1,321 research outputs found

    Macro-microscopic mass formulae and nuclear mass predictions

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    Different mass formulae derived from the liquid drop model and the pairing and shell energies of the Thomas-Fermi model have been studied and compared. They include or not the diffuseness correction to the Coulomb energy, the charge exchange correction term, the curvature energy, different forms of the Wigner term and powers of the relative neutron excess I = (N − Z)/A. Their coefficients have been determined by a least square fitting procedure to 2027 experimental atomic masses [1]. The Coulomb diffuseness correction Z2/A term or the charge exchange correction Z4/3/A1/3 term plays the main role to improve the accuracy of the mass formula. The Wigner term and the curvature energy can also be used separately but their coefficients are very unstable. The different fits lead to a surface energy coefficient of around 17-18 MeV. A large equivalent rms radius (r0 = 1.22−1.24 fm) or a shorter central radius may be used. A rms deviation of 0.54 MeV can be reached between the experimental and theoretical masses. The remaining differences come probably mainly from the determination of the shell and pairing energies. Mass predictions of selected expressions have been compared to 161 new experimental masses and the correct agreement allows to provide extrapolations to masses of 656 selected exotic nuclei

    On the liquid drop model mass formulas and alpha decay of the heaviest nuclei

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    International audienceThe coefficients of different macro-microscopic Liquid Drop Model mass formulas have been determined by a least square fitting procedure to 2027 experimental atomic masses. A rms deviation of 0.54 MeV can be reached. The remaining differences come mainly from the determination of the shell and pairing energies. Extrapolations are compared to 161 new experimental masses and to 656 mass evaluations. The different fits lead to a surface energy coefficient of around 17-18 MeV. Finally, alpha decay potential barriers are revisited and predictions of alpha decay half-lives of still unknown superheavy elements are given from previously proposed analytical formulas and from extrapolated Qalpha values

    Mass predictions of exotic nuclei within a macro-microscopic model

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    International audienceDifferent Liquid Drop Model mass formulae have been studied. They include a Coulomb diffuseness correction Z2/A term and pairing and shell energies of the Thomas-Fermi model. The influence of the selected charge radius, the curvature energy and different forms of the Wigner term has been investigated. Their coefficients have been determined by a least square fitting procedure to 2027 experimental atomic masses. The different fits lead to a surface energy coefficient of 17-18 MeV. A large equivalent rms radius (r0 = 1.22 − 1.24 fm) or a shorter central radius may be used. A rms deviation of 0.54 MeV can be reached between the experimental and theoretical masses. The remaining differences come from the determination of the shell and pairing energies. Mass predictions are given for exotic nuclei

    Inclusive photon production at forward rapidities in proton-proton collisions at s\sqrt{s} = 0.9, 2.76 and 7 TeV

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    See paper for full list of authors – 24 pages, 10 captioned figures, 4 tables, authors from page 19, figures at http://aliceinfo.cern.ch/ArtSubmission/node/1024International audienceThe multiplicity and pseudorapidity distributions of inclusive photons have been measured at forward rapidities (2.3<η<3.92.3 < \eta < 3.9) in proton-proton collisions at three center-of-mass energies, s=0.9\sqrt{s}=0.9, 2.76 and 7 TeV using the ALICE detector. It is observed that the increase in the average photon multiplicity as a function of beam energy is compatible with both a logarithmic and a power-law dependence. The relative increase in average photon multiplicity produced in inelastic pp collisions at 2.76 and 7 TeV center-of-mass energies with respect to 0.9 TeV are 37.2% ±\pm 0.3% (stat) ±\pm 8.8% (sys) and 61.2% ±\pm 0.3% (stat) ±\pm 7.6% (sys), respectively. The photon multiplicity distributions for all center-of-mass energies are well described by negative binomial distributions. The multiplicity distributions are also presented in terms of KNO variables. The results are compared to model predictions, which are found in general to underestimate the data at large photon multiplicities, in particular at the highest center-of-mass energy. Limiting fragmentation behavior of photons has been explored with the data, but is not observed in the measured pseudorapidity range

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð„with constraintsð ð ð„ „ ðandðŽð„ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

    Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks