NLCTA Facility Capabilities

E. R. Colby 5/18/09

NLCTA Overview

RF PhotoInjector

Ti:Sapphire LaserSystem

Next Linear Collider Test Accelerator

Cl. 10,000 Clean Room

Counting Room(b. 225)

E163 Optical Microbuncher

Gun Spectrometer

ESB

Next Linear Collider Test Accelerator

E-163

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

S X-0 X-1 X-2

X-3

(2-pack)

L-1

(SNS)

Space available for experiments

20 feet

30 feet

Capabilities• Electron Beam (from injector)

– 60 MeV, 5 pC, p/p≤10-4, ~1.5x1.5 mm-mradtpsec– Beamline & laser pulse optimized for very low energy spread, short pulse

operation• Laser Beams

– 10 GW-class Ti:Sapphire system (800nm, 2 mJ)• KDP/BBO Tripler for photocathode (266nm, 0.16 mJ)

– Active and passive stabilization techniques– 5 GW-class Ti:Sapphire system (800nm, 1 mJ)

• 100 MW-class OPA (1000-3000 nm, 80-20 J)• 5 MW-class DFG-OPA (3000-10,000 nm, 1-3 J)

• 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/= 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

First- and Second-Harmonic COTR Output as a function of Energy Modulation Depth (“bunching voltage”)

Left: First- and Second-Harmonic COTR output as a

function of temporal dispersion (R56)

Inferred Electron Pulse Train Structure

Bunching parameters: b1=0.52, b2=0.39

C. M. Sears, et al, “Production and Characterization of Attosecond Electron Bunch Trains“, Phys. Rev. ST-AB, 11, 061301, (2008).

800 nm 400 nm

400 nm 800 nm

=800 nm

Inferred Electron Beam Satellite Pulse

E

400 nm

800 nm

Q(t)

I(t)

Electron Beam Satellite!

Machine stability supports sub-picosecond class e/ experiments

e.g. This cross-correlation measurement of the electron bunch profile took 5 minutes.

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

• 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)

EEHG Location

Measurement Locations

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/ experiments is directly

relevant and provides significant leverage– Experience designing experiments and hardware in this low-charge sub-

psec regime– Wealth of advanced automated measurement software in LabVIEW and

Matlab