Study on the Quark-Gluon Structure of Hadrons

为了研究核子的自旋结构和强子的夸克-胶子结构，我们正在准备欧洲核子研究中心的COMPASS（COmmon μ on Proton Apparatus for Structure and Spectroscopy）国际合作项目的实验。COMPASS项目的主要实验之一是通过测量极化介子在极化核子上的深非弹性散射中开放粲数产生的截面不对称性来获得核子中的胶子极化。在本次COMPASS合作中，我们负责开发和构建具有180 nirad大开口立体角的新型极化氢靶系统和光束跟踪探测器系统，以精确确定极化靶上游和下游入射μ子的位置。为了测量胶子偏振，必须在4 * 4 cm^22…More的探测区域内以小于0.5 mm的空间分辨率确定μ子的轨迹，且μ子的入射速度大于10^8 μ子/秒。即使在计数率极高的情况下，闪烁光纤跟踪探测器也具有良好的时间和空间分辨率，可以满足这些要求。在本研究项目中，我们研究了用于COMPASS实验的塑料闪烁光纤跟踪探测器系统与位置敏感光倍增器相结合。利用塑料闪烁光纤与多阳极型位敏光倍增器（HAMAMATSU: H6568）连接，构建了一个原型跟踪探测器系统，并在KIEK用450 MeV/c电子和CERN用3.6 GeVk质子和介子测试了系统的特性。测量结果表明，当光束强度为3.6 × 10^7 p/ 110mm ^2时，得到了680 psec的时间分辨率，可用于COMPASS实验。因此，我们在本项目中构建了基于该类型的波束跟踪系统，并于2000年开始进行COMPASS实验。少

We are now preparing the experiment of the COMPASS(COmmon Muon Proton Apparatus for Structure and Spectroscopy) international collaboration program at CERN in order to investigate the spin structure of the nucleon as well as the quark-gluon structure of hadrons. One of the main experiments of the COMPASS program is to obtain the gluon polarization in the nucleon from the measurement of the cross-section asymmetry for the open charm production in the deep inelastic scattering of polarized muons on polarized nucleons.In this COMPASS collaboration, we are responsible for developing and constructing the new polarized hydrogen target system with a large opening solid angles of 180 nirad and the beam tracker detector system to determine the positions of incident muons precisely at the upstream and the downstream of the polarized target. To measure the gluon polarization, the tracks of muons must be determined in the spatial resolution of less than 0.5 mm in the detection area of 4 * 4 cm^22 … More under more than 10^8 incident muons per second. The scintillation fiber tracking detectors are considered to be applicable for these requirements from the good time and spatial resolution even in the extremely high counting rate condition.In the present research project we have investigated the plastic scintillation fiber tracking detector system combined with position-sensitive photo-multipliers to be used in the COMPASS experiment. A prototype tracking detector system was constructed by using plastic scintillation fibers connected to multi-anode type position-sensitive photo-multipliers(HAMAMATSU : H6568)and tested the characteristics with 450 MeV/c electrons at KIEK and 3.6 GeVk protons and pions at CERN.From the measurement, the time resolution of 680 psec was obtained for the beam intensity of 3.6*10^7 p/spill 110 mm^2, which is applicable for the use in the COMPASS experiment. Therefore, we have constructed the beam tracker system based on this type in this project for the start of the COMPASS experiment in 2000. Less