KEKB Upgrade Plan Super KEKB J W Flanagan
KEKB Upgrade Plan: Super. KEKB J. W. Flanagan ASEPS 2010. 3. 24 J. W. Flanagan @ ASEPS 2010. 3. 24
Contents 1. Introduction – Super. KEKB Luminosity goal 2. Strategy: Nano-Beam Scheme – – Much smaller y* Larger crossing angle at IP & low emittance Same xy as KEKB Higher beam currents than KEKB 3. What we need – – – Lattice design for the Nano-beam scheme IR design Hardware 4. Schedule 5. Summary J. W. Flanagan @ ASEPS 2010. 3. 24
1. Introduction Super. KEKB Luminosity goal J. W. Flanagan @ ASEPS 2010. 3. 24
4 Target: 8 × 1035 cm-2 s-1 = 40 x World Record (KEKB) J. W. Flanagan @ ASEPS 2010. 3. 24
2. Strategy Nano-beam scheme – Much smaller y* – Larger crossing angle at IP & low emittance – Same xy as KEKB – Higher beam currents than KEKB J. W. Flanagan @ ASEPS 2010. 3. 24
6 Nano-beam Scheme H. Koiso • The scheme proposed by P. Raimondi and Super. B Group. • Squeeze y* as small as possible: 0. 27/0. 41 mm. • Assume beam-beam parameter = 0. 09 which has been already achieved at KEKB. • Change beam energies 3. 5 / 8 -> 4 /7 Ge. V to achieve longer Touschek lifetime and mitigate the effect of intrabeam scattering in LER. J. W. Flanagan @ ASEPS 2010. 3. 24
Three key factors for a factor of ~40 gain Stored current: Beam-beam parameter: 1. 7 / 1. 4 A (e+/ e- KEKB) 0. 09 (KEKB) 3. 6 / 2. 6 A (Super. KEKB) 0. 09 (Super. KEKB) Lorentz factor Classical elec. radius Beam size ratio Geometrical correction factors due to crossing angle and hour-glass effect 1(xy) x 20(1/ y*) x 2(I) = 40 Vertical β at the IP: 0. 21 × 1035 cm-2 s-1 (KEKB) 6. 5/5. 9 mm (KEKB) 8× 1035 cm-2 s-1 (Super. KEKB) 0. 27/0. 41 mm (Super. KEKB) J. W. Flanagan @ ASEPS 2010. 3. 24
Colliding bunches 8 Belle II New IR e- 2. 6 A New beam pipe & bellows Super. KEKB New superconducting /permanent final focusing quads near the IP e+ 3. 6 A Replace long TRISTAN dipoles with shorter ones (HER) Add / modify RF systems for higher beam current Low emittance positrons to inject Redesign the HER arcs to squeeze the emittance Ti. N-coated beam pipe with antechambers Positron source Damping ring New positron target / capture section Low emittance gun Low emittance electrons to inject x 40 Gain in Luminosity J. W. Flanagan @ ASEPS 2010. 3. 24
Super. KEKB Parameters as of Feb. 15, 2010 KEKB Design KEKB Achieved : with crab Super. KEKB Energy (Ge. V) (LER/HER) 3. 5/8. 0 4. 0/7. 0 Crossing angle (mrad) 22 0 (crab) 83 βy* (mm) 10/10 5. 9/5. 9 0. 27/0. 41 εx (nm) 18/18 18/24 3. 2/2. 4 σy(μm) 1. 9 0. 94 0. 059 ξy 0. 052 0. 129/0. 090 0. 09/0. 09 σz (mm) 4 ~6 6/5 Ibeam (A) 2. 6/1. 1 1. 64/1. 19 3. 6/2. 62 Number of bunches 5000 1584 2503 1 2. 11 80 Luminosity (1034 cm-2 s-1) J. W. Flanagan @ ASEPS 2010. 3. 24
3. What we need • Lattice design for the Nano-Beam Scheme • IR design • Hardware J. W. Flanagan @ ASEPS 2010. 3. 24
Lattice design for the Nano-Neam Scheme • Low βy* • IR optics design, Local Chromaticity Corrector (LCC) • Low emittance • LER: Longer bending magnets to lower average energy of SR emitted in high dispersion regions (bends), and shorten wiggler period by factor of 2. • HER: Increase number of arc cells to lower dispersion in bends • Arc bends shortened and increased in number. • Wide dynamic aperture IR optics design QC 1, 2 magnets closer to IP Separated final quadrupole magnets Beam energy was changed reduce intra-beam scattering and increase Touschek lifetime for LER: 3. 5 to 4. 0 Ge. V, HER: 8. 0 to 7. 0 Ge. V Design target (Touschek) lifetime is > 600 sec (min. 400 sec) J. W. Flanagan @ ASEPS 2010. 3. 24
