Activation of aluminum beam dumps by high-energy electrons at SLAG.

Water-cooled Al beam dumps are used at SLAC to absorb the energy of high-intensity electron beams through development of a massive electromagnetic cascade. The aluminum becomes activated and constitutes a moderate radiation hazard. Decay-curve measurements made near two such dump installations are presented and compared with calculation. The most important radionuclides produced in the Al are identified as 24 Na(Ti = 14.96 h) and 22 Na(Ti = 2.62 yr). It is found that other activated materials, particularly Fe shielding, can increase the exposure rates near such installations significantly, and must be considered. A formula is given which is useful for predicting dose rates for operational health-physics use, Recommendations are made with a view to reducing doses to personnel who must work in the vicinity of such installations. (Submitted to Health Physics) * Work supported by the TJ. S. Atomic Energy Commission. Paper presented at the 18th Annual Meeting of the Health Physics Society, Miami Beach, June 17-21, 1973.