用于加速器质谱测量的Bragg探测器

文章涉及1台用于加速器质谱(AMS)测量的Bragg探测器的建立及其调试结果。该探测器是1台全阻止型的气体电离室,电场方向与入射粒子方向平行。用241Am源的α粒子对该探测器的主要性能进行了测试,并将该探测器用于AMS实验进行总能量测量和Z的鉴别。对于能量为49.7 MeV的26Mg离子,能量分辨达到1.4%,Bragg峰值的分辨好于4.1%。     

薄窗型多阳极气体探测器研究进展

薄窗型气体探测器是最近发展并用于低能量加速器质谱探测技术。该探测器的入射窗采用氮化硅膜,薄而均匀,分辨率高,目前已在低能量粒子探测技术中得到初步应用,显示出广泛的应用前景。本文主要从薄窗型气体探测器基本原理、薄氮化硅膜与Mylar膜的对比、不同质子数Z的低能量粒子脉冲高度对比、薄窗型气体探测器与硅探测器的对比,以及应用等方面进行阐述。     

薄窗型多阳极气体探测器研究进展

薄窗型气体探测器是最近发展并用于低能量加速器质谱探测技术。该探测器的入射窗采用氮化硅膜,薄而均匀,分辨率高,目前已在低能量粒子探测技术中得到初步应用,显示出广泛的应用前景。本文主要从薄窗型气体探测器基本原理、薄氮化硅膜与Mylar膜的对比、不同质子数Z的低能量粒子脉冲高度对比、薄窗型气体探测器与硅探测器的对比,以及应用等方面进行阐述。     

重离子单粒子效应实验研究

在HI—l3串列加速器上建立了对微电子器件进行单粒子效应模拟实验的辐照和检测技术。利用该Q3D磁谱仪获得种类和能量单一、强度分布均匀且足够弱的重离子辐照源，利用散射室内的半导体探测器和焦面上的位置灵敏半导体探测器监测辐照离子。用该装置和技术测量了在8个传能线密度(LET)值的重离子辐照下引起的几个存储器器件的单粒子翻转（SEI）截面o(L)。从测得的o(L)——LET曲线，结合空间重离子和质子辐照环境模型以及离子与微电子器件相互作用模型计算，预言了器件在空间的单粒子翻转率。     

低能重离子薄窗型气体电离室的设计

正为建立低能重核素加速器质谱测量技术,需研发薄窗型气体电离室。对于传统的气体电离室,一般采用Mylar膜,但其厚度需在1μm左右,但低能重核素在这种膜中会损失很大能量(SRIM模拟1.2 MeV的~(129)I穿不过1μm的Mylar膜,如图1所示),导致电离室无法测量低能重离子。为解决这个问题,30nm厚的Si_3N_4膜作为探测器的入射窗,SRIM模拟显示1.2 MeV的~(129)I在30nm厚的Si_3N_4窗中损失的能量为0.113 MeV,满足低能重核素测量要求。在此基础上,开展了低能重核素探测器的设计和建造,结构如图2所示,     

中重离子焦面探测器系统的改进

经改进的中重离子焦面探测器系统(长500mm),已通过束流检验并用于核物理实验 中。在串列加速器上,以66 MeV~(12)C束流,测得剩余能量E探测器的能量分辨约为7％,另外还进行了粒子鉴别试验。     

中重离子焦面探测器系统的改进

经改进的中重离子焦面探测器系统(长500mm),已通过束流检验并用于核物理实验中。在串列加速器上,以66MeV~(12)C束流,测得剩余能量E探测器的能量分辨约为7％,另外还进行了粒子鉴别试验。     

一维位置灵敏塑料闪烁探测器的测试

随着兰州重离子加速器HIRFL的建成出束,一批实验终端也已经建成并投入使用。大面积位置灵敏电离室终端是其中之一,它包括一个80cm,一个140cm的电离室。电离室具有较大的立体角,可以测量低能粒子的能量及空间位置,可鉴别粒子电荷,如配以时间测量,还可鉴别粒子质量。但气体电离室质量厚度不大,对轻粒子阻止本领低,所以在电离室后面加上较厚的塑料闪烁探测器,以满足中能物理实验的需要,可以测量出射粒子和碎片的能量,并能鉴别粒子种类,同时还可以得出粒子的位置、多重性等信息,有利于进行符合测量。     

