A study of interference between resonant nuclear and Rayleigh scatterings by Fe-57 with selective excitation

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1974

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Abstract

The interference between resonant nuclear and Rayleigh scattering in 90° scattering of 14.4 keV gamma rays from the Mossbauer Fe-57 scatterer was studied. This interference becomes constructive or destructive depending upon the vectorial relations between the incoming gamma ray k[lowered 1] , the outgoing gamma ray kg and the direction of the polarization of the scatterer B. This effect was first observed by L.Y. Lee and Clark Goodman, who measured the magnitude of the effect at roughly 6%. By analyzing gamma rays re-emitted from the scatterer with a selective excitation scheme, we have intensified this interference effect. The differences in intensity between a polarization of B being parallel to k[lowered 1] x k[lowered 2] and B being antiparallel to k[lowered 1] x k[lowered2] for line 3 ( 1(1/2)(1/2)> -> 1(3/2)-(1/2)> -> 1(1/2)(1/2)> ) and line 4 ( 1(1/2)-(1/2)> -> 1(3/2)-(1/2)> -> 1(1/2)-(1/2)> ) were observed to be 9.8% and 21.3% respectively. Line 3 indicates a constructive interference when B is antiparallel to k[lowered 1] x k[lowered 2], and a destructive interference when B is parallel to k[lowered 1] x k[lowered 2], whereas the sign of interference is reversed for line 4. These observations, though the magnitude of interference for line 3 was slightly smaller than the prediction, agree with the theory developed by Lee and Goodman.

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