-Ray Spectrum and ft-Values in teh Forbidden Transitions
S. Nakamura, Hisao Takebe, M. Umezawa · Progress of Theoretical Physics · 1951
It is shown that the j9-spectra of Tc99, Sb124 in the second-forbidden transition, and Tm170 in the first forbidden transition, can be explained by the tensor or vector interaction of the Fermi theory, if a suitable linear combination of matrix elements are chosen.Using the ratio of the matrix elements to provide a good fitting with the experimental spectra, ft-values of each fl-decay are evaluated on the corrected forbidden fonnula.Criticism is made with respect to the explanation of the beta spectrum of RaE by Konopinski and Uhlenbeck.§ 1. Introduction Forbidden {1-ray spectra predicted by the Fermi theory have different shapes corresponding to various interaction types and selection rules of {1-transitions.Discoveries of new type spectra verified the occurrence of forbidden transitions, i.e., • a' type spectra imply the transition with LlJ= ±2, parity change yes, and 'D2' type spectra with ilJ= ±3, parity change no.They can be explained by the tensor interaction, the former in the 1st forbidden, the latter in 2nd forbidden transition; both transitions select the unique nuclear matrix element, B'j and S'jk' respectively.Recently, another new type of forbidden spectrum of Cl 3 ft was successfully explained by C. S. Wu and L. Feldman l ) by means of a linear combination of A'j and T'j terms in the second fordidden tensor interaction.This provides a strong support for the forbidden theory, and stimulated us to develop further interpretation of forbidden spectra on the same principle.Correction factors given by Konopinski and Uhlenbeck can be written as follows, if .theselection rule, LlJ--±2, parity change no, holds, C2T/,BIT1jI2-k~T(3a) + 1~ (3D+-c)-k2~' (1) for the second forbidden transition, and if the selection rule ilJ-± 1,0, parity change yes is valid, CIT/I 1<1 xrf-~T+A+'-klpB, Cn /I!'rI2 -k~,.+A+-