Laser based Emittance Measurement for LINAC4

Laser basedEmittanceMeasurementfor LINAC4 Project Overview & CurrentStatus T. Hofmann, E. Bravin, U. Raich, F. Roncarolo, F. Zocca (CERN) G. Boorman, A. Bosco, S. Gibson, K. Kruchinin (RHUL) 08.5.2014 Thomas Hofmann CERN – Beam Instrumentation (BE/BI/PM) thomas.hofmann@cern.ch

Contents • Overview & Simulations • 3 MeV Test Setup • PreliminaryResults

CERN Accelerator overview LINAC 4 LHC luminosity upgrade!

LINAC 4 overview • Particles: H-ions • Top Energy: 160 MeV • Current: 40 mA • Pulse length: 400 µs Transfer line to PSB 160 MeV Linac length ~ 80 m 100 MeV 50 MeV Laser Emittance Meter

Concept of Laser Emittance Meter for 160 MeV NON invasive! DiamondDetector Pulsed Laser 1064 nm H0 H- x-scan Bending Magnet y-scan H- beam Principle: H- beam H0 beamlet < 1 ppm beamlet after drift

Laser-Particle Interaction • Stripping Probability • In rest frame of H- beam: • Lorentz-Shift of Photon Energy • At 160 MeV: 1064 nm -> 909 nm Ref: J.T. Broad and W.P. Reinhardt, Phys. Rev. A14 (6) (1976) 2159 • Laser requirements: • Laser wavelength: 1064 nm • M2 < 3 fordiameter < 200 µm • PPeak > 1 kW

Stripping & propagation to detector • H- Beam • Size (1 Sigma): y = 1.6 mm • Div (1 Sigma):y’ = 2.2 mrad • Laser Beam • Size (1/e2): = 150 µm • Rayleigh length = 10 mm 3.0 m Drift Laser • Emittance measurement possible via vertical detector scan

3 MeV Testbench Transfer line to PSB 160 MeV 100 MeV 50 MeV Testbench

Setup at 3 MeV Diagnostics Testbench Focusing system

Lasers

Integration Laser Setup Diagnostics rack Linear stage with 500 mm lens tube PXI-System Class 4 fiber laser Coupling Ref: Fiber Laser Transport for the PhotodetachmentEmittance Measurements at FETS, AlessioBosco

Optical setup Fiber input with collimator lens Focusing lens Beam Expander 5m LMA fiber (20/130 µm; NA =0.08) CCD with filterwheel on stage H- Beam Photodiode Focusing & Diagnostics Laser – Fiber Coupling

Detector Scope 500 V 1 µF Preamp 50 Ohm CIVIDEC Instrumentation, Austria

Troubleshooting • Burnedfiber end-facets • ~ 250 J/cm2 • Noise ofmotordriver on signalofdiamonddetector • Pre-amplifiersfor Diamond Ref: G. Mann et al: ›Nanosecond laser damage resistance of differently prepared semi-finished parts of optical multimode fibers‹, Applied Surface Science 254, pp.1096-1100 (2007)

PreliminaryResults • Rawsignal • Beam profile • Vertical emittance

Outlook • 12 MeV Testbench • 10 m LMA fiberforlasertransport • Particles traverse diamond detector • 160 MeVsetup • Detector(Readout & Calibration) • Fiber deliverysetup (20 m needed)

Thanks for your attention!

Laser based Emittance Measurement for LINAC4