Astroparticle Seminar: Karen Andeen, Rutgers, "First Measurement of Cosmic Ray Composition using the IceCube Neutrino Observator"

Tue, Dec 13, 2011, 3:00 pm to 4:00 pm
Location: 
Jadwin A06
Speaker:Karen Andeen, CMS Collaboration,Rutgers the State University of New Jersey; IceCube Collaboration,University of Wisconsin-Madison, www.physics.rutgers.edu/~kandeen Host: Professor Cristiano Galbiati The recently completed IceCube Neutrino Observatory instruments a volume of roughly one cubic kilometer (one gigaton) of Antarctic ice with more than 5000 digital optical modules. While IceCube was primarily designed to detect high energy neutrinos, the overwhelming majority of events are caused by downing cosmic-ray induced muons. These muons, when measured in coincidence with events from the IceTop air shower array on the surface of the icecap, provide an indirect measurement of the cosmic ray primary particle, mediated by the physics of air shower propagation. These measurements, in conjunction with detailed simulations of the air showers interacting with our detector and a neural-network analysis technique, can be used to precisely measure the cosmic ray energy spectrum and composition at energies near and above the "knee"--a critical feature in the spectrum where the spectral index steepens. The results of the first coincident analysis from IceCube and IceTop will be presented.