1. Diagnostics Summary G. Blair RHUL 23rd June 2005
Laser Wire Mini Workshop Chair: J. Urakawa, J. Frisch
EUROTeV Chair: G. Blair

2. Diagnostics I Laser Wire Mini Workshop Chair: J. Urakawa, J. Frisch
(08:30->12:00) (Location: Arts) (Room: G3A--)
Micron electron beam optics at ATF extraction line for laser wire experiment P. Karataev / KEK
ATF Laser-wire Optics N. Delerue / Oxford
ATF infrastructure plans + discussion D. Howell / Oxford
PETRA laser-wire analysis S. Malton / UCL
PETRAIII Laser-wire T. Kamps / BESSY
EO Scanning possibilities A. Bosco / RHUL
UK Laser-wire project: plans G. Blair / RHUL
Aims:
Define+ decide key parameters for ATF extraction line LW
Discuss recent scans + analysis from PETRA LW
Aim towards ATF2 LW project and ILC LW needs

3. University College London (UL)
Laser-wire People
BESSY
T. Kamps
DESY
H. C. Lewin, S. Schreiber, K. Wittenburg, K. Balewski
Oxford
R. Bingham, S. Dixit, B. Foster, N. Delerue, D. Howell, A. Reichold
Royal Holloway (UL)
Agapov, G. Blair, G. Boorman, A. Bosco, J. Carter,
L. Deacon, F. Poirier, M. Price, C. Driouichi
University College London (UL)
S. Boogert, S. Malton
CCLRC Daresbury
L. Jenner
KEK
Aryshev, H. Hayano, P. Karataev, K. Kubo, N. Terunuma, J. Urakawa
Kyoto
N. Sasao
SLAC
A. Brachmann, J. Frisch, M. Ross
Project web page:

4. Laserwire - PETRA See talk by S. Malton, this workshop + UCL RHUL UCL
+ Oxford
RHUL
UCL
DESY
CERN
See talk by S. Malton,
this workshop

5. Practical Considerations I
f1 geometry is challenging
Limitations from power
Limitations from angle
Surface optical quality
Alignment tolerance
See talks by
N. Delerue + D Howell
in this workshop.

6. Practical Considerations II
See talks by
N. Delerue
in this workshop.
f1 Lens design is challenging
Limitations from power
Limitations from ghost images
Alignment tolerance

9. Diagnostics II EUROTeV Chair: G. Blair (08:30->12:00) (Room: G3A--)
Confocal Resonator Beam Position Monitor
Ferrari, A / Uppsala Uni.
Precision Cavity BPM + WBCM: Wide-Band Current Monitor L.Soby / CERN
The Cold Re-entrant Q-BPM design C. Simon /CEA/Saclay
Development of non-invasive micron beam size diagnostics using optical diffraction radiation P. Karataev / KEK
High Energy Polarimetry F. Zomer / LAL, Orsay
Timing and Phase Monitoring J. Sladen / CERN
Fast Lumi Monitoring C. Grah / DESY-Zeuthen
Fast Lumi Spectrum Measurement F. Poirier / RHUL
Precision Energy Spectrometry D. Miller / UCL
Aims
Discuss and define the EUROTeV tasks
Explore synergies and potentials for lumi-spectrum

10. Confocal Resonator Pickup A. Ferrari (Uppsala)

11. PBPM- L. Soby (CERN) Requirements
Aperture: 4mm
Resolution: 100nm
Absolute precision: 10μm
Rise time: <15ns
Dynamic range: ±1.5mm (15 bits)
Linearity error: < 1%
24H stability: 1μm
Vibrations <100nm
Low frequency cutoff: 100kHz
High frequency cutoff: 30MHz
Bake out temperature: 150C
Operating temperature: ~20C
Vacuum: Torr

12. WBCM-Requirements L. Soby (CERN)
Beam current monitor with > 20GHz band width for measurement of
intensity and bunch to bunch longitudinal position.
Main beams, drive beams and
damping rings.
Impedance
4 W
Lf cut-off, direct output
250 kHz
Lf cut-off, integrator output
10 kHz
Hf cut-off
7 GHz
Number of feed thru 8
Gap length
2 mm
Beam aperture diameter
40 mm
Length
256 mm
Flange type
DN63CF
Max temp. bake-out
150 ºC
Low frequency cutoff: 100kHz
Bake out temperature: 150C
Operating temperature: 20C
Vacuum: Torr
100kHz-20GHz WB signal transmission over 10-20m.

