Chacko Elected APS Fellow

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Category: Department News

Published: Friday, October 04 2024 06:00

Professor Zackaria Chacko has been elected Fellows of the American Physical Society. APS Fellowship recognizes excellence in physics and exceptional service to the physics community.

Chacko, who is a member of the Maryland Center for Fundamental Physics (MCFP), was cited for discovering two of the major theoretical scenarios for particle physics beyond the Standard Model — neutral naturalness and gaugino mediated supersymmetry breaking — and for inspiring experimental programs to test them.

Following his B.S. and M.S. degrees at the Indian Institute of Technology, Kharagpur, Chacko earned his Ph.D. in Physics at the University of Maryland in 1999, working with Markus Luty. While a graduate student at Maryland, he received the Michael J. Pelczar Award for Excellence in Graduate Study and was named an Outstanding Teaching Assistant.

He then held postdoctoral positions at the University of Washington and the University of California, Berkeley, before accepting the role of Assistant Professor at the University of Arizona. In 2007, he returned to the University of Maryland. He was promoted to Associate Professor in 2009 and full Professor in 2016. He has served on the department’s Priorities, Curriculum Review, and Graduate Admissions committees, and is currently a member of the editorial board of JHEP, the premier journal dedicated to elementary particle physics.

The primary focus of Chacko’s research is on proposing new theories that address the known problems of the Standard Model of particle physics which can be tested in current and future experiments. The work for which he received the award is related to a theoretical problem of the Standard Model, known as the “hierarchy problem”. The Higgs boson has a mass of order the weak scale, the mass scale of the force carriers of the weak interactions. However, in the Standard Model, quantum effects tend to make the Higgs many orders of magnitude heavier than the observed value. The fact that the Higgs is light then arises from a very delicate cancellation between completely independent effects, which seems extremely contrived.

An elegant class of solutions to the hierarchy problem involve extending the Standard Model to include new particles related to the known particles by a new symmetry of nature. The quantum effects of the new particles cancel against those of the Standard Model, explaining the lightness of the Higgs boson. Chacko was recognized for proposing two paradigms that realize this framework, gaugino mediated supersymmetry breaking and neutral naturalness, which have been enormously influential in the field and inspired novel experimental searches to discover them.    

“Chacko’s APS Fellowship highlights his highly original and influential proposals to solve one of the deepest mysteries of particle physics, the Hierarchy Problem,” said Raman Sundrum, Director of the MCFP. “This distinction is richly deserved.”

High Altitude Water Cherenkov Observatory Sheds Light on Origin of Galactic Cosmic Rays

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Category: Research News

Published: Wednesday, September 25 2024 00:01

HAWC observes Ultra-High Energy gamma rays confirming Galactic Center as a source of Ultra-High Energy cosmic ray protons in the Milky Way

The High-Altitude Water Cherenkov (HAWC) Observatory, located on the slopes of the Sierra Negra volcano in Mexico, has achieved a groundbreakingHAWC by Jordan Goodman milestone with the first detection of gamma rays exceeding 100 TeV from the Galactic Center. This provides strong evidence for the existence of a PeVatron—a source capable of accelerating particles to energies of up to petaelectronvolts (PeV), which is over one hundred times the energy achieved by particle accelerators on Earth. PeVatrons have long intrigued astrophysicists due to their role in high-energy cosmic particle acceleration. While magnetic fields in space deflect charged particles, making it difficult to pinpoint their origin, gamma rays offer a direct view into these extreme acceleration processes, shedding light on their origins within our Galaxy.

The figure shows the best-fit spectrum of the source detected by HAWC, and the resulting spectrum after subtracting two known point sources that are coincident with ours. This resulting spectrum corresponds to the diffuse emission from the Galactic Center and it shows that it extends without evidence of a cutoff to over 100 TeV.The center of our Galaxy hosts a range of remarkable astrophysical objects, including Sagittarius A*, a supermassive black hole with a mass approximately four million times that of the Sun. It is surrounded by neutron stars, white dwarfs stripping material from nearby stars, and extremely hot, dense gas clouds with temperatures reaching millions of degrees. These environments provide ideal conditions for the interaction of PeV protons, freshly accelerated by the suspected PeVatron, with protons from the surrounding matter. These  interactions produce neutral pions, which quickly decay into gamma rays, contributing to the observed photon spectrum between 6 and 114 TeV. The lack of a spectral cutoff strongly suggests a hadronic origin for these gamma rays. Furthermore, the short escape time of the PeV protons suggests the need for a quasi-continuous injection of particles into the gas to maintain the observed gamma-ray production.

