AAC May 6-8th, 2008

Accelerator Science at theA0 photoinjector and beyond

P. Piot, APC/FNAL

May 7th, 2008

AAC May 6-8th, 2008

DOE HEP “Advanced Technologies R&D” Program

• Accelerator Science in National Labs:

• Excerpt from the request for funding: – “At Fermilab, the FY 2009 budget will support experimental studies of electron

beam physics in a high-brightness photo-injector, research on muon acceleration, and research by the Accelerator Physics Center in beam theory and accelerator simulation. R&D in support of the international muon cooling collaboration with Rutherford Appleton Laboratory in the UK will continue. “

Request

AAC May 6-8th, 2008

Accelerator R&D for future HEP facilities

High Beam Energy High Luminosity People

Highest Accelerating

Gradient

Smallest Beam Emittances

Train Accele-rator

Physicists

E-beam Plasma DWA

Laser Plasma Direct

Sources e-guns, ,

H-

Control xchange,

cool

FACILITIES

FFTB/FACET,AWA,L’OASIS/BELLA,A0/NML,NEPTUNE,ATF,UMER..

Univ’s

Labs

AAC May 6-8th, 2008

Scientific Highlights

• Present: – Beam physics

• optimization of high brightness beam: emittance, peak current, magnetized beams, beam compression

• Emittance exchange and phase-space manipulations (Traditional interest due to stochastic, electron, muon cooling expertise);

– Accelerator Technology• Without the A0 photoinjector we would not have had any

SCRF at Fermilab! • R&D on a 3.9-GHz cavity and CM for the DESY FLASH facility;

• Future direction: – Beam Physics: A combination of emittance exchange schemes,

higher beam energy and higher peak current (novel acceleration schemes, Å-wavelength photons, etc…)

– Accelerator Technology: Advanced instrumentation

AAC May 6-8th, 2008

Current Schedule

• Operation of A0 until 2011, • 2012: A0 moves to NML

bldg. 50-500 MeV high average and peak brightness electron beams available to users for Accelerator Science R&D

2008 2009 2010 2011 2012 2013NML

A0

ILC ILC, PrX ILC, PrX ILC, PrX ILC, ARD ILC, ARD

NML

A0

AAC May 6-8th, 2008

Accelerator Science & Education at NML

• NML could be the backbone of Accelerator Science activities at Fermilab in conjunction with Project-X, collider R&D, ILC, AARD

• NML could also be used as an AARD user facility provided we have a strong support, investment, and commitment from the laboratory…

• Pay-off is enormous: – unique center in the Midwest for accelerator science and education,– attract more universities/students (collaborations w. A0/AARD groups:

ANL, Chicago, DESY, IIT, INFN, NIU, Penn, Paris XI, Rochester, UCLA, UW),

bring extramural funding from other agencies the AARD program could eventually become a self-sustained program.

AAC May 6-8th, 2008

Short term plans at A0

• Upgrade(s) in A0 building should1. be minimally disruptive to the experimental program,2. provide an opportunity to expand the Scientific program,3. provide path for a smooth transition to the NML photoinjector4. improve reliability/capability of the facility

• Minor upgrades (already planned) include– Low Level RF system,– New rf gun (from DESY),– DAQ (e.g., digitizers)– High level control system.

• What is the most viable upgradecapable of strengthening our program before move to NML?

Coaxial coupler

Gun CavityMain solenoid

Bucking

solenoid

photocathode

e-

Coaxial coupler

Gun CavityMain solenoid

Bucking

solenoid

photocathode

e-

AAC May 6-8th, 2008

Energy upgrade from 15 to ~40-50 MeV

• Provide an opportunity to expand the science program,– Lessen space charge force O(1/2)– Provide a more rigid beam – Reduce p/p higher flat beam ratio

• Would mimic the NML photoinjector: ex-situ commissioning of the NML injector! – benchmark beam dynamics– Develop/refine diagnostics •Is an energy upgrade realistic?

–We have a 2nd cryomodule+cavity assembly already commissioned–Real estate in A0 will be tight but OK–Shielding issues might prevent operationat full energy and full current (but “few-bunches” mode OK for all experiments)–Implication on cryogenic system is the main issues

AAC May 6-8th, 2008

Possible experiments at A0 (currently under consideration for proposals)

• 20-fs time-of-flight monitor with an Electro-optical Modulator (FNAL)

• Deflecting-mode cavity for slice emittance measurement (FNAL)

•Image Charge Undulator (coll. w. Jlab & NIU) •Ultra-low transverse emittance using Ya. Derbenev’s ring-to-flat beam scheme•Electro-optical beam position monitor (FNAL/NIU)•Inv. Cherenkov acceleration in Open Iris Loaded Structure using a TM*010 laser

AAC May 6-8th, 2008

Example: phase space manipulation

• Generic activity started in the context of linear colliders.

