ILC Positron TDR and R&D Meeting 1: Oxford ILC GDE Activities Update and Undulator Scheme Status

1. ILC Positron TDR and R&D Meeting 1: OxfordILC GDE Activities Updateand Undulator Scheme Status J. C. Sheppard SLAC September 27, 2006 1

2. Undulator Scheme ILC GDE Activities Update, to date December, 2005: Undulator Baseline Documentation – BCD March, 2006: RDR Configuration: the undulator scheme April, 2006: RDR Parts Inventory to Technical Systems for Costing July, 2006: RDR Preliminary Costing Results (the Big Secret) August-September, 2006: Cost comparisons between undulator and conventional schemes; central Injector layouts and initial costing activities. September, 2006 GDE Decision: Undulator Scheme and Central Injector 2

3. Undulator Scheme ILC GDE Activities Update, thru end of calendar 2006 September, 2006: RDR Text Outlines (N. Phinney editor) November, 2006: Valencia Meeting: RDR Text and Costs (???? rumors of short delay with appropriate rescoping of RDR deliverables….)15 pages for undulator scheme; not clear how alternatives are being handled 3

4. Beam Delivery System Positron Linac IP 150 GeV 100 GeV 250 GeV Helical Undulator In By-Pass Line Photon Collimators e- Dump e- Dump Photon Dump e- DR e- source e+ pre-accelerator ~5GeV Photon Target Optical Matching Device Auxiliary e- Source e+ DR Optical Matching Device e- Target Undulator Scheme Layout of ILC Positron Source: December, 2005 • Photon production at 150 GeV electron energy • K=1, l=1 cm, 100 m long helical undulator • Two e+ production stations (1 as backup) + KAS • Pulsed OMD (shielded target) • Keep alive auxiliary source is e+ side • Timing Insert and Trombone in PML Extension 4

5. Undulator Scheme Positron System Site Layout: July 2006 5

6. Undulator Scheme Positron System Site Layout Discussions: September, 2006 6

7. Undulator Scheme Positron System Site Layout Discussions: September, 2006 Central Injector Discussions: Electron dr and a single positron dr in a single tunnel located at the center of the ILC site Two 14 mrad crossing angle IPs at a different elevation (~10-20 m) from dr’s Positron production still at 150 GeV point in electron main linac e+ transport line reduced from 18.7 km to about 5 km Removal of timing insert (still need to do correct timing) and 2nd IP trombone Looking at feasibility to use e- source to make 500 MeV KAS drive electron beam Cost reductions thru hardware reduction ~30 km of low emittance, damped beam added to RTML systems Ongoing discussions that have lives of their own 7

8. Undulator Scheme Positron System Site Layout Discussions: September, 2006 Impact to ongoing work for ILC Undulator Scheme: No real changes to the technical challenges No parameter changes Reduction of transport lines Rework of injection/extraction schemes Still have same technical challenges and cost drivers Work continues 8

9. Undulator Scheme ILC Positron System Design and R&D Goals in Support of the TDR Abstract: Detailed positron systems designs and documentation are required for the ILC TDR by the end of FY09. The goal of the research and development for the ILC positron systems is to learn enough about the component and subsystem technical requirements such that the scope of the resource requests in the TDR are adequate and not excessive. Included in the R&D list are key enabling technologies. Detailed systems integration, design, and engineering for manufacture are not considered herein. Fabrication of production prototypes is to be done as part of the construction phase of the project. 9

10. Undulator Scheme R&D Tasks: Undulator OMD/Flux Concentrator Target Station Remote Handling Photon Collimation and Stops Positron Stabilization Capture RF Systems Fast Ion Instabilities Documentation: TDR 10

11. Undulator Scheme Tasks: Undulator Demonstration of undulator performance with a standard module: Up to 200 m of helical undulator with K=1, l = 1 cm, and inner diameter > 6 mm is required. The undulator is a superconducting magnet design and is made from modules which are 2-4 m in length. The goal is this task is to select a technology (Nb-Ti or Nb-Sn), specify the performance characteristics (K value, aperture, length, tolerance), build and measure the performance of a prototype magnet. A beam test may not be required. 11

