professor physics – Polkinghorne http://polkinghorne.org/ Thu, 17 Mar 2022 18:30:28 +0000 en-US hourly 1 https://wordpress.org/?v=5.9.3 https://polkinghorne.org/wp-content/uploads/2022/01/icon-2022-01-25T202759.511-150x150.png professor physics – Polkinghorne http://polkinghorne.org/ 32 32 The Absolutely Incredible Theory of Almost Everything https://polkinghorne.org/the-absolutely-incredible-theory-of-almost-everything/ Sat, 15 Jan 2022 08:00:00 +0000 https://polkinghorne.org/the-absolutely-incredible-theory-of-almost-everything/ How does our world work at the subatomic level? The standard model. What a boring name for the most accurate scientific theory known to human beings. More than a quarter of the Nobel Prizes in Physics of the last century are direct inputs or direct results of the Standard Model. Still, its name suggests that […]]]>

How does our world work at the subatomic level?

The standard model. What a boring name for the most accurate scientific theory known to human beings.

More than a quarter of the Nobel Prizes in Physics of the last century are direct inputs or direct results of the Standard Model. Still, its name suggests that if you can afford a few extra bucks a month, you should buy the upgrade. As a theoretical physicist, I would prefer The Absolutely Incredible Theory of almost anything. That’s what the standard model really is.

Many remember the enthusiasm of scientists and the media over the 2012 discovery of the Higgs boson. But this high-profile event didn’t come out of nowhere — it capped a five-decade unbeaten streak for the standard model. All fundamental forces except gravity are included. All attempts to overthrow it to demonstrate in the laboratory that it needs substantial reworking – and there have been many over the past 50 years – have failed.

In short, the standard model answers this question: what is it all made of and how does it fit together?

The smallest building blocks

You know, of course, that the world around us is made of molecules, and molecules are made of atoms. Chemist Dmitri Mendeleev discovered in the 1860s how to arrange all of the atoms – aka the elements – in the periodic table that you probably studied in college. But there are 118 different chemical elements. There’s antimony, arsenic, aluminum, selenium… and 114 others.

Periodic table

But these elements can be broken down further. Credit: Ruben Vera Koster

Physicists like simple things. We want to boil things down to their essence, a few basics. More than a hundred chemical elements is not simple. The ancients believed that everything was made up of only five elements: earth, water, fire, air and ether. Five is much simpler than 118. It’s also wrong.

In 1932, scientists knew that all these atoms were made up of only three particles: neutrons, protons and electrons. Neutrons and protons are tightly bound in the nucleus. Electrons, thousands of times lighter, whirl around the nucleus at speeds close to the speed of light. The physicists Planck, Bohr, Schroedinger, Heisenberg and their friends had invented a new science – quantum mechanics – to explain this movement.

It would have been a satisfying place to stop. Just three particles. Three is even easier than five. But how to hold together? Negatively charged electrons and positively charged protons are bound by electromagnetism. But the protons are all packed into the nucleus, and their positive charges should powerfully push them away. Neutrons can’t help.

What binds these protons and these neutrons? “Divine intervention” a man told me on a Toronto street corner; he had a pamphlet, I could read all about it. But this scenario seemed to pose a lot of problems, even for a divine being – to keep an eye on every one of the 108° protons and neutrons in the universe and bend them to his will.

Expand the Particle Zoo

Meanwhile, nature has cruelly refused to limit its particle zoo to just three. Really four, because you would have to count the photon, the particle of light described by Einstein. Four changed to five when Anderson measured electrons with a positive charge – positrons – hitting Earth from space. At least Dirac had predicted these first antimatter particles. Five became six when the pawn, which Yukawa believed would hold the core together, was found.

Then came the muon – 200 times heavier than the electron, but otherwise a twin. “Who ordered this? II Rabi joked. That sums it all up. Number seven. Not only not simple, redundant.

In the 1960s, there were hundreds of “fundamental” particles. Instead of the neatly organized periodic table, there were only long lists of baryons (heavy particles like protons and neutrons), mesons (like Yukawa pions) and leptons (light particles like the electron and the elusive neutrinos) – with no organization and no guiding principles.

Into this breach has slipped the standard model. It wasn’t an overnight flash of brilliance. No Archimedes jumped out of a bathtub shouting “eureka”. Instead, there was a series of crucial ideas from a few key people in the mid-1960s that turned this quagmire into a simple theory, and then five decades of experimental verification and theoretical elaboration.

Standard model of elementary particles

The standard model of elementary particles provides a list of ingredients for everything around us. Credit: National Fermi Accelerator Laboratory

Quarks. They come in six varieties which we call flavors. Like ice cream, except it’s not as tasty. Instead of vanilla, chocolate and so on, we have high, low, weird, charm, low and high. In 1964, Gell-Mann and Zweig taught us the recipes: mix and match three quarks to get a baryon. Protons are two ups and one down quark bound together; neutrons are two lows and one high. Choose a quark and an antiquark to get a meson. A pion is an up or down quark bound to an anti-up or an anti-down. All the material of our daily life is composed only of quarks, anti-quarks and electrons.

Simple. Well, it’s simple, because keeping those quarks bound is a feat. They are so closely related to each other that you never find a single quark or antiquark. The theory of this binding, and the particles called gluons (laughs) that are responsible for it, is called quantum chromodynamics. It is an essential piece of the standard model, but mathematically difficult, even posing an unsolved problem of basic mathematics. We physicists do our best to calculate with it, but we are still learning how.

The other aspect of the standard model is “a lepton model”. It’s the name of Steven Weinberg’s landmark 1967 paper that brought together quantum mechanics with the essential knowledge of how particles interact and organized the two into a single theory. He incorporated the familiar electromagnetism, associated it with what physicists called “the weak force” that causes certain radioactive decays, and explained that they were different aspects of the same force. It incorporated the Higgs mechanism to give mass to fundamental particles.

Since then, the Standard Model has predicted the results of experiment after experiment, including the discovery of several varieties of quarks and W and Z bosons, heavy particles that are to weak interactions what the photon is to electromagnetism. The possibility that neutrinos are not massless was overlooked in the 1960s, but slipped easily into the Standard Model in the 1990s, a few decades later.

CERN particle accelerator Higgs boson decay SM

3D view of an event recorded at the CERN particle accelerator showing the expected characteristics of the decay of the SM Higgs boson into a pair of photons (dashed yellow lines and green towers). Credit: McCauley, Thomas; Taylor, Lucas; for the CMS CERN collaboration

Discovering the Higgs boson in 2012, long predicted by the Standard Model and long sought after, was a thrill but not a surprise. It was yet another crucial victory for the Standard Model over the dark forces that particle physicists have repeatedly warned were looming on the horizon. Concerned that the Standard Model did not adequately embody their expectations of simplicity, worried about its mathematical consistency, or anticipating the possible need to incorporate the force of gravity, physicists made numerous proposals for theories beyond of the norm. Model. These go by exciting names like Grand Unified Theories, Supersymmetry, Technicolor, and String Theory.

Unfortunately, at least for their proponents, theories beyond the Standard Model have not yet successfully predicted a new experimental phenomenon or an experimental divergence from the Standard Model.

After five decades, far from needing an upgrade, the Standard Model deserves to be celebrated as an absolutely incredible theory of almost everything.

Written by Glenn Starkman, Distinguished University Professor of Physics, Case Western Reserve University.

