1. ALCW15 Mike Harrison AD&I and Change Request status

2. Design Considerations 2 At present we have the site specific design and SRF technology development as the two broad program goals. Design changes that have CFS ramifications are given priority We are trying to implement design changes that improve the machine and result in cost reductions or cost neutral at worst Not much value engineering, no DR work, no electrons No new cost estimate on the horizon Overall schedule uncertain ALCW15 Mike Harrison

3. TDR baseline is under change management control ILC Accelerator Design: Post-TDR Updates Propose (Creator) ReviewDecideImplement CR-001Add return “Dogleg” to target by- pass 2014/08/27 (K.Yokoya) doneRejected CR-002Adapt equal L* for both detectors2014/09/02 (G. White) doneDiffered to Review Panel L* to be settled to ~ 4.1 m CR-003Detector hall with vertical shaft access 2014/09/16 (K. Buesser) doneAccepted CR-004Collision point timing adjustment & tunnel extension 2014/12/18 (N. Walker) In progress PipelineCryogenic layout, tunnel X-section ProposalExpert reviewDecisionDocumentation update ALCW15 Mike Harrison

4. Change requests ALCW15 Mike Harrison

5. CR-004: Collision point timing The Charge …..Your charge is essentially to look at all aspects of the problem (including tolerances) and propose a practical solution which can then be integrated into the baseline design. The key aspects are :  Proposing a realistic scheme which maintains the overall IP collision timing constraint  Explore any possible constraints on the allowed bunch patterns in the damping ring (flexibility)  Understanding the tolerances for the required path length adjustment(s): static - a ‘one time’ correction concept for an survey (installation) error for the path length dynamic - dealing with ‘drifts’ (both ‘slow’ long term as well as any relatively fast corrections required) ALCW15 Mike Harrison

6. CR-004: The numerical condition Length (DR ejection -> IP) – length (target -> IP) + length (target -> DR injection) = n * DR circumference For a given DR circumference: ML length is quantized by ½ DR circumference (~1.5km) ALCW15 Mike Harrison

7. CR-004 proposed change 7 It is proposed to extend both the electron and positron main linac tunnels by approximately 1.5 km (total machine length approximately 3 km). For the baseline the additional tunnel length will be filled with simple passive beam transport lines. The additional tunnel length will be used to: adjust the total beamline path length on the positron side by 2946.x metres in order to fulfill the timing constraint imposed by the baseline method of positron production; Allowing for a possible increase in the length of the linacs allows some additional margin in both achievable average accelerating gradient and top-end energy reach of the machine, and significantly reduces the risk of not achieving 500 GeV cm. The path length adjustment (i) is consistent with the existing TDR damping ring design (circumference) and bunch patterns, and while potentially not the cheapest solution, when taken together with (ii) appears to be the more straightforward approach. ALCW15 Mike Harrison

8. CR-004 proposed change 8 The main issues with respect to CR-4 are: Increased Tunnel Length - Increase in cost ( € 80M ) Additional beam transfer line w/magnets - Increase in cost ( € 20M ) Relocation of horizontal access tunnels - initial review indicates a cost neutral solution Cryogenic system - currently unchanged from TRD design - cost neutral Additional access point - unlikely ALCW15 Mike Harrison

