Update on FACET at SLAC

Christine Clarke 23rd August 2012

ESTB Users Meeting

Introduction to FACET

• FACET uses 2/3 SLAC linac to deliver electrons to the experimental area in Sector 20

• The FACET dump separates FACET from LCLS

• Our first User Run was April-July 2012

http://facet.slac.stanford.edu

Facility for Advanced Accelerator Experimental Tests

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Beam Parameters

Parameter Typical Value 2012 Best Value 2012Energy (GeV) 20.35Charge per pulse 2.7 nC (1.7e10 e-) 3.0 nC (2.0e10 e-)Bunch length σz (μm) 20-25 20

Beam size σx x σy (μm)

35 x 35 20 x 23

Particle Electrons

Positrons will be commissioned in 2013 for delivery to experiments in sector 20 in 2014.

Proposal Process

• In 2011 and 2012, we received 15 proposals

• The charge of the SAREC committee is to: - evaluate the scientific merit - evaluate the feasibility- review the progress of existing R&D

• 7 proposals have led to beam-time as of now:- 6 further experiments have been

approved and are waiting for beam-time in 2013 4

Receive Proposals

Peer review (SAREC)

SAREC ranks proposals

Highest ranked proposals get beamtime

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Time Allocation for 2012

Number of Experiments 7Total Beam Time scheduled in User Run 2012 2046 hours

FACET’s first User Run was 12 weeks long (13th April – 5th July 2012)

Most of the time was allocated to experiments (65%)

Some time was set aside for machine development (20%)

One day a week is a scheduled access day for experimental installations and hardware maintenance (15%)

Plasma Wakefield

Acceleration28%

Dielectric Wakefield Studies

20%

Material Science5%

Accelerator Diagnostic 4%

THz Source Studies

3%

Linac Studies3%

Machine Develop-

ment21%

Planned Tunnel Ac-

cess15%

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FACET Beamline

Sector 0 Sector 10 Sector 20Linac:

FACET (Sector 20):

Experimental Area (next slide)

Notch Collimator

xTCAV

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FACET’s Experimental Area

Diagnostics

Sample chamber

Plasma Experiment Sample

chamberProfile measurement experiment

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Notch Collimator and TCAV

• Started commissioning transverse defecting cavity for bunch length measurements

• Started commissioning Notch Collimator for creating two bunches

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E-200 Multi-GeV Plasma Wakefield Acceleration

• SLAC, UCLA, MPI• FACET’s high power electron beam ionises alkali gas and interacts

with the plasma, wakefields accelerating part of the bunch• Lithium – small interaction, occasionally significant acceleration

observed• Rubidium - consistently lots of interaction and good accelerationBeam bypassing plasma Beam going through plasma

Significant interaction (energy loss)

Energy gain by ~8% of beam

E-201 Wakefield Acceleration in Dielectric Structures

Slab-symmetricStructures

Axi-symmetricTubes

e-

Sample holder on stages for alignment

• UCLA, Euclid Techlabs, Tech-X, Radiabeam Technologies, NRL, SLAC, MPI, Argonne

FACET provides unique high-field regime to test limits of dielectric wakefield structures

• >1GV/m acceleration anticipatedCoherent Cherenkov Radiation (CCR) spectrum gives information about the excited modes

• ~THz frequency light source

The FACET beam is sent through prototype structures of varying dimensions and materials

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E-202 Study of Ultrafast Processes in Magnetic Solids following Excitations with Electron Beams

• SLAC, IBM, Univ. Regensburg, Bogolyubov Institute

A novel switching process - electrical field induced magnetic anisotropy

• Fastest and most efficient method of switchingWhat is the microscopic origin for observed phenomena?

• Exposed magnetic samples to the electron beam• Began study of ferroelectric films and resistive memories• Exposed materials used in spintronics applications

CoFe Fe

Samples

Spin-sensitive electron microscope imagesThanks I. Tudosa

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FWHM600 fs = 180 µm

FWHM310 fs = 93 µm

FWHM 420 fs = 126 µm

E-203 Determination of the time profile by means of coherent Smith-Purcell radiation

• Univ. Oxford, LAL Orsay, Univ. Valencia, ENS Lyon, Los Alamos, SLAC• Comparatively cheap, compact, non-destructive bunch length diagnostic• FACET provides ultra-short bunch length regime

Data from August commissioning and April this year

• Main uncertainties from the inaccurate knowledge of the beam-grating distance• Not yet one-shot, data were averaged over time and beam conditions may have

changed

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Reconstructed bunch profiles from August 2011Thanks G. Doucas

April 2012

Can directly compare measurements to transverse deflecting cavity and E-206

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E-206/T-500 THz Studies of FACET Source

• THz frequency electromagnetic radiation is produced at 1μm titanium foil inserted into beamline upstream of IP Area

• Goal: characterize THz pulses, determine peak fields

• Measure temporal profile and spectrum – affected by source size

• Determine peak electric and magnetic fields. Property Preliminary Result

Frequency 1 THz

Energy per pulse ~0.5 mJ

Focus size ~1 mm

Electric field strength at focus ~6 MV/cm

• There is interest from SLAC’s PULSE and SIMES to use extracted THz for materials studies

Thanks A. Fisher and Z. Wu13

T-501 Linear Collider Final Focus and Alignment Algorithms

• CERN, Univ. Oslo, PSI, EPFL, TU Graz, SLAC• Experimental verification of CLIC and ILC main linac corrections

- linac system identification- global orbit correction- global dispersion correction

• Measured machine responses and performed correction 24hr later• Good orbit correction over a test section of 500m of the linac

Thanks E. Adli and A. Latina

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Looking Ahead…

• FACET’s second User run is in winter/spring 2013- Proposals for 2013 and 2014 currently welcome!

https://slacportal.slac.stanford.edu/sites/ard_public/facet/user/Pages/ProposalOverview.aspx

- The proposal deadline is 1st September- FACET User Meeting 9th/10th October

http://www-conf.slac.stanford.edu/facetusers/2012/ - Next SAREC review 11th/12th October

• New features to the facility are coming:- E-200 is installing a 10TW Laser to pre-ionise plasma- Positrons will be commissioned in 2013 for delivery to experiments in 2014- Designs for a THz transport line are in place to take THz up to the laser room

• FACET continues to run ~4 months/year until 2016