1. June 16, 2009 Today: Updates on Mitigations KEK – Y. Suetsugu Updates on photoe- estimates by Synrad3D – K. Harkay CesrTA last run and updates on mitigations – M. Palmer DR Working Group plans

2. June 16, 2009 WG Main Deliverables Recommendation for the reduction of the ILC Positron Damping Ring Circumference Recommendation for the baseline and alternate solutions for the electron cloud mitigation in various regions of the ILC Positron Damping Ring. by March 2010 by Late 2010 Characterization of electron cloud at different bunch spacing: 6ns and 3ns by 2010

3. June 16, 2009 Working Group plans Goals of the LC DR Working Group: To give a recommendation on the feasibility of a shorter damping ring by comparing the electron cloud build-up and instability for the 6.4km and 3.2km rings with a 6 ns bunch spacing. DONE: March 2010 by ECLOUD’10 then following the CesrTA program: –1) evaluate the electron cloud in the shorter 3.2 km ring with a 3 ns bunch spacing. –2) give our recommendation on electron cloud mitigations. Furthermore starting late 2010, to fully integrate the CesrTA results into the Damping Ring design.

4. June 16, 2009 Build up simulations We run simulations for both ring configurations 6km and 3km with 6ns bunch spacing: IPAC’10 paper: WEPE097 paper in preparation, submission to journal Next: 1) In 3km ring, run with 3ns bunch spacing 2) fill pattern?! Discussion. 3) Then: need to include refined estimate of photoelectron production rate by SYNRAD3D. Kathy, Laura and Gerry are working on estimates for the ILC Damping Ring.

5. June 16, 2009 Mitigations Table for ILC Damping Ring DR element% ringAntechamber need CoatingMitigationAdditional Mitigation DRIFT in STRAIGHT 54NoSolenoid DRIFT in ARC 33Downstream of BEND only Solenoid BEND7Yes WIGG3Yes QUAD & SEXT 3Downstream BEND / WIGG Color code: Green = defined, Red = not yet defined. Goal is to define mitigations by 2010 or early 2011 as input for ILC TD Phase 2.

6. June 16, 2009 Mitigations Table for ILC Damping Ring DR element% ringAntechamber need CoatingMitigationAdditional Mitigation DRIFT in STRAIGHT 54NoNEG & Carbon SolenoidGrooves DRIFT in ARC 33Downstream of BEND only NEGSolenoidGrooves BEND7YesTiNGrooves WIGG3YesTiNClearing Electrodes QUAD & SEXT 3Downstream BEND / WIGG TiNGrooves Color code: Green = defined, Red = not yet defined. Goal is to define mitigations by 2010 or early 2011 as input for ILC TD Phase 2.

7. June 16, 2009 Presentation of the Work at ILC Damping Ring Meeting The Working Group will present a recommendation for mitigations to a Damping Ring meeting and a decision will be then made for the baseline as well as for alternate solutions. The mechanism for the decision remains yet to be defined. Within the damping ring group, a decision could be taken by means of a voting system based on scaling factors (example: mitigation costs, effectiveness, durability, maintenance etc.) to be defined.

8. June 16, 2009 A document produced by the Working Group by late 2010 early 2011, including: the research work, the recommendation on mitigations, the recommendation process and a clear set of criteriae that lead to the recommendation. Report Document on Mitigations and Recommendation for ILC DR

9. June 16, 2009 Report Document on Mitigations and Recommendation for ILC DR

10. June 16, 2009 Our presentations posted on web site ILC Damping Ring Wiki: https://wiki.lepp.cornell.edu/ilc/bin/view/Public/Dampi ngRings/https://wiki.lepp.cornell.edu/ilc/bin/view/Public/Dampi ngRings/ ILC Damping Ring Teleconference page: https://wiki.lepp.cornell.edu/ilc/bin/view/Public/Dampi ngRings/TeleConferencehttps://wiki.lepp.cornell.edu/ilc/bin/view/Public/Dampi ngRings/TeleConference

11. June 16, 2009 Link to all our presentations here

12. June 16, 2009 Past ILC DR WG meetings

13. June 16, 2009 WebEx meeting Proposed time Next meeting: –Wednesday 14 July 2010

14. June 16, 2009 Blackboard Messages board Messages here