Measurements of the secondary particle energy spectra in the space shuttle

Description of Transport Codes for Space Radiation Shielding

“…Energy spectra for light particles measured with particle hodoscopes are also in good agreement with the HZETRN/QMSFRG code (Badhwar et al 1995). Measurements of heavy ion spectra require large area detectors, and very few have been made in human-rated vehicles because of the mass requirements.…”

“…Complex geometries are typically handled with simplifications in the representation by combining parts and material composition, thus negating any advantages compared to one-dimensional transport methods that could be found by treatment of detailed threedimensional effects. Boltzmann equation solvers such as the HZETRN code (Wilson et al 1995) are able to use raytracing techniques to consider a very detailed geometry in a one-dimensional approach that is adequate for fast ions, especially for the omnidirectional radiation sources in space. The relative contribution from low energy charged ions that deviate from the straight-ahead approximation can be solved by quadratures leaving only the angular deflections of neutrons and intermediate energy light ions with sufficient energy to produce nuclear reactions to be addressed when considering deviation from one-dimensional transport.…”

3DHZETRN: Shielded ICRU spherical phantom

“…It is clear that the straight-ahead approximation provides accurate dosimetric results and a good approximation to the particle fluence in many circumstances (Badhwar et al, 1995;Badhwar, 1997). One limitation of the straight-ahead approximation is near the front boundary where the calculated neutron fluence vanishes (unless neutrons are part of the external radiation environment such as the neutron albedo .…”

Assessment and requirements of nuclear reaction databases for GCR transport in the atmosphere and structures

“…Recent spaceflight measurements of light ion charged particle spectrum by Badhwar et al (1994) highlight the effects of secondary nuclear reactions where fluxes of n, d, t, h, and _ ions below 100 MeV/u showed a combined flux close to the primary and secondary proton flux. In low earth orbit, the geomagnetic effects prevent primaries from this energy regime and the fluxes seen are attributed solely to secondary fragments produced in the shielding.…”