744 research outputs found

    Fabrication and Characterisation of 3D Diamond Pixel Detectors With Timing Capabilities

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    Diamond sensors provide a promising radiation hard solution to the challenges posed by the future experiments at hadron machines. A 3D geometry with thin columnar resistive electrodes orthogonal to the diamond surface, obtained by laser nanofabrication, is expected to provide significantly better time resolution with respect to the extensively studied planar diamond sensors. We report on the development, production, and characterisation of innovative 3D diamond sensors achieving 30% improvement in both space and time resolution with respect to sensors from the previous generation. This is the first complete characterisation of the time resolution of 3D diamond sensors and combines results from tests with laser, beta rays and high energy particle beams. Plans and strategies for further improvement in the fabrication technology and readout systems are also discussed

    Spectroscopy of 98Ru

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    The nucleus 98 Ru has been investigated by means of γ - γ coincidence, γ - γ angular correlation and K-internal conversion coefficient measurements. The results have led to spin-parity assignment to several levels and to the determination of E 2/ M 1 mixing ratios for the most intense transitions

    Search for heavy neutral lepton production in K+ decays

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    A search for heavy neutral lepton production in K + decays using a data sample collected with a minimum bias trigger by the NA62 experiment at CERN in 2015 is reported. Upper limits at the 10−7 to 10−6 level are established on the elements of the extended neutrino mixing matrix |Ue4| 2 and |Uμ4| 2 for heavy neutral lepton mass in the ranges 170–448 MeV/c2 and 250–373 MeV/c2, respectively. This improves on the previous limits from HNL production searches over the whole mass range considered for |Ue4|2 and above 300 MeV/c2 for |Uμ4|2

    A Probe into the Reform of Public Calligraphy Course in Chinese Colleges and Universities

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    中国书法是中国传统文化中的瑰宝,它既是一门艺术,又有着深厚的文化内涵。我国普通高校开设公共书法教学是与目前倡导的素质教育,培养创新型人才,提倡人的全面和谐发展的高等教育理念相一致的。加强高校公共书法教育,是全面推进素质教育的有效途径之一,也是提高当代大学生人文素质的重要手段。它对促进大学生人格完善、创造力培养以及民族文化的传承等有着不可低估的作用。本文主要针对我国普通高等院校公共书法教学现状进行分析,并由此比较借鉴日本高校中实施书法教学的成功经验提出对我国高校公共书法教学改革的具体建议和措施,设计并实践一种具备学科视野的、以学生为主体的公共书法教学的新模式。论文共分为五部分。引言扼要介绍论文写...Chinese calligraphy is a treasure of Chinese traditional culture. It not only is an art, but also has profound culture contents. Opening the public calligraphy course to the university students is in accordance with the concept that advocated by the current quality- oriented education, which aims to cultivate the students’ creative talent and comprehensive development. This paper concentrates on a...学位:文学硕士院系专业:艺术教育学院美术系_美术学学号:20042201

    Precise tests of low energy QCD from Ke4 decay properties

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    We report results from the analysis of the K\ub1 \u2192 pi+ pi 12 e\ub1 \u3bd (Ke4 ) decay by the NA48/2 collaboration at the CERN SPS, based on the total statistics of 1.13 million decays collected in 2003\u20132004. The hadronic form factors in the S- and P-wave and their variation with energy are obtained. The phase difference between the S- and P-wave states of the pion pion system is accurately measured and allows a precise determination of a00 and a02 , the I = 0 and I = 2 S-wave pion pion scattering lengths: a00 = 0.2220 \ub1 0.0128stat \ub1 0.0050syst \ub1 0.0037th , a02 = 120.0432 \ub1 0.0086stat \ub1 0.0034syst \ub1 0.0028th . Combination of this result with the other NA48/2 measurement obtained in the study of K\ub1 \u2192 pi0 pi0 pi\ub1 decays brings an improved determination of a00 and the first precise experimental measurement of a02, providing a stringent test ofChiral Perturbation Theory predictions and lattice QCD calculations. Using constraints based on analyticity and chiral symmetry, even more precise values are obtained: a00 = 0.2196 \ub1 0.0028stat \ub1 0.0020syst and a02 = 120.0444 \ub10.0007stat \ub1 0.0005syst \ub1 0.0008ChPT

    Measurement of K0e3 form factors

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    The semileptonic decay of the neutral K meson, K0L → π± e∓ ν (Ke3 ), was used to study the strangeness-changing weak interaction of hadrons. A sample of 5.6 million reconstructed events recorded by the NA48 experiment was used to measure the Dalitz plot density. Admitting all possible Lorentz-covariant couplings, the form factors for vector (f+(q2)), scalar (fS) and tensor (fT) interactions were measured. The linear slope of the vector form factor λ+ = 0.0284 ± 0.0007 ± 0.0013 and values for the ratios |fS/f+(0)| = 0.015 +0.007-0.010 ± 0.012 and |fT/f+(0)| = 0.05 +0.03-0.04 ± 0.03 were obtained. The values for fS and fT are consistent with zero. Assuming only vector–axial-vector couplings, λ+ = 0.0288 ± 0.0004 ± 0.0011 and a good fit consistent with pure V–A couplings were obtained. Alternatively, a fit to a dipole form factor yields a pole mass of M = 859 ± 18 MeV, consistent with the K∗(892) mass

    Measurement of the radiative Ke3 branching ratio

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    We present a measurement of the relative branching ratio of the decay K0 → π± e± νγ (Ke3γ) with respect to K0 → π± e± ν (Ke3 + Ke3γ ) decay. The result is based on observation of 19 000 Ke3γ and 5.6 × 10^6 Ke3 decays. The value of the branching ratio is BR(K0e3γ , E∗γ > 30 MeV, θ∗eγ > 20◦)/ Br(K0e3 ) = (0.964 ± 0.008+0.011-0.009)%. This result agrees with theoretical predictions but is at variance with a recently published result
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