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Report from the 1st meeting of Linac4 Machine Review Committee . G ü nther Geschonke, Stuart Henderson, Alban Mosnier, Ulrich Ratzinger, Yoshishige Yamazaki. Charge. “Monitor progress and provide advice on technical and management issues”. . Introduction.
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Report from the1st meeting of Linac4 Machine Review Committee Günther Geschonke, Stuart Henderson, Alban Mosnier, Ulrich Ratzinger, Yoshishige Yamazaki Linac4 Review Committee
Charge • “Monitor progress and provide advice on technical and management issues”. Linac4 Review Committee
Introduction • LINAC4 = First step to guarantee the LHC performance and to implement the future upgrade of the Cern injector complex • its design and location fit well the possible later injection into the SPL Linac4 Review Committee
Parameters • Full consistent parameter list available • intensity in PSB improved by a factor 2 • Energy 160 MeV OK for PSB • Frequency change 700 (TDR06) 352 MHz MRC endorses the move to a single frequency ! • RF and Beam Dynamics advantages • But the different duty cycles are confusing for the design of the components (power sources, structures...) needs to be clarified for the specs Linac4 Review Committee
Beam Dynamics • looks on the safe side, in comparison with other similar projects (SNS, J-PARC) • however, concern about the RF tolerances(0.5% in amp, 0.5° in phase, as needed in DTL) • to check a larger longitudinal acceptance, study the sensitivity to the s law, field ramp ... • small safety margin in DTL • decision between 2 PMQ designs needed soon • think about steerers in empty DT (FFDD lattice) Linac4 Review Committee
Ion Source • DESY-type is a robust design and performances already achieved very close to the LINAC4 specs • good lifetime (RF antenna) • no cesium • MRC encourages beam measurements at the TestStand (expected end of 2008) Linac4 Review Committee
RFQ • home-made (drawings, machining, brazing) to master all the fabrication steps • tolerances look similar to IPHI RFQ • length divided by 2, but smaller aperture (1.8 mm) • can learn from the IPHI experience • especially, deformation during heat-treatment • concern about dipole modes • consider Pi-mode stabilizing loops to relax mechanical tolerances Linac4 Review Committee
Chopper • design looks fine • deflecting structure is OK • concern about the pulse driver • 0.5 kV in less than 2 ns ! • needs specialized FID technology • MRC encourages beam test ASAP • chopper line expected in operation in 2010is it realistic ? Linac4 Review Committee
Choice of structures • Question: Is the present choice optimal ? • trade-off between efficiency, beam dyn. & cost • the efficiency study was made, is that the cost optimum wrt energy ranges ? Linac4 Review Committee
Drift Tube Linac • Field looks fine (Killpatrick < 1.6) • Drift tubes alignment: mechanical tests could be done soon • Cooling issue: to prevent from local over-heating of the drift tube (PMQ & innertube) • power test ASAP, expected in Summer 2008 • thermal beam loss studies • Now two distinct approaches: decreases the technological risk Linac4 Review Committee
CC-DTL • LINAC4 will be the first Linac in the world to be equipped with CC-DTL structures • Sealing : Cu-plated Helicoflex gasketgood for vacuum but RF performance should be checked (alternative ?) • designed for which max. duty cycle ? • additional cooling is required in the tuners • Two distinct technological approaches: what is the conclusion ? Linac4 Review Committee
PIMS • robust design (LEP) and even better understood ... • Transient behaviour: well analysed and conclusion was positive • Choice of copper (3D forged or not ?) • in case metallurgical experts cannot answer, make two prototypes with different copperand compare before series production ... Linac4 Review Committee
RF power • 1 big 2.5MW klystron? compare the total cost : klystron + RF splitting + possibly High power Phase & Amp control and 2 x 1.3MW klystrons • Specs should allow the average power for SPL • Modulators: space should be enough for the upgrade to SPL requirements • Space issue: no room is left • consider vertical klystron Linac4 Review Committee
LLRF • choice: to start from the LHC systemnot far from the LINAC4 requirements • more study on the performance of the phase and amplitude (or I/Q) control • bandwidth of the feedback loops • operation close to saturation: enough margin on power overhead (at the expense of the efficiency) Linac4 Review Committee
Beam instrumentation • diagnostics plan looks very promising • but developments are needed to compact the devices Linac4 Review Committee
Magnets • even if some magnets are foreseen for the low duty cycle in the 1st stage for obvious economic reasons, a design for all magnets should exist for the SPL requirements Linac4 Review Committee
Test-Stand • MRC appreciates the possible extension to 10 MeV • A lot of tests are essential for the success of the project: Take care to additional delays ! Linac4 Review Committee
Resources • Time-schedule (5 years ½) is short • organisation: matrix structure of the project (Working Group coordinators / Workpackage responsibles) could optimise the manpower • In parallel, the TestStand, the Design and construction of Linac 4 : a big issuethe total manpower should not be underestimated !!! Linac4 Review Committee
Final comments • Very impressed with the new LHC injectors effort, now focused on the Linac4 • Has a complete 10-year scenario for the LHC luminosity upgrade 2007 2017 • Presentations were excellent • MRC appreciates the right approach adopted to meet this big challenge as well as the progress made so far by Maurizio and his Team • Thanks to All (especially to Cecile) Linac4 Review Committee