A. Morita KEKB Review Feb. 2010 Lattice design for the Nano-Neam Scheme Angle of 41. 5 mrad between HER orbit and Belle To save vertical emittance increase by anti-solenoid fringe fields J. W. Flanagan @ ASEPS 2010. 3. 24
13 Lattice A. Morita KEKB Review Feb. 2010 J. W. Flanagan @ ASEPS 2010. 3. 24
3. What we need • Lattice design for the nano-beam scheme • IR design • Hardware J. W. Flanagan @ ASEPS 2010. 3. 24
IR design M. Tawada KEKB Review Feb. 2010 QC 1 magnets closer to IP Superconducting & permanent magnets 83 mrad Full crossing Boundary between accelerator & detector is same as at present Superconducting magnets: • Leakage fields of SC magnets canceled by correction windings on the other beam pipe • Warm bore Permanent magnets: • Cryostats can be made smaller • Vacuum pump can be located near IP J. W. Flanagan @ ASEPS 2010. 3. 24
3. What we need • Lattice design for the Nano-Beam Scheme • IR design • Hardware J. W. Flanagan @ ASEPS 2010. 3. 24
Injectors & Damping ring • The injected beam should have very low emittance because of poor dynamic aperture of the main rings. J. W. Flanagan @ ASEPS 2010. 3. 24
(1)Damping Ring for LER Injection M. Kikuchi KEKB Review Feb. 2010 Lattice Design almost completed. (2)Low emittance RF gun for HER S. Ohsawa, T. Sugimura KEKB Review Feb. 2010 J. W. Flanagan @ ASEPS 2010. 3. 24
Vacuum Straight duct Bellows chamber BPM RF-shield (gate valve) Y. Suetsugu Feed through for NEG Gate valve Basic R&D on components has almost finished. Optimization of design should be required considering the cost. Aluminum beam ducts. J. W. can. Flanagan be used for LER. @ ASEPS 2010. 3. 24
Y. Suetsugu KEKB Review Feb. 201 Vacuum: Electron cloud suppression NEG strip Beam ducts with ante-chambers – Low beam impedance • Pump ports and SR masks locate in an antechamber. – Fit to the existing (reused) magnets. – Ti. N coating to reduce secondary electron yield • Effectiveness demonstrated at PEP-II (Roundness) Rt Clearing electrodes and grooved structures developed for electron cloud suppression Collaboration with Cornell, SLAC, LBL d by L. Wang et al. (Depth) Groove An insertion for test with a thin electrode 400 mm x 40 mm B Tungsten (t 0. 1) 7 R 4 Al 2 O 3 (t 0. 2) Stainless steel Monitor Y. Suetsugu, H. Fukuma, M. Pivi and L. Wang, NIM-PR-A, 598 (2008) 372 Y. Suetsugu, H. Fukuma, M. Pivi and L. Wang, NIM-PR-A, 604 (2009) 449 J. W. Flanagan @ ASEPS 2010. 3. 24
Higher-Order Mode dampers RF system 2 ARES cavties/klystron to 1/klystron for more power Low total RF voltage is obtained while each cavity is operated at a high voltage. J. W. Flanagan @ ASEPS 2010. 3. 24
Magnet and power supplies • Main dipole magnets need to be replaced for both HER and LER rings. – LER dipoles become longer (Leff 0. 89 m ⇒ 3. 99 m) : 104 needed – HER dipoles become shorter (Leff 5. 91 m ⇒ 3. 8 m) : 144 needed • 112 wiggler magnets with shorter pole length (half pole)& 56 single pole wiggler needed. • More dipole, quadrupole and sextupole magnets are needed in HER since number of cells increased (~30 % more magnets). ⇒Magnet & power supply design & production & field measurements (from 500 to 1000 magnets need to be measured) • Most of the magnets will be relocated to new positions. ⇒Realignment is necessary. J. W. Flanagan @ ASEPS 2010. 3. 24
23 Beam Instrumentation • Beam Position Monitors – For high currents, and fast (~k. Hz) orbit vibration feedback • Bunch-by-bunch Feedback – Next generation system being developed in collaboration with SLAC, INFN, others • Beam size monitors for low-emittance beams – Synchrotron Light Monitors – X-ray Monitors (collaboration including Cornell) • Collision monitor – Beamstrahlung Monitor • Gated measurements J. W. Flanagan @ ASEPS 2010. 3. 24
