Papers by Luis E Grave de Peralta
Book, May 6, 2024
We are surrounded by living beings made of matter. However, no living beings made of antimatter h... more We are surrounded by living beings made of matter. However, no living beings made of antimatter have ever been observed. This looks like a huge wrong prediction of our best theories about the physical fundaments of our world. In this work, the author advances a possible explanation of this mystery. This work discusses how we could explain the everyday experience of the absence of biological antimatter in our world by maintaining the validity of relativistic quantum mechanics, but adopting the idea that an electron like a positron could interact electrically with itself. For simplicity, the discussion is based on the solution of the Grave de Peralta equation for the infinity well. This is the simplest model for a spatially localized relativistic quantum particle with mass. A semiquantitative discussion of the consequences of adding the interaction of the quantum particle with itself is presented. The matter-antimatter symmetry is broken by postulating that a particle electrically interacts with itself in a different way that the corresponding antiparticle interacts with itself.
arXiv (Cornell University), Sep 29, 2011
Purpose: For more than a decade that plastic optical fiber based dosimeters have been developed f... more Purpose: For more than a decade that plastic optical fiber based dosimeters have been developed for medical applications. The feasibility of dosimeters using optical fibers that are almost Cherenkov light free has been demonstrated in some prototypes, particularly suitable for photon high-energy beams. In the energy range up to a few hundred keV, where the production of Cherenkov light by secondary electrons is negligible or small, the largest source of background are the fluorescence mechanisms. In recent years our group has developed an optical fiber dosimeter with photodiode readout named DosFib, which has small energy dependence in the range below 100 keV relevant for radiology. Photodiodes are robust photodetectors, presenting good stability over time and enough sensitivity to allow the use of an electrometer as a measuring device without extra electronics. In-vitro tests using a High Dose Rate 192 Ir source have demonstrated its suitability for brachytherapy applications using this important radioactive source. Attenuation curves have been obtained in water with the DosFib dosimeter and an ionization chamber and the depth dose profiles shown to be identical. This new dosimeter can thus be calibrated and used in clinical measurements with good competitive advantages over other dosimeters.
IEEE Nuclear Science Symposium Conference Record, 2008
Plastics are a great material to be used as a dosimeter. Their radio-properties are similar to wa... more Plastics are a great material to be used as a dosimeter. Their radio-properties are similar to water, so correction factors to convert the measured dose into dose in water are small. Traditionally the light from plastic dosimeters has been measured using PMT’s. An effective alternative is provided by photodiodes, which have broader wavelength sensitivity, allowing for the use of lower wavelength photons.
IEEE Nuclear Science Symposium Conference Record, 2012
Dosimeters made of scintillating optical fibers have interesting properties and due to its small ... more Dosimeters made of scintillating optical fibers have interesting properties and due to its small dimensions can found a field of application in brachytherapy. In this work we exploit the properties of such a dosimeter when irradiated with a clinical 192Ir radioactive source. Furthermore, we compare its response to the responses of an ionization chamber and a MOSFET dosimeter irradiated under
Research Features, 2024
This research aims to show how the complexity of the Dirac and Klein-Gordon equations may not be ... more This research aims to show how the complexity of the Dirac and Klein-Gordon equations may not be necessary to encapsulate the defining principles of relativistic quantum mechanics. In the recently published book, Relativistic and Non-Relativistic Quantum Mechanics: Both at Once," we show that it is possible and convenient to use the Poveda-Poirier-Grave de Peralta equations for simultaneously teaching relativistic and non-relativistic quantum mechanics to undergraduate students.
Optics Express, 2014
We present a simple method for obtaining direct non-scanning images in the far-field with subwave... more We present a simple method for obtaining direct non-scanning images in the far-field with subwavelength resolution. Our approach relies on the use of a digital optical condenser comprised of an array of light emitting diodes uniformly distributed inside of a hollow hemisphere. We demonstrate experimental observation of minimum feature sizes of the order of λ/6 with the proposed technique. Although our experiments were performed at visible frequencies, we anticipate that the proposed approach to subwavelength resolution can be extended to the ultraviolet and infrared spectral regions.
