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Study of Spin Structure of the Proton and Nectron with Hadror Coincidence Method

哈德罗符合法研究质子和中子的自旋结构

基本信息

批准号：
09304030
负责人：
SHIBATA Toshi-aki
金额：
$ 13.7万
依托单位：
TOKYO INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

In this project we have done 1) the experimental data analysis and 2) detector development at Tokyo Institute of Technology. The thema oa the project was the study of the quark-gluon structure of the spin of proton and neutron. The spin of the nucleon is 1/2. It was found by EMC in 1988 that only a small part of the nucleon spin is carried by quarks. We are participating in HERMES experiment at DESY in Hamburg in Germany. At HERMES the high energy polarized electron beam is scattered off the polarized nucleon target. The experimental data are sent from HERMES to our university. This experiment is a deep inelastic scattering. We mea sured not only the scattered electron but also produced hadrons (mesons, nucleons, lambda etc.) in coincidence. For that purpose we developped a Ring Imag ing CHerenkov counter (RICH) and installed into HERMES.Pions, kaons, protons and anti-protons at 2-20Gev/c are identified with the RICH.Polarized u, d, and s quark distributions in the nucleon are determined.Furthremore, transversity of the quark spin was studied for the first time. This is a study of the distribution of the quark whose spin is perpendicular to the nucleon spin. At HERMES the angle between the electron scattering plane and the pion production direction was measured by reversing the target nucleon spin direction. We succeeded to observe a non-zero asymmetry. 'Transversity' of the quark spin is a new field and will attract many physicists in the near future to study it further.

在这个项目中，我们在东京工业大学完成了1）实验数据分析和2）探测器开发。该项目的主题是研究质子和中子自旋的夸克-胶子结构。核子的自旋是1/2。EMC在1988年发现，只有一小部分核子自旋是由夸克携带的。我们正在参加德国汉堡DESY的爱马仕实验。在爱马仕实验中，高能极化电子束被极化核子靶散射。实验数据从爱马仕发送到我们大学。这个实验是一个深度非弹性散射。我们不仅测量了散射电子，而且测量了强子（介子、核子、λ等）的产生。巧合。为此，我们研制了一个环形成像的切伦科夫计数器（RICH），并安装在爱马仕中，用它鉴别了2- 20 Gev/c的π介子、K介子、质子和反质子，测量了核子中极化的u、d、s夸克分布，并首次研究了夸克自旋的横变性。这是对自旋垂直于核子自旋的夸克分布的研究。在爱马仕，电子散射面和π介子产生方向之间的角度是通过反转靶核子的自旋方向来测量的。我们成功地观察到了非零不对称性。夸克自旋的“横向性”是一个新的领域，在不久的将来将吸引许多物理学家对其进行进一步的研究。