scholarly journals Geometric models of matter

2012 ◽  
Vol 468 (2141) ◽  
pp. 1252-1279 ◽  
Author(s):  
M. F. Atiyah ◽  
N. S. Manton ◽  
B. J. Schroers
Keyword(s):  
Electric Fields ◽  
Chern Class ◽  
Charged Particles ◽  
Baryon Number ◽  
Circle Bundle ◽  
Neutral Particles ◽  
The Core ◽  
Electrically Charged ◽  
Kaluza Klein ◽  
Bundle Structure

Inspired by soliton models, we propose a description of static particles in terms of Riemannian 4-manifolds with self-dual Weyl tensor. For electrically charged particles, the 4-manifolds are non-compact and asymptotically fibred by circles over physical 3-space. This is akin to the Kaluza–Klein description of electromagnetism, except that we exchange the roles of magnetic and electric fields, and only assume the bundle structure asymptotically, away from the core of the particle in question. We identify the Chern class of the circle bundle at infinity with minus the electric charge and, at least provisionally, the signature of the 4-manifold with the baryon number. Electrically neutral particles are described by compact 4-manifolds. We illustrate our approach by studying the Taub–Newman, Unti, Tamburino (Taub–NUT) manifold as a model for the electron, the Atiyah–Hitchin manifold as a model for the proton, with the Fubini–Study metric as a model for the neutron and S 4 with its standard metric as a model for the neutrino.

scholarly journals Ionosphere monitoring sensor, placed on nanosatellites

2021 ◽  
pp. 54-65
Author(s):  
V.E. Dreyzin ◽  
◽  
Mohammed Al Kadhimi Ali Noori ◽  
V.E. Bondyrev ◽  
◽  
...  
Keyword(s):  
Energy Consumption ◽  
Electric Fields ◽  
Ion Trap ◽  
Charged Particles ◽  
High Concentration ◽  
Existing Problems ◽  
The Core ◽  
Autonomous Operation ◽  
Electric And Magnetic Fields ◽  
Electrons And Ions

In this paper, we propose a sensor for the density and composition of the upper atmosphere (ionosphere), designed for installation on nanosatellites. The relevance and existing problems of direct instrumental studies of the ionosphere at altitudes of 150-500 km are shown. Of the existing types of vacuum meters, the most suitable for autonomous operation at these altitudes are ionization vacuum meters with inverse magnetron primary converters with a cold cathode. However, the existing industrial types of such vacuum meters are unsuitable for operation in the ionosphere due to high concentration of charged particles in the air, resulting in large distortions of the readings. In addition, they have large weight and size characteristics and energy consumption, which exclude the possibility of their installation on nanosatellites. To solve these problems, a mathematical model of the electrophysical processes, occurring in the core of such a converter, was developed which significantly reduced its weight and size characteristics and energy consumption. And to eliminate the influence of charged particles, it is equipped with an electron-ion trap, which additionally made it possible to measure the concentration of electrons and ions in the environment. The design of such a combined converter is described, and calculations of the electric and magnetic fields in the core of the vacuum gauge converter and the electric fields in the interelectrode space of the trap are performed. A method for calculating the current values of such a combined converter has been developed, which makes it possible to estimate the required measurement ranges of the sensor measuring channels. The results obtained allow us to proceed with its experimental design.

scholarly journals GAUGE INVARIANCE OF ELEMENTARY PARTICLE PROCESSES IN THE PRESENCE OF A BACKGROUND MAGNETIC FIELD

2006 ◽  
Vol 21 (15) ◽  
pp. 3151-3170
Author(s):  
KAUSHIK BHATTACHARYA
Keyword(s):  
Elementary Particle ◽  
Magnetic Field ◽  
Neutron Stars ◽  
Gauge Invariance ◽  
Charged Particles ◽  
Final State ◽  
The Core ◽  
Background Magnetic Field ◽  
Elementary Particle Processes ◽  
Electrically Charged

Elementary particle scatterings and decays in the presence of a background magnetic field are very common in physics, especially after the observation that the core of the neutron stars can sustain a magnetic field of the order of 1013 G. The important point about these calculations is that they are done in a background of a gauge field and as a result the calculations are prone to gauge arbitrariness. In this work we will investigate how this gauge arbitrariness is eradicated in processes where the initial and final particles taking part in the interactions are electrically neutral. Some comments on those processes where the initial or final state consists of electrically charged particles is presented at the end of the paper.

