The beta-spectra of the forbidden transitions of Y 91 , Sr 89 , Y 90 , Cs 137 , RaE, Au 198 , Re 186 , and P 32 have been measured with thin sources and high resolution. Forbidden type spectra are found for the first five. Au 198 , Re 186 , and P 32 yield spectra with the allowed shape. Evidence is advanced for the reliability of the nuclear shell structure model and for the validity of G.-T. selection rules. End points found are: Y 91 , 1.537±0.007 Mev; Sr 89 , 1.463±0.005 Mev; Y 90 , 2.180±0.007 Mev; Cs 137 , 0.51±0.01 Mev; Au 198 , 0.956±0.005 Mev; Re 186 , 1.063±0.006; and P 32 , 1.689±0.01 Mev.

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