Angular reconstruction of a lead scintillating-fiber sandwiched electromagnetic calorimeter

The Neighbor Cell Deposited Energy Ratio （NCDER） is a new method that is proposed to reconstruct incidence position in a single layer for a 3-dimensional imaging electromagnetic calorimeter （ECAL）. This method was applied to reconstruct the ECAL test beam data for the Alpha Magnetic Spectrometer-02 （AMS-02）. The results show that this method can achieve an angular resolution of 7.36±0.08°/√E＋0.28±0.02° in the determination of the photon＇s direction, which is much more precise than that obtained with the commonly-adopted Center of Gravity （COG） method （8.4±0.1°/E＋0.8±0.3°）. Furthermore, since it uses only the properties of electromagnetic showers, this new method could also be used for other type of fine grain sampling calorimeters.     

具有可逆热致变色有机-无机杂化铜化合物的合成及表征

在浓盐酸水溶液中，碘化N，N-二甲基-1，5-二氮杂环[3.2.1]辛烷（[3.2.1-Me₂dabco]I₂）和碘化1-氨基-1，4-二氮杂环[2.2.2]辛烷（[2.2.2-NH₂dabco]I）与氯化铜反应得到2种有机-无机杂化铜化合物[3.2.1-Me₂dabco][CuCl₄]（1）和[2.2.2-NH₂dabco][CuCl₄]（2）。X射线单晶结构衍射证实化合物1和2中的无机阴离子是[CuCl₄]^2-四面体。化合物1和2表现出可逆的热致变色现象，随着温度升高，它们的颜色从黄色变为红色，这应该是由[CuCl₄]^2-四面体的变形引起的。     

Angular reconstruction of a lead scintillating-fiber sandwiched electromagnetic calorimeter

The Neighbor Cell Deposited Energy Ratio(NCDER) is a new method that is proposed to reconstruct incidence position in a single layer for a 3-dimensional imaging electromagnetic calorimeter(ECAL).This method was applied to reconstruct the ECAL test beam data for the Alpha Magnetic Spectrometer-02(AMS-02).The results show that this method can achieve an angular resolution of 7.36±0.08°/E~(1/2)(?)0.28±0.02o in the determination of the photon's direction,which is much more precise than that obtained with the commonly-adopted Center of Gravity(COG) method(8.4±0.1°/E~(1/2)(?)0.8±0.3o).Furthermore,since it uses only the properties of electromagnetic showers,this new method could also be used for other type of fine grain sampling calorimeters.     

Correction of PMT position effect for a lead-scintillating fiber electromagnetic calorimeter

The position effect of the photoelectron multiplier tube (PMT) of the electromagnetic calorimeter (ECAL) of Alpha Magnetic Spectrometer-02 (AMS-02) has been studied with beam-test data. The reconstructed deposited energy in a layer versus incidence position in the cell can be described by Gaussian distribution, maximum and minimum value can be obtained when the particle passes across the center and the edge of a cell respectively. The distribution can be used to correct the effect of incidence position on energy reconstruction. Much better energy resolution was acquired be got with the correction, for 100 GeV electrons, energy resolution improved from 3% to 2%.     

随机缺失相依函数型数据的非参数核回归估计

针对函数型非参数回归模型,基于相依数据场合,研究了模型中响应变量随机缺失的回归算子核估计问题.在一定的条件下,采用Kolmogorov熵得到了核估计量的几乎一致完全收敛速度.     

Circulation model for water circulation and purification in a water Cerenkov detector

Owing to its low cost and good transparency,highly purified water is widely used as a medium in large water Cerenkov detector experiments. The water circulation and purification system is usually needed to keep the water in good quality. In this work,a practical circulation model is built to describe the variation of the water resistivity in the circulation process and compared with the data obtained from a prototype experiment. The successful test of the model makes it useful in the future design and optimization of the circulation/purification system.     

Study of Tyvek reflectivity in water

Tyvek is widely used as the inner lining material of water Cherenkov detectors. Therefore, information about its optical properties plays an important role in the simulation and reconstruction of particles passing through water Cherenkov detectors. In this paper, a water tank experiment is performed to study the Tyvek reflectivity in water. The so-called UNIFIED model, which is an optical model of surface reflection in Geant4, is adopted to describe the Tyvek reflectivity. Two key optical parameters are obtained from a comparison between the measured data and a Monte Carlo simulation.