This article first appeared in The Conversation.The conversation

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Beate Heinemann becomes the new director in charge of particle physics at DESY https://polkinghorne.org/beate-heinemann-becomes-the-new-director-in-charge-of-particle-physics-at-desy/ Tue, 07 Dec 2021 08:00:00 +0000 https://polkinghorne.org/beate-heinemann-becomes-the-new-director-in-charge-of-particle-physics-at-desy/ A professor of physics completes the board of directors of the Research Center First woman on the board of DESY: Beate Heinemann. Image: DESY / Angela Pfeiffer Beate Heinemann, DESY Principal Investigator and Professor of Physics at the University of Fribourg, will take over as Director of DESY’s High Energy Physics Division on February 1. […]]]>

A professor of physics completes the board of directors of the Research Center

First woman on the board of DESY: Beate Heinemann. Image: DESY / Angela Pfeiffer

Beate Heinemann, DESY Principal Investigator and Professor of Physics at the University of Fribourg, will take over as Director of DESY’s High Energy Physics Division on February 1. This was unanimously decided by DESY’s supervisory body, the Foundation Council, at its meeting on 7 December. Heinemann is the first female director in the history of DESY.

“Beate Heinemann is a real asset to the research centre,” says Dr. Volkmar Dietz of the Federal Ministry of Education and Research, Chairman of the Foundation Board. “With her international experience, vast knowledge, reputation and forward-looking ideas, she will certainly lead the field of particle physics research into the next exciting era. As the first female CEO, she will mark also the DESY story!”

Beate Heinemann is a true Hamburger, having grown up very close to DESY in Hamburg. She cut her teeth in particle physics experiments and at universities and research centers around the world. After completing her PhD at the University of Hamburg on an experiment at DESY’s HERA accelerator, she joined the CDF experiment at Fermilab near Chicago as a scientist at the University of Liverpool before becoming a professor at the ‘University of California at Berkeley working on the ATLAS experiment, a giant particle detector at CERN in Geneva. From 2013 to 2017, she was deputy spokesperson for the ATLAS experiment. She then returned to Germany to continue her research with ATLAS as a senior scientist at DESY and a professor at the University of Freiburg.

“I am very pleased that Beate Heinemann will join the management of DESY in the future”, says Helmut Dosch, Director of DESY. “His excellent expertise in particle physics and his experience in managing large international teams are perfectly suited to the many facets of fundamental research at DESY and the Helmholtz Association. We are proud to welcome him to the team and have looking forward to shaping the future with her.”

Heinemann succeeds Joachim Mnich, who joined European research center CERN as research director in early 2021, and Ties Behnke, who led the research division as interim director. At DESY, the particle physics division includes not only the particle physicists and technicians involved in the international experiments, but also theorists, the DESY computer department, the library and many service groups such as electronics development.

“DESY is a world-class laboratory and I am thrilled to be part of shaping its present and its future,” says Heinemann. “Many topics and projects are close to my heart – from fundamental research and developments in future technologies to sustainability and diversity. The next decade offers many exciting challenges, both scientifically and socially, and I look forward to the decisive contributions DESY will meet these challenges.”

We spoke to the new director and asked her about her plans and ideas.

What are your plans for your new research center?

As Director, you are not only responsible for your own division, but for DESY as a whole. DESY as a whole is close to my heart. First of all, I think it is very important that we maintain and further expand our pioneering role as a center for fundamental research for the study of matter.

We know that many of the major breakthrough developments and changes stem from basic research. This is why I think it should continue to be the basis of research at DESY – but we also have actions and a research mandate in application-oriented fields, for example climate, digitalization or health . DESY can contribute with all its research areas, for example through new accelerator technologies, new methods for developing detectors or new facilities for photon science. And we must also prioritize sustainability on campus.

Another topic close to my heart, both personally and through my new office, is diversity. DESY must remain a cosmopolitan and diverse laboratory, and there is still room for improvement in many areas, for example the number of women in leadership positions.

And what about your own research division?

Of course, I also have ideas for particle physics, which is based on several very strong pillars at DESY: we participate in international experiments, have our own very interesting experiments on campus, a strong theory group and we are pioneers of digital transformation with our IT sector. . Thanks to our cutting-edge research, we are also very attractive to young scientists who come to us from countries all over the world to do their PhD, postdoctoral research or take up a staff position. We must continue to evolve to stay at the international forefront and review our strategy for the next decade.

In our detector assembly facility here on campus, for example, we are building several core components for the upgrade of experiments as part of the LHC accelerator expansion. DESY has taken on a huge responsibility – it is important that we deliver!

But we can also be proud of the exciting experiments we carry out here at DESY in the framework of international collaboration. The ALPS II experiment will begin next year. ALPS searches for dark matter using small, elusive particles called axions, which also play a role in several other experiments that are on DESY’s wish and planning list. If they all came, which I will of course defend, DESY would be world-leading in the very dynamic field of axion research. The excellent infrastructure we have at DESY as a national research laboratory for particle physics plays a major role here.

We can also be very proud of our theory. It rightly enjoys an excellent reputation around the world, based in particular on the fact that our experts cover more than 60 orders of magnitude in physics – from string theory to cosmology. With the future Wolfgang Pauli Center, it will be even larger and more multidisciplinary.

In the next few years, the course will be set for the successor project to the LHC, namely the next big particle accelerator, the technology and location of which have not yet been chosen. It is very important to me that DESY also actively participates in the preparation of this project in order to maintain and expand its pioneering role.

These are just a few of my ideas and we should always be open to new ones. We have a lot of smart, creative people here, and you never know what spectacular proposition they’ll come up with next.

DESY aside – what are the things that are most important to you?

Above all, durability is very important to me. Our generation bears the responsibility now; we must act now and think climate in everything, both in research and in the development of the DESY campus and Science City Bahrenfeld.

Fundamental research is also close to my heart because not only is it extremely interesting, but it can also stimulate innovation. Take for example the mRNA vaccine, which is based on 20 years of basic research, or the accelerators, which were developed 100 years ago in particle physics and are now used worldwide to treat tumors.

But above all, I am still determined to find out how nature works and what laws of nature underlie it. In my opinion, we are now in the most exciting period in particle physics since the structure of the atom was first discovered and then understood in the early 20th century. In about forty years, physics has been completely revolutionized. At this moment, we are again entering a new energy scale, the electroweak force scale, which is closely related to the Higgs particle and gives us many questions. Studying this scale in detail now is extremely exciting and can also lead to groundbreaking discoveries that no one can even dream of today.

You were born in Hamburg and also studied here. What’s it like to become the first female director at DESY?

First of all, it is a great honor for me to be the first female director at DESY, having taken my first career steps at DESY during my university studies. In general, it is very, very important to me that women have the same opportunities and find the same conditions as men in all areas. In a modern society, we must make the most of everyone’s potential, regardless of gender, religion or social or ethnic origin.

And I’ve always stayed connected to Hamburg: I’m a big HSV fan! As the eldest of three siblings, my dad took me to the stadium from an early age, and to this day I still watch every game with him (although usually on the couch rather than in the stadium) .

DESY is one of the world’s leading particle accelerator centers and studies the structure and function of matter – from the interaction of tiny elementary particles and the behavior of new nanomaterials and vital biomolecules to the great mysteries of the universe. . The particle accelerators and detectors that DESY develops and builds at its sites in Hamburg and Zeuthen are unique research tools. They generate the most intense X-radiation in the world, accelerating particles to record energies and opening new windows on the universe. DESY is a member of the Helmholtz Association, Germany’s largest scientific association, and receives its funding from the German Federal Ministry of Education and Research (BMBF) (90%) and the German federal states of Hamburg and Brandenburg (10%).

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Steven Weinberg obituary | Particle physics https://polkinghorne.org/steven-weinberg-obituary-particle-physics/ Mon, 02 Aug 2021 07:00:00 +0000 https://polkinghorne.org/steven-weinberg-obituary-particle-physics/ The American theoretical particle physicist Steven Weinberg, who died at the age of 88, was one of the leading figures of the 20th century in this field. In 1979, he won a Nobel Prize for his work uniting two of nature’s fundamental forces, which became a foundation of the Standard Model of particle physics, the […]]]>

The American theoretical particle physicist Steven Weinberg, who died at the age of 88, was one of the leading figures of the 20th century in this field. In 1979, he won a Nobel Prize for his work uniting two of nature’s fundamental forces, which became a foundation of the Standard Model of particle physics, the theory that describes all known particles and fundamental forces in the universe. .

