| 1. |
- Kirsebom, O. S., et al.
(författare)
-
Discovery of an Exceptionally Strong β -Decay Transition of F 20 and Implications for the Fate of Intermediate-Mass Stars
- 2019
-
Ingår i: Physical Review Letters. - 0031-9007. ; 123:26
-
Tidskriftsartikel (refereegranskat)abstract
- A significant fraction of stars between 7 and 11 solar masses are thought to become supernovae, but the explosion mechanism is unclear. The answer depends critically on the rate of electron capture on Ne20 in the degenerate oxygen-neon stellar core. However, because of the unknown strength of the transition between the ground states of Ne20 and F20, it has not previously been possible to fully constrain the rate. By measuring the transition, we establish that its strength is exceptionally large and that it enhances the capture rate by several orders of magnitude. This has a decisive impact on the evolution of the core, increasing the likelihood that the star is (partially) disrupted by a thermonuclear explosion rather than collapsing to form a neutron star. Importantly, our measurement resolves the last remaining nuclear physics uncertainty in the final evolution of degenerate oxygen-neon stellar cores, allowing future studies to address the critical role of convection, which at present is poorly understood
|
|
| 2. |
- Bertulani, C. A., et al.
(författare)
-
Examination of the sensitivity of quasifree reactions to details of the bound-state overlap functions
- 2021
-
Ingår i: Physical Review C. - 2469-9985. ; 104:6
-
Tidskriftsartikel (refereegranskat)abstract
- It is often stated that heavy-ion nucleon knockout reactions are mostly sensitive to the tails of the bound-state wave functions. In contrast, (p,2p) and (p,pn) reactions are known to access information on the full overlap functions within the nucleus. We analyze the oxygen isotopic chain and explore the differences between single-particle wave functions generated with potential models, used in the experimental analysis of knockout reactions, and ab initio computations from self-consistent Green's function theory. Contrary to common belief, we find that not only the tail of the overlap functions, but also their internal part is assessed in both reaction mechanisms, which are crucial to yield accurately determined spectroscopic information.
|
|
| 3. |
- Dobaczewski, J., et al.
(författare)
-
Solution of universal nonrelativistic nuclear DFT equations in the Cartesian deformed harmonic-oscillator basis. (IX) HFODD (v3.06h) : A new version of the program
- 2021
-
Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 48:10
-
Tidskriftsartikel (refereegranskat)abstract
- We describe the new version (v3.06h) of the code HFODD that solves the universal nonrelativistic nuclear DFT Hartree-Fock or Hartree-Fock-Bogolyubov problem by using the Cartesian deformed harmonic-oscillator basis. In the new version, we implemented the following new features: (i) zero-range three- and four-body central terms, (ii) zero-range three-body gradient terms, (iii) zero-range tensor terms, (iv) zero-range isospin-breaking terms, (v) finite-range higher-order regularized terms, (vi) finite-range separable terms, (vii) zero-range two-body pairing terms, (viii) multi-quasiparticle blocking, (ix) Pfaffian overlaps, (x) particle-number and parity symmetry restoration, (xi) axialization, (xii) Wigner functions, (xiii) choice of the harmonic-oscillator basis, (xiv) fixed omega partitions, (xv) consistency formula between energy and fields, and we corrected several errors in the previous versions.
|
|
| 4. |
- Hebborn, C., et al.
(författare)
-
Optical potentials for the rare-isotope beam era
- 2023
-
Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 50:6
-
Tidskriftsartikel (refereegranskat)abstract
- We review recent progress and motivate the need for further developments in nuclear optical potentials that are widely used in the theoretical analysis of nucleon elastic scattering and reaction cross sections. In regions of the nuclear chart away from stability, which represent a frontier in nuclear science over the coming decade and which will be probed at new rare-isotope beam facilities worldwide, there is a targeted need to quantify and reduce theoretical reaction model uncertainties, especially with respect to nuclear optical potentials. We first describe the primary physics motivations for an improved description of nuclear reactions involving short-lived isotopes, focusing on its benefits for fundamental science discoveries and applications to medicine, energy, and security. We then outline the various methods in use today to build optical potentials starting from phenomenological, microscopic, and ab initio methods, highlighting in particular, the strengths and weaknesses of each approach. We then discuss publicly-available tools and resources facilitating the propagation of recent progresses in the field to practitioners. Finally, we provide a set of open challenges and recommendations for the field to advance the fundamental science goals of nuclear reaction studies in the rare-isotope beam era. This paper is the outcome of the Facility for Rare Isotope Beams Theory Alliance (FRIB-TA) topical program ‘Optical Potentials in Nuclear Physics’ held in March 2022 at FRIB. Its content is non-exhaustive, was chosen by the participants and reflects their efforts related to optical potentials.
|
|
| 5. |
- Salvioni, G., et al.
