International Scientific Spring 2010, March 1-6, 1. R. Garoby. slhc

Transcription

1 International Scientific Spring 2010, March 1-6, R. Garoby slhc

2 1. Plans for future LHC injectors 2. Implementation stages 3. Final words R.G. 2 3/10/2009

3 R.G /10/2009

4 Motivation 1. Reliability Plans for future LHC injectors The present accelerators are getting old (the PS is 50 years old!) and they operate far beyond their initial design parameters need for new accelerators tailored to the slhc requirements 2. Performance Brightness N/ε* of the beam in LHC must be increased beyond the capability of the present injectors to allow for the maximum luminosity. [Present limit: incoherent space charge tune spreads ΔQ SC at injection in the PSB and PS]. Nb R ΔQSC 2 ε X, Y βγ with Nb : number of protons/bunch ε X, Y : normalized transverse emittances R : mean radius of the accelerator βγ :classical relativistic parameters need to increase the injection energy in the synchrotrons Increased injection energy in the PSB from 50 to 160 MeV kinetic Need for 4 GeV injection energy in PS2 (PS successor) to allow for 2.2 times the ultimate beam brightness in slhc Increased injection energy in the SPS from 25 to 50 GeV kinetic (partly because of space charge, but mostly to inject further from transition energy and to displace TMCI threshold) R.G. 4

5 Description Plans for future LHC injectors Output energy 50 MeV 160 MeV 1.4 GeV 4 GeV 26 GeV 50 GeV 450 GeV 7 TeV Proton flux / Beam power Linac2 PS B PS SPS LHC / slhc Linac4 LP-SPL PS2 Linac4: H- Linac (160 MeV) LP-SPL: Low Power- Superconducting Proton Linac (4 GeV) PS2: High Energy PS (4 to 50 GeV 0.3 Hz) slhc: Superluminosity LHC (up to cm -2 s -1 peak) Stage 1: Linac4 - construction Stage 2: PS2 and LP-SPL: preparation of Conceptual Design Reports for - project approval mid start of construction begin 2013 R.G. 5

6 Site layout Plans for future LHC injectors SPS PS2 ISOLDE PS SPL Linac4 R.G. 6

7 LP-SPL & PS2 design goals Plans for future LHC injectors For LHC operation Higher beam brightness within nominal transverse emittances Flexibility for generating various bunch spacings and bunch patterns Reduction of SPS injection plateau and LHC filling time General design goals High reliability and availability Simplification of operation schemes for complete complex Low beam losses in operation for complete complex Potential for future upgrades of the accelerator complex R.G. Chamonix

8 Performance requirements and parameters Plans for future LHC injectors Brightness (N/ε n ) for LHC beams Design goal: Twice higher brightness than ultimate 25ns beam with 20% intensity reserve for transfer losses ppb = in transverse emittances of 3μm Transfer energy LP SPL PS2 Determined by the beam brightness of the LHC beam Limit of incoherent space charge tune spread at injection to below GeV injection energy Extraction energy Injection into SPS well above transition energy to reduce space charge effects and TMCI Higher energy gives smaller transverse emittances and beam sizes and therefore reduced injection losses Potential for long term SPS replacement with higher energy ~50 GeV extraction energy R.G. Chamonix

9 PS2 goals: PS2 parameters to provide the beam brightness required by all slhc options to improve SPS operation in fixed target mode Plans for future LHC injectors Reason Physical parameter Value Space charge PS2 Injection energy (kinetic) 4 GeV SPS improvement Ejection energy (kinetic) 50 GeV LHC Transverse normalized 1 sigma emittances at 3 π mm.mrad ejection for LHC LHC Longitudinal emittance/bunch with 25 ns 0.35 evs 2.2 ultimate brightness for LHC (includes 10% loss) Flux for SPS / PS2 fixed target physics Possible bunch spacings in LHC (25, 50 & 75 ns) Flux for SPS / PS2 fixed target + LHC filling time bunch spacing at ejection Nb of protons / bunch with 25 ns bunch spacing at ejection for LHC (total 168 bunches) ( ) Nb of protons / bunch with 25 ns bunch spacing (total) (~ ) Size (ratio PS2/SPS) 15/77 Circumference m h RF for 25 ns (resp. 50 or 75 ns) bunch spacing 180 (resp. 90 or 60) Cycling period to 50 GeV (case of no 2.4 s injection flat porch) R.G. 9

