A biography of Professor Sau Lan Wu was included as the cover story in a recent issue of the AIP History Newsletter (see pages 14-15). The story covers her early life in Hong Kong, her arrival in the U.S. to attend college at Vassar which she attended on a full scholarship, and into her graduate studies and subsequent research programs at MIT, UW–Madison and CERN. There is also a list of references / further readings. Check out the article to learn more about Prof. Wu’s illustrious career so far!
The Department of Physics is pleased to announce that Prof. Yang Bai has been promoted to the rank of full professor.
“It is my pleasure and honor as Dean to approve Prof. Yang Bai’s promotion to Full Professor. His creativity and impressive breadth in particle physics research make him a leader not only on dark matter, but also more generally on Beyond-the-Standard-Model Physics,” says Eric Wilcots, Dean of the College of Letters & Science. “He is also a valued teacher, appreciated by students especially at the graduate level. Graduate students and junior researchers in Madison are in good hands.”
Bai joined the department in 2012, and was promoted to associate professor in 2017. In addition to his robust and well-funded research program, he has trained several successful graduate students, taught all levels of departmental courses, and served on several departmental and university committees.
“Professor Yang Bai is widely recognized as one of the leading theoretical particle physicists of his generation with a broad and vigorous research program, covering both the collider-related frontiers and the cosmic frontier. His work includes significant contributions in essentially every area related to dark matter,” says Sridhara Dasu, professor and department chair. “The Physics Department very strongly endorses the promotion of Yang Bai to Full Professor.”
Congrats, Prof. Bai on this well-earned recognition!
Neutrinos mix and transform from one flavor to the other. So do quarks. However, electron and its heavier cousins, the muon and the tau, seem to conserve their flavor identity. This accidental conservation of charged lepton flavor must have a profound reason, or low-levels of violation of that conservation principle should occur at high energy scales. However, evidence for any charged lepton flavor violation remains elusive.
The CMS group recently published a new study on Lepton flavor in Higgs boson decays. At UW–Madison, the effort was led by Sridhara Dasu and postdoctoral researcher Varun Sharma, building off of work done by former postdoctoral researcher Maria Cepeda and former graduate student Aaron Levine.
The international CMS collaboration recently published a news story about this new study. Please read the full story here.
For decades, researchers assumed the cosmic rays that regularly bombard Earth from the far reaches of the galaxy are born when stars go supernova — when they grow too massive to support the fusion occurring at their cores and explode.
Those gigantic explosions do indeed propel atomic particles at the speed of light great distances. However, new research suggests even supernovae — capable of devouring entire solar systems — are not strong enough to imbue particles with the sustained energies needed to reach petaelectronvolts (PeVs), the amount of kinetic energy attained by very high-energy cosmic rays.
And yet cosmic rays have been observed striking Earth’s atmosphere at exactly those velocities, their passage marked, for example, by the detection tanks at the High-Altitude Water Cherenkov (HAWC) observatory near Puebla, Mexico. Instead of supernovae, the researchers — including UW–Madison’s Ke Fang — posit that star clusters like the Cygnus Cocoon serve as PeVatrons — PeV accelerators — capable of moving particles across the galaxy at such high energy rates.
For the full news story, please visit https://www.mtu.edu/news/stories/2021/march/not-so-fast-supernova-highestenergy-cosmic-rays-detected-in-star-clusters.html.
New UW–Madison assistant professor of physics Lu Lu’s research program combines the past with the future. Her research looks for sources of ultrahigh energy particles, which is done by analyzing data that has already been collected. As she says, “Maybe data is already talking to us, we just haven’t looked.” But she is also working toward improving future data collection, which will require more technologically-advanced detectors. “My teachers, my great masters, have taught me that the current young generation has the responsibility to look into new techniques to go to the future for younger generations to proceed forward,” she says about her work in sensor R&D.
On January 1, Professor Lu joined the Department of Physics and IceCube. Most recently, she was a postdoctoral fellow at the International Center for Hadron Astrophysics at Chiba University in Japan. To welcome her, we sat down for a (virtual) interview.
What are your research interests?
My prime interest is astroparticle physics, and my ultimate goal is to find the sources of the highest energy particles in the universe. These particles carry energy of about 1020 electronvolts. This is higher energy than what we have from the Large Hadron Collider and human technologies. The real attractiveness here is we don’t know how nature accelerates these particles. And once we identify the sources, we can test new theories beyond the Standard Model using sources crated by nature.
