Slide 1

M. E. Biagini, INFN/LNF EPS-HEP, Stockholm July 20 th 2013 Slide 2 Flavour Factories Past: PEP-II @ SLAC, USA KEKB @ KEK, Japan Present: DA NE @ INFN-LNF, Italy Vepp2000 @ BINP, Russia BEPCII @ IHEP, China Future: SuperKEKB @ KEK Proposals: Tau-Charm @ BINP, INFN, IHEP, TAC (Turkey) Slide 3 Super TC Linear Circular Xbeam Super BF e+e- colliders Luminosity vs Energy Slide 4 The past Slide 5 PEP-II B-Factory 1999-2008 Slide 6 KEKB B-Factory 1999-2010 Slide 7 Integrated Luminosity Slide 8 KEKB tried crab cavities Crab cavities installed in Feb. 2007 at KEKB and worked very well until the end of the KEKB operation Highest luminosity with the crab cavities was about 23% higher than that before crab (prediction by bb simulation: ~100% increase) Tuning with skew-sextupole magnets was effective to increase the luminosity with the crab cavity (~15% gain) Found that skew-sextupoles are also effective to increase the luminosity when the crab cavities were switched off Slide 9 Recipes for success a) Efficient injection system Trickle injection b) Tuning knobs beam control c) Strenuous instabilities fight e-cloud mitigation, bunch-by-bunch feedbacks d) Higher currents than design see a) e) New ideas (crab cavities, skew sextupoles) f) Stable RF system g) Powerful diagnostics see b) h) Skilled and expert staff Slide 10 Standard Collision Scheme Limitations 1. Hourglass effect limits minimum IP : y * z 2. Bunch length reduction not advisable bunch lengthening, microwave instability, CSR 3. Further multibunch current increase would result in coupled bunch instabilities, HOM heating, higher wall-plug power 4. Higher emittances conflict with beam stay-clear and dynamics aperture limitations 5. Tune shifts saturate, beam lifetime drops due to beam-beam interactions Slide 11 Less than 10 years ago the brute force (increasing currents) was the only approach to higher luminosity P. Raimondi (LNF) studied a new collision scheme with larger crossing angle and lower IP beam sizes (Large Piwinski Angle) PLUS a couple of sextupoles to twist the IP waist and cure x-y and synchro-betatron resonances raising from the angle (Crab Waist). Test at DA NE Adopted by all Factory projects after 2008 Changing the approach Oide, Progress of Theoretical Physics, Vol. 122, No. 1, July 2009 Slide 12 1.Large Piwinskis angle = tg( z / x 2. Vertical beta comparable with overlap area y 2 x / 3. Crab waist transformation y = xy/ Crab Waist Advantages a)Luminosity gain with N b)Very low horizontal tune shift c)Vertical tune shift decreases with oscillation amplitude a)Geometric luminosity gain b)Lower vertical tune shift c)Suppression of vertical synchro-betatron resonances a)Geometric luminosity gain b)Suppression of X-Y betatron and synchro-betatron resonances Slide 13 ....and besides a)No need to increase excessively beam current and to decrease the bunch length: 1)Beam instabilities are less severe 2)Manageable HOM heating 3)No coherent synchrotron radiation of short bunches 4)No excessive power consumption b)Problem of parasitic collisions automatically solved due to higher crossing angle and smaller horizontal beam size c)Less hourglass y * can be decreased Slide 14 Crab sextupoles effect Crab sextupoles are strong and introduce large non- linearity, optics between them has to be linear as much as possible Dynamic Aperture is greatly reduced. Solutions: Design IP doublet so to compensate the kynematic (octupole) and fringing field effects Locally compensate the chromaticity (Y and X separately) Add octupoles and additional sextupoles to compensate for the aberrations induced by the off-phase sextupoles Adjust and phase advance between crab sextupoles Done for SuperB and Italian Tau/Charm: effect is reduced (not cancelled) Slide 15 Design & operation challenges Ultra low emittances (H, V) Coupling compensation Interaction Region and Final Focus design (Low *, IP quadrupoles) Dynamic aperture (with fringing fields in IP quads and crab sextupoles) Tolerances to machine errors and vibrations Low Emittance Tuning Impedance budget Lifetimes (bb bremsstrahlung, Touschek) trickle charge injection High backgrounds detector protection High beam currents injection system Extreme vacuum with high currents Short bunch distance kickers, feedbacks Instabilities control (collective effects, b-by-b feedbacks) Adequate