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 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 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.

The mass-number dependence studies for the multiplicity of shower particles produced in interactions of different projectiles with emulsion nuclei at 3.7 GeV/n in the framework of the modified Glauber models I and II

2009 ◽  
Vol 87 (8) ◽  
pp. 945-956 ◽  
Author(s):  
M. S.M. Nour El-Din ◽  
M. E. Solite
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Reaction Cross ◽  
Total Reaction ◽  
Binary Collisions ◽  
Zero Range ◽  
Reaction Cross Sections ◽  
Better Than ◽  
Good Agreement

In the present work, we calculate the total reaction cross sections for the reactions of the following projectiles: P, 12C, 14N, 16O, 22Ne, 24Mg, 28Si, and 32S with emulsion nuclei, at incident energy ELab = 3.7 GeV/n, in the framework of the modified Glauber models I and II (Gl-I and Gl-II approaches). At the same time the number of interacted nucleons from these projectiles and the emulsion target nuclei beside the number of their binary collisions are calculated. Also the multiplicity of the shower particles produced in these reactions are calculated. A comparison between the calculated values of these total reaction cross sections and their multiplicities of the produced shower particles in these reactions, with the corresponding measured values, had been done within both: Gl-I and Gl-II approaches and in accordance to the zero-range considerations. As a result of this comparison we have not obtained an agreement between the calculated values and the corresponding experimental data in case of the total reaction cross sections, but we have got, in general, a good agreement for the comparison in the case of the particle multiplicities calculations. It should be noted, for the last comparison, that the theoretical calculations in the framework of Gl-II approach give, in general, agreement with the corresponding experimental data better than those we have obtained for the theoretical calculations in the framework of the Gl-I approach.

scholarly journals Statistical model calculations of the 232Th(n,2n) reaction

2019 ◽  
Vol 11 ◽  
Author(s):  
D. Karamanis ◽  
S. Andriamonje ◽  
P. A. Assimakopoulos ◽  
G. Doukellis ◽  
D. A. Karademos ◽  
...  
Keyword(s):  
Experimental Data ◽  
Statistical Model ◽  
Cross Sections ◽  
Nuclear Reactions ◽  
Level Density ◽  
Computer Code ◽  
Reaction Cross ◽  
Tandem Accelerator ◽  
Model Calculations ◽  
Equilibrium Evaporation

On the context of the Cern n_TOF collaboration the 232Th(n,2n)231Th reaction cross section has been measured relative to the 56Fe(n,p)56Mn and 27Al(n,a)24Na reaction cross sections by the activation method for neutron energies up to 11 MeV. The neutrons were produced via the 2H(d,n) reaction using a deuterium filled gas-cell, at the 5.5MV TANDEM Accelerator of NCSR "Demokritos". In addition to the experimental work, theoretical Statistical model calculations have been performed using the computer code STAPRE/F. The code STAPRE is designed to calculate energy averaged cross sections for particle induced nuclear reactions with several emitted particles and gamma rays under the assumption of sequential evaporation. For the first evaporation step preequilibrium emission is taken into account while population of states resulting from the first equilibrium evaporation step is calculated using the Hauser-Feschbach theory. Fission process competition is also taken into account in the evaporation steps. Sensitive parameters for the calculation, like level density parameters, have been adopted after fitting experimental data for the competing (n,f) reaction. The results are being compared to the experimental data.

MICROSCOPICAL ANALYSIS OF THE REACTION CROSS-SECTIONS OF 11Li+12C and 22C+12C ELASTIC SCATTERING

2011 ◽  
Vol 20 (03) ◽  
pp. 721-732 ◽  
Author(s):  
AWAD A. IBRAHEEM
Keyword(s):  
Experimental Data ◽  
Elastic Scattering ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Reaction Cross ◽  
Halo Nuclei ◽  
Neutron Halo ◽  
Nucleon Density ◽  
First Time ◽  
Reaction Cross Sections

Total reaction cross-sections of the two neutron halo nuclei 11Li and 22C elastic scattering from 12C target at E = 30–1000 MeV/nucleon have been analyzed using the eikonal phase shift based, for the first time, on the semi-phenomenological nucleon density. The obtained results reasonably agree with those of previous theoretical calculations as well as the corresponding experimental data.

