Synthesis and field emission of diamond-like carbon nanorods on TiO2/Ti nanotube arrays

Highly ordered TiO2/Ti nanotube arrays were fabricated by anodic oxidation method in 0.5 wt% HF. Using prepared TiO2/Ti nanotube arrays deposited Ni nanoparticles as substrate, high quality diamond-like carbon nanorods (DLCNRs) were synthesized by a conventional method of chemical vapor deposition at 750 degrees C in nitrogen atmosphere. DLCNRs were analyzed by filed emission scanning electron microscopy and Raman spectrometer. It is very interesting that DLCNRs possess pagoda shape with the length of 3-10 mu m. Raman spectra show two strong peaks about 1332 cm (1) and 1598 cm (1), indicating the formation of diamond-like carbon. The field emission measurements suggest that DLCNRs/TiO2/Ti has excellent field emission properties, a low turn-on field about 3.0 V/mu m, no evident decay at 3.4 mA/cm(2) in 480 min. (C) 2009 Elsevier B. V. All rights reserved.

Microelements in Potato and Lily Samples Studied by Laser-Induced Breakdown spectroscopy Technology

A LIBS setup was built in the Institute of Modern Physics. In our experiments, LIBS spectra produced by infrared radiation of Nd : YAG nanosecond laser with 100 and 150 mJ pulse energy, respectively, were measured by fiber optic spectrometer in the ranges of 230-430 run and 430-1080 nm with a delay time of 1.7 and gate width of 2 ms for potato and lily samples prepared by vacuum freeze-dried technique. The lines from different metal elements such as K, Ca, Na, Mg, Fe, Al, Mn and Ti, and nonmetal elements such as C, N, O and H, and some molecular spectra from C-2, CaO, and CN were identified according to their wavelengths. The relative content of the six microelements, Ca, Na, K, Fe, Al, and Mg in the samples were analyzed according to their representative line intensities. By comparison we found that there are higher relative content of Ca and Na in lily samples and higher relative content of Mg in potato samples. The experimental results showed that LIBS technique is a fast and effective means for measuring and comparing the contents of microelements in plant samples.

Latest progress of the RFQ cooler and buncher RFQ1L

The RFQ cooler and buncher RFQ1L is a key device of the SHANS (Spectrometer for Heavy Atoms and Nucleax Structure). The status of the machining and assembly of the central part is introduced, and the structure of the whole RFQ1L system and the preliminary plan for the testing are discussed also.

Fast simulation of the forward tracking detector of HPLUS

The necessity of installing a forward tracking detector stack is discussed for the Hadron Physics LanzhoU Spectrometer(HPLUS). A local tracker is developed to solve the multi-track finding problem. The track candidates are searched iteratively via Hough Transform. The fake tracks are removed by a least square fitting process. With this tracker we have studied the feasibility of pp -> pp + phi(-> K+K-), a typical physical channel proposed on HPLUS. The single track momentum resolution due to the uncertainty of the positioning in FTD is 1.3%. The multiple scattering effect contributes about 20% to the momentum resolution in the FTD coverage. The width and the signal-to-background ratio of the reconstructed phi are 1.51 MeV and 4.36, respectively, taking into account the direct Kaon channel pp -> pp + K+K- as background. The geometry coverage of FTD for phi events is about 85.4%. Based on the current fast simulation and estimation, the geometrical configuration of FTD meets the physical requirement of HPLUS under the current luminosity and multiplicity conditions. The tracker is applicable in the full simulation coming next and is extendable to other tracking component of HPLUS.

Hadron physics programs at HIRFL-CSRm: Plan and status

An internal target experiment at HIRFL-CSRm is planned for hadron physics, which focuses on hadron spectroscopy, polarized strangeness production and medium effect. A conceptual design of Hadron Physics Lanzhou Spectrometer (HPLUS) is discussed. Related computing framework involves event generation, simulation, reconstruction and final analysis. The R&D works on internal target facilities and sub-detectors are presented briefly.

Experimental study of the high-voltage breakdown and simulations for the RFQ cooler and buncher RFQ1L

The RFQ cooler and buncher RFQ1L is one of the key parts of the being-built super-heavy nuclide research spectrometer. In order to understand the high-voltage breakdown phenomenon, the voltages between electrodes have been measured. In addition, more extensive simulations have been performed for better understanding and optimizing the RFQ1L work points.

