A. Brachmann and J. C. Sheppard SLAC April 4, 2006 April 2006 DOE/NSF Review - Polarized Electron Source and Positron Source R&D FY06 Status and FY07-09 Proposal WBS 2.3, 3.3, 2.4, 3.4 A. Brachmann and J. C. Sheppard SLAC April 4, 2006 1 April 4, 2006

ILC Polarized Electron and Positron Sources: WBS 2.3, 3.3, 2.4, 3.4 (FY06 WBS ) 2 April 4, 2006

ILC Polarized Electron Source - Schematic Layout - Photocathode R&D e- Gun Technology Source Drive Laser System 3 April 4, 2006

Polarized Electron Source FY 06 WBS Budget Overview WBS Work Package Labor Direct DOE M&S Direct DOE Budget 2.3 Electron Source design 180 3.3 Electron source R&D 3.3.1 Polarized electron source R&D 3.3.2 Development of Polarized Photocathodes for the Linear Collider 222 100* SLAC Spending 2.3 Electron source design 87.16 42.49 43.72 WBS 3.3 FY05/06 M&S combined 400 WBS 3.3 FY 05/06 spending (Feb. 06) 60.32 Additional laser room installation (HVAC, PPS) 150 WBS 3.3 FY 06 remaining budget 189.68 * Additional M&S from FY 05 carry over (see table below), decision was made to combine FY05/06 M&S to allow for HVAC installation and room upgrade for ILC source laser lab Remaining budget for WBS 3.3. will be spend on ILC polarized e- source laser system. 4 April 4, 2006

FY 06 WBS 2.3 Injector Design RDR work Simulations: Successful conversion of Parmela Saclay design (TESLA TDR - gun exit to buncher exit) some parameters (phase, solenoid) are adjusted Parameters TESLA TDR SLAC Energy (MeV) 11.3 10.9 Phase extension FWHM (deg) ~10 ~10 Energy spread FWHM (keV) ~100 ~80 Normalized emittance rms (m) 42 25 Future simulation work: higher gun voltage, higher SHB frequency, real solenoidal field, etc. Parmela simulations starting from buncher exit to the warm L-band exit (~90 MeV) are underway. 5 April 4, 2006

FY 06 WBS 3.3.1 Polarized electron source R&D - RF Gun Technology - US Collaboration: SLAC, FNAL, BNL, JLAB, MIT, NIU, Princeton HOM design at 1300 MHz 50Ω input coaxial line with beam pipe aperture 4 cm Adjustment of field flatness by outer wall tapering 6 April 4, 2006

FY 06 WBS 3.3.1 Polarized electron source R&D - Laser R&D - New facility (Laser lab, HVAC, PPS system) in parallel with SLAC’s ~ 500 k$ investment for building upgrade (CEF budget, not ILC!) Remainder of FY 06 is dedicated to ILC bunch train generation Mode locked Ti:Sapphire oscillator Fast electro-optic system ILC Laser Lab DC Gun Lab 7 April 4, 2006

FY 06 WBS 3.3.2 Photocathode R&D - Overview - R&D Topics University of Wisconsin Collaboration: Goals: 90% Polarization 1 % QE Re-optimization of doping profile to increase polarization Faster conduction electrons improves QE and polarization (SL parameters and cathode bias Smaller spin-orbit interaction reduces depolarization of e- (SL parameters) Support of Photocathode R&D program: InAlGaAs/GaAs superlattice structures 85 % polarization GaAs/GaAsP supelattice structures: 86 % polarization Support for source drive laser construction 8 April 4, 2006

(thin unstrained GaAs) FY 06 WBS 3.3.2 Photocathode R&D - Biased Photocathodes - Biased photocathodes (thin unstrained GaAs) Bias across Photocathode using metal grid forward bias  QE ↑ negative bias  QE, Polarization ↓ 9 April 4, 2006

WBS 2.3 and 3.3: FY 06-09 Electron Source Activities 10 April 4, 2006

Layout of ILC Positron Source WBS 2.4 and 3.4: ILC Positron Source Layout of ILC Positron Source Photon production at 150 GeV electron energy K=1, l=1 cm, 200 m long helical undulator Two e+ production stations including a back up. Keep alive auxiliary source is e+ side. e- source e- DR e- Dump Photon Dump e+ Auxiliary e- Source Photon Collimators Adiabatic Matching Device e+ pre-accelerator ~5GeV 150 GeV 100 GeV Helical Undulator In By-Pass Line Target 250 GeV Positron Linac IP Beam Delivery System e- Target 11 April 4, 2006 M. Kuriki, KEK

