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  • richardmitnick 12:27 pm on October 15, 2021 Permalink | Reply
    Tags: "Holey metalens!", , , Physics   

    From Harvard University John A Paulson School of Engineering and Applied Sciences (US) : “Holey metalens!” 

    From Harvard University John A Paulson School of Engineering and Applied Sciences (US)

    at


    Harvard University (US)

    October 13, 2021
    Leah Burrows

    New metalens focuses light with ultra-deep holes.

    1
    Holey metalens! New metalens focuses light with ultra-deep holes.

    Metasurfaces are nanoscale structures that interact with light. Today, most metasurfaces use monolith-like nanopillars to focus, shape and control light. The taller the nanopillar, the more time it takes for light to pass through the nanostructure, giving the metasurface more versatile control of each color of light. But very tall pillars tend to fall or cling together. What if, instead of building tall structures, you went the other way?

    In a recent paper, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) developed a metasurface that uses very deep, very narrow holes, rather than very tall pillars, to focus light to a single spot.

    The research is published in Nano Letters.

    The new metasurface uses more than 12 million needle-like holes drilled into a 5-micrometer silicon membrane, about 1/20 the thickness of hair. The diameter of these long, thin holes is only a few hundred nanometers, making the aspect ratio — the ratio of the height to width — nearly 30:1.

    It is the first time that holes with such a high aspect ratio have been used in meta-optics.

    “This approach may be used to create large achromatic metalenses that focus various colors of light to the same focal spot, paving the way for a generation of high-aspect ratio flat optics, including large-area broadband achromatic metalenses,” said Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS and senior author of the paper.

    3
    A scanning electron microscopy (SEM) image (left) of the holes on side I of the holey metalens and (right) SEM image of the holes on side II of the metalens. Credit: Capasso Lab/Harvard SEAS.

    “If you tried to make pillars with this aspect ratio, they would fall over,” said Daniel Lim, a graduate student at SEAS and co-first author of the paper. “The holey platform increases the accessible aspect ratio of optical nanostructures without sacrificing mechanical robustness.”

    Just like with nanopillars, which vary in size to focus light, the holey metalens has holes of varying size precisely positioned over the 2 mm lens diameter. The hole size variation bends the light towards the lens focus.

    “Holey metasurfaces add a new dimension to lens design by controlling the confinement and propagation of light over a wide parameter space and make new functionalities possible,” said Maryna Meretska, a postdoctoral fellow at SEAS and co-first author of the paper. “Holes can be filled in with nonlinear optical materials, which will lead to multi-wavelength generation and manipulation of light, or with liquid crystals to actively modulate the properties of light.”

    The metalenses were fabricated using conventional semiconductor industry processes and standard materials, allowing it to be manufactured at scale in the future.

    The Harvard Office of Technology Development has protected the intellectual property relating to this project and is exploring commercialization opportunities.

    This project is supported by the Defense Advanced Research Projects Agency (DARPA), under award number HR00111810001. Lim is supported by A*STAR Singapore through the National Science Scholarship Scheme. Meretska is supported by NWO Rubicon Grant 019.173EN.010 from the Dutch Funding Agency NWO.

    See the full article here .

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    Stem Education Coalition

    Through research and scholarship, the Harvard John A. Paulson School of Engineering and Applied Sciences (US) will create collaborative bridges across Harvard and educate the next generation of global leaders. By harnessing the power of engineering and applied sciences we will address the greatest challenges facing our society.

    Specifically, that means that SEAS will provide to all Harvard College students an introduction to and familiarity with engineering and technology as this is essential knowledge in the 21st century.

    Moreover, our concentrators will be immersed in the liberal arts environment and be able to understand the societal context for their problem solving, capable of working seamlessly with others, including those in the arts, the sciences, and the professional schools. They will focus on the fundamental engineering and applied science disciplines for the 21st century; as we will not teach legacy 20th century engineering disciplines.

    Instead, our curriculum will be rigorous but inviting to students, and be infused with active learning, interdisciplinary research, entrepreneurship and engineering design experiences. For our concentrators and graduate students, we will educate “T-shaped” individuals – with depth in one discipline but capable of working seamlessly with others, including arts, humanities, natural science and social science.

    To address current and future societal challenges, knowledge from fundamental science, art, and the humanities must all be linked through the application of engineering principles with the professions of law, medicine, public policy, design and business practice.

    In other words, solving important issues requires a multidisciplinary approach.

    With the combined strengths of SEAS, the Faculty of Arts and Sciences, and the professional schools, Harvard is ideally positioned to both broadly educate the next generation of leaders who understand the complexities of technology and society and to use its intellectual resources and innovative thinking to meet the challenges of the 21st century.

    Ultimately, we will provide to our graduates a rigorous quantitative liberal arts education that is an excellent launching point for any career and profession.

    Harvard University campus

    Harvard University (US) is the oldest institution of higher education in the United States, established in 1636 by vote of the Great and General Court of the Massachusetts Bay Colony. It was named after the College’s first benefactor, the young minister John Harvard of Charlestown, who upon his death in 1638 left his library and half his estate to the institution. A statue of John Harvard stands today in front of University Hall in Harvard Yard, and is perhaps the University’s bestknown landmark.

    Harvard University (US) has 12 degree-granting Schools in addition to the Radcliffe Institute for Advanced Study. The University has grown from nine students with a single master to an enrollment of more than 20,000 degree candidates including undergraduate, graduate, and professional students. There are more than 360,000 living alumni in the U.S. and over 190 other countries.

    The Massachusetts colonial legislature, the General Court, authorized Harvard University (US)’s founding. In its early years, Harvard College primarily trained Congregational and Unitarian clergy, although it has never been formally affiliated with any denomination. Its curriculum and student body were gradually secularized during the 18th century, and by the 19th century, Harvard University (US) had emerged as the central cultural establishment among the Boston elite. Following the American Civil War, President Charles William Eliot’s long tenure (1869–1909) transformed the college and affiliated professional schools into a modern research university; Harvard became a founding member of the Association of American Universities in 1900. James B. Conant led the university through the Great Depression and World War II; he liberalized admissions after the war.

    The university is composed of ten academic faculties plus the Radcliffe Institute for Advanced Study. Arts and Sciences offers study in a wide range of academic disciplines for undergraduates and for graduates, while the other faculties offer only graduate degrees, mostly professional. Harvard has three main campuses: the 209-acre (85 ha) Cambridge campus centered on Harvard Yard; an adjoining campus immediately across the Charles River in the Allston neighborhood of Boston; and the medical campus in Boston’s Longwood Medical Area. Harvard University (US)’s endowment is valued at $41.9 billion, making it the largest of any academic institution. Endowment income helps enable the undergraduate college to admit students regardless of financial need and provide generous financial aid with no loans The Harvard Library is the world’s largest academic library system, comprising 79 individual libraries holding about 20.4 million items.

    Harvard University (US) has more alumni, faculty, and researchers who have won Nobel Prizes (161) and Fields Medals (18) than any other university in the world and more alumni who have been members of the U.S. Congress, MacArthur Fellows, Rhodes Scholars (375), and Marshall Scholars (255) than any other university in the United States. Its alumni also include eight U.S. presidents and 188 living billionaires, the most of any university. Fourteen Turing Award laureates have been Harvard affiliates. Students and alumni have also won 10 Academy Awards, 48 Pulitzer Prizes, and 108 Olympic medals (46 gold), and they have founded many notable companies.

    Colonial

    Harvard University (US) was established in 1636 by vote of the Great and General Court of the Massachusetts Bay Colony. In 1638, it acquired British North America’s first known printing press. In 1639, it was named Harvard College after deceased clergyman John Harvard, an alumnus of the University of Cambridge(UK) who had left the school £779 and his library of some 400 volumes. The charter creating the Harvard Corporation was granted in 1650.

    A 1643 publication gave the school’s purpose as “to advance learning and perpetuate it to posterity, dreading to leave an illiterate ministry to the churches when our present ministers shall lie in the dust.” It trained many Puritan ministers in its early years and offered a classic curriculum based on the English university model—many leaders in the colony had attended the University of Cambridge—but conformed to the tenets of Puritanism. Harvard University (US) has never affiliated with any particular denomination, though many of its earliest graduates went on to become clergymen in Congregational and Unitarian churches.

    Increase Mather served as president from 1681 to 1701. In 1708, John Leverett became the first president who was not also a clergyman, marking a turning of the college away from Puritanism and toward intellectual independence.

    19th century

    In the 19th century, Enlightenment ideas of reason and free will were widespread among Congregational ministers, putting those ministers and their congregations in tension with more traditionalist, Calvinist parties. When Hollis Professor of Divinity David Tappan died in 1803 and President Joseph Willard died a year later, a struggle broke out over their replacements. Henry Ware was elected to the Hollis chair in 1805, and the liberal Samuel Webber was appointed to the presidency two years later, signaling the shift from the dominance of traditional ideas at Harvard to the dominance of liberal, Arminian ideas.

    Charles William Eliot, president 1869–1909, eliminated the favored position of Christianity from the curriculum while opening it to student self-direction. Though Eliot was the crucial figure in the secularization of American higher education, he was motivated not by a desire to secularize education but by Transcendentalist Unitarian convictions influenced by William Ellery Channing and Ralph Waldo Emerson.

    20th century

    In the 20th century, Harvard University (US)’s reputation grew as a burgeoning endowment and prominent professors expanded the university’s scope. Rapid enrollment growth continued as new graduate schools were begun and the undergraduate college expanded. Radcliffe College, established in 1879 as the female counterpart of Harvard College, became one of the most prominent schools for women in the United States. Harvard University (US) became a founding member of the Association of American Universities in 1900.

