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Positron Search and Gamma Ray Spectrum

NSSDCA ID: 1964-054A-15

Mission Name: OGO 1
Principal Investigator:Dr. Thomas L. Cline


This experiment was designed to determine whether low-energy (0 to 3 MeV) positrons are trapped temporarily or permanently in the Van Allen radiation region and whether low-energy solar and interplanetary positrons exist at the edge of the earth's magnetic field. It was also designed to detect gamma-ray bursts from the sun in the energy interval from 80 keV to 1 MeV. The experimental apparatus consisted of three cesium iodide (CsI) crystals surrounded by a plastic anticoincidence shield, with the output of the whole unit being monitored by three photomultipliers. It was primarily designed to search for interplanetary positrons by measuring the spectra of single or paired X rays produced by the stopping of a positron. In another possible mode of data acquisition, single X rays were monitored in one of the CsI spectrometers with 4-pi particle anticoincidence, which was virtually X-ray transparent above 80 keV. Once every 18.5 seconds, integral intensity measurements were made in each of the 16 energy levels equally spaced between 80 keV and 1 MeV, allowing for both temporal and spectral analysis of the data. Inflight calibration of the spectrometer was accomplished by monitoring the 511-keV annihilation line. The experiment did not achieve the desired objectives, but did obtain useful data. The basic difficulties were electrical interference and secular degradation of the photomultipliers' response. No important papers were produced using the data. More details regarding experiment design may be found in Cline, T. L., et al., "A double gamma-ray spectrometer to search for positrons in space," Inst. of Radio Engr., IRE Trans. on Nucl. Sci., v. NS-9, n. 3, pp. 370-375, June 1962. No data sets now exist from this investigation.

Alternate Names

  • OGO1/PositronSearchandGammaRaySpectrum


  • Astronomy: Gamma Ray

Additional Information

Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Dr. Edward W. Hones, Jr.Other InvestigatorLos Alamos National
Dr. Thomas L. ClinePrincipal InvestigatorNASA Goddard Space Flight
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