Gamow-Teller transitions from unstable $^{34}$P to $^{34}$Si via the ($^{7}$Li,$^{7}$Be+$\gamma )$ reaction in inverse kinematics*

Although charge-exchange reactions at intermediate energies with a variety of probes on stable nuclei have long been the preferred tool to extract Gamow-Teller strengths beyond the Q-value window available for $\beta$-decay, the implementation of such reactions for rare isotopes has proven to be an experimental challenge. Here, we report on the first successful extraction of a $\beta $+ Gamow-Teller strength distribution from a radioactive isotope in an intermediate-energy charge-exchange experiment in inverse kinematics. The ($^{7}$Li,$^{7}$Be+$\gamma )$ reaction at 100 AMeV was used to measure Gamow-Teller transition strengths from $^{34}$P to states in $^{34}$Si. The results show that little mixing occurs between sd and pf shell configurations for the low-lying 0$^{+}$ and 2$^{+}$ states even though $^{34}$Si neighbors the island of inversion and low-lying intruder states exist.