds that of the niobium-titanium presently used in the LHC magnets, but once formed it becomes brittle and strain-sensitive, which makes it much more challenging to process and use.

The milestone signals the end of the prototyping phase for the HL-LHC quadrupoles.

Following the first successful test of a US-built HL-LHC quadrupole magnet at Brookhaven National Laboratory (BNL) in January last year—attaining a conductor peak field of 11.4 T and exceeding the required integrated gradient of 556 T in a 150 mm-aperture bore—a second quadrupole magnet has now been tested at BNL at nominal performance. Since the US-built quadrupole magnets must be connected in pairs before they can constitute fully operational accelerator magnets, the milestone signals the end of the prototyping phase for the HL-LHC quadrupoles, explains Giorgio Apollinari of Fermilab, who is head of the US Accelerator Upgrade Projects (AUP). “The primary importance is that we have entered the ‘production’ period that will make installation viable in early 2025. It also means we have satisfied the requirements from our funding agency and now the US Department of Energy has authorised the full construction for the US contribution to HL-LHC.”

Joint venture

The design and production of the HL-LHC quadrupole magnets are the result of a joint venture between CERN, BNL, Fermilab and Lawrence Berkeley National Laboratory, preceded by the 15 year-long US LHC Accelerator Research Program (LARP).

The US labs are to provide a total of ten 9 m-long helium-tight vessels (eight for installation and two as spares) for the HL-LHC, each containing two 4.2 m-long magnets. CERN is also producing ten 9 m-long vessels, each containing a 7.5 m-long magnet. The six magnets to be placed on each side of ATLAS and CMS – four from the US and two from CERN – will be powered in series on the same electrical circuit.

The synergy between CERN and the US laboratories allowed us to considerably reduce the risks.

“The synergy between CERN and the US laboratories allowed us to considerably reduce the risks, have a faster schedule and a better optimisation of resources,” says Ezio Todesco of CERN’s superconductors and cryostats group. The quadrupole magnet programme at CERN is also making significant progress, he adds, with a short-model quadrupole having recently reached a record 13.4 T peak field in the coil, which is 2 T more than the project requirements. “The full series of magnets, sharing the same design and built on three sites, will also give very relevant information about the viability of future hadron colliders, which are expected to rely on massive, industrial production of Nb3Sn magnets with fields up to 16 T.”

Since the second US quadrupole magnet was tested in October, the AUP teams have completed the assembly of a third magnet and are close to completing the assembly of a fourth. Next, the first two magnets will be assembled in a single cold mass before being tested in a horizontal configuration and then shipped to CERN in time for the “string test” planned in 2023.

“In all activities at the forefront of technology, like in the case for these focusing Nb3Sn quadrupoles, the major challenge is probably the transition from an ‘R&D mentality’, where minor improvements can be a daily business, to a ‘production mentality’, where there is a need to build to specific procedures and criteria, with all deviations being formally treated and corrected or addressed,” says Apollinari. “And let’s not forget that the success of this second magnet test came with a pandemic raging across the world.”

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THE FOUR MAJOR PROJECT COLLABORATIONS

ATLAS

CERN/ATLAS detector

ALICE

CERN/ALICE Detector

CMS

LHCb

LHC

CERN map

SixTRack CERN LHC particles

From DOE’s Fermi National Accelerator Laboratory: “Undulator magnet for the optical stochastic cooling experiment in IOTA” Photo Study

FNAL Art Image by Angela Gonzales

From DOE’s Fermi National Accelerator Laboratory , an enduring source of strength for the US contribution to scientific research world wide.

FNAL IOTA project.

After the first electron beam was circulated in August 2018, the experimental program at the Fermilab Integrable Optics Test Accelerator (IOTA) continues with commissioning of machine and diagnostics and with the first beam-physics experiments.

Photo Study

The optical stochastic cooling experiment’s undulator magnet installed in the Fermilab Integrable Optics Test Accelerator, or IOTA, in November. Credit: Giulio Stancari.

This detail shows the the gap between the OSC undulator magnet coils and poles. Credit: Giulio Stancari.