10 Requirements of PS2 on its injector: PS2 injector Plans for future LHC injectors Reason Physical parameter Value Space charge Injection energy (kinetic) 4 GeV Twice the ultimate brightness Nb of protons per PS2 cycle for LHC % margin for beam loss SPS / PS2 fixed target physics Nb of protons per PS2 cycle for PS2 / SPS fixed target physics R.G. 10

11 LHC beams from PS2 (i) Plans for future LHC injectors Nominal bunch train at PS2 extraction h=180 (40 MHz) with bunch shortening to fit SPS 200 MHz. 168 buckets filled leaving a kicker gap of ~ 300 ns (50 GeV!) Achieved by direct painting into PS2 40 MHz buckets using SPL chopping. No sophisticated RF gymnastics required. Beam parameters Extraction energy: 50 GeV Maximum bunch intensity: 4E11 / protons per LHC bunch (25 ns) Bunch length rms: 1 ns (identical to PS) Transverse emittances norm. rms: 3 μm (identical to PS) Any other bunch train pattern down to 25 ns spacing Straightforward with SPL 40 MHz chopping and 40 MHz system Again without sophisticated RF gymnastics Same brightness per bunch R.G. Chamonix

12 LHC beam from PS2 (ii) Plans for future LHC injectors Example 25 ns beam from LP SPL PS2: PS2 will provide twice ultimate LHC bunches with 25 ns spacing Bunch train for SPS twice as long as from PS Only 2 injections (instead of 4) from PS to fill SPS for LHC PS2 cycle length 2.4 s instead of 3.6 s for PS Reduces SPS LHC cycle length by 8.4 of 21.6 s (3x3.6 1x2.4) Reduced LHC filling time PS SPS injection plateau 3x3.6 s = 10.8 s up to 4 consecutive injections PS2 SPS plateau ~2.4 s 2 injections 1 2 Booster 1 2 Booster 1 2 Booster 1 2 Booster LP-SPL LP-SPL R.G. Chamonix

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14 Implementation stage 1: H - source RFQ chopper DTL CCDTL PIMS LINAC4 3 MeV 50 MeV 102 MeV 160 MeV ~ 80 m Implementation stages Ion species H Output Energy 160 MeV Bunch Frequency MHz Max. Rep. Rate 2 Hz Max. Beam Pulse Length 1.2 ms Max. Beam Duty Cycle 0.24 % Chopper Beam-on Factor 65 % Chopping scheme: 222 transmitted /133 empty buckets Source current 80 ma RFQ output current 70 ma Linac pulse current 40 ma N. particles per pulse Transverse emittance 0.4 π mm mrad Max. rep. rate for accelerating structures: 50 Hz H - charge exchange injection and painting in PSB 160/50 MeV factor 2 in βγ 2 ) same tune shift with twice the intensity. Re-use of LEP RF components: klystrons, waveguides, circulators. Chopping at low energy to reduce beam loss in PSB. Structures and klystrons dimensioned for 50 Hz Power supplies and electronics dimensioned for 2 Hz, 1.2 ms pulse. R.G. 14

15 Linac4 construction site from M. Vretenar Implementation stages Linac4 tunnel ( cut and cover excavation) seen from highenergy side. Final concrete works starting at low-energy side, excavation proceeding at high energy side. Tunnel level -12 m, length 100 m. Delivery of tunnel and surface equipment building end of R.G. 15

