Measurements of (n,$\gamma$) neutron capture cross-sections with liquid scintillator detectors

J.N. Wilson (1) , B. Haas (1) , S. Boyer (1) , D. Dassie (1) , G. Barreau (1) , M. Aiche (1) , S. Czajkowski (1) , C. Grosjean (1) , A. Guiral (1)

1 CENBG - Centre d'Etudes Nucléaires de Bordeaux Gradignan

A method for measuring (n,$\gamma$) neutron capture cross-sections using liquid scintillator detectors has been investigated. If the response function of the detector is known, and the efficiency as a function of energy is low and approximately constant, then gamma cascades can be counted via a method that is independent of the cascade path provided the detector response is manipulated to allow detection efficiency to be proportional to emitted gamma-ray energy. In this paper, we demonstrate the measurement of efficiency and response functions for a C6D6 liquid scintillator using gamma-ray sources and (p,$\gamma$) reactions on light nuclei. Methods to reproduce the detector response and efficiency data successfully using simulations are presented and discussed. An entire response matrix for the detector has been constructed using a new interpolation technique, allowing weighting functions that force the detector efficiency to be proportional to gamma-ray energy to be calculated. An analysis of the sources of error involved in making (n,$\gamma$) cross-section measurements with this method has been undertaken using Monte-Carlo simulation techniques.

Mots clés: $\gamma$ capture cross sections; Liquid scintillators; Response functions; Weighting functions; Monte Carlo techniques

Domaines: Physique Nucléaire Expérimentale [nucl-ex]

J.N. Wilson, B. Haas, S. Boyer, D. Dassie, G. Barreau, et al.. Measurements of (n,$\gamma$) neutron capture cross-sections with liquid scintillator detectors. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2003, 511, pp.388-399. ⟨10.1016/S0168-9002(03)01944-2⟩. ⟨in2p3-00103375⟩