scholarly journals Thermonuclear Reaction Rates for Reactions Leading to N = 28 Nuclei

1995 ◽  
Vol 48 (1) ◽  
pp. 125
Author(s):  
A.J Morton ◽  
DG Sargood
Keyword(s):  
Statistical Model ◽  
Nuclear Reaction ◽  
Cross Sections ◽  
Optical Model ◽  
Reaction Rates ◽  
Reaction Cross ◽  
Model Parameters ◽  
Thermonuclear Reaction ◽  
Model Calculations ◽  
Reaction Cross Sections

Nuclear reaction cross sections derived from statistical-model calculations have been used in the calculation of thermonuclear reaction rates for 36 nuclei at temperatures that are representative of the interiors of evolving stars and supernovae as nucleosynthesis approaches the production of nuclei with N = 28. The statistical-model calculations used optical-model parameters in the particle channels which had been selected to give the best overall agreement between theoretical and experimental cross sections for reactions on stable target nuclei in the mass and energy ranges of importance for the stellar conditions of interest. The optical-model parameters used, and the stellar reaction rates obtained, are tabulated. Comparisons are made between these stellar rates and those from other statistical-model calculations in the literature.

scholarly journals Statistical-model calculations for α-capture reactions relevant to the p process

2019 ◽  
Vol 26 ◽  
pp. 228
Author(s):  
C. Fakiola ◽  
I. Karakasis ◽  
I. Sideris ◽  
A. Khaliel ◽  
T. J. Mertzimekis
Keyword(s):  
Experimental Data ◽  
Statistical Model ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Reaction Network ◽  
Reaction Cross ◽  
Model Parameters ◽  
Model Calculations ◽  
Reaction Channels ◽  
Reaction Cross Sections

About 35 nuclides which lie on the neutron deficient side of the isotopic chart cannot be created by the two basic nucleosynthetic processes, the sand the rprocess. Due to scarce experimental data and the vast complexity of the reaction network involved, cross sections and reactions are estimated theoretically, using the Hauser–Feshbach statistical model. In the present work, theoretical calculations of cross sections of radiative α-capture reactions on the neutron–deficient Erbium and Xenon isotopes are presented in an attempt to make predictions inside the astrophysically relevant energy window (Gamow). The particular reactions are predicted to be sensitive branchings in the γprocess path.The most recent versions of TALYS (v1.9) and Fresco codes were employed for all calculations, initially focusing on investigating the influence of the default eight (8) α–nucleus optical potential models of TALYS on reaction cross sections. The theoretical results of both codes are compared and for the reactions where experimental data exist in literature, the optical model parameters were adjusted appropriately to best describe the data and were subsequently used for estimating (α,γ) reaction cross sections. Predictions for the (α,n) reaction channels have also been calculated and studied.

scholarly journals Statistical model calculations of 72,73Ge(n,p) and 72,74Ge(n,α) reactions on natural Ge

2020 ◽  
Vol 15 ◽  
pp. 104
Author(s):  
S. Galanopoulos ◽  
R. Vlastou ◽  
P. Demetriou ◽  
M. Kokkoris ◽  
C. T. Papadopoulos ◽  
...  
Keyword(s):  
Statistical Model ◽  
Energy Range ◽  
Neutron Energy ◽  
Cross Sections ◽  
Reaction Cross ◽  
Model Calculations ◽  
Monoenergetic Neutron ◽  
Theoretical Investigations ◽  
Equilibrium Emission ◽  
Reaction Cross Sections

Systematic experimental and theoretical investigations of the 72,73Ge(n,p)72,73 Ga and 72,74Ge(n,α)69,71Znm reaction cross sections are presented in the energy range from thresh- old to about 17 MeV neutron energy. The above reaction cross sections were measured from 8.8 to 11.4 MeV by using the activation method, relative to the 27Al(n,α)24Na refer- ence reaction. The quasi-monoenergetic neutron beams were produced via the 2H(d,n)3He reaction at the 5 MV VdG Tandem T11/25 accelerator of NCSR “Demokritos”. Statisti- cal model calculations using the code EMPIRE-II (version 2.19) taking into consideration pre-equilibrium emission were performed on the data measured in this work as well as on data reported in literature.

scholarly journals Isomeric Cross Section Study of neutron induced reactions on Ge

2020 ◽  
Vol 16 ◽  
pp. 169
Author(s):  
R. Vlastou ◽  
S. Galanopoulos ◽  
C. T. Papadopoulos ◽  
M. Kokkoris ◽  
M. Serris ◽  
...  
Keyword(s):  
Statistical Model ◽  
Cross Section ◽  
Cross Sections ◽  
Reaction Cross ◽  
Model Calculations ◽  
Section Study ◽  
Reaction Cross Sections

The72Ge(n,α)69mZn, 74Ge(n,α)71mZn, 76Ge(n,2n)75g+mGe reaction cross sections have been measured from 9.6 to 11.4 MeV and studied, along with data from litera- ture, within the frame of statistical model calculations by using the code EMPIRE-II.