16 PSB and SPL connection area from M. Vretenar Implementation stages High-energy side of Linac4 tunnel, with beam dump chamber and connecting tunnel to the end of Linac2. R.G. 16

17 Implementation stage 1: Planning Implementation stages Task Name Linac4 project start Linac systems Source and LEBT construction, test Drawings, material procurement RFQ construction and commissioning Accelerating structures construction Klystron prototype production Klystrons production Transfer line construction and installation Magnets construction Power converters construction Building and infrastructure Building design and construction Infrastructure installation PS Booster systems PSB injection elements construction Installation and commissioning Test stand operation Cavities testing, conditioning Cabling, waveguides installation Accelerator installation Klystrons, modulators installation Hardware tests Front-end commissioning DTL1 commissioning Linac accelerator commissioning Transfer line commissioning PSB modifications PSB commissioning with Linac4 PSB beam ready for PS Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 01/01 01/ Milestones End CE works: December 2010 Infrastructure: 2011 Installation: Commissioning: Modifications PSB: shut-down 2013/14 Operation: 1 st of April 2014 project duration: ~ 6 years R.G. 17

18 Implementation stage 2: LP-SPL 0 m 0.16 GeV 110 m 0.73 GeV 186 m 1.4 GeV 427 m 4 GeV Implementation stages From Linac4 Medium β cryomodule 10 x 6 β=0.65 cavities High β cryomodules 5 x 8 β=1 cavities High β cryomodules Ion species H Output Energy 4 GeV Bunch Frequency MHz Max. Rep. Rate 2 Hz Max. Beam Pulse Length 0.9 ms Linac pulse current 20 ma Number of ions per pulse RF frequency MHz Cooling temperature 2 K Max. rep. rate for acc. structures & klystrons: 50 Hz Ejection TT6 to ISOLDE 13 x 8 β=1 cavities Debunchers To PS2 Length: ~430 m R.G. 18

19 Implementation stages Examples of SPL developments [from HIPPI inside CARE (EU FP6)] Elliptical 5 cell bulk Niobium cavities (e.g.: β=0.47) Auxiliary equipment (e.g.: 1 MW RF coupler) from G. Devanz (CEA) HIPPI meeting Nov. 2007) R.G. 19

20 Goal of the SPL study ( ) from Note on 31/03/2009 (EDMS Id ) The goal of the SPL study is to submit to the CERN Council in mid a detailed Conceptual Design Report and a cost estimate. Implementation stages For that purpose: cavities must be built and tested for a reliable assessment of the achievable gradient, a full size prototype cryomodule must be designed and assembled, the SM18 test place at CERN must be upgraded to allow for exercising multiple cavities in the prototype cryomodule at the nominal RF power, Civil Engineering and Integration must be studied, including safety and environment concerns. Multiple partners are already collaborating or are planning to collaborate: Member states institutions [CEA, IN2P3, DESY, Rostock & Frankfurt Universities, STFC- DL, ASTEC-RHUL, Cockcroft Institute, Soltan Institute, ESS (Lund, Bilbao,...),...] often with the support of the E.U., in the context of its FP7 programme ( slhc CNI-PP + EuCARD IA) Non-member states institutions [TRIUMF, Stony Brook/BNL, FNAL, SNS] and more are in discussion (USA, China, India, Turkey, Hungary,...) R.G. 20

21 Implementation stage 2: PS2 (1/4) Implementation stages Lattice with imaginary γ tr No transition crossing No beam losses at transition Simplification for operation by avoiding transition jump scheme More complicated lattice design and more magnet types/families than in e.g. regular FODO lattices Lattice structure Injection/extraction requirements limit tuning flexibility of long straight sections Arcs have to provide not only imaginary gamma transition but also tuning flexibility Regular arc modules Dispersion suppressor modules to match to straight sections Long straight sections with zero-dispersion Collaborations with LARP, US labs R.G. Chamonix

