Minutes of the SPL working group

meeting no. 84

date: 20. September 2007

present: Y. Body, L. Bruno, C. Carli, E. Ciapala, C. de Almeida Martins, M. Eshraqi, R. Garoby, F. Gerigk, D. Kuchler, J-M. Lacroix, A. Lombardi, T. Meinschad, M. Paoluzzi, V. Parma, M. Pasini, M. Poehler, C. Rossi, E. Sargsyan, J. Tuckmantel


1. Layout of Linac4, SPL, PS2 (Michael Poehler)
2. SPL tunnel integration (Jean-Michel Lacroix)
3. Status and plans for the SPL (Roland Garoby)
4. SPL/LPSPL status & parameters (Frank Gerigk)
5. Comments and remarks
6. next meeting

1. Layout of Linac4, SPL, PS2 (Michael Poehler)

M. Poehler showed slides on the latest layout plans for Linac4, SPL, and PS2. M. Poehler is responsible for the civil engineering aspects of the SPL and is asked by his department to complete a feasibility study of the SPL layout by the end of the year. This includes a preliminary cost estimate for the preferred layout. He introduced D. Parchet who works on integration aspects and Jean-Michel Lacroix, working on the tunnel integration drawings (next talk). The TS-CE work plan contains an extraction to the ISOLDE area (and possibly to an EURISOL area), the addition of accumulator/compressor rings for a neutrino factory, a connection to the west-hall (which can be used for fixed target physics), and an option to supply the Antiproton target area. The major points at the moment are to fix the exact depth of Linac4, and to make sure that there is enough distance between existing tunnels and the SPL tunnels. Critical item are i) the distance between the SPL accelerating tunnel and the basement of building 513 (including the parking areas around 513), ii) the distance between the SPL accelerating tunnel and technical gallery TP9B to ensure that the optical cables are not damaged, iii) distance between the target area of nTOF and the SPL tunnels: this is only of relevance during the tunneling works for the SPL. Once the SPL and PS2 are running, nTOF will no longer operate in its present location. The size of the buildings is taken from the SPL CDR and a proposal for their new location is shown in the slides.

2. SPL tunnel integration (Jean-Michel Lacroix)

J.-M. Lacroix showed a first solution for the tunnel cross-sections of accelerating and klystron tunnel. Taken into account are: i) klystrons and modulators including racks (based on information from Thales and the CERN power group), ii) cryo-modules (using information from TESLA and the CERN cryo-group), iii) wave-guides and wave-guide splitting are based on the DESY-XFEL approach using uneven splitting ratios and otherwise existing wave-guide components. Due to space restrictions in the klystron tunnel the splitting is done in the accelerating tunnel. iv) water pipes. v) space for an AC system in the klystron tunnel is foreseen but the system is not implemented in the drawings, vi) space for transport. The distance between the tunnels is 9 metres and there is one chicane in the passage of the wave-guides between the tunnels.

It is clear that the present design will have to undergo many iterations in order to optimise and include all elements in the tunnels. At the present stage further refinement is limited by the available manpower (RF system, cryogenics, controls, diagnostics, modulators, etc).

3. Status and plans for the SPL (Roland Garoby)

R. Garoby presented the present status of support for the SPL and reviewed envisaged and existing collaborations. He reminded the audience of the comparison between a RCS-based solution and a low-power SPL (LPSPL), which was published in May. As an outcome it was established that the LPSPL is approximately 30% more expensive than a RCS solution. However, due to the extensive upgrade possibilities of a Linac, the CERN directorate, the SPC and the Council have accepted the LPSPL as the the baseline option for the future PS2 injector.

R.G. explained that the SPL is mentioned in the "White paper" in two out of four themes. In theme 2) the SPL is quoted together with Linac4 as the future injector of the PS2, which is supported by the CERN management. It is mentioned that funding should come in part from FP7 proposals. In theme 4) a test stand is mentioned with the capability for RF tests at cryogenic temperatures, which can be used for ISOLDE upgrades, ILC and SC linac development. It is expected that the LHC results until 2010/2011 will suggest to increase the luminosity of the LHC, which will entail the decision to build a new injector (SPL and PS2). The building phase would then span the years 2011 to 2016, requiring an investment of 200 - 250 MCHF per year and 200-300 staff per year. By the end of June 07 a work-plan was submitted to the DG describing the resources to arrive at a Technical Design Report for the SPL in 2011, which can be used as a basis for the decision on construction.

Within FP7 there are two instruments, which will be employed: i) CNI-PP (Construction of new infrastructure-preparatory phase) for LHC luminosity upgrade: it was submitted in May 07 for R&D on the H- source and R&D on the field control in pulsed SC cavities, ii) IA (Integrated Activity) on "High-energy, high-intensity proton beams": the JRA (Joint Research Activity) on the SPL contains SC cavity development and cryo-module design and prototyping. A 2nd JRA proposes a cryo- equipped SC test stand at CERN. The bids were recently presented at the ESGARD meeting at CERN.

A work-plan for the years 2008-2012 indicating the various financial instruments is in the slides along with an overall planning.

4. SPL/LPSPL status & parameters (Frank Gerigk)

F. Gerigk reviewed the present machine parameters for the LPSPL and the SPL. He reminded that the present tunnel integration exercise and the overall layout are made for the full power (5 GeV, 4 MW) linac to be sure that all necessary equipment can be housed in the tunnels and/or inside suitable surface buildings. He summarised the recent changes in the Linac4 design and outlined the transitions from Linac4 to LPSPL and then from LPSPL to SPL. One of the problems is the envisaged 1.2 ms beam pulse length, foreseen for the operation of the LPSPL (20 mA). If the Linac4 power converters are not capable of providing this pulse length, then all power converters need to be exchanged when going from Linac4 to LPSPL operation, even though the repetition rate remains the same. C. de Almeida Martins remarked that the Linac4 power converters can deliver longer pulses if one increases the price tag by 20-30%.

Comments & remarks

  • C. de Almeida Martins reported that the klystron power modulator for the 3 MeV test stand was tested successfully with 800 us pulse length at 2 Hz for up to six hours on a dummy load. The voltage stability was below 1%. Short-circuit tests are foreseen in the near future before testing the device together with a klystron.
  • Vittorio Parma and Edmond Ciapala were welcomed as new members of the SPL study team. V. Parma will be the CERN linkman for the cryo-module development and E. Ciapala will be involved with the envisaged test program of SC cavities and cryo-modules.
  • The HIPPI'07 meeting starts on September 25th,
  • The Beam'07 meeting (HHH) will take place at CERN, starting October, 1st,
  • upcoming events can be seen in the "event calendar" on the SPL web-pages: https://twiki.cern.ch/twiki/bin/view/SPL/EventCalendar, everyone who wants to edit this calendar should contact: mailto:frank.gerigk@cernNOSPAMPLEASE.ch.

next meeting: will take place on November, 14th, 9:00 in 40-R-C10

-- FrankGerigk - 24 Sep 2007

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