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

Abstract

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 $$\alpha $$ -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.