Search results for "Ikona"
showing 10 items of 30 documents
Personalization of Fast Conduction Purkinje System in Eikonal-Based Electrophysiological Models with Optical Mapping Data
2010
We present a pipeline for the personalization of model-based Purkinje fast conduction system using fast electrophysiological models and optical mapping data acquired from ex-vivo porcine hearts. The regional density of the Purkinje terminals as well as the latest endocardial activation time were the parameters personalized in an iterative procedure maximizing the similarity between the outcome of the electrophysiological simulations and measurements obtained from optical mapping data. We used a fast wave-front Eikonal-based electrophysiological model that generated the depolarization time maps that were subsequently compared with measurements at each iteration of the optimization stage. The…
Subleading Regge limit from a soft anomalous dimension
2018
Wilson lines capture important features of scattering amplitudes, for example soft effects relevant for infrared divergences, and the Regge limit. Beyond the leading power approximation, corrections to the eikonal picture have to be taken into account. In this paper, we study such corrections in a model of massive scattering amplitudes in N = 4 super Yang-Mills, in the planar limit, where the mass is generated through a Higgs mechanism. Using known three-loop analytic expressions for the scattering amplitude, we find that the first power suppressed term has a very simple form, equal to a single power law. We propose that its exponent is governed by the anomalous dimension of a Wilson loop w…
No chiral light bending by clumps of axion-like particles
2019
We study the propagation of light in the presence of a parity-violating coupling between photons and axion-like particles (ALPs). Naively, this interaction could lead to a split of light rays into two separate beams of different polarization chirality and with different refraction angles. However, by using the eikonal method we explicitly show that this is not the case and that ALP clumps do not produce any spatial birefringence. This happens due to non-trivial variations of the photon's frequency and wavevector, which absorb time-derivatives and gradients of the ALP field. We argue that these variations represent a new way to probe the ALP-photon couping with precision frequency measuremen…
Reliable extraction of the dB(E1)/dE for 11Be from its breakup at 520 MeV/nucleon
2019
We analyze the breakup of the one-neutron halo nucleus 11Be measured at 520 MeV/nucleon at GSI on Pb and C targets within an eikonal description of the reaction including a proper treatment of special relativity. The Coulomb term of the projectile-target interaction is corrected at first order, while its nuclear part is described at the optical limit approximation. Good agreement with the data is obtained using a description of 11Be, which fits the breakup data of RIKEN. This solves the apparent discrepancy between the dB(E1)/dE estimations from GSI and RIKEN for this nucleus.
Introduction to Nuclear-Reaction Theory
2019
These notes summarise the lectures I gave during the summer school "International Scientific Meeting on Nuclear Physics" at La R\'abida in Spain in June 2018. They offer an introduction to nuclear-reaction theory, starting with the basics in quantum scattering theory followed by the main models used to describe breakup reactions: the Continuum Discretised Coupled Channel method (CDCC),the Time-Dependent approach (TD) and the eikonal approximation. These models are illustrated on the study of the exotic structure of halo nuclei.
Matka Boska z Koźla – ikona czy obraz?
2021
Dekalog zakazuje kultu obrazów. Jednak chrześcijanie zinterpretowali Wcielenie Boga w Jezusie Chrystusie jako zniesienie zakazu tworzenia obrazów. Cztery sobory powszechne wypowiedziały się na temat obrazów w Kościele. Pojęcie obrazu i ikony w pierwszym tysiącleciu chrześcijaństwa było takie samo. Chrześcijanie prawosławni zawęzili znaczenie ikony tylko do obrazu tworzonego na desce za pomocą określonej techniki i estetyki. Matka Boska z Koźla jest jednocześnie obrazem (w znaczeniu szerokim, zachodnim, katolickim), jak i ikoną (w znaczeniu wąskim, wschodnim, prawosławnym). Ikony posługują się językiem symboli i ich celem jest przypominanie o obecności świętej osoby, przedstawionej w obrazie…
Halo effective field theory analysis of one-neutron knockout reactions of Be11 and C15
2021
Background: One-nucleon knockout reactions provide insightful information on the single-particle structure of nuclei. When applied to one-neutron halo nuclei, they are purely peripheral, suggesting that they could be properly modeled by describing the projectile within a halo effective field theory (halo-EFT).Purpose: We reanalyze the one-neutron knockout measurements of $^{11}\mathrm{Be}$ and $^{15}\mathrm{C}$---both one-neutron halo nuclei---on beryllium at about 60 MeV/nucleon. We consider halo-EFT descriptions of these nuclei which already provide excellent agreement with breakup and transfer data.Method: We include a halo-EFT description of the projectile within an eikonal-based model …
Low-energy corrections to the eikonal description of elastic scattering and breakup of one-neutron halo nuclei in nuclear-dominated reactions
2018
Background: The eikonal approximation is a high-energy reaction model, which is very computationally efficient and provides a simple interpretation of the collision. Unfortunately, it is not valid at energies around 10 MeV/nucleon, the range of energy of HIE-ISOLDE at CERN and the future ReA12 at MSU. Fukui et al. [Phys. Rev. C 90, 034617 (2014)10.1103/PhysRevC.90.034617] have shown that a simple semiclassical correction of the projectile-target deflection could improve the description of breakup of halo nuclei on heavy targets down to 20 MeV/nucleon. Purpose: We study two similar corrections, which aim at improving the projectile-target relative motion within the eikonal approximation, wit…
Extension of the ratio method to proton-rich nuclei
2019
The ratio method has been developed to improve the study of one-neutron halo nuclei through reactions. By taking the ratio of angular distributions for two processes, viz. breakup and elastic scattering, this new observable is nearly independent of the reaction mechanism and hence much more sensitive to the projectile structure than the cross sections for each single process. We study the extension of the ratio method to proton-rich nuclei and also explore the optimum experimental conditions for measuring this new observable. We compare accurate dynamical calculations of reactions for proton-rich projectiles to the prediction of the ratio method. We use the dynamical eikonal approximation t…
New Results on Multiphoton Free-Free Transitions
1988
Recently some of the present authors have reported on calculations concerning free-free transitions in the presence of very strong laser fields,1 in which a number of peculiar features were clearly displayed (among others, well pronounced maxima in the total cross sections and an oscillatory structure). In particular, those calculations concerned total cross sections of direct and inverse multiphoton bremsstrahlung, for several numbers of exchanged photons as functions of the field intensity. Figs. 1 and 2 show a sample of the typical results reported in Ref. 1.