GEANT4 application for the simulation of the head of a siemens primus linac

The Monte Carlo simulation of the head of a Siemens Primus Linac used at Virgen Macarena Hospital (Sevilla, Spain) has been performed using the code GEANT4 [1-2], version 9.2. In this work, the main features of the application built by our group are presented. They are mainly focused in the optimization of the performance of the simulation. The geometry, including the water phantom, has been entirely wrapped by a shielding volume which discards all the particles escaping far away through its walls. With this, a factor of four in the time spent by the simulation can be saved. An interface to read and write phase-space files in IAEA format has been also developed to save CPU time in our simulations [3-4]. Finally, some calculations of the dose absorption in the water phantom have been done and compared with the results given by EGSnrc [5] and with experimental data obtained for the calibration of the machine

Four-body continuum-discretized coupled-channels calculations: Application to 6He+64Zn at 13.6 MeV

The recently developed four-body continuum-discretized coupled-channels (CDCC) method, making use of the binning procedure [1], is applied to the reaction 6He+64Zn at 13.6 MeV (around the Coulomb barrier). Excellent agreement with available elastic data [2] is found.Dirección General de Investigación Científica y Técnica FIS 2008-04189, FPA 2006- 13807-C02-01U.S. Department of Energy DE-AC52-07NA27344U.K. STFC EP/D00362

Describing resonances in a discrete basis

The problem of describing resonances when the continuum is represented by a discrete set of normalizable states is addressed. In particular, here the description of resonances in a transformed harmonic oscillator basis is presented. A method to disentangle the resonances from the nonresonant continuum is proposed. The Ginocchio potential is used to model a case in which resonances appear in the continuum and a reference case in which only nonresonant continuum appears.Ministerio de Ciencia y Tecnología FPA2002-04181-C04-04 BFM2002-0331

Comment on “Pairing interaction and Galilei invariance”

A recent article by Dussel, Sofia, and Tonina studies the relation between Galilei invariance and dipole energy weighted sum rule (EWSR). The authors find that the pairing interaction, which is neither Galilei nor Lorentz invariant, produces big changes in the EWSR and in effective masses of the nucleons. They argue that these effects of the pairing force could be realistic. In this Comment we stress the validity of Galilei invariance to a very good approximation in this context of low-energy nuclear physics and show that the effective masses and the observed change in the EWSR for the electric dipole operator relative to its classical value are compatible with this symmetry.Dirección General de Investigación Científica y Técnica PB95-0533European Commission CI1*-CT94-007

Experiencias de uso y evaluación de una herramienta de apoyo a la enseñanza de Teoría de Autómatas y Lenguajes Formales

Una materia habitual en los planes de estudios de Ingeniería Informática es la Teoría de Autómatas y Lenguajes Formales. Los alumnos suelen tener problemas a la hora de afrontar la preparación de esta materia, ya que la encuentran muy abstracta y apartada de otras materias que estudian en paralelo. Para facilitar la preparación de esta materia, se desarrolló la herramienta SELFA-Pro, que permite resolver ejercicios de la mayor parte del temario de la materia. En este artículo se presenta la experiencia reciente de uso de la herramienta en un entorno real, tanto en cuanto a estadísticas y su relación con los resultados académicos, como en cuanto a opinión subjetiva de los alumnos.A subject that is usually found in the studies of Computer Science is the Theory of Automata and Formal Languages. Students usually have some problems when facing this subject, as they find it very abstract and distant from other subjects they study at the same time. In order to make easier the preparation of the subject, the SELFA-Pro tool was developed. This tool allows students solving problems of most themes in the subject. In this paper we show some recent experiences of use of this tool in real studies. We include both statistics of use with their possible relationship with academic results and subjective opinion of the students that work with the tool

Reactions induced by 9Be in a four-body continuum-discretized coupled-channels framework

