The concept of elementary particle rests on the idea that it is a physical system with no excited states, so that all possible states of the particle are just kinematical modifications of any one of them. In this way instead of describing the particle attributes it amounts to describe the collection of consecutive inertial observers who describe the particle in the same kinematical state. The kinematical state space of an elementary particle is a homogeneous space of the kinematical group.By considering the largest homogeneous spaces of both, Galilei and Poincare groups, it is shown how the spin structure is related to the different degrees of freedom. Finally, the spacetime symmetry group of a relativistic particle which satisfies Dirac's equation when quantized, is enlarged to take into account additional symmetries like spacetime dilations and local rotations. An interaction Lagrangian invariant under this enlarged group is proposed and the compound system of two Dirac particles is analyzed.
The questions on the presense and quantitative role of the constant terms in the real part of the high-energy photon-nucleon and photon-nucleus amplitudes representing the contribution of the non-Regge (the fixed j = 0-pole) singularities in the finite-energy sum rules (FESR) for the photoabsorption cross sections on nucleons and the lightest atomic nuclei are discussed and new testable relations are presented for relevant combinations of the Compton scattering amplitudes.
Within a perturbative approach to Quantum Chromodynamics (QCD), we show how to extend ordinary DGLAP longitudinal evolution equations to include the radiative transverse momentum generated in the collinear branching regime. Considering Semi-inclusive Deep Inelastic Scattering as a reference process, we perform such a generalization both in the current and in the target fragmentation region. These distributions are then used to predict semi-inclusive Deep Inelastic Scattering cross-sections onto the whole phase space of the detected hadron.
The Kerr-Newman solution has g=2 as that of the Dirac electron and is considered as a model of spinning particle in general relativity. The Kerr geometry changes cardinally our representations on the role of gravity in the particle physics. We show that the Kerr gravitational field has a stringy local action and a topological peculiarity which are extended up to the Compton distances, and also a strong non-local action playing the key role in the mass-renormalization and regularization of singularities. The Kerr-Newman gravity determines the structure of spinning particle in the form of a relativistically rotating disk, a highly oblate bag of the Compton radius. Interior of this bag consists of an AdS or dS ``false vacuum'', depending on the correlation of the mass density and charge. In the same time, the local action of gravitational field may be considered as negligible for regularized particle.
Relativistic formulae for spin averaged and spin dependent one photon exchange differential cross sections are developed for spin half fermion fermion elastic scattering. Spin transfer cross sections are important for the Polarized Antiproton eXperiments (PAX) project at GSI Darmstadt. In particular, cross sections for polarization transfer in antiproton electron and antiproton proton elastic collisions are presented.
We study light vector meson photoproduction at small $x$ on the basis of the generalized parton distribution (GPD). Our results on the cross section and spin density matrix elements (SDME) are in fair agreement with DESY experiments
Emphasizing the physical constraints on the formulation of the quantum theory, based on the standard measurement axiom and the Schrodinger equation, we comment on some conceptual issues arising in the formulation of the PT-symmetric quantum mechanics. In particular, we elaborate on the requirements of the boundedness of the metric operator and the diagonalizability of the Hamiltonian. We also provide an accessible account of a Kreins-pace derivation of the CPT-inner product, that was widely known to mathematicians since 1950's. We show how this derivation is linked with the pseudo-Hermitian formulation of the PT-symmetric quantum mechanics.
The possibility to excite low-energy nuclear states using laser induced plasma on the Prague Asterix Laser System PALS is investigated. This medium-energy high-power facility yields interaction intensities at the level of 10 16 ÷ 10 17 Wcm −2 thus producing subrelativistic plasmas with electron temperature of the order of 1 ÷ 10 keV. Based on a systematic survey of suitable candidate nuclei, the search for the 6.238 keV excitation and decay in 181 Ta has been initiated. Tests and preliminary operation of detecting systems including active detectors are reported.
In the past several years come up interest of laser devices in plasma applications. Interaction between a laser beam and magnetized plasma is very important for the next use of the laser beam to increase the plasma temperature.
