Experimental evidence for low-lying quadrupole isovector excitation of ${}^{208}$Po

We present the results from an experiment dedicated to measure the lifetime of the 2${}_2^{+}$ state, candidate for the one-phonon mixed-symmetry state, of ${}^{208}$Po. This nucleus was studied in the α-transfer reaction ${}^{204}$Pb(${}^{12}$C,${}^8$Be)${}^{208}$Po and the lifetime of the 2${}_2^{+}$ state was determined by utilizing the Doppler-shift attenuation method. The experimental data show that the 2${}_2^{+}$ state decays with a sizable M1 transition to the 2${}_1^{+}$ state revealing its isovector nature.