分类: 物理学 >> 核物理学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: The ambiguity of the structure of 12Be especially in the configuration of 12Be ground state has attracted a lot of attention recently. We notice that the nuclear reaction cross section R at low energy region is sensitive to the surface structure of 12Be, which is greatly impacted by the ground state configuration of 12Be especially by the occupancy probability of the s orbital component. By using existed interaction cross section data of 12Be on C at 790 MeV/nucleon and Glauber model, the upper limit of the s orbital occupation probability of 12Be ground state is roughly determined to be about 56% with Single Particle Model calculations. This demonstrates that the method is very promising to determine the s orbital component of 12Be with proper nuclear-matter density distribution calculations for different orbitals of 12Be ground state. Hence we bring forward to determine the s orbital component of 12Be by measuring the R of 12Be on C and Al at several tens of MeV/nucleon. In this paper, the feasibility and detailed experimental scheme of the R measurement are carefully studied. The precision of the s orbital occupation probability of 12Be ground state is expected to achieve 9% by using the proposed 2% R data.
分类: 核科学技术 >> 粒子加速器 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: The macromolecular crystallography beamline BL17U1 at the Shanghai Synchrotron Radiation Facility (SSRF) is the first dedicated macromolecular crystallography (MX) beamline at a third-generation synchrotron in China. It utilizes an in-vacuum undulator as a source and is energy-tunable from 5 to 18 keV. The beamline was commissioned and opened for users in April 2009. The experimental station was upgraded in 2011 with an advanced detector, a high precision goniometer and an automatic sample exchanger for high efficient and high-throughput data collection of protein crystals. The current set-up allows for remote operation of sample mounting, centering and data collection of pre-frozen crystals. In recent two years, the number of PDB depositions from this beamline exceeds 330 each year. In this paper, we describe the complete BL17U1 beamline with upgraded end station and how it is managed for user community.