一种漂移室定位子性能反常现象的研究

研究了一种漂移室定位子性能的反常现象,它关系到定位子的使用寿命．着重测量了暗电流和随机噪声与时间、高压及温度的关系.     

BES主漂移室的宇宙线测试结果

简要描述了北京谱仪(BES)主漂移室的结构和宇宙线实验安排,给出利用宇宙线测试主漂移室性能的主要结果.单元内具有线性的漂移距离S-漂移时间T关系.室的单丝空间分辨率σ_x=210～240μm.相当室内40次dE/dx取样的能量分辨率为8.7%.主漂移室运行稳定.     

1m×1m漂移室特性在线测量

本文给出了用宇宙线在线测量漂移室性能的实验结果. 获得时间分辨率4.26ns, 空间分辨率132μm, 效率96%以上. 漂移室在线实验系统由五个1m×1m×0.09m可调电场漂移室, 闪烁计数器触发系统, 漂移室读出电子学系统, 以及TRS-80微型计算机四部分构成. 数据的实时采集, 分析处理等均由微型计算机在线或离线完成.     

Installation and cosmic ray test of the high voltage system of the BESⅢ drift chamber

After examination of the designed high voltage power supply system of the BESⅢ drift chamber in the beam test of the full length prototype of drift chamber, a full system covering all the channels of high voltage was installed. The system's training and the high voltage value adjustment were carried out in the cosmic ray test of the BESⅢ drift chamber. The cosmic ray test for the full system and its final installation on the BESⅢ drift chamber were reported. The full system of high voltage power supply works stably and reliably.     

施振功率与温度对工业纯铝凝固组织的影响

在工业纯铝的凝固过程中引入超声场,探讨了超声细化晶粒的机理,并具体研究了超声功率、导入声波的熔体温度区间对铸锭凝固组织的影响规律. 实验结果表明:铝熔体经超声处理后,凝固组织均得到显著细化,这主要取决于超声的空化效应和声流效应;超声功率增大时,组织细化程度提高,功率达到170W时细化效果最好,继续增大功率则细化作用减弱;施振温度区间对凝固组织的影响也有相似的规律,在合理的温度导入声波,晶粒能细化到最佳程度.     

Study of measuring methods on spatial resolution of a GEM imaging detector

In this paper, the limitations of the common method measuring intrinsic spatial resolution of the GEM imaging detector are presented. Through theoretical analysis and experimental verification, we have improved the common method to avoid these limitations. Using these improved methods, a more precise measurement of intrinsic spatial resolutions are obtained.     

Study of a bulk-Micromegas with a resistive anode

The design and performance of a Micromegas with a resistive anode are presented in this paper. A thin resistive sheet with volume resistivity of 10¹² Ω·m cm is glued onto the readout electrode surface and its performance is investigated by using a ⁵⁵Fe X-ray radioactive source in the operation gas of argon and isobutene mixtures (Ar/Iso=95/5). The gas gain at different mesh high voltage, counting rate and working time are given. Energy spectra at different working voltages are measured and the results are discussed. We have oberved that a Micromegas with a resistive anode can be operated at higer gain than a standard Micromegas without sparks.     

“钦州红荔”新株系形态及同工酶分析

在广西钦州市钦北区新棠镇进行田间试验,观测“钦州红荔”株系和“黑叶”、“香荔”等品种单株的植株形态和果实性状表现,采集营养梢老熟叶片进行过氧化物酶（ＰＯＤ）同工酶分析。结果表明：“钦州红荔”植株形态和果实性状保留有“黑叶”和“香荔”品种单株的一些特性,该株系早结丰产,果形特大,果皮鲜红色、品质优。叶片ＰＯＤ同工酶分析,它们具有相似遗传基础、迁移率为０．３３和０．５４的２条特征酶带,初步鉴定认为“钦     

Moodle网络课程中讨论区交互特征的社会网络分析——以《网络远程教育》课程为例

以上海师范大学东行记Moodle平台中开设的一门网络课程为例,运用社会网络分析的方法对其中的讨论区交互状况进行了分析,在此基础上总结得出,Moodle网络课程中的讨论区具有异步、动态、不稳定、弹性等特征,与此同时,也发现部分学生很少参与讨论的问题,对此,提出了使用讨论区的一些建议,最后指出本研究的不足之处和后续的研究计划．     

两个不同单元尺寸的小单元漂移室模型的性能研究

利用宇宙线分别测量了两个单元尺寸为14mm和16.4mm充He/C3H8(60/40)气体的小单元漂移室模型的性能，包括空间分辨，dE/dx分辨和单元效率. 测量结果表明两个漂移室模型的性能没有明显区别.