From Weinberg’s prodigious work – in research, in his technical and popular books on quantum field theory and cosmology, and in scientific commentary articles – his work demonstrating that the transmutation of elements by the weak nuclear force is fundamentally related to electromagnetism constituted a truly remarkable breakthrough.

Following Peter Higgs’ discovery in 1964 that fundamental particles can, in theory, gain mass through the “Higgs mechanism”, he, Weinberg and others tried to find examples where this mechanism is used in the nature. These attempts initially focused on the strong force that binds atomic nuclei, but no consistent correspondence emerged, until 1967, while on his way to work at MIT (the Massachusetts Institute of Technology), Weinberg had an inspired thought: they had implemented the right idea. , but to the wrong problem.

Instead of the strong force, Weinberg realized that the mechanism could apply to the weak nuclear force, manifested by radioactivity. As a bonus, Weinberg realized that thanks to this application, he could describe in a single mathematical diagram both the phenomena of electromagnetism and the form of radioactivity which is the key to the creation of elements in stars. This idea would become the basis of the current standard model of particles and forces.

A viable quantum field theory of electromagnetism – quantum electrodynamics (QED) – had been known since 1947. The key to its consistency was that the photon – the basic particle of electromagnetic radiation – is massless. Weinberg’s marriage of weak and electromagnetic forces required the existence of analogues of the photon. These “W and Z bosons” were later discovered and confirmed to be very massive, as Weinberg had predicted.

There was a problem, however: being massive, they apparently undermined the mathematical coherence of the theory. Weinberg conjectured, but was unable to prove, that if the W and Z gained their masses through the Higgs mechanism, his extension of QED would indeed be a viable quantum theory of two forces.

Initially his paper had little impact, with one prominent scientist later describing the response: “Rarely has such a great achievement been so widely ignored.” Then, in 1971, a young Dutch student, Gerard ‘t Hooft, proved the model to be a complete and viable theory, winning himself a Nobel Prize in 1999 for this feat.

With the demonstration that Weinberg had indeed constructed a coherent relativistic quantum theory of electromagnetic and weak force fields, the predictions of which were soon confirmed in a variety of experiments, his seminal paper quickly became the most cited in all of theoretical physics. Its implications were so profound that they determined the direction of high-energy particle physics during the last decades of the 20th century. In what was to prove to be of momentous importance, his papers drew attention to a cornerstone of his theoretical construction – the necessary role of the ‘Higgs boson’. The search for this particle would take four decades; its discovery in 2012 was the final piece in a structure whose architectural design owed much to the genius of Weinberg.

Born in New York, Steven was the son of Jewish immigrants, Eva (née Israel) and Frederick Weinberg, a court stenographer. Steven’s love for science began in childhood with the gift of a chemistry set. He attended Bronx Science High School, which produced eight Nobel laureates, including Weinberg’s contemporary Sheldon Glashow, whose freelance work led him to share the 1979 prize with Weinberg and Abdus Salam. He earned a bachelor’s degree at Cornell University in 1954, and that year married Louise Goldwasser, whom he had met while a student; she became a law professor. After a year at what is now the Niels Bohr Institute in Copenhagen, Weinberg returned to the United States and Princeton University, where he earned a doctorate (1957).

After two years at Columbia University and six at Berkeley, in 1966 Weinberg joined Harvard University, first as a lecturer, and from 1973 as a professor of physics. Early in his Harvard stint, Weinberg had a joint appointment at MIT, and it was while driving there in his red Camarro that he had his weak nuclear force epiphany.

In 1982 he moved to the University of Texas at Austin, where he spent the rest of his career. He never retired and continued teaching until the spring of that year.

For decades, Weinberg’s ideas outside of his 1967 paper inspired new lines of research. His work on “effective field theories” redefined the direction of work in quantum field theory and influenced attempts to find a viable quantum theory of gravity. He was one of the founders of the concept of “chiral perturbation theory” as a mathematical approach to understanding aspects of the strong nuclear force.

In addition to these seminal research contributions, Weinberg wrote an influential text on gravitation, a masterful three-volume set of textbooks on quantum field theory, and authored the popular best-selling cosmology book The First Three Minutes (1977).

In 1992 he published Dreams of a Final Theory, which has become a classic discourse on the goal of fundamental physics at the dawn of the 21st century.

In his later years he became an authoritative historian of science, his gravity and wisdom making him a respected commentator on science policy as well as social issues, and making him one of the most respected figures in science. world.

He is survived by his wife, Louise, whom he married in 1954, their daughter, Elizabeth, and one granddaughter.

Steven Weinberg, theoretical physicist, born May 3, 1933; passed away on July 23, 2021

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Quantum Science, Particle Physics and Nanoscale Motors Receive Support from Eric and Wendy Schmidt Transformative Tech Fund https://polkinghorne.org/quantum-science-particle-physics-and-nanoscale-motors-receive-support-from-eric-and-wendy-schmidt-transformative-tech-fund/ Tue, 11 May 2021 07:00:00 +0000 https://polkinghorne.org/quantum-science-particle-physics-and-nanoscale-motors-receive-support-from-eric-and-wendy-schmidt-transformative-tech-fund/ New quantum materials that promise to power future communications, AI-based research to uncover fundamental laws of physics, and a project to build biomolecular engines have been selected for funding through the Eric and Wendy Schmidt Transformative Technology Fund. The three projects, led by teams of professors from all fields of science and engineering, aim to […]]]>

New quantum materials that promise to power future communications, AI-based research to uncover fundamental laws of physics, and a project to build biomolecular engines have been selected for funding through the Eric and Wendy Schmidt Transformative Technology Fund.

The three projects, led by teams of professors from all fields of science and engineering, aim to launch new discoveries that have the potential to transform entire fields of research and propel innovation. Projects were selected following a competitive application process in which proposals were evaluated on their potential to accelerate progress on important challenges through advances in knowledge development and technological capabilities.

“These are deeply important projects that have the potential to take both our fundamental knowledge and our technical capabilities to exciting new levels,” said Dean of Research Pablo Debenedetti, Class of 1950 Professor of Engineering and Applied Sciences. and professor of chemistry and biology. engineering. “Rather than iterating, these proposals aim to make major breakthroughs in a discipline and have the ability to completely change the conversation.”

The Eric and Wendy Schmidt Transformative Technologies Fund stimulates the exploration of ideas and approaches that can profoundly enable advances in science or engineering. Eric Schmidt, former CEO of Google and former executive chairman of Alphabet Inc., Google’s parent company, received his bachelor’s degree in electrical engineering from Princeton in 1976 and served as a director of Princeton from 2004 to 2008. He and his wife, Wendy, a businesswoman and philanthropist, established the fund in 2009. Including this year’s three awards, the fund has supported 27 research projects at Princeton.

From left to right: Peter Elmer, Senior Research Physicist, Physics; Mariangela Lisanti, associate professor of physics; and Isobel Ojalvo, Assistant Professor of Physics

Bringing artificial intelligence to the search for new discoveries in physics

Embarking on a quest to explore the fundamental mysteries of the universe, a team of physicists will bring the power of artificial intelligence (AI) to the exploration of the subatomic building blocks of matter.

Despite major advances in understanding the physical laws that govern the universe, many questions remain open, including the nature of dark matter and dark energy, which together make up 95% of the universe. A team led by Senior Research Physicist Peter Elmer, Associate Professor of Physics Mariangela Lisanti and Assistant Professor of Physics Isobel Ojalvo will develop methods to apply AI as a tool to search for new physical phenomena in experiments conducted at accelerators particles such as CERN’s Large Hadron Collider (LHC).

The LHC experiments validated the main theory of the composition of the universe, the Standard Model, by confirming theoretical predictions such as the existence of the Higgs particle. Yet these discoveries do not answer unresolved questions insufficiently explained by the Standard Model, including dark matter, dark energy, and neutrino mass. New theories are needed but how to conduct a search for new principles of physics when you don’t know what to look for?