Principles of radiation therapy

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Janusz Winiecki
Keyword(s):  
Radiation Therapy ◽  
Ionizing Radiation ◽  
Charged Particles ◽  
Living Matter ◽  
Oncological Treatment ◽  
Neutral Particles ◽  
The World ◽  
The Difference ◽  
Electrically Charged ◽  
Physical Quantities

AbstractIntroductionRadiotherapy is one of the basic methods of cancer treatment. Tens of millions of people around the world are exposed to ionizing radiation each year in the hope that it will help fight the disease or slow down its progress. Radiotherapy owes its success mainly to important discoveries in the field of physics, which allowed to understand the essence of the interaction of ionizing radiation with matter, in particular living matter.MaterialsThe following study explains which types of radiation have the ability to ionize matter. The difference between the interaction of electrically charged particles and neutral particles was explained. The author briefly described methods of delivering radiation to diseased tissues and how adjacent tissues are protected. The most important physical quantities describing the quality and dose of the delivered radiation were introduced.ConclusionsSafe use of radiotherapy as one of the methods of oncological treatment requires proficient knowledge of the basics of radiobiology and the physics of nuclear interactions. The study describes the most important steps in the preparation and implementation of radiotherapy, but it is not sufficient to fully understand this method. However, it provides an opportunity to be familiar with the issue in general.

scholarly journals WHAT IS A MATTER PARTICLE?

2006 ◽  
Vol 15 (01) ◽  
pp. 259-272
Author(s):  
TSAN UNG CHAN
Keyword(s):  
Standard Model ◽  
Weak Interaction ◽  
Strong Interaction ◽  
Neutral Particle ◽  
Z Bosons ◽  
Baryon Number ◽  
Lepton Number ◽  
Neutral Particles ◽  
The Standard Model ◽  
The Stability

Positive baryon numbers (A>0) and positive lepton numbers (L>0) characterize matter particles while negative baryon numbers and negative lepton numbers characterize antimatter particles. Matter particles and antimatter particles belong to two distinct classes of particles. Matter neutral particles are particles characterized by both zero baryon number and zero lepton number. This third class of particles includes mesons formed by a quark and an antiquark pair (a pair of matter particle and antimatter particle) and bosons which are messengers of known interactions (photons for electromagnetism, W and Z bosons for the weak interaction, gluons for the strong interaction). The antiparticle of a matter particle belongs to the class of antimatter particles, the antiparticle of an antimatter particle belongs to the class of matter particles. The antiparticle of a matter neutral particle belongs to the same class of matter neutral particles. A truly neutral particle is a particle identical with its antiparticle; it belongs necessarily to the class of matter neutral particles. All known interactions of the Standard Model conserve baryon number and lepton number; matter cannot be created or destroyed via a reaction governed by these interactions. Conservation of baryon and lepton number parallels conservation of atoms in chemistry; the number of atoms of a particular species in the reactants must equal the number of those atoms in the products. These laws of conservation valid for interaction involving matter particles are indeed valid for any particles (matter particles characterized by positive numbers, antimatter particles characterized by negative numbers, and matter neutral particles characterized by zero). Interactions within the framework of the Standard Model which conserve both matter and charge at the microscopic level cannot explain the observed asymmetry of our Universe. The strong interaction was introduced to explain the stability of nuclei: there must exist a powerful force to compensate the electromagnetic force which tends to cause protons to fly apart. The weak interaction with laws of conservation different from electromagnetism and the strong interaction was postulated to explain beta decay. Our observed material and neutral universe would signify the existence of another interaction that did conserve charge but did not conserve matter.

scholarly journals Non-spherical nucleon clusters in the mantle of a neutron star: CLDM based on Skyrme-type forces

2021 ◽  
Vol 2103 (1) ◽  
pp. 012004
Author(s):  
N A Zemlyakov ◽  
A I Chugunov ◽  
N N Shchechilin
Keyword(s):  
Neutron Star ◽  
Nuclear Matter ◽  
Liquid Drop ◽  
Outer Region ◽  
Spherical Shape ◽  
Baryon Number ◽  
Compressible Liquid ◽  
Liquid Drop Model ◽  
The Core ◽  
Nuclear Clusters

Abstract Neutron stars are superdense compact astrophysical objects. The central region of the neuron star (the core) consists of locally homogeneous nuclear matter, while in the outer region (the crust) nucleons are clustered. In the outer crust these nuclear clusters represent neutron-rich atomic nuclei and all nucleons are bound within them. Whereas in the inner crust some neutrons are unbound, but nuclear clusters still keeps generally spherical shape. Here we consider the region between the crust and the core of the star, so-called mantle, where non-spherical nuclear clusters may exist. We apply compressible liquid drop model to calculate the energy density for several shape types of nuclear clusters. It allows us to identify the most energetically favorable configuration as function of baryon number density. Employing four Skyrme-type forces (SLy4 and BSk24, BSk25, BSk26), which are widely used in the neutron star physics, we faced with strong model dependence of the ground state composition. In particular, in agreement with previous works within liquid drop model, mantle is absent for SLy4 (nuclear spheres directly transit into homogeneous nuclear matter; exotic nuclear shapes do not appear).

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