In this study, shadow cones were examined with Bonner sphere spectrometer (BSS) for the measurement of neutron spectrum of an 241Am-Be source. Our BSS consists of a set of nine polyethylene spheres with a centeral 6LiI(Eu) scintillator sensitive to thermal neutron. The energy response matrix of the BSS was determined by Monte Carlo simulations for the neutron energies from 10-8 to 100 MeV. A crucial problem in neutron measurements is determining the contribution of scattered neutrons coming from the structures and materials surrounding a source. Two shadow cones were manufactured and positioned between the source and the detector. Experiments were performed to select the optimal source to shadow-cone distance. An unfolding code was used to obtain neutron spectra. The difference between the unfolded spectra obtained by using the shadow cones and the ISO reference spectra was considered as a parameter to select the optimum condition for the shadow cone technique application. The unfolded spectra obtained with the shadow-cone technique showed a satisfactory agreement with the ISO 8529-1241Am–Be neutron spectrum.

Analysis of the application of the shadow cone technique for the determination of neutron spectrum with Bonner sphere spectrometer

CIOLINI, RICCARDO;
2013

Abstract

In this study, shadow cones were examined with Bonner sphere spectrometer (BSS) for the measurement of neutron spectrum of an 241Am-Be source. Our BSS consists of a set of nine polyethylene spheres with a centeral 6LiI(Eu) scintillator sensitive to thermal neutron. The energy response matrix of the BSS was determined by Monte Carlo simulations for the neutron energies from 10-8 to 100 MeV. A crucial problem in neutron measurements is determining the contribution of scattered neutrons coming from the structures and materials surrounding a source. Two shadow cones were manufactured and positioned between the source and the detector. Experiments were performed to select the optimal source to shadow-cone distance. An unfolding code was used to obtain neutron spectra. The difference between the unfolded spectra obtained by using the shadow cones and the ISO reference spectra was considered as a parameter to select the optimum condition for the shadow cone technique application. The unfolded spectra obtained with the shadow-cone technique showed a satisfactory agreement with the ISO 8529-1241Am–Be neutron spectrum.
Mirzajani, N.; Ciolini, Riccardo; Curzio, G.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/227934
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