Accelerator Physics and Engineering Update

Jan 6, 2010Josef Frisch Tonee Smith

Clive FieldAlan FisherHenrik Loos Christopher Behrens (NEW!) Nate Lipkowitz (NEW!) Jeff RzepielaMark PetreeSteve SmithJim WelchGlen WhiteWalter WittmerMark WoodleyGerald Yocky

APE: What we do

Physics

EngineeringOperations

Whatever it takes to make accelerators work

Some long term planned projects

Some kludges to get systems working

E-beam opticsLight opticsX-raysDetectorsApplicationsModelingRFElectronicsAcousticsVacuumMechanicalPowerPoint

Beam Arrival Time Monitor Problem

Phase cavity difference noise has been increasing since OctoberIncrease from 12 to ~50 femtoseconds RMSDifficult to debug: still smaller than raw beam jitter, no signal when beam is off.

Not yet the dominant noise source, but will be soon!

In addition to short term fix, need an independent check: 3rd phase cavity?

Future Timing• Previous meeting mentioned using an optical / X-ray cross-correlator.

GaAs or similar

Laser

X-rays Reflected optical beam measured on array sensor

Tests at SXR (W. Schlotter et al) have demonstrated 60fs RMS single shot X-ray to laser optical timing measurement.

Note that electronic timing will still be needed for “crude” 100fs timing

Cross Correlator (very preliminary)

W. Schlotter et al. (LCLS)

(SXR)M. BeyeB. Schlotter

Materials Damage and Wavefront Distortion Tests

3D map of damage to SiO2 Sample

Damage

Damage and wave front distortion tests indicate that Al2O3, Diamond and SiC all are OK.

Speckle from Be attenuators led to search for alternate materials

Fused Silica damages

Be Lens to be Installed in LCLS X-ray diagnostics chamber

4000 5000 6000 7000 8000 9000 1 1040

2

4

6

Simulated divergence for R=1.5mm Be lens at STOR=2 mmR=3 mmExpected divergence in 2005Measured LCLS divergence in 2010

photon energy [eV]di

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ence

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r STO

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B. Lenegeler, J. Krzywinski, E. Kraft, et al. (Engineering, LCLS, APE, etc)

Reduce divergence to (incorrect) design

Broadband IR Spectrometer for Bunch Length Measurement

Measure spectrum of OTR light from short bunches to estimate bunch lengthNeed single shot, very broadband ~50:1 low resolution (25%) spectrometerOperating range ~0.8 –40 microns

PyroelectricArray detector

OTR foil

Parabolicmirror

ParabolicmirrorPrism,

KRS-5

Tilted image plane corrects aberrations

Christoph BehrensHenrik LoosJennifer LoosSasha Gilevich

Optics design done, prototype parts on order

THz

Emitted THz power GaAs z-scan

D. Daranciang et. Al.

THz system for LCLS now being commissioned.Working with Pulse, and Stanford have first demonstration experiments with THz

Alan Fisher will discuss in detail in next talk.

LHC Synchrotron Light Monitor

Lead Ions at 2.3 TeVA. Fisher will discuss in next talk

ATF2 Recent Results4 OTR screens now provide reproducible emittance measurements in less than a minute, rather than hours for the wire scanners (1.5 Hz beam).

Automated Dispersion Correction G. White, M. Woodley, S. Boogert, T. Smith

25 Cavity BPMs now working at <50nm resolution

Spot size monitor not working in high resolution mode (ATF2 group)

Other Projects• 120Hz upgrades– Time-slot aware feedbacks: Big project from Controls and APE. – Accelerator now at 120Hz with good time-slot.

• FACET bunch length monitors – (similar to LCLS)

• Diagnostics and control applications– Ongoing efforts to automate machine operations

• Thermal-acoustic X-ray calorimeter– Passed Vacuum check– Install in late January.