Measurements of Gamow-Teller strength distributions in masses 13 and 15

The differenctial cross section and the transverse spin-flip probability have been measured for the dominant transitions in /sup 13/C(p,n) /sup 13/N and /sup 15/N(p,n) /sup 15/O at E/sub p/ = 160 MeV. The Gamow-Teller transition strengths deduced from the data show that the major (1/2)/sup -/..-->..(3/2)/sup -/ transitions are strongly quenched relative to the (1/2)/sup -/..-->..(1/2)/sup -/ mirror transitions, in strong disagreement with simple shell-model expectations.