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Chehab, R.

Paper Title Page
THPMN030 Enhancement of the Positron Intensity by a Tungsten Single Crystal Target at the KEKB Injector Linac 2778
  • T. Suwada, K. Furukawa, T. Kamitani, H. Okuno, M. Satoh, T. Sugimura, K. Umemori
    KEK, Ibaraki
  • R. Chehab
    IN2P3 IPNL, Villeurbanne
  • R. Hamatsu, T. Haruna, T. Sumiyoshi
    TMU, Hatioji-shi, Tokyo
  • A. Potylitsyn
    INPR, Tomsk
  • I. S. Tropin
    TPU, Tomsk
  • K. Yoshida
    SAGA, Tosu
  Funding: This work was supported by the Grant-in-Aid of Ministry of Education, Culture, Sports, Science and Technology of Japan and by the grant of Ministry of Education and Science of the Russian Federation.

A new tungsten single-crystalline positron target has been successfully employed for generation of the intense positron beam at the KEKB injector linac in September 2006. The target is composed of a tungsten single-crystal with a thickness of 10.5 mm. The positron production target is bombarded at an incident electron energy of 4 GeV, and the produced positrons are collected and accelerated up to the final injection energy of 3.5 GeV in the succeeding sections. A conventional tungsten plate with a thickness of 14 mm has been used previously, and the conversion efficiency (Ne+/Ne-), the ratio between the number of positrons (Ne+) captured in the positron capture section and the number of the incident electrons (Ne-), was 0.20 on average. By replacing the tungsten plate with the tungsten crystal, it increased to 0.25 on average. The increase of the conversion efficiency has boosted the positron intensity to its maximum since the beginning of KEKB operation in 1999. Now this new positron source is stably operating and is contributing to increasing the integrated luminosity of the KEKB B-factory.