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

KEKB / SuperKEKB

The Luminosity Frontier

Katsunobu Oide (KEK) April 17, 2006 @ CERN

http://kekb.jp

(number of events/unit time) = (cross section) X (luminosity)

1989: Design work started. 1994: Approval of the budget, construction started. June 1995: KEKB Design Report

• Sep. 1997:

Commissioning of the injector Linac started.

• Dec. 1998: First beam at HER.
• Jan. 1999:

First beam at LER. May 1999: Belle roll-in. June 1999: First event at Belle.

• Apr. 2001:

World record of the luminosity, 3.4 /nb/s.

• Oct. 2002:

World record of the integrated luminosity, 100 /fb. May 2003: Exceeded the design luminosity, 10 /nb/s.

• Feb. 2004:

Exceeded 12 /nb/s & 200 /fb.

• 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 …

KEKB = Asymmetric Double-Ring Collider for B-Physics

8 GeV Electron + 3.5 GeV Positron

Superconducting cavities (HER) e- e+ ARES copper cavities (LER) 8 GeV e- 3.5 GeV e+ Linac e+ target ARES copper cavities (HER) Belle detector

KEKB B-Factory

TRISTAN tunnel

• Mt. Tsukuba

Nikko KEKB Rings Belle Linac KEK Site

1034 cm-2s-1 600 /pb/day

Achieved >500 /fb in 6.5 years. (Initial Goal: 100 /fb in 3 years.)

The best 24 hours > 1.2 /fb

1034

We are here

54 /fb/mo 27 /fb/mo.

Next Milestone

Crab Cavity Beam Test

SuperKEKB, The Next Step

SuperKEKB

KEKB design 10 30 10 31 10 32 10 33 10 34 10 35 10 36 1 10 10

2

10

3

10 30 10 31 10 32 10 33 10 34 10 35 10 36 1 10 10

2

10

3

DAFNE ADONE BEPC CESR PEP-II KEKB LEP LEP-II TRISTAN PETRA DORIS SPEAR VEPP-2M VEPP-4M PEP ILC

CMS Energy (GeV) Luminosity (cm-2s-1)

Shutdown for upgrade

Data doubling time Integrated Luminosity

• SuperKEKB is a natural extension of KEKB, the world

leader in the luminosity frontier.

• 8 ×1035 cm-2s-1 will be available with technologies proven

at KEKB, together with a few modifications.

Crab cavities will be installed and tested with beam in 2006. The superconducting cavities will be upgraded to absorb more higher-order mode power up to 50 kW. The beam pipes and all vacuum components will be replaced with higher-current-proof design. The state-of-art ARES copper cavities will be upgraded with higher energy storage ratio to support higher current.

SuperKEKB

e+ 4.1 A e- 9.4 A β*y = σz = 3 mm

will reach 8 × 1035 cm-2s-1.

L = γ± 2er

e

1+ σ y

*

σ x

*

      I±ξ±y βy

*

RL Ry      

Three factors to determine luminosity:

L = γ± 2er

e

1+ σ y

*

σ x

*

      I±ξ±y βy

*

RL Ry      

Stored current: 1.36/1.75 A (KEKB) → 4.1/9.4 A (SuperKEKB) Beam-beam parameter: 0.059 (KEKB) → >0.24 (SuperKEKB) Vertical β at the IP: 6.5/5.9 mm (KEKB) → 3.0/3.0 mm (SuperKEKB)

Lorentz factor Classical electron radius Beam size ratio Geometrical reduction factors due to crossing angle and hour-glass efgect

Luminosity: 0.16 ×1035 cm-2s-1 (KEKB) 8×1035 cm-2s-1 (SuperKEKB)

New Parameter Set for 8×1035 -- by K. Ohmi

• Good parameters are not yet found with crab waist.

10

Why was higher luminosity made possible?

• 8 ×1035 cm-2s-1 is achievable with same beam currents,

beta, bunch length as 4 ×1035 cm-2s-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

εx=18nm, εy=0.09nm, βx=0.2m βy=3mm σz=3mm Lower coupling gives higher luminosity, but numerical instability occurs with less number of slices.

