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The low-lying level structure of the unbound neutron-rich nucleus 13Be has been investigated via breakup on a carbon target of secondary beams of 14,15B at 35 MeV/nucleon. The coincident detection of the beam velocity 12Be fragments and neutrons permitted the invariant mass of the 12Be+n and 12Be+n+n systems to be reconstructed. In the case of the breakup of 15B, a very narrow structure at threshold was observed in the 12Be+n channel. Analysis of the 12Be+n+n events demonstrated that this resulted from the sequential decay of the unbound 14Be(2+) state rather than a strongly interacting s-wave virtual state in 13Be, as had been surmised in stable beam fragmentation studies. Single-proton removal from 14B was found to populate a broad low-lying structure some 0.7 MeV above the neutron-decay threshold, in addition to a less prominent feature at around 2.4 MeV. Based on the selectivity of the reaction and a comparison with (0-3)... shell-model calculations, the low-lying structure is concluded to arise from closely spaced Jp=1/2+ and 5/2+ resonances (Er=0.40±0.03 and 0.85-0.11+0.15 MeV), while the broad higher-lying feature is a second 5/2+ level (Er=2.35±0.14 MeV). Taken in conjunction with earlier studies, the results suggest that the lowest 1/2+ and 1/2- levels lie relatively close together below 1 MeV. [ABSTRACT FROM AUTHOR]

The fission of a variety of actinides was induced by fusion and transfer reactions between a 238 U beam and 12 C nuclei, in the active target MAYA. The performance of MAYA was studied, as well as its capability to reconstruct the fission-fragment trajectories. Furthermore, a full characterization of the different transfer reactions was achieved, and the populated excitation-energy distributions were investigated as a function of the kinetic energy in the entrance channel. The ratio between transfer- and fusion-induced fission cross-sections was also determined, in order to investigate the competition between both reaction types and its evolution with the incident energy. The experimental results will be discussed with a view to forthcoming radioactive-ion beam facilities, and next-generation active-target setups. [ABSTRACT FROM AUTHOR]

The unbound nucleus 7He has been investigated via the reaction of a 16.8 MeV 6He radioactive ion beam on a 9Be target. The measurement of the outgoing 8Be through its well characterized two-α decay permitted the energy of the 6He+n system to be reconstructed. Through comparison with a complete Monte Carlo simulation incorporating R-matrix lineshapes, the 7He ground state was determined to lie 0.380(28) MeV above the neutron decay with a width of Γ=0.179(21) MeV. A neutron spectroscopic factor SF=0.608(18) was extracted in agreement with the most recent calculations. Significant evidence was found for a broad resonance lying at 2.6(2) MeV above threshold with a ΓFWHM=2.3(3) MeV. These parameters are fully consistent with the properties of 1/2- state reported by Wuosmaa et al. [Phys. Rev. C 72, 061301(R) (2005)]. Limits were also put on the presence of narrow resonances seen in earlier experiments. [ABSTRACT FROM AUTHOR]

While the C 12 ( α , γ ) 16 O reaction plays a central role in nuclear astrophysics, the cross section at energies relevant to hydrostatic helium burning is too small to be directly measured in the laboratory. The β -delayed α spectrum of 16 N can be used to constrain the extrapolation of the E1 component of the S -factor; however, with this approach the resulting S -factor becomes strongly correlated with the assumed βα branching ratio. We have remeasured the βα branching ratio by implanting 16 N ions in a segmented Si detector and counting the number of βα decays relative to the number of implantations. Our result, 1.49 ( 5 ) × 10 − 5 , represents a 24 % increase compared to the accepted value and implies an increase of ≈ 10 % in the extrapolated S -factor. [ABSTRACT FROM AUTHOR]

In a proof-of-principle measurement, the Maya active target detector was employed for a C( p, p) resonant elastic scattering experiment in inverse kinematics. The excitation energy region from 0 to 3MeV above the proton breakup threshold in N was investigated in a single measurement. By using the capability of the detector to localize the reaction vertex and record the tracks of the recoiling protons, data covering a large solid angle could be utilized, at the same time keeping an energy resolution comparable with that of direct-kinematics measurements. The excitation spectrum in N was fitted using the R-matrix formalism. The level parameters extracted are in good agreement with previous studies. The active target proved its potential for the study of resonant elastic scattering in inverse kinematics with radioactive beams, when detection efficiency is of primary importance. [ABSTRACT FROM AUTHOR]

