We introduce the LUNA neutron detector array developed for the investigation of the C-13(alpha, n)O-16 reaction towards its astrophysical s-process Gamow peak in the low-background environment of the Laboratori Nazionali del Gran Sasso (LNGS). Eighteen He-3 counters are arranged in two different configurations (in a vertical and a horizontal orientation) to optimize neutron detection efficiency, target handling and target cooling over the investigated energy range E-alpha,E-lab = 300 - 400 keV (E-n = 2.2 - 2.6 MeV in emitted neutron energy). As a result of the deep underground location, the passive shielding of the setup and active background suppression using pulse shape discrimination, we reached a total background rate of 1.23 +/- 0.12 counts/hour. This resulted in an improvement of two orders of magnitude over the state of the art allowing a direct measurement of the C-13(alpha, n)O-16 cross-section down to E-alpha,E-lab = 300 keV. The absolute neutron detection efficiency of the setup was determined using the V-51(p,n)Cr-51 reaction and an AmBe radioactive source, and completed with a Geant4 simulation. We determined a (34 +/- 3)% and (38 +/- 3)% detection efficiency for the vertical and horizontal configurations, respectively, for E-n = 2.4 MeV neutrons.

Characterization of the LUNA neutron detector array for the measurement of the 13C(α, n)16O reaction / L. Csedreki, G.F. Ciani, J. Balibrea-Correa, A. Best, M. Aliotta, F. Barile, D. Bemmerer, A. Boeltzig, C. Broggini, C.G. Bruno, A. Caciolli, F. Cavanna, T. Chillery, P. Colombetti, P. Corvisiero, T. Davinson, R. Depalo, A. Di Leva, Z. Elekes, F. Ferraro, E.M. Fiore, A. Formicola, Z. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, G. Gyürky, G. Imbriani, Z. Janas, M. Junker, I. Kochanek, M. Lugaro, P. Marigo, E. Masha, C. Mazzocchi, R. Menegazzo, V. Mossa, F.R. Pantaleo, V. Paticchio, R. Perrino, D. Piatti, P. Prati, L. Schiavulli, K. Stöckel, O. Straniero, T. Szücs, M.P. Takács, F. Terrasi, S. Zavatarelli. - In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH. SECTION A, ACCELERATORS, SPECTROMETERS, DETECTORS AND ASSOCIATED EQUIPMENT. - ISSN 0168-9002. - 994:(2021), pp. 165081.1-165081.8. [10.1016/j.nima.2021.165081]

Characterization of the LUNA neutron detector array for the measurement of the 13C(α, n)16O reaction

R. Depalo;F. Ferraro;A. Guglielmetti;E. Masha;
2021

Abstract

We introduce the LUNA neutron detector array developed for the investigation of the C-13(alpha, n)O-16 reaction towards its astrophysical s-process Gamow peak in the low-background environment of the Laboratori Nazionali del Gran Sasso (LNGS). Eighteen He-3 counters are arranged in two different configurations (in a vertical and a horizontal orientation) to optimize neutron detection efficiency, target handling and target cooling over the investigated energy range E-alpha,E-lab = 300 - 400 keV (E-n = 2.2 - 2.6 MeV in emitted neutron energy). As a result of the deep underground location, the passive shielding of the setup and active background suppression using pulse shape discrimination, we reached a total background rate of 1.23 +/- 0.12 counts/hour. This resulted in an improvement of two orders of magnitude over the state of the art allowing a direct measurement of the C-13(alpha, n)O-16 cross-section down to E-alpha,E-lab = 300 keV. The absolute neutron detection efficiency of the setup was determined using the V-51(p,n)Cr-51 reaction and an AmBe radioactive source, and completed with a Geant4 simulation. We determined a (34 +/- 3)% and (38 +/- 3)% detection efficiency for the vertical and horizontal configurations, respectively, for E-n = 2.4 MeV neutrons.
Helium-3 counter; Low-background; Underground laboratory; Nuclear Astrophysics; Neutron
Settore FIS/04 - Fisica Nucleare e Subnucleare
2021
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/843660
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