Traveling through the magnet, the electron beam generates infrared light, which is used to detect its position and velocity. The OSC experiment will use for the first time this light to increase the density of the electron beam and therefore improve the performance of future high-energy physics experiments. Credit: Giulio Stancari.

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Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
collaborate at Fermilab on experiments at the frontiers of discovery.

From FNAL: Northern Illinois flourishes as accelerator R&D hub under Fermilab leadership

September 25, 2020

Steve Koppes

Only a handful of particle accelerators around the world can produce proton beams intense enough for use in neutrino experiments. Europe and Japan each has an accelerator chain. So does the U.S. Department of Energy’s Fermi National Accelerator Laboratory.

Fermilab, however, is the only laboratory that produces protons at energies suitable for both low- and high-energy neutrino experiments. In fact, it produces the most intense neutrino beam in the world. This is but one example of Fermilab’s accelerator prowess. The laboratory’s collaborations with nearby universities and research laboratories have established the northern Illinois region as a leader in multiple areas of particle accelerator science and technology.

“In Chicago we have a very strong academic environment, not only in physics, in fundamental science, but also in applied science as well as engineering,” said Sergei Nagaitsev, head of Fermilab’s accelerator science programs and a University of Chicago faculty member.

This has led to accelerator research collaborations with the Illinois Institute of Technology, Northern Illinois University, Northwestern University and the University of Chicago.

“The combined accelerator R&D portfolio of Fermilab and collaborating Illinois institutions covers nearly every facet of particle acceleration, from basic principles to applications of accelerators in industry,” said Fermilab Chief Technology Officer Sergey Belomestnykh.

A spectrum of discovery and invention

Together with its northern Illinois partners, Fermilab grapples with multiple scientific and engineering challenges that are vitally important to improving accelerator beams and experimental outcomes.

“It’s hard to point at where science ends and technology begins,” Nagaitsev said. “There is a spectrum of discovery on one side versus invention on the other side. Both require creativity from our scientists and engineers.”

Researchers at Fermilab, Illinois Institute of Technology, Northern Illinois University and the University of Chicago all use IOTA, the Integrable Optics Test Accelerator, a major component of the lab’s accelerator-science enterprise and one of only a few accelerators in the world dedicated to studying the physics of beams. Photo: Giulio Stancari, Fermilab.

The physics of beams

The challenges on the accelerator science side relate to the physics of the beam itself.

Scientists work to produce beams of higher quality, which is connected to properties such as beam size and spread; achieve better measurements and control of beams down to the level of individual particles; predict beam behavior with better fidelity using computer simulations; and produce beams of higher intensity.

“Our particle physics experiments, especially the neutrino experiments, are hungry for intense proton beams delivered to the target,” Nagaitsev said.

To investigate problems in beam physics, Fermilab operates the Integrable Optics Test Accelerator, called IOTA, a major component of the lab’s accelerator-science enterprise and one of only a few accelerators in the world dedicated to studying the physics of beams. Researchers at Fermilab, IIT, NIU and the University of Chicago all use IOTA. Their work includes studies of electron and proton beams in rings, and their results will directly affect the Fermilab high-intensity proton rings used for neutrino and other particle physics research. Nagaitsev and his colleagues will also soon aim to demonstrate a new beam cooling technique called optical stochastic cooling — a novel way to improve the beam’s quality.

Science and technology of superconductivity

Science and technology of superconductivity is critical for building modern particle accelerators. Superconducting radio-frequency cavities – structures that impart energy to a particle beam – provide high levels of acceleration, making it more efficient, while high-field superconducting magnets allow tighter bending of particle trajectories, thus reducing the footprint of future accelerators. Members of Fermilab’s Applied Physics and Superconducting Technology Division are at the forefront of this field.

“It’s a cool blend of basic and applied science. We’re applying our understanding of the principles of materials science to giant particle-accelerating machines,” Belomestnykh said. “In turn, these machines enable us to scrutinize matter’s fundamental constituents.”

In July, Fermilab set the new world record for field strength for a superconducting accelerator dipole magnet – 14.5 teslas. And it is ambitiously setting its sights on developing magnets that can generate a field of 20 teslas — about 2,000 times higher than a strong refrigerator magnet.