Theoretical investigation on the propagation of ion-acoustic waves in an unmagnetized self-gravitating plasma has been made for the existence of solitary waves using the reductive perturbation method. It is observed that nonlinear excitations follow a coupled third-order partial differential equation which is slightly different from the usual case of coupled Korteweg-de Vries (K-dV) system. It appears that the system so deduced is a two-component generalization of the previous one derived by Paul et al. (1999) in which it was shown that ion-acoustic solitary waves can not exist in such system.
Two nonlinear Schrödinger equations, linked by cross-modulation terms, are used to study the nature of coupled pulse propagation in an optical fiber. The problem is formulated within the framework of variational calculus. Using Gaussian trial functions for the propagating pulses, an expression is constructed for the effective Lagrangian of the system. It is shown that this Lagrangian, via the Ritz optimization procedure, provides a basis to construct approximate solutions of the problem. Some judicious approximations are invoked to investigate how the cross modulation affects the behavior of pulse propagation. Conditions are derived under which both pulses can propagate without distortion.
The results of 3-dimensional (3D) Particle Image Velocimetry (PIV) measurements of the electrohydrodynamic (EHD) flow patterns in a narrow electrostatic precipitator (ESP) are presented in this paper. The ESP was an acrylic parallelepiped with a wire discharge electrode and two plane collecting electrodes. In contrary to typical ESPs the wire electrode was placed along the gas flow, in the ESP centre, in the halfway between collecting electrodes. Either two smooth stainless steel plates or two stainless steel meshes with nylon flocks were used as the collecting electrodes. They were placed on the top and bottom of the ESP. The PIV measurements were carried out in two parallel planes, placed perpendicularly to the collecting electrodes and parallel to the wire electrode. The obtained results showed some similarities and differences of a 3D particle flow in the ESP with plate or flocking electrodes.
Diamond-like carbon (DLC) films can be produced by Pulsed Laser Deposition (PLD) technique in vacuum. Energetic laser pulses, with intensity of the order of 10 10 W/cm 2 , can be employed to generate hot carbon plasmas from glassy carbon ablation. Particles ejected from plasma can be deposited and/or ion implanted on different substrates. Energetic particles diffuse on the substrate surface and may generate nucleation and nanostructures. In the present work a Nd:Yag laser radiation, 532 nm wavelength, 9 ns pulse duration and 30 Hz repetition rate, was employed to grow thin DLC films on SiO 2 substrates, placed at different distances and angles from the target. The PLD-generated plasma can be controlled “on line” by mass quadrupole spectrometry and time-of-flight techniques, in order to evaluate the atomic and molecular kinetic energy distributions. “Off line” investigations were performed on the deposited films by using scanning electron microscopy (SEM), atomic force microscopy (AFM), infrared-absorption spectroscopy (FTIR) and Raman spectroscopy. Nanostructures with cubic shape and 300 nm average size growth on SiO 2 surface are investigated and discussed.
There exist few methods for reconstruction of time-resolved energy distributions of particles which are emitted in intense bursts. One of them, which offers very good results, is the Monte Carlo method. This article describes the use of this method for the reconstruction of time-resolved energy distribution of neutrons which are emitted in D-D fusion reactions. This article shows the main idea and testing of the method. The energy spectra are reconstructed from time-resolved signals of neutrons, which are recorded using several detectors in one direction at different distances. The basic idea of the method and results of testing reflect that the method could give better results while including other detectors in opposite direction. Considering these facts, the method was extended with the transformation of the energy of neutrons, which are emitted in opposite direction. This transformation is based on scattering theory and specifically is applied for the D-D reaction (energy of emitting neutrons is around 2.45 MeV). This modified Monte Carlo method was implemented in the FORTRAN 95 language and was used in the processing of data from experiments in the PF 1000 facility working in the Institute of Plasma Physics and Laser Microfusion in Warsaw. Specifically, shot No. 5566 is presented.
