The SPL-based Proton Driver at CERN OUTLINE 1. Introduction 2. SPL characteristics 3. On-going work 4. Staging 5. Summary and Conclusion R. Garoby for the SPL W.G. 1

SPL Working Group REFERENCE Conceptual Design of the SPL, a High Power Superconducting Proton Linac at CERN Ed. M. Vretenar, CERN 2000-012 R. Garoby for the SPL W.G. 2

1. Introduction CERN baseline scenario for a Neutrino Factory R. Garoby for the SPL W.G. 3

Other applications of the proton driver Approved physics experiments CERN Neutrinos to Gran Sasso (CNGS): increased flux (~ ´ 2) Anti-proton Decelerator: increased flux Neutrons Time Of Flight (TOF) experiments: increased flux ISOLDE: increased flux, higher duty factor, multiple energies... LHC: faster filling time, increased operational margin... Future potential users “Conventional” neutrino beam from the SPL “super-beam” Second generation ISOLDE facility (“EURISOL” -like) LHC performance upgrade beyond ultimate… R. Garoby for the SPL W.G. 4

2. SPL characteristics H- source, 25 mA 14% duty cycle CCDTL new SC cavities: b=0.52,0.7,0.8 Fast chopper (2 ns transition time) RF system: freq.: 352 MHz ampli.: tetrodes and LEP klystrons R. Garoby for the SPL W.G. 5

Improvements w.r.t. the reference design Improved transitions between sections  better beam stability Doubled period length above 1.1 GeV  save 25 doublets, 8m, 3 MCHF Improved error studies  100% beam radius < 20 mm, even for large error case (30 %)  quad. radius reduced from 100 mm to 60 mm, (17rms)  save 2 - 3 MCHF Reduced longitudinal emittance: 0.6  0.3 ºMeV  improved design of the transfer line (drift length 230  175 m, bunch length 180  130 ps) Use of beta=0.8 cavities up to the highest energy  shorter tunnel (- 100 m), less cavities per klystron, better control of mechanical resonances R. Garoby for the SPL W.G. 6

SPL beam specifications R. Garoby for the SPL W.G. 7

Accumulator-Compressor scheme R. Garoby for the SPL W.G. 8

Characteristics of the beam sent to the target R. Garoby for the SPL W.G. 9

Layout on the CERN site (top view) R. Garoby for the SPL W.G. 10

Cross section R. Garoby for the SPL W.G. 11

3. On-going work R. Garoby for the SPL W.G. 12

Collaboration on RFQs with CEA-IN2P3 (IPHI) and INFN Legnaro Progress highlights Chopper structure 3 D view of a coupled cavity drift tube module (CCDTL) Scaled model (1 GHz) in test Full performance prototype tested Driver amplifier in development Collaboration on RFQs with CEA-IN2P3 (IPHI) and INFN Legnaro 352 MHz test place prepared (planned tests of CEA-built DTL structures in 2002) R. Garoby for the SPL W.G. 13

Chopper  Travelling wave electrostatic deflector, meander line to match beam and wave velocity  Used to create gaps in the linac bunch distribution between accumulator buckets  Needs very short rise/fall times (2 ns !) to avoid partially deflected bunches  Development of pulser 198+2mm (33 cells) 50 mm accumulator bucket R. Garoby for the SPL W.G. 14

Study of RT structures for the SPL front-end bl Alvarez Drift Tube Linac unsurpassable <20 MeV good but expensive for 20-120 MeV bl Cell Coupled Drift Tube Linac attractive solution for 20-150 MeV (a cold model is being designed) bl/2 Coupled-Cell Cavity (LEP1) better efficiency >110 MeV quadrupole quadrupole The final choice will depend on preferred apertures, RT final energy, etc. R. Garoby for the SPL W.G. 15

Superconducting cavities  CERN technique of Nb/Cu sputtering for b=0.7, b=0.8 cavities (352 MHz): excellent thermal and mechanical stability (very important for pulsed systems) lower material cost, large apertures, released tolerances, 4.5 K operation with Q = 109 The b=0.7 4-cell prototype  Bulk Nb or mixed technique for b=0.52 (one 100 kW tetrode per cavity) R. Garoby for the SPL W.G. 16

RF and Superconducting cavities Parameters R. Garoby for the SPL W.G. 17

Pulsed operation of a LEP klystron set-up RF output power (800 kW max.) Mod anode driver 5 ms/div 1 ms/div 14/05/2001 - H. Frischholz Þ LEP power supplies and klystrons are capable to operate in pulsed mode after minor modifications R. Garoby for the SPL W.G. 18

RF power distribution & field regulation in the superconducting cavities Effect on field regulation Effect on the beam Þ unsolved problem ! Needs work Þ similar difficulties are likely in the muon accelerators... R. Garoby for the SPL W.G. 19

4. Staging Test of the 3 MeV H- injector Means: strengthen collaboration with the CEA-IN2P3 and jointly exploit the IPHI set-up Contribute to the chopper and bunchers 120 MeV H- linac in the PS South Hall Goal: increase beam intensity for CNGS and improve characteristics of all proton beams (LHC, ISOLDE…) Under study: detailed design report with cost estimate in 2003 Needs new resources (collaborations, manpower, money) SPL R. Garoby for the SPL W.G. 20

Proton Intensity increase: location of the SPL front-end in the PS South Hall PS To the PSB Beam dump H- source LEIR Þ Increased brightness for LHC, ´ 1.8 the flux to CNGS & ISOLDE, … (with upgrades to the PSB, PS & SPS) Þ “cheap” installation, giving benefits from SPL related hardware before the full machine is operational & shortening the final setting-up R. Garoby for the SPL W.G. 21

5. Summary and Conclusion The SPL design is improving Work is started on most items, based on collaborations A staged approach is proposed Feedback (and support !) is needed from potential users R. Garoby for the SPL W.G. 22