Charge for the Technical Board Members of the Tesla Technology Collaboration (TTC)

1. Technical Board MeetingTESLA Technology Collaboration Meeting Fermilab, April 19th – 22nd, 2010

2. Charge for the Technical Board Members of the Tesla Technology Collaboration (TTC) • According to the MoU of TTC the Technical Board TB shall provide advice to the Collaboration on technical activities towards reaching the goals of the Collaboration Mission. To this end, the TB will • compile information on the technology activities in different technical areas, • provide findings and recommendations to the CB. • … • The TB can be described as the technical arm of the Tesla Technology Collaboration, TTC. As such its primary duties are to carry forward the technical program of the TTC. • Much of the work to the TTC is carried out in, and as a result of, the semi-annual meetings of the TTC. Working Groups focuse on technical items of current interest as defined by the CB. The TB will discuss and lay plans for advancing the issues under consideration. • … • Some activities of the TB and its members will be self-assigned while some will result from responses to requests from outside by leaders of the various projects which depend on superconducting RF.

3. TTC Technical Board Cavity: P. Kneisel (JLAB) L. Lilje (DESY) D. Reschke (DESY) K. Saito (KEK) R. Laxdal (TRIUMF) Coupler:E. Kako (KEK) W.D. Moeller (DESY) Module: N. Ohuchi (KEK) C. Pagani (INFN)Paolo Michelato B. Petersen (DESY) T. Peterson (FNAL) Linac and and Integration: H. Edwards (FNAL) S. Michizono (KEK) (S. Simrock ) new LLRF person needed! H. Weise (DESY) Chair Ex-Officio (per TTC MOU) Spokespersons of major test facilities TTF / FLASH: S. Schreiber ILCTA-NM (old SMTF): S. Nagaitsev STF: H. Hayano

4. TTC Technical Board Guests: Axel Matheisen (DESY) Lucija Lucovac (LAL Orsay) Marc Ross (FNAL + ILC) Nobu Toge (KEK + ILC) Y. Yamazaki (J-PARC, KEK&JAEA) J. Mammosser (SNS)

5. General studies / common topics At the last TTC Meeting the TB decided to support the HF free electro polishing studies done at INFN Legnaro. CEA Saclay had/has also interest in further EP R&D and is looking into Buffered EP. For the latter R&D line see the talk of F. Eozenou / Saclay. For the first we unfortunately have no recent information and hope for the SRF workshop. Nothing new? Have a look at yesterdays KEK contribution…. Comparison of “standard” EP recipies between KEK and JLAB; lower current density and longer EP; additional info exchange with DESY planned; no conclusion yet but go on with the work! DR: U.S. company mentioned new EP method… Excitation of other pass-band modes was observed in many cavity tests. So far there is some understanding of the excitation mechanism. KEK and DESY have presented their findings. The DESY results are going to be published at the SRF workshop. The TB suggests to consider a summary report given at the next TTC Meeting together with a TTC Report. It didn’t make it to the agenda… DESY “switched” to pulsed mode vertical tests… seconds on/off KEK, not visible for LL FNAL is aiming for cw operation with high Q, does it become an issue again? LLRF people were worried about too; source seems to be field emission

6. General studies / common topics Since the last TTC Meeting some progress was made wrt. pressure vessel certification. We have some additional information from all three regions. The TB will ask the relevant TB members to take care of the preparation of an overview at the next TTC Meeting. Participation in ILC GDE discussions is assumed. Ongoing discussions… a lot of work done at DESY… but needs more time… re-schedule it for the next TTC Meeting! FNAL guidelines; e.g. methods and requirements for testing of Nb and also for the dressed cavity, stainless steel vessel; could be described during next meeting SNS different strategy – certifying vacuum vessel as pressure containment; they use this approach for the upgrade JLAB; looking at different material – large grain… KEK activities in the frame of three projects; material studies on-going At least a summary of different approaches should be given OR even several presentations S1 Global found a way to deal with the certification issue, but ILC GDE has to come back to the issue Field emission: Calibration procedure for existing Vertical Test Stands, i.e. a calibration source. Marc Ross is going to check if FNAL can work on this. Was it done? FNAL horiz. test has Faraday Cup measurement attached; closely related to definition of operational gradient; relation between radiation and current measurement; operation of cavities close to the limit, f.e. and radiation emission (see also 9 mA test at FLASH) Around 2005 an overview about existing Cavity Preparation Infrastructure was produced. Since then two tables were established (KEK and within CARE, the EU funded projects). An update should be made for the next TTC Meeting with the help of the tables’ authors. Here we “failed”… overview talk at next meeting

7. General studies / common topics (cont.) Two statements from the last TTC Meeting: Whenever projects arrive on the real axis some excellent R&D plans have to be stopped or paused. The TTC Meetings should be used to present the status of such activities with the hope that the baton can be passed to ‘some good friends’ in the SRF community. The TB would be happy to include more low beta cavity issues. As also discussed in the Collaboration Board the TB’s expertise should be strengthened as soon the relevant colleagues become regular participants of the TTC Meetings. Open discussion….. - f.e. measurement in vertical tests; DESY will measure the radiation at both(!) cavity ends • Which data can TTC expect from the larger scale cavity/coupler/module production of e.g. XFEL? • Comparison of cavity behavior for the first vs. the n-th power rise/cycle • Which systematic measurements could be added to the “simple” gradient and f.e. / Q check during module tests? Try to record processing events… what can be done in the time given for the module test? Can one define standards for module tests? • More systematic simulations wrt. characterization of defects; review during next meeting? • Mechanical grinding • Power Coupler: discuss cleaning; also for the HOM coupler • CW coupler for high beam power; who is working on it? • Low beta: FRIB approx. 350 cavs; medium field Q-slope; different treatments known from beta=1 are still to be tried out for low(er) beta • Re-activate “old” topics (linac integration, LLRF, operation of srf linacs); system integration