Directory of Open Access Journals (Sweden)
Metin SALTIK
1996-03-01
Full Text Available According to classical electromagnetic theory, an accelerated charge or system of charges radiates electromagnetic waves. In a radio transmitter antenna charges are accelerated along the antenna and release electromagnetic waves, which is radiated at the velocity of light in the surrounding medium. All of the radio transmitters work on this principle today. In this study an analogy is established between the principles by which accelerated charge systems markes radiation and the accelerated mass system, and the systems cousing gravitational radiation are investigated.
Gravitation radiation observations
Glass, E. N.
2017-01-01
The notion of gravitational radiation begins with electromagnetic radiation. In 1887 Heinrich Hertz, working in one room, generated and received electromagnetic radiation. Maxwell's equations describe the electromagnetic field. The quanta of electromagnetic radiation are spin 1 photons. They are fundamental to atomic physics and quantum electrodynamics.
Schäfer, G.; Schutz, B.
1996-01-01
Gravity is truly universal. It is the force that pulls us to the Earth, that keeps the planets and moons in their orbits, and that causes the tides on the Earth to ebb and flow. It even keeps the Sun shining. Yet on a laboratory scale gravity is extremely weak. The Coulomb force between two protons is 1039 times stronger than the gravitational force between them. Moreover, Newton's gravitational constant is the least accurately known of the fundamental constants: it has been measured to 1 par...
Detection of gravitational radiation
Energy Technology Data Exchange (ETDEWEB)
Holten, J.W. van [ed.
1994-12-31
In this report the main contributions presented at the named symposium are collected. These concern astrophysical sources of gravitational radiation, ultracryogenic gravitational wave experiments, read out and data analysis of gravitational wave antennas, cryogenic aspects of large mass cooling to mK temperatures, and metallurgical and engineering aspects of large Cu structure manufacturing. (HSI).
Detection of gravitational radiation
International Nuclear Information System (INIS)
Holten, J.W. van
1994-01-01
In this report the main contributions presented at the named symposium are collected. These concern astrophysical sources of gravitational radiation, ultracryogenic gravitational wave experiments, read out and data analysis of gravitational wave antennas, cryogenic aspects of large mass cooling to mK temperatures, and metallurgical and engineering aspects of large Cu structure manufacturing. (HSI)
Gravitational radiation reaction
International Nuclear Information System (INIS)
Tanaka, Takahiro
2006-01-01
We give a short personally-biased review on the recent progress in our understanding of gravitational radiation reaction acting on a point particle orbiting a black hole. The main motivation of this study is to obtain sufficiently precise gravitational waveforms from inspiraling binary compact starts with a large mass ratio. For this purpose, various new concepts and techniques have been developed to compute the orbital evolution taking into account the gravitational self-force. Combining these ideas with a few supplementary new ideas, we try to outline a path to our goal here. (author)
Gravitational radiation from dust
International Nuclear Information System (INIS)
Isaacson, R.A.; Welling, J.S.; Winicour, J.
1985-01-01
A dust cloud is examined within the framework of the general relativistic characteristic initial value problem. Unique gravitational initial data are obtained by requiring that the space-time be quasi-Newtonian. Explicit calculations of metric and matter fields are presented, which include all post-Newtonian corrections necessary to discuss the major physical properties of null infinity. These results establish a curved space version of the Einstein quadrupole formula, in the form ''news function equals third time derivative of transverse quadrupole moment,'' for this system. However, these results imply that some weakened notion of asymptotic flatness is necessary for the description of quasi-Newtonian systems
Gravitational Physics Research
Wu, S. T.
2000-01-01
Gravitational physics research at ISPAE is connected with NASA's Relativity Mission (Gravity Probe B (GP-B)) which will perform a test of Einstein's General Relativity Theory. GP-B will measure the geodetic and motional effect predicted by General Relativity Theory with extremely stable and sensitive gyroscopes in an earth orbiting satellite. Both effects cause a very small precession of the gyroscope spin axis. The goal of the GP-B experiment is the measurement of the gyroscope precession with very high precision. GP-B is being developed by a team at Stanford University and is scheduled for launch in the year 2001. The related UAH research is a collaboration with Stanford University and MSFC. This research is focussed primarily on the error analysis and data reduction methods of the experiment but includes other topics concerned with experiment systems and their performance affecting the science measurements. The hydrogen maser is the most accurate and stable clock available. It will be used in future gravitational physics missions to measure relativistic effects such as the second order Doppler effect. The HMC experiment, currently under development at the Smithsonian Astrophysical Observatory (SAO), will test the performance and capability of the hydrogen maser clock for gravitational physics measurements. UAH in collaboration with the SAO science team will study methods to evaluate the behavior and performance of the HMC. The GP-B data analysis developed by the Stanford group involves complicated mathematical operations. This situation led to the idea to investigate alternate and possibly simpler mathematical procedures to extract the GP-B measurements form the data stream. Comparison of different methods would increase the confidence in the selected scheme.
On the gravitational radiation formula
International Nuclear Information System (INIS)
Schaefer, G.; Dehnen, H.
1980-01-01
For electromagnetically as well as gravitationally bound quantum mechanical many-body systems the coefficients of absorption and induced emission of gravitational radiation are calculated in the first-order approximation. The results are extended subsequently to systems with arbitrary non-Coulomb-like two-particle interaction potentials;it is shown explicitly that in all cases the perturbation of the binding potentials of the bound systems by the incident gravitational wave field itself must be taken into account. With the help of the thermodynamic equilibrium of gravitational radiation and quantised matter, the coefficients for spontaneous emission of gravitational radiation are derived and the gravitational radiation formula for emission of gravitational quadrupole radiation by bound quantum mechanical many-body systems is given. According to the correspondence principle the present result is completely identical with the well known classical radiation formula, by which recent criticism against this formula is refuted. Finally the quantum mechanical absorption cross section for gravitational quadrupole radiation is deduced and compared with the corresponding classical expressions. As a special example the vibrating two-mass quadrupole is treated explicitly. (author)
Gravitational scattering of electromagnetic radiation
Brooker, J. T.; Janis, A. I.
1980-01-01
The scattering of electromagnetic radiation by linearized gravitational fields is studied to second order in a perturbation expansion. The incoming electromagnetic radiation can be of arbitrary multipole structure, and the gravitational fields are also taken to be advanced fields of arbitrary multipole structure. All electromagnetic multipole radiation is found to be scattered by gravitational monopole and time-varying dipole fields. No case has been found, however, in which any electromagnetic multipole radiation is scattered by gravitational fields of quadrupole or higher-order multipole structure. This lack of scattering is established for infinite classes of special cases, and is conjectured to hold in general. The results of the scattering analysis are applied to the case of electromagnetic radiation scattered by a moving mass. It is shown how the mass and velocity may be determined by a knowledge of the incident and scattered radiation.
Resonant-bar gravitational radiation antennas
International Nuclear Information System (INIS)
Blair, D.G.
1987-01-01
This paper reviews the concept of gravitational radiation, and describes the worldwide research programme for the development of high-sensitivity resonant-bar antennas which are aimed at detecting gravitational radiation from astrophysical sources. (author)
Accelerating Photons with Gravitational Radiation
Shore, Graham M
2001-01-01
The nature of superluminal photon propagation in the gravitational field describing radiation from a time-dependent, isolated source (the Bondi-Sachs metric) is considered in an effective theory which includes interactions which violate the strong equivalence principle. Such interactions are, for example, generated by vacuum polarisation in conventional QED in curved spacetime. The relation of the resulting light-cone modifications to the Peeling Theorem for the Bondi-Sachs spacetime is explained.
Gravitational radiation from electromagnetic systems
International Nuclear Information System (INIS)
Nikishov, A.I.; Ritus, V.I.
1989-01-01
It is shown that the spectrum of gravitational radiation of a charge e with mass m, undergoing finite motion in an electromagnetic field, smoothly varying in the neighborhood of the orbit over a region of the order of the radius of curvature, differs in the ultrarelativistic limit from the spectrum of the charge's electromagnetic radiation. The difference consists of the frequency-independent coefficient 4πGm 2 Λ 2 /e 2 , where Λ is of the order of the Lorentz factor of the charge and depends on the direction of the wave vector and on the behavior of the field in the above-indicated region. For a plane-wave external field the gravitational and electromagnetic spectra are strictly proportional to each other for arbitrary velocities of the charge. Localization of the external forces near the orbit violates this proportionality of the spectra and weakens the gravitational radiation by an amount of the order of the square of the Lorentz factor
Gravitational radiation quadrupole formula is valid for gravitationally interacting systems
International Nuclear Information System (INIS)
Walker, M.; Will, C.M.
1980-01-01
An argument is presented for the validity of the quadrupole formula for gravitational radiation energy loss in the far field of nearly Newtonian (e.g., binary stellar) systems. This argument differs from earlier ones in that it determines beforehand the formal accuracy of approximation required to describe gravitationally self-interacting systems, uses the corresponding approximate equation of motion explicitly, and evaluate the appropriate asymptotic quantities by matching along the correct space-time light cones
Gravitational radiation and 3D numerical relativity
International Nuclear Information System (INIS)
Nakamura, T.
1986-01-01
Study of Numerical Relativity in Kyoto is reviewed. Main topics discussed are 2D rotating collapse, phase cancellation effects and perturbation calculation of the gravitational radiation from a particle falling into a black hole. New numerical results on 3D time evolution of pure gravitational waves are also presented
Conservation laws and gravitational radiation
International Nuclear Information System (INIS)
Rastall, P.
1977-01-01
A total stress-momentum is defined for gravitational fields and their sources. The Lagrangian density is slightly different from that in the previous version of the theory, and the field equations are considerably simplified. The post-Newtonian approximation of the theory is unchanged. The existence and nature of weak gravitational waves are discussed. (author)
Introduction to the theory of gravitational radiation
International Nuclear Information System (INIS)
Damour, T.
1987-01-01
In these lectures our attention is restricted to the analytical investigations of the theory of gravitational radiation. There exist already several reviews concerning this topic and, in particular, a recent detailed review, by Thorne, where gravitational radiation theory is put in a form suitable for astrophysical studies. This is why the scope of these lectures is limited to supplement the existing reviews in two ways. First, both the basic concepts of gravitational radiation theory, and the precise conditions, as well as the limitations, of validity of some of the well-known results in this theory are presented. Indeed, as these results have been, or will be, applied in astrophysics, it is important to have clearly in mind both what they mean, and when they can be legitimately applied. Second, a progress report on some of the ongoing analytical research in gravitational radiation theory is presented. 144 references
Gravitational perturbation theory and synchrotron radiation
Energy Technology Data Exchange (ETDEWEB)
Breuer, R A [Max-Planck-Institut fuer Physik und Astrophysik, Muenchen (F.R. Germany). Inst. fuer Astrophysik
1975-01-01
This article presents methods and results for a gravitational perturbation theory which treats massless fields as linearized perturbations of an arbitrary gravitational vacuum background spacetime. The formalism is outlined for perturbations of type (22) spacetimes. As an application, high-frequency radiation emitted by particles moving approximately on relativistic circular geodesic orbits is computed. More precisely, the test particle assumption is made; throughout it is therefore assumed that the reaction of the radiation on the particle motion is negligible. In particular, these orbits are studied in the gravitational field of a spherically symmetric (Schwarzschild-) black hole as well as of a rotating (Kerr-) black hole. In this model, the outgoing radiation is highly focussed and of much higher fequency than the orbital frequency, i.e. one is dealing with 'gravitational synchrotron radiation'.
Production of gravitation waves by electromagnetic radiation
International Nuclear Information System (INIS)
Buchner, K.; Rosca, R.
1980-01-01
An exact solution of Einstein's equations is presented that corresponds to an axisymmetric bundle of electromagnetic waves with finite cross section. Outside this bundle, there is gravitational radiation parallel to the electromagnetic radiation. If no static electromagnetic fields are present, the frequency of the gravitational waves is twice the frequency of the electromagnetic waves. Einstein's energy complex vanishes identically. The covariant energy complex, however, yields also a radial momentum. (author)
Physics, Astrophysics and Cosmology with Gravitational Waves
Directory of Open Access Journals (Sweden)
Sathyaprakash B. S.
2009-03-01
Full Text Available Gravitational wave detectors are already operating at interesting sensitivity levels, and they have an upgrade path that should result in secure detections by 2014. We review the physics of gravitational waves, how they interact with detectors (bars and interferometers, and how these detectors operate. We study the most likely sources of gravitational waves and review the data analysis methods that are used to extract their signals from detector noise. Then we consider the consequences of gravitational wave detections and observations for physics, astrophysics, and cosmology.
Physics, Astrophysics and Cosmology with Gravitational Waves.
Sathyaprakash, B S; Schutz, Bernard F
2009-01-01
Gravitational wave detectors are already operating at interesting sensitivity levels, and they have an upgrade path that should result in secure detections by 2014. We review the physics of gravitational waves, how they interact with detectors (bars and interferometers), and how these detectors operate. We study the most likely sources of gravitational waves and review the data analysis methods that are used to extract their signals from detector noise. Then we consider the consequences of gravitational wave detections and observations for physics, astrophysics, and cosmology.
Gravitational radiation resistance, radiation damping and field fluctuations
International Nuclear Information System (INIS)
Schaefer, G.
1981-01-01
Application is made of two different generalised fluctuation-dissipation theorems and their derivations to the calculation of the gravitational quadrupole radiation resistance using the radiation-reaction force given by Misner, Thorne and Wheeler (Gravitation (San Francisco: Freeman) ch 36,37 (1973)) and the usual tidal force on one hand and the tidal force and the free gravitational radiation field on the other hand. The quantum-mechanical version (including thermal generalisations) of the well known classical quadrupole radiation damping formula is obtained as a function of the radiation resistance. (author)
Theory and experiment in gravitational physics
Will, C. M.
New technological advances have made it feasible to conduct measurements with precision levels which are suitable for experimental tests of the theory of general relativity. This book has been designed to fill a new need for a complete treatment of techniques for analyzing gravitation theory and experience. The Einstein equivalence principle and the foundations of gravitation theory are considered, taking into account the Dicke framework, basic criteria for the viability of a gravitation theory, experimental tests of the Einstein equivalence principle, Schiff's conjecture, and a model theory devised by Lightman and Lee (1973). Gravitation as a geometric phenomenon is considered along with the parametrized post-Newtonian formalism, the classical tests, tests of the strong equivalence principle, gravitational radiation as a tool for testing relativistic gravity, the binary pulsar, and cosmological tests.
Radiatively-induced gravitational leptogenesis
Energy Technology Data Exchange (ETDEWEB)
McDonald, J.I., E-mail: pymcdonald@swansea.ac.uk; Shore, G.M., E-mail: g.m.shore@swansea.ac.uk
2015-12-17
We demonstrate how loop effects in gravitational backgrounds lead to a difference in the propagation of matter and antimatter, and show this is forbidden in flat space due to CPT and translation invariance. This mechanism, which is naturally present in beyond the standard model (BSM) theories exhibiting C and CP violation, generates a curvature-dependent chemical potential for leptons in the low-energy effective Lagrangian, allowing a matter–antimatter asymmetry to be generated in thermodynamic equilibrium, below the BSM scale.
Spherically symmetric radiation in gravitational collapse
International Nuclear Information System (INIS)
Bridy, D.J.
1983-01-01
This paper investigates a previously neglected mode by which a star may lose energy in the late stages of gravitational collapse to the black hole state. A model consisting of a Schwarzschild exterior matched to a Friedman interior of collapsing pressureless dust is studied. The matter of the collapsing star is taken as the source of a massive vector boson field and a detailed boundary value problem is carried out. Vector mesons are strongly coupled to all nucleons and will be radiated by ordinary matter during the collapse. The time dependent coupling between interior and exterior modes matched across the moving boundary of the collapsing star and the presence of the gravitational fields and their gradients in the field equations may give rise to a parametric amplification mechanism and permit the gravitational field to pump energy into the boson field, greatly enhancing the amount of boson radiation. The significance of a radiative mechanism driven by collapse is that it can react back upon the collapsing source and deprive it of some of the very mass that drives the collapse via its self gravitation. If the mass loss is great enough, this may provide a mechanism to slow or even halt gravitational collapse in some cases
Radiatively-induced gravitational leptogenesis
Directory of Open Access Journals (Sweden)
J.I. McDonald
2015-12-01
Full Text Available We demonstrate how loop effects in gravitational backgrounds lead to a difference in the propagation of matter and antimatter, and show this is forbidden in flat space due to CPT and translation invariance. This mechanism, which is naturally present in beyond the standard model (BSM theories exhibiting C and CP violation, generates a curvature-dependent chemical potential for leptons in the low-energy effective Lagrangian, allowing a matter–antimatter asymmetry to be generated in thermodynamic equilibrium, below the BSM scale.
Theory of antennas for gravitational radiation
International Nuclear Information System (INIS)
Hirakawa, Hiromasa; Narihara, Kazumichi; Fujimoto, Masakatsu.
1976-01-01
A theory of antennas for gravitational radiation is presented. On the basis of the eigenmode system and the structure symmetry, the emission and reception characteristics and the directivity pattern of antennas are treated. The antenna thermal noise is discussed in connection with the coupling constant of vibration sensors and with the effect of cold-damping. (auth.)
Why does gravitational radiation produce vorticity?
International Nuclear Information System (INIS)
Herrera, L; Barreto, W; Carot, J; Prisco, A Di
2007-01-01
We calculate the vorticity of worldlines of observers at rest in a Bondi-Sachs frame, produced by gravitational radiation, in a general Sachs metric. We claim that such an effect is related to the super-Poynting vector, in a similar way as the existence of the electromagnetic Poynting vector is related to the vorticity in stationary electrovacuum spacetimes
Advanced instrumentation for Solar System gravitational physics
Peron, Roberto; Bellettini, G.; Berardi, S.; Boni, A.; Cantone, C.; Coradini, A.; Currie, D. G.; Dell'Agnello, S.; Delle Monache, G. O.; Fiorenza, E.; Garattini, M.; Iafolla, V.; Intaglietta, N.; Lefevre, C.; Lops, C.; March, R.; Martini, M.; Nozzoli, S.; Patrizi, G.; Porcelli, L.; Reale, A.; Santoli, F.; Tauraso, R.; Vittori, R.
2010-05-01
The Solar System is a complex laboratory for testing gravitational physics. Indeed, its scale and hierarchical structure make possible a wide range of tests for gravitational theories, studying the motion of both natural and artificial objects. The usual methodology makes use of tracking information related to the bodies, fitted by a suitable dynamical model. Different equations of motion are provided by different theories, which can be therefore tested and compared. Future exploration scenarios show the possibility of placing deep-space probes near the Sun or in outer Solar System, thereby extending the available experimental data sets. In particular, the Earth-Moon is the most accurately known gravitational three-body laboratory, which is undergoing a new, strong wave of research and exploration (both robotic and manned). In addition, the benefits of a synergetic study of planetary science and gravitational physics are of the greatest importance (as shown by the success of the Apollo program), especially in the Earth-Moon, Mars-Phobos, Jovian and Saturnian sub-suystems. This scenarios open critical issues regarding the quality of the available dynamical models, i.e. their capability of fitting data without an excessive number of empirical hypotheses. A typical case is represented by the non-gravitational phenomena, which in general are difficult to model. More generally, gravitation tests with Lunar Laser Ranging, inner or outer Solar System probes and the appearance of the so-called 'anomalies'(like the one indicated by the Pioneers), whatever their real origin (either instrumental effects or due to new physics), show the necessity of a coordinated improvement of tracking and modelization techniques. A common research path will be discussed, employing the development and use of advanced instrumentation to cope with current limitations of Solar System gravitational tests. In particular, the use of high-sensitivity accelerometers, combined with microwave and laser
International Nuclear Information System (INIS)
Nam, Sang Hui
1991-02-01
This book deals with radiation physics, which introduces atomic theory and an atomic nucleus of materials, conception of an atom and materials, wave and particle, X ray generation and character, a radioactive element and change law, nature of radioactivity, neutron rays, fission, alpha collapse and beta collage and a neutrino collapse of artificial radioactivity such as collapse of artificial nucleus and artificial radioactivity and radiative capture, interaction with materials like interaction between a charged particle and materials and interaction among X-ray, r-ray and materials, radiation of quantity and unit and a charged particle accelerator.
Radiation reaction force and unification of electromagnetic and gravitational fields
International Nuclear Information System (INIS)
Lo, C.Y.; Goldstein, G.R.; Napier, A.
1981-04-01
A unified theory of electromagnetic and gravitational fields should modify classical electrodynamics such that the radiation reaction force is accounted for. The analysis leads to a five-dimensional unified theory of five variables. The theory is supported by showing that, for the case of a charged particle moving in a constant magnetic field, the radiation reaction force is indeed included. Moreover, this example shows explicitly that physical changes are associated with the fifth variable. Thus, the notion of a physical five-dimensional space should be seriously taken into consideration
Gravitational probes of dark matter physics
Buckley, Matthew R.; Peter, Annika H. G.
2017-01-01
The nature of dark matter is one of the most pressing questions in particle physics. Yet all our present knowledge of the dark sector to date comes from its gravitational interactions with astrophysical systems. Moreover, astronomical results still have immense potential to constrain the particle properties of dark matter. We introduce a simple 2D parameter space which classifies models in terms of a particle physics interaction strength and a characteristic astrophysical scale on which new p...
International Nuclear Information System (INIS)
Anon.
1976-01-01
The radiation physics program is directed toward understanding the basic mechanism by which charged particles lose energy in traversing matter, and presenting this information in a way meaningful to the study of radiation dosimetry and biological damage. Measurements of the absolute cross sections for the ejection of electrons from ionization by fast charged particles, measurements of optical fluorescence from liquid systems, preliminary analyses of electron emission cross sections for proton bombardment of carbon foils, and nonexponential decay of fluorescence in both polar and nonpolar solutions are covered
Entropy of self-gravitating radiation
International Nuclear Information System (INIS)
Sorkin, R.D.; Wald, R.M.; Jiu, Z.Z.
1981-01-01
The entropy of self-gravitating radiation confined to a spherical box of radius R is examined in the context of general relativity. It is expected that configurations (i.e., initial data) which extremize total entropy will be spherically symmetric, time symmetric distributions of radiation in local thermodynamic equilibrium. Assuming this is the case, it is proved that extrema of S coincide precisely with static equilibrium configurations of the radiation fluid. Furthermore, dynamically stable equilibrium configurations are shown to coincide with local maxima of S. The equilibrium configurations and their entropies are calculated and their properties are discussed. However, it is shown that entropies higher than these local extrema can be achieved and, indeed, arbitrarily high entropies can be attained by configurations inside of or outside but arbitrarily near their own Schwarzschild radius. However, consideration is limited to configurations which are outside their own Schwarzschild radius by at least one radiation wavelength, then the entropy is bounded and it is found Ssub(max) < is approximately equal to MR, where M is the total mass. This supports the validity for self-gravitating systems of the Bekenstein upper limit on the entropy to energy ratio of material bodies. (author)
Gravitational-wave physics and astronomy an introduction to theory, experiment and data analysis
Creighton, Jolien D E
2011-01-01
This most up-to-date, one-stop reference combines coverage of both theory and observational techniques, with introductory sections to bring all readers up to the same level. Written by outstanding researchers directly involved with the scientific program of the Laser Interferometer Gravitational-Wave Observatory (LIGO), the book begins with a brief review of general relativity before going on to describe the physics of gravitational waves and the astrophysical sources of gravitational radiation. Further sections cover gravitational wave detectors, data analysis, and the outlook of gravitation
The physical gravitational degrees of freedom
International Nuclear Information System (INIS)
Anderson, E; Barbour, J; Foster, B Z; Kelleher, B; Murchadha, N O
2005-01-01
When constructing general relativity (GR), Einstein required 4D general covariance. In contrast, we derive GR (in the compact, without boundary case) as a theory of evolving three-dimensional conformal Riemannian geometries obtained by imposing two general principles: (1) time is derived from change; (2) motion and size are relative. We write down an explicit action based on them. We obtain not only GR in the CMC gauge, in its Hamiltonian 3 + 1 reformulation, but also all the equations used in York's conformal technique for solving the initial-value problem. This shows that the independent gravitational degrees of freedom obtained by York do not arise from a gauge fixing but from hitherto unrecognized fundamental symmetry principles. They can therefore be identified as the long-sought Hamiltonian physical gravitational degrees of freedom
Gravitational physics of stellar and galactic systems
International Nuclear Information System (INIS)
Saslaw, W.C.
