NUCLEAR REACTIONS INDUCED IN TANTALUM BY PROTONS OF ENERGY UP TO 84 MEV

Nuclear reactions induced in tantalum by protons of energy up to 84 Mev have been studied and excitation functions obtained for products formed by (p,xn), (p,pxn), (p,2pxn), and (p,3pxn) reactions. Radiation characteristics of the products were redetermined. Previously unreported γ-rays with energies 90 to 1050 kev have been found for W176, and 113 kev for W177. A new half-life of 2.7 ± 0.1 hr for W176 is reported. The cross sections for the (p,xn) reactions were compared with the values predicted by Jackson's schematic model and found to be in reasonable agreement. More complex reactions are discussed in the light of current nuclear theories.

THE SPALLATION OF IRIDIUM WITH PROTONS OF ENERGIES 9–87 MEV

Iridium metal has been bombarded with protons varying in energy from 8 to 87 Mev. The spallation products were radiochemically separated and decay characteristics and formation cross sections were determined. It was confirmed that both Pt187 and Pt186 have half-lives of about 3 hr, and a half-life of 13.3 ± 0.2 days was found for Ir189. An isomeric state of Ir186 with half-life 2.0 ± 0.5 hr has been found. Fair agreement was obtained between excitation functions for (p,xn) reactions determined experimentally and those predicted by the Jackson model. The (p,pn) yield at 84 Mev has been compared with that calculated from Monte Carlo cascade data combined with evaporation theory and found to be too high by a factor of 4.