Characteristics of position sensitive detector pixels based on promising inorganic scintillators LaBr3:Ce and CeBr3

The energy resolution of different-geometry LaBr₃:Ce and CeBr₃ scintillation crystals grown by the Institute of Solid State Physics (Russian Academy of Sciences) by the order of the Skobel’tsyn Institute of Nuclear Physics (Moscow State University) was measured. The measurements were taken at energies of detected γ rays ranging from 20 keV to ～5 MeV. The samples under investigation were shaped as cylinders with a diameter of 0.5 cm and heights of 1.5 and 3.0 cm. The positional resolution along the crystal axis was also investigated for the CeBr₃ crystals by measuring the amplitudes of the scintillation signals from the opposite crystal ends. It was shown that the ratio of these amplitudes was dependent on the distance from a crystal end surface to the interaction point of a γ quantum inside the detector according to the linear law. The positional resolution along the crystal length appeared to be comparable to the crystal diameter. The results of the study suggest that CeBr₃ crystals have a great potential as position-sensitive elements of space-sensitive detectors for high-energy charge particles and γ rays.     

Energy resolution of gamma-ray spectroscopy of JET plasmas with a LaBr3 scintillator detector and digital data acquisition

A new high efficiency, high resolution, fast γ-ray spectrometer was recently installed at the JET tokamak. The spectrometer is based on a LaBr3(Ce) scintillator coupled to a photomultiplier tube. A digital data acquisition system is used to allow spectrometry with event rates in excess of 1 MHz expected in future JET DT plasmas. However, at the lower rates typical of present day experiments, digitization can degrade the energy resolution of the system, depending on the algorithms used for extracting pulse height information from the digitized pulses. In this paper, the digital and analog spectrometry methods were compared for different experimental conditions. An algorithm based on pulse shape fitting was developed, providing energy resolution equivalent to the traditional analog spectrometry method.     

Studying the spectrometric characteristics of an ionizing-radiation detector based on a LaBr<Subscript>3</Subscript>(Ce) scintillator and a silicon photomultiplier

The intrinsic background of a LaBr₃(Ce) scintillator with a diameter of 5 mm and a height of 10 mm has been studied in comparison with LYSO and CeBr₃ scintillators. It is shown that due to its high energy resolution the detector based on a LaBr₃(Ce) crystal exhibits the lowest background count rate in a specified amplitude range. The measured energy resolution of the detector based on a LaBr₃(Ce) crystal with dimensions of Ø5 mm × 10 mm in combination with a silicon photomultiplier with an active area of 3 × 3 mm² are presented. It is demonstrated that a detector array with the proposed configuration (a scintillator + a silicon photomultiplier enclosed in a common container) exhibits an energy resolution of 4% for 661.7-keV γ rays and a background count rate of ~0.39 cps in the energy range of (140 ± 3σ) keV.     

Use of a scintillator based on an activated paraterphenyl polycrystal as part of a phoswich detector

The possibility of designing phoswich detectors comprising organic polycrystalline scintillators for simultaneous and separate detection of β and γ rays has been investigated. Activated n-terphenyl polycrystals of a certain thickness were produced for these detectors by molding solution-grown raw material in the shape of plates at premelting temperatures. It is shown that the spectrometric and radiometric characteristics of the phoswich detectors can be improved by using these polycrystals, as well as by gluing two scintillators by optical adhesive compositions based on high-purity polymethyl phenylsiloxane rubber.     

A single crystal of YALO3: Ce3+ as a fast scintillator in SEM

A new single-crystal scintillator intended for applications in a scanning electron microscope (SEM) is presented. It is a single-crystal disc of yttrium aluminium perovskite activated by trivalent cerium free of traces of Fe ions. The single crystals of YAlO₃: Ce³⁺ (YAP: Ce³⁺) were prepared by the Czochralski method in a reducing atmosphere of Ar and H₂ with an excess amount of Y³⁺ ions. Effective methods of purification and purity control of the raw material are described. The highest achievable concentration of Ce³⁺ ions in as grown crystals amounted to 0.3 wt%, concentration in the melt was 8–9 times higher. The best properties were found with samples of the maximum possible concentration of Ce³⁺. Compared with the previous aluminate Y₃ Al₅ O₁₂: Ce³⁺ (YAG: Ce³⁺) these samples showed higher efficiency, a shorter decay time of luminescence (40 ns) and an emission band in a more advantageous spectral region (378 nm). Because of high resistance to radiation damage, high chemical resistance and applicability to ultra-high vacuum it is also suitable for detection of other kinds of ionizing radiation.     