AI can help in this quest by searching the huge amount of data resulting from particle collision experiments for new or unexpected results. The team will develop AI-based algorithms that look for anomalies in the data that suggest new phenomena. Through training and deployment of AI software, the team will evaluate particle collision data to search for new physical laws that could explain unexplained facets of our universe.

Sanfeng Wu, Leslie Schoop, Mansour Shayegan and Loren Pfeiffer

From left to right: Sanfeng Wu, assistant professor of physics; Leslie Schoop, assistant professor of chemistry; Mansour Shayegan, Professor of Electrical and Computer Engineering (ECE); and Loren Pfeiffer, Senior ECE Researcher

Station X: an extreme environment for quantum discoveries

Building on recent discoveries in quantum materials, a team from the departments of Physics, Chemistry, and Electrical and Computer Engineering will build a new quantum exploration site that features some of the most extreme conditions on Earth. including ultra-low temperatures, ultra-low and ultra-high pressures and strong magnetic fields.

Technologies that use quantum properties could unlock new capabilities in computing, communications, and many other fields. While much research has focused on the exotic quantum properties of metals and semimetals, few studies have looked into the quantum behaviors of electrical insulators. materials in which electrons cannot move freely mainly due to the lack of methods to observe these properties in insulators. Recent work by Princeton teams has detected intriguing examples of quantum phases in insulators and semiconductors, but exploring quantum behaviors in these systems requires specialized conditions and new experimental approaches.

To make transformative discoveries in the emerging field of quantum insulators, a team led by Assistant Professor of Physics Sanfeng Wu, Assistant Professor of Chemistry Leslie Schoop, Professor of Electrical and Computer Engineering Mansour Shayegan, and Senior Researcher in Electrical Engineering and Loren Pfeiffer will build an experimental research facility in Princeton’s Jadwin Hall called Station X.

The station will house equipment to create extreme temperatures, pressures, magnetic fields, material purity, and other conditions that allow researchers to evaluate materials with hidden quantum phases. The team will develop advanced measurement systems that combine electronics and optics to provide an unprecedented platform capable of exploring the synthesis and measurements of a wide range of quantum materials. This project, combining Princeton’s expertise in chemistry, engineering and physics, will ensure Princeton a leading role in the emergence of new areas of quantum science.

Sabine Petry, Akanksha Thawani, Howard Stone

From left to right: Sabine Petry, Associate Professor of Molecular Biology; Akanksha Thawani, a 2020 Ph.D. graduate in Chemical and Biological Engineering; and Howard Stone, Donald R. Dixon ’69 and Elizabeth W. Dixon Professor of Mechanical and Aerospace Engineering

Bio-inspired nanoscale engines and factories

Inspired by the biological machinery of the body, a team of molecular biologists and mechanical engineers will design tiny motors and possibly entire factories dedicated to treating disease.

The technology for building these molecular robots builds on recent discoveries at Princeton about the nature of the cellular skeleton, which is made up of long, thin proteins called microtubules. Nature is adept at building devices with mobile microtubules that perform tasks such as propelling the movement of single-celled organisms or dividing chromosomes in cells. One such device, the mitotic spindle, is made up of strands of microtubules that attach to chromosomes and pull them apart during cell division. Microtubules can exert force on other molecules by pulling or pushing them, they can pull molecules apart or propel them together, and they can self-assemble into new structures.

Princeton researchers led by Associate Professor of Molecular Biology Sabine Petry have uncovered how spindles form and uncovered molecular mechanisms to control them. Petry will team up with Howard Stone, Professor of Mechanical and Aerospace Engineering Donald R. Dixon ’69 and Elizabeth W. Dixon, whose expertise in fluid mechanics will help build miniature channels and chips, in which the machines based on microtubules will be assembled.

The team planned to build several types of nanoscale microtubule-based devices, including bio-actuators, capable of performing a task such as moving a particle or molecule from a place to another. By connecting microtubule-based machines through channels, guided by fluid flows in certain directions, researchers will create nanoscale assembly lines and eventually factories. Researchers envision this microtubule-based nanotechnology as opening up an entirely new field of science, making complex manipulations of molecules and other small structures at the nanoscale possible.

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Muons don’t fit the standard model of particle physics https://polkinghorne.org/muons-dont-fit-the-standard-model-of-particle-physics/ Fri, 16 Apr 2021 07:00:00 +0000 https://polkinghorne.org/muons-dont-fit-the-standard-model-of-particle-physics/ Share this Item You are free to share this article under the Attribution 4.0 International License. Fundamental particles called muons behave in ways that scientists’ best theory to date, the Standard Model of particle physics, does not predict, the researchers report. The discovery comes from early results from the Muon g-2 experiment at the US […]]]>

Fundamental particles called muons behave in ways that scientists’ best theory to date, the Standard Model of particle physics, does not predict, the researchers report.

The discovery comes from early results from the Muon g-2 experiment at the US Department of Energy’s Fermi National Accelerator Laboratory.

“This experience is a bit like a detective novel.”

This historic result confirms a discrepancy that has plagued researchers for decades.

The strong evidence that muons deviate from the Standard Model calculation could hint at some exciting new physics. The muons in this experiment act as a window into the subatomic world and could interact with as yet unknown particles or forces.

“This experiment is a bit like a detective novel,” says team member David Hertzog, a University of Washington physics professor and founding spokesperson for the experiment. “We analyzed data from the inaugural Muon g-2 test at Fermilab and discovered that the Standard Model alone cannot explain what we found. Something else, perhaps beyond the standard model, may be required. »

A muon is about 200 times more massive than its cousin the electron. They occur naturally when cosmic rays hit the Earth’s atmosphere. Fermilab’s particle accelerators can produce large numbers of them. Like electrons, muons act as if they have a small internal magnet. In a strong magnetic field, the direction of the muon magnet precedes, or “wobbles,” much like the axis of a spinning top. The strength of the internal magnet determines the muon’s precession rate in an external magnetic field and is described by a number known as the g-factor. This number can be calculated with ultra-high precision.

As muons flow through the Muon g-2 magnet, they also interact with a “quantum foam” of subatomic particles that appear and disappear. Interactions with these short-lived particles affect the value of the g-factor, causing muon precession to accelerate or slightly slow down. The standard model predicts with great accuracy what the value of this “abnormal magnetic moment” should be. But if the quantum foam contains additional forces or particles not accounted for by the Standard Model, it would further alter the g-factor of the muon.

Hertzog, then at the University of Illinois, was a lead scientist in the previous experiment at Brookhaven National Laboratory. This attempt ended in 2001 and offered clues that the behavior of the muon did not conform to the Standard Model. The new measurement from the Muon g-2 experiment at Fermilab strongly agrees with the value found at Brookhaven and deviates from theory with the most accurate measurement to date.

The accepted theoretical values ​​for the muon are:

  • g-factor: 2.00233183620(86)
  • abnormal magnetic moment: 0.00116591810(43)

The new experimental global mean results announced today by the Muon g-2 collaboration are:

  • g-factor: 2.00233184122(82)
  • abnormal magnetic moment: 0.00116592061(41)

The combined results from Fermilab and Brookhaven show a difference with theoretical predictions at a significance of 4.2 sigma, a little short of the 5 sigma – or 5 standard deviations – that scientists prefer as a claim of discovery. But it’s still compelling evidence of new physics. The probability that the results are a statistical fluctuation is approximately 1 in 40,000.

“This result from the first run of the Fermilab Muon g-2 experiment is arguably the most anticipated result in particle physics in recent years,” says Martin Hoferichter, assistant professor at the University of Bern and member of the theoretical collaboration that predicts the value of the standard model. “After almost a decade, it’s great to see this massive effort finally come to fruition.”

