196 research outputs found

    New insight into the low-energy 9^9He spectrum

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    The spectrum of 9^9He was studied by means of the 8^8He(dd,pp)9^9He reaction at a lab energy of 25 MeV/n and small center of mass (c.m.) angles. Energy and angular correlations were obtained for the 9^9He decay products by complete kinematical reconstruction. The data do not show narrow states at \sim 1.3 and \sim 2.4 MeV reported before for 9^9He. The lowest resonant state of 9^9He is found at about 2 MeV with a width of \sim 2 MeV and is identified as 1/21/2^-. The observed angular correlation pattern is uniquely explained by the interference of the 1/21/2^- resonance with a virtual state 1/2+1/2^+ (limit on the scattering length is obtained as a>20a > -20 fm), and with the 5/2+5/2^+ resonance at energy 4.2\geq 4.2 MeV.Comment: 5 pages, 4 figures, 2 table

    Three-body correlations in direct reactions: Example of 6^{6}Be populated in (p,n)(p,n) reaction

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    The 6^{6}Be continuum states were populated in the charge-exchange reaction 1^1H(6^{6}Li,6^{6}Be)nn collecting very high statistics data (5×106\sim 5 \times 10^6 events) on the three-body α\alpha+pp+pp correlations. The 6^{6}Be excitation energy region below 3\sim 3 MeV is considered, where the data are dominated by contributions from the 0+0^+ and 2+2^+ states. It is demonstrated how the high-statistics few-body correlation data can be used to extract detailed information on the reaction mechanism. Such a derivation is based on the fact that highly spin-aligned states are typically populated in the direct reactions.Comment: submitted to Physical Review

    New broad 8Be nuclear resonances

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    Energies, total and partial widths, and reduced width amplitudes of 8Be resonances up to an excitation energy of 26 MeV are extracted from a coupled channel analysis of experimental data. The presence of an extremely broad J^pi = 2^+ ``intruder'' resonance is confirmed, while a new 1^+ and very broad 4^+ resonance are discovered. A previously known 22 MeV 2^+ resonance is likely resolved into two resonances. The experimental J^pi T = 3^(+)? resonance at 22 MeV is determined to be 3^-0, and the experimental 1^-? (at 19 MeV) and 4^-? resonances to be isospin 0.Comment: 16 pages, LaTe

    Alpha cluster resonance structure of light nuclei close to coulomb barrier

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    The aim of this experimental study is to investigate the structure of the 19F nuclei at energies representing astrophysical interest. Here we study the resonant interaction 15N+4He in the cyclotron DC-60 in Astana

    The TTIK approach for neutrons

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    We applied Thick Target Inverse Kinematics Method for a study of resonances decaying through neutron emission. As a test we used a well-studied, because of its role in s-process in stars, 13^{13}C(α\alpha; n) reaction. The observed energy resolution for the 13^{13}C(α\alpha; n) excitation function was \sim60 keV, the largest contributions coming from the time structure of the beam and the thickness of the neutron detector. These measurements demonstrated the high efficiency of the approach and revealed a disagreement with R-matrix calculations based on parameters of the most recent previous analysis
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