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Recent commissioning of the Cooler Storage Ring at the Heavy Ion Research Facility in Lanzhou enabled us to conduct high-precision mass measurements at the Institute of Modern Physics in Lanzhou (IMP). In the past few years, mass measurements were performed using the CSRe-based isochronous mass spectrometry employing the fragmentation of the energetic beams of 58Ni, 78Kr, 86Kr, and 112Sn projectiles. Masses of short-lived nuclides on both sides of the stability valley were addressed. Relative mass precision of down to 10−6 ~ 10−7 is routinely achieved. The mass values were used as an input for dedicated nuclear structure and astrophysics studies, providing for instance new insights into the rp-process of nucleosynthesis in X-ray bursts. In this contribution, we briefly review the so far conducted experiments and the main achieved results, as well as outline the plans for future experiments.  相似文献   

本文报导了合成109号元素的实验。用能量为4.95,5.05和5.15MeV/u 的~(58)Fe 束轰击~(209)Bi 靶,研究了全熔合产物衰变模式的特性。总辐照剂量为7×10~(17)粒子。所用的实验方法是:用静电场速度过滤器在飞行过程中分离向前方向成峰的反应产物,经过飞行时间装置后注入到位置灵敏固态探测器中,测量其动能,估算出质量、入射的时间和位置。以所有的出射粒子的能量和时间来记录很有限的反应产物发生级联α粒子和(或)自发裂变的继发衰变。在5.15 MeV/u 时的一个特别的衰变过程是:在5ms 和22ms 先分别发射两个α粒子,最后,在13s 后发生自发裂变。第一个α粒子的动能为11.10±0.04MeV。对各种可能的解释进行了详细的分析,例如纯属偶然的信号相关,转移反应产物的衰变和从能量上看允许的余核蒸发等。最后表明质量数为266的109号元素的同位素、即全熔合后的单中子蒸发道、从统计的观点看是最好的指定。本文同时也讨论了合成新元素的前景。  相似文献   

Simultaneous bandwidth(BW) enhancement and time-delay signature(TDS) suppression of chaotic lasing over a wide range of parameters by mutually coupled semiconductor lasers(MCSLs) with random optical injection are proposed and numerically investigated. The influences of system parameters on TDS suppression(characterized by autocorrelation function(ACF) and permutation entropy(PE) around characteristic time) and chaos BW are investigated. The results show that, with the increasing bias current, the ranges of parameters(detuning and injection strength) for the larger BW(> 20 GHz) are broadened considerably, while the parameter range for optimized TDS(< 0.1) is not shrunk obviously.Under optimized parameters, the system can simultaneously achieve two chaos outputs with enhanced BW(> 20 GHz)and perfect TDS suppression. In addition, the system can generate two-channel high-speed truly physical random number sequences at 200 Gbits/s for each channel.  相似文献   

Gamal G.L. Nashed 《中国物理 B》2010,19(2):20401-020401
The energy--momentum tensor, which is coordinate-independent, is used to calculate energy, momentum and angular momentum of two different tetrad fields. Although, the two tetrad fields reproduce the same space--time their energies are different. Therefore, a regularized expression of the gravitational energy--momentum tensor of the teleparallel equivalent of general relativity (TEGR), is used to make the energies of the two tetrad fields equal. The definition of the gravitational energy--momentum is used to investigate the energy within the external event horizon. The components of angular momentum associated with these space--times are calculated. In spite of using a static space--time, we get a non-zero component of angular momentum! Therefore, we derive the Killing vectors associated with these space--times using the definition of the Lie derivative of a second rank tensor in the framework of the TEGR to make the picture more clear.  相似文献   

王继锁  范洪义  孟祥国 《中国物理 B》2010,19(3):34206-034206
We discuss quantum fluctuation in excited states(named thermo number states) of mesoscopic LC circuits at a finite temperature.By introducing the coherent thermo state into the thermo field dynamics pioneered by Umezawa and using the natural representation of thermo squeezing operator we can concisely derive the fluctuation.The result shows that the noise becomes larger when either temperature or the excitation number increases.  相似文献   

