Shape of the 935 keV beta transition of143Pr

The beta spectrum shape of the 7/2⁺ → 7/2^? beta transition in the decay of¹⁴³Pr is measured employing a thoroughly tested intermediate image beta ray spectrometer of the Siegbahn-Slatis type and using the source produced by irradiation of highly enriched stable¹⁴²Ce sample. The spectrum exhibits a definite energy dependence and is well fitted with shape factorC(W) = 1 ? (0·057 ± 0·006)W whereW is in m₀c² units for an end point energy of 935 ± 2 keV agreeing well with the results of Hamiltonet al and Spejweskiet al and disagreeing with the results of Persson and Reynolds. The single particle configurations for the low lying levels of¹⁴³Pr could not give quantitative results.