P 34 ( Li 7 , Be 7 + γ ) Reaction at 100 A MeV in Inverse Kinematics

We report on the first successful extraction of a ${\ensuremath{\beta}}^{+}$ Gamow-Teller strength distribution from a radioactive isotope in an intermediate-energy charge-exchange experiment in inverse kinematics. The ($^{7}\mathrm{Li},^{7}\mathrm{Be}+\ensuremath{\gamma}(429\text{ }\text{ }\mathrm{keV})$) reaction at $100A\text{ }\text{ }\mathrm{MeV}$ was used to measure Gamow-Teller transition strengths from $^{34}\mathrm{P}$ to states in $^{34}\mathrm{Si}$. The results show that little mixing occurs between $sd$ and $pf$ shell configurations for the low-lying ${0}^{+}$ and ${2}^{+}$ states even though $^{34}\mathrm{Si}$ neighbors the island of inversion and low-lying $2\ensuremath{\hbar}\ensuremath{\omega}$ intruder states exist. Shell-model calculations in the $sdpf$ model space are consistent with these findings.