2023年度核データ+PHITS合同研究会/Joint Symposium on Nuclear Data and PHITS in 2023

A variety of unstable nuclear 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. Recently, it was found that ${}^{234-238}$Np can be created by a proton pickup reaction on 1 GeV/nucleon ${}^{238}$U beam. Owing to the recent developments of the high-Z beams at BigRIPS, energy dependence of the proton pickup reaction on ${}^{238}$U can be obtained at RIBF. Thus, we conducted an experiment to determine the energy dependence of the production cross section of ${}^{237}$Np. A test of the production of Np isotopes was performed by using the BigRIPS spectrometer at RIBF in March 2022.
Secondary beams around Z = 90 were produced by a ${}^{238}$U beam with energies of 345 and 250 MeV/nucleon impinging on a 1-mm-thick ${}^9$Be production target at F0 in BigRIPS.
The particle identification (PID) of the secondary beam was performed using the TOF-Bρ-ΔE method.
To validate the production of the ${}^{237}$Np${}^{91+}$, a two dimensional (2D) Gaussian fitting approach was conducted in accordance with the distribution patterns of neighboring ions of ${}^{234}$U${}^{90+}$, ${}^{235}$U${}^{90+}$, and ${}^{232}$Pa${}^{89+}$. It is found that Np isotope can be counted up with contaminated U/Pa isotopes using the 2D Gaussian fitting technique. The production cross sections of ${}^{234}$U, ${}^{235}$U, ${}^{236}$U, ${}^{232}$Pa, and $^{233}Pa as well as Np isotopes were derived.
In this presentation, we will report the analysis status of 345 MeV/nucleon.