Nuclear Moments of Secondary Beams from a Recoil Mass Spectrometer.

Static magnetic dipole and electric quadrupole moments of nuclear isomers were measured using secondary beam techniques. The isomers were produced by heavy-ion fusion evaporation reactions and formed into secondary beams by the Rochester recoil mass spectrometer. These isomer beams were oriented and stopped in a perturbing environment. Perturbed angular distributions of the isomers' decay radiations were observed to extract the nuclear moments. Three distinct studies were made using variations of this general technique. The preservation, following separation by the RMS, of reaction-induced nuclear alignment for Ar-like ^{69}Ge and Ne-like ^{54}Fe ions was established. The degree of alignment observed is estimated to be roughly 25% of the initial alignment. Electric quadrupole moments of polarized ^{92}Mo(8 ^+) and ^{93 }Ru(21/2^+) isomers were measured. The sign of Q_{92_ {rm Mo}} was found to be negative, indicating that the state is of a proton particle rather than hole character. Q_{93_ {rm Ru}} was found to be +0.03(1)b. This result is consistent with the isomer's small B(E2,21/2 ^+to 17/2^+) but is not well predicted by shell-model calculations. The third experiment, which has not yet been completed, is an application of the beta-NMR technique to a measurement of the magnetic dipole moment of ^{23 }Mg. A preliminary result of |mu_{23_{rm Mg}}| =0.536(13) mu _{rm N} has been obtained.