Mewaldt, R. A. and Stone, E. C. and Vogt, R. E.
(1975)
The Quiet Time Flux of 0.16-1.6 MeV Cosmic Ray Positrons.
In:
Proceedings of the 14th International Cosmic Rays Conference.
Vol.1.
Max Planck Gesellschaft
, p. 401.
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Abstract
Measurements of the cosmic ray positron
flux near ~ 1 MeV are of interest because
of possible contributions in this energy
region from β-decay sources. Previously
we reported (Hurford et al.,1973) an
upper limit for the quiet time positron flux
at ~1 MeV of ~2x10^(-3) cm^(-2)•sec^(-1)•sr^(-1)•Mev^(-1),
based on a preliminary analysis of data from
the Caltech Electron/Isotope Spectrometer
on IMP-7. The method of positron detection
is discussed in Mewaldt et. al. (1975). Our
IMP-8 instrument has somewhat improved positron
detection efficiency and includes an
analysis mode that allows a determination
of the rate of background events with positron-
like signatures. Subtraction of this
background contribution and the accumulation
of additional data with improved statistical
accuracy from both instruments shows that
less than 30% of the positron-like events
are due to positrons. This results in the
new upper limits to the 0.16 to 1.6 MeV
positron flux shown in Figure 1. These new
upper limits are a factor of ~ 2 lower than
those we reported previously. Thus we find
no evidence for ~ 1 MeV positrons which might
result from the β-decay of radioactive interstellar
secondaries or the decay of ^(56)Co in
supernovae.
Item Type: | Book Section |
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Additional Information: | © 1975 MPE.
Provided by the NASA Astrophysics Data System.
This work was supported in part by the National Aeronautics
and Space Administration under Contract NAS5-11066 and Grant NGR 05-002-160. |
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Group: | Space Radiation Laboratory |
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Funders: | Funding Agency | Grant Number |
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NASA | NAS5-11066 | NASA | NGR 05-002-160 |
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Space Radiation Laboratory | 1975-08 |
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Record Number: | CaltechAUTHORS:20140410-133715368 |
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Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20140410-133715368 |
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Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. |
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ID Code: | 44864 |
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Collection: | CaltechAUTHORS |
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Deposited On: | 10 Apr 2014 21:56 |
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Last Modified: | 20 Feb 2020 14:33 |
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