Beta-Gamma Directional Correlation inRe188

The directional correlation between the 1960-keV beta group and the 155-keV gamma in the decay of ${\mathrm{Re}}^{188}$ has been measured. The coefficient $A_2$ is found to vary from about 0.17 to about 0.25 over the energy range $W=3\mathrm{}$ to $W=4.3\mathrm{}$. Limitations on the matrix elements for the sequence $1^{-}\left(\beta \right)2^{+}\left(\gamma \right)0^{+}$ are discussed. It is found that the directional correlation and a variety of beta spectral shapes may be fitted for values of the parameter $\left|{\zeta }_1\right|$ greater than some minimum value which is dependent upon the spectral shape. Information is presented on further limitations of the matrix elements which will result when the shape is known and some discussion is given for the role of a measurement of the beta-circularly polarized gamma correlation.