Studies of prompt gamma ray multiplicity distributions in spontaneous fission of 252Cf

Shape parameters of the prompt gamma ray multiplicity distributions in spontaneous fission of 252Cf have been obtained by the multiple coincidence technique. Using three NaI(Tl) detectors for detecting the gamma rays, the single, double and triple coincidence rates between the fission pulse and any one, two or all the three detectors were measured and were used to obtain the second and third moments of the total gamma ray multiplicity distributions. The second and third moments were estimated to be 124.2 +- 1.7 and 1659 +- 20 respectively. Using the known value of 10.3 for the average number of gamma rays per fission, the measured moments correspond to a Gaussian distribution with a FWHM equal to 10 +- 1. The above measurements were extended to obtain the widths of the multiplicity distribution as a function of fragment kinetic energy. These results are discussed in terms of the mechanism of gamma ray emission from fission fragments. (author)