• Y. Shoji
  LASTI, Hyogo

　Sub-THz coherent synchrotron radiation (CSR) from the SPing-8 linac beam was observed after the injection into the NewSUBARU storage ring. The beam from the linac has much sorter bunch length than the stationary stored bunch in the ring. It had been reported that the injected linac beam emits CSR at just after the injection until it diluted to a longer bunch by its energy spread. However we observed CSR at after more revolutions. At some tens of microseconds after the injection we observed CSR produced by a fine time structure in a bunch. At after more revolutions, a half of the synchrotron oscillation period (0.1 ms), CSR was back because the bunch length became shorter again. At this timing we also expect CSR emitted from a structure produced by longitudinal and transverse coupling, which should depend on the chromaticity. We report results of CSR observation through these periods.

• K. Takeda, Y. Shoji
  LASTI, Hyogo

The emittance of a single-shot beam from the SPring-8 electron linac was measured. A stability of the linac beam was evaluated from the shot-by-shot fluctuation of the emittance. We used the electron storage ring NewSUBARU as a part of the measurement system. The electron beam from the linac was injected into the ring and circulated. The beam profile was measured by a fast-gated ICCD camera using the visible light in the ring. Because of the intentional dipole injection errors, the beam position oscillated after the injection in vertical and horizontal directions. It enabled a multi-record of turn-by-turn beam profiles in one camera frame. The profiles for several revolutions were used to reconstruct the emittance of the linac beam. The horizontal and the vertical betatron tunes were optimized for the emittance measurement because the beam storage was not necessary. We compared the results with that by Q-scanning at the beam transport line, which required multi-shot beam.