What are one or two main projects you focus your research on?
I’m involved in two experiments. One is IceCube, the other is Pierre Auger Observatory. I was doing cosmic ray analysis, but cosmic rays are usually charged particles and they are deflected in the magnetic field of the galaxy; they would not travel in a straight line. IceCube studies neutrinos which are neutral particles, they travel directly from the source. Pierre Auger detects ultrahigh energy photons, which are also neutral particles. One thing I want to do immediately after I join Madison is to combine these two experiments to do a joint analysis. We have photon candidates but we haven’t really tried to connect them in the multimessenger regime. By combining Pierre Auger photons with IceCube neutrinos, we could possibly find a transient source, a source that doesn’t constantly emit ultrahigh energy photons or neutrinos but all of a sudden there’s a flare. This type of analysis has never been done, but we have data on disks.
The second thing I’m interested in is using new sensor technologies. In IceCube, we have Gen2 being planned right now. Instead of using a single photon sensor, we’d use a more sensitive design and R&D. UW–Madison is taking the lead of designing this future detector. There’s also radio technology. So, to detect the highest energy neutrinos we need to build a large instrument volume. With optical array, it is really hard to scale up because one has to drill holes inside the South Pole, which is really expensive. But radio technology doesn’t have to go so deep, so they can bury their detectors on the surface areas, and the radiowaves can transmit further away than the optical photons in ice. For optical you have to make the detectors very dense, but for radio you can make the antennas further apart, so that means you can have a larger area and detect more events easily. I think radio is the way to go for the future.
You said you have a lot of data collected already and just need to analyze it. How do you analyze the data from these detectors?
We would have to search for photon candidates from the data from Auger, and identify where it comes from and what the time this event happened. Correspondingly, do we see neutrinos from IceCube coming from the same direction and at the same time? Because you can never be sure it’s a photon. It could be a proton. We then want to build a statistical framework to combine different multimessengers together in real time.
What does it mean if you find a photon in coincidence with a neutrino?
Cosmic rays were first detected more than 100 years ago, and there’s a rich history of studying where they come from. The mystery of origins still remains today because our poor knowledge on the galactic/extragalactic magnetic fields and mass composition of cosmic rays. In my opinion, the most probable way to solve this puzzle is to use neutral particles. If we can identify ultrahigh energy photons in coincidence with neutrinos, that is a smoking gun that we are actually looking at a source and we can finally pin down where in the universe is accelerating high energy particles. And therefore, we can study particle physics maybe beyond Standard Model. It’s just like a lab created by the universe to test particle physics.
What is your favorite element and/or elementary particle?
My favorite elementary particle is the electron anti-neutrino. I like muons, too. My favorite element is hydrogen.
What hobbies and interests do you have?
I’m afraid I’ll disappoint you because my hobby is related to my research: Augmented reality. When I heard about something called Microsoft Hololens, I thought, I could make IceCube a hologram. I bought these special glasses, and then made a program on it and used it for some outreach events. But the glasses are very expensive, so people said, “Okay we can’t buy hologram glasses.” So I moved it to mobile phones so that everyone could look at it for fun. It’s called IceCubeAR (note: download it for iPhones or Android phones). I made it with a group of friends in Tokyo.
The Daya Bay Reactor Neutrino Experiment collaboration – which made a precise measurement of an important neutrino property eight years ago, setting the stage for a new round of experiments and discoveries about these hard-to-study particles – has finished taking data. Though the experiment is formally shutting down, the collaboration will continue to analyze its complete dataset to improve upon the precision of findings based on earlier measurements.
The detectors for the Daya Bay experiment were built at UW–Madison by the Physical Sciences Laboratory, and detailed in a 2012 news release.
Says PSL’s Jeff Cherwinka, U.S. chief project engineer for Daya Bay:
The University of Wisconsin Physics Department and the Physical Sciences Lab were very involved in the design, fabrication and installation of the anti-neutrino detectors for the Daya Bay Experiment. It was a great opportunity for faculty, staff, and students to participate in an important scientific measurement, while learning about another country and culture. There were many trips and man years of effort in China by UW physicists, engineers and technicians to construct the experiment and many more for operations and data taking. This international collaboration took a lot of effort, and in the end produced great results.