Excitation functions for the production of heavy residues have been measured for the collisions 6,7Li + 64Zn at energies around and below the Coulomb barrier. The cross sections for heavy residue production have been measured using an activation technique, detecting off-line the characteristic atomic x-rays emitted in the electron capture decay of the reaction products. The experimental relative yields of the residues have been compared with statistical model calculations performed by using the code CASCADE. Such a comparison suggests that heavy residue production is dominated by complete fusion at above-barrier energies, whereas different processes like incomplete fusion and/or transfer become dominant in the sub-barrier energy region. The heavy residue excitation function ratio between the 6Li- and 7Li-induced collisions shows an increasing trend as the energy decreases below the barrier. [ABSTRACT FROM AUTHOR]

The quasi-elastic scattering angular distribution of the collision 11Be + 64Zn was measured and compared with the elastic scattering angular distribution for its core, the 10Be nucleus on the same target. Optical model and continuum-discretized coupled-channel calculations of the 11Be+64Zn reaction were performed in order to interpret the effect of coupling with the break-up channels on the measured cross-sections. [ABSTRACT FROM AUTHOR]

In this paper details of the experimental procedure and data analysis of the collision of 11 Be+64Zn around the Coulomb barrier are described and discussed in the framework of different theoretical approaches. In a previous work [A. Di Pietro et ai, Phys. Rev. Lett. 105, 022701 (2010).], the elastic scattering angular distribution of the collisions 9,10Be+64Zn as well as the angular distribution for the quasielastic scattering and transfer/breakup cross sections for the 11Be+64Zn reaction were briefly reported. The suppression of the quasielastic angular distribution in the Coulomb-nuclear interference angular region observed in the collision of the 11 Be halo nucleus with respect to the other two beryllium isotopes was interpreted as being caused by a long-range absorption owing to the long decay length of the uBe wave function. In this paper, new continuum-discretized coupledchannel calculations of the 11Be+64Zn reaction are reported in the attempt to interpret the effect of coupling with the breakup channels on the measured cross sections. The calculations show that the observed suppression of the Coulomb-nuclear interference peak is caused by a combined effect of Coulomb and nuclear couplings to the breakup channels. [ABSTRACT FROM AUTHOR]

In this contribution, results concerning different reaction channels for the collisions induced by the three Be isotopes, 9,10,11Be, on a 64Zn target at energies around the Coulomb barrier will be presented. The experiments with the radioactive 10,11Be beams were performed at REX-ISOLDE (CERN) whereas the experiment with the stable weakly bound 9Be beam was performed at LNS Catania. Elastic scattering angular distributions have been measured for the three systems 9,10,11Be + 64Zn at the same center of mass energy. The angular distributions were analyzed with optical potentials and reaction cross sections were obtained from optical model calculations, performed with the code PTOLEMY. For the 11Be + 64Zn reaction, the break-up angular distribution was also measured. [ABSTRACT FROM AUTHOR]

Abstract: An experimental technique is described that is able to measure reaction cross-sections at energies around the Coulomb barrier by using low intensity beams and a Si detector as an active target. Set-up optimization was carefully investigated in terms of collimation, detector efficiency and pile-up rejection. The method has been tested by measuring the total reaction cross-section σ R(E) for the 7Li+28Si system in the energy range of E lab=12–16MeV. The deduced excitation function σ R(E) agrees with the data obtained in a previous experiment. The presented technique can also be applied in order to determine total reaction cross-sections for low intensity radioactive beams at energies around the Coulomb barrier. [Copyright &y& Elsevier]

BACKGROUND: Migraine is a highly prevalent and disabling disease which is substantially underdiagnosed in primary care. Recently, the ID Migraine, a self-administered questionnaire, consisting of only 3 items, was shown to be a valid and reliable screening instrument for migraine in primary care in the United States. OBJECTIVE: The aim of the present study was to validate an Italian version of the 'ID Migraine' questionnaire. METHODS: Two hundred and twenty-two consecutive headache patients referring to 8 headache centers in Sicily (Italy) completed an Italian version of the ID Migraine. The responses to the questionnaire were compared with the diagnosis of headache made by a headache specialist blind to the result of the questionnaire. Sensitivity, specificity, positive and negative predictive values for migraine were calculated. RESULTS: The statistical analysis of 222 patients examined showed a very good performance of the ID Migraine with high sensitivity: 0.95 (95% CI, 0.91 to 0.98), specificity: 0.72 (95% CI, 0.62 to 0.82), and positive predictive value: 0.88 (95% CI, 0.82 to 0.93). ID Migraine showed also a very good accuracy level: 0.87 (95% CI, 0.83 to 0.92). CONCLUSION: This validation study showed 'ID Migraine' as a valid tool for migraine screening also in Italian patients referring to headache centers. If confirmed in a primary care setting, these results establish the 'ID Migraine' as a valid screening instrument for migraine in Italian population. [ABSTRACT FROM AUTHOR]