The electromagnetic calorimeter（ECAL） of the Alpha Magnetic Spectrometer（AMS-02） is one of the key detectors for dark matter searches. It measures the energies of electrons, positrons and photons and seperates the...The electromagnetic calorimeter（ECAL） of the Alpha Magnetic Spectrometer（AMS-02） is one of the key detectors for dark matter searches. It measures the energies of electrons, positrons and photons and seperates them from hadrons. Currently, there are 5 dead cells in the ECAL, which affect the reconstructed energy of 4.2%of total events in the ECAL acceptance. When an electromagnetic shower axis is close to the ECAL border, due to the side leakage, the reconstructed energy is affected as well. In this paper, methods for dead cells and side leakage corrections for the ECAL energy reconstruction are presented. For events with the shower axis crossing dead cells,applying dead cell correction improves the difference in the reconstructed energy from 12% to 1%, while for events near the ECAL border, with side leakage correction it is improved from 4% to 1%.展开更多
In this paper, we studied the development of hadronic shower in an electromagnetic calorimeter of Alpha Magnetic Spectrometer Ⅱ. Two parametrized empirical formulae were proposed to describe the hadronic shower shape...In this paper, we studied the development of hadronic shower in an electromagnetic calorimeter of Alpha Magnetic Spectrometer Ⅱ. Two parametrized empirical formulae were proposed to describe the hadronic shower shape in calorimeter. Using 100 GeV proton beam incident on the center of the ECAL, detailed plots of lateral and longitudinal hadronic shower behavior were given and we found the formulae can describe the development of the hadronic shower with the test beam data. The possible application of the parametrized formulae including e±-π± discrimination and tau jet reconstruction was discussed.展开更多
We develop an empirical formula to parameterize the 3-dimension （3D） distribution of electromagnetic showers in the Alpha Magnetic Spectrometer Ⅱ electromagnetic calorimeter（ECAL）. The formula was verified by ECA...We develop an empirical formula to parameterize the 3-dimension （3D） distribution of electromagnetic showers in the Alpha Magnetic Spectrometer Ⅱ electromagnetic calorimeter（ECAL）. The formula was verified by ECAL test beam data in 2002 and found to perform well. The distribution of electron showers in the ECAL are well described by the formula, which has parameters that allow one to determine the 3D shape of electromagnetic showers in the ECAL. We use this formula to correct for lateral energy leakage and dead channels in the ECAL; good results are obtained.展开更多
The DArk Matter Particle Explorer is an orbital indirect dark matter search experiment which measures the spectra of photons, electrons and positrons originating from deep space. The electromagnetic calorimeter （ECAL...The DArk Matter Particle Explorer is an orbital indirect dark matter search experiment which measures the spectra of photons, electrons and positrons originating from deep space. The electromagnetic calorimeter （ECAL）, made of bisnmth germinate （BGO）, is one of tile key sub-detectors of DAMPE, and is designed for energy measurement with a large dynamic range from 5 GeV to 10 TeV. In this paper, methods for energy correction are discussed, in order to reconstruct the primary energy of the incident electrons. Different methods are chosen for the appropriate energy ranges. The correction results of Geant4 simulation and beam test data （at CERN） are presented.展开更多
Silicon photomultipliers （SiPMs） have remarkable advantages for use in photo-detection. Compared with PMT, SiPM shows advantages of high gain, excellent time resolution, insensitivity to magnetic fields and a lower ...Silicon photomultipliers （SiPMs） have remarkable advantages for use in photo-detection. Compared with PMT, SiPM shows advantages of high gain, excellent time resolution, insensitivity to magnetic fields and a lower operating voltage. SiPMs from Hamamatsu are used in the electromagnetic calorimeter （ECAL） sub-detector in the Positron Electron Balloon Spectrometer （PEBS） experiment, a balloon-borne spectrometer experiment aiming at the precise measurement of the cosmic-ray positron fraction. This paper introduces the evaluation and test results of several SiPM detector types, the dedicated front-end application specific integrated circuit （ASIC） electronics and the design of the data acquisition system （DAQ） system.展开更多
