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Student Number 89222024
Author Shin-Chuan Kao(高世權)
Author's Email Address No Public.
Statistics This thesis had been viewed 1609 times. Download 942 times.
Department Physics
Year 2001
Semester 2
Degree Master
Type of Document Master's Thesis
Language zh-TW.Big5 Chinese
Title Proton antiproton production via two photon collisions
Date of Defense 2002-06-12
Page Count 70
Keyword
  • anti-proton
  • baryon pair production
  • pQCD
  • proton
  • QCD
  • two photon
  • Abstract   The cross-section of the gamma gamma->p-pbar reaction , integrated over a c.m. angular region of | cosθ* | < 0.7, is measured at two photon c.m. energy (Wγγ) between 2.0 and 4.0 GeV, . The results are obtained by using  events selected from an integrated luminosity of 32.6 fb-1 of the data taken by the BELLE detector.
      With the help of Monte-Carlo simulation and the application of likelihood method , a powerful proton identification method is developed. After applying the proton identification , the background events are rejected and their effect can be neglected. In addition , the amount of data is twenty times larger than that of CLEO and VENUS , It can thus give better statistics for baryon pair production , in particular at low Wγγ(< 2.2 GeV) and high Wγγ( > 2.8 Gev ) region.
    The measured cross-section at Wγγ > 2.5 GeV region is dominated by W-12 term based on the conventional pQCD prediction. The prediction at Wγγ < 2.5 GeV by a newer model , the QCD sum rule , is in agreement with the result of BELLE experiment.
    Table of Content 第一章簡介
    1.1 正負電子對撞中的雙光子反應............. 1
    1.2 雙光子反應中的重子對生成................ 3
    第二章理論計算
    2.1 雙光子動力學................... 5
    2.2 截面積的計算................... 7
    第三章KEK 和BELLE 探測器
    3.1 KEK 加速器簡介.................. 9
    3.2 矽頂點探測器.................. 10
    3.3 中央漂移室................... 12
    3.4 Aerogl Cherenkov 計數器............ 12
    3.5 飛時計數器................... 14
    3.5 電磁量能器................... 14
    第四章帶電粒子的辨認方法
    4.1 Monte Carlo 模擬................ 16
    4.2 帶電粒子的能量損失............... 17
    4.3 帶電粒子的飛行時間............... 20
    4.4 Cherenkov 輻射................. 23
    4.5 能量與動量的比值................ 25
    第五章數據分析
    5.1 事件的選擇................... 29
    5.2 質子反質子對的挑選............... 32
    5.3 背景事件的分析................. 35
    5.4 碰撞原點時間誤判的修正............. 37
    5.5 探測器的效率分析................ 47
    5.6 結果分析.................... 51
    5.7 結論...................... 60
    參考文獻...................... 70
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    10. BELLE Collab.,NIM A479 (2002) 117-232.
    11. Fernand M.Renard ,Basics of Electron Positron
      Collisions.
    12. John David Jackson, Classical Electrondynamics.
    Advisor
  • Augustine E. Chen(陳鎰鋒)
  • Files
  • 89222024.pdf
  • approve immediately
    Date of Submission 2002-07-10

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