First production of intense circularly polarized hard x rays from a novel multipole wiggler in an accumulation ring

A novel multipole wiggler and an associated beam line have been installed in the accumulation ring for the TRISTAN project at the National Laboratory for High Energy Physics (KEK). An intense source of circularly polarized synchrotron radiation in the energy ranging 40 to 80 keV has been achieved for the first time. A degree of circular polarization, ${\mathrm{P}}_{\mathrm{c}}$≃0.7, at 60 keV of photon energy was in good agreement with a theoretical prediction in the 6-GeV operation of the accumulation ring.