检索结果-南通市图书馆

Tuner design and RF test of a four-rod RFQ

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2011年第S2期54卷 271-273页

作者： QuanFeng Zhou (1) Kun Zhu (1) ZhiYu Guo (1) MingLei Kang (1) ShuLi Gao (1) YuanRong Lu (1) JiaEr Chen (1) 1. State Key Lab of Nuclear Physics and Technology School of Physics Peking University Beijing 100871 China

A mini-vane four-rod radio frequency quadruple (RFQ) accelerator has been built for neutron imaging. The RFQ will operate at 201.5 MHz, and its length is 2.7 m. The original electric field distribution along the electrodes is not flat. The resonant frequency needs to be tuned to the operating value. And the frequency needs to be compensated for temperature change during high power RF test and beam test. As tuning such a RFQ is difficult, plate tuners and stick tuners are designed. This paper will present the tuners design, the tuning procedure, and the RF properties of the RFQ.

关键词： four-rod RFQ electric-field distribution RF tuning RF measurement

Design and manufacturing of the antechamber for BEPCII storage rings

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2011年第S2期54卷 164-168页

作者： Ling Kang (1) ChunHua Li (1) KaiXi Huang (1) HuaMin Qu (1) YiQing Zou (1) Yan Zhang (1) LuXiang Han (1) LingLing Men (1) 1. Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China

Antechamber which composes the arc vacuum chamber of storage rings is one of the key devices of BEPCII. It has the characteristic of various specifications, large size, complex structure, and high dimension accuracy. This paper gives a review on the structure features and the procedure of production, including the mechanical machining process, cleaning and welding process of high vacuum aluminum alloy, ultrahigh vacuum test and so on. In view of the occurrence of the concave deformation, the reasons are analyzed and the correction method developed is introduced too.

关键词： antechamber cleaning welding form correction

（3＋ 1）-TQFTs and topological insulators

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2012年第2期7卷 150-159页

作者： Kevin Walker (1) Zhenghan Wang (1) 1. Microsoft Station Q CNSI Bldg. Rm. 2243 University of California Santa Barbara CA 93106-6105 USA

Levin-Wen models are microscopic spin models for topological phases of matter in （2＋ 1）-dimension. We introduce a generalization of such models to （3 ＋ 1）-dimension based on unitary braided fusion categories, also known as unitary premodular categories. We discuss the ground state degeneracy on 3-manifolds and statistics of excitations which include both points and defect loops. Potential con- nections with recently proposed fractional topological insulators and projective ribbon permutation statistics are described.

关键词： topological quantum field theory (TQFT) topological insulator premodular category

Progress in the beam commissioning of separated function RFQ accelerator

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2011年第S2期54卷 222-224页

作者： MingLei Kang (1) YuanRong Lu (1) Zhi Wang (1) Kun Zhu (1) XueQing Yan (1) ZhiYu Guo (1) ShuLi Gao (1) ShiXiang Peng (1) Ao Liu (2) JiaXun Fang (1) JiaEr Chen (1) 1. State Key Laboratory of Nuclear Physics and Technology Peking University Beijing 100871 China2. Department of Physics Indiana University Bloomington IN 47405 USA

Separated Function RFQ (SFRFQ) was proposed as a post accelerator of RFQ to accelerate heavy ions at low frequency. It introduces gap accelerating in the quadrupole electrodes, and therefore it has higher accelerating efficiency than the conventional RFQ accelerator. The first SFRFQ prototype cavity has been specially designed and constructed as a post accelerator to accelerate O+ beam from 1.03 MeV to 1.64 MeV. based on accomplishment of low power measurement and high power test, the beam commissioning was carried out to verify its feasibility. The measured energy gain per cell of SFRFQ is 45 keV, which is about 60% higher than that of Peking University Integral Split Ring (ISR) RFQ.

关键词： separated function RFQ beam commissioning energy spectrum

Spin squeezing in Bose-Einstein condensates： Limits imposed by decoherence and non-zero temperature

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2012年第1期7卷 86-97页

作者： Alice Sinatra (1) Jean-Christophe Dornstetter (1) Yvan Castin (1) 1. Laboratoire Kastler Brossel Ecole Normale Supérieure UPMC and CNRS Paris France

We consider dynamically generated spin squeezing in interacting bimodal condensates. We show that particle losses and non-zero temperature effects in a multimode theory completely change the scaling of the best squeezing for large atom numbers. We present the new scalings and we give approximate analytical expressions for the squeezing in the thermodynamic limit. Besides reviewing our recent theoretical results, we give here a simple physical picture of how decoherence acts to limit the squeezing. We show in particular that under certain conditions the decoherence due to losses and non-zero temperature acts as a simple dephasing.

