Electron-capture modes with realistic nuclear structure calculations

HNPS Proceedings ◽

10.12681/hnps.1997 ◽

2019 ◽

Vol 21 ◽

pp. 4

Author(s):

P. G. Giannaka ◽

T. S. Kosmas

Keyword(s):

Electron Capture ◽

Cross Sections ◽

Nuclear Reactions ◽

Random Phase ◽

Point Of View ◽

Electron Neutrino ◽

Β Decay ◽

Decay Modes ◽

Theory Point ◽

Nuclear Structure Calculations

Nuclear electron capture posses prominent position among other weak interaction processes occuring in explosive nucleosynthesis. In particular, this process plays important role in the core-colapse of massive stars by modifying the electron to baryon ratio Ye. From a nuclear theory point of view, such processes may be studied by using the same nuclear methods (e.g. the quasi-particle random phase approximation, QRPA), employed in the present work with these used for the one-body charge changing nuclear reactions (β-decay modes, charged-current electron-neutrino absorption by nuclei, etc). In this work we calculate e−-capture cross sections on 56Fe using two different approaches. At first, original cross section calculations are perfored by using the pn-QRPA method considering all the accessible transitions of the final nucleus 56Mn. Secondly, we evaluate the Gamow-Teller strength distributions and obtain the cross sections at the limit of zero-momentum transfer. The agreement between the two methods is very good.

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Electron-capture and beta-decay modes with realistic nuclear structure calculations

HNPS Proceedings ◽

10.12681/hnps.2495 ◽

2012 ◽

Vol 20 ◽

pp. 112

Author(s):

P. G. Giannaka ◽

T. S. Kosmas

Keyword(s):

Excited States ◽

Meson Exchange ◽

Exchange Potential ◽

Β Decay ◽

Decay Modes ◽

Nuclear Structure Calculations ◽

Analytical Expressions ◽

Structure Calculations ◽

Gamow Teller

In this work, we concentrate on the e-capture and β-decay processes in isotopes that are important for searching the explosive nucleosynthesis in massive stars. To this aim, we improved our codes which use compact analytical expressions for the required reduced matrix elements of all basic multipole operators (isospin repre- sentation). The ground state of the nuclear isotopes chosen, is constructed in the context of the BCS method while their excited states are calculated by solving the QRPA equations, using as residual two-body interactions that of the Bonn C-D one-meson exchange potential. We focus on the role of the charged Gamow-Teller and Fermi transitions in Fe group nuclei that are the main constituents of the core in presupernovae formation.

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Electron Capture Cross Sections for Stellar Nucleosynthesis

Advances in High Energy Physics ◽

10.1155/2015/398796 ◽

2015 ◽

Vol 2015 ◽

pp. 1-11 ◽

Cited By ~ 11

Author(s):

P. G. Giannaka ◽

T. S. Kosmas

Keyword(s):

Electron Capture ◽

Cross Sections ◽

Random Phase ◽

Model Space ◽

Boltzmann Distribution ◽

Capture Cross ◽

Quasiparticle Random Phase Approximation ◽

Stellar Nucleosynthesis ◽

Exclusive Processes ◽

Capture Cross Sections

In the first stage of this work, we perform detailed calculations for the cross sections of the electron capture on nuclei under laboratory conditions. Towards this aim we exploit the advantages of a refined version of the proton-neutron quasiparticle random-phase approximation (pn-QRPA) and carry out state-by-state evaluations of the rates of exclusive processes that lead to any of the accessible transitions within the chosen model space. In the second stage of our present study, we translate the abovementionede--capture cross sections to the stellar environment ones by inserting the temperature dependence through a Maxwell-Boltzmann distribution describing the stellar electron gas. As a concrete nuclear target we use the66Zn isotope, which belongs to the iron group nuclei and plays prominent role in stellar nucleosynthesis at core collapse supernovae environment.

