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http://hdl.handle.net/2117/3983
Mon, 30 Mar 2015 07:14:46 GMT2015-03-30T07:14:46Zwebmaster.bupc@upc.eduUniversitat Politècnica de Catalunya. Servei de Biblioteques i DocumentaciónoDiffraction control of reflected beam by chirped mirror
http://hdl.handle.net/2117/22805
Title: Diffraction control of reflected beam by chirped mirror
Authors: Cheng, Yu Chieh; Peckus, Martynas; Kicas, S.; Trull Silvestre, José Francisco; Cojocaru, Crina; Vilaseca Alavedra, Ramon; Drazdys, R.; Staliunas, Kestutis
Abstract: We propose and demonstrate a novel functionality of chirped mirror for monochromatic light beams: a diffraction control in reflections resulting in focusing or imaging of beams. The chirped mirrors, commonly used for manipulating temporal profiles of pulses, here are applied for manipulating the spatial dispersion of a monochromatic beam. By penetrating into dielectric layers of chirped mirror, the monochromatic beam experiences the negative diffraction, therefore the beam diverge propagating in front and behind the structure in normal diffraction region can be compensated inside this structure with negative diffraction. The result is focusing or imaging of the reflected beam from a flat interface of chirped mirror without optical axis.http://hdl.handle.net/2117/22805Cheng, Yu Chieh; Peckus, Martynas; Kicas, S.; Trull Silvestre, José Francisco; Cojocaru, Crina; Vilaseca Alavedra, Ramon; Drazdys, R.; Staliunas, Kestutisnochirped mirror, diffraction, focusing, imaging, photonic crystalsWe propose and demonstrate a novel functionality of chirped mirror for monochromatic light beams: a diffraction control in reflections resulting in focusing or imaging of beams. The chirped mirrors, commonly used for manipulating temporal profiles of pulses, here are applied for manipulating the spatial dispersion of a monochromatic beam. By penetrating into dielectric layers of chirped mirror, the monochromatic beam experiences the negative diffraction, therefore the beam diverge propagating in front and behind the structure in normal diffraction region can be compensated inside this structure with negative diffraction. The result is focusing or imaging of the reflected beam from a flat interface of chirped mirror without optical axis.Structural and dynamical properties of Mg65Cu25Y10 metallic glasses studied by in situ high energy X-ray diffraction and time resolved xray photon correlation spectroscopy
http://hdl.handle.net/2117/27080
Title: Structural and dynamical properties of Mg65Cu25Y10 metallic glasses studied by in situ high energy X-ray diffraction and time resolved xray photon correlation spectroscopy
Authors: Ruta, Beatrice; Giordano, Valentina; Erra, Loredana; Liu, Chaoren; Pineda Soler, Eloi
Abstract: We present a temperature investigation of the structural and dynamical evolution of rapidly quenched metallic glasses of Mg65Cu25Y10 at the atomic length scale by means of in situ high energy x-ray diffraction and time resolved x-ray photon correlation spectroscopy. We find a flattening of the temperature evolution of the position of the first sharp diffraction peak on approaching the glass transition temperature from the glassy state, which reflects into a surprising slowing down of the relaxation ynamics
of even one order of magnitude with increasing temperature. The comparison between structural and dynamical properties strengthens the idea of a stress-induced, rather than pure diffusive, atomic motion in metallic glassesThu, 26 Mar 2015 17:14:00 GMThttp://hdl.handle.net/2117/270802015-03-26T17:14:00ZRuta, Beatrice; Giordano, Valentina; Erra, Loredana; Liu, Chaoren; Pineda Soler, EloinoWe present a temperature investigation of the structural and dynamical evolution of rapidly quenched metallic glasses of Mg65Cu25Y10 at the atomic length scale by means of in situ high energy x-ray diffraction and time resolved x-ray photon correlation spectroscopy. We find a flattening of the temperature evolution of the position of the first sharp diffraction peak on approaching the glass transition temperature from the glassy state, which reflects into a surprising slowing down of the relaxation ynamics
of even one order of magnitude with increasing temperature. The comparison between structural and dynamical properties strengthens the idea of a stress-induced, rather than pure diffusive, atomic motion in metallic glassesAvailability simulation software adaptation to the IFMIF accelerator facility RAMI analyses
http://hdl.handle.net/2117/27060
Title: Availability simulation software adaptation to the IFMIF accelerator facility RAMI analyses