Purpose The distributions of energy responses of helium measured by the electromagnetic calorimeter(ECAL)of Alpha Magnetic Spectrometer(AMS-02)in Monte-Carlo do not agree with those in real data,thus using energy resp...Purpose The distributions of energy responses of helium measured by the electromagnetic calorimeter(ECAL)of Alpha Magnetic Spectrometer(AMS-02)in Monte-Carlo do not agree with those in real data,thus using energy response matrix obtained from Monte-Carlo to measure the cosmic ray helium spectrum is not correct.Therefore,the spectrum measured with ECAL based on raw Monte-Carlo would be different from the real one.The purpose is to correct the response matrix to measure helium spectrum with ECAL.Methods The energy measured by ECAL of AMS-02 provides in-flight correction for the energy response matrix in Monte-Carlo.Results The spectrum based on corrected response matrix is consistent with the AMS collaboration published result.Conclusions It is feasible to measure helium spectrum with ECAL with corrected energy response matrix.展开更多
Background The circular electron positron collider(CEPC)was proposed as a future Higgs/Z factory.A sampling calo-rimeter with scintillator-tungsten sandwich structure(ScW)is selected as one of the electromagnetic calo...Background The circular electron positron collider(CEPC)was proposed as a future Higgs/Z factory.A sampling calo-rimeter with scintillator-tungsten sandwich structure(ScW)is selected as one of the electromagnetic calorimeter(ECAL)options.Its active layers consist of plastic scintillator strip units with a thickness of 2 mm and a size of 5×45 mm2,read out by silicon photomultipliers(SiPM).Purpose The light output has non-uniformity along the length direction of the scintillator strip,which affects the resolution of the ScW ECAL.It is necessary to control the non-uniformity to a low level.Methods We present the optimization of the scintillator units to improve the uniformity of the light output,including the light output distribution of the scintillator strips with different SiPM coupling configurations,and the impact of the coupling groove shape and dimension on the light output uniformity.Results and conclusion The results show that the non-uniformity of the scintillator unit with a runway-shaped coupling groove at the bottom-center of the strip can achieve 4%without reduction in the light output.Compared to the case of non-uniformity before optimization,the optimized uniformity improves the boson mass resolution about 23%based on the reconstruction of Higgs→γγ,which is comparable to the perfect homogeneous case.展开更多
目的:通过模拟不同剂量分割方式照射食管癌细胞Eca109,观察比较各组别凋亡相关基因肿瘤坏死因子(tumor necrosis factor,TNF)和死亡结构域沉默子(silencer of death domains,SODD)的各组别表达差异并分析原因及意义,尝试为临床实施的非...目的:通过模拟不同剂量分割方式照射食管癌细胞Eca109,观察比较各组别凋亡相关基因肿瘤坏死因子(tumor necrosis factor,TNF)和死亡结构域沉默子(silencer of death domains,SODD)的各组别表达差异并分析原因及意义,尝试为临床实施的非常规放疗提供潜在基础理论依据。方法:设计具有相同BED的4种剂量分割模式,照射处于指数生长期的Eca109细胞后,RT-PCR检测各组TNF mRNA和SODD mRNA表达变化,Western Blot检测各组TNF蛋白和SODD蛋白表达变化。结果:各组TNF mRNA及蛋白的表达量均数差值比较,有显著性差异;各组SODD mRNA及蛋白的表达均数差值比较,有统计学意义。结论:模拟照射各组中超分割组TNF mRNA表达上调幅度最大,SODD mRNA上调幅度亦最大。提示在射线诱导肿瘤细胞以某种方式走向死亡过程中,存在着促凋亡基因和抗凋亡基因之间的博弈。模拟照射各组中TNF蛋白和SODD蛋白均大部分下调,提示除DNA是射线的主要损伤靶点外,射线对其他细胞器的损伤作用亦不容忽视,因为它们的功能状态可能影响到蛋白质的合成。展开更多
