Production of²³⁵Np,²³⁶Pu and²³⁷Puvianuclear reactions on^235,236,238U and²³⁷Np targets

Abstract

SummaryA summary of methods for cyclotron production of

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

“…The average thickness of the 236 U layer was 100 µg/cm 2 and the variations in the thickness were within 3%. Seven uranium targets were placed in the multiple target system described in [3] and irradiated with the K-130 cyclotron of University of Jyväskylä. The irradiations were carried out with 40 MeV protons at an intensity of 3 µA for 8 hours.…”

“…In a review work [3] it was concluded that the most efficient reactions to produce 235 Np are 236 U( p, 2n) 235 Np at proton energies lower than 18 MeV [4,5] and 238 U( p, 4n) 235 Np at energies from 18 to 50 MeV [6,7]. In reactions in the actinide region the competition between fission and neutron evaporation of the compound nucleus is decisive in the formation of the end product.…”

“…Both these effects lead to the decrease of ( p, 2n) cross section with proton energies approaching 20 MeV. An assumption has been made in [3], based on the extrapolations of the measured cross section curves, that the 236 U( p, 2n) 235 Np reaction could be the most productive also in the energy range higher than 18 MeV. In this case the 234 Np (T 1/2 = 4.4 ± 0.1 d [1]) will also be produced in the reaction 236 U( p, 3n) 234 Np.…”

“…The main impurity in the 236 Pu tracer produced with nuclear reactions of actinides with light particles is 238 Pu. In work [3] it was stated that the highest radionuclidic purity of 236 Pu can be obtained by the 236 U( p, nβ − ) 236 Pu reaction, where the impurity of 238 Pu produced in the 238 U( p, nβ − ) reaction depends only on the abundance of 238 U in the enriched 236 U target. The cross sections and yields of the 236 U( p, nβ − ) 236 Pu reaction have been determined in works [4,5] for proton energies lower than 18 MeV.…”

“…The present work is a completion of a series of experiments aiming at good understanding of production of short-lived neptunium and plutonium isotopes in nuclear reactions of 235,236,238 U and 237 Np targets with protons and 3 Heions [3]. It is devoted to the study of the 236 U( p, n) 236m Np, 236 U( p, 2n) 235 Np and 236 U( p, 3n) 234 Np reaction cross sections in proton energy range from 17 to 40 MeV.…”