KEKB / SuperKEKB The Luminosity Frontier (number of events/unit - PowerPoint PPT Presentation

KEKB / SuperKEKB The Luminosity Frontier (number of events/unit time) = (cross section) X (luminosity) Katsunobu Oide (KEK) April 17, 2006 @ CERN http://kekb.jp

KEKB = Asymmetric Double-Ring Collider for B-Physics 8 GeV Electron + 3.5 GeV Positron Superconducting cavities (HER) 1989: Design work started. Belle detector 1994: Approval of the budget, e- construction started. June 1995: KEKB Design Report KEKB B-Factory e+ Sep. 1997: Commissioning of the injector Linac started. ARES copper Dec. 1998: First beam at HER. cavities (HER) Jan. 1999: First beam at LER. May 1999: Belle roll-in. ARES copper June 1999: First event at Belle. cavities (LER) Apr. 2001: World record of the TRISTAN luminosity, 3.4 /nb/s. tunnel Oct. 2002: World record of the integrated luminosity, 100 /fb. May 2003: Exceeded the design 8 GeV e- luminosity, 10 /nb/s. 3.5 GeV e+ Linac Feb. 2004: Exceeded 12 /nb/s & 200 /fb. e+ target Oct. 2004: 13.9 /nb/s & 300 /fb. May 2005: 15.3 /nb/s & 420 /fb. Dec. 2005: 16.3 /nb/s & 528 /fb. … continues rewriting own records …

Nikko Mt. Tsukuba Belle KEKB Rings KEK Site Linac

10 34 cm -2 s -1 600 /pb/day Achieved >500 /fb in 6.5 years. (Initial Goal: 100 /fb in 3 years.)

10 34 The best 24 hours > 1.2 /fb

54 /fb/mo Next Milestone We are here 27 /fb/mo. Crab Cavity Beam Test

SuperKEKB, The Next Step 10 36 10 36 Luminosity (cm -2 s -1 ) SuperKEKB 10 35 10 35 Integrated Luminosity KEKB design KEKB ILC PEP-II 10 34 10 34 CESR 10 33 10 33 Data doubling time LEP-II DAFNE 10 32 10 32 PEP TRISTAN DORIS BEPC LEP 10 31 10 31 PETRA VEPP-2M VEPP-4M SPEAR 10 30 10 30 ADONE 2 2 3 3 1 1 10 10 10 10 10 10 Shutdown for upgrade CMS Energy (GeV) • SuperKEKB is a natural extension of KEKB, the world leader in the luminosity frontier. • 8 × 10 35 cm -2 s -1 will be available with technologies proven at KEKB, together with a few modifications.

β * y = σ z = 3 mm Crab cavities will be SuperKEKB installed and tested with e- 9.4 A beam in 2006. e+ 4.1 A The state-of-art ARES The superconducting cavities will be copper cavities will be upgraded to absorb more higher-order upgraded with higher mode power up to 50 kW. energy storage ratio to support higher current.    *  I ± ξ ± y 1 + σ y R L L = γ ±     * * 2 er R y σ x β y     e The beam pipes and all vacuum components will be replaced with will reach 8 × 10 35 cm -2 s -1 . higher-current-proof design.

Three factors to determine luminosity: Stored current: Beam-beam parameter: 1.36/1.75 A (KEKB) 0.059 (KEKB) → 4.1/9.4 A (SuperKEKB) → >0.24 (SuperKEKB) Lorentz factor    *  I ± ξ ± y 1 + σ y R L L = γ ±     * * 2 er R y σ x β y     e Geometrical reduction factors due to crossing angle and hour-glass e fg ect Classical electron radius Beam size ratio Vertical β at the IP: Luminosity: 6.5/5.9 mm (KEKB) 0.16 × 10 35 cm -2 s -1 (KEKB) → 3.0/3.0 mm (SuperKEKB) 8 × 10 35 cm -2 s -1 (SuperKEKB)

New Parameter Set for 8 × 10 35 -- by K. Ohmi • Good parameters are not yet found with crab waist. 10

Why was higher luminosity made possible? • 8 × 10 35 cm -2 s -1 is achievable with same beam currents, beta, bunch length as 4 × 10 35 cm -2 s -1 . • The simulation was improved by more longitudinal slices to reduce the numerical noises and the instability, using a new supercomputer at KEK. • A new choice of parameters with smaller emittance ratio or smaller horizontal emittance. • Crab crossing is necessary. • No crab waist, travel focus are needed for luminosity, but may help the lifetime. 11

Increase number of longitudinal slices in the simulation ε x =18nm, ε y =0.09nm, β x =0.2m β y =3mm σ z =3mm Lower coupling gives higher luminosity, but numerical instability occurs with less number of slices. K. Ohmi 5 slices 10 slices

Smaller emittances K. Ohmi 1e+36 8e+35 10 slice 6e+35 L 4e+35 2e+35 ex=9nm 0 0 0.02 0.04 0.06 0.08 0.1 ey (nm) ex = 18 nm ex = 9 nm • For ex = 18 nm, smaller ey gives higher luminosity. • For ex = 9 nm, luminosity is high up to ey/ex < 1%.

