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Status & plans of the SPL* study

Status & plans of the SPL* study. Why upgrade the proton beams at CERN ? Approved physics programme Potential extensions of the physics programme Why a high energy linac ? Linac versus RCS World-wide context How ? SPL design R. & D. topics and collaborations Staging

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Status & plans of the SPL* study

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  1. Status & plans of the SPL* study • Why upgrade the proton beams at CERN ? • Approved physics programme • Potential extensions of the physics programme • Why a high energy linac ? • Linac versus RCS • World-wide context • How ? • SPL design • R. & D. topics and collaborations • Staging • Roadmap and resources * SPL = Superconducting Proton Linac A concept for improving the performance of the proton beams at CERN, ultimately based on a high-energy Superconducting Linear Accelerator 1

  2. The SPL Working Group REFERENCES - Conceptual Design of the SPL, a High Power Superconducting Proton Linac at CERN Ed. M. Vretenar, CERN 2000-012 - SPL web site: http://cern.web.cern.ch/CERN/Divisions/PS/SPL_SG/ 2

  3. PART 1: WHY ? 3

  4. Period of interest… Why upgrade the proton beams at CERN ? (1) Long-term Scientific Programme at CERN (from CERN/SPC/811) LHC SPS Fixed target PSB & PS 4

  5. Why upgrade the proton beams at CERN ? (2) • Because users will miss protons… PS supercycle for LHC PS supercycle for CNGS Remaining PSB & PS pulses to be shared between nTOF, AD, ISOLDE, East Hall, Machine studies… 5

  6. Why upgrade the proton beams at CERN ? (3) • Because higher beam performance (brightness*) will be first, welcome, and later, necessary to: • Reliably deliver the ultimate beam actually foreseen for LHC, • Reduce the LHC filling time, • Increase the proton flux onto the CNGS target, • Prepare for further upgrades of the LHC performance beyond the present ultimate. * For protons, brightness can only degrade along a cascade of accelerators Þ Any improvement has to begin at the low energy (linac) end 6

  7. Why upgrade the proton beams at CERN ? (4) • To address new physics programmes: • “Neutrino Super-Beam” (= conventional but very intense neutrino beam) Accelerator, target and decay channel at CERN Detector in the Frejus tunnel (400 ktons…) 7

  8. Why upgrade the proton beams at CERN ? (5) • To address new physics programmes: • EURISOL (Next generation of ISOLDE-like source of radio-active isotopes) _ European Isotope Separation On-LineRadioactive Nuclear Beam Facility The EURISOL project is one of the 5 Research and Technical Development (RTD) projects in Nuclear Physics selected for support by the EU. The project is aimed at completing a preliminary design study of the next-generation European ISOL radioactive nuclear beam (RNB) facility. The resulting facility is intended to extend and amplify, beyond 2010, the exciting work presently being carried out using the first-generation RNB facilities in various scientific disciplines including nuclear physics, nuclear astrophysics and fundamental interactions. Careful design and developments will be needed to increase the variety and the number of exotic ions available per second to be provided for research, beyond the limits of presently available facilities. 8

  9. Why upgrade the proton beams at CERN ? (6) • To address new physics programmes: • b beams to Frejus 9

  10. Why upgrade the proton beams at CERN ? (7) • To address new physics programmes: • Neutrino Factory 1021 y-1 1/g dominates ~ 3´1020n/year to each experiment 10

  11. Why upgrade the proton beams ?Summary of reasons • 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 • LHC performance upgrade beyond ultimate • “Conventional” neutrino beam from the SPL “super-beam” • Second generation ISOLDE facility (“EURISOL” -like) • Neutrino source from “beta beams” • Neutrino Factory 11

  12. Why a high energy linac ? (1) • ~ 4 MW of beam power at 2-3 GeV are needed • The energy of the linac injecting into the first synchrotron has to be increased (50 MeV today) • Comparing a Linac + fixed energy rings set-up with a 2-3 GeV Rapid Cycling Synchrotron (RCS) : • The linac set-up can accommodate more users since its beam power can be increased, • Some users prefer the long beam pulse delivered by a linac, • The RCS construction cost could be smaller, but this is moderated by the availability of the LEP RF equipment which a linac will re-use • Linac maintenance is likely to require less manpower 12