Among achievements in superconducting radio-frequency technology, Fermilab researchers have discovered ways to significantly boost the cavity’s efficiency and accelerating field, both of which are crucial for future particle accelerators. And it turns out that these cavities, developed for accelerators, find applications in somewhat unexpected areas. They are leading candidates for scalable quantum computing technology thanks to the exceptionally long times they can maintain energy. The same technology has proven to be very useful in a search for elusive dark matter particles, such as dark photons.

Here, too, Fermilab collaborates with regional partners. For example, scientists at the Center for Applied Physics and Superconducting Technologies, known as CAPST, a collaboration between Fermilab and nearby Northwestern University, are exploring the upper limits of superconductivity to design and build more powerful and efficient accelerator components.

“The importance of superconductivity research for particle accelerators can not be overstated,” said Fermilab Deputy Chief Technology Officer and CAPST Co-Director Anna Grassellino. “We’re making great strides in this area in northern Illinois.”

Scientists at Fermilab are studying superconductivity to design and build more powerful and efficient accelerator components. Several Fermilab and Northwestern University scientists are part of Center for Applied Physics and Superconducting Technologies to explore the upper limits of superconductivity. Photo: Reidar Hahn, Fermilab.

Targets and beams

There’s also the science and technology of targetry: engineering materials to withstand the powerful particle beams smashing into them.

“Suppose we resolve the challenge of making beams very intense. Then you put them on a target and the target melts,” Nagaitsev said. “There has to be continuing research on how to make the targets more robust so that when the science delivers high-intensity beams, the target can take it.”

Toward autonomous accelerators

Fermilab scientists are exploring the use of artificial intelligence and machine learning for tuning accelerators, delivering flexible beam patterns and increasing a machine’s uptime. This steady move toward autonomous accelerator operation means that, one day, accelerators could run with little to no human intervention. Researchers are carrying out autonomous-accelerator studies at the Fermilab Science and Technology facility and at Fermilab’s PIP-II Injector Test Facility, a proving ground for the future heart of the lab’s accelerator complex, its PIP-II accelerator.

A number of these studies are being conducted as part of a program led by the University of Chicago.

And in the next five years or so, Fermilab’s accelerator researchers would like to build an electron injector for testing a potential way to do large-scale quantum computing.

“Fermilab has many interesting research plans for both near and far future,” Nagaitsev promised.

Accelerator applications

The use of accelerator technology goes beyond the academic. The world’s more than 30,000 operating particle accelerators also shrink tumors, make better tires, spot suspicious cargo, clean up dirty drinking water and help design drugs.

To facilitate the application of accelerators for societal benefit, Fermilab established the IARC at Fermilab (formerly known as the Illinois Accelerator Research Center), a technology development hub that connects scientists with members of industry. Industry partners are welcome to use the lab’s facilities to try out accelerator-related concepts. For example, IARC’s Accelerator Applications Development and Demonstration Facility, known as A2D2, is a test platform experts can use to evaluate new ideas for electron-beam applications.

“We have a wonderful concentration of accelerator expertise at Fermilab and in northern Illinois, and we’re facilitating cross-pollination with people who are innovating accelerator-based technologies for our everyday lives,” said Tim Meyer, head of Fermilab Technology Engagements. “By putting our heads together, by sharing our capabilities and facilities, we’re discovering uses for particle accelerators we wouldn’t otherwise.”

One of IARC’s goals is to make the technologies developed for science more widely available for commercial applications. For example, experts at IARC are developing a compact, mobile, superconducting particle accelerator that would fit on a truck for a variety of applications. To help realize that goal, they’ve also developed a new cooling method to reduce the bulk of the traditional infrastructure needed to cool it to cryogenic temperatures.

IARC at Fermilab is a technology development hub that connects scientists with members of industry. Photo: Reidar Hahn, Fermilab.

Accelerating the workforce

The potential of accelerators is boundless, so accelerator research is a strong draw for early-career scientists. Perhaps this explains why Mike Syphers, an NIU research professor of physics, has yet to see a saturated demand for accelerator scientists, even as large projects have come and gone.

