(LDEF) Archive System
NASA Langley Research Center
Hampton, Virginia
Linear Energy Transfer (LET) Spetra
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Responsible Parties:
Page Content: William H. Kinard Page Construction: Thomas H. See |
Given the altitude stability of LDEF, it is possible for the first time to comprehensively study the directional properties of LET spectra in spacecraft. These properties are a consequence of the directionality of the primary radiation and secondary particles produced by them and the geometry of the shielding around the detection point.
Improvement in the accuracy of LET prediction is significant for all future space programs. High LET particles can cause Single Event Upsets (SEUs) in microelectronics. The decreased device size and increased number of devices per chip in contemporary microcircuits, along with a growing awareness of the SEU susceptibility problem, necessitate the need for a better understanding and analysis of the LET spectra.
Not only are the microelectronics susceptible to damage from the LET spectra. Recoil particles, which dominate the high end of the LET spectra, have a large quality factor (QF), or effectiveness, in producing biological damage. An accurate prediction of the LET spectra is therefore important for assessing crew health risk.
The long exposure of LDEF has permitted a unique study of the short range recoil particles. These particles have very high LET values, exceeding that of
relativistic iron nuclei. These data will allow new modelling techniques to be applied that promise a more physically complete and more accurate prediction of LET spectra for future missions.
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