Fast and precise exciton model calculations of nuclear reactions

1978 ◽  
Vol 288 (2) ◽  
pp. 175-177 ◽  
Author(s):  
J. Dobeš ◽  
E. Běták
Keyword(s):  
Nuclear Reactions ◽  
Exciton Model ◽  
Model Calculations

scholarly journals PRE-EQUILIBRIUM EFFECTS IN THE SECONDARY PARTICLE SPECTRA IN THE REACTIONS WITH HEAVY IONS

2010 ◽  
Vol 19 (05n06) ◽  
pp. 1134-1140 ◽  
Author(s):  
O. V. FOTINA ◽  
D. O. EREMENKO ◽  
YU. L. PARFENOVA ◽  
S. YU. PLATONOV ◽  
O. A. YUMINOV ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Heavy Ions ◽  
Nuclear Reactions ◽  
Level Density ◽  
Laboratory System ◽  
Nuclear Level Density ◽  
Model Calculations ◽  
Equilibrium Processes ◽  
Equilibrium Evaporation ◽  
Particle Spectra

Theoretical description of the experimentally obtained spectra for protons and α-particles and model calculations for the neutron spectra in the reactions with heavy ions has been presented. The hybrid model of non-equilibrium processes was used. Equilibrium evaporation process was analyzed in the framework of the statistical theory of nuclear reactions with Monte-Carlo simulation including certain dynamical and kinematical characteristics. This approach was included in PACE code, which permits to simulate Monte-Carlo de-excitation nuclear process. The Fermi-gas model and level-density phenomenological model for the variation of the nuclear level density parameters was used. In this approach data on 16 O +116 Sn reaction with Ebeam = 130, 250 MeV were analyzed. Double-differential light charged particle spectra for this reaction were measured using the GARFIELD apparatus in coincidence with evaporation residues. The experimental data were collected in four angular ranges from 29 to 41, 41 to 53, 53 to 67 and 67 to 82 degrees in the laboratory system. The results of the calculations are shown and discussed for these four angular ranges. The contributions from the evaporative and pre-equilibrium processes were analyzed in connection with different nucleus equilibration mechanisms.

Cascade-exciton model of nuclear reactions

1983 ◽  
Vol 401 (2) ◽  
pp. 329-361 ◽  
Author(s):  
K.K. Gudima ◽  
S.G. Mashnik ◽  
V.D. Toneev
Keyword(s):  
Nuclear Reactions ◽  
Exciton Model

MEASUREMENT AND ANALYSIS OF EXCITATION FUNCTIONS FOR ALPHA-INDUCED REACTIONS IN BISMUTH

1992 ◽  
Vol 01 (04) ◽  
pp. 823-831 ◽  
Author(s):  
B. P. SINGH ◽  
M. G. V. SANKARACHARYULU ◽  
M. A. ANSARI ◽  
R. PRASAD ◽  
H. D. BHARDWAJ
Keyword(s):  
Energy Range ◽  
Compound Nucleus ◽  
Projectile Energy ◽  
Exciton Model ◽  
Excitation Functions ◽  
Model Calculations ◽  
Stacked Foil Technique ◽  
Measurement And Analysis ◽  
Foil Technique

Excitation functions for 209 Bi (α, 3n), 209 Bi (α, 4n) and 209 Bi (α, 5n) reactions have been measured in the energy range threshold to ≈50 MeV using stacked foil technique. Excitation functions have also been theoretically calculated and as expected, inclusion of pre-equilibrium contribution based on exciton model calculations along with compound nucleus calculations using Hauser–Feshbach formalism reproduces well the measured excitation functions. Interesting trend in the ratio of pre-equilibrium to equilibrium component with projectile energy has been observed.

STAU-CATALYZED BIG-BANG NUCLEOSYNTHESIS AND NUCLEAR CLUSTER MODEL

2009 ◽  
Vol 24 (11) ◽  
pp. 2076-2083 ◽  
Author(s):  
M. KAMIMURA ◽  
Y. KINO ◽  
E. HIYAMA
Keyword(s):  
Cross Sections ◽  
Cluster Model ◽  
Nuclear Reactions ◽  
Light Element ◽  
Bound State ◽  
Big Bang ◽  
Reaction Cross ◽  
Big Bang Nucleosynthesis ◽  
Model Calculations ◽  
Three Body

Three-body cluster-model calculations are performed for the new types of big-bang nucleosynthesis (BBN) reactions that are calalyzed by a supersymmetric (SUSY) particle stau, a scalar partner of the tau lepton. If a stau has a lifetime ≳ 103s, it would capture a light element previously synthesized in standard BBN and form a Coulombic bound state. The bound state, an exotic atom, is expected to induce various reactions, such as (αX-) + d → 6 Li + X-, in which a negatively charged stau (denoted as X-) works as a catalyzer. Recent literature papers have claimed that some of these stau-catalyzed reactions have significantly large cross sections so that inclusion of the reactions into the BBN network calculation can change drastically abundances of some elements, giving not only a solution to the 6 Li -7 Li problem (calculated underproduction of 6 Li by ~ 1000 times and overproduction of 7 Li +7 Be by ~ 3 times) but also a constraint on the lifetime and the primordial abundance of the elementary particle stau. However, most of these literature calculations of the reaction cross sections were made assuming too naive models or approximations that are unsuitable for those complicated low-energy nuclear reactions. We use a few-body calculational method developed by the authors, and provides precise cross sections and rates of the stau-catalyzed BBN reactions for the use in the BBN network calculation.