The U.S. Particle Accelerator School, he noted, attracts near-record-setting numbers of students every year. Fermilab hosts and manages this national, graduate-level program, which provides training and workforce development in the science and technology of charged-particle accelerators and associated systems.

Multiple training programs will help develop young scientists to help realize the field’s future plans.

The Joint University-Fermilab Doctoral Program in Accelerator Physics and Technology, for example, has graduated 53 Ph.D. students since its establishment in 1985. Three more are currently in the pipeline.

Students study at the U.S. Particle Accelerator School hosted by Northern Illinois University in 2017. USPAS is just one particle accelerator science program in which Fermilab participates. Others include The Joint University-Fermilab Doctoral Program in Accelerator Physics and Technology and the Chicagoland Accelerator Science Traineeship, launched by NIU and IIT. Photo: USPAS.

A related effort, launched by NIU and IIT and funded with $1.9 million from the U.S. Department of Energy, is the Chicagoland Accelerator Science Traineeship. The traineeships will provide up to two years of funding for graduate students at NIU and IIT to prepare them for careers in accelerator science and technology. Fermilab also participates in two other similar programs: the Accelerator Science and Engineering Traineeship at Michigan State University and the Ernest Courant Traineeship in Accelerator Science & Engineering at Stony Brook University.

Two Fermilab internships attract students interested in particle accelerator physics and technology to the lab: The Lee Teng Internship is a joint program between Fermilab and neighboring Argonne National Laboratory for undergraduate students. The Helen Edwards Summer Internship brings European physics and engineering students to Fermilab.

“The field has continued to grow as the use of particle accelerators has expanded beyond national laboratories and pure scientific research,” Syphers said. “Various applications of accelerators and medical uses have driven further demand for people with knowledge of these devices.”

Building acceleration

Fermilab stands alone as a laboratory that can deliver the most intense beam of neutrinos in the world and accelerate beams for low- and high-energy neutrino experiments. This is thanks to a major accelerator upgrade currently under way at the lab: the Proton Improvement Plan-II. The heart of PIP-II will be the construction of a 215-meter-long superconducting accelerator that can generate powerful proton beams for the lab’s experiments.

Again, partnership is key: Argonne National Laboratory — a 30-mile jaunt from Fermilab — pursues accelerator R&D and serves as one of Fermilab’s U.S. partners in PIP-II. And Fermilab collaborates with Argonne accelerator research groups at the Advanced Photon Source, the Argonne Tandem Linac Accelerator System and the Argonne Wakefield Accelerator Facility.

With PIP-II scheduled to become fully operational in the late 2020s, NIU’s Syphers is already helping to develop plans for Fermilab’s next accelerator upgrade path.

“We have to start thinking now about what the next step would be beyond PIP-II because it would take years to plan,” Syphers said.

Fermilab and partners, including Argonne National Laboratory and Northern Illinois University, are designing and building the upcoming PIP-II accelerator, scheduled to become fully operational in the late 2020s. Photo: Reidar Hahn, Fermilab.

While prototyping and testing of PIP-II components take place, researchers already are discussing ideas for improvements beyond the new machine, for example, doubling the number of protons Fermilab’s accelerator chain would send to experiments.

Intense proton beams are necessary to produce the neutrinos for the international Deep Underground Neutrino Experiment, or DUNE, hosted by Fermilab, and its Long-Baseline Neutrino Facility. By studying neutrinos, the most abundant matter particles in the universe, DUNE discoveries could revolutionize cosmological research.

PIP-II boasts collaborators beyond Illinois borders: It is the only accelerator project in the U.S. that receives major international contributions.

Once operational, PIP-II will dramatically boost Fermilab’s proton production for DUNE and future research programs.

“We are always innovating technologies to help design and build the leanest and most powerful machines we can for discovery,” Belomestnykh said. “In sharing those innovations with our global partners, we’re helping advance accelerator technology not just in Illinois, but around the world.”

For example, together with other DOE national laboratories, Fermilab leads the U.S. effort to design, build and test next-generation focusing magnets for upgrading the Large Hadron Collider at CERN and is building superconducting cryomodules for the Linac Coherence Light Source-II project, a revolutionary X-ray laser under construction at SLAC National Accelerator Laboratory.

