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.