Experimental 7Be production cross section from the Li7(p,n)7Be reaction at Ep = 3.5 − 13 MeV

Abstract

The ${}^7\mathrm{Li}(p,n){}^7\mathrm{Be}$ reaction is widely used as neutron source for neutron induced reaction cross section measurements, and for ⁷Be radioactive source production. There are two prominent structures in the excitation function, a narrow resonance between $E_p=2.2-2.3$ MeV, and a broad peak, around $E_p=5$ MeV. There are tension between the experimental data sets both in the position and the width of this latter structure, as well as in the absolute scale of the data. In the present work the ${}^7\mathrm{Li}(p,n){}^7\mathrm{Be}$ reaction is investigated using the activation technique, with the aim of providing comprehensive cross section data covering the second structure and connecting prior literature data sets. The irradiations were performed with the Atomki cyclotron accelerator with pairs of thin foil targets, thus with precisely controlled reaction energy in the range of $E_p=3.5-13$ MeV. After the irradiations the activity of the samples was measured using a high-purity germanium detector. The energy uncertainty of the new data points is much smaller than in any of the previous works, while the cross section uncertainty is comparable with the most precise literature data. A consistent data set was obtained connecting the most recent and most precise literature data sets. With the new data the absolute magnitude of the ${}^7\mathrm{Li}(p,n){}^7\mathrm{Be}$ reaction cross section is constrained and became more precise.