为满足核工程对核数据的需求,对20 Me V以下65Cu(n,p)65Ni反应截面的实验数据进行了分析和评价,包括实验数据的收集、修正、选取、归一、误差调整和数据处理,在分析实验误差特别是关联误差的基础上构造了每家数据的协方差矩阵,最后利用样条拟合程序SPCC给出了评价截面数据和实验数据的协方差矩阵。评价不仅考虑了实验数据的误差,还考虑了数据间的相关性。
The masses of some orbitally and radially excited heavy-light mesons are calculated in Regge phenomenol- ogy. The results are in reasonable agreement with the experimental data and those given in many other theoretical approaches. Based on the calculation, we suggest that the recently observed D（2550）, D（2600） and D（2760） can be assigned as the charmed members of the 21S0, 23S1 and 13D1 multiplets, respectively. D＇1（2700） may be assigned as the charm-strange member of the 23S1 state. The results may be helpful in understanding the nature of current and future experimentally observed heavy-light mesons.
We investigate electron transport through Hg Te ribbons embedded by strip-shape gate voltage through using a nonequilibrium Green function technique. The numerical calculations show that as the gate voltage is increased, an edgerelated state in the valence band structure of the system shifts upwards, then hangs inside the band gap and merges into the conduction band finally. It is interesting that as the gate voltage is increased continuously, another edge-related state in the valence band also shifts upwards in the small-k region and contacts the previous one to form a Dirac cone in the band structure. Meanwhile in this process, the conductance spectrum displays as multiple resonance peaks characterized by some strong antiresonance valleys in the band gap, then behaves as Fabry–P＇erot oscillations and finally develops into a nearly perfect quantum plateau with a value of 2e^2/h. These results give a physical picture to understand the formation process of the Dirac state driven by the gate voltage and provide a route to achieving particular quantum oscillations of the electronic transport in nanodevices.
