Gamma-Gamma Angular Correlation inNi60

Abstract

The angular correlation of the gamma rays emitted in cascade from the excited states of ${\mathrm{Ni}}^{60}$ has been measured at increments of 10° from 90° to 270° with automatic apparatus using sodium iodide detectors and 5819 photomultipliers. For a dilute Co${\mathrm{Cl}}_2$ source, the correlation obtained is $W\left(\theta \right)=1+(0.131\mathrm{}\pm 0.017){cos}^2\theta +(0.024\mathrm{}\pm 0.017){cos}^4\theta$. The anisotropy, $\frac{({\alpha }_2+{\alpha }_4)}{{\alpha }_0}\equiv R$, where $W\left(\theta \right)={\alpha }_0+{\alpha }_2{cos}^2\theta +{\alpha }_4{cos}^4\theta$, is 0.1557 ±0.0010. The expected value of $R$, taking the finite angular resolution of the apparatus into account, is 0.1517. A change in the anisotropy to a value of 0.1453±0.0023 due to a chemical change in the source was observed.