1,721,454 research outputs found
Gamma spectroscopy as a tool to search for particle–phonon coupled states: status and perspectives
No full textThe coupling mechanism between a particle and a phonon is a basic phenomenon in fermonic many-body interacting systems, which is here experimentally investigated in neutron-rich nuclei by in-beam γ-spectroscopy. In particular, nuclei around doubly magic 48Ca are studied by the heavy-ion transfer reaction 48Ca on 64Ni at 282 MeV, with the PRISMA-CLARA setup at Legnaro Laboratory of INFN. Angular distributions, polarizations and lifetimes analyses are used to probe spin and parities of several excited states, shading lights on their configuration. In the one-neutron transfer channels (49Ca and 47Ca), states arising from coupling of a single particle to the 3− phonon of 48Ca are identified, showing the robustness of nuclear collectivity in rather light systems. Preliminary results on 65Cu are also discussed with regard to the coupling of the p3/2 unpaired proton to the 3− phonon of 64Ni. Experimental results are interpreted using a phenomenological weak-coupling model, which is also used to provide predictions on exotic systems around the doubly magic 132Sn core
Warm superdeformed nuclei : nuclear structure effects on the order-to-chaos transition region
No full text
Reaction dynamics and nuclear structure studies of N-rich nuclei around 48Ca via deep inelastic collisions with heavy-ions
No full textThe population and
decay of neutron rich nuclei around 48Ca has
been measured at Legnaro National Laboratory with the PRISMA-CLARA
setup, using deep-inelastic collisions on 64Ni, at 5.9 MeV/A. The reaction
properties of the main products are investigated, focusing on total crosssections
and energy integrated angular distributions. Gamma spectroscopy
studies are also performed for the most intense transfer channels, making
use of angular distributions and polarization measurements to firmly establish
spin and parity of the excited states. In the case of 49Ca candidates for
particle-core couplings are investigated and interpreted on basis of lifetime
measurements and comparison with model predictions
Complete gamma-spectroscopy of n-rich nuclei around 48Ca with multi-nucleon transfer reactions
No full textThe gamma decay of neutron-rich nuclei around 48Ca was measured at Legnaro National Laboratory (Italy) with the PRISMA-CLARA setup, following the multi-nucleon transfer reaction 48Ca on 64Ni at 282 MeV. Evidence is found for a large spin alignment (of the order of 70%), perpendicular to the reaction plane. As a consequence, angular distributions and polarizations of gamma-rays allow to firmly establish, for the first time, spin and parities of excited states in several nuclei, such as Ca, Sc and K. In addition, lifetime measurements, performed with the Differential Plunger Technique, help establishing the nature of these states, in comparison with predictions based on shell model and particle-vibration coupling calculations. In the case of 49Ca, evidence is found for the presence, in the same excitation energy region, of two types of coupled states, i.e. particle-vibration coupled states based on the 3- phonon of 48Ca and single particle coupled to either 48Ca or 50Ca simple configurations. In the latter case, the measured B(Elambda) value gives also the possibility to disentangle between equivalent configurations based on the two different core states. Furthermore, we note that the 9/2+ state at 4017 keV in 49Ca represents one of the few fully established examples of particle-vibration coupling in nuclei with mass A<100, showing the robustness of nuclear collectivity in rather light systems. The cases of 47Ca and 50Ca will be also discussed in detail, where particle-phonon couplings and pairing effects play a crucial role. The present work makes clearly visible the multifaceted nature of particle-core coupling interactions in the atomic nucleus, giving also a warning to simple generalizations of coupling schemes. It also clearly demonstrates the feasibility of complete in-beam gamma-spectroscopy with heavy-ion transfer reactions, providing a method that can be further exploited in the future with heavy targets and radioactive beams
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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