70th ATF2 meeting
January 30 14:30- 16:30, ATF LC meeting room at KEK.
1. Minimum hardware preparation for ATF2 initial commissioning, T. Okugi
file , pdf (8 pages, 416kB)
At the 5th ATF Technical Board (TB) meeting, 21 December 2007, the TB recommended for ATF2 project as follows;
For ATF2, the single highest priority is completion of the beam line to allow delivery of beam to the dump by the end of October 2008. We note that because of radiation safety issues, any beam extracted from ATF must be transported to the dump with minimal losses; terminating the beam at some point before the dump will not be possible. Here, the main concern is that because of budget issues in the US, certain key components and the staff needed to support their installation and commissioning may not be available on the intended schedule. The components at risk include magnet power supplies, and the final doublet magnets. It is believed that even without a number of quadrupole magnets (including the final doublet) a complete transport line to the dump can still be provided, although the beam size will naturally be very large. Hence, it is likely that a plan can be developed to allow delivery of beam to the dump in ATF2, by the end of October 2008, even if there are severe budget reductions in the US. Nevertheless, delivery of hardware components from the US should be a priority, together with the necessary support from staff for installation and commissioning.
To evaluate fully the impact of funding cuts and to develop plans for mitigating the impact, a review should be performed to identify the status of each component required for ATF2, and to develop solutions to any issue that has the potential to prevent beam from reaching the dump. The results of this review should be shared amongst the ATF2 collaboration, to help to identify solutions to possible problems. The review should be completed, by the ATF2 project managers, by the end of January 2008.
In order to address one major issue in the recommendation, T. Okugi revised a previous study of commissioning strategy, 1 March 2006, focused on the minimum hardware requirement for new components at ATF2 beam line.
The minimum set of magnets are found in order to transport beam to the beam dump. It is listed below;
- 3 Bend magnets (B1FF, B2FF and B5FF) with 200A-PS
- 4 (ZH8X-10X and ZV11X) + 4 steering magnets, i.e. 8 in total, where additional steering magnets 3 V and 1 H must be installed ( which are not listed in ATF2DeviceListv3.8r0.xls ).
The maximum beam size will be &sigmax=1.3mm at the last dipole magnet (BDMP).
The beam size can decrease to &sigmax= 0.6mm with addition of 3 quadrupole magnets, i.e. QD2A, QF3 and QD2B.
Another three quadrupole magnets, i.e. QD10X, QF11X and QD12X, are needed in order to measure the beam emittance by re-located 5 wire scanners. The three ones can be operated with all the same current of 47.9A.
8 steering magnets are available from 7 spare/nominal V steering magnets and one 12cm long H steering magnet.
All of the power supplies are available as listed below;
- 8 steering magnets : some of them need repair.
- 3 Bend : 3 J-PARC PS ( 16V, 300A),
- Resistance of magnet is 0.038 ohms
- Maximum voltage is 5.87 volts
- 3 Qs for smaller beam size : 2 ATF 100A PS and 1 J-PARC PS
- 3 Qs for emittance measurement : 3 J-PARC PS
, where 10 J-PARC PSs are borrowed by T. Naito.
- Q : How large is the beam size without additional Qs?
- A : As explained, it is 1.3mm beam size ( &sigmax ). In general, it is better to minimize it.
- C : Since the physical aperture is more than 50mm, several mm would be OK.
- Q : where is the largest beam size?
- A : at the final bend !
- Q : How much is the beam size at IP ?
- A : It is 0.1 - 0.3mm .
- C : The large IP beam size is OK , since collision will not be planned with BSM in this commissioning.
- Q : Are 3 Qs needed in terms of transportation to the beam dump without radiation-safety issue?
- A : No, we do not need them.
- Q : What case is the minimum set needed?
For correct coupling, skew-Qs must be needed ?
- A : It depends on the HA-PS availability. If the HA-PS arrive early, it is not needed.
- C : The HA-PS is preparing at SLAC. An issue is manpower for commissioning it.
It will take a half month to know more accurate plan.
- Q : How long does it take for the commissioning ?
- A : It needs 2 men for 1 month. However, SLAC could send 1 man now.
- Q : In Oct. 2008, new fiscal year starts in U.S. So is it possible to recover the budget?
- A : It may be possible, but it depends on the SLAC policy.
- Q : When one man for month is available ?
- A : It will be right after the HA-PS arrives at KEK.
- Q : In February, more accurate plan will be known.
- A : Since Orsay will help SLAC to participation in Sendai meeting, Orsay may support it.
- Q : what is the initial emittance ?
- A : emittance = 1 x 10-11 in V, 2 x 10-9 in H, and energy spread=0.1 %.
- Q : What the extraction line has in the minimum set ?
- A : there is no coupling correction section. but matching section.
- Q : To see more the other option, we want have some correction.
So, what is the next option ?
- A : Additional 4 Qs for coupling correction, so 7 more Qs are needed with the emittance measurement.
- Q : IPBPM has 6mm aperture in vertical . Is it problem?
- A : No, IPBPM will not be installed in this commissioning.
- Q : Where is the final steering magnet and how much is the accuracyH
- A : It is 10urad accuracy corresponding to 0.05A for ATF steering magnets.
Since the free distance is 10m for one section with a steering magnet, the positioning accuracy is 0.1mm by it.
- Q : How much is stability of Bends PS?
- A : J-PARC PS has several x 0.001 (?) to be checked by Naito.
- Q : There are 3 V and 1 H steers. Why 1 H with 3 Bends ?
- A : Distance of 25m from ZH10X to first Bend is too long. So one H-steer is needed between them.
- Q : The most tight aperture is IP, where the beam size would be 4mm ( 3 sigma ). Is it OK ?
- A : Without IPBPM, it will be no problem.
- C : For the corrections, skew-Qs and wire scanners must be available at the extraction line.
- Q : Is it possible for laserwire R&D at this commissioning ?
- C : In the worst case, the minimum set and options would be operated by Summer 2009.
We would like to ask Okugi for writing a note of summarizing this study. It will be submitted to the TB.
Critical review of QBPM and carbon wire scanner systems is also needed .
KEK site meeting
Update of Shintake monitor support, T. Kume (KEK)
file , pdf (Japanese) (9 pages, 644kB)
From the recent measurement, the floor is lower by 13 - 17mm at the Shintake monitor. So, a "thick" shims will be placed between the floor and the base of the Shintake monitor. If we use local shims, gap, which is made by the shims, must be filled with mortar.
Since the beam dump will be installed by end of March 2008, the mortar will be injected in April at least. The vertical position of Shintake monitor can be aligned by shimming between the vertical optical table and the base within ±5mm.
We also discussed on detailed schedule of the installation and commissioning. The pulsed high power laser will be installed and operated at the beam line for April through middle of June, 2008.
In this period, an optical table for the laser optics will be borrowed from Honda. After re-location of the laser system, the final dipole magnet (BDMP) will be installed at the beam line.