“Accelerator science and technology is one Fermilab’s core competencies. Together with our regional partners, we are striving to make Chicagoland the next Silicon Valley for particle accelerators and their applications,” Nagaitsev said. “With the unparalleled wealth of accelerator knowledge and activity here in one of the tech hubs of the country, we’re very well positioned to do just that.”

Fermilab accelerator R&D is supported by the DOE Office of Science.

Fermilab is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit science.energy.gov.

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Northern Illinois flourishes as accelerator R&D hub under Fermilab leadership

From Fermi National Accelerator Lab: “Searching for millicharged particles”

FNAL Art Image by Angela Gonzales

From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

July 17, 2020
Yu-Dai Tsai

[I am in the hospital and copy/paste for images is not working (Thankyou RWJ Barnabas Robert Wood Johnson Hospital. See the full article for images. All images which show are a part of the .html template I have built for the institution.)

Ever since Robert Millikan’s 1909 discovery of electric charge and, later, the discovery of the quark, scientists have postulated electric charge to come in discrete units, and the minimal electric charge has been believed to be carried by quarks. Yet theories still postulate that particles can carry much smaller charges — significantly smaller than that of quarks.

Scientists, including Fermilab researchers, have proposed a new experiment to help search for these “millicharged particles.” The proposal is inspired by analyses based on results from several neutrino experiments. The potential discovery would shatter the current Standard Model paradigm and open a window to new physics.

The new proposed experiment is called FerMINI [https://arxiv.org/abs/1812.03998] which has the ability to search for millicharged particles in the MeV/c2 to few GeV/c2 mass range.

FerMINI builds on previous analyses [https://inspirehep.net/literature/1708533]. A group of theoretical physicists showed that data from neutrino experiments MiniBooNE at Fermilab, the Liquid Scintillator Neutrino Detector at Los Alamos National Laboratory, and Super-Kamiokande Observatory in Japan limits the possible range of mass and electric charge that millicharged particles can have. Their findings narrow the region where scientists should look for millicharged particles. Independent and detailed millicharge analyses were studied for the ArgoNeuT neutrino experiment and conducted by the ArgoNeuT collaboration.

The search could extend beyond MiniBooNE and LSND to other Fermilab neutrino experiments, including MicroBooNE and the Short-Baseline Near Detector. Further, experiments such as the international, Fermilab-hosted Deep Underground Neutrino Experiment, or DUNE, and CERN’s proposed experiment, the Search for Hidden Particles, called SHiP, have the potential to discover millicharged particles in mass ranges that have yet to be experimentally tested. This research may have implications for their detector designs and analysis techniques.

The FerMINI detector can sense millicharged particles produced in the Fermilab proton beam when it hits a fixed target. It detects multiple scintillation hits in a small time window as the millicharged-particle signature. The detector technology is inspired by the milliQan experiment, a proposed search at the Large Hadron Collider at CERN, some of whose collaborators are also involved in the FerMINI project.

The search could potentially help explain the nature of dark matter, as the hypothetical particle could contribute to a fraction of the universe’s dark matter abundance. For example, scientists on the Experiment to Detect the Global EoR Signature, or EDGES, recently reported an anomaly in the 21-centimeter hydrogen absorption spectrum from the early universe. The discovery of millicharged particles as a fraction of dark matter might explain the anomaly.

This type of fractional dark matter candidate, with sizable coupling to Standard Model particles, would be hard for underground direct-detection experiments to detect, because the dark matter particles would lose their kinetic energy through their interaction with Earth’s atmosphere and crust before they reach the underground detectors. The Fermilab experiments thus have advantages in detecting such particles since they can directly produce these particles from the proton beam with a high energy.

We now know where we can look in searching for these millicharged particles, given available capabilities. By combining detector technology with existing and planned high-intensity proton beams provided by Fermilab, we can advance our search for these mysterious particles, overturning our understanding of the structure of nature’s fundamental constituents.

The FerMINI collaboration, based at Fermilab, comprises 10 institutions.

This work is supported by the DOE Office of Science.

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Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
collaborate at Fermilab on experiments at the frontiers of discovery.

