三能段X射线成像数据采集系统设计

伴随着探测器技术以及电子学技术的不断发展,多能段X射线图像采集技术在安检领域特别对提高物质分辨能力起到越来越重要的作用.针对这一需求,文章基于多能量X射线成像技术的成像原理以及技术现状,介绍了利用光子计数型探测器来实现多能段X射线成像的方法.并利用YSO晶体与硅光电倍增管给出一种基于该技术的三能段X射线数据采集系统的电...     

用半导体探测器测量1.5-60keV的X射线

本文阐述X射线能谱测量用的半导体探测器,对硅与锗X射线探测器进行了比较。扼要介绍了X荧光分析用的探测器的制备方法和性能,分析了影响探测器效率的因素。实际量测了1.5-60keV的X和低能γ射线。对于能量>5keV的X射线,探测效率用~(241)Am源刻度,<5keV时,用玻璃荧光源测量窗吸收及其他效率损失的标准技术。测量结果与文献发表过的数据进行了比较。     

半导体探测器的厚度确定及CsI(Tl)的刻度

根据核反应过程中发射带电粒子在硅半导体中的最大能量沉积,利用带电粒子在硅半导体中的阻止本领曲线,同时实现半导体探测器的厚度确定及与之组合的CsI(Tl）的刻度。     

金-硅面垒型探测器的制备

一、引言金-硅面垒型探测器具有下列的特点:能量分辨率高;脉冲上升时间短;耗尽层宽度可调节,因而能甄别不同的射线;脉冲高度与能量之间的线性响应好;对γ射线、中子本底不灵敏,适于在γ射线、中子本底较高的情况下测量带电粒子;工艺简单,成本较低等等。因此,自1949年麦凯(K.G.McKay)首先利用半导体探测器探测射线以来,它在核辐射探测领域中得到了很大的发展。关于金-硅面垒型探测器的制作工艺、探测原理、性能和应用已有报导。     

PIN硅光二极管在n/γ混合辐射场中的探测技术研究

PIN硅光型半导体探测器较传统辐射探测器具有响应快、抗干扰强、体积小、灵敏度高、能量分辨率高以及无需高压等优点,在个人剂量仪、X射线荧光分析、镀层测厚、放射诊断等粒子辐射测量领域中被广泛采用.采用6LiI与BGO晶体把n和γ射线转换至PIN的有效光谱探测范围内,同时参考PIN硅光二极管的电路等效模型,设计与之匹配的电荷...     

XAFS实验探测器的研究

新型硅P-N结光电超二极管对光于能量响应范围已达到了X射线范围。它具有线性范围大，能量响应范围宽，量子效率高等优点，因而适用X射线之探测。本介绍了以光电二板管构成同步辐射XAFS探测器替代传统的电离室探测器组合的研究工作，给出了的探测器结构设计，工作原理，实验结果及讨论。     

硅(锂)X射线探测器

介绍了10～80mm~2的硅(锂)X射线探测器研制工艺,并讨论了工艺过程和测量中的一些问题;给出了探测器的指标,这些指标大都达到和接近国外同类产品水平。硅(锂)X射线探测器是一种低能X射线探测器,它具有能量分辨率高、线性好,对低能区X射线探测效率高等特点,在核物理、医学、地矿、环保等领域有着广泛的应用。它也是扫描电镜,X射线荧光分析等能谱分析的核心部件。     

硅(锂)X射线探测器

介绍了10～80mm’的硅(锂)X射线探测器研制工艺,并讨论了工艺过程和测量中的一些问题;给出了探测器的指标,这些指标大都达到和接近国外同类产品水平。硅(理)X射线探测器是一种低能X射线探测器,它具有能量分辨率高、线性好,对低能区X射线探测效率高等特点,在核物理、医学、地矿、环保等领域有着广泛的应用。它也是扫描电镜X射线荧光分析等能谱分析的核心部件。     

碘化汞核辐射半导体探测器

由于硅(锂)和锗(锂)探测器都需要在液氮温度下保存和工作,因此人们集中发展了原子序数高的、能在室温下工作的半导体探测器。现在主要研究的室温半导体化合物探测器有砷化镓、碲化镉和碘化汞。HgI_2是七十年代发展起来的一种新型室温核辐射探测器。由于它具有很高的原子序数和较大的禁带宽度,因而它的光电吸收截面大、探测效率高、能在常温下工作,体积小,使用方便。它可探测的能量范围较大,但更适合于探测能量在几个keV至150keV的X射线和γ射线。在医学生物学、放射性监测、野外探矿、能谱分析等方面有     

