Investigation of high energy γ-rays accompanying spontaneous fission of 252Cf in double and triple neutron-γ coincidences

The high energy bremsstrahlung gamma-rays accompanying the spontaneous fission of Cf-252 were measured in the 10-70 MeV energy range. The photons were detected by two BGO scintillator detectors (circle divide 7.6cm x 7.6cm) in coincidence with neutrons detected by plastic scintillator detector, in the 90 degrees and 180 degrees geometry of the two BGO detectors with respect to the axis of the plastic scintillator. The distance from the Cf-252 source to the BGO detectors was 10 cm, and the one to the plastic detector was 50 cm. The fast digital shape analysis technique and the time-of-flight method were used to reject pile-up effects and cosmic ray background. The gamma-ray emission probability of 3 x 10(-8)photon/(MeV x fission) at E gamma = 70 MeV was obtained.