Measurement of the Magnetic Moment of theΛ0Hyperon

Abstract

A measurement of the magnetic moment of the ${\Lambda }^0$ hyperon carried out at the Brookhaven Cosmotron gives the value ${\mu }_{{\Lambda }^0}=-1.5\mathrm{}\pm 0.5$ Bohr nucleon magnetons. Polarized ${\Lambda }^0$ hyperons were produced by 1.02±0.03 BeV/c ${\pi }^{+}$ mesons incident on a Be target in the reaction ${\pi }^{+}+n\to {\Lambda }^0+K^{+}$. After passing through a strong magnetic field, the ${\Lambda }^0$ were observed to decay in a parallel plate spark chamber which was triggered by an electronic counter logic. The asymmetry of the ${\pi }^{-}$ from the decay ${\Lambda }^0\to {\pi }^{-}+p$ provided the method for determining the axis of polarization. The magnetic field and flight path were such that a magnetic moment of one Bohr nucleon magneton would precess 16.5° in a plane perpendicular to the ${\Lambda }^0$ trajectory. Measurement of the angle of rotation of the decay pattern with field on, off, and reversed gave the magnitude of the moment; the sense of rotation yielded the sign.