LASER-WIRE UPDATE

• Commissioning of the PETRA3 Laser-wire• Summary of first ATF-ext laser-wire• Installation of ATF2 laser wire

Grahame BlairCLIC Technical Board

CERN29th June 2010

www.pp.rhul.ac.uk

THE RHUL TEAM• Grahame Blair

Laser-wire, BDSIM, …• Stewart Boogert

Laser-wire, low-Q BPM, ATF2…• Pavel Karataev

CDR, CTF3, ATF2 …• Stephen Molloy

RF Simulation, RTML, ATF2…

• Alessio BoscoLaser-wire

• (Anne Dabrowski)CTF3, …

• Lawrence DeaconLaser-wire, BDSIM

• (Alexey Lyapin)Laser-wire, BPM, ATF2, …

• Robert AinsworthRF Simlation,

•Thomas AumeyrLaser-wire

• Nirav JoshiBPM

• Konstantin LekomtsevCDR/CTF3

• Maximilian MichelerCDR/CTF3

• + 2 others to join this year

CLIC-related activities

POST-DOCTORAL RAS

ACADEMICS

PHD STUDENTS

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DESY : V. Gharibyan, S. Schreiber, K. Wittenburg, K. Balewski

JAI@Oxford: B. Foster, N. Delerue, L. Corner, L. Nevay, R. Walczak

JAI@RHUL:,T. Aumeyr, G. Blair, S. Boogert, G. Boorman, A. Bosco, L. Deacon, P. Karataev

KEK: A. Aryshev H. Hayano, K. Kubo, N. Terunuma, J. Urakawa

Laser-wire People

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PETRA II

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PETRAII 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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Q-switched, unseeded Laser Longitudinal Profile

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

60 ps

66 ps

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Laser Temporal Profile

Unseeded

Seeded

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Laser Pointing Jitter

Translates into a 1.6 m jitter at the LW IP forBoth horizontal and vertical scans

Translates to longitudinalso not relevant

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PETRAII Results: Vertical

Convoluted profile(takes<50s)

Fit to Rayleigh formula

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PETRAII Results: Horizontal

Convoluted profile

Fit to Rayleigh formula

PETRAIII Laser-Wire

Installed early 2009Easy initial commissioningCurrently have Laser problems

PETRAIII Laser-wire

PETRAIII Laser-wire

Breadboard layout

Raw scan

ATF-ext Laser-wire

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Aiming at micron-scale vertical scansATF Laser-Wire

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Layout in ATF Extraction line

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ATF2 Detector

optimum

Where we were running

Effect of Optical Aberrations

Pulsed laser performance

Profile scans (shows astigmatism)

Temporal scans (shows laser pulse length)

Simple Gaussian Fit

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Laserwire principle

Systematic Effects:Fit methods

Important to know beam aspect ratio

ATF2 Laser Infrastructure installation

• Large laser room on ATF2 shield blocks– Facility for future users– 6 m optical table– Temperature stabilised– Seismic safe

ATF2 Laser TestsTasks completed:1.Check laser working (sorted out cooling) – very good2.Started work on software for DAQ and experiment control3.Set up temperature logging around laser hut4.Aligned cw laser into tunnel and through laser-wire IP5.Completed laser pulse duration measurements6.Started laser spatial quality measurements

Interferometric autocorrelation

Laura CornerLaurie NevayStewart BoogertAlex Aryshev (KEK)

Intensity autocorrelation

Mode-LockedOscillator

Pulse duration: 10 psPulse energy: 15 nJPulse power: 1.5 kWRepetition rate: 62.5 MHzAverage power: 1 W

Fiber AmplifierFiber Core 30 m

Diode Pump Pw = 12W

Pulse duration: 10 psPulse energy: 500 nJPulse power: 50 kWRepetition rate: 1 MHzAverage power: 500 mW

RHUL Mode-Locked LaserCurrent Status

Pulse duration: 10 psPulse energy: 180 nJPulse power: 18 kWRepetition rate: 62.5 MHzAverage power: 12 W

Pulse duration: 10 psPulse energy: 10 nJPulse power: 1 kWRepetition rate: 1 MHzAverage power: 10 mW

PulsePicker

Possible Improvement

Current StatusPETRAII showed good results for an accelerator ring LW

PETRAIII laser wire installed and commissioning hasStarted; however there are currently laser problems

ATF-ext: Proof of principle for a BDS LW

ATF2 LW has been installed and attempts at signal observation have so far been unsuccessful; there is a verylong path for photon extraction (electron extraction not relevant due to relatively small Compton energy loss)

Laser R&D ongoing at both RHUL and Oxford; fibre lasersare being actively developed and tested.

(Funding issues beyond March 2011).

Relevant Publications

Theory/emittance extraction:Phys. Rev. ST Accel. Beams 10, 112801 (2007)

PETRAII laser-wire:Nucl.Instrum.Meth.A592:162-170,2008

ATF Laser-wire:Proc. PAC09 A. Aryshev et al.(PRST-AB in preparation)

Possible fast scanning system based on EO:Applied Physics Letters 94, 1 (2009)