Minutes of the Linac4 Technical Design Committee

meeting no. 4

date: 25 July 2006


AB/RF F. Gerigk, M. Pasini, R. Wegner, C. Rossi, M. Paoluzzi, M. Vretenar
AB/ABP G. Bellodi, E. Sargsyan, D. Kuchler, Th. Meinschad, R. Scrivens, C. Lacroix
AB/BI U. Raich
AB/CO J. Serrano
AB/BT W. Weterings
AB/PO C. De Almeida, J.P. Royer
TS/CV Y. Body
TS/CE A. Lopez
TS/SU M. Jones
TS/MME Y. Cuvet, M. Timmins
AT/VAC E. Page
AT/MEL T. Zickler
AT/MTM W. Venturini
SC/RP M. Silari, T. Otto

excused: W. Kalbreier, U. Raich, P. Bourquin, S. Maury, O. Brunner


1. Options for Linac4 Layout (M. Vretenar)
2. Latest Design of the Transfer Line (G. Bellodi)
3. Preliminary estimate of electrical power requirements for Linac4 (F. Gerigk)
4. Status of Technical Design Report preparation (M. Vretenar)
6. next meeting

1. Options for Linac4 Layout (M. Vretenar)

Up to now, three options have been considered for placing Linac4 on the site. In the order, they are:
  • Linac4 in the South Hall. Main advantages are the use of an existing hall and of the infrastructure (cooling, electricity, crane,…). Concerns are the important shielding to be installed in the hall, complicated by the nearby offices, and the difficult transfer line to PSB.
  • Linac4 in a new building under Mont Citron. In this case shielding and connection to the PSB line are simple, but the new tunnel with all infrastructure and external equipment building would be very expensive (estimated at ~10 MCHF).
  • Linac4 in the Linac2 building. A new tunnel (35m) would be built in the prolongation of Linac2 on the low energy side. The new tunnel will house RFQ and DTL of Linac4, which could be commissioned while Linac2 is operating. Then, a 6 month shutdown could be sufficient to dismount Linac2, install the rest of Linac4 in the existing building and then commission the high energy part of Linac4. The drawbacks of this solution are the accurate planning required to minimise the beam interruption and the fact that there would be no possible backup with Linac2 in case of problems with the new linac. Moreover, it has still to be checked that the shielding of the Linac2 hall could be increased to the values required for Linac4.

The situation at this moment is that option #2 has been abandoned because of the cost, option #1 remains our nominal option, has to be investigated in all details and will be presented in the TDR report, and option #2 is considered an interesting alternative option, which has to be further investigated, and which will be presented as alternative in the TDR. A small working group coordinated by S. Maury is investigating these options, and should come to a conclusion by the end of September.


  • A. Lopez-Hernandez presented the latest drawings for the Linac2 option. The question of the shielding remains open, Linac2 has already a concrete shielding of increasing thickness. The thickness could be increased, but the tunnel section can not be reduced and protection of the existing Linac2 equipment gallery could be a problem.

2. Latest Design of the Transfer Line (G. Bellodi)

The layout of the transfer line went recently through some changes. The deflection angle out of Linac4 is changed in order to avoid the LEIR shielding, the optics has been changed to allow crossing the PS shielding wall with a simple pipe, the initial triplet in the line has been removed and finally the second dipole pair has been compacted in one single magnet. The debunching cavities have been re-designed and their position optimized.

3. Preliminary estimate of electrical power requirements for Linac4 (F. Gerigk)

The new list of electrical requirements now includes all the RF needs (filament supplies, realistic efficiency of power supplies, etc.). For cooling water, it has been decided to take an amount of 20 l/min for each LEP klystron, a value considerably lower than the CW requirement, that one hopes can be achieved in pulsed model. The final figure can be determined only after the tests in the 3 MeV test stand.


  • Y. Body asked to know some estimates for the water, and invited to consider the amount of power that has to be removed inside the tunnel by the air conditioning system. About the quadrupoles, T. Zickler mentioned that he prefers water cooled magnets even in case the power supply is pulsed.

4. Status of Technical Design Report preparation (M. Vretenar)

Up to now, 17 contributions out of 29 have been received. In particular, the machine design chapter is now complete, providing a coherent set of information for the general services chapter. In this chapter (number 5), some important contributions are still missing: Radio Frequency, magnets, power supplies and vacuum. We need now this information, because it is the basis for the definition of the infrastructure, the next chapter to be filled. The contributors are kindly asked to prepare as soon as possible their contribution, in order to be able to meet the new schedule agreed with TS: by 15.8 should be defined the electricity and cooling requirements, and by mid-September the TS chapter should be ready.


it was pointed out that PO is still waiting for the magnet parameters in order to complete their contribution. T. Zickler apologized for the delay due to many urgent interventions on the machine and promised to deliver a table with magnet parameters before the end of the week.


next meeting:

Tuesday September 5th, 14:00, room 354 1-001

-- MaurizioVretenar -

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