12. Undulator Scheme Tasks: OMD/Flux Concentrator A viable OMD: pulsed/shielded and or dc/immersed: A strong (~7T), axial magnetic field at the exit of the conversion target is required for efficient capture of positrons. The device is called the optical matching device (OMD) and serves essentially as a point to parallel focusing element. Two candidate technologies are presently under consideration: a pulsed flux concentrator and a superconducting coil. In the former case, the magnet filed rises rapidly (~5mm) from zero to full strength immediately downstream of the target. In the latter case, the coil sits upstream of the target and the field penetrates the target. It is likely that a pulsed device can be based on previous designs which need to be improved for reliability. If the issues associated with spinning the conversion target in a strong magnet field can be successfully handled, the immersion of the target in the field offers an improvement in positron capture efficiency by as much as 40% over that possible with the field profile of the flux concentrator. Because of the uncertainties in both candidates, it is recommended that both technologies be studies and developed. 12

13. Undulator Scheme Tasks: Target Station Rotating target assembly compatible with OMD choice: The positron conversion target is a 1 m diameter annulus which spins at about 2000 rpm. Approximately 30 kW of average power deposited by the beam and perhaps a similar amount of power due to eddy currents from the OMD must be removed. The goal of this project is to develop a prototype water cooled, spinning target and to test the performance of the system along with a functioning OMD as chosen in task 2. 13

14. Undulator Scheme Tasks: Remote Handling Remote handling strategy and task descriptions: The beam power in the ILC positron vault is in the range of 350 kW. The target and much of the downstream accelerator components and ancillary infrastructure will become activated. To facilitate maintenance and repair, it is necessary to develop remote handling techniques and systems for this area. It is likely that much of what is required can be adapted from facilities which have similar issues, such as the SNS, ISIS, various hot cell facilities, and perhaps reactor installations. It is recommended that existing remote handling facilities and techniques be studied for application and unique needs for the ILC positron vault be identified. A strategy for remote handling must be developed and a design for this capability needs to be developed and fully integrated into the positron system. A simulation of component and vault dose and activation is required. 14

15. Undulator Scheme Tasks: Photon Stops and Collimation Photon stops and photon collimation: Positron polarization can be enhanced by collimating the incident gamma beam. Some designs call for cutting as much as 50% of the incident photons which corresponds to an average power of up to 175 kW. As a separate issue, it is necessary to collimate large angle gammas along the length of the undulator to prevent unwanted energy deposition along the undulator. While the power levels are reduced from that of the main photon collimator, the spectrum of the photons is similar to those absorbed by the main collimator. The goal of this research is to develop the photon collimator and photon stops, prototyping and testing as necessary. 15

16. Undulator Scheme Tasks: Positron Stabilization Stabilization schemes: intensity control, fault recovery: Positron intensity fluctuations arise from variations in the drive electron beam intensity as well as due to drift and jitter in the positron system itself. The goal of this task is to identify all potential sources of intensity jitter, invent solutions and work arounds, and to develop hardware as necessary. 16

17. Undulator Scheme Tasks: NC RF Normal conducting structure demonstration of achievable gradient and power handling capability: (separate presentation if time permits or will add to meeting notes) 17

18. Undulator Scheme Tasks: Fast Ion Instability Fast ion instability mitigation in undulator, as required: (Expect this to be resolved in FY07; presently have a vacuum specification of 100 nTorr which is under discussion) 18

19. Undulator Scheme Tasks: TDR Development Positron System Design and Optimization: Positron accelerator system design and optimization studies. The goal of this task is to produce the positron system documentation required for the ILC TDR. This goal includes complete specifications for all aspects of the positron system and full integration with the ILC. 19

20. Undulator Scheme Challenge: The foregoing need better definition in terms of work packages; need to do what is required for the TDR, need to push off what can not be accomplished into construction. Need to avoid duplication if possible Need to run in parallel as needed Important to develop and implement a global entrerprise 20

21. Undulator Scheme 21

22. Undulator Scheme 22