Nuclear Moments of 140La, 147Nd, and 149Nd

Abstract

<p> Using atomic beam magnetic resonance techniques the hyperfine structure (hfs) constants for the magnetic dipole and electric quadrupole interaction, AJ and BJ, have been measured for the following isotopes: 40-hour 140La, 1.8-hour 149Nd and 11-day 147Nd.</p> <p> For 140La the hfs constants are (relative to the J = 5/2 state of 2D) |A5/2| = 55.9(4) MHz, |B5/2| = 38(4) MHz, B5/2/A5/2 > 0. Application of the Fermi-Segre relations in comparison with 139La yields the nuclear moments; μI = (+)0.73(3) n.m., and Q =(+)0.11(4) b. The adopted signs are based on Blok's measured sign of Q for 140La.</p> <p> For 149Nd the hfs constants are: |A4| = 91.0(19) MHz, |B4| = 266(53) MHz, and B4/A4 > 0. Comparison with 145Nd yields μI = (-)0.350(10) nm., and Q = +1.3(3)b. The signs of these moments are based on Q>0 as indicated by nuclear systematics in this region.</p> <p> For 147Nd the hfs constants are |A4| = 143(4) MHz, |B4| = 181(64) MHz, and B4/A4 > 0. Comparison with 145Nd yields |μI| = 0.553(15) n.m., |Q| = 0.9(3) b and μI/Q <0.</p> <p> The error in the 140La magnetic moment allows for a possible 2% hfs anomaly. The quadrupole moments allow for a possible 25% error in the core polarization correction (Sternheimer).</p> <p> These results are discussed in terms of the shell model, the quasi-particle model, and the Nilsson model.</p>