Authors: Bargalló Font, Enric; Sureda, Pere Joan; Arroyo Macias, José Manuel; Abal López, Javier; Blas Del Hoyo, Alfredo de; Dies Llovera, Javier; Tapia Fernández, Carlos; Mollá Lorente, Joaquin; Ibarra Sanchez, Angel
Abstract: Several problems were found when using generic reliability tools to perform RAM! (Reliability Availability Maintainability Inspectability) studies for the IFMIF (International Fusion Materials Irradiation Facility) accelerator. A dedicated simulation tool was necessary to model properly the complexity of the accelerator facility.; AvailSim, the availability simulation software used for the International Linear Collider (ILC) became an excellent option to fulfill RAMI analyses needs. Nevertheless, this software needed to be adapted and modified to simulate the IFMIF accelerator facility in a useful way for the RAMI analyses in the current design phase. Furthermore, some improvements and new features have been added to the software. This software has become a great tool to simulate the peculiarities of the IFMIF accelerator facility allowing obtaining a realistic availability simulation. Degraded operation simulation and maintenance strategies are the main relevant features.; In this paper, the necessity of this software, main modifications to improve it and its adaptation to IFMIF RAMI analysis are described. Moreover, first results obtained with AvailSim 2.0 and a comparison with previous results is shown.Thu, 26 Mar 2015 13:18:25 GMThttp://hdl.handle.net/2117/270602015-03-26T13:18:25ZBargalló Font, Enric; Sureda, Pere Joan; Arroyo Macias, José Manuel; Abal López, Javier; Blas Del Hoyo, Alfredo de; Dies Llovera, Javier; Tapia Fernández, Carlos; Mollá Lorente, Joaquin; Ibarra Sanchez, AngelnoIFMIF, RAMI, Availability, Reliability, Accelerator, AvailSimSeveral problems were found when using generic reliability tools to perform RAM! (Reliability Availability Maintainability Inspectability) studies for the IFMIF (International Fusion Materials Irradiation Facility) accelerator. A dedicated simulation tool was necessary to model properly the complexity of the accelerator facility.; AvailSim, the availability simulation software used for the International Linear Collider (ILC) became an excellent option to fulfill RAMI analyses needs. Nevertheless, this software needed to be adapted and modified to simulate the IFMIF accelerator facility in a useful way for the RAMI analyses in the current design phase. Furthermore, some improvements and new features have been added to the software. This software has become a great tool to simulate the peculiarities of the IFMIF accelerator facility allowing obtaining a realistic availability simulation. Degraded operation simulation and maintenance strategies are the main relevant features.; In this paper, the necessity of this software, main modifications to improve it and its adaptation to IFMIF RAMI analysis are described. Moreover, first results obtained with AvailSim 2.0 and a comparison with previous results is shown.Sharp crossover from composite fermionization to phase separation in microscopic mixtures of ultracold bosons
http://hdl.handle.net/2117/27031
Title: Sharp crossover from composite fermionization to phase separation in microscopic mixtures of ultracold bosons
Authors: Garcia March, Miguel Angel; Julia Diaz, Bruno; Astrakharchik, Grigori; Busch, T; Boronat Medico, Jordi; Rios Polls, Artur
Abstract: We show that a two-component mixture of a few repulsively interacting ultracold atoms in a one-dimensional trap possesses very diverse quantum regimes and that the crossover between them can be induced by tuning the interactions in one of the species. Starting from the composite fermionization regime, in which the interactions between both components are large and neither gas is phase coherent, our results show that a phase-separated state can be reached by increasing the interaction in one of the species. In this regime, the weakly interacting component stays at the center of the trap and becomes almost fully phase coherent, while the strongly interacting one is expelled to the edges of the trap. The crossover is sharp, as can be witnessed in the system's energy and in the occupation of the lowest natural orbital of the weakly interacting species. We show that such a transition is a few-atom effect which disappears for a large population imbalance.Wed, 25 Mar 2015 16:00:33 GMThttp://hdl.handle.net/2117/270312015-03-25T16:00:33ZGarcia March, Miguel Angel; Julia Diaz, Bruno; Astrakharchik, Grigori; Busch, T; Boronat Medico, Jordi; Rios