A SPIKE OF MO-98(42) IN YIELDS OF URANIUM SPONTANEOUS FISSION AN EXTENSION OF SHELL STRUCTURE EFFECT

The investigations of the isotopic abundance ratios of molybdenum in z ircon have shown that the molybdenum isotopic composition obtained ref lects two effects: (1) spontaneous fission of U-238(92) contained in t he zircon and (2) double beta decay of Zr(-96(40). Interestingly, howe ver, the products due to the spontaneous fission appear to have a stra nge large excess (spike) of Mo-98(42). It intrigues us that 92 minus 4 2 leaves 50, one of the outstanding magic numbers. It is suggested in the present communication that the strange spike of Mo-98(42) in quest ion can result from a special type of sontaneous fission having essent ial bearings on the magic number 50 of protons and the ''magical'' num bers 58 and 92 of neutrons.