Development of multi-channel gated integrator and PXI-DAQ system for nuclear detector arrays

A multi-channel gated integrator and PXI based data acquisition system have been developed for nuclear detector arrays with hundreds of detector units. The multi-channel gated integrator can be controlled by a programmable Cl controller. The PXI-DAQ system consists of NI PXI-1033 chassis with several PXI-DAQ cards. The system software has a user-friendly GUI which is written in C language using LabWindows/CVI under Windows XP operating system. The performance of the PXI-DAQ system is very reliable and capable of handling event rate up to 40 kHz. (C) 2010 Elsevier B.V. All rights reserved.

Gas-phase isothermal chromatography with short-lived technetium isotopes

In order to study the gas-phase chemical behavior of transactinides, an on-line isothermal chromatography apparatus has been developed and applied to separate short-lived technetium isotopes in the form of TcO3 from fission products. The fission products from a Cf-252 source were continuously and rapidly transported through the capillary to the isothermal chromatography apparatus using the N-2/KBr gas-jet techniques. Volatile oxide molecules were formed at the reaction zone kept at 900 degrees C since a trace amount of oxygen existed in the N-2 carrier gas. With the new developed isothermal chromatography apparatus, a selective separation of Tc from fission products was achieved. After isothermal chromatographic separation, Tc-101,Tc-103,Tc-104,Tc-105,Tc-106,Tc-107,Tc-108 were dominantly observed together with their Ru daughters in the gamma-spectrum, The chemical yields of Tc-101, and Tc-104 and Tc-105 isotopes with longer half-lives are about 55-57%, and those of Tc-103, Tc-106 and Tc-108 isotopes with shorter half-lives dropped down to 25-28%. The adsorption enthalpy of the investigated compounds on quartz surfaces was determined to be -150 +/- 5 kJ/mol by fitting the measured retention curves with a Monte Carlo model. The observed species of technetium oxide is attributed to TcO3, which is in good agreement with previous experimental results. That means our system worked properly and it can be used to investigate the gas-phase chemical behavior of transactinides.

Structural stability of C-60 films under the bombardment of 1.95 GeV Kr ions

The structural stability of C-60 films under the bombardment of 1.95 GeV Kr ions is investigated. The irradiated C-60 films were analyzed by Fourier Transform Infrared (FTIR) spectroscopy and Raman scattering technique. The analytical results indicate that the irradiation induced a decrease of icosahedral symmetry of C-60 molecule and damage of C-60 films; different vibration modes of C-60 molecule have different irradiation sensitivities; the mean efficient damage radius obtained from experimental data is about 1.47 nm, which is in good agreement with thermal spike model prediction.

缺中子核素133Sm、133Pr和93Pd的衰变

本硕士沦文籍助兰州重离子加速器国家实验室分离扇聚焦回旋加速器（SFC）提供的重离子束通过全融合蒸发反应产生远离口稳定线的缺中子核素，并用本课题组发展和建立的氦喷嘴快速带传输系统以及多重符合测量装置分离、测量核素来研究其衰变性质。在实验准备期间，曾采用~(252)Cf���进行了氦喷嘴（I－I eje咧央速带传输系统效率的测定。给出了PbI_2，PbCl_2，NaCl三种无机欲添加剂的传输效率，以及传输效率随目标核质量变化的初步结果。而后完成了以下两项物理实验：~(113)Sm的（EC＋β~+）衰变纲图和133Pr的同核异能态的研究：用SFC引出的~(40)Ca~(12+)束流轰击96%Ru的浓缩同位素靶，采用氦喷嘴带传输系统和x-γ与γ-γ符合测量方法，首次建议了~(133)Sm的简单的（EC＋β~+）衰变纲图并测得了其β衰变半衰期。~(133)Sm是目前发表过（EC＋β~+）衰变纲图的最轻的钐（Sm的缺中子核。由于Ru靶中含有~(98-102)Ru的成分，同时产生了~(133)Pr，并首次测定了~(133)Pr 11／2~－同核异能态的寿命为（l.1±0.2）s。为Pr奇A核11／2~-同核异能态的数据作了重要的补充，汇编成Pr奇A核的11／2一同核异能态和与之相关的3／2~＋，5／2~+和7／2~+能级的系统性数据。用单粒子模型理论拟合从中提取了~(131,133,135,137)Pr的11／2~-同核异能态的约化跃迁概率的实验值，并与Weisskopf近似估计进行了比较。2.~(93)Pd的β缓发质子衰变：通过~(58)Ni（~(40)Ca，3n2p）反应合成β缓发质了先驱核~(93)Pd，采用氦喷嘴带传输系统加p-γ符合观测到了它的β缓发质子衰李，测得其半衰期为1.3±0.2s。采用统计模型计算拟合了实验测得的口缓发质子能谱和布居到质子发射体子核不同终态的分支比，首次由实验数据出发初步指认了93Pd的基态自旋-宇称为9／2~±。同时与采用Woods-Saxon Strutinsky方法计算~(93)Pd的核位能面得到的结果进行了比较。计算结果支持对~(93)Pd基态自旋一宇称为9／2~+的实验指认。

