Thickness analysis of LiF thin films by using 7Li(p,n) and 19F(p,αγ) nuclear reactions

A neutron time of flight (n-TOF) technique is applied for analyzing the thickness of a LiF thin film used as a neutron target. Measuring the flight time of the neutron generated from the neutron target gives information on the proton attenuation energy corresponding to the film’s thickness. Three thin-film targets were fabricated at an applied electron voltage of 4.3 kV and an electron current of about 20 mA by using an evaporating system with an electron gun. Two methods, weight on a micro-balance and the excitation function for the narrow resonance band of 483.8 keV on the 19 F(p, αγ ) reaction, were used to confirm the target thickness. The thicknesses of the three targets were found to be 95.5, 109.7, and 206.8 µg/cm 2 by treating statistically the results of the three methods. The results for the three methods agreed within 7%.