Polls, ArturnoInteracting species, Large population, Natural orbitals, Phase coherent, Quantum regimes, Two-component mixtures, Ultracold atoms, Ultracold bosonsWe show that a two-component mixture of a few repulsively interacting ultracold atoms in a one-dimensional trap possesses very diverse quantum regimes and that the crossover between them can be induced by tuning the interactions in one of the species. Starting from the composite fermionization regime, in which the interactions between both components are large and neither gas is phase coherent, our results show that a phase-separated state can be reached by increasing the interaction in one of the species. In this regime, the weakly interacting component stays at the center of the trap and becomes almost fully phase coherent, while the strongly interacting one is expelled to the edges of the trap. The crossover is sharp, as can be witnessed in the system's energy and in the occupation of the lowest natural orbital of the weakly interacting species. We show that such a transition is a few-atom effect which disappears for a large population imbalance.Aging and structural relaxation of hyper-quenched Mg65Cu25Y10 metallic glass
http://hdl.handle.net/2117/27011
Title: Aging and structural relaxation of hyper-quenched Mg65Cu25Y10 metallic glass
Authors: Zhai, Fuqiang; Pineda Soler, Eloi; Ruta, Beatrice; Gonzalez Silveira, Marta; Crespo Artiaga, Daniel
Abstract: The structural relaxation, glass transition and crystallization processes of Mg65Cu25Y10 metallic glass are studied by Differential Scanning Calorimetry (DSC) and Mechanical spectroscopy. The relaxation model derived from the mechanical measurements is compared with the kinetics of these transformations obtained from the DSC curves. The structural relaxation kinetics is found to be controlled by the glassy dynamics following an Adams-Gibbs-Vogel function. The glass transition and crystallization kinetics are controlled by the dynamics of the supercooled melt following a Vogel-Fulcher-Tammann behaviour. The results suggest that the microscopic processes responsible of structural relaxation and aging below the glass transition correspond to the same processes generating the a-relaxation peak. (C) 2013 Elsevier B.V. All rights reserved.Tue, 24 Mar 2015 16:47:16 GMThttp://hdl.handle.net/2117/270112015-03-24T16:47:16ZZhai, Fuqiang; Pineda Soler, Eloi; Ruta, Beatrice; Gonzalez Silveira, Marta; Crespo Artiaga, DanielnoMetallic glasses, Relaxation kinetics, Alpha relaxation, Mechanical spectroscopy, DSC, JOHARI-GOLDSTEIN RELAXATION, TEMPERATURE, KINETICSThe structural relaxation, glass transition and crystallization processes of Mg65Cu25Y10 metallic glass are studied by Differential Scanning Calorimetry (DSC) and Mechanical spectroscopy. The relaxation model derived from the mechanical measurements is compared with the kinetics of these transformations obtained from the DSC curves. The structural relaxation kinetics is found to be controlled by the glassy dynamics following an Adams-Gibbs-Vogel function. The glass transition and crystallization kinetics are controlled by the dynamics of the supercooled melt following a Vogel-Fulcher-Tammann behaviour. The results suggest that the microscopic processes responsible of structural relaxation and aging below the glass transition correspond to the same processes generating the a-relaxation peak. (C) 2013 Elsevier B.V. All rights reserved.Collective stochastic coherence and synchronizability in weighted scale-free networks
http://hdl.handle.net/2117/26958
Title: Collective stochastic coherence and synchronizability in weighted scale-free networks
Authors: Balenzuela, Pablo; Rue Queralt, Pau; Boccaletti, Stefano; García Ojalvo, Jordi
Abstract: Coupling frequently enhances noise-induced coherence and synchronization in interacting nonlinear systems, but it does so separately. In principle collective stochastic coherence and synchronizability are incompatible phenomena, since strongly synchronized elements behave identically and thus their response to noise is indistinguishable to that of a single element. Therefore one can expect systems that synchronize well to have a poor collective response to noise. Here we show that, in spite of this apparent conflict, a certain coupling architecture is able to reconcile the two properties. Specifically, our results reveal that weighted scale-free networks of diffusively coupled excitable elements exhibit both high synchronizability of their subthreshold dynamics and a good collective response to noise of their pulsed dynamics. This is established