1. L ASER - WIRE U PDATE Commissioning of the PETRA3 Laser-wire Summary of first ATF-ext laser-wire Installation of ATF2 laser wire Grahame Blair CLIC Technical Board CERN 29 th June 2010 www.pp.rhul.ac.uk

2. T HE RHUL T EAM 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 Bosco Laser-wire (Anne Dabrowski) CTF3, … Lawrence Deacon Laser-wire, BDSIM (Alexey Lyapin) Laser-wire, BPM, ATF2, … Robert Ainsworth RF Simlation, Thomas Aumeyr Laser-wire Nirav Joshi BPM Konstantin Lekomtsev CDR/CTF3 Maximilian Micheler CDR/CTF3 + 2 others to join this year CLIC-related activities P OST -D OCTORAL RA S A CADEMICS P H D STUDENTS

3. 3 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

4. 4 PETRA II

5. 5 PETRAII Detector Requirements for detector material – short decay time (avoid pile up) – short radiation length – small Moliere radius Cuboid detector crystals made of PbWO 4 3x3 matrix of 18x18x150 mm crystals Energy resolution better than 5%

6. 6 Q-switched, unseeded Laser Longitudinal Profile Example of a single shot measurement of the profile 500 ps window, resolution 5 ps 60 ps 66 ps

7. 7 Laser Temporal Profile Unseeded Seeded

8. 8 Laser Pointing Jitter Translates into a 1.6  m jitter at the LW IP for Both horizontal and vertical scans Translates to longitudinal so not relevant

9. 9 PETRAII Results: Vertical Convoluted profile (takes<50s) Fit to Rayleigh formula

10. 10 PETRAII Results: Horizontal Convoluted profile Fit to Rayleigh formula

11. PETRAIII Laser-Wire Installed early 2009 Easy initial commissioning Currently have Laser problems

12. PETRAIII Laser-wire

13. Breadboard layout Raw scan

14. ATF-ext Laser-wire

15. 15 Aiming at micron-scale vertical scans ATF Laser-Wire

16. 16 Layout in ATF Extraction line

17. 17 ATF2 Detector

19. optimum Where we were running Effect of Optical Aberrations

20. Pulsed laser performance Profile scans (shows astigmatism) Temporal scans (shows laser pulse length)

21. Simple Gaussian Fit

22. 22 Laserwire principle

24. Systematic Effects: Fit methods  Important to know beam aspect ratio

25. ATF2 Laser Infrastructure installation Large laser room on ATF2 shield blocks – Facility for future users – 6 m optical table – Temperature stabilised – Seismic safe

26. ATF2 Laser Tests Tasks completed: 1.Check laser working (sorted out cooling) – very good 2.Started work on software for DAQ and experiment control 3.Set up temperature logging around laser hut 4.Aligned cw laser into tunnel and through laser-wire IP 5.Completed laser pulse duration measurements 6.Started laser spatial quality measurements Interferometric autocorrelation Laura Corner Laurie Nevay Stewart Boogert Alex Aryshev (KEK) Intensity autocorrelation

27. Mode-Locked Oscillator Pulse duration: 10 ps Pulse energy: 15 nJ Pulse power: 1.5 kW Repetition rate: 62.5 MHz Average power: 1 W Fiber Amplifier Fiber Core 30  m Diode Pump Pw = 12W Pulse duration: 10 ps Pulse energy: 500 nJ Pulse power: 50 kW Repetition rate: 1 MHz Average power: 500 mW RHUL Mode-Locked Laser Current Status Pulse duration: 10 ps Pulse energy: 180 nJ Pulse power: 18 kW Repetition rate: 62.5 MHz Average power: 12 W Pulse duration: 10 ps Pulse energy: 10 nJ Pulse power: 1 kW Repetition rate: 1 MHz Average power: 10 mW Pulse Picker Possible Improvement

28. Current Status PETRAII showed good results for an accelerator ring LW PETRAIII laser wire installed and commissioning has Started; 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 very long 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 lasers are being actively developed and tested. (Funding issues beyond March 2011).

29. 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)