静态随机存取存储器重离子单粒子翻转效应实验研究

应用重离子加速器和 2 52 Cf源进行单粒子翻转效应实验 ,测量得到 IDT系列和 HM系列静态随机存取存储器的单粒子翻转重离子 L ET阈值为 4～ 8Me V· cm2 /mg,单粒子翻转饱和截面为 10 -7cm2 · bit-1量级 ,位单粒子翻转截面随集成度的提高而减小。实验结果表明 ,可以用 2 52 Cf源替代重离子加速器测量静态随机存取存储器的单粒子翻转饱和截面     

加速器质谱(AMS)测量中的粒子鉴别探测器

描述了中国原子能科学研究院AMS测量中使用的飞行时间探测器、多阳极电离室、Bragg探测器、入射离子X射线探测器以及充气飞行时间探测器。通过它们可以获得粒子的飞行时间、部分能量和总能量,从而达到粒子鉴别的目的。介绍了采用这些探测器在HI—13串列AMS系统上做的相关工作以及取得成果。     

Annular gas ionization detector for low energy heavy ion backscattering spectrometry

A gas ionization chamber for use in backscattering spectrometry has been built. It has the shape of a hollow cylinder and can be placed in-line with the incident ion beam. The entrance window for detected particles is composed of a circular array of silicon nitride membranes. A low noise preamplifier with cooled FET is used for charge amplification. The detector resolution has been measured for a variety of ions in the mass range from He to Si and for energies between 0.5 and 8 MeV. The energy resolution of the ionization chamber surpasses the one of a state-of-the-art silicon charged particle detector for all ions heavier than Li. For Si ions the improvement in resolution is more than a factor of 2. The device does not suffer from any radiation damage. For He particles around 1 MeV the resolution is between 13 and 16 keV (FWHM). Therefore the new detector is not only well suited for heavy ion backscattering spectrometry but can also be applied for standard He RBS, allowing the use of a single detector for all types of projectiles in a wide energy range.     

Improvement of Bragg Curve Detector Using in CIAE-AMS

Isobar identification method is the most important factor for the high-resolution and high-accuracy measurement in the AMS technology. The Bragg detector has the relatively high energy resolution, so the Bragg detector used for AMS measurement can improve the isobar identification, especially for the medial heavy radioisotopes. This can supply the important method for the medial heavy radioisotopes AMS measurement. We re-tested and improved the electronic signal obtaining way systemically,     

Improved 10Be and 26Al-AMS with a 5 MV spectrometer

Detector and ion source changes have increased Be and Al count rates and reduced measurement background at SUERC. Low energy 16 MeV ²⁶Al³⁺ ions can be separated from interferences by adopting thin silicon nitride membrane detector windows. In contrast, a thick Havar detector window is used to preferentially slow boron ions for simplified ¹⁰Be vs. ¹⁰B separation without an additional gas cell.     

The development of a time of flight spectrometer for LARN

An elastic recoil detection time of flight system to depth profile light elements has been developed on ALTAÏS, the new Tandetron accelerator at LARN. The detector mounted at 45° from the beam axis consists of two isochronous electron detectors for the timing signal (START and STOP) and a 450 mm² heavy ion PIPS detector that detects the energy of the recoil atoms. The 2MV Tandem accelerator provides heavy ion beams with a maximum energy of 16 MeV depending on the charge transfer efficiency of the gas exchange canal located in the middle of the machine. A large variety of primary ion beams like ²⁸Si, ³⁵Cl, ⁶³Cu, ¹²⁷I or ¹⁹⁷Au can be produced with the SINIX heavy ion source and accelerated on the target. Typical current around 1 nA can be obtained. The energy transfer to the recoil atoms is typically in the MeV range and depends on the mass and the energy of the projectile. Some secondary effects like the energy loss in the carbon foils of the timing detector but also in the entrance window of the energy detector should not be neglected if we try to depth profile light elements with this technique. Time resolution of about 1 ns for the electrons detectors is suitable to obtain 1 amu mass resolution. Some examples of applications will be developed in this paper.     

