The static electric quadrupole moments of the first excited states of 144, 146, 148, 150Nd

Abstract

Abstract From the relative yield of γ-rays deexciting the 2 + first excited states of 144, 146, 148, 150 Nd following Coulomb excitation by helium, oxygen and sulfur ions, it has been possible to measure the relative static quadrupole moments of these states. Ratios of the γ-ray yields for different projectiles were compared with the calculations of a Coulomb excitation coupled channels computer code. Absolute quadrupole moments of +0.03 ± 0.21, −0.63 ± 0.10 and −1.24 ± 0.14 e · b were obtained for 144, 146, 148 Nd, respectively, if the rotational value of −1.48 e · b is assumed for the quadrupole moment of 150 Nd. Best agreement with the quadrupole moments of 144, 146, 148 Nd measured by Crowley 1 ) is obtained assuming Q 2+ = −2.00 ± 0.51 e · b for 150 Nd. Corresponding to this value for 150 Nd, the quadrupole moments for 144, 146, 148 Nd are −0.07 ± 0.15, −0.78 ± 0.09 and −1.46 ± 0.13 e · b, respectively. A comparison with previously published data on the quadrupole moments for neighboring nuclei shows a smooth increase in the magnitude of the (negative) quadrupole moments of the first 2 + states as one adds pairs of neutrons or neutron holes to the closed neutron shell at N = 82. The static quadrupole moments for 148 Nd and 150 Nd exceed the rotor value, derived from the B (E2, 0 + → 2 + ), by about 37 %. Similar results have been observed in previous reorientation measurements on rotational nuclei and are not understood at the present time.