Radiation Effects of Protons on Samarium-Cobalt Permanent Magnets

At TRIUMF the use of samarium-cobalt permanent magnet quadrupoles as the first element in a secondary channel has been studied as a means of increasing the solid angle acceptance of the channel. The high remanent induction Br and high coercive force Hc of rareearth cobalt (REC) can be utilized to produce a high-gradient quadrupole field in an extremely compact magnet. Although many properties of REC material have been measured, little is known about the effect of charged particle radiation on the magnetic behaviour. As the TRIUMF application requires the magnets to operate in a high radiation environment it was considered essential to study this effect. This paper describes the results of exposing samples of samarium-cobalt and other permanent magnet materials to a beam of protons.