A. Deppman

Properties of hadronic systems according to the nonextensive self-consistent thermodynamics

The nonextensive self-consistent theory describing the thermodynamics of hadronic systems at high temperatures is used to derive some thermodynamical quantities, as pressure, entropy, speed of sound and trace-anomaly. The calculations are free of fitting parameters, and the results are compared to lattice QCD calculations, showing a good agreement between theory and data up to temperatures around 175 MeV. Above this temperature the effects of a singularity in the partition function results in a divergent behaviour in respect with the lattice calculation.

The CRISP package for intermediate- and high-energy photonuclear reactions

The two-step process that characterizes the intermediate- and high-energy photonuclear reactions (between 40 MeV and 4 GeV) has been successfully described by Monte Carlo calculations. Recently, a new class of codes capable to perform those calculations according to a more realistic method has been developed, improving the possibilities for simulating the reactions in more details. In this work we present the CRISP package (standing for Rio–Sao Paulo Collaboration), which is a coupling of the multi collisional Monte Carlo (MCMC) and the Monte Carlo for evaporation–fission (MCEF) codes. The first one describes the intranuclear cascade process, while the second one is dedicated to the evaporation/fission competition step. Both codes have already shown to be useful for calculating several features of different nuclear reactions. The CRISP code, coupling these two software, represents a good tool to describe the complex characteristics of the nuclear reactions, and opens the opportunity for applications in quite different fields, such as studies of hadron physics inside the nucleus, specific nuclear reactions, spallation and/or fission processes initiated by different probes and many others.

The MCEF code for nuclear evaporation and fission calculations

We present an object oriented algorithm, written in the Java programming language, which performs a Monte Carlo calculation of the evaporation-fission process taking place inside an excited nucleus. We show that this nuclear physics problem is very suited for the object oriented programming by constructing two simple objects: one that handles all nuclear properties and another that takes care of the nuclear reaction. The MCEF code was used to calculate important results for nuclear reactions, and here we show examples of possible uses for this code.

A Monte Carlo method for nuclear evaporation and fission at intermediate energies

Abstract We describe a Monte Carlo method to calculate the characteristics of the competition between particle evaporation and nuclear fission processes taking place in the compound nucleus formed after the intranuclear cascade following the absorption of intermediate energy photons by the nucleus. In this version we include not only neutrons, but also protons and alphas as possible evaporating particles. The present method allows the easy inclusion of other evaporating particles, such as deuteron or heavier clusters. Some fissility results are discussed for the target nuclei 237 Np, 238 U and 232 Th.

Photofission of 232 Th and 238 U at intermediate energies

In this work we present an analysis of the yields of fission fragments induced by bremsstrahlung photons with endpoint energies of 50 and 3500 MeV on 232Th and 238U targets using the simulation code CRISP. A multimodal fission option was added to this code and an extension of the calculation to the properties of the fission products is presented. By dividing the fissioning nuclei according to their fissionability, an approach is introduced which accounts for the contribution of symmetric and asymmetric fission. By adopting this procedure, it was possible to calculate the main parameters for the fission fragment charge distribution such as the most probable charge for a given fission product mass chain and its corresponding width parameter. Also, it was possible to reproduce features of fragment mass distribution and evaluate the fissility of fissioning nuclei for photon-induced fission of 232Th and 238U.

In Vitro Effects of Gamma Radiation from 60Co and 137Cs on Plasmid DNA

The effects of gamma radiation from 60Co and 137Cs on DNA in aqueous solution are studied experimentally. Using an improved plasmid purification protocol and improved electrophoretic gel analysis techniques provided results with relatively small uncertainties. The results are compared with both theoretical and experimental results. In particular, the results obtained here are discussed in the light of recent discussion on supposed differences of the effects induced by gamma radiation from 60Co and 137Cs. We find that the effects of both types of gamma radiation are similar.

Many-body cascade calculation of final state interactions in _\Lambda ^{12}C nonmesonic weak decay

We study the nonmesonic weak decay (NMWD) ?N ? nN of hypernucleus induced by one nucleon N = n, p. The whole process is described by two coupled models: one for the primary NMWD of ? hyperon in the nuclear environment, and the other taking into account the final state interactions (FSI) of the two outgoing nucleons within the residual nucleus. The NMWD dynamics is represented by the one-meson-exchange potential with usual parametrization, while the independent-particle shell model is used as the nuclear structure framework. The FSI are accounted for by a time-dependent multicollisional Monte Carlo cascade scheme, implemented within the CRISP code (Collaboration Rio-S?o Paulo), which describes in a phenomenological way both the nucleon?nucleon scattering inside the nucleus and the escaping of nucleons from the nuclear surface. An evaporation phase is included to cool down the cascade residual nucleus as well. We analyze the single-nucleon kinetic energy spectra, and the two-nucleon coincidence spectra as a function of both: (i) the sum of the kinetic energies and (ii) the opening angle. The theoretical results are compared with recent data from KEK and FINUDA experiments, obtaining fairly good agreement for inclusive and exclusive kinetic energy spectra. Further theoretical improvements are required to explain angular distributions.

The utilization of crisp code in hybrid reactor studies

One of the main applications of the Hybrid Reactors (ADS - Accelerator Driven System) is the incineration of transuranics (TRU) by fast neutrons that emerge from a spallation source in a sub critical reactor waste burner [1, 2]. For this application, an accurate description and prediction of spallation reaction is necessary, including all the characteristics concerning spatial and energetic angular distributions, spallation products and neutron multiplicity. To describe the nuclear reactions at intermediate and high energies, Monte Carlo calculations have been used. The CRISP package considers the intranuclear cascade (INC) that occurs during the spallation process in a realistic time-sequence approach in which all particles inside the nucleus can participate in the cascade and the nuclear density fluctuations are naturally taken into account during the process. The occupation number of each single particle level is considered as a function of time and a more realistic Pauli blocking mechanism can be performed. None of the existing models have effectively used all those features. The evaporation of protons and alpha particles are taken into account making possible the correct prediction of fissilities of actinides and pre-actinides [3]. Another implementation is the NN single-pion production reaction. This reaction is especially relevant if one is interested in neutron or proton multiplicities, since the creation/emission of pions is directly related with the excitation energy of the residual nucleus. We will present some results obtained with the CRISP package for proton-nucleus reaction at intermediate and high energies. This package was obtained by the coupling of the MCMC [4] and MCEF [5] codes, with the introduction of some improvements, such as better Pauli blocking mechanism, which constrains the residual nucleus energetic evolution to the Pauli Principle from the ground-state to the final compound-nucleus formed at the end of the intranuclear cascade process, and introduction of the most relevant resonant excitation and the NN single pion production channel. The results of interest for ADS development are consistent with the experimental data at different proton energies. More detailed calculations are being performed for studying other features of proton-nucleus reactions and with different targets.

Proton-induced fission on 241 Am, 238 U, and 237 Np at intermediate energies

Intermediate energy data of proton-induced fission on

Fragment mass distributions in the fission of heavy nuclei by intermediate- and high-energy probes

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