title: Neutron measurements onboard the space shuttle.
abstract: The radiation environment inside a shielded volume is highly complex, consisting of both charged and neutral particles. Since the inception of human space flights, the charged particle component has received virtually all of the attention. There is however, a significant production of secondary neutrons, particularly from the aluminum structure in low earth orbiting spacecrafts. The interactions of galactic cosmic rays (GCR), and solar energetic particles with the earth's atmosphere produce a non-isotropic distribution of albedo neutrons. Inside any reasonable habitable module, the average radiation quality factor of neutrons is about 4-5 times larger than the corresponding average quality factor of charged particles. The measurement of neutrons and their energy spectra is a difficult problem due the intense sources of charged particles. This paper reviews the results of Shuttle flight experiments (made during both solar maximum and solar minimum) to measure the contribution of neutrons to the dose equivalent, as well as theoretical calculations to estimate the appropriate range of neutron energies that contribute most to the dose equivalent.
authors.affiliation: NASA Lyndon B. Johnson Space Center, SN 2101 NASA Road 1, Houston, TX 77058-3696, USA. gautam.d.badhwar@jsc.nasa.gov
authors.forename: G D
authors.initials: GD
authors.lastname: Badhwar
authors.forename: J E
authors.initials: JE
authors.lastname: Keith
authors.forename: T F
authors.initials: TF
authors.lastname: Cleghorn
mesh_terms: D003359:Cosmic Radiation; D005118:Extraterrestrial Environment; D006801:Humans; D008962:Models, Theoretical; D009502:Neutrons; D011829:Radiation Dosage; D011834:Radiation Monitoring / Q000295:instrumentation*; D011835:Radiation Protection; D011874:Radiometry; D019445:Solar Activity; D013026:Space Flight / Q000295:instrumentation*; D018531:Spacecraft / Q000295:instrumentation; D013819:Thermoluminescent Dosimetry