MEASUREMENT OF G-FACTORS IN YB-170, YB-172 AND YB-174 BY TRANSIENT FIELD INTERACTION AT HIGH RECOIL VELOCITIES

A beam of 40Ca ions at 168 MeV has been used to Coulomb excite high-spin states in 169Tm and 170, 172, 174Yb which recoiled through thin polarized iron at ν/c ≈ 3.5%. An enhanced transient field ≈ 6 times larger than the Lindhard-Winther prediction was observed and calibrated against the known g-factors in 169Tm. Individual g-factors could not be extracted because of strong feeding; nevertheless, deviations from rotational behaviour (constant g-factors) would be detectable. Empirical fits to microscopic calculations of the rotational g-factors below spin 12+ suggest that if deviations from the simple rotational formula occur, they should be of the form g(J) = g0(1 + αJ2). We find the following values in 170, 172, 174Yb: α × 103 = -0.5±1.5, +1.0±1.5. The uncertainties are the level at which deviations from rotational behaviour are expected to occur. The results are discussed in terms of Coriolis anti-pairing effects. © 1979.