He的敲出反应机制研究.PPT

6He的敲出反应机制研究 吕林辉 叶沿林等 北京大学实验核物理组 2010.07.26 内容提要 6He敲出反应研究意义 最近二十几年来晕核的结构与反应一直是原子核物理研究的热点。其中以 6He和11Li 为代表的 Borromean 核的少体结构及其少体之间的关联尤为引人关注。 6He 是最轻的双中子晕核（Jπ=0+; S1n=1.867MeV; S2n=0.973 MeV; T 1/2= 0.807 s；Rrms~2.5fm），基态大于90% 处于纯 (0p3/2)2 ，通常认为 6He 由一个稳定的 4He 核心和两个价中子组成，这两个价中子相对于核心的运动状态以及它们之间的关联是人们研究的重点。需要更多实验和理论的工作对其进行研究。 敲出反应是研究晕核中价核子的关联性质与行为的有效手段。但对于未知的核结构，存在一种不确定，即反应机制。6He 结构比较清楚，作为“bench-mark”是一个很好的研究对象。 来自很经典的RIB物理的书 Y. Suzuki, R.G.Lovas, K.Yabana, and K.Varga, Structure and Reaction of Light Exotic Nuclei (Taylor Francis, London,2003)。 From P.3： “virtually all information that we have on light exotic nuclei comes from reaction. In fact, the reliability of these information hinges very much on the reliability of the reaction model and analysis”. “Since the structure information on exotic nuclei is primarily obtained through reaction experiment using the secondary beam, the theory of reaction with exotic nuclei is of interest not only for its own sake, i.e., for studies of the reaction mechanism, but also as a framework to extract structure information reliably” Literature review RIPS@RIKEN 2009.07.26 - 08.05 6He Beam Beam intensity: ~2.3x105 pps Energy: 82.3 A MeV Δp/p=2.02% Target： （CH2)n , 0.0830 g/cm^2 C , 0.1339 g/cm^2 6He 实验装置6He beam RPIPS RIKEN Neutron wall 1 2 5 4 3 6 8 7 9 1 2 3 4 BDC2 BDC1 MDC FDC D12 D11 D2 Dipole Magnet target 靶前的粒子飞行径迹探测 靶后小角度的粒子鉴别 Drift Chamber 1 Drift Chamber 2 Beam on target 4He 6He x/mm y/mm x/mm x/mm x/mm x/mm y/mm x/mm y/mm y/mm Theta X/deg y/mm M DC F DC F DC 大角度带电粒子探测器的粒子鉴别图 6He 4He 3He deuteron Triton proton 6He beam With CH target 4He theta vs. Proton theta theta proton/degree theta 4he/degree phi 4He/degree phi proton/degree phi proton/degree phi 4He/degree With CH target 4He phi angle vs. Proton phi angle phi proton/degree phi 4He/degree With C target 4He phi ang