Laserwire

1
Laser-wire

• Grahame Blair
• JAI Advisory Board,
• Oxford
• 13th February 2006

• Overview of laser-wire goals.
• Overview of ongoing technical work in this group
• Plans for the future.

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Laser-wire People

• BESSY
• T. Kamps
• DESY
• H. C. Lewin, S. Schreiber, K. Wittenburg, K.
  Balewski
• Oxford
• B. Foster, N. Delerue, S. Dixit, F. Gannaway, D.
  Howell,
• M. Qureshi, A. Reichold, R. Senanayake
• Royal Holloway (UL)
• A.Agapov, G. Blair, S. Boogert, G. Boorman, A.
  Bosco, J. Carter,
• L. Deacon, C. Driouichi, M. Price
• University College London (UL)
• S. Malton
• CCLRC
• I. Ross, L. Jenner
• KEK
• A. Aryshev, H. Hayano, P. Karataev, K. Kubo, N.
  Terunuma, J. Urakawa
• Kyoto
• N. Sasao
• SLAC

Project web page http//www.hep.ph.rhul.ac.uk/lb
bd/
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Three-Prong Hardware Strategy

• LW system at PETRA II
• Storage Ring ?DR style operation
• User Facility
• DAQ development
• ATF Extraction Line system
• Single Shot
• BDS style operation
• Advanced laser scanning RD
• Mode locked systems
• Ultra-fast scanning

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General Strategy
PETRA Develop reliable turnkey diagnostics for
2-d emittance measurements
Blue-skies RD for Ultra-fast scanning
ATF Aim at micron spot-sizes, single-train
measurements
Specify hardware for various ILC locations,
particularly BDS
Laser RD
BDSIM simulations
Working ILC LW Solutions
Machine optics design
Machine tuning strategy
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Laser-wire Principle
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Laserwire for PETRA
PETRA parameter

• Long free straight section
• Easy installation of hardware due to existing
  access pipe and hut outside tunnel area
• Q-switch NdYAG
• From CERN LEP polarimeter
• Trans Mode large M2 9
• Long Mode stability 20, beating ? ps
  substructure
• Homegrown timing unit for external triggering

Laser parameter
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Laserwire for PETRA
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Detector

• Requirements for detector material
• short decay time (avoid pile up)
• short radiation length
• small Moliere radius
• Cuboid detector crystals made of PbWO4
• 3x3 matrix of 18x18x150 mm crystals
• Energy resolution better than 5

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Laserwire - PETRA
UCL
Since then, new hardware installed.
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Structure in the Longitudinal Profile

• Example of a single shot measurement of the
  profile500 ps window, resolution 5 ps

66 ps
T. Kamps, S. Schreiber
60 ps
J. Carter
40 rms from these fluctuations ?move to
injection seeded laser
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Piezo voltage (angle)
Raw cal. signal
500 triggers ? 17 s
µ168.2 4.7 s84.9 5.5
Will improve with injection seeding
S. Malton (UCL)
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C. Driouichi
Construction finished and tests started
Lens characterization TS Calibration Scanning
range Waist measurement
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New PETRA LW Hardware
M. Price

• 2-d scanning system
• Mechanics designed built at Oxford
• Optics electronics tested at RHUL
• Was shipped to DESY in November 2005

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PETRA Laser-wire
New system installed at PETRA in Dec 2006
New laser arrived, but had to be returned
for repairs. PhD student (M. Price) to be based
full time at DESY from Feb06.
R.Senanayake
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PETRA Plans
Up to Apr 07

• M. Price (PhD Student) will be based at DESY from
  Feb 06 to work on 2d-system
• Understand new laser (injection-seeded
• Q-switched) improve trigger/DAQ
• Perform machine studies at PETRA using LW.

Beyond Apr 07 (subject to new funding)

• Transfer LW to new location for PETRAIII
• Perform machine studies using LW.
• Investigate EO scanning techniques at high
  frequency.

