The Effect of strange Quark Spin and Higher Twist to QCD

我们小组今年在CERN上实现了质子自旋相关结构函数g_1(Chi)的测量。这一测量是由g^P_(chi，q^2)在chi=0.02以下的小chi区的行为引起的。在1993年的上一次测量中，它表现出随着CHI的减小而增加的趋势。从4月20日到9月17日进行了测量。日本成员不仅在偏振靶操作和偏振分析领域做出了贡献，而且在维护MWPC和光谱仪的数据采集方面也做出了贡献。(1)Muon束流和强度分别为190GeV和4.5×10^7ppp。光束的重复率为14.4秒。(2)极化靶材为固体氨(NH_3)，平均极化约90%。以NH_3为靶材，可获得比正丁醇靶高20-30%的散射数据。目前正在对获得的数据进行分析。S Miya…先生这项工作涉及了更多的池和小川，将目前的数据与1993年获得的数据相结合，可以得到更可靠的g^P_(chi，Q^2)值。这使得给出夸克自旋对核子自旋贡献的决定性结论成为可能，并更精确地检验Bjorken求和规则和Ellis-Jaffe求和规则。在获得数据的同时，我们的小组成员进行了1995年氚靶实验的数据分析。尤其是小川先生在SMC集团担任了分析的关键人物。通过对探测器位置、假不对称性、辐射修正、不对称参数A^d_和g^d_(chi，q^2)的QCD演化等多种检验，他推导出了1995年的氚数据的最终g^d_(chi，q^2)值。他总结了1995年的氚实验，并在1996年9月4-10日在阿姆斯特丹举行的高能自旋物理国际研讨会上作了报告。他将此总结为博士论文，并于1997年1月向名古屋大学物理系提出。他于1997年3月获得博士学位。岩田博士与JINR(Dubna)的人讨论了新的极化靶材料的可能性，并在Dubna进行了利用Dubna的极化氢束研究原子核中夸克结构的极化实验。较少

Our group has achieved this year the measurement of the spin-dependent structure function g_1 (chi) of the proton at CERN.This measurement was motivated by the behavior of g^P_ (chi, Q^2) in the small chi region below chi=0.02. In the previous measurement in 1993, it showed the tendency to increase with smaller chi. The measurement has been done from April 20 to September 17. Japanese members contributed not only in the field of polarized target operation and polarization analysis, but also in the maintenance of the MWPCs and the data acquisition by the spectrometer.The experimental conditions were following. (1) The muon beam and intensity were 190GeV and 4.5*10^7 ppp, respectively. The repitition rate of the beam was 14.4sec.. (2) The polarized target material was solid ammonia (NH_3) with a polarization of about 90% in average. By adopting NH_3 as target material, we could obtain scattering data 20-30% more than the butanol target. The acquired data are now under analysis. Mr.s Miya … More chi and Ogawa are involved in this job.By adding the present data to those obtained in 1993, we can get more reliable values of g^P_ (chi, Q^2) in the lower chi region. It makes possible to give the decisive conclusion on the quark spin contribution to nucleon spin and to test the Bjorken sum rule and Ellis-Jaffe sum rule more precisely.In parallel with the data acquisition, our group members progressed the data analysis for the 1995 deuteron target experiment. Especially, Mr.Ogawa worked as a key person of the analysis in SMC group. By making many kinds of checks, like detector position, false asymmetry, radiative corrections, QCD evolutions to the asymmetry parameter A^d_ and g^d_ (chi, Q^2), etc., he deduced the final g^d_ (chi, Q^2) valuse to 1995 deuteron data. He has summarized the 1995 experiment for the deuteron and reported at the International Symposium on High Energy Spin Physics held in Amsterdam on Sep. 4-10,1996. He has summarized this to Doctor Thesis and proposed to Department of physics, Nagoya University in January, 1997. He was given The Ph.D in March, 1997.Dr.Iwata discussed with JINR (DUBNA) people on the possibility of the new polarized target material and the polarization experiment at DUBNA to investigate the quark structure in nucleus, using the polarized deuteron beam at DUBNA. Less