Production of ^234,235Np and ²³⁶Pu in bombardment of ²³⁶U with protons in the energy range from 17 to 40 MeV

Abstract

Proton induced nuclear reaction / 236 U target / 234,235 Np and 236 Pu / Excitation function / Thick-target yield Summary. The production of 235 Np and 236 Pu by the reactions 236 U( p, 2n) 235 Np and 236 U( p, nβ − ) 236 Pu using the K-130 cyclotron of the University of Jyväskylä was investigated. The cross sections for the reactions were determined. Thicktarget yield curves were derived 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 yield of 235 Np in the 236 U( p, 2n) reaction is about 50 percent higher than the yield obtained in the 238 U( p, 4n) reaction leading to this nuclide at comparable particle energies. The purity of 236 Pu produced in the 236 U( p, nβ − ) reaction is more than ten times better than for earlier known as the purest reaction 237 Np( p, 2n + pnβ − ) 236 Pu.

Formation of heavy neutron-deficient nuclides in 3He-induced reactions

“…U targets 1 mg cm -2 thick were irradiated using 3 He ions with energies of 20.4-42.0 MeV at the Acceler ator Laboratory of University of Jyväskylä, Finland. The irradiated targets were analyzed with gamma and alpha spectrometers and then dissolved in order to chemically separate Pu and Np from the fission products and the target material.…”

“…At present, there is little information on the inter action between 3 He and actinide nuclei. There have been few near barrier measurements of the probability of fission in direct reactions of 3 He with actinide nuclei [1].…”

“…The special structure of the nuclide 3 He can pro duce interesting features in the excitation functions of various reaction channels. From a practical point of view, reactions induced by 3 He can play an important part in the production of heavy neutron deficient nuclides that are used in environmental studies.…”

“…Ways of obtaining various short lived Np and Pu isotopes were studied systematically in [2][3][4]. These works focused on the isotopes 235 Np (T 1/2 = 396.1 days), 236 Pu (T 1/2 = 2.858 years), and 237 Pu (T 1/2 = 45.2 days)-convenient tracers for, e.g, study ing the spread and biological pathways of neptunium and plutonium isotopes ejected into the environment in nuclear accidents.…”

“…This work presents the results from experimental and theoretical studies on the formation cross sections of evaporation residues in the reaction 235 U + 3 He at incident nucleus energies in the range of 20-42 MeV. The investigated reaction channels are listed in Table 1.…”