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41.
采用湿化学法合成了Eu原子掺量5%的Lu2O3陶瓷前驱体,通过SEM、XRD研究了煅烧前后前驱体和1 100 ℃煅烧4 h后粉体的形貌、结构以及物相。结果表明煅烧后的粉体为纳米类球形、高分散且结晶性良好的颗粒。颗粒尺寸为68.5 nm。使用煅烧后的粉体为原料,在1 650 ℃真空烧结30 h制备了高透过率的Eu:Lu2O3陶瓷,晶粒尺寸为46 μm,在611 nm处的直线透过率可以达到66.3%。此外对陶瓷的吸收曲线、光致激发和发射光谱特性以及X射线激发发射光谱进行研究。可观察到,Eu:Lu2O3陶瓷存在基质和激活离子两类吸收,光致发光光谱和X射线激发发射光谱均可以看出Eu:Lu2O3陶瓷存在极强的5D0→7F2跃迁发光,位于611 nm处。对比商业的BGO单晶的X射线发射光谱,可得本实验中制备的陶瓷的光输出为85 000 ph/MeV。Eu:Lu2O3陶瓷本身有着高X射线以及高能粒子的阻止能力,结合高光输出特性,表明Eu:Lu2O3陶瓷在X射线成像等领域具有巨大的潜在应用价值。 相似文献
42.
差分吸收激光雷达回波信号统计模型的研究 总被引:3,自引:0,他引:3
差分吸收激光雷达回波信号统计模型是研究差分吸收激光雷达系统的基础,但是现有的统计模型中均没有考虑大气湍流导致的激光闪烁对回波信号的影响。针对已有统计模型的缺陷和应用需要,综合考虑了大气湍流导致的激光闪烁、目标反射斑纹、接收噪声以及发射功率波动对回波信号统计特性的影响,提出了一种改进的长程差分吸收激光雷达回波信号统计模型,分析了该模型的统计特性。仿真结果表明大气湍流导致的激光闪烁对回波信号统计特性的影响十分显著,同时也验证了该统计模型比已有统计模型更精确、更符合实际。 相似文献
43.
The distribution function which given by Grad cannot be used to describe the ionospheric ion velocity distribution due to the larger anisotropic temperature appears in the high-latitude ionosphere. In this article, based on the Boltzmann equation, the relaxation collision model (RCM) was used to substitute the Boltzmann collision integration, and a non-Maxwell ion velocity distribution function with the 16-moments approximation for the bi-Maxwell distribution was given, and the ion transport equation with the 16-moments approximation was also derived and solved. Moreover, the ion velocity distribution, the solution of transport equation and the incoherent scattering spectra with the 13-moments and 16-moments approximation for the relaxation collision model were simulated, analyzed and compared. The research shows that compared with the 13-moments approximation, the 16-moments approximation with the bi-Maxwell distribution is more suitable to describe the characteristics of the anisotropic temperature ion distribution in the high-latitude ionosphere. 相似文献
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K. Irmer 《Isotopes in environmental and health studies》2013,49(10):417-418
Bei der kontinuierlichen Durchstrahlungsprüfung von Werkstücken werden überwiegend Meßeinrichtungen, bestehend aus 60Co-Strahlungsquelle, Szintillationsdetektor und schreibendem Meßgerät, verwendet 1. 相似文献
47.
Mittels Aktivierungsanalyse wurde der Gehalt an Arsen, Antimon, Kupfer, Phosphor und Zink in Halbleitersilizium bestimmt. Die Methode besteht aus zwei Schritten: 1. Gruppentrennung durch Anionenaustausch mit einem Gemisch von Salz- und Fluorwasserstoffsäure, 2. Selektive substöchiometrische Extraktion von Arsen und Kupfer mit Diäthyldithiocarbamat, von Antimon mit Cupferron und von Zink mit Dithizon. Phosphor wurde extraktiv als Phosphomolybdat abgetrennt. 相似文献
48.
D. Hebert K. Froöhlich A. Andreeff 《Isotopes in environmental and health studies》2013,49(10):358-361
Aufbau, Arbeitsweise und Eigenschaften einer Apparatur, mit der naturliche l4C-Aktiviäten in Grund- und Oberflächenwässern gemessen werden können, werden beschrieben. Die Messung erfordert 3 Arbeitsschritte: Probenahme, Synthese von Benzol, welches dann den Probenkohlenstoff enthält, und Messung der 14C-Aktivität in einem Flüssigkeitsszintillationszähler. Die Apparatur kann zur Datierung von Wasserproben im Altersbereich zwischen 200 und 37000 a verwendet werden. 相似文献
49.
New commercial dosimetry systems need careful characterization and can benefit from the comparison with similar, in-house developed solutions. A comparison between such two dosimetry systems, both based on fibre-coupled organic plastic scintillator detectors, is presented. One system is the Exradin W1, fully commercialized by Standard Imaging, while the other system is the non-commercial ME40 system, developed by DTU Nutech with the aim of fundamental dosimetric research. Both systems employ plastic scintillator detectors that can be considered similar in design, calibrated using the same method, but differing primarily in the signal detection hardware. The two systems were compared with respect to essential dosimetric properties, with the purpose of testing their performance under conditions less well discussed in the literature. A Farmer ionization chamber was used as the primary reference of the comparison. The study demonstrated that the Cerenkov light ratio calibration coefficient of both systems was not constant, but changed systematically with photon beam quality to a maximum difference of 1.1%. Calibration with respect to stem effect correction should therefore be performed for every investigated beam quality when using plastic scintillator detectors. Both systems were found to be dose rate independent, even for the highest instantaneous dose rate evaluated (1.5 mGy per pulse). Low-dose measurements revealed large uncertainties for both systems, although the ME40 system handled short beam deliveries under reference conditions with accuracy and precision within 0.4%. Changes in response due to field size dependence were investigated and found to be as large as 3.3% for the W1 and 5.4% for the ME40, biasing output factor measurements in large fields. Great caution is therefore advised if using either system for measurements in large fields or under circumstances where the fibre irradiation geometry is unfavourable. Measurements of reference dose to water yielded differences up to 1.5% when compared with the Farmer ionization chamber for all investigated beam qualities. 相似文献
50.
Digital pulse shape discrimination methods for n-γ separation in an EJ-301 liquid scintillation detector 下载免费PDF全文
WAN Bo ZHANG Xue-Ying CHEN Liang GE Hong-Lin MA Fei ZHANG Hong-Bin JU Yong-Qin ZHANG Yan-Bin LI Yan-Yan XU Xiao-Wei 《中国物理C(英文版)》2015,39(11):116201-116201
A digital pulse shape discrimination system based on a programmable module NI-5772 has been established and tested with an EJ-301 liquid scintillation detector. The module was operated by running programs developed in Lab VIEW, with a sampling frequency up to 1.6 GS/s. Standard gamma sources22 Na,137Cs and60 Co were used to calibrate the EJ-301 liquid scintillation detector, and the gamma response function was obtained. Digital algorithms for the charge comparison method and zero-crossing method have been developed. The experimental results show that both digital signal processing(DSP) algorithms can discriminate neutrons from γ-rays. Moreover,the zero-crossing method shows better n-γ discrimination at 80 ke Vee and lower, whereas the charge comparison method gives better results at higher thresholds. In addition, the figure-of-merit(FOM) for detectors of two different dimensions were extracted at 9 energy thresholds, and it was found that the smaller detector presented better n-γseparation for fission neutrons. 相似文献