Polarized Electron Source FY 06 WBS Budget Overview WBS Work Package Labor Direct M&S Direct FY06 Budget 2.4.1 Positron Source design 2.4.2 End-to-end simulations 455 150 3.4.1 NC Positron Capture Structure 3.4.2 E166 Polarization Experiment 3.4.3 Positron source target design 3.4.4 Undulator-based Polarized Positrons 466 40 275 40a 225 25 15 Spending to Date 2.4 Positron source design 235 0.5 3.4 Positron source R&D 395 78 a. Total FY06 University of Tennessee e+ funding 12 April 4, 2006

FY06 WBS 2.4.1: Positron Source Design In FY06, after completion of the BCD in December, 2005, the majority of the efforts on the ILC e+ systems are directed towards the development of the ILC RDR Specifications Layouts Optics Interactions w/ ILC TS and GG Costing RDR Text Drawings 13 April 4, 2006

FY06 WBS 2.4.2 undulator 14 April 4, 2006

FY06 WBS 3.4.1: NC rf Structures, 1 Goal: Evaluate performance of a 1.3 GHz, NC cavity Issues: Significant heating from both rf and particle losses, must sustain high surface fields (~ 35 MV/m for 1 msec) 15 April 4, 2006

NC rf Structures Project Description FY06 WBS 3.4.1: NC rf Structures, 2 NC rf Structures Project Description A five cell, pi-mode, standing-wave cavity with a 60 mm aperture has been designed for the (a new rf window has also been developed for this application). A prototype cavity will be constructed at SLAC and installed in the NLCTA beamline in a 0.5 T solenoidial field, as would be witnessed in the ILC. Using the L-band source being constructed at NLCTA, the cavity will be powered with 5 MW, 1 ms pulses at 5 Hz to produce a 15 MV/m accelerator gradient. A single bunch beam with a variable injection time will be accelerated in the cavity to measure the variation of the gradient during the pulse. 16 April 4, 2006

NC RF Structure Project Status FY06 WBS 3.4.1: NC rf Structures, 3 NC RF Structure Project Status Half cells for body rough machined. Need to braze pairs, 2nd machining and tuning. Four windows are being made, two of which will be tested at high power before one is used for the cavity. Expect to receive a SDI-legacy solenoid magnet from Boeing soon. Need 100 gpm temperature regulated water supply – initial tests at NLCTA show this to be feasible with present system. Expect cavity completion in 3-4 months. As of March 1, 2006 225 k$ labor charges (466 k$ allocated) – includes some e+ accelerator design efforts. 67 k$ M&S charges (140 k$ allocated). Spending roughly commensurate with progress – expect structure test in FY06 17 April 4, 2006

Summary (from Wm. Bugg, UTK) FY06 WBS 3.4.2 and 3.4.4: E166-Polarized Positrons Summary (from Wm. Bugg, UTK) E166 completed successful running-October 10, 2005. Undulator produced photons at the expected intensity and showed predicted quadratic dependence on magnet current. Undulator is well understood. Photon polarization was demonstrated and observed asymmetry agreed well with that expected from the predicted undulator spectrum. Polarized Positrons were produced, converted into photons and transmission asymmetry measured. Final results on expected intensity and the average positron polarization as a function of momentum await the completion of simulations incorporating fine details of the positron transport system including a more accurate field map, survey information, shielding and better mechanical detail. E166 has provided successful demonstration of feasibility of polarized positron production at ILC. 18 April 4, 2006

FY06 WBS 2.4.1 and 3.4.3: AMD Adiabatic Matching Device: Point-to-parallel focusing element for e+ collection A viable AMD: pulsed/shielded and or dc/immersed: 1+2 years 7T axial magnetic field for positron capture Two technologies under consideration Pulsed device based on previous design (circa 1965): improvement for performance and reliability Immersion of target field improves positron capture by 40% over that possible with the field profile of the flux concentrator. Because of the uncertainties, both technologies will be studied 19 April 4, 2006

FY06 WBS 3.4.3 (J. Gronberg, LLNL) A conceptual design for the positron target Positron target design FY06 $600K (1.5FTE) Detailed engineering of the spinning target Drawings being produced for prototyping at Daresbury Simulations of eddy currents from the AMD magnetic field done. Verifying calculations with a small test setup Mitigation strategies in place Examining the design for a pulsed AMD Target simulations Energy deposition radiation damage Activation Analysis of remote handling issues Eddy currents in a spinning metal disc 20 April 4, 2006

FY06 WBS 2.4.1: Undulator Demonstration of undulator performance with a standard undulator module: 3 years 200 m helical undulator K=1, l = 1 cm, id > 6 mm superconducting coil 2-3 m length module Goal: spec performance characteristics in FY06; build and demo performance of a trial module in FY07-09 21 April 4, 2006

WBS 2.4 and 3.4: FY 06-09 Positron Source Activities, 1-of-2 22 April 4, 2006

WBS 2.4 and 3.4: FY 06-09 Positron Source Activities, 2-of-2 23 April 4, 2006