Traveling waist • Particles with z collide with central part of another beam. Hour glass effect still exists for each K. Ohmi particles with z. • No big gain in Luminosity. ε x =24 nm ε y =0.18nm • Life time is improved. β x=0.2m β y =1mm σ z=3mm

Traveling of positron beam K. Ohmi

SuperKEKB R&D • Crab cavities • Vacuum components for high current: antechambers, coating, bellows, collimators, etc. • Superconducting quadrupole • High power RF components • Bunch-by-bunch feedback • C-band linac • Beam diagnostics

Crab crossing is coming soon @ KEKB!  Crab crossing will boost the beam-beam parameter up to 0.19! K. Ohmi Head-on(crab) (Strong-strong simulation) crossing angle 30 mrad (at the optimum tune)  Superconducting crab cavities are under development, and will be installed in KEKB in 2006 . Input Coupler I.R. 90 I.D. 120 I.D. 240 I.D. 188 I.R.241.5 Coaxial Coupler 866 I.R. 20 I.D. 30 Monitor Port 100 150 0 50 483 scale (cm) K. Hosoyama, et al

Crab cavity He jacket

Cryostat & couplers Input coupler was conditioned successfully. K. Hosoyama, et al

1. Beam Duct with Ante-chambers  Beam duct with two antechambers (2005)  Model: for wiggler section  OFC( t 6), w 224, h 94, L 4.7 m  Fabrication methods:  Forming (from plates)  Manufacturing was successful.  Degree of accuracy should be Forming improved in future Inside view Final check 2006/3/21 2006 KEKB Review 20

2. Bellows Chamber and Gate Valve  Application of Ver.2 to antechamber-type bellows  Manufactured at BINP (2005)  Copper cooling channel  Improve cooling of teeth  Two bellows chamber were installed into LER wiggler (2005).  No problem was found up to 1.7 A. 2006/3/21 2006 KEKB Review 21

3. Vacuum Flange  Application to bellows chamber and ducts (2005)  MO-flange was applied to beam duct with ante-chambers and their bellows chambers, and installed into LER.  No problem was found up to 1.7 A.  Temperature of bellows was almost same to conventional ones (circular). ~30 ° C . SS flange Bellows chamber Cu gasket MO-type flange for beam duct with MO-type flange for bellows chamber antechambers for wiggler section 2006/3/21 2006 KEKB Review 22

4. Movable Mask  Stealth type Ver.4 at present  Has been studied since 2003  Features  Ceramics support  Little interference with beam  Carbon head Head (C)  Little damage by beam  With HOM absorber (SiC) SiC  R&D points (still preliminary)  Trapped mode SiC  Heating of head  Charge up Support (ceramics) Beam  Experimental demonstration Beam duct 2006/3/21 2006 KEKB Review 23

LC との連携（２）（加藤） In-situ Measurement System of Secondary Electron Yields at Positron Ring of the KEKB <Features> ★ In-situ Measurements of Secondary Electron Yields at Surfaces Exposed to Positron Beam of the KEKB ★ Primary Electron Beam : 50eV~5KeV, Beam Scan Capability ★ Quick Sample Exchanging Capability with Loadlock Chamber (N.A. @CERN) ★ Electron Activity Monitoring Close to Sample @ Beam Chamber <Achievement and Plan> ◆ PY2005 : designing and manufacturing of the system 1. installation of a copper beam chamber in a straight 2. Gate section at the KEKB. Valve Positron Beam a measurement system is being tested in a lab.. 3. Chamber the whole setup will be installed onto the chamber Electron 4. and the measurement will get started. Source ◆ PY2006 : Electron a series of the experiments 1. Sample Manipulator Monitor installation of a setup for short & long term exposure 2. capability installation of a setup for gas puffing capability ( H 2 , Loadlock Chamber 3. CO etc ) installation of a residual gas analyzer 4. Sample Manipulator

Construction of QCS R&D Magnet (2-4) 12 Cured Coils and curing 6 layer coils all at once (1) (1) 12 cured double pan-cake coils. (2) (2) Curing process of 6 layer coils. This process is necessary for improving the field quality in the

High power RF R&D • Upgrade of ARES with higher energy storage ratio. (left) • High power rf input couplers. • SiC dummy load with higher power capability (right).

Superconducting Cavity SuperKEKB challenges: Storing world’s highest beam current of 1.2A. The expected power load to the HOM Input coupler has been operated up to 380kW. absorber is 50 kW/cavity at 4.1 A, Ferrite Higher Order Mode (HOM) (even) with a larger beam pipe of 220 mm φ . absorber working at 10 kW (has achieved 12kW at 1.2 A). HOM damper upgrade may be needed.

A prototype of the new bunch-by-bunch feedback system (G-board / Gproto) was tested at KEKB and ATF. The results were quite successful. •Even in single-bunch mode, we observed a strong longitudinal instability at the ATF. •In multi-bunch mode, we observed a strong CBI. •Successfully damped the longitudinal CBI with the BxB feedback system using Gproto down to 1/10. •Successfully analyzed strongest coupled-bunch mode. (218+n*357 MHz) •For practical use, it will be necessary to build and install a good feedback kicker.