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Neutron measurements in near-Earth orbit with COMPTELThe fast neutron flux in near-Earth orbit has been measured with the COMPTEL instrument on the Compton Gamma Ray Observatory (CGRO). For this measurement one of COMPTEL's seven liquid scintillator modules was used as an uncollimated neutron detector with threshold of 12.8 MeV. The measurements cover a range of 4.8 to 15.5 GV in vertical cutoff rigidity and 3 deg to 177 deg in spacecraft geocenter zenith angle. One of the measurements occurred near the minimum of the deepest Forbush decrease ever observed by ground-level neutron monitors. After correction for solar modulation, the total flux is well fitted by separable functions in rigidity and zenith angle. With the spacecraft pointed near the nadir the flux is consistent with balloon measurements of the atmospheric neutron albedo. The flux varies by about a factor of 4 between the extremes of rigidity and a factor of 2 between the extremes of zenith angle. The effect of the spacecraft mass in shielding the detector from the atmospheric neutron albedo is much more important than its role as a source of additional secondary neutrons. The neutron spectral hardness varies little with rigidity or zenith angle and lies in the range spanned by earlier atmospheric neutron albedo measurements.
Document ID
19950063965
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Morris, D. J.
(Max-Planck-Institut fuer extraterrestrische Physik Garching, Germany)
Aarts, H.
(SRON-Utrecht Utrecht, Netherlands)
Bennett, K.
(European Space Research and Technology Centre Noordwijk, Netherlands)
Lockwood, J. A.
(University of New Hampshire, Durham, NH United States)
Mcconnell, M. L.
(University of New Hampshire, Durham, NH United States)
Ryan, J. M.
(University of New Hampshire, Durham, NH United States)
Schoenfelder, V.
(Max-Planck-Institut fuer extraterrestrische Physik Garching, Germany)
Steinle, H.
(Max-Planck-Institut fuer extraterrestrische Physik Garching, Germany)
Peng, X.
(University of New Hampshire, Durham, NH United States)
Date Acquired
August 17, 2013
Publication Date
July 1, 1995
Publication Information
Publication: Journal of Geophysical Research
Volume: 100
Issue: A7
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
95A95564
Funding Number(s)
CONTRACT_GRANT: NAS5-26645
Distribution Limits
Public
Copyright
Other

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