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β-DECAY OF KEY TITANIUM ISOTOPES IN STELLAR ENVIRONMENT

International Journal of Modern Physics E ◽

10.1142/s0218301311018174 ◽

2011 ◽

Vol 20 (03) ◽

pp. 705-719

Author(s):

JAMEEL-UN NABI ◽

IRGAZIEV BAKHADIR

Keyword(s):

Electron Capture ◽

Large Scale ◽

Massive Stars ◽

Random Phase ◽

Neutrino Energy ◽

Decay Rates ◽

Β Decay ◽

Quasiparticle Random Phase Approximation ◽

Stellar Temperatures ◽

Titanium Isotopes

Amongst iron regime nuclei, β-decay rates on titanium isotopes are considered to be important during the late phases of evolution of massive stars. The key β-decay isotopes during presupernova evolution were searched from available literature and a microscopic calculation of the decay rates were performed using the proton–neutron quasiparticle random phase approximation (pn-QRPA) theory. As per earlier simulation results, electron capture and β-decay on certain isotopes of titanium are considered to be important for the presupernova evolution of massive stars. Earlier the stellar electron capture rates and neutrino energy loss rates due to relevant titanium isotopes were presented. In this paper we finally present the β-decay rates of key titanium isotopes in stellar environment. The results are also compared against previous calculations. The pn-QRPA β-decay rates are bigger at high stellar temperatures and smaller at high stellar densities compared to the large scale shell model results. This study can prove useful for the core-collapse simulators.

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Cross sections for the neutral current νe - 116Cd scattering reaction

HNPS Proceedings ◽

10.12681/hnps.2586 ◽

2020 ◽

Vol 16 ◽

pp. 97

Author(s):

K. G. Balasi ◽

T. S. Kosmas ◽

P. C. Divari ◽

V. C. Chasioti

Keyword(s):

Cross Sections ◽

Neutral Current ◽

Random Phase ◽

Initial Energy ◽

Electron Neutrino ◽

Excitation Energies ◽

Quasi Particle ◽

Neutrino Scattering ◽

Supernova Neutrino ◽

Nuclear Response

The cross sections for neutrino scattering off the 116Cd nucleus have been computed by utilizing the Quasi-particle Random Phase Approximation (QRPA). An- gular and initial energy dependence of the neutrino-nucleus cross sections have been calculated at low and intermediate electron neutrino energies up to 100 MeV. By solving the QRPA equations and fixing the appropriate parameters the lowest lying excitation energies spectrum was reproduced. The contributions from multipole ex- citations was examined. The obtained results could be used for studying the nuclear response of this isotope to supernova neutrino spectra.

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Nuclear study of the exotic neutrino interactions

HNPS Proceedings ◽

10.12681/hnps.1934 ◽

2019 ◽

Vol 22 ◽

pp. 79

Author(s):

D. K. Papoulias ◽

T. S. Kosmas

Keyword(s):

Cross Sections ◽

Neutral Current ◽

Point Of View ◽

High Confidence ◽

Oak Ridge ◽

Nuclear Study ◽

Theory Point ◽

Nucleus Scattering ◽

Event Rates ◽

Nuclear Detectors

Open neutrino physics issues require precision studies, both theoretical and experimental ones, and towards this aim coherent neutral current neutrino-nucleus scattering events are expected to be observed soon. In this work, we explore ν -nucleus processes from a nuclear theory point of view and obtain results with high confidence level based on accurate nuclear structure cross sections calculations. The present study explores the differential event rates as well as the total number of events expected to be measured by nuclear detectors, indicating measurable rates. We concentrate on the possibility of detecting supernova neutrinos by using massive detectors like those of the GERDA and SuperCDMS dark matter experiments and at spallation neutron source facilities (at Oak Ridge National Lab) by the COHERENT experiment.

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Studying supernova neutrinos through nuclear structure calculations

HNPS Proceedings ◽

10.12681/hnps.2552 ◽

2019 ◽

Vol 18 ◽

pp. 193

Author(s):

V. Tsakstara ◽

T. S. Kosmas ◽

J. Sinatkas

Keyword(s):

Cross Sections ◽

Random Phase ◽

Neutrino Energy ◽

Double Beta Decay ◽

Quasi Particle ◽

Supernova Neutrinos ◽

Nuclear Structure Calculations ◽

Structure Calculations ◽

Two Parameter ◽

Astrophysical Neutrino

Differential and integrated cross section calculations are performed in the context of the quasi particle random phase approximation (QRPA) by utilizing realistic two- nucleon forces, for the 64,66 Zn isotopes, contents of the COBRA double beta decay detector. For these isotopes the response to supernova neutrinos is of current inter- est. The response of the 66 Zn isotope to the energy-spectra of supernova neutrinos is also explored by convoluting the original results for the differential cross sections by employing: (i) a two-parameter Fermi-Dirac (FD) and (ii) a Power-Law (PL) neutrino energy distribution. Such folded cross sections are useful in low-energy astrophysical-neutrino detection in underground terrestrial experiments.

