579 research outputs found

    Liquid ionization calorimetry: review and preview

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    Detectors for elementary particle physics

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    Response of a BGO detector to photon and neutron sources: simulations and measurements

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    In this paper Monte Carlo simulations (FLUKA) and measurements of the response of a BGO detector are reported. %For the measurements different radioactive sources were used to irradiate the BGO crystal. For the measurements three low-energy photon emitters (60Co,\left({}^{60}\rm{Co},\right. 54Mn,{}^{54}\rm{Mn}, 137Cs)\left. {}^{137}\rm{Cs}\right) were used to irradiate the BGO from various distances and angles. The neutron response was measured with an Am--Be neutron source. Simulations of the experimental irradiations were carried out. Our study can also be considered as a benchmark for FLUKA in terms of its reliability to predict the detector response of a BGO scintillator

    Classification of the LHC BLM Ionization Chamber

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    The LHC beam loss monitoring (BLM) system must prevent the super conducting magnets from quenching and protect the machine components from damage. The main monitor type is an ionization chamber. About 4000 of them will be installed around the ring. The lost beam particles initiate hadronic showers through the magnets and other machine components. These shower particles are measured by the monitors installed on the outside of the accelerator equipment. For the calibration of the BLM system the signal response of the ionization chamber is simulated in GEANT4 for all relevant particle types and energies (keV to TeV range). For validation, the simulations are compared to measurements using protons, neutrons, photons and mixed radiation fields at various energies and intensities. This paper will focus on the signal response of the ionization chamber to various particle types and energies including space charge effects at high ionization densities

    Benchmarking the Particle Background in the Large Hadron Collider Experiments

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    Background benchmarking measurements have been made to check the low-energy processes which will contribute via nuclear reactions to the radiation background in the LHC experiments at CERN. Previously these processes were only evaluated with Monte Carlo simulations, estimated to be reliable within an uncertainty factor of 2.5. Measurements were carried out in an experimental set-up comparable to the shielding of ATLAS, one of the general-purpose experiments at LHC. The absolute yield and spectral measurements of photons and neutrons emanating from the final stages of the hadronic showers were made with a Bi_4Ge_3O_{12} (BGO) detector. The particle transport code FLUKA was used for detailed simulations. Comparison between measurements and simulations show that they agree within 20% and hence the uncertainty factor resulting from the shower processes can be reduced to a factor of 1.2

    Rate effects in high-resolution drift chambers

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    The impact of high counting rates on the spatial resolution of cylindrical drift tubes is investigated in detail and the results are compared with simulations. Electronics effects and space-charge effects are quantitatively analysed. A spatial resolution of σ<80μm\sigma < 80\,\mu\mathrm{m} can be achieved even at rates as high as 1500\,Hz/cm wire length (300\,kHz per wire)

    Resolution limits of drift tubes

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    Measurements of the drift-tube response to charged particle tracks are compared with a complete simulation. The measured resolution of typically 80\,μ\mum agrees well with the simulation and allows the individual factors limiting the resolution such as diffusion, charge deposit fluctuations, gas gain fluctuations and signal processing to be studied. The results with respect to the dependence of the drift chamber resolution on gas gain, gas pressure and electronics parameters are reported

    Front-end electronics for drift tubes in a high-rate environment

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    A front-end electronics readout for drift tubes in a high-rate environment is presented. This system allows us to encode several pieces of information (leading edge time, trailing edge time, signal charge and piled-up hits from multiple tracks) into a single readout channel that is presented to the TDC. The advantage of active baseline restoration compared to bipolar signal shaping is discussed

    Dependence of Drift Tube Performance on the Anode Wire Diameter

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    Cylindrical pressurized drift tubes with different anode wire diameters wereoperated in a 170~GeV muon test beam. The dependences of spatialresolution, efficiency and streamer probability on the anode wirediameter were measured. The resolution measurements are compared with a simulation

    Design and Implementation of Community Forum System Based on MVC Model

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    随着信息技术的发展以及网络的开放性,越来越多的人通过互联网进行沟通 和在线交流,而各式各样的论坛就为上网用户提供了一个很好的线上场所,通过 搜索自己感兴趣的论坛,用户可以在论坛中发表自己的见解并与志同道合的人进 行经验的交流。而随着社区的居民的沟通变得越来越频繁,能否为他们提供一个 在线的社区论坛系统就成为了很多社区管理者面临的一个重要课题。本项目就是 在这样的背景下产生的。 本文以软件工程的设计思想为指导,通过实地的调研对需求分析做了深入的 了解,并通过用例图对需求分析进行了总结,得出了系统的功能模块以及每个功 能模块的具体功能。在需求分析的基础上,通过流程图对每个功能的具体...With the opening and development of network information technology, more and more people communicate and online communication through the Internet, and every kind of forum for Internet users to provide a good online sites, search through their interest in the forum, users can be in on the altar in the opinions of their own and with like-minded people the exchange of experiences. With the resident...学位:工程硕士院系专业:软件学院_工程硕士(软件工程)学号:X201223095
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