The behaviour of plasma electrons in a laser corona generated by focusing the first harmonic (λ = 1.315 µm) beam of the nanosecond iodine laser Asterix for a power density in the focal spot of 10 16 Wcm −2 is studied by solving a 1D Vlasov equation with a small collision term coupled to the Maxwell equations to describe the wave propagation and transformation in a long plasma corona. The temporal evolution of electron phase space is studied in detail with the aim to identify the mechanisms relevant for the wave properties. The dominant wave modes occurring in our model are both the backward and forward propagating Raman waves, each accompanied by a daughter electrostatic wave, which may strongly interact with the plasma electrons. Within the frame of our model we identify several mechanisms of wave transformation accompanying the propagation and the corresponding kinetic phenomena in the phase space. These are visualized by the behaviour of electron distribution function, evolution of electrostatic spectrum and of Raman reflection coefficient.
The positive column of DC glow discharge sustained in pure O-2, Ar and O-2-Ar mixtures with several concentration ratios has been studied in two U-shaped discharge tubes made from different materials for discharge currents up to 30 mA. Total mixture pressures were 3 and 7 Torr. Parameters of discharge - electrical field strength and emission spectra - were studied by means of double-probe method and optical emission spectroscopy. We have focused on the investigation of affecting the intensities of the oxygen spectral lines and bands by the presence of argon for different ratios of the components in mixtures.From the point of view of the role of the discharge tubes material, no very significant role of the material has been observed mainly for the small portion of oxygen in the mixture.
The paper describes results of the recent measurements of fusion-reaction protons, which were performed within the large PF-1000 facility operated at IPPLM in Warsaw. The main aim of those studies was to perform time-integrated measurements of fast (about 3-MeV) protons by means of ion-pinhole cameras, which were equipped with nuclear track detectors (of the PM-355 type) and appropriate absorption filters. To determine the angular distribution of fusion protons the use was made of seven miniature pinhole cameras placed at different angles to the PF-1000 axis. The irradiated and etched detectors were analyzed with an optical microscope. To gain more information about fusion processes occurring inside the high-temperature deuterium plasma, the results were compared with those provided by other diagnostics. The most important result is a comparison of the fusion-reaction protons characteristics with the results of neutron and hard X-ray measurements. Fusion-reaction neutron measurements, which were performed by means of a few scintillation-probes placed at different distances from the PF facility electrode outlet, delivered some complementary information.
The aim of the presented work was to develop a method, which would make possible to identify spectral lines in complicated optical emission spectra. This is an important task for many optical diagnostic methods. It was found out, that the most useful technique combines a manual identification of the lines by the user, according to the developed database of atomic and molecular lines, and an enhanced support of the user by various assistant mechanisms. Therefore, in this work a software for displaying, identification and analysis of the optical emission spectra was developed. Besides the identification, program enables a basic handling of the spectra, corrections of the wavelengths and intensities of the spectra and calculations of some plasma parameters (e. g. calculation of rotational, vibrational and electron temperatures) or other important quantities (e. g. calculation of integrated intensity). The developed software was applied to the study of low pressure RF discharge in neon.
The analytical formalism of Rokushima and Yamakita [J. Opt. Soc. Am. 73, 901–908 (1983)] treating the Fraunhofer diffraction in planar multilayered anisotropic gratings proved to be a useful introduction to new fundamental and practical situations encountered in laterally structured periodic (both isotropic and anisotropic) multilayer media. These are employed in the spectroscopic ellipsometry for modeling surface roughness and in-depth profiles, as well as in the design of various frequency-selective elements including photonic crystals. The subject forms the basis for the solution of inverse problems in scatterometry of periodic nanostructures including magnetic and magneto-optic recording media. It has no principal limitations as for the frequencies and period to radiation wavelength ratios and may include matter wave diffraction. The aim of the paper is to make this formalism easily accessible to a broader community of students and non-specialists. Many aspects of traditional electromagnetic optics are covered as special cases from a modern and more general point of view, e.g., plane wave propagation in isotropic media, reflection and refraction at interfaces, Fabry-Perot resonator, optics of thin films and multilayers, slab dielectric waveguides, crystal optics, acousto-, electro-, and magneto-optics, diffraction gratings, etc. The formalism is illustrated on a model simulating the diffraction on a ferromagnetic wire grating.
Monochromatic and point-like source which emits a particle beam without wave-like property is proposed. Such a source can be realized by taking halves of entangled pairs. Experimental feasibility to realize such a source is discussed in detail.
