Design and commissioning of the miniBELEN neutron counter for the study of $(\alpha,n)$ reactions

Abstract

The miniBELEN detector is a moderated neutron counter based on the use of $^3$He tubes and high-density polyethylene as moderator. The detector has been designed to have a neutron detection efficiency that is nearly independent from the initial neutron energy for ($\alpha$,n) reactions with alpha-particle energies up to 15 MeV. In order to achieve that, an innovative design methodology based on the use of cadmium neutron filters has been used. Monte Carlo calculations of the detector response have been validated using a $^{252}$Cf fission source. Measurements of the relatively well-known ($\alpha$,n) thick-target yields on aluminum have been found to be consistent with data from previous works. A method has been developed to correlate the counting rate ring ratios with the mean neutron energy and validated using previous time-of-flight measurements of the aluminum ($\alpha$,n) spectra and with a $^{252}$Cf fission source. Submitted to The European Physical Journal - Plus