Two Problems...

1
Two Problems...

• LCLS Diagnostics and Commissioning Workshop

This work was performed under the auspices of
the U.S. Department of Energy by the University
of California, Lawrence Livermore National
Laboratory under contract No. W-7405-Eng-48 and
by Stanford University, Stanford Linear
Accelerator Center under contract No.
DE-AC03-76SF00515.
2
Gain Length Measurement
3
How faint can FEL be?
(X-Ray resolution 300 x 100 mm)
14.5 GeV
1 FEL Spontaneous directly into 25 mm LSO
0.01 FEL Spontaneous into 25 mm LSO
4
Camera Image Calculator Chain
Photoelectrons in Camera (2.5 x Zeiss SITEC
CCD)
Absorbed in 25 mm LSO
Spontaneous
Spontaneous FEL resampler
(E,Px,y)
Spontaneous
Transmitted by Material
5
Gain Length Simulation

• Run separate spontaneous calculations at position
  of imagers for roll-away undulator senario.
  Current spatial binning good. Energy binning too
  fine.
• Run FEL simulations for previous cases. Use finer
  spatial binning (10 microns.) Put in same format
  as as spontaneous.
• Write re-sampler module for XTOD analysis chain
  to combine FEL and spontaneous at camera
  resolutions. Evaluate camera response

6
What fixed apertures will we allow?
7
1.5 Scope Front End Enclosure/ Near Experimental
Hall
PPS
4' Muon shield
NEH
PPS
Flipper Mirror
Front End Enclosure
Comissioning Spectrometer, Total Energy
Solid Attenuator
Slit A
112 m
Direct Imager Indirect Imager
Photon Beam
83 m
Slit B
Gas Attenuator
13' Muon shield
Fast close valve
Electron Beam
Electron Dump
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Spontaneous Fluence at NEH Hutch 1
Te 4.5 GeV Z 243 m Dx 1.0 mm Dy 0.3
mm 1.85 mJ
Te 14.5 GeV Z 243 m Dx 0.3 mm Dy 0.1
mm 18.2 mJ
2
4
9
Spontaneous with Vacuum Pipe Reflection
14.5 GeV
4.5 GeV
Near Hall, Hutch 1
4.5 GeV beam gt10 cm diameter
14.5 GeV beam gt4 cm diameter
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Setting apertures

• Strategy should be to allow as wide a beam
  possible during commissioning, then put in our
  custom Fixed Masks
• We need to generate 4.5 and 14.5 spontaneous
  radiation patterns at minimum apertures (muon
  shields, post undulator )
• We need to understand aperture limits (radiation
  safety) and consequences (commissioning) and
  finalize

11
Photon Energies gt 400 KeV
Without pipe
With pipe