Comparison of CREME (Cosmic Ray Effects on Microelectronics) Model LET (Linear Energy Transfer) Spaceflight Dosimetry Data,

The galactic cosmic radiation GCR component of space radiation is the dominant cause of single event phenomena in microelectronic circuits when Earths magnetic shielding is low. Spaceflights outside the magnetosphere and in high inclination orbits are examples of such circumstances. In high inclination orbits, low energy high LET particles are transmitted through the field only at extreme latitudes, but can dominate the orbit-averaged dose. GCR is an important part of the radiation dose to astronauts under the same conditions. As a test of the CREME environmental model and particle transport codes used to estimate single event upsets, we have compiled existing measurements of HZE doses where GCR is expected to be important Apollo 16 and 17, Skylab, Apollo Soyuz Test Project, and Kosmos 782. The LET spectra, due to direct ionization from GCR, for each of these missions has been estimated. The resulting comparisons with data validate the CREME model predictions of high LET galactic cosmic ray fluxes to within a factor of two. Some systematic differences between the model and data are identified.