PROTON AND HE-3 INDUCED NUCLEAR-REACTIONS IN URANIUM AND NEPTUNIUM TARGETS - PRODUCTION OF NEPTUNIUM AND PLUTONIUM TRACERS WITH A LOW-ENERGY CYCLOTRON

The production of Np-235, Pu-296 and Pu-237 by the reactions U-236(p,2 n)(NP)-N-235, Np-237(He-3,p2n)Pu-237 and Np-237(He-3,p3n)Pu-236 using a low-energy cyclotron (K = 20) was investigated. The cross sections f or the reactions were determined. Thick-target yield curves were deriv ed based on the cross sections. The results are discussed and compared with previous data on other reactions leading to the formation of the same end products. The thick-target yields of Np-235 from the U-236(p 2n) reaction and of Pu-237 from the Np-237(He-3,p2n) reaction are ten times higher than yields obtained with other reactions leading to thes e radionuclides at comparable particle energies. The reactions were th eoretically analyzed. The preequilibrium model predicts well the (p,2n ) results but underestimates by a factor of ten or more the (He-3,pxn) cross sections, probably due to the essential role of direct interact ions.