HR: 15:28h
AN: AE53A-10    [Abstracts]
TI: RHESSI Observations of Terrestrial Gamma-Ray Flashes
AU: * Smith, D M
EM: dsmith@scipp.ucsc.edu
AF: Physics Department and Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, 1156 High St, Santa Cruz, CA 95060 United States
AU: Lopez, L I
EM: astrolili@ssl.berkeley.edu
AF: Physics Department and Space Sciences Laboratory, University of California, Berkeley, Berkeley, CA 94720 United States
AU: Lin, R P
EM: rlin@ssl.berkeley.edu
AF: Physics Department and Space Sciences Laboratory, University of California, Berkeley, Berkeley, CA 94720 United States
AU: Barrington-Leigh, C P
EM: cpbl@interchange.ubc.ca
AF: University of British Columbia, 2329 West Mall, Vancouver, BC V6T 1Z4 Canada
AB: Terrestrial gamma-ray flashes (millisecond bursts of gamma-rays seen from space) have been observed by only one instrument until now, the Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray Observatory. BATSE saw less than one event per month, but its 9-year lifetime was enough to establish a connection between these events and thunderstorms, suggesting a connection with other upper-atmosphere phenomena such as sprites and blue jets. Using data from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) satellite, we find that these events extend up to extremely high energies ($>$ 10 MeV) as predicted by theories of runaway breakdown -- BATSE was unable to establish this as its highest-energy channel included everything from 300 keV up. We also find an average of 12 events per month, despite having smaller collecting area than BATSE, indicating that the phenomenon is much more common than previously thought. RHESSI returns every photon with a 1-microsecond time tag, while BATSE had to trigger a special burst mode in order to get high-time-resolution data; this may account for RHESSI's ability to find more events. We will present individual and statistical properties of the RHESSI TGFs and report on efforts to correlate them with lightning storms, individual lightning strokes/sferics, and sprites/blue jets.
DE: 7554 X rays, gamma rays, and neutrinos
DE: 3324 Lightning
DE: 2451 Particle acceleration
DE: 3304 Atmospheric electricity
SC: Atmospheric and Space Electricity [AE]
MN: 2004 AGU Fall Meeting