HAWC’s Measurement of the Highest Energy Photons Sets Limits on Violations of Relativity

New measurements confirm, to the highest energies yet explored, that the laws of physics hold no matter where you are or how fast you're moving. Observations of record-breaking gamma rays prove the robustness of Lorentz Invariance—a piece of Einstein's theory of relativity that predicts the speed of light is constant everywhere in the universe. The High Altitude Water Cherenkov observatory in Puebla, Mexico detected the gamma rays coming from distant galactic sources. UMD authors on the paper were Jordan Goodman, Andy Smith, Bob Ellsworth, Kristi Engel, Israel Martinez-Castellanos, Michael Schneider and Elijah Tabachnick.

Goodman Hawc 2020This compound graphic shows a view of the sky in ultra-high energy gamma rays. The arrows indicate the four sources of gamma rays with energies over 100 TeV from within our galaxy (courtesy of the HAWC collaboration) imposed over a photo of the HAWC Observatory’s 300 large water tanks. The tanks contain sensitive light detectors that measure showers of particles produced by the gamma rays striking the atmosphere more than 10 miles overhead. Credit: Jordan Goodman

"How relativity behaves at very high energies has real consequences for the world around us," said Pat Harding, an astrophysicist in the Neutron Science and Technology group at Los Alamos National Laboratory and a member of the HAWC scientific collaboration. "Most quantum gravity models say the behavior of relativity will break down at very high energies. Our observation of such high-energy photons at all raises the energy scale where relativity holds by more than a factor of a hundred."

Lorentz Invariance is a key part of the Standard Model of physics. However, a number of theories about physics beyond the Standard Model suggest that Lorentz Invariance may not hold at the highest energies. If Lorentz Invariance is violated, a number of exotic phenomena become possibilities. For example, gamma rays might travel faster or slower than the conventional speed of light. If faster, those high-energy photons would decay into lower-energy particles and thus never reach Earth.

The HAWC Gamma Ray Observatory has recently detected a number of astrophysical sources which produce photons above 100 TeV (a trillion times the energy of visible light), much higher energy than is available from any earthly accelerator. Because HAWC sees these gamma rays, it extends the range that Lorentz Invariance holds by a factor of 100 times.

"Detections of even higher-energy gamma rays from astronomical distances will allow more stringent the checks on relativity. As HAWC continues to take more data in the coming years and incorporate Los Alamos-led improvements to the detector and analysis techniques at the highest energies, we will be able to study this physics even further," said Harding.

Story courtesy of Los Alamos National Laboratory. Article: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.124.131101


Physics Student Named 2020 Goldwater Scholar

moroch goldwaterScott Moroch, courtesy of same

Scott Moroch was one of four CMNS undergraduates to receive a scholarship from the Barry Goldwater Scholarship and Excellence in Education Foundation, which encourages students to pursue advanced study and research careers in the sciences, engineering and mathematics.  Over the last decade, UMD’s nominations yielded 33 scholarships—the most in the nation, followed by Stanford University with 32. Harvard University, the Massachusetts Institute of Technology and Johns Hopkins University also rank in the top 10. Moroch is the eighth physics undergraduate recipient in the past four years. 

“Our scholars are a uniquely talented group, already making discoveries in their fields of study—from developing more stable batteries and innovative power supplies to streamlining the pathway of drug design and understanding the contributions of RNA in cancer and other diseases,” said Robert Infantino, associate dean of undergraduate education in the College of Computer, Mathematical, and Natural Sciences. Infantino has led UMD’s Goldwater Scholarship nominating process since 2001.

Moroch was among the 396 Barry Goldwater Scholars selected from 1,343 students nominated nationally this year. Goldwater Scholars receive one- or two-year scholarships that cover the cost of tuition, fees, books, and room and board up to $7,500 per year. These scholarships are a stepping-stone to future support for the students’ research careers. The Goldwater Foundation has honored 70 UMD winners and five honorable mentions since the program’s first award was given in 1989.

Moroch, a native of Wayne, New Jersey, designed his own particle accelerator when he was still in high school. Since enrolling at Maryland, he has been working on UMD’s cyclotron with Timothy Koeth, an assistant professor in the Department of Materials Science and Engineering and the Institute for Research in Electronics and Applied Physics.

A cyclotron is a type of particle accelerator that won its inventor the Nobel Prize in physics in 1939. The beams that cyclotrons produce, while potentially dangerous, accomplish wondrous things—killing cancer cells with extreme precision, for instance, or changing atoms into a different element altogether.

