Alexander Volya
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View article: Relaxation and decay of collective modes in open quantum systems
Relaxation and decay of collective modes in open quantum systems Open
In a quantum many-body system, such as atoms, molecules, and atomic nuclei, interparticle interactions generate a complex quantum level scheme that can be analyzed progressively: from the simplest picture of independent quasiparticles movi…
View article: Quantifying alpha clustering in the ground states of 16-O and 20-Ne
Quantifying alpha clustering in the ground states of 16-O and 20-Ne Open
Understanding the role of multi-nucleon correlations in the structure of light nuclei is at the forefront of modern nuclear science. In this letter, we present a quantitative benchmark study of alpha-cluster correlations in the ground stat…
View article: Motivations for early high-profile FRIB experiments
Motivations for early high-profile FRIB experiments Open
This white paper is the result of a collaboration by many of those that attended a workshop at the facility for rare isotope beams (FRIB), organized by the FRIB Theory Alliance (FRIB-TA), on ‘Theoretical Justifications and Motivations for …
View article: Exploring $β$ decay and $β$-delayed neutron emission in exotic $^{46,47}$Cl isotopes
Exploring $β$ decay and $β$-delayed neutron emission in exotic $^{46,47}$Cl isotopes Open
In this paper, $β^-$ and $β$-delayed neutron decays of $^{46,47}$Cl are reported from an experiment carried out at the National Superconducting Cyclotron Laboratory using the Beta Counting System. The half-lives of both $^{46}$Cl and $^{47…
View article: Nuclear studies with FSU Hamiltonian
Nuclear studies with FSU Hamiltonian Open
You should leave 8 mm of space above the abstract and 10 mm after the abstract. The heading Abstract should be typed in bold 9-point Arial. The body of the abstract should be typed in normal 9-point Times in a single paragraph, immediately…
View article: R-matrix analysis of <sup>22</sup>Ne structure in the energy range 11.7–13.38 MeV
R-matrix analysis of <sup>22</sup>Ne structure in the energy range 11.7–13.38 MeV Open
An R-matrix analysis of the old high energy resolution experimental data [4, 5] in the excitation region of 11.7–13.78 MeV of 22 Ne was performed.
View article: Development of alpha cluster structure in nuclei of the same mass number
Development of alpha cluster structure in nuclei of the same mass number Open
The resonant 14 N+α particle scattering was studied in the 18 F excitation region from 6.5 to 9 MeV at Astana cyclotron using the TTIK approach. The excitation functions for the elastic 14 N+α scattering were analyzed in the framework of R…
View article: Proton-neutron pairing, quartet condensation and <i>α</i>− transfer in N=Z nuclei
Proton-neutron pairing, quartet condensation and <i>α</i>− transfer in N=Z nuclei Open
In the past years various studies have shown that the proton-neutron pairing correlations in N=Z nuclei can be accurately described by a condensate of α -like quartets. It was also shown that the α -like quartets, defined as 4- body collec…
View article: Probing the nonexponential decay regime in open quantum systems
Probing the nonexponential decay regime in open quantum systems Open
The most important law of radioactivity is that of the exponential decay. In the realm of quantum mechanics, however, this decay law is neither rigorous nor fundamental. The deviations from the exponential decay have been observed experime…
View article: Measurement of the $\mathrm{^{25}Al(d,n)^{26}Si}$ reaction and impact on the $\mathrm{^{25}Al(p,γ)^{26}Si}$ reaction rate
Measurement of the $\mathrm{^{25}Al(d,n)^{26}Si}$ reaction and impact on the $\mathrm{^{25}Al(p,γ)^{26}Si}$ reaction rate Open
The $\mathrm{^{25}Al(p,γ)^{26}Si}$ reaction is part of a reaction network with impact on the observed galactic $^{26}$Al abundance. A new determination of the proton strength of the lowest $\ell=0$ proton-resonance in $^{26}$Si is required…
View article: $β^-$ decay of neutron-rich $^{45}$Cl at magic number N=28
$β^-$ decay of neutron-rich $^{45}$Cl at magic number N=28 Open
Results from the study of $β^-$-decay of $^{45}$Cl, produced in the fragmentation of a 140-MeV/u $^{48}$Ca beam, are presented. The half-life for $^{45}$Cl $β$-decay is measured to be 513(36) ms. The $β^-$ and $β^- 1n$ decay of $^{45}$Cl p…
View article: Intruder configurations of excited states in the neutron-rich isotopes P 33 and P 34
Intruder configurations of excited states in the neutron-rich isotopes P 33 and P 34 Open
Excited states in the neutron-rich isotopes P33 and P34 were populated by the O18+O18 fusion-evaporation reaction at Elab=24 MeV. The Gammasphere array was used along with the Microball particle detector array to detect γ transitions in co…
View article: Cross-shell excitations in Si 31
Cross-shell excitations in Si 31 Open
The Si31 nucleus was produced through the O18(O18, αn) fusion-evaporation reaction at Elab=24MeV. Evaporated α particles from the reaction were detected and identified in the Microball detector array for channel selection. Multiple γ-ray c…
View article: Structured ground states of randomly interacting bosons
Structured ground states of randomly interacting bosons Open
Bosonic degrees of freedom and their emergence as part of complex quantum many-body dynamics, symmetries, collective behavior, clustering, and phase transitions play an important role in modern studies of quantum systems. In this paper, we…
View article: Study of Alpha-cluster States in \(N\neq Z\) Nuclei Using the TTIK Approach
Study of Alpha-cluster States in \(N\neq Z\) Nuclei Using the TTIK Approach Open
In this paper, we investigate the role of potential deformation in explaining the α-decay.The deformation of the nuclear potential has been taken into account by adding a Gaussian potential to the well-known Wood-Saxon potential.For the nu…
View article: Eigenstate thermalization and disappearance of quantum many-body scar states in weakly interacting fermion systems
Eigenstate thermalization and disappearance of quantum many-body scar states in weakly interacting fermion systems Open
The recent discovery of quantum many-body scar states has revealed the possibility of having states with low entanglement that violate the eigenstate thermalization hypothesis in nonintegrable systems. Eigenstates with low entanglement ent…
View article: Are the ground states of randomly interacting bosons random?
