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Summary Report from WG6:High resolution diagnostics, timing,
and stabilizationJohn Byrd, LBNL
Florian Loehl, Cornell University
Diagnostics has it all…
Diagnostics
LasersUltrastable
clocks
Beam dynamics
RF and microwavesFiber optics
Electronics
X-ray detectors
Challenging problems inspire innovative solutions and attract very good people
Topics
• Overviews of hot topics in storage rings, FELs, ERLs, and LPAs
• Longitudinal and transverse bunch diagnostics– Deflecting cavities– EO sampling techniques
• Timing and synchronization– Science drivers (Coffee and Barty)– Present status at present facilities– Future directions
SpeakersDiagnostics overview for the LCLS J. Frisch,
Diagnostics overview for ERLs Pavel Evtushenko, Jefferson Lab
High precision orbit stabilization in future light sources Boris Keil,
Overview of storage ring diagnostics Glenn Decker, ANL
Beam Diagnostics using a Transverse Deflecting RF-Structure at FLASH Christopher Behrens, DESY
Electro optical methods to measure the longitudinal beam properties Allan Gillespie, University of Dundee
Transverse and longitudinal electron beam diagnostics Hirokazu Maesaka, Spring-8
Optical replica synthesizer Peter van der Meulen, Stockholm U.
Streaking at optical frequencies Yuantao Ding, SLAC
Longitudinal diagnostics for laser plasma accelerators Jeroen van Tilborg, LBNL
Optical Diagnostics for Ultrashort bunches from Laser-Plasma Accelerators Nicholas Matlis, LBNL
Single shot undulator spectra for an emittance diagnostic Michael Bakeman, LBNL
Timing for pump-probe experiments at LCLS Ryan Coffee, SLAC
Pump probe timing at FLASH / XFEL Anton Barty, CFEL
Results from CW stablized link timing distribution at LCLS R. Wilcox, LBNL
Recent progress on the pulsed optical synchronization system Franz Kartner, MIT
Installation progress of the optical synchronization system at FLASH Sebastian Schulz, DESY
Precision optical timing distribution and electron arrival-time measurement Yurji Otake, SPring-8
Simulations on Beam Monitor Systems and Longitudinal Feedback Schemes for FLASH Christopher Behrens, DESY
Photon arrival-time monitor for LCLS Valery Dolgashev, SLAC
Overview of diagnostic systems for high brightness electron injectors Henrik Loos, SLAC
Diagnostics for high repetition rate ERL injectors Florian Loehl, Cornell University
• Optical imaging highly sensitive to COTR from tiny optical beam structure.
• High quality beams like to bunch!
ORS: Optical Replica Synthesizer (Peter van der Meulen)
FLS2010, March 1-5, 2010, 48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources
Temporal Profile MeasurementHirokazu Maesaka, SPring8
• The electron bunch is vertically pitched by transverse RF voltage and the temporal structure is converted to a spatial distribution.
• Beam image is taken by an OTR monitor.• Required temporal resolution: < 10 fs
– 100 fs/mm on the screen (after 5–10m drift space)– Peak deflecting voltage: 40 MV
• Installed downstream of 3rd Bunch compressor
1.4 GeV
5-10m~4m
7
C-band
Detailed Investigations (Christopher Behrens)
Electro-Optic Techniques...Allan Gillespie, STFC
SLAC DESYLBNL, ...
FELIX DESYRAL(CLF)MPQJena, ...
FELIX DESYLBNL...
Spectral Decoding
Spatial Encoding
Temporal Decoding
complexity
demonstratedtime resolution
spectral upconversion
Spectral upconversion diagnosticAim to measure the bunch Fourier spectrum...
... accepting loss of phase informatio & explicit temporal information
... gaining potential for determining information on even shorter struct
... gaining measurement simplicity
use long pulse, narrow band, probe laser
• laser complexity reduced, reliability increased• laser transport becomes trivial (fibre)• problematic artefacts of spectral decoding become solution
→ δ-function
NOTE: the long probe is converted to optical replica
same physics as “standard” EO
different observationaloutcome
•Many new opportunities for machine optimization (i.e. diagnostics)•Large overlap with interests with operating ultrafast FELs
•Inherent fsec bunches•Inherent synchronization with high peak-power lasers
•Lots of machine time for development.
Time Domain Approach (Franz Kaertner)
J. Cox et al. CLEO 2008.
PZT-based fiber stretcher
Mode-locked laser
Fiber link ~ several hundreds meters
to a few kilometers
isolator
TimingComparison
Faradayrotatingmirror
Frequency domain approachRussell Wilcox
• FRM is Faraday rotator mirror (ends of the Michelson interferometer)
• FS is optical frequency shifter• CW laser is absolutely stabilized• Transmitted RF frequency is 2856 MHz• Detection of fringes is at receiver• Signal paths not actively stabilized are temperature controlled
Rblock
0.01C
AMCWlaser
0.01C
FS
RF phasedetect,correct
opticaldelay
sensing
FRMFRM fiber 1
fiber 2d1
d2
ωFSωRF
transmitter receiver
XFEL/SPring-8 (Yuji Otake)
LCLS timing scheme
• We sync to bunch arrival time monitor• The laser is treated as a VCO 120Hz
trigger
undulator
phasecavity
arrivaltimemonitor
receiver
near-end hall
X6476
φ
φ
receiver
laser
experiment
modulator
CW laser
X6
divider
476
2856 and 68
sender
e-
timing information
~150m
2856
4.25
2856
First Pump-Probe at LCLS (Ryan Coffee)
• Many new opportunities open up for <10 fsecpulses AND synchronization
Stabilizing the whole machineChristopher Behrens
• Use diagnostic measurements to feedback and stabilize machine
• Essential for new sources to approach the stability performance of storage rings
X-ray phase cavity (Valery Dolgashev)
rf probe
target
electron bunch
Solid Model: Robert Reed, SLAC
14 m
m
Optical Streaking (Yuantao Ding)
20
System Setup • laser system: beating 800nm+770nm, 0.5TW
• a 10-period wiggler
• a spectrometer
Summary• Tremendous progress since FLS2006• New opportunities for x-ray BPMs and stabilization at
new SRs and SR upgrades. • COTR for optical imaging diagnostics potentially a
problem for all high quality beams. • “Standard” diagnostics approaching maturity with
detailed analysis and incorporation into machine feedback.
• New techniques need to push resolution to ~1 fsec. • Timing distribution over stabilized fibers at <10 fsec
daily drift now available. Work needed to get <10 fsecdrift at the experiment. How do we get to 1 fsec?
• Thanks to the organizers!
• Special thanks to the working group members for excellent presentation and very lively and stimulating discussion.