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Abstracts Brochure - CERN

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WEPLS054<br />

WEPLS055<br />

28-Jun-06 16:00 - 18:00 WEPLS — Poster Session<br />

for visible lights, which are prepared in a factory, can be used for a long time without vacuum breaking. Since a<br />

load-lock system for forming a new high QE film is not needed, the cartridge-type RF gun becomes compact. We<br />

are going to introduce this cartridge-type system to our linac with the BNL-GUN-IV RF gun this summer. Now,<br />

we are calculating the gun parameters of the transmission cavity which has a back plate with a center hole 8mm in<br />

diameter with SUPERFISH and simulating the beam dynamics after modifying the beam line to install the system<br />

with PARMELA. We aim to use reliable Mg and high-QE Cs2Te and try diamond and Ag-Cs-O for radiation chemistry<br />

applications. The detailed numerical design and construction will be presented.<br />

Higher-order Effect Compensation in Magnetic Compressor for < 50 fs Electron Bunch<br />

Generation<br />

An ultrashort electron bunch is essential<br />

K. Kan, T. Kondoh, J. Yang, Y. Yoshida (ISIR)<br />

for pulse radiolysis, which is a pump-probe<br />

measurement based on an ultrashort electron<br />

beam and an ultrashort light. In Osaka University, a laser photocathode electron linear accelerator with a magnetic<br />

compressor has been constructed for the femtosecond electron bunch generation. An electron beam with bunch<br />

length of 98 fs was successfully generated and used in pulse radiolysis. However, an electron beam with bunch length<br />

of < 50 fs is required for development of pulse radiolysis with time resolution of 100 fs. To generate such a short<br />

bunch, higher order disadvantage effects, which are caused by the fringing fields of the magnets in the compressor,<br />

should be compensated. In this paper, a compensation technique of higher-order effects was proposed by using a<br />

nonlinear energy modulation in the bunch produced in the linear accelerator by re-phasing the linac away from the<br />

zero-crossing of the rf (i.e., away from the linear slope). In the simulation, we compressed the electron bunch into 48<br />

fs at bunch charge of 0.1 nC.<br />

Development of Double-decker Electron Beam Accelerator for Femto/attosecond Pulse Radiolysis<br />

The study of electron-induced reactions in<br />

Y.K. Kuroda, T. Kondoh, J. Yang, Y. Yoshida (ISIR)<br />

femto/attosecond time region is very important<br />

for the next electron beam nanofabrication.<br />

Pulse radiolysis with time resolution of sub-picosecond, as a powerful method to study such reactions in<br />

materials, has been developed by using radio-frequency electron accelerators and ultrashort lasers. In Osaka University,<br />

a new concept of double-decker electron beam accelerator is proposed for opening next pulse radiolysis on<br />

femto/attosecond time scale. The double electron beams with time delay of 1.4ns (350ps x 4) and bunch charge of<br />

0.5-0.6 nC were generated in a photocathode electron accelerator by injecting two laser pulses into the photocathode.<br />

The beam energy of the two beams was 31.7MeV. The transverse normalized emittance was 3∼6 mm-mrad for both<br />

the beams. The front of them is converted to Cherenkov light and used as a probe light source, and the back is used<br />

as a pump source. Both electron pulses are generated by one accelerator, resulting in no time jitter between the pump<br />

electron bunch and the probe laser pulse.<br />

348

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