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Status and Perspectives of High Luminosity Flavour Factories. M. E. Biagini, INFN/LNF EPS-HEP, Stockholm July 20 th 2013. Flavour Factories. Past: PEP - II @ SLAC, USA KEKB @ KEK, Japan Present: DA F NE @ INFN-LNF, Italy Vepp2000 @ BINP, Russia BEPCII @ IHEP, China Future :

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status and perspectives of high luminosity flavour factories

Status and Perspectives of High Luminosity FlavourFactories

M. E. Biagini, INFN/LNF

EPS-HEP, Stockholm July 20th 2013

flavour factories
Flavour Factories
  • Past:
    • PEP-II @ SLAC, USA
    • KEKB @ KEK, Japan
  • Present:
    • DAFNE @ INFN-LNF, Italy
    • Vepp2000 @ BINP, Russia
    • BEPCII @ IHEP, China
  • Future:
      • SuperKEKB @ KEK
  • Proposals:
    • Tau-Charm @ BINP, INFN, IHEP, TAC (Turkey)
e e colliders luminosity vs energy
e+e- colliders Luminosity vsEnergy

Super BF



Super TC

kekb tried crab cavities
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
recipes for success
Recipes for success
  • Efficient injection system  Trickle injection
  • Tuning knobs  beam control
  • Strenuous instabilities fight  e-cloud mitigation, bunch-by-bunch feedbacks
  • Higher currents than design  see a)
  • New ideas (crab cavities, skew sextupoles)
  • Stable RF system
  • Powerful diagnostics  see b)
  • Skilled and expert staff

Standard CollisionSchemeLimitations

1. Hourglass effect limits minimum IP b:by* ≤ sz

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

beamstay-clear and dynamics aperture limitations

5. Tune shifts saturate, beam lifetime drops due to

beam-beam interactions


Changing the approach…

  • 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 DAFNE
  • Adopted by all Factory projects after 2008

Oide, Progress of Theoretical Physics, Vol. 122, No. 1, July 2009



  • Luminosity gain with N
  • Verylowhorizontaltuneshift
  • Vertical tuneshiftdecreases with oscillationamplitude
  • Large Piwinski’s angle
  • F = tg(q/2)sz/sx
  • 2. Vertical beta comparable
  • with overlap area
  • by 2sx/q

3. Crabwaisttransformation

  • y = xy’/q
  • Geometricluminosity gain
  • Lower verticaltuneshift
  • Suppression of verticalsynchro-betatronresonances
  • Geometricluminosity gain
  • Suppression of X-Y betatron and synchro-betatronresonances

....and besides…

  • No need to increaseexcessivelybeamcurrent and to decrease the bunchlength:
    • Beaminstabilities are less severe
    • Manageable HOM heating
    • No coherentsynchrotronradiation of short bunches
    • No excessivepowerconsumption
  • Problem of parasiticcollisionsautomaticallysolved due to highercrossing angle and smallerhorizontalbeamsize
  • Lesshourglassby* can be decreased
crab sextupoles effect
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 b and phase advance between crab sextupoles
  • Done for SuperB and Italian Tau/Charm: effect is reduced (not cancelled)
design operation challenges
Design & operation challenges
  • Ultra low emittances (H, V)  Coupling compensation
  • Interaction Region and Final Focus design (Low b*, 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
  • ….
  • Most of the above topics (except for high beam currents and beam-beam issues) apply to modern design of 4th generation Synchrotron Light Sources
  • Low emittance tuning techniques (LOCO, LET, …) successfully applied
  • Record emittances measured at Diamond, SLS, ASLS (ey < 2 pm)
  • Dynamic Aperture optimization techniques (MOGA, FMA, …) give larger momentum and transverse acceptances
  • The two communities actively collaborate (see for example 3rdLOWeRING Workshop at Oxford, EuCARD2)

da f ne @ infn frascati
DAFNE @ INFN-Frascati
  • First F-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
effect of crab waist scheme
Effect of crab waist scheme

Design Goal



comparison of best runs with and without crab waist
Comparison of best runs with and without Crab-Waist

