Events at Physics |
Events During the Week of September 4th through September 11th, 2022
Monday, September 5th, 2022
- Academic Calendar
- Labor Day
- Abstract: *Note: actual end time may vary.* University offices closed. URL:
Tuesday, September 6th, 2022
- Academic Calendar
- Deadline for students to cancel fall enrollment and have no fall term record on transcript
- Abstract: *Note: actual end time may vary.* CONTACT: 262-3811, registrar@em.wisc.edu URL:
- Academic Calendar
- Graduate School Fall 2022: Fall degree window period deadline for master's students
- Time: 4:00 pm - 5:00 pm
- Abstract: CONTACT: 262-2433, gsacserv@grad.wisc.edu URL:
- Academic Calendar
- Graduate School Fall 2022: Fall degree window period deadline for doctoral students
- Time: 11:55 pm - 12:55 am
- Abstract: CONTACT: 262-2433, gsacserv@grad.wisc.edu URL:
Wednesday, September 7th, 2022
- Academic Calendar
- Fall semester instruction begins
- Abstract: *Note: actual end time may vary.* URL:
Thursday, September 8th, 2022
- Theory Seminar (High Energy/Cosmology)
- Axion Solar Halos
- Time: 12:00 pm
- Place: Chamberlin 5280
- Speaker: Joshua Eby, Tokyo U., IPMU
- Abstract: Ultralight dark matter (ULDM) is known to form self-gravitating bound states through gravitational relaxation. There are intriguing hints in the literature suggesting similar dynamics might lead to overdensities in the solar system as well, with ULDM becoming bound to the Sun. These Solar Halos can be probed by experiments on Earth when their radius R > 1 AU, which implies ULDM particle masses m < 10^{-14} eV. For larger masses m, space-based missions on orbits within 1 AU can probe small, compact Solar Halos with exceptional reach; for scalar couplings probable in current and near-future atomic clock systems, the sensitivity can exceed that of Equivalence Principle tests and probe well-motivated space for natural scalar field models. I will review the state of the art on these topics, including the use of asteroids as direct probes of DM density, as well as several exciting NASA and international missions that motivate searches aboard space probes.
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Light at the end of the tunnel: Astrophysical searches for axion-like particles in gamma-ray energies
- Time: 2:30 pm - 3:30 pm
- Place: Chamberlin 4274
- Speaker: Milena S. Crnogorcevic, University of Maryland
- Abstract: Axion-like particles (ALPs) are a well-motivated candidate for constituting a significant fraction of dark matter. They are produced in high-energy environments, such as core-collapse supernovae (CCSNe), and could undergo conversion into gamma-rays in the presence of an external magnetic field, with a characteristic spectrum peaking in the 30--100-MeV energy range. CCSNe are often invoked as progenitors of ordinary long gamma-ray bursts (GRBs), allowing us to conduct a search for potential ALP spectral signatures using GRB observations with Fermi Large Area Telescope (LAT). In this presentation, I will talk about using the Fermi LAT's low-energy (LLE) technique which, in contrast to the standard LAT analysis, allows for a larger effective area for energies down to 30 MeV. I will summarize the statistical methods used in our analysis and the underlying physical assumptions, the feasibility of the upper limits on ALP coupling from our model comparison results, and an outlook on future MeV instruments in the context of ALP searches.
- Host: Ke Fang
Friday, September 9th, 2022
- Academic Calendar
- Deadline for students (except Special and Guest) to begin initial Fall term enrollment without $50 late fee
- Abstract: *Note: actual end time may vary.* CONTACT: 262-3811, registrar@em.wisc.edu URL:
- Physics Department Colloquium
- Cherenkov Imaging in Humans, during Radiation Therapy
- Time: 3:30 pm - 6:00 pm
- Place: 2103 Chamberlin Hall
- Speaker: Brian W. Pogue, UW-Madison
- Abstract: Radiotherapy is the controlled delivery of high energy MV and MeV radiation to human tissue, in a manner that maximizes damage to cancer tissues, while minimizing damage to normal tissues. The control of this delivery and visualization of it requires several advanced technologies for guidance. An example is the use of time-gated Cherenkov imaging as a tool for the therapists to see what is happening within the room where the treatment is occurring. The invention and development of this approach will be outlined, where single photon imaging is achieved with full ambient room lighting. Additionally, these cameras can be used for scintillator spot imaging as a way to achieve non-contact radiation dose measurement. A recent offshoot of this work has been in the setting of ultra-high dose rate radiation delivery, which has been termed “FLASH’ radiotherapy. This technique uses dose rates >40 Gy/s and instantaneous dose rates of >105 Gy/s to deliver the radiation, and has an apparent normal tissue sparing effect. This technique has become intensely investigated in the last 5 years, because it holds potential for a revolutionary change in how radiation therapy is delivered. The hypothesized models of this ‘FLASH’ effect and the physio-chemical measurements to discern the mechanisms will be reviewed, along with the Cherenkov based dosimetry methods being developed. Biography Brian W. Pogue, PhD is Chair of the Department of Medical Physics at the University of Wisconsin-Madison, and Professor of Medical Physics, Radiology and Human Oncology, and Adjunct Professor of Engineering at Dartmouth. Dr Pogue’s work in the area of optical imaging devices to guide cancer therapies, has led to the invention of a unique system for imaging radiation dose with Cherenkov emission, and another unique approach to imaging hypoxia during surgical resection. Each of these is supported by NIH funding, and this translational work led to co-founding of three start-ups companies DoseOptics LLC, QUEL Imaging LLC and Hypoxia Surgical LLC. This work has led to US Patents, with 12 issued and 29 pending, and more than 450 peer-reviewed papers. Dr Pogue is a Fellow member of Optica, SPIE, AIMBE, and the National Academy of Inventors, and is the Editor-in-Chief of the Journal of Biomedical Optics.
- Host: Albrecht Karle