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

WOS: 000414625700003In the EXILL campaign a highly efficient array of high purity germanium (HPGe) detectors was operated at the cold neutron beam facility PF1B of the Institut Laue-Langevin (ILL) to carry out nuclear structure studies, via measurements of gamma-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 10(8) ns(-1)cm(2) at the target position and negligible neutron halo. The targetwas surrounded by an array of eight to ten anti-Compton shielded EXOGAMClover detectors, four to six anti-Compton shielded large coaxial GASP detectors and two standard Clover detectors. For a part of the campaign the array was combined with 16 LaBr3:(Ce) detectors from the FATIMA collaboration. The detectorswere arranged in an array of rhombicuboctahedron geometry, providing the possibility to carry out very precise angular correlation and directional-polarization correlation measurements. The triggerless acquisition system allowed a signal collection rate of up to 6 x 10(5) Hz. The data allowed to set multi-fold coincidences to obtain decay schemes and in combination with the FATIMA array of LaBr3:(Ce) detectors to analyze half-lives of excited levels in the pico-to microsecond range. Precise energy and efficiency calibrations of EXILL were performed using standard calibration sources of Ba-133, Co-60 and Eu-152 as well as data from the reactions Al-27(n, gamma)Al-28 and Cl-35(n,gamma)Cl-36 in the energy range from 30 keV up to 10MeV.U.S. DOE grant [DE-FG02-91ER40609]; NUPNET; German BMBF [O5P12PKNUF, 05P15RDFN1, 05P12RDNUP]; German DFG contract [KR 1796/2-1]; Polish National Science Centre [DEC-2013/09/B/ST2/03485]This work has been partly supported by the Polish National Science Centre under contract DEC-2013/09/B/ST2/03485, the U.S. DOE grant No. DE-FG02-91ER40609, the NUPNET and the German BMBF under contracts O5P12PKNUF, 05P15RDFN1 and 05P12RDNUP and the German DFG contract KR 1796/2-1