Production of Np isotopes from ²³⁸U beam at BigRIPS

A variety of rare isotope beams with atomic numbers (Z) up to 92 can be produced by the projectile fragmentation and in-flight fission from high intensity U beams at RIBF. In numerous instances of spallation reactions, transitions to channels leading to Z+1 have been observed, and their energy dependence can be perceived qualitatively. In the Pd region, a comprehensive investigation was conducted by Wang et al. It was also found that ^234−238Np can be generated by a proton pickup reaction at 1 GeV/u ²³⁸U beam by E.Casarejos et al. Owing to the developments of the high-Z beams at BigRIPS, energy dependence of the proton pickup reaction on ²³⁸U can be obtained at RIBF. Thus, we conducted an experiment to determine the energy dependence of the production cross section of ²³⁷Np.

Secondary beams around Z = 90 were produced by an ²³⁸U primary beam with energies of 345 and 250 MeV/u. To validate the production of the ²³⁷Np⁹¹⁺, a two dimensional (2D) Gaussian fitting approach was conducted in accordance with the distribution patterns of neighboring ions of ²³⁴U⁹⁰⁺,²³⁵U⁹⁰⁺, and ²³²Pa⁸⁹⁺. It is found that Np isotope can be counted with contaminated U/Pa isotopes. The production cross sections of ^234-236U and ^232-233Pa as well as Np isotopes were derived.

We will report the results of 345MeV/u.