108th ATF2 weekly meeting

July 22 14:30- 18:00, ATF LC meeting room, KEK.

International phone/webex meeting

Stripline BPM electronics study, Yves Renier (LAL)

file : pdf (pdf, 23 pages, 2.2 MB)

Y.Renier reported test results of stripline BPM electronics which were used for the 12 BPMs. The electronics is consisted of head amp circuit ( band-pass filters and amplification ) and clipping circuit (i.e. unipolar circuit).

The clipping module has an input switch and three amplifiers with bias adjustments by potentiometers. All the bias voltages were observed to be below 5mV. The first and third amplifiers are inverters and a positive clipping is done by the second voltage limiting amplifier. Nominal input is a negative pulse, whose polarity can be changed by the switch. The input polarity should be chosen for the real configuration of BPMs.

The performances were checked with the test pulser, whose amplitude and width were -840mV with overshoot of +360mV and about 3nsec, respectively. Test pulses were input to the calibration in the head amp, then the outputs were input to the clipping circuit. All the output signals were checked by an oscilloscope. Results are listed in a following table.
CircuitHead ampClipping
Channel nameVmin(mV)Vmax(mV)T (ns)Vmin(mV)Vmax(mV)T/2 (ns)
MQF1X X1-51048018-400109
MQF1X X2-51048018-400189
MQF1X Y1-51048018-400189
MQF1X Y2-52048018-400-2010
MQF4X X1-10010026-1002012
MQF4X X2-15013028-502515
MQF4X Y1-16013028-1004212
MQF4X Y2-18014028-803212
, where the Head amps of MQF4X have no stick written "filter skip" while others have same behavior. So, those of MQF1X and MQF4X are listed as each representatives .

In conclusions, all head amp circuit has been looked at and seems equivalent, except the ones of MQF4X which have lower outputs and lower frequency. The performances of MQF4X have been the worst during last runs. All clipping circuit seems to be set configured for BPMs in the same direction, but they are not.

In future plan, I would like to continue this study on all BPMs :

Once done, I would like to see what is the signal induced by the kicker, and how it is problematic.
Q : Are the clipping circuits of MQF4X have good performances, while the head amps of MQ4X are differently configured ?
A : I will check them.
Q : Did you check three clipping circuit II modules which include head amplifiers ?
A : No, since they have shown good performances.
Q : The pulser always outputs with 63dB attenuator. So, I had to press the button for the good pulse amplitude during the tests. Is there any way to remove the attenuator ?
A : We must look at the pulser which has been designed by H.Hayano.
C : Looking at the device list, three BPMs of MQD5X, MQF6X and MQF9X are located at upstream of magnets, while others are set at the downstream.
C : Yves's observation for bad behaviors are MQF4X of "very Bad in Y, non-linear", MQF6X of "did not succeed BBA", and MQF9X of "really strange, need further study".

Discussion of beam schedule in 2009

Personal strategy for ATF2 beam operation in 2009, Toshiyuki Okugi (KEK)

file : ppt, pdf (pdf, 5 pages, 140KB)

Installation plan in this summer shutdown, Nobuhiro Terunuma (KEK)

file : ppt, pdf (pdf, x pages, xxx)

Okugi briefly showed his strategy for beam studies by end of this year, 2009.

In 10/19-23, fast kicker and DR BPM test.

In 10/26-10/30, beam extraction with the nominal kicker, hardware checkout of the stripline BPMs with high pass filters which have been orderd by Naito (checkout of new readout electronics of stripline BPMs ?) Also, studies of QBPM since the calibration constants have changed in every day, say 10%/day, which are expected to be stable. We need studies of the stability, in particular. Septum rotation check by beam, and Shintake monitor background test with new chamber with larger aperture in the last bending magnet, tuning of ref. detector of BSM bkg.

Since there will be many hardware commissioning/checkouts, the ATF2 beam tuning studies are not approriate in October.

In Nov. 1st week, optics study with new wire scanner at IP in the IP-chamber for 1-2um beam size. Also, there are FONT and LW studies.

In Nov.2nd week, again studies of QBPMs, IP-BSM with 1 -2 um beam size, and the interference mode will be studied.

Dec. 1st - 3rd weeks, C-band and S-band BPMs must be established with respect to their stabilities. Also the interference mode should be established for sub-um beam size. We aim an establishment of the high beta optics tuning. We must understand background as a function of beta* in Shintake monitor. There will be FONT and LW studies.

