A test of QCD at low energy

低能QCD测试

• 批准号: 15340205
• 负责人: OKADA Kenji
• 金额: $ 4.35万
• 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: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15340205/
• 关键词: DIRAC Experiment; π^+π^-atom; QCD; Chiral perturbation; pion scattering length; πK atom; scintillating fiber hodoscope; topological trigger device; 実験核物理; S-波散乱長; ππ原子; ダイバーホドスコープ; ハドロニック原子; 中間子原子; PSPM; π^+π^-原子寿命; DIRAC experiment; pion

The DIRAC experiment (PS212) aims to measure the lifetime of π+π^- atoms using 24GeV proton beam provided by the CERN PS. The precise measurement of the lifetime enables to determine an s-wave pion-pion scattering length in a model independent way. The ππ scattering length has been calculated by means of Chiral perturbation theory with a precision of 5% at the starting stage of the DIRAC experiment. Now the precision of the calculation is better than 2.5%. The results are based on the assumption of a spontaneous chiral symmetry breaking due to a strong quark condensation. Therefore, a precise comparison of the theoretical value with the experimental one provides an opportunity to verify the current understanding of chiral symmetry breaking in QCD and to check the magnitude of the quark condensation.We analyzed 30% of the collected data and deduced the lifetime as τ = [2.91+0.49-0.62] X 10^<-15> s. This lifetime corresponds to the scattering length |a0・a2| = 0.264+0.033・0.020m_π^<-1>. The errors are mostly due to statistics.In this DIRAC experiment, Japan group has developed a topological trigger device consisting of scintillating-fiber hodoscopes(SFD), peak-sensing circuits(PSC), ADC/TDC hybrid read-out circuits(F1) and trigger logic circuits(TLC). They can select out online a real π^+π^- pair due to a dissociation of π^+π^- atom from a huge amount of background events. As the second stage of the DIRAC experiment we measure a lifetime of πK-atoms. For the πK measurements more than ten time intense beam than the π^+π^- measurement is required. We developed new high resolution scintillating fiber hodoscopes(HRH) consisting of 480 column made of 280μm fine fibers and 30 multi-anode photo multipliers with 16 channels. We found that the HRH has an excellent spatial resolution of 75μm and a time resolution of 0.56ns in rms.

狄拉克实验(PS212)的目的是利用欧洲核子研究中心提供的24GeV质子束测量π+π^-原子的寿命。寿命的精确测量使我们能够以一种与模型无关的方式确定S波的介子-介子散射长度。在狄拉克实验的初始阶段，用手征微扰理论计算了ππ散射长度，精度为5%。目前计算精度优于2.5%。这些结果是基于强夸克凝聚导致手征对称性自发破缺的假设。因此，将理论值与实验值进行精确的比较，为验证目前对QCD中手征对称性破缺的理解和检验夸克凝聚的量级提供了机会。我们分析了30%的收集数据，并推导出τ=[2.91+0.49-0.62]X10^&lt；-15&gt；S的寿命。这个寿命对应于散射长度|a0·a2|=0.264+0.033·0.020m_π^&lt；-1&gt；。在这次狄拉克实验中，日本团队开发了一种由闪烁光纤望远镜(SFD)、峰值检测电路(PSC)、ADC/TDC混合读出电路(F1)和触发逻辑电路(TLC)组成的拓扑触发装置。他们可以在线选择一个真正的π^+π^-对，因为π^+π^-原子从大量的背景事件中解离。作为狄拉克实验的第二阶段，我们测量了πK原子的寿命。对于πK的测量，需要比π^+π^-测量强十倍以上的束流。我们研制了一种新型高分辨率闪烁光纤显微镜，它由280μm细纤维制成的480柱和16个通道的30个多阳极光电倍增器组成。结果表明，该系统具有75μm的空间分辨率和0.56 ns的均方根时间分辨率。

项目成果

First measurement of the π^+π^- atom lifetime.

首次测量 π^+π^- 原子寿命。

• 发表时间: 2005
• 期刊: Physics Letters B 619
• 作者: A.Gorin et al.;A.Gorin et al.;A.Gorin et al.;B.Adeva et al.
• 通讯作者: B.Adeva et al.

High resolution scintillating-fibre hodoscope and its readout using peak-sensing algorithm.

高分辨率闪烁纤维视距镜及其使用峰值传感算法的读数。

• 发表时间: 2006
• 期刊: Nuclear Inst. and Meth. in Physics Research A 566
• 作者: A.Gorin et al.

Detection of π+π- atoms with the DIRAC spectrometer at CERN

使用 CERN 的 DIRAC 光谱仪检测 π+π- 原子

• DOI: 10.1088/0954-3899/30/12/012
• 发表时间: 2004
• 期刊: Journal of Physics G
• 作者: B. Adeva;L. Afanasyev;M. Benayoun;A. Benelli;Z. Berka;V. Brekhovskikh;G. Caragheorgheopol;T. Čechák;M. Chiba;S. Constantinescu;S. Costantini;C. Détraz;D. Dreossi;D. Drijard;A. Dudarev;I. Evangelou;M. Ferro;M. Gallas;J. Gerndt;R. Giacomich;P. Gianotti;D. Goldin;F. Gómez;A. Gorin;O. Gorchakov;C. Guaraldo;M. Hansroul;R. Hošek;M. Iliescu;N. Kalinina;V. Karpukhin;J. Klusoň;M. Kobayashi;P. Kokkas;V. Komarov;V. Kruglov;L. Kruglova;A. Kulikov;A. Kuptsov;I. Kurochkin;K. Kuroda;A. Lamberto;A. Lanaro;V. Lapshin;R. Lednický;P. Leruste;P. Sandri;A. L. Aguera;V. Lucherini;T. Maki;N. Manthos;I. Manuilov;L. Montanet;J. Narjoux;L. Nemenov;M. Nikitin;T. Pardo;K. Okada;V. Olchevskii;A. Pazos;M. Pentia;A. Penzo;J. Perreau;C. Petrascu;M. Pló;T. Ponta;G. Rappazzo;A. Fernandez;A. Romero;A. Ryazantsev;V. Rykalin;C. Santamarina;J. Saborido;J. Schacher;C. Schuetz;A. Sidorov;J. Smolík;F. Takeutchi;A. Tarasov;L. Tauscher;M. Tobar;S. Trusov;V. Utkin;O. Doce;P. Vázquez;S. Vlachos;V. Yazkov;Y. Yoshimura;M. Zhabitsky;P. Zrelov
• 通讯作者: P. Zrelov

DIRAC : A High Resolution spectrometer for Pionium

DIRAC：高分辨率锍光谱仪

• 发表时间: 2003
• 期刊: Nuclear Inst. and Meth. in Physics Research A 515
• 作者: A.Gorin et al.;A.Gorin et al.;A.Gorin et al.;B.Adeva et al.;B.Adeva et al.;B.Adeva et al.;B.Adeva et al.;B.Adeva;B.Adeva et al.
• 通讯作者: B.Adeva et al.

DIRAC collaboration: "DIRAC : A High Resolution Spectrometer for Pionium Detection"Nuclear Instruments and Methods in Physics Research A. A515. 467-496 (2003)

DIRAC 合作：“DIRAC：用于钍检测的高分辨率光谱仪”物理研究中的核仪器和方法 A. A515。