A5075085054- Nuclear physics research studies
- Nuclear reactor physics and engineering
- Astronomical and nuclear sciences
- High-Energy Particle Collisions Research
- Nuclear Physics and Applications
- Atomic and Molecular Physics
- Evolution and Genetic Dynamics
- Statistical Mechanics and Entropy
- Evolutionary Game Theory and Cooperation
- Complex Network Analysis Techniques
- Advanced Chemical Physics Studies
- Complex Systems and Time Series Analysis
- Nuclear Materials and Properties
- Chemical Thermodynamics and Molecular Structure
- High-pressure geophysics and materials
- Ion-surface interactions and analysis
- Opinion Dynamics and Social Influence
- Theoretical and Computational Physics
- High-Velocity Impact and Material Behavior
- X-ray Diffraction in Crystallography
- Gene Regulatory Network Analysis
- X-ray Spectroscopy and Fluorescence Analysis
- Quantum Chromodynamics and Particle Interactions
- Economic theories and models
- Market Dynamics and Volatility
Universidade Federal do Rio de Janeiro
2015-2024
Universidade Federal de Minas Gerais
2018-2024
Universidade Federal Fluminense
2023-2024
Centro de Tecnologia Mineral
2023
Centro Universitário de Volta Redonda
2023
Central Bank of Brazil
2006-2023
Universidade Federal da Bahia
2017-2018
Universidade Federal do Rio Grande do Sul
2007-2016
Universidade Federal do Rio Grande
2014
Universidade de Brasília
2000
Different statistical multifragmentation models have been used to study isoscaling, i.e., the factorization of isotope ratios from two reactions, into fugacity terms proton and neutron number, ${R}_{21}{(N,Z)=Y}_{2}{(N,Z)/Y}_{1}(N,Z)=C\mathrm{exp}(\ensuremath{\alpha}N+\ensuremath{\beta}Z).$ Even though primary distributions are quite different final due evaporation excited fragments, values $\ensuremath{\alpha}$ $\ensuremath{\beta}$ not much affected by sequential decays. is shown be mainly...
The relationship between observed intermediate mass fragment and total charged particle multiplicities has been measured for Kr84 + Au197 collisions at energies E/A=35 400 MeV. Fragment are greatest central or near-central collisions. For these collisions, production increases up to E/A≊100 MeV, then decreases higher energies.Received 14 January 1994DOI:https://doi.org/10.1103/PhysRevC.49.R2271©1994 American Physical Society
Charge and transverse energy distributions for intermediate mass fragments have been extracted central 84Kr+197Au collisions at E/A=35−400 MeV. The slopes of the measured fragment charge decrease monotonically with incident energy, consistent expectations highly charged systems, but not recent critical exponent analyses. Statistical model calculations, which reproduce experimental trends, suggest that post-breakup secondary decays alter significantly observed distributions. Radial expansion...
Calculations predict a connection between the isotopic composition of particles emitted during an energetic nucleus-nucleus collision and density dependence asymmetry term nuclear equation state (EOS). This is investigated for central ${}^{112}{\mathrm{S}\mathrm{n}+}^{112}\mathrm{Sn}$ ${}^{124}{\mathrm{S}\mathrm{n}+}^{124}\mathrm{Sn}$ collisions at $E/A=50\mathrm{MeV}$ in limit equilibrated freeze-out condition. Comparisons measured yield ratios theoretical predictions equilibrium are used...
We develop an improved Statistical Multifragmentation Model that provides the capability to calculate calorimetric and isotopic observables with precision. With this new model we examine influence of nuclear isospin on fragment elemental distributions. show proposed improvements are essential for studying effects in multifragmentation. In particular, these calculations accurate comparisons experimental data require masses, free energies secondary decay must be handled higher precision than...
Using different parametrizations of the nuclear mass formula, we study sensitivity isoscaling parameters to formula employed in grand-canonical calculations. Previous works on have suggested that symmetry energy implied such calculations is anomalously smaller than by fits masses. We show surface corrections naturally broadens isotopic distribution thus allowing for values which more closely match those obtained from
Sidewards directed fragment flow has been extracted for ${}^{84}\mathrm{Kr}{+}^{197}\mathrm{Au}$ collisions at $E/A\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}200\mathrm{MeV}$, using techniques that are free of reaction plane dispersion. The per nucleon increases with mass, following a thermal or coalescencelike behavior, and attains roughly constant limiting values $4\ensuremath{\le}A\ensuremath{\le}12$. Comparisons the impact parameter dependences measured coalescence-invariant...
Recent data on multifragmentation in central Au+Au collisions at beam energy 100 MeV/nucleon are analyzed within the statistical and molecular dynamics models. The consistent with breakup of a thermalized source radius 14 fm, mass number around 250, excitation about 7 meV/nucleon, good agreement calculations. According to this model, fragment formation takes place time interval 50 fm/c after maximum compression. Intense preequilibrium emission light particles strong collective flow fragments...