Are the ground states of randomly interacting bosons random? Open
Bosonic degrees of freedom and their emergence as a part of complex quantum many-body dynamics, symmetries, collective behavior, clustering and phase transitions play an important role in modern studies of quantum systems. In this work we …
View article: Superradiance in alpha clustered mirror nuclei
Superradiance in alpha clustered mirror nuclei Open
Resonances in unstable quantum systems are radiating states that despite decaying overall normalization have a well-defined structure which is being balanced by outgoing radiation. Such an interplay between outgoing wave and internal quant…
View article: Eigenstate thermalization and disappearance of quantum many-body scar states in interacting fermion systems
Eigenstate thermalization and disappearance of quantum many-body scar states in interacting fermion systems Open
The recent discovery of quantum many-body scar states has revealed the possibility of having states with low entanglement that violate the eigenstate thermalization hypothesis in nonintegrable systems. Such states with low entanglement ent…
View article: alpha-cluster structure of 18Ne
alpha-cluster structure of 18Ne Open
In this work we study alpha-clustering in 18Ne and compare it with what is\nknown about clustering in the mirror nucleus 18O. The excitation function of\n18Ne was measured in inverse kinematics from the resonant elastic scattering\nreactio…
View article: The Lowest Broad Alpha Cluster Resonances in $^{19}$F
The Lowest Broad Alpha Cluster Resonances in $^{19}$F Open
There is a deep astrophysical interest in the structure of $^{19}$F states close to the alpha decay threshold. The nuclear structure of these states is important for understanding of the development of $α$ clustering in the $^{20}$Ne regio…
View article: White paper: From bound states to the continuum
White paper: From bound states to the continuum Open
This white paper reports on the discussions of the 2018 Facility for Rare Isotope Beams Theory Alliance (FRIB-TA) topical program ‘From bound states to the continuum: Connecting bound state calculations with scattering and reaction theory’…
View article: Time-dependent relaxation of observables in complex quantum systems
Time-dependent relaxation of observables in complex quantum systems Open
We consider time-dependent relaxation of observables in quantum systems of chaotic and regular type. Using statistical arguments and exact numerical solutions we show that the spread of the initial wave function in the Hilbert space and th…
View article: Clustering in structure and reactions using configuration interaction techniques
Clustering in structure and reactions using configuration interaction techniques Open
Atomic nuclei are remarkable quantum many-body systems where clustering properties develop naturally from underlying interactions between the constituent nucleons. Clustering degrees of freedom manifest themselves in multiple structure and…
View article: Backbending, seniority, and Pauli blocking of pairing correlations at high rotational frequencies in rapidly rotating nuclei
Backbending, seniority, and Pauli blocking of pairing correlations at high rotational frequencies in rapidly rotating nuclei Open
Garrett et al. systematically investigated band-crossing frequencies resulting from the rotational alignment of the first pair of $i_{13/2}$ neutrons (AB) in rare-earth nuclei. In that study, evidence was found for an odd-even neutron numb…
View article: Study of clustering in isotopes of beryllium
Study of clustering in isotopes of beryllium Open
Recently, a new strategy that unifies the structure, clustering, and reactions aspects of the nuclear quantum many-body problem has been put forward; the configuration interaction technique combined with the resonating group method based o…
View article: Study of Nuclear Clustering from an <i>Ab Initio</i> Perspective
Study of Nuclear Clustering from an <i>Ab Initio</i> Perspective Open
We put forward a new ab initio approach that seamlessly bridges the structure, clustering, and reactions aspects of the nuclear quantum many-body problem. The configuration interaction technique combined with the resonating group method ba…
View article: Constructing realistic alpha cluster channels
Constructing realistic alpha cluster channels Open
We present techniques that allow for α-cluster channels with realistic α-particle wave functions from No Core Shell Model calculations to be constructed. We compare results of several clustering calculations with realistic α wave functions…