    The student body in the early decades of the century was predominantly “old-stock, high-status Protestants, especially Episcopalians, Congregationalists, and Presbyterians.” A 1923 proposal by President A. Lawrence Lowell that Jews be limited to 15% of undergraduates was rejected, but Lowell did ban blacks from freshman dormitories.

    President James B. Conant reinvigorated creative scholarship to guarantee Harvard University (US)’s preeminence among research institutions. He saw higher education as a vehicle of opportunity for the talented rather than an entitlement for the wealthy, so Conant devised programs to identify, recruit, and support talented youth. In 1943, he asked the faculty to make a definitive statement about what general education ought to be, at the secondary as well as at the college level. The resulting Report, published in 1945, was one of the most influential manifestos in 20th century American education.

    Between 1945 and 1960, admissions were opened up to bring in a more diverse group of students. No longer drawing mostly from select New England prep schools, the undergraduate college became accessible to striving middle class students from public schools; many more Jews and Catholics were admitted, but few blacks, Hispanics, or Asians. Throughout the rest of the 20th century, Harvard became more diverse.

    Harvard University (US)’s graduate schools began admitting women in small numbers in the late 19th century. During World War II, students at Radcliffe College (which since 1879 had been paying Harvard University (US) professors to repeat their lectures for women) began attending Harvard University (US) classes alongside men. Women were first admitted to the medical school in 1945. Since 1971, Harvard University (US) has controlled essentially all aspects of undergraduate admission, instruction, and housing for Radcliffe women. In 1999, Radcliffe was formally merged into Harvard University (US).

    21st century

    Drew Gilpin Faust, previously the dean of the Radcliffe Institute for Advanced Study, became Harvard University (US)’s first woman president on July 1, 2007. She was succeeded by Lawrence Bacow on July 1, 2018.

     
  • richardmitnick 9:43 pm on October 13, 2021 Permalink | Reply
    Tags: "Einstein’s Principle of Equivalence verified in quasars for the first time", , , , , , Physics   

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) : “Einstein’s Principle of Equivalence verified in quasars for the first time” 

    Instituto de Astrofísica de Andalucía

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES)

    13/10/2021

    Evencio Mediavilla
    emg@iac.es

    1
    Artist impression of a quasar. Credit: M. Kornmesser/ European Southern Observatory [Observatoire européen austral][Europäische Südsternwarte](EU)(CL)

    According to Einstein’s theory of general relativity gravity affects light as well as matter. One consequence of this theory, based on the Principle of Equivalence, is that the light which escapes from a region with a strong gravitational field loses energy on its way, so that it becomes redder, a phenomenon known as the gravitational redshift. Quantifying this gives a fundamental test of Einstein’s theory of gravitation. Until now this test had been performed only on bodies in the nearby universe, but thanks to the use of a new experimental procedure scientists at the Instituto de Astrofísica de Canarias (IAC) and The University of Granada [Universidad de Granada] (ES) have been able to measure the gravitational redshift in quasars, and thus extend the test to very distant regions from where the light was emitted when our universe was young.

    Einstein’s Principle of Equivalence is the cornestone of the General Theory of Relativity, which is our best current description of gravity, and is one of the basic theories of modern physics. The principle states that it is experimentally impossible to distinguish between a gravitational field and an accelerated motion of the observer, and one of its predictions is that the light emitted from within an intense gravitational field should undergo a measurable shift to lower spectral energy, which for light means a shift to the red, which is termed “redshift”.

    This prediction has been well and very frequently confirmed close to the Earth, from the first measurements by R.V. Pound and G.A. Rebka at Harvard in 1959 until the most recent measurements with satellites. It has also been confirmed using observations of the Sun, and of some stars, such as our neighbour Sirius B, and the star S2 close to the supermassive black hole at the centre of the Galaxy. But to confirm it with measurements beyond the Galaxy has proved difficult, and there have been only a few tests with complicated measurements and low precision in clusters of galaxies relatively near to us in cosmological terms.

    The reason for this lack of testing in the more distant universe is the difficulty of measuring the redshift because in the majority of situations the effect of gravity on the light is very small. For that reason massive black holes with very strong gravitational fields offer promising scenarios for measuring gravitational redshifts. In particular the supermassive black holes found at the centres of galaxies, which have huge gravitational fields, offer one of the more promising scenarios to measure the gravitational redshift. They are situated at the centres of the extraordinarily luminous and distant quasars.

    A quasar is an object in the sky which looks like a star but is situated at a great distance from us, so that the light we receive from it was emitted when the universe was much younger than now. This means that they must be extremely bright. The origin of this huge power output is a disc of hot material which is being swallowed by the supermassive black hole at its centre. This energy is generated in a very small region, barely a few light days in size.

    In the neighbourhood of the black hole there is a very intense gravitational field and so by studying the light emitted by the chemical elements in this region (mainly hydrogen, carbon, and magnesium) we would expect to measure very large gravitational redshifts. Unfortunately the majority of the elements in quasar accretion discs are also present in regions further out from the central black hole where the gravitational effects are much smaller, so the light we receive from those elements is a mixture in which it is not easy to pick out clearly the gravitational redshifts.

    The measurements cover 80% of the history of the universe

    Now a team of researchers at the Instituto de Astrofísica de Canarias (IAC) and the University of Granada (UGR) have found a well defined portion of he ultraviolet light emitted by iron atoms from a region confined to the neighbourhood of the black hole. “Through our research related to gravitational lensing, another of the predictions of Einstein’s theory of General Relativity, we found that a characteristic spectal feature of iron in quasars seemed to be coming from a region very close to the black hole. Our measurements of the redshift confirmed this finding” explains Evencio Mediavilla, an IAC researcher, Professor at the Unversity of La Laguna(ULL) and first author of the article.

    Using this feature the researchers have been able to measure clearly and precisely the gravitational redshifts of many quasars and, using them, estimate the masses of the black holes. “This technique marks an extraordinary advance, because it allows us to measure precisely the gravitational redshifts of individual objects at great distances, which opens up important possibilities for the future” says Mediavilla.

    Jorge Jimenez Vicente, a researcher at the UGR, and co-author of the article, stressess the implications of this new experimental procedure, as it allows comparison of the measured redshift with the theoretcially predicted value: “this technique allows us for the first time to test Einstein’s Principle of Equivalence, and with it the basis of our understanding of gravity on cosmological scales.”

    This test of the Principle of Equivalence performed by these researchers is based on measurements which include active galaxies in our neighbourhood (some 13,800 million years after the Big Bang) out to individual quasars a large distances, whose light was emitted when the age of the universe was only some 2,200 million years, thus covering around 80% of the history of the universe. “The results, with a precision comparable to those of experiments carried out within our Galaxy, validate the Principle of Equivalence over this vast period of time” notes Jiménez-Vicente.

    The article has been published in the journal The Astrophysical Journal, and recently has been selected by The American Astronomical Society (US) which as published an interview with the researchers in the section “AAS Journal Author Series” of its YouTube channel, whose aim is to link the authors with their article, their personal histories, and the astronomical community in general.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) operates two astronomical observatories in the Canary Islands:

    Roque de los Muchachos Observatory on La Palma
    Teide Observatory on Tenerife.

    The seeing statistics at ORM make it the second-best location for optical and infrared astronomy in the Northern Hemisphere, after Mauna Kea Observatory Hawaii (US).

    Maunakea Observatories Hawai’i (US) altitude 4,213 m (13,822 ft)

    The site also has some of the most extensive astronomical facilities in the Northern Hemisphere; its fleet of telescopes includes the 10.4 m Gran Telescopio Canarias, the world’s largest single-aperture optical telescope as of July 2009, the William Herschel Telescope (second largest in Europe), and the adaptive optics corrected Swedish 1-m Solar Telescope.

    Gran Telescopio Canarias [Instituto de Astrofísica de Canarias ](ES) sited on a volcanic peak 2,267 metres (7,438 ft) above sea level.

    The observatory was established in 1985, after 15 years of international work and cooperation of several countries with the Spanish island hosting many telescopes from Britain, The Netherlands, Spain, and other countries. The island provided better seeing conditions for the telescopes that had been moved to Herstmonceux by the Royal Greenwich Observatory, including the 98 inch aperture Isaac Newton Telescope (the largest reflector in Europe at that time). When it was moved to the island it was upgraded to a 100-inch (2.54 meter), and many even larger telescopes from various nations would be hosted there.

    Teide Observatory [Observatorio del Teide], IAU code 954, is an astronomical observatory on Mount Teide at 2,390 metres (7,840 ft), located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It became one of the first major international observatories, attracting telescopes from different countries around the world because of the good astronomical seeing conditions. Later the emphasis for optical telescopes shifted more towards Roque de los Muchachos Observatory on La Palma.

     
  • richardmitnick 12:55 pm on October 13, 2021 Permalink | Reply
    Tags: "Scientists capture image of bizarre 'electron ice' for the first time", , , Physics, Wigner crystal — a strange honeycomb-pattern material inside another material made entirely out of electrons.   

    From Live Science (US) : “Scientists capture image of bizarre ‘electron ice’ for the first time” 

    From Live Science (US)

    10.12.21
    Ben Turner
    ben.turner@futurenet.com

    1
    The scanning tunnelling image of the graphene sheet shows the honeycomb imprint of the ‘electron ice’ underneath it. (Image credit: H. Li et al./Nature)

    Physicists have taken the first ever image of a Wigner crystal — a strange honeycomb-pattern material inside another material made entirely out of electrons.