The chief experimentalist at UW–Madison was Karsten Heeger who has since left for Yale. At present, Prof. Baha Balantekin is the only one remaining at UW–Madison in the Daya Bay Collaboration.
A completion ceremony will be held Friday, December 11from 7:30-8:3opm CST. Video stream options and the full story can be found at Berkeley Lab’s website.
Three UW–Madison physics professors and their colleagues have been awarded a U.S. Department of Energy (DOE) High Energy Physics Quantum Information Science award for an interdisciplinary collaboration between theoretical and experimental physicists and experts on quantum algorithms.
The grant, entitled “Detection of dark matter and neutrinos enhanced through quantum information,” will bring a total of $2.3 million directly to UW-Madison. Physics faculty include principal investigator Baha Balantekin as well as Mark Saffman, and Sue Coppersmith. Collaborators on the grant include Kim Palladino at the University of Oxford, Peter Love at Tufts University, and Calvin Johnson at San Diego State University.
With the funding, the researchers plan to use a quantum simulator to calculate the detector response to dark matter particles and neutrinos. The simulator to be used is an array of 121 neutral atom qubits currently being developed by Saffman’s group. Much of the research plan is to understand and mitigate the behavior of the neutral atom array so that high accuracy and precision calculations can be performed. The primary goal of this project is to apply lessons from the quantum information theory in high energy physics, while a secondary goal is to contribute to the development of quantum information theory itself.
The High Energy Physics (HEP) group at UW–Madison, which broadly focuses on identifying and understanding the fundamental aspects of particles and forces in Nature, has been awarded three significant grants in 2020. The grants — two from the Department of Energy (DOE) and one from the National Science Foundation (NSF) — are awarded either directly to UW–Madison or indirectly through multi-institution international collaborations, bringing over $14 million to the department.
The first grant, $7.37 million from DOE, funds research that is expected to help physicists understand how our Universe works at its most fundamental level. At UW–Madison, this research includes experimental and theoretical studies into topics such as using the Higgs boson as a tool for new discoveries and identifying principles of dark matter.
The grant will fund five areas of research: 1) studies of high energy proton-proton collisions; 2) studies of neutrino interactions; 3) studies of super-weak signals from galactic dark matter particles; 4) wide-area imaging surveys using powerful new telescopes; and 5) computational and mathematical methods of quantum field theory and string theory.
Sridhara Dasu is principal investigator on this DOE grant. Co-investigators include Yang Bai, Vernon Barger, Keith Bechtol, Kevin Black, Tulika Bose, Lisa Everett, Matthew Herndon, Kimberly Palladino, Brian Rebel, Gary Shiu, Jennifer Thomas (WIPAC), and Sau Lan Wu. The grant was awarded in June 2020 and provides funding through March 2023.
The other two grants awarded will provide funding for upgrades to the Compact Muon Solenoid (CMS) project at the Large Hadron Collider (LHC) at CERN. The first is an NSF-funded grant for which Kevin Black is leading the UW–Madison effort to upgrade the CMS End Cap muon system upgrade. The $900,000 to the department is part of a larger multi-institutional grant through Cornell University and runs through 2025.
“The GEM detectors are novel micropattern gas detectors which can handle the high background rates expected in the end-cap muon detectors. They will enhance the triggering and reconstruction of forward muons which are expected to make significant improvements and increased acceptance to search for new particles and make precision measurements of known particles and interactions,” Black explains. “UW has a long history with CMS muon system with Prof Matt Herndon, Senior Emeritus Scientist Dick Loveless, and Senior Scientist Armando Lanaro leading to the design, construction, operation, and upgrade of the other end-cap subdetector system instrumented with Cathode Strip Chambers.”
The other CMS-specific grant is a four-year, $5.3 million DOE grant through Fermilab that will fund the CMS trigger upgrade. This funding will allow the UW–Madison CMS group to perform all aspects of the work involved in design, prototyping, qualification, production and validation of the calorimeter trigger system for the upgrade. When completed, the project is expected to result in the collection of 25 times more data than is currently possible. Sridhara Dasu is the principal investigator of this grant.
