Measurement of equilibrium beam polarization in the KEKe+estorage ring TRISTAN

Abstract
The equilibrium polarization of the electron spin has been measured at the TRISTAN electron-positron storage ring. The measurement was carried out by using a laser polarimeter detecting an asymmetry in the Compton scattering of a circularly polarized laser beam on polarized electrons. The laser polarimeter allows for simultaneous measurements of the transverse and longitudinal polarization with sufficient accuracy. The polarization level was relatively high, 40% at an electron-beam energy of 29 GeV, and the polarization vector was inclined at an angle of about 30°.