University of Maryland
Atlantic Building, Room 2400
4:30 PM Monday, February 6, 2017
Coffee, Tea & Snacks 4:15-4:30 PM

Vladimir Ptuskin
IZMIRAN, Moscow, Russia
Inverse Problem for Transport of Ultra-High Energy Cosmic Rays
in Expanding Universe

The origin of ultra-high energy extragalactic cosmic rays is discussed. The propagation of nuclei with energies more than 10^18 eV in expanding Universe filled with the background electromagnetic radiation is considered. The source spectrum of extragalactic cosmic rays for protons and nuclei up to Iron is determined from the observed at the Earth spectrum of particles as the solution of inverse problem of transport of ultrarelativistic nuclei. The method of regularization of this mathematically incorrect problem is employed. The data of the Auger experiment on cosmic-ray energy spectrum, the mean logarithm of mass number and it's dispersion are used. The found energy spectra of sources are very hard and strongly depend on the composition of accelerated nuclei.

Sponsored by: Department of Physics and the Institute for Physical Science and Technology, University of Maryland. For information call Victoria at (301) 405-4811 or go to the UMD Space Physics group seminar web site.

There is free parking after 4:00 PM in lot B (the big parking garage across the street from the ATL building). There are a limited number of spaces in lot Q next to the new ATL wing with free parking after 4PM even when there is a basketball game on campus.