A New detector system for the measurement of high-energy prompt -rays for low-energy neutron induced fission

Makii, Hiroyuki   ; Nishio, Katsuhisa   ; Hirose, Kentaro  ; Orlandi, R.   ; Lguillon, R.*; Ogawa, Tatsuhiko   ; Soldner, T.*; Hambsch, F.-J.*; Ache, M.*; Astier, A.*; Czajkowski, S.*; Frost, R.*; Guo, S.*; Kster, U.*; Mathieu, L.*; Otsuki, Tsutomu*; Petrache, C. M.*; Pollitt, A.*; Sekimoto, Shun*; Takamiya, Koichi*; Tsekhanovich, I.*

We have developed a new setup to measure prompt fission -ray spectra in neutron induced fission up to energies sufficient to reveal the structure associated with giant dipole resonances of fission fragments. The setup consists of multi-wire proportional counters, to detect both fission fragments in coincidence, and two large volume (101.6 mm in diameter and 127.0 mm in length) LaBr(Ce) scintillators, to measure the -rays. The setup was used to obtain the prompt fission -ray spectrum for thermal neutron induced fission of U at the PF1B cold-neutron beam facility of the Institut Laue-Langevin, Grenoble, France. We have successfully measured the -ray spectrum up to energies of about 20 MeV, what extends the currently known -ray spectrum limit to higher energies by approximately a factor of two.