The Fermilab experiment, which is underway, reuses the main component of the Brookhaven experiment, a superconducting magnetic storage ring 50 feet in diameter. In 2013, it was transported 3,200 miles by land and sea from Long Island to suburban Chicago, where scientists were able to take advantage of Fermilab’s particle accelerator and produce the states’ most intense muon beam. -United. Over the next four years, researchers mounted the experiment; tuned and calibrated an incredibly uniform magnetic field; developed new techniques, instruments and simulations; and thoroughly tested the entire system.

The Muon g-2 experiment sends a beam of muons into the storage ring, where they circulate thousands of times at near the speed of light. Detectors lining the ring allow scientists to determine how fast muons “wobble”.

Many Fermilab sensors and detectors have been built at the University of Washington, such as instruments to measure the muon beam as it enters the storage ring and to detect the telltale particles that appear when the muons decay . Dozens of scientists – including professors, postdoctoral researchers, technicians, graduate students and undergraduates – worked to assemble these sensitive instruments, then set them up and monitor them at Fermilab.

“The outlook for the new result has triggered a coordinated theoretical effort to provide our experimental colleagues with a robust and consensus prediction of the Standard Model,” says Hoferichter. “Future runs will motivate further refinements, to enable a conclusive statement whether physics beyond the Standard Model lurks in the muon’s anomalous magnetic moment.”

In its first year of operation, 2018, the Fermilab experiment collected more data than all previous muon g-factor experiments combined. The Muon g-2 collaboration has now completed the analysis of the movement of more than 8 billion muons from this first period.

Analysis of data from the second and third cycles of the experiment is in progress; the fourth is in progress and a fifth is planned. Combining the results from all five tests will give scientists an even more precise measurement of the muon’s ‘wobble’, revealing with greater certainty whether new physics is lurking in the quantum foam.

“So far, we’ve analyzed less than 6% of the data the experiment will eventually collect,” says Fermilab scientist Chris Polly, who is a co-spokesperson for the current experiment and was a graduate student. of the University of Illinois under Hertzog during the Brookhaven Experiment. “While these early results tell us there is an intriguing difference to the standard model, we will learn much more over the next two years.”

“With these exciting results, our team, especially our students, are excited to push hard on analyzing the remaining data and taking future data to achieve our ultimate goal of accuracy,” says Peter Kammel, research professor of physics at the University of Washington.

An article on the research appears in Physical examination letters. Hertzog will present the findings at a University of Washington Physics Department Symposium on April 12.

The Muon g-2 experiment is an international collaboration between Fermilab in Illinois and more than 200 scientists from 35 institutions in seven countries.

Source: University of Washington

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Brookhaven Lab Appoints New Director of Nuclear and Particle Physics Branch https://polkinghorne.org/brookhaven-lab-appoints-new-director-of-nuclear-and-particle-physics-branch/ Thu, 15 Apr 2021 07:00:00 +0000 https://polkinghorne.org/brookhaven-lab-appoints-new-director-of-nuclear-and-particle-physics-branch/ Haiyan Gao, nuclear physicist and professor, will join the lab as associate lab director for nuclear and particle physics UPTON, NY – Haiyan Gao, currently the Henry W. Newson Professor Emeritus of Physics at Duke University, will join the U.S. Department of Energy’s Brookhaven National Laboratory as Associate Laboratory Director (ALD) for Nuclear Physics and […]]]>

Haiyan Gao, nuclear physicist and professor, will join the lab as associate lab director for nuclear and particle physics

UPTON, NY – Haiyan Gao, currently the Henry W. Newson Professor Emeritus of Physics at Duke University, will join the U.S. Department of Energy’s Brookhaven National Laboratory as Associate Laboratory Director (ALD) for Nuclear Physics and particles (NPP) from or around June 1, 2021.

Gao, who has a long background in nuclear physics, will help develop Brookhaven’s collective long-term vision for the next 10 years. She will also work throughout the lab and beyond to develop her emerging expertise at the future Electron-Ion Collider (EIC), a one-of-a-kind nuclear physics research facility to be built at the lab over the next decade after Brookhaven’s flagship nuclear physics facility, the Relativistic Heavy Ion Collider, completes its research mission.

“The Nuclear and Particle Physics Branch is internationally well-known in the fields of accelerator science, high-energy physics and nuclear physics,” Gao said. “I am very excited about the opportunity and the impact that I will be able to have in collaboration with many people at the Lab.”

Gao will replace ALD Deputy for High Energy Physics Dmitri Denisov, who became interim NPP ALD after Berndt Mueller left office last year to return to teaching and research full-time at Duke.

“We are delighted to welcome Haiyan to Brookhaven at such an exciting time for nuclear and particle physics,” said Brookhaven Laboratory Director Doon Gibbs. “His perspective and experience will be instrumental in advancing science here in the lab and beyond.”

Gao joins Brookhaven Lab as he develops the EIC in collaboration with scientists at the DOE’s Thomas Jefferson National Accelerator Facility. The EIC will offer scientists a deeper look at the building blocks of visible matter and the most powerful force in nature.

“What’s important in the end is that we really deliver the science,” she said.

The facility is one that the nuclear physics community has been campaigning for for many years, to work towards a more complete understanding of nucleons and atomic nuclei in quantum chromodynamics, the physical theory that describes strong interactions, Gao noted. . It will also allow scientists to discover new physics beyond the Standard Model of particle physics, Gao said.

“This facility also gives us a wonderful opportunity to train a highly motivated scientific and technical workforce in this country,” she added.

In addition to his expertise in nuclear physics, Gao has a keen interest in promoting diversity, equity and inclusion in science.

Gao obtained his doctorate. in physics from the California Institute of Technology in 1994. Since then, she has held several positions in the field, including as assistant physicist at Argonne National Laboratory and assistant and associate professor of physics at Massachusetts Institute of Technology.

While at Duke, Gao also served as the Founding Professor of Physics and Vice Chancellor for Academic Affairs at Duke Kunshan University in Kunshan, China, where she spent some of her childhood years.

Gao’s research interests at Duke have included the structure of the nucleon, the search for exotic states of quantum chromodynamics, fundamental studies of low-energy symmetry to search for new physics beyond the standard model of electroweak interactions, and the development of polarized targets.

She was elected a Fellow of the American Physical Society in 2007 and won the U.S. Department of Energy’s Best Junior Researcher Award in 2000.

Brookhaven National Laboratory is supported by the US Department of Energy’s Office of Science. The Office of Science is the largest supporter of basic physical science research in the United States and works to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science.

Follow @BrookhavenLab on Twitter or find us on Facebook.

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Experimental and theoretical physicists can now apply for the Rosen Scholar Fellowship to work at the Los Alamos Neutron Science Center https://polkinghorne.org/experimental-and-theoretical-physicists-can-now-apply-for-the-rosen-scholar-fellowship-to-work-at-the-los-alamos-neutron-science-center/ Mon, 11 Jan 2021 08:00:00 +0000 https://polkinghorne.org/experimental-and-theoretical-physicists-can-now-apply-for-the-rosen-scholar-fellowship-to-work-at-the-los-alamos-neutron-science-center/ Newswise – LOS ALAMOS, New Mexico, January 11, 2021—Experimental and theoretical scientists seeking an opportunity to pursue research in neutron scattering, dynamic materials, isotope production, and applied and basic nuclear physics research at the Los Alamos Neutron Science Center (LANSCE) can apply for the Rosen Scholar Scholarship. Applications are due March 1, 2021. “As the […]]]>

Newswise – LOS ALAMOS, New Mexico, January 11, 2021—Experimental and theoretical scientists seeking an opportunity to pursue research in neutron scattering, dynamic materials, isotope production, and applied and basic nuclear physics research at the Los Alamos Neutron Science Center (LANSCE) can apply for the Rosen Scholar Scholarship.

Applications are due March 1, 2021.

“As the flagship experimental facility of Los Alamos National Laboratory, LANSCE, research touches nearly every aspect of the laboratory’s mission, and we are always looking for opportunities to advance this work in innovative ways,” said Mike Furlanetto, LANSCE User Installation Manager. “The Rosen Scholar Fellowship offers the opportunity to combine the unique tools of LANSCE with some of the most creative ideas from academia to answer cutting-edge scientific questions. It’s also a perfect way to commemorate the creativity of Louis Rosen, the visionary behind LANSCE.

