The Investigation of the Nucleon Spin Structure and the Development of Polarized Targets

核子自旋结构的研究和极化靶的发展

• 批准号: 07102008
• 负责人: HORIKAWA Naoaki
• 金额: $ 179.84万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Specially Promoted Research
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07102008/
• 关键词: spin; nucleon spin structure; COMPASS; polarized target; quark spin; gluon spin; QCD; muon beam; SMC; クォークスピン; グルーオンスピ; グル-オンスピン; 偏極ガンマー線; GDH; 核子スピン; スピン偏極標的; 超電動電磁石; DHG和則; ハドロン生成; 超伝導電磁石

The nulceon spin structure is one of the most interesting and important problems in high energy physics. By getting support of Grant-in-Aid(Specially Promoted Research), we performed three kinds of research in five years.The first subject is the research on the quark and gluon spin contributions to the nucleon one. In order to make clear the role of quarks, we performed SMC experiment in 1995 and 1996, using polarized deuteron (deuterated butanol) and polarized proton (solid ammonia) targets. By these experiments, the quark spin contribution to the nucleon spin has been determined as 20%〜30%. The Bjorken sum rule which is thought to beheld is successfully tested. This assured the validity of OPE (Operator Production Expansion) method to the quark-gluon problems in the frame of QCD. The sizable negative spin contribution by s-quark has been again confirmed. Based on those conclusions, the spin contribution of gluon has been an important subject. Our present Grant-in-Aid has stimulated t … More he international collaboration to investigate the role of gluon spin, by proposing the construction of the superconductive magnet, for the polarized target. The magnet has such characteristics as, (i) the maximum field strength of 2.7T with a homogeneity over 3cm in diameter and 130cm inlength, (ii) the dipole coil to produce 0.6T perpendicular to the solenoid field, (iii) the exit aperture of ± 180 mrad. The magnet is now underconstruction and will be transported to CERN from Oxford Co. LTD soon.The next contribution is the construction of the scintillating fiber beam-tracker detectors which are mounted before and behind the polarized target. This tracker system determined the incoming and outgoing muon in good time and space resolutions. The scintillating fiber has a diameter of 0.5mm. The prototype tracker gave enough time resolution (σ〜300 PS) for the real muon beam. Now, the construction of the tracker for the real experiment is going on.One more contribution of Japan group is the construction of the off-line analysis program. This job must be prepared before real experiments. Two Japanese members contribute to write programs for data base, histgram display and so on.Second subject is the research on the test of GDH (Gerasimov, Drell-Hearn) sum rule. This sum rule relates the anomalous magnetic moment to the polarized photon-polarized nucleon reaction cross section. To perform the test of this sum rule, the experiment has to be extended up to the infinite energy. But, the sum rule includes the factor 1/ν (ν : photon energy), the higher energy part is thought to be negligible. So, one should make experiment up to several GeV. As the first experiment in the world, we performed the experiment at Mainz in 1998. The data was taken in the energy range of 200-800 MeV. The data are now being analyzed. To achieve the higher energy region, we are preparing the experiments in Bonn Univ. (up to 2.5 GeV) and in SPring-8 (up to 3 GeV).Third subject is the development of the polarized target. The study at CERN developed the target for higher polarization, delivation of exact polarization value to spin-1 system. In Nagoya, we tried to polarize the polymer material like polyethylene. This material has a merit to be handled in room temperature. This helps to form very thin target material. We polarized deuterated polyethylene ({CDィイD22ィエD2}n) which is prepared by two methods, i.e. free electron doping method and irradiation one by electron beam. We confirmed the highest polarization P=16.7% to the irradiated d-polyethylene. Less

