Events at Physics |
Events During the Week of November 29th through December 5th, 2009
Monday, November 30th, 2009
- High Energy Seminar
- Fully Leptonic Charged B Decays at Babar.
- Time: 4:00 pm
- Place: 5310 Chamberlin
- Speaker: Dr. Luke Corwin, Indiana University
- Abstract: The Babar detector was a multi-purpose particle physics detector at the PEP-II accelerator in SLAC National Laboratory. It is named after its primary objects of study, the B mesons, and a cartoon elephant. The accelerator was tuned to produce the Upsilon(4S) resonance, which almost always decays into a pair of B mesons. In this talk, I will describe the challenges and methods of searching for events in which a charged B decays into a charged lepton and a neutrino. The primary focus will be the search for charged B mesons decaying into a tau lepton and a neutrino in the recoil of a semi-leptonically decaying B. I will review complementary searches at Babar and the Belle experiment in Japan, and I will present the implications of these results for physics beyond the Standard Model.
- Host: Matthew Herndon
Tuesday, December 1st, 2009
- Chaos & Complex Systems Seminar
- Health Care Reform: what are we reforming?
- Time: 12:05 pm
- Place: 5310 Chamberlin (Refreshments will be served)
- Speaker: Linda Reivitz, UW School of Nursing
- Abstract: Health care reform, and ideas for national health insurance, have been part of our national dialogue at least since 1912, when the idea was proposed by Theodore Roosevelt . We're still talking about health care reform today. But what is health care reform. And what are we 'reforming' anyway. Is 'reform' going to happen. What would change if it did. Of all the reform ideas now being discussed, which one is 'best'? And how many people are really uninsured? The answers to these questions will be discussed by Linda Reivitz, an instructor of health policy in the UW School of Nursing and former legislation aide on Capitol Hill. Says Reivitz: as I write this in late September, two things are clear: first, the world of 'health care reform' will surely be a lot different in December, 2009 than it is today; and second, questions about public policy are rarely answered using the scientific method. Talking about health care and health reform to a seminar on Chaos and Complex Systems is totally apropos. For those who have an interest in comparing, across a number of characteristics and plan components, the leading comprehensive reform proposals being considered by the Congress, you can find this information at http://www.kff.org/healthreform/upload/healthreform_sbs_full.pdf
- Astronomy Colloquium
- The Invisibles: Revealing dark matter and the lower limit on galaxy Formation
- Time: 3:30 pm - 5:00 pm
- Place: 3425 Sterling Hall
- Speaker: Beth Willman, Haverford College
- Abstract: Tracking the growth of stellar mass in galaxies is a fundamental characterization of the galaxy population. Recent observations have shown that the total mass in L>L* red galaxies has increased by a factor of ~2 at z<1, although at different rates as a function of galaxy mass. Despite the advance made by these studies of the whole galaxy population, until recently it has not been clear if the growth of the red sequence depended on environment. Galaxy clusters are a useful probe of this as they sample the most extreme environments. However, progress toward answering this question has been hampered by a lack of deep multi-band imaging of a large sample of clusters that can be well linked to those in the local universe. To address this I will present the evolution of the red sequence as measured in 16 intermediate redshift clusters drawn from the ESO Distant Cluster Survey (EDisCS). Unlike massive x-ray selected clusters, these clusters have velocity dispersions that make them likely progenitors of clusters that populate the local Universe. I will show how the luminosity function (LF) of red-sequence galaxies in these clusters has evolved over 50% of cosmic time, highlighting the rapid buildup of the faint cluster galaxy population. I will also compare the evolution of the red sequence in clusters to the evolution of the field red sequence population and show that they evolve at different rates. Finally I will address how the total mass on the red sequence evolves in clusters and will use this to constrain the mechanisms of how red galaxies can be added to clusters. From this analysis it appears likely that some fraction of the light in recently added cluster red sequence galaxies is currently in the in the form of intracluster stars.
Wednesday, December 2nd, 2009
- No events scheduled
Thursday, December 3rd, 2009
- R. G. Herb Condensed Matter Seminar
- Recent Experiments to Probe Individual Spins of Few-Electron Silicon Quantum Dots
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: HongWen Jiang, UCLA
- Abstract: It is becoming increasingly apparent that qubits based on individual electron spins in Si quantum dots have considerable potential for scalable quantum information processing. Complementary to the active research efforts at Wisconsin, we at UCLA have developed a different type of electrostatically-confined quantum dots on Si MOS based materials. An array of electrical characterization shows that the quantum dots have unprecedented device stability and controllability. In this talk, I present results of transport measurements in the few electron regime. Unusual spin filling configurations, along with non-linear transport features associated with high-spin states will be reported. An integrated charge sensing channel adjacent to the quantum dot has been used to study the individual electron tunneling events and relaxation dynamics. The electron spin relaxation time T1 in the presence of an in-plane magnetic field is measured by the charge sensor with a pump-and-probe technique. I will discuss mechanisms leading to spin relaxation in this type of Si device.
- Host: Susan Coppersmith
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Acoustic Detection of Ultra-high Energy Neutrinos
- Time: 4:00 pm
- Place: 5310 Chamberlin
- Speaker: Naoko Kurahashi, Stanford
- Abstract: Study of Acoustic Ultra-high energy Neutrino Detection (SAUND) phase II uses 1000km^2 of ocean as a neutrino detector. SAUND<br>
aims to detect comic ray neutrinos of GZK energies and beyond<br>
(>10^18eV) acoustically by utilizing the ocean water as the target and an existing US Navy underwater microphone array as sensors. A DAQ system was developed and deployed in 2005. The experiment ran during 2006 and 2007, collecting over 1 TB of data with over 100 days of cumulative livetime. A study of the ocean ambient noise was performed using SAUND data, characterising the background for neutrino signals. Data analysis to isolate signals is performed in parallel to Monte Carlo studies of the detector to optimize cut efficiencies and set a neutrino flux limit in the ultra-high energy region. - Host: Teresa Montaruli
Friday, December 4th, 2009
- Physics Department Colloquium
- The Very High Energy Universe
- Time: 4:00 pm
- Place: 2241 Chamberlin Hall (coffee at 3:30 pm)
- Speaker: Rene Ong, UCLA
- Abstract: Our understanding of the very high energy (VHE) universe has progressed rapidly during the last few years as a result of new instruments and exciting discoveries. In particular, ground-based telescopes, such as VERITAS in southern Arizona, have discovered many astrophysical sources of VHE gamma rays, including supernova remnants, binary star systems, blazars, and radio galaxies. These telescopes are also carrying out sensitive searches for the annihilation of particle dark matter. Similar exciting results are arriving from the recently-launched Fermi Gamma-ray Space Telescope. This talk will overview what we know about the VHE universe and describe recent exciting results from VERITAS. The future prospects for high-energy gamma-ray and neutrino astronomy will be summarized.
- Host: Montaruli