Laser Based Beam Diagnostics
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The aim of the Laser Based Beam Diagnostics (LBBD) Collaboration is to study the feasibility of laser based diagnostics tools for future linear electron positron collider (FLC). The objectives of the laserwire project are to develop laser based techniques for determining the dimensions of electron (positron) bunches in a FLC and optimising their application using simulations.
ATF International Collaboration
The performance of future linear collider depends strongly on the
of the transverse particle beam size along the complete machine, for
example to verify beam optics and to measure the transverse beam
Some of the expected beam sizes are in the range between 500 nm and
10 µm, where conventional wire scanners are at the limit of their
To provide a non-invasive measurement we suggest to use a laser beam
to probe the electron beam. The central idea is to use Compton
scattering between electrons in the bunch and photons in the laser beam
The operation principle of the laserwire is sketched above. A focused laser beam is brought into a 90 degree crossing angle with the electron trajectory and is scanned horizontal and vertical across the electron beam. Compton scattered photons are detected further downstream the beamline with appropriate detectors. Since the number of scattered photons is proportional to the overlap of photon and electron beam, the beam size can be measured.
Until now the laserwire monitor is not a standard tool for the operation of an accelerator. Nonetheless first experiments with a prototype device at SLC (Stanford Linear Collider) showed the exciting opportunities of such a system.
The LBBD Collaboration brings together individuals from all over the globe in order to fully exploit the potential of laser based diagnostics for accelerators. See the list of collaborating people for more details. Below contact persons are listed:
The RHUL task is to inspire and coordinate experimental activities related to the laser system. Issues that will be addressed include
Collaborative activities include the development of an optical cavity laser wire at ATF and the projecting of a combined laser system at SLAC for the Next Linear Collider (NLC).
At RHUL a laserlab will be installed in the near future for the work on the laser system. This opens up unique opportunities for graduate students interested in accelerator/laser physics.
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Content: Grahame Blair