Laser-wire at the ATF extraction line: Progress report

1
Laser-wire at the ATF extraction lineProgress
report

• UK collaborators
• Laser-wire principle
• Progress on the ATF laser-wire
• Future plans

• Nicolas Delerue,
• University of Oxford for the Laser Based Beam
  Diagnostic collaboration

2
People and institutes involvedin laser-wire
activities in the UK

• University of OxfordNicolas Delerue, Brian
  Foster, David Howell, Armin Reichold
• Royal Holloway University LondonIlya Agapov,
  Grahame Blair, Gary Boorman, John Carter, Chafik
  Driouichi, Michael Price, Thorsten Kamps (now at
  BESY)
• University College LondonStewart Boogert, Steve
  Malton
• We acknowledge great help from DESY, KEK and SLAC.

3
How does a laser-wire work?

• A laser-wire uses a high power laser to shoot
  short laser pulses on a particle beam.
• A movable mirror is used to "scan" the beameach
  laser pulse is deflected by the mirror with a
  different angle.
• When the pulse hits a bunch of electrons, Compton
  photons are produced.
• A calorimeter is installed downstream after a
  bend in the electrons trajectory.
• This distribution of the energy gives the beam
  profile.
• From the beam profile, it is possible to exctract
  the size of the electron beam.

Laser wavelength 532 nm (NdYAG) Laser power
1MW_at_PETRA 1GW_at_ATF
4
This years plans for the ATF extraction line
laser-wire

• March 2005study trip Understand the possible
  setup optics/infrastructure, prepare our DAQ,
  study the laser,
• May/June 2005Laser measurements, study the beam
  optics, validate the DAQ
• Summer/September 2005Install the laser
  transport and delivery (Optics, Scanning,),
  install our vacuum vessel at the ATF and final
  focusing lens
• November/December 2005Laser-wire run
• Our latest plans for our work at the ATF are
  posted at
• http//www-pnp.physics.ox.ac.uk/delerue/laserwire
  /atf.php

5
Results from this trip

• The APD has been validated but another detector
  may better suit our needs
• Some preliminary tests have been done for the
  DAQ.
• A design is ready for the laser delivery and
  diagnostics optics.
• Better idea of the beam jitter (thanks to the
  nanoBPM group).
• Learned a lot about the laser and the ATF timing
  system (thanks to the Compton e group and
  Naito-san).
• Lots of discussion on the vacuum vessel design
  and the lens design (still need to finalize the
  discussions)
• Need for more work on the electron beam optics
  has been uncovered.

6
APD signal at the Compton IP

• After some alignment we observed signal in the
  APD when inserting the screens located near the
  Compton IP.
• Signal seen with Y screen but no with X
  screens (not installed).

7
Wire scan with the APD and our DAQ

• Beam profile with our system (not great yet)

8
Future plans

• Our goal is to perform our first scan by the end
  of the year but
• There is still a lot of work to be done
• Electron beam optics and diagnostics
• Vacuum vessel
• Lens design
• Laser delivery and diagnostics (scheme proposed
  this week)
• DAQ
• Put everything together
• We would like to thank people from the ATF and
  from SLAC for their help and their support