Biomedical Optics Express, 2015
We present a computer-controlled hemispherical digital condenser and demonstrate that a single de... more We present a computer-controlled hemispherical digital condenser and demonstrate that a single device can be used to implement a variety of both well established and novel optical microscopy techniques. We verified the condenser capabilities by imaging fabricated periodic patterned structures and biological samples.
Fourier ptychographic microscopy is demonstrated in the near-infrared spectral range using a comp... more Fourier ptychographic microscopy is demonstrated in the near-infrared spectral range using a computer-controlled hemispherical digital condenser comprising multiple 940 nm wavelength light emitting diodes. This technique was used to image periodic patterned samples (photonic crystals). Experimental and simulated results using a phase retrieval algorithm were found to be in excellent correspondence. We show that for samples with a single period in each direction, the resolution of the obtained high-resolution near-infrared images is limited by the Rayleigh criteria.
Journal of Modern Physics, 2022
Using the Hamilton-Jacobi and the Lagrange formalisms, a pair of relativistic quantum mechanics e... more Using the Hamilton-Jacobi and the Lagrange formalisms, a pair of relativistic quantum mechanics equations are obtained by abduction. These equations, in contrast with the Klein-Gordon and other relativistic quantum mechanics equations, have no solutions with both positive and negative kinetic energies. The equation with solutions with only positive kinetic energy values describes a spin-0 particle of mass m, which is moving at relativistic speeds in a scalar potential. The wavefunctions and the energies corresponding to the associated antiparticle can be obtained by solving the other equation, which only has solutions with negative kinetic energy values.
Journal of Modern Physics
Disclaimer of liability Statements and opinions expressed in the articles and communications are ... more Disclaimer of liability Statements and opinions expressed in the articles and communications are those of the individual contributors and not the statements and opinion of Scientific Research Publishing, Inc. We assume no responsibility or liability for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained herein. We expressly disclaim any implied warranties of merchantability or fitness for a particular purpose. If expert assistance is required, the services of a competent professional person should be sought.
Foundations of Physics, 2022
A recently proposed approach to relativistic quantum mechanics (Grave de Peralta, Poveda, Poirier... more A recently proposed approach to relativistic quantum mechanics (Grave de Peralta, Poveda, Poirier in Eur J Phys 42:055404, 2021) is applied to the problem of a particle in a quadratic potential. The methods, both exact and approximate, allow one to obtain eigenstate energy levels and wavefunctions, using conventional numerical eigensolvers applied to Schrödinger-like equations. Results are obtained over a nine-order-of-magnitude variation of system parameters, ranging from the non-relativistic to the ultrarelativistic limits. Various trends are analyzed and discussed—some of which might have been easily predicted, others which may be a bit more surprising.
European Journal of Physics, 2021
The fundamentals of a quasi-relativistic wave equation, whose solutions match the Schrödinger res... more The fundamentals of a quasi-relativistic wave equation, whose solutions match the Schrödinger results for slow-moving particles but are also valid when the particle moves at relativistic speeds, are discussed. This quasi-relativistic wave equation is then used for examining some interesting quantum problems where the introduction of relativistic considerations may produce remarkable consequences. We argue in favor of the academic use of this equation, for introducing students to the implications of the special theory of relativity in introductory quantum mechanics courses.
Journal of Modern Physics, 2021
Using a Schrödinger-like equation, which describes a particle with mass and spin-0 and with the c... more Using a Schrödinger-like equation, which describes a particle with mass and spin-0 and with the correct relativistic relation between its linear momentum and kinetic energy, the basic equations of the non-relativistic quantum mechanics with trajectories and quantum hydrodynamics are extended to the relativistic domain. Some simple but instructive free particle examples are discussed.
SSRN Electronic Journal, 2021
It is shown how to build a simple but exact theory of a relativistic Fermi gas at 0 ˚K, which is ... more It is shown how to build a simple but exact theory of a relativistic Fermi gas at 0 ˚K, which is based in a recently reported analytic formula for the energies of a relativistic spin-0 particle in a box. A white dwarf star is then simulated as a sphere filled with a relativistic Fermi gas. The Chandrasekhar mass limit is simply obtained using this model. We then discuss, using the proposed approach to relativistic quantum mechanics, how the interplay between the special theory of relativity, quantum mechanics, and gravity determines the stability of the matter.