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Inclusive neutrino-nucleus reaction cross sections at intermediate energies

HNPS Proceedings ◽

10.12681/hnps.2892 ◽

2020 ◽

Vol 5 ◽

pp. 29

Author(s):

T. S. Kosmas ◽

E. Oset

Keyword(s):

Cross Section ◽

Cross Sections ◽

Reaction Cross ◽

Point Of View ◽

Electron Neutrino ◽

Muon Capture ◽

Light Nuclei ◽

Experimental Point ◽

Intermediate Energies ◽

Reaction Cross Sections

Inclusive neutrino-nucleus reaction cross sections at intermediate energies (20 MeV < Ey < 500 MeV) are calculated throughout the periodic table for the most interesting nu clei from an experimental point of view. The method used had previously proved to be very accurate in calculating the induced reaction cross section for T=0 light nuclei (12C and 16O) and in the study of other similar processes like the ordinary muon capture. The electron-neutrino (ve) cross section weighted by the Michel distribution is also discussed in conjuction with the existing experimental results at LAMPF and ΚARMEN.

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Standard and Nonstandard Neutrino-Nucleus Reactions Cross Sections and Event Rates to Neutrino Detection Experiments

Advances in High Energy Physics ◽

10.1155/2015/763648 ◽

2015 ◽

Vol 2015 ◽

pp. 1-17 ◽

Cited By ~ 30

Author(s):

D. K. Papoulias ◽

T. S. Kosmas

Keyword(s):

Cross Sections ◽

Particle Physics ◽

Point Of View ◽

Oak Ridge ◽

Upper Limits ◽

The Standard Model ◽

Theory Point ◽

Event Rates ◽

Nuclear Detectors ◽

Lepton Flavour

In this work, we exploreν-nucleus processes from a nuclear theory point of view and obtain results with high confidence level based on accurate nuclear structure cross sections calculations. Besides cross sections, the present study includes simulated signals expected to be recorded by nuclear detectors and differential event rates as well as total number of events predicted to be measured. Our original cross sections calculations are focused on measurable rates for the standard model process, but we also perform calculations for various channels of the nonstandard neutrino-nucleus reactions and come out with promising results within the current upper limits of the corresponding exotic parameters. We concentrate on the possibility of detecting (i) supernova neutrinos by using massive detectors like those of the GERDA and SuperCDMS dark matter experiments and (ii) laboratory neutrinos produced near the spallation neutron source facilities (at Oak Ridge National Lab) by the COHERENT experiment. Our nuclear calculations take advantage of the relevant experimental sensitivity and employ the severe bounds extracted for the exotic parameters entering the Lagrangians of various particle physics models and specifically those resulting from the charged lepton flavour violatingμ-→e-experiments (Mu2e and COMET experiments).

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Neutral-Current Neutrino-Nucleus Scattering off Xe Isotopes

Advances in High Energy Physics ◽

10.1155/2018/9163586 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11 ◽

Cited By ~ 9

Author(s):

P. Pirinen ◽

J. Suhonen ◽

E. Ydrefors

Keyword(s):

Nuclear Structure ◽

Cross Sections ◽

Direct Detection ◽

Neutral Current ◽

Random Phase ◽

Solar Neutrinos ◽

Neutrino Energy ◽

Quasiparticle Random Phase Approximation ◽

Nucleus Scattering ◽

Nuclear Structure Calculations

Large liquid xenon detectors aiming for dark matter direct detection will soon become viable tools also for investigating neutrino physics. Information on the effects of nuclear structure in neutrino-nucleus scattering can be important in distinguishing neutrino backgrounds in such detectors. We perform calculations for differential and total cross sections of neutral-current neutrino scattering off the most abundant xenon isotopes. The nuclear-structure calculations are made in the nuclear shell model for elastic scattering and also in the quasiparticle random-phase approximation (QRPA) and microscopic quasiparticle-phonon model (MQPM) for both elastic and inelastic scattering. Using suitable neutrino energy distributions, we compute estimates of total averaged cross sections for 8B solar neutrinos and supernova neutrinos.

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