A high performance Time-of-Flight detector applied to isochronous mass measurement at CSRe

A high performance Time-of-Flight detector has been designed and constructed for isochronous mass spectrometry at the experimental Cooler Storage Ring (CSRe) The detector has been successfully used in an experiment to measure the masses of the N approximate to Z approximate to 33 nuclides near the proton drip-line Of particular interest is the mass of As-65 A maximum detection efficiency of 70% and a time resolution of 118 +/- 8 Ps (FWHM) have been achieved in the experiment The dependence of detection efficiency and signal average pulse height (APH) on atomic number Z has been studied The potential of APH for Z identification has been discussed (C) 2010 Elsevier B V All rights reserved

8×8单元CsI(Tl)探测阵列研制；Development of 88 CsI(Tl) array detector

描述了1个8×8单元CsI(Tl)探测阵列的结构和工作原理。探测阵列的每个单元是由1块前表面21 mm×21 mm、后表面23.1 mm×23.1 mm、高50 mm的CsI(Tl)棱台、1块光导和光电倍增管组成。在兰州放射性次级束流线(RIBLL)上对探测阵列进行测试,得到探测阵列对30 MeV质子的能量分辨可达2.7%,对170 MeV7Be可达1.5%,可很好地用于放射性束物理实验中带电粒子的鉴别。

64通道一维位置灵敏电流分布探测器及其数据获取系统；A 64-Channel Position Sensitive Current Distribution Detector with Data Acquisition System

针对高流强粒子束与绝缘毛细管相互作用的特点,设计制作了一套64通道一维位置灵敏电流分布探测器及其配套的数据获取系统,该探测器可分辨最小直径为1mm的束斑,通过数据获取系统可实现可视化自动数据采集。用2nA和200—2000eV电子对探测器进行了定标,并用10μA和2000eV的电子束穿越锥形毛细管后的出射电子,对探测器及数据获取系统进行测试,获得了出射粒子的位置分布谱及能量信息。

A TOF-PET prototype with position sensitive PMT readout

A prototype of time-of-flight positron emission computed tomography (TOF-PET) has been developed for acquiring the coincident detection of 511 keV gamma-rays produced from positron annihilation. It consists of two 80.5 mmx80.5 mm LYSO scintillator arrays (composed of 35 x35 pixel finger crystals) with the position sensitive photomultiplier tubes R2487 as the readout. Each array is composed of 2 mm x2 mm x 15 mm finger crystals and the average pixel pitch is 2.30 mm. The measured results indicate that the TOF information has the potential to significantly enhance the image quality by improving the noise variance in the image reconstruction. The best spatial resolution (FWHM) of the prototype for the pairs of 511 keV gamma-rays is 1.98 mm and 2.16 mm in the x and y directions, respectively, which are smaller than the average pixel pitch of 2.30 mm.

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.

Investigation of add-back effects in a segmented Clover detector

The resolution and the summing characteristics of an EXOGAM segmented Clover germanium detector has been studied for use it in gamma spectroscopic experiments. The measurements have been performed with standard radioactive sources of Eu-152, Ba-133 and beta-delayed gamma-rays from Ir-176 decay. The data analytic results, realized by software, are presented in this paper.

Investigation of the energy resolution with a RETGEM detector

A novel Micro-pattern gaseous detector (MPGD), thick GEM with electrodes made of a resistive material (RETGEM) is presented. In this paper we mainly investigate the energy resolution of a RETGEM in Ar+CO2 with different gas mixtures. The results indicate that an energy resolution 30% in single and double mode can be obtained. The existence of an optimum energy resolution is discussed.

Study on shunt impedance and voltage distribution of 4-rod RFQ cavity

A high current RFQ (radio frequency quadrupole) is being studied at the Institute of Modern Physics, CAS for the direct plasma injection scheme. Shunt impedance is air important parameter when designing a 4-rod RFQ cavity, it reflects the RF efficiency of the cavity, and has a direct influence on the cost of the structure. Voltage distribution of a RFQ cavity has an effect on beam transmission, and particles would be lost if the actual voltage distribution is not as what, it should be. The influence of cell length, stern thickness and height on Shunt impedance and voltage distribution have been studied, in particular the effect of projecting electrodes has been investigated in detail.