1985-01-01
The book concerns the gravitational interactions and evolution of astronomical systems on all scales, and is aimed at the graduate student of physics and astronomy. The text is divided into four parts, and each describes areas of the subject in order of decreasing symmetry. The four parts include: idealized homogeneous systems-basic ideas and gentle relaxation; infinite inhomogeneous systems and galaxy clustering; finite spherical systems including clusters of galaxies; galactic nuclei and globular clusters; and finite flattened systems and galaxies. (U.K.)
Physics through the 1990s: Gravitation, cosmology, and cosmic-ray physics
International Nuclear Information System (INIS)
1986-01-01
This report reviews and highlights three areas of astrophysics; gravitation; cosmology; and cosmic-ray physics. Topics such as: gravitational collapse and black holes, gravitational waves, general relativity, nucleosynthesis, and the standard model are among the many topics highlighted
Exact solutions, numerical relativity and gravitational radiation
International Nuclear Information System (INIS)
Winicour, J.
1986-01-01
In recent years, there has emerged a new use for exact solutions to Einstein's equation as checks on the accuracy of numerical relativity codes. Much has already been written about codes based upon the space-like Cauchy problem. In the case of two Killing vectors, a numerical characteristic initial value formulation based upon two intersecting families of null hypersurfaces has successfully evolved the Schwarzschild and the colliding plane wave vacuum solutions. Here the author discusses, in the context of exact solutions, numerical studies of gravitational radiation based upon the null cone initial value problem. Every stage of progress in the null cone approach has been associated with exact solutions in some sense. He begins by briefly recapping this history. Then he presents two new examples illustrating how exact solutions can be useful
Testing fundamental physics with gravitational waves
CERN. Geneva
2017-01-01
The landmark detection of gravitational waves (GWs) has opened a new era in physics, giving access to the hitherto unexplored strong-gravity regime, where spacetime curvature is extreme and the relevant speed is close to the speed of light. In parallel to its countless astrophysical applications, this discovery can have also important implications for fundamental physics. In this context, I will discuss some outstanding, cross-cutting problems that can be finally investigated in the GW era: the nature of black holes and of spacetime singularities, the limits of classical gravity, the existence of extra light fields, and the effects of dark matter near compact objects. Future GW measurements will provide unparalleled tests of quantum-gravity effects at the horizon scale, exotic compact objects, ultralight dark matter, and of general relativity in the strong-field regime.
Gravitational waves — A review on the theoretical foundations of gravitational radiation
Dirkes, Alain
2018-05-01
In this paper, we review the theoretical foundations of gravitational waves in the framework of Albert Einstein’s theory of general relativity. Following Einstein’s early efforts, we first derive the linearized Einstein field equations and work out the corresponding gravitational wave equation. Moreover, we present the gravitational potentials in the far away wave zone field point approximation obtained from the relaxed Einstein field equations. We close this review by taking a closer look on the radiative losses of gravitating n-body systems and present some aspects of the current interferometric gravitational waves detectors. Each section has a separate appendix contribution where further computational details are displayed. To conclude, we summarize the main results and present a brief outlook in terms of current ongoing efforts to build a spaced-based gravitational wave observatory.
Radiation and detection of gravitational waves in laboratory conditions
International Nuclear Information System (INIS)
Bogolyubov, P.N.; Pisarev, A.F.; Shavokhina, N.S.
1981-01-01
Two variants are proposed and analyzed for an experiment on radiation and detection of gravitational waves in laboratory conditions in the optical and superhigh frequency range (band). In the first variant the laser light is parametrically transformed to the gravitational wave in the optical-inhomogeneous medium. The gravitational flux produced is registered by the inverse parametric transformation of the gravitational to light wave. In the second variant the radiation of gravitational waves is realized through hypersonic oscillations in piezocrystals, and the reception of waves is made by the superconducting coaxial resonator in which the gravitational wave resonantly transforms into the electromag= . netic wave. The analysis performed testifies to the possibility of an experiment of this type at the present time [ru
Interiors of Vaidya's radiating metric: Gravitational collapse
International Nuclear Information System (INIS)
Fayos, F.; Jaen, X.; Llanta, E.; Senovilla, J.M.M.
1992-01-01
Using the Darmois junction conditions, we give the necessary and sufficient conditions for the matching of a general spherically symmetric metric to a Vaidya radiating solution. We present also these conditions in terms of the physical quantities of the corresponding energy-momentum tensors. The physical interpretation of the results and their possible applications are studied, and we also perform a detailed analysis of previous work on the subject by other authors
Misner, Charles W; Wheeler, John Archibald
2017-01-01
First published in 1973, Gravitation is a landmark graduate-level textbook that presents Einstein’s general theory of relativity and offers a rigorous, full-year course on the physics of gravitation. Upon publication, Science called it “a pedagogic masterpiece,” and it has since become a classic, considered essential reading for every serious student and researcher in the field of relativity. This authoritative text has shaped the research of generations of physicists and astronomers, and the book continues to influence the way experts think about the subject. With an emphasis on geometric interpretation, this masterful and comprehensive book introduces the theory of relativity; describes physical applications, from stars to black holes and gravitational waves; and portrays the field’s frontiers. The book also offers a unique, alternating, two-track pathway through the subject. Material focusing on basic physical ideas is designated as Track 1 and formulates an appropriate one-semester graduate-level...
Gravitational radiation from nearly Newtonian systems
International Nuclear Information System (INIS)
Kirk, E.M.
1989-09-01
A method of examining gravitational radiation from nearly Newtonian systems is presented. Using the Cartan formulation of Newtonian gravity, a one parameter family of space-times which have a strict Newtonian limit is constructed. An expression for the initial null data in terms of the Newtonian potential is obtained in the Newtonian limit. Using this, the problem is formulated as a series in the Newtonian parameter. The series expansions for the sources of the Bianchi identities are obtained to third order in both the vacuum and non-vacuum cases. A simple technique is presented for determining whether a particular source term gives rise to asymptotically flat null data. The far field quadrupole formula is derived in a leading approximation and a method for obtaining error bounds is discussed. Additionally, a method for solving Einstein's equations is shown. This involves expressing the Ricci identities as a matrix, Riccati equation and a system of linear matrix equations. A comparison of the formalisms of Bondi and Newman Penrose is presented and explicit correspondences between the supersurface constrain equations and the Ricci identities are shown. (author)
Physics of interferometric gravitational wave detectors
Indian Academy of Sciences (India)
The Caltech-MIT joint LIGO project is operating three long-baseline interferometers (one of 2 km and two of 4 km) in order to unambiguously measure the infinitesimal displacements of isolated test masses which convey the signature of gravitational waves from astrophysical sources. An interferometric gravitational wave ...
International Nuclear Information System (INIS)
Robles, Ana Maria
1994-01-01
A brief historical review of radioactivity, nuclear physics, atomic nucleus, nuclear models,nuclear instability, mass defect, nuclear transmutations, radioactivity phenomenon, Batemand equations, decay constants, half life, mean life, des integration rates,units.Alpha, Beta and gamma decay, other less probably encountered decay modes.Bibliography
International Nuclear Information System (INIS)
Sorenson, J.A.
1987-01-01
As in other technologically based field, progress in medical imaging occurs both by ''breakthroughs,'' such as completely new concepts, and by evolutionary advances, such as incremental improvements in existing technology. Both types of advances are of fundamental importance to the field. The new kinestatic charge detection technique, which represents a fundamentally new concept in image recording, qualifies as a ''breakthrough.'' This and several other articles describe new approaches to digital radiography, focusing in particular on the formidable problems of trying to match the excellent image recording and display capabilities of x-ray film. An example of an incremental improvement is a new design for x-ray tube filaments. The modified filament design can provide a significant reduction in focal-spot size, without loss of tube-loading capacity. Because spatial resolution is limited in many practical situations by focal-spot blurring, this incremental improvement in the design of an existing piece of hardware is as important a contribution to improving image quality as a new type of digital detector with a two-fold improvement in spatial resolution. The author has included a few articles dealing with practical issues in radiation protection and quality assurance of x-ray imaging systems
Physics of interferometric gravitational wave detectors
Indian Academy of Sciences (India)
The Caltech-MIT joint LIGO project is operating three long-baseline inter- ... gravitational waves for LIGO are: (i) binary coalescing neutron star systems, (ii) ..... The fundamental mode of this basis is a purely Gaussian function which means.
Physical optics in a uniform gravitational field
Hacyan, Shahen
2012-01-01
The motion of a (quasi-)plane wave in a uniform gravitational field is studied. It is shown that the energy of an elliptically polarized wave does not propagate along a geodesic, but in a direction that is rotated with respect to the gravitational force. The similarity with the walk-off effect in anisotropic crystals or the optical Magnus effect in inhomogeneous media is pointed out.
Electromagnetic radiation accompanying gravitational waves from black hole binaries
Energy Technology Data Exchange (ETDEWEB)
Dolgov, A. [Dept. of Physics, Novosibirsk State University, Pirogova 2, 630090 Novosibirsk (Russian Federation); Postnov, K., E-mail: dolgov@fe.infn.it, E-mail: kpostnov@gmail.com [Sternberg Astronomical Institute, Moscow M.V. Lomonosov State University, Universitetskij pr. 13, 119234 Moscow (Russian Federation)
2017-09-01
The transition of powerful gravitational waves, created by the coalescence of massive black hole binaries, into electromagnetic radiation in external magnetic fields is considered. In contrast to the previous calculations of the similar effect we study the realistic case of the gravitational radiation frequency below the plasma frequency of the surrounding medium. The gravitational waves propagating in the plasma constantly create electromagnetic radiation dragging it with them, despite the low frequency. The plasma heating by the unattenuated electromagnetic wave may be significant in hot rarefied plasma with strong magnetic field and can lead to a noticeable burst of electromagnetic radiation with higher frequency. The graviton-to-photon conversion effect in plasma is discussed in the context of possible electromagnetic counterparts of GW150914 and GW170104.
Electromagnetic radiation accompanying gravitational waves from black hole binaries
International Nuclear Information System (INIS)
Dolgov, A.; Postnov, K.
2017-01-01
The transition of powerful gravitational waves, created by the coalescence of massive black hole binaries, into electromagnetic radiation in external magnetic fields is considered. In contrast to the previous calculations of the similar effect we study the realistic case of the gravitational radiation frequency below the plasma frequency of the surrounding medium. The gravitational waves propagating in the plasma constantly create electromagnetic radiation dragging it with them, despite the low frequency. The plasma heating by the unattenuated electromagnetic wave may be significant in hot rarefied plasma with strong magnetic field and can lead to a noticeable burst of electromagnetic radiation with higher frequency. The graviton-to-photon conversion effect in plasma is discussed in the context of possible electromagnetic counterparts of GW150914 and GW170104.
Gravitational radiation reaction in the NUT-de Sitter spacetime
International Nuclear Information System (INIS)
Ahmed, M.
1988-07-01
The equations for gravitational perturbation in the NUT-de Sitter spacetime are obtained. Using these equations, some preliminary calculations have been made with a view to constructing the retarded Green functions. Then with the help of the retarded Green functions, the radiative Green functions have been constructed. With the aid of these radiative Green functions, the reaction force on a particle is computed and this reaction force is then shown to account correctly for the energy and the angular momentum carried away by gravitational radiation to infinity and to the horizon. (author). 9 refs
Detection of gravitational radiation by the Doppler tracking of spacecraft
International Nuclear Information System (INIS)
Mashhoon, B.
1979-01-01
It has been suggested that the residual Doppler shift in the precision electromagnetic tracking of spacecraft be used to search for gravitational radiation that may be incident on the Earth-spacecraft system. The influence of a gravitational wave on the Doppler shift is calculated, and it is found that the residual shift is dominated by two terms: one is due to the passage of electromagnetic waves through the gravitational radiation field, and the other depends on the change in the relative velocity of the Earth and the spacecraft caused by the external wave. A detailed analysis is given of the influence of gravitational radiation on a binary system with an orbital size small compared to the wavelength of the incident radiation. It is shown that, as a consequence of the interaction with the external wave, the system makes a transition from one Keplerian orbit into another which, in general, has a different energy and angular momentum. It is therefore proposed to search for such effects in the solar system. Observations of the orbit of an artificial Earth satellite, the lunar orbit, and especially the planetary orbits offer exciting possibilities for the detection of gravitational waves of various wavelengths. From the results of the lunar laser ranging experiment and the range measurement to Mars, certain interesting limits may be established on the frequency of incidence of gravitational waves of a given flux on the Earth-Moon and the Earth-Mars systems. This is followed by a brief and preliminary analysis of the possibility of detecting gravitational radiation by measuring a residual secular Doppler shift in the satellite-to-satellite Doppler tracking of two counterorbiting drag-free spacecraft around the Earth as in the Van Patten-Everitt experiment
Gravitational wave background from Standard Model physics: qualitative features
International Nuclear Information System (INIS)
Ghiglieri, J.; Laine, M.
2015-01-01
Because of physical processes ranging from microscopic particle collisions to macroscopic hydrodynamic fluctuations, any plasma in thermal equilibrium emits gravitational waves. For the largest wavelengths the emission rate is proportional to the shear viscosity of the plasma. In the Standard Model at 0T > 16 GeV, the shear viscosity is dominated by the most weakly interacting particles, right-handed leptons, and is relatively large. We estimate the order of magnitude of the corresponding spectrum of gravitational waves. Even though at small frequencies (corresponding to the sub-Hz range relevant for planned observatories such as eLISA) this background is tiny compared with that from non-equilibrium sources, the total energy carried by the high-frequency part of the spectrum is non-negligible if the production continues for a long time. We suggest that this may constrain (weakly) the highest temperature of the radiation epoch. Observing the high-frequency part directly sets a very ambitious goal for future generations of GHz-range detectors
Gravitational radiation in quadratic f(R) gravity
International Nuclear Information System (INIS)
Naef, Joachim; Jetzer, Philippe
2011-01-01
We investigate the gravitational radiation emitted by an isolated system for gravity theories with Lagrange density f(R)=R+aR 2 . As a formal result, we obtain leading order corrections to the quadrupole formula in general relativity. We make use of the analogy of f(R) theories with scalar-tensor theories, which in contrast to general relativity feature an additional scalar degree of freedom. Unlike general relativity, where the leading order gravitational radiation is produced by quadrupole moments, the additional degree of freedom predicts gravitational radiation of all multipoles, in particular, monopoles and dipoles, as this is the case for the most alternative gravity theories known today. An application to a hypothetical binary pulsar moving in a circular orbit yields the rough limit a 17 m 2 by constraining the dipole power to account at most for 1% of the quadrupole power as predicted by general relativity.
Gravitational radiation from preheating with many fields
International Nuclear Information System (INIS)
Jr, John T. Giblin; Price, Larry R.; Siemens, Xavier
2010-01-01
Parametric resonances provide a mechanism by which particles can be created just after inflation. Thus far, attention has focused on a single or many inflaton fields coupled to a single scalar field. However, generically we expect the inflaton to couple to many other relativistic degrees of freedom present in the early universe. Using simulations in an expanding Friedmann-Lemaître-Robertson-Walker spacetime, in this paper we show how preheating is affected by the addition of multiple fields coupled to the inflaton. We focus our attention on gravitational wave production — an important potential observational signature of the preheating stage. We find that preheating and its gravitational wave signature is robust to the coupling of the inflaton to more matter fields
Gravitational radiation from preheating with many fields
Energy Technology Data Exchange (ETDEWEB)
Jr, John T. Giblin [Department of Physics, Kenyon College, 201 North College Road, Gambier, OH 43022 (United States); Price, Larry R.; Siemens, Xavier, E-mail: giblinj@kenyon.edu, E-mail: larry@gravity.phys.uwm.edu, E-mail: siemens@gravity.phys.uwm.edu [Center for Gravitation and Cosmology, Department of Physics, University of Wisconsin — Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States)
2010-08-01
Parametric resonances provide a mechanism by which particles can be created just after inflation. Thus far, attention has focused on a single or many inflaton fields coupled to a single scalar field. However, generically we expect the inflaton to couple to many other relativistic degrees of freedom present in the early universe. Using simulations in an expanding Friedmann-Lemaître-Robertson-Walker spacetime, in this paper we show how preheating is affected by the addition of multiple fields coupled to the inflaton. We focus our attention on gravitational wave production — an important potential observational signature of the preheating stage. We find that preheating and its gravitational wave signature is robust to the coupling of the inflaton to more matter fields.
Gravitational radiation and the validity of general relativity
International Nuclear Information System (INIS)
Will, C.M.
2001-01-01
The regular observation of gravitational radiation by a world-wide network of resonant and laser-interferometric detectors will usher in a new form of astronomy. At the same time, it will provide new and interesting tests of general relativity. We review the current empirical status of general relativity, and discuss three areas in which direct observation of gravitational radiation could test the theory further: polarization of the waves, speed of the waves, and back-reaction of the waves on the evolution of the source. (author)
Competition of neutrino and gravitational radiation in neutron star formation
International Nuclear Information System (INIS)
Kazanas, D.; Schramm, D.N.
1976-01-01
The possibility is explored that neutrino radiation, rather than gravitational radiation, may be the dominant way by which non-radial pulsations are damped out in a collapsing star. If this is so it implies that hopes of detecting gravity waves from supernovae explosions are very optimistic. Neutron stars and black holes are probably the collapsed central remnants of a supernovae explosion. These objects presumably originate from collapse of the cores of sufficiently massive stars, following the cessation of thermonuclear burning. Although there is at present no completely consistent detailed theory as to how collapse of the core and the subsequent supernova explosion take place, a general model exists for the final stages of stellar evolution and supernovae explosions. According to this model the electrons of a sufficiently massive stellar core, due to the high density and temperature, become absorbed by the protons through the reaction p + e - → n + v. Very large numbers of neutrinos, resulting from this and other thermal processes, such as pair annihilation, plasma decay, and Bremsstrahlung, are emitted, taking away most of the gravitational energy of the collapse. These neutrinos possibly drive ejection of the overlying stellar mantle, whilst the neutron-rich core collapses further to a condensed remnant. Gravitational radiation comes into play only at very late stages of the collapse. All of this implies that neutrino radiation might contribute to the decay of the non-radial oscillations of the collapsing core and the newly formed neutron star, possibly damping out these oscillations much faster than gravitational radiation. In order to obtain a more quantitative answer to the question the effects of neutrino radiation on the non-radial oscillations are examined. The implication is that neutrino radiation, by more rapid damping of the non-radial oscillations of a newly formed neutron star in a supernova explosion, would hinder gravitational radiation and
Gravitational radiation from first-order phase transitions
International Nuclear Information System (INIS)
Child, Hillary L.; Giblin, John T. Jr.
2012-01-01
It is believed that first-order phase transitions at or around the GUT scale will produce high-frequency gravitational radiation. This radiation is a consequence of the collisions and coalescence of multiple bubbles during the transition. We employ high-resolution lattice simulations to numerically evolve a system of bubbles using only scalar fields, track the anisotropic stress during the process and evolve the metric perturbations associated with gravitational radiation. Although the radiation produced during the bubble collisions has previously been estimated, we find that the coalescence phase enhances this radiation even in the absence of a coupled fluid or turbulence. We comment on how these simulations scale and propose that the same enhancement should be found at the Electroweak scale; this modification should make direct detection of a first-order electroweak phase transition easier
Gravitational radiation from first-order phase transitions
Energy Technology Data Exchange (ETDEWEB)
Child, Hillary L.; Giblin, John T. Jr., E-mail: childh@kenyon.edu, E-mail: giblinj@kenyon.edu [Department of Physics, Kenyon College, 201 North College Road, Gambier, OH 43022 (United States)
2012-10-01
It is believed that first-order phase transitions at or around the GUT scale will produce high-frequency gravitational radiation. This radiation is a consequence of the collisions and coalescence of multiple bubbles during the transition. We employ high-resolution lattice simulations to numerically evolve a system of bubbles using only scalar fields, track the anisotropic stress during the process and evolve the metric perturbations associated with gravitational radiation. Although the radiation produced during the bubble collisions has previously been estimated, we find that the coalescence phase enhances this radiation even in the absence of a coupled fluid or turbulence. We comment on how these simulations scale and propose that the same enhancement should be found at the Electroweak scale; this modification should make direct detection of a first-order electroweak phase transition easier.
Non-linear excitation of gravitational radiation antennae
International Nuclear Information System (INIS)
Blair, D.G.
1982-01-01
A mechanism of non-linear excitation is proposed to explain observed excess noise in gravitational radiation antennae, driven by low frequency vibration. The mechanism is analogous to the excitation of a violin string by low frequency bowing. Numerical estimates for Weber bars suspended by cables are in good agreement with observations. (Auth.)
Imprints of relic gravitational waves in cosmic microwave background radiation
International Nuclear Information System (INIS)
Baskaran, D.; Grishchuk, L. P.; Polnarev, A. G.
2006-01-01
A strong variable gravitational field of the very early Universe inevitably generates relic gravitational waves by amplifying their zero-point quantum oscillations. We begin our discussion by contrasting the concepts of relic gravitational waves and inflationary 'tensor modes'. We explain and summarize the properties of relic gravitational waves that are needed to derive their effects on cosmic microwave background (CMB) temperature and polarization anisotropies. The radiation field is characterized by four invariants I, V, E, B. We reduce the radiative transfer equations to a single integral equation of Voltairre type and solve it analytically and numerically. We formulate the correlation functions C l XX ' for X, X ' =T, E, B and derive their amplitudes, shapes and oscillatory features. Although all of our main conclusions are supported by exact numerical calculations, we obtain them, in effect, analytically by developing and using accurate approximations. We show that the TE correlation at lower l's must be negative (i.e. an anticorrelation), if it is caused by gravitational waves, and positive if it is caused by density perturbations. This difference in TE correlation may be a signature more valuable observationally than the lack or presence of the BB correlation, since the TE signal is about 100 times stronger than the expected BB signal. We discuss the detection by WMAP of the TE anticorrelation at l≅30 and show that such an anticorrelation is possible only in the presence of a significant amount of relic gravitational waves (within the framework of all other common assumptions). We propose models containing considerable amounts of relic gravitational waves that are consistent with the measured TT, TE and EE correlations
Scattering of point particles by black holes: Gravitational radiation
Hopper, Seth; Cardoso, Vitor
2018-02-01
Gravitational waves can teach us not only about sources and the environment where they were generated, but also about the gravitational interaction itself. Here we study the features of gravitational radiation produced during the scattering of a pointlike mass by a black hole. Our results are exact (to numerical error) at any order in a velocity expansion, and are compared against various approximations. At large impact parameter and relatively small velocities our results agree to within percent level with various post-Newtonian and weak-field results. Further, we find good agreement with scaling predictions in the weak-field/high-energy regime. Lastly, we achieve striking agreement with zero-frequency estimates.
Statistical formulation of gravitational radiation reaction
International Nuclear Information System (INIS)
Schutz, B.F.
