Evidence for the first 9/2+state inBr75and maximum deformation atN∼42

Evidence for the first 9/$2^{+}$ state in ${}_{}{}^{75}{}_{}{}^{}\mathrm{Br}$ at 694 keV has been obtained through the ${}_{}{}^{75}{}_{}{}^{}\mathrm{As}$ (55 MeV $\alpha ,4n$) reaction. This result shows a sharp change in the systematics of the 9/$2^{+}$ states in the Br isotopes and implies that the maximum of prolate deformation is reached for $N\sim 42$. The previously postulated correlation between 9/$2^{+}$ and $2^{+}$ states in the neighboring even-even nuclei is confirmed by the present experiment.