After the 2009 operation, there will be decision of the beam optics for 2010 operation. We need improvement of the IP-BSM DAQ to be used for beam operation for every colleagues . We may have installations of the multi-OTR chambers and the new readout electronics for all of the stripline BPMs if necessary.

Finally, a target by the end of 2010 spring run is the beam size measurement of < 100nm .

Q : How do you measure 1 -2 um beam size at IP?
A : We can measure it up to 2um by 10um W wire.
Q : How do you think kicker test in January ?
A : Naito, Terunuma and Okugi think that the fast kicker study is important in Oct.
Q : If so, there will be no ATF2 work in October. The goal can not be achieved in this year.
C : Yes. In general, Okugi's strategy is good for ATF2. However, the time is short. If the 2nd week in October is used for the hardware checkout, there will be no ATF2 beam tuning in October.
C : First we need commissioning of hardwares. So far difficulties are related with hardware problem, i.e. BPMs were not well calibrated. The checkout runs can be done before the October's run.
Q : How do you check septum rolling by beam ?
A : The stripline BPMs will be used to measure the orbit, i.e. vertical bend.
Q : Will be septum rotated, then measure by beam ?
A : Yes, the rotations will be small (a few m rad), but it takes time to remove a lot of lead blocks. So, the test should be in the beginning.
Q : On the issue of vertical dispersions, recent conclusions seem to be different (from those at the project meeting)?
A : We can separate issues of large vertical orbit and vertical dispersion if we don't run out of strength in ZV1X for the orbit correction. To find sources of vertical orbit, we will study by changing the kicker current and changing DR optics to see sources in DR.
C : Although the septum rotation will not generate vertical dispersion, the vertical orbit may cause worse at off-axis of QF1X etc. .
C : We need another knob for residual vertical dispersion correction, such as Kubo's bumps .
Q : Do we expect beam size changes from the septum rotation ?
A : It depends on the multiple component of septum.
Q : What is the priority in 2009 ?
A : We all agree with the sub-micron beam by December, 2009.
Q : Additional knob or additional Skew-Qs ?
Terunuma shortly reported the hardware preparation in this summer.

DR-BPMs have no replacement in this October. They will be upgraded after December. Following installation is prepared in this summer shutdown;

Q : What is the resolution of new PSs ?
A : They will be controlled by PLC. The resolution will be 14 - 16 bits, while the present one is 10 bits .
C : For better resolution, we need choose steering magnets , e.g. FONT .
Q : Including checkout runs for hardware, shall we ask TB for the schedule or discussion at ICB meeting, ALPG09/GDE meeting, 9/29-10/3 ?
Q : Is there extension ?
A : We can extend ATF operation for ATF2 beam studies in December 21 week if needed.
C : We need three month schedule at least.
C : First, new stripline kickers will be tested at EXT in checkout runs, i.e. 1 or 2 days just evening run or day shifts before this October run. Then, The 1st week October will be dedicated run to the fast kicker in DR.
Q : What impact of the checkout runs ?
A : If results are not good, it will not be installed in DR.
Q : In that case, many oversea colleague will not be there since it is already scheduled as the fast kicker study.
Q : Can we have the fast kicker tested at LINAC?
A : It may be possible.
C : There is no good BPMs to detect orbits at LINAC end.
In summary, we have agreement of the goal in 2009, that is, experimental verification of beam size at sub-micron with the interference mode of Shintake monitor. Therefore, we should evaluate schedule in details as much as possible. So, we would like to suggest that Philip ad Okugi will make such a plan and discuss at the weekly meeting, 12th August.

Others

Status of stripline BPM electronics will be presented by SLAC colleagues. G.White will ask engineers for availability.

As SLAC colleagues know, there is a problem of "Interlock Summary Board" for the injector kicker. There have been e-mail exchanges for a month since end of June. The progress is very slow. This issue will be resolved by sending the spare boards which are working at SLAC. We would like to ask A.Seryi for helping the spare board.

A : The spare will be provided from SLAC.
C : This is an important issue for the ATF international collaboration. We expect a quick handling by SLAC, since it is the SLAC responsibility to be written in the MoU.

KEK site meeting

file :Yamanaka's ppt, Yamanaka's pdf (4 pages, 268KB)


Beam_Time_Simulation ppt, pdf, (13 pages, 404KB)