(författare)
-
Model nuclear energy density functionals derived from ab initio calculations
- 2020
-
Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 47:8
-
Tidskriftsartikel (refereegranskat)abstract
- We present the first application of a new approach, proposed in (2016 J. Phys. G: Nucl. Part. Phys. 43 04LT01) to derive coupling constants of the Skyrme energy density functional (EDF) from ab initio Hamiltonian. By perturbing the ab initio Hamiltonian with several functional generators defining the Skyrme EDF, we create a set of metadata that is then used to constrain the coupling constants of the functional. We use statistical analysis to obtain such an ab initio-equivalent Skyrme EDF. We find that the resulting functional describes properties of atomic nuclei and infinite nuclear matter quite poorly. This may point to the necessity of building up the ab initio-equivalent functionals from more sophisticated generators. However, we also indicate that the current precision of the ab initio calculations may be insufficient for deriving meaningful nuclear EDFs.
|
|
| 6. |
- Boström, J., et al.
(författare)
-
Spectroscopic factors with generator coordinate method and application to 25Mg states
- 2023. - 1
-
Ingår i: Journal of Physics: Conference Series. - 1742-6588. ; 2586
-
Konferensbidrag (refereegranskat)abstract
- Nuclei can be studied through the analysis of their shell structure, that provides important information on the wavefunctions useful for interpreting many phenomena, from excitations to transfer reactions. Spectroscopic factors provide the degree of single particle behaviour of a nuclear state and are used to represent the shell structure of a nucleus. In this manuscript, we expand our recently developed model, which uses the generator coordinate method with an effective Hamiltonian, to calculate spectroscopic factors of states of odd deformed nuclei. Here we provide the results for 25Mg.
|
|
| 7. |
- Idini, A., et al.
(författare)
-
Ab Initio Optical Potentials and Nucleon Scattering on Medium Mass Nuclei
- 2019
-
Ingår i: Physical Review Letters. - 0031-9007. ; 123:9
-
Tidskriftsartikel (refereegranskat)abstract
- We derive ab initio optical potentials from self-consistent Green's function theory and compute the elastic scattering of neutrons off oxygen and calcium isotopes. The comparison with scattering data is satisfactory at low scattering energies. The method is benchmarked against the no-core shell model with continuum calculations, showing that virtual excitations of the target are crucial to predict proper fragmentation and absorption at higher energies. This is a significant step toward deriving optical potentials for medium mass nuclei and complex many-body systems in general.
|
|
| 8. |
- Idini, A., et al.
(författare)
-
Collective wavefunction of Yrast states in 50Cr
- 2024
-
Ingår i: Nuovo Cimento della Societa Italiana di Fisica C. - 2037-4909. ; 47:2
-
Tidskriftsartikel (refereegranskat)abstract
- In the generator coordinate method the wavefunctions are defined with respect to reference states that can indicate different shapes and deformations, which are examples of collective generator coordinates. In this work, we study the collective wavefunctions of Yrast states up to the terminating state of 50Cr using a recently introduced framework to calculate projected states of spins up to I = 14 based on effective Hamiltonians and a 5 dimensional collective coordinate space.
|
|
| 9. |
- Idini, A.
(författare)
-
Statistical learnability of nuclear masses
- 2020
-
Ingår i: Physical Review Research. - 2643-1564. ; 2:4
-
Tidskriftsartikel (refereegranskat)abstract
- After more than 80 years from the seminal work of Weizsäcker and the liquid drop model of the atomic nucleus, deviations from experiments of mass models (~MeV) are orders of magnitude larger than experimental errors (~keV). Predicting the mass of atomic nuclei with precision is extremely challenging. This is due to the nontrivial many-body interplay of protons and neutrons in nuclei, and the complex nature of the nuclear strong force. Statistical theory of learning will be used to provide the bounds to prediction errors of a model trained with a finite data set. These bounds are validated with neural network models and compared with state of the art mass models. It will be argued that nuclear structure mass models explore a system on the limit of the precision bounds, as defined by the statistical theory of learning.
|
|
| 10. |
- Idini, A., et al.
(författare)
-
Towards microscopic optical potentials in deformed nuclei
- 2023. - 1
-
Ingår i: Journal of Physics: Conference Series. - 1742-6588. ; 2586
-
Konferensbidrag (refereegranskat)abstract
- A microscopic and consistent description of both nuclear structure and reactions is instrumental to extend the predictivity of models calculating scattering observables. In particular, this is crucial in the case of exotic nuclei not yet discovered. In this manuscript, we will present the plan of the Lund effort for a symmetry breaking description of bound and scattering observables using a generator coordinate method model based on an effective Hamiltonian constrained with a (Skyrme) functional. Following this, we will illustrate the steps to construct an optical potential for deformed nuclei from microscopic wavefunctions obtained with projected generator coordinate method from Hartree-Fock-Bogoliubov basis.
|
|
