Summary Timing and Diagnostics

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Summary Timing and Diagnostics

• 1Franz X. Kärtner and 2Steve Jamison
• 1CFEL - DESY and MIT, 2Daresbury

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CW / Pulsed Timing Distribution and Synch.
MIT- DESY Pulsed LBNL Cw- Laser
Timing Stabilized Optical Fiber Links
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Pulsed Timing-Stabilized Fiber Links
Fiber link several hundreds of meters to a few
kilometers
PZT-based fiber stretcher
isolator
Mode-locked laser
Balanced Optical Cross Correlator
Faraday rotating mirror
Cancel fiber length fluctuations slower than the
pulse travel time (2nL/c).
1 km fiber travel time 10 µs ? 100 kHz BW
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Other Implementations
Pulsed FLASH _at_ DESY European XFEL planingPAL in
prototype phase
CW LCLS _at_ SLAC XPS _at_ APS NGLS planing
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FERMI CW Transmitter
Electron bunch arrival time measurement Drive
KLY3 unstable
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5.3fsRMS in 10 days
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Towards sub-fs systems
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Jungwon Kim, KAIST Sub-100 attosecond Ultrafast
Lasers
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Tisapphire Laser Jitter 13 as
A. Benedick, et al. Nat. Photonics 6, 97-100,
2012
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Timing To Do List

• Ongoing work is concentrated on pushing the
  timing precision towards the sub-fs scale
  in laboratory experiments

• Urgent need in engineered implementation of
  sub-10fs systems in accelerator
  laboratories with many gt 10s of links. -
  systematically eliminate free space sections and
  components
• - all fiber implementations avoiding unintended
  reflections
• - integrated optical components, plug and play-
  develop a true timing technology base suited for
  modulator
• implementations in accelerator facilities
• Open issues for sub-systems operating at
  low-repetition rate characterize drifts of
  amplifiers and how to compensate for it
• characterize intra pulse train drifts and
  how to compensate for it
• Ultimately single shot X-ray optical cross
  correlator to eliminate
• critical drifts at the output

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Diagnostics longitudinal profile
Bernhard Schmidt, DESY
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Measured Spectrum -gt temporal profile.
Retrieval of missing phase info through
Kramers-Kronig

• Much discussion on feasibility of retrieval
• Sceptics converted by real data demonstration
• only possible through thorough calibration
• - ..caveats/pitfalls puzzles still remain

Discrepancies real beam effects (?)
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Online bunch profile available for FLASH
operators....
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Prospects of EO as facility ready systems...?
Current time resolution 1 ps potential
improvement to 100fs (state of art) with data
deconvolution..
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Do we need explicit time information...?
Upconvert bunch form factor to an optical
spectrum Potential for robust all-optical
diagnostic - simple/robust ns laser
Discussion on whether the phase information could
be experimentally retrieved. Yes, probably ...
With reintroduction of modest complexity
(another laser!)
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Time explicit diagnostics
Many challenges need to be overcome together to
break the 100fs barrier in resolution

• Materials issues
• Bandwidth currently 10THz. Want 50THz
  bandwidth!
• Potential solutions in new materials, or in
  multi-crystal detectors

• optical characterisation issues
• FROG concepts for sub (optical) pulse
  duration characterisation
• phase retrieval at low pulse energy..
• splicing of multi-crystal detectors

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Wider diagnostic challenges (no claim to be
comprehensive!)
High dynamic range imaging - halo
high current machines. - high
repetition rate laser wire as potential solution
Ultrafast Photon diagnostics (arrival /
duration) - (soft-xray ) attosecond laser
technique other? - hard xray .
Via electron beam diagnostics (energy loss).
Other?
Laser-plasma diagnostics almost everything
challenging! - 1 fs duration - Emmittance
- Energy spread - slice
parameters !!!? But some nice results coming out
(duration through faraday effect in plasma)
Users and operator availability vs.
Diagnostics-by experiment -
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Summary Timing and Diagnostics

• Thank you to speakers and workshop organizers