• K. Ohmi

5 slices 10 slices

Smaller emittances

2e+35 4e+35 6e+35 8e+35 1e+36 0.02 0.04 0.06 0.08 0.1 L ey (nm) 10 slice ex=9nm

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%.
• K. Ohmi

• Particles with z collide with central part of another
• beam. Hour glass effect still exists for each

particles with z.

• No big gain in Luminosity.
• Life time is improved.

εx=24 nm εy=0.18nm βx=0.2m βy=1mm σz=3mm

Traveling waist

• K. Ohmi

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!

crossing angle 30 mrad

Head-on(crab)

(Strong-strong simulation)

Crab crossing will boost the beam-beam parameter up to 0.19! Superconducting crab cavities are under development, and will be installed in KEKB in 2006.

• K. Ohmi
• K. Hosoyama, et al

(at the optimum tune)

Crab cavity He jacket

Input coupler was conditioned successfully.

• K. Hosoyama, et al

Cryostat & couplers

2006/3/21 2006 KEKB Review 20

• 1. Beam Duct with Ante-chambers

 Beam duct with two antechambers (2005)

 Model: for wiggler section

 OFC(t6), w224, h94, L4.7 m

 Fabrication methods:

 Forming (from plates)

 Manufacturing was successful.

 Degree of accuracy should be

improved in future

Forming Inside view Final check

2006/3/21 2006 KEKB Review 21

• 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 22

• 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 .

MO-type flange for bellows chamber MO-type flange for beam duct with antechambers for wiggler section SS flange Cu gasket Bellows chamber

2006/3/21 2006 KEKB Review 23

• 4. Movable Mask

 Features

 Ceramics support

 Little interference with beam

 Carbon head

 Little damage by beam

 With HOM absorber (SiC)

 Stealth type

 Has been studied since 2003

 R&D points (still preliminary)

 Trapped mode  Heating of head  Charge up  Experimental demonstration Ver.4 at present Beam duct Support (ceramics) Head (C) SiC Beam SiC

Positron Beam Chamber Sample Manipulator Electron Source Gate Valve Sample Manipulator Electron Monitor

LCとの連携（２）（加藤） In-situ Measurement System of Secondary Electron Yields at Positron Ring of the KEKB

★ 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

◆ PY2005 :

1.

designing and manufacturing of the system

2.

installation of a copper beam chamber in a straight section at the KEKB.

3.

a measurement system is being tested in a lab..

4.

the whole setup will be installed onto the chamber and the measurement will get started. ◆ PY2006 :

1.

a series of the experiments

2.

installation of a setup for short & long term exposure capability

3.

installation of a setup for gas puffing capability ( H2, CO etc )

4.

installation of a residual gas analyzer

<Features> <Achievement and Plan>

Loadlock Chamber

Construction of QCS R&D Magnet

(2-4) 12 Cured Coils and curing 6 layer coils all at once

(1) 12 cured double pan-cake coils. (2) Curing process of 6 layer coils. This process is necessary for improving the field quality in the

(1) (2)

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

High power RF R&D

Superconducting Cavity

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

• Even in single-bunch mode,

we observed a strong longitudinal instability at the ATF.

• In multi-bunch mode, we
• bserved 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. A prototype of the new bunch-by-bunch feedback system (G-board / Gproto) was tested at KEKB and

• ATF. The results were quite successful.

• C-band linac: completed a single section in the linac

with 4 structures.

• Performance was satisfactory with the beam.

C-Band Klystrons

Prototype C-band structure installed and tested at linac using actual beam (2003). Measured field gradient of 41 MV at 43 MW agrees with expectation.

Damping Ring

• Positron emittance needs to be damped, to pass reduced

aperture of C-Band section and to meet IR dynamic aperture restrictions.

– Electron DR may be considered later to reduce injection backgrounds in physics detector, but for now only positron DR considered.

• Damping ring located downstream of positron target,

before C-Band accelerating section.

e+ Damping Ring e+ production J-ARC B T e- gun

Oku-yen = 0.9 M$ Detector upgrade is not included.

How much do we need?

(International support may be necessary to make this project real.)

Conclusions

• A technically feasible design of SuperKEKB has been

made with 8 ×1035 cm-2s-1 luminosity.

• This is a natural extension of KEKB. Tunnel, ring lattice,

magnets, rf cavities and power sources are reused.

• Detailed R&D is going on for critical components.
• Ready for construction, once budget is approved.

33