892 research outputs found

    Polarization Phenomena by Deuteron Fragmentation into Pions

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    The fragmentation of deuterons into pions emitted forward in the kinematic region forbidden for free nucleon-nucleon collisions is analyzed. The inclusive relativistic invariant spectrum of pions and the tensor analyzing power T_{20} are investigated within the framework of an impulse approximation using different kinds of the deuteron wave function. The influence of P-wave inclusion in the deuteron wave function is studied, too. The invariant spectrum is shown to be more sensitive to the amplitude of the NNπXNN \to \pi X process than the tensor analyzing power T_{20}. It is shown that the inclusion of the non-nucleon degrees of freedom in a deuteron results a satisfactory description of experimental data about the inclusive pion spectrum and improves the description of data about T_{20}. According to the experimental data, T_{20} has the positive sign and very small values, less than 0.2, what contradicts to the theoretical calculations ignoring these degrees of freedom.Comment: 18 pages, 8 eps figures, 1 picture - svjour.cls required; enlarged new version with corrections and additional figure. The Abstract and the section "Summary and outlook" have been also corrected. Final version to appear in Eur.Phys.J. A. A talk given at the International Workshop "Symmetries and Spin" (July 17-22, Prague, Czech Republic

    Probing the deuteron structure at small N-N distances by cumulative pion production

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    The fragmentation of deuterons into pions emitted forward in the kinematic region forbidden for free nucleon-nucleon collisions is analyzed. It is shown that the inclusion of the non-nucleonic degrees of freedom in a deuteron results in a satisfactory description of the data for the inclusive pion spectrum and improves the description of the data about T20T_{20}. According to the data, T20T_{20} has very small positive values, less than 0.2, which contradicts the theoretical calculations ignoring these degrees of freedom.Comment: 3 pages, 2 postscript figures; to appear in the proceedings of Conference on Quarks and Nuclear Physics (QNP 2002), Julich, Germany, 9-14 Jun 200

    On the Evolution of Ion Bunch Profile in the Presence of Longitudinal Coherent Electron Cooling

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    In the presence of longitudinal coherent electron cooling, the evolution of the line-density profile of a circulating ion bunch can be described by the 1-D Fokker-Planck equation. We show that, in the absence of diffusion, the 1-D equation can be solved analytically for certain dependence of cooling force on the synchrotron amplitude. For more general cases with arbitrary diffusion, we solved the 1-D Fokker-Planck equation numerically and the numerical solutions have been compared with results from macro-particle tracking

    Enhanced fusarium head blight resistance in bread wheat and durum by alien introgressions

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    Fusarium head blight resistance has previously been detected in two accessions of Ae. cylindrica (2n=4x=28, CCDD genome). The resistance was introgressed initially into a semi-dwarf winter wheat, then subsequently into a number of Canadian hard red spring wheat cultivars plus one cultivar from USA. DON contents, determined on field plot-harvested samples are reported for selected lines from three populations.  Of the total of 83 lines tested from the three populations, 18 lines showed DON contents of less than 1ppm. Another 48 lines had 1-5ppm DON in their seed, compared to check cultivars Sumai3 at 1.2ppm and Roblin at 11.0 ppm. It is anticipated that unique FHB resistance QTL will be identified in these populationsУстойчивость к фузариозу колоса/гибберелёзу предварительно выявлена у 2-х образцов Ae.cylindrica (2n = 4 x = 28, ССДД геном). Первоначально эта устойчивость была интрогрессирована в полукарликовую озимую пшеницу, затем впоследствии в ряд канадских сортов твердой краснозерной яровой пшеницы и в один сорт из США. Данные по уровням содержания DON, определявшихся по образцам, собранным с полевой делянки, представлены для селекционных линий от 3-х популяций. Из всех 83 линий, которые испытывались, 18 линий демонстрировали DON-содержание менее 1 части на миллион. Другие 48 линий имели в своих семенах показатель DON 1-5 частей на млн. в сравнении с контрольными сортами Сумаи 3 при показателе 1.2 частей на млн. и Роблин – 11,0 частей на млн. Ожидают, что уникальную стойкость к болезням в локусах количественных признаков идентифицируют в этих популяцияхВиявлено стійкість до фузаріозу колоса/гіберельозу спочатку у 2-х зразків Ae.cylindrica (2n = 4 x = 28, ССДД геном). Вперше ця стійкість була інтегрована у напівкарликову озиму пшеницю, потім у ряд канадських сортів твердої червонозерної ярої пшениці та у один сорт із США. Дані по рівню утримання DON, що визначались по зразках, зібраних з польових ділянок, представлені для селекційних ліній від 3-х популяцій.Із усіх 83 ліній, які випробувались, 18 ліній продемонстрували DON-вміст менше 1 частини на мільйон. Інші 48 ліній мали у своєму насіння DON-показник 1-5 частин на мільйон в порівнянні з контрольними сортами Сумаі 3 при показнику 1.2 частини на мільйон і Роблін – 11,0 частин на мільйон. Чекають, що унікальну стійкість до хвороб у локусах кількісних ознак буде визначено у цих популяція

    Charge and matter distributions and form factors of light, medium and heavy neutron-rich nuclei

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    Results of charge form factors calculations for several unstable neutron-rich isotopes of light, medium and heavy nuclei (He, Li, Ni, Kr, Sn) are presented and compared to those of stable isotopes in the same isotopic chain. For the lighter isotopes (He and Li) the proton and neutron densities are obtained within a microscopic large-scale shell-model, while for heavier ones Ni, Kr and Sn the densities are calculated in deformed self-consistent mean-field Skyrme HF+BCS method. We also compare proton densities to matter densities together with their rms radii and diffuseness parameter values. Whenever possible comparison of form factors, densities and rms radii with available experimental data is also performed. Calculations of form factors are carried out both in plane wave Born approximation (PWBA) and in distorted wave Born approximation (DWBA). These form factors are suggested as predictions for the future experiments on the electron-radioactive beam colliders where the effect of the neutron halo or skin on the proton distributions in exotic nuclei is planned to be studied and thereby the various theoretical models of exotic nuclei will be tested.Comment: 26 pages, 11 figures, 3 tables, accepted for publication in Phys. Rev.
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