by comparing the behavior of this system to that of random, regular, and unweighted scale-free networks. We attribute the optimal response of weighted scale-free networks to a balance between degree heterogeneity, which ensures a good collective response to noise, and the coupling-strength weighting procedure, which overcomes the paradox of heterogeneity that would otherwise impair synchronization.Mon, 23 Mar 2015 16:13:49 GMThttp://hdl.handle.net/2117/269582015-03-23T16:13:49ZBalenzuela, Pablo; Rue Queralt, Pau; Boccaletti, Stefano; García Ojalvo, JordinoNOISE, HETEROGENEITY, RESONANCECoupling frequently enhances noise-induced coherence and synchronization in interacting nonlinear systems, but it does so separately. In principle collective stochastic coherence and synchronizability are incompatible phenomena, since strongly synchronized elements behave identically and thus their response to noise is indistinguishable to that of a single element. Therefore one can expect systems that synchronize well to have a poor collective response to noise. Here we show that, in spite of this apparent conflict, a certain coupling architecture is able to reconcile the two properties. Specifically, our results reveal that weighted scale-free networks of diffusively coupled excitable elements exhibit both high synchronizability of their subthreshold dynamics and a good collective response to noise of their pulsed dynamics. This is established by comparing the behavior of this system to that of random, regular, and unweighted scale-free networks. We attribute the optimal response of weighted scale-free networks to a balance between degree heterogeneity, which ensures a good collective response to noise, and the coupling-strength weighting procedure, which overcomes the paradox of heterogeneity that would otherwise impair synchronization.Gap soliton in a waveguide array with a saturating defocusing nonlinearity
http://hdl.handle.net/2117/26937
Title: Gap soliton in a waveguide array with a saturating defocusing nonlinearity
Authors: Gaizzuskas, E; Savickas, A.; Staliunas, Kestutis
Abstract: We investigate radiation of the solitary waves in the first band gap of the waveguide array with a defocusing nonlinearities of different types (Kerr nonlinearity and saturating nonlinearity). We confirm recent findings that gap solitons (GSs) are unstable for their eigenfrequencies around the middle of the band gap for Kerr nonlinearity. The instability is mediated by four-wave mixing process and appears in the form of radiation of solitons into mode continua of the upper and lower bands. We find that this soliton radiation is reduced (and even suppressed completely) in case of a saturating nonlinearity, resulting in substantial stabilization of the GSs.Mon, 23 Mar 2015 12:32:35 GMThttp://hdl.handle.net/2117/269372015-03-23T12:32:35ZGaizzuskas, E; Savickas, A.; Staliunas, KestutisnoPeriodic structures, Photonic crystal, Supercontinuum, Superlattices, Radiation, Lattices, Fibers, MediaWe investigate radiation of the solitary waves in the first band gap of the waveguide array with a defocusing nonlinearities of different types (Kerr nonlinearity and saturating nonlinearity). We confirm recent findings that gap solitons (GSs) are unstable for their eigenfrequencies around the middle of the band gap for Kerr nonlinearity. The instability is mediated by four-wave mixing process and appears in the form of radiation of solitons into mode continua of the upper and lower bands. We find that this soliton radiation is reduced (and even suppressed completely) in case of a saturating nonlinearity, resulting in substantial stabilization of the GSs.Beam focusing in reflections from flat subwavelength diffraction gratings
http://hdl.handle.net/2117/26933
Title: Beam focusing in reflections from flat subwavelength diffraction gratings
Authors: Cheng, Yu Chieh; Redondo, Javier; Staliunas, Kestutis
