Abstract for CEBAF Technical Note 91-024  

The effect of line of sight shielding (LOSS) on pion, proton, and neutron induced background is considered for Hall A. FLUKA calculations show that about 75CM LOSS will reduced energetic charged particle fluxes to the level of 7 KHz - 10 KHz in a 1m2 region placed in the detector package for a Hall A spectrometer. Further increasing the line of sight shielding does not lower the charged particle rate because the rate is then dominated by particles which strike the hut and miss the LOSS. Placing additional shielding of about 40cm thickness on both sides of the LOSS to shield the hut walls can bring the charged particle rate in the sensitive region of the detector package to about 1 KHz - 2 KHz per 1m2.

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