DIRECT COMPARISON OF THE B$sup 12$ AND N$sup 12$ BETA SPECTRA

An experimental direct comparison of the shapes of the B/sup 12/ and N/ sup 12/ beta decay spectra was made as a test of the validity of the conserved vector current theory (CVCT). The comparison was made at corresponding momentum points normalized to the end-point momenta of the spectra using a 5-channel 180 deg magnetic spectrometer. The comparative shape factor was measured to have an energy dependence of 1.62 plus or minus 0.28% per Mev, to be compared with a predicted value of 1.10 plus or minus 0.17% per Mev on the basis of the CVCT. The measured end-point energy of the N/sup 12/ groundstate spectrum is 16.384 plus or minus 0.015 Mev. The comparison of the spectra also yielded a value of 2.2 plus or minus 0.6% for the branching fraction of the N/sup 12/ decay to the 7.6-Mev level of C/sup 12/ 0.85 plus or minus 0.6% for the fraction to the 10.1- Mev level, and an indication of a branch to one or more levels around 12 Mev. (auth)

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