Stellar 30-keV neutron capture in 94,96Zr and the 90Zr(gamma,n)89Zr photonuclear reaction with a high-power liquid-lithium target

Abstract

A high-power Liquid-Lithium Target (LiLiT) was used for the first time for neutron production via the thick-target 7 Li(p, n) 7 Be reaction and quantitative determination of neutron capture cross sections. Bombarded with a 1-2 mA proton beam at 1.92 MeV from the Soreq Applied Research Accelerator Facility (SARAF), the setup yields a 30-keV quasi-Maxwellian neutron spectrum with an intensity of 3-5 ×10 10 n/s, more than one order of magnitude larger than present near-threshold 7 Li(p, n) neutron sources. The setup was used here to determine the 30-keV Maxwellian averaged cross section (MACS) of 94 Zr and 96 Zr as 28.0 ± 0.6 mb and 12.4 ± 0.5 mb respectively, based on activation measurements.The precision of the cross section determinations results both from the high neutron yield and from detailed simulations of the entire experimental setup. We plan to extend our experimental studies to low-abundance and radioactive targets.In addition, we show here that the setup yields intense high-energy (17.6 and 14.6 MeV) prompt capture γ rays from the 7 Li(p, γ) 8 Be reaction with yields of ∼ 3×10 8 γ/s/mA and ∼ 4×10 8 γ/s/mA, respectively, evidenced by the 90 Zr(γ, n) 89 Zr photonuclear reaction.

A Micromegas-based gaseous detector for neutron-induced charged-particle reaction studies in nuclear astrophysics

“…The intensity of the 478-keV gammas was calculated using the 7 Li(𝑝, 𝑝 ′ 𝛾) cross sections from Presser and Bass [17], and Mateus et al [18]. The intensities of the 14.6 and 17.6 MeV 𝛾-rays are based on Tessler et al [19] and are scaled to amount to the higher beam energy. The simulation's statistics were equivalent to a 60-minute run at a beam intensity of 10 μA and proton energy of 3.6 MeV, which result in the worst background level.…”