The J.J. Sakurai Prize is considered one of the most prestigious annual prizes in the field of theoretical high energy physics. Barger, who joined the UW–Madison faculty in 1965, is a world leader in theoretical particle physics where theory meets experiment. He is one of the founders of collider phenomenology as it is practiced today.
“This prize belongs to the hundreds of students, postdocs, faculty and visiting colleagues who entered the portal of UW–Madison to discover the quarks, leptons and bosons of particle physics,” Barger says. “Only at UW–Madison could this research at the interface of theory and experiment so thrive.”
The techniques that Barger helped develop have been crucial in establishing the experimental foundations of the Standard Model of particle physics and in guiding the search for signals of new physics. His contributions have played a key role in many important milestones in particle physics, including the discovery of the W boson in 1985, the top quark in 1995, and the Higgs boson discovery in 2012.
UW–Madison physics professor Lisa Everett and University of Hawaii professor Xerxes Tata, both phenomenologists, co-nominated Barger for the prize.
“We are thrilled that Vernon Barger has been awarded the 2021 J.J. Sakurai Prize, for which we nominated him for his seminal accomplishments and leadership record in collider physics phenomenology over five decades in the field,” Everett says. “The techniques he has pioneered have and continue to be of pivotal importance for elucidating physics signals at particle colliders, and these contributions are only part of a very long and distinguished research career in theoretical particle physics. He is highly deserving of this honor.”
UW–Madison chemistry professor Martin Zanni also won an APS award, the Earle K. Plyler Prize for Molecular Spectroscopy & Dynamics. Read the UW–Madison news piece about both Barger and Zanni’s awards here.
Shortly after incoming physics graduate student Winnie Wang attended a UW–Madison campus visit weekend in February, her plans took an abrupt change due to COVID-19. The University of Massachusetts, where she was studying, closed right before spring break, and she decided to go to Taipei to be with extended family. But first, she needed to follow the regulations in Taiwan and self-isolate for 14 days.
“I chose to be quarantined in a hotel, so I was by myself for two weeks. It was honestly kind of brutal, and for the first five days I was feeling pretty miserable,” Wang recalls. “I’m putting it bluntly, because that misery was what inspired me to do something about it. I was like, ‘Okay, well, why don’t I proactively use some of my free time.’”
Wang, who is from Canada and attended school in the U.S., watched what was happening to the case numbers in those two countries, especially compared to the relatively lower numbers in Taiwan, and started looking for ways to get involved. She posted on Facebook asking if anyone knew groups she could volunteer with, and eventually landed on a group called N95DECON.
According to the group’s website, N95DECON is a volunteer collective of scientists, engineers, clinicians, and students from universities across the U.S. as well as other professionals in the private sector. N95DECON seeks to review, collate, publish, and disseminate scientific information about N95 decontamination to help inform decisions about N95 decontamination and reuse.
“Hospitals use a lot of N95s, and you’ve probably heard of things where people have put masks in microwaves or rice cookers to decontaminate them. And basically, you don’t want to do that,” Wang says. “We looked at the research that’s already out there, looked at what the CDC recommends, and we culminated our findings into papers and seminars for hospitals to use around the world.”
Wang serves as a communications volunteer for the group, meaning she responds to emails and proofreads and edits the group’s publications. She says that when she first started, N95DECON did not have much in the way of formal documentation, so much of her early efforts were spent answering emails from the public asking about reuse procedures. But knowing that N95s were in short supply and time was of the essence, N95DECON worked quickly to put together online seminars that could be viewed by anyone.
“After we organized and recorded the seminars in May and put them on our website so that anyone can watch them, the email team received less email from the general public,” Wang says. “And I’ve moved on now to more literature review.”
N95DECON shared their work largely through the hospital networks of the health professionals that volunteer with the group, as well as through social media and other word-of-mouth. The group will continue to monitor research on best practices for decontaminating and reusing N95 masks and update their recommendations accordingly. Much of their current efforts are focused on translating their papers and seminars.
“We’d have people from all over the world join our seminars and talk about their experiences,” Wang says. “So, another aspect of our outreach is that we do translations. Our goal is to disperse this information around the world, and we’ve translated it into seven languages now.”
Wang plans to continue volunteering with N95DECON after the UW–Madison academic year begins. She is interested in studying experimental high energy physics for her doctorate.