164 research outputs found

    A comparative study of super- and highly-deformed bands in the A ~ 60 mass region

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    Super- and highly-deformed rotational bands in the A ~ 60 mass region are studied within cranked relativistic mean field theory and the configuration-dependent shell-correction approach based on the cranked Nilsson potential. Both approaches describe the experimental data well. Low values of the dynamic moments of inertia J^(2) compared with the kinematic moments of inertia J^(1) seen both in experiment and in calculations at high rotational frequencies indicate the high energy cost to build the states at high spin and reflect the limited angular momentum content in these configurations.Comment: 11 pages, 4 PostScript figures, Latex, uses 'epsf', submitted to Phys. Lett.

    Time-odd mean fields in the rotating frame: microscopic nature of nuclear magnetism

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    The microscopic role of nuclear magnetism in rotating frame is investigated for the first time in the framework of the cranked relativistic mean field theory. It is shown that nuclear magnetism modifies the expectation values of single-particle spin, orbital and total angular momenta along the rotational axis effectively creating additional angular momentum. This effect leads to the increase of kinematic and dynamic moments of inertia at given rotational frequency and has an impact on effective alignments.Comment: 16 pages, 4 figures, submitted to Physical Review

    Recent progress in the study of fission barriers in covariant density functional theory

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    Recent progress in the study of fission barriers of actinides and superheavy nuclei within covariant density functional theory is overviewed.Comment: 10 pages, 5 figures. In press in International Journal of Modern Physics

    УГОИТЕЛНИ СПОСОБНОСТИ И КАЧЕСТВО НА МЕСОТО ПРИ ЯПОНСКИ ПЪДПЪДЪЦИ ОТ ПОРОДИТЕ “ФАРАОН” И “БЕЛИ АНГЛИЙСКИ”

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    The aim of the study was to establish the fatting capacity and the meat quality of the combined (meat+eggs) White English breed and to compare with the same of the meat Faraon breed. Logically, the live weight of 31-day old male Faraon-birds was by 5,9 % higher and of the female ones – by 7,9 % compared to the birds of White English breed. Feed conversion ratio for the experimental period (3-31 days) for the White English quails was to 9,95% less effective, compared to the Faraon birds. The meat of Faraon quails contained more dry matter and protein compared to the meat of White English breed. Fat content in the quail bodies of White English breed was signifi cantly lower compared to Faraon breed /Р≤0,05/. Quail meat of White English breed was characterized by its better capacity for technological processing due to the lower loss of moisture – by 18,8 % for breast and 22,4 % for leg muscles /Р≤0,05/. The established results characterize the combined White English breed as suitable for producing both of eggs and meat from quails.Целта на изследването е да се проучат угоителните способности и качеството на месото на месо-яйчната порода Бели английски, като се сравни с това на използваната в целия свят специализирана месодайна порода Фараон. Логично на 31-дневна възраст живата маса на мъжките птици от породата Фараон е била с 5,9% по- висока, а при женските - със 7,9% в сравнение с птиците от породата Бели английски. Средно за опитния период (3-31 дни), конверсията на фураж при птиците от породата Бели английски е била с 9,95% по-неефективна в сравнение с тази при месодайната порода Фараон. Месото на птиците от породата Фараон е по-богато на сухи вещества и протеин - съответно с 8% при гръдната и 8,5% при крачната мускулатура сухи вещества и с 3,2% при гръдната и 4,6% при крачната мускулатура протеин. Съдържанието на мазнини в трупчета от породата Бели английски е достоверно по-ниско в сравнение с трупчетата на породата Фараон /Р≤0,05/. Месото на пъдпъдъците от породата Бели английски се характеризира с по-добра пригодност за технологична преработка, поради по-ниската загуба на влага – с 18,8% за гръдната и с 22,4% за крачната мускулатура / Р≤0,05/. Получените резултати характеризират породата Бели английски като подходяща за производство на яйца и месо от японски пъдпъдъци

    Moments of Inertia of Nuclei in the Rare Earth Region: A Relativistic versus Non-Relativistic Investigation

