In 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 γ-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 n s−1cm−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 standard Clover detectors. For a part of the campaign the array was combined with 16 LaBr3:(Ce) detectors from the FATIMA collaboration. 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 triggerless acquisition system allowed a signal collection rate of up to 6 × 105 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 133Ba, 60Co and 152Eu as well as data from the reactions 27Al(n,γ)28Al and 35Cl(n,γ)36Cl in the energy range from 30 keV up to 10 MeV.
The multiplicities of prescission protons and n particles in the reaction ' F+ Th at 104, 110, 116, and 118 MeV have been measured. The observed multiplicities are much larger than the prediction of the statistical model without the introduction of fission delay. An analysis of the prescission proton and u data along with that for neutrons (measured earlier) has been made using deformed optical model and deformation-dependent particle binding energies. Simultaneous fits to the charged particle and neutron data required a total fission time scale in the range of (25 -80)X 10 ' s. For this system, the mean kinetic energies of the prescission particles are insensitive to the division of the total delay time into presaddle and postsaddle components; however, the neutron and charged particle multiplicity data are sensitive to the deformation of the saddle-to-scission emitter.The analysis shows that postsaddle emission takes place close to the scission point. PACS number(s): 25.70.Jj, 25.85.6e
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