Asymmetry parameters in 183W and 182W using MICE detection with a crystal monochromator

Using exceptionally high intensity Moessbauer sources (∼ 1-100 Ci) of 182Ta and 183Ta, the authors have measured the Moessbauer effect for the 46.5 and 99.1 keV transitions of 183W and the 100.1 keV transition of 182W. Using a microfoil internal conversion electron detector capable of operation at low temperatures, and a LiF crystal monochromator, effects of nearly 600% for the 46.5 keV transition and 3 1/2% and 6% for the other two cases are obtained, while standard transmission measurements typically yield much smaller signal-to-background ratios. With this technique the authors have measured the asymmetry term in the conversion electron spectra. (Auth.)