NucleargFactors of the First Excited2+States in Samarium-152 and -154 and Gadolinium-156, -158, and -160

The nuclear $g$ factors of the Coulomb-excited $2^{+}$ rotational states in samarium-152 and -154 and gadolinium-156, -158, and -160 have been measured using the pulsed-beam technique. The precession of the excited nuclei in an external magnetic field was detected by observing the angular distribution of the deexcitation $\gamma$ radiation as a function of time. The measured $g$ factors and mean lives $\tau$ were $g=0.277\mathrm{}\pm 0.028$ and $\tau =2.12\mathrm{}\pm 0.07$ nsec for the 122-keV state in ${}_{}{}^{152}{}_{}{}^{}\mathrm{Sm}$, $g=0.288\mathrm{}\pm 0.029$ and $\tau =4.37\mathrm{}\pm 0.07$ nsec for the 82-keV state in ${}_{}{}^{154}{}_{}{}^{}\mathrm{Sm}$, $g=0.296\mathrm{}\pm 0.018$ and $\tau =3.29\mathrm{}\pm 0.08$ nsec for the 89-keV state in ${}_{}{}^{156}{}_{}{}^{}\mathrm{Gd}$, $g=0.315\mathrm{}\pm 0.025$ and $\tau =3.69\mathrm{}\pm 0.08$ nsec for the 79-keV state in ${}_{}{}^{158}{}_{}{}^{}\mathrm{Gd}$, and $g=0.303\mathrm{}\pm 0.026$ and $\tau =3.92\mathrm{}\pm 0.08$ nsec for the 75-keV state in ${}_{}{}^{160}{}_{}{}^{}\mathrm{Gd}$. For ${}_{}{}^{152}{}_{}{}^{}\mathrm{Sm}$ the precession was measured as a function of target temperature in order to understand better the internal field at the nucleus. It was found that the internal field did not have the theoretically expected temperature dependence above room temperature. The samarium results were obtained by using samarium metal targets, which were noticeably perturbed by electric quadrupole interactions. The gadolinium experiments utilized liquid-metal targets, and no perturbations were observed.