AAC May 6-8th, 2008 Accelerator Science at the A0 photoinjector and beyond P. Piot, APC/FNAL May 7 th, 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 EnergyHigh LuminosityPeople 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.  MeV high average and peak brightness electron beams available to users for Accelerator Science R&D NML A0 ILCILC, PrX 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 should 1.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 photoinjector 4.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 upgrade capable of strengthening our program before move to NML?

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 operation at 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 MeV exp. area Possible configuration for A0 upgrade NML photoinjector option TESLA cavity 3.9 GHz TM 010 Rf-gun Flat beam transform Bunch compressor new rf gun 2 booster cavities bunch compressor at MeV new rf gun 2 booster cavities bunch compressor at 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

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 AWA team.

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) A0 program committee Emittance Exchange Diagnostics R&D LLRF & Control system Upgrade of A0 (gun + E) Beam dynamics studies New experiment 1 New experiment 2 New 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.