1. 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

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

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

4. 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

5. 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)
Phase extension FWHM (deg) ~ ~10
Energy spread FWHM (keV) ~ ~80
Normalized emittance rms (m)
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

6. 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

7. 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

8. 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

9. (thin unstrained GaAs)
FY 06 WBS 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

10. WBS 2.3 and 3.3: FY 06-09 Electron Source Activities10
April 4, 2006

11. 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

12. 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

13. 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

14. FY06 WBS 2.4.2
undulator 14
April 4, 2006

15. 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

16. 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

17. 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

18. Summary (from Wm. Bugg, UTK)
FY06 WBS 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

19. FY06 WBS 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

20. 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

21. 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

22. WBS 2.4 and 3.4: FY 06-09 Positron Source Activities, 1-of-222
April 4, 2006

23. WBS 2.4 and 3.4: FY 06-09 Positron Source Activities, 2-of-223
April 4, 2006