Concept information
Preferred term
GFE-3R DOSIMETER
Definition
- [Source: National Space Science Data Center, http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=1976-091A-03 ] The purpose of the GFE-3R dosimeter was to measure the radiation dose in silicon under aluminum shielding of four thicknesses representative of Block 5D DMSP spacecraft. The dosimeter, built by the Aerospace Corporation Space Science Laboratory, consisted of four separate, single-detector units. These omnidirectional sensors were small, cubical, lithium-drifted, silicon detectors centered under hemispherical shells, and heavily shielded (relative to the hemispherical shell) over the rear 2 pi solid angle. The shielding domes for the four sensors were 35, 75, 125, and 200 mils of aluminum, respectively. The dosimeter directly measured the ionization in the silicon cube caused by the natural radiation and served as an electron-proton spectrometer, thus yielding the fluences of energetic electrons and protons encountered in the DMSP orbit, as a function of time. Four integral discriminators, with thresholds corresponding to deposited energy of 25, 75, 300, and 5000 keV, were used to analyze the pulse-height spectrum of signals produced by protons, electrons, and gamma rays entering the detector. Individual pulses from the 25, 300, and 5000 keV channels were counted in scaling registers, which are read out and reset by the telemetry system every three s. Pulses, whose amplitudes exceed the gating thresholds of 25 keV and 75 keV, were integrated into 1 MeV equivalent energy pulses (corresponding to a dose of 8.0E-6 rad), which were counted by a cumulative storage register. These registers were read out every three seconds but not reset by the telemetry so that the number of counts read out at any time represented the total energy in MeV deposited in the silicon acitve volume during the mission life. Maximum accumulated dose storage corresponded to 5.5E5 rads. Additional information can be obtained from Aerospace Corporation publication number TOR-0077(1630)-1, June 1977. Group: Instrument_Details Entry_ID: GFE-3R DOSIMETER Group: Instrument_Identification Instrument_Category: Earth Remote Sensing Instruments Instrument_Class: Passive Remote Sensing Instrument_Type: Thermal/Radiation Detectors Short_Name: GFE-3R DOSIMETER Long_Name: Radiation Dosimeter (SSJ*) End_Group Group: Associated_Platforms Short_Name: DMSP 5D-1/F1 End_Group Online_Resource: http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=1976-091A-03 Creation_Date: 2008-09-25 Group: Instrument_Logistics Instrument_Owner: Department of Defense-Department of the Air Force (United States) End_Group End_Group (en)
Broader concept
URI
https://gcmd.earthdata.nasa.gov/kms/concept/55c84391-ef1c-4318-9a8f-c2072e5a864a
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