1980-01-01
A new formulation of the radiation-reaction problem is proposed, which is simpler than alternatives which have been used before. The new approach is based on the initial-value problem, uses approximations which need be uniformly valid only in compact regions of space-time, and makes no time-asymmetric assumptions (no a priori introduction of retarded potentials or outgoing-wave asymptotic conditions). It defines radiation reaction to be the expected evolution of a source obtained by averaging over a statistical ensemble of initial conditions. The ensemble is chosen to reflect one's complete lack of information (in real systems) about the initial data for the radiation field. The approach is applied to the simple case of a weak-field, slow-motion source in general relativity, where it yields the usual expressions for radiation reaction when the gauge is chosen properly. There is a discussion of gauge freedom, and another of the necessity of taking into account reaction corrections to the particle-conservation equation. The analogy with the second law of thermodynamics is very close, and suggests that the electromagnetic and thermodynamic arrows of time are the same. Because the formulation is based on the usual initial-value problem, it has no spurious ''runaway'' solutions
Thermal gravitational radiation of Fermi gases and Fermi liquids
International Nuclear Information System (INIS)
Schafer, G.; Dehnen, H.
1983-01-01
In view of neutron stars the gravitational radiation power of the thermal ''zero-sound'' phonons of a Fermi liquid and the gravitational bremsstrahlung of a degenerate Fermi gas is calculated on the basis of a hard-sphere Fermi particle model. We find for the gravitational radiation power per unit volume P/sub( s/)approx. =[(9π)/sup 1/3//5] x GQ n/sup 5/3/(kT) 4 h 2 c 5 and P/sub( g/)approx. =(4 5 /5 3 )(3/π)/sup 2/3/ G a 2 n/sup 5/3/(kT) 4 /h 2 c 5 for the cases of ''zero sound'' and bremsstrahlung, respectively. Here Q = 4πa 2 is the total cross section of the hard-sphere fermions, where a represents the radius of their hard-core potential. The application to very young neutron stars results in a total gravitational luminosity of about 10 31 erg/sec
Hendee's radiation therapy physics
Pawlicki, Todd; Starkschall, George
2016-01-01
The publication of this fourth edition, more than ten years on from the publication of Radiation Therapy Physics third edition, provides a comprehensive and valuable update to the educational offerings in this field. Led by a new team of highly esteemed authors, building on Dr Hendee’s tradition, Hendee’s Radiation Therapy Physics offers a succinctly written, fully modernised update. Radiation physics has undergone many changes in the past ten years: intensity-modulated radiation therapy (IMRT) has become a routine method of radiation treatment delivery, digital imaging has replaced film-screen imaging for localization and verification, image-guided radiation therapy (IGRT) is frequently used, in many centers proton therapy has become a viable mode of radiation therapy, new approaches have been introduced to radiation therapy quality assurance and safety that focus more on process analysis rather than specific performance testing, and the explosion in patient-and machine-related data has necessitated an ...
Initial value gravitational quadrupole radiation theorem
International Nuclear Information System (INIS)
Winicour, J.
1987-01-01
A rigorous version of the quadrupole radiation formula is derived using the characteristic initial value formulation of a general relativistic fluid space-time. Starting from initial data for a Newtonian fluid, an algorithm is presented that determines characteristic initial data for a one-parameter family of general relativistic fluid space-times. At the initial time, a one-parameter family of space-times with this initial data osculates the evolution of the Newtonian fluid and has leading order news function equal to the third time derivative of the transverse Newtonian quadrupole moment
Cooperstock's counterexample to the gravitational-radiation quadrupole formula
International Nuclear Information System (INIS)
Walker, M.
1986-01-01
Cooperstock has recently modified the axially symmetric gravitational two-body problem previously analyzed by himself, Lim, and Hobill by introducing a new assumption, that ''The system undergoes a smooth transition from the static state to free-fall and the motion. . .consists of the two bodies accelerating towards each other while undergoing slow tidal deformation.'' This assumption is inconsistent with his solution of the field equations. The quadrupole formula correctly describes the radiation emitted
Influence of gravitation on the propagation of electromagnetic radiation
Mashhoon, B.
1975-01-01
The existence of a general helicity-rotation coupling is demonstrated for electromagnetic waves propagating in the field of a slowly rotating body and in the Goedel universe. This coupling leads to differential focusing of circularly polarized radiation by a gravitational field which is detectable for a rapidly rotating collapsed body. The electromagnetic perturbations and their frequency spectrum are given for the Goedel universe. The spectrum of frequencies is bounded from below by the characteristic rotation frequency of the Goedel universe. If the universe were rotating, the differential focusing effect would be extremely small due to the present upper limit on the anisotropy of the microwave background radiation.
Hawking radiation of a vector field and gravitational anomalies
International Nuclear Information System (INIS)
Murata, Keiju; Miyamoto, Umpei
2007-01-01
Recently, the relation between Hawking radiation and gravitational anomalies has been used to estimate the flux of Hawking radiation for a large class of black objects. In this paper, we extend the formalism, originally proposed by Robinson and Wilczek, to the Hawking radiation of vector particles (photons). It is explicitly shown, with the Hamiltonian formalism, that the theory of an electromagnetic field on d-dimensional spherical black holes reduces to one of an infinite number of massive complex scalar fields on 2-dimensional spacetime, for which the usual anomaly-cancellation method is available. It is found that the total energy emitted from the horizon for the electromagnetic field is just (d-2) times that for a scalar field. The results support the picture that Hawking radiation can be regarded as an anomaly eliminator on horizons. Possible extensions and applications of the analysis are discussed
Physics for radiation protection
Martin, James E
2013-01-01
A much-needed working resource for health physicists and other radiation protection professionals, this volume presents clear, thorough, up-to-date explanations of the basic physics necessary to address real-world problems in radiation protection. Designed for readers with limited as well as basic science backgrounds, Physics for Radiation Protection emphasizes applied concepts and carefully illustrates all topics through examples as well as practice problems. Physics for Radiation Protection draws substantially on current resource data available for health physics use, providing decay schemes and emission energies for approximately 100 of the most common radionuclides encountered by practitioners. Excerpts of the Chart of the Nuclides, activation cross sections, fission yields, fission-product chains, photon attenuation coefficients, and nuclear masses are also provided.
Directional radiative cooling thermal compensation for gravitational wave interferometer mirrors
Energy Technology Data Exchange (ETDEWEB)
Justin Kamp, Carl [Department of Chemical Reaction Engineering, Chalmers University of Technology, SE-412 96 Goteborg (Sweden)], E-mail: carl.kamp@chalmers.se; Kawamura, Hinata [Yokoyama Junior High School, Sanda, Hachioji, Tokyo 193-0832 (Japan); Passaquieti, Roberto [Dipartimento di Fisica ' Enrico Fermi' and INFN Sezione di Pisa, Universita' di Pisa, Largo Bruno Pontecorvo, I-56127 Pisa (Italy); DeSalvo, Riccardo [LIGO Observatories, California Institute of Technology, Pasadena, CA 91125 (United States)
2009-08-21
The concept of utilizing directional radiative cooling to correct the problem of thermal lensing in the mirrors of the LIGO/VIRGO gravitational wave detectors has been shown and has prospects for future use. Two different designs utilizing this concept, referred to as the baffled and parabolic mirror solutions, have been proposed with different means of controlling the cooling power. The technique takes advantage of the power naturally radiated by the mirror surfaces at room temperature to prevent their heating by the powerful stored laser beams. The baffled solution has been simulated via COMSOL Multiphysics as a design tool. Finally, the parabolic mirror concept was experimentally validated with the results falling in close agreement with theoretical cooling calculations. The technique of directional radiative thermal correction can be reversed to image heat rings on the mirrors periphery to remotely and dynamically correct their radius of curvature without subjecting the mirror to relevant perturbations.
Outline of a classical theory of quantum physics and gravitation
International Nuclear Information System (INIS)
Gallop, J.W.
1975-01-01
It is argued that in the manner in which the Galilean-Newtonian physics may be said to have explained the Ptolemaic-Copernican theories in terms which have since been called classical, so also Milner's theories of the structure of matter may be said to explain present day quantum and relativistic theory. In both cases the former employ the concept of force and the latter, by contrast, are geometrical theories. Milner envisaged space as being stressed, whereas Einstein thought of it as strained. Development of Milner's theory from criticisms and suggestions made by Kilmister has taken it further into the realms of quantum and gravitational physics, where it is found to give a more physically comprehensible explanation of the phenomena. Further, it shows why present day quantum theory is cast in a statistical form. The theory is supported by many predictions such as the ratio of Planck's constant to the mass of the electron, the value of the fine structure constant and reason for apparent variations in past measurements, the magnetic moment of the electron and proton of the stable particles such as the neutron Λ and Σ together with the kaon, and a relation between the universal gravitational constant and Hubble's constant - all within published experimental accuracy. The latest results to be accounted for by the theory are the masses of the newly discovered psi particles and confirmation of the value of the decay of Newton's gravitational constant obtained from lunar measurements. (author)
Gravitational radiation from stellar collapse: The initial burst
International Nuclear Information System (INIS)
Shapiro, S.L.
1977-01-01
The burst of gravitational radiation emitted during the initial collapse and rebound of a homogeneous, uniformly rotating spheroid with internal pressure is analyzed numerically. The surface of the collapsing spheroid is assumed to start at rest from infinity with negligible eccentricity (''zero-energy collapse''). The adopted internal pressure function is constant on self-similar spheroidal surfaces, and its central value is described by a polytropic law with index n< or =3. The Newtonian equations of motion are integrated numerically to follow the initial collapse and rebound of the configuration for the special case in which the collapse is time-reversal invariant about the moment of maximum compression, and the total energy and frequency spectrum of the emitted quadrupole radiation are computed. The results are employed to estimate the (approx.minimum) total energy and frequency distribution of the initial burst of gravitational radiation emitted during the formation of low-mass (Mapproximately-less-thanM/sub sun/) neutron stars and during the collapse of supermassive gas clouds
Gravitational Collapse of Radiating Dyon Solution and Cosmic Censorship Hypothesis
International Nuclear Information System (INIS)
Patil, K. D.; Zade, S. S.; Mohod, A. N.
2008-01-01
We investigate the possibility of cosmic censorship violation in the gravitational collapse of radiating dyon solution. It is shown that the final outcome of the collapse depends sensitively on the electric and magnetic charge parameters. The graphs of the outer apparent horizon, inner Cauchy horizon for different values of parameters are drawn. It is found that the electric and magnetic components push the apparent horizon towards the retarded time-coordinate axis, which in turn reduces the radius of the apparent horizon in Vaidya spacetime. Also, we extend the earlier work of Chamorro and Virbhadra [Pramana, J. Phys. 45 (1995) 181
Physical effects in gravitational field of black holes
International Nuclear Information System (INIS)
Frolov, V.P.
1986-01-01
A large number of problems related to peculiarities of physical processes in a strong gravitational field of black holes has been considered. Energy shift and the complete structure of physical fields for charged sources near a black hole have been investigated. Density matrix and generating functional for quantum effects in stationary black holes have been calculated. Contributions of massless and massive fields to vacuum polarization in black holes have been investigated and influence of quantum effects on the global structure of a black hole has been discussed
Where Does the Physics of Extreme Gravitational Collapse Reside?
Directory of Open Access Journals (Sweden)
Carlos Barceló
2016-05-01
Full Text Available The gravitational collapse of massive stars serves to manifest the most severe deviations of general relativity with respect to Newtonian gravity: the formation of horizons and spacetime singularities. Both features have proven to be catalysts of deep physical developments, especially when combined with the principles of quantum mechanics. Nonetheless, it is seldom remarked that it is hardly possible to combine all these developments into a unified theoretical model, while maintaining reasonable prospects for the independent experimental corroboration of its different parts. In this paper we review the current theoretical understanding of the physics of gravitational collapse in order to highlight this tension, stating the position that the standard view on evaporating black holes stands for. This serves as the motivation for the discussion of a recent proposal that offers the opposite perspective, represented by a set of geometries that regularize the classical singular behavior and present modifications of the near-horizon Schwarzschild geometry as the result of the propagation of non-perturbative ultraviolet effects originated in regions of high curvature. We present an extensive exploration of the necessary steps on the explicit construction of these geometries, and discuss how this proposal could change our present understanding of astrophysical black holes and even offer the possibility of detecting genuine ultraviolet effects in gravitational-wave experiments.
Two-time physics with gravitational and gauge field backgrounds
International Nuclear Information System (INIS)
Bars, Itzhak
2000-01-01
It is shown that all possible gravitational, gauge and other interactions experienced by particles in ordinary d dimensions (one time) can be described in the language of two-time physics in a spacetime with d+2 dimensions. This is obtained by generalizing the world line formulation of two-time physics by including background fields. A given two-time model, with a fixed set of background fields, can be gauged fixed from d+2 dimensions to (d-1)+1 dimensions to produce diverse one-time dynamical models, all of which are dually related to each other under the underlying gauge symmetry of the unified two-time theory. To satisfy the gauge symmetry of the two-time theory the background fields must obey certain coupled differential equations that are generally covariant and gauge invariant in the target (d+2)-dimensional spacetime. The gravitational background obeys a closed homothety condition while the gauge field obeys a differential equation that generalizes a similar equation derived by Dirac in 1936. Explicit solutions to these coupled equations show that the usual gravitational, gauge, and other interactions in d dimensions may be viewed as embedded in the higher (d+2)-dimensional space, thus displaying higher spacetime symmetries that otherwise remain hidden
1st Karl Schwarzschild Meeting on Gravitational Physics
Kaminski, Matthias; Mureika, Jonas; Bleicher, Marcus
2016-01-01
These proceedings collect the selected contributions of participants of the First Karl Schwarzschild Meeting on Gravitational Physics, held in Frankfurt, Germany to celebrate the 140th anniversary of Schwarzschild's birth. They are grouped into 4 main themes: I. The Life and Work of Karl Schwarzschild; II. Black Holes in Classical General Relativity, Numerical Relativity, Astrophysics, Cosmology, and Alternative Theories of Gravity; III. Black Holes in Quantum Gravity and String Theory; IV. Other Topics in Contemporary Gravitation. Inspired by the foundational principle ``By acknowledging the past, we open a route to the future", the week-long meeting, envisioned as a forum for exchange between scientists from all locations and levels of education, drew participants from 15 countries across 4 continents. In addition to plenary talks from leading researchers, a special focus on young talent was provided, a feature underlined by the Springer Prize for the best student and junior presentations.
Radiation physics for medical physicists
Podgorsak, Ervin B
2016-01-01
This textbook summarizes the basic knowledge of atomic, nuclear, and radiation physics that professionals working in medical physics and biomedical engineering need for efficient and safe use of ionizing radiation in medicine. Concentrating on the underlying principles of radiation physics, the textbook covers the prerequisite knowledge for medical physics courses on the graduate and post-graduate levels in radiotherapy physics, radiation dosimetry, imaging physics, and health physics, thus providing the link between elementary undergraduate physics and the intricacies of four medical physics specialties: diagnostic radiology physics, nuclear medicine physics, radiation oncology physics, and health physics. To recognize the importance of radiation dosimetry to medical physics three new chapters have been added to the 14 chapters of the previous edition. Chapter 15 provides a general introduction to radiation dosimetry. Chapter 16 deals with absolute radiation dosimetry systems that establish absorbed dose or ...
1995-01-01
The aim of this book is to provide a uniquely comprehensive source of information on the entire field of radiation therapy physics. The very significant advances in imaging, computational, and accelerator technologies receive full consideration, as do such topics as the dosimetry of radiolabeled antibodies and dose calculation models. The scope of the book and the expertise of the authors make it essential reading for interested physicians and physicists and for radiation dosimetrists.
Accelerator and radiation physics
Basu, Samita; Nandy, Maitreyee
2013-01-01
"Accelerator and radiation physics" encompasses radiation shielding design and strategies for hadron therapy accelerators, neutron facilities and laser based accelerators. A fascinating article describes detailed transport theory and its application to radiation transport. Detailed information on planning and design of a very high energy proton accelerator can be obtained from the article on radiological safety of J-PARC. Besides safety for proton accelerators, the book provides information on radiological safety issues for electron synchrotron and prevention and preparedness for radiological emergencies. Different methods for neutron dosimetry including LET based monitoring, time of flight spectrometry, track detectors are documented alongwith newly measured experimental data on radiation interaction with dyes, polymers, bones and other materials. Design of deuteron accelerator, shielding in beam line hutches in synchrotron and 14 MeV neutron generator, various radiation detection methods, their characteriza...
Effect of a gravitational wave on electromagnetic radiation confined in a cavity
International Nuclear Information System (INIS)
Tourrenc, P.
1978-01-01
Gravitational radiation is considered within the first-order approximation. A pattern of an electromagnetic cavity is studied: Gravitational waves give rise to a deformation of the planes limiting the cavity. This deformation alters the electromagnetic radiation. Several cases are studied and orders of magnitude are put forward. (author)
Gravitational radiation in relativistic theory of gravity with a nonzero graviton mass
International Nuclear Information System (INIS)
Vlasov, A.A.; Chugreev, Yu.V.
1987-01-01
Radiation of gravitation waves have been analysed in the linear approximation of the relative theory of gravity, with the mass of graviton being nonzero. It is shown that the main contribution to the energy loss due to gravitational radiation has been described by the well-known quadrupole formula. Linear approximation applicability conditions have been analysed
Gravitational Radiation from Post-Newtonian Sources and Inspiralling Compact Binaries
Directory of Open Access Journals (Sweden)
Blanchet Luc
2006-06-01
Full Text Available The article reviews the current status of a theoretical approach to the problem of the emission of gravitational waves by isolated systems in the context of general relativity. Part A of the article deals with general post-Newtonian sources. The exterior field of the source is investigated by means of a combination of analytic post-Minkowskian and multipolar approximations. The physical observables in the far-zone of the source are described by a specific set of radiative multipole moments. By matching the exterior solution to the metric of the post-Newtonian source in the near-zone we obtain the explicit expressions of the source multipole moments. The relationships between the radiative and source moments involve many non-linear multipole interactions, among them those associated with the tails (and tails-of-tails of gravitational waves. Part B of the article is devoted to the application to compact binary systems. We present the equations of binary motion, and the associated Lagrangian and Hamiltonian, at the third post-Newtonian (3PN order beyond the Newtonian acceleration. The gravitational-wave energy flux, taking consistently into account the relativistic corrections in the binary moments as well as the various tail effects, is derived through 3.5PN order with respect to the quadrupole formalism. The binary's orbital phase, whose prior knowledge is crucial for searching and analyzing the signals from inspiralling compact binaries, is deduced from an energy balance argument.
Basic ionizing physic radiation
International Nuclear Information System (INIS)
Abdul Nassir Ibrahim; Azali Muhammad; Ab. Razak Hamzah; Abd. Aziz Mohamed; Mohamad Pauzi Ismail
2008-01-01
To become an expert in this field, radiographer must first master in radiation physics. That why the second chapter discussed on radiation physic. The topic that must covered such as atom and molecule, atomic structure, proton, isotope, half life, types of radiation and some basic formula such as formula for shielding, half life, half value layer, tenth value layer and more. All of this must be mastered by radiographer if they want to know more detail on this technique because this technique was a combination of theory and practical. Once they failed the theory they cannot go further on this technique. And to master this technique, once cannot depend on theory only. So, for this technique theory and practical must walk together.
The notions of mass in gravitational and particle physics
Castellani, Gianluca
It is presently thought that the mass of all of the elementary particles is determined by the Higgs field. This scalar field couples directly into the trace of the energy momentum tensor of the elementary particles. The attraction between two or more masses arises from the exchange of gravitational quantum particles of spin 2, called gravitons. The gravitational field couples directly into the energy momentum tensor. Then there is a close connection between the Higgs field, that originates the mass, and the gravitational field that dictates how the masses interact. Our purpose in this thesis is to discuss this close connection in terms of fundamental definitions of inertial and gravitational masses. On a practical level we explore two properties of mass from the viewpoint of coupling into the Higgs field: (i) The coupling of the both the Higgs and gravity to the energy-pressure tensor allows for the decay of the Higgs particle into two gravitons. We use the self energy part of the Higgs propagator to calculate the electromagnetic, weak, fermionic and gravitational decay rate of the Higgs particle. We show that the former process appears to dominate the other decay modes. Since the gravitons are detectable with virtually zero probability, the number of Higgs particles with observable decay products will be much less than previously expected. (ii) Some new experimental results seem to indicate that the mass of the heavy elementary particles like the Z,W+,W- and especially the top quark, depends on the particle environment in which these particles are produced. The presence of a Higgs field due to neighboring particles could be responsible for induced mass shifts. Further measurements of mass shift effects might give an indirect proof of the Higgs particle. Such can be in principle done by re-analyzing some of the production data e +e- → ZZ (or W+W-) already collected at the LEP experiment. About the physical property of the top quark, it is too early to arrive at
Secular instability of axisymmetric rotating stars to gravitational radiation reaction
International Nuclear Information System (INIS)
Managan, R.A.
1985-01-01
A generalization of the Eulerian variational principle derived by Ipser and Managan, for nonaxisymmetric neutral modes of axisymmetric fluid configurations, is developed. The principle provides a variational basis for calculating the frequencies of nonaxisymmetric normal modes proportional to e/sup i/(sigmat + mphi). A modified form of this principle, valid for sigma near 0, is also developed. The latter principle is used to locate the points where the frequency of a nonaxisymmetric normal mode of an axisymmetric rotating fluid configuration passes through zero. lt is at these points that the configuration becomes secularly unstable to gravitational radiation reaction (GRR). This is demonstrated directly by including the GRR potential and showing that the imaginary part of sigma passes through zero and becomes negative at these points. The imaginary part of the frequency is used to estimate the e-folding time of the mode. This variational principle is applied to sequences of rotating polytropes. The sequences are constructed using four rotation laws at each value of the polytropic index n = 0.5, 1.0, 1.5, 2.0, and 3.0. The values of (T/W)/sub m/, the ratio of the rotational kinetic energy to the magnitude of the gravitational potential energy at the onset of instability, and timescales for the modes with m = 2, 3, and 4 are estimated for each sequence. The value of (T/W) 2 is largely independent of the equation of state and rotation law. For m > 2, (T/W)/sub m/ decreases as the equation of state becomes softer, i.e., as the polytropic index n increases, and increases as the amount of differential rotation increases. The most striking result of this behavior occurs for uniform rotation
Reflections on the information paradigm in quantum and gravitational physics
Andres Höhn, Philipp
2017-08-01
We reflect on the information paradigm in quantum and gravitational physics and on how it may assist us in approaching quantum gravity. We begin by arguing, using a reconstruction of its formalism, that quantum theory can be regarded as a universal framework governing an observer’s acquisition of information from physical systems taken as information carriers. We continue by observing that the structure of spacetime is encoded in the communication relations among observers and more generally the information flow in spacetime. Combining these insights with an information-theoretic Machian view, we argue that the quantum architecture of spacetime can operationally be viewed as a locally finite network of degrees of freedom exchanging information. An advantage - and simultaneous limitation - of an informational perspective is its quasi-universality, i.e. quasi-independence of the precise physical incarnation of the underlying degrees of freedom. This suggests to exploit these informational insights to develop a largely microphysics independent top-down approach to quantum gravity to complement extant bottom-up approaches by closing the scale gap between the unknown Planck scale physics and the familiar physics of quantum (field) theory and general relativity systematically from two sides. While some ideas have been pronounced before in similar guise and others are speculative, the way they are strung together and justified is new and supports approaches attempting to derive emergent spacetime structures from correlations of quantum degrees of freedom.
International Nuclear Information System (INIS)
Fennelly, A.J.
