Intermediate Energy Nuclear Physics

法国萨克莱的同步加速器“星期六”可以加速高强度极化氘核，最高可达2.2 GeV。利用氘核的裂变反应，我们在E_n=1 GeV附近的中能区获得了高强度的单能极化中子。中子束强度为3 × 10^7 n/sec，能量分辨率约为40 MeV。利用这个极化中子，我们进行了p (n,p') X和^<12>C (n,p') X反应来寻找原子核中的δ激发。从我们在E_n>800 MeV的测试实验中发现，包纳质子能谱在δ激发区周围没有任何增强，但在^<12>C (n,pn) X的包纳质子能谱中可以观察到δ激发。发现介子产生过程提供了巨大的物理背景来掩盖该能量区域的δ激发和准弹性过程。因此，我们改变了我们的项目，通过测量排他性过程来测量光谱。我们合作建造了焦平面偏振仪Pomme，用于测量反应后质子或氘核的偏振，还合作建造了顶点室Arcole，专门用于检测反应。通过这次合作，我们在大阪大学核物理研究中心为我国焦平面偏振计的建设体验了许多新的探测器技术。在最后一年，我们测量了p (n, pp) π ^-和p (n, π ^- π ^+) d反应，只使用顶点室ARCOLE，它覆盖了反应可能相空间的90%。实验结束后，我们将全部原始数据压缩成8m /m的录像带带回日本。日本和法国目前正在进行数据分析。

The synchrotron Saturne at Saclay, France can accelerate high intensity polarized deuterons up to 2.2 GeV. By using the break-up reaction of deuterons in the nucleus, we obtain high intensity mono energetic polarized neutrons in the intermediate energy region around E_n=1 GeV. The neutron beam intensity is 3x10^7 n/sec and the energy resolution is about 40 MeV. Using this polarized neutron, we have performed p (n,p') X and ^<12>C (n,p') X reactions to search the delta-excitation in the nucleaus. From our test experiment at E_n>800 MeV the inclusive proton energy spectum is found not to give any enhancement around delta-excitaion region, but in the exclusive proton energy spectrum of ^<12>C (n,pn) X we can observe the delta-excitation. The pion production process is found to give the huge physical background to mask the delta-excitation and quasi-elastic process in this energy region. Thus we have changed our project to measure the spectrum by measuring the exclusive process. We have collabrated on the construction of the Focal Plane Polarimeter named Pomme to measure the polarization of protons or deuterons after the reaction, and on the construction of the he vertex chamber Arcole to detect the reaction exclusively. By this collaboration we have experienced many new detector techniques for the construction of the Focal Plane Polarimeter in our country at the Research Center for Nuclear Physics, Osaka University. In the final year we measured the p (n, pp) pi^- and p (n,pi^-pi^+) d reactions exclusively using the vertex chamber ARCOLE which covers about the 90 % of the possible phase space of the reaction. After the experiment we have condenced the whole raw data to 8 m/m video tape to bring back to Japan. The data analysis is now in progress both in Japan and in France.