    Hungarian physicist Eugene Wigner first theorized this crystal in 1934, but it’s taken more than eight decades for scientists to finally get a direct look at the “electron ice.” The fascinating first image shows electrons squished together into a tight, repeating pattern — like tiny blue butterfly wings, or pressings of an alien clover.

    The researchers behind the study, published on Sept. 29 in the journal Nature, say that while this isn’t the first time that a Wigner crystal has been plausibly created or even had its properties studied, the visual evidence they collected is the most emphatic proof of the material’s existence yet.

    “If you say you have an electron crystal, show me the crystal,” study co-author Feng Wang, a physicist at The University of California (US), told Nature News.

    Inside ordinary conductors like silver or copper, or semiconductors like silicon, electrons zip around so fast that they are barely able to interact with each other. But at very low temperatures, they slow down to a crawl, and the repulsion between the negatively charged electrons begins to dominate. The once highly mobile particles grind to a halt, arranging themselves into a repeating, honeycomb-like pattern to minimize their total energy use.

    To see this in action, the researchers trapped electrons in the gap between atom-thick layers of two tungsten semiconductors — one tungsten disulfide and the other tungsten diselenide. Then, after applying an electric field across the gap to remove any potentially disruptive excess electrons, the researchers chilled their electron sandwich down to 5 degrees above absolute zero. Sure enough, the once-speedy electrons stopped, settling into the repeating structure of a Wigner crystal.

    The researchers then used a device called a scanning tunneling microscope (STM) to view this new crystal. STMs work by applying a tiny voltage across a very sharp metal tip before running it just above a material, causing electrons to leap down to the material’s surface from the tip. The rate that electrons jump from the tip depends on what’s underneath them, so researchers can build up a picture of the Braille-like contours of a 2D surface by measuring current flowing into the surface at each point.

    But the current provided by the STM was at first too much for the delicate electron ice, “melting” it upon contact. To stop this, the researchers inserted a single-atom layer of graphene just above the Wigner crystal, enabling the crystal to interact with the graphene and leave an impression on it that the STM could safely read — much like a photocopier. By tracing the image imprinted on the graphene sheet completely, the STM captured the first snapshot of the Wigner crystal, proving its existence beyond all doubt.

    Now that they have conclusive proof that Wigner crystals exist, scientists can use the crystals to answer deeper questions about how multiple electrons interact with each other, such as why the crystals arrange themselves in honeycomb orderings, and how they “melt.” The answers will offer a rare glimpse into some of the most elusive properties of the tiny particles.

    See the full article here.

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    Please help promote STEM in your local schools.

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  • richardmitnick 12:35 pm on October 13, 2021 Permalink | Reply
    Tags: "Levitation yields better neutron-lifetime measurement", , , , , Physics,   

    From DOE’s Los Alamos National Laboratory (US) via Science Alert (US) : “Levitation yields better neutron-lifetime measurement” 

    LANL bloc

    From DOE’s Los Alamos National Laboratory (US)

    via

    ScienceAlert

    Science Alert (US)

    13 OCTOBER 2021
    MICHELLE STARR

    1
    TanyaLovus/iStock/Getty Images Plus.

    We now know, to within a tenth of a percent, how long a neutron can survive outside the atomic nucleus before decaying into a proton.

    This is the most precise measurement yet of the lifespan of these fundamental particles, representing a more than two-fold improvement over previous measurements. This has implications for our understanding of how the first matter in the Universe was created from a soup of protons and neutrons in the minutes after the Big Bang.

    “The process by which a neutron ‘decays’ into a proton – with an emission of a light electron and an almost massless neutrino – is one of the most fascinating processes known to physicists,” said nuclear physicist Daniel Salvat of The Indiana University (US) Bloomington.

    “The effort to measure this value very precisely is significant because understanding the precise lifetime of the neutron can shed light on how the universe developed – as well as allow physicists to discover flaws in our model of the subatomic universe that we know exist but nobody has yet been able to find.”

    The research was conducted at The Los Alamos National Science Center, where a special experiment is set up just for trying to measure neutron lifespans. It’s called the UCNtau project, and it involves ultra-cold neutrons (UCNs) stored in a magneto-gravitational trap.

    The neutrons are cooled almost to absolute zero, and placed in the trap, a bowl-shaped chamber lined with thousands of permanent magnets, which levitate the neutrons, inside a vacuum jacket.

    The magnetic field prevents the neutrons from depolarizing and, combined with gravity, keeps the neutrons from escaping. This design allows neutrons to be stored for up to 11 days.

    The researchers stored their neutrons in the UCNtau trap for 30 to 90 minutes, then counted the remaining particles after the allotted time. Over the course of repeated experiments, conducted between 2017 and 2019, they counted over 40 million neutrons, obtaining enough statistical data to determine the particles’ lifespan with the greatest precision yet.

    This lifespan is around 877.75 ± 0.28 seconds (14 minutes and 38 seconds), according to the researchers’ analysis. The refined measurement can help place important physical constraints on the Universe, including the formation of matter and dark matter.

    After the Big Bang, things happened relatively quickly. In the very first moments, the hot, ultra-dense matter that filled the Universe cooled into quarks and electrons; just millionths of a second later, the quarks coalesced into protons and neutrons.

    Knowing the lifespan of the neutron can help physicists understand what role, if any, decaying neutrons play in the formation of the mysterious mass in the Universe known as dark matter. This information can also help test the validity of something called the Cabibbo-Kobayashi-Maskawa matrix, which helps explain the behavior of quarks under the Standard Model of physics, the researchers said.

    “The underlying model explaining neutron decay involves the quarks changing their identities, but recently improved calculations suggest this process may not occur as previously predicted,” Salvat said.

    “Our new measurement of the neutron lifetime will provide an independent assessment to settle this issue, or provide much-searched-for evidence for the discovery of new physics.”

    The research has been accepted into Physical Review Letters.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    DOE’s Los Alamos National Laboratory (US) mission is to solve national security challenges through scientific excellence.

    LANL campus
    DOE’s Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is managed by Triad, a public service oriented, national security science organization equally owned by its three founding members: The University of California Texas A&M University (US), Battelle Memorial Institute (Battelle) for the Department of Energy’s National Nuclear Security Administration. Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    DOE’s Los Alamos National Laboratory (US) mission is to solve national security challenges through scientific excellence.

    LANL campus
    DOE’s Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is managed by Triad, a public service oriented, national security science organization equally owned by its three founding members: The University of California Texas A&M University (US), Battelle Memorial Institute (Battelle) for the Department of Energy’s National Nuclear Security Administration. Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.

     
  • richardmitnick 12:29 pm on October 12, 2021 Permalink | Reply
    Tags: "New study sheds light on molecular motion", , , Physics,   

    From University of Nottingham (UK) : “New study sheds light on molecular motion” 

    1

    From University of Nottingham (UK)

    11 October 2021
    Jane Icke – Media Relations Manager Science
    Email: jane.icke@nottingham.ac.uk
    Phone: 0115 7486462

    1
    Courtesy of Mònica Amabilino i Pérez.

    New research has shown how a synthetic self-made fibres can guide molecular movement that can be fuelled by light over long distances, a discovery that could pave the way for new ways to use light as a source of sustainable energy.

    Researchers from the University of Nottingham have for the first time used a path of assembled molecules liquids that travelling molecules can be propelled along by light. The research has been published today in Nature Chemistry.

    Professor David Amabilino from the School of Chemistry at the University of Nottingham is one of the lead researchers, he explains: “In living organisms, molecular motors travel along specific molecular paths, it is an essential part of cell function. We have shown that a synthetic self-made molecular fibre in a liquid behaves like a path for the movement of a molecular traveller over a distance 10,000 times its length. Light acts as the fuel to encourage the motion, while a molecular switch mixed into the system apparently propels the traveller on its way.”

    The team used interactions between oppositely charged chemical groups and created motion to this static system by introducing a switching molecule, that flaps back and forth quite quickly, into the fibres. Shining a light onto this weakens the traveller molecules interaction with the path as they move along it, which can be at some distance. If the molecule were our size, they would move the equivalent of 10 km.

    Heat is released when the switching molecules are irradiated, and that heat has a local effect that helps the traveller move, so the mechanical movement of the switch, and the heat that is released when it does, are important for making the system work.

    The technique the team used to observe these effects is a special optical microscope that allowed the simultaneous exciting of the molecules – making them move – and observation of them as they give light back out (the travelling molecules are fluorescent).

    Co-author on the study Mario Samperi adds: “The system we have prepared is very sensitive to the solvent in which the fibres are formed. In a liquid about the strength of strong whisky, the travelling molecules move along the fibres to another location, whereas when the liquid is the strength of weaker limoncello, rings of rearranged fibres are formed where the travellers have moved along and incorporated into the newly formed circular track.

    We want to be able to transport other molecules from one place to another in a controlled way, so that the travelling molecules can carry a package from one place to another, emulating nature, but using light as energy.”

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    2

    The University of Nottingham (UK) is a public research university in Nottingham, United Kingdom. It was founded as University College Nottingham in 1881, and was granted a royal charter in 1948. The University of Nottingham belongs to the elite research intensive The Russell Group Association .