European Journal of Physics, 2020
Wave mechanics triumphed when Schrödinger published his now famous equation and showed how to des... more Wave mechanics triumphed when Schrödinger published his now famous equation and showed how to describe hydrogen-like atoms using it. However, while looking for the right equation, Schrödinger first explored, but did not publish, the equation that we today call the Klein–Gordon equation. An alternative possible choice is explored in this work. It is shown a quasi-relativistic wave equation which solutions match the Schrödinger’s results at electron energies much smaller than the energy associated to the electron’s mass, but include, at higher energies, the relativity energy’s correction calculated in traditional first order perturbation theory. A discussion is presented about several consequences that would follow from using this quasi-relativistic wave equation as a quantum mechanics foundational equation. It is also suggested the academic use of this equation for introducing the students to the implications of the special theory of relativity in introductory quantum mechanics courses.
Scientific Reports, 2020
Exact solutions of a novel quasi-relativistic quantum mechanical wave equation are found for Hydr... more Exact solutions of a novel quasi-relativistic quantum mechanical wave equation are found for Hydrogen-like atoms. This includes both, an exact analytical expression for the energies of the bound states, and exact analytical expressions for the wavefunctions, which successfully describe quantum particles with mass and spin-0 up to energies comparable to the energy associated to the mass of the particle. These quasi-relativistic atomic orbitals may be used for improving ab-initio software packages dedicated to numerical simulations in physical-chemistry and atomic and solid-state physics.
Journal of Modern Physics, 2020
Using a novel wave equation, which is Galileo invariant but can give precise results up to energi... more Using a novel wave equation, which is Galileo invariant but can give precise results up to energies as high as mc 2 , exact quasi-relativistic quantum mechanical solutions are found for the Hydrogen atom. It is shown that the exact solutions of the Grave de Peralta equation include the relativistic correction to the non-relativistic kinetic energies calculated using the Schrödinger equation.
Journal of Modern Physics, 2020
A Schrödinger-like equation for a single free quantum particle is presented. It is argued that th... more A Schrödinger-like equation for a single free quantum particle is presented. It is argued that this equation can be considered a natural relativistic extension of the Schrödinger equation for energies smaller than the energy associated to the particle's mass. Some basic properties of this equation: Galilean invariance, probability density, and relation to the Klein-Gordon equation are discussed. The scholastic value of the proposed Grave de Peralta equation is illustrated by finding precise quasi-relativistic solutions for the infinite rectangular well and the quantum rotor problems. Consequences of the non-linearity of the proposed equation for the quantum superposition principle are discussed.
ABSTRACT Simulation of semiconductor diode laser performance involves interaction between multipl... more ABSTRACT Simulation of semiconductor diode laser performance involves interaction between multiple physics domains. This report presents the governing equations and finite-element (FE) implementation of such a simulation, including coupled calculation of electronic band structure, determined by solving Schrodinger's equation; carrier distribution and potential in the active region, solved using a drift-diffusion model; electrostatic potential in the ohmic regions, governed by Laplace's equation; temperature distribution, governed by Fourier's law and the heat equation; and light propagation, described by Maxwell's equations. Preliminary simulation results are provided for stripe lasers based on the GaAs/AlGaAs material system, including asymmetrically waveguided devices. Important implementation issues are discussed, particularly computation across multiple length scales and formulation of appropriate boundary conditions. Simulation results are compared to previous calculations reported in the literature. Advancement of the technical component is paralleled by development of a graphical user interface for ease of use by non-experts in FE methods.
Journal of Lightwave Technology, 2008
We demonstrate a universal reconfigurable add-drop optical filter based on arrays of digital micr... more We demonstrate a universal reconfigurable add-drop optical filter based on arrays of digital micromirrors. Our approach allows for reconfiguration of the device parameters for operation in different sets of channel wavelengths, even or uneven channel-to-channel separation, adjustable channel passband, and dynamic add-drop of optical signals. The proposed device shows insertion loss at the center wavelength in the all-pass configuration of 7.6 dB, extinction ratio of 35 dB, channel isolation better than 24 dB, negligible loss ripple, and possibility of reconfiguration time in the order of microseconds. Although designed for demonstration on optical telecommunication frequencies, the high-flexibility features of the proposed add-drop filter allow it to be used for other optical wavelength-based filtering/switching applications.
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Papers by Luis E Grave de Peralta