Yield measurements for 7Be and 10Be productions from natCu, natAg and 197Au by bremsstrahlung irradiation at E0=200 MeV

The yields of Be-7 and Be-10 produced by bremsstrahlung having a maximum energy (E-0) of 200 MeV in Cu-nat, Ag-nat and Au-197 targets were investigated by the AMS technique at MALT of the University of Tokyo. It was found that the yields at E-0 = 200 MeV were much lower than those at E-0 greater than or equal to 250 MeV, obtained in our previous works. A change in the yields of the fragmentation component in the target-mass dependence was observed at E-0 = 200 MeV when compared with those at E-0 greater than or equal to 250 MeV. However, the ratios of the fragmentation yield of Be-10 to that of Be-7 remained unchanged throughout the concerned E-0. (C) 2004 Elsevier B.V. All rights reserved.