From Fermi National Accelerator Lab: “CMS collaboration publishes 1,000th paper”

FNAL Art Image by Angela Gonzales

From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

June 22, 2020
Boaz Klima

We are proud to share with you the exciting news that on Friday, June 19, CMS reached a momentous milestone by submitting its 1,000th paper for publication [Physical Review Letters]. In doing so, CMS became the first experiment in the history of HEP to reach this outstanding total of papers.

CERN/CMS Detector

The very first paper published by the CMS collaboration as a whole was a description of the detector, submitted early in 2008. This was followed in 2009 by a series of papers describing the preoperation tuning of the apparatus using cosmic rays. The first publications of physics results based on LHC collisions appeared very soon after the LHC commenced operation at the end of 2009, and they have been issued at an average rate of about 100 papers per year since then. The publications timeline of collider-data papers split by physics topics is available on the CMS publications webpage.

The scientific impact of CMS publications has been at the highest level. Approximately a third are published as letters in Physical Review Letters or Physics Letters B, where the standards for significance and timeliness are even more stringent than those required for longer articles. Indeed, several CMS letters have been singled out for special recognition as “Editor’s Selection,” a testament to the utmost importance of those results.

By happy coincidence, the 1,000th CMS paper has been submitted close to the eighth anniversary of the most notable paper submitted so far, that reporting the observation of the Higgs boson, paper number 183, which was submitted in July 2012. The discovery of the Higgs boson led to a Nobel Prize.

Not only has the number of papers produced by CMS reached an unprecedented level, but the diversity of physics topics covered is also unparalleled. Just one decade ago the high-energy physics field exploited three different types of accelerators to pursue separately research at the energy frontier, the intensity frontier and on heavy-ion collisions under extreme conditions. In contrast, the advanced design of the CMS detector, made possible by a long program of R&D, and the remarkable flexibility of the LHC accelerator, have enabled CMS to publish world-class results probing all three boundaries of knowledge.

The exceptional success of CMS is a testimony to the skill and dedication of the collaboration, and credit for reaching the milestone of 1,000 publications belongs to all its members.

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Please help promote STEM in your local schools.

Stem Education Coalition

Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
collaborate at Fermilab on experiments at the frontiers of discovery.

From Fermi National Accelerator Lab: “Interview with Nobel laureate Carlo Rubbia about neutrino research” Video

FNAL Art Image by Angela Gonzales

From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

In this 5-minute video, Nobel laureate Carlo Rubbia explains why mysterious particles called neutrinos could be the key to understanding the nature of the universe. He talks about the search for a fourth type of neutrino and why the universe would not exist without neutrinos. He describes how scientists aim to unveil the secrets of the neutrino with the ICARUS (https://icarus.fnal.gov) and DUNE (https://fnal.gov/dune) neutrino experiments, hosted by Fermilab (https://fnal.gov). He recalls why early in his career he chose liquid argon as his material of choice to collect information about neutrino interactions with matter.

FNAL/ICARUS

FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA

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Please help promote STEM in your local schools.

Stem Education Coalition

Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
collaborate at Fermilab on experiments at the frontiers of discovery.

From Fermi National Accelerator Lab: “Silicon detector R&D for future high-energy physics experiments”

FNAL Art Image by Angela Gonzales

From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

June 19, 2020
Ron Lipton

Our ability to explore the physics of elementary particles depends on the sensors we use to translate flows of energy from particle collisions in our accelerators into electronic pulses in our detectors. The patterns of these pulses are used to reconstruct the underlying particles and their interactions. At the core of the mammoth detector assemblies and snugly surrounding the beam pipes are arrays of silicon sensors. These sensors, derived from integrated circuit technology, provide detailed patterns of interactions to micron-level (40 millionths of an inch) precision, with subnanosecond timing and low mass. The active area of these arrays has increased from a few square centimeters in experiments in the 1980s to 200 square meters in the CMS and ATLAS trackers at the Large Hadron Collider at CERN.

