ATF2 review R. Tomas ATF2 review web:https://ilcagenda.linearcollider.org/internalPage.py?pageId=1&confId=5973

Contents ATF2 Goals ATF2 review CERN contributions Support needs for ATF2

Evolution of ATF2 Goals Original goals from ILC TDR phase: 1. Achieving 37 nm 2. Stabilization to nm level Re-interpreted by the ATF2 collaboration 1. Achieving and maintaining 37 nm over long periods 2. Orbit and jitter stabilization to nm level with ILC beam

The ATF2 review O. Napoly A. Yamamoto A. Seryi R. Tomas B. Barish K. Oide N. Walker M. Ross A .Chao

ATF2 review: all participants

ATF2 review: General statements “...The extensive upgrades and improvements to the machine itself, including critical sub- systems such as the IPBSM, together with the organized approach to shifts and personnel training, have resulted in significant gains in terms of understanding and characterizing the accelerator, resulting in a best-recorded beam size of 64 nm.”

Goal 1: 37 nm Reached 64 nm Tuning from ~3000 nm Suppression of aberrations confirmed to about ~90% Bunch charge ~109 e-!! Goal 1: 37 nm Review assess.: “...successful demonstration of the compact final focus optics and both the linear optics tuning and high-order aberration compensation schemes involved.”

Goal 2 Goal 2 needs nominal bunch charge ~1010 e- But this is seriously under threat by the “wakefield” problem → This needs special attention (Goal 3?) “There is a danger that the program becomes a demonstration of nm BPM technology... more details are needed... what exactly will be measured and quantified.” “Moving high resolution BPMs to a location upstream (exit of the EXT line) would aid in separating injection from FFS jitter sources. Installation of vibration sensors would further help characterization of jitter sources by separating mechanical (i.e. vibration) from wakefield driven sources.”

Severe budget cut Barely enough for operation and the replacement of the IP chamber in summer.

Recommendations for the ATF2 future Beyond the existing (GDE) ILC goals... The plans for the ultra- low beta* optics should be pursued. Although the committee recognises this is being driven by a CLIC demonstration, these parameters are clearly also useful for any linear collider, including ILC. The more demanding vibration suppression and ground motion measurement will equally provide additional margin for ILC. A further ILC-specific programme would be to reconsider the tests of the superconducting final doublet. This is a critical component for ILC, and the ATF2 offers the only true possibility to measure the magnetic field vibration at the required level.

CERN-LAPP ground motion sensor system LAPP bought 15 sensors (A. Jeremie et al) CERN puts the DAQ (Kurt et al) and the simulations (Yves et al) System commissioned in Annecy Equipment already operational in KEK

Andrea Jeremie & Yves Renier

CERN contribution to commissioning Hector, Juergen and Yves joined the December commissioning They also carried out parallel studies: Damping ring optics, Yves Jitter source identification, Juergen and Hector We should think on how to continue this activity, Yves and Hector leave in 2013, Juergen leaves ~June 2014.

Ultra-low beta* and new QD0 based on CLIC technology? Current QD0 is OK for nominal ATF2 optics For ultra-low beta* there are 3 options: Increase beta_x → σy = 23 nm Replace QD0 → σy = 26 nm New! 2 new octupoles→ σy = 23 nm

Support needs for ATF2 Fellow and PhD student for fall 2013 (need fast learning, candidates? ) Shall we/Can we increase contribution to commissioning? Magnets for Ultra-low beta* under consideration Addendum to existing MoU under consideration too