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Plaza, J., Bécares, V., Cano-Ott, D., Gómez, C., Martínez, T., Mendoza, E., et al. (2023). CLYC as a neutron detector in low background conditions. Eur. Phys. J. C, 83(11), 1049–10pp.
Abstract: We report on the thermal neutron flux measurements carried out at the Laboratorio Subterraneo de Canfranc (LSC) with two commercial 2 '' x 2 '' CLYC detectors. The measurements were performed as part of an experimental campaign at LSC with He-3 detectors, for establishing the sensitivity limits and use of CLYCs in low background conditions. Acareful characterization of the intrinsic alpha and gamma-ray background in the detectors was required and done with dedicated measurements. It was found that the alpha activities in the two CLYC crystals differ by a factor of three, and the use of Monte Carlo simulations and a Bayesian unfolding method allowed us to determine the specific alpha activities from the U-238 and Th-232 decay chains. The simulations and unfolding also revealed that the gamma-ray background registered in the detectors is dominated by the intrinsic activity of the components of the detector such as the aluminum housing and photo-multiplier and that the activity within the crystal is low in comparison. The data from the neutron flux measurements with the two detectors were analyzed with different methodologies: one based on an innovative alpha/neutron pulse shape discrimination method and one based on the subtraction of the intrinsic alpha background that masks the neutron signals in the region of interest. The neutron sensitivity of the CLYCs was calculated by Monte Carlo simulations with MCNP6 and GEANT4. The resulting thermal neutron fluxes are in good agreement with complementary flux measurement performed with He-3 detectors, but close to the detection limit imposed by the intrinsic a activity.
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Plaza, J., Martinez, T., Becares, V., Cano-Ott, D., Villamarin, D., de Rada, A. P., et al. (2023). Thermal neutron background at Laboratorio Subterraneo de Canfranc (LSC). Astropart Phys., 146, 102793–9pp.
Abstract: The thermal neutron background at Laboratorio Subterraneo de Canfranc (LSC) has been determined using several He-3 proportional counter detectors. Bare and Cd shielded counters were used in a series of long measurements. Pulse shape discrimination techniques were applied to discriminate between neutron and gamma signals as well as other intrinsic contributions. Montecarlo simulations allowed us to estimate the sensitivity of the detectors and calculate values for the background flux of thermal neutrons inside Hall-A of LSC. The obtained value is (3.5 +/- 0.8)x10(-6) n/cm(2)s, and is within an order of magnitude compared to similar facilities.
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Tain, J. L., Agramunt, J., Algora, A., Aprahamian, A., Cano-Ott, D., Fraile, L. M., et al. (2015). The sensitivity of LaBr3:Ce scintillation detectors to low energy neutrons: Measurement and Monte Carlo simulation. Nucl. Instrum. Methods Phys. Res. A, 774, 17–24.
Abstract: The neutron sensitivity of a cylindrical circle minus 1.5 in x 1.5 in LaBr3:Ce scintillation detector was measured using quasi-monoenergetic neutron beams in the energy range from 40 keV to 2.5 MeV. In this energy range the detector is sensitive to gamma-rays generated in neutron inelastic and capture processes. The experimental energy response was compared with Monte Carlo simulations performed with the Geant4 simulation toolkit using the so-called High Precision Neutron Models. These models rely on relevant information stored in evaluated nuclear data libraries. The performance of the Geant4 Neutron Data Library as well as several standard nuclear data libraries was investigated. In the latter case this was made possible by the use of a conversion tool that allowed the direct use of the data from other libraries in Geant4. Overall it was found that there was good agreement with experiment for some of the neutron data bases like ENDF/B-VII.0 or JENDL-3.3 but not with the others such as ENDF/B-VI.8 or JEFF-3.1.
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Tain, J. L., Algora, A., Agramunt, J., Guadilla, V., Jordan, M. D., Montaner-Piza, A., et al. (2015). A decay total absorption spectrometer for DESPEC at FAIR. Nucl. Instrum. Methods Phys. Res. A, 803, 36–46.
Abstract: This paper presents the design of a total absorption gamma-ray spectrometer for the determination of beta-decay intensity distributions of exotic nuclear species at the focal plane of the FAIR-NUSTAR Super Fragment Separator. The spectrometer is a key instrument in the DESPEC experiment and the proposed implementation follows extensive design studies and prototype tests. Two options were contemplated, based on Nal(TI) and LaBr3:Ce inorganic scintillation crystals respectively. Monte Carlo simulations and technical considerations determined the optimal configurations consisting of sixteen 15 x 15 x 25 cm(3) crystals for the Nal(Tl) option and one hundred and twenty-eight 5.5 x 5.5 x 11 cm(3) crystals for the LaBr3:Ce option. Minimization of dead material was crucial for maximizing the spectrometer full-energy peak efficiency. Module prototypes were build to verify constructional details and characterize their performance. The measured energy and timing resolution was found to agree rather well with estimates based on simulations of scintillation light transport and collection. The neutron sensitivity of the spectrometer, important when measuring beta-delayed neutron emitters, was investigated by means of Monte Carlo simulations.
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