This paper discusses the Ⅰ-Ⅴ property of the GaAs-based resonant tunnelling structure(RTS) under external uniaxial pressure by photoluminescence studies.Compressive pressure parallel to the [110] direction,whose value is determined by Hooke's law,is imposed on the sample by a helix micrometer.With the increase of the applied external uniaxial compressive pressure,the blue shift and splitting of the luminescence peaks were observed,which have some influence on the I-V curve of RTS from the point of view of the energy gap,and the splitting became more apparent with applied pressure.Full width at half maximum broadening could also be observed.  相似文献   

匀速圆周运动是曲线运动章节的教学重点.现行高中及中专教材均以两节的篇幅来讨论这种运动.一节是建立匀速圆周运动的概念,引入描述匀速圆周运动快慢的4个量,即周期(T)、频率(v)、角速度(ω)、线速度(v),并讨论这4个量的关系.另一节则从受力的角度讨论圆周运动的向心力及向心加速度.共涉及6个量.由于这6个量之间彼此存在一定的关系,这就使圆周运动具有较多的公式.如果学生能熟练掌握这些公式以及它们之间相互关系的规律,解题就能  相似文献   

董嫣然  张树东  侯圣伟  程起元 《中国物理 B》2012,21(8):83104-083104
Potential energy curves(PECs) for the ground state(X 2 Σ +) and the four excited electronic states(A 2 Π,B 2 Π,C 2 Σ +,4 Π) of a BeH molecule are calculated using the multi-configuration reference single and double excited configuration interaction(MRCI) approach in combination with the aug-cc-pVTZ basis sets.The calculation covers the internuclear distance ranging from 0.07 nm to 0.70 nm,and the equilibrium bond length R e and the vertical excited energy T e are determined directly.It is evident that the X2Σ+,A2Π,B2Π,C2Σ+ states are bound and 4Π is a repulsive excited state.With the potentials,all of the vibrational levels and inertial rotation constants are predicted when the rotational quantum number J is set to be equal to zero(J = 0) by numerically solving the radial Schr¨odinger equation of nuclear motion.Then the spectroscopic data are obtained including the rotation coupling constant ω e,the anharmonic constant ωexe,the equilibrium rotation constant Be,and the vibration-rotation coupling constant αe.These values are compared with the theoretical and experimental results currently available,showing that they are in agreement with each other.  相似文献   

With the full-vector plane-wave method (FVPWM) and the full-vector beam propagation method (FVBPM),the dependences of the band-gap and mode characteristics on material index and cladding structure parameter in antiresonance guiding photonic crystal fibres (ARGPCFs) are sufficiently analysed.An ARGPCF operating in the nearinfrared wavelength is shown.The influences of the high index cylinders,glass interstitial apexes and silica structure on the characteristics of band-gaps and modes are deeply investigated.The equivalent planar waveguide theory is used for analysing such an ARGPCF filled by the isotropic materials,and the resonance and the anti-resonance characteristics can be well predicted.  相似文献   

孟祥国  王继锁  梁宝龙 《中国物理 B》2011,20(5):50303-050303
Using the technique of integration within an ordered product of operators,we find a new kind of coherent-entangled state(CES),which exhibits both coherent and entangled state properties.The set of CESs makes up a complete and partly nonorthogonal representation.Using a beam splitter,we propose a simple experimental scheme to produce the CES.Finally,we present some applications of CESs in quantum optics.  相似文献   

