The Nuclear Reaction Network WinNet Reichert, M.; Winteler, C.; Korobkin, O. ...
The Astrophysical journal. Supplement series,
10/2023, Letnik:
268, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Abstract
We present the state-of-the-art single-zone nuclear reaction network
WinNet
, which is capable of calculating the nucleosynthetic yields of a large variety of astrophysical environments and ...conditions. This ranges from the calculation of the primordial nucleosynthesis, where only a few nuclei are considered, to the ejecta of neutron star mergers with several thousands of involved nuclei. Here we describe the underlying physics and implementation details of the reaction network. We additionally present the numerical implementation of two different integration methods, the implicit Euler method and Gears method, along with their advantages and disadvantages. We furthermore describe basic example cases of thermodynamic conditions that we provide together with the network and demonstrate the reliability of the code by using simple test cases. With this publication,
WinNet
will be publicly available and open source at GitHub and Zenodo.
We have carried out an (e,e'p) experiment at high momentum transfer and in parallel kinematics to measure the strength of the nuclear spectral function S(k,E) at high nucleon momenta k and large ...removal energies E. This strength is related to the presence of short-range and tensor correlations, and was known hitherto only indirectly and with considerable uncertainty from the lack of strength in the independent-particle region. This experiment locates by direct measurement the correlated strength predicted by theory.
Nuclear physics is a basic ingredient in a large number of energetic astrophysical environments which are characterized by sufficient temperatures and densities to permit scattering events among ...particles, leading to nuclear reactions and possibly the production of unstable reaction poducts. Strong, electromagnetic and weak interactions (fusion, exchange reactions, photodisintegrations, beta-decays, electron and positron captures on nucleons and nuclei, neutrino scattering and captures i.e. neutral and charged current reactions) can produce nuclei far form stability and require extended knowledge of nuclear structure near and far from stability, including decay and fission properties. Last, but not least, the nucleon-nucleon interaction determines the nuclear equation of state at and beyond nuclear densities and is ultimately connected to the question under which conditions a phase transitions from hadrons to the quark-gluon plasma occurs. In this review we will survey how these aspects of nuclear physics enter the modeling of astrophysical objects.
A simple description for obtaining the parity distribution of nuclear levels in the
pf + g
9
2
shell as a function of excitation energy was recently derived. We implement this in a global nuclear ...level density model. In the framework of the statistical model, cross sections and astrophysical reaction rates are calculated in the Fe region and compared to rates obtained with the common assumption of an equal distribution of parities. We find considerable differences, especially for reactions involving particles in the exit channel.
Production of intermediate-mass and heavy nuclei Thielemann, F.-K.; Fröhlich, C.; Hirschi, R. ...
Progress in particle and nuclear physics,
07/2007, Letnik:
59, Številka:
1
Journal Article, Publication
Recenzirano
Odprti dostop
Nucleosynthesis is the science related to all astrophysical processes which are responsible for the abundances of the elements and their isotopes in the universe. The astrophysical sites are the big ...bang and stellar objects. The working of nucleosynthesis processes is presented in a survey of events which act as abundance sources. For intermediate-mass and heavy elements, these are stellar evolution, type Ia and core collapse supernovae as well as hypernovae. We discuss successes and failures of existing processes and possible solutions via new (hitherto unknown) processes. Finally an analysis of their role is given in the puzzle to explain the evolution of the elemental and isotopic compositions found in galaxies, and especially the mixture found in the solar system. Different timescales due to the progenitor mass dependence of the endpoints of stellar evolution (type II supernova explosions — SNe II vs. planetary nebulae) or single vs. binary stellar systems (the latter being responsible for novae, type Ia supernovae — SNe Ia, or X-ray bursts) are the keys to understand galactic evolution. At very early times, the role of explosion energies of events, polluting pristine matter with a composition originating only from the big bang, might also play a role. We also speculate on the role of very massive stars not undergoing SN II explosions but rather causing “hypernovae” after the formation of a central black hole via core collapse.
Astrophysical reaction rates are sensitive to the parity distribution at low excitation energies. We combine a formula for the energy-dependent parity distribution with a microscopic-macroscopic ...nuclear level density. This approach describes well the transition from low excitation energies where a single parity dominates to high excitations where the two densities are equal.
The role of fission in the r-process Martínez-Pinedo, G.; Mocelj, D.; Zinner, N.T. ...
Progress in particle and nuclear physics,
07/2007, Letnik:
59, Številka:
1
Journal Article
Recenzirano
We have developed a full set of fission rates that include spontaneous fission, neutron-induced fission, beta-delayed fission and, neutrino-induced fission, that are supplemented with realistic ...distributions of fission yields. Using this new input data we have carried out r-process calculations assuming adiabatic expansions that mimic the conditions achieved in the supernova neutrino driven wind. We have explored the sensitivity of the final abundances to different mass models. The resulting abundance distribution turns out to be very sensitive to the strength of the
N
=
82
shell gap far from stability. Mass models with a strong shell gap converge to an r-process distribution that is independent of the initial conditions once fission sets in. This convergence is not achieved in mass models with a quenched
N
=
82
shell gap.
We present the state-of-the-art single-zone nuclear reaction network WinNet that is capable of calculating the nucleosynthetic yields of a large variety of astrophysical environments and conditions. ...This ranges from the calculation of the primordial nucleosynthesis, where only a few nuclei are considered, to the ejecta of neutron star mergers with several thousands of involved nuclei. Here we describe the underlying physics and implementation details of the reaction network. We additionally present the numerical implementation of two different integration methods, the implicit Euler method and Gears method along with their advantages and disadvantages. We furthermore describe basic example cases of thermodynamic conditions that we provide together with the network and demonstrate the reliability of the code by using simple test cases. With this publication, WinNet is publicly available and open source at GitHub and Zenodo.
We present spin- and parity-resolved level densities extracted from high-resolution hadron and electron scattering data by means of a fluctuation analysis. A nearly model-independent method based on ...discrete wavelet transform is introduced for the determination of a non-resonant background. The data obtained are compared to the predictions of two models widely used in applications for astrophysical network calculations with an emphasis on a possible parity dependence of nuclear level densities.
PDF
