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Alpha Particle Spectrometer

NSSDCA ID: 1972-031A-09

Mission Name: Apollo 16 Command and Service Module (CSM)
Principal Investigator:Dr. Paul Gorenstein


This experiment was designed to determine the lunar surface radon evolution using alpha particle measurement techniques and, in so doing, to assist the other geochemical experiments (gamma ray spectrometer, 72-031A-07, and X-ray fluorescence, 72-031A-08) in determining lunar surface composition and in identifying localized sources of enhanced radon emission that may correspond to regions of enhanced lunar outgassing. The experiment was intended to obtain data on the gross rate of the lunar surface radon evolution and on localized sources of enhanced radon emission for use in constructing a radiation map showing lunar surface inhomogeneities. Measurements of deep space background alpha particles were also made during lunar orbit and transearth coast concurrent with the X-ray fluorescence experiment. The spectrometer was composed of a 2 by 5 array of 10 silicon, surface barrier detectors housed in the same enclosure as the X-ray fluorescence experiment. Each of the 10 sensors looked toward the moon with a 90-deg full-angle field of view. Each sensor had its own preamplifier, the outputs of which fed into a common analog-to-digital converter which, in turn, sorted the pulses into 256 energy channels in the range 4.5 to 9.0 MeV. The instrumentation was designed to turn off the other nine detectors once an event was registered in one of the detectors until the event had been analyzed. Pulse height channel information for a bit rate limited value of up to 10 events per second was telemetered. The average alpha particle rate encountered was about 1 count/sec. The CM controlled the activation/deactivation of the experiment. All 10 detectors performed normally throughout the mission.

Alternate Names

  • Apollo16CSM/AlphaParticleSpectrometer
  • S162

Funding Agency

  • NASA-Office of Space Science (United States)


  • Planetary Science: Geology and Geophysics

Additional Information

Questions and comments about this experiment can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Dr. Paul GorensteinPrincipal InvestigatorHarvard College

Selected References

  • Burnett, D., et al., Solar cosmic ray, solar wind, solar flare, and neutron albedo measurements: Part C -- Cosmic ray experiment, in Apollo 16 Prelim. Sci. Rept., NASA SP-315, 15-19 thru 15-31, Wash., DC, 1972.
  • Gorenstein, P., and P. Bjorkholm, Alpha-particle spectrometer experiment, in Apollo 16 Prelim. Sci. Rept., NASA SP-315, 20-1 thru 20-6, Wash., DC, 1972.
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