First nuclear-astrophysics experiments with high-intensity neutrons from the liquid-lithium target LiLiT

Abstract

A high-intensity neutron source based on a Liquid-Lithium Target (LiLiT) and the 7Li(p,n) reaction was developed at SARAF (Soreq Applied Research Accelerator Facility, Israel). The setup is used for nuclear-astrophysics experiments owing to the quasi-Maxwellian shape of the neutron energy distribution at stellar thermal energies (kT ∼ 30 keV). The LiLiT device consists of a forced-flown (> 2 m/s) film of liquid lithium (∼200 °C) whose free surface is bombarded by a proton beam. The lithium film acts both as the neutron-producing target and as a power beam dump. The setup was commissioned with a 1.2 mA proton beam at 1.91 MeV, producing a neutron yield (peaked at ∼28 keV) of ∼ 3 ×1010 n/s, more than one order of magnitude larger than conventional 7Li(p,n)-based neutron sources. The target dissipates a peak power areal density of 2.5 kW/cm2 and a peak power volume density of 500 kW/cm3 with no significant temperature or vacuum pressure elevation in the target chamber. We present preliminary results of first activation measurements on Zr and Ce stable isotopes performed with the SARAF-LiLiT setup, using Au as neutron monitor and of the determination of their Maxwellian-averaged neutron capture cross section.