Background The electromagnetic calorimeter(ECAL)of the Alpha Magnetic Spectrometer(AMS-02)measures the energy of electrons/positrons and separates them from protons.Currently,there are five dead cells in the ECAL whic...Background The electromagnetic calorimeter(ECAL)of the Alpha Magnetic Spectrometer(AMS-02)measures the energy of electrons/positrons and separates them from protons.Currently,there are five dead cells in the ECAL which affect the reconstructed energy of particles.The particle identification power of the ECAL decreases when particles pass through these dead cells or close to the ECAL border.Purpose To improve the ECAL particle identification for particles pass through these dead cells or close to the ECAL border.Methods An improved ECAL particle identification estimator using the electromagnetic shower shape is developed with dead cell and side leakage corrections.Results For events passing through dead cells,with this new estimator,the proton rejection power is improved by a factor of 2.2 and positron purity is improved from 31 to 50%in the energy range of 500–800 GeV.Conclusion The new estimator works well for event passing through dead cells or close to the ECAL border.展开更多
基金Supported by National Natural Science Foundation of China(11220101004)
文摘The electromagnetic calorimeter（ECAL） of the Alpha Magnetic Spectrometer（AMS-02） is one of the key detectors for dark matter searches. It measures the energies of electrons, positrons and photons and seperates them from hadrons. Currently, there are 5 dead cells in the ECAL, which affect the reconstructed energy of 4.2%of total events in the ECAL acceptance. When an electromagnetic shower axis is close to the ECAL border, due to the side leakage, the reconstructed energy is affected as well. In this paper, methods for dead cells and side leakage corrections for the ECAL energy reconstruction are presented. For events with the shower axis crossing dead cells,applying dead cell correction improves the difference in the reconstructed energy from 12% to 1%, while for events near the ECAL border, with side leakage correction it is improved from 4% to 1%.
基金Supported by National Natural Science Foundation of China (10435070,10721140381,10099630)China Ministry of Science and Technology (2007CB16101)Chinese Academy of Sciences (KJCX2-N17,1730911111)
文摘In this paper, we studied the development of hadronic shower in an electromagnetic calorimeter of Alpha Magnetic Spectrometer Ⅱ. Two parametrized empirical formulae were proposed to describe the hadronic shower shape in calorimeter. Using 100 GeV proton beam incident on the center of the ECAL, detailed plots of lateral and longitudinal hadronic shower behavior were given and we found the formulae can describe the development of the hadronic shower with the test beam data. The possible application of the parametrized formulae including e±-π± discrimination and tau jet reconstruction was discussed.
基金Supported by NSFS(10099630),International S&T Collaboration Key Program,Ministry of Science and Technology of China
文摘We develop an empirical formula to parameterize the 3-dimension （3D） distribution of electromagnetic showers in the Alpha Magnetic Spectrometer Ⅱ electromagnetic calorimeter（ECAL）. The formula was verified by ECAL test beam data in 2002 and found to perform well. The distribution of electron showers in the ECAL are well described by the formula, which has parameters that allow one to determine the 3D shape of electromagnetic showers in the ECAL. We use this formula to correct for lateral energy leakage and dead channels in the ECAL; good results are obtained.
基金Supported by the Chinese 973 Program(2010CB833002)the Strategic Priority Research Program on Space Science of the Chinese Academy of Science(XDA04040202-4)100 Talents Program of CAS
文摘The DArk Matter Particle Explorer is an orbital indirect dark matter search experiment which measures the spectra of photons, electrons and positrons originating from deep space. The electromagnetic calorimeter （ECAL）, made of bisnmth germinate （BGO）, is one of tile key sub-detectors of DAMPE, and is designed for energy measurement with a large dynamic range from 5 GeV to 10 TeV. In this paper, methods for energy correction are discussed, in order to reconstruct the primary energy of the incident electrons. Different methods are chosen for the appropriate energy ranges. The correction results of Geant4 simulation and beam test data （at CERN） are presented.
