110th ATF2 weekly meeting

International phone/webex meeting

Installation status of the HLS system, G. Gassner, M. Masuzawa, R. Ruland, M. Satoh and R. Sugahara

M.Masuzawa reported the installation status of the HLS system.

Preparation has been started in mid July. Installation was done in a week of 3 August with Georg Gassner ( SLAC ), providing 5 sensors from SLAC. After test run with small modifications, a long run started since 11 August, 2009.

5 sensors are set at intervals of 6 to 9m, which are close to QF16FF, QM11FF, QF7FF, QD4AFF and QD2AFF, respectively, in total length of about 35m. The test run data show clearly tidal variations in vertical direction for 4 days and small earth quake as well. Also, they measured a slightly large earthquake with intensity 3 in Tsukuba, 20:35, 9 August, for the data acquisition at every 2 seconds.

In future, the measurement will continue, and we will report results periodically. Also, we will integrate the HLS system with the ATF2 EPICS database so that we can use the mover position data. More sensors may be installed.

Q : Are there sensors on the floor ?

A : No now, we like to have them on the floor.

Q : How much is the resolution ?

A : 2um is easily obtained.

Q : Is there any systematic effect ?

A: Such effect is already subtracted.

Q : Data (variations of height at 5 sensors) look converse in the test run period.

A : We will see if they are real in long run.

Q : Do you continue the measurement ?

A : Yes.

C : This is a nice work !

Schedule for end of 2009 : Discussion

Strategy of Shintake monitor commissioning, Yoshio Kamiya (Icepp, the Univ. of Tokyo)

Y. Kamiya reported the strategy of Shintake monitor works, assuming total 5 weeks for machine time in 2009.

We would like to request successive 3 shifts ( 24h) in every week. The beam tuning will be requested in every first 6 hours, which has been done in previous runs by T.Okugi.

In the first week, signals will be confirmed from each laser beam together with the calibration of new background monitor and the fine adjustment of laser optics.

In the second and third weeks, the interference modes will be studies with 4.5 degree crossing angle. For greater than 50% modulation, vertical beam size of less than 1 um is required. The beam tilt angle must be 1 mrad for 20mm diameter collimator in front of the detector. Also, the S-band and C-band BPMs must work for the beam tuning.

In the last 2 weeks, performances will be studied systematically with respect to fringe movement/stability, beam intensity, coupling corrections etc. . The post IP carbon wire scanner is important for the beam tuning, specially for providing stable/reproducible and small beam to Shintake monitor.

Finally, when the beam size becomes less than 300nm, 30 degree crossing angle scheme will be tested.

Q : Is there a new wire scanner at IP, which you did not mentioned?

A : Yes, it is included in the first week studies.

Q : You stress the importance of post IP wire scanner and BPMs . It can not measure the 1um beam. So, the new wire scanner at IP position is better, why not use it?

A : Since the post IP wire scanner has been commissioned, it can be used for the beam tuning.

C/Q : There are many new instruments in Shintake monitor. Will they be commissioned in the first week ? It may need more time.

Q : Do you expect better resolution with LW mode in coming run?

A : It should be the same as before.

Q : Will be the next run with new laser system which has 3 more intensity ?

A : Yes.

Q : In the 5 weeks, how do you distribute your shifts ?

A : We did not discuss yet, we will do later.

Q : Are there background studies with respect to beta function ?

A : I would like to ask others for the studies.

A : We will install a new background monitor.

Q : Why did you choose 4.5 deg. ?

A : In this degree, laser beam can go through the center of the prizm which is good.

Q : What kind of wires do you use at new IP wire scanner ?

A : They are 10um tungsten wires.

Q : How do you expect signal enhancement with 4.5 deg. to see the fringe pattern (when the beam size is unknown) ?

A : First we try vertical scan, then waist scan.

Q : Can we go to the beam size of less than 1um?

A : Yes, with beta-y=1cm, the beam will be focus to 300nm.

A : Also, the carbon wire scanner is important to confirm micron-meter beam size.

C : Hardware responsibility of QBPMs is UK group led by Stewart, who will come to KEK in this September. So, we will ask him for details.

C : The carbon wire scanner has been made by SLAC led by Doug who will come in November.

Q : Which detector is for the carbon wire scanner ? Can we use the new detector for it ?

A : It is now designed. I am not sure when it is ready.

Q : When do you fix the design ?

A : It is under studying .

C : We need one more shift for detector study on new detectors of cherenkov counter, one new calorimeter etc. , at least.

Q : Do we need dedicated beam time for such studies ?

A : Yes, since they need signals from the laser-Comptom scattering.

Q : Why did you request just 5 weeks?

A : It is minimum.

Q : Can you have shift for 24h with three students and others ? Is there any organization in the shift ?

A : We think first 6h by Okugi, 18h divided into 2 (sub-groups) for Shintake monitor group.

Q : The beam tuning should be done by commissioning team.

Q : It will take a lot of time for commission the Shintake monitor.

A/C : We should make a joint study gradually. All study-time needs beam tuning, so all members have responsibility for it. Also, the beam size measurement should be able to be done by all.

A : We (Kamiya) do not see the interference pattern yet, so... automation of beam size measurement willl follow after 5 weeks.

Q : Why ?

A : We can not work in parallel because of manpower.

C : First, the commissioning by Shintake group, then we should gradually move joint work.

FONT run plans at ATF2, Philip Burrows (John Adams Institute, Oxford University)

P.Burrows reported FONT run plans as well as brief summary of previous runs.

It has been demonstrated that the bunch no. 3 was fed back. We have took 1 shift/week, so 5 or 6 shifts in total . In recent runs, we obtained the kick angle of 40urad and the BPM resolution of 3um with maximum beam intensity of 5 x 10⁹/bunch. However, we could not study at the 3-bunch mode.