高性能小型带电粒子探测阵列的研制

随着核物理理论研究和各种先进探测设备研制工作的不断深入,世界各大实验室相继建立了各具特色的放射性束装置,放射性束物理得到了长足的发展。在放射性束引起的核反应实验上,要得到更加精确的非稳定原子核的结构信息和反应机制，需要对反应产物实现完全运动学测量,这就要求位置分辨和能量分辨更精确的探测器装置。高性能小型带电粒子探测阵列是基于△E-E粒子鉴别方法,采用位置分辨精确的双面硅微条作为△E探测器,用阻止本领大的BGO晶体阵列作为E探测器,来测量反应产物的能量分辨和角分布,从而进行带电粒子的鉴别。 Geant4是由欧洲核子中心(CERN)开发的一个大型高能物理探测器模拟程序，是采用当代先进的面向对象程序设计技术利用C++语言编写的。我们基于该模拟工具,对探测器分辨随能量的变化情况、粒子斜入射对探测器分辨的影响情况、晶体厚度变化对分辨的影响情况以及与阻止相同能量的CsI晶体分辨情况等进行了一系列的模拟对照。 本论文工作的主要内容有:首先,介绍了探测器的研制及测试过程。该探测器用一块双面硅微条作为△E探测器,用64块BGO晶体阵列作E探测器。晶体阵列采用一块64单元位置灵敏的光倍管读出信号。该探测器具有体积小，死区小,位置分辨好等优点。其次,根据探测器在实验中可能遇到的问题,我们利用Geant4系统的模拟了晶体尺寸变化对分辨的影响情况；晶体分辨随能量升高的变化情况及粒子斜入射对晶体分辨造成的影响等，从而为探测器选用合适尺寸的晶体提供了很好的参考。模拟结果显示，晶体分辨随着能量升高而变好,这为选用BGO晶体作为带电粒子探测阵列提供了很好的参考；粒子斜入射会对分辨造成一定的影响，并从三维图上显示了粒子的踪迹，这为今后实验数据处理提供了很好的参考；与CsI晶体位置分辨和能量分辨作了对照模拟，模拟结果显示，随着带电粒子能量的增加BGO分辨逐渐与CsI晶体接近，并且角分辨会比CsI晶体好，从而得出BGO晶体用来作带电粒子探测阵列的独特优势。最后，针对以后的工作方向作了简单的讨论

A miniaturized fluorescence detector with a windowless flow cell using a light-emitting diode

A miniaturized fluorescence detector using a high-brightness light-emitting diode as an excitation source was constructed and evaluated. A windowless flow cell based on a commercial four-port cross fitting was designed to reduce the stray-light level and to eliminate the optical alignment. The observed detection limit for fluorescein was 26 nM in the continuous-flow mode. The error in the reproducibility of the responses was evaluated by the FIA method, and was found to be within 2% RSD.

Light-emitting-diode-induced fluorescence detector for capillary electrophoresis using optical fiber with spherical end

A simple fluorescence detector for capillary electrophoresis (CE) using a blue light-emitting-diode (LED) as excitation source is constructed and evaluated. An optical fiber was used to collect the fluorescence, and a flat end of the fiber was modified to spherical end, resulting in 50% increase of efficiency over the flat end. A simple device for optical alignment of the fibers and capillary column was designed. The concentration and mass detection limits for fluorescein were 1.8 x 10(-7) Mol l(-1) and 4.3 femol, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.

Determination of sulfur-containing compounds in diesel oils by comprehensive two-dimensional gas chromatography with a sulfur chemiluminescence detector

This article reports an analytical method for separating, identifying and quantitating sulfur-containing compounds and their groups in diesel oils (170-400degreesC) using comprehensive two-dimensional gas chromatography coupled with a sulfur chemiluminescence detector. The identification of target compounds and their groups was based on standard substances, the group separation feature and the-effect of comprehensive two-dimensional gas chromatography. The quantitative analysis on major sulfur compounds and total sulfur was carried out based on the linear response of sulfur chemiluminescence detector and the internal standards method. The results of total sulfur determination in the samples were compared with those from ASTM D 4294 standard method, the R.S.D. percentage were <6.02%, correctness of this method can meet the industrial requirement. To the end, the method developed was used to investigate the sulfur-containing compounds in different diesel oils, the result shows that the distribution of sulfur-containing compounds in diesel oils from different process units are apparently different. The sulfur compounds in fluid catalytic cracking (FCC), residuum fluid catalytic cracking (RFCC) diesel oils mainly exist in the form of alkyl-substituted dibenzothiophenes that add up to about 40-50% of the total sulfur, while this number is only 6-8 and 20-28% in visbreaking (VB) and delayed-coking (DC) diesel oils, respectively. (C) 2003 Elsevier B.V. All rights reserved.

Research and compilation of the Geomorphologic Atlas of the People's Republic of China (1:1,000,000)

National Natural Science Foundation of China [40871177, 40830529]