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Geiger Counters

NSSDCA ID: 1958-008A-01

Mission Name: Pioneer 3
Principal Investigator:Prof. James A. Van Allen


Two Geiger-Mueller tubes were used to obtain data on the belt of trapped radiation, discovered by Explorer 1, surrounding Earth. An Anton-type 302 tube had its output counted by a 17-stage binary scaler in order to cover the extreme dynamic ranges expected in counting rates within the bandwidth of the communications system. This counter would saturate at about 10 roentgen/hr. An Anton-type 213 tube which saturated at about 100 roentgen/hr was used to provide coverage in the high-intensity region of radiation. The counters were designed to count up to 200,000 radiation strikes per second, covering proton energies >30 MeV and electron energies > 2.2 MeV. The Geiger-Mueller tubes were mounted at the base of the nose cone within the thin fiberglass casing. Pioneer 4 used the same instrument with shielding added to the Anton 213 tube.

Continuous radiation data were received on the outbound leg of the trajectory to a radial distance from the center of the Earth of 107,400 km (nearly to apogee) and from 60,000 km to 9400 km on the inbound leg. Radiation data were received from launch until spacecraft failure on December 7, 1958 (38 hr, 6 min). The data from this experiment showed two distinct belts of radiation, later named the Van Allen belts in honor of the principal investigator.

Alternate Names

  • Pioneer3/GeigerCounters


  • Space Physics: Heliospheric Studies

Additional Information

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



NameRoleOriginal AffiliationE-mail
Prof. James A. Van AllenPrincipal InvestigatorUniversity of Iowa
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