RARE-GAS ISOTOPE YIELDS IN BREMSSTRAHLUNG-INDUCED NUCLEAR-REACTIONS OF K-41, RB-87, I-127, CS-133, AND LA-136

Radiochemical yield measurements are reported for K-41 (gamma, pi+)Ar- 41, Rb-87 (gamma, pi+)Kr-87, Cs-133 (gamma, pi+)Xe-133m, I-127 (gamma, pi- xn)Xe-127-x (x = 0, 2, 4, 5, and 6), Cs-133 (gamma, pxn)Xe-136-x (x = 1, 3, 5, 7, 9, 10, and 11), and La-139 (gamma, 3pxn)Xe-136-x (x = 7, 9, 11, 13, 14, and 15) at bremsstrahlung end-point energies (E0) o f 50-1200 MeV. For photopion reactions, both yields of (gamma, pi-) an d (gamma, pi+) reactions are independent of target mass (A(t)), and th e yield ratios of (gamma, pi-) to (gamma, pi+) reactions are about 5 o ver the studied ranges of E0 and A(t). The profile of I-127(gamma, pi- xm) yields as a function of x is similar to that of Cs-133 but quite d ifferent from that of V-51 when compared at the same E0, suggesting a strong A(t)-dependence. The photospallogenic Xe isotope yields from Cs -133 and La-139 are consistent with the reported mass yield patterns o f the other radionuclides produced from the same targets. These result s are discussed by referring to the previous literature values and to a cascade-evaporation calculation based on the PICA code by Gabriel an d Alsmiller.