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

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.