蒋哲  李小凡  周玉淑  高守亭 《中国物理 B》2012,21(5):54215-054215
The effects of sea surface temperature(SST),cloud radiative and microphysical processes,and diurnal variations on rainfall statistics are documented with grid data from the two-dimensional equilibrium cloud-resolving model simulations.For a rain rate of higher than 3 mm.h 1,water vapor convergence prevails.The rainfall amount decreases with the decrease of SST from 29℃ to 27℃,the inclusion of diurnal variation of SST,or the exclusion of microphysical effects of ice clouds and radiative effects of water clouds,which are primarily associated with the decreases in water vapor convergence.However,the amount of rainfall increases with the increase of SST from 29℃ to 31℃,the exclusion of diurnal variation of solar zenith angle,and the exclusion of the radiative effects of ice clouds,which are primarily related to increases in water vapor convergence.For a rain rate of less than 3 mm.h 1,water vapor divergence prevails.Unlike rainfall statistics for rain rates of higher than 3 mm.h 1,the decrease of SST from 29℃ to 27℃ and the exclusion of radiative effects of water clouds in the presence of radiative effects of ice clouds increase the rainfall amount,which corresponds to the suppression in water vapor divergence.The exclusion of microphysical effects of ice clouds decreases the amount of rainfall,which corresponds to the enhancement in water vapor divergence.The amount of rainfall is less sensitive to the increase of SST from 29℃ to 31℃ and to the radiative effects of water clouds in the absence of the radiative effects of ice clouds.  相似文献   

周平  曹玉霞 《中国物理 B》2010,19(10):100507-100507
This paper investigates the function projective synchronization between fractional-order chaotic systems and integer-order chaotic systems using the stability theory of fractional-order systems. The function projective synchronization between three-dimensional (3D) integer-order Lorenz chaotic system and 3D fractional-order Chen chaotic system are presented to demonstrate the effectiveness of the proposed scheme.  相似文献   

针对加速器驱动次临界系统(ADS)注入器Ⅱ对超导磁铁电源系统的要求,设计了一款主要由光纤模块、数模转换器(DAC)和模数转换器(ADC)相关电路组成的高稳定度的超导磁铁电源控制器。提出了一种基于数字电位器(DCP)与现场可编程门阵列(FPGA)所组成的DAC,该DAC可以实现高稳定度的超导磁铁电源的控制,电源电流值通过该DAC给定,其电压给定输出稳定度优于2×10-5,完全满足超导磁铁电源系统5×10-5量级的稳定度要求。最后给出了系统的实际测试数据,验证了设计的合理性和使用的可靠性。  相似文献   

由于束流脉冲无法控制而引起直线加速器的热冲击损伤是造成加速器无法完成聚束及偏转的主要因素,而对热冲击进行定量的热应力评估可以有效地避免RFQ、超导腔以及其他加速元件等加速器设备的损伤,这在研制强流直线加速器的过程中至关重要。本研究引用一种新颖的计算方法定量分析整个注入器的热冲击损伤并明确了三种不同材料高纯铌、无氧铜和不锈钢对应的加速器件的热冲击的特征。基于有限元方法对瞬态热应力进行分析,得出三种不同材料对应的加速器件在入射角度为90度时的温度分析结果。对于所研制的注入能量低于10 MeV的强流直线加速器来讲,得到可允许的入射时间为20μs。  相似文献   

在同位旋依赖的量子分子动力学(IQMD)和Boltzmann-Uehling-Uhlenbeck(BUU)的框架下研究了重离子碰撞过程中核物质的剪切粘滞系数与熵密度的比值。用不同的方法提取了剪切粘滞系数(η)、熵密度(s)和其他相关的物理量。随着碰撞能量的增加,粘滞系数和熵密度的比值在BUU模型中逐渐趋于一个饱和值而在IQMD模型中出现了一个极小值,认为这个局域的最小值或饱和值对应于中能重离子碰撞中发生的核物质液气相变现象。  相似文献   

近年来,国际社会对核材料保护、控制和衡算日益加强。对不明材料损失量(MUF)的关注逐渐提升。铀材料质量不确定性测量在估算铀材料生产量中扮演重要角色。由于铀材料自发裂变相对较弱,主动中子多重性法被应用于估算铀材料质量。通过拟合对不同系列铀金属壳的数值模拟结果,获得了描述铀材料质量与主动中子多重性特征之间的算法和参数。得到的关系表明,可以通过分析不同重数中子多重性探测结果获得铀部件的质量。对不同探测条件下的模拟结果的定量分析,确定了探测系统设置对铀质量估算的影响,以及认知不确定性和随机不确定在估算过程中传播对质量估算的影响。对不确定度的分析获得了本文模拟采用的探测系统的最佳源强和探测时间窗设置,在此设置下,质量估算的不确定性最小。  相似文献   