1978-01-01
Investigations of several problems of gravitation are discussed. The question of the existence of black holes is considered. While black holes like those in Einstein's theory may not exist in other gravity theories, trapped surfaces implying such black holes certainly do. The theories include those of Brans-Dicke, Lightman-Lee, Rosen, and Yang. A similar two-tensor theory of Yilmaz is investigated and found inconsistent and nonviable. The Newman-Penrose formalism for Riemannian geometries is adapted to general gravity theories and used to implement a search for twisting solutions of the gravity theories for empty and nonempty spaces. The method can be used to find the gravitational fields for all viable gravity theories. The rotating solutions are of particular importance for strong field interpretation of the Stanford/Marshall gyroscope experiment. Inhomogeneous cosmologies are examined in Einstein's theory as generalizations of homogeneous ones by raising the dimension of the invariance groups by one more parameter. The nine Bianchi classifications are extended to Rosen's theory of gravity for homogeneous cosmological models
The space-time outside a source of gravitational radiation: the axially symmetric null fluid
Energy Technology Data Exchange (ETDEWEB)
Herrera, L. [Universidad Central de Venezuela, Escuela de Fisica, Facultad de Ciencias, Caracas (Venezuela, Bolivarian Republic of); Universidad de Salamanca, Instituto Universitario de Fisica Fundamental y Matematicas, Salamanca (Spain); Di Prisco, A. [Universidad Central de Venezuela, Escuela de Fisica, Facultad de Ciencias, Caracas (Venezuela, Bolivarian Republic of); Ospino, J. [Universidad de Salamanca, Departamento de Matematica Aplicada and Instituto Universitario de Fisica Fundamental y Matematicas, Salamanca (Spain)
2016-11-15
We carry out a study of the exterior of an axially and reflection symmetric source of gravitational radiation. The exterior of such a source is filled with a null fluid produced by the dissipative processes inherent to the emission of gravitational radiation, thereby representing a generalization of the Vaidya metric for axially and reflection symmetric space-times. The role of the vorticity, and its relationship with the presence of gravitational radiation is put in evidence. The spherically symmetric case (Vaidya) is, asymptotically, recovered within the context of the 1 + 3 formalism. (orig.)
Electric Dipole Antenna: A Source of Gravitational Radiation
Directory of Open Access Journals (Sweden)
Chifu E. N.
2013-07-01
Full Text Available In this article, the gravitational scalar potential due to an oscillating electric dipole antenna placed in empty space is derived. The gravitational potential obtained propagates as a wave. The gravitational waves have phase velocity equal to the speed of light in vacuum (c at the equatorial plane of the electric dipole antenna, unlike electromagnetic waves from the dipole antenna that cancel out at the equatorial plane due to charge symmetry.
The physics of radiation protection
International Nuclear Information System (INIS)
Doerschel, B.; Schuricht, V.; Steuer, J.
1996-01-01
The book is aimed at both practising specialists and scientists wishing to learn about the fundamental science of radiation protection. The first part of the book, 'Physical Fundamentals of Radiation Protection', presents a concise description of radiation sources and radiation fields, interaction of radiation with matter, radiation effects and radiation damage, basic concept of radiation protection, radiation exposure of man, radiation protection measuring techniques and physical fundamentals for limiting radiation exposure. The second part, 'Calculational Exercises for Radiation Protection' is intended to supplement the first part by carrying out relevant calculations, amending and adding special aspects and to give guidance in solving practical problems. The book is written for scientists as well as for students and staff working in nuclear facilities, hospitals and institutions responsible for radiation and environmental protection. (UK)
Radiation physics for medical physicists
Podgorsak, Ervin B
2006-01-01
This book summarizes the radiation physics knowledge that professionals working in medical physics need to master for efficient and safe dealings with ionizing radiation. It contains eight chapters, each chapter covering a specific group of subjects related to radiation physics and is intended as a textbook for a course in radiation physics in medical-physics graduate programs. However, the book may also be of interest to the large number of professionals, not only medical physicists, who in their daily occupations deal with various aspects of medical physics and find a need to improve their understanding of radiation physics. The main target audience for this book is graduate students studying for M.Sc. and Ph.D. degrees in medical physics, who have to possess the necessary physics and mathematics background knowledge to be able to follow and master the complete textbook. Medical residents, technology students and biomedical engineering students may find certain sections too challenging or esoteric, yet they...
Mashhoon, B.
1982-01-01
The influence of a stochastic and isotropic background of gravitational radiation on timing measurements of pulsars is investigated, and it is shown that pulsar timing noise may be used to establish a significant upper limit of about 10 to the -10th on the total energy density of very long-wavelength stochastic gravitational waves. This places restriction on the strength of very long wavelength gravitational waves in the Friedmann model, and such a background is expected to have no significant effect on the approximately 3 K electromagnetic background radiation or on the dynamics of a cluster of galaxies.
A Physical Model of Pulsars as Gravitational Shielding and Oscillating Neutron Stars
Directory of Open Access Journals (Sweden)
Zhang T. X.
2015-04-01
Full Text Available Pulsars are thought to be fast rotating neutron stars, synchronously emitting periodic Dirac-delta-shape radio-frequency pulses and Lorentzian-shape oscillating X-rays. The acceleration of charged particles along the magnetic field lines of neutron stars above the magnetic poles that deviate from the rotating axis initiates coherent beams of ra- dio emissions, which are viewed as pulses of radiation whenever the magnetic poles sweep the viewers. However, the conventional lighthouse model of pulsars is only con- ceptual. The mechanism through which particles are accelerated to produce coherent beams is still not fully understood. The process for periodically oscillating X-rays to emit from hot spots at the inner edge of accretion disks remains a mystery. In addition, a lack of reflecting X-rays of the pulsar by the Crab Nebula in the OFF phase does not support the lighthouse model as expected. In this study, we develop a physical model of pulsars to quantitatively interpret the emission characteristics of pulsars, in accor- dance with the author’s well-developed five-dimensional fully covariant Kaluza-Klein gravitational shielding theory and the physics of thermal and accelerating charged par- ticle radiation. The results obtained from this study indicate that, with the significant gravitational shielding by scalar field, a neutron star nonlinearly oscillates and produces synchronous periodically Dirac-delta-shape radio-frequency pulses (emitted by the os- cillating or accelerating charged particles as well as periodically Lorentzian-shape os- cillating X-rays (as the thermal radiation of neutron stars whose temperature varies due to the oscillation. This physical model of pulsars broadens our understanding of neu- tron stars and develops an innovative mechanism to model the emissions of pulsars.
Modern Gravitational Lens Cosmology for Introductory Physics and Astronomy Students
Huwe, Paul; Field, Scott
2015-01-01
Recent and exciting discoveries in astronomy and cosmology have inspired many high school students to learn about these fields. A particularly fascinating consequence of general relativity at the forefront of modern cosmology research is gravitational lensing, the bending of light rays that pass near massive objects. Gravitational lensing enables…
Electromagnetic signatures of far-field gravitational radiation in the 1 + 3 approach
International Nuclear Information System (INIS)
Chua, Alvin J K; Cañizares, Priscilla; Gair, Jonathan R
2015-01-01
Gravitational waves (GWs) from astrophysical sources can interact with background electromagnetic fields, giving rise to distinctive and potentially detectable electromagnetic signatures. In this paper, we study such interactions for far-field gravitational radiation using the 1 + 3 approach to relativity. Linearized equations for the electromagnetic field on perturbed Minkowski space are derived and solved analytically. The inverse Gertsenshteĭn conversion of GWs in a static electromagnetic field is rederived, and the resultant electromagnetic radiation is shown to be significant for highly magnetized pulsars in compact binary systems. We also obtain a variety of nonlinear interference effects for interacting gravitational and electromagnetic waves, although wave–wave resonances previously described in the literature are absent when the electric–magnetic self-interaction is taken into account. The fluctuation and amplification of electromagnetic energy flux as the GW strength increases towards the gravitational–electromagnetic frequency ratio is a possible signature of gravitational radiation from extended astrophysical sources. (paper)
Radiation Physics for Medical Physicists
Podgorsak, Ervin B
2010-01-01
This well-received textbook and reference summarizes the basic knowledge of atomic, nuclear, and radiation physics that professionals working in medical physics and biomedical engineering need for efficient and safe use of ionizing radiation. Concentrating on the underlying principles of radiation physics, it covers the prerequisite knowledge for medical physics courses on the graduate and post-graduate levels in radiotherapy physics, radiation dosimetry, imaging physics, and health physics, thus providing the link between elementary physics on the one hand and the intricacies of the medical physics specialties on the other hand. This expanded and revised second edition offers reorganized and expanded coverage. Several of the original chapters have been split into two with new sections added for completeness and better flow. New chapters on Coulomb scattering; on energy transfer and energy absorption in photon interactions; and on waveguide theory have been added in recognition of their importance. Others tra...
The black hole symphony: probing new physics using gravitational waves.
Gair, Jonathan R
2008-12-13
The next decade will very likely see the birth of a new field of astronomy as we become able to directly detect gravitational waves (GWs) for the first time. The existence of GWs is one of the key predictions of Einstein's theory of general relativity, but they have eluded direct detection for the last century. This will change thanks to a new generation of laser interferometers that are already in operation or which are planned for the near future. GW observations will allow us to probe some of the most exotic and energetic events in the Universe, the mergers of black holes. We will obtain information about the systems to a precision unprecedented in astronomy, and this will revolutionize our understanding of compact astrophysical systems. Moreover, if any of the assumptions of relativity theory are incorrect, this will lead to subtle, but potentially detectable, differences in the emitted GWs. Our observations will thus provide very precise verifications of the theory in an as yet untested regime. In this paper, I will discuss what GW observations could tell us about known and (potentially) unknown physics.
International Nuclear Information System (INIS)
Abd Nasir Ibrahim; Azali Muhammad; Ab Razak Hamzah; Abd Aziz Mohamed; Mohammad Pauzi Ismail
2004-01-01
This chapter discusses the following topics: concept of atom and elements; molecules and compounds; basic principles of radiation; types of radiations; radioactivity, unit of radioactivity, specific activity, radioactive decay, ionisation and ions, interaction of radiation with matters, modes of interaction: photoelectric absorption: Compton scattering, pair-production; attenuation of x and gamma radiation; build-up factors
Radiation tails of the scalar wave equation in a weak gravitational field
International Nuclear Information System (INIS)
Mankin, R.; Piir, I.
1974-01-01
A class of solutions of the linearized Einstein equations is found making use of the Newman-Penrose spin coefficient formalism. These solutions describe a weak retarded gravitational field with an arbitrary multipole structure. The study of the radial propagation of the scalar waves in this gravitational field shows that in the first approximation the tails of the scalar outgoing radiation appear either in the presence of a gravitational mass or in the case of a nonzero linear momentum of the gravitational source. The quadrupole moment and the higher multipole moments of the gravitational field as well as the constant dipole moment and the angular moment of the source do not contribute to the tail
2005-01-01
UNIVERSITE DE GENEVE ECOLE DE PHYSIQUE Département de physique nucléaire et corspusculaire 24, Quai Ernest-Ansermet - 1211 GENEVE 4 Tél : (022) 379 62 73 Fax: (022) 379 69 92 Wednesday 11 May PARTICLE PHYSICS SEMINAR at 17:00 - Stückelberg Auditorium The search for gravitational waves. Physical motivations and experimental perspectives by Prof. Michele Maggiore / DPT-UniGe I will give an overview of gravitational-wave physics, addressing two main questions: What are the physical motivations for gravitational-wave research, both from the point of view of astrophysics and of high-energy physics. Present status and future perspectives of gravitational-wave experiments. Information: http://dpnc.unige.ch/seminaire/annonce.html Organizer: A. Cervera Villanueva
Precessing Black Hole Binaries and Their Gravitational Radiation
Directory of Open Access Journals (Sweden)
László Á. Gergely
2018-02-01
Full Text Available The first and second observational runs of Advanced Laser Interferometer Gravitational-wave Observatory (LIGO have marked the first direct detections of gravitational waves, either from black hole binaries or, in one case, from coalescing neutron stars. These observations opened up the era of gravitational wave astronomy, but also of gravitational wave cosmology, in the form of an independent derivation of the Hubble constant. They were equally important to prove false a plethora of modified gravity theories predicting gravitational wave propagation speed different from that of light. For a continued and improved testing of general relativity, the precise description of compact binary dynamics, not only in the final coalescence phase but also earlier, when precessional effects dominate, are required. We report on the derivation of the full secular dynamics for compact binaries, valid over the precessional time-scale, in the form of an autonomous closed system of differential equations for the set of spin angles and periastron. The system can be applied for mapping the parameter space for the occurrence of the spin flip-flop effect and for more accurately analyzing the spin-flip effect, which could explain the formation of X-shaped radio galaxies.
Prasanna, A R
2017-01-01
This book suitable for post graduates in Physics and Astrophysics aims at introducing the theory of general relativity as an important background for doing astrophysics. Starting from a detailed discussion of the various mathematical concepts for doing general relativity, the book introduces the geometric description of gravity. It gives a brief historical perspective to classical mechanics and electrodynamics making an attempt to establish the necessity of special relativity as propounded by Einstein extending to General Relativity. This book is a good starting point for post graduates wanting to pursue the modern topics of Cosmology, High energy astrophysics and related areas.
Final result of the Munich-Frascati gravitational radiation experiment
International Nuclear Information System (INIS)
Kafka, P.; Schnupp, L.
1977-02-01
Within 580 days of usable common observation time between July 1973 and February 1976, this Weber-type coincidence experiment had set the lowest upper limits to the rates of gravitational wave pulses. We report the total result up to the dismantling of the detectors. We also describe a reevaluation of our data using Weber's preferred algorithm for two months in 1974 during which Weber communicated to have found a particularly significant effect in his own experiment. Finally, we confront the negative results with the far aims of gravitational pulse astronomy. (orig.) [de
Final result of the Munich-Frascati gravitational radiation experiment
International Nuclear Information System (INIS)
Kafka, P.; Schnupp, L.
1978-01-01
Within 580 days of usable common observation time between July 1973 and February 1976, this Weber-type coincidence experiment had set the lowest upper limits to the rates of gravitational wave pulses. We report the total result up to the dismantling of the detectors. We also describe a re-evaluation of our data using Weber's preferred algorithm for two months in 1974 during which Weber communicated to have found a particularly significant effect in his own experiment. Finally, we confront the negative results with the far aims of gravitational pulse astronomy. (orig.) [de
On the propagation problem in gravitational radiation theory
International Nuclear Information System (INIS)
Damour, T.
1986-01-01
The authors emphasize that a suitable combination of analytical and numerical methods might be useful to overcome the limitations of both methods. In particular, analytical methods are needed, on the one hand to provide boundary conditions to numerical codes, and on the other hand to relate the gravitational field at the outer edge of the grid with the asymptotic outgoing wave form. The authors present an explicit formula which solves approximately the latter ''propagation problem'' in a simplified situation which might be relevant to the problem of computing the gravitational wave form emitted during the three-dimensional collapse of a star
Is Hawking radiation physically reasonable?
International Nuclear Information System (INIS)
Ahmed, M.
1995-07-01
Hawking radiation is observed in a general spacetime which includes all the black hole spacetimes as well as various types of other spacetimes which are not interesting form the physical point of view like black hole spacetimes. Even Hawking radiation is observed in NUT spacetime which is sometimes considered as unphysical. So naturally arises the question whether Hawking radiation is physically reasonable. (author). 22 refs
Sub-Microarcsecond Astrometry and New Horizons in Relativistic Gravitational Physics
National Research Council Canada - National Science Library
Kopeikin, Sergei M; Gwinn, Carl R
2000-01-01
.... Beyond the sub-microarcsecond threshold, one will meet in the sky a new population of physical phenomena caused by primordial gravitational waves from the early universe and/or different localized...
International Nuclear Information System (INIS)
Mashhoon, B.; Grishchuk, L.P.
1980-01-01
The possibility of detection of an isotropic background gravitational radiation of a stochastic nature by the method of Doppler tracking of spacecraft is considered. In the geometrical optics limit, the general formula for the frequency shift of an electromagnetic signal in the gravitational radiation field is discussed, and it is shown to be gauge (or rather Lie) independent. A detailed examination of the propagation of a free electromagnetic wave in a gravitational radiation field shows that no resonance phenomena can be expected. Thus, the results valid in the geometrical optics limit are also approximately valid for any gravitational radiation spectrum dominated by wavelengths large compared to that of the electromagnetic signal. The ''Doppler noise'' due to a stochastic background is evaluated, and it is shown to depend on the total energy density of the background and a parameter that is a characteristic of the aradiation spectrum and the detection system used. A background gravitational radiation with an energy density comparable to the electromagnetic (approx.3 K) background and a spectrum dominated by wavelengths > or approx. =1 AU may be detectable in the near future by the Doppler tracking of interplanetary spacecraft
Radiation physics, biophysics, and radiation biology
International Nuclear Information System (INIS)
Hall, E.J.; Zaider, M.
1991-05-01
Research at the Radiological Research Laboratory is a blend of physics, chemistry, and biology, involving research at the basic level with the admixture of a small proportion of pragmatic or applied research in support of radiation protection and/or radiotherapy. Current research topics include: oncogenic transformation assays, mutation studies involving interactions between radiation and environmental contaminants, isolation, characterization and sequencing of a human repair gene, characterization of a dominant transforming gene found in C3H 10T1/2 cells, characterize ab initio the interaction of DNA and radiation, refine estimates of the radiation quality factor Q, a new mechanistic model of oncogenesis showing the role of long-term low dose medium LET radiation, and time dependent modeling of radiation induced chromosome damage and subsequent repair or misrepair
International Nuclear Information System (INIS)
Cardoso, Vitor; Lemos, Jose P.S.
2003-01-01
In this paper, we consider the gravitational radiation generated by the collision of highly relativistic particles with rotating Kerr black holes. We use the Sasaki-Nakamura formalism to compute the waveform, energy spectra, and total energy radiated during this process. We show that the gravitational spectrum for high-energy collisions has definite characteristic universal features, which are independent of the spin of the colliding objects. We also discuss the possible connections between these results and black-hole-black-hole collisions at the speed of light. Our results show that during the high-speed collision of a nonrotating hole with a rotating one, at most 35% of the total energy can get converted into gravitational waves. This 35% efficiency occurs only in the most optimistic situation, that of a zero impact parameter collision, along the equatorial plane, with an almost extreme Kerr black hole. In the general situation, the total gravitational energy radiated is expected to be much less, especially if the impact parameter increases. Thus, if one is able to produce black holes at the CERN Large Hadron Collider, at most 35% of the partons' energy should be emitted during the so-called balding phase. This energy will be missing, since we do not have gravitational wave detectors able to measure such amplitudes. The collision at the speed of light between one rotating black hole and a nonrotating one or two rotating black holes turns out to be the most efficient gravitational wave generator in the Universe
Trapped surfaces due to concentration of gravitational radiation
International Nuclear Information System (INIS)
Beig, R.; O Murchadha, N.
1991-01-01
Sequences of global, asympotically flat solutions to the time-symmetric initial value constraints of general relativity in vacuo are constructed which develop outer trapped surfaces for large values of the argument. Thus all such configurations must gravitationally collapse. A new proof of the positivity of mass in the strong-field regime is also found. (Authors) 22 refs
Spectral Cauchy characteristic extraction of strain, news and gravitational radiation flux
International Nuclear Information System (INIS)
Handmer, Casey J; Szilágyi, Béla; Winicour, Jeffrey
2016-01-01
We present a new approach for the Cauchy-characteristic extraction (CCE) of gravitational radiation strain, news function, and the flux of the energy–momentum, supermomentum and angular momentum associated with the Bondi–Metzner–Sachs asymptotic symmetries. In CCE, a characteristic evolution code takes numerical data on an inner worldtube supplied by a Cauchy evolution code, and propagates it outwards to obtain the space–time metric in a neighborhood of null infinity. The metric is first determined in a scrambled form in terms of coordinates determined by the Cauchy formalism. In prior treatments, the waveform is first extracted from this metric and then transformed into an asymptotic inertial coordinate system. This procedure provides the physically proper description of the waveform and the radiated energy but it does not generalize to determine the flux of angular momentum or supermomentum. Here we formulate and implement a new approach which transforms the full metric into an asymptotic inertial frame and provides a uniform treatment of all the radiation fluxes associated with the asymptotic symmetries. Computations are performed and calibrated using the spectral Einstein code. (paper)
Radiation physics for medical physicists
International Nuclear Information System (INIS)
Podgorsak, E.B.
2006-01-01
This book summarizes the radiation physics knowledge that professionals working in medical physics need to master for efficient and safe dealings with ionizing radiation. It contains eight chapters, each chapter covering a specific group of subjects related to radiation physics and is intended as a textbook for a course in radiation physics in medical-physics graduate programs. However, the book may also be of interest to the large number of professionals, not only medical physicists, who in their daily occupations deal with various aspects of medical physics and find a need to improve their understanding of radiation physics. The main target audience for this book is graduate students studying for M.Sc. and Ph.D. degrees in medical physics, who have to possess the necessary physics and mathematics background knowledge to be able to follow and master the complete textbook. Medical residents, technology students and biomedical engineering students may find certain sections too challenging or esoteric, yet they will find many sections interesting and useful in their studies. Candidates preparing for professional certification exams in any of the medical physics subspecialties should find the material useful, and some of the material would also help candidates preparing for certification examinations in medical dosimetry or radiation-related medical specialties. Numerous textbooks are available covering the various subspecialties of medical physics but they generally make a transition from the elementary basic physics directly into the intricacies of the given medical physics subspecialty. The intent of this textbook is to provide the missing link between the elementary physics on the one hand and the physics of the subspecialties on the other hand. (orig.)
The physics of radiation therapy
Khan, Faiz M
2009-01-01
Dr. Khan's classic textbook on radiation oncology physics is now in its thoroughly revised and updated Fourth Edition. It provides the entire radiation therapy team—radiation oncologists, medical physicists, dosimetrists, and radiation therapists—with a thorough understanding of the physics and practical clinical applications of advanced radiation therapy technologies, including 3D-CRT, stereotactic radiotherapy, HDR, IMRT, IGRT, and proton beam therapy. These technologies are discussed along with the physical concepts underlying treatment planning, treatment delivery, and dosimetry. This Fourth Edition includes brand-new chapters on image-guided radiation therapy (IGRT) and proton beam therapy. Other chapters have been revised to incorporate the most recent developments in the field. This edition also features more than 100 full-color illustrations throughout.
International Nuclear Information System (INIS)
Sagunski, Laura
2013-04-01
Relic gravitational waves, generated by strongly first-order phase transitions in the early Universe, can serve as cosmological probes for new physics beyond the Standard Model. We investigate phase transitions at temperatures between the electroweak and the GUT scale in two extensions of the Standard Model for their possibility to provide detectable gravitational radiation. First, we study the Z 2 symmetry breaking phase transition in the Standard model extended by a real gauge singlet. The analysis yields that the gravitational wave amplitude of the first-order phase transition with a thermally induced barrier is several orders too small for being detectable. The second model we discuss is a left-right symmetric model based on the gauge group SU(2) L x SU(2) R x U(1) B-L generating a first-order phase transition already due to the emergence of a barrier in the tree-level potential. We derive an upper bound on the peak amplitude of the gravitational wave spectrum of the order h o 2 Ω GW ≅ 3 . 10 -11 . Hence, for very strong phase transitions a detection with the spaceborne interferometer LISA will be possible, whereas the sensitivity of the (cross-correlated) BBO detector will even allow to observe the gravitational wave spectrum within the whole parameter range of the model. By using the correlation between the characteristic parameters α and β of the gravitational wave spectrum, we finally compute the lower bounds on α(T * ) in dependence of the tunneling temperature T * which are necessary for a detection of the model spectrum by the specific detectors.