Research at LANSCE currently includes materials science using neutron scattering at the Lujan Center, dynamic materials at the Proton X-Ray Facility, isotope production at the Isotope Production Facility, and applied and basic research in nuclear physics at the Ultracold Neutron Facility, Weapons Neutron Research Center and the Lujan Center.

The Rosen Scholar scholarship is reserved for individuals recognized as scientific leaders in a field of research currently carried out at LANSCE and who exemplify the innovative and visionary qualities of Louis Rosen. The scholarship was created to honor Rosen’s memory, accomplishments, hard work, and affection for the wide range of sciences practiced at LANSCE. Louis Rosen’s outstanding leadership and scientific career at Los Alamos spanned six and a half decades and included both the initial concept of the Los Alamos Meson Physics Facility in the 1960s and its commissioning in 1972.

The Rosen Fellow is expected to be a resident at LANSCE and contribute scientific expertise to both LANSCE and the wider Los Alamos scientific community. The position will support the Rosen Fellow at his current salary, including relocation costs, for up to one year. The start date, end date and duration (maximum of 12 months) of the scholarship are flexible, but must be between October 1, 2021 and September 30, 2022.

Past Rosen Scholars can attest to the worth of the scholarship. “I was extremely excited and honored to be named a 2020 Rosen Fellow, which gave me the opportunity to dedicate a full semester to working in the lab and with kindred spirits in the subatomic physics group,” said Tim. Chupp, professor of physics, applied physics and biomedical engineering at the University of Michigan.

“We developed the lab’s neutron electric dipole moment experiment,” Chupp said. “Los Alamos has the best source of ultracold neutrons in the world. The dipole moment would arise due to as yet unknown elementary particle forces that may also have produced the dominance of matter over antimatter in the early universe. I especially enjoyed working and learning from the physicists, engineers and staff at Los Alamos and hopefully bringing some of my experience to this awesome project.

“Being the 2019 Rosen Scholar has been an incredible experience from a technical, professional and human point of view,” said Paolo Rech, associate professor at the Institute of Computer Science at the Federal University of Rio Grande do Sul at the Brazil. Rech called the Los Alamos National Laboratory “a unique place” where exceptional researchers from the most varied fields meet.

“Whenever you have a doubt or a question, you’ll be sure to find someone with an answer or better yet, with more questions,” Rech said. “It stimulates research. Los Alamos is the right place to have new ideas and implement them. In addition, the staff is very helpful, which makes you enthusiastic and productive from day one. Finally, Los Alamos is a wonderful place, where it is easy to be inspired, to discover impressive landscapes and peaceful corners. I couldn’t be more grateful and proud of what we’ve accomplished during my year at the Lab.

Further information on LANSCE is available at http://lansce.lanl.gov

On Los Alamos National Laboratory
Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Triad, a public service-focused national security science organization equally owned by its three founding members. : the Battelle Memorial Institute (Battelle), the Texas A&M University System (TAMUS), and the University of California (UC) Regents for the Department of Energy’s National Nuclear Security Administration.

Los Alamos strengthens national security by ensuring the safety and reliability of America’s nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and addressing issues related to energy, environment, infrastructure, to global health and security issues.
LA-UR-21-20085

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Proven Accurate Artificial Intelligence for Nuclear and Particle Physics | MIT News https://polkinghorne.org/proven-accurate-artificial-intelligence-for-nuclear-and-particle-physics-mit-news/ Thu, 24 Sep 2020 07:00:00 +0000 https://polkinghorne.org/proven-accurate-artificial-intelligence-for-nuclear-and-particle-physics-mit-news/ The Standard Model of particle physics describes all known elementary particles and three of the four fundamental forces governing the universe; anything but gravity. These three forces – electromagnetic, strong and weak – govern the formation of particles, their interaction and their disintegration. The study of particle and nuclear physics in this framework is however […]]]>

The Standard Model of particle physics describes all known elementary particles and three of the four fundamental forces governing the universe; anything but gravity. These three forces – electromagnetic, strong and weak – govern the formation of particles, their interaction and their disintegration.

The study of particle and nuclear physics in this framework is however difficult and relies on large-scale numerical studies. For example, many aspects of the strong force require numerically simulating the dynamics at the scale of 1/10th to 1/100th the size of a proton to answer fundamental questions about the properties of protons, neutrons and cores.

“Ultimately, we are computationally limited in studying proton and nuclear structure using lattice field theory,” says Phiala Shanahan, assistant professor of physics. “There are a lot of interesting problems that we know how to solve in principle, but we just don’t have enough compute, even though we’re running on the biggest supercomputers in the world.”

To overcome these limitations, Shanahan leads a group that combines theoretical physics with machine learning models. In their article “Equivariant flow-based sampling for lattice gauge theory”, published this month in Physical examination lettersthey show how integrating the symmetries of physical theories into machine learning and artificial intelligence architectures can provide much faster algorithms for theoretical physics.

“We use machine learning not to analyze large amounts of data, but to accelerate first-principles theory in a way that doesn’t compromise the rigor of the approach,” Shanahan says. “This particular work has demonstrated that we can build machine learning architectures with some of the Standard Model symmetries of particle and nuclear physics built in, and accelerate the sampling problem we are targeting by orders of magnitude.”

Shanahan started the project with MIT graduate student Gurtej Kanwar and Michael Albergo, who is now at NYU. The project has expanded to include Center for Theoretical Physics postdocs Daniel Hackett and Denis Boyda, NYU Professor Kyle Cranmer, and physics-savvy machine learning scientists from Google Deep Mind, Sébastien Racanière and Danilo. Jiménez Rezende.

This month’s article is part of a series aimed at enabling studies in theoretical physics that are currently computationally unsolvable. “Our goal is to develop new algorithms for a key component of numerical calculations in theoretical physics,” says Kanwar. “These calculations tell us about the inner workings of the Standard Model of particle physics, our most fundamental theory of matter. Such calculations are of vital importance for comparing the results of particle physics experiments, such as the Large Hadron Collider at CERN, both to constrain the model more precisely and to discover where the model breaks down and must be extended to something even more fundamental.

The only known systematically controllable method of studying the Standard Model of particle physics in the non-perturbative regime is based on sampling snapshots of quantum fluctuations in vacuum. By measuring the properties of these fluctuations, one can deduce the properties of the particles and collisions of interest.

This technique comes with challenges, says Kanwar. “This sampling is expensive, and we’re looking to use physics-inspired machine learning techniques to take samples much more efficiently,” he says. “Machine learning has already made great strides in image generation, including, for example, NVIDIA’s recent work to generate images of faces ‘imagined’ by neural networks. Considering these vacuum snapshots as images, we think it’s only natural to turn to similar methods for our problem.

Shanahan adds, “In our approach to sampling these quantum snapshots, we optimize a model that takes us from an easy-to-sample space to the target space: given a trained model, then sampling is efficient since it suffices to take independent samples. in the easy-to-sample space, and transform them via the learned pattern.

In particular, the group introduced a framework for building machine learning models that exactly respect a class of symmetries, called “gauge symmetries”, crucial for the study of high-energy physics.

As a proof of principle, Shanahan and colleagues used their framework to train machine learning models to simulate two-dimensional theory, resulting in efficiency gains of orders of magnitude over state-of-the-art techniques. and more accurate predictions from theory. This paves the way for significantly accelerating research into the fundamental forces of nature using physics-based machine learning.

The first papers of the group as a collaboration discussed the application of the machine learning technique to a simple lattice field theory and developed this class of approaches on compact and connected manifolds that describe field theories more complicated than the standard model. Now they are working to adapt the techniques to cutting-edge calculations.