Abstract: We predict that narrow beams, reflecting from flat subwavelength diffraction gratings, can focus. The effect is shown for the beams of electromagnetic radiation; however, it should be observable for beams of waves of arbitrary nature (microwaves, surface plasmons, and acoustic and mechanical waves). We present analytical estimations of the focusing performance obtained by multiple scattering calculations and demonstrate the focusing effect numerically for an optical system (reflections from an array of dielectric cylinders), using the finite-difference time-domain calculations.Mon, 23 Mar 2015 12:02:55 GMThttp://hdl.handle.net/2117/269332015-03-23T12:02:55ZCheng, Yu Chieh; Redondo, Javier; Staliunas, KestutisnoAnalytical estimations, Dielectric cylinder, Finite-difference time-domain calculations, Focusing effect, Focusing performance, Multiple scattering calculations, Sub-wavelength, Surface plasmonsWe predict that narrow beams, reflecting from flat subwavelength diffraction gratings, can focus. The effect is shown for the beams of electromagnetic radiation; however, it should be observable for beams of waves of arbitrary nature (microwaves, surface plasmons, and acoustic and mechanical waves). We present analytical estimations of the focusing performance obtained by multiple scattering calculations and demonstrate the focusing effect numerically for an optical system (reflections from an array of dielectric cylinders), using the finite-difference time-domain calculations.Temporal percolation in activity-driven networks
http://hdl.handle.net/2117/26924
Title: Temporal percolation in activity-driven networks
Authors: Starnini, Michele; Pastor Satorras, Romualdo
Abstract: We study the temporal percolation properties of temporal networks by taking as a representative example the recently proposed activity-driven-network model [N. Perra et al., Sci. Rep. 2, 469 ( 2012)]. Building upon an analytical framework based on a mapping to hidden variables networks, we provide expressions for the percolation time T-p marking the onset of a giant connected component in the integrated network. In particular, we consider both the generating function formalism, valid for degree-uncorrelated networks, and the general case of networks with degree correlations. We discuss the different limits of the two approaches, indicating the parameter regions where the correlated threshold collapses onto the uncorrelated case. Our analytical predictions are confirmed by numerical simulations of the model. The temporal percolation concept can be fruitfully applied to study epidemic spreading on temporal networks. We show in particular how the susceptible-infected-removed model on an activity-driven network can be mapped to the percolation problem up to a time given by the spreading rate of the epidemic process. This mapping allows us to obtain additional information on this process, not available for previous approaches.Mon, 23 Mar 2015 09:53:58 GMThttp://hdl.handle.net/2117/269242015-03-23T09:53:58ZStarnini, Michele; Pastor Satorras, RomualdonoTime-varying networks, Random graphsWe study the temporal percolation properties of temporal networks by taking as a representative example the recently proposed activity-driven-network model [N. Perra et al., Sci. Rep. 2, 469 ( 2012)]. Building upon an analytical framework based on a mapping to hidden variables networks, we provide expressions for the percolation time T-p marking the onset of a giant connected component in the integrated network. In particular, we consider both the generating function formalism, valid for degree-uncorrelated networks, and the general case of networks with degree correlations. We discuss the different limits of the two approaches, indicating the parameter regions where the correlated threshold collapses onto the uncorrelated case. Our analytical predictions are confirmed by numerical simulations of the model. The temporal percolation concept can be fruitfully applied to study epidemic spreading on temporal networks. We show in particular how the susceptible-infected-removed model on an activity-driven network can be mapped to the percolation problem up to a time given by the spreading rate of the epidemic process. This mapping allows us to obtain additional information on this process, not available for previous approaches.Simulation of condensation in a closed, slightly inclined horizontal pipe with a modified RELAP5 code
http://hdl.handle.net/2117/26919
Title: Simulation of condensation in a closed, slightly inclined horizontal pipe with a modified RELAP5 code
Authors: Szijártó, Rita; Freixa Terradas, Jordi; Prasser, Horst-Michael
