A telescope detection system for direct and high resolution spectrometry of intense neutron fields

摘要

A high energy- and spatial-resolution telescope detector was designed and constructed for neutronudspectrometry of intense neutron fields. The detector is constituted by a plastic scintillator coupled to audmonolithic silicon telescope (MST), in turn consisting of a DE and an E stage. The scintillator behaves asudan “active” recoil-proton converter, since it measures the deposited energy of the recoil-protonsudgenerated across. The MST measures the residual energy of recoil-protons downstream of the converterudand also discriminates recoil-protons from photons associated to the neutron field. The lay-out ofudthe scintillator/MST system was optimized through an analytical model for selecting the angular range ofudthe scattered protons. The use of unfolding techniques for reconstructing the neutron energy distributionudwas thus avoided with reasonable uncertainty (about 1.6% in neutron energy) and efficiency (of the orderudof 106 counts per unit neutron fluence). A semi-empirical procedure was also developed for correctingudthe non-linearity in light emission from the organic scintillator. The spectrometer was characterized withudquasi-monoenergetic and continuous fields of neutrons generated at the CN Van De Graaff accelerator ofudthe INFN-Legnaro National Laboratory, Italy, showing satisfactory agreement with literature data.