HIAF-BRing的双向涂抹注入模拟

BRing是HIAF工程的主加速器,其设计流强为每个脉冲内的粒子数1×1011个（238U34+）,为了达到此设计流强,注入增益应达到88倍以上。BRing采用了双向涂抹注入方案,其满足BRing的注入增益要求,同时具有注入时间短和累计束分布较均匀而减小了空间电荷效应的特点。双向涂抹注入方案利用水平和垂直两组凸轨磁铁以及倾斜的静电偏转板,在水平相空间和垂直相空间内同时进行涂抹。为了检验双向涂抹注入方案能否达到BRing的设计要求,利用ORBIT程序对双向涂抹注入过程进行了模拟,模拟结果显示,在单次双向涂抹注入113圈的情况下,注入效率为97.7%,注入增益达到110.3倍,满足了BRing流强要求。累积束的分布相对均匀,空间电荷效应引起的工作点漂移约为-0.02,粒子因共振损失风险很小。针对注入束流偏角、切割板角度、工作点偏差和Bump延时等不同注入参数进行了误差分析,结果显示BRing的双向涂抹注入效率对注入参数偏差的容忍度较高。BRing is the main accelerator of High Intensity heavy Ion Accelerator Facility(HIAF) and its design current is 1×1011 particles per pulse (238U34+). To accumulate beams up to the design current, the injection gain has to reach 88. Two planes painting injection scheme is proposed for BRing. This scheme uses a tilted electrostatic septum and 8 bump magnets to paint beams into horizontal and vertical phase space simultaneously. It can inject enough beams into the ring in a short time and paint beams uniformly. The injection process is simulated using ORBIT code and 113 turns is injected into BRing with an injection efficiency of 97.7% which meets the requirement for beam current of BRing. The accumulated beams are distributed uniformly in transverse and hence have a little tune shift of -0.02 which reduces the risk of beam loss due to the resonance. Errors of injection parameters are analysed and the result shows two planes painting injection scheme has a high tolerance for errors of injection parameters.     

CSR-LINAC IH-RFQ的高频电磁设计

中国科学院近代物理研究所在CSR-LINAC项目中设计了一台108.48 MHz的IH型RFQ直线加速器。该RFQ可以将质荷比为3~7的离子从4 keV/u加速到300 keV/u。在完成束流动力学设计的基础上,主要针对RFQ腔体的高频电磁设计展开了研究,同时利用了电磁场仿真和束流动力学模拟来研究腔体的四极场不平整度和二极场及其动力学影响。未经调谐的情况下,腔体的谐振频率为108.15 MHz,腔体空载品质因子Q₀为5 910,腔体功耗为123 kW。通过在支撑板两端增加底切的设计,将腔体的四极场不平整度由-21%~ 12%优化至±2.5%,满足了束流动力学要求。腔体的二极场为-3%~ -2.2%,使得束流在垂直方向小幅振荡,RFQ的垂直方向接受度减小5%。为了保证功率馈入时反射较小,将耦合器设置在临界耦合状态,耦合面积为940 mm2。为了补偿腔体的频率偏差和漂移,设计了调谐量分别为707和132 kHz的固定调谐器和可动调谐器。The 108.48 MHz IH type RFQ for CSR-LINAC project is under design at Institute of Modern Physics, Chinese Academy of Sciences. This RFQ can accelerate heavy ions with mass to charge ratio of 3~7 from 4 keV/u to 300 keV/u. According to the beam dynamics requirement, the RF structure design has been finished. The quadrupole field unflatness and dipole field of the cavity were studied by electromagnetic simulation and beam dynamics simulation. The frequency of the cavity without tuning is 108.15 MHz, the Q₀ of the cavity is 5910, and the RF power loss is 123 kW. The quadrupole field unflatness of ±2.5%,which was -21%~12% before optimizing, is achieved to meet dynamics requirement through the undercuts in cavity supporters. The dipole field of -3%~ -2.2% causes the oscillation of the beam center and acceptance reduction of 5%. The power coupler must be in critical coupling state with the coupling area of 940 mm2 for minimum reflection coefficient. The tuners, consist of coarse and fine tuners with frequency shift of 707 and 132 kHz respectively, is used for tuning of frequency deviation of the cavity.     

HIAF-SRing的等时性模式光学设计

高精度环形谱仪SRing作为HIAF装置的核心之一,是获取高品质放射性次级束,并将束流用于加速器技术研究、原子物理及核物理实验的关键设备。SRing有三种运行模式:等时性模式、正常模式与内靶模式。等时性模式下,SRing运行在特殊线性光学设置下,可以精确测量寿命低至几十微秒的原子核的质量。介绍SRing等时性模式的线性光学及高阶项校正的设计方案。在使用程序GICOSY进行等时性高阶项校正数值计算后,将得到的光学传输矩阵输入到程序MOCADI进行粒子跟踪模拟。以γ_t=1.43的等时性模式为例,SRing的动量接收度为±0.20%,粒子跟踪结果显示,在仅满足一阶等时性条件时SRing的质量分辨能力R=1.6×104。在保证动量接收度不变的前提下,考虑了等时性高阶项校正后SRing的质量分辨能力提高到R=1.2×106,达到设计要求。The Spectrometer Ring, as the most important experiment terminal of the High Intensity heavy-ion Accelerator Facility (HIAF) project, is a key device to obtain high-quality radioactive ion beams (RIBs) for atomic physics, nuclear physics experiments and accelerator technology researches. Three operation modes including the isochronous mode, the normal mode and the internal target mode, have been designed for the SRing. In the isochronous mode, the SRing operates under a special ion optics and could be used for precision mass measurement of short-lived nuclei with half-life shorter than several tens of microseconds. This study aims to design the ion optics for the isochronous mode and improve the mass resolving power of the SRing with higher-order ion-optical correction scheme for isochronism while preserve a large momentum acceptance of SRing. The ion optics and the higher-order correction for the isochronous mode are calculated with the code MAD-X and GICOSY respectively. Three ion optics with γ_t=1.43, 1.67, 1.83 settings have been calculated. The code MCOADI which utilizes the matrixes generated by the code GICOSY is used for particles tracking to verify the correction results. For the ion-optical setting of γ_t=1.43 with a momentum acceptance of ±0.20%, the mass resolving power of the SRing could be improved from R=1.6×104 to R=1.2×106, after isochronous higher-order corrections.     