  13. Why a high energy linac ? (2)LEP RF equipment A large inventory of LEP RF equipment is available (SC cavities, cryostats, klystrons, waveguides, circulators, etc.) which can drastically reduce the cost of construction The LEP klystron Storage of the LEP cavities in the ISR tunnel 13

  14. Why a high energy linac ? (3)World-wide context High Power Linacs Survey (H+,H-,D+) * * Updated during the 20th ICFA Beam Dynamics workshop (FNAL, 8-12 April 2002) 14

  15. PART 2: HOW ? 15

  16. SPL Design - Basics Basic parameters Energy >2 GeV (PS injection, p production)  Max. repetition rate 50 Hz (limit for SC cavities)  Beam power 4 MW (limit of target technology) Design principles:  352 MHz frequency (LEP) for all the linac (standard RF, easy long. matching)  start room-temperature, go to SC as soon as possible  trade-off between current and pulse length (best compromise SC/RT) 16

  17. SPL Design - Parameters chopping 17

  18. SPL Design - Layout 55 cryostats, 33 from LEP, 22 using components (68 total available) 49 klystrons (44 used in LEP) Note: no more unmodified LEP cavities are used in the SPL design, for a 87 m shorter linac 18

  19. SPL Design – Layout on site 19

  20. SPL R&D guidelines Identify strategic items (and establish a list of priorities): 1. Requiring limited resources 2. Essential / critical to the project 3. Where CERN competence is particularly valuable 4. With a maximum of collaboration/exchanges with other labs 5. Useful for any upgrade of the CERN injectors 20

  21. SPL Design – R&D topics H- source, 25 mA 14% duty cycle Cell Coupled Drift Tube Linac Fast chopper (2 ns transition time) Beam dynamics studies aiming at minimising losses (activation!) new SC cavities: b=0.52, 0.7, 0.8 RF system: pulsing of LEP klystrons Vibrations of SC cavities: analysis, compensation schemes. Development of a new Low Level RF (with Linac2) 21

  22. R&D topics: the chopper structure and driver Chopper: Travelling-wave RF deflector (meander line) at 3 MeV kicks out the bunches falling between accumulator buckets (reduce loss at injection) essential for modern injector linacs ! CERN Chopper structure: Alumina substrate, reduced width (inside quads) Prototypes tested (attenuation and dispersion) (F. Caspers) • Driver amplifier: • 2 ns rise-fall time • (10%-90%) • ± 500 V • Prototype of HF part • (M. Paoluzzi) 40 ns 22

  23. R&D topics – the CCDTL From 40 MeV (up to 120 MeV) the Alvarez can be replaced by a Cell-Coupled Drift Tube Linac: quadrupole housing drift tube 1. Quadrupoles outside drift tubes: simpler cooling, access/replacement, alignment 2. Less expensive structure than DTL 3. Same real estate shunt impedance 4. Continuous focusing lattice 5. Stabilised structure (p/2 mode) 6. One resonator/klystron coupling cell 5 klystrons 4 klystrons 6 klystrons 23

  24. R&D collaborations: the DTL test stand (with IPHI) Measurements (ISN Grenoble) New test stand in the PS South Hall for 352 MHz linac structures 50 kW CW, 100 kW pulse (just outside MCR) DTL model (CEA-Saclay) Waveguide (ex LEP) CERN 50 kW amplifier (ex SPS-LEP) 2002: testing the IPHI DTL model (3 drift tubes) 2003: testing the CERN CCDTL model 24

  25. R&D topics – low b SC cavities • CERN technique of Nb/Cu sputtering • excellent thermal and mechanical stability (important for pulsed systems) • lower material cost, large apertures, released tolerances, 4.5 K operation with Q = 109  Bulk Nb or mixed technique for b=0.52 (one 100 kW tetrode per cavity) (E. Chiaveri, R. Losito) The b=0.7 4-cell prototype 25

  26. R&D topics - vibrations + possible chaotic effects (J. Tückmantel) Effect on the beam Effect on field regulation • vector sum feedback can compensate only for vibration amplitudes below 40 Hz • possible remedies: piezos and/or high power phase and amplitude modulators (prototype ordered - H. Frischholz) 26