文摘Silicon photomultipliers （SiPMs） have remarkable advantages for use in photo-detection. Compared with PMT, SiPM shows advantages of high gain, excellent time resolution, insensitivity to magnetic fields and a lower operating voltage. SiPMs from Hamamatsu are used in the electromagnetic calorimeter （ECAL） sub-detector in the Positron Electron Balloon Spectrometer （PEBS） experiment, a balloon-borne spectrometer experiment aiming at the precise measurement of the cosmic-ray positron fraction. This paper introduces the evaluation and test results of several SiPM detector types, the dedicated front-end application specific integrated circuit （ASIC） electronics and the design of the data acquisition system （DAQ） system.
基金funding was provided by China Sponsorship Council(Grant Number:202004910534).
文摘Purpose The distributions of energy responses of helium measured by the electromagnetic calorimeter(ECAL)of Alpha Magnetic Spectrometer(AMS-02)in Monte-Carlo do not agree with those in real data,thus using energy response matrix obtained from Monte-Carlo to measure the cosmic ray helium spectrum is not correct.Therefore,the spectrum measured with ECAL based on raw Monte-Carlo would be different from the real one.The purpose is to correct the response matrix to measure helium spectrum with ECAL.Methods The energy measured by ECAL of AMS-02 provides in-flight correction for the energy response matrix in Monte-Carlo.Results The spectrum based on corrected response matrix is consistent with the AMS collaboration published result.Conclusions It is feasible to measure helium spectrum with ECAL with corrected energy response matrix.
基金supported by National Key Programme for S&T Research and Development(Grant No.2016YFA0400400)National Natural Science Foundation of China(Grant No.11675196)supported in part by the CAS Centre for Excellence in Particle Physics(CCEPP)
文摘Background The circular electron positron collider(CEPC)was proposed as a future Higgs/Z factory.A sampling calo-rimeter with scintillator-tungsten sandwich structure(ScW)is selected as one of the electromagnetic calorimeter(ECAL)options.Its active layers consist of plastic scintillator strip units with a thickness of 2 mm and a size of 5×45 mm2,read out by silicon photomultipliers(SiPM).Purpose The light output has non-uniformity along the length direction of the scintillator strip,which affects the resolution of the ScW ECAL.It is necessary to control the non-uniformity to a low level.Methods We present the optimization of the scintillator units to improve the uniformity of the light output,including the light output distribution of the scintillator strips with different SiPM coupling configurations,and the impact of the coupling groove shape and dimension on the light output uniformity.Results and conclusion The results show that the non-uniformity of the scintillator unit with a runway-shaped coupling groove at the bottom-center of the strip can achieve 4%without reduction in the light output.Compared to the case of non-uniformity before optimization,the optimized uniformity improves the boson mass resolution about 23%based on the reconstruction of Higgs→γγ,which is comparable to the perfect homogeneous case.
文摘Background The electromagnetic calorimeter(ECAL)of the Alpha Magnetic Spectrometer(AMS-02)measures the energy of electrons/positrons and separates them from protons.Currently,there are five dead cells in the ECAL which affect the reconstructed energy of particles.The particle identification power of the ECAL decreases when particles pass through these dead cells or close to the ECAL border.Purpose To improve the ECAL particle identification for particles pass through these dead cells or close to the ECAL border.Methods An improved ECAL particle identification estimator using the electromagnetic shower shape is developed with dead cell and side leakage corrections.Results For events passing through dead cells,with this new estimator,the proton rejection power is improved by a factor of 2.2 and positron purity is improved from 31 to 50%in the energy range of 500–800 GeV.Conclusion The new estimator works well for event passing through dead cells or close to the ECAL border.
