First operation of 11m long undulator at NewSUBARU

Abstract The synchrotron radiation source NewSUBARU has a long undulator with the total length of 10.8 m and with 200 periods for high-brilliance radiation. Commissioning studies has been performed since February 2000 and recently the first photon spectrum from the undulator was observed. The non-linearity of the magnetic field decreased both the lifetime and injection efficiency with small gap. The observed spectrum was broader than expected because of imperfect trajectory through LU, near-field effect of radiation in addition to beam emittance.