Cross Section Measurements for the Reactions 53Cr(p,g)54Mn, 53Cr(p,n)53Mn and 53Cr(p, p')53Cr

1981 ◽  
Vol 34 (1) ◽  
pp. 25 ◽  
Author(s):  
HJ Gardner ◽  
LW Mitchell ◽  
SR Kennett ◽  
MR Anderson ◽  
DG Sargood
Keyword(s):  
Statistical Model ◽  
Cross Section ◽  
Cross Sections ◽  
Proton Energy ◽  
Optical Model ◽  
Model Parameters ◽  
Model Calculations ◽  
Isobaric Analogue ◽  
Theory And Experiment

Cross sections have been measured for the reactions 53Cr(p, y)5 4Mn, 53Cr(p, n)53Mn and 53Cr(p, p/)53Cr over the proton energy range O'88-2'40 MeV. The results are compared with the predictions of statistical model, calculations with global optical model parameters, with particular reference to the role of isobaric analogue resonances. Satisfactory agreement between theory and experiment is achieved for all three reactions.

scholarly journals (p,γ) Reaction Cross Sections Relevant to the p process: First Results for the Se Isotopes

2020 ◽  
Vol 13 ◽  
pp. 161
Author(s):  
A. Lagoyannis ◽  
A. Spyrou ◽  
S. Harissopulos ◽  
S. Galanopoulos ◽  
R. Kunz ◽  
...  
Keyword(s):  
Cross Sections ◽  
Optical Model ◽  
Reaction Cross ◽  
Activation Technique ◽  
Nuclear Level ◽  
Proton Capture ◽  
Model Calculations ◽  
Level Densities ◽  
First Results ◽  
Reaction Cross Sections

Proton-capture reaction cross sections of Se isotopes were determined in the 1-6 MeV energy range by means of γ-angular distribution measurements as well as via the activation technique. In this report we compare our first cross-section results with statistical model calculations performed using various microscopic and phenomenological approaches of Optical Model Potentials and Nuclear Level Densities.

Cross sections and thermonuclear reaction rates for the 28Si(α, p)31P and 54Fe(α, p)57Co reactions

1984 ◽  
Vol 62 (2) ◽  
pp. 134-140 ◽  
Author(s):  
M. A. Buckby ◽  
J. D. King
Keyword(s):  
Statistical Model ◽  
Cross Sections ◽  
Ground State ◽  
Reasonable Agreement ◽  
Reaction Rates ◽  
Parametric Equation ◽  
Thermonuclear Reaction ◽  
Model Calculations ◽  
Experimental Cross

Absolute cross sections for the 28Si(α, p)31P and 54Fe(α, p)57Co reactions have been measured for laboratory bombarding energies over the range 5.52 ≤ Eα ≤ 12.00 MeV, using targets of approximately 4-keV thickness. Ground state reaction rates were then deduced from these cross sections and stellar rates were deduced by multiplying by the ratio of stellar-to-ground state rates obtained from statistical model calculations. Stellar rates for the reverse reactions have been determined and are fitted by a parametric equation for ease of interpolation. The experimental cross sections and rates have been compared with statistical model calculations and are in reasonable agreement for the 54Fe(α, p)57Co reaction but deviate by as much as a factor of three for the 28Si(α, p)31P reaction.

scholarly journals The 55Mn(p,?)56Fe and 55Mn(p,n)55Fe Cross Sections

1983 ◽  
Vol 36 (1) ◽  
pp. 1 ◽  
Author(s):  
LW Mitchell ◽  
DG Sargood
Keyword(s):  
Statistical Model ◽  
Energy Range ◽  
Cross Section ◽  
Cross Sections ◽  
Reaction Rates ◽  
Significant Part ◽  
Thermonuclear Reaction ◽  
Model Calculations ◽  
The Cross

The cross section of the reaction 55Mn(p, y)56Pe has been measured in the energy range 0�80-2�04 MeV and of the reaction 55Mn(p, n)55Pe from threshold to 2� 04 MeV. Statistical model calculations reproduce the (p, n) cross section to within a factor of 1� 4, but with the (p, y) reaction they fail by a factor ;;;:2 over a significant part of the energy range. Thermonuclear reaction rates are calculated from the data for temperatures in the range (1-5) x 109 K.

scholarly journals Capture reaction cross-section measurements relevant to p process: the case of (α , γ) reactions on 63Cu, 72Ge,118Sn and the 107Ag(ρ, γ)108Cd reaction

2020 ◽  
Vol 227 ◽  
pp. 01008
Author(s):  
Sotirios Harissopulos ◽  
Eleni Vagena ◽  
Michail Axiotis ◽  
Artemis Spyrou ◽  
Georgios Provatas ◽  
...  
Keyword(s):  
Statistical Model ◽  
Cross Section ◽  
Cross Sections ◽  
Optical Model ◽  
Reaction Cross ◽  
Model Calculations ◽  
Level Densities ◽  
Model Code ◽  
Section Data ◽  
Strength Functions

The cross sections of the 72Ge( α , γ)76Se and 1°7Ag(ρ, γ)1°8Cd reactions were measured at energies relevant to p-process nucleosynthesis. The new data, together with cross section results from our previous ( α , γ) measure-ments on 65Cu and 118Sn and other ( α , γ) cross-section data reported in lit-erature are compared with statistical model calculations performed using the latest version (1.9) of the statistical model code TALYS. In addition, the effect on these calculations of different combinations of the optical model potentials (OMPs), nuclear level densities (NLDs) and γ-ray strength functions (γSFs) entering the calculations was investigated.

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