HR: 0800h
AN: SH22A-0837    [Abstracts]
TI: Search for Solar Neutrons Using the MESSENGER Neutron Spectrometer Between 0.7 and 0.32 AU
AU: * Feldman, W C
EM: feldman@psi.edu
AF: Planetary Science Institute, 1700 East Ft. Lowell, Suite 106, Tucson, AZ 85719-2395, United States
AU: Lawrence, D J
EM: djlawrence@lanl.gov
AF: Los Alamos National Laboratory, Mail Stop D466, Los Alamos, NM 87545, United States
AU: McNutt, R L
EM: ralph.mcnutt@jhuapl.edu
AF: Johns Hopkins Applied Physics Laboratory, Johns Hopkins Road, Laurel, Md 20723, United States
AU: Goldsten, J O
EM: john.goldsten@jhuapl.edu
AF: Johns Hopkins Applied Physics Laboratory, Johns Hopkins Road, Laurel, Md 20723, United States
AU: Rhodes, E A
EM: ed.rhodes@jhuapl.edu
AF: Johns Hopkins Applied Physics Laboratory, Johns Hopkins Road, Laurel, Md 20723, United States
AU: Vilas, F
EM: fvilas@mmto.org
AF: Planetary Science Institute, 1700 East Ft. Lowell, Suite 106, Tucson, AZ 85719-2395, United States
AB: The MESSENGER Neutron Spectrometer is composed of three separate sensors that span the neutron energy range between 0 and about 8 MeV. It has been operating continuously since about 1 February 2007. After the spacecraft's second Venus flyby on 5 June 2007, this detector will be sensitive to solar neutrons in the heliospheric distance range between 0.32 AU and 0.7 AU. The time period between the Venus flyby and orbit insertion in March 2011 spans the solar activity cycle between solar minimum and solar maximum. The first perihelion of MESSENGER's new orbit occurred on 1 September 2007. Counting rates of neutrons in the thermal and epithermal energy range (up to about 0.5 MeV) are sensibly zero. Observed rates for neutron energies between about 0.5 MeV and 8 MeV, signifying cosmic-ray interactions with spacecraft material, average about 1.9/s. As of the time of writing of this abstract, no solar flares have occurred and it is too early to place either actual rates for, or lower limits on, detection of background solar neutrons that result from the quiet-time heating of the corona. These rates will be reported at the meeting.
DE: 7509 Corona
DE: 7514 Energetic particles (2114)
DE: 7519 Flares
DE: 7554 X-rays, gamma rays, and neutrinos
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting