Study of the Decay Parameters and Magnetic Moment of theΞ−

Abstract

This paper describes an experimental study of the decay parameters and the magnetic moment of the ${\Xi }^{-}$. A 1.8-GeV/c $K^{-}$ beam derived from the Bevatron was used to produce ${\Xi }^{-}$ by the reaction $K^{-}p\to {\Xi }^{-}{K}^{+}$. The $K^{+}$ and resulting decay products of the ${\Xi }^{-}$ were used to trigger a spark-chamber system, pictures from which yielded a total of 2724 events which passed all measuring criteria. The ${\Xi }^{-}$ were produced in an intense (170 kG) magnetic field obtained from a pulsed magnet. The precession of the magnetic moment of the ${\Xi }^{-}$ in the presence of this field can be measured from the angular distribution of the ${\Xi }^{-}$ decay products and a value of the magnetic moment obtained. The decay parameters and polarization of the ${\Xi }^{-}$ are also obtained from the angular distribution of the decay products; we obtain $\alpha =-0.383\mathrm{}\pm 0.065$, $\Phi =-(26\mathrm{}\pm 30)°$, and $\overline{P}=0.19\mathrm{}\pm 0.09$. The accuracy of the magnetic moment value is severely limited by the low value of polarization and experimental biases in the distribution; we obtain ${\mu }_{{\Xi }^{-}}=-0.1\mathrm{}\pm 2.1$ nuclear magnetons.