Penning trap mass measurements on nobelium isotopes

The Penning trap mass spectrometer SHIPTRAP at GSI Darmstadt allows accurate mass measurements of radionuclides, produced in fusion-evaporation reactions and separated by the velocity filter SHIP from the primary beam. Recently, the masses of the three nobelium isotopes No252-254 were determined. These are the first direct mass measurements of transuranium elements, which provide new anchor points in this region. The heavy nuclides were produced in cold-fusion reactions by irradiating a PbS target with a Ca-48 beam, resulting in production rates of the nuclei of interest of about one atom per second. In combination with data from decay spectroscopy our results are used to perform a new atomic-mass evaluation in this region.

Secondary electron time detector for mass measurements at CSRe

The Isochronous Mass Spectrometry is a high accurate mass spectrometer. A secondary electrons time detector has been developed and used for mass measurements. Secondary electrons from a thin carbon foil are accelerated by ail electric field and deflected 180 degrees by a magnetic field onto a micro-channel plate. The time detector has been tested with alpha particles and a time resolution of 197 ps (FWHM) was obtained in the laboratory. A mass resolution around 8 x 10(-6) For Delta m/m was achieved by using this time detector in a pilot mass measurement experiment.

Progress on the RFQ1L and LPT

The SHANS spectrometer is under construction in the Institute of Modern Physics, Chinese Academy of Science. The RFQ cooler and buncher RFQ1L is one of the key devices in the SHANS. To perform direct mass measurement, the Lanzhou Penning Trap LPT is also under construction. In this symposium, the principle of the SHANS, the status of RFQ1L and LPT and some primary test results will be reported.

超重谱仪充气段及其初步调试

论文介绍了超重充气谱仪的基本原理及此类装置的国际现状，在此基础上，对中国科学院近代物理研究所超重谱仪充气段的基本情况进行了描述。本工作采用离线和在线的方法对超重谱仪充气段进行了调试。在离线实验中，通过改变α源及探测装置的位置，确定了谱仪的接收度，得到了谱仪对不同能量及发散度的α粒子的传输效率，测试了充气对谱仪传输效率的影响，并对靶厚与传输效率间的关系进行了模拟研究。根据离线实验的结果，对谱仪进行了合理的改进。在线实验利用重离子束流轰击薄靶并观测靶反冲核的方法，确认了束流监测装置的最佳探测器和最佳安装位置，测试了谱仪对一些靶反冲核的传输效率。通过初步调试，测试了该超重谱仪充气段的一些基本性能，测量了谱仪的一些相关参数，为其投入今后的物理实验研究提供了必要的经验和参考

超重谱仪中冷却聚束器RFQ1L的模拟研究

对超重核和超重元素越来越多的探索和研究，以及对远离β稳定线奇异核的精细研究，都迫切地需要低能量、高品质的放射性束流。然而，由原子核反应产生的放射性束流普遍具有能量分散大、发射度大以及束流斑点大的缺点，因此，对放射性次级束流进行进一步的操控成为深入研究的必需条件。充有缓冲气体的RFQ冷却聚束器是适合这项任务的最佳选择。它不但可以高速度、高效率地提高束流的品质，而且适用于所有的核素。这项技术在上世纪末蓬勃地发展起来，现在已经成为世界各主要实验室进行放射性次级束流操控的必备实验装置。在中国科学院近代物理研究所，一台正在研制的专用于研究长寿命核素的超重核研究谱仪中就使用了RFQ冷却聚束器来冷却、约束和储存离子。论文首先简单介绍了近代物理研究所超重谱仪的情况和国际上RFQ冷却聚束器的研究情况，其次阐述了RFQ冷却聚束器相关原理，然后重点论述了用SIMION程序进行模拟的方法和对RFQ1L冷却段的模拟情况，并对模拟结果进行了讨论，接着，讨论了计算机无法模拟的一些因素，重点讨论了气体击穿问题，最后，对本论文的工作进行了总结，并对下一步工作进行了展望望。对RFQ1L冷却段的模拟和气体击穿问题是本论文的两个重点。冷却段的模拟是以为例进行的。通过改变缓冲气体压强、入射离子能量以及轴向电场梯度，得到了离子在RFQ冷却聚束器中不同的运动情况，得到了一些有意义的结论，有助于设备的设计和工作点的选择。另外，RFQ冷却聚束器的工作区域，正好位于缓冲气体最容易被击穿的范围，再加上射频的影响，因此气体击穿问题成为制约工作点选择的一个非常重要的因素。本文对此也作了详细的讨论