Energy Technology Data Exchange (ETDEWEB)
Sagunski, Laura
2013-04-15
Relic gravitational waves, generated by strongly first-order phase transitions in the early Universe, can serve as cosmological probes for new physics beyond the Standard Model. We investigate phase transitions at temperatures between the electroweak and the GUT scale in two extensions of the Standard Model for their possibility to provide detectable gravitational radiation. First, we study the Z{sub 2} symmetry breaking phase transition in the Standard model extended by a real gauge singlet. The analysis yields that the gravitational wave amplitude of the first-order phase transition with a thermally induced barrier is several orders too small for being detectable. The second model we discuss is a left-right symmetric model based on the gauge group SU(2){sub L} x SU(2){sub R} x U(1){sub B-L} generating a first-order phase transition already due to the emergence of a barrier in the tree-level potential. We derive an upper bound on the peak amplitude of the gravitational wave spectrum of the order h{sub o}{sup 2}{Omega}{sub GW} {approx_equal} 3 . 10{sup -11}. Hence, for very strong phase transitions a detection with the spaceborne interferometer LISA will be possible, whereas the sensitivity of the (cross-correlated) BBO detector will even allow to observe the gravitational wave spectrum within the whole parameter range of the model. By using the correlation between the characteristic parameters {alpha} and {beta} of the gravitational wave spectrum, we finally compute the lower bounds on {alpha}(T{sub *}) in dependence of the tunneling temperature T{sub *} which are necessary for a detection of the model spectrum by the specific detectors.
Gravitational waves from inflation
International Nuclear Information System (INIS)
Guzzetti, M.C.; Bartolo, N.; Liguori, M.; Matarrese, S.
2016-01-01
The production of a stochastic background of gravitational waves is a fundamental prediction of any cosmological inflationary model. The features of such a signal encode unique information about the physics of the Early Universe and beyond, thus representing an exciting, powerful window on the origin and evolution of the Universe. We review the main mechanisms of gravitational-wave production, ranging from quantum fluctuations of the gravitational field to other mechanisms that can take place during or after inflation. These include e.g. gravitational waves generated as a consequence of extra particle production during inflation, or during the (p)reheating phase. Gravitational waves produced in inflation scenarios based on modified gravity theories and second-order gravitational waves are also considered. For each analyzed case, the expected power spectrum is given. We discuss the discriminating power among different models, associated with the validity/violation of the standard consistency relation between tensor-to-scalar ratio r and tensor spectral index ηT. In light of the prospects for (directly/indirectly) detecting primordial gravitational waves, we give the expected present-day gravitational radiation spectral energy-density, highlighting the main characteristics imprinted by the cosmic thermal history, and we outline the signatures left by gravitational waves on the Cosmic Microwave Background and some imprints in the Large-Scale Structure of the Universe. Finally, current bounds and prospects of detection for inflationary gravitational waves are summarized.
Gravitational Radiation from Post-Newtonian Sources and Inspiralling Compact Binaries
Directory of Open Access Journals (Sweden)
Luc Blanchet
2014-02-01
Full Text Available To be observed and analyzed by the network of gravitational wave detectors on ground (LIGO, VIRGO, etc. and by the future detectors in space (eLISA, etc., inspiralling compact binaries -- binary star systems composed of neutron stars and/or black holes in their late stage of evolution -- require high-accuracy templates predicted by general relativity theory. The gravitational waves emitted by these very relativistic systems can be accurately modelled using a high-order post-Newtonian gravitational wave generation formalism. In this article, we present the current state of the art on post-Newtonian methods as applied to the dynamics and gravitational radiation of general matter sources (including the radiation reaction back onto the source and inspiralling compact binaries. We describe the post-Newtonian equations of motion of compact binaries and the associated Lagrangian and Hamiltonian formalisms, paying attention to the self-field regularizations at work in the calculations. Several notions of innermost circular orbits are discussed. We estimate the accuracy of the post-Newtonian approximation and make a comparison with numerical computations of the gravitational self-force for compact binaries in the small mass ratio limit. The gravitational waveform and energy flux are obtained to high post-Newtonian order and the binary's orbital phase evolution is deduced from an energy balance argument. Some landmark results are given in the case of eccentric compact binaries -- moving on quasi-elliptical orbits with non-negligible eccentricity. The spins of the two black holes play an important role in the definition of the gravitational wave templates. We investigate their imprint on the equations of motion and gravitational wave phasing up to high post-Newtonian order (restricting to spin-orbit effects which are linear in spins, and analyze the post-Newtonian spin precession equations as well as the induced precession of the orbital plane.
Current trends in radiation physics
Energy Technology Data Exchange (ETDEWEB)
Gomaa, M A; Elbehay, A Z; Hassib, G M; Elnaggar, A M [eds.
1994-12-31
This conference details 11 papers, explain radiation physics. It discuss subjects of axial and spherical symmetry,accelerators,cyclotron laboratory and radon monitoring. contains figures,tables and data.
Current trends in radiation physics
International Nuclear Information System (INIS)
Gomaa, M.A.; Elbehay, A.Z.; Hassib, G.M.; Elnaggar, A.M.
1993-01-01
This conference details 11 papers, explain radiation physics. It discuss subjects of axial and spherical symmetry,accelerators,cyclotron laboratory and radon monitoring. contains figures,tables and data
Gravitational Physics: the birth of a new era
Sakellariadou, Mairi
2017-11-01
We live the golden age of cosmology, while the era of gravitational astronomy has finally begun. Still, fundamental puzzles remain. Standard cosmology is formulated within the framework of Einstein's General theory of Relativity. Notwithstanding, General Relativity is not adequate to explain the earliest stages of cosmic existence, and cannot provide an explanation for the Big Bang itself. Modern early universe cosmology is in need of a rigorous underpinning in Quantum Gravity.
(Almost) All You Need to Know About Gravitational Wave Physics
CERN. Geneva
2016-01-01
General Relativity, some of which have been taken for granted without observations: are gravitons massless? Are black holes the simplest possible macroscopic objects? do event horizons and black holes really exist, or is their formation halted by some as-yet unknown mechanism? In these lectures, we will describe the anatomy of a GW event, with particular emphasis on how to compute gravitational-waves from black hole systems and what kind of information such waves carry.
Radiation physics for nuclear medicine
Hoeschen, Christoph
2011-01-01
The field of nuclear medicine is expanding rapidly, with the development of exciting new diagnostic methods and treatments. This growth is closely associated with significant advances in radiation physics. In this book, acknowledged experts explain the basic principles of radiation physics in relation to nuclear medicine and examine important novel approaches in the field. The first section is devoted to what might be termed the "building blocks" of nuclear medicine, including the mechanisms of interaction between radiation and matter and Monte Carlo codes. In subsequent sections, radiation sources for medical applications, radiopharmaceutical development and production, and radiation detectors are discussed in detail. New frontiers are then explored, including improved algorithms for image reconstruction, biokinetic models, and voxel phantoms for internal dosimetry. Both trainees and experienced practitioners and researchers will find this book to be an invaluable source of up-to-date information.
International Nuclear Information System (INIS)
Barut, A.O.; Cruz, M.G.
1992-08-01
We use the method of analytic continuation of the equation of motion including the self-fields to evaluate the radiation reaction for a classical relativistic spinning point particle in interaction with scalar, tensor and linearized gravitational fields in flat spacetime. In the limit these equations reduce to those of spinless particles. We also show the renormalizability of these theories. (author). 10 refs
Food physics and radiation techniques
International Nuclear Information System (INIS)
Szabo, A. S.
1999-01-01
In the lecture information is given about food physics, which is a rather new, interdisciplinary field of science, connecting food science and applied physics. The topics of radioactivity of foodstuffs and radiation techniques in the food industry are important parts of food physics detailed information will be given about the main fields (e.g. radio stimulation, food preservation) of radiation techniques in the agro-food sector. Finally some special questions of radioactive contamination of foodstuffs in hungary and applicability of radioanalytical techniques (e.g. Inaa) for food investigation will be analyzed and discussed
Small-scale fluctuations in the microwave background radiation and multiple gravitational lensing
International Nuclear Information System (INIS)
Kashlinsky, A.
1988-01-01
It is shown that multiple gravitational lensing of the microwave background radiation (MBR) by static compact objects significantly attenuates small-scale fluctuations in the MBR. Gravitational lensing, by altering trajectories of MBR photons reaching an observer, leads to (phase) mixing of photons from regions with different initial fluctuations. As a result of this diffusion process the original fluctuations are damped on scales up to several arcmin. An equation that describes this process and its general solution are given. It is concluded that the present upper limits on the amplitude of the MBR fluctuations on small scales cannot constrain theories of galaxy formation. 25 references
Osmaston, Miles
2013-04-01
solar wind ions are evident in the negative H ions whose opacity is responsible for the solar photosphere 'surface' [11]. The Earth displays the same effect, with 90% of lightning strikes bringing negative charge to ground, and a concensus estimate of 250 kV between F-layer and ground. The earthquake precursor link. The conclusion offered in this presentation is that the precursory electron density-gradient change in the ionosphere is due to the build-up of elastic deformation of Earth's crust that changes the surface gravitational potential and the associated G-E field. So our caveat is that there will be no precursory sign in the ionosphere if the build-up of pre-seismic stress is by a dynamical mechanism that does not do that. On the other hand, this understanding should help to dispel doubts about interpreting a short-term ionospheric change as an earthquake precursor when one does appear over an active region. Other reasoning or measurements could then be concentrated on that location for guidance as to the kind of earthquake to be expected and its human severity. [1] Astafieva EI & Heki K (2007) Ionosphere Responses to Large Earthquakes of Different Focal Mechanisms: Case Study of 1994, 2006 and 2007 Kuril Islands Earthquakes. AGU Fall Mtg. Abstr. #S33B-1311. [2] Osmaston MF (2009) A two-stage scenario for forming the Sun's planetary system, with good links to exoplanet findings, arising from new physical insight on the graviational process. EPSC Abstracts 4, EPSC-2009.264. [3] Osmaston MF (2012) How stars grow massive despite radiation pressure, triggering star-bursts; insights from gravitation. UK-Germany NAM2012, Session ISM1: Interstellar medium and star formation. Http://www.jodrellbank.manchester.ac.uk/meetings/nam2012/sessions.html [4] Osmaston MF (2013) Implementing Maxwell's aether illuminates the physics of gravitation: the gravity-electric (G-E) field, evident at every scale, from the ionosphere to spiral galaxies and a neutron star extreme. In The
Semiconductor radiation detectors. Device physics
International Nuclear Information System (INIS)
Lutz, G.
2007-01-01
Starting from basic principles, the author, whose own contributions to these developments have been significant, describes the rapidly growing field of modern semiconductor detectors used for energy and position measurement radiation. This development was stimulated by requirements in elementary particle physics where it has led to important scientific discoveries. It has now spread to many other fields of science and technology. The book is written in a didactic way and includes an introduction to semiconductor physics. The working principles of semiconductor radiation detectors are explained in an intuitive way, followed by formal quantitative analysis. Broad coverage is also given to electronic signal readout and to the subject of radiation damage. The book is the first to comprehensively cover the semiconductor radiation detectors currently in use. It is useful as a teaching guide and as a reference work for research and applications. (orig.)
Radiation physics, biophysics, and radiation biology
International Nuclear Information System (INIS)
Hall, E.J.; Zaider, M.
1993-05-01
Research at the Center for Radiological Research is a multidisciplenary blend of physics, chemistry and biology aimed at understanding the mechanisms involved in the health problems resulting from human exposure to ionizing radiations. The focus is increased on biochemistry and the application of the techniques of molecular biology to the problems of radiation biology. Research highlights of the program from the past year are described. A mathematical model describing the production of single-strand and double-strand breaks in DNA as a function radiation quality has been completed. For the first time Monte Carlo techniques have been used to obtain directly the spatial distribution of DNA moieties altered by radiation. This information was obtained by including the transport codes a realistic description of the electronic structure of DNA. We have investigated structure activity relationships for the potential oncogenicity of a new generation of bioreductive drugs that function as hypoxic cytotoxins. Experimental and theoretical investigation of the inverse dose rate effect, whereby medium LET radiations actually produce an c effect when the dose is protracted, is now at a point where the basic mechanisms are reasonably understood and the complex interplay between dose, dose rate and radiation quality which is necessary for the effect to be present can now be predicted at least in vitro. In terms of early radiobiological damage, a quantitative link has been established between basic energy deposition and locally multiply damaged sites, the radiochemical precursor of DNA double strand breaks; specifically, the spatial and energy deposition requirements necessary to form LMDs have been evaluated. For the first time, a mechanically understood ''biological fingerprint'' of high-LET radiation has been established. Specifically measurement of the ratio of inter-to intra-chromosomal aberrations produces a unique signature from alpha-particles or neutrons
Radiation physics, biophysics, and radiation biology
Energy Technology Data Exchange (ETDEWEB)
Hall, E.J.; Zaider, M.
1993-05-01
Research at the Center for Radiological Research is a multidisciplenary blend of physics, chemistry and biology aimed at understanding the mechanisms involved in the health problems resulting from human exposure to ionizing radiations. The focus is increased on biochemistry and the application of the techniques of molecular biology to the problems of radiation biology. Research highlights of the program from the past year are described. A mathematical model describing the production of single-strand and double-strand breaks in DNA as a function radiation quality has been completed. For the first time Monte Carlo techniques have been used to obtain directly the spatial distribution of DNA moieties altered by radiation. This information was obtained by including the transport codes a realistic description of the electronic structure of DNA. We have investigated structure activity relationships for the potential oncogenicity of a new generation of bioreductive drugs that function as hypoxic cytotoxins. Experimental and theoretical investigation of the inverse dose rate effect, whereby medium LET radiations actually produce an c effect when the dose is protracted, is now at a point where the basic mechanisms are reasonably understood and the complex interplay between dose, dose rate and radiation quality which is necessary for the effect to be present can now be predicted at least in vitro. In terms of early radiobiological damage, a quantitative link has been established between basic energy deposition and locally multiply damaged sites, the radiochemical precursor of DNA double strand breaks; specifically, the spatial and energy deposition requirements necessary to form LMDs have been evaluated. For the first time, a mechanically understood biological fingerprint'' of high-LET radiation has been established. Specifically measurement of the ratio of inter-to intra-chromosomal aberrations produces a unique signature from alpha-particles or neutrons.
SOGRO (Superconducting Omni-directional Gravitational Radiation Observatory)
Paik, Ho Jung
2018-01-01
Detection of gravitational waves (GWs) from merging binary black holes (BHs) by Advanced LIGO has ushered in the new era of GW astronomy. Many conceivable sources such as intermediate-mass BH binaries and white dwarf binaries, as well as stellar-mass BH inspirals, would emit GWs below 10 Hz. It is highly desirable to open a new window for GW astronomy in the infrasound frequency band. A low-frequency tensor detector could be constructed by combining six magnetically levitated superconducting test masses. Such a detector would be equally sensitive to GWs coming from anywhere in the sky, and would be capable of resolving the source direction and wave polarization. I will present the design concept of a new terrestrial GW detector, named SOGRO, which could reach a strain sensitivity of 10-19-10-21 Hz-1/2 at 0.1-10 Hz. Seismic and Newtonian gravity noises are serious obstacles in constructing terrestrial GW detectors at frequencies below 10 Hz. I will explain how these noises are rejected in SOGRO. I will also report the progress made in designing the platform and modelling its thermal noise.
Medical radiation physics in Bulgaria
International Nuclear Information System (INIS)
Todorov, V.; Vasileva, G.
1999-01-01
In Bulgaria medical radiation physics in not yet on a world level. The number of medical physicists working in diagnostic and therapeutic centres is low. Comparatively good is the situation of medical physics in the areas of therapy and radiation protection. But the role of physics in medicine is underestimated as a whole, because of subjective reasons. At the other hand the education in this area is good and very professional. Since 1992 there has been established a specialty 'medical physics' in University of Shoumen and since 1997 the same specialty exists in Sofia University. The situation is expected to be approved with reorganization of the Health System in Bulgaria with compliance with the European standards
Synchrotron radiation in atomic physics
International Nuclear Information System (INIS)
Crasemann, B.
1998-01-01
Much of present understanding of atomic and molecular structure and dynamics was gained through studies of photon-atom interactions. In particular, observations of the emission, absorption, and scattering of X rays have complemented particle-collision experiments in elucidating the physics of atomic inner shells. Grounded on Max von Laue's theoretical insight and the invention of the Bragg spectrometer, the field's potential underwent a step function with the development of synchrotron-radiation sources. Notably current third-generation sources have opened new horizons in atomic and molecular physics by producing radiation of wide tunability and exceedingly high intensity and polarization, narrow energy bandwidth, and sharp time structure. In this review, recent advances in synchrotron-radiation studies in atomic and molecular science are outlined. Some tempting opportunities are surveyed that arise for future studies of atomic processes, including many-body effects, aspects of fundamental photon-atom interactions, and relativistic and quantum-electrodynamic phenomena. (author)
PREFACE: X Workshop of the Gravitation and Mathematical Physics Division, Mexican Physical Society
2014-11-01
The collection of papers in this volume was presented during the X Workshop of the Gravitation and Mathematical Physics Division of the Mexican Physical Society (DGFM-SMF), which was held in Pachuca, Hidalgo, México, December 2-6, 2013. The Workshop is a bi-annual series of conferences sponsored by the DGFM-SMF that started in 1993 with the purposes of discussing and exchanging the research and experience of the gravitational and mathematical physics communities in Mexico. Each Mexican Workshop has been devoted to subjects of broad interest, so that students, in particular, can have access to specialized courses and talks that allow them to raise up their qualifications as professional researchers. Recurrent topics in the Mexican Workshop are supergravity, branes, black holes, the early Universe, observational cosmology, quantum gravity and cosmology and numerical relativity. Following our previous Workshops, distinguished researchers in the field, working in Mexico, were invited to give courses, whereas young researchers were invited for plenary lectures. More specialized talks were also presented in parallel sessions, with ample participation of researchers, and graduate and undergraduate students; most of the presentations have been included in these proceedings. The contributions in this volume have been peer-reviewed, and they represent most of the courses, plenary talks and contributed talks presented during our Workshop. We are indebted to the contributors of these proceedings, as well as to the other participants and organizers, all for making the event a complete success. We acknowledge the professionalism of our reviewers, who helped us to keep high quality standards in all manuscripts. Acknowledgments The organizing committee would like to acknowledge the financial support of the Mexican National Science and Technology Council (CONACyT), the Mexican Physical Society (SMF), as well as several Institutions including: Centro de Investigación y Estudios
Backreaction of Hawking radiation on a gravitationally collapsing star I: Black holes?
International Nuclear Information System (INIS)
Mersini-Houghton, Laura
2014-01-01
Particle creation leading to Hawking radiation is produced by the changing gravitational field of the collapsing star. The two main initial conditions in the far past placed on the quantum field from which particles arise, are the Hartle–Hawking vacuum and the Unruh vacuum. The former leads to a time-symmetric thermal bath of radiation, while the latter to a flux of radiation coming out of the collapsing star. The energy of Hawking radiation in the interior of the collapsing star is negative and equal in magnitude to its value at future infinity. This work investigates the backreaction of Hawking radiation on the interior of a gravitationally collapsing star, in a Hartle–Hawking initial vacuum. It shows that due to the negative energy Hawking radiation in the interior, the collapse of the star stops at a finite radius, before the singularity and the event horizon of a black hole have a chance to form. That is, the star bounces instead of collapsing to a black hole. A trapped surface near the last stage of the star's collapse to its minimum size may still exist temporarily. Its formation depends on the details of collapse. Results for the case of Hawking flux of radiation with the Unruh initial state, will be given in a companion paper II
Radiation applications of physical chemistry
International Nuclear Information System (INIS)
Talrose, V.L.
1993-01-01
Many chemical energy problems have a physical chemistry nature connected with chemical kinetics and thermodynamics. In our country, the development in this field is associated with the name N.N. Semenov, who was involved in a large number of fundamental and applied physical chemistry problems.Energy development during the last decades created or sharpened new problems. Our new Institute, the Institute of Energy problems of Chemical Physics, USSR Academy of Sciences, is dealing with some of them. The present article is an overview of our work on radiation applications. Examples of the use of radiation in power industry (such as coal gasification), tire production, mechanical joints, metal powder production and sterilization of pharmaceutical products are given. Methods and problems involved in these applications are discussed and the great potential for vast utilization is demonstrated. (authors)
Statistical methods in radiation physics
Turner, James E; Bogard, James S
2012-01-01
This statistics textbook, with particular emphasis on radiation protection and dosimetry, deals with statistical solutions to problems inherent in health physics measurements and decision making. The authors begin with a description of our current understanding of the statistical nature of physical processes at the atomic level, including radioactive decay and interactions of radiation with matter. Examples are taken from problems encountered in health physics, and the material is presented such that health physicists and most other nuclear professionals will more readily understand the application of statistical principles in the familiar context of the examples. Problems are presented at the end of each chapter, with solutions to selected problems provided online. In addition, numerous worked examples are included throughout the text.
Isotropization of the cosmic background radiation due to galactic gravitational screening
International Nuclear Information System (INIS)
Tomita, Kenji.
1988-04-01
The primordial objects with the masses of galaxies or their clusters formed at early stages such as z > 10 can play a powerful role of gravitational lenses and their random multiple scattering brings an effective screening for the cosmic background radiation. In a cold-dark-matter dominant model with the white-noise spectrum of initial density perturbations, it is shown that, if the primordial objects with the masses 10 12 h -1 (solar mass) are in the nonlinear stage at the epochs 1 + z = 10 ∼ 20, the objects with 6 x 10 14 h -1 (solar mass) are in the nonlinear stage at 1 + z = 6.3 ∼ 14, and accordingly the small-scale anisotropy of the radiation may be smoothed-out within 13 ∼ 28 minutes by this gravitational screening, where the Hubble constant H o = 100 h km s -1 Mpc -1 . (author)
CERN. Geneva
2005-01-01
We will present a brief introduction to the physics of gravitational waves and their properties. We will review potential astrophysical sources of gravitational waves, and the physics and astrophysics that can be learned from their study. We will survey the techniques and technologies for detecting gravitational waves for the first time, including bar detectors and broadband interferometers, and give a brief status report on the international search effort, with special emphasis on the LIGO detectors and search results.
Medical radiation physics training EMERALD
International Nuclear Information System (INIS)
Tabakov, S.; Roberts, C.; Lamm, I.L.; Milano, F.; Lewis, C.; Smith, D.; Litchev, A.; Jonsson, B.A.; Ljungberg, M.; Strand, S.E.; Jonsson, L.; Riccardi, L.; Benini, A.; Silva, G. da; Teixeira, N.; Pascoal, A.; Noel, A.; Smith, P.; Musilek, L.; Sheahan, N.
2001-01-01
Training of young medical physicists is an essential part of the framework of measures for Radiological Protection of Patients. The paper describes the Medical Radiation Physics Training Scheme EMERALD, developed by an European Project Consortium. EMERALD Training covers the Physics of X-ray Diagnostic Radiology, Nuclear Medicine and Radiotherapy. Each of these 3 modules covers 4 months training period. The EMERALD training materials are 3 Workbooks with tasks and a Teachers' Guide (total volume approx 700 pages) and 3 CD-ROMs with image database. (author)
Aerosols, cloud physics and radiation
International Nuclear Information System (INIS)
Twomey, S.
1990-01-01
Some aspects of climate physics are discussed with special attention given to cases where cloud physics is relevant for the phase and microstructure of clouds and, therefore, in the optical properties of the planet. It is argued that aerosol particles, through their strong effect on cloud microphysics, influence the shortwave energy input to earth, and that cloud microphysics strongly influence rain formation. Therefore, through their influence on microphysics, the aerosols play a central role in the atmospheric water cycle and, thus, on the planet's outgoing radiation. 20 refs
Enhanced polarization of the cosmic microwave background radiation from thermal gravitational waves.
