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Diagnostics Summary
G. Blair
RHUL
23rd June 2005
Laser Wire Mini Workshop Chair: J. Urakawa, J. Frisch
EUROTeV Chair: G. Blair
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
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)
A. 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
A. Aryshev, H. Hayano, P. Karataev, K. Kubo, N. Terunuma,
J. Urakawa
Kyoto
N. Sasao
SLAC
A. Brachmann, J. Frisch, M. Ross
Project web page: http://www.hep.ph.rhul.ac.uk/~lbbd/
Laserwire - PETRA
+ UCL
RHUL
UCL
11.2.05
+ Oxford
DESY
CERN
See talk by S. Malton,
this workshop
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.
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
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
Confocal
Resonator
Pickup
A. Ferrari (Uppsala)
PBPM- L. Soby (CERN)
Requirements
•
•
•
•
Aperture:
Resolution:
Absolute precision:
Rise time:
Dynamic range:
Linearity error:
24H stability:
Vibrations
Low frequency cutoff:
High frequency cutoff:
Bake out temperature:
Operating temperature:
Vacuum:
4mm
100nm
10μm
<15ns
±1.5mm (15 bits)
< 1%
1μm
<100nm
100kHz
30MHz
150C
~20C
10-9 Torr
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
Low frequency cutoff:
100kHz
Bake out temperature:
150C
Operating temperature:
20C
Vacuum:
10-9 Torr
100kHz-20GHz WB signal transmission
over 10-20m.
4W
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
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
Voltage Δ/Σ [a.u]
Plot of the output voltage (behind electronics) vs position of the beam
Position of the beam (mm)
ILC meeting
A. Liapine UCL
Spectrometer design
 Possible 3/4 magnet
spectrometer designs
Dipole magnet
BPM triplet
 3 Magnets
– Deflection angle measured
from offset and distance
– Beam incline influence on
BPM measurements
Dipole
magnet
 4 Magnets
– Translation of beam
– Extra precision dipole required
– Simple translation of BPMs for
maximum sensitivity
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
Summary of EUROTeV
TPMON
Phase Detection Requirements
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
• Single-shot
• ± 50MHz bandwidth
• 0.1 degree resolution
• Limited linear range OK
• Amplitude range?
250 MHz REFERENCE
FREQUENCY
DOWNCONVERTED 250 MHz
BEAM SIGNAL

Things to do next
ARRAY OF AD835
ANALOGUE MULTIPLIERS
SUMMED TO REDUCE NOISE
•More work on summed analogue
multipliers
•Review other phase detection methods
•Choose IF
ADC's
CORRECTION
FOR
AMPLITUDE
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
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
A wedge is used to act on the gimbal mount in vacuum
R. Cizeron, R. Marie, J. Bonis
Summary
• R&D EUROTEV at LAL/Orsay : 2005-2007
– Fabry-Perot cavity for a polarimeter
• 1ps/100fs pulses of energy 100 mJ/pulse@76MHz
– Moderate input Ti:sa laser beam power but very high cavity finesse
30000-300000
– 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
(100mJ/pulse@~300MHz)
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, m+m- etc.
(Active study at UCL {+ new collaborators}
see Stewart Boogert’s report to top/QCD at LCWS)
BeamCal: Beam Diagnostics
and Fast Luminosity Monitoring
e+
e-
e+e- pairs from beamstrahlung are
deflected into the BeamCal
 15000 e+e- per BX
=>
10 – 20 TeV
=>
O(μs)
~ 10 MGy per year
“fast”
Direct photons for q < 400 mrad (PhotoCal)
Deposited energy from
pairs at z = +365
(no B-field, TESLA parameters)
C. Grah
DESY
Results of Analysis
Parameter
σx
σy
σz
beam offset x
beam offset y
vertical waist shift
nom.
553
5.0
300
0
0
360
in
nm
nm
μm
nm
nm
μm
phot. pairs
4.2 1.5
0.1 0.2
7.5 4.3
4.0 6.0
0.16 0.4
14
24
C. Grah
DESY
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
[email protected]
Freddy Poirier – ILC-European workshop 2005
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
Freddy Poirier – ILC-European workshop 2005
Tau=6*107
Diagnostics Summary
A big thankyou to all
the speakers and particpants