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Belle has accumulated 200 /fb !!
 
 

At 11:35 AM on Feb. 21, 2004, the total integrated luminosity recorded by the Belle detector surpassed 200 /fb. KEKB and Belle are setting a new world record for total integrated luminosity every day. Having reached a total of 100 /fb in October, 2002 after three years of data-taking, it took only one year and four months to accumulate the second 100 /fb. This new record was made possible by significant improvements in the performance of the KEKB accelerator.

One of the most important performance improvements made recently at KEKB is the adoption of a continuous injection scheme. Using this scheme, the Belle detector can continuously take data, even during beam injection, while the luminosity can be maintained close to its maximum value. Due to the success of this scheme, the daily luminosity collected by Belle increased by nearly 30%.


 

Figure 1 : KEKB operation status on Feb. 15 (the best day so far). The beam currents of HER (High Energy Ring) and LER (Low Energy Ring) were kept almost constant and as a result of this, the luminosity was maintained close to its maximum value (~1X1034/cm2/sec). Belle collected about 819 /pb (= 0.819 /fb) on this day.

 
 

Figure 2 : History of the total integrated luminosity of KEKB-Belle compared with that of PEP-II which is the rival machine working at SLAC in United States.

 

 

Figure 3 : Participants delighted at the achievement of 200 /fb (at the KEKB control room).
 
 
 
For more information :  KEKB  (http://www-acc.kek.jp/WWW-ACC-exp/KEKB/index.html)
 
 
Feb. 27. 2004    
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