Transcript NLCTA Facility Capabilities [ file]

NLCTA Facility Capabilities
E. R. Colby 5/18/09
NLCTA Overview
E
S
B
Counting Room
(b. 225)
Ti:Sapphire Laser
System
Cl. 10,000 Clean Room
L-1
X-3
(SNS)
(2-pack)
E-163
E163 Optical Microbuncher
Gun Spectrometer
RF PhotoInjector
30 feet
Next
Linear
Collider
Test Test
Accelerator
Next
Linear
Collider
Accelerator
S
X-0
X-1
Space available
for experiments
20 feet
X-2
NLCTA capabilities:
* S-band Injector producing high-brightness 60 MeV beams (to ~100 pC); ultrashort, ultracold
* (4) x-band rf stations and >300 MeV of installed structures
* (2) L-band rf stations
* Skilled operations group with significant in-house controls capability
Capabilities
• Electron Beam (from injector)
– 60 MeV, 5 pC, dp/p≤10-4, e~1.5x1.5 mm-mrad, st~0.5 psec
– Beamline & laser pulse optimized for very low energy spread,
short pulse operation
• Laser Beams
– 10 GW-class Ti:Sapphire system
• KDP/BBO Tripler for photocathode
(800nm, 2 mJ)
(266nm, 0.16 mJ)
– Active and passive stabilization techniques
– 5 GW-class Ti:Sapphire system
(800nm, 1 mJ)
• 100 MW-class OPA
• 5 MW-class DFG-OPA
(1000-3000 nm, 80-20 mJ)
(3000-10,000 nm, 1-3 mJ)
• Precision Diagnostics
– Picosecond-class direct timing diagnostics
• Micron-resolution beam diagnostics
– Femtosecond-class indirect timing diagnostics
– Picocoulomb-class beam diagnostics
• BPMS, Profile screens, Cerenkov Radiator, Spectrometer
– A range of laser diagnostics, including autocorrelators, crosscorrelators,
profilometers, etc.
NLCTA Laser & LSS
Modest changes required to support EEHG Experiment:
• Install evacuated transport line (vacuum components in-hand; pumping is in place)
• Install second laser safety shutter (no new logic; add second driver + shutter)
• Seek LSC approval for 1-3 micron operation in NLCTA vault and modify SOP
EEHG Experiment and Diagnostics are similar to
the E-163 Attosecond Bunching Experiment
Experimental Parameters:
• Electron beam
• γ = 127
• Q ~ 5-10 pC
• Δγ/g = 0.05%
• Energy Collimated
• εN = 1.5 mm-mrad
• IFEL:
• ¼+3+¼ period
• 0.3 mJ/pulse laser
• 100 micron focus
• Z0 = 10 cm (after center
of und.)
• 2 ps FWHM
• Gap 8mm
• Chicane 20 cm after undulator
• Pellicle (Al on mylar) COTR
foil
Attosecond Bunch Train Generation
800 nm
400 nm
First- and Second-Harmonic COTR Output as a function of
Energy Modulation Depth (“bunching voltage”)
l=800 nm
Inferred Electron Pulse
Train Structure
400 nm
Bunching parameters: b1=0.52, b2=0.39
800 nm
Left: First- and
Second-Harmonic
COTR output as a
function of temporal
dispersion (R56)
C. M. Sears, et al, “Production and
Characterization of Attosecond Electron Bunch
Trains“, Phys. Rev. ST-AB, 11, 061301, (2008).
Machine stability supports sub-picosecond class e/g experiments
e.g. This cross-correlation measurement of the electron bunch profile took 5 minutes.
Inferred Electron Beam Satellite Pulse
sE
800 nm
Electron Beam
Satellite!
I(t)
Q(t)
400 nm
Much of the visible spread is due to COTR
intensity jitter (~Q2) rather than timing jitter
Preliminary Beam Quality Measurement at EEHG Experiment Location
20 pC, 60 MeV, Measured 4/13/09
EEHG Location
Measurement
Locations
• Dispersion measurement was not yet working in downstream linac!
Horizontal emittance had significant residual dispersion contribution
• Beam at 60 MeV (drifting through all linac x-band structures)
Summary
• Existing NLCTA laser systems meet EEHG experimental
requirements
– Modest extension of the LSS functionality required (shutter+driver)
– Laser transport installation required (components in-hand)
• Existing NLCTA electron beam quality meets EEHG
experimental requirements at 120 MeV, likely also at 60 MeV, with
further machine studies.
– Some additional beam diagnostics ahead of the EEHG experiment
would speed commissioning
• Sub-picosecond-class timing stability has been demonstrated
• E-163 experience with near-IR e/g experiments is directly
relevant and provides significant leverage
– Experience designing experiments and hardware in this low-charge subpsec regime
– Wealth of advanced automated measurement software in LabVIEW and
Matlab