Studies of Few-Body Nuclei with Tagged Photons at MAX-lab (Open call for Nuclear Physics Travel requests)

该项目为在瑞典隆德max实验室的标记光子设施进行实验计划的旅行寻求资金。实验将使用高能光子（高能X射线）来探测3He和4He原子核的结构。它们还将提供构成这些原子核的质子和中子的结构信息。质子和中子本身是由基本夸克和胶子组成的，它们通过量子色动力学（QCD）描述的强作用力相互作用。这些测量，结合了在少体结构理论中新的“手性有效场理论”的发展，将提供核性质和量子cd描述的基本色力之间的定量联系。测量将基于He气体闪烁体主动目标技术。在气体中相互作用引起电离的粒子产生闪烁，发出探测到高能光子将目标核（He）分解成两个或更多碎片的信号。该靶设计用于检测核碎片的效率很高，但用于检测光子束与靶材料原子相互作用产生的电子的效率很低。因此，目标有效地抑制了背景过程，否则会模糊感兴趣的信号。2009年3月，全新的主动靶将完成调试，之后将开始“全面生产”He光分解特性的测量。我们计划在2009年6月和2009年9 - 10月使用标记光子束周期。2009年下半年核物理运行的最终时间表将在6月之后确定。

This project seeks funding for travel to carry of programme of experiments at the Tagged-Photon facility of MAX-lab in Lund Sweden. Experiments will use energetic photons (high-energy X rays) to probe the structure of 3He and 4He atomic nuclei. They will also provide structure information on the protons and neutrons, which make up these nuclei. The protons and neutrons themselves are composites of elementary quarks and gluons which interact via the strong force, described by Quantum Chromo Dynamics (QCD). The measurements, allied to new 'chiral effective field theory' developments in few-body structure theory, will provide a quantitative link between nuclear properties and the fundamental colour force, described by QCD. The measurements will be based on He gas scintillator active target technology. Particles which interact in the gas to cause ionisation produce scintillations, signalling detection of an event where an energetic photon disintegrates a target nucleus (He) into two or more fragments. The target is designed to be highly efficient for detecting nuclear fragments but highly inefficient for detecting electrons produced by atomic interactions of the photon beam with target material. Thus the target effectively suppresses background processes which otherwise would obscure the signals of interest. Commissioning of the completely new active target will be completed in March 2009, after which 'full production' measurements of He photo disintegration characteristics can start. We plan to use tagged-photon beam periods in June 2009 and also in September-October of 2009. Final scheduling for nuclear physics operations in the second half of 2009 will take place after June.