  27. 5 ms/div 1 ms/div R&D topics – pulsing of LEP klystrons Mod anode driver 14/05/2001 - H. Frischholz • LEP power supplies and klystrons are capable to operate in pulsed mode after minor modifications • up to 12 klystrons can be connected to one LEP power supply 27

  28. R&D topics – loss management For hands-on maintenance, the generally accepted figure is a particle loss < 1 W/m For the SPL, 10 nA/m (10-6/m) @ 100 MeV, 0.5 nA/m (10-7/m) @ 2 GeV Present Linac2 loss level (transfer line):  25W/80m = 0.3 W/m (but hot spots at > 1 W/m !) • Mechanism of beam loss in the SPL: • H- stripping  < 0.01 W/m in quads for an off-axis beam • Residual gas  < 0.03 W/m @ 10-8 mbar, 2 GeV (but 0.25 W/m @ 10-7) • Halo scraping  more delicate, requires: • large apertures (SC is good!) •  careful beam dynamics design 28

  29. R&D topics – beam dynamics Control rms emittance growth and loss from the outer halo by avoiding parametric resonances  Selection of the working point (phase advances) on the Hofmann’s chart + Careful matching (50Mpartsimulations with IMPACT at NERSC, Berkeley) (F. Gerigk) 29

  30. R&D topics – after the linac… Transfer lines, collimation (= scrape away halo particles before the accumulator), etc. Accumulator/Collector scheme (PDAC study group) for NuFact Two Rings in the ISR Tunnel Accumulator: 3.3 ms burst of 144 bunches at 44 MHz Compressor: Bunch length reduced to 3 ns 30

  31. Staging 1: a common low-energy test stand with IPHI IPHI=Injecteur de Protons Haute Intensité (CEA+IN2P3) a 5 MeV CW RFQ @ 352 MHz is in construction and a test stand (2 LEP klystrons) in preparation at CEA-Saclay. Agreement reached in April:  IPHI RFQ split at 3 MeV to accomodate the CERN line  CERN will assemble a chopper line (choppers, quads, bunchers)  Common test stand at CEA Saclay More details: CERN/PS 2002-012 (RF) SUMMARY OF MINI-WORKSHOP ON SPL AND IPHI R. Garoby  Further tests (2006) at CERN with an H- source 31

  32. Staging 2 – a 120 MeV linac in the PS South Hall Any upgrade of the CERN injectors to higher brightness requires a higher energy linac Profiting of the SPL design, we have a unique chance to build a new, low-cost and high- performance linac by using the RT (120 MeV) part of the SPL to inject H- into the PSB. Parameters are relaxed, there is enough space for a linac in the PS South Hall, the RF comes for free. 32

  33. Staging – the 120 MeV linac to inflector & PSB 72 m 33

  34. Staging – the 120 MeV linac 34

  35. A new 120 MeV linac at CERN (Linac 4…) • 1. Cost-effective construction • (the RF is available, including waveguides and power supplies, the building is there as well as cooling and electricity,…) • Advantages for the LHC beam • (shorter filling time, more margin for the injectors, • opens the way for an LHC upgrade) • Many advantages for the users of secondary beams • (factor 1.8 in flux for CNGS, factor 2 for ISOLDE, • improvements for AD and n-TOF). • A more modern and easy-to-run injector replacing • the aging Linac2 35