STRUCTURE EFFECTS IN COLLISIONS INDUCED BY HALO AND WEAKLY BOUND NUCLEI AROUND THE COULOMB BARRIER

2010 ◽  
Vol 19 (05n06) ◽  
pp. 1236-1240 ◽  
Author(s):  
V. SCUDERI ◽  
A. DI PIETRO ◽  
L. ACOSTA ◽  
F. AMORINI ◽  
M. J. G. BORGE ◽  
...  
Keyword(s):  
Cross Sections ◽  
Coulomb Barrier ◽  
Center Of Mass ◽  
Reaction Cross ◽  
Angular Distributions ◽  
Weakly Bound ◽  
Model Calculations ◽  
Center Of Mass Energy ◽  
Reaction Channels ◽  
Reaction Cross Sections

In this contribution, results concerning different reaction channels for the collisions induced by the three Be isotopes, 9,10,11 Be , on a 64 Zn target at energies around the Coulomb barrier will be presented. The experiments with the radioactive 10,11 Be beams were performed at REX-ISOLDE (CERN) whereas the experiment with the stable weakly bound 9 Be beam was performed at LNS Catania. Elastic scattering angular distributions have been measured for the three systems 9,10,11 Be + 64 Zn at the same center of mass energy. The angular distributions were analyzed with optical potentials and reaction cross sections were obtained from optical model calculations, performed with the code PTOLEMY. For the 11 Be + 64 Zn reaction, the break-up angular distribution was also measured.

scholarly journals Critical review of CIELO evaluations of n+ 235U, 238U using differential experiments

2018 ◽  
Vol 4 ◽  
pp. 27 ◽  
Author(s):  
Roberto Capote ◽  
Andrej Trkov
Keyword(s):  
Cross Sections ◽  
Critical Review ◽  
Nuclear Data ◽  
Reaction Cross ◽  
Reaction Models ◽  
Reaction Channels ◽  
Data Files ◽  
Integral Data ◽  
Evaluated Nuclear Data ◽  
Reaction Cross Sections

Key reactions have been selected to compare JEFF-3.3 (CIELO 2) and IAEA CIELO (CIELO 1) evaluated nuclear data files for neutron induced reactions on 235U and 238U targets. IAEA CIELO evaluation uses reaction models to construct the evaluation prior, but strongly relied on differential data including all reaction cross sections fitted within the IAEA Neutron Standards project. The JEFF-3.3 evaluation relied on a mix of differential and integral data with strong contribution from nuclear reaction modelling. Differences in evaluations are discussed; a better reproduction of differential data for the IAEA CIELO evaluation is shown for key reaction channels.

Nonequilibrium effects in α-particle induced reactions on gallium isotopes

1989 ◽  
Vol 67 (9) ◽  
pp. 870-875 ◽  
Author(s):  
I. A. Rizvi ◽  
M. K. Bhardwaj ◽  
M. Afzal Ansari ◽  
A. K. Chaubey
Keyword(s):  
Cross Sections ◽  
Residual Nucleus ◽  
Reaction Cross ◽  
Activation Technique ◽  
Individual Reaction ◽  
Reaction Channels ◽  
Stacked Foil Activation Technique ◽  
The Individual ◽  
Reaction Cross Sections

The stacked foil activation technique and Ge(Li) γ-ray spectroscopy have been employed for the determination of the excitation functions, up to 60 MeV, of six reactions, 69Ga(α,n), (α,2n), (α,3n), (α,p3n); 71Ga(α,n) and (α,4n). Since natural gallium used as the target has two odd-mass stable isotopes of abundance, 69Ga(60.1%) and 71Ga(39.9%), their activation in some cases gives the same residual nucleus through different reaction channels, but with very different Q values. In such cases, the individual reaction cross sections are separated with the help of the ratio of their theoretical cross sections. A preliminary theoretical comparison with the preequilibrium geometry-dependent hybrid (GDH) model has been done using an initial exciton number no = 4 (2n + 2p + 0h), and general agreement was found for all reactions at high energies.

(n, p) Reaction Cross Sections Calculations of Some Stellar Iron Group Fusion Materials

2017 ◽  
Vol 6 (1) ◽  
pp. 18-25 ◽  
Author(s):  
Tarik Siddik
Keyword(s):  
Cross Sections ◽  
Reaction Cross ◽  
Nuclear Model ◽  
Incident Neutron ◽  
Excitation Functions ◽  
Model Calculations ◽  
Model Code ◽  
Group Target ◽  
Reaction Cross Sections ◽  
Group Fusion

The excitation functions for (n, p) reactions from reaction threshold to 24 MeV on some important iron (Fe) group target elements (20 ≤ Z ≤ 28) for astrophysical (n, p) reactions such as Si, Ca, Sc, Ti, Cr, Fe, Co and Ni were calculated using TALYS-1.0 nuclear model code. The new calculations on the excitation functions of 28Si(n, p)28Al, 29Si(n, p)29Al, 42Ca(n, p)42K, 45Sc(n, p)45Ca, 46Ti(n, p)46Sc, 53Cr(n, p)53V, 54Fe(n, p)54Mn, 57Fe(n, p)57Mn, 59Co(n, p)59Fe, 58Ni(n, p)58Co and 60Ni(n, p)60Co reactions have been carried out up to 24 MeV incident neutron energy. In these calculations, the compound nucleus and pre-equilibrium reaction mechanism studied extensively. According to these calculations, we assume that these model calculations can be applied to some heavy elements, ejected into interstellar medium by dramatic supernova events.

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