9. Change Request Register 9 CreatorPrimary WGsTitleDescriptionState N. WalkerBDS / MDIAlternative FF scheme removing strong sextupoles from FD Consider alternative FF schemes which would remove the strong sextupole magnets from the FD. Under consideration B. ParkerBDS / MDI / CFSReduce IR crossing angleDevelop hilghly-compact SC FD to allow for smaller crossing angle. Removed BDSAdopt Kamaboko-style solution for BDS / central region Replace separate service tunnel with Kamaboko-style solution Under consideration N. WalkerMDIIntegrate laser wire(s) into IR region (detectors) Incorporate one or more laser wire system in into the detectors ± some distance from the IP to facilitate accelerator tuning. Under consideration N. SolyakSRF / MLImplement cost-effective PDSUpdate current PDS design to a cheaper simpler alternative Under consideration A. YamamotoCRYO / MLRelocate cryo components to surface Move compressors and helium storage to surface sites (requires long transfer line). Under consideration M. KurikiPS / CFS / PHYS300-Hz e-driven sourceAdopt 300-Hz e-driven positron source as baselineUnder consideration ?CFSReduce the width of Kamaboko shield wall Reduce the width of the ML tunnel shield wall in accordance with defined radiation safety protocols Under consideration LCBML / CFSImplement design for energy staging. Effectively develop lattice / CFS design for first-stage 250 GeV cm operations. Removed G. WhiteBDS / MDIMove FFBK kicker downstream of QD0 Locate intra-beam FFBK downstream of QD0 (inside detector), to effectively increase FD vibration tolerance correction range. Removed G. WhiteBDS / MDIAdd BPM downstream of QD0Add a BPMs immediately downstream of the QD0s to facilitate beam capture and construction of a "virtual IP BPM". Under consideration ALCW15 Mike Harrison

10. 10 H. HayanoSRFAdopt Saclay-like tuner as baselineAdopt LCLS-2 tuner and associated helium tank and flange solution. Under consideration E. PatersonPSAdd timing adjustment chicance system Implement a timing adjustment chicane in the positron injection system to allow for fine path-length adjusment. Under consideration G. WhiteBDS / CFSLength adjustment of BDS latticeRelease of new lattice after review and subsequent development. Under consideration G. WhiteBDS / CFSInclude beta matching sectionAdd a dedicated beta matching lattice section to aid tuning (similar to ATF2) Under consideration E. PatersonDRModify circumference of DRAdjust circumference of damping ring to accommodate global timing constraint Removed N. WalkerDRAdd RF and wiggler for high current 10Hz operation Configure DR designs to accommodate 100ms dampng time with 2625 bunches to allow for 10-Hz collisions after the luminosity upgrade. Under consideration N. WalkerMLIncrease bandwidth of extraction lines in BC Review operational requirements of fast extraction lines and dumps and re-design appropriately. Under consideration N. WalkerML / CFSChange in average gradient specification in ML Adjustment of baseline average accelerating gradient in the main linacs. Under consideration N. WalkerMLModify lattice for staged implementation Lattice design for the first-stage 250 GeV machine.Removed H. YamamotoML / CFSExtend max. energy reachExtend maximum energy range of the machine to 550 GeV centre of mass. Under consideration Wei GaiPSExtend undulator length to 230m as baseline Remove need for 10-Hz production mode at 250 GeV centre-of-mass energy Under consideration Wei GaiPSAlternative target designAdopt alternative photon target designUnder consideration H. HayanoSRFMagnetic shield inside helium tankPlace magnetic shielding inside helium tank to simplify string / cryomodule assembly. Removed D. RubinDRReduce number of BPMsReduce the compliment of BPMs in the DR latticeUnder consideration D. RubinDRLoosen multipole tolerance specs.Update magnet specifications to reflect allowable looser tolerances on magnet multipoles. Under consideration ALCW15 Mike Harrison Change Request Register

11. CR – ??Cryogenic Concept From Nakai et al ALCW15 Mike Harrison

12. CR-xxCryogenic Concept From Nakai et al ALCW15 Mike Harrison

13. CR - ??Tunnel X-section From Enomoto et al 3.5 m baseline shielding wall arose from the requirement of personnel access during beam-on operations. This arose from reliability arguments including those related to the HLRF More on Tuesday ALCW15 Mike Harrison

14. CR – ?? Beam Delivery System single tunnel 14 SW3.5m % PAC Paris April 2015 Mike Harrison

15. 15 Positron production remains an issue The R&D program was suspended when the US effort was terminated post-GDE. We had not shown a working target due to failures of the ferro- fluidic vacuum seal ALCW15 Mike Harrison

16. Sliding Contact Cooling Heat Transfer Demonstration – Argonne Lab proposal Sliding Contact Cooling 2x Infrared Thermometer 250 watt halogen lamp ALCW15 Mike Harrison