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Detailed measurements of Hamamatsu R5912 photomultiplier signals are presented, including the single photoelectron charge response, waveform shape, nonlinearity, saturation, overshoot, oscillation, prepulsing, and afterpulsing. The results were used to build a detailed model of the PMT signal characteristics over a wide range of light intensities. Including the PMT model in simulated Daya Bay particle interactions shows no significant systematic effects that are detrimental to the experimental sensitivity. 相似文献
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《Journal of Magnetic Resonance (1969)》1984,56(3):428-442
Spurious signals caused by the piezoelectric ringing of single crystals of NaNO2 in pulsed NMR have been studied at 14.5 MHz using AM detection. Their amplitude is about two orders of magnitude larger than the 23Na FID when the a axis of the crystal is along the axis of the coil, and about one order of magnitude larger than the FID when the b or c axis is along the coil axis. The buildup of the piezoelectric signals during a pulse is found to be characterized by a time constant of about 10 μec. However, the decay following the pulse is characterized by an altogether different time constant which varies with the pulse length but is of the order of 100 μsec. Measurements at different locations of the crystal relative to the rf coil show that the piezoelectric signals are generated by a wholly electrostatic interaction, primarily involving the longitudinal electric field generated by the pulse. A theoretical expression for the signal amplitude has been derived. It accounts for many properties of the signals but gives an amplitude which is two orders of magnitude larger than the experimental. Ways of suppressing the piezoelectric signals to facilitate the observation of NMR are discussed. 相似文献
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买买提吐送.买买提明 《应用声学》2013,32(4):325-封三
对不同厚度液体进行光强测量,深入探索空化气泡的运动,研究发光机理很有意义。用超声激励法在磷酸液体中实现多泡声致发光,研究不同共振频率下发光的特点。利用光电倍增管多次测量发光强度相互比较,结果是在液体厚度10 cm、驱动频率f=21.061kHz和f=20.316kHz时,周期性较好为50μs,液体通过漩涡集中气泡可以使更多气泡发光;在液体厚度3 mm、驱动频率f=17.91kHz和f=19kHz时,周期性很好为25μs;且光信号都较强。结论是磷酸中声致发光强度、周期与液体厚度、驱动频率密切相关。本文以磷酸液多泡声致发光实验研究为基础,从内部和外部原理来出发,详细介绍了光电倍增管在多泡声致发光光强测量中的实用,为今后研究者提供了一些经验。根据实验过程中遇到的一些实际问题提出了建议和改善意见。 相似文献
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米氏模型和德拜级数展开模型在气泡尺寸达到μm量级时不能很好地解释海水中大尺寸空泡的后向散射现象,计算速度较慢且容易溢出。提出使用几何物理光学模型解释大尺寸空泡的后向散射现象,给出了一种基于几何物理光学模型的球形大气泡散射特性的数值计算方法,并与德拜级数展开式进行了比较,计算结果基本吻合。该方法在计算大尺寸空泡的后向散射时不受微粒尺寸参数和折射率的限制,且避免了复杂的级数形式,与基于米散射理论或德拜级数展开的算法相比,具有更快的运算速度。最后给出了一些计算实例。 相似文献