The β spectrum following fission from ^(252)Cf

Citation

Wark, David Lee (1987) The β spectrum following fission from ^(252)Cf. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:01052012-145244894

Abstract

The β spectrum from the fission products of ^(252)Cf has been measured using a flat-field magnetic spectrometer. The active entrance aperture to the magnetic field region consisted of an annular plastic scintillator to veto slit scattering and a thin wire chamber to signal electrons on a good trajectory. The electrons exited the magnetic field through a position sensitive wire chamber capable of three dimensional track reconstruction. The energy calibration and relative efficiency of the spectrometer were determined using the β decays of ^(12)B ^(20)F, and ^(90)Sr. The shape of the β spectrum from ^(252)Cf was measured at 5 field settings and the results combined to form a complete spectrum from 2.0 to 9.0 MeV (β total energy) with a total error of 3% at 3 MeV, rising to 6% at 5 MeV, 9% at 7 MeV, 15% at 8 MeV and 25% at 9 MeV. This experiment was motivated by the need to know the ν_e spectrum from the β decays of fission products in order to interpret the results of reactor based neutrino oscillation experiments. The ν_e spectrum can be calculated directly or converted from a measured β spectrum. This experiment is an additional check of these calculations and constitutes a complementary check of previous measurements of the β spectrum from other fissioning nuclei ^(235)U, ^(239)Pu, and ^(241)Pu. We find a softer spectrum fewer β at high momenta) than predicted by the calculations, in agreement with earlier measurements in other nuclei by Schreckenbach et al.. but in disagreement with earlier measurements by Borovoi et al. in ^(252)Cf. Possible sources of the disagreement with the calculations and the earlier experiment and possible improvements to the experiment are discussed.

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