Bhattacharya, Kaushik; Mohanty, Subhendra; Nautiyal, Akhilesh
2006-12-22
If inflation was preceded by a radiation era, then at the time of inflation there will exist a decoupled thermal distribution of gravitons. Gravitational waves generated during inflation will be amplified by the process of stimulated emission into the existing thermal distribution of gravitons. Consequently, the usual zero temperature scale invariant tensor spectrum is modified by a temperature dependent factor. This thermal correction factor amplifies the B-mode polarization of the cosmic microwave background radiation by an order of magnitude at large angles, which may now be in the range of observability of the Wilkinson Microwave Anisotropy Probe.
Gravitational waves and antennas
CERN. Geneva
2003-01-01
Gravitational waves and their detection represent today a hot topic, which promises to play a central role in astrophysics, cosmology and theoretical physics. Technological developments have enabled the construction of such sensitive detectors that the detection of gravitational radiation and the start of a new astronomy could become a reality during the next few years. This is expected to bring a revolution in our knowledge of the universe by allowing the observation of hiterto unseen phenomena such as coalescence of compact objects (neutron stars and black holes) fall of stars into supermassive black holes, stellar core collapses, big bang relics and the new and unexpected. In these lectures I give a brief overview of this challenging field of modern physics. Topics : Basic properties of gravitational radiation. Astrophysical sources. Principle of operation of detectors. Interferometers (both ground based and space-based), bars and spheres. Present status of the experiments, their recent results and their f...
Radiation physics, biophysics, and radiation biology
International Nuclear Information System (INIS)
Hall, E.J.; Zaider, M.; Delegianis, M.J.
1989-07-01
An important event of the year was the designation of our Laboratory as a Center for Radiological Research by the Dean of the Faculty of Medicine and Vice-President for Health Sciences. Center status acknowledges the size and importance of the research efforts in this area, and allows a greater measure of independence in administrative matters. While the name has changed from a Laboratory to a Center within the Medical School, the mission and charge remain the same. The efforts of the Center are a multidisciplinary mix of physics, chemistry, and biology, mostly at a basic level, with the admixture of a small proportion of pragmatic or applied research in support of radiation protection or radiation therapy. About a quarter of our funding, mostly individual research awards, could be regarded as in direct support of radiotherapy, with the remainder (an NCI program project grant and DOE grants) being in support of research addressing more basic issues. An important effort currently underway concerns ab-initio calculations of the dielectric response function of condensed water. This investigation has received the coveted designation, ''Grand Challenge Project,'' awarded by DOE to research work which represents ''distinct advance on a major scientific or engineering problem that is broadly recognized as important within the mission of the Department.''
Perturbed effects at radiation physics
International Nuclear Information System (INIS)
Külahcı, Fatih; Şen, Zekâi
2013-01-01
Perturbation methodology is applied in order to assess the linear attenuation coefficient, mass attenuation coefficient and cross-section behavior with random components in the basic variables such as the radiation amounts frequently used in the radiation physics and chemistry. Additionally, layer attenuation coefficient (LAC) and perturbed LAC (PLAC) are proposed for different contact materials. Perturbation methodology provides opportunity to obtain results with random deviations from the average behavior of each variable that enters the whole mathematical expression. The basic photon intensity variation expression as the inverse exponential power law (as Beer–Lambert's law) is adopted for perturbation method exposition. Perturbed results are presented not only in terms of the mean but additionally the standard deviation and the correlation coefficients. Such perturbation expressions provide one to assess small random variability in basic variables. - Highlights: • Perturbation methodology is applied to Radiation Physics. • Layer attenuation coefficient (LAC) and perturbed LAC are proposed for contact materials. • Perturbed linear attenuation coefficient is proposed. • Perturbed mass attenuation coefficient (PMAC) is proposed. • Perturbed cross-section is proposed
Antihydrogen physics: gravitation and spectroscopy in AEgIS
Ferragut, R; Stroke, H H; Dassa, L; Rohne, O; Hogan, S D; Cialdi, S; Al-Qaradawi, I Y; Formaro, L; Sandaker, H; Testera, G; Stepanov, S V; Folegati, P; Morhard, C; Warring, U; Prelz, F; Belov, A S; Bonomi, G; Consolati, G; Ferrari, G; Lagomarsino, V; Krasnicky, D; Drobychev, G; Giammarchi, M G; Heyne, R; Zenoni, A; Castelli, F; Mariazzi, S; Cabaret, L; Fischer, A; Boscolo, I; Sillou, D; Villa, F; Perini, D; Djourelov, N; Zavatarelli, S; Oberthaler, M K; Manuzio, G; Carraro, C; Matveev, V A; Jorgensen, L V; Nedelec, P; Prevedelli, M; Comparat, D; Dupasquier, A; Turbabin, A V; Zvezhinskij, D S; Fontana, A; Kellerbauer, A; Canali, C; Dudarev, A; Petracek, V; Riccardi, C; Nebbia, G; Gninenko, S N; Brusa, R S; Rotondi, A; Sacerdoti, M; Calloni, A; Doser, M; Byakov, V M; Quasso, F; Trezzi, D
2011-01-01
AEgIS (Antimatter experiment: gravity, interferometry, spectroscopy) is an experiment approved by CERN with the goal of studying antihydrogen physics. In AEgIS, antihydrogen will be produced by charge exchange reactions of cold antiprotons with positronium atoms excited in a Rydberg state (n > 20). In the first phase of the experiment, controlled acceleration by an electric field gradient (Stark effect) and subsequent measurement of free fall in a Moire deflectometer will allow a test of the weak equivalence principle. In a second phase, the antihydrogen will be slowed, confined, and laser-cooled to perform CPT studies and detailed spectroscopy. In the present work, after a general description of the experiment, the present status of advancement will be reviewed, with special attention to the production and excitation of positronium atoms.
Radiation physics as a new science discipline
International Nuclear Information System (INIS)
Sri Ram, K.
1987-01-01
After tracing the evolution of radiation physics teaching at the university level in U.S.A., the current status of teaching of radiation physics in Indian Universities is reviewed. It is noted that parts of radiation physics are taught in some Indian academic institutions. Only Madras University offers an M.Sc. programme in radiation physics. Its curriculum is critically examined and it is noted that more emphasis is required on practical and applied aspects of radiation physics. Closer interaction between academic and R and D institutions is required. (M.G.B.)
Observable gravitational and electromagnetic orbits and trajectories in discrete physics
International Nuclear Information System (INIS)
Noyes, H.P.; McGoveran, D.O.
1988-01-01
Our discrete and finite version of relativistic quantum mechanics provides an elementary particle physics consistent with the standard model of quarks and leptons. Our recent relativistic calculation of the bound state spectrum of hydrogen has allowed us to make a combinatorial correction to the first order estimate of 1/α = /Dirac h/c/e 2 = 137 derived from the combinatorial hierarchy and achieve agreement with experiment up to terms of order α 3 . The same theory requires that to first order /Dirac h/c/Gm/sub p/ 2 = 2 127 + 136 ≅ 1.7 /times/ 10 38 . Using the emission and absorption of spin 1 photons and spin 2 gravitons in this framework, we try to show that we can meet the three additional tests of general relativity---solar red shift, solar bending of light, and precession of the perihelion of Mercury. We predict that a macroscopic electromagnetic orbit would have four times the Sommerfeld precession for basically the same reason that Mercury has six times the Sommerfeld precession. 20 refs
Note on self-gravitating radiation in AdS spacetime
International Nuclear Information System (INIS)
Li Zhonghua; Hu Bin; Cai Ronggen
2008-01-01
Recently Vaganov and Hammersley investigated independently the equilibrium self-gravitating radiation in higher (d≥4)-dimensional, spherically symmetric anti-de Sitter space. It was found that in 4≤d≤10, there exist locally stable radiation configurations all the way up to a maximum red-shifted temperature, above which there are no solutions; there is also a maximum mass and maximum entropy configuration occurring at a higher central density than the maximal temperature configuration. Beyond their peaks the temperature, mass, and entropy undergo an infinite series of damped oscillations, which indicates the configurations in this range are unstable. In d≥11, the temperature, mass, and entropy of the self-gravitating configuration are monotonic functions of the central energy density, asymptoting to their maxima as the central density goes to infinity. In this paper we investigate the equilibrium self-gravitating radiation in higher-dimensional, plane-symmetric anti-de Sitter space. We find that there exist essential differences from the spherically symmetric case: In each dimension (d≥4), there are maximal mass (density), maximal entropy (density), and maximal temperature configurations; they do not appear at the same central energy density; the oscillation behavior appearing in the spherically symmetric case does not happen in this case; and the mass (density), as a function of the central energy density, increases first and reaches its maximum at a certain central energy density and then decreases monotonically in 4≤d≤7, while in d≥8, besides the maximum, the mass (density) of the equilibrium configuration has a minimum: the mass (density) first increases and reaches its maximum, then decreases to its minimum, and then increases to its asymptotic value monotonically. The reason causing the difference is discussed
Barausse, Enrico; Yunes, Nicolás; Chamberlain, Katie
2016-06-17
The aLIGO detection of the black-hole binary GW150914 opens a new era for probing extreme gravity. Many gravity theories predict the emission of dipole gravitational radiation by binaries. This is excluded to high accuracy in binary pulsars, but entire classes of theories predict this effect predominantly (or only) in binaries involving black holes. Joint observations of GW150914-like systems by aLIGO and eLISA will improve bounds on dipole emission from black-hole binaries by 6 orders of magnitude relative to current constraints, provided that eLISA is not dramatically descoped.
Interaction of a parametric transducer with a resonant bar gravitational radiation detector
International Nuclear Information System (INIS)
Linthorne, N.P.; Veitch, P.J.; Blair, D.G.
1990-01-01
It is shown that a microwave parametric transducer for a resonant bar gravitational radiation antenna can achieve high electromechanical coupling without degrading the acoustic Q of the antenna. The reactive coupling of the transducer to the antenna leads to both cold-damping and modification of the antenna's resonant frequency. These effects are examined in a 1.5 tonne niobium resonant bar antenna. At low coupling the observed behaviour is found to be in good agreement with theory. At higher coupling, the behaviour is complicated by other effects. We discuss how these parametric effects may be used to advantage when suitably controlled. (author)
Conservation laws and radiation in the scale covariant theory of gravitation
International Nuclear Information System (INIS)
Beesham, A.
1988-01-01
The conservation laws for mass, energy, and momentum are derived in the scale covariant theory of gravitation. The entropy problem which exists in the standard Friedmann-Lemaitre-Robertson-Walker models can be solved in the present context. Since the weak and strong energy conditions may be violated, a big bang singularity may be avoided, in contrast to general relativity. Since beta is shown to be constant during the radiation-dominated era, the difficulties in the theory associated with nucleosynthesis are avoided. 10 references
International Nuclear Information System (INIS)
Boyer, T.H.
1984-01-01
A derivation of Planck's spectrum including zero-point radiation is given within classical physics from recent results involving the thermal effects of acceleration through classical electromagnetic zero-point radiation. A harmonic electric-dipole oscillator undergoing a uniform acceleration a through classical electromagnetic zero-point radiation responds as would the same oscillator in an inertial frame when not in zero-point radiation but in a different spectrum of random classical radiation. Since the equivalence principle tells us that the oscillator supported in a gravitational field g = -a will respond in the same way, we see that in a gravitational field we can construct a perpetual-motion machine based on this different spectrum unless the different spectrum corresponds to that of thermal equilibrium at a finite temperature. Therefore, assuming the absence of perpetual-motion machines of the first kind in a gravitational field, we conclude that the response of an oscillator accelerating through classical zero-point radiation must be that of a thermal system. This then determines the blackbody radiation spectrum in an inertial frame which turns out to be exactly Planck's spectrum including zero-point radiation
Proceedings of the Ninth Radiation Physics and Protection Conference
International Nuclear Information System (INIS)
2009-01-01
The publication has been set up as proceedings of the Radiation Physics and Protection conference, the conference contains of the following subjects: Radiation Sources and Radioactive Waste; Theoretical Radiation Physics; Experimental Radiation Physics; Radiation and Nuclear Emergency; Non Ionizing Radiation; Medical Physics; Environment; Natural Radioactivity; Radiation Effect; Dosimetry; Elemental Analysis; Radiation Instruments. This conference consists of one volume and 459 pages., figs., tabs., refs
International Nuclear Information System (INIS)
Iordache, Dan-Alexandru
2005-01-01
As in the period of creation of the 'monumental' works of A. Einstein (1905-1920, mainly), when many outstanding physicists [theoreticians, inclusively, as Albert Einstein (alumni of the Polytechnics from Geneva), as Paul Adrian Maurice Dirac, Alexandru Proca (alumni of Bucharest Polytechnics), et al., finished their academic studies to different Polytechnics Universities, presently many students of technical Universities obtained (as high-school students) some outstanding results in the Physics field. Particularly, the leadership of the Faculty of Control Systems and Computers of the Bucharest University has found that 'the best students in their divisions are winners at the Physics Olympics Contests'. These students and many of their colleagues (those with special scientific aptitudes) want to know more details about the most difficult scientific creation of Albert Einstein: the Gravitation Theory. Taking into account that the Einstein's Gravitation Theory is particularly difficult (from mathematical point of view, especially), and the duration of the Physics study in our technical universities is so restricted (totally 42 to 98 teaching hours, depending on the technical division profile), we have to answer to the question: what elements of the Einstein's gravity theory could be presented in frame of Physics courses taught in our technical universities? After accomplishing our analysis, we concluded as possible and useful - for the scientific training of the best students 'engineers' - the assimilation of the following elements of the Einstein's gravity theory: - The time and space concepts in the Einstein's gravitation theory, in connection with the equation of electromagnetic waves in ideal media and - eventually - in relation with the Larmor's theory of the electrical dipole radiation [which needs the expressions in curvilinear coordinates of the gradient and divergence (the main elements of the mathematical theory of fields)]; - The applications of the
Proceedings of the 7th Italian conference on general relativity and gravitational physics
International Nuclear Information System (INIS)
Bruzzo, U.; Cianci, R.; Massa, E.
1987-01-01
The 7th Italian Conference on General Relativity and Gravitational Physics was held in Rapallo (Genoa), from September 3 to 6, 1986, under the auspices of the International Society on General Relativity and Gravitation. Like the previous conferences of this series, it brought together physicists, mathematicians, and astronomers interested in various aspects of relativity, field theory, astrophysics, and cosmology. The scientific program included two types of sessions: invited lectures and workshops for presenting contributed papers. All these have been grouped into four main sections. The divisions are the following: A: General Relativity; B: Field Theory, Supergravity, and Strings; C: Relativistic Astrophysics and Cosmology; D: Experimental and Observational Relativity. This book presents the papers discussed in the meetings on the above mentioned subjects
Teaching the gravitational redshift: lessons from the history and philosophy of physics
International Nuclear Information System (INIS)
Scott, Robert B
2015-01-01
The equivalence principle and the notion of an ideal clock running independently of acceleration suggest that clocks are unaffected by gravity. The apparent contradiction with the gravitational redshift points to a subtlety in general relativity theory. Indeed, early attempts for a clear derivation of the gravitational redshift were fraught with errors and ambiguities, and much confusion endured for the next two decades. This suggests that the subject should be treated carefully in introductory textbooks on relativity theory. I analyze the weaknesses of the presentation in five otherwise excellent modern introductory general relativity books (by Rindler, Schutz, Hobson et al., Weinberg, and Carroll). I also present some analysis from an history and philosophy of physics article, which proves to be a great resource to learn about, anticipate, and clarify problems in teaching the redshift. (paper)
Cosmology and Gravitation: the grand scheme for High-Energy Physics
Binétruy, P.
2014-12-10
These lectures describe how the Standard Model of cosmology ( Λ CDM) has developped, based on observational facts but also on ideas formed in the context of the theory of fundamental interactions, both gravitational and non-gravitational, the latter being described by the Standard Model of high energy physics. It focuses on the latest developments, in particular the precise knowledge of the early Universe provided by the observation of the Cosmic Microwave Background and the discovery of the present acceleration of the expansion of the Universe. While insisting on the successes of the Standard Model of cosmology, we will stress that it rests on three pillars which involve many open questions: the theory of inflation, the nature of dark matter and of dark energy. We will devote one chapter to each of these issues, describing in particular how this impacts our views on the theory of fundamental interactions. More technical parts are given in italics. They may be skipped altogether.
Directory of Open Access Journals (Sweden)
Roberto Peron
2017-07-01
Full Text Available A dedicated mission in low Earth orbit is proposed to test predictions of gravitational interaction theories and to directly measure the atmospheric density in a relevant altitude range, as well as to provide a metrological platform able to tie different space geodesy techniques. The concept foresees a small spacecraft to be placed in a dawn-dusk eccentric orbit between 450 and 1200 km of altitude. The spacecraft will be tracked from the ground with high precision, and a three-axis accelerometer package on-board will measure the non-gravitational accelerations acting on its surface. Estimates of parameters related to fundamental physics and geophysics should be obtained by a precise orbit determination, while the accelerometer data will be instrumental in constraining the atmospheric density. Along with the mission scientific objectives, a conceptual configuration is described together with an analysis of the dynamical environment experienced by the spacecraft and the accelerometer.
3.International conference 'Nuclear and Radiation Physics'
International Nuclear Information System (INIS)
2001-01-01
The 3-rd International Conference 'Nuclear and Radiation Physics' was held in Almaty (Kazakhstan) 4-7 June 2001. The primary purpose of the conference is consolidation of the scientists efforts in the area of fundamental and applied investigations on nuclear physics, radiation physics of solids and radioecology. In the conference more than 350 papers were presented by participants from 17 countries
Kelly, Bernard J.
2010-01-01
Einstein's General Theory of Relativity is our best classical description of gravity, and informs modern astronomy and astrophysics at all scales: stellar, galactic, and cosmological. Among its surprising predictions is the existence of gravitational waves -- ripples in space-time that carry energy and momentum away from strongly interacting gravitating sources. In my talk, I will give an overview of the properties of this radiation, recent breakthroughs in computational physics allowing us to calculate the waveforms from galactic mergers, and the prospect of direct observation with interferometric detectors such as LIGO and LISA.
Introduction to ionizing radiation physics
International Nuclear Information System (INIS)
Musilek, L.
1979-01-01
Basic properties are described of the atom, atomic nucleus and of ionizing radiation particles; nuclear reactions, ionizing radiation sources and ionizing radiation interaction with matter are explained. (J.P.)
International Nuclear Information System (INIS)
Jiang Qingquan; Wu Shuangqing
2007-01-01
Robinson-Wilczek's recent work, which treats Hawking radiation as a compensating flux to cancel gravitational anomaly at the horizon of a Schwarzschild-type black hole, is extended to study Hawking radiation of rotating black holes in anti-de Sitter spaces, especially that in dragging coordinate system, via gauge and gravitational anomalies. The results show that in order to restore gauge invariance and general coordinate covariance at the quantum level in the effective field theory, the charge and energy flux by requiring to cancel gauge and gravitational anomalies at the horizon, must have a form equivalent to that of a (1+1)-dimensional blackbody radiation at Hawking temperature with an appropriate chemical potential
Physics and engineering of radiation detection
Ahmed, Syed Naeem
2015-01-01
Physics and Engineering of Radiation Detection presents an overview of the physics of radiation detection and its applications. It covers the origins and properties of different kinds of ionizing radiation, their detection and measurement, and the procedures used to protect people and the environment from their potentially harmful effects. The second edition is fully revised and provides the latest developments in detector technology and analyses software. Also, more material related to measurements in particle physics and a complete solutions manual have been added.
Accuracy of inference on the physics of binary evolution from gravitational-wave observations
Barrett, Jim W.; Gaebel, Sebastian M.; Neijssel, Coenraad J.; Vigna-Gómez, Alejandro; Stevenson, Simon; Berry, Christopher P. L.; Farr, Will M.; Mandel, Ilya
2018-04-01
The properties of the population of merging binary black holes encode some of the uncertain physics underlying the evolution of massive stars in binaries. The binary black hole merger rate and chirp-mass distribution are being measured by ground-based gravitational-wave detectors. We consider isolated binary evolution, and explore how accurately the physical model can be constrained with such observations by applying the Fisher information matrix to the merging black hole population simulated with the rapid binary-population synthesis code COMPAS. We investigate variations in four COMPAS parameters: common-envelope efficiency, kick-velocity dispersion, and mass-loss rates during the luminous blue variable and Wolf-Rayet stellar-evolutionary phases. We find that ˜1000 observations would constrain these model parameters to a fractional accuracy of a few per cent. Given the empirically determined binary black hole merger rate, we can expect gravitational-wave observations alone to place strong constraints on the physics of stellar and binary evolution within a few years. Our approach can be extended to use other observational data sets; combining observations at different evolutionary stages will lead to a better understanding of stellar and binary physics.
Chapter 1: A little of Radiation Physics and radiation protection
Energy Technology Data Exchange (ETDEWEB)
NONE
2018-04-01
The chapter 1 presents the subjects: 1) quantities and units of radiation physics which includes: the electron volt (eV); Exposure (X); Absorbed dose (D); Dose equivalent (H); Activity (A); Half-life; Radioactive decay; 2) Radiation protection which includes: irradiation and radioactive contamination; irradiation; contamination; background radiation; dose limits for individual occupationally exposed (IOE) and for the general public.
Radiation physics, biophysics, and radiation biology
International Nuclear Information System (INIS)
Hall, E.J.
1992-05-01
The following research programs from the Center for Radiological Research of Columbia University are described: Design and development of a new wall-less ultra miniature proportional counter for nanodosimetry; some recent measurements of ionization distributions for heavy ions at nanometer site sizes with a wall-less proportional counter; a calculation of exciton energies in periodic systems with helical symmetry: application to a hydrogen fluoride chain; electron energy-loss function in polynucleotide and the question of plasmon excitation; a non-parametric, microdosimetric-based approach to the evaluation of the biological effects of low doses of ionizing radiation; high-LET radiation risk assessment at medium doses; high-LET radiobiological effects: increased lesion severity or increased lesion proximity; photoneutrons generated by high energy medical linacs; the biological effectiveness of neutrons; implications for radiation protection; molecular characterization of oncogenes induced by neutrons; and the inverse dose-rate effect for oncogenic transformation by charged particles is LET dependent
Gravitational Radiation from Binary Black Holes: Advances in the Perturbative Approach
Lousto, C. O.
2005-08-01
After the work of Regge, Wheeler, Zerilli, Teukolsky and others in the 1970s, it became possible to accurately compute the gravitational radiation generated by the collision of two black holes (in the extreme-mass limit). It was soon evident that, to first perturbative order, a particle in a circular orbit would continue orbiting forever if the radiative corrections to the particle motion that make the orbit decay were not taken into account. When I entered the field in 1996, a quick search of the literature showed that this problem was still unsolved. A straightforward computation leads to infinities produced by the representation of the particle in terms of Dirac delta functions. Since 1938, when Dirac had solved the equivalent problem in electromagnetic theory, nobody had succeeded in regularizing this in a self-consistent manner. Fortunately, the solution was arrived at much sooner than we expected. In 1997, Mino, Sasaki and Tanaka, and Quinn and Wald published the equations of motion that a particle obeys after self-force corrections. This essentially gave birth to the field of radiation reaction/self-force computations. The aim of this programme is first to obtain the corrections to the geodesic motion of a particle in the background of a single black hole, and then to use this corrected trajectory to compute second-order perturbations of the gravitational field. This will give us the energy-momentum radiated to infinity and into the hole, as well as the waveforms that we will eventually be able to measure with ground- or space-based gravitational wave detectors. As mentioned, the programme as a whole will give us waveforms accurate to second perturbative order in the mass ratio of the black holes, i.e. Script O[(m/M)2]. This will be a good approximation for galactic binary black holes of the order of a few solar masses, in the right frequency range (few hundred Hertz) to be detected by ground-based gravitational wave interferometers such as LIGO and VIRGO
Proceedings of the Tenth Radiation Physics and Protection Conference
International Nuclear Information System (INIS)
2011-01-01
The publication has been set up as proceedings of the Radiation Physics and Protection Conference.. The conference consists Natural Radiation Sources; Radiation Detection and Measurements; Applied Radiation Physics; Radiation Medical Physics and Biophysics; Radiation Dosimetry; Operational Radiation Protection; Radiation Shielding; Transport of Radioactive Materials; Nuclear and Radiation Physics; Medical Physics and Public Protection Against Radiological Attack. This conference consists of 402 p., figs., tabs., refs.
