Determination of the Sign of theHe3Nuclear Magnetic Moment

Abstract

EDITOR 837 FIG. 2. Comparison of experimental values of a, f, with theoretical limits, from Larsen, Lubkin, and Tausner. 3 The direct empirical parameters a', £' for p -0.68, p = 0.75 are represented by the little rectangles. The actual parameters a, £ are larger in absolute value because of depolarization effects. The first quadrant applies if the ju's are polarized in the direction back to the parent 7r, the third quadrant if they are polarized opposite to this direction.ratios of (7) are compared as a solid line with experiment in Fig. 1. The contribution of the distribution function uncertainty is indicated by the cross-hatching on the two-component curve. We judge the results to be a rather successful prediction of the two-component theory. Radiative corrections 8 amount to of the order of 1% in this method of analyzing the data. A more quantitative test of the two-component theory may be made by evaluating the additional parameters of the four-component theory. Larsen, Lubkin, and Tausner 3 find, instead of (6), the distributionwhere a and f are the new parameters. The comparison with experiment is made in Fig. 2 which was prepared by these authors. Here too, resolution effects may account for the small deviation from two-component theory.The data permit a determination of ao=%B. Integration of (6) from x=0 to x= 1 gives /(0) = 1 -|a 0 cos#. We find from (5) £B=0.79±0.06.In the two-component theory | £ | < 1 and hence 5>0.80. This is consistent with the two-component prediction that, in the decay T->fx+v, the muons are formed in a state of complete polarization. Independent of the two-component theory, the observation of P/V>3 (Fig. 1) and the restriction |a|<l in (1) leads to B> 0.50. Phys. Rev. 99, 885 (1955). These authors give p = 0.68±0.10. L. Rosenson (to be published). He gives p = 0.67±0.05. K. Crowe (private communication). He obtains p = 0.68±0.02. These p values exclude the ix->e-\-2v and fx->e-}-2v versions of two-component theory. 8 Berhrends, Sirlin, and Finkelstein, Phys. Rev. 101, 866 (1956); T. Kinoshita and A. Sirlin, Phys. Rev. (to be published); T. Kinoshita (private communication).W E have made a direct comparison between the signs of the proton and the He 3 nuclear magnetic moments. The result is that the proton and He 3 have nuclear magnetic moments of opposite sign. Since the sign of the proton moment is known to be positive, 1 the He 3 moment is therefore negative as predicted 2 from the odd neutron configuration and previously inferred from optical hyperfme spectra data. 3 1/ .,.; j FIG. 1. Nuclear induction dispersion derivative signals of H 1 and He 3 .

Explorations of Magnetic Properties of Noble Gases: The Past, Present, and Future

“…This outstanding nucleus has its mirror analog in the tritium nucleus. The nuclear spin of helium-3 (triton) was determined from the intensity alternation in the band spectrum of the helium dimer [31]; the sign of the 3 He nuclear magnetic moment is opposite to that of the proton [32]. Over the last seventy years, several attempts have been made to precisely determine the 3 He nuclear magnetic moment.…”