    Nottingham’s main campus (University Park) with Jubilee Campus and teaching hospital (Queen’s Medical Centre) are located within the City of Nottingham, with a number of smaller campuses and sites elsewhere in Nottinghamshire and Derbyshire. Outside the UK, the university has campuses in Semenyih, Malaysia, and Ningbo, China. Nottingham is organised into five constituent faculties, within which there are more than 50 schools, departments, institutes and research centres. Nottingham has about 45,500 students and 7,000 staff, and had an income of £703.6 million in 2019/20, of which £105.0 million was from research grants and contracts. The institution’s alumni have been awarded a variety of prestigious accolades, including 3 Nobel Prizes, a Fields Medal, a Turner Prize, and a Gabor Medal and Prize. The university is a member of the Association of Commonwealth Universities (UK), The European University Association, the The Russell Group Association, Universitas 21, Universities UK, The Virgo Consortium, and participates in the Sutton Trust Summer School programme as a member of the Sutton 30.

     
  • richardmitnick 10:52 am on October 11, 2021 Permalink | Reply
    Tags: "Refuting a 70-year approach to predicting material microstructure", , Carnegie Mellon University - College of Engineering (US), , HEDM: high energy diffraction microscopy, , Physics   

    From Carnegie Mellon University – College of Engineering (US) : “Refuting a 70-year approach to predicting material microstructure” 

    From Carnegie Mellon University – College of Engineering (US)

    10.11.21

    Kaitlyn Landram
    Jocelyn Duffy

    Researchers at Carnegie Mellon University have developed a new microscopy technique that maps material microstructure in three dimensions; results demonstrate that the conventional method for predicting materials’ properties under high temperature is ineffective.

    A 70-year-old model used to predict the microstructure of materials doesn’t work for today’s materials, say Carnegie Mellon University researchers in Science. A microscopy technique developed by Carnegie Mellon and DOE’s Argonne National Laboratory (US) yields evidence that contradicts the conventional model and points the way toward the use of new types of characterizations to predict properties—and therefore the safety and long-term durability—of new materials.

    If a metallurgist discovered an alloy that could drastically improve an aircraft’s performance, it could take as long as 20 years before a passenger would be able to board a plane made of that alloy. With no way to predict how a material will change when it is subjected to the stressors of processing or everyday use, researchers use trial and error to establish a material’s safety and durability. This lengthy process is a significant bottleneck to materials innovation.


    Greg Rohrer: Polycrystalline Materials.

    Gregory Rohrer and Robert Suter of Carnegie Mellon University have uncovered new information that will help materials scientists to predict how the properties of materials change in response to stressors such as elevated temperatures. Using near-field high energy diffraction microscopy (HEDM), they found that the established model for predicting a material’s microstructure and properties does not apply to polycrystalline materials, and a new model is needed.

    To the eye, most commonly used metals, alloys, and ceramics used in industrial and consumer equipment and products appear to be uniformly solid. But at the microscopic level, they are polycrystalline, made up of aggregates of grains that have different size, shapes, and crystal orientations. The grains are tied together by a network of grain boundaries that shift when exposed to stressors, changing the material’s properties.

    1
    The dark blue shading represents a boundary separating two grains; as the boundary moves some elements that belong to grain m become part of grain n. Credit: College of Engineering, Carnegie Mellon University.

    2
    High energy diffraction microscopy images of grain boundary velocities and curvatures and computed mobilities. Velocities do not correlate with the other properties. Credit: College of Engineering, Carnegie Mellon University.

    When they make a new material, scientists need to control its microstructure, which includes its grain boundaries. Materials scientists manipulate the density of grain boundaries in order to meet different needs. For example, the structure surrounding the passenger cabin in a car is made of an ultrahigh strength steel that contains more grain boundaries than the aesthetic body panels in the car’s front-end crumple zone.

    For the last 70 years, researchers have predicted materials’ behavior using a theory that says that the speed at which grain boundaries move throughout a heated material is correlated to the boundary’s shape. Rohrer and Suter have shown that this theory, formulated to describe the most ideal case, does not apply in real polycrystals.

    Polycrystals are more complicated than the ideal cases studied in the past. Rohrer, a professor of materials science and engineering, Opens in new window explained, “If one considers a single grain boundary in a crystal, it can move without interruption, like a car driving down an empty roadway. In polycrystals, each grain boundary is connected to, on average, 10 others, so it’s like that car hit traffic—it can’t move so freely anymore. Therefore, this model no longer holds.” On top of that, Rohrer and Suter found that often polycrystal grain boundaries weren’t even moving in the direction that the model would have predicted.

    HEDM, a technique that was pioneered by Suter and colleagues using the Argonne National Laboratory’s Advanced Photon Source (APS), was key to these discoveries. HEDM and its associated techniques allow researchers to non-destructively image thousands of crystals and measure their orientations within opaque metals and ceramics. The technique requires high energy X-rays available only at one of a few synchrotron sources around the world.

    “It’s like having 3D X-ray vision,” said Suter, a professor of physics. “Before, you couldn’t look at a material’s grains without cutting it apart. HEDM allows us to noninvasively view the grain orientations and boundaries as they evolve over time.”

    The development of HEDM began around 20 years ago and continues to this day. Suter’s group worked with scientists at APS to develop procedures for the synchronized collection of thousands of images of X-ray diffraction patterns from a material sample as it undergoes precision rotation in an intense incident beam.

    ANL DOE Argonne National Laboratory (US) Advanced Photo Source

    High performance computer codes developed by Suter’s research group convert the sets of images into three-dimensional maps of the crystalline grains that make up the material microstructure.

    Ten years ago, Suter’s group (including physics graduate students Chris Hefferan, Shiu-Fai Li, and Jon Lind) repeatedly measured a nickel sample after successive high temperature treatments resulting in the first observations of individual grain boundary motions. These motions failed to show the systematic behavior predicted by the 70-year-old theory. The point of view developed by the Carnegie Mellon researchers in the Science paper correlates grain boundary structure with systematic behaviors observed in the HEDM experimental data.

    While the current analysis is based on a single material, nickel, X-ray diffraction microscopy is being used on many materials, and Rohrer and Suter believe that many of those materials will demonstrate similar behavior to that seen in nickel. Similar applications to other material processing conditions also are being studied.

    This research was funded by the National Science Foundation’s Designing Materials to Revolutionize and Engineer the Future program (DRMEF). The team’s four-year grant was renewed for $1.8 million dollars effective October 1, 2021. Carnegie Mellon’s Kaushik Dayal, professor of civil and environmental engineering ; Elizabeth Holm, professor of materials science and engineering; and David Kinderlehrer, professor of mathematical sciences, will also be involved in the next steps of research studying how and why polycrystals behave this way in different materials. Professors Carl Krill (Ulm University [Universität Ulm](DE)) and Amanda Krause (The University of Florida (US)) are also part of the collaboration.

    See the full article here .

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    Stem Education Coalition

    The College of Engineering is well-known for working on problems of both scientific and practical importance. Our acclaimed faculty focus on transformative results that will drive the intellectual and economic vitality of our community, nation and world. Our “maker” culture is ingrained in all that we do, leading to novel approaches and unprecedented results.

    Carnegie Mellon University (US) is a global research university with more than 12,000 students, 95,000 alumni, and 5,000 faculty and staff.
    CMU has been a birthplace of innovation since its founding in 1900.
    Today, we are a global leader bringing groundbreaking ideas to market and creating successful startup businesses.
    Our award-winning faculty members are renowned for working closely with students to solve major scientific, technological and societal challenges. We put a strong emphasis on creating things—from art to robots. Our students are recruited by some of the world’s most innovative companies.
    We have campuses in Pittsburgh, Qatar and Silicon Valley, and degree-granting programs around the world, including Africa, Asia, Australia, Europe and Latin America.

    The university was established by Andrew Carnegie as the Carnegie Technical Schools, the university became the Carnegie Institute of Technology in 1912 and began granting four-year degrees. In 1967, the Carnegie Institute of Technology merged with the Mellon Institute of Industrial Research, formerly a part of the University of Pittsburgh. Since then, the university has operated as a single institution.

    The university has seven colleges and independent schools, including the College of Engineering, College of Fine Arts, Dietrich College of Humanities and Social Sciences, Mellon College of Science, Tepper School of Business, Heinz College of Information Systems and Public Policy, and the School of Computer Science. The university has its main campus located 3 miles (5 km) from Downtown Pittsburgh, and the university also has over a dozen degree-granting locations in six continents, including degree-granting campuses in Qatar and Silicon Valley.

    Past and present faculty and alumni include 20 Nobel Prize laureates, 13 Turing Award winners, 23 Members of the American Academy of Arts and Sciences (US), 22 Fellows of the American Association for the Advancement of Science (US), 79 Members of the National Academies, 124 Emmy Award winners, 47 Tony Award laureates, and 10 Academy Award winners. Carnegie Mellon enrolls 14,799 students from 117 countries and employs 1,400 faculty members.
    Research

    Carnegie Mellon University is classified among “R1: Doctoral Universities – Very High Research Activity”. For the 2006 fiscal year, the university spent $315 million on research. The primary recipients of this funding were the School of Computer Science ($100.3 million), the Software Engineering Institute ($71.7 million), the College of Engineering ($48.5 million), and the Mellon College of Science ($47.7 million). The research money comes largely from federal sources, with a federal investment of $277.6 million. The federal agencies that invest the most money are the National Science Foundation (US) and the Department of Defense (US), which contribute 26% and 23.4% of the total university research budget respectively.

    The recognition of Carnegie Mellon as one of the best research facilities in the nation has a long history—as early as the 1987 Federal budget Carnegie Mellon University was ranked as third in the amount of research dollars with $41.5 million, with only Massachusetts Institute of Technology (US) and Johns Hopkins University (US) receiving more research funds from the Department of Defense.