diagnostics (SLM, BPM, BLM, b-by-b luminosity monitor) On-line tuning knobs orbit, IP waist, dispersion, coupling, IP b, tunes, IP angles . Slide 16 Synergies Most of the above topics (except for high beam currents and beam-beam issues) apply to modern design of 4 th generation Synchrotron Light Sources Low emittance tuning techniques (LOCO, LET, ) successfully applied Record emittances measured at Diamond, SLS, ASLS ( y < 2 pm) Dynamic Aperture optimization techniques (MOGA, FMA, ) give larger momentum and transverse acceptances The two communities actively collaborate (see for example 3 rd LOWeRING Workshop at Oxford, EuCARD2) http://www.physics.ox.ac.uk/lowemittance13/index.asp Slide 17 The present Slide 18 DA NE @ INFN-Frascati First -Factory with Large Piwinski Angle and Crab Waist collision scheme (adapted to previous IR design) 3xLuminosity boost with non magnetic detector SIDDHARTA Proven effectiveness of crab sextupoles (very good agreement with numerical predictions and simulations) New Interaction Region for KLOE2 magnetic detector Limited in beam currents (e-cloud, damaged bellows, short lifetime), but e-cloud clearing electrodes successful in increasing threshold, and..lot of work in 2013 for replacement/upgrade of old hardware in progress resume operation by this Summer Slide 19 Effect of crab waist scheme Design Goal CRAB OFF CRAB ON Slide 20 Luminosity [10 28 cm -2 s -1 ] Comparison of best runs with and without Crab-Waist Slide 21 VEPP-2000, BINP, Round Beams Slide 22 Round Beams Collisions Round beams experiment: geometrical factor gain beam-beam limit enhancement 2 pairs of superconducting focusing solenoids in the 2 Interaction Regions symmetrically with respect to IPs Several combinations of solenoid polarities satisfy Round Beams condition: Normal Round (++ --) Mbius (++ -+) Double Mbius (++ ++) Two Flat combinations (+- +- or +- - +) more simple and also satisfy RBC if the betatron tunes lie on the coupling resonance 1 - 2 = 2 Small Dynamic Aperture Slide 23 VEPP-2M data Simulations 2010-2011 run, 2011-2012 run, 2012-2013 run DA and IBS lifetime Flip-flop Lack of e+ Luminosity vs Energy Slide 24 BEPC-II, IHEP Major upgrade of BEPC in 2004 Presently only existing /charm Slide 25 Slide 26 Luminosity tuning Luminosity increased x 0.5 Low p lattice lower and z Slide 27 The near Future Slide 28 40 times higher luminosity 2.1x10 34 --> 8x10 35 cm -2 s -1 KEKB to SuperKEKB Colliding bunches Nano-Beam scheme extremely small y * low emittance Beam current double Redesign the lattice to squeeze the emittance (replace short dipoles with longer ones, increase wiggler cycles) Replace beam pipes with TiN-coated beam pipes with antechambers New superconducting final focusing magnets near the IP New e+ Damping Ring Upgrade positron capture section Upgrade to Belle II detector e - 2.6A e + 3.6A Injector Linac upgrade DR tunnel Improve monitors and control system Low emittance RF electron gun Reinforce RF systems for higher beam currents 28K. AKAI, Progress in Super B-Factories, IPAC13 Slide 29 parameters KEKB (@record) SuperKEKB units LERHERLERHER Beam energy EbEb 3.5847.007 GeV Crossing angle (full) 2283 mrad # of Bunches N15842500 Horizontal emittance xx 18243.24.6 nm Emittance ratio 0.880.66 0.270.28 % Beta functions at IP x * / y * 1200/5.932/0.2725/0.30 mm Max. beam currents IbIb 2.01.43.62.6 A Beam-beam param. yy 0.1290.090 0.08810.0807 Bunch Length zz 6.0 5.0 mm Horizontal Beam Size xx 150 1011 um Vertical Beam Size yy 0.94 0.0480.062 um Luminosity L2.1 x 10 34 8 x 10 35 cm -2 s -1 Intra-beam scattering is included. Parameters of KEKB and SuperKEKB 29K. AKAI, Progress in Super B-Factories, IPAC13 Slide 30 Eight final focus QCS with 40 corrector coils are to be used. Fabrication of QCS-L started in July 2012, and will be completed in JFY2013. Fabrication of QCS-R is scheduled in JFY2013 and 2014. Prototype magnet was made at KEK. Test results show sufficient margin for operation. Corrector coils are being wound at BNL under BNL/KEK collaboration. Successfully tested without any quench up to 2157A, well over the design current (1560A) for nominal operation. I 4S /I c@4.7K = 62.8% I 12GeV /I c@4.7K = 87.0% Sufficient margin for operation QC1LE prototype magnet Final focus SC quads (QCS) 30K. AKAI, Progress in Super B-Factories, IPAC13 Slide 31 