Experimental Investigation of Parity Conservation in the 14.4-kev Gamma Transition inFe57

Abstract

An experiment using recoilless resonance scattering on the 14.4-kev $M1\mathrm{}$ gamma rays of ${\mathrm{Fe}}^{57}$ was performed to set a limit on the degree of parity impurities in the nuclear states involved. The anisotropies of the $\Delta m=\pm 1$ gamma-ray transition rates were examined towards and away from the direction of nuclear polarization. The use of recoilless resonance scattering allows the problem to be so overdetermined that instrumental anisotropies could be cancelled by appropriate summing of data. No parity-nonconserving anisotropy was observed. Taking into account the slowness of the $M1\mathrm{}$ transition compared to a parity-admixed $E1\mathrm{}$ transition of single-particle speed, a factor of 100 in amplitude, the limit on $\mathcal{F}$, the relative strength of a parity-admixed wave function is, $\mathcal{F}<~{10}^{-5\mathrm{}}$.