CERN/CMS Detector

CERN ATLAS Credit CERN SCIENCE PHOTO LIBRARY

The CMS high-granularity calorimeter, or HGCal, will use 600 square meters of silicon. The precision of these detectors enables unique identification of heavy quarks (bottom and charm) that travel a fraction of a millimeter before they decay. The precision was crucial, for example, in the discoveries of the top quark in 1995, CP violation and mixing in the B meson system, and the Higgs boson in 2012.

Research and development to improve the characteristics and develop better silicon detectors with the use of new technologies continue as we upgrade the existing detectors for better performance and develop designs for experiments at future generations of accelerators.

Working with collaborating laboratories and industrial partners, Fermilab researchers have developed and demonstrated the first three-layer 3-D bonded devices. This shows a three-layer 3-D chip stack. Image courtesy of Ron Lipton

The 3-D integration of pixelated sensors with readout chips was an infant technology when we began R&D in 2006. The 3-D interconnection technique (now called hybrid bonding by the semiconductor industry) can replace the large, costly, solder bump interconnect technology with one that can be directly integrated into semiconductor process lines. It reduces the minimum spacing between pixels from about 50 microns to three, allows multilayer stacked connections through the body of the semiconductor, and dramatically reduces the capacitance of the interconnect, increasing speed and reducing electronic noise. Working with collaborating laboratories and industrial partners, we have developed and demonstrated the first three-layer 3-D bonded devices, with two electronics layers occupying only 35 microns in height, down from the usual hundreds. This hybrid bonding technology is now probably in your smart phone camera.

Schematic of the stacked layers. Image courtesy of Ron Lipton

Future accelerators, including the High-Luminosity LHC, will produce collisions at a rate many times higher than the current LHC. The complexity of these collision events puts a premium on fast timing and recognition of very complex patterns of energy deposited in detectors. A possibility we are exploring is the induced-current detector. 3-D technology allows us to combine small pixels and low electronic noise with sophisticated electronics. The sensitivity and timing capabilities are now so good that we can measure the detailed shape of pulses due to charge movement deep in the silicon. This pattern of pulse shapes can give us much more information than the usual measurement of only the total charge. If this idea works, a single layer of silicon could measure timing to picoseconds, position to microns, as well as track angle, compressing multiple layers of sensor into one. This would greatly increase the power of detectors to select and process interesting events at very high speed. Work is under way on simulations of these effects and collaboration with industry on a 3-D demonstrator.

Another way to address the experimental challenges is to improve the time resolution of silicon detectors. This can be done by designing the silicon to provide internal gain, providing a larger signal with a faster rise time. The low-gain avalanche diode, or LGAD, was designed to accomplish this. The LGAD is a new technology, and improved variants are continually emerging. Fermilab has an extensive program of testing and qualifying these LGAD detectors in bench tests and in the Fermilab Test Beam. The work is a close collaboration with the foundries and with other institutes within CMS and ATLAS. This program has been crucial in the validation and adoption of LGAD technology for the CMS upgrade endcap timing layer.

The current generation of LGADs suffers from dead regions at the edges of each pixel and has only moderate radiation hardness. This limits the pixel size and range of applicability of these devices. By changing the top layers of the sensors (AC coupling) and adding a layer buried below the surface (buried gain layer) we can both eliminate most of the dead region and provide for a more well-defined gain that is also more resistant to radiation. First demonstrators are now being fabricated in collaboration with industry and universities.

Researchers are developing 8-inch sensors, seen here on a probe station at SiDet, for the CMS HGCal. Photo courtesy of Ron Lipton

Finally, the very large area of the CMS HGCal prompted us to begin the development of large-area sensors, producing the first HEP sensors on 8-inch silicon wafers in collaboration with industry. We developed the process flow with colleagues from other laboratories and integrated designs from contributors all over the world. We have demonstrated high quality 8-inch sensors thinned to 200 microns.

In this work, intense collaboration with the Fermilab ASIC group, support from CMS and DOE, infrastructure at SiDet, strong collaboration with laboratory, university and industrial partners, and the central contributions of summer students, graduate students, and postdocs have all been vital. These are all exciting developments and there is much more to do. As Richard Feynman said: “There is plenty of room at the bottom.”

See the full here.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
collaborate at Fermilab on experiments at the frontiers of discovery.