Commissioning Scenario First target luminosity 1 x 10 34 cm -2 s -1 Baseline Scenario Phase 1 Jan. 2015 - ~5 months Phase 2 ~4 months [Phase 1]No QCS, No Belle II Basic machine tuning, Low emittance tuning Vacuum scrubbing ( 0.5 ~ 1.0 A, >1 month) DR commissioning start (~Apr. - ) [Phase 2]With QCS, With Belle II (without Vertex Detector) Small x-y coupling tuning, Collision tuning y* will be gradually squeezed Background study [Phase 3]With Full Belle II Increase beam current with adding more RF Increase luminosity TOP PXD/SVD ready CDC installation Phase 3 31K. AKAI, Progress in Super B-Factories, IPAC13 Commissioning Scenario Slide 32 The possible Future Slide 33 Super /charm proposals Italian Tau/Charm BINP Tau/Charm IHEP Tau/Charm Turkish Charm 2 rings Linac+rin g Luminosity (cm -2 s -1 ) 1 x 10 35 1.4 x 10 35 Circumference (m)340360/800990250 (600?) Beam energy (GeV)1 2.30.5 231 + 3.56 Emittance H (nm)53/101016 Coupling (%)0.250.5 0.3 IP (x,y) (mm) 70, 0.6200,0.6/20, 0.761000, 180, 5 bb V tune shift0.64 0.080.095 0.170.060.12 Crab waistYES NO Beam current (A)1 1.71.8 1.72.70.48 + 4.8 N. of bunches530418540125 Slide 34 Italian /Charm Factory Evolution after cancellation of SuperB Energy tunable in the range E cm = 1-4.6 GeV 10 35 cm -2 s -1 luminosity at the /charm threshold and upper Symmetric beam energies Longitudinal polarization in the electron beam (60-70%) Possibility of e - e - collisions (to be studied) Design based on Large Piwinski angle & crab waist sextupoles collision scheme Low beam emittance (about 2 nm natural) Wigglers needed at lower beam energy Injection system scaled from the SuperB one Possibility to use injection Linac + additional C-band Linac for a 6 GeV SASE-FEL facility Slide 35 /charm parameters vs E Slide 36 /charm @Tor Vergata (former SuperB site) Tau/Charm Accelerator Report just written (150 pp, not public yet) Slide 37 Summary Higher luminosity colliders can still be built, profiting from: experience from past successes new ideas new technologies synergy with other communities A Super Factory is being built at KEK very important to keep alive this kind of Accelerators and Physics ! Several proposal for lower energy High Luminosity Flavour Factories on the market at different laboratories with experience of successful accelerators Slide 38 Aknowledgments For the material presented here Im indebted with: K. Akai, Y. Funakhoshi, KEK Q. Qing, Y. Zhang, IHEP M. Zobov, INFN-LNF A. Bogomiagkov, I. Koop, D. Schwartz, BINP Slide 39 Spare slides Slide 40 BINP Super cTau (2 nd design) Beam energy from 0.5 to 2.1 GeV Peak luminosity 10 35 cm -2 s -1 at 2 GeV and within as wide as possible energy range Circumference 366 m to fit in the existent tunnel of VEPP4-M (previous design 800m) Conform as much as possible to existent infrastructure Longitudinal polarization at some energy points Slide 41 Parameters Energy2.0 GeV1.5 GeV1.0 GeV0.5 GeV Circumference368 m Beta IP hor/ver20 cm / 0.6 mm Emittance hor/ver with ibs @ 0.5% coupling 3.1 nm 16 pm 2.7 nm 14 pm 5.5 nm 26 pm 18 nm 89 pm Crossing angle2x30 mrad Bunch length8 mm Energy spread110 -3 1.410 -3 3.310 -3 9.910 -3 RF frequency700 MHz Harmonic number864 Particles in bunch3.2510 10 3.1110 10 3.7810 10 3.5310 10 Number of bunches418 Total beam current1.8 A1.7 A2.1 A1.9 A Beam-beam parameter0.0950.130.17 Luminosity110 35 0.9810 35 0.3610 35 2 cm / 0.76 mm 10 nm 10 mm Old C-Tau, 800m 710 10 1.7 A Slide 42 IHEP Super Tau-Charm Factory Dual ring, factory like 2.5-3 GeV, parasitic 3 rd generation SR source Crab Waist collision scheme Small IP functions Small emittance using wigglers High beam current Electron beam polarization (e- source, 5 Siberian Snakes) Top-up injection at 3 GeV, 50 Hz Slide 43 IHEP Super Tau-Charm Factory Slide 44 Turkish Accelerator Complex (TAC) SCF TAC SCF presented to ECFA 2011 Linac (e-) + ring (e+) charm factory with L= 1.4 10 35 cm -2 s -1 Synchrotron light source based on positron ring Free electron laser based on electron linac TDR SCF@TAC will be completed in 2013 Slide 45 TAC Super Charm Factory parameters Parametere - -linace + -ring Energy, GeV1.003.56 Particles per bunch, 10 10 220 function at IP, mm 80/5 x / y / z, m/ m/mm 36/0.5/5 Beam current (A)0.484.8 Circumference, m600 Crossing angle, mrad34 Collision frequency, MHz150 Luminosity, cm -2 s -1 1.4 10 35