We investigate the elastic scattering of 9Be on 208Pb at beam energies above (50MeV) and below (40MeV) the Coulomb barrier. The reaction is described within a four-body framework using the Continuum-Discretized Coupled-Channels (CDCC) method. The 9Be projectile states are generated using the analytical Transformed Harmonic Oscillator (THO) basis in hyperspherical coordinates. Our calculations confirm the importance of continuum effects at low energies.Ministerio de Economía y Competitividad FIS2014-53448-c2-1-P FIS2014-51941-PJunta de Andalucía FQM-160 P11-FQM-763

Three-body nuclei and their astrophysical implications: The case of 6He

The analytic THO method [1] is generalized to study three-body nuclei of astrophysical interest, and applied to 6He. Results are consistent with previous publications and experimental data [2, 3].Economía y Competitividad FPA2009-07653 FIS2011-28738-c02-01Junta de Andalucía FQM-7632Consolider-Ingenio 2010 Programme CPAN CSD2007-0004

Entropies and IPR as Markers for a Phase Transition in a Two-Level Model for Atom–Diatomic Molecule Coexistence

This work is part of the I+D+i projects PID2019-104002GB-C22 and PID2020-114687GB-I00 funded by MCIN/AEI/10.13039/501100011033. This work is also part of grant Group FQM-160, EU FEDER funds US-1380840 and the project PAIDI 2020 with reference P20_01247, funded by the Consejería de Economía, Conocimiento, Empresas y Universidad, Junta de Andalucía (Spain) and “ERDF—A Way of Making Europe”.A quantum phase transition (QPT) in a simple model that describes the coexistence of atoms and diatomic molecules is studied. The model, which is briefly discussed, presents a second-order ground state phase transition in the thermodynamic (or large particle number) limit, changing from a molecular condensate in one phase to an equilibrium of diatomic molecules–atoms in coexistence in the other one. The usual markers for this phase transition are the ground state energy and the expected value of the number of atoms (alternatively, the number of molecules) in the ground state. In this work, other markers for the QPT, such as the inverse participation ratio (IPR), and particularly, the Rényi entropy, are analyzed and proposed as QPT markers. Both magnitudes present abrupt changes at the critical point of the QPT.Consejería de Economía, Conocimiento, Empresas y Universidad, Junta de AndalucíaSecretaría de Estado de Investigacion, Desarrollo e Innovacion FQM-160, MCIN/AEI/10.13039/501100011033, PID2019-104002GB-C22, PID2020-114687GB-I00European Regional Development Fund US-138084

Temas relacionados en el cine y la literatura

Aunque la física del caos en la predicción meteorológica no es abordada como tal, en toda su magnitud, en el cine o en la literatura, los fenómenos meteorológicos han puesto contexto a numerosas obras y, en menor medida, la física del caos aparece en unas cuantas. Con no poco esfuerzo, hemos intentado encontrar un cierto número de referencias en estas formas de arte donde se abordan temas afines a la meteorología o a la teoría del caos y que pueden conectar con algunos aspectos mostrados en este libro. Presentamos así una primerísima y muy sencilla aproximación a unas pocas películas y novelas que tocan, a mayor o menor distancia, temas relacionados con el caos y la meteorología o la climatología y el cambio climático. Ofrecemos una sinopsis de estas obras seleccionadas, así como nuestra modestísima impresión desde el punto de vista técnico-científico

Entropies and IPR as Markers for a Phase Transition in a Two-Level Model for Atom–Diatomic Molecule Coexistence

A quantum phase transition (QPT) in a simple model that describes the coexistence of atoms and diatomic molecules is studied. The model, which is briefly discussed, presents a second-order ground state phase transition in the thermodynamic (or large particle number) limit, changing from a molecular condensate in one phase to an equilibrium of diatomic molecules–atoms in coexistence in the other one. The usual markers for this phase transition are the ground state energy and the expected value of the number of atoms (alternatively, the number of molecules) in the ground state. In this work, other markers for the QPT, such as the inverse participation ratio (IPR), and particularly, the Rényi entropy, are analyzed and proposed as QPT markers. Both magnitudes present abrupt changes at the critical point of the QPT.Ministerio de Ciencia e Innovación PID2019-104002GB-C22, PID2020-114687GB-I00, 10.13039/501100011033Junta de Andalucía US-1380840, P20_0124