EXILL - a high efficiency, high resolution setup for γ-spectroscopy at an intense cold neutron beam

EXILL - a high efficiency, high resolution setup for γ-spectroscopy at an intense cold neutron beam

Jentschel, M.; Blanca, A.; de France, G.; Köster, U.; Leoni, S.; Mutti, P.; Simpson, G.; Soldner, T.; Ur, C.; Urban, W.; Ahmed, S.; Astieri, A.; Augey, L.; Back, T.; Baczyk, P.; Bajoga, A.; Balabanski, D.; Belgya, T.; Benzoni, G.; Bernards, C.; Biswas, D.; Bocchi, G.; Bottoni, S.; Britton, R.; Bruyneel, B.; Burnett, J.; Cakirli, R. B.; Carroll, R.; Catford, W.; Cederwall, B.; Celikovic, I.; Cieplicka, N.; Clement, E.; Cooper, N.; Crespic, F.; Csatlos, M.; Czerwinski, M.; Danu, L.; Davies, A.; Didierjean, F.; Drouet, F.; Duchene, G.; Ducoin, C.; Eberhardt, K.; Erturk, S.; Fraile, L. M.; Gottardo, A.; Grente, L.; Grocutt, L.; Guerrero, C.; Guinet, D.; Hartig, A.-L.; Henrich, C.; Ignatov, A.; Ilieva, S.; Ivanova, D.; John, B.; John, R.; Jolie, J.; Kisyov, S.; Konstantinopoulos, T.; Korgul, A.; Krasznahorkay, A.; Kröll, T.; Kurpeta, J.; Kutiu, I.; Lalkovski, S.; Larijani, C.; Leguillon, R.; Lica, R.; Litaize, O.; Magron, C.; Mancuso, C.; Ruiz Martinez, E.; Massarczyk, R.; Mazzocchi, C.; Melon, B.; Mengoni, D.; Million, B.; Mokry, C.; Mukhopadhyay, S.; Mulholland, K.; Nannini, A.; Napoli, D. R.; Olaizola, B.; Orlandi, R.; Patel, Z.; Paziy, V.; Petrache, C.; Pfeiffer, M.; Podolyak, Z.; Ramdhane, M.; Redon, N.; Regan, P.; Regis, J. M.; Regnier, D.; Oliver, R. J.; Rudigier, M.; Runke, J.; Rzaca-Urban, T.; Saed-Samii, N.; Salsacq, M. D.; Scheck, M.; Schwengner, R.; Sengele, L.; Simpson, G.; Singh, P.; Smith, J.; Stezowski, O.; Szpak, B.; Thomas, T.; Thürauf, M.; Timaru, J.; Toml, A.; Tomandl, I.; Tornyi, T.; Townsley, C.; Tuerler, A.; Valenta, S.; Vancraeyenest, A.; Vandone, V.; Vanhoy, J.; Vedia, V.; Warr, N.; Werner, V.; Wilmsen, D.; Wilson, E.; Zerrouki, T.; Zielinska, M.

In the EXILL campaign a highly efficient array of HPGe detectors was operated at the cold neutron beam instrument PF1B of the Institut Laue-Langevin to carry out nuclear structure studies, via measurements of -rays following neutron-induced capture and fission reactions. The setup consisted of a collimation system producing a pencil beam with a thermal capture equivalent
flux of about 108 s-1 cm-2 at the target position and negligible neutron halo. The target was surrounded by an array of eight to ten anti-Compton shielded EXOGAM clover detectors, four to six
anti-Compton shielded large coaxial GASP detectors and two smaller clover detectors. The detectors were arranged in an array of rhombicuboctahedron geometry, providing the possibility to carry out very precise angular correlation and directional-polarization correlation measurements. The trigger-less acquisition system allowed an event collection rate of up to 6 × 105 Hz. From triggerless collected data it was possible to construct decay schemes and in combination with the FATIMA array of LaBr3 detectors to analyze half-lives of excited levels in the pico- to micro-second range. Precise energy and efficiency calibrations of EXILL were performed using 27Al(n,γ)28Al and 35Cl(n,γ)36Cl reactions in the energy range from 30 keV up to 10 MeV.

Keywords: neutron-induced fission; 235U; 241Pu; (n,γ)-reactions; Ge detectors; angular correlations; multiple-γ coincidences

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