A Dual-energy X-ray detector on the basis of ZnSe(Al) and LGSO(Ce) composite scintillators

The results of tests of an experimental prototype of a two-energy scintillation detector, which is based on a two-layer composite system of fine-crystalline ZnSe(Al) and LGSO(Ce) scintillators, are presented and its properties are determined. The X-rays spectra for each element of the detector were obtained. The analysis of these spectra allowed determination of the energy efficiency of the X-ray absorption for each element of the detector in an energy range of 30–70 keV. The dependences of proper signals from photodetectors under the action of X rays (the tube voltage varied from 40 to 90 kV) were restored. The corresponding X-ray spectra are presented as well. The dependences of scintillation signals from disperse ZnSe(Al) and LGSO(Ce) scintillators on the X-ray tube voltage are presented (the voltage varied from 40 to 70 keV). Due to the high registration efficiency of relatively low-energy X rays (up to 70 keV), this detector can be used not only in engineering introscopy (customs baggage control, mail, cargo-container, and vehicle checks, etc.), but also in various fields of medical radiology.     

A modification of the ET secondary electron detector with a single crystal scintillator

On the basis of the study of optical properties of single crystal YAG scintillators, it has been found that the maximum light output signal propagated in the required direction in the scintillator of a secondary electron detector is obtained if a cone-shaped scintillator is used. A modified Everhart-Thornley (ET) detector containing a conical scintillator and an electro-optical diaphragm operated at a positive voltage shows an increase to 2.8 times the light output signal of the classical ET detector with a flat single crystal YAG scintillator disc. The modification allows optimization of the suction of secondary electrons toward the scintillator and of the propagation of light from the scintillator toward the light guide.     

The response of a fast phosphor screen scintillator (ZnO:Ga) to low energy ions (0-60 keV)

ZnO:Ga is a promising, high time resolution candidate for use as a fast-ion-loss detector in TJ-II. We compare its ionoluminescence with that of the standard fast-ion-loss detector material, SrGa(2)S(4):Eu (also known as TG-Green), when irradiated by H(+) ions with a range of energies E≤60?keV using a dedicated laboratory setup. It is found that ZnO:Ga is a reasonably good candidate for detecting low energy (E<60?keV) ions as it has excellent time resolution; however, its sensitivity is about 100 times lower than TG-Green, potentially limiting it to applications with high energy ion loss signals.     

Note: a high performance pulse energy detector for Q-switched laser based on photoacoustic effect

A high performance pulse energy detector is developed based on photoacoustic effect. Different from the detectors reported before which also utilized photoacoustic effect, our detector can measure the energy of each pulse output from a Q-switched laser and monitor the pulse energy fluctuation in real time owing to the signal processing circuit designed. By comparing with a commercial laser energy meter, our detector is proved to be of high sensitivity and accuracy. We test the detector under illumination of different pulse energy at varied wavelengths, and the results demonstrate that the detector has a broad spectral response and a dynamical energy range. Besides, the measurements of this detector will not be affected by the background light according to the principle of photoacoustic effect.     

Portable (3)He detector cryostat for the far infrared

A portable (3)He cryostat for far infrared detection applications is described. The cryostat has been used for a number of years in aircraft- , observatory- , and laboratory-based research. Some related studies of various bolometric materials are also reported.     

Heteroepitaxy of Nd(0.67)Sr(0.33)MnO3 on silicon for bolometric x-ray detector application

We have recently reported the design concept and sensor fabrication for a novel bolometric x-ray detector based on a rare earth manganite material for application as a total energy monitor for the Linac Coherent Light Source (LCLS) free electron laser at the Stanford Linear Accelerator Center (SLAC). The detector employs epitaxial thin films of Nd(0.67)Sr(0.33)MnO(3) grown on Si by pulsed laser deposition. In this paper we report details of the fabrication of the actual detector, its response characteristics under photon illumination from LCLS, and improvements in the growth scheme of the sensor material on Si using a buffer/template layer scheme that employs yttria-stabilized zirconia, cerium oxide (CeO(2)), and bismuth titanate (Bi(4)Ti(3)O(12)). The thermal sensor response changes linearly with the energy of an optical calibration laser as expected, and the signals from optical and x-ray pulses at LCLS are very similar, thereby validating the design concept. To the best of our knowledge, the LCLS detector application reported here is the first practical use of colossal magnetoresistive manganite bolometers.     

基于料斗秤标定核子秤的改进研究

针对使用下矿料斗标定核子秤应用过程中存在误差大、劳动强度大等问题及缺陷,通过应用过程中分析研究,提出对下矿料斗进行改造,加装称重传感器、显示仪表的方法,解决多次计量误差大、劳动强度大的问题.     