Abstract: The performance of the RELAP5 thermal-hydraulic system code was analyzed in predicting very fast transient condensation processes in horizontal pipes. The code significantly underpredicted the heat transfer from the primary to the secondary side in case of rapid wall condensation process in the so called Inverse Edwards Pipe Experiment, where the condensation pipe was immerged in a cool water pool, and hot steam injection was performed into a pipe, which was closed on one side. The RELAP5 condensation model for horizontal pipes was modified in order to take into account a stratified flow pattern, and the effect of the local void fraction. The modified RELAP5 code was compared to the original code through the calculation of the Inverse Edwards Pipe Experiment. An improved prediction of the heat transfer process was achieved, considering the temperature, pressure and void fraction distribution along the horizontal pipe during the transient condensation process. (C) 2014 Elsevier B.V. All rights reserved.Mon, 23 Mar 2015 09:14:12 GMThttp://hdl.handle.net/2117/269192015-03-23T09:14:12ZSzijártó, Rita; Freixa Terradas, Jordi; Prasser, Horst-MichaelnoHEAT-TRANSFER MODEL, CONVECTIVE CONDENSATION, STRATIFIED FLOW, EMERGENCY CONDENSER, LIQUID ENTRAINMENT, TUBES, SMOOTH, RELAP5/MOD3.2, REGIME, GASESThe performance of the RELAP5 thermal-hydraulic system code was analyzed in predicting very fast transient condensation processes in horizontal pipes. The code significantly underpredicted the heat transfer from the primary to the secondary side in case of rapid wall condensation process in the so called Inverse Edwards Pipe Experiment, where the condensation pipe was immerged in a cool water pool, and hot steam injection was performed into a pipe, which was closed on one side. The RELAP5 condensation model for horizontal pipes was modified in order to take into account a stratified flow pattern, and the effect of the local void fraction. The modified RELAP5 code was compared to the original code through the calculation of the Inverse Edwards Pipe Experiment. An improved prediction of the heat transfer process was achieved, considering the temperature, pressure and void fraction distribution along the horizontal pipe during the transient condensation process. (C) 2014 Elsevier B.V. All rights reserved.Homothetic motions and Newtonian cosmology
http://hdl.handle.net/2117/26879
Title: Homothetic motions and Newtonian cosmology
Authors: Jaen Herbera, Javier; Molina Compte, Alfred
Abstract: We construct a homothetic covariant Newtonian gravitation theory which unifies inertial homothetic forces and gravitational fields. This is achieved through an equivalence principle based on a local homothetic frame of motion. As a consequence, we can obtain a coherent Newtonian cosmology which admits a cosmological principle and leads to the Friedman equations for a dust universe. Finally we prove that this gravity theory can be obtained as the non-relativistic limit of a class of metrics in General Relativity. The Friedmann–Lemaître–Robertson–Walker metric and its limit are also studied.Fri, 20 Mar 2015 10:00:17 GMThttp://hdl.handle.net/2117/268792015-03-20T10:00:17ZJaen Herbera, Javier; Molina Compte, AlfrednoHomothetic motion, Newtonian cosmology, FLRW, Dust universeWe construct a homothetic covariant Newtonian gravitation theory which unifies inertial homothetic forces and gravitational fields. This is achieved through an equivalence principle based on a local homothetic frame of motion. As a consequence, we can obtain a coherent Newtonian cosmology which admits a cosmological principle and leads to the Friedman equations for a dust universe. Finally we prove that this gravity theory can be obtained as the non-relativistic limit of a class of metrics in General Relativity. The Friedmann–Lemaître–Robertson–Walker metric and its limit are also studied.ß-delayed neutron emission measurements around the third r-process abundance peak
http://hdl.handle.net/2117/26863
Title: ß-delayed neutron emission measurements around the third r-process abundance peak
Authors: Caballero Folch, Roger; Domingo Pardo, César; Cortés Rossell, Guillem Pere; Calviño Tavares, Francisco; Riego Pérez, Albert
Abstract: The elements heavier than iron are produced in the Universe mainly by means of the slow (s) and rapid (r) neutron capture processes (for a recent review see e.g. [1]). The latter nucleosynthesis mechanism occurs between the valley of stability and the neutron drip line, passing along the neutron shell closures where exceptionally long half-lives and small neutron capture cross sections yield the three characteristic abundance maxima at A ~ 80, 130 and 195.Thu, 19 Mar 2015 14:40:29 GMThttp://hdl.handle.net/2117/268632015-03-19T14:40:29ZCaballero Folch, Roger; Domingo Pardo, César; Cortés Rossell, Guillem Pere; Calviño Tavares, Francisco; Riego Pérez, AlbertnoThe elements heavier than iron are produced in the Universe mainly by means of the slow (s) and rapid (r) neutron capture processes (for a recent review see e.g. [1]). The latter nucleosynthesis mechanism occurs between the valley of stability and the neutron drip line, passing along the neutron shell closures where exceptionally long half-lives and small neutron capture cross sections yield the three characteristic abundance maxima at A ~ 80, 130 and 195.Measurement of the angular distribution of fission fragments using a PPAC assembly at CERN n_TOF