平面型CdZnTe探测器的能谱特性模拟

CdZnTe(CZT)探测器是一种高原子序数的化合物半导体探测器，具有体积小、探测效率高、可在常温环境使用等特点，广泛应用于X、γ射线探测领域。为了更好地研究CZT探测器能谱特性的影响因素，通过Geant4软件建立探测器几何模型，模拟计算CZT晶体的本征探测效率和吸收率；根据Hecht公式计算电荷收集效率，通过收集晶体中的沉积能量和位置信息得到γ射线能谱；通过分析晶体的物理特性，探索其对探测器性能的影响。模拟计算结果表明：电荷收集不完整是影响探测器能谱性能的重要因素，当能量低于50 keV时，γ射线谱基本不受空穴尾迹的影响，而能量在50～100 keV的γ射线能谱受空穴尾迹的影响较为明显，高于100 keV的γ射线能谱受空穴尾迹的影响逐渐加重。通过增加偏压的方式可以降低空穴尾迹对能谱的影响，同时偏压的增加会使峰位产生偏移，偏移程度受最大电荷收集效率的影响。     

一种监测低能X射线的Si探测器

低能(50keV以下)光子探测器广泛应用于外大气层核爆监测,天体物理现象研究。采用半导体探测单元试制了低能X射线探测器模块。说明了配置多探测器系统的方法,并介绍了探测单元模块的设计、主要试验和技术指标。室温下噪声等效输入光子能量为2.1keV。     

A novel compact Tokamak Hard X-ray diagnostic detector

A compact X-ray detector based on the lutetium yttrium oxyorthosilicate scintillator(LYSO) and silicon photomultiplier(Si PM) has been designed and fabricated for the hard X-ray diagnosis on the HL_2A and HL_2M Tokamak devices. The LYSO scintillator and Si PM in small dimensions were combined in a heat shrink tube package, making the detector compact and integrative. The Monte Carlo particle transport simulation tool,Geant4, was utilized for the design of the detector for the hard X-ray from 10 keV to 200 keV and the best structure scheme was presented. Finally, the detector was used to measure the photon spectrum of a ~(137)Cs gamma source with a pre-amplifier and a multichannel amplitude analyzer. The measured spectrum is consistent with the theoretic spectrum, it has shown that the energy resolution of the detector is less than 14.8% at an energy of 662 keV.     

The Characteristics of an Ultra-High Resolution Ge(Li) Spectrometer for Singles and Coincidence X-Ray and Gamma-Ray Studies

The use of an ultra-high resolution Ge(Li) photon spectrometer in low and high energy X-ray and gamma-ray measurements has been evaluated. Studies were made of the resolution, low energy cutoff, the full energy and K X-ray escape efficiencies, tha effective detector dead layer and the detector linearity. The detector was used simultaneously with a high resolution Si(Li) detector to measure fast coincidences between Ka1 , Ka2 and L X-rays, as well as coincidences between K, L conversion electrons and L X-rays. A detailed discussion is presented of the electronic problems associated with making these kind of measurements. Measurements were also made of X-ray beams produced by clinical X-ray machines at 40, 78 and 220 kV.     

Low Energy Dosimetry With Photon Counting Pixel Detectors Such as Medipix

Hybrid semiconductor photon counting pixel detectors like the Medipix detector have several advantages for an use in X-ray dosimetry. The noiseless photon counting principle allows to monitor low photon energies down to 3.5 keV. Due to the small pixel size (55 mum in case of Medipix2) dosimetry at very high dose rates is possible still processing each photon individually. The large amount of pixels in combination with the possible thickness of the sensor layer enables dosimetry at very low dose rates. A method has been developed to determine personal dose equivalents from the number of counts in energy deposition intervals measured with a semiconductor photon counting pixel detector, despite the strong influence of charge sharing effects among pixels. We tested the method experimentally by reconstructing the air kerma free in air for different qualities of X-radiation in the energy range below 150 keV with an accuracy better than 4%. We show that the response of a dosimeter based on a hybrid photon counting pixel detector can fulfill the IEC type testing requirements. The statistical precision is high due to the thickness and the large area of the sensor layer. We estimate that a dosimeter based on the Medipix detector will be able to cope with dose rates of more than approximately 57 Sv/h for mathdot Hp (0.07) or 19 Sv/h for mathdot Hp(10) . We outline the advantages and perspectives of using this kind of detector in a dosimeter in comparison to standard active personal dosimeters.     