“I think we’ve shown over the past year that there’s a lot of promise in combining physics insights with machine learning techniques,” Kanwar says. “We are actively considering how to overcome the remaining hurdles in how to perform large-scale simulations using our approach. I hope to see the first application of these methods to large-scale calculations within the next two years. If we are able to overcome the final hurdles, it promises to expand what we can do with limited resources, and I dream of soon performing calculations that will give us new insight into what is beyond our best understanding of physics. today.

This physics-based machine learning idea is also known to the team as “ab-initio AI”, a key theme of the Institute for Artificial Intelligence and Fundamental Interactions (IAIFI) of the National Science Foundation recently launched at MIT, where Shanahan is a researcher. coordinator for physical theory.

Led by the Nuclear Science Laboratory, IAIFI is made up of physics and artificial intelligence researchers from MIT and Harvard, Northeastern and Tufts universities.

“Our collaboration is a great example of the spirit of IAIFI, with a diverse team coming together to advance AI and physics simultaneously,” Shanahan says. Apart from research such as Shanahan’s targeting physics theory, IAIFI researchers are also working to use AI to improve the scientific potential of various facilities, including the Large Hadron Collider and the Wave Observatory. gravity of the laser interferometer, and to advance the AI ​​itself.

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Experimental physicists design new technology for the CERN Collider https://polkinghorne.org/experimental-physicists-design-new-technology-for-the-cern-collider/ Fri, 26 Jun 2020 07:00:00 +0000 https://polkinghorne.org/experimental-physicists-design-new-technology-for-the-cern-collider/ The Large Hadron Collider is the largest machine on Earth and one of the most complex scientific instruments ever built. It uses powerful electromagnets to propel beams of charged particles at nearly the speed of light and manipulates these beams into controlled collisions that create showers of billions of tiny particles. Most of these particles […]]]>

The Large Hadron Collider is the largest machine on Earth and one of the most complex scientific instruments ever built. It uses powerful electromagnets to propel beams of charged particles at nearly the speed of light and manipulates these beams into controlled collisions that create showers of billions of tiny particles. Most of these particles are not particularly remarkable, but some can reveal the underlying physical properties of our universe.

Operated by the European Organization for Nuclear Research (CERN), the Large Hadron Collider consists of two 27-kilometre circular tubes buried deep underground along the border between Switzerland and France. Powerful compressors remove air from these tubes and beams of particles are propelled in opposite directions through them. The tubes are lined with over 1,200 large magnets that keep the particles centered inside, so they don’t collide with the machine itself.

Along the circuit there are 16 radio frequency cavities – metal chambers that maximize resonance to create a powerful electromagnetic field. This field oscillates 400 million times per second, which separates the particle beams into many bunches. As the particles pass through each radio frequency cavity, their electromagnetic force accelerates the particles to ever greater speeds until they reach their maximum speed – 99.999999% of the speed of light.

Welding and assembly of the superconducting crab cavities of the HL_LHC

Finally, another set of magnets focuses these bunches of particles, directing them to collide into one of CERN’s four main detectors. This results in a rain of particles and a lot of radiation. Sensors in CERN’s detectors must be sensitive enough to detect subatomic particles, and the chips that process this data must be able to record more than a billion particle interactions per second. And all of this has to happen in an environment where radiation levels approach those at the heart of a nuclear reactor.

Experimental physicists at Carleton are validating new sensors and readout chips that will be used in the internal tracker of CERN’s largest detector: ATLAS. The Higgs boson was first observed in ATLAS in 2012, and the facility is being upgraded as part of the High-Luminosity Large Hadron Collider project. Scheduled to be completed in 2027, the facility upgrade will significantly improve the performance of the Large Hadron Collider – and enable experiments aimed at demonstrating the existence of dark matter and other dimensions.

In particle accelerators, luminosity is a measure of how many particles can pass through a particular space in a given amount of time. More particles means more collisions to observe and study. The new Large High-Luminosity Hadron Collider will increase the luminosity of the accelerator by an order of magnitude – and so will increase the number of particle collisions it can generate.

High-luminosity upgrade kicks off with installation of two HL-LHC connecting cryostats

To accomplish all of this, significant hardware updates will be required.

“We need to be able to detect individual elementary particles as a single electron,” says Thomas Koffas, associate professor of experimental particle physics at Carleton University.

“The new sensors are so sensitive that if you breathe on them, they will most likely be damaged.

“But in the ATLAS Inner Tracker, they’ll be exposed to full-throttle radiation. There’s nothing in front of them and thousands of particles will hit each sensor with every collision. We want to be able to catch them all. To see what they are, and decide if we care about a particular collision, or let it go and wait for the next one.

The Inner Tracker has an area of ​​about 200 square meters, and about three-quarters of that will be covered with sensors measuring about 10 centimeters by 10 centimeters. That’s extremely large for a sensor. Most are only a few millimeters in diameter.

“Maintaining electrical performance over such a large area was one of the main challenges,” Koffas explains.

“The sensors must be able to withstand at least half a kilovolt without failing. The larger the surface area of ​​a semiconductor, the more difficult it is to achieve this.

Masters student at Carleton, Robert Hunter, Professor Dag Gillberg and Professor Thomas Koffas

From left to right: Robert Hunter, Master’s student at Carleton, Professor Dag Gillberg and Professor Thomas Koffas (Photo: Justin Tang)

The R&D of the project was led by the optoelectronics and microelectronics team at CERN. Carleton joined the initiative in 2014 and contributed to the stereo ring geometry of the sensor silicon wafer design. Due to the irregular shape of the ATLAS Inner Tracker, eight different sensor shapes are required. To correct the irregularities, the researchers had to incorporate rotation angles into the designs. Final prototypes were approved in 2019 and the first sensors were shipped this spring to Hammamatsu Photonics in Japan.

Inside ATLAS, each sensor will transmit data to application-specific embedded chips (ASICs) that record what they have detected. These chips were custom designed for this application by CERN’s Microelectronics Department, in collaboration with Carleton and Rutherford Appleton Laboratories in Oxford, UK. The ASIC chips are manufactured in Vermont by Global Foundries, and over 300,000 will be installed during the upgrade. Each of them must be able to handle around 640 megabytes of data in the brief moment a particle shower occurs. The stakes are high. If a sensor or chip fails during an experiment, data will be lost. This could prevent a major discovery.

To ensure that all chips and sensors meet rigorous performance standards, each sensor and chip will be individually tested. Carleton is the lead ASIC chip beta tester and will test about a quarter of the sensors. To meet the requirements of the project, Carleton physicists are teaming up with the Department of Electronics and DA-Integrated, a local microelectronics testing company and the only company to date to have demonstrated the ability to test the chips. DA-Integrated was awarded a start-up contract and invited to participate in a tendering process – the first time a Canadian company has been invited to do so.

To avoid damage to the sensors, testing should take place in purified air free of dust and moisture. The electrical performance of the sensors will be tested in a clean room of the Carleton University Microfabrication Facility in the Mackenzie Building, while mechanical performance and a visual inspection will take place at FANSSI Nanofabrication Facility at the Minto Center for Advanced Studies in Engineering.

A silicon tracker being worked on in the ATLAS SR1 cleaning room

The chip test will take place at Integrated AD facility in Stittsville, just outside of Ottawa. There, the processing power of each chip will be validated using a suite of tests developed by experimental physicists from Carleton and the University of Oxford to test prototypes during the R&D process.

“There’s a wafer with over 400 chips on it, and a machine tests each chip in sequence. Within seconds it runs several hundred tests to make sure it’s fully operational,” says Dag Gillberg, associate professor of physics working on the project.

“If it fails a test, the chip is removed and will not be sent to CERN.”

It is essential that each component is up to the task.

“We only have one hit. Once we get started, they’ll stay in the detector for 12 years,” says Gillberg.

