Speaker
Description
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.