位置灵敏塑料闪烁探测器阵列

我们研制了一个用于测量重离子核反应中轻带电粒子的位置灵敏塑料闪烁探测器阵列，该阵列由六块100 * 10 * 1 cm~3和两块100 * 5 * 1 cm~3的Pilot U型塑料闪烁体组成，所用光电管为XP2020Q型。本文详细地讨论了影响探测器的分辨做了测量，~(252)cf���位于探测器中心时，得到两种宽度探测器的时间分辨为740ps和610ps，相应的位置分辨为5.7cm和4.6cm，探测器中心位置能量分辨为60%和40%。还使用JUHU数据获取系统对探测器进行了测试。给出了由能量确定的位置分辨。最后还讨论了探测器阵列的适用能区和粒子鉴别能力以及今后改进的设想

位置灵敏塑料闪烁探测器阵列

本论文研制了一个二维位置灵敏塑料闪烁探测器阵列，该阵列由六块100 * 10 * 1 cm~3和两块100 * 5 * 1 cm~3的Pilot U型塑料闪烁体组成，所用光电管为xp2020Q型。本探测器阵列将用于重离子反应中的轻粒子角分布和飞行时间测量。本文对该种闪烁体及对应的光导中的荧光传输进行了理论计算，并用~(90)Sr-~(90)Y β源和~(252)Cf α源进行了性能测试。用~(252)Cf���的α粒子测得10cm宽的探测器的时间分辨、位置分辨和能量分辨分别为740ps、6cm和60％；测得5cm宽的探测器的分辨分别为600ps、5cm和40％。本文还介绍了用本所的MODAS-1数据获取系统对阵列进行联合测试的方法和结果，对粒子鉴别和多重性测量也进行了讨论

在线He-喷嘴β-反冲飞行时间质谱仪的研制

本论文阐明了He-喷嘴反冲传输系统设计及其机制，并将它用于β-反冲飞行时间测量中构成-名在线He-喷嘴β-反冲飞行时间质谱仪装置。该装置对于探索高温难熔金属元素，鉴别其质量具有潜在的能力，预计在对远离β稳定线核素的探索及其质量数的鉴别中发挥作用。通过离线实验测定了0.189μg ~(252)Cf���的自发型裂变碎片的传输特征，得到了各种情况下装置运行的最佳参数，同时利用该装置在线测定了0.135 + 0.189 μg ~(252)Cf���裂变碎片的飞行时间谱。质量数为100左右的核素很好地分开，并给出了实验结果及其讨论。最后在附录中提出了提高谱仪性能的改进建议

