26 research outputs found
Octupole deformation instability in atomic nuclei
Recent high-energy heavy-ion collision experiments have revealed that some
atomic nuclei exhibit unusual softness and significant shape fluctuations. In
this Letter, we use the fully self-consistent mean-field theory to identify all
even-even nuclei that are unstable or soft against octupole deformation. All
exceptional cases of enhanced octupole transition strengths in stable even-even
nuclei throughout the nuclide chart are resolved. These results represent a
significant advance in our understanding of the underlying mechanisms of
nuclear octupole deformation and have implications for further experimental and
theoretical studies.Comment: New references [3,4] were added. Thank Prof. Jiangyong Jia for the
discussion
Super-Radiant Dynamics, Doorways, and Resonances in Nuclei and Other Open Mesoscopic Systems
The phenomenon of super-radiance (Dicke effect, coherent spontaneous
radiation by a gas of atoms coupled through the common radiation field) is well
known in quantum optics. The review discusses similar physics that emerges in
open and marginally stable quantum many-body systems. In the presence of open
decay channels, the intrinsic states are coupled through the continuum. At
sufficiently strong continuum coupling, the spectrum of resonances undergoes
the restructuring with segregation of very broad super-radiant states and
trapping of remaining long-lived compound states. The appropriate formalism
describing this phenomenon is based on the Feshbach projection method and
effective non-Hermitian Hamiltonian. A broader generalization is related to the
idea of doorway states connecting quantum states of different structure. The
method is explained in detail and the examples of applications are given to
nuclear, atomic and particle physics. The interrelation of the collective
dynamics through continuum and possible intrinsic many-body chaos is studied,
including universal mesoscopic conductance fluctuations. The theory serves as a
natural framework for general description of a quantum signal transmission
through an open mesoscopic system.Comment: 85 pages, 10 figure
Recent results on heavy-ion induced reactions of interest for neutrinoless double beta decay at INFN-LNS
Abstract. The possibility to use a special class of heavy-ion induced direct reactions, such as double charge exchange reactions, is discussed in view of their application to extract information that may be helpful to determinate the nuclear matrix elements entering in the expression of neutrinoless double beta decay halflife. The methodology of the experimental campaign presently running at INFN - Laboratori Nazionali del Sud is reported and the experimental challenges characterizing such activity are describe
NURE: An ERC project to study nuclear reactions for neutrinoless double beta decay
Neutrinoless double beta decay (0νββ) is considered the best potential resource to
access the absolute neutrino mass scale. Moreover, if observed, it will signal that neutrinos are
their own anti-particles (Majorana particles). Presently, this physics case is one of the most
important research âbeyond Standard Modelâ and might guide the way towards a Grand
Unified Theory of fundamental interactions.
Since the 0νββ decay process involves nuclei, its analysis necessarily implies nuclear structure
issues. In the NURE project, supported by a Starting Grant of the European Research Council
(ERC), nuclear reactions of double charge-exchange (DCE) are used as a tool to extract
information on the 0νββ Nuclear Matrix Elements. In DCE reactions and ββ decay indeed the
initial and final nuclear states are the same and the transition operators have similar structure.
Thus the measurement of the DCE absolute cross-sections can give crucial information on ββ
matrix elements. In a wider view, the NUMEN international collaboration plans a major
upgrade of the INFN-LNS facilities in the next years in order to increase the experimental
production of nuclei of at least two orders of magnitude, thus making feasible a systematic
study of all the cases of interest as candidates for 0νββ
New results from the NUMEN project
NUMEN aims at accessing experimentally driven information on Nuclear Matrix Elements (NME) involved in the half-life of the neutrinoless double beta decay (0νββ), by high-accuracy measurements of the cross sections of Heavy Ion (HI) induced Double Charge Exchange (DCE) reactions. First evidence about the possibility to get quantitative information about NME from experiments is found for the (18O,18Ne) and (20Ne,20O) reactions. Moreover, to infer the neutrino average masses from the possible measurement of the half-life of 0νββ decay, the knowledge of the NME is a crucial aspect. The key tools for this project are the high resolution Superconducting Cyclotron beams and the MAGNEX magnetic spectrometer at INFN Laboratori Nazionali del Sud in Catania (Italy). The measured cross sections are extremely low, limiting the present exploration to few selected isotopes of interest in the context of typically low-yield experimental runs. A major upgrade of the LNS facility is foreseen in order to increase the experimental yield of at least two orders of magnitude, thus making feasible a systematic study of all the cases of interest. peerReviewe
Study of the double Gamow-Teller transitions using the shell model approach
The double Gamow-Teller strength distributions in the lightest double beta-decay candidate 48Ca and its isotope 46Ca were calculated using the nuclear shell model by applying the single Gamow-Teller operator two times sequentially on the ground state of parent nucleus. The nuclear matrix element of the double Gamow- Teller transition from the ground state to the ground state that goes into the double beta decay calculation was shown as a small fraction of the total transition
Study of the double Gamow-Teller transitions using the shell model approach
The double Gamow-Teller strength distributions in the lightest double beta-decay candidate 48Ca and its isotope 46Ca were calculated using the nuclear shell model by applying the single Gamow-Teller operator two times sequentially on the ground state of parent nucleus. The nuclear matrix element of the double Gamow- Teller transition from the ground state to the ground state that goes into the double beta decay calculation was shown as a small fraction of the total transition