13. C. Simon CEA/Saclay Cold Re-entrant Q-BPM design
The reentrant BPM is a resonant cavity with 4 feedthroughs and analog and digital electronics
Good resolution ~1µm and good “centering accuracy” <1µm
Now, the cleaning of the cavity, with the holes, is ok. Tests in DESY were made
Good resolution time. The damping time for the re-entrant cavity is 9.5ns.
Robust in the cold
Tests on the new system at the beginning of 2006
Plot of the output voltage (behind electronics) vs position of the beam
Voltage Δ/Σ [a.u]
Position of the beam (mm)
ILC meeting

14. Liapine UCL Spectrometer design
BPM triplet
Dipole magnet
Possible 3/4 magnet spectrometer designs
3 Magnets
Deflection angle measured from offset and distance
Beam incline influence on BPM measurements
4 Magnets
Translation of beam
Extra precision dipole required
Simple translation of BPMs for maximum sensitivity
Dipole magnet

15. Results from ATF - resolution
May 2005 data
Fitting algorithm
Calibration using hexapod movers
Resolution ~ 35 nm
Stable: 20 nm drift over 2 hours, around 80 nm of jittering over few minutes

16. Summary of EUROTeV TPMON
Phase Detection Requirements
Single-shot
± 50MHz bandwidth
0.1 degree resolution
Limited linear range OK
Amplitude range?
Alexandra Andersonn and Jonathan Sladen
Develop, build and test 30GHz beam
phase measurement system aiming for 0.1 degree (9fs) resolution
Precision synchronization is a feasibility issue for CLIC
Phase detection will be at a lower, intermediate frequency,
developments may be of interest to other machines
Things to do next
More work on summed analogue multipliers
Review other phase detection methods
Choose IF

17. Fabry-Perot cavity & pulsed laser
R. Bernier, J. Bonis, V. Brisson, R. Chiche, R. Cizeron, G. Guilhem, M. Jacquet-Lemire, D. Jehanno, R. Marie, K. Moenig, V. Soskov, A. Variola, Z. Zhang, F. Zomer
Outline
Introduction : 2 laser needs for ILC
Fabry-Perot cavity, in pulsed regime
R&D at LAL : description & status

18. Fabry-Perot cavity filled with a pulsed laser
Electron beam
1ps
Pulsed laser
Fabry-Perot cavity
with Super mirrors
A priori impossible because of the laser frequency width:
Dn ≈1/(1ps)=1THz for picosecond laser (c.f. 3kHz cavity banwidth for a gain of 104)
In fact possible with mode-locked lasers

19. A wedge is used to act on the gimbal mount in vacuum
R. Cizeron, R. Marie, J. Bonis

20. Summary R&D EUROTEV at LAL/Orsay : 2005-2007
Fabry-Perot cavity for a polarimeter
1ps/100fs pulses of energy 100
Moderate input Ti:sa laser beam power but very high cavity finesse
Feedback on frep & f0 [need for a high quality mode-locked laser beam]
Concentric OR ring cavity to reduce the laser beam size
mechanics & feedback conception started
If this R&D gives satisfaction
Study of the implementation for a polarimeter
A new laser source should be considered to match the laser power required for an e+ polarised source study

24. D. Miller UCL Physics needs the Luminosity weighted spectrum
at collision. Three components:
1. Precision measurement of absolute incoming energy.
Main goal of ESPEC project. Rest of talk.
BPM spectrometer in upstream chicane.
2. Measurement of shape of incoming spectrum.
Long term concern. Maybe Laserwire upstream?
(Downstream: Eric Torrence, earlier this morn.)
3. Correction for beamstrahlung and beam fluctuations.
Event-based: Bhabha acollinearity, e+e- Z, +- etc.
(Active study at UCL {+ new collaborators}
see Stewart Boogert’s report to top/QCD at LCWS)

25. BeamCal: Beam Diagnostics and Fast Luminosity Monitoring
e+e- pairs from beamstrahlung are
deflected into the BeamCal
15000 e+e- per BX => – 20 TeV
~ 10 MGy per year
“fast” => O(μs)
Direct photons for q < 400 mrad (PhotoCal)
Deposited energy from
pairs at z = +365
(no B-field, TESLA parameters)
C. Grah
DESY

26. Results of Analysis C. Grah DESY Parameter nom. in phot. pairs
σx nm
σy nm
σz μm
beam offset x 0 nm
beam offset y 0 nm
vertical waist shift 360 μm 14 24
C. Grah
DESY

27. Fast Luminosity Spectrum Measurement
Aim
Bhabha & Beamstrahlung generator  Interface
Luminosity Calorimeter
Response matrix
Parameters estimation technique
Estimation result
Unfolding
Choice of regularisation parameter
Summary
Outlook
Freddy Poirier - RHUL/JAI
Freddy Poirier – ILC-European workshop 2005

28. Summary
Unfolding helps drastically to gain in accuracy for the beam energy spread measurement.
Larger mean errors in the estimated parameters for the unfolded results.
Lumi. spectrum reconstructed correctly (not minimum χ2).
Relative errors
Tau=6*107
Freddy Poirier – ILC-European workshop 2005

29. the speakers and particpants
Diagnostics Summary
A big thankyou to all
the speakers and particpants