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Cosmic-Ray Anisotropy

NSSDCA ID: 1968-100A-05

Mission Name: Pioneer 9
Principal Investigator:Dr. Kenneth G. McCracken


This experiment consisted of a CsI scintillator and three solid-state telescopes. The CsI scintillator was collimated by an anticoincidence plastic scintillator and had a conical aperture with a 38.2-deg half-angle. The scintillator look direction was centered in the ecliptic plane. Three solid-state detectors were oriented in a fan arrangement with respect to a fourth solid-state detector, such that each of the first three detectors formed a telescope with the fourth detector. Each of the three telescopes thus formed had an acceptance cone of 23-deg half-angle. The mean viewing directions of the telescopes were in the ecliptic plane and 48 deg above and below that plane, respectively. Two concurrent modes of counting were employed. In the first mode, counts were accumulated in eight separate 45-deg intervals during the spacecraft spin, while, in the second, spin-integrated counts were acquired. In the first mode, the scintillator separately measured particles with energies in the ranges 7.4 to 21.5 MeV/nucleon and 19.7 to 63.0 MeV/nucleon (no species discrimination) while each solid-state telescope separately measured protons in the energy ranges 3.3 to 3.6 MeV and 3.6 to 6.7 MeV. In the second mode, the scintillator separately measured particles in six contiguous energy intervals between 4.5 and 40 MeV/nucleon (interval lower limits at 4.5, 7.0, 9.6, 13, 21, and 28 MeV/nucleon), while each of the solid-state telescopes separately measured protons in the energy ranges 1 to 8, 1 to 5, 1 to 3, and 4 to 6 MeV, and alpha particles in the energy range 4 to 8 MeV. During each 224-bit main telemetry frame, two first-mode 9-bit accumulators and one second-mode 9-bit accumulator were read out. Inflight calibration of the scintillator and of some of the electronics was performed daily. See Bukata et al, IEEE Trans. Nuc. Sci., NS-17, pp. 18-24, 1970, for a more detailed experiment description.

Alternate Names

  • Pioneer9/Cosmic-RayAnisotropy


  • Astronomy: Cosmic Ray
  • Space Physics: Heliospheric Studies

Additional Information

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NameRoleOriginal AffiliationE-mail
Dr. William C. BartleyOther InvestigatorDepartment of Energy Headquarters
Prof. Udipi Ramachandra RaoOther InvestigatorISRO Satellite
Dr. Kenneth G. McCrackenPrincipal InvestigatorCommonwealth Scientific and Industrial Research Orqanisation
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