SuperB and Super KEKB SuperB and Super KEKB The Precision - PowerPoint PPT Presentation

SuperB and Super KEKB SuperB and Super KEKB The “ “Precision Frontier Precision Frontier” ” The U. Wienands U. Wienands SLAC, presently at CERN SLAC, presently at CERN Former PEP-II Run Coordinator Former PEP-II Run Coordinator I am indebted to M. Iwasaki and to M. Masuzawa, KEK, for providing me with I am indebted to M. Iwasaki and to M. Masuzawa, KEK, for providing me with material on Super KEKB material on Super KEKB U. Wienands, SLAC 1 U. de Paris, 16-Sep-10

Outline Outline • Introduction Introduction • • The Crab Waist The Crab Waist • • The SuperB proposals The SuperB proposals • • Conclusion Conclusion • U. Wienands, SLAC 2 U. de Paris, 16-Sep-10

B -Factories: Success Story -Factories: Success Story B 34 /cm 2 /s, about 0.5 ab –1 1 • PEP-II: 1.2 10 PEP-II: 1.2 10 34 /cm 2 /s, about 0.5 ab – • KEKB: 2.1 10 34 34 /cm /cm 2 2 /s, about 1 ab /s, about 1 ab – –1 1 • KEKB: 2.1 10 • • PEP-II/BaBar together with KEKB-Belle: PEP-II/BaBar together with KEKB-Belle: • – Definitive measurement of sin(2 ß ), solid foundation for CKM formalism – Exceeded their physics goals – Proved that multi-ampere beam currents can be handled • up to 3.2 A @ 3.1 GeV; 2 A @ 9 GeV in PEP-II – Proved that background is manageable • s.r. background as well as lost-particle background – Proved that high overall efficiency can be maintained • PEP-II/BaBar reached >85% up time U. Wienands, SLAC 3 U. de Paris, 16-Sep-10

Super B B -Factories -Factories Super • A growing momentum has built up to expand on A growing momentum has built up to expand on • the program and push for new reach on the the program and push for new reach on the “precision frontier precision frontier” ” “ –1 1 100 ab – • This physics reach is possible with 50 This physics reach is possible with 50… …100 ab • of data of data • In order to gather such an amount in a reasonable In order to gather such an amount in a reasonable • 36 cm –2 2 s –1 1 is time, a peak luminosity of ≈ ≈ 10 10 36 cm – s – is time, a peak luminosity of necessary necessary U. Wienands, SLAC 4 U. de Paris, 16-Sep-10

+ – Luminosity Trend e + e – e Luminosity Trend e U. Wienands, SLAC 5 U. de Paris, 16-Sep-10

Luminosity Equation Luminosity Equation • It then follows that, for fixed beam-beam parameter ξ , one • It then follows that, for fixed beam-beam parameter ξ , one needs higher beam current and/or lower ß needs higher beam current and/or lower ß y y * * . . U. Wienands, SLAC 6 U. de Paris, 16-Sep-10

Strategies Strategies • Head-on collisions ( R R L =1): hourglass becomes important • Head-on collisions ( L =1): hourglass becomes important – σ l ≥ 2 mm – > ß * ≥ 2 mm => need O(10) A beam current  • Crossing angle (horizontal): • Crossing angle (horizontal): – foreshortens the IP => ß* ≤ σ l is possible – > synchro-betatron coupling due to beam-beam   can reduce or eliminate the effect of crossing angle  • “Crab Waist Crab Waist” ” can reduce or eliminate the effect of crossing angle • “ – Raimondi, LNF, based on earlier work by Balakin, BINP – Successfully operated at DA Φ NE, Luminosity gain ≈ *2.5. U. Wienands, SLAC 7 U. de Paris, 16-Sep-10

High Beam Current/Short Bunches High Beam Current/Short Bunches • Problems of high beam current for short bunches: Problems of high beam current for short bunches: • BPM damage due to overheating Rf seal damage U. Wienands, SLAC 8 U. de Paris, 16-Sep-10

Crab Waist Crab Waist Crab sextupoles: n Crab sextupoles: n π π in x; in x; Raimondi (n+1/2) π (n+1/2) π in y from IP in y from IP Graphics by E. Paoloni Tune scan, red red=higher luminosity =higher luminosity Tune scan, U. Wienands, SLAC 9 U. de Paris, 16-Sep-10

DA Φ NE Luminosity DA Φ NE Luminosity Crab Waist U. Wienands, SLAC 10 U. de Paris, 16-Sep-10

Towards next-Generation B B -Factories -Factories Towards next-Generation • Both Both B B -Factory teams have proposed upgrades -Factory teams have proposed upgrades • exploiting this scheme: exploiting this scheme: – Super KEKB: Upgrade of existing KEKB – Super B : New facility, to be built at LNF in a collaboration of LNF, SLAC, several European Laboratories and BINP Novosibirsk. • While the challenges are similar for both facilities, While the challenges are similar for both facilities, • they differ in the details: they differ in the details: – Super KEKB: ≈ 3 km circumference (KEKB tunnel), no polarized beam, KEKB hardware – Super B : 1.25 km circumference, polarized electrons, PEP-II hardware U. Wienands, SLAC 11 U. de Paris, 16-Sep-10

