Shielding for space microelectronics needs to provide an acceptable dose rate with minimum shield mass. The analysis presented here shows that the best approach is, in general, to use a graded-Z shield, with a high-Z layer sandwiched between two low-Z materials. A graded-Z shield is shown to reduce the electron dose rate by more than sixty percent over a single-material shield of the same areal density. For protons, the optimal shield would consist of a single, low-Z material owever, it is shown that a graded-Z shield is nearly as effective as a single-material shield, as long as a low-Z layer is located adjacent to the microelectronics. A specific shield design depends upon the details of the radiation environment, system model, design margins/levels, compatibility of shield materials, etc. Therefore, we present here general principles for designing effective shields and describe how the computer codes are used for this application.
The SPR 111 bare cavity spectrum and integral parameters have been determined with 24 measured spectrum sensor responses and an independent, detailed, transport calculation. This environment qualifies as a benchmark field for electronic parts testing.
The conventional discrete ordinates approximation to the Boltzmann transport equation can be described in a matrix form. Specifically, the w i t h i n-g r o u p s c a t t e r i n g i n t e g r a l c a n b e r e p r e s e n t e d b y three components: a moment-to-discrete matrix, a scattering cross-section matrix and a discrete-to-moment matrix. Using and extending these entities, we derive and summarize the matrix representations of the second-order transport equations.
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