Correlation of dose rate and spectral measurements in the Inner Van Allen Belt.
Dose rate measurements and the charged particle environment of the Inner Van Allen Belt have been correlated using recent data obtained from the radiation research satellite, OV3-4. Six tissue equivalent ionization chambers, constructed of a material which simulates the muscle tissue response to ionizing radiation, measured the dose rate behind various types and thicknesses of material. The specific shields used for several of the chambers were 0.192 g/cm2 aluminum, 0.797 g/cm2 Lucite and 4.485 g/cm2 brass. The proton and electron spectra were determined with an omnidirectional spectrometer using solid state detectors. The spectral measurements discussed here include geomagnetically trapped protons with energies in the range of 15 to 200 MeV. The proton spectra and dose rates are presented as profiles in terms of the McIlwain parameters of L (1.5, 2.0 and 2.5 earth radii) and the magnetic field B (0.050 to 0.250 gauss). The excellent agreement between the measured dose rate and the theoretically predicted dose rate based on the measured spectra provides justification for the radiation transport techniques now being employed to predict the doses to be encountered during future manned space missions. It was found, however, that a more adequate description of the proton fluxes for energies greater than 50 MeV will be necessary to predict dose rate accurately behind shields of 2.5 g/cm2 thickness or greater.
Biophysics Branch, Air Force Weapons Laboratory, Kirtland AFB, New Mexico, USA.
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D003359:Cosmic Radiation; D005118:Extraterrestrial Environment; D008953:Models, Anatomic; D008962:Models, Theoretical; D009132:Muscles / Q000528:radiation effects; D011522:Protons; D011829:Radiation Dosage; D011834:Radiation Monitoring; D011835:Radiation Protection; D019445:Solar Activity; D013026:Space Flight / Q000295:instrumentation*; D018531:Spacecraft / Q000295:instrumentation
D011522:Protons