Abstract
The photon spectra in the capture of stopped pions on and were measured in the 50-150-MeV region with a high-resolution pair spectrometer. The total radiative capture branching ratios are 2.13±0.21 and 2.27±0.22%, respectively. The spectrum corresponding to the first 13 MeV excitation in each of the residual nuclei and is dominated by the transition to the analog of a giant state of the target nucleus. The ground state transitions in both nuclei are resolved experimentally. The measured branching ratio for the extremely weak (g.s.) transition is (3±2) × . There is evidence for selective excitation of the analogs of the giant dipole spin-isospin states of , of which the component appears to be the strongest. In the transition strength to the giant resonance region is more fragmented. An analysis is presented that employs an impulse-approximation Hamiltonian with amplitudes taken directly from the fundamental process on the nucleon, , and shell-model wave functions obtained using realistic interactions in the , , and shells. Also, a calculation for the (g.s.) transition from capture using the "elementary-particle soft-pion" ansatz is presented.
NUCLEAR REACTIONS () on and with stopped ; measured photon spectrum (50-150 MeV) and radiative branching ratio using pair spectrometer of 2 MeV resolution. Shell-model calculations compared with measurements.
- Received 9 September 1974
DOI:https://doi.org/10.1103/PhysRevC.12.921
©1975 American Physical Society