The KEKB accelerator and the Belle detector group recorded a one-day integrated luminosity of over 1000 /pb (inverse pico-barn) on February 19. It is about 20% performance increase since February last year, when the combination of the accelerator and the detector had achieved the total integrated luminosity of 200/fb (inverse femto-barn).
 
Integrated luminosity is a measure of the capability of producing the particle collisions in a collider experiments. As the cross-section of the particle beam narrows down and as the intensity of the beam increases, luminosity improves. The integrated luminosity improves as the stability of the accelerator operation and the data collection capability of the detector etc, increases.
 
During the operation of the former TRISTAN accelerator from 1987 to 1995 by KEK, the total integrated luminosity by the VENUS detector was 400/pb. KEKB and Belle now collect roughly same amount of data in less than half a day.
 
The continuous beam injection has contributed most to the performance increase. It is the mode of accelerator operation during which the detector keeps taking data while the electron and positron beams are being fed from an injector. It was thought to be almost impossible due to the large noise generated by the injected beams. The accelerator group succeeded in developing fancy handling scheme of the beam injection and the detector group has developed a new electronics system with more robust noise tolerance, which led to the renewal of the record.
 
The KEKB accelerator was designed for the target luminosity of 1x10³⁴/cm²/s. This goal was achieved in May 2003, and the record has steadily been kept broken. On February 15, a new peak record, 1.516x10³⁴/cm²/s was obtained. The figure shows the luminosity increase since the start of the operation of the KEKB and Belle. From the top to bottom: the peak luminosity, integrated luminosity per day, stored currents, integrated luminosity since the start of operation of KEKB.