22 Implementation stage 2: PS2 (2/4) Implementation stages Transition gamma: 37i Tunes: / 8.25 (h/v) Beta max: 59 m (h and v) Dispersion min.: 2.8 m Dispersion max.: 3.3 m Relative chromaticities 1.65 / 1.59 (h/v) Circumference: m 166 dipoles, 3.78m long (1.7T field) 132 quadrupoles in = 17 families of 5+1 types (lengths and apertures), with max. strength of 0.1m 2 Not yet optimized R.G. Chamonix

23 Implementation stage 2: PS2 (3/4) Injection chicane Foil stripping optics H 0 (n=1), H D1 D2 D3 D4 Implementation stages QF B 0.13 T Chicane bump p +, H 0,H 140 mm 40 B~1.6 T p +, p + (H 0 n 2) Baseline is classical foil stripping with fast horizontal and vertical orbit bumpers for corr./uncorr. painting. Optimisation of insertion layout and optics to allow also integrating laser stripping. Collaboration with LARP and US Labs QF Laser stripping optics R.G. Chamonix

24 Implementation stage 2: PS2 (4/4) Fourth order tune 0.25 or 0.75 Tune variation 4 th order phase space topology Splitting of beam in 5 islands with sextupoles/octopoles Implementation stages Loss less splitting Extraction process Closed extraction bump taking the outer islands into the extraction channel Similar to slow extraction Outer island are extracted on four consecutive turns Central island as fifth turn with an additional kicker No losses with beam gap for kicker rise time. Phase space portrait Simulation parameters: Hénon like map (i.e. 2D polynomial degree 3 mapping) representing a FODO cell with sextupole and octupole Courtesy: M. Giovannozzi R.G. Chamonix

25 Implementation stage 2: Planning First milestones Project proposal: Project start: January Implementation stages Critical path: Design Study & Civil Engineering! Construction of LP SPL and PS2 will not interfere with the regular operation of Linac4 + PSB for physics. Similarly, beam commissioning of LP SPL and PS2 will take place without interference with physics. R.G. 25

26 Possible stage 3: High Power SPL Upgrade of infrastructure (cooling water, electricity, cryogenics etc.) Replacement of klystron power supplies, Addition of 5 high β cryomodules to accelerate up to 5 GeV (π production for ν Factory)? Implementation stages SC-linac [160 MeV 4 (5?) GeV] with ejection at intermediate energy From Linac4 0 m 0.16 GeV Medium β cryomodule 9 x 6 β=0.65 cavities 110 m 0.73 GeV High β cryomodules 11 x 8 β=1 cavities 291 m 2.5 GeV Ejection to EURISO L High β cryomodules 13 x 8 β=1 cavities 500 m 5 GeV Debunchers To PS2 and Accumulator Length: ~500 m R.G. 26

27 Possible stage 3: High Power SPL Implementation stages Faster rep. rate new power supplies, more cooling etc. Option 1 Option 2 Energy (GeV) 2.5 or and 5 Beam power (MW) 2.25 MW (2.5 GeV) or 4.5 MW (5 GeV) 5 MW (2.5 GeV) and 4 MW (5 GeV) Rep. frequency (Hz) Protons/pulse (x ) (2.5 GeV) + 1 (5 GeV) Av. Pulse current (ma) Beam characteristics of the main options Pulse duration (ms) (2.5 GeV) (5 GeV) 2 beam current 2 nb. of klystrons etc. R.G. 27

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29 Summary including recent news There has been significant progress during the past years in the definition of CERN future proton accelerators for the needs of LHC. A lower cost proposal is now competing, based on upgrades of the existing PSB and PS. A new strategy is in preparation for submission to the CERN Council in June. Final words HOWEVER Superconducting RF is a key technology for many future accelerator projects. It makes sense for CERN to be active in that field. A High Power SPL is of interest as a Proton Driver for EURISOL as well as for different types of Neutrino Facilities. In any case, safety and environmental issues will be important ingredients for any future Neutrino Facility (as well as for any future high energy Lepton Collider ). R.G. 29

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