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Neutron dosimetry in low-earth orbit using passive detectors.
E R Benton1, E V Benton, A L Frank
1Eril Research, Inc., P.O. Box 150788, San Rafael, CA 94915-0788, USA.
Radiation Measurements
|February 21, 2002
Summary
Neutron dosimetry in space was measured using passive detectors over 20 years. High-energy neutrons (>1 MeV) contributed the most to dose equivalent, with measurements varying by mission altitude and inclination.
Area of Science:
- Space physics
- Radiation detection
- Dosimetry
Background:
- Spacecraft missions involve significant radiation exposure.
- Accurate neutron dosimetry is crucial for astronaut safety and mission planning.
Purpose of the Study:
- To summarize 20 years of neutron dosimetry measurements on US and Russian LEO spacecraft.
- To reanalyze neutron data in terms of ambient dose equivalent.
- To compare measured neutron dose contributions with model estimates.
Main Methods:
- Utilized passive detectors: thermal/resonance neutron detectors (for <1 MeV neutrons) and fission foil detectors (for >1 MeV neutrons).
- Measurements were conducted aboard US and Russian Low Earth Orbit (LEO) spacecraft over two decades.
- Data were reanalyzed using ambient dose equivalent, updating from NCRP-38 quality factor definitions.
Main Results:
- Dose equivalent rates for neutrons <1 MeV varied from 0.80 to 22.0 microSv/d.
- Dose equivalent rates for neutrons >1 MeV ranged from 4.5 to 172 microSv/d (on LDEF mission).
- Neutrons >1 MeV accounted for over 98% of the total neutron dose equivalent on the LDEF mission.
Conclusions:
- Neutrons, particularly those with energies >1 MeV, are the primary contributors to neutron dose equivalent in space.
- Measured neutron dose contributions were generally lower than model estimates.
- Passive dosimetry provides valuable data for understanding space radiation environments.