    The Pittsburgh Supercomputing Center (PSC) (US) is a joint effort between Carnegie Mellon, University of Pittsburgh (US), and Westinghouse Electric Company. Pittsburgh Supercomputing Center was founded in 1986 by its two scientific directors, Dr. Ralph Roskies of the University of Pittsburgh and Dr. Michael Levine of Carnegie Mellon. Pittsburgh Supercomputing Center is a leading partner in the TeraGrid, the National Science Foundation’s cyberinfrastructure program.
    Scarab lunar rover is being developed by the RI.

    The Robotics Institute (RI) is a division of the School of Computer Science and considered to be one of the leading centers of robotics research in the world. The Field Robotics Center (FRC) has developed a number of significant robots, including Sandstorm and H1ghlander, which finished second and third in the DARPA Grand Challenge, and Boss, which won the DARPA Urban Challenge. The Robotics Institute has partnered with a spinoff company, Astrobotic Technology Inc., to land a CMU robot on the moon by 2016 in pursuit of the Google Lunar XPrize. The robot, known as Andy, is designed to explore lunar pits, which might include entrances to caves. The RI is primarily sited at Carnegie Mellon’s main campus in Newell-Simon hall.

    The Software Engineering Institute (SEI) is a federally funded research and development center sponsored by the U.S. Department of Defense and operated by Carnegie Mellon, with offices in Pittsburgh, Pennsylvania, USA; Arlington, Virginia, and Frankfurt, Germany. The SEI publishes books on software engineering for industry, government and military applications and practices. The organization is known for its Capability Maturity Model (CMM) and Capability Maturity Model Integration (CMMI), which identify essential elements of effective system and software engineering processes and can be used to rate the level of an organization’s capability for producing quality systems. The SEI is also the home of CERT/CC, the federally funded computer security organization. The CERT Program’s primary goals are to ensure that appropriate technology and systems management practices are used to resist attacks on networked systems and to limit damage and ensure continuity of critical services subsequent to attacks, accidents, or failures.

    The Human–Computer Interaction Institute (HCII) is a division of the School of Computer Science and is considered one of the leading centers of human–computer interaction research, integrating computer science, design, social science, and learning science. Such interdisciplinary collaboration is the hallmark of research done throughout the university.

    The Language Technologies Institute (LTI) is another unit of the School of Computer Science and is famous for being one of the leading research centers in the area of language technologies. The primary research focus of the institute is on machine translation, speech recognition, speech synthesis, information retrieval, parsing and information extraction. Until 1996, the institute existed as the Center for Machine Translation that was established in 1986. From 1996 onwards, it started awarding graduate degrees and the name was changed to Language Technologies Institute.

    Carnegie Mellon is also home to the Carnegie School of management and economics. This intellectual school grew out of the Tepper School of Business in the 1950s and 1960s and focused on the intersection of behavioralism and management. Several management theories, most notably bounded rationality and the behavioral theory of the firm, were established by Carnegie School management scientists and economists.

    Carnegie Mellon also develops cross-disciplinary and university-wide institutes and initiatives to take advantage of strengths in various colleges and departments and develop solutions in critical social and technical problems. To date, these have included the Cylab Security and Privacy Institute, the Wilton E. Scott Institute for Energy Innovation, the Neuroscience Institute (formerly known as BrainHub), the Simon Initiative, and the Disruptive Healthcare Technology Institute.

    Carnegie Mellon has made a concerted effort to attract corporate research labs, offices, and partnerships to the Pittsburgh campus. Apple Inc., Intel, Google, Microsoft, Disney, Facebook, IBM, General Motors, Bombardier Inc., Yahoo!, Uber, Tata Consultancy Services, Ansys, Boeing, Robert Bosch GmbH, and the Rand Corporation have established a presence on or near campus. In collaboration with Intel, Carnegie Mellon has pioneered research into claytronics.

     
  • richardmitnick 10:49 am on October 10, 2021 Permalink | Reply
    Tags: "Ruling Electrons and Vibrations in a Crystal with Polarized Light", , Atomic vibrations-and therefore phonons-can be generated in a solid by shining light on it., , , Physics, , To the naked eye solids may appear perfectly still but in reality their constituent atoms and molecules are anything but.,   

    From Tokyo Institute of Technology [東京工業大学](JP): “Ruling Electrons and Vibrations in a Crystal with Polarized Light” 

    tokyo-tech-bloc

    From Tokyo Institute of Technology [東京工業大学](JP)

    October 8, 2021

    Associate Professor Kazutaka G. Nakamura
    Institute of Innovative Research,
    Tokyo Institute of Technology
    nakamura@msl.titech.ac.jp
    Tel +81-45-924-5387

    Contact
    Public Relations Division
    Tokyo Institute of Technology
    media@jim.titech.ac.jp
    Tel +81-3-5734-2975

    The quantum behavior of atomic vibrations excited in a crystal using light pulses has much to do with the polarization of the pulses, say materials scientists from Tokyo Tech. The findings from their latest study offer a new control parameter for the manipulation of coherently excited vibrations in solid materials at the quantum level.

    1

    To the naked eye solids may appear perfectly still but in reality their constituent atoms and molecules are anything but. They rotate and vibrate, respectively defining the so-called “rotational” and “vibrational” energy states of the system. As these atoms and molecules obey the rules of quantum physics, their rotation and vibration are, in fact, discretized, with a discrete “quantum” imagined as the smallest unit of such motion. For instance, the quantum of atomic vibration is a particle called “phonon.”

    Atomic vibrations-and therefore phonons-can be generated in a solid by shining light on it. A common way to do this is by using “ultrashort” light pulses (pulses that are tens to hundreds of femtoseconds long) to excite and manipulate phonons, a technique known as “coherent control.” While the phonons are usually controlled by changing the relative phase between consecutive optical pulses, studies have revealed that light polarization can also influence the behavior of these “optical phonons.”

    Dr. Kazutaka Nakamura’s team at Tokyo Institute of Technology (Tokyo Tech) explored the coherent control of longitudinal optical (LO) phonons (i.e., phonons corresponding to longitudinal vibrations excited by light) on the surface of a GaAs (gallium arsenide) single crystal and observed a “quantum interference” for both electrons and phonons for parallel polarization while only phonon interference for mutually perpendicular polarization. “We developed a quantum mechanical model with classical light fields for the coherent control of the LO phonon amplitude and applied this to GaAs and diamond crystals. However, we did not study the effects of polarization correlation between the light pulses in sufficient detail,” says Dr. Nakamura, Associate Professor at Tokyo Tech.

    Accordingly, his team focused on this aspect in a new study published in Physical Review B. They modeled the generation of LO phonons in GaAs with two relative phase-locked pulses using a simplified band model and “Raman scattering,” the phenomenon underlying the phonon generation, and calculated the phonon amplitudes for different polarization conditions.

    Their model predicted both electron and phonon interference for parallel-polarized pulses as expected, with no dependence on crystal orientation or the intensity ratio for allowed and forbidden Raman scattering. For perpendicularly polarized pulses, the model only predicted phonon interference at an angle of 45° from the [100] crystal direction. However, when one of the pulses was directed along [100], electron interference was excited by allowed Raman scattering.

    With such insights, the team looks forward to a better coherent control of optical phonons in crystals. “Our study demonstrates that polarization plays quite an important role in the excitation and detection of coherent phonons and would be especially relevant for materials with asymmetric interaction modes, such as bismuth, which has more than two optical phonon modes and electronic states. Our findings are thus extendable to other materials,” comments Nakamura.

    Indeed, light has its ways of getting both materials and material scientists excited!

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    tokyo-tech-campus

    Tokyo Institute of Technology [東京工業大学](JP) is the top national university for science and technology in Japan with a history spanning more than 130 years. Of the approximately 10,000 students at the Ookayama, Suzukakedai, and Tamachi Campuses, half are in their bachelor’s degree program while the other half are in master’s and doctoral degree programs. International students number 1,200. There are 1,200 faculty and 600 administrative and technical staff members.

    In the 21st century, the role of science and technology universities has become increasingly important. Tokyo Tech continues to develop global leaders in the fields of science and technology, and contributes to the betterment of society through its research, focusing on solutions to global issues. The Institute’s long-term goal is to become the world’s leading science and technology university.

     
  • richardmitnick 1:59 am on October 9, 2021 Permalink | Reply
    Tags: "FAU physicists control the flow of electron pulses through a nanostructure channel", APF: alternating phase focusing, , , DLA uses ultra-fast laser technology and advances in semi-conductor production to potentially minimise these accelerators to merely a few millimetres or centimetres in size., DLA: dielectric laser acceleration, , , , , Physics   

    From Friedrich-Alexander-Universität Erlangen-Nürnberg [FAU] (DE): “FAU physicists control the flow of electron pulses through a nanostructure channel” 

    From Friedrich-Alexander-Universität Erlangen-Nürnberg [FAU] (DE)

    September 23, 2021

    Chair for Laser Physics
    Dr. Roy Shiloh
    Tel.: 09131/85-27211
    roy.shiloh@fau.de

    Johannes Illmer M.Sc.
    Tel.: 09131/85-27211
    johannes.i.illmer@fau.de

    Prof. Dr. Peter Hommelhoff
    Tel.: 09131/85-27090
    peter.hommelhoff@fau.de

    1
    Experimental setup in the laser laboratory. Picture: Maximilian Schlosser.

    Particle accelerators are essential tools in research areas such as biology, materials science and particle physics. Researchers are always looking for more powerful ways of accelerating particles to improve existing equipment and increase capacities for experiments. One such powerful technology is dielectric laser acceleration (DLA). In this approach, particles are accelerated in the optical near-field which is created when ultra-short laser pulses are focused on a nanophotonic structure. Using this method, researchers from the Chair of Laser Physics at FAU have succeeded in guiding electrons through a vacuum channel, an essential component of particle accelerators. The basic design of the photonic nanostructure channel was developed by cooperation partner The Technical University of Darmstadt [Technische Universität Darmstadt] (DE). They have now published their joint findings in the journal Nature.