This is the second part of the new evaluation of atomic masses,Ame2020.Using least-squares adjustments to all evaluated and accepted experimental data,described in Part I,we derived tables with numerical values and graphs which supersede those given in Ame2016.The first table presents the recommended atomic mass values and their uncertainties.It is followed by a table of the influences of data on primary nuclides,a table of various reaction and decay energies,and finally,a series of graphs of separation and decay energies.The last section of this paper provides all input data references that were used in the Ame2020 and the Nubase2020 evaluations.  相似文献   

杨秀丽  戴保东  张伟伟 《中国物理 B》2012,21(10):100208-100208
Based on the complex variable moving least-square(CVMLS) approximation and a local symmetric weak form,the complex variable meshless local Petrov-Galerkin(CVMLPG) method of solving two-dimensional potential problems is presented in this paper.In the present formulation,the trial function of a two-dimensional problem is formed with a one-dimensional basis function.The number of unknown coefficients in the trial function of the CVMLS approximation is less than that in the trial function of the moving least-square(MLS) approximation.The essential boundary conditions are imposed by the penalty method.The main advantage of this approach over the conventional meshless local Petrov-Galerkin(MLPG) method is its computational efficiency.Several numerical examples are presented to illustrate the implementation and performance of the present CVMLPG method.  相似文献   

陈明君  姜伟  李明全  陈宽能 《中国物理 B》2010,19(6):64203-064203
The KH 2 PO 4 crystal is a key component in optical systems of inertial confinement fusion (ICF).The microwaviness on a KH 2 PO 4 crystal surface is strongly related to its damage threshold which is a key parameter for application.To study the laser induced damage mechanism caused by microwaviness,in this paper the near-field modulation properties of microwaviness to the incident wave are discussed by the Fourier modal method.Research results indicate that the microwaviness on the machined surface will distort the incident wave and thus lead to non-uniform distribution of the light intensity inside the crystal;in a common range of microwaviness amplitude,the light intensity modulation degree increases about 0.03 whenever the microwaviness amplitude increases 10 nm;1 order diffraction efficiencies are the key factors responsible for light intensity modulation inside the crystal;the light intensity modulation is just around the microwaviness in the form of an evanescent wave,not inside the crystal when the microwaviness period is below 0.712 μm;light intensity modulation degree has two extreme points in microwaviness periods of 1.064 μm and 1.6 μm,remains unchanged between periods of 3 μm and 150 μm,and descends above the period of 150 μm to 920 μm.  相似文献   

We propose a joint exponential function and Woods–Saxon stochastic resonance(EWSSR)model.Because change of a single parameter in the classical stochastic resonance model may cause a great change in the shape of the potential function,it is difficult to obtain the optimal output signal-to-noise ratio by adjusting one parameter.In the novel system,the influence of different parameters on the shape of the potential function has its own emphasis,making it easier for us to adjust the shape of the potential function.The system can obtain different widths of the potential well or barrier height by adjusting one of these parameters,so that the system can match different types of input signals adaptively.By adjusting the system parameters,the potential function model can be transformed between the bistable model and the monostable model.The potential function of EWSSR has richer shapes and geometric characteristics.The effects of parameters,such as the height of the barrier and the width of the potential well,on SNR are studied,and a set of relatively optimal parameters are determined.Moreover,the EWSSR model is compared with other classical stochastic resonance models.Numerical experiments show that the proposed EWSSR model has higher SNR and better noise immunity than other classical stochastic resonance models.Simultaneously,the EWSSR model is applied to the detection of actual bearing fault signals,and the detection effect is also superior to other models.  相似文献   

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