Engineering DNA logic systems with non-canonical DNA-nanostructures:basic principles,recent developments and bio-applications

Engineering DNA logic systems is considered as one of the most promising strategies for next-generation molecular computers.Owing to the inherent features of DNA,such as low cost,easy synthesis,and controllable hybridization,various DNA logic devices with different functions have been developed in the recent decade.Besides,a variety of logic-programmed biological applications are also explored,which initiates a new chapter for DNA logic computing.Although this field has gained rapid developments,a systematical review that could not only elaborate the logic principles of diverse DNA logic devices but also outline recent representative works is urgently needed.In this review,we first elaborate the general classification and logical principle of diverse DNA logic devices,in which the operating strategy of these devices and representative examples are selectively presented.Then,we review state-of-the-art advancements in DNA computing based on different non-canonical DNA-nanostructures during the past decade,in which some classical works are summarized.After that,the innovative applications of DNA computing to logic-controlled bioanalysis,cell imaging,and drug load/delivery are selectively presented.Finally,we analyze current obstacles and suggest appropriate prospects for this area.     

菲涅耳数字全息图的Gabor小波变换再现法

提出了一种基于Gabor小波变换的菲涅耳全息图的数值再现方法,实现无需空间滤波处理,即可对物光波进行数值再现.给出Gabor小波变换以及小波变换脊的定义,并从理论上证明通过对全息图进行Gabor小波变换,提取小波变换脊对应的小波变换系数,包括幅值与相位信息,即可直接获得与+1级频谱相对应的被测物光在全息面上的强度与相位分布,并同时直接消除零级衍射像以及孪生像的影响.通过计算机模拟再现光波经全息图衍射后的传播规律实现数值再现,得到清晰的再现像.通过计算机模拟一相位型物体以及实验证明该方法的有效性.     

冷却储存实验环功率源的设计与计算

 对兰州重离子加速器冷却储存环实验环(CSRe)的高频系统功率源的设计作了详细的工程计算,工作频率范围为0.5~2.0 MHz,工作于基波及二次谐波模式,发射机不仅能工作于点频连续波模式,而且还可以工作在扫频调制模式,输出最大功率达到70 kW。满足最高加速或减速电压10 kV的设计要求,能够用于捕获放射性次级束并将束流的能量从400 MeV/u 减速到 30 MeV/u。     

CSRm闭轨畸变及其校正的模拟研究

在给定的磁铁安装误差和磁场加工误差的条件下,对兰州重离子加速器冷却储存环主环的闭轨畸变及其校正进行了计算机模拟研究,在典型的误差分布下,校正前的水平方向及垂直方向的最大闭轨畸变分别为3.08mm和2.73mm,校正模拟的结果显示CSRm的闭轨畸变可以控制在足够小的范围内.     

不饱和碳碳键电化学加氢的最新研究进展

选择性加氢是有机合成反应中最为经典的反应之一,它在天然产物、药物和工业化学品的制造中有着广泛的应用。传统的加氢反应因为其高温高压、危险系数大和使用贵重金属等诸多不利因素,所以人们一直希望能发现更安全温和的加氢反应方法。近年来,由于电化学加氢方法反应条件温和、能量消耗低及反应进程容易控制等优势越来越受到人们的重视,并取得了许多研究成果。本综述依据电化学加氢反应的化学键类型,对近几年来的不饱和碳碳键电化学加氢相关文献报道进行了归纳和综述,希望为电化学加氢研究提供一定指导意义。     

Analysis of β-blockers and β2-agonists in environmental and biological samples by magnetic solid-phase extraction combined with high-performance liquid chromatography-tandem mass spectrometry

β-Blockers and β2-agonists are commonly prescribed for therapeutic treatments and are also administered to livestock, leading to their presence in both environmental and biological samples. Hence, the development of sensitive, rapid, and reliable analytical methods for the determination of β-blockers and β2-agonists in environmental and biological samples is important. In this study, MIL-101(Cr)-NH₂&GO-coated SiO₂/Fe₃O₄ magnetic particles were prepared as sorbents for magnetic solid-phase extraction and then combined with high-performance liquid chromatography-tandem mass spectrometry for the analysis of 20 β-blockers and eight β2-agonists. The experimental parameters of magnetic solid-phase extraction were studied in detail, and the optimal conditions were established. Under optimal conditions, the limits of detection were in the range of 0.002–0.007 μg/L with enrichment factors of 20.2–24.9. The developed method was successfully applied for the determination of 20 β-blockers and eight β2-agonists in river water, human urine, and freeze-dried pork liver powder. Bisoprolol and salbutamol were detected at concentrations of 2.78 mg/L in human urine and 11.5 μg/kg in freeze-dried pork liver powder.     

疲劳短裂纹扩展速率的电测技术

木文研究了间接直流电位法(IDC法)和交流电位法(AC法)用于监测疲劳短裂纹扩展速率的有关技术问题。文中提出了一种用电磁场边界元法对电位法进行标定的理论标定方法。研究了有关的试验标定方法。并对IDC法和AC法的适用范围、灵敏度和稳定性等做了详细的比较分析。