996 resultados para HE-6
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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We present model results for the two-halo-neutron correlation functions, C-nn, for the dissociation process of light exotic nuclei modelled as two neutrons and a core. A minimum is predicted for C-nn as a function of the relative momentum of the two neutrons, p(nn), due to the coherence of the neutrons in the halo and final state interaction. Studying the systems Be-14, Li-11, and He-6 within this model, we show that the numerical asymptotic limit, C-nn-> 1, occurs only for p(nn)greater than or similar to 400 MeV/c, while such limit is reached for much lower values of p(nn) in an independent particle model as the one used in the analysis of recent experimental data. Our model is consistent with data once the experimental correlation function is appropriately normalized.
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We investigate the breakup of the proton halo B-8 projectile in the presence of the light target C-12 at near barrier energies. Our calculations show that the effect of the breakup on the elastic scattering angular distributions is negligible. We also investigate the relative importance of Coulomb and nuclear breakups for this system. We compare the results of our calculations with those for the He-6 + C-12 and B-8 Ni-58 systems. (C) 2012 Elsevier B.V. All rights reserved.
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We exploit the possibility of new configurations in three-body halo nuclei, Samba type (the neutron-core form a bound system) as a doorway to Borromean systems. The nuclei Be-12, B-15, N-23 and F-27 are of such nature, in particular N-23 with a half-life of 37.7 s and a halo radius of 6.07 fm is an excellent example of Samba-halo configuration. The fusion below the barrier of the Samba halo nuclei with heavy targets could reveal the so far elusive enhancement and a dominance of one-neutron over two-neutron transfers, in contrast to what was found recently for the Borromean halo nucleus He-6 + U-238.
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The elastic scattering of (6)He on (120)Sn has been measured at four energies above the Coulomb barrier using the (6)He beam produced at the RIBRAS (Radioactive Ion Beams in Brasil) facility. The elastic angular distributions have been analyzed with the optical model and three- and four-body continuum-discretized coupled-channels calculations. The total reaction cross sections have been derived and compared with other systems of similar masses.
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New data for the (6)He + (9)Be reaction at E(1ab) = 16.2 and 21.3 MeV have been taken and analyzed. The effect of the collective couplings to the excited states of the target has been studied by means of coupled-channels calculations, using a double-folding potential for the bare interaction between the colliding nuclei, supplemented with a phenomenological imaginary part of Woods-Saxon type. In addition, three- and four-body continuum-discretized coupled-channels calculations have been performed to investigate the effect of the projectile breakup on the elastic scattering. Both effects, the coupling to target and projectile excited states, are found to affect significantly the elastic scattering. The trivial local polarization potential extracted from the continuum-discretized coupled-channels calculations indicates that continuum couplings produce a repulsive real part and a long-range imaginary part in the projectile-target interaction.
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Fil: Bisignano, Julia Alejandra. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.
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Fil: Bisignano, Julia Alejandra. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.
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Fil: Bisignano, Julia Alejandra. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.
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Fil: Bisignano, Julia Alejandra. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.
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This layer is part of a set of georeferenced, raster images of the manuscript, paper map set entitled: Ch'ing-Hai upper Yellow River expedition : Rock and Simpson, 1925-27, [cartography by J.F. Rock]. Scale 1:250,000. This layer image is of Sheet VI [of 10] covering a portion of the Yellow River (Huang He) region in eastern Qinghai Sheng, southern Gansu Sheng, and northwestern Sichuan Sheng, China. The map set details the route and surrounding environs of the Arnold Arboretum's "Western China" expedition led by Joseph Rock, 1924-1927. The set covers a portion of the Yellow River (Huang He) region in south central China (Qinghai, Gansu, and Sichuan shengs (a portion of historic Tibet)). It shows features, labeled variously in English, Chinese, Wade-Giles transliteration, and Tibetan, including: rivers, streams, lakes, mountains, gorges, valleys, plateaus, plains, cities, towns, villages, provincial capitals, county seats, passes, monasteries, ruin sites, native tribe locations, and more. Relief is shown by hachures, spot heights, and landform drawings. The original manuscript map set is part of the Harvard College Library, Harvard Map Collection. "Joseph Rock traced his travels for the [Arnold] Arboretum's [Western China] 1924-1927 expedition in a colorful, hand-drawn map entitled 'Ch'ing-Hai upper Yellow River expedition.' The pen-and-ink drawing was made on ten sheets that when joined form a single, irregularly-shaped map, approximately six by eight feet in size. The individual sheets are numbered, using roman numerals; on sheet VII is a second title, 'Choni Territory, Upper and Lower T'ieh-Pu country and route to Sung-Pan, J. F. Rock, 1925-1927.' Topographical and other features are identified using a combination of English, Chinese characters, Wade-Giles transliterations and Tibetan script. Rock's attractive cursive style and use of hachures, spot heights, and landform drawings to depict relief add character to the map." -- Text from the Arnold Arboretum Web site.
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Reprint of Ting zhen xuan kan ben.
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Double leaves, oriental style, in case.