RFQ冷却聚束器RFQ1L的研制

SHANS (Spectrometer of Heavy Atoms and Nuclear Structure，重原子和核结构研究谱议)正在建设中，它不但可以直接鉴别离子的电荷数Z和质量数A，而且还将在核结构和核衰变的精细研究方面发挥重要作用。RFQ冷却聚束器RFQ1L和彭宁离子阱LPT是其中的两个重要组成部分。 RFQ冷却聚束器RFQ1L的主要目的是收集经过充气反冲谱议分离后的反应产物，然后经过冷却、聚束，使原来品质很差的束流转化为能量单一、发射度小、束斑很小的高品质束流。现在已经顺利完成了模拟、设计、机械加工和机械安装等工作，其中机械安装部分是本论文的主要工作之一。经过近半年的时间，我们克服了种种困难，高质量地完成了RFQ1L的机械安装工作。各种测量综合显示：各部件间的位置精度达到了±0.5 mm；真空系统的真空度达到了1.7×10-4 Pa，系统压升率为(0.04±0.02) Pa/h；各电极间的绝缘效果和导电效果良好。彭宁离子阱LPT的主要目的是直接高精度测量原子核的质量。质量是原子核的一个最基本属性，对检验和拓广现有核理论、研究核天体物理中的核反应过程和基本常数具有非常重要的作用。控制系统在LPT中起着至关重要的作用。控制系统的设计和实现也是本论文的另一个主要工作。本论文详细论述了LPT的控制系统LPTCtrlSys的基本要求、硬件和软件布局情况

dd→αK+K-反应截面在ANKE/COSY上的测量

ANKE谱仪是位于冷却储存环COSY上的一个内靶实验终端，在它的针对物理目标中，研究靠近 产生阈的共振态a0(980)/f0(980)是一个主要的内容。在通过强相互作用反应对a0/f0进行测量时，初态会选择使用不同的同位旋组合，也就是使用pp、 pn、pd和dd反应。本实验完成于2006年的4、5月间，是一个使用COSY所能提供的最大束流动能Td = 2.273 GeV的dd道反应，它比 产生阈高Q = 39 MeV。在实验中探测了αK+符合事件，结合使用丢失质量分析方法就可以对反应链dd → αf0 → αK+K- 以及其中的f0(980)共振态进行研究。 作为本文的主要内容这个实验，是在Monte - Carlo模拟的帮助下准备后，在4个星期的束流时间里完成的。在实验完成后，数据分析主要集中在对稀有的αK+事件进行鉴别。 ANKE的射程望远镜阵列针对K+介子的鉴别做过优化，在它的帮助下K+就可以通过飞行时间、能量损失方法，以及探测延迟发射的K+衰变产物而被挑选出来。而与之关联的α粒子则是通过它们相对于K+介子的定时点进行鉴别的，α和K+的动量及轨迹由在相应多丝正比室上测量到的径迹信息重建。由此，就可以通过使用丢失质量方法鉴别出实验中没有测量的K-介子。最终所得的αK+丢失质量谱在K-介子质量区域内呈现一个峰，其中包含大约15个事件。由这些αK+K-事件可以得到总的反应截面σtot = (9 ± 3sta ± 5sys) pb。 同位旋破缺反应dd → α(π0η) 的截面由测量得到的σtot (dd → αK+K-)值推出，进而它也给出了在WASA-at-COSY上观察这个过程所要求的最短束流时间。因为这个反应被认为主要是源于通过KK中间态的f0 → a0转化，所以它对于确定出轻标量介子a0(980)/f0(980)的结构扮演着格外重要的角色

超重谱仪充气段及其初步调试

论文介绍了超重充气谱仪的基本原理及此类装置的国际现状，在此基础上，对中国科学院近代物理研究所超重谱仪充气段的基本情况进行了描述。本工作采用离线和在线的方法对超重谱仪充气段进行了调试。在离线实验中，通过改变α源及探测装置的位置，确定了谱仪的接收度，得到了谱仪对不同能量及发散度的α粒子的传输效率，测试了充气对谱仪传输效率的影响，并对靶厚与传输效率间的关系进行了模拟研究。根据离线实验的结果，对谱仪进行了合理的改进。在线实验利用重离子束流轰击薄靶并观测靶反冲核的方法，确认了束流监测装置的最佳探测器和最佳安装位置，测试了谱仪对一些靶反冲核的传输效率。通过初步调试，测试了该超重谱仪充气段的一些基本性能，测量了谱仪的一些相关参数，为其投入今后的物理实验研究提供了必要的经验和参考