There are following issues to be improved ; poor setting resolution of ZV6X, ZV7X, π shift in the 357MHz LO signal, low intensity and difficulty of 3-bunch mode operation.

FONT5 9-ch FB/FF board is ready to be tested in this October. New FONT BPM movers (3) by Valencia to be installed in late September. So, we would like to have 1 shift/week, i.e. 5 shifts in Nov.-Dec., 2009, at least and high intensity of 1 x 10¹⁰/bunch for the FONT studies. Also, we like to commission the 3 bunch operation.

Q : In this fall, who will come ?

A : Out visit will not be continuous. In Nov. and Dec. , 4 or 5 people will visit. So, our visit will be one month in Nov. and 2 weeks in Dec. .

Q : Do you like to have 2 shifts/week ?

A : Yes, 1 shift/week is not enough, especially for hoping the 3 bunch operation.

C : High intensity operation is common request.

Q : Is the BPM resolution with jitter ?

A : Since the resolution was estimated with 3 BPMs, the jitter was extracted.

Q : How much was the beam jitter, while the 3um resolution is good?

A : The jitter was about 5 um. Thanks for your acknowledgement of 3um resolution. But, we aimed 1um resolution. So we rather disappointed , since we tried to 1um for stabilization at IP. It becomes worse with 375MHz problem and low intensity. ( We will take a "baseband" scheme instead of the LO-based BPM processor.)

Q : Is there a milestone?

A : Yes, feedback with the new 9ch-board ( at the 3 bunch operation).

Schedule for end of 2009 for discussion, Philip Bambade (LAL & KEK)

P.Bambade presented priorities of commissioning issues in each month, which are results of discussions with Okugi-san ( commissioning team leader) and other KEK colleagues.

First he listed external participants with their visiting schedules based on e-mail exchanges. Since some one is missing, please communicate for any missing colleagues. Obviously, I will ask Daresbury colleagues .

Priorities for October :

1. Pilot runs day / evening time from October 13 to restart system and test new fast kicker and auxiliary septum with beam in ATF2 line
   -> basis for decision to install in DR for extraction test (days and evenings) in week of October 19-23
2. if YES, then in Oct. 19-23:
   - day & evening shifts for fast kicker program led by Naito-san with daily support by local KEK team
   - use night shifts for DR low emittance tuning program (with support from external visitors)
3. If YES, then in Oct. 26-30:
   - re-establish orbit with BBA, emittance and rough tuning in EXT (1 shift)
   - record stripline & cavity BPM data for calibrations & monitoring (1 shift)
   - IP setup with 8 x 1 cm optics
   -> measure dispersion, size and divergence with post-IP W wire (1 shift)
   - commission new BSM IP diagnostics incl. IP W wire, measure BSM background with respect to FD alignment & IP divergences (2 shifts)
   - FONT & LW programs (2 or more shifts ?)
   
4. If NO, then in Oct. 19-23 and Oct. 26-30:
   - same as above for ATF2 in Oct. 19-23, including DR low emittance tuning
   - in Oct. 26-30, repeat with more detailed EXT emittance and Twiss & dispersion study, more systematic IP dispersion & beta-match measurements and re-establishment of BSM LW measurement of horizontal beam size.

1. IP setup with 8 x 1 cm optics for more detailed confirmation of Twiss & dispersion
2. Post-IP C wire commissioning
3. IP spot minimization with optical multi-knobs
   -> resolution limit of 1.5 micron ?
4. BSM 8 degree interference mode study
5. Dedicated and parasitic background studies near IP, especially with respect to &beta*
6. (multi)-OTR investigations ?
7. Continued BPM studies and reconstruction
   -> precision & calibration stability ?
8. FONT & LW studies

Priorities for December :

1. Depending on November progress, many above items may need continuation
2. Decision on stripline BPM electronics based on results in October & November
3. Based on IP background study and success with BSM 8 degree mode, reduction of &beta* for optical studies and commissioning of BSM 30 degree mode ?

According to Kamiya's talk, the 8 degree is changed to 4.5 degree for the first interference.

C : cavity BPMs, IP wire scanner, post IP carbon wire scanners are important to provide beam of less than 1um size at IP for Shintake monitor. So, these hardware commissioning should be first priority.

Q : Do we understand dispersion ?

A : So far there is no good measurement. We need accurate BPM readings first.

Q : Do we have ability to correct dispersions ?

A : The sum knob with combination of a few mm bunp is effective, which was verified by simulation.

Q : I suspect the bump , near the 2nd kicker, since there are many unknown?

A : There seems to be no other solution.

Q : How about any correction in DR ?

A : There may be some at the north straight section. I am not sure how to .

C : High priority to try is the bump knob at EXT.

Q : What studies are expected as non-ATF2 ?

A : They are cavity Compton and fast ion .

C : Machine time will be 70% for ATF2 beam studies in 2009. It includes FONT and LW .

More detailed schedule will be planned by P.Bambade and T.Okugi who will daily communicate.

KEK site meeting

Q: Is it possible to move a new Cherenkov detector remotely?

A: Yes, it is not impossible. However, since it is heavy, it may be difficult with devices in hand. Furthermore it is uncertain whether continue to use a Chenkov detector.

Q: How long is the stroke of the collimator scanning stage?

A: 100 mm in horizontal and 50 mm in vertical. They are enough.

C: Cause of the laser position drift may be air temperature rather than laser cooling water. When air temperature changes, the support of the mirrors deforms and laser path changes.

C: Stabilization of the laser path will be needed to suppress the position drift.