  36. PART 3: ROADMAP & RESOURCES 36

  37. Roadmap (1)CERN context “The R&D budget for future detectors and accelerators foreseen in the 2002-2005 MTP and for the subsequent years to 2010 is reduced in total by 54.2 MCHF making thus available 26 MCHF for the completion of the upgrade of the injectors. The materials budget for R&D during the period 2003-2006 will therefore be limited to around 3.8 MCHF per year. For the time being, similar figures are also foreseen, for the years 2007-2010. Direct manpower involved in accelerator R&D is kept over the next 8 years at about 30 CERN staff and 5 fellows and associates, full time equivalent per year. It should be stressed that the above is a minimal programme of Accelerator R&D especially for an accelerator laboratory of the importance of CERN. Its narrowness and limitations can only be justified by the present severe budgetary problems facing CERN. Efforts will be made to enhance the synergies in accelerator R&D with other Laboratories by enlarging the scope of ongoing collaborations and by setting up new ones. In the years 2002-2004 about 90 % of the accelerator R&D resources will go to the construction of the CTF3 facility for CLIC... R&D work on components for the front-end of a Superconducting Proton Linac (SPL) will continue with limited funds until the first phase of CTF3 is completed and the testing of high-gradient accelerating structures is well advanced. From then on, the sharing of resources between CLIC and SPL work might evolve as a function of the results technically achieved and of the contribution of the collaborations with other Laboratories. The work on the SPL front-end is carried out within the framework of collaboration for powerful H -- sources among seven European laboratories and with IN2P3/CEA for a Radio Frequency Quadrupole (RFQ) device…” • R & D on accelerators at CERN - Medium Term Plan (SPC/811) 37

  38. Roadmap (2)[until 2006] • 5 MeV H- injector (summary of collaboration meetings in April 2002) • Tests at Saclay: • Construction & installation of RFQ1 (3MeV) mid-2004 • + CW diagnostic line (3 MeV) + beam stopper • Characterisation in CW up to ~ 100 mA end 2004 • Installation of chopping line + RFQ2 (?) mid-2005 • + CW diagnostic line (5 MeV) with • time resolved instrumentation • Characterisation at 5 MeV [pulsed & CW] end 2005 • Installation at CERN (without H+ source) ~ 2006 Resources: Need to provide the foreseen CERN contribution (chopper line and instrumentation), develop an H- source and prepare the infrastructure for installation. Comment: ~ feasible with the manpower authorised in 2002 + ~ 500 kCHF/year 38

  39. Roadmap (3) [until 2010 ?] • 120 MeV H- linac in the PS South Hall [replacing LINAC 2 (50 MeV H+)] • Goal: increase beam intensity for CNGS and improve characteristics of all proton beams (LHC, ISOLDE…) • Under study: detailed design report with cost estimate in October 2002 • On-going activities: • Tests at CERN of DTL prototypes (collaboration with CEA & IN2P3) • Development of CCDTL structures • Development of new low level RF • Study of charge exchange injection in the PSB Resources: Requires an order of magnitude increase w.r.t. the effort invested in the 5 MeV injector Comment: Active search for external resources (E.U. etc.). Nothing will be possible without a clear decision by the CERN management, linked to the commitment to an adequate support. 39

  40. Roadmap (4) [until 201x !] • Full size SPL • Necessary condition: approval of (at least) one new physics programme (Neutrino super-beam ? EURISOL ?…) • Design is not frozen ! (beam energy, type of SC cavities…) • On-going activities: • Studies and developments for the 120 MeV injector • Characterisation of 352 MHz low b SC cavities in pulsed mode • Development of high power amplitude & phase modulator • Beam dynamics optimisation Resources: Large size project when combined with the realisation of high power target area(s) and new experimental facilities Comment: Will need major contributions in know-how and in-kind from other laboratories. A clear possibility of development of CERN after the completion of the LHC construction… 40

  41. Roadmap (5) • The SPL study is alive and supported, although with limited resources, and progress is made: • design is improving, • R&D is going on, • collaborations are active and more is encouraged ! • A staged approach is proposed to: • bring immediate benefits to the approved physics programme • help preserve and gradually strengthen a competent team • accelerate the realization of the complete SPL • Continuation after 2002 depends upon CERN management decisions to solve the LHC crisis… 41

  42. CONCLUSION • High intensity protons beams will remain a strong asset of CERN beyond 2010. Improving their performance is a logical and necessary path for the approved physics programme (especially LHC). • Proposals for new major experimental facilities are being prepared (UNO, neutrino super-beams, EURISOL, …), for which the CERN site is perfectly suitable. ß A new high performance proton injector like the SPL would be a key component to satisfy both needs • Such a project is ideally suited to bridge the gap between the end of payment of the LHC construction and a future project for high energy physics (VLHC ? Linear Collider ? Neutrino Factory ? …) 42

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