Moroch is working with Koeth to develop a novel cyclotron storage ring for Lockheed Martin. The company is interested in using the technology for a new class of power supplies for aerospace electric propulsion systems that can carry things into the solar system and beyond.

With initial funding from Lockheed, Moroch showed that a cyclotron design could be effective, but it was unstable. So the company decided to fund a more ambitious project at UMD—where the instabilities could be factored out. Moroch now leads a significant portion of the research team.

“Scott is no ordinary exceptional student,” said E. H. “Ned” Allen, senior fellow and chief scientist at Lockheed Martin. “He has won so much respect that he has become a colleague and a first-line team member—even though still an undergraduate.”

Last summer and fall, Moroch led a team of three undergraduates in assembling and upgrading a low-energy storage ring as part of the project. A storage ring is a type of particle accelerator in which a continuous or pulsed particle beam may be kept circulating typically for many hours. The students retrieved used components from another university, restored the retrieved components, designed and fabricated missing subsystems, reassembled them into a working ion storage ring, and brought the whole assembly under high vacuum. The new accelerator got up and running early in the spring semester, achieving what’s known as “first beam.”

“In the past 20 years, I have mentored several dozen undergraduate researchers, and Scott Moroch is the first that has demonstrated the entire cycle of research and brought in substantial research funds,” Koeth said.

Moroch also helped design an electron beamline in collaboration with Los Alamos National Laboratory. In graduate school, Moroch plans to pursue a Ph.D. in accelerator physics.

Read about the other CMNS recipients here.

Jarzynski Wins Simons Fellowship

Chris Jarzynski,  a Distinguished University Professor in the University of jarzynski by levine 23Christopher Jarzynski. Photo: byFaye Levine Maryland’s Department of Chemistry and Biochemistry, Department of Physics, and Institute for Physical Science and Technology (IPST), is one of three faculty members in the University of Maryland’s College of Computer, Mathematical, and Natural Sciences (CMNS) to received a 2020 Simons Foundation Fellowship. The prestigious fellowships provide support for faculty scientists to extend a one-term, university-sponsored sabbatical into a full year, allowing them to focus solely on advancing fundamental research in mathematics or theoretical physics.

UMD researchers received 2 of the 40 fellowships awarded for mathematics and one of the eight fellowships for theoretical physics. UMD topped the list with the most 2020 Simons Fellows, tied with the University of Michigan, the University of Illinois at Urbana-Champaign and Stony Brook University. UMD’s 2020 Simons Fellows join six other CMNS faculty members who were named Simons Fellows since 2013.

“We are very pleased to congratulate all three of these very accomplished researchers,” said CMNS Dean Amitabh Varshney. “The awarding of this very competitive fellowship to three of our researchers demonstrates UMD’s strength in fundamental research in both mathematics and physics.” 

Jarzynski is a statistical physicist and theoretical chemist who models the random motions of atoms and molecules. Working at the boundary between chemistry and physics, Jarzynski studies how the laws of thermodynamics—originally developed to describe the operation of steam engines—apply to complex microscopic systems such as living cells and artificial nanoscale machines.

Jarzkynski is well known for developing an equation to express the second law of thermodynamics for systems at the molecular scale. The equation is known as the Jarzynski equality, which was noted by the Nobel Committee for Physics as an application of the 2018 prize-winning invention, optical tweezers. This research has led to a new method for measuring “free energy”—the energy available to any system to perform useful work—in extremely small systems.

A Fellow of the American Physical Society (APS) and the American Academy of Arts and Sciences, Jarzynski received the APS 2019 Lars Onsager Prize, which recognizes outstanding research in theoretical statistical physics. He was also awarded a Fulbright Fellowship and the Raymond and Beverly Sackler Prize in the Physical Sciences. He serves on the editorial board for the Journal of Statistical Mechanics: Theory and Experiment and is an associate editor for the Journal of Statistical Physics.

Jarzynksi earned his B.A. in physics from Princeton University and his Ph.D. in physics from the University of California, Berkeley. After a postdoctoral appointment at the Institute for Nuclear Theory in Seattle, he spent 10 years at Los Alamos National Laboratory. He has been on the faculty of the University of Maryland since 2006.

During his sabbatical, Jarzynski will be based at UMD but intends to travel to Europe and California for workshops, visiting professorships and collaborations.

 UMD's other Simons Fellows were Professor Jacob Bedrossian of the Department of Mathematics and the Center for Scientific Computation and Mathematical Modeling and Professor Leonid Koralov of the Department of Mathematics.

Original story here.