A new measurement of the magnetic moment of the Δ-hyperon

The magnetic moment of the Δ-hyperon has been measured by observing the precession of the polarization vector of Δ-particles in a transverse pulsed magnetic field of 20 T (= 200 kG). The hyperons were produced in a polyethylene target by the reaction π−+p→+Δ+K0 at a pion momentum of 1.05 GeV/c; their decays were detected in stacks of nuclear emulsion at a distance of 11 em from the centre of the target. The angular distribution of the decay products in the rest frame of the Δ was used to determine the direction of the polarization at the time of the decay, and hence the magnetic moment. About 1300 Δ decays have been analysed, giving the result\(\mu _\Lambda = - 0.66\mu _{\mathcal{N}}\) (nuclear magnctons) with a statistical uncertainty of\( \pm 0.06\mu _{\mathcal{N}}\). The systematic error is less then\( \pm 0.03\mu _{\mathcal{N}}\), so that the total (68% confidence level) error is\( \pm 0.07\mu _{\mathcal{N}}\).