Minutes of the Booster Commissioning Working Group held on 20th of March 2008

Present: K. Hanke, T. Zickler, C. Carli, C. De Almeida Martins, W. Weterings, B. Mikulec.

Agenda:

1. Follow-up of open actions
2. Equipment timing for PSB injection (W. Weterings)
3. Planning of PSB commissioning with Linac4 (K. Hanke)
4. AOB

1. Follow-up of open actions:

• Kickers in LBE line: It is not yet clear if the power supplies for the kickers LBE.KVT10 and LBE.KHZ10 have to be replaced; K. Hanke will provide the required simulations to clarify the situation. C. De Almeida mentions that these power supplies are very special. In case a new design would prove to be necessary, one has to count with a corresponding delay. The person responsible for the kickers in the LBE line couldn't yet be identified. Nevertheless it seems agreed that the responsibility lies within the BT group.

Assigned to	Start date	Description	State	Result
T.Fowler, W.Weterings	2008-03-20	Clarify who within BT could take over the responsibility for the kicker magnets of the LBE line.	openclosed	W. Weterings agreed to act as contact person for this equipment.	edit
K.Hanke	2008-03-20	Perform simulations of the LBE line with Linac4 to check suitability of magnets and power supplies.	openclosed	The LBE line has been redesigned with a different approach for the emittance measurement (sLHC-PROJECT-Report-0029).	edit

• LTB.BHZ40: C. De Almeida confirms that the Tekelec power converter for this magnet requires replacement. This should in principle be covered by the consolidation budget (to be confirmed with S. Baird; see open actions).
• LT.BHZ20+30: Also for these magnets the Tekelec power converters have to be replaced, but the specifications with Linac4 operation are more stringent than with Linac2 operation only. Therefore C. De Almeida needs to clarify with S. Baird the question whether their replacement can still be covered by the consolidation budget.
• LBS.BVT10: The BVT10 magnet deflects the beam vertically at the end of the actual LBS line. The magnet has been designed for a beam energy of 50 MeV and runs already at its limit (operation temperature: 75 degrees C!). It cannot be powered beyond this limit. A decrease of the deflection angle is not realistic, since the beam would hit magnet yoke. Conclusion: If the LBS measurement line should become operational for a beam energy of 160 MeV, the magnet needs to be replaced by a new and stronger magnet. See below for a photo of the LBS line.

The drawings of the magnet can be found at

• ps_lmltp8194-v0.plt: ps_lmltp8194-v0.plt

• ps_lmltp8199-v0.plt: ps_lmltp8199-v0.plt

• PS Booster injection elements (see design parameters on last page of resume_commisioning.pdf): Could the new PSB injection elements also be used with Linac2 operation? The horizontal septum aperture will be reduced from 110 to 70 mm with Linac4 operation in order to increase the gradient (vertical aperture 32 mm). The horizontal aperture of the distributor is 50 mm. It should be cross-checked with AB/ABP whether these apertures are acceptable for both Linac2 and Linac4 operation. In any case, a major shutdown would be required if Linac2 would have to be revived as the septa in the PSB injection period would have to be put back in place (removed for stripper foil injection). Another idea that could be evaluated would be whether the H- source and the RFQ could be made to work with the Linac2 injection line.

Assigned to	Start date	Description	State	Result
A.Lombardi, M.Eshraqi	2008-03-20	Check aperture limitations of BI line both for Linac4 and Linac2 operation. In case the aperture would be too stringent, inform W.Weterings as soon as possible.	openclosed	See presentation 10/04/2008.	edit

T. Zickler will send the latest version of the magnet and power converter inventory for the old transfer line under Linac4 operation to K. Hanke who will complete the information. The file will be added to the commissioning WG Wiki page once cross-checked by T. Zickler and C. De Almeida.

Addendum to these minutes:
After the meeting, the file with the magnet and power converter list for the old Linac2 to PSB transfer line was completed and cross-checked and can be found here (L4_existing_TL_magnets_CAM.pdf). This file should be used as reference from now on.
In summary, 2 magnets have to be exchanged: BI.BVT and LBS.BVT10; the suitability of the quadrupoles in the LBE line still needs to be confirmed.
On the power converter side, the 3 Tekelec power supplies require replacement (for LT.BHZ20, LT.BHZ30 and LTB.BHZ40). In addition, the power converters for BI.BVT and LBS.BVT10 also have to be replaced; the decision for some elements in the LBE line is still pending. C. De Almeida is pointing out that many converters will work at much lower currents than before; therefore their precision will be affected by the ratio between the old (Linac2 operation) and the new (Linac4 operation) current values.

2. Equipment timing for PSB injection:

W. Weterings presented the timing structure of the distributor with Linac4 operation (see resume_commisioning.pdf). Linac4 will deliver 4 pulses (one for each ring), typically 100 us long with 1 us spacing, as well as a head and tail dump. The head dump is necessary to define the beam loading in the cavities for stable Linac4 operation; the tail dump could in principle be removed by the chopper. The 'holes' of about 1 us between the pulses will be formed by the chopper to avoid losses during the rise time of the distributor. C. Carli mentioned that 1 us spacing is the maximum again due to cavity beam loading.

Contrary to current operation, the distributor pulse length will be fixed, but different for each distributor magnet. Linac4 pulses and distributor timing can be adjusted to define the number of injection turns.

3. Planning of PSB commissioning with Linac4:

It seems impossible to commission the new Linac4 to Linac2 transfer line up to the measurement line in parallel with the installation of the new PSB injection elements as a real beam dump would have to be added. Commissioning of the transfer line and the PSB injection line should somehow be grouped, and time has to be attributed individually to PSB injection line installation. In this context it should be checked if some new PSB injection elements could already be installed in advance during one of the shutdowns (distributor?). W. Weterings will investigate this.

The remark was made that 3 months are too short to implement all the PSB modifications. In addition, this area is quite hot and about 3 weeks have to be counted as cool-down period. Maybe the cool-down period could be used to send beam to the measurement line for transfer line commissioning?

Can a beam stopper or dump be added at the end of the new tunnel (before LT.BHZ20) for transfer line commissioning?

Assigned to	Start date	Description	State	Result
W.Weterings	2008-03-20	Can the installation of some new PSB injection elements be advanced?	openclosed	Closed. See minutes 10/04/2008.	edit
K.Hanke	2008-03-20	Draft a modification to the planning of Linac4 transfer line commissioning and PSB injection line changes.	openclosed	Done. See minutes of July 3rd 2008.	edit

-- BettinaMikulec - 20 Mar 2008

• L4_existing_TL_magnets_CAM.pdf: Magnet and power converter list for Linac2 to PSB transfer line; changes with Linac4 operation.%META:FILEATTACHMENT{name="resume_commisioning.pdf" attachment="resume_commisioning.pdf" attr="" comment="Pulses from Linac4 and distributor; design parameters of PSB injection elements" date="1206437507" path="resume_commisioning.pdf" size="100863" stream="resume_commisioning.pdf" user="Main.BettinaMikulec" version="1"}%