Affiliations: [a] Nuclear Engineering Research Laboratory, Graduated
School of Engineering, University of Tokyo, 2-22 Shirakata-Shirane, Tokai,
Naka, Ibaraki, 319-1188, Japan | [b] High Energy Accelerator Research Organization, 1-1
Oho, Tsukuba, Ibaraki, 305-0801, Japan
Correspondence:
[*]
Corresponding author: Nuclear Engineering Research Laboratory,
Graduated School of Engineering, University of Tokyo, 2-22 Shirakata-Shirane,
Tokai, Naka, Ibaraki, 319-1188, Japan. Tel.: +81 29 287 8473; Fax: +81 29 287
8471; E-mail: koba@tokai.t.u-tokyo.ac.jp
Abstract: For a sub-picosecond pump-and-probe-type radiation chemistry work, a
new synchronized electron linac and laser system was installed in Nuclear
Engineering Research Laboratory (NERL) of University of Tokyo. The new 0.3 TW
laser system with a Ti:Sapphire oscillator (795 nm) and amplifiers generate
300 ps pulses at 10 Hz at first. The laser is splitted into the two beams. The
first is compressed to 4 ∼ 11 ps so as to drive the RF-Gun
and generate a pump-electron-beam. The second is compressed to 100 fs and used
for the probe-light. The drive laser is converted to the third harmonics
(265 nm, < 250 μJ). Moreover, a new 15 MW klystron
was installed for the linac RF system. The RF power is divided to the gun and
the accelerating section. Finally the time jitter between the
pump-electron-beam and the probe-laser is designed to be 320 fs (rms). By using
the new drive laser system, the charge of 7 nC per bunch was observed at the
exit of the gun. Improvement of the vacuum in the
gun < 10^{-9} Torr) is most effective to obtain such a high
charge beam. After two and a half years operation of the gun, no degradation of
QE has been found for the Cu photo-cathode.