    Staying focused

    As charged particles tend to move further away from each other as they spread, all accelerator technologies face the challenge of keeping the particles within the required spatial and time boundaries. As a result, particle accelerators can be up to ten kilometres long, and entail years of preparation and construction before they are ready for use, not to mention the major investments involved. Dielectric laser acceleration, or DLA uses ultra-fast laser technology and advances in semi-conductor production to potentially minimise these accelerators to merely a few millimetres or centimetres in size.

    A promising approach: Experiments have already demonstrated that DLA exceeds currently used technologies by at least 35 times. This means that the length of a potential accelerator could be reduced by the same factor. Until now, however, it was unclear whether these figures could be scaled up for longer and longer structures.

    A team of physicists led by Prof. Dr. Peter Hommelhoff from the Chair of Laser Physics at FAU has taken a major step forward towards adapting DLA for use in fully-functional accelerators. Their work is the first to set out a scheme which can be used to guide electron pulses over long distances.

    Technology is key

    The scheme, known as ‘alternating phase focusing’ (APF) is a method taken from the early days of accelerator theory. A fundamental law of physics means that focusing charged particles in all three dimensions at once – width, height and depth – is impossible. However, this can be avoided by alternately focusing the electrons in different dimensions. First of all, electrons are focused using a modulated laser beam, then they ‘drift’ through another short passage where no forces act on them, before they are finally accelerated, which allows them to be guided forward.

    In their experiment, the scientists from FAU and TU Darmstadt incorporated a colonnade of oval pillars with short gaps at regular intervals, resulting in repeating macro cells. Each macro cell either has a focusing or defocusing effect on the particles, depending on the delay between the incident laser, the electron, and the gap which creates the drifting section. This setup allows precise electron phase space control at the optical or femto-second ultra-timescale (a femto-second corresponds to a millionth of a billionth of a second). In the experiment, shining a laser on the structure shows an increase in the beam current through the structure. If a laser is not used, the electrons are not guided and gradually crash into the walls of the channel. ‘It’s very exciting,’ says FAU physicist Johannes Illmer, co-author of the publication. ‘By way of comparison, the large Hadron collider at CERN uses 23 of these cells in a 2450 metre long curve. Our nanostructure uses five similar-acting cells in just 80 micrometres.’

    When can we expect to see the first DLA accelerator?

    ‘The results are extremely significant, but for us it is really just an interim step,’ explains Dr. Roy Shiloh, ‘and our final goal is clear: we want to create a fully-functional accelerator – on a microchip.’

    See the full article here.

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    Friedrich-Alexander-Universität Erlangen-Nürnberg, [FAU] (DE} is a public research university in the cities of Erlangen and Nuremberg in Bavaria, Germany. The name Friedrich–Alexander comes from the university’s first founder Friedrich, Margrave of Brandenburg-Bayreuth, and its benefactor Christian Frederick Charles Alexander, Margrave of Brandenburg-Ansbach.

    FAU is the second largest state university in the state of Bavaria. It has 5 faculties, 24 departments/schools, 25 clinical departments, 21 autonomous departments, 579 professors, 3,457 members of research staff and roughly 14,300 employees.

    In winter semester 2018/19 around 38,771 students (including 5,096 foreign students) enrolled in the university in 265 fields of study, with about 2/3 studying at the Erlangen campus and the remaining 1/3 at the Nuremberg campus. These statistics put FAU in the list of top 10 largest universities in Germany. In 2018, 7,390 students graduated from the university and 840 doctorates and 55 post-doctoral theses were registered. Moreover, FAU received 201 million Euro (2018) external funding in the same year, making it one of the strongest third-party funded universities in Germany.

    FAU is also a member of DFG (Deutsche Forschungsgemeinschaft) and the Top Industrial Managers for Europe network.

     
  • richardmitnick 4:33 pm on October 8, 2021 Permalink | Reply
    Tags: "The strange afterglow of a gamma-ray burst", , Gamma-ray bursts (GRBs) are bright X-ray and gamma-ray flashes observed in the sky emitted by distant extragalactic sources., GRBs are associated with the creation or merging of neutron stars or black holes., H.E.S.S. Collaboration, , , Physics   

    From MPG Institute for Nuclear Physics [MPG Institut für Kernphysik] (DE): “The strange afterglow of a gamma-ray burst” 

    From MPG Institute for Nuclear Physics [MPG Institut für Kernphysik] (DE)

    June 04, 2021 [Why now? Where has this been?]

    Dr. Gertrud Hönes
    MPG Institut für Kernphysik, Heidelberg
    +49 6221 516-572
    info@mpi-hd.mpg.de

    Edna L. Ruiz Velasco
    +49 6221 516-137
    Edna.ruiz@mpi-hd.mpg.de

    Prof. Dr. Felix Aharonian
    +49 6221 516-485
    Felix.Aharonian@mpi-hd.mpg.de

    Prof. Dr. Jim Hinton
    +49 6221 516-140
    jim.hinton@mpi-hd.mpg.de

    Researchers from the H.E.S.S. Collaboration succeeded to derive the intrinsic spectrum of the very-high-energy gamma-ray afterglow emission of a relatively nearby gamma-ray burst. Surprisingly, the gamma-ray spectrum resembles that of the much lower-energy X-rays, while the fading emission from both bands was observed to march in parallel over three nights. These remarkable findings challenge the current emission scenarios.

    H.E.S.S. Čerenkov Telescope Array, located on the Cranz family farm, Göllschau, in Namibia, near the Gamsberg searches for cosmic rays, altitude, 1,800 m (5,900 ft).

    1

    Flash in space: An artist’s view of a gamma-ray burst. © DESY Electron Synchrotron[ Deütsches Elektronen-Synchrotron](DE), Science Communication Lab.

    Gamma-ray bursts (GRBs) are bright X-ray and gamma-ray flashes observed in the sky emitted by distant extragalactic sources. They are associated with the creation or merging of neutron stars or black holes; processes which result in an explosive outburst of material moving incredibly close to the speed of light. The initial flashes, which last a few seconds, are followed by a long-lived afterglow phase that can be detectable for several days in X-rays, and often weeks or even months in the optical and radio bands. It was this afterglow emission that first confirmed the extragalactic origin of GRBs. The X-ray afterglow radiation is produced by accelerated electrons interacting and losing energy within the blast wave magnetic field. This energy is radiated in the form of synchrotron photons.

    GRB afterglows are considered to be an excellent cosmic laboratory for studying acceleration of particles in the cosmos, due to the apparent simplicity of the underlying physics. This is in contrast with the prompt phase which is extremely complex. Many aspects of the afterglow emission are well known in X-rays, but the very-high-energy (VHE, >100 GeV) emission – six orders of magnitude more energetic than X-rays – has been a missing piece of the multi-wavelength puzzle.

    In the VHE regime, making a detection is particularly challenging since the distant Universe is not fully transparent to VHE gamma rays due to their absorption in the background light that permeates the Universe. In recent years, major steps have been made toward the understanding of GRBs at VHEs with two detections, the first observed 10 hours after the afterglow onset and the second within the first hour of the afterglow. Both were observable for no more than two hours and happened at moderate cosmological distances, limiting the highest energy in the spectrum that could be probed. The process responsible for the most energetic emission, however, remained inconclusive.

    2
    Fading burst: The H.E.S.S. sky maps of GRB190829A show the fading afterglow emission over the three observa-tion nights (panels A, B, C). © H.E.S.S. Collaboration.

    Now, the international team of researchers operating the H.E.S.S. (High Energy Stereoscopic System) array of atmospheric Čerenkov telescopes, reported the detection of a third GRB – at a redshift of only z = 0.0785, a mere 1 billion light-years away. “A gamma-ray burst occurring in our cosmic backyard like this one, is a very rare thing, and a fantastic opportunity to understand what is going on at the highest energies” – mentioned Jim Hinton, director at MPG Institut für Kernphysik (DE).

    On 29 August 2019, the Fermi Gamma-Ray Burst Monitor and the Swift Burst Alert Telescope detected and localised GRB 190829A.

    National Aeronautics and Space Administration(US) Fermi Large Area Telescope

    National Aeronautics and Space Administration(US)/Fermi Gamma Ray Space Telescope.

    National Aeronautics and Space Administration(US) Neil Gehrels Swift Observatory.

    Subsequently, ground-based observatories including H.E.S.S. turned to look at this position to monitor the evolution of this burst over a very wide range of wavelengths. Observations with H.E.S.S. started 4 hours after the burst, when the source became visible to its telescopes. Edna Ruiz Velasco, a PhD student from MPIK, was one of the lead investigators in the work: “We have been able to cover the GRB afterglow from 4 to 56 hours after the initial explosion and measure its emission very accurately”. Dmitry Khangulyan, a H.E.S.S. member from Rikkyo University [立教大学](JP), and an MPIK alumnus, added: “This new result provides two new and unique observational insights about GRB afterglows.”

    The accurate determination of the spectrum over more than an order of magnitude in energy, from 0.18 to 3.3 TeV, and covering an extended temporal range of several days, was made possible by a combination of good instrumental sensitivity and the fortuitous proximity of the GRB. Such accurate measurements over a broad energy range have allowed the intrinsic VHE spectrum to be reliably probed for the first time. As Carlo Romoli, a post-doctoral researcher at MPIK noted, “these new results have revealed curious similarities between the X-ray and VHE gamma-ray emission”.