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ATF Laser-wire

• At ATF, we will aim to measure micron-scale
  electron spot-sizes
• with green (532 nm) light.
• Aim at intra-train (fast) scan for 150 ns bunch
  spacing.
• The final spot-size measurable
• at ILC will have implications for
• the length and layout of the BDS
• diagnostics section.
• The ATF/ATF2 results will be
• crucial to determine the
• technical boundaries.

pulsed laser-wire location
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ATF-LW Vacuum Chamber
Built at Oxford DO Workshop
Vacuum Tested At DL
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Arrival Installation at KEK

• 3 such crates delivered to KEK
• In October 2005
• Vacuum Vessel
• Mechanical Supports
• Optics
• Electronics
• Tooling and components

Thanks to KEK and SLAC for Logistical advice
Installation and alignment of the vacuum vessel
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ATFInfrastructure supplied by KEK
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(No Transcript)
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ATF laser-wire at the beamline
Inside the optics hut At the beam-line
ATF beamline LW optics hut at beam-line
S. Boogert
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ATF Laser-wire
Vacuum chamber built in Oxford and Installed in
ATF extraction Line in December 2006.
Laser light transported to IP, but no collisions
yet seen probably a detector issue. New run
planned For March 06.
Designing diagnostics insertion at Oxford
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LW Practical Considerations

• f1 geometry is challenging
• Limitations from power
• Limitations from angle
• Surface optical quality
• Alignment tolerance

• f1 Lens design is challenging
• Limitations from power
• Limitations from ghost images
• Alignment tolerance
• Lens currently under construction

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Canidate f/1 Lens Designs
Aspheric doublet
Vacuum window
ZEMAX course held at JAI in January
2006. Expertise and possibilities are expanding
Spheric triplet
N. Delerue et al.
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ATF LW Plans
Up to Apr 07

• Data run in Spring 2006
• More runs 06/07 lots of systematics to
  understand (eg beam jitter, BPM integration )
• Integrate solid wire scanner into vac. vessel
  design
• Iteration on lens design.
• Provide statement to GDE on technical feasibility
  of reliable micron-scale LW

Beyond Apr 07 (subject to new funding)

• Play a major role in ATF2 LW system.
• Develop fast scanning
• Multiple IPs, laser system, light transport.
• Investigate running with UV light.
• Collaborate on Shintake type systems.

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Mode-locked laser-lab

• Major new facility
• Now complete
• Will be used to test ATF LW
• optics
• Will house mode-locked system
• with ILC specs
• International laser meeting at Oxford Jan 30th
  2006 to pool resources and objectives.
• JAI students and RAs will all
• get training at this facility.

D. Howell, G. Quelsh
S. Dixit currently drawing up specs and
contacting vendors for mode-locked laser hardware
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S. Dixit
General observations
As of today, no Fiber system is anywhere close to
our requirement of about 20 MW (100 ?J at 5 ps
at 3 MHz)
Fiber laser expertise, methodology, their tools,
optics, components, etc are completely different
from conventional lasers
Hence the pros and cons are w.r.t. 3 choices,
Choice 1
Conventional laser
MOPA system based on NdYLF/NdYAG
Choice 2

A hybrid MOPA laser system based on Fiber laser
oscillator preamplifier and conventional high
power Nd amplifiers
Choice 3! A full Fiber laser MOPA system
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EO FAST Scanning
a 45 deg
Z axis
Ideas are being explored to scan using
electro-optics Crystals
Deposited Electrodes
prism aperture
approx. 11 mm
First prototypes under Design.
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Fast scanning
EO crystal
Next experimental tests - LNB prism (slide 2)
and LNB plate (slide 3) ready for static HV
tests. - Beam quality test using cylindrical
lens to introduce an ellipticity on the laser
beam Future - High frequency HV design (slide
5) - High rep rate (100 kHz) operation
tests - High laser power tests (gt1 MW per pulse)
A. Bosco
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Fast Scanning Plans
Up to Apr 07

• Investigate issues of a working EO scanning
  system
• Compare with fast piezo scanners
• Initiate design of high frequency drivers
• Investigate RF locking with laser driver
• Investigate running at a beam test facility

Beyond Apr 07 (subject to new funding)

• Build integrated fast scanning system
• Operate at ATF2 with multiple IPs
• Investigate frequency tripled light (or higher
  modes)?
• Engineering prototype for ILC use.

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Simulations
Photons
Electrons
Simulations of laser-wires in BDS are underway in
BDSIM. LINAC simulations are planned see talk
by J. Carter.
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Summary

• Very active international programme
• Hardware
• Optics design
• Advanced lasers
• Blue-skies RD
• Data taking analysis
• Simulation
• Programme imbedded into GDE
• Training of PDRAs and students
• International schools
• ZEMAX workshop
• Local laser workshop
• At the labs
• Look forward to a year of data-taking at PETRA
  and ATF
• Planning next phase of RD now.