The absorption of $\pi^{-}$ at rest on complex nuclei

The energy, width and intensity of prompt nuclear gamma -rays following capture of pi /sup -/ at rest by /sup 9/Be, /sup 10/B, /sup 16/O, /sup 19/F, /sup 31/P, Ca and /sup 93/Nb were measured with a Ge (Li) detector. In most cases it was possible to identify the final nucleus from the energy of the observed gamma -ray. Using the measured Doppler broadening of gamma -rays from short-lived states, the vector sum momentum distribution of the emitted nucleons was calculated. From the measured gamma -ray intensities, isotopic yields were deduced corresponding to the removal of from 1 to 12 nucleons. The average number of removed nucleons changes from 3.0 to 5.5 as the target varies from /sup 16/O to /sup 40/Ca. A comparison was made with data from both spallation reactions and multi-nucleon pick up reactions. (40 refs).