Luminosity [1028 cm-2 s-1]

Luminosity [1028 cm-2 s-1]

round beams collisions
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” (++ --)
    • “Möbius” (++ -+)
    • “Double Möbius” (++ ++)
    • Two “Flat” combinations (+- +- or +- - +) more simple and also satisfy RBC if the betatron tunes lie on the coupling resonance
    • n1- n2 = 2
  • Small Dynamic Aperture
luminosity vs energy
Luminosity vs Energy

Lack of e+

DA and IBS




VEPP-2M data

2010-2011 run,2011-2012 run,2012-2013 run

bepc ii ihep
  • Major upgrade of BEPC in 2004
  • Presently only existing t/charm
luminosity tuning
Luminosity tuning
  • Luminosity increased nx 0.5
  • Low ap lattice  lower e and sz

Upgrade to Belle II detector

Colliding bunches

New superconducting final focusing magnets near the IP

e+ 3.6A

e- 2.6A


Redesign the lattice to squeeze the emittance (replace short dipoles with longer ones, increase wiggler cycles)

  • Nano-Beam scheme
  • extremely small by*
  • low emittance
  • Beam current double

Reinforce RF systems for

higher beam currents

Replace beam pipes with TiN-coated beam pipes with antechambers

40 times higher luminosity

2.1x1034 --> 8x1035 cm-2s-1

Improve monitors and control system

Injector Linac upgrade

Upgrade positron capture section

DR tunnel

Low emittance

RF electron gun

New e+ Damping Ring

K. AKAI, Progress in Super B-Factories, IPAC13


Parameters of KEKB and SuperKEKB

Intra-beam scattering is included.

K. AKAI, Progress in Super B-Factories, IPAC13


Final focus SC quads (QCS)

  • 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.

QC1LE prototype magnet

Successfully tested without any quench up to 2157A, well over the design current (1560A) for nominal operation.

I4S/Ic@4.7K = 62.8%

I12GeV/Ic@4.7K = 87.0%

Sufficient margin for operation

K. AKAI, Progress in Super B-Factories, IPAC13

commissioning scenario

Commissioning Scenario

Commissioning Scenario



Phase 1

Jan. 2015 -

~5 months

Phase 2

~4 months

Phase 3

First target luminosity

1 x 1034 cm-2s-1



PXD/SVD ready


[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
  • by* will be gradually squeezed
  • Background study

[Phase 3] With Full Belle II

  • Increase beam current with adding more RF
  • Increase luminosity

K. AKAI, Progress in Super B-Factories, IPAC13

italian t c harm factory
Italian t/Charm Factory
  • Evolution after cancellation of SuperB
  • Energy tunable in the range Ecm = 1-4.6 GeV
  • 1035cm-2 s-1luminosity at the t/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
t charm @tor vergata former superb site
t/charm @Tor Vergata (former SuperB site)

Tau/Charm Accelerator Report just written (150 pp, not public yet)

  • 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
  • For the material presented here I’m indebted with:
    • K. Akai, Y. Funakhoshi, KEK
    • Q. Qing, Y. Zhang, IHEP
    • M. Zobov, INFN-LNF
    • A. Bogomiagkov, I. Koop, D. Schwartz, BINP


binp super ctau 2 nd design

Beam energy from 0.5 to 2.1 GeV

  • Peak luminosity 1035 cm-2s-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
BINP Super cTau (2nd design)

Old C-Tau, 800m

2 cm / 0.76 mm

10 nm

10 mm


1.7 A

ihep super tau charm factory
IHEP Super Tau-Charm Factory
  • Dual ring, factory like
  • 2.5-3 GeV, parasitic 3rd generation SR source
  • Crab Waist collision scheme
  • Small IP b functions
  • Small emittance using wigglers
  • High beam current
  • Electron beam polarization (e- source, 5 Siberian Snakes)
  • Top-up injection at 3 GeV, 50 Hz
turkish accelerator complex tac scf
Turkish Accelerator Complex (TAC) SCF
  • TAC SCF presented to ECFA 2011
  • Linac (e-) + ring (e+) charm factory with L= 1.41035 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