Comparative studies of silicon photomultipliers and traditional vacuum photomultiplier tubes

Silicon photomultipliers (SiPMs) are a new generation of semiconductor-based photon counting devices with the merits of low weight, low power consumption and low voltage operation, promising to meet the needs of space particle physics experiments. In this paper, comparative studies of SiPMs and traditional vacuum photomultiplier tubes (PMTs) have been performed regarding the basic properties of dark currents, dark counts and excess noise factors. The intrinsic optical crosstalk effect of SiPMs was evaluated.     

CsI（T1）晶体量能器中硅光二极管的核计数器效应研究

研究了由于电磁簇射在CsI（T1）晶体后端的泄漏而引起的硅光二极管“核计数器”效应．通过GEANT模拟和实验测量分析其在BESⅢ的CsI（T1）晶体量能器中对能量测量的影响．     

BESⅢ晶体量能器设计中的蒙特卡罗研究

在BESⅢ晶体量能器的设计、研制过程中,利用7×7CsI晶体探测单元的模拟程序,对其性能做了精细的蒙特卡罗研究.给出了与非相干噪声、能量线性、晶体光输出均匀性、位置依赖等相关的模拟结果.     

N-乙酰半胱氨酸对老年患者碘海醇肾损害的保护作用

目的探讨N-乙酰半胱氨酸对老年患者碘海醇肾损害的保护作用。方法选取行增强CT检查（静脉注射碘造影剂碘海醇）的老年患者74例,其中A组26例（于造影前48h和造影后48h口服N-乙酰半胱氨酸600mg,2次/d）,B组25例（于造影前48h和造影后48h口服N-乙酰半胱氨酸600mg,1次/d）;对照组23例（于造影前48h和造影后48h口服安慰剂,1次/d）。造影前和造影后48h,检测3组患者血尿素氮（BUN）、SCr、内生肌酐清除率（CCr）,并记录对比剂肾病发生率,造影前和造影后48h以及5d时,检测24h尿蛋白（PRO）、24h尿β2-微球蛋白(β2- MG)、24h尿微量白蛋白（UmAlb）。结果 A组无CIN发生,B组发生CIN5例（20%）,C发生CIN6例（26.09%）,A组CIN发生率明显低于B、C组（均P＜0.05）。3组患者造影前各指标的差异均无统计学意义（P＞0.05）。与造影前比较,3组患者造影后48h BUN、SCr、Ccr均发生明显变化（P＜0.05）;与B组、对照组比较,A组造影后48h BUN、SCr、Ccr均发生明显变化（P＜0.05）。与造影前比较,3组患者造影后48h、5d时PRO、Umalb、和β2- MG均发生明显变化（P＜0.05）;与对照组比较,A组造影后48h及5d、B组造影后48h的PRO、Umalb、和β2- MG均发生明显变化（P＜0.05）。结论口服N-乙酰半胱氨酸600mg（2次/d）能有效预防老年患者碘海醇肾损害。     

Performance study of a micro-pattern gas detector: leak microstructure

A micro-pattern gas detector named leak microstructure (LM) has been studied. A new chemical electrolytic technique is introduced to make perfect shaped LM needles with very sharp tips, and this method may be developed to make LM array detectors in batches. The experimental results are presented for both a single needle LM detector and a small LM array detector. The gas gain is up to 10⁵ by calculation from the waveform. Good gain stability and uniformity are achieved. The light emission from the needle tip is also measured in Ar/CF₄(95/5) gas mixture. The result shows a promising application for imaging.     

Aging of LAB-based liquid scintillator in stainless steel containers

Types 316 and 304 stainless steel are two candidates for the storage vessels and piping systems of LAB-based liquid scintillator (LS) in the JUNO experiment. LS aging experiments are carried out at temperatures of 40℃ and 25℃. After 192 days aging at 40℃, the attenuation length of LS was reduced by 6% in a glass container, 12% in a type 304 stainless steel tank, and 10% in a type 316 stainless steel tank. At 25℃ in 304 and 316 stainless steel tanks, the attenuation length was reduced by 6% after 307 days. The light yield and the absorption spectrum were practically the same as that of the unaged sample. The concentration of element Fe in the LAB-based LS did not show a clear change. Type 316 and 304 stainless steel can be used as vessels and transportation pipeline material for LAB-based LS.     

反相微乳液法制备膜状普鲁士蓝类配合物纳米材料

在十六烷基三甲基溴化铵(CTAB)/正戊醇/异辛烷/水构成的油包水型(W/O)微乳体系中合成了膜状及50 nm立方状的Co-Fe普鲁士蓝类配合物(cobalt-iron Prussian blue analogues). 研究了w值(水与CTAB的物质的量的比)、反应物浓度和反应温度对产品形貌的影响. 并用原子力显微镜(AFM), 透射电子显微镜(TEM), 电子能谱(EDS), X射线光电子能谱(XPS)和红外(IR)对产品进行了表征.     

硝基苯与正十六烷二元溶液在临界区域的浊度

测量了硝基苯与正十六烷二元溶液在临界区域不同波长及温度下的浊度, 结合与关联长度、渗透压缩系数、共存曲线有关的三个指前因子(x0, ξ0, B)的比例关系: R=ξ0[B^2/(4kBTcx0)]^1^/^3(kB和Tc分别为玻尔兹曼常数与临界温度)及R的理论值(0.65-0.67), 用Ornstein-Zernike方程拟合浊度-温度-波长数据, 得到临界指数γ与ν, 在误差范围内与值一致。将γ与ν固定在理论值1.241和0.63, 求得ξ0为0.168nm(R=0.65)和0.174nm(R=0.67), x0为2.81×10^-^9m^3.J^-^1(R=0.65)和2.85×10^-^9m^3.J^-^1(R=0.67)。     

钴-钴普鲁士蓝类似物衍生的SnCoOx中空纳米立方体的制备及电化学检测氯氮平的性能研究

通过化学沉淀法合成了钴-钴普鲁士蓝类似物(CoCo-PBA)纳米立方前驱体,掺杂Sn4+后,将其在空气中高温热解,制备中空多孔SnCoOx,然后通过超声将SnCoOx固定在石墨毡(GF)上,制成复合电极(SnCoOx/GF).利用X-射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、X-射线光电子能谱(XPS)、扫...     

Monte Carlo study on the low momentum μ-π identification of the BESⅢ EM calorimeter

The BESⅢ detector has a high-resolution electromagnetic calorimeter which can be used for low momentum μ-π identification. Based on Monte Carlo simulations, μ-π separation was studied. A multilayer perceptron neural network making use of the defined variables was used to do the identification and a good μ-π separation result was obtained.