    Such a strong connection, however, is unexpected in standard GRB theory, which predicts a separate origin for the VHE component. In this theory, synchrotron emission up to VHE gamma rays is not possible, since a maximum energy is placed on the electrons. The observations by H.E.S.S., however, can be explained if electrons are accelerated beyond this limit. “The far-reaching implication of this possibility highlights the need for further studies of VHE GRB afterglow emission”, mentioned Felix Aharonian, external scientific member of MPIK and at Dublin Institute for Advanced Studies [Institiúid Ard-Léinn Bhaile Átha Cliath](IE).

    As highlighted by Andrew Taylor from DESY-Zeuthen (and another MPIK alumnus), “the community is getting more and more excited about the prospects for the next generation of observatories. After decades of searching, we are finally getting closer to understanding the processes that govern this extremely energetic phenomena”. Looking to the future, the prospects for the detection of GRBs by future instruments look promising. Certainly, the abundance of GRB afterglow detections over the last few years indicates that regular detections in the VHE band will become rather common. However, a high bar has now been set by this H.E.S.S. result, which has highlighted the scientific importance of the detection at VHE of local GRBs, particularly at late times in the afterglow.

    Science paper:
    Science

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The MPG Institute for Nuclear Physics [MPG Institut für Kernphysik](DE) is a research institute in Heidelberg, Germany.

    The institute is one of the 80 institutes of the Max-Planck-Gesellschaft (Max Planck Society), an independent, non-profit research organization. The MPG Institute for Nuclear Physics was founded in 1958 under the leadership of Wolfgang Gentner. Its precursor was the Institute for Physics at the MPI for Medical Research.

    Today, the institute’s research areas are: crossroads of particle physics and astrophysics (astroparticle physics) and many-body dynamics of atoms and molecules (quantum dynamics).

    The research field of Astroparticle Physics combines questions related to macrocosm and microcosm. Unconventional methods of observation for gamma rays and neutrinos open new windows to the universe. What lies behind “dark matter” and “dark energy” is theoretically investigated.

    The research field of Quantum Dynamics is represented by the divisions of Klaus Blaum, Christoph Keitel and Thomas Pfeifer. Using reaction microscopes, simple chemical reactions can be “filmed”. Storage rings and traps allow precision experiments almost under space conditions. The interaction of intense laser light with matter is investigated using quantum-theoretical methods.

    Further research fields are cosmic dust, atmospheric physics as well as fullerenes and other carbon molecules.

    Scientists at the MPIK collaborate with other research groups in Europe and all over the world and are involved in numerous international collaborations, partly in a leading role. Particularly close connections to some large-scale facilities like GSI Helmholtz Centre for Heavy Ion Research [GSI Helmholtzzentrum für Schwerionenforschung] (DE), DESY Electron Synchrotron[ Deütsches Elektronen-Synchrotron](DE), European Organization for Nuclear Research [Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) [CERN], TRIUMF-Canadian national particle accelerator center (CA), and INFN-LNGS – Gran Sasso National Laboratory (IT) exist. The institute has about 390 employees, as well as many diploma students and scientific guests.

    In the local region, the Institute cooperates closely with The Ruprecht Karl University of Heidelberg, [Ruprecht-Karls-Universität Heidelberg] (DE), where the directors and further members of the Institute are teaching. Three International Max Planck Research Schools (IMPRS) and a graduate school serve to foster young scientists.

    The institute operates a cryogenic ion storage ring (CSR) dedicated to the study of molecular ions under interstellar space conditions. Several Penning ion traps are used to measure fundamental constants of nature, such as the atomic mass of the electron and of nuclei. A facility containing several electron beam ion traps (EBIT) that produce and store highly charged ions is dedicated to fundamental atomic structure as well as astrophysical investigations. Large cameras for gamma-ray telescopes (H.E.S.S. – The High Energy Stereoscopic System (NM), CTA Consortium – Čerenkov Telescope Array), Dark Matter (Gran Sasso XENON1T Dark Matter Search (IT), DARWIN – Dark Matter WIMP Search With Liquid Xenon The University of Zürich [Universität Zürich ](CH)), and neutrino detectors are developed and tested on-site.

    MPG Institute for the Advancement of Science [MPG zur Förderung der Wissenschaften e. V](DE) is Germany’s most successful research organization. Since its establishment in 1948, no fewer than 18 Nobel laureates have emerged from the ranks of its scientists, putting it on a par with the best and most prestigious research institutions worldwide. The more than 15,000 publications each year in internationally renowned scientific journals are proof of the outstanding research work conducted at MPG Institutes – and many of those articles are among the most-cited publications in the relevant field.

    What is the basis of this success? The scientific attractiveness of the MPG Society is based on its understanding of research: MPG institutes are built up solely around the world’s leading researchers. They themselves define their research subjects and are given the best working conditions, as well as free reign in selecting their staff. This is the core of the Harnack principle, which dates back to Adolph von Harnack, the first president of the Kaiser Wilhelm Society, which was established in 1911. This principle has been successfully applied for nearly one hundred years. The MPG Society continues the tradition of its predecessor institution with this structural principle of the person-centered research organization.

    The currently 83 MPG Institutes and facilities conduct basic research in the service of the general public in the natural sciences, life sciences, social sciences, and the humanities. MPG Institutes focus on research fields that are particularly innovative, or that are especially demanding in terms of funding or time requirements. And their research spectrum is continually evolving: new institutes are established to find answers to seminal, forward-looking scientific questions, while others are closed when, for example, their research field has been widely established at universities. This continuous renewal preserves the scope the Max Planck Society needs to react quickly to pioneering scientific developments.

    MPG Society for the Advancement of Science [MPG Gesellschaft zur Förderung der Wissenschaften e. V.] is a formally independent non-governmental and non-profit association of German research institutes founded in 1911 as the Kaiser Wilhelm Society and renamed the MPG Society in 1948 in honor of its former president, theoretical physicist Max Planck. The society is funded by the federal and state governments of Germany as well as other sources.

    According to its primary goal, the MPG Society supports fundamental research in the natural, life and social sciences, the arts and humanities in its 83 (as of January 2014) MPG institutes. The society has a total staff of approximately 17,000 permanent employees, including 5,470 scientists, plus around 4,600 non-tenured scientists and guests. Society budget for 2015 was about €1.7 billion.

    The MPG Institutes focus on excellence in research. The MPG Society has a world-leading reputation as a science and technology research organization, with 33 Nobel Prizes awarded to their scientists, and is generally regarded as the foremost basic research organization in Europe and the world. In 2013, the Nature Publishing Index placed the MPG institutes fifth worldwide in terms of research published in Nature journals (after Harvard University (US), Massachusetts Institute of Technology (US),
    Stanford University (US)and the National Institutes of Health (US)). In terms of total research volume (unweighted by citations or impact), the MPG Society is only outranked by the Chinese Academy of Sciences [中国科学院] (CN), the Russian Academy of Sciences [Росси́йская акаде́мия нау́к](RU) and Harvard University. The Thomson Reuters-Science Watch website placed the Max Planck Society as the second leading research organization worldwide following Harvard University, in terms of the impact of the produced research over science fields.

    The MPG Society and its predecessor Kaiser Wilhelm Society hosted several renowned scientists in their fields, including Otto Hahn, Werner Heisenberg, and Albert Einstein.

    History

    The organization was established in 1911 as the Kaiser Wilhelm Society, or Kaiser-Wilhelm-Gesellschaft (KWG), a non-governmental research organization named for the then German emperor. The KWG was one of the world’s leading research organizations; its board of directors included scientists like Walther Bothe, Peter Debye, Albert Einstein, and Fritz Haber. In 1946, Otto Hahn assumed the position of President of KWG, and in 1948, the society was renamed the MPG Society after its former President (1930–37) Max Planck, who died in 1947.

    The MPG Society has a world-leading reputation as a science and technology research organization. In 2006, the Times Higher Education Supplement rankings of non-university research institutions (based on international peer review by academics) placed the MPG Society as No.1 in the world for science research, and No.3 in technology research (behind AT&T Corporation and the DOE’s Argonne National Laboratory (US).

    The domain mpg.de attracted at least 1.7 million visitors annually by 2008 according to a Compete.com study.

    MPG Institutes and research groups

    The MPG Society consists of over 80 research institutes. In addition, the society funds a number of MPG Research Groups (MPRG) and International MPG Research Schools (IMPRS). The purpose of establishing independent research groups at various universities is to strengthen the required networking between universities and institutes of the MPG Society.

    The research units are primarily located across Europe with a few in South Korea and the U.S. In 2007, the Society established its first non-European centre, with an institute on the Jupiter campus of Florida Atlantic University (US) focusing on neuroscience.

    The MPG Institutes operate independently from, though in close cooperation with, the universities, and focus on innovative research which does not fit into the university structure due to their interdisciplinary or transdisciplinary nature or which require resources that cannot be met by the state universities.

    Internally, MPG Institutes are organized into research departments headed by directors such that each MPG institute has several directors, a position roughly comparable to anything from full professor to department head at a university. Other core members include Junior and Senior Research Fellows.

