Events at Physics
Events on Thursday, May 7th, 2015
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Probing hadronic interactions with atmospheric leptons
- Time: 2:30 pm
- Place: 5280 Chamberlin Hall
- Speaker: Anatoli Fedynitch, Karlsruhe
- Abstract: Inclusive fluxes of muons and neutrinos in the atmosphere provide a continuous source of information about the spectrum and composition of cosmic rays interacting with air nuclei. Furthermore, measurements of the fluxes allow us to learn more about hadronic interactions in phase space regions not accessible at high-energy colliders. Using an accurate and flexible solution of the coupled cascade equations, called matrix-method, it is possible to study numerically the connection between atmospheric muon observations and measurements made at fixed-target or collider experiments. I will present the status of lepton
flux calculations using different interaction models and primary cosmic ray flux assumptions. Emphasis is put on the role of hadronic interactions by discussing the importance of different phase-space regions, particle species and interaction energies for the prediction of atmospheric lepton fluxes.
- Host: Paolo Desiati
- Astronomy Colloquium
- Searching for evidence for ongoing cold accretion in the local universe using the Green Bank Telescope
- Time: 3:35 pm
- Place: 4421 Sterling Hall
- Speaker: DJ Pisano, West Virginia University Physics & Astronomy
- Abstract: One of the key questions in astronomy today is how galaxies accrete the gas they need to fuel ongoing star formation. While many interferometric surveys have revealed populations of low mass HI clouds around galaxies, they have not found enough gas to sustain continued star formation. One possible explanation of this deficit is that this HI is extended and diffuse such that it is missed by interferometers. To rectify this problem, my collaborators and I are conducting a Green Bank Telescope (GBT) HI survey of about 50 local galaxies. The GBT's unique design makes it the ideal single-dish telescope for observing low column density HI and makes it capable of detecting HI emission from analogs to Lyman limit systems. I will present the initial results from our search for ongoing accretion from the ``cosmic web", how it compares with theoretical predictions, and our future plans.