Three dimensional parametrization of electromagnetic shower in Alpha Magnetic Spectrometer Ⅱ ECAL

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.     

A study of hadronic shower development in the ECAL of the alpha magnetic spectrometer Ⅱ

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.     

用最小电离的质子刻度铅–闪烁光纤夹层电磁量能器

研究利用最小电离的质子和已知能量的电子来刻度铅–闪烁光纤夹层电磁量能器.对最小电离粒子输出响应进行光纤衰减修正后,利用最小电离质子的输出响应对量能器测量单元进行标定,然后对不同入射能量的电子事例进行能量重建,重建能量与入射能量有很好的线性关系.本文还对最小电离的质子与μ子对量能器测量单元的输出响应进行了比较,发现二者在误差范围内是一致的.     

A study of hadronic shower development in the ECAL of the alpha magnetic spectrometer Ⅱ

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.     

Longitudinal development of electromagnetic showers in directional spectrometer

The length of the longitudinal development of the electromagnetic shower induced by electrons with an energy of 26 GeV in a directional spectrometer consisting of a crystalline tungsten converter oriented along the ??111?? axis and a composite Cherenkov shower spectrometer is shorter in comparison with the length of the standard shower development by 20?C30% at a converter thickness from 2.7 to 8.4 mm.     

Energy correction for the BGO calorimeter of DAMPE using an electron beam

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 bismuth germinate(BGO),is one of the 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.     

Design, performance, and calibration of?the?CMS?hadron-outer?calorimeter

The Outer Hadron Calorimeter (HCAL HO) of the CMS detector is designed to measure the energy that is not contained by the barrel (HCAL HB) and electromagnetic (ECAL EB) calorimeters. Due to space limitation the barrel calorimeters do not contain completely the hadronic shower and an outer calorimeter (HO) was designed, constructed and inserted in the muon system of CMS to measure the energy leakage. Testing and calibration of the HO was carried out in a 300 GeV/c test beam that improved the linearity and resolution. HO will provide a net improvement in missing E _T measurements at LHC energies. Information from HO will also be used for the muon trigger in CMS. Deceased. Now at University of Pennsylvania, Philadelphia, PA, USA. At Niğde University, Niğde, Turkey. At Marmara University, Istanbul, Turkey. At Kafkas University, Kars, Turkey. At Süleyman Demirel University, Isparta, Turkey. At Mersin University, Mersin, Turkey. At Izmir Yüksek Teknoloji Enstitüsü, Izmir, Turkey.     

Detection of high-energy electrons by a directional spectrometer

A method for the detection of 26- and 28-GeV electrons by a directional spectrometer based on oriented tungsten, tungstate, and garnet crystals has been reported. In spite of an anomalous character of the development of an electromagnetic shower at the initial stage in a crystal oriented along the 〈111〉 axis, the relative energy release of the shower in the spectrometer behind the crystal at the final stage is described by the standard dependence of the development of the electromagnetic shower.     

BEPCⅡ激光丝系统探测器模拟研究(英文)

BEPCⅡ上正在进行激光丝系统的研究。基于GEANT4对激光丝系统探测器进行了模拟。首先模拟了康普顿散射信号在探测器材料中电磁簇射的分布,确定了探测器初始尺寸。之后模拟了不同尺寸下探测器的输出,根据模拟结果确定了探测器的最终尺寸,使得探测器在所确定的尺寸有较大的信号输出。还进行了不同康普顿散射位置时探测器的响应模拟,结果表明束流管道的影响是不可忽略的,是探测器响应非线性的主要原因,预计该结果对束流截面测量有重要意义。最后简要介绍了BEPCⅡ几种可能的束流能量时,探测器信号输出和能量泄漏的模拟结果。     

Energy‐dependent dead‐time correction in digital pulse processors applied to silicon drift detector's X‐ray spectra

Dead‐time effects in X‐ray spectra taken with a digital pulse processor and a silicon drift detector were investigated when the number of events at the low‐energy end of the spectrum was more than half of the total, at counting rates up to 56 kHz. It was found that dead‐time losses in the spectra are energy dependent and an analytical correction for this effect, which takes into account pulse pile‐up, is proposed. This and the usual models have been applied to experimental measurements, evaluating the dead‐time fraction either from the calculations or using the value given by the detector acquisition system. The energy‐dependent dead‐time model proposed fits accurately the experimental energy spectra in the range of counting rates explored in this work. A selection chart of the simplest mathematical model able to correct the pulse‐height distribution according to counting rate and energy spectrum characteristics is included.     

Muon Content of Extensive Air Showers: Comparison of the Energy Spectra Obtained by the Sydney University Giant Air-Shower Recorder and by the Pierre Auger Observatory

The Sydney University Giant Air-shower Recorder(SUGAR) measured the energy spectrum of ultra-high-energy cosmic rays reconstructed from muon detector reading. Comparison of their spectra SUGAR and Pierre Auger Observatory allows us to reconstruct the empirical dependence of the number of muons in a vertical shower on the primary energy for energies between 1017 and 1018 eV. We compared this dependence with the predictions of hadronic interaction models QGSJET-II-04, EPOS-LHC and SIBYLL-2.3c. In addition, we analyzed the response of the array of muon detectors in order to determine the slope of the muon lateral distribution function. It is important to understand how much the number of muons differs from the predictions of modeling at different distances from the shower axis.     

