No abstract

Electron beams with the lowest, normalized transverse emittance recorded so far were produced and confirmed in single-bunch-mode operation of the Accelerator Test Facility at KEK. We established a tuning method of the damping ring which achieves a small vertical dispersion and small x-y orbit coupling. The vertical emittance was less than 1% of the horizontal emittance. At the zero-intensity limit, the vertical normalized emittance was less than 2.8 x 10(-8) rad m at beam energy 1.3 GeV. At high intensity, strong effects of intrabeam scattering were observed, which had been expected in view of the extremely high particle density due to the small transverse emittance.

Design Calculations for the An injector of an electron linear accelerator has been modified at ISIR of Osaka University in order to increase a single bunch charge from 14 nC to 60 nC. A 6th subharmonic prebuncher has been replaced with two 12th subharmonic prebunchers and a 6th subharmonic prebuncher which are newly constructed.A one-dimensional disk model has been used to calculate the bunching of the beam and to decide the optimum location of the subharmonic prebunchers.The subharmonic prebunchers are immersed in a solenoidal magnetic field so that the electron beam is confined during the travel through the drift region.The single bunch of 16 -20 ps duration and up to 67 nC in charge, with the energy spread of 0.7 -2.5 % over the range of 24 -34 MeV, and a repetition rate from a single shot to 720 pps can be obtained.The energy spread depends on the charge and the minimum spread is 0.7 % at 33 nC.The single bunch of 25 -45 nC in charge is used for the experiments in routine work.

No abstract