八单元一维位置灵敏雪崩室

In the experiment of nuclear reaction, it is important to measure the mass, charge, energy and emitted direction of particles. For multiparameter measurement, we must use a detector or a group of detectors which can give the time, energy, and position information. The Large Area position sensitive Ionization Chamber(LAIC) is one of the eight experiment terminals of HIRFL. It is built for researching nuclear reactions from low energy to intermediate energy. It is an excellent equipment for energy measurements and atomic number identification of emitted fragments in this energy region. It is also designed to give the time and position information of the emitted fragments by itself. Obviously, an IC can not supply a good timing signal. Moreover, the mechanical installation is different from the original design by some other reasons. In this case, it is not enough to obtain the correct direction information of the emitted fragments. To obtain good timing signals and the correct direction information, some modifications must be made. It is well known that a PPAC can give us excellent timing signals. It also can be easily built as a position sensitive detector. For this reason, a specially designed PPAC is installed in the entrance of the LAIC. For the different purposes, two types of PPACs were designed and tested. Both are OCTPSACs (OCTunit one dimension Position Sensitive Avalanche Counter). In this paper, both OCTPSACs will be introduced. Based on the requirements of the LAIC, the OCTPSACs consist of eight position sensitive PPACs. Each PPAC has an anode and a cathode. In both cases, the sizes are same. But different type of cathodes are used. In one type of OCTPSAC, its cathode is made of wire plane. It consists of gold-plated tungsten wires with the diameter of 20μm, spaced 0.5 mm apart from each other. The anode is a mylar foil which was evaporated by gold layer with the thickness of 50μg/cm~2 mounted on a printed plate in the shape of rectangle. the thickness of mylar foil is 1.5μm. The gap between anode and cathode is 3mm. The performance of the OCTPSAC has been tested by using a ~(252)Cf source in flowing isobutylene gas at the pressure of 3.4mb. The intrinsic time resolution of 289ps and position resolution of 2 mm have been obtained. In another type of OCTPSAC, the cathode is made of mylar foil, which is composed of gold strip by vacuume evaporation method with a special mask on the mylar foil. The thickness and the width of the gold strip is 50μg/cm~2 and 1.7mm. The strips are spaced 0.3 mm apart from each other. The anode is the same as the former type. We have obtained the time resolution of 296ps and position resolution of 2mm by using ~(241)Am-a source when the gas pressure is 6 mb and high voltage is 600V. The working gas is heptane

Geometries of the Halocarbene anions HCF- and CF2-: ab initio calculation and Franck-Condon analysis

A theoretical method to calculate multidimensional Franck-Condon factors including Duschinsky effects is described and used to simulate the photoelectron spectra of HCF- and CF2- radicals. Geometry optimization and harmonic vibrational frequency calculations have been performed on the (X) over tilde (1)A' state of HCF and (X) over tilde (2)A" state of HCF-, and (X) over tilde (1)A(1) state of CF2 and (X) over tilde B-2(1) state of CF2-. Franck-Condon analyses and spectral simulation were carried out on the first photoelectron band of HCF- and CF2- respectively. The theoretical spectra obtained by employing B3LYP/6-311 + G(2d,p) values are in excellent agreement with the observed ones. In addition, the equilibrium geometry parameters, R(CF) = 0.1475 +/- 0.0005 nm, of the (X) over tilde (2)A" state of HCF-, and r(FC) = 0.1425 +/- 0.0005 nm and angle(FCF) = 100.5 +/- 0.5degrees, of the (X) over tilde B-2(i) state of CF2-, are derived by employing an iterative Franck-Condon analysis procedure in the spectral simulation. (C) 2003 Elsevier B.V. All rights reserved.

低温弱光下类囊体腔内质子由CF_0渗漏引起黄瓜类囊体耦联度降低

毫秒延迟发光测定结果表明低温弱光处理黄瓜叶片导致类囊体原位 (in situ)耦联度显著降低。DCCD可以恢复低温弱光处理的黄瓜叶片的毫秒延迟发光的慢相强度和反映类囊体膜质子吸收的 9- AA(9- Aminoacridine)荧光猝灭能力 ,说明类囊体耦联度降低的原因是质子由 CF0 大量快速渗漏。进一步研究结果表明 ,活性氧和 CF1的脱落不是低温弱光引起黄瓜类囊体耦联度降低的根本原因。

马铁菊头蝠不同状态下回声定位声波分析

在自建网室(9 m×4 m×4 m)内驯养马铁菊头蝠(Rhinolophus ferrumequinum),利用超声波探测仪录制蝙蝠不同状态下回声定位声波,声波录制与红外摄像保持同步。结果表明,马铁菊头蝠回声定位声波为调频(FM)/恒频(CF)/调频(FM)型;在蝙蝠接近猎物过程中,声脉冲持续时间和间隔时间显著变短,下调FM(即tFM)组分变得愈为显著,捕捉猎物瞬间,产生捕食蜂鸣;飞行与悬挂状态相比,声脉冲重复率、主频率、声脉冲时间、声脉冲间隔和能率环的差异均达到显著水平。

Two novel molybdenum complexes containing [Mo2O2S2](2+) fragment: synthesis, crystal structures and catalytic studies

Mo2O2S2(HGly)(GlY)(2) 1 and K-6[Mo2O2S2(nta)(2)][Mo2O2S2(ntaH)(2)]center dot 4H(2)O 2 were synthesized by the reactions of (NH4)(2)MoS4 and amino acids L (L = glycine, nitrilotriacetic acid) in ethanol-water medium at ambient temperature. The two complexes were characterized by elemental analysis, infrared spectra, UV-visible spectra, TG-DTA and XPS.