• Applications beyond linear colliders have emerged:– Ultra short pulse X-ray in recirculating

linacs (Berkeley) and Storage-ring based (APS/ANL) light sources,

– Use to drive Image charge undulator (sponta-neous and possibly SASE-type radiation).

• Led to longitudinal-to-transverse emittance exchange (motivation from light sources).

• Next manipulation to try at A0: shape the initial laser distribution and map low initial intrinsic emit-tance beam into very low emittance round beams via a nonlinear transformation.

x

y

x

x’y’

y

x

x’y’

y

At cathode (magnetized)

After flat beam transform

After nonlinear transformation

(Ya. Derbenev)

AAC May 6-8th, 2008

A0 upgrade vs. ILCTA photoinjector

ILC cryomodule

40-50 MeV exp. area

• Possible configuration for A0 upgrade

• NML photoinjector option

TESLA cavity

3.9 GHzTM010

Rf-gun Flat beamtransform

Bunch compressor

• new rf gun• 2 booster cavities• bunch compressor

at 40-50 MeV

• new rf gun• 2 booster cavities• bunch compressor

at 40-50 MeV

AAC May 6-8th, 2008

Photoinjector performances

• Beam parameter comparable to current state-of-the-art accelerators

• Bunch compression at 40 MeV is a challenging beam dynamics problem (collective effects)…

• Can be “ignored” with flat beams

Q=3.2 nC

Q=1.0 nC

• Longitudinal distribution can be tailored

AAC May 6-8th, 2008

Possible experiments at NML (currently being discussed)

• Phase space manipulations:– 3.9 GHz cavities for grabbing,– Phase space manipulations between two degree-of-freedoms– Optical Stochastic Cooling.

• Radiation source and high-gradients:– Image Charge Undulator to support a SASE FEL (coll. w. Jlab & NIU) – In vacuum laser acceleration

• Extension of the Inverse Cherenkov using a TM*010 laser at A0, • Other type of laser/beam coupling structure?

– Beam driven acceleration in slab dielectric structure.• Diagnostics:

– Bunch length and slice emittance Diagnostics– High order mode-based BPMs in SC cavities, – Electro-optical technique for time-of-flight & bunch duration

monitor,– Novel transverse beam diagnostics: diffraction radiation, laser

Compton scattering.More example from potential users at http://home.fnal.gov/~piot/ILCTA_AARD/

AAC May 6-8th, 2008

Example: Dielectric accelerating slab structure in the Terahertz regime

• Dielectric wakefield acceleration in cylindrical-symmetric structure was pionnered at ANL (AWA) in the GHz regime.

• Extension to THz more compact accelerators and higher E-field.

• Slab structures offer advantages– better tuning capability,– higher stored energy and cor-

respondingly reduction of beam loading, and

– mitigation of transverse wakefields .

• Need compressed flat beams with bunch length < 1 mm.

• This could be an extension of what is currently done at AWA and would be done in collaboration with AWAteam.

AAC May 6-8th, 2008

Plans: short term [up to ~2011]

1. Need to have a mini workshop to see interest in A0 beam time

2. Review informal proposal + approve beam time for main experiments (A0 program committee?)

3. Small, parasitic, locally-based experiments (diagnostics R&D, LLRF development, optimization of the photoinjector performances) should continue in parallel to (2)

2008 2009 2010 2011 2012A0 program committeeEmittance ExchangeDiagnostics R&DLLRF & Control systemUpgrade of A0 (gun + E)Beam dynamics studiesNew experiment 1New experiment 2New experiment 3

AAC May 6-8th, 2008

Plans: longer term [>2011]

• When the general plan with NML become clearer, organize a second AARD workshop at Fermilab (probably in 2011),

• Have a formal call for proposal.

• AARD activities will be competing with ILC-related R&D at NML.

• There is synergy between the two programs in many areas.• AARD should be fully integrated as part of the NML program

and not be considered as a side activity.• There should be a good organization to support external

AARD users (e.g. provide operators and beam time) at NML.

• Scheduling beam time might be challenging, • Successful example is DESY’s TTF-1 which supported a linear

collider and FEL programs simultaneously for several years

AAC May 6-8th, 2008

Conclusions

• Over the past years A0 has made significant contributions to Accelerator Science & Technology.

• These achievements have been possible thanks to strong collaborations with Universities and Institutes (both within US and abroad) along with students involvement.

• To become more competitive with other national labs, Fermilab plans to expand its Accelerator science and education program using the NML facility as a backbone.

• Such a GeV (eventually)-class facility could become the main user facility in the Midwest and foster a strong University-based research and education programs.

• In the short term an energy upgrade of A0 is appealing: it would (1) support a significant expansion of the Accelerator science program and provide (2) a smooth transition to the NML facility.