Basic radiation physics and chemistry of composites
International Nuclear Information System (INIS)
Przybytniak, G.; Zagorski, Z.P.
2006-01-01
Composites are increasingly more important in the applied and fundamental polymer science, and the participation of radiation processing of these systems increase. In presented paper the newest achievements of radiation physics and chemistry of composites are reviewed. It is stressed, that although main experimental effort is directed towards the development of composites as such, and investigation of their specific properties, mechanical, physicochemical and physical, the radiation processing will enter the field on the wider scale, especially as concerns specialized plastics
Bursts of gravitational radiation from superconducting cosmic strings and the neutrino mass spectrum
International Nuclear Information System (INIS)
Mosquera Cuesta, Herman J.
2001-02-01
Berezinsky, Hnatyk and Vilenkin showed that superconducting cosmic strings could be central engines for cosmological gamma-ray bursts and for producing the neutrino component of ultra-high energy cosmic rays. A consequence of this mechanism would be that a detectable cusp-triggered gravitational wave burst should be release simultaneously with the γ-ray surge. If contemporary measurements of both γ and ν radiation could be made for any particular source, then the cosmological time-delay between them might be useful for putting unprecedently tight bounds on the neutrino mass spectrum. Such measurements could consistently verify or rule out the model since strictly correlated behaviour is expected for the duration of the event and for the time variability of the spectra. (author)
Ionising radiation - physical and biological effects
International Nuclear Information System (INIS)
Holter, Oe.; Ingebretsen, F.; Parr, H.
1979-01-01
The physics of ionising radiation is briefly presented. The effects of ionising radiation on biological cells, cell repair and radiosensitivity are briefly treated, where after the effects on man and mammals are discussed and related to radiation doses. Dose limits are briefly discussed. The genetic effects are discussed separately. Radioecology is also briefly treated and a table of radionuclides deriving from reactors, and their radiation is given. (JIW)
Energy Technology Data Exchange (ETDEWEB)
Kim, Dong-Hoon [Basic Science Research Institute, Ewha Womans University, Seoul 03760 (Korea, Republic of); Trippe, Sascha, E-mail: ki13130@gmail.com, E-mail: trippe@astro.snu.ac.kr [Department of Physics and Astronomy, Seoul National University, Seoul 08826 (Korea, Republic of)
2016-10-20
Understanding the interaction of primordial gravitational waves (GWs) with the Cosmic Microwave Background (CMB) plasma is important for observational cosmology. In this article, we provide an analysis of an apparently as-yet-overlooked effect. We consider a single free electric charge and suppose that it can be agitated by primordial GWs propagating through the CMB plasma, resulting in periodic, regular motion along particular directions. Light reflected by the charge will be partially polarized, and this will imprint a characteristic pattern on the CMB. We study this effect by considering a simple model in which anisotropic incident electromagnetic (EM) radiation is rescattered by a charge sitting in spacetime perturbed by GWs, and becomes polarized. As the charge is driven to move along particular directions, we calculate its dipole moment to determine the leading-order rescattered EM radiation. The Stokes parameters of the rescattered radiation exhibit a net linear polarization. We investigate how this polarization effect can be schematically represented out of the Stokes parameters. We work out the representations of gradient modes (E-modes) and curl modes (B-modes) to produce polarization maps. Although the polarization effect results from GWs, we find that its representations, the E- and B-modes, do not practically reflect the GW properties such as strain amplitude, frequency, and polarization states.
Physics and engineering of radiation detection
Ahmed, Syed Naeem
2007-01-01
Physics and Engineering of Radiation Detection presents an overview of basic physics of radiation and its applications and covers the origins and properties of different kinds of ionizing radiation, their detection and measurement, and the procedures used to protect people and the environment from their potentially harmful effects. Covering both the basic physics of radiation and its applications, it will provide an up-to-date and coherent account of the origins and properties of the different kinds of ionizing radiation, and their detection and measurement. This book will illustrate the basic physical principles with an abundance of practical, worked-out examples, numerical problems, real world applications, and data, including biological effects, radon, risk assessment, and statistics.
International Nuclear Information System (INIS)
Braginsky, V.B.; Kardashev, N.S.; Polnarev, A.G.; Novikov, I.D.
1989-12-01
Propagation of an electromagnetic wave in the field of gravitational waves is considered. Attention is given to the principal difference between the electromagnetic wave propagation in the field of random gravitational waves and the electromagnetic wave propagation in a medium with a randomly-inhomogeneous refraction index. It is shown that in the case of the gravitation wave field the phase shift of an electromagnetic wave does not increase with distance. The capability of space radio interferometry to detect relic gravitational waves as well as gravitational wave bursts of non cosmological origin are analyzed. (author). 64 refs, 2 figs
Energy Technology Data Exchange (ETDEWEB)
Dyer, C C [Cambridge Univ. (UK). Inst. of Theoretical Astronomy
1976-05-01
The gravitational effect of density concentrations in the Universe on the temperature distribution of the cosmic blackbody background radiation is considered, using the Swiss cheese model universe, and supposing each hole to contain an expanding, homogeneous dust sphere at its centre. The temperature profile across such a hole differs in an essential way from that obtained earlier by Rees et al (Nature; 217:511 (1968)). The evolution of this effect with the expansion of the Universe is considered for 'relatively increasing' density contrasts emerging from the same initial singular state as the rest of the Universe. This effect becomes comparable to the bremsstrahlung and Compton effects on the isotropy of the background radiation for masses of about 10/sup 19/ times the mass of the sun, and exceeds these other effects as about Msup(2/3) for larger masses. If large-scale condensations of the Universe can be found for z approximately 1 to 5, delineated, maybe, by the clustering of quasars, etc., then this effect may be observable.
Highlights in gravitation and cosmology
International Nuclear Information System (INIS)
Iyer, B.R.; Kembhavi, Ajit; Narlikar, J.V.; Vishveshwara, C.V.
1988-01-01
This book assesses research into gravitation and cosmology by examining the subject from various viewpoints: the classical and quantum pictures, along with the cosmological and astrophysical applications. There are 35 articles by experts of international standing. Each defines the state of the art and contains a concise summary of our present knowledge of a facet of gravitational physics. These edited papers are based on those first given at an international conference held in Goa, India at the end of 1987. The following broad areas are covered: classical relativity, quantum gravity, cosmology, black holes, compact objects, gravitational radiation and gravity experiments. In this volume there are also summaries of discussions on the following special topics: exact solutions of cosmological equations, mathematical aspects of general relativity, the early universe, and quantum gravity. For research workers in cosmology and gravitation this reference book provides a broad view of present achievements and current problems. (author)
Problems of generation and reception of gravitational waves
International Nuclear Information System (INIS)
Pisarev, A.F.
1975-01-01
The present day status of the problems of gravitation, wave radiation and reception is surveyed. The physical presentation and mathematical description of the processes of radiation, propagation and interaction of gravitation waves with matter and the electromagnetic field are given. The experiments on the search for gravitation waves of astophysical nature are analysed. The laboratory and cosmic sources of these waves and the methods of their reception are described. Special attention is drawn to the analysis of the proposals to perform a complete laboratory gravitation wave experiment
Problems of generation and reception of gravitational waves. [Review
Energy Technology Data Exchange (ETDEWEB)
Pisarev, A F [Joint Inst. for Nuclear Research, Dubna (USSR)
1975-01-01
The present day status of the problems of gravitation, wave radiation and reception is surveyed. The physical presentation and mathematical description of the processes of radiation, propagation and interaction of gravitation waves with matter and the electromagnetic field are given. The experiments on the search for gravitation waves of astophysical nature are analysed. The laboratory and cosmic sources of these waves and the methods of their reception are described. Special attention is drawn to the analysis of the proposals to perform a complete laboratory gravitation wave experiment.
International Nuclear Information System (INIS)
Liu Jinzhong; Han Zhanwen; Zhang Fenghui; Zhang Yu
2010-01-01
Close double white dwarfs (CDWDs) are believed to dominate the Galactic gravitational wave (GW) radiation in the frequency range 10 -4 to 0.1 Hz, which will be detected by the Laser Interferometer Space Antenna (LISA) detector. The aim of this detector is to detect GW radiation from astrophysical sources in the universe and to help improve our understanding of the origin of the sources and their physical properties (masses and orbital periods). In this paper, we study the probable candidate sources in the Galaxy for the LISA detector: CDWDs. We use the binary population synthesis approach of CDWDs together with the latest findings of the synthesis models from Han, who proposed three evolutionary channels: (1) stable Roche lobe overflow plus common envelope (RLOF+CE), (2) CE+CE, and (3) exposed core plus CE. As a result, we systematically investigate the detailed physical properties (the distributions of masses, orbital periods, and chirp masses) of the CDWD sources for the LISA detector, examine the importance of the three evolutionary channels for the formation of CDWDs, and carry out Monte Carlo simulations. Our results show that RLOF+CE and CE+CE are the main evolutionary scenarios leading to the formation of CDWDs. For the LISA detectable sources, we also explore and discuss the importance of these three evolutionary channels. Using the calculated birth rate, we compare our results to the LISA sensitivity curve and the foreground noise floor of CDWDs. We find that our estimate for the number of CDWD sources that can be detected by the LISA detector is greater than 10,000. We also find that the detectable CDWDs are produced via the CE+CE channel and we analyze the fraction of the detectable CDWDs that are double helium (He+He), or carbon-oxygen plus helium (CO+He) WD binary systems.
Semiconductor radiation detectors: device physics
National Research Council Canada - National Science Library
Lutz, Gerhard
1999-01-01
..., including nuclear physics, elementary particle physics, optical and x-ray astronomy, medicine, and materials testing - and the number of applications is growing continually. Closely related, and initiated by the application of semiconductors, is the development of low-noise low-power integrated electronics for signal readout. The success of semicond...
Physics of intense, high energy radiation effects.
Energy Technology Data Exchange (ETDEWEB)
Hjalmarson, Harold Paul; Hartman, E. Frederick; Magyar, Rudolph J.; Crozier, Paul Stewart
2011-02-01
This document summarizes the work done in our three-year LDRD project titled 'Physics of Intense, High Energy Radiation Effects.' This LDRD is focused on electrical effects of ionizing radiation at high dose-rates. One major thrust throughout the project has been the radiation-induced conductivity (RIC) produced by the ionizing radiation. Another important consideration has been the electrical effect of dose-enhanced radiation. This transient effect can produce an electromagnetic pulse (EMP). The unifying theme of the project has been the dielectric function. This quantity contains much of the physics covered in this project. For example, the work on transient electrical effects in radiation-induced conductivity (RIC) has been a key focus for the work on the EMP effects. This physics in contained in the dielectric function, which can also be expressed as a conductivity. The transient defects created during a radiation event are also contained, in principle. The energy loss lead the hot electrons and holes is given by the stopping power of ionizing radiation. This information is given by the inverse dielectric function. Finally, the short time atomistic phenomena caused by ionizing radiation can also be considered to be contained within the dielectric function. During the LDRD, meetings about the work were held every week. These discussions involved theorists, experimentalists and engineers. These discussions branched out into the work done in other projects. For example, the work on EMP effects had influence on another project focused on such phenomena in gases. Furthermore, the physics of radiation detectors and radiation dosimeters was often discussed, and these discussions had impact on related projects. Some LDRD-related documents are now stored on a sharepoint site (https://sharepoint.sandia.gov/sites/LDRD-REMS/default.aspx). In the remainder of this document the work is described in catergories but there is much overlap between the atomistic
Physics of intense, high energy radiation effects
International Nuclear Information System (INIS)
Hjalmarson, Harold Paul; Hartman, E. Frederick; Magyar, Rudolph J.; Crozier, Paul Stewart
2011-01-01
This document summarizes the work done in our three-year LDRD project titled 'Physics of Intense, High Energy Radiation Effects.' This LDRD is focused on electrical effects of ionizing radiation at high dose-rates. One major thrust throughout the project has been the radiation-induced conductivity (RIC) produced by the ionizing radiation. Another important consideration has been the electrical effect of dose-enhanced radiation. This transient effect can produce an electromagnetic pulse (EMP). The unifying theme of the project has been the dielectric function. This quantity contains much of the physics covered in this project. For example, the work on transient electrical effects in radiation-induced conductivity (RIC) has been a key focus for the work on the EMP effects. This physics in contained in the dielectric function, which can also be expressed as a conductivity. The transient defects created during a radiation event are also contained, in principle. The energy loss lead the hot electrons and holes is given by the stopping power of ionizing radiation. This information is given by the inverse dielectric function. Finally, the short time atomistic phenomena caused by ionizing radiation can also be considered to be contained within the dielectric function. During the LDRD, meetings about the work were held every week. These discussions involved theorists, experimentalists and engineers. These discussions branched out into the work done in other projects. For example, the work on EMP effects had influence on another project focused on such phenomena in gases. Furthermore, the physics of radiation detectors and radiation dosimeters was often discussed, and these discussions had impact on related projects. Some LDRD-related documents are now stored on a sharepoint site (https://sharepoint.sandia.gov/sites/LDRD-REMS/default.aspx). In the remainder of this document the work is described in catergories but there is much overlap between the atomistic calculations, the
Applied physics of external radiation exposure dosimetry and radiation protection
Antoni, Rodolphe
2017-01-01
This book describes the interaction of living matter with photons, neutrons, charged particles, electrons and ions. The authors are specialists in the field of radiation protection. The book synthesizes many years of experiments with external radiation exposure in the fields of dosimetry and radiation shielding in medical, industrial and research fields. It presents the basic physical concepts including dosimetry and offers a number of tools to be used by students, engineers and technicians to assess the radiological risk and the means to avoid them by calculating the appropriate shields. The theory of radiation interaction in matter is presented together with empirical formulas and abacus. Numerous numerical applications are treated to illustrate the different topics. The state of the art in radiation protection and dosimetry is presented in detail, especially in the field of simulation codes for external exposure to radiation, medical projects and advanced research. Moreover, important data spread in differ...
Biological physics and synchrotron radiation
International Nuclear Information System (INIS)
Filhol, J.M.; Chavanne, J.; Weckert, E.
2001-01-01
This conference deals with the applications of synchrotron radiation to current problems in biology and medicine. Seven sessions take stock on the subject: sources and detectors; inelastic scattering and dynamics; muscle diffraction; reaction mechanisms; macromolecular assemblies; medical applications; imaging and spectroscopy. The document presents the papers abstracts. (A.L.B.)
Biological physics and synchrotron radiation
Energy Technology Data Exchange (ETDEWEB)
Filhol, J M; Chavanne, J [European Synchrotron Radiation Facility, 38 - Grenoble (France); Weckert, E [Hasylab at Desy, Hamburg (Germany); and others
2001-07-01
This conference deals with the applications of synchrotron radiation to current problems in biology and medicine. Seven sessions take stock on the subject: sources and detectors; inelastic scattering and dynamics; muscle diffraction; reaction mechanisms; macromolecular assemblies; medical applications; imaging and spectroscopy. The document presents the papers abstracts. (A.L.B.)
Atomic physics research with synchrotron radiation
International Nuclear Information System (INIS)
Crasemann, B.; Wuilleumier, F.
1985-01-01
This chapter discusses applications of synchrotron light in atomic and molecular physics. Use of the radiation from storage rings has expanded and lent access to new areas of absorption and photoemission spectroscopy and scattering experiments. Techniques applied in connection with synchrotron radiation are discussed including absorption spectroscopy, photoelectron spectroscopy, fluorescence spectroscopy and X-ray scattering. Problem areas that are being studied by the techniques mentioned above are discussed. Synchrotron radiation has provided the means for measuring the threshold-excitation and interference effects that signal the breakdown of the two-step model of atomic excitation/deexcitation. Synchrotron radiation provides more means of excited-state photoionization measurements
Radiation and risk in physics education
International Nuclear Information System (INIS)
Eijkelhof, H.M.C.
1990-01-01
The study reported in this thesis deals with physics education, particularly with the teaching and learning of radioactivity and ionizing radiation. It is a follow up of earlier research and development work in the Dutch Physics Curriculum Development Project (PLON) on a unit called Ionizing Radiation. The central theme of this unit was the acceptability of the risks of ionizing radiation. Preliminary evaluation of the effectiveness of the PLON-unit showed that pupils appear to have lay-ideas which seem to be resistant to change. In this study the nature and persistence of these lay-ideas have been explored and a set of recommendations have been developed for writing curriculum materials and for teaching strategies, for physics lessons in secondary high school, in order to promote thoughtful risk analysis and assessment as regards applications of ionizing radiation. (H.W.). 225 refs.; 3 figs.; 41 tabs
Progress in Medical Radiation Physics
International Nuclear Information System (INIS)
Orton, C.G.
1982-01-01
In-depth reviews of the advances and concepts in the application of radiation to medicine are presented in six comprehensive review articles which help to bridge the communications gap between the international research community and the medical physicists and physicians whose responsibility it is to put these advances into clinical use. Topics include techniques used both for the diagnosis of disease, such as computerized tomography, digital radiography, ultrasonography, computerized nuclear medicine scanning, and nuclear magnetic resonance imaging, and for its treatment, such as the radiotherapeutic utilization of high-LET radiations, and the widespread application of computers to perform dosimetry calculations from 3-D treatment planning and imaging. Each chapter has extensive references and the collection is indexed
International Nuclear Information System (INIS)
Bertotti, B.; Carr, B.J.
1980-01-01
We examine the theoretical and experimental prospects of detecting a low-frequency, continuous, stochastic background of gravitational waves by Doppler tracking interplanetary spacecraft. From a theoretical standpoint, such a background may have been generated by various postgalactic processes or by pregalactic black hole formation; there could also exist a primordial background which goes back to the beginning of the universe. We review the characteristic frequency and density ranges which one might anticipate for these backgrounds. From an experimental standpoint, one's ability to detect a background is limited by the finite length of the record available and by an imperfect knowledge of the spectrum of various sources of noise. The fundamental contribution to the noise comes from the clock which regulates the frequency of the tracking waves. If one uses a hydrogen maser clock, this noise becomes progressively less important with decreasing frequency: one might hope to detect a critical density of background radiation at frequencies below 10 -2 Hz and a background with 10 -4 times the critical density at frequencies below 10 -5 Hz. It is encouraging that some of the sorts of background which we anticipate from theoretical considerations fall within the observable regime. We discuss the extent to which other sources of noise may exceed the clock noise and the degree to which they can be eliminated
Energy Technology Data Exchange (ETDEWEB)
Rudolph, E [Max-Planck-Institut fuer Physik und Astrophysik, Muenchen (F.R. Germany)
1975-01-01
As a model for gravitational radiation damping of a planet the electromagnetic radiation damping of an extended charged body moving in an external gravitational field is calculated in harmonic coordinates using a weak field, slowing-motion approximation. Special attention is paid to the case where this gravitational field is a weak Schwarzschild field. Using Green's function methods for this purpose it is shown that in a slow-motion approximation there is a strange connection between the tail part and the sharp part: radiation reaction terms of the tail part can cancel corresponding terms of the sharp part. Due to this cancelling mechanism the lowest order electromagnetic radiation damping force in an external gravitational field in harmonic coordinates remains the flat space Abraham Lorentz force. It is demonstrated in this simplified model that a naive slow-motion approximation may easily lead to divergent higher order terms. It is shown that this difficulty does not arise up to the considered order.
Physics of radiation effects in crystals
Johnson, RA
1986-01-01
``Physics of Radiation Effects in Crystals'' is presented in two parts. The first part covers the general background and theory of radiation effects in crystals, including the theory describing the generation of crystal lattice defects by radiation, the kinetic approach to the study of the disposition of these defects and the effects of the diffusion of these defects on alloy compositions and phases. Specific problems of current interest are treated in the second part and include anisotropic dimensional changes in x-uranium, zirconium and graphite, acceleration of thermal creep in reactor ma
To a physical interpretation of a weak gravitational field in GRT
International Nuclear Information System (INIS)
Pavlov, N.V.
1981-01-01
The problem of separation of Newton components of weak vacuum gravitational fields is discussed. Chronometric- invariant (CI) characteristics of space-time and the corresponding Newton values are compared in the fixed systems of reference. Attention is paid to the following facts. ''Weak'' sources of weak gravitational fields do not interact gravitationally. If the CI characteristics of vacuum space- time permit series expansion in 1/c powers then the coefficients at odd 1/c powers are connected with the presence of non-gravitational material fields inside the sources. Masses producing gravitational field may not be the sources of gravitational waves in the form of which this field manifests itself. Perspectives of detecting laboratory gravitational waves are discussed: the simplest metrics of plane wave is considered in the quasi-inertial reference system; the flowsheet of the generator of this wave is suggested; relativistic oscillation of a test massive particle is calculated in the postnewtonian approximation. The numerical evaluations show that attempts of mechanical detection of laboratory gravitational waves are hopeless [ru
Some aspects of vacuum ultraviolet radiation physics
Damany, Nicole; Vodar, Boris
2013-01-01
Some Aspects of Vacuum Ultraviolet Radiation Physics presents some data on the state of research in vacuum ultraviolet radiation in association with areas of physics. Organized into four parts, this book begins by elucidating the optical properties of solids in the vacuum ultraviolet region (v.u.v.), particularly the specific methods of determination of optical constants in v.u.v., the properties of metals, and those of ionic insulators. Part II deals with molecular spectroscopy, with emphasis on the spectra of diatomic and simple polyatomic molecules, paraffins, and condensed phases. Part III
Gravitational wave emission from oscillating millisecond pulsars
Alford, Mark G.; Schwenzer, Kai
2015-02-01
Neutron stars undergoing r-mode oscillation emit gravitational radiation that might be detected on the Earth. For known millisecond pulsars the observed spin-down rate imposes an upper limit on the possible gravitational wave signal of these sources. Taking into account the physics of r-mode evolution, we show that only sources spinning at frequencies above a few hundred Hertz can be unstable to r-modes, and we derive a more stringent universal r-mode spin-down limit on their gravitational wave signal. We find that this refined bound limits the gravitational wave strain from millisecond pulsars to values below the detection sensitivity of next generation detectors. Young sources are therefore a more promising option for the detection of gravitational waves emitted by r-modes and to probe the interior composition of compact stars in the near future.
Detecting the Stochastic Gravitational-Wave Background
Colacino, Carlo Nicola
2017-12-01
The stochastic gravitational-wave background (SGWB) is by far the most difficult source of gravitational radiation detect. At the same time, it is the most interesting and intriguing one. This book describes the initial detection of the SGWB and describes the underlying mathematics behind one of the most amazing discoveries of the 21st century. On the experimental side it would mean that interferometric gravitational wave detectors work even better than expected. On the observational side, such a detection could give us information about the very early Universe, information that could not be obtained otherwise. Even negative results and improved upper bounds could put constraints on many cosmological and particle physics models.