http://hdl.handle.net/2117/26844
Title: Measurement of the angular distribution of fission fragments using a PPAC assembly at CERN n_TOF
Authors: Tarrío, D.; Audouin, Ludmila; Altstadt, Sebastian; Andrzejewski, Józef; Barbagallo, Massimo; Calviño Tavares, Francisco; Cortés Rossell, Guillem Pere; Gómez Hornillos, María Belén; Riego Pérez, Albert
Abstract: A fission reaction chamber based on Parallel Plate Avalanche Counters (PPACs) was built for measuring angular distributions of fragments emitted in neutron-induced fission of actinides at the neutron beam available at the Neutron Time-Of-Flight (n_TOF) facility at CERN. The detectors and the samples were tilted 45° with respect to the neutron beam direction to cover all the possible values of the emission angle of the fission fragments. The main features of this setup are discussed and results on the fission fragment angular distribution are provided for the 232Th(n,f) reaction around the fission threshold. The results are compared with the available data in the literature, demonstrating the good capabilities of this setupThu, 19 Mar 2015 12:55:34 GMThttp://hdl.handle.net/2117/268442015-03-19T12:55:34ZTarrío, D.; Audouin, Ludmila; Altstadt, Sebastian; Andrzejewski, Józef; Barbagallo, Massimo; Calviño Tavares, Francisco; Cortés Rossell, Guillem Pere; Gómez Hornillos, María Belén; Riego Pérez, AlbertnoFission, Neutron, Anisotropy, Angular distribution, 232Th, Gas detectorsA fission reaction chamber based on Parallel Plate Avalanche Counters (PPACs) was built for measuring angular distributions of fragments emitted in neutron-induced fission of actinides at the neutron beam available at the Neutron Time-Of-Flight (n_TOF) facility at CERN. The detectors and the samples were tilted 45° with respect to the neutron beam direction to cover all the possible values of the emission angle of the fission fragments. The main features of this setup are discussed and results on the fission fragment angular distribution are provided for the 232Th(n,f) reaction around the fission threshold. The results are compared with the available data in the literature, demonstrating the good capabilities of this setupDel reto al proyecto una nueva experiencia docente en el marco del Espacio Europeo de Educacion Superior
http://hdl.handle.net/2117/26840
Title: Del reto al proyecto una nueva experiencia docente en el marco del Espacio Europeo de Educacion Superior
Authors: Jaen Fernandez, Carles; Hervada Sala, Carme; Lamich Arocas, Manuel; Corbalán Fuertes, Montserrat; Pou Félix, Josep; Arias Pujol, AntoniThu, 19 Mar 2015 12:35:07 GMThttp://hdl.handle.net/2117/268402015-03-19T12:35:07ZJaen Fernandez, Carles; Hervada Sala, Carme; Lamich Arocas, Manuel; Corbalán Fuertes, Montserrat; Pou Félix, Josep; Arias Pujol, AntoninoSelective advantage of diffusing faster
http://hdl.handle.net/2117/26769
Title: Selective advantage of diffusing faster
Authors: Pigolotti, Simone; Benzi, R.
Abstract: We study a stochastic spatial model of biological competition in which two species have the same birth and death rates, but different diffusion constants. In the absence of this difference, the model can be considered as an off-lattice version of the voter model and presents similar coarsening properties. We show that even a relative difference in diffusivity on the order of a few percent may lead to a strong bias in the coarsening process favoring the more agile species. We theoretically quantify this selective advantage and present analytical formulas for the average growth of the fastest species and its fixation probability.Tue, 17 Mar 2015 15:54:02 GMThttp://hdl.handle.net/2117/267692015-03-17T15:54:02ZPigolotti, Simone; Benzi, R.noEngineering controlled terms, Atomic physics, PhysicsWe study a stochastic spatial model of biological competition in which two species have the same birth and death rates, but different diffusion constants. In the absence of this difference, the model can be considered as an off-lattice version of the voter model and presents similar coarsening properties. We show that even a relative difference in diffusivity on the order of a few percent may lead to a strong bias in the coarsening process favoring the more agile species. We theoretically quantify this selective advantage and present analytical formulas for the average growth of the fastest species and its fixation probability.