“We won’t be able to repair it after a year, if it’s damaged. That’s why we have to be so careful. We have to make sure everything works perfectly. »

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FDA approves ventilator designed by particle physics community https://polkinghorne.org/fda-approves-ventilator-designed-by-particle-physics-community/ Tue, 05 May 2020 07:00:00 +0000 https://polkinghorne.org/fda-approves-ventilator-designed-by-particle-physics-community/ In just six weeks, from March 19 to May 1, an international team of physicists and engineers led by Princeton’s Christian Galbiati brought a fan from concept to FDA approval. The US Food and Drug Administration announced on Sunday May 3 that the Milano Mechanical Ventilator (MVM) East safe for use in the United States […]]]>

In just six weeks, from March 19 to May 1, an international team of physicists and engineers led by Princeton’s Christian Galbiati brought a fan from concept to FDA approval.

The US Food and Drug Administration announced on Sunday May 3 that the Milano Mechanical Ventilator (MVM) East safe for use in the United States under FDA Emergency Use Authorization, which helps support public health during a crisis.

A massive international team led by Princeton’s Cristian Galbiati worked to design, test and finalize the Milano Mechanical Ventilator (MVM), a low-cost ventilator designed to alleviate device shortages caused by COVID-19. With FDA approval secured, production has begun and the first 20 ventilators are already on their way to hospitals. Full production begins next week, with an initial planned manufacturing rate of 50 ventilators per day.

This the fan is an original idea de Galbiati, professor of physics at Princeton University who normally conducts a dark matter experiment called DarkSide-20k. While confined to Milan, a city hard hit by COVID-19, Galbiati heard of ventilator shortages and wanted to help.

“The sense of crisis was palpable,” Galbiati said. “It was clear that many patients would require respiratory support.

He contacted other DarkSide-20k researchers to develop a ventilator with minimal components that could be quickly produced using commonly available parts. Dark matter researchers have extensive experience design and use sophisticated gas handling systems and complex control systems, the same capabilities required in mechanical ventilators.

“Princeton has provided strong support for more than 15 years to the DarkSide project, which aims to discover dark matter with an argon-based detector,” Galbiati said. “To this end, we have faced unique challenges, such as the development of special techniques to extract isotope-depleted argon from mantle gas wells and the development of cryogenic distillation columns hundreds of meters in height to further purify the argon. None of this would have been possible without the support of Princeton. Our scientific collaboration has grown to encompass nearly 400 scientists from 100 institutions, including many talented researchers with strong technical gas expertise and know-how. When the time was right, we were ready to turn our attention to the problem of mechanical ventilator development and put the collective talents of the collaboration to good use in this context.”

Word spread quickly, with engineers and physicists from nine countries – particularly Italy, the United States and Canada – stepping in to help. Experts who typically spend their days building and operating delicate detectors quickly applied their skills and volunteered their time to build a device for delicate lungs.

“We’ve taken a huge benefit from the way particle physics collaborations work,” said Steve Brice, head of the neutrino division at the Fermi National Accelerator Laboratory. “The structure already in place includes large international and multidisciplinary groups. We can reallocate that structure to work on something different, and you can act much faster. »

The MVM is inspired by the Manley ventilator built in the 1960s. The design is simple, cheap, compact, and requires only compressed oxygen (or medical air) and an electrical power source to operate. Mojtaba “Moji” Safabakhsh, head of the manufacturing group at the Princeton Plasma Physics Laboratory, was part of the initial team working seven days a week on the design. A mechanical engineer, he offered his expertise in the design of several aspects of the device. Design variables include volume and pressure control for example, when the system supports patient breathing, what type of valve to have, how the power supply and software components work.

“We had to see what kind of parts were available through the supply chain, what hardware we could get, and I gave my expertise on how it might work,” Safabakhsh said. The design needed to be simple and use readily available parts.

The modern twist on the classic Manley design comes from the electronics and control system. “We focus on the software and keep the hardware as minimal as possible,” said Stephen Pordes, a DarkSide member based at CERN, the European Organization for Nuclear Research.

The project was not limited to dark matter researchers. While working on the prototypes, the team worked with doctors, medical device manufacturers and regulators to ensure they were making something valuable and easy to use for medical staff, with a chain of robust supply and which could be produced quickly.

Christian Galbiati

“One of the main issues was translating between what the machine does technically and how the operators would interact with the machine itself,” said Elena Gramellini, an Italian neutrino physicist who liaised with first-line doctors. line in Italy.

Industry and medical experts made themselves readily available for consultation; the doctors tested the MVM prototypes on sophisticated breathing simulators. Anesthesiologists from the COVID-19 wards in Lombardy, one of the districts hardest hit by the pandemic, played a special role in providing detailed advice for the design of the unit. With collaborators spread across 10 different time zones, work on various systems was able to occur almost around the clock, allowing MVM to go from publishing a preprinted paper March 23 at FDA approval May, the 1st.

“It’s in our DNA to collaborate across borders and in real time as particle physicists,” Galbiati said. “As borders increased and supply chains became more difficult, it remained a ray of hope for me to be able to collaborate internationally. It is important to see that as the virus spreads around the world at the speed of jets, research spreads at the speed of the internet. And if there’s a way to beat the virus, it’s if research can prevail.”

While physicists are used to collaborating remotely, telecommuting and social distancing have added new complications. Researchers working from home did not have access to their labs – or all the parts they needed to test. Instead, they connected various components through the Internet. So a microcontroller in Italy could connect and receive software written in the United States, then have someone test the interface on a touch screen in Canada.

In early April, completed prototype MVM units in temporary 3D-printed enclosures were making their way through rigorous testing in Italy and with collaborators around the world – and they worked.

“This effort is the demonstration that the particle physics community pays attention to the application of basic research to social needs,” said Fernando Ferroni, professor at the Institute of Sciences of Gran Sasso and former president of the INFN, the Italian National Institute of Nuclear Physics. Applying the efforts of hundreds of people in a very effective way was possible thanks to the level of organization and the shared vision of this community. This is an incredible result, indeed.

The end result is an open-source fan with ready-to-use parts that the MVM team hopes will close the gap between supply and demand in a short period of time. Both hardware and software designs will be made publicly available, so in principle anyone in the world could create their own version. The modular design can also be adapted to interchange parts depending on their availability in different regions of the world. Additionally, the MVM is specifically aimed at COVID-19 patients, offering two key modes – full ventilation and gentler respiratory support – available at the touch of a single button. Most traditional fans require pressing half a dozen buttons or switching between different operating modes to accomplish the same thing. Galbiati is now working with Elemaster and other manufacturers to produce fans and get them where they are needed most.

“It was great to work with such a skilled and highly motivated group of scientists and engineers,” noted Arthur McDonaldwinner of the 2015 Nobel Prize in Physics and head of Canada’s involvement in MVM, who taught at Princeton in the 1980s. “Everybody worked hard on this because they see it as a way to use their skills to help in this global crisis.We are very grateful for the contributions of our team members and all the external support we have received.

“MVM is a new paradigm, and it shows the incredible impact that basic research can have on society, thanks to its unique ability to generate new knowledge and technological innovation; it also highlights the importance of international and multidisciplinary collaboration to meet the great challenges of this new era,” said Galbiati. “Our Milan mechanical ventilator is now a reality, and we hope it will help save many lives.

Princeton collaborators on the MVM include Peter Elmera senior research physicist; Bert Harrop, senior technician in physics and at the Princeton Institute for the Science and Technology of Materials (PRISM); Andrea Ianni, Borexino General Engineer in the Department of Physics at Princeton; David Langea computational physicist; Xinran Lia graduate student in physics; Daniel Marlowprofessor of physics Evans Crawford 1911 from Princeton; Javier Romualdez, postdoctoral researcher in physics; Mojtaba Safabakhsh, Manufacturing Group Leader in Engineering and Technical Infrastructure at Princeton Plasma Physics Lab; and Jeff Thompsonassistant professor of electrical engineering who is an associate professor at PRISM.

[Editor’s note: You can hear more from Cristian Galbiati on the June 29 episode of the “We Roar” podcast, available as audio or video with closed captions.]

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