ABSORPTION OF STOPPED PI- IN CO-59, AS-75, AU-197 AND BI-209 INVESTIGATED BY IN-BEAM AND ACTIVATION GAMMA-RAY SPECTROSCOPY

In-beam pionic X-ray and γ-ray spectra and activation γ-ray spectra following π- absorption at rest in 59Co, 75As, 197Au and 209Bi have been measured. The isotopic yield distributions and thus the (π-, xnγp) reaction yields were determined. The mean numbers of emitted neutrons and protons are, respectively, 4.5 ± 0.2 and 1.48 ± 0.16 for 59Co, 5.1 ± 0.3 and 1.02 ± 0.14 for 75As, 6.6 ± 0.4 and 0.32 ± 0.14 for 197Au, and 6.8 ± 0.4 and 0.37 ± 0.16 for 209Bi. The experimental results are compared with a pre-equilibrium exciton model calculation and proton-induced spallation reactions. High spin states in the residual nuclei were observed. For pionic X-rays absolute intensities of various transitions are given. © 1979.