Minutes of the Booster Commissioning Working Group held on 10th of April 2008

Present: K. Hanke, T. Zickler, C. Carli, C. De Almeida Martins, M. Eshraqi, J. Borburgh, W. Weterings, B. Goddard, B. Mikulec.


  1. Communications
  2. Follow-up of open actions
  3. Aperture limitations of transfer line and PSB injection
  4. AOB

2. Follow-up of open actions:

  • Tekelec power supplies: S. Baird confirmed that he can cover the amount originally foreseen in the consolidation project for the replacement of the Linac2 Tekelec power supplies. Everything that exceeds the current specifications and increases therefore the cost has to be covered by the Linac4 project budget. This difference in cost accounts to about 30% (in numbers about 120-130 kCHF). C. De Almeida will first complete the EVM document including all changes with respect to the original situation and then send the complete cost estimate to M. Vretenar.
Assigned to Start date Description State Result
C.DeAlmeida 2008-04-10 Correct EVM document to include all agreed modifications of the power converters in the Linac4 to PSB transfer line and inform M. Vretenar about the changes. Done. edit

  • Advance installation of some PSB injection elements?: Most probably it is not possible to advance the installation of BI.BVT due to its smaller aperture. Also the distributor cannot be installed earlier due to rise-time conflicts. The only element for which the potential of earlier installation was seen is BI.KSW (used as vacuum chamber with Linac2 operation). W. Weterings will contact T. Fowler to find out if this would be feasible. It was stated that the 3 months foreseen in the current planning for the installation of the new PSB injection elements is the absolute minimum (one of the reasons is that the area there is very restricted and doesn't allow too much parallel work) - the cool-down period and possible holiday periods should not be included in the 3 months.
Assigned to Start date Description State Result
W.Weterings 2008-04-10 Contact T. Fowler to find out if the installation of BI.KSW could be advanced. It seems feasible to advance the BI.KSW installation to 2011/2012 shutdown. edit
  • Planning: As it won't be accepted to add a beam stopper in the line for commissioning, the aim is now to combine the transfer line commissioning with the Linac4 commissioning period. The 2 months foreseen in the planning for the transfer line commissioning seem exaggerated. K. Hanke will prepare a new planning strategy. For transfer line commissioning, the beam will be sent to the measurement line; no access can be given for work in the PSB during this period.

3. Aperture limitations of transfer line and PSB injection:

M. Eshraqi presented simulations to evaluate aperture limitations of the Linac4 to PSB transfer line (see PSB_comissioning1.pdf). Page 3 shows the 5 rms beam size together with the aperture in both planes (remark: the vertical offset of 5.19 mm of the distributor is not taken into account in the simulations, but would not influence the results). It can be seen that beam is lost vertically at the septum, but otherwise the situation seems fine. Large horizontal dispersion is present after the first horizontal dipole and the debuncher (page 4). Under nominal conditions particles are mainly lost in the vertical plane. Adding a 1.2 MeV energy shift required for longitudinal painting, losses also occur in the horizontal plane due to dispersion. Losses are at the level of 4E-4.

A tighter aperture in the septum leads to losses (mainly vertical plane) under both working conditions. The problem is that the new septum cannot be produced with the old ferrite technology as the ferrites would saturate already below 300 mT. As a consequence the vertical bend in the septum cannot be made that smooth. J. Borburgh will review again the design. One workaround would be to increase the kick in the distributor; J. Borburgh will check this possibility with T. Fowler, but the strength might already be at the limit. Another solution would be to move the distributor further upstream. M. Eshraqi will provide the exact beam envelopes to the BT group at the location of the septum.

Assigned to Start date Description State Result
J.Borburgh 2008-04-10 Review design of the new septum. Contact T. Fowler to find out whether the kick in the distributor could be increased. See minutes 22/05/2008. edit
Independently it should be checked if a collimator could be added upstream of the septum.
Assigned to Start date Description State Result
K.Hanke 2008-04-10 Find out if collimators could be added upstream of the septum. This action has been attributed to the Linac4 beam dynamics working group. edit

M. Eshraqi has been asked to check if the horizontal aperture of the septum could even further be reduces from 70 to 50 mm (same level as the distributor) as there seems to be the freedom to do so from the simulations. This would decrease significantly the cost for the power converter. Nevertheless care should be taken to take enough margin into account and to watch closely the emittance evolvement. It was also proposed to consult M. Chanel on this issue.

Assigned to Start date Description State Result
M.Eshraqi 2008-04-10 Provide simulations to decide if the horizontal aperture of the septum could further be reduced from 70 to 50 mm. Done. This is in principle possible, but detailed error studies still have to be done. edit
-- BettinaMikulec - 10 Apr 2008
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Topic revision: r7 - 2010-03-15 - BettinaMikulec
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