Liquid Scintillators Neutron Response Function: A Tutorial

Abstract

This tutorial is devoted to the understanding of the different components that are present in the neutron light output pulse height distribution of liquid scintillators in fusion relevant energy ranges. The basic mechanisms for the generation of the scintillation light are briefly discussed. The different elastic collision processed between the incident neutrons and the hydrogen and carbon atoms are described in terms of probability density functions and the overall response function as their convolution. The results from this analytical approach is then compared with those obtained from simplified and full Monte Carlo simulations. Edge effect, finite energy resolution, light output and transport and competing physical processes between neutron and carbon and hydrogen atoms and their impact on the response functions are discussed. Although the analytical treatment here presented allows only for a qualitative comparison with full Monte Carlo simulations it enables an understanding of the main features present in the response function and therefore provides the ground for the interpretation of more complex response functions such those measured in fusion plasmas. Although the main part of this tutorial is focussed on the response function to mono-energetic 2.45 MeV neutrons a brief discussion is presented in case of broad neutron energy spectra and how these can be used to infer the underlying properties of fusion plasmas via the application of a forward modelling method.

Method for environmental noise estimation via injection tests for ground-based gravitational wave detectors

“…The microphones, speakers, and amplifiers used in this study are summarized in Table 1. § The response function is widely used in the field of fast-neutron detector [11].…”

Method for environmental noise estimation via injection tests for ground-based gravitational wave detectors

“…where R( f, f ) is the response function 7 , ε = ε( f, f , P bkg ) is a function that describes some nonlinearity (ε = 1 for linear response). 7 The response function is widely used in the field of fast-neutron detector [11]. The coupling function model is included as…”

Validation of neutron emission and neutron energy spectrum calculations on MAST with DRESS

“…The proton light output function found in literature [28] has been used in this work. The acquisition threshold has been included in the modelling of the PHS after folding the total neutron spectrum with the response function matrix based on the acquisition of 22 Na γ−ray spectra and estimated to be E thr ≃ 0.12 MeVee (1MeVee ≃ 2.86 MeV proton). The contributions from "pile-up" (containing two or more superimposed separable events) and coincident "pile-up" events in the detectors have been investigated.…”

“…All scattering angles are roughly equiprobable and the recoil proton pulse height spectrum (PHS) extends from zero energy (grazing collision) to the incident neutron energy (head-on collision). The ideal box-like recoil proton PHS is smoothed at the high energy end and enhanced at the low energy end by the detector finite energy resolution and by its non-linear light output [22]. In addition, since neutrons emitted from a plasma are not mono-energetic, modelling of the experimentally measured PHS requires the estimation of the neutron energy spectrum Ψ at the detector location and of the response function matrix of the liquid scintillator for all neutron energies of interest.…”