Neutrinos emitted during the collapse, bounce, and subsequent explosion provide information about supernova dynamics. The neutrino spectra are determined by weak interactions with nuclei nucleons in inner regions of star, thus composition matter. stellar matter at temperature ranging from T = 1–3 MeV densities 10−5 to 0.1 times saturation density is explored. We examine single-nucleus approximation commonly used describing dense simulations show that while accurate for predicting energy...
In evolutionary dynamics, the probability that a mutation spreads through whole population, having arisen from single individual, is known as fixation probability. general, it not possible to find analytically given mutant's fitness and topological constraints govern spread of mutation, so one resorts simulations instead. Depending on topology in use, great number steps may be needed each simulation events, particularly those end with population containing mutants only. We introduce two...
We discuss the accuracy of mass models for extrapolating to very asymmetric nuclei and impact such extrapolations on predictions isotopic observables in multifragmentation. obtain improved by incorporating measured masses unmeasured with a formula that includes surface symmetry Coulomb terms. find using accurate has significant predicted observables.
The properties of isobaric ratios, between nuclei produced in the same reaction, are investigated using canonical and grand-canonical statistical ensembles. Although formulas furnish a means to correlate ratios with liquid drop parameters, finite size effects make it difficult obtain their actual values from fitting nuclear collision data.
We use an improved version of a semiclassical coupled-channels method previously developed by some us to evaluate fusion cross sections in collisions weakly bound nuclei. This takes into account the static effects low breakup threshold, uses better bin states discretization continuum, and avoids excitation closed channels. The population these channels is consequence violation energy conservation, which inherent method. employed complete total section $^{6,7}\mathrm{Li}$ projectiles with...
The properties of the nuclear isoscaling at finite temperature are investigated and extent to which its parameter $\ensuremath{\alpha}$ holds information on symmetry energy is examined. We show that, although effects invalidate analytical formulas that relate those mass formula, remains main ingredient dictates behavior temperatures, even for very different sources. This conclusion not obvious as it true in vanishing limit, where available. Our results also reveal statistical ensembles lead...
Odd-even staggering (OES) appears in many areas of nuclear physics and is generally associated with the pairing term binding energy. To explore this effect, we use improved statistical multifragmentation model to populate an ensemble hot primary fragments, which are then de-excited using Weisskopf-Ewing emission formalism. The yields compared experimental data. Our results show that, before secondary decay, OES only even mass fragments not odd fragments. De-excitation must be taken into...
We discuss different aspects which might influence temperatures deduced from experimental isotopic yields in the multifragmentation process. It is shown that fluctuations due to finite size of system and distortions decay hot primary fragments conspire blur temperature determination reactions. These facts suggest caloric curves obtained through isotope thermometers, were taken as evidence for a first-order phase transition nuclear matter, should be investigated very carefully.
We show that the qualitative behavior of nuclear caloric curve can be inferred from energy dependence isoscaling parameters. Since there are strong indications latter not distorted by secondary decay primary hot fragments, in contrast to other observables, this suggests valuable information on may obtained through analysis presented work.
The sensitivity of the statistical multifragmentation model to underlying assumptions is investigated. We concentrate on its microcanonical, canonical, and isobaric formulations. As far as average values are concerned, our results reveal that all ensembles make very similar predictions, long relevant macroscopic variables (such temperature, excitation energy, breakup volume) same in ensembles. It also turns out multiplicity dependence volume microcanonical version mimics a system at...
The statistical multifragmentation model is modified to incorporate the Helmholtz free energies calculated in finite temperature Thomas-Fermi approximation using Skyrme effective interactions. In this formulation, density of fragments at freeze-out configuration corresponds equilibrium value obtained given temperature. behavior nuclear caloric curve constant volume investigated micro-canonical ensemble, and a plateau observed for excitation between 8 10 MeV per nucleon. A kink found onset...
The density dependence of the nuclear symmetry energy is inspected using Statistical Multifragmentation Model with Skyrme effective interactions. model consistently considers expansion fragments' volumes at finite temperature freeze-out stage. By selecting parameterizations force that lead to very different equations state for energy, we investigate sensitivity observables properties forces. Our results suggest that, in spite being sensitive thermal dilation volumes, it difficult distinguish...
We propose an opinion model based on agents located at the vertices of a regular lattice. Each agent has independent (among arbitrary, but fixed, number choices) and its own degree conviction. The latter changes every time it interacts with another who different opinion. dynamics leads to size distributions clusters (made up which have same are contiguous spatial positions) follow power law, as long range interaction between is not too short, i.e. system self-organizes into critical state....