SHIELDINGEFFECTSIN SPACEBORNE,NaIGAMMA-RAYSPECTROMETERS

Radioactivity inducedin detectorsby cosmic raysand trappedprotonslimitsthe sensitivityof spacebornegamma-rayspectrometers.In thispaper 1-D transportcalculations are used to analysethe influenceof neutronshieldingon the radioactive backgroundinducedin NaI by neutroncapturereactions. It is foundthattheuse of thermalisingabsorbersto surroundcentraldetectorelementsis in factcounterproductive.Full 3-D transportcodeshavebeen applied to thetrappedprotoncaseand verifyboth the absolute levelsof thiscomponentand the negativeinfluenceof neutronshielding.