Schedule J. W. Flanagan @ ASEPS 2010. 3. 24
K. Akai 25 Presuppositions • We present fastest possible schedule with following presuppositions: – Not a small part of budget allocated to KEK in JFY 2010 be assigned to KEKB upgrade by the KEK Executive Board. – Positive decision be made by the committee for largescale projects in MEXT by this summer. – Budget for the Damping Ring tunnel and buildings be allocated in JFY 2011 by the Japanese Government. – Full approval of the overall project, Super. KEKB, be made in JFY 2011 by the Japanese Government. J. W. Flanagan @ ASEPS 2010. 3. 24
K. Akai Feb. 2010 Super. KEKB Main Ring schedule FY 2009 FY 2010 FY 2011 FY 2012 FY 2013 FY 2014 MR commissioning Beam operation Tunnel clear Remove magnets and beam pipes Base plates Beam pipes (LER_wiggler) Fabrication Ti. N coating Beam pipes (LER_arc) Design Install Fabrication Ti. N coating Beam pipes (HER_arc) Design Fabrication Install Magnets & Power supplies Design / Fabrication Field measurement Install Cabling / Check Alignment Beam monitors and Control R&D / Fabrication RF reinforcement Layout change / Add stations / Cavity improvements IR hardware QCS R&D QCS fabrication J. W. Flanagan @ ASEPS 2010. 3. 24 Test Condit ioning Install & test 2 nd?
K. Akai Feb. 2010 27 Injector upgrade and DR construction schedule FY 2009 Linac FY 2010 FY 2011 FY 2012 FY 2013 FY 2014 e+ new matching & L-band acc. R&D Construction A 1 gallery extension Commisioning at test stand RF-gun & laser system Design study e+ beam commissioning move to A 1 e- beam commisioning Damping Ring DR commissioning Magnets & Power supplies B&Q mag. design/fabricate Beam pipes Other magnets Power supplies Field measurement Install Fabrication Monitors, Control Install Fabrication Install RF System cavity design cavity fabrication HP test Tunnel & building Base plan Design align. cavity install HP&LLRF install Tunnel construction Building construction Main Ring Beam operation MR construction J. W. Flanagan @ ASEPS 2010. 3. 24 MR commissioning
Summary J. W. Flanagan @ ASEPS 2010. 3. 24
29 • Summary H. Koiso KEKB Review Feb. 2010 Nano-Beam Design: – Lattice: solutions exist, preserving the present tunnel. Optimization of dynamic aperture is ongoing. – IR: large crossing angle, independent quadrupoles for both beams. – Electron cloud mitigation has been studied at KEKB. – RF system will be added and modified to store beam currents twice those of present KEKB. – Design of e+ damping ring has been done. – Low-emittance electron gun will be installed in linac. • Construction Schedule: – Target schedule: Super. KEKB commissioning starts at the beginning of JFY 2014. J. W. Flanagan @ ASEPS 2010. 3. 24
Spares J. W. Flanagan @ ASEPS 2010. 3. 24
Facilities • • Storage and staging areas needed for magnet and vacuum components. Need increased cooling water for klystrons and magnets: – – • 24 klystrons for ARES cavities, 8 klystrons for SCC Magnet cooling water needs double (4 plants -> 8) Electricity: Electricity Consumption: June-09 KEKB/KEK total (Design option) KEKB: MW ΔMW Present(Average) 45 KEK: MW ΔMW 64 Nano Beam: June-09 70. 7 24. 3 96 32 Upgrade: Feb. -09 94. 8 49. 8 120 56 Super: ‘ 07 -July 102. 6 57. 6 128 64 Recent Design(Feb. -10): Add 2 ARES units--> +(3~4)MW Ono KEKB Review Feb. 2010 J. W. Flanagan @ ASEPSM. 2010. 3. 24
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