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 7Be and 8B reaction dynamics at Coulomb barrier energies

2018 ◽  
Vol 184 ◽  
pp. 02015
Author(s):  
E. Strano ◽  
M. Mazzocco ◽  
A. Boiano ◽  
C. Boiano ◽  
M. La Commara ◽  
...  
Keyword(s):  
Cross Sections ◽  
Coulomb Barrier ◽  
Reaction Cross Section ◽  
Optical Model ◽  
Reaction Dynamics ◽  
Reaction Cross ◽  
Total Reaction Cross Section ◽  
Weakly Bound ◽  
Total Reaction ◽  
Reaction Cross Sections

We investigated the reaction dynamics induced by the 7Be,8B+208Pb collisions at energies around the Coulomb barrier. Charged particles originated by both the col- lisions were detected by means of 6 ΔE-Eres telescopes of a newly developed detector array. Experimental data were analysed within the framework of the Optical Model and the total reaction cross-sections were compared together and with the 6,7Li+208Pb colli-sion data. According to the preliminary results, 7Be nucleus reactivity is rather similar to the 7Li one whereas the 8B+208Pb total reaction cross section appears to be much larger than those measured for reactions induced by the other weakly-bound projectiles on the same target.

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 Experimental measurement of the 12C+16O fusion cross sections at astrophysical energies

2018 ◽  
Vol 178 ◽  
pp. 04008
Author(s):  
X. Fang ◽  
W. P. Tan ◽  
M. Beard ◽  
R. J. deBoer ◽  
G. Gilardy ◽  
...  
Keyword(s):  
Cross Sections ◽  
Center Of Mass ◽  
Model Calculations ◽  
Center Of Mass Energy ◽  
Pure Graphite ◽  
S Factor ◽  
Hpge Detectors ◽  
Low Energies ◽  
The University

The total cross sections of the 12C+16O fusion have been experimentally determined at low energies to investigate the role of this reaction during late stellar evolution burning phases. A high-intensity oxygen beam was produced by the 5MV pelletron accelerator at the University of Notre Dame impinging on a thick ultra-pure graphite target. Protons and γ-rays were measured simultaneously in the center-of-mass energy range from 3.64 to 5.01 MeV, using strip silicon and HPGe detectors. Statistical model calculations were employed to interpret the experimental results. A new broad resonance-like structure is observed for the 12C+16O reaction, and a decreasing trend of its S-factor towards low energies is found.

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.

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.

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