Spin determination by in-plane angular correlation analysis in various coordinate systems

In the excitation of the resonant state followed by the sequential cluster-decay,the in-plane angular correlation method is usually employed to determine the spin of the mother nucleus.However,the correlation pattern exhibited in a two-dimensional angular-correlation spectrum depends on the selected coordinate system.In particular,the parity-symmetric and axial-symmetric processes should be presented in a way to enhance the correlation pattern,whereas the non-symmetric process should be plotted separately to reduce the background.In this study,three coordinate systems previously adopted for correlation patterns in the literature are described and compared to each other.The consistency among these systems is evaluated based on the experimental data analysis for the 10.29-MeV state in ~(18) O.A spin-parity of 4~+ is obtained for all three coordinate systems.     

硅探测器的数字化脉冲形状甄别

介绍了利用硅探测器的脉冲形状甄别进行粒子鉴别的原理。详细叙述了基于数字化方法的脉冲形状甄别的实现。采样频率和位数是数字化方法的两个重要参数。对于硅探测器信号,采用100 MS/s,12 bit的Digitizer可以满足脉冲形状甄别法对时间分辨的要求。同时对该方法粒子鉴别的特征和能量阈值做了简要的分析和对比。粒子背面入射硅探测器的所得的阈值低于正面入射的情况。例如对于氖周围的同位素,背面入射情况的阈值约为100 MeV,为正面入射情况下鉴别阈值的二分之一,相当与ΔE-E方法中ΔE探测器厚度约为60 μm情况下的阈值。最后定性讨论了硅探测器的电阻率不均匀性和沟道效应对粒子鉴别性能的影响。In this paper Pulse Shape Discrimination(PSD) for silicon detector has been briefly introduced. The emerging digital method successfully applied to detector signal processing makes digital PSD method one of the most promising particle identification methods. Sampling frequency and the number of bits are two key parameters of digital method. For silicon detector signal, adopting 100 Ms/s, 12 bit Digitizer can satisfy the time resolution requirement of PSD method. The identification characteristic and energy threshold of this method have been discussed and compared with both front injection and rear injection cases. Energy threshold with rear injection usually is much lower than that with front injection. For example, around for Neon isotope energy threshold with rear injection is about 100 MeV which is only half of the threshold with front injection, also equivalent to thickness of about 60 μm silicon detector threshold in ΔE-E method. At the end the impact of silicon detector's resistivity nonuniformity and channel effect on the identification capacity of PSD method has been discussed in detail.     

Investigation of the near-threshold cluster resonance in ~(14)C

An experiment for p(~(14)C,~(14)C~*→~(10)Be+α)p inelastic excitation and decay was performed in inverse kinematics at a beam energy of 25.3 Me V/u.A series of~(14)C excited states,including a new one at 18.3(1)Me V,were observed which decay to various states of the final nucleus of~(10)Be.A specially designed telescope system,installed around zero degrees,played an essential role in detecting the resonant states near theα-separation threshold.A state at 14.1(1)Me V is clearly identified,being consistent with the predicted band-head of the molecular rotational band characterized by theπ-bond linear chain configuration.Further clarification of the properties of this exotic state is suggested by using appropriate reaction tools.     

异长春花苷内酰胺的光化学降解

报道了异长春花苷内酰胺在水溶液中经自然光照射后, 发生光氧化反应, 主要降解产物为(3S)-短小蛇根草苷. 采用通入氧气和日光灯照射的方法可加速异长春花苷内酰胺光降解, (3S)-短小蛇根草苷的产率为56%.     

High-efficiency focusing grating coupler with optimized ultra-short taper

A novel high-efficiency focusing non-uniform grating coupler is proposed to couple light into or off silicon photonic chips for large-scale silicon photonic integration. This kind of grating coupler decreases the transition length of the linking taper between the grating and the single-mode waveguide by at least 80%. The radian of the grating lines and the size of the taper are optimized to improve the coupling efficiency. An experimental coupling efficiency of ~ 68% at 1556.24 nm is obtained after optimization and the whole size of the grating is 12 μm × 30 μm, with a very short taper transition of ~15 μm long.     

聚醚醚酮表面的亲水改性和胶原蛋白固定化

采用紫外光接枝法对聚醚醚酮(PEEK)表面进行化学修饰和生物分子固定化.首先向PEEK表面引入亲水性的丙烯酰胺,并以此为反应位点通过戊二醛将胶原和胶原蛋白固定在PEEK表面.用接触角测定仪、扫描电镜、荧光标记和X射线光电子能谱等对改性薄膜进行了表征.结果表明,PEEK上丙烯酰胺的接枝密度高达50.9μg/cm~2;改性薄膜表面浸润性显著提高,水接触角最低降至(22±3)°.荧光标记胶原固定的PEEK薄膜荧光发射光谱强度最高,并在X射线光电子能谱中检测到N元素,表明胶原已固定化,固定胶原蛋白的浓度为10.2μg/cm~2.     

广义中立型系统的渐近稳定性及数值分析

１．引 言 考察如下广义中立型系统：其中,Ｌ,Ｍ,Ｎ ∈ Ｃｄ×ｄ为已知矩阵,　　　为已知向量值函数,　　　　　　　　　　当ｔ＞０时为未知函数,　　　　　　　　　　　　　　　　　　　　　　　　　为常数延时量． 对于　　　　　　　　　　　　　　　　　,１９６７年,Ｂｒａｙｔｏｎ［１］基于Ｌ,Ｍ,Ｎ为实对称矩阵,以及Ｉ± Ｎ和－Ｌ± Ｍ为正定矩阵时,讨论了（１）渐近稳定的充分条件;１９８４年,Ｊａｃｋｉｅｗｉｃｚ［２］基于 Ｌ,Ｍ,Ｎ为复系数时,研究了理论解的渐近稳定性及单步方法的数值稳定性;１９８８年,Ｂ…     

磷酸铁锂电池的热效应研究

以磷酸铁锂为正极材料,石墨为负极材料,制备了1865型磷酸铁锂电池,研究了该电池在绝热、隔热和自然散热条件下,不同大小电流充放电过程的热效应.研究结果表明,磷酸铁锂电池充放电过程中所放出的热量主要来源于不可逆发热,即电子、离子在传导过程中克服电池内部阻力所产生的热量.发热量与电流呈线性关系,随着电流的增大而增大.这些结...     

活性炭吸附氦气式回热器的吸附特性研究

回热式低温制冷机在空间探测和地面实验中都有重要应用,但是在液氦温区工质氦气的体积比热容高于目前几乎所有的蓄冷材料,导致回热器效率低下.直接使用活性炭吸附一部分工质氦气作为蓄冷填料是一种潜在的解决方案.基于4～J10 K温度区间内吸附量的实验数据,建立了低温动态吸附计算模型,分析了液氦温区动态吸附特性对回热器性能参数的影...     

相机阵列在空间目标初轨确定中的应用

将由商业相机组成的相机阵列应用于空间目标的初轨确定。介绍了相机阵列的系统概况,结合相机阵列的技术特点,从空间目标探测能力、定位精度、初轨确定算法改进三方面分析了将相机阵列应用于空间目标初轨确定的可行性,提供了主要流程,进行了实验验证。实验结果初步展示了相机阵列系统在提高极限探测星等和初轨确定精度方面的能力。