PECULIARITIES OF NUCLEAR REACTIONS INDUCED BY 6He AND 6Li NUCLEI NEAR THE COULOMB BARRIER

2008 ◽  
Vol 17 (10) ◽  
pp. 2349-2353 ◽  
Author(s):  
YU. E. PENIONZHKEVICH ◽  
R. KALPAKCHIEVA ◽  
A. A. KULKO ◽  
S. M. LUKYANOV ◽  
V. A. MASLOV ◽  
...  
Keyword(s):  
Statistical Model ◽  
Cross Section ◽  
Coulomb Barrier ◽  
Nuclear Reactions ◽  
Transfer Reactions ◽  
Excitation Functions ◽  
Model Calculations ◽  
The Cross ◽  
Evaporation Residues

Excitation functions for evaporation residues in the reactions 206,208 Pb (6,4 He,2n 210 Po , as well as for the transfer reactions in the interaction of 6 He and 6 Li projectiles with Au and Pt were measured at the energies near the Coulomb barrier. Studied reactions were characterized by an increase in the cross-section compared to statistical model calculations.

Experimental study and nuclear model calculations of 3He-induced nuclear reactions on zinc

2017 ◽  
Vol 53 (5) ◽  
Author(s):  
M. Al-Abyad ◽  
Gehan Y. Mohamed ◽  
F. Ditrói ◽  
S. Takács ◽  
F. Tárkányi
Keyword(s):  
Experimental Study ◽  
Nuclear Reactions ◽  
Nuclear Model ◽  
Model Calculations

scholarly journals A systematic study of proton capture reactions in the Se-Sn region relevant to p-process nucleosynthesis

2019 ◽  
Vol 11 ◽  
Author(s):  
S. Harissopulos ◽  
P. Demetriou ◽  
S. Galanopoulos ◽  
G. Kriembardis ◽  
M. Kokkoris ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Nuclear Physics ◽  
Nuclear Reactions ◽  
Reaction Network ◽  
Reaction Rates ◽  
Compton Suppression ◽  
Experimental Information ◽  
Systematic Investigation ◽  
Model Calculations

The synthesis of the so-called ρ nuclei, i.e. a certain class of proton rich nuclei that are heavier than iron, requires a special mechanism known as ρ process. This process consists of various nucleosynthetic scenaria. In some of them proton and alpha-capture reactions are strongly involved, p-process nucleosynthesis is assumed to occur in the Oxygen/Neon rich layers of type II supernovae during their explosion, ρ nuclei are typically 10-100 times less abundant than the corresponding more neutron-rich isotopes. The prediction of their abundances is one of the major puzzles of all models of p-process nucleosynthesis. Until now all these models are capable of reproducing these abundances within a factor of 3. However, they all fail in the case of the light ρ nuclei with A<100. The observed discrepancies could be attributed to uncertainties in the pure "astrophysical" part of the p-process modelling. However, they could also be the result of uncertainties in the nuclear physics data entering the corresponding abundance calculations. In order to perform these calculations the cross sections of typically 10000 nuclear reactions of an extended reaction network involving almost 1000 nuclei from A=12 to 210 are used as input data. Such a huge amount of experimental cross section data are not available. Hence, all extended network calculations rely almost completely on cross sections predicted by the Hauser-Feshbach (HF) theory. It is therefore of paramount importance, on top of any astrophysical model improvements, to test also the reliability of the HF calculations, i.e. to investigate the uncertainties associated with the evaluation of the nuclear properties, like nuclear level densities and nucleon-nucleus potentials, entering the calculations. Until now, this check has been hindered significantly by the fact that in the Se-Sn region there has been scarce experimental information on cross sections at astrophysically relevant energies. In the present work, a systematic investigation of (p,7) cross sections of nuclei from Se to Sb is presented for the first time. The in-beam cross section measurements reported were carried out at energies relevant to p-process nucleosynthesis, i.e. from 1.4 to 5 MeV. The experiments were performed by using either an array of 4 HPGe detectors of 100% relative efficiency shielded with BGO crustals for Compton suppression, or a 4π Nal summing detector. The resulting cross sections, astrophysical S-factors and reaction rates of more than 10 nuclear reactions are compared with the predictions of various statistical model calculations.

Sign in / Sign up

Export Citation Format

Share Document