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

摘要

We have developed a new setup to measure prompt fissionγ-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) LaBr3(Ce) scintillators, to measure theγrays. The setup was used to obtain the prompt fissionγ-ray spectrum for thermal neutron induced fission of235U at the PF1B cold-neutron beam facility of the Institut Laue-Langevin, Grenoble, France. We have successfully measured theγ-ray spectrum up to energies of about 20 MeV, what extends the currently knownγ-ray spectrum limit to higher energies by approximately a factor of two.