High Duty Cycle, Tagged and Polarized Photon Beam from 1.3 GeV Electron Synchrotron

A new tagged-photon beam channel is under construction at the electron synchrotron laboratory of Institute for Nuclear Study, University of Tokyo. In this channel, the duty cycle of the extracted electron beam is expected to be 20% so that the effective tagged-photon intensity will be as high as 2 × 106 photons/second. To obtain the high-duty-cycle beam, magnetic fields of the components in the beam extraction system and in the beam transport system are modulated so as to follow the change of the magnetic field of the synchrotron. By introducing a largeacceptance spectrometer for the experiments with the tagged photon beam, the data-taking efficiency will be markedly improved. These high-duty beam will enable us to perform the experiment with the tagged and polarized photon beam by using a single crystal for the radiator material in the tagging system.