Abstracts Brochure - CERN

WEPLS029
WEPLS030
WEPLS031
28-Jun-06 16:00 - 18:00 WEPLS — Poster Session
Monoenergetic 200fs (FWHM) Electron Bunch Measurement from the Laser Plasma Cathode
A. Maekawa, T. Hosokai, K. Kinoshita, K. Kobayashi, T. Ohkubo, T.
Tsujii, M. Uesaka (UTNL) Y. Kondo, Y. Shibata (Tohoku University)
T. Takahashi, A. Yamazaki (KURRI) A.G. Zhidkov (NIRS)
340
A laser plasma accelerator is the most
promising approach to compact accelerators
that can generate femtosecond electron
bunches. It is expected that the electron
bunch duration less than 100fs can be
achieved owing to the high frequency of plasma waves. Since the time-resolution of the fastest streak camera is only
200fs, we have to use the coherent transition radiation (CTR) measurement or E/O (electro-optical) method. We plan
to perform a single-shot measurement by getting the whole CTR spectrum by a IR polychromator in near future.
As the first step forward it, we used a IR bolometer with different filters and obtained the average spectrum. We
can generate monoenergetic electron bunches in the condition of laser intensity 3x1019W/cm2 and electron density
6x1019cm-3. The charge is estimated to be about 10pC using ICT (Integrated Current Transformer). The electron
bunch accelerated by plasma waves penetrates 300um Ti-foil, and transition radiation is emitted. We measure CTR
spectrum using a bolometer. Spectrum distribution of CTR depends on the electron bunch distribution, therefore we
can evaluate the bunch duration from it. In the experiment, bunch duration can be estimated.
LEPTA Ring Commissioning
A.O. Sidorin, I.N. Meshkov, I.A. Seleznev, A.V. Smirnov, G.V. Trubnikov
(JINR)
Abstract The project of Low Energy Particle
Toroidal Accumulator (LEPTA) is dedicated
to construction of a positron storage ring with
electron cooling of positrons circulating in
the ring. Such a peculiarity of LEPTA enables it automatically to be a generator of positronium (Ps) atoms, which
appear in recombination of positrons with cooling electrons inside the cooling section of the ring. The project has
a few goals: 1) Dynamics in the modified betatron; 2) Electron cooling of positrons; 3)Positronium generation in
flight; 4) Positronium physics; 5) Feasibility of antihydrogen generation in flight; 6) Electron cooling with circulating
beam An assembling of the storage ring LEPTA is completed. Peculiarity of the storage ring is focusing circulating
particles by longitudinal magnetic field which covers whole orbit. As result, the particle motion in the ring is coupled
in transverse plane. First results of the experimental study of the particle dynamics in the ring performed with
circulating electron beam are presented. The beam life time was achieved about 20 ms at electron energy of 4 keV
and vacuum pressure of 30 nTorr. The limitations of the beam life time and the possibility of
This work is supported by RFBR grant #05-02-16320 and INTAS grant #03-54-5584.
First Beam of Slow Positrons for LEPTA
An injector of the monochromatic positrons
S. Yakovenko (JINR)
for accumulator LEPTA is being tested at
JINR. The positron injector is based on 22Na
radioactive source. Positrons from the source are moderated in the solid target. Solid neon is chosen as moderator.
For this goals the cryogenic system of the source and neon feed line has been constructed. The low energy positron
registration method has been tuned. The first experiments with the solid moderator have been performed.