The dense interstellar gas between Earth and the Galactic Center obscures this intriguing region from optical observation. Thus, the findings from the HAWC Gamma-Ray observatory provide valuable insights into the high-energy processes occurring at the core of our Galaxy, shedding light on the origin of Galactic cosmic rays.

The particle astrophysics group at UMD plays an important role in the operations of the HAWC Observatory. This particular study was led by Sohyoun Yun-Cárcamo (Ph.D. candidate), Dezhi Huang (postdoc), and Jason Fan (former UMD Ph.D. student). Other UMD authors of this paper are Jordan Goodman, Andrew Smith, Kristi Engel, Elijah Willox, and Zhen Wang.

Publication: https://iopscience.iop.org/article/10.3847/2041-8213/ad772e

William Douglass Dorland, 1965-2024

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Category: Department News

Published: Tuesday, September 24 2024 10:24

Bill Dorland, an esteemed plasma and computational physicist who last week received the American Physical Society’s James Clerk Maxwell Prize, has died at age 58. Since a 2004 diagnosis of chordoma, a rare cancer affecting the spine, he optimistically pursued emerging therapies while advocating for the chordoma community, engaging in continued physics research and serving as a superb mentor and teacher.

After completing his undergraduate studies at the University of Texas (and winning the campus foosball tournament), Dorland earned both a Ph.D. in astrophysical sciences and a Master’s degree in public affairs at Princeton University. He returned to Texas, working at the Institute for Fusion Studies, before joining the University of Maryland in 1998 when his wife, Sarah C. Penniston-Dorland, accepted a fellowship at Johns Hopkins University.

Early in his career, Dorland’s calculations revealed that an international plan to build a gigantic fusion reactor was based on flawed science, thereby saving $10 billion and preventing a probable scientific debacle.

His work modeling plasma turbulence merited the prestigious E. O. Lawrence Medal of the Department of Energy. A Diamondback profile described Dorland’s reluctance to leave his class for a call from “the secretary”, who turned out to be Secretary of Energy Steven Chu relaying news of the award and its $50,000 honorarium.

During his career, Dorland held appointments at the University of Vienna, the University of Oxford and Imperial College, London.  From 2020-23, he served as associate laboratory director for Computational Science at the U.S. Department of Energy's Princeton Plasma Physics Lab, which is managed by Princeton University.

Dorland studied in Japan during high school, and found the experience invaluable and insightful. Arriving at the University of Texas, he was shocked by paucity of such opportunities, and launched a vigorous campaign to direct a fraction of student fees toward international exchanges. The number of students studying abroad from UT grew from eight his freshmen year to more than a thousand four years later. In 2000, he received a special award by the Council on International Education Exchange.

At UMD, he co-developed new curricula, including Physics for Decision Makers: The Global Energy Crisis, a Marquee course to instruct non-science majors in perhaps the world’s most pressing challenge. He was a remarkable mentor; three of Dorland’s undergraduate advisees have received the University Medal.  Twice he officiated the weddings of UMD graduate students.

When his chordoma diagnosis prompted an assessment of his life and priorities, he sought the role of director of the UMD Honors College, recalling his own transformative experience as a UT undergrad. For seven years, he advocated for new programs and encouraged study abroad experiences. In a Maryland Today  article during that time, he described continuing his work through his tortuous medical odyssey with the support of his wife, a professor in the Department of geology, and his daughter Kendall.  The family asks that those interested in commemorating Bill do so with a donation to the Chordoma Foundation.