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    A parameter free investigation of the moments of inertia of ground state rotational bands in well deformed rare-earth nuclei is carried out using Cranked Relativistic Hartree-Bogoliubov (CRHB) and non-relativistic Cranked Hartree-Fock-Bogoliubov (CHFB) theories. In CRHB theory, the relativistic fields are determined by the non-linear Lagrangian with the NL1 force and the pairing interaction by the central part of finite range Gogny D1S force. In CHFB theory, the properties in particle-hole and particle-particle channels are defined solely by Gogny D1S forces. Using an approximate particle number projection before variation by means of the Lipkin Nogami method improves the agreement with the experimental data, especially in CRHB theory. The effect of the particle number projection on the moments of inertia and pairing energies is larger in relativistic than in non-relativistic theory.Comment: 18 pages + 2 PostScript figure

    Large collection of astrophysical S-factors and its compact representation

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    Numerous nuclear reactions in the crust of accreting neutron stars are strongly affected by dense plasma environment. Simulations of superbursts, deep crustal heating and other nuclear burning phenomena in neutron stars require astrophysical S-factors for these reactions (as a function of center-of-mass energy E of colliding nuclei). A large database of S-factors is created for about 5000 non-resonant fusion reactions involving stable and unstable isotopes of Be, B, C, N, O, F, Ne, Na, Mg, and Si. It extends the previous database of about 1000 reactions involving isotopes of C, O, Ne, and Mg. The calculations are performed using the Sao Paulo potential and the barrier penetration formalism. All calculated S-data are parameterized by an analytic model for S(E) proposed before [Phys. Rev. C 82, 044609 (2010)] and further elaborated here. For a given reaction, the present S(E)-model contains three parameters. These parameters are easily interpolated along reactions involving isotopes of the same elements with only seven input parameters, giving an ultracompact, accurate, simple, and uniform database. The S(E) approximation can also be used to estimate theoretical uncertainties of S(E) and nuclear reaction rates in dense matter, as illustrated for the case of the 34Ne+34Ne reaction in the inner crust of an accreting neutron star.Comment: 13 pages, 2 figures, Phys. Rev. C, accepte

    Cranked Relativistic Hartree-Bogoliubov Theory: Superdeformed Bands in the A190A\sim 190 Region

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    Cranked Relativistic Hartree-Bogoliubov (CRHB) theory is presented as an extension of Relativistic Mean Field theory with pairing correlations to the rotating frame. Pairing correlations are taken into account by a finite range two-body force of Gogny type and approximate particle number projection is performed by Lipkin-Nogami method. This theory is applied to the description of yrast superdeformed rotational bands observed in even-even nuclei of the A190A\sim 190 mass region. Using the well established parameter sets NL1 for the Lagrangian and D1S for the pairing force one obtains a very successful description of data such as kinematic (J(1)J^{(1)}) and dynamic (J(2)J^{(2)}) moments of inertia without any adjustment of new parameters. Within the present experimental accuracy the calculated transition quadrupole moments QtQ_t agree reasonably well with the observed data.Comment: 6 pages including 4 PostScript figures, uses RevTex, revised version, Phys.Rev. C, Rapid Communications, in pres

    A New Parameterization for the Lagrangian Density of Relativistic Mean Field Theory

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    A new parameterization for an effective non-linear Lagrangian density of relativistic mean field (RMF) theory is proposed, which is able to provide an excellent description not only for the properties of stable nuclei but also for those far from the valley of beta-stability. In addition recently measured superdeformed mimima in the Hg-region are reproduced with high accuracy.Comment: 8 pages, Latex, 1 ps figur

    A Uniform Analysis of the Ly-alpha forest at z = 0 - 5: I. The sample and distribution of clouds at z > 1.7

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    We present moderate resolution data for 39 QSOs at z \approx 2 obtained at the Multiple Mirror Telescope. These data are combined with spectra of comparable resolution of 60 QSOs with redshifts greater than 1.7 found in the literature to investigate the distribution of Ly-alpha forest lines in redshift and equivalent width. We find a value for γ\gamma, the parameter describing the number distribution of Ly-alpha forest lines in redshift, of 1.88±0.221.88\pm0.22 for lines stronger than a rest equivalent width of 0.32 A˚\AA, in good agreement with some previous studies. The Kolmogorov-Smirnov test was applied to the data and it is found that this single power law is a good fit over the relevant redshift ranges. Simulations of the Lyman alpha forest were performed to determine the completeness of the line lists and to test how well the analysis the underlying line statistics, given this level of completeness.Comment: minor corrections to text, 37 Latex pages, 11 encapsulated Postscript figures, uses emulateapj.sty, To appear in the Sept. 2000 ApJS, line lists and spectra available at http://qso.as.arizona.edu/~jscott/Spectra/index.htm
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