Common Features Common Features • Energy asymmetry: 4 on 7 GeV Energy asymmetry: 4 on 7 GeV • • Crossing angle: Crossing angle: 2* 41.5 mr, 2*30 mr 2* 41.5 mr, 2*30 mr • • Small beam emittances (nmr in Small beam emittances (nmr in x x , pmr in , pmr in y y ) ) • – Beam aspect ratios ≈ 1/100 • Beam currents up to Beam currents up to ≈ ≈ 3.5 A or less 3.5 A or less • • Bunch length Bunch length ≈ ≈ 5 mm 5 mm • • Short beam lifetime ( Short beam lifetime ( ≈ ≈ 5 min) 5 min) • – continuous injection (“trickle charge”) U. Wienands, SLAC 12 U. de Paris, 16-Sep-10

KEKB/SuperKEKB KEKB/SuperKEKB U. Wienands, SLAC 13 U. de Paris, 16-Sep-10

KEKB Site KEKB Site U. Wienands, SLAC 14 U. de Paris, 16-Sep-10

Super KEKB Parameters Super KEKB Parameters U. Wienands, SLAC 15 U. de Paris, 16-Sep-10

Low Emittance Lattice Low Emittance Lattice • Achieving low emittance with minimum change Achieving low emittance with minimum change • – Replace short dipoles with longer ones for LER ≈ 100 0.89 m dipoles replaced with 4 m ones. U. Wienands, SLAC 16 U. de Paris, 16-Sep-10

SuperKEKB Lattice SuperKEKB Lattice Crab Crab U. Wienands, SLAC 17 U. de Paris, 16-Sep-10

Super B B Parameters Parameters Super + ) on 4.18 ( – ) GeV • Energy: Energy: 6.78 ( e e + ) on 4.18 ( e e – ) GeV • 6.78 ( • Half crossing angle: Half crossing angle: 30 mr • 30 mr • Horiz. emittance: Horiz. emittance: 2 on 2.5 nmr • 2 on 2.5 nmr • Vertic. emittance: Vertic. emittance: 5 on 6 nmr • 5 on 6 nmr • ß ß x / ß ß y at IP: 26/0.25 on 32/0.21 mm 32/0.21 mm • x / y at IP: 26/0.25 on • Beam currents: Beam currents: 1.9 on 2.5 A • 1.9 on 2.5 A • Beam-beam parameter Beam-beam parameter ξ : 0.097 • y : 0.097 ξ y • Beam lifetime: Beam lifetime: 4.2 on 4.5 min • 4.2 on 4.5 min 36 cm –2 2 s –1 1 • Luminosity: Luminosity: 1 × 10 36 cm – s – • 1 × 10 U. Wienands, SLAC 18 U. de Paris, 16-Sep-10

U. Wienands, SLAC 19 U. de Paris, 16-Sep-10

Super B B Tunnel Layout Tunnel Layout Super U. Wienands, SLAC 20 U. de Paris, 16-Sep-10

Low Emittance Lattice Low Emittance Lattice • Lattice near TME Lattice near TME • – synch.-rad. type design µ x = 3 π , µ y = π Cell in HER • In the LER, dipole In the LER, dipole • position adjusts the position adjusts the emittance emittance µ x = 3 π , µ y = π Cell in LER • ≈ ≈ 5 mm bunch 5 mm bunch • length length – acceptable U. Wienands, SLAC 21 U. de Paris, 16-Sep-10

LER Interaction Region LER Interaction Region • Spin Rotator outside local chromaticity correction Spin Rotator outside local chromaticity correction • V12 X-sext Y-sext Crab Match & SR U. Wienands, SLAC 22 U. de Paris, 16-Sep-10

Chromatic behaviour of the IP Chromatic behaviour of the IP • ß ß chromaticity ( chromaticity ( W W ) corrected at IP ) corrected at IP • – necessary condition for high momentum bandwidth U. Wienands, SLAC 23 U. de Paris, 16-Sep-10

SuperB LER Spin Rotation SuperB LER Spin Rotation • 90° spin rotation about x x axis axis • 90° spin rotation about – 90° about z followed by 270° about y • “flat flat” ” geometry => no vertical emittance growth geometry => no vertical emittance growth • “ • Solenoid scales with energy => LER more economical • Solenoid scales with energy => LER more economical • Solenoids are split & decoupling optics added. • Solenoids are split & decoupling optics added. IP HER LER S.r. dipoles Compton IP for polarimetry (270° spin) LER HER S.r. solenoids (90° spin) U. Wienands, SLAC 24 U. de Paris, 16-Sep-10

SuperB LER Polarization SuperB LER Polarization 3.5 min beam lifetime U. Wienands, SLAC 25 U. de Paris, 16-Sep-10

Polarimetry Polarimetry – detection • Compton polarimeter, Compton polarimeter, γ and e e – detection • γ and – bunch-by-bunch, < 1% systematic error U. Wienands, SLAC 26 U. de Paris, 16-Sep-10

Super KEKB Final-Focusing system Super KEKB Final-Focusing system • Crossing angle 83 mrad to make the FF magnets close to • Crossing angle 83 mrad to make the FF magnets close to IP IP U. Wienands, SLAC 27 U. de Paris, 16-Sep-10

Super KEKB IR Beam Pipe Super KEKB IR Beam Pipe • Crotched structures (Two FF Q-magnets in both Crotched structures (Two FF Q-magnets in both • sides) sides) • 1cm radius of vtx chamber 1cm radius of vtx chamber • e- e+ U. Wienands, SLAC 28 U. de Paris, 16-Sep-10