| Press Release:June 20, 2001 |
|
In the run 2001 through June 25, KEKB has marked the following records
of the luminosity:
|
Peak Luminosity: |
4.10 /nb/s (= 1033/cm2/s) |
|
Integrated Luminosity/day: |
224 /pb |
|
Integrated Luminosity/7 days: |
1.48 /fbV |
|
Integrated Luminosity/month: |
4.70 /fb |
The numbers above are all recorded values by the Belle detector. All these
numbers shows the highest luminosity in the history of colliders. Belle's
integrated luminosity has also reached 30.3 /fb on June 25.
KEKB's luminosity has been nearly doubled in this year as shown in the figure. It was brought by several improvements on the machine:
| 1) |
New additional solenoid windings in LER. About 500 m of solenoid was wound
around the bellows chambers in January. Up to now 1,300 m out of 1,800
m of the field-free region of the LER arc has been covered by the solenoid field. It suppresses the vertical blowup of the LER beam due to
the photo-electron cloud up to about 950 mA. |
| 2) |
Replacement of the HER movable masks. The new moving-chamber movable masks
(Ver. 4), which have been already verified at LER last year, removed the
limitation of the stored current at HER in April. After the replacement,
the HER current was raised from 580 mA to 770 mA. |
| 3) |
New betatron tunes. The vertical tunes was raised over the half-integer
resonance lines in both rings to obtain a stabilities of the orbit as well
as wider high-luminosity areas in the tune spaces. The horizontal tunes, especially in LER, were set even close to the half-integer
resonance (0.52 to 0.51 or 0.505), to gain the dynamic focusing effect
of the beam-beam interaction without sacrificing the machine aperture. The distance from the resonance line would be the state
of art. |
| 4) |
Many efforts to stabilize the machine. Progresses were made in the orbit
control, betatron tune monitor & control, beam size control, beam abort
systems, logging systems, and the injectors, etc. |
| Message of the Director General of KEK (to HEP Laboratories) |
Dear Colleagues,
I am pleased to report that the KEK asymmetric energy B factory (KEKB)
and the Belle detector have achieved recently an operating luminosity that
is above 4x1033/cm2/s. We believe that this is the highest luminosity ever realized in a colliding
beam facility.
Although this is still below the design luminosity of 1034/cm2/s it is an important milestone for the project and confirms many of the
design choices.
| Hirotaka Sugawara |
|
| Director General, KEK |
|
|
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