Spin flip transitions in 13C and 19F probed with the (π-, γ) reaction
Abstract
Photon spectra from radiative capture of stopped negative pions captured by 13C and 19F nuclei have been measured with a high resolution pair spectrometer. In the bound region transitions have been observed to 13B(g.s.), 13B(3.5 MeV), 19O(g.s.), 19O(4.9 MeV), and 19O(6.3 MeV). In addition, strong transitions to narrow states above the neutron separation threshold were observed in both cases. The results for 13C are in agreement with detailed shell model calculations of this process. Major strength is observed for states formed by coupling extra nucleons or holes to the spin-quadrupole d52 and d32, Jπ=2- states in 16O. The 13C(π-, γ)13Bg.s. branching ratio is shown to be consistent with beta decay and electroexcitation data, through a combined phenomenological analysis. The observed transition strengths are accounted for by matrix elements of the spin-density operators [σ×Y0]1t+ and [σ×Y1]2t+. NUCLEAR REACTIONS 13C(π-, γ), 19F(π-, γ) measured normalized I(Eγ) deduced upper limit on δ(E2M1) for 13C-->13B(g.s.) at q=125 MeV/c, systematics of SIGDR in 12<=A<=20. Stopped π- pair spectrometer; 850 keV at 129.4 MeV.
- Publication:
-
Physical Review C
- Pub Date:
- April 1983
- DOI:
- 10.1103/PhysRevC.27.1621
- Bibcode:
- 1983PhRvC..27.1621M