Precision measurement of the magnetic moment of the. sigma. /sup -/ hyperon

The magnetic moment of the ..sigma../sup -/ hyperon has been obtained from measurements of fine-structure splittings of x-ray transitions in ..sigma../sup -/ exotic atoms. The use of targets consisting of sheets of Pb or W immersed in liquid hydrogen, and of a tagging technique utilizing the ..pi../sup +/ emitted in the reaction K/sup -/p..--> sigma../sup -/..pi../sup +/, resulted in improved x-ray signal-to-noise ratio by a factor of 15 over that in previous experiments. The present result is ..mu..(..sigma../sup -/) = (-1.111 +- 0.031 +- 0. 011)..mu../sub N/. .AE