Signal charge sharing in multilinear drift detectors: design andexperimental characterization

Multilinear silicon drift detectors (MLSDDs) are radiation detectors which combine excellent energy and position resolution with high count-rate capabilities. This is achieved by controlling the diffusion of the signal charges and limiting their lateral spread during the drift. This paper will present a study of the signal electrons' transport in MLSDDs in comparison with the experimental measurements. Three-dimensional simulations were carried out, taking into account diffusion effects and mutual electrostatic interaction between the signal electrons. A representative sample of these simulations will be presented. Signal sharing in a multilinear drift detector and in a “classical” multi-anode drift detector are characterized and discussed. The results are useful to tailor the design of MLSDDs for the detection of different kinds of radiation (e.g., optical photon, X-ray, ionizing particle) and to optimize signal charge sharing and detector performance according to a particular application purpose     

X-ray imaging sensor using CdTe crystals for dual energy X-rayabsorptiometry

The authors have designed and built a multi-channel cadmium telluride detector array to test its suitability as an X-ray imaging sensor for dual energy X-ray absorptiometry. The X-ray imaging sensor was constructed of 64 CdTe detector elements with high frequency current amplifiers, discriminators, and counters. The detector elements were operated in the photon counting mode and output pulses induced by the X-ray photons were separated into two energy levels according to their height. The energy resolution of the detector elements was 18.7% to 59.54 keV gamma-rays. In combination with a K-edge filter to produce dual energy X-rays, the X-ray imaging sensor was able to generate two energy X-ray images simultaneously over a short time. By applying a simple energy subtraction method to these images, bone phantoms were distinguished from the overlying tissue phantoms and their densities could be successfully measured. It was clearly demonstrated that this X-ray imaging sensor using CdTe crystals has good potential for high speed bone densitometry     

准单色X射线机替代~(241)Am放射源的测厚应用研究

应用自制的能量50~60 keV的准单色X射线机替代~(241)Am低能光子源(1.11×10~9 Bq)应用于BS-03测厚仪进行测厚研究,分别测试了BS-03测厚仪输出电流范围,测试X射线在钢板、铝板、有机玻璃的衰减规律以及准单色X射线机稳定性,结果表明,准单色X射线机可以替代~(241)Am放射源用于BS-03测厚仪。     

Development of hybrid photon detectors with integrated siliconpixel readout for the RICH counters of LHCb

We report on the ongoing work towards a hybrid photon detector with integrated silicon pixel readout for the ring imaging Cherenkov detectors of the LHCb experiment at the Large Hadron Collider at CERN. The photon detector is based on a cross-focussed image intensifier tube geometry where the image is demagnified by a factor of 4. The anode consists of a silicon pixel array, bump-bonded to a fast, binary readout chip with matching pixel electronics. The developments and tests of full-scale prototypes with 80% active area are presented. Specific requirements for pixel front-end and readout electronics in LHCb are outlined, and recent results obtained from pixel chips applicable to hybrid photon detector design are summarized     

用于HL-2A装置的新型硬X射线探测器

介绍了一种应用于托卡马克等离子诊断领域的新型硬X射线探测器,该探测器主要由硅酸钇镥(Lutetium-yttrium Oxyorthosilicate,LYSO)闪烁体和硅光电倍增管(Silicon Photomultiplier,Si PM)组成。基于项目应用需求,对探测器的选型和基于粒子输运蒙特卡罗仿真软件GEANT4的探测器设计加以阐述,并搭建了前端的探测系统,在HL-2A托卡马克装置上进行了现场诊断实验。实现了硬X射线空间能谱和辐射强度分布的诊断测量。实验表明该探测器阵列具有10 ms的时间分辨率,同时具有结构紧凑、使用方便等特点,能够满足等离子体诊断中硬X射线动态能谱和强度分布测量的诊断需求。     

X-ray energy separation method using a CdTe semiconductor X-rayimaging sensor and photon counting method

A multichannel X-ray imaging sensor using a CdTe compound semiconductor radiation detector in photon counting mode was developed and tested for digital X-ray imaging and an X-ray energy separation capability. The X-ray imaging sensor was constructed of CdTe detector elements at a pitch of 0.25 mm. High band amplifiers, discriminators, and counters attached to each element formed the pulse counting circuit. Charge pulses generated by absorbed X-ray photons were directly counted and separated into two energy regions. Digitized X-ray images containing energy information were thus obtained. Using this sensor two separate X-ray images of different energy can be obtained simultaneously. A 256-channel X-ray imaging sensor was prepared and used to provide spatial resolution measurement for an X-ray charge. Low and high energy images of a hand phantom were thus obtained and both a soft tissue image and a bone image were produced using an energy subtraction method