In 2010, Dorland was named a UMD Distinguished Scholar-Teacher (DST). In a letter supporting the nomination, one student described Dorland as “the sort of genius who, while always impressive, is never intimidating….His cheerful encouragement, quirky sense of humor, and constant support were what kept me going in graduate school, even when finishing the dissertation seemed like an impossible goal.”

In his own DST essay, Dorland wrote that after his diagnosis, “I had occasion to reconsider all the decisions I had made in life, and to adjust my trajectory accordingly for the time remaining. I spent a few weeks thinking hard, and was extraordinarily happy to find that I was already doing exactly that which gives me the most satisfaction.”

He concluded: “I generally work as hard as I can to challenge the best students at the University of Maryland to perform at their very best level. This is my mission. It is nothing more than teaching, research, and love.”

Dorland received the E.O. Lawrence Medal from the U.S. Department of Energy in 2009.

Juan Uriagereka congratulates Bill Dorland on his Distinguished Scholar-Teacher Award in 2010.

Dorland Selected for APS Maxwell Prize

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Category: Department News

Published: Monday, September 16 2024 15:24

Professor William Dorland will receive the American Physical Society’s (APS) 2024 James Clerk Maxwell Prize for Plasma Physics for “pioneering work in kinetic plasma turbulence that revolutionizes turbulent transport calculations for magnetic confinement devices and inspires research in astrophysical plasma turbulence". This honor—shared with Greg Hammett, Dorland’s doctoral advisor from Princeton University—will be presented at the 66^th Annual Meeting of the APS Division of Plasma Physics in October.

The James Clerk Maxwell Prize annually recognizes outstanding contributions to the field of plasma physics.  The prize is named after a nineteenth century Scottish physicist known for his work with electricity, magnetism and light.Bill Dorland (photo by Mark Sherwood)

Dorland graduated with a B.S. in physics (with special and highest honors) from the University of Texas in 1988, and received his Ph.D. in Astrophysical Sciences from Princeton University in 1993. He also earned a Master’s degree in Public Affairs from the Princeton School of Public and International Affairs in 1993, after completing a course of study focused on international science policy.

He then accepted an appointment as a Department of Energy Fusion Postdoctoral Fellow at the Institute for Fusion Studies of the University of Texas and rose to the rank of Associate Research Scientist before joining the University of Maryland in 1998. He holds a joint appointment in Physics and the Institute for Research in Electronics and Applied Physics (IREAP). Dorland has been a Visiting Professor of Theoretical Physics at the University of Oxford since 2010 and held a previous appointment in the Department of Physics of Imperial College, London. From 2020-23, he served as Associate Laboratory Director for Computational Science at the Princeton Plasma Physics Lab.

In 2005, Dorland was elected a Fellow of the APS Division of Plasma Physics. He won the Department of Energy’s 2009 E. O. Lawrence Medal for “his scientific leadership in the development of comprehensive computer simulations of plasma turbulence, and his specific predictions, insights, and improved understanding of turbulent transport in magnetically-confined plasma experiments”.

Dorland is a UMD Distinguished Scholar-Teacher, a recipient of the Richard A. Ferrell Distinguished Faculty Fellowship and a Merrill Presidential Faculty Mentor. He served as Director of the UMD Honors College for seven years, and afterward was cited with an Honors College Outstanding Faculty Award. Three of Dorland’s undergraduate mentees have received the University Medal.  He has been active in professional societies, contributing to APS advocacy for the international freedom of scientists, human rights and national security. He has published more than 150 journal articles.

“With his brilliant insights, Bill Dorland has fundamentally transformed the exploration of turbulence in fusion and astrophysical plasmas, and the Maxwell Prize is an immense and appropriate honor,” said Physics chair Steve Rolston. “In addition, he has been an extraordinary teacher, fantastic colleague and superb mentor. I could not be happier about this recognition.”

The prize carries a $10,000 stipend. UMD physicists who have won the Maxwell Prize include Tom Antonsen,  Phillip A. Sprangle, Roald Sagdeev, James Drake, Hans R. Griem, and Ronald C. Davidson.

Bill Dorland died days after this story was published. Read more about him here: https://umdphysics.umd.edu/about-us/news/department-news/1982-dorland.html