Développement d'un nouveau multi-détecteur de neutrons

Abstract : Beta-decay is a crucial tool in exploring the structure of exotic nuclei. The decay of neutronrich nuclei is often followed by the emission of delayed neutrons. This work focuses on the R&D for a new modular time-of- ight array for decay spectroscopy. The detector will use a liquid scintillator, allowing for neutron-gamma discrimination, and will be coupled to a digital acquisition system. The neutron-gamma discrimination was investigated using the FASTER digital electronics. First, the well known charge comparison method was studied and performances superior to those obtained with standard analogue electronics were obtained. Di erent methods were also explored and compared quantitatively. Except for the method of Gatti and De Martini, charge comparison provides the best discrimination. In order to overcome the limitations of liquid scintillators for low-energy neutrons (En<1 MeV), the light yield and discrimination capabilities were evaluated for 7 small volume scintillators including liquids, crystals and new discriminating plastic scintillators. The best performances were obtained for stilbene and p-therpenyl crystals. Intrinsic detection e fficiencies and cross talk probabilities of the envisaged modules were measured with monoenergetic neutrons in the range 0.5 to 15.5 MeV. In the case of cross talk, this represents the fi rst measurements ever made for low energy neutrons (1.4 to 5 MeV). Monte Carlo simulations were undertaken for both the effi ciencies and cross talk. In the case of the former very good agreement was found, and while the overall behavior of the cross talk could be reproduced more sophisticated simulations need to be developed.
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  • HAL Id : tel-01064554, version 1

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M. Sénoville. Développement d'un nouveau multi-détecteur de neutrons. Physique Nucléaire Expérimentale [nucl-ex]. Université de Caen, 2013. Français. ⟨tel-01064554⟩

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