A scintillation γ-ray detector based on a solid-state photomultiplier

A scintillation detector based on a silicon photodetector of a new type—a solid-state photomultiplier—and a single-crystal CsI(Tl) scintillator was investigated. The effect of temperature on the low-energy detection threshold and the energy resolution of the detector and the influence of the radiation level on the detector efficiency (i.e., the influence of the counting rate of the distortion in the recorded spectrum shape) were estimated. A mathematical model of the detector was developed in order to assess its parameters.     

基于组合评价方法(AHM-GF)的制造企业综合能效评价研究

依据制造业中高能耗企业的能源消费特点,从经济、管理、技术、环境4个方面,归纳出14个评价指标,构建了企业能效综合评价指标体系。并鉴于评价过程中存在的模糊性和随机性,提出了高能耗企业能效综合评价的AHM—GF组合评价方法。该方法将属性层次分析法,灰色关联法和模糊评价法运用在企业能效评价的不同阶段,较好的克服了评估信息的灰色性和不确定性。最后通过实例运算证明了该评价方法的科学性和可行性。     

基于51单片机的透光式孔洞检测仪设计

工业生产板带过程中,由于原料不稳定、工艺控制波动和设备异常等因素,会引入多种缺陷,孔洞属于引入的典型的严重缺陷。该文设计的孔洞检测仪相对于人工检测和影像检查具有检测精度高,投入成本低,易于现场安装和维护等多种优点,有很好的应用前景。     

基于PSPICE的热释电红外线探测器设计

本文介绍了热释电红外探测器的结构及工作原理，由热释电效应推导出了热释电电流及热释电电压响应表达式，利用仿真软件PSPICE分析了热释电探测器等效电路模型，该模型是使用PSPICE的ABM功能中的微分器和压控电流源等电路元件来建立等效模型。本文最后在红外专用芯片BISS0001不可重复触发工作方式下给出了热释电红外探测器电路，模拟结果与实验数据基本一致。根据该模型选取适当的参数，可以设计不同的红外探测器实用电路，为红外探测器电路设计提供了新的思路。     

基于Overhauser效应的磁场梯度探测器

为提高单探头磁力仪在自然环境中的抗干扰能力,设计了一种基于Overhauser效应的双探头磁场梯度探测器。文中介绍了Overhauser效应的基本原理,对仪器的射频激发系统、信号调理系统和频率计做了详细的描述。论文分析了射频系统的不稳定因素,并给出解决方案。针对拉莫尔旋进信号,提出一种基于FPGA的多通道测频算法,并对比测试使用该算法前后的结果,分析了实验数据。同时对仪器双探头的数据一致性进行比对,给出了测试方法和测试结果。最后将该仪器和商用仪器进行室内、室外以及磁异常探测等对比试验,结果表明,其性能接近商用仪器水平,具有野外操作便捷、测量磁场精度高、抗干扰能力强等优点,证明了所研制的基于Overhauser效应的磁场梯度探测器在梯度测量中的有效性。     

Optimization of a bolometer detector for ITER based on Pt absorber on SiN membrane

Any plasma diagnostic in ITER must be able to operate at temperatures in excess of 200?°C and neutron loads corresponding to 0.1 dpa over its lifetime. To achieve this aim for the bolometer diagnostic, a miniaturized metal resistor bolometer detector based on Pt absorbers galvanically deposited on SiN membranes is being developed. The first two generations of detectors featured up to 4.5?μm thick absorbers. Results from laboratory tests are presented characterizing the dependence of their calibration constants under thermal loads up to 450?°C. Several detectors have been tested in ASDEX Upgrade providing reliable data but also pointing out the need for further optimization. A laser trimming procedure has been implemented to reduce the mismatch in meander resistances below 1% for one detector and the thermal drifts from this mismatch.     

A BSE scintillation detector in the (S)TEM

A single crystal YAG: Ce³⁺ annular scintillator axially placed in a movable light guide forms the essential part of a new BSE detector. Comparison of properties of this detector with those of a semiconductor detector is made. The bandwidth, signal-to-noise ratio, capacitance effects, and relative efficiency are parameters which favour the scintillation detector. Its disadvantage is that it must be equipped with a photomultiplier and a light guide. The position of the scintillator above the specimen permits efficient detection at a large collection angle of BSE. For normal beam incidence, the signal homogeneity from any area of the scintillator ensures that images are obtained without shadow effects due to signal loss in the scintillator or due to detector geometry. The same probe current as for other detection modes can be used. Resolution of details is as high as for an SE image.