    In addition, there are several associated institutes:

    International Max Planck Research Schools
    Together with the Association of Universities and other Education Institutions in Germany, the MPG Society established numerous International Max Planck Research Schools (IMPRS) to promote junior scientists:

    Cologne Graduate School of Ageing Research, Cologne
    International Max Planck Research School for Intelligent Systems, at the MPG Institute for Intelligent Systems (DE) located in Tübingen and Stuttgart
    International Max Planck Research School on Adapting Behavior in a Fundamentally Uncertain World (Uncertainty School), at the Max Planck Institutes for Economics, for Human Development, and/or Research on Collective Goods
    International Max Planck Research School for Analysis, Design and Optimization in Chemical and Biochemical Process Engineering, Magdeburg
    International Max Planck Research School for Astronomy and Cosmic Physics, Heidelberg at the MPG for Astronomy
    International Max Planck Research School for Astrophysics, Garching at the MPG Institute for Astrophysics
    International Max Planck Research School for Complex Surfaces in Material Sciences, Berlin
    International Max Planck Research School for Computer Science, Saarbrücken
    International Max Planck Research School for Earth System Modeling, Hamburg
    International Max Planck Research School for Elementary Particle Physics, Munich, at the MPG Institute for Physics
    International Max Planck Research School for Environmental, Cellular and Molecular Microbiology, Marburg at the MPG Institute for Terrestrial Microbiology
    International Max Planck Research School for Evolutionary Biology, Plön at the Max Planck Institute for Evolutionary Biology
    International Max Planck Research School “From Molecules to Organisms”, Tübingen at the MPG Institute for Developmental Biology
    International Max Planck Research School for Global Biogeochemical Cycles, Jena at the Max Planck Institute for Biogeochemistry
    International Max Planck Research School on Gravitational Wave Astronomy, Hannover and Potsdam MPG Institute for Gravitational Physics
    International Max Planck Research School for Heart and Lung Research, Bad Nauheim at the MPG Institute for Heart and Lung Research
    International Max Planck Research School for Infectious Diseases and Immunity, Berlin at the Max Planck Institute for Infection Biology
    International Max Planck Research School for Language Sciences, Nijmegen
    International Max Planck Research School for Neurosciences, Göttingen
    International Max Planck Research School for Cognitive and Systems Neuroscience, Tübingen
    International Max Planck Research School for Marine Microbiology (MarMic), joint program of the MPG Institute for Marine Microbiology in Bremen, the University of Bremen [Universität Bremen](DE), the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, and the Jacobs University Bremen [Jacobs Universität Bremen] (DE)
    International Max Planck Research School for Maritime Affairs, Hamburg
    International Max Planck Research School for Molecular and Cellular Biology, Freiburg
    International Max Planck Research School for Molecular and Cellular Life Sciences, Munich
    International Max Planck Research School for Molecular Biology, Göttingen
    International Max Planck Research School for Molecular Cell Biology and Bioengineering, Dresden
    International Max Planck Research School Molecular Biomedicine, program combined with the ‘Graduate Programm Cell Dynamics And Disease’ at the University of Münster (DE) and the MPG Institute for Molecular Biomedicine (DE)
    International Max Planck Research School on Multiscale Bio-Systems, Potsdam
    International Max Planck Research School for Organismal Biology, at the University of Konstanz [Universität Konstanz] (DE) and the MPG Institute for Ornithology (DE)
    International Max Planck Research School on Reactive Structure Analysis for Chemical Reactions (IMPRS RECHARGE), Mülheim an der Ruhr, at the Max Planck Institute for Chemical Energy Conversion (DE)
    International Max Planck Research School for Science and Technology of Nano-Systems, Halle at MPG Institute of Microstructure Physics (DE)
    International Max Planck Research School for Solar System Science at the University of Göttingen – Georg-August-Universität Göttingen (DE) hosted by MPG Institute for Solar System Research [Max-Planck-Institut für Sonnensystemforschung] (DE)
    International Max Planck Research School for Astronomy and Astrophysics, Bonn, at the MPG Institute for Radio Astronomy [MPG Institut für Radioastronomie] (DE) (formerly the International Max Planck Research School for Radio and Infrared Astronomy)
    International Max Planck Research School for the Social and Political Constitution of the Economy, Cologne
    International Max Planck Research School for Surface and Interface Engineering in Advanced Materials, Düsseldorf at MPG Institute for Iron Research [MPG Institut für Eisenforschung] (DE)
    International Max Planck Research School for Ultrafast Imaging and Structural Dynamics, Hamburg

     
  • richardmitnick 3:18 pm on October 8, 2021 Permalink | Reply
    Tags: "CCNY researchers announce photon-phonon breakthrough", , City College of New York (US), , , Physics, , The research also holds promise for vibrational spectroscopy—also known as infrared spectroscopy., Topological photonics-an emergent direction in photonics, Topological photons—light—has been combined with lattice vibrations also known as phonons to manipulate their propagation in a robust and controllable way.   

    From City College of New York (US) : “CCNY researchers announce photon-phonon breakthrough” 

    10.8.21

    Max Dorfman/Jay Mwamba
    p: 212.650.7580
    e: jmwamba@ccny.cuny.edu

    From City College of New York (US)

    1
    Topologically distinct photonic crystals (orange and blue) with a layer of hexagonal boron nitride on top enable coupling of topological light and lattice vibrations to form chiral half-light half-vibration excitations, which can be directionally guided along 1D channels in robust manner. Credit: Filipp Komissarenko and Sriram Guddala.

    New research by a City College of New York team has uncovered a novel way to combine two different states of matter. For one of the first times, topological photons—light—has been combined with lattice vibrations also known as phonons to manipulate their propagation in a robust and controllable way.

    The study utilized topological photonics-an emergent direction in photonics which leverages fundamental ideas of the mathematical field of topology about conserved quantities—topological invariants—that remain constant when altering parts of a geometric object under continuous deformations. One of the simplest examples of such invariants is number of holes, which, for instance, makes donut and mug equivalent from the topological point of view. The topological properties endow photons with helicity, when photons spin as they propagate, leading to unique and unexpected characteristics, such as robustness to defects and unidirectional propagation along interfaces between topologically distinct materials. Thanks to interactions with vibrations in crystals, these helical photons can then be used to channel infrared light along with vibrations.

    The implications of this work are broad, in particular allowing researchers to advance Raman spectroscopy, which is used to determine vibrational modes of molecules. The research also holds promise for vibrational spectroscopy—also known as infrared spectroscopy—which measures the interaction of infrared radiation with matter through absorption, emission, or reflection. This can then be utilized to study and identify and characterize chemical substances.

    “We coupled helical photons with lattice vibrations in hexagonal boron nitride, creating a new hybrid matter referred to as phonon-polaritons,” said Alexander Khanikaev, lead author and physicist with affiliation in CCNY’s Grove School of Engineering. “It is half light and half vibrations. Since infrared light and lattice vibrations are associated with heat, we created new channels for propagation of light and heat together. Typically, lattice vibrations are very hard to control, and guiding them around defects and sharp corners was impossible before.”

    The new methodology can also implement directional radiative heat transfer, a form of energy transfer during which heat is dissipated through electromagnetic waves.

    “We can create channels of arbitrary shape for this form of hybrid light and matter excitations to be guided along within a two-dimensional material we created,” added Dr. Sriram Guddala, postdoctoral researcher in Prof. Khanikaev’s group and the first author of the manuscript. “This method also allows us to switch the direction of propagation of vibrations along these channels, forward or backward, simply by switching polarizations handedness of the incident laser beam. Interestingly, as the phonon-polaritons propagate, the vibrations also rotate along with the electric field. This is an entirely novel way of guiding and rotating lattice vibrations, which also makes them helical.”

    The study appears in the journal Science.

    See the full article here.

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    WE’RE THE ORIGINAL –
    AND WE’RE STILL MEETING THE NEED.

    Since 1847, The City College of New York (US) has provided a high quality and affordable education to generations of New Yorkers in a wide variety of disciplines. CCNY embraces its role at the forefront of social change.

    Located in the heart of New York City, CCNY is home to such important ‘firsts’ as: The first college explicitly founded on the ideal of educating the ‘whole people’, the first documentary film program in the U.S., the first intercollegiate lacrosse game played in the U.S., first student government in the nation, and the longest running Alumni Association in the U.S.

    It is ranked #1 by The Chronicle of Higher Education out of 369 selective public colleges in the United States on the overall mobility index. This measure reflects both access and outcomes, representing the likelihood that a student at CCNY can move up two or more income quintiles. In addition, the Center for world University Rankings places CCNY in the top 1.2% of universities worldwide in terms of academic excellence. More than 16,000 students pursue undergraduate and graduate degrees in eight professional schools and divisions, driven by significant funded research, creativity and scholarship. CCNY is as diverse, dynamic and visionary as New York City itself.

    Outstanding programs in architecture, engineering, education and the liberal arts and sciences prepare our students for the future, and produce outstanding leaders in every field.Whether they are drawn to the traditional, like philosophy or sociology, or emerging fields like sonic arts or biomedical engineering, our baccalaureate graduates go on to graduate programs at Stanford, Columbia or MIT – or they stay right here in one of our 50 master’s programs or our doctoral programs in engineering, the laboratory sciences, and psychology.

    Nowhere else in the city do undergraduates have so many opportunities to conduct research with professors and publish and present their findings.In our science, engineering and social science programs, more than 300 undergrads work alongside senior researchers in funded projects. Leading CUNY in funded research, we house a number of research centers, and soon two new advanced research centers will rise on South Campus.Nearly all of our full-time faculty hold PhDs or – like our architecture faculty, maintain professional practices.Art professors exhibit their work, film professors make films, and music professors perform in venues around the country.

    The campus is alive with student activity. City College fields 16 varsity teams that compete in NCAA Division III – and students work out in an equipment rich fitness center and socialize in more than 100 student clubs. And our students come from around the corner and world, representing more than 150 nationalities. City College is an integral part of the civic, urban and artistic energy of New York and inseparable from its history. We are the City that built this city.

     
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