2009 APS April Meeting
Volume 54, Number 4
Saturday–Tuesday, May 2–5, 2009;
Denver, Colorado
Session G4: New Eyes on the Universe I
8:30 AM–10:18 AM,
Sunday, May 3, 2009
Room: Plaza F
Sponsoring
Unit:
DAP
Chair: Steven Barwick, University of California, Irvine
Abstract ID: BAPS.2009.APR.G4.2
Abstract: G4.00002 : TIGER: Progress in Determining the Sources of Galactic Cosmic Rays
9:06 AM–9:42 AM
Preview Abstract
Abstract
Author:
Martin Israel
(Washington University in St. Louis)
The Trans-Iron Galactic Element Recorder (TIGER) is a 1-square-meter
detector system composed of scintillators, Cherenkov detectors, and
scintillating optical fibers, which gives excellent resolution of individual
elements in the cosmic rays. With two high-altitude balloon flights over
Antarctica, TIGER accumulated fifty days of data on the elemental
composition of the rare galactic cosmic rays heavier than Ni, measuring the
abundances of Cu, Zn, Ga, Ge, Se, and Sr, as well as the more abundant
lighter elements. After accounting for fragmentation of cosmic rays as they
propagate through the Galaxy and the atmosphere above the detector system,
the source material appears to be a mixture of about 80{\%} ``standard''
Solar-System composition and 20{\%} ejecta from massive stars. This mixture
supports a model of cosmic-ray origin in OB associations, as has previously
been inferred from the isotopic composition of the more abundant elements,
Ni and lighter. These TIGER data also support a cosmic-ray acceleration
model in which elements present in interstellar grains are accelerated
preferentially compared with those found in interstellar gas. This emerging
model of cosmic-ray origin and acceleration will be further tested with a
similar but much larger instrument that will give much better statistics,
improve the precision of TIGER'S studies and allowing more rare elements to
be studied; Super-TIGER development is beginning now, leading to its first
balloon flight in December 2012.
The TIGER investigation is a collaboration among scientists at Washington
University in St. Louis, NASA Goddard Space Flight Center, California
Institute of Technology, Jet Propulsion Laboratory, and University of
Minnesota. Principal funding for this research was from NASA under grant
NNG05WC04G. We also acknowledge the excellent work of the staff of the
Columbia Scientific Balloon Facility, the NASA Balloon Program Office, and
the NSF Office of Polar Programs.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.APR.G4.2