Scientists of the Veksler and Baldin Laboratory of High Energy Physics at JINR and the Alikhanyan National Science Laboratory (Armenia) measured cross sections of proton-induced neutron emission reactions on thorium and uranium at energies below 18 MeV.

Experimental data on proton-induced neutron emission reactions in actinides are important for nuclear astrophysics, nuclear energy, and medical applications.

The Ep dependence of the 232Th(p,n)232Pa and 238U(p,n)238Np reactions cross section

Current data on (𝑝,𝑥𝑛) reactions in thorium and uranium at low energies range (Ep < 20 MeV) are somеwhat scarce and often contradict each other. In this work, the cross sections of proton-induced ²³²Th(𝑝,𝑛)²³²Pa, ²³²Th(𝑝,3𝑛)²³⁰Pa, ²³⁸U(𝑝,𝑛)²³⁸Np, ²³⁸U (𝑝,3𝑛) ²³⁶m Np, and ²³⁸U(𝑝,𝑛𝑝)²³⁷U reactions are measured at the proton energy range 12–17 MeV using the stacked-foil technique and the induced activation method. γ-ray spectroscopy is used to identify the resulting radionuclides and to determine their yields. In total, there are 21 cross sections determined in this work for the listed reactions. This new data set can help to clear up the discrepancies between existing data sets from different experiments and to fill in the gap of missing low-energy data.

The cross-section data are compared to the predictions of the TALYS1.96 nuclear reactions simulation code, using different combinations of options of several main ingredients of the code, such as the photon strength function, the optical model potential, the fission barrier, the nuclear level density, and the pre-equilibrium mechanism.

The experiment was carried out at Alikhanyan National Science Laboratory using the proton beam of the C-18 Cyclotron. The paper on the results of the research was published in Physical Review C in June 2024. Among the authors is a leading researcher at the Laboratory of High Energy Physics at JINR Armen Kechechyan.