Products of stopped-pion interactions with Cu and Ta

Abstract

Yields of radioactive products from the interactions of stopped ${\pi }^{-}$ with Cu and Ta have been measured. Absolute yields of products ranging down to ${10}^{-5\mathrm{}}$ per stop were determined. The experimental yields are compared with yields calculated with a model that was developed in this work for the stopped-${\pi }^{-}$ interaction. The calculations give excellent agreement with measured total mass yields for Ta, but some discrepancies exist for the independent yields of Hf, Er, and Tm isotopes; in the case of Cu, most independent yields, except for Co and Sc, are in good agreement. Measurements were also made with both stopped ${\pi }^{-}$ and 20-MeV ${\pi }^{+}$ on Cu and Fe to determine the shift in the centroids of the isotopic yields with pion charge.