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Measurement of the scattering length of pions and the test of QCD

π介子散射长度的测量及QCD测试

基本信息

批准号：
11694099
负责人：
TAKEUTCHI Fujio
金额：
$ 3.84万
依托单位：
Kyoto Sangyo University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11694099/
关键词：
pionic atom App hadronic atom pion scattering length non-perturbative QCD chiral perturbation CERN PS experiment PS212 DIRAC experiment ハドロニック原子A_<2π>標準理論非摂動領域でのQCD π^+π^-相互作用シンチレーティングファイバーホトスコープ

项目摘要

The aim of this project is to measure directly the lifetime of π^-π^+ atoms bound by the Coulomb force, and deduce the scattering length of the s-wave interaction. We aim at measuring it with a precision of 5%, and test the QCD in the non-perturbative region by comparing it with a prediction based on the chiral perturbation theory.The proposal of the "DIRAC" experiment (PS212) was approved by CERN in 1996, and since, we started the construction of the spectrometer. In 1999, a serious data taking has started. Since then, we were successful in gradually increasing the extracted proton beam intensity by taking measures to reduce the background. Concerning the trigger that the Japanese group is responsible for, tuning of the Scifi hodoscope and the dE/dx counter, improvement of the read-out electronics and the integration circuit, improvement of the trigger circuit contributed greatly to the improvement of the experimental conditions. The data taking now continues smoothly, and the data taken in 1999 have been roughly analyzed. The analysis of the data taken in year 2000 is under way. In the preliminary result of the 1999 data, 266±79 atomic pairs with a loose cut, 160±45 with a tight cut, and 240 atomic pairs as a whole have been identified.Considering the proton beam intensity already ten times higher than in 1999, we should be able to deduce the scattering length with 5% precision within 2-3 years. Part of the result is already reported in conferences. We plan to publish the result of the 1999 data in May 2001, and that of 2000 in this autumn.

该项目的目的是直接测量受库仑力束缚的 π^-π^+ 原子的寿命，并推导出横波相互作用的散射长度。我们的目标是以5%的精度进行测量，并通过与基于手征微扰理论的预测进行比较来测试非微扰区域的QCD。“DIRAC”实验（PS212）的提议于1996年获得CERN批准，从此我们开始了光谱仪的建造。 1999 年，开始了认真的数据采集工作。此后，我们通过采取降低背景的措施，成功地逐步提高了提取的质子束强度。日本小组负责的触发方面，对Scifi视距仪和dE/dx计数器的调谐，读出电子器件和积分电路的改进，触发电路的改进对实验条件的改善做出了很大贡献。目前数据采集工作正在顺利进行，并对1999年采集的数据进行了粗略分析。对 2000 年采集的数据的分析正在进行中。 1999年数据的初步结果中，已识别出松切割的266±79个原子对，紧切割的160±45个原子对，总共240个原子对。考虑到质子束强度已经比1999年高出十倍，我们应该能够在2-3年内以5%的精度推算出散射长度。部分结果已在会议上报告。我们计划于2001年5月公布1999年的数据结果，并于今年秋天公布2000年的数据结果。