Measurement of the Spin-Dependent Structure Functions of the Neutron and Proton (Development of Polarized Deuteron and Proton Targets)

本次研究项目的动机是先前的EMC实验，该实验揭示了核子内部夸克自旋的有趣之处。实验表明，夸克粒子对核子自旋几乎没有贡献。但是，根据基于SU(3)或SU(6)模型的常规理解，核子的SIPN取决于夸克的SIPN。Ellis-Jaffe在考虑颜色SU(3)和没有S夸克的贡献的情况下，预测了自旋相关结构函数对核子的积分。根据他们的预测，积分质子应该给出的值是0.189，而实验值是0.126。这种差异相当大。如果采用实验值来估计质子内部夸克自旋的总和，它几乎给出了。零分。在EMC结果发表后，人们提出了许多讨论，即(1)指出实验中的模糊性，(2)QCD破缺，(3)寻找核子自旋的其他来源，从而…还有更多。这就是所谓的“自旋危机”。为了平息这场争论，获得对自旋核子的真实看法，有必要积累更多关于质子和中子的实验数据。特别是对中子的实验是很重要的，因为从来没有测量过中子的自旋结构函数，而且质子和中子之间存在着明确的关系，即基于GCD的比约肯求和规则。这种被称为比约肯求和规则的关系可以用质子和中子的测量来检验。对于质子，需要更多的数据，误差小，x范围宽。本研究项目旨在解开核子自旋的谜团，这是高能强子物理中最令人兴奋的话题之一。这项实验已经在欧洲核子研究中心用100GeV的偏振µ子束和偏振氘靶进行了部分实验。在这个研究计划中，我们计划进行两种实验，分别用于氚靶和质子靶。我们的日本集团将主要为休偏振靶的制备和发展做出贡献。在散射实验中，我们将对目标操作负责。测量完成后，我们将对数据进行分析。较少

The motivation of the present research project is the previous EMC experiment which revealed the interesting of the quark spin inside nucleon. The experiment showed almost no contribution of the quark sipns to the nucleon spin. But, by out normal understanding based on the SU(3) or SU(6) madel, the sipn of the nucleon depends on those of quarks.Ellis-Jaffe had predicted the integral of the spin dependent structure function to the nucleon,taking the color SU(3) and no contribution of s-quark into consideration. By their prediction,the integral proton should give the value 0.189, but the experimental value 0.126. This discrepancy is fairly big. If one adopts the experimental value for the estimation of the whole sum of the quark spins inside the proton, it gives nearly. zero. After the publication of the EMC results, many discussions have been proposed, that is, (1) pointing out the ambiguity in experiment, (2) QCD break down, (3) looking for some other origins of the nucleon spin and so … More on. This topics is called " Spin Crisis".In order to settle the discussion and get the true view of the spin nucleon, it is necessary to accumulate more experimental data both for proton and neutron. Especially, the experiment for neutron is important, because the spinstructure function for the neutron has never been measured and there is a clear relation between proton and neutron called Bjorken sum rule based on the GCD. This relation called Bjorken sum rule can be checked the measurements for both proton and neutron. For the proton, more data with small errors and wide x region are requested.The present research project aims to make clear the puzzle of the nucleon spin which is one of the most exciting topics in high energy hadron physics. The experiment has been partly already achieved at CERN using 100 GeV polarized muon beam and polarized deuteron target.In This research program, two kinds of experiment for the experiment for the deuteron and proton targets are planned. Our Japanese group will contributes mainly to the praparation and development of the hugh polarized target. During the scattering experiment, we will have resposibility for the target operation. After the measurement, we will contribute the data analysis. Less