关键词： Bose-Einstein condensate decoherence

Quantum phase transition of cold atoms trapped in optical lattices

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of physics 2012年第2期7卷 223-234页

作者： Yao-hua Chen (1) Wei Wu (1) Guo-cai Liu (1) Hong-shuai Tao (1) Wu-ming Liu (1) 1. Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China

We review our recent theoretical advances in phase transition of cold atoms in optical lattices, such as triangular lattice, honeycomb lattice, and Kagome lattice. By employing the new developed numerical methods called dynamical cluster approximation and cellular dynamical mean-field theory, the properties in different phases of cold atoms in optical lattices are studied, such as density of states, Fermi surface and double occupancy. On triangular lattice, a reentrant behavior of phase translation line between Fermi liquid state and pseudogap state is found due to the Kondo effect. We find the system undergoes a second order Mott transition from a metallic state into a Mott insulator state on honeycomb lattice and triangular Kagom~ lattice. The stability of quantum spin Hall phase towards interaction on honeycomb lattice with spin-orbital coupling is systematically discussed. And we investigate the transition from quantum spin Hall insulator to normal insulator in Kagom~ lattice which includes a nearest-neighbor intrinsic spin-orbit coupling and a trimerized Hamiltonian. In addition, we propose the experimental protocols to observe these phase transition of cold atoms in optical lattices.

关键词： quantum phase transition optical lattice DMFT spin-orbit coupling

Input function and simulated distributions of tritium in the North Pacific

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2010年第3期53卷 441-453页

作者： ba Qi1,2 & XU YongFu1 1 State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China 2 Graduate University of Chinese Academy of Sciences, Beijing 100049, China State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Graduate University of Chinese Academy of Sciences Beijing China

An ocean general circulation model (OGCM) of the North Pacific with a southern open boundary condition is used to simulate the distribution and transport of tritium in the North Pacific. First, the observed tritium in precipitation dataset of GNIP/ISOHIS is chosen, and used to develop an input function of tritium for the model domain from 1951 to 1997 in terms of the triangulation for interpolation. Then, the input function is used as an upper flux for the tritium model. The OGCM with tritium is integrated for 47 years with the initial condition of zero tritium concentrations. Compared with the observations from GEOSECS and WOCE, the model generates a meridional gradient of surface tritium concentrations and the high tritium concentrations in the subsurface layer, which is consistent with that indicated in the observations. The simulated time series of total tritium fluxes from the atmosphere to the ocean shows a spike in 1963. The total inventory of tritium in the ocean changes slowly with time after 1975. Tritium enters the higher-latitude region, and then is mainly transported by the subsurface process towards the equatorial region, which is well simulated in the model. However, the difference mainly occurs at 30°N–40°N, which can be seen also in the simulation of CFCs. This difference may partly originate from the insufficient description of physical processes in the OGCM. Nevertheless, some uncertainties exist in the development of the tritium input function, which can also influence the simulated results.

关键词： North Pacific basin-wide ocean general circulation model tritium input function tritium distributions

Cloning and Expression Analysis of p26 Gene in Artemia sinica

在线全文

学校读者我要写书评

暂无评论

Acta Biochimica et Biophysica Sinica 2007年第5期39卷 351-358页

作者： Lijuan JIANG~1, Lin HOU~(1*), Xiangyang ZOU2, Ruifeng ZHANG~1, Jiaqing WANG~1, We njing SUN~1, Xintao ZHAO~1, and Jialu AN~1 1 College of Life Sciences, Liaoning Normal University, Dalian 116029, China 2 Department of Biology, Dalian Medical University, Dalian 116027, China College of Life Sciences Liaoning Normal UniversityDalian 116029 China Department of Biology Dalian Medical UniversityDalian 116027 China

The protein p26 is a small heat shock protein that functions as a molecular chaperone to protect embryos by preventing irreversible protein damage during embryonic development. A 542 bp fragment of the p26 gene was cloned and sequenced. The fragment encoded 174 amino acid residues and the amino acid sequence contained the α-crystallin domain. Phylogenetic analysis showed that eight Artemia populations were divided into four major groups. Artemia sinica (YC) belonged to the East Asia bisexual group. Expression of the p26 gene at different developmental stages ofA. sinica was quantified using real-time quantitative polymerase chain reaction followed by cloning and sequencing. The relationship between the quantity of p26 gene expression and embryonic development was analyzed. The results indicated that massive amounts of p26 were expressed during the development of A. sinica. At the developmental stage of 0 h, A. sinica expressed the highest level of p26. As development proceeded, expression levels of the p26 gene reduced significantly. There was a small quantity of p26 gene expression at the developmental stages of 16 h and 24 h. We concluded that p26 might be involved in protecting the embryo from physiological stress during embryonic development.

关键词： Artemia sinica cloning expression p26 gene real-time quantitative PCR

Human atlastin GTPases mediate differentiated fusion of endoplasmic reticulum membranes

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Protein & Cell 2015年第4期6卷 307-311页

作者： Xiaoyu Hu (1) Fuyun Wu (1) Sha Sun (1) Wenying Yu (1) Junjie Hu (1) (2) 1.Tianjin Key Laboratory of Protein Sciences Department of Genetics and Cell Biology College of Life Sciences Nankai University Tianjin 300071 China 2.National Laboratory of Biomacromolecules Institute of Biophysics Chinese Academy of Sciences Beijing 100101 China

Dear Editor,In eukaryotic cells, the endoplasmic reticulum （ER） is a continuous membrane system with interconnected tubules and sheets. The formation of a typical network requires constant fusion between ER membranes.

关键词：