Search results for "Radius"
showing 10 items of 708 documents
Getting covariantly smeared sources into better shape
2014
The use of covariantly smeared sources in hadronic correlators is a common method of improving the projection onto the ground state. Studying the dependence of the shape of such sources on the gauge field background, we find that localized fluxes of magnetic field can strongly distort the sources. This results in a reduction of the smearing radii that can be reached by iterative smearing prescriptions, in particular as the continuum limit is approached. As a remedy, we propose a novel covariant smearing procedure (“free-form smearing”) enabling the creation of arbitrarily shaped sources, including in particular Gaussians of arbitrary radius, as well as shapes with nodes, such as hydrogenic …
Size of the accretion disk in the gravitationally lensed quasar SDSS J1004+4112 from the statistics of microlensing magnifications
2016
We present eight monitoring seasons of the four brightest images of the gravitational lens SDSS J1004+4112 observed between December 2003 and October 2010. Using measured time delays for the images A, B and C and the model predicted time delay for image D we have removed the intrinsic quasar variability, finding microlensing events of about 0.5 and 0.7 mag of amplitude in the images C and D. From the statistics of microlensing amplitudes in images A, C, and D, we have inferred the half-light radius (at {\lambda} rest = 2407 {\AA}) for the accretion disk using two different methods, $R_{1/2}=8.7^{+18.5}_{-5.5} \sqrt{M/0.3 M_\odot}$ (histograms product) and $R_{1/2} = 4.2^{+3.2}_{-2.2} \sqrt{…
Dynamics of magnetized relativistic tori oscillating around black holes
2007
We present a numerical study of the dynamics of magnetized, relativistic, non-self-gravitating, axisymmetric tori orbiting in the background spacetimes of Schwarzschild and Kerr black holes. The initial models have a constant specific angular momentum and are built with a non-zero toroidal magnetic field component, for which equilibrium configurations have recently been obtained. In this work we extend our previous investigations which dealt with purely hydrodynamical thick discs, and study the dynamics of magnetized tori subject to perturbations which, for the values of the magnetic field strength considered here, trigger quasi-periodic oscillations lasting for tens of orbital periods. Ove…
Periodic Table of the Elements, History, Education and Evaluation
2021
The periodic tables of transition metal thiophosphates MPS3, transition metal dichalcogenides MX2 and other materials, the origin of chemical elements and toxic trace elements in dried mushrooms are provided. The effective nucleus-electron attraction is proportional to the effective nuclear charge (Zeff) and inversely proportional to the effective principal quantum number (n*). The periodic arch is one of many modern visual displays that have been developed to augment the traditional periodic table of the chemical elements. The table is related to the multiparameter optimisation of N atom, nuclear magnetic resonance and everyday life. Educational activities were developed and evaluated. Se …
Lösungseigenschaften von polymethylmethacrylat und polystyrol aus Röntgenkleinwinkelmessungen
1969
Die mit der Lichtstreuungsmethode an Losungen von Polymethylmethacrylat (PMMA) und Polystyrol (PST) im Bereich groser Molekulargewichte durchgefuhrten Untersuchungen werden mit Hilfe von Rontgenkleinwinkelmessungen auf das Gebiet Kleiner Molekulargewichte ausgedehnt. Es gibt einen Molekulargewichtsbereich (M = 103 bis 3·104), innerhalb dessen auch im guten Losungsmittel der Tragheitsradius der Wurzel aus dem Molekulargewicht proportional ist. Bei PMMA stimmen in diesem Bereich und auch bei kleineren Molekulargewichten die Tragheitsradein im guten Losungsmittel Aceton mit denen im verwendeten Θ-Losungsmittel innerhalb der Fehlergrenzen uberein; bei PST in Toluol gilt das nicht. Aus den Bezie…
The runaway instability of thick discs around black holes. II. Non constant angular momentum discs
2003
We present results from a comprehensive number of relativistic, time-dependent, axisymmetric simulations of the runaway instability of non-constant angular momentum thick discs around black holes. This second paper extends earlier results where only constant angular momentum discs were considered. All relevant aspects of the theory of stationary thick discs around rotating black holes, necessary to build the initial state in our simulations, are presented in great detail. The angular momentum of the discs is assumed to increase outwards with the radial distance according to a power law. The main simplifying assumptions of our approach are not to include magnetic fields and self-gravity in t…
A method to constrain the neutron star magnetic field in Low Mass X-ray Binaries
2005
We describe here a method to put an upper limit to the strength of the magnetic field of neutron stars in low mass X‐ray binaries for which the spin period and the X‐ray luminosity during X‐ray quiescent periods are known. This is obtained using simple considerations about the position of the magnetospheric radius during quiescent periods. We applied this method to the accreting millisecond pulsar SAX J1808.4‐3658, which shows coherent X‐ray pulsations at a frequency of ∼ 400 Hz and a quiescent X‐ray luminosity of ∼ 5 × 1031 ergs/s, and found that B ⩽ 5 × 108 Gauss in this source. Combined with the lower limit inferred from the presence of X‐ray pulsations, this constrains the SAX J1808.4‐3…
Emission of neutrons and the neutron halo of $^{11}$Li
1991
The matter distribution of the neutron drip-line nuclei has been a subject of intense interest since pioneering radioactive-beam experiments at Berkeley1). Unusually large interaction cross-sections measured at relativistic energies for 11Li,14Be and 17B nuclei were translated into effective matter radii. It was found that these were significantly larger than for other p-shell nuclei. In particular, the root-mean-square (rms) mass radius of 11Li was found to be 3.2fm, which was considerably larger than the 2.4fm radius of 9Li. At the same time, no signatures for significant deformation of 11Li were found in measurements of electric quadrupole moment by means of laser spectroscopy2).
Electromagnetic energy within dielectric spheres
1987
We present exact and approximate analytic expressions for the time-averaged electromagnetic energy within dielectric spheres on the basis of rigorous Mie theory. Such information is of importance for the study of photochemical reactions within atmospheric water spheres. Numerical results show that on the average the energy inside a cloud droplet is enlarged by a factor exceeding 2 compared with that of a sphere of the same radius of the surrounding medium. In regions of resonance peaks the electromagnetic energy may be increased by more than 2 orders of magnitude.
Dosimetry revisited for the HDR I192r brachytherapy source model mHDR-v2
2010
Purpose: Recently, the manufacturer of the HDR I 192 r mHDR-v2 brachytherapysource reported small design changes (referred to herein as mHDR-v2r) that are within the manufacturing tolerances but may alter the existing dosimetric data for this source. This study aimed to (1) check whether these changes affect the existing dosimetric data published for this source; (2) obtain new dosimetric data in close proximity to the source, including the contributions from I 192 r electrons and considering the absence of electronic equilibrium; and (3) obtain scatterdose components for collapsed cone treatment planning system implementation. Methods: Three different Monte Carlo(MC) radiation transport co…