The high energy bremsstrahlung γ-rays accompanying the spontaneous fission of 252-Cf were measured in the 10-70 MeV energy range. The photons were detected by two BGO scintillator detectors ( 7.6cm × 7.6cm) in coincidence with neutrons detected by plastic scintillator detector, in the 90◦ and 180◦ geometry of the two BGO detectors with respect to the axis of the plastic scintillator. The distance from the 252 Cf 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 γ-ray emission probability of 3 × 10−8 photon/(MeV × f ission) at Eγ = 70 MeV was obtained.

High energy bremsstrahlung emission during spontaneous fission of 252-Cf is observed. The new experimental method to detect rare coincident events by digital storage oscilloscope is used. The γ-rays with energies up to 60 MeV have been measured (by a BGO detector) in coincidence with neutrons detected by a plastic scintillator. The determination of γ-ray emission probability up to the value of about 8 × 10−9 event/(MeV × fission) at Eγ = 60 MeV is achieved.