Cascade showers in the NEVOD Cherenkov water detector

A technique for measuring the cascade shower energy in the NEVOD Cherenkov water detector with a spatial lattice of quasi-spherical modules is discussed. The technique allows the number of cascade particles that move near the shower axis to be reconstructed on the basis of analysis of response amplitudes of triggered photomultiplier tubes. The technique of cascade-curve reconstruction was applied to cascade showers generated by near-horizontal high-energy muons extracted by means of the DECOR coordinate-tracking detector arranged around the Cherenkov water detector. The first results of measuring the energy spectrum of cascade showers of 10–1000 GeV are presented.     

Estimation of the parameters of the cascade curve of electromagnetic shower development in a spectrometer with oriented crystal converter

Based on the experimental results on the development of electromagnetic showers from 26-GeV electrons in misoriented and oriented along the 〈111〉 axis tungsten crystals 2.7, 5.8, 8.4mm thick and then in a composite Cherenkov shower spectrometer, the parameters of the cascade curve of shower development in a spectrometer with 1-mm tungsten crystal converter were estimated.     

Simulation of electromagnetic shower formation in a Germanium crystal

Abstract

When high-energy electrons penetrate crystalline matter, the successive processes of photon emission and pair production form an electromagnetic shower. If the incident electrons are directed along the crystal axis, the cross section for photon emission is drastically enhanced because electrons in ‘channeling’ states feel a strong electric field continuously. Experiments designed to detect this effect were performed at CERN. The results showed an anomalous peak in the energy loss spectrum of the emerging electrons. In this paper, we report results of a Monte-Carlo simulation of shower formation in a Germanium crystal. Our results agree with the experimental data more quantitatively than previous simulations. We simulated a shower formation by incident photons as well.     

Effect of oriented crystalline converter temperature on spectrometer response

Cooling of a 1-mm crystalline tungsten converter oriented along the ??111?? axis situated in front of an electromagnetic spectrometer of thickness 25X ₀, recording showers of 28-GeV electrons, to a temperature of 77 K results in a decrease of the crystal radiation length by ??30%, shifts the cascade curve of the shower development in the spectrometer by ??7%, and improves the spectrometer energy resolution by ??5% in comparison with similar parameters of the spectrometer at a crystal temperature of 293 K.     

Restoration of parameters of high-energy cascades in Cherenkov water calorimeter with a dense array of quasispherical modules

A problem concerning the restoration of the parameters of a cascade shower with an unknown axis originating by muons in a Cherenkov water calorimeter is considered. A method for estimating the direction and geometric position of the cascade’s axis, which is based on the analysis of responses of quasispherical modules, and the criteria of selection of the events with cascades among the events with a large energy liberation are proposed. The method and the criteria are tested on events with cascades generated by near-horizontal muons of high energies detected by a DECOR coordinate-track detector. The preliminary results of measurements of the energy spectrum of cascade showers are presented.     

Design, performance, and calibration of CMS forward calorimeter wedges

We report on the test beam results and calibration methods using high energy electrons, pions and muons with the CMS forward calorimeter (HF). The HF calorimeter covers a large pseudorapidity region (), and is essential for a large number of physics channels with missing transverse energy. It is also expected to play a prominent role in the measurement of forward tagging jets in weak boson fusion channels in Higgs production. The HF calorimeter is based on steel absorber with embedded fused-silica-core optical fibers where Cherenkov radiation forms the basis of signal generation. Thus, the detector is essentially sensitive only to the electromagnetic shower core and is highly non-compensating (e/h≈5). This feature is also manifest in narrow and relatively short showers compared to similar calorimeters based on ionization. The choice of fused-silica optical fibers as active material is dictated by its exceptional radiation hardness. The electromagnetic energy resolution is dominated by photoelectron statistics and can be expressed in the customary form as . The stochastic term a is 198% and the constant term b is 9%. The hadronic energy resolution is largely determined by the fluctuations in the neutral pion production in showers, and when it is expressed as in the electromagnetic case, a = 280% and b = 11%.     

Employing cherenkov radiation and fluorescence light in calibrating the energy of giant air showers

A classic procedure for estimating the energy of giant air showers in terms of the parameter s(600) (density of energy deposition in a scintillator at a distance of 600 m from the shower axis) is analyzed on the basis of the model of quark-gluon strings. A simulation of the signal s(600) by means of the CORSIKA code leads to estimates of energy that are approximately 1.6 times lower than those adopted at the Yakutsk array. Estimates of energy on the basis of Cherenkov radiation agree with experimental data within the errors. Calculations of the distributions of energy deposited in the atmosphere indicate that more than 20% of this energy can be deposited at distances in excess of 100 m from the shower axis.     

Application of the parametric formulae for electromagnetic showers in unconverted γ/π0 discrimination

In the LHC experiment,the neutral pions produced during jet fragmentation are the background sources for all physics channels with high-energy photons in their final state.In this paper,the application of the three-dimensional parametric formula for electromagnetic(EM)showers,which we developed in the Alpha Magnetic Spectrometer Ⅱ experiment,is presented to distinguish the unconverted photons from the neutral pions.With the constructed electromagnetic calorimeter(ECAL)in a GEANT4 simulation,the parametric formulae were validated and the unconverted γ/π0 discrimination was performed with the Toolkit for Multivariate Data Analysis(TMVA)package in ROOT for different transverse energies ranging from 15 GeV to75 GeV,which is the most sensitive region for light Higgs(with mass～120 GeV)searches with the channel H→γγ.With this discrimination method and the selected transverse energy region,we can reject π0 with the efficiency from～40%(65-75 GeV)to～90%(15-25 GeV)when keeping 90% γefficiency.