Study of a few-nucleon system using electron scattering (relativistic effects, meson exchange effects, contributions of quarks)

1. 我们完成了东北大学^<40>Ca（e, e'p）实验的研究，并将其与前人研究的^<12 >c和^<16>0的结果进行了比较。实验得到的截面几乎是用相对论DWIA计算得到的所有目标的理论截面的一半。这一结果表明，在计算中遗漏了一些重要的成分。介子交换电流对12C的贡献最大，对重核的贡献较小。在麻省理工学院贝茨分校进行的四动量传递Q^2 = 0.33 (GeV/c)^2的虚拟光子康普顿散射实验中，质子的极化率与用低能展开法和色散关系法分析的值有很大的不同。这种差异在更高的动量转移中是看不到的。利用色散理论在MIT-Bates和JLab得到的偶极子参数是一致的，但与mainz得到的值有很大的不同。我们分析了在JLab进行的^3He（e, e'p）实验的数据，并将结果发表在《物理评论快报》上。我们将^3He中质子的动量分布与各种波函数的计算结果进行了比较，发现在1 GeV/c附近没有与实验结果一致的计算结果。这表明核子的描述需要核子以外的自由度。我们制作了一个Lamb-shift型偏振计，并对其性能进行了测试。用偏振光计直接测量了氘核的三个磁性亚能级的分数。我们在京都大学的电子存储环中使用自约束离子靶进行了电子散射的测试实验。该靶利用电子束诱导的静电场捕获正离子。利用分析系统监测捕获离子的状态，观察提取离子的电荷态分布。我们已经证实Cs离子确实被困在了目标中。我们还利用安装在目标区域的导线靶来评估散射电子探测系统的性能。少

1. We have completed the study of ^<40>Ca(e, e'p) experiment made at Tohoku University, and compared it with previously studied results of ^<12>C and ^<16>0. The experimentally-obtained cross sections were almost half of theoretically obtained ones using relativistic DWIA calculations for all targets. This result suggests that some important ingredients are missing in the calculation. The contribution of the meson exchange currents is largest for 12C, and becomes smaller for heavier nuclei.2. Polarizabilities of the proton obtained from an experiment of virtual-photon Compton scattering made at a four-momentum transfer of Q^2 = 0.33 (GeV/c)^2 at MIT-Bates are much different from each other between the values that were analyzed using the low energy expansion and using dispersion relation. Such a discrepancy is not seen at higher momentum-transfers. The dipole parameters obtained at MIT-Bates and at JLab using the dispersion theory are consistent each other, but different very much from … More the value obtained at Mainz.3. We have analyzed data of the ^3He(e, e'p) experiment made at JLab, and published the result on Physical Review Letters. We compared the momentum distribution of protons in ^3He with calculations using various wave functions, and found no calculations agree with the experimental result near 1 GeV/c. It suggests that degrees of freedom beyond nucleons are needed for description of nuclei.4. We have fabricated a Lamb-shift type polarimeter and tested its performance. The fraction of three magnetic sub-levels of the deuteron was directly measured using the polarimeter.5. We have performed test experiments of electron scattering using a self-confining ion target in an electron storage ring at Kyoto University. This target traps positive atomic ions using electrostatic field induced by an electron beam. The condition of trapped ions was monitored by an analyzer system, which observed charge-state distribution of extracted ions. We have confirmed Cs ions were actually trapped in the target. We also evaluated the performance of the scattered-electron detection system using wire targets installed in the target region. Less