318 research outputs found
Study of shape coexistence in the 188Hg isotope
Shape coexistence is a striking phenomenon that has attracted a large community and has been evidenced in many nuclear species where structures belonging to different deformations are observed coexisting within a typical energy range of nuclear excitation. Along the Z=80 isotopic chain, the 188Hg nucleus is the border-line where the presence of this phenomenon is foreseen but has not been confirmed yet. For this reason, this nucleus has been studied in a two-steps experiment performed at the Laboratori Nazionali di Legnaro in order to measure the lifetimes of the low-lying states of the 188Hg
Pair neutron transfer in Ni 60 + Sn 116 probed via γ -particle coincidences
D. Montanari et al. ; 6 págs.; 5 figs.; 1 tab.We performed a γ-particle coincidence experiment for the Ni60+Sn116 system to investigate whether the population of the two-neutron pickup channel leading to Ni62 is mainly concentrated in the ground-state transition, as has been found in a previous work [D. Montanari et al., Phys. Rev. Lett. 113, 052501 (2014)PRLTAO0031-900710.1103/PhysRevLett.113.052501]. The experiment has been performed by employing the PRISMA magnetic spectrometer coupled to the Advanced Gamma Tracking Array (AGATA) demonstrator. The strength distribution of excited states corresponding to the inelastic, one- and two-neutron transfer channels has been extracted. We found that in the two-neutron transfer channel the strength to excited states corresponds to a fraction (less than 24%) of the total, consistent with the previously obtained results that the 2n channel is dominated by the ground-state to ground-state transition. ©2016 American Physical SocietyThis work was partly supported by the
EU FP7/2007-2013 under Grant No. 262010-ENSAR and by
the Croatian Science Foundation under Project No. 7194.
A.G. was partially supported by MINECO and Generalitat
Valenciana, Spain, under Grants No. FPA2014-57196-C5 and
No. PROMETEOII/2014/019 and the EU under the FEDER
program.Peer Reviewe
Perspectives on the measurement of competitive double gamma decay with the AGATA tracking array
The double-gamma decay is a second order electromagnetic process where two photons are emitted simultaneously. It is characterized by low branching ratios, making its measurement interesting both theoretically and also experimentally. Although this process has been already observed in the past, a recent publication claimed its observation in competition with the single gamma decay.
A measurement of this process with the AGATA spectrometer (Advanced GAmma Tracking Array) will deliver more detailed results. A test of feasibility of this challenging measurement has been performed through GEANT4 simulations of the decay of the 137Ba isotope. Particular emphasis is placed on the tracking algorithm which allows to reconstruct a scattering gamma-ray event based on the position and energy of every interaction point within the AGATA germanium detector
Clusters in Light Nuclei
A great deal of research work has been undertaken in the alpha-clustering
study since the pioneering discovery, half a century ago, of 12C+12C molecular
resonances. Our knowledge of the field of the physics of nuclear molecules has
increased considerably and nuclear clustering remains one of the most fruitful
domains of nuclear physics, facing some of the greatest challenges and
opportunities in the years ahead. In this work, the occurence of "exotic"
shapes in light N=Z alpha-like nuclei is investigated. Various approaches of
superdeformed and hyperdeformed bands associated with quasimolecular resonant
structures are presented. Results on clustering aspects are also discussed for
light neutron-rich Oxygen isotopes.Comment: 12 pages, 5 figures. Invited Talk presented by C. Beck at the
Zakopane Conference on Nuclear Physics "Extremes of the Nuclear Landscape"
XLV in the series of Zakopane Schools of Physics - International Symposium -
Zakopane, Poland, August 30 - September 5, 2010.To be publihed in Acta
Physica Polonica B42 no 3, March 201
C+O sub-barrier radiative capture cross-section measurements
We have performed a heavy ion radiative capture reaction between two light
heavy ions, C and O, leading to Si. The present experiment
has been performed below Coulomb barrier energies in order to reduce the phase
space and to try to shed light on structural effects. Obtained -spectra
display a previously unobserved strong feeding of intermediate states around 11
MeV at these energies. This new decay branch is not fully reproduced by
statistical nor semi-statistical decay scenarii and may imply structural
effects. Radiative capture cross-sections are extracted from the data.Comment: 4 pages, 7 figures, to appear as proceedings of FUSION 2011
conference at St-Malo, Franc
From the stable to the exotic: clustering in light nuclei
A great deal of research work has been undertaken in alpha-clustering study
since the pioneering discovery of 12C+12C molecular resonances half a century
ago. Our knowledge on physics of nuclear molecules has increased considerably
and nuclear clustering remains one of the most fruitful domains of nuclear
physics, facing some of the greatest challenges and opportunities in the years
ahead. The occurrence of "exotic" shapes in light N=Z alpha-like nuclei is
investigated. Various approaches of the superdeformed and hyperdeformed bands
associated with quasimolecular resonant structures are presented. Evolution of
clustering from stability to the drip-lines is examined: clustering aspects
are, in particular, discussed for light exotic nuclei with large neutron excess
such as neutron-rich Oxygen isotopes with their complete spectroscopy.Comment: 15 pages, 5 figures, Presented at the International Symposium on "New
Horizons in Fundamental Physics - From Neutrons Nuclei via Superheavy
Elements and Supercritical Fields to Neutron Stars and Cosmic Rays" held at
Makutsi Safari Farm, South Africa, December 23-29, 2015. arXiv admin note:
substantial text overlap with arXiv:1402.6590, arXiv:1303.0960,
arXiv:1408.0684, arXiv:1011.342
Fusion Hindrance and Quadrupole Collectivity in Collisions of A≃50 Nuclei: The Case of 48Ti + 58Fe
International audience; The fusion excitation function of Ti-48 + Fe-58 has been measured in a wide energy range around the Coulomb barrier, covering 6 orders of magnitude of the cross sections. We present here the preliminary results of this experiment, and a full comparison with the near-by system Ni-58 + Fe-54 where evidence of fusion hindrance shows up at relatively high cross sections. The sub-barrier cross sections of Ti-48 + Fe-58 are much larger than those of Ni-58 + Fe-54. Significant differences are also observed in the logarithmic derivatives, astrophysical S-factors and fusion barrier distributions. The influence of low-energy nuclear structure on all these trends is pointed out and commented. Coupled-channels calculations using a Woods-Saxon potential are able to reproduce the experimental results for Ti-48 + Fe-58. The logarithmic derivative of the excitation function is very nicely fit, and no evidence of hindrance is observed down to around 1 mu b. The fusion barrier distribution is rather wide, flat and structureless. It is only in qualitative agreement with the calculated distribution
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