核子自旋结构是高能物理中最有趣和最重要的问题之一。在获得特惠研究资助的支持下，我们在五年内进行了三种研究。第一个课题是研究夸克和胶子自旋对核子自旋的贡献。为了明确夸克的作用，我们在1995年和1996年分别用极化氘核（氘化丁醇）和极化质子（固体氨）为靶进行了SMC实验。通过这些实验，确定了夸克自旋对核子自旋的贡献为20% ~ 30%。被认为是正确的比约肯和规则被成功地验证了。这保证了算子产生展开方法在QCD框架下求解夸克-胶子问题的有效性。s-夸克相当大的负自旋贡献再次得到证实。基于这些结论，胶子的自旋贡献一直是一个重要的课题。我们目前的资助刺激了更多的国际合作来研究胶子自旋的作用，通过提出超导磁体的结构，极化目标。该磁体具有以下特点：(1)最大场强2.7T，均匀度在直径3cm，长度130cm以上；(2)偶极线圈垂直于电磁场产生0.6T;(3)出口孔径±180mrad。该磁体目前正在建设中，很快将从牛津有限公司运送到欧洲核子研究中心。下一个贡献是安装在极化目标前后的闪烁光纤波束跟踪探测器的构造。该跟踪系统以良好的时间和空间分辨率确定了进出的μ子。闪烁光纤的直径为0.5mm。原型跟踪器对实际的μ介子光束具有足够的时间分辨率（σ ~ 300 PS）。现在，为真正的实验建造追踪器的工作正在进行中。日本组的另一个贡献是离线分析程序的构建。这项工作必须在真正的实验之前做好准备。两名日本成员负责编写数据库、直方图显示等程序。第二个课题是GDH （Gerasimov, Drell-Hearn）和规则检验的研究。该求和规则将反常磁矩与极化光子-极化核子反应截面联系起来。为了验证这个求和规则，实验必须扩展到无限能量。但是，求和规则包括因子1/ν （ν：光子能量），高能部分被认为是可以忽略不计的。所以，我们应该做几个GeV的实验。作为世界上第一个实验，我们于1998年在美因茨进行了这个实验。数据采集在200-800 MeV的能量范围内。目前正在分析这些数据。为了实现更高的能量区域，我们正在准备在波恩大学（高达2.5 GeV）和SPring-8（高达3 GeV）的实验。第三个课题是极化靶的发展。欧洲核子研究中心的研究发展了更高极化的目标，为自旋-1系统提供精确的极化值。在名古屋，我们尝试将聚乙烯等高分子材料极化。这种材料的优点是可以在室温下处理。这有助于形成非常薄的靶材料。对采用自由电子掺杂法和电子束辐照法制备的氘化聚乙烯（{CD γ γ γ D22 γ γ γ D2}n）进行了极化。我们证实了辐照d-聚乙烯的最高极化P=16.7%。少

项目成果

堀川直顕,C.Bradke,他: "A New Frozen-Spin Target for 4π Particle Detection"Ncul. Instrum. Methods. A436. 430-442 (1999)

Naoaki Horikawa，C. Bradke 等人：“用于 4π 粒子检测的新冷冻旋转目标”Ncul A430-442 (1999)。

堀川直顕、他SMCメンバー: "Spin Asymmetries A_1 and Structure Functions g_1 of the Proton and the Deuteron from Polarized High Energy Muon Scattering" Phys.Rev.D58. 112001 (1998)

Naoaki Horikawa 和其他 SMC 成员：“来自偏振高能 μ 子散射的质子和氘核的自旋不对称 A_1 和结构函数 g_1”Phys.Rev.D58 (1998)。

堀川直顕、他SMCメンバー: "Measurement of Proton and Nitrogen Polarization in Ammonia and a Test of Equal Spin Temperature" Nucl.Instr.and Methods in Physics Research. A419. 60-82 (1998)

Naoaki Horikawa 和其他 SMC 成员：“氨中质子和氮极化的测量以及等自旋温度的测试”Nucl.Instr.and 物理研究方法 60-82 (1998)。

堀川直顕,堀川壮介,他: "Time Resolution of a Scintillating Fiber Detector"Ncul. Instrum. and Methods in Phys. Research. A431. 177-184 (1999)

Naoaki Horikawa、Sosuke Horikawa 等人：“闪烁光纤探测器的时间分辨率”Ncul。物理研究方法，177-184。

堀川直顕、他SMCメンバー: "A Line Shape Analysis for Spin-1 NMR Signals" Nucl.Instr.and Methods in Physical Research. A398. 109-125 (1997)

Naoaki Horikawa 和其他 SMC 成员：“Spin-1 NMR 信号的线形分析”Nucl.Instr.and 物理研究方法 109-125 (1997)。