空间单粒子翻转甄别与定位系统原理样机的设计及试验

单粒子翻转（SEU）是影响空间电子设备可靠性的重要因素,本文提出了一种SEU甄别与定位技术方法,研制了原理样机。硅探测器与辐照敏感器件在垂直方向相互临近安装,粒子入射到硅探测器的位置区域与目标辐照器件单粒子翻转的物理位置相对应。采用波形数字化技术实现了多道粒子甄别与能量信号测量,通过数据回读比较法实现了SRAM器件翻转逻辑定位检测。根据实验室测试和单粒子辐照试验结果,可探测高能粒子的LET≥6?06×10-3 MeV·cm2/mg,入射粒子的位置分辨率优于5 mm,最大计数率≥10 000 s-1,SRAM器件的SEU巡检周期时间分辨率为13?76 ms。通过掌握大容量SRAM型器件的SEU甄别与定位及其辐射环境感知能力,有助于提升空间电子设备的在轨工作性能。     

Test of Silicon Strip Detector for Heavy Ion Nuclear Reaction

Nowdays, the silicon strip detectors play an important roles in nuclear experiment. Not only the particle position signal can be supplied, but also the energy signal can be given. However, how to use the silicon strip detector in heavy ion nuclear reaction is different from the usual experiment, so it is necessary to test the silicon strip detector.     

WDX-PIXE analysis of low energy X-rays using a microbeam

A high-energy resolution PIXE system developed at a heavy ion microbeam line was used to analyze low energy X-rays below 1 keV. The system is equipped with a plane crystal spectrometer with a gas flow position sensitive proportional counter (PSPC), which enables high-energy resolution PIXE analysis using a microbeam. In order to improve the detection efficiency for the low energy X-rays, the X-ray entrance window of the PSPC was replaced with a thin polymer film supported by a metal grid. As the result, the detectable energy range was extended to carbon K X-rays and chemical effect in Fe and Cu L X-rays could be detected. A preliminary result of high-energy resolution PIXE mapping of Cu mesh (#500) showed that it is possible to obtain the Cu L mapping image using a 2 MeV proton microbeam with the size of 20 × 20 μm.     

The precise determination by NRA of the relative stoichiometry of silicon nitride thin films on heavy substrates

A method has been developed for measuring the relative stoichiometry of silicon nitride films less than 3000 Å thick on heavy substrates. By using (d, p) reactions and a single particle detector, a precision of ± 2% in the relative stoichiometry can be obtained without standards, charge integration or knowledge of the detector solid angle. Measurement of the absolute stoichiometry is dependent on the availability of a suitable standard. An application of this method to a study of the properties of magnetron sputtered Si₃N₄ thin films on GaAs is described.     

用于CSNS反角白光中子源的双屏栅电离室设计及性能研究

为测量中国散裂中子源（China Spallation Neutron Source, CSNS）反角白光中子源150 keV以下能区飞行时间法中子能谱,研制基于¹⁰B(n, α)⁷Li和⁶Li(n, t)α核反应的双屏栅电离室,采用薄窗和薄底衬的结构设计。通过Garfield++、SRIM和Simcenter Magnet Electric程序对屏栅电离室的工作气体、极间距和电场分布等工作参数进行模拟设计,并采用α源及CF₄、P10、90%Ar-10%CO₂三种气体对电离室进行性能参数测试。结果表明,选定电子漂移速度快、扩散系数小,以及阻止本领大的CF4作为CSNS/Back-n束上测试工作气体,阴极-栅极和栅极-阳极间距分别为20 mm和5 mm。屏栅电离室收集区74 mm范围内是电场均匀区,场强的相对偏差≤0.03%;性能测试结果表明,工作气体为CF₄时,电离室对²³⁹Pu/²⁴¹Am/²⁴⁴Cm混合α面源具有很好的能量分辨,最佳能量分辨率为2.4%@5.48 MeV。对比平板型电离室和硅微条探测器的测量结果,验证了本工作研制的屏栅型电离室的能量分辨优势。