Abstracts Brochure - CERN

WEPLS054
WEPLS055
28-Jun-06 16:00 - 18:00 WEPLS — Poster Session
for visible lights, which are prepared in a factory, can be used for a long time without vacuum breaking. Since a
load-lock system for forming a new high QE film is not needed, the cartridge-type RF gun becomes compact. We
are going to introduce this cartridge-type system to our linac with the BNL-GUN-IV RF gun this summer. Now,
we are calculating the gun parameters of the transmission cavity which has a back plate with a center hole 8mm in
diameter with SUPERFISH and simulating the beam dynamics after modifying the beam line to install the system
with PARMELA. We aim to use reliable Mg and high-QE Cs2Te and try diamond and Ag-Cs-O for radiation chemistry
applications. The detailed numerical design and construction will be presented.
Higher-order Effect Compensation in Magnetic Compressor for < 50 fs Electron Bunch
Generation
An ultrashort electron bunch is essential
K. Kan, T. Kondoh, J. Yang, Y. Yoshida (ISIR)
for pulse radiolysis, which is a pump-probe
measurement based on an ultrashort electron
beam and an ultrashort light. In Osaka University, a laser photocathode electron linear accelerator with a magnetic
compressor has been constructed for the femtosecond electron bunch generation. An electron beam with bunch
length of 98 fs was successfully generated and used in pulse radiolysis. However, an electron beam with bunch length
of < 50 fs is required for development of pulse radiolysis with time resolution of 100 fs. To generate such a short
bunch, higher order disadvantage effects, which are caused by the fringing fields of the magnets in the compressor,
should be compensated. In this paper, a compensation technique of higher-order effects was proposed by using a
nonlinear energy modulation in the bunch produced in the linear accelerator by re-phasing the linac away from the
zero-crossing of the rf (i.e., away from the linear slope). In the simulation, we compressed the electron bunch into 48
fs at bunch charge of 0.1 nC.
Development of Double-decker Electron Beam Accelerator for Femto/attosecond Pulse Radiolysis
The study of electron-induced reactions in
Y.K. Kuroda, T. Kondoh, J. Yang, Y. Yoshida (ISIR)
femto/attosecond time region is very important
for the next electron beam nanofabrication.
Pulse radiolysis with time resolution of sub-picosecond, as a powerful method to study such reactions in
materials, has been developed by using radio-frequency electron accelerators and ultrashort lasers. In Osaka University,
a new concept of double-decker electron beam accelerator is proposed for opening next pulse radiolysis on
femto/attosecond time scale. The double electron beams with time delay of 1.4ns (350ps x 4) and bunch charge of
0.5-0.6 nC were generated in a photocathode electron accelerator by injecting two laser pulses into the photocathode.
The beam energy of the two beams was 31.7MeV. The transverse normalized emittance was 3∼6 mm-mrad for both
the beams. The front of them is converted to Cherenkov light and used as a probe light source, and the back is used
as a pump source. Both electron pulses are generated by one accelerator, resulting in no time jitter between the pump
electron bunch and the probe laser pulse.
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