Upper limits on gravitational-wave bursts radiated from stellar-core collapses in our galaxy
International Nuclear Information System (INIS)
Ando, Masaki; Akutsu, Tomomi; Akutsu, Tomotada
2005-01-01
We present the results of observations with the TAMA300 gravitational-wave detector, targeting burst signals from stellar-core collapse events. We used an excess-power filter to extract gravitational-wave candidates, and developed two methods to reduce fake events caused by non-stationary noises of the detector. These analysis methods were applied to real data from the TAMA300 interferometric gravitational wave detector. We compared the data-processed results with those of a Monte Carlo simulation with an assumed galactic-event distribution model and with burst waveforms expected from numerical simulations of stellar-core collapses, in order to interpret the event candidates from an astronomical viewpoint. We set an upper limit of 5.0 x 10 3 events s -1 on the burst gravitational-wave event rate in our galaxy with a confidence level of 90%
A Global Three-Dimensional Radiation Hydrodynamic Simulation of a Self-Gravitating Accretion Disk
Phillipson, Rebecca; Vogeley, Michael S.; McMillan, Stephen; Boyd, Patricia
2018-01-01
We present three-dimensional, radiation hydrodynamic simulations of initially thin accretion disks with self-gravity using the grid-based code PLUTO. We produce simulated light curves and spectral energy distributions and compare to observational data of X-ray binary (XRB) and active galactic nuclei (AGN) variability. These simulations are of interest for modeling the role of radiation in accretion physics across decades of mass and frequency. In particular, the characteristics of the time variability in various bandwidths can probe the timescales over which different physical processes dominate the accretion flow. For example, in the case of some XRBs, superorbital periods much longer than the companion orbital period have been observed. Smoothed particle hydrodynamics (SPH) calculations have shown that irradiation-driven warping could be the mechanism underlying these long periods. In the case of AGN, irradiation-driven warping is also predicted to occur in addition to strong outflows originating from thermal and radiation pressure driving forces, which are important processes in understanding feedback and star formation in active galaxies. We compare our simulations to various toy models via traditional time series analysis of our synthetic and observed light curves.
Modified gravity (MOG), the speed of gravitational radiation and the event GW170817/GRB170817A
Green, M. A.; Moffat, J. W.; Toth, V. T.
2018-05-01
Modified gravity (MOG) is a covariant, relativistic, alternative gravitational theory whose field equations are derived from an action that supplements the spacetime metric tensor with vector and scalar fields. Both gravitational (spin 2) and electromagnetic waves travel on null geodesics of the theory's one metric. MOG satisfies the weak equivalence principle and is consistent with observations of the neutron star merger and gamma ray burster event GW170817/GRB170817A.
Atomic physics research with synchrotron radiation
International Nuclear Information System (INIS)
Crasemann, B.
1981-01-01
Applications of synchrotron radiation to research in high-energy atomic physics are summarized. These lie in the areas of photoelectron spectrometry, photon scattering, x-ray absorption spectroscopy, time-resolved measurements, resonance spectroscopy and threshold excitation, and future, yet undefined studies
Zheng, Yahui; Hao, Binzheng; Wen, Yaxiang; Liu, Xiaojun
2018-01-01
The evolution of the Tsallis entropy in self-gravitating systems and plasmas is studied in this letter, which is determined by two factors. The first factor is the change of the microstate number of systems, whose spontaneous increase leads to the entropy's increase, consistent with the standard text book. The second is the evolution of the nonextensive parameter, whose evolution rate to time is opposite to the one of entropy. We find the correlation between heat radiation and time evolution of the nonextensive parameter in the self-gravitating systems and plasmas. In such systems, the emission of radiation heat leads to the increase of the parameter while the absorption of radiation heat results in the decrease of this parameter. This is consistent with the inference derived from the Clausius' definition of entropy. In order to evolve to the current state, the solar corona should absorb a large amount of radiation heat, which might be originated from the energy released by solar flare. The magnetic connection probably plays a role in the conversion of energy. A correct dynamics theory of magnetic connection should explain how the energy conversion is achieved.
Directory of Open Access Journals (Sweden)
Canuel B.
2014-01-01
Full Text Available We are building a hybrid detector of new concept that couples laser and matter-wave interferometry to study sub Hertz variations of the strain tensor of space-time and gravitation. Using a set of atomic interferometers simultaneously manipulated by the resonant optical field of a 200 m cavity, the MIGA instrument will allow the monitoring of the evolution of the gravitational field at unprecedented sensitivity, which will be exploited both for geophysical studies and for Gravitational Waves (GWs detection. This new infrastructure will be embedded into the LSBB underground laboratory, ideally located away from major anthropogenic disturbances and benefitting from very low background noise.
Dodelson, Scott
2017-01-01
Gravitational lensing is a consequence of general relativity, where the gravitational force due to a massive object bends the paths of light originating from distant objects lying behind it. Using very little general relativity and no higher level mathematics, this text presents the basics of gravitational lensing, focusing on the equations needed to understand the phenomena. It then applies them to a diverse set of topics, including multiply imaged objects, time delays, extrasolar planets, microlensing, cluster masses, galaxy shape measurements, cosmic shear, and lensing of the cosmic microwave background. This approach allows undergraduate students and others to get quickly up to speed on the basics and the important issues. The text will be especially relevant as large surveys such as LSST and Euclid begin to dominate the astronomical landscape. Designed for a one semester course, it is accessible to anyone with two years of undergraduate physics background.
The physical principles of radiation protection
International Nuclear Information System (INIS)
Lokan, K.H.
1990-01-01
This lecture reviews the production of ionising radiation from the naturally occurring radioactive decay chains and introduces the mathematical expressions relating to secular equilibrium and the calculation of the activity of daughter products. The absorption of α, β and γ radiation is discussed from the point of view of the physical processes which occur, e.g. the photoelectric, Compton and pair production processes for γ-rays. Linear energy transfer and range-energy relationships are discussed for α and β particles. Units of measurement for ionising radiation, relative biological effectiveness, dose equivalence and quality factors for each type of radiation are reviewed. the behaviour and properties of radon, thoron and their daughter products are described, and units used in the assessments of effective dose from radon daughters are discussed. 16 refs., 1 tab., 15 figs
The physical principles of radiation protection
International Nuclear Information System (INIS)
Lokan, K.H.
1982-01-01
The production of ionising radiation from the naturally occurring radioactive decay chains is reviewed and mathematical expressions relating to secular equilibrium and the calculation of the activity of daughter products are introduced. The absorption of α, β and γ radiation is discussed from the point of view of the physical processes which occur, e.g. the photoelectric, Compton and pair production processes for γ-rays. Linear energy transfer (LET) and range-energy relationships are discussed for α and β particles. Units of measurement for ionising radiation, relative biological effectiveness, dose equivalence and quality factors for each type of radiation are reviewed. The behaviour and properties of radon, thoron and their daughter products are described, and the definition of the Working Level introduced
Integration of radiation and physical safety in large radiator facilities
International Nuclear Information System (INIS)
Lima, P.P.M.; Benedito, A.M.; Lima, C.M.A.; Silva, F.C.A. da
2017-01-01
Growing international concern about radioactive sources after the Sept. 11, 2001 event has led to a strengthening of physical safety. There is evidence that the illicit use of radioactive sources is a real possibility and may result in harmful radiological consequences for the population and the environment. In Brazil there are about 2000 medical, industrial and research facilities with radioactive sources, of which 400 are Category 1 and 2 classified by the - International Atomic Energy Agency - AIEA, where large irradiators occupy a prominent position due to the very high cobalt-60 activities. The radiological safety is well established in these facilities, due to the intense work of the authorities in the Country. In the paper the main aspects on radiological and physical safety applied in the large radiators are presented, in order to integrate both concepts for the benefit of the safety as a whole. The research showed that the items related to radiation safety are well defined, for example, the tests on the access control devices to the irradiation room. On the other hand, items related to physical security, such as effective control of access to the company, use of safety cameras throughout the company, are not yet fully incorporated. Integration of radiation and physical safety is fundamental for total safety. The elaboration of a Brazilian regulation on the subject is of extreme importance
Introduction to radiological physics and radiation dosimetry
Attix, Frank Herbert
2004-01-01
A straightforward presentation of the broad concepts underlying radiological physics and radiation dosimetry for the graduate-level student. Covers photon and neutron attenuation, radiation and charged particle equilibrium, interactions of photons and charged particles with matter, radiotherapy dosimetry, as well as photographic, calorimetric, chemical, and thermoluminescence dosimetry. Includes many new derivations, such as Kramers X-ray spectrum, as well as topics that have not been thoroughly analyzed in other texts, such as broad-beam attenuation and geometrics, and the reciprocity theorem
Fundamentals of health physics for the radiation-protection officer
Energy Technology Data Exchange (ETDEWEB)
Murphy, B.L.; Traub, R.J.; Gilchrist, R.L.; Mann, J.C.; Munson, L.H.; Carbaugh, E.H.; Baer, J.L.
1983-03-01
The contents of this book on health physics include chapters on properties of radioactive materials, radiation instrumentation, radiation protection programs, radiation survey programs, internal exposure, external exposure, decontamination, selection and design of radiation facilities, transportation of radioactive materials, radioactive waste management, radiation accidents and emergency preparedness, training, record keeping, quality assurance, and appraisal of radiation protection programs. (ACR)
Fundamentals of health physics for the radiation-protection officer
International Nuclear Information System (INIS)
Murphy, B.L.; Traub, R.J.; Gilchrist, R.L.; Mann, J.C.; Munson, L.H.; Carbaugh, E.H.; Baer, J.L.
1983-03-01
The contents of this book on health physics include chapters on properties of radioactive materials, radiation instrumentation, radiation protection programs, radiation survey programs, internal exposure, external exposure, decontamination, selection and design of radiation facilities, transportation of radioactive materials, radioactive waste management, radiation accidents and emergency preparedness, training, record keeping, quality assurance, and appraisal of radiation protection programs
Nath, G.; Vishwakarma, J. P.
2016-11-01
Similarity solutions are obtained for the flow behind a spherical shock wave in a non-ideal gas under gravitational field with conductive and radiative heat fluxes, in the presence of a spatially decreasing azimuthal magnetic field. The shock wave is driven by a piston moving with time according to power law. The radiation is considered to be of the diffusion type for an optically thick grey gas model and the heat conduction is expressed in terms of Fourier's law for heat conduction. Similarity solutions exist only when the surrounding medium is of constant density. The gas is assumed to have infinite electrical conductivity and to obey a simplified van der Waals equation of state. It is shown that an increase of the gravitational parameter or the Alfven-Mach number or the parameter of the non-idealness of the gas decreases the compressibility of the gas in the flow-field behind the shock, and hence there is a decrease in the shock strength. The pressure and density vanish at the inner surface (piston) and hence a vacuum is formed at the center of symmetry. The shock waves in conducting non-ideal gas under gravitational field with conductive and radiative heat fluxes can be important for description of shocks in supernova explosions, in the study of a flare produced shock in the solar wind, central part of star burst galaxies, nuclear explosion etc. The solutions obtained can be used to interpret measurements carried out by space craft in the solar wind and in neighborhood of the Earth's magnetosphere.
Future gravitational physics tests from ranging to the BepiColombo Mercury planetary orbiter
International Nuclear Information System (INIS)
Ashby, Neil; Bender, Peter L.; Wahr, John M.
2007-01-01
Milani et al. recently have published careful and fundamental studies of the accuracy with which both gravitational physics information and the solar quadrupole moment can be obtained from Earth-Mercury distance data. To complement these results, a quite different analysis method is used in the present paper. We calculate the first-order corrections to the Keplerian motion of a single planet around the Sun due to the parameterized post-Newtonian theory parameters β, γ, α 1 , α 2 , and ξ, as well as corrections due to the solar quadrupole moment J 2 and a possible secular change in GM · . The Nordtvedt parameter η that is used in tests of the strong equivalence principle also is included in this analysis. The expected accuracies are given for 1 yr, 2 yr, and 8 yr mission durations, assuming that the planet-planet and asteroid-planet perturbations are accurately known. The ''modified worst-case'' error analysis method that we use is quite different from the usual covariance analysis method based on assumed uncorrelated random errors, plus a bias that is fixed or that changes in a prescribed way. We believe this is appropriate because systematic measurement errors are likely to be the main limitation on the accuracy of the results. Our final estimated uncertainties are one-third of the errors that would result if a 4.5-cm rms systematic error had the most damaging possible variation with time. We discuss the resulting uncertainties for several different subsets of orbital and relativity parameters
Exercises with solutions in radiation physics
Nilsson, Bo N
2015-01-01
The textbook begins with exercises related to radioactive sources and decay schemes. The problems covered include series decay and how to determine the frequency and energy of emitted particles in disintegrations. The next chapter deals with the interaction of ionizing radiation, including the treatment of photons and charged particles. The main focus is on applications based on the knowledge of interaction, to be used in subsequent work and courses. The textbook then examines detectors and measurements, including both counting statistics and properties of pulse detectors. The chapter that follows is dedicated to dosimetry, which is a major subject in medical radiation physics. It covers theoretical applications, such as different equilibrium situations and cavity theories, as well as experimental dosimetry, including ionization chambers and solid state and liquid dosimeters. A shorter chapter deals with radiobiology, where different cell survival models are considered. The last chapter concerns radiation pro...
Progress in medical radiation physics. Vol. 1
International Nuclear Information System (INIS)
Orton, C.G.
1982-01-01
This book is the first of a series that will provide in-depth reviews of new developments in medical radiation physics. This volume is directed toward application scientists who are involved with research in this field. Six chapters review current topics in medical radiation physics. The first chapter reviews neutron dosimetry for biomedical applications. The second chapter briefly surveys current tissue inhomogeneity corrections in proton-beam treatment planning. Chapter three deals with anthropomorphic phantom materials. It includes a useful table of recommended tissue substitutes and information on manufacturing. The fourth chapter reviews applications of computed tomography (CT) in radiotherapy treatment planning. Chapter five is a short introduction to positron imaging. The last chapter describes optical methods for radiograph storage
Dark Energy and Dark Matter Phenomena and the Universe with Variable Gravitational Mass
Gorkavyi, N.
2005-12-01
Generation of high-frequency gravitational waves near the singularity is a crucial factor for understanding the origin and dynamics of the Universe. Emission of gravitational waves increases with a decreasing radius of collapsed object much faster than a gravitational force itself. Gravitationally unstable matter of the Universe will be completely converted into gravitational radiation during the Big Crunch. According to Misner, Thorne & Wheeler (Gravitation, 1977, p.959) plane gravitational waves have not gravitational mass or spacetime is flat everywhere outside the pulse. We can propose that the gravitational mass of the Universe is vanished after converting matter into gravitational waves. This hypothesis in the framework of Einstein's theory of gravitation can solve the problem of singularity without contradiction with theorems by Penrose-Hawking; explain the acceleration of our Universe as the effect of a retarded gravitational potential (Gorkavyi, BAAS, 2003, 35, #3) and the low quadrupole in fluctuations in CMB as result of blue-shift effect in a gravitational field. Proposed solution of dark energy problem free from coincidence problems. The hypothesis keeps best parts of Big Bang theory and inflation model without any unknown physical fields or new dimensions. According to this hypothesis a relic sea of high-frequency gravitational radiation in our Universe can be very dense. Interaction of relic gravitational waves with gravitational fields of galaxies and stars can create an additional dynamical effects like pressure of relic radiation that proportional to gravitational potential GM/(Rc2). This effect can be responsible for dark matter phenomena in galaxies and the Pioneer acceleration in the solar system (Gorkavyi, BAAS, 2005, 37, #2).
Abstracts of 21. International Symposium Radiation Protection Physics
International Nuclear Information System (INIS)
1989-01-01
45 papers are presented as titles with abstracts which are processed individually for the INIS data base. They deal with general aspects of radiation protection physics, chiefly problems of radiation detection and measuring techniques in radiation protection
CERN. Geneva HR-RFA
2006-01-01
We will present a brief introduction to the physics of gravitational waves and their properties. We will review potential astrophysical sources of gravitational waves, and the physics and astrophysics that can be learned from their study. We will survey the techniques and technologies for detecting gravitational waves for the first time, including bar detectors and broadband interferometers, and give a brief status report on the international search effort.
Foundations of radiation physics and radiation protection. 5. ed.
International Nuclear Information System (INIS)
Krieger, Hanno
2017-01-01
The following topics are dealt with: Types of radiation and radiation fields, the atomic structure, radioactive decays, decay law, natural and artificial radioactivity, interactions of ionizing photon radiation, attenuation of neutral-particle beams, interactions of neutron radiation, interactions of charged particles, ionization and energy transfer, radiation doses, radiation protection phantoms, foundations of the radiation biology of cells, effects and risks of ionizing radiation, radiation expositions of men with ionizing radiation, radiation protection law, practical radiation protection against ionizing radiations, radiation eposures in medical radiology. (HSI)
Proceedings of the third Radiation Physics Conference. Vol. 2
International Nuclear Information System (INIS)
Gomaa, M.A.; El-Behay, A.Z.; Hassib, G.M.; El-Naggar, A.M.
1996-01-01
The conference of radiation physics was held in 13-17 Nov. 1996 in cairo. The specialists of atomic energy authority and Al-Minia University discussed the biological radiation effects,radiation protection, applied radiation physics and material shielding studies were discussed at the meeting more than 400 page were presented
Proceedings of the 4. International Symposium on Radiation Physics - Abstracts
International Nuclear Information System (INIS)
1988-01-01
The studies on: fundamental processes in radiation physics; radiation sources and detectors; physical, chemical and biological radiation effects; plasma technology; radioisotope application in medicine and agriculture; environment; use of radiation in material science and; reactor technology, are presented. (M.C.K.) [pt
Proceedings of the third Radiation Physics Conference. Vol. 2
Energy Technology Data Exchange (ETDEWEB)
Gomaa, M A; El-Behay, A Z; Hassib, G M; El-Naggar, A M [eds.
1997-12-31
The conference of radiation physics was held in 13-17 Nov. 1996 in cairo. The specialists of atomic energy authority and Al-Minia University discussed the biological radiation effects,radiation protection, applied radiation physics and material shielding studies were discussed at the meeting more than 400 page were presented.
Astronomy's New Messengers: A traveling exhibit on gravitational-wave physics
International Nuclear Information System (INIS)
Cavaglia, Marco; Hendry, Martin; Marka, Szabolcs; Reitze, David H; Riles, Keith
2010-01-01
The Laser Interferometer Gravitational-wave Observatory exhibit Astronomy's New Messengers: Listening to the Universe with Gravitational Waves is traveling to colleges, universities, museums and other public institutions throughout the United States. Astronomy's New Messengers primarily communicates with an adolescent and young adult audience, potentially inspiring them into the field of science. Acknowledging that this audience is traditionally a difficult one to attract, the exhibit publicly announces itself in a charismatic fashion to reach its principal goals of broadening the community of people interested in science and encouraging interest in science among young people.
EMERALD - Vocational training in medical radiation physics
International Nuclear Information System (INIS)
Lewis, C.A.; Tabakov, S.D.; Roberts, V.C.
2000-01-01
EMERALD (European MEdiation RAdiation Learning Development) is a project funded by the European Union under the Leonardo da Vinci programme. It involves a collaboration between Universities and Hospitals from the UK, Sweden, Italy and Portugal. The aim of the EMERALD project is to develop and deliver three common transnational vocational training modules in Medical Radiation Physics in the specific areas of Diagnostic Radiology, Nuclear Medicine and Radiotherapy. These modules are intended to be used in the training programme for young professionals involved in medical radiation physics. Each module is developed from a series of competencies. The competencies are acquired by undertaking practical tasks described in a workbook given to each trainee. Once the task has been completed the trainee discusses the results and observations with his supervisor to ensure that the appropriate competency has been achieved. In addition to the workbook, each trainee receives a CD-ROM containing a series of images to help describe each task. The workbooks for each subject area have been completed and students from Sweden have undertaken Diagnostic Radiology training in the United Kingdom using this approach. The project is now entering the next phase; to develop a multimedia version of the workbook. (author)
Energy Technology Data Exchange (ETDEWEB)
Errard, Josquin [Sorbonne Universités, Institut Lagrange de Paris (ILP), 98 bis Boulevard Arago, 75014 Paris (France); Feeney, Stephen M.; Jaffe, Andrew H. [Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom); Peiris, Hiranya V., E-mail: josquin.errard@lpnhe.in2p3.fr, E-mail: s.feeney@imperial.ac.uk, E-mail: h.peiris@ucl.ac.uk, E-mail: a.jaffe@imperial.ac.uk [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)
2016-03-01
Recent results from the BICEP, Keck Array and Planck Collaborations demonstrate that Galactic foregrounds are an unavoidable obstacle in the search for evidence of inflationary gravitational waves in the cosmic microwave background (CMB) polarization. Beyond the foregrounds, the effect of lensing by intervening large-scale structure further obscures all but the strongest inflationary signals permitted by current data. With a plethora of ongoing and upcoming experiments aiming to measure these signatures, careful and self-consistent consideration of experiments' foreground- and lensing-removal capabilities is critical in obtaining credible forecasts of their performance. We investigate the capabilities of instruments such as Advanced ACTPol, BICEP3 and Keck Array, CLASS, EBEX10K, PIPER, Simons Array, SPT-3G and SPIDER, and projects as COrE+, LiteBIRD-ext, PIXIE and Stage IV, to clean contamination due to polarized synchrotron and dust from raw multi-frequency data, and remove lensing from the resulting co-added CMB maps (either using iterative CMB-only techniques or through cross-correlation with external data). Incorporating these effects, we present forecasts for the constraining power of these experiments in terms of inflationary physics, the neutrino sector, and dark energy parameters. Made publicly available through an online interface, this tool enables the next generation of CMB experiments to foreground-proof their designs, optimize their frequency coverage to maximize scientific output, and determine where cross-experimental collaboration would be most beneficial. We find that analyzing data from ground, balloon and space instruments in complementary combinations can significantly improve component separation performance, delensing, and cosmological constraints over individual datasets. In particular, we find that a combination of post-2020 ground- and space-based experiments could achieve constraints such as σ(r)∼1.3×10{sup −4}, σ(n{sub t})∼0
Directory of Open Access Journals (Sweden)
Sandra Regina Teodoro Gatti
2010-03-01
Full Text Available We report here some outcomes of a research related to a didactical experience aiming to integrate the History of Science to the Physics Teaching, taking as background the historical development of the gravitational attraction. The research, of qualitative approach, is a case study and it was carried out in a sample of eleven students belonging to an undergraduate physics program (called licenciatura in Brazil designed to from High School physics teachers in a São Paulo State Public University. We tried initially to reveal prospective teachers’ conceptions in order to provide a prepare that was used to guide the activities from the reality’s diagnosis. The aim was to promote discussions on the existence and persistence of alternative conceptions, on the historical evolution of the subject gravitational attraction, through readings and debates of texts contemplating recent subjects on the Science Education research, in order to generate dissatisfaction with traditional teaching models. The future High School physics teachers were asked to construct their own teaching proposal, through the development, in real situations, in a High School, of a mini-course based on: debates and synthesis developed in University classroom, the History of the Science and the student’s alternative conceptions. In this paper we will analyze future teachers’ alternative conceptions, the development of the course proposed, and details of the mini-courses taught by the prospective teachers in real situations, among High School students, its coherence and the posture changes observed in them.
Metric elasticity in a collapsing star: Gravitational radiation coupled to torsional motion
International Nuclear Information System (INIS)
Gerlach, U.H.; Scott, J.F.
1986-01-01
Torsional oscillatory matter motion as well as differential rotation couple via the linearized Einstein field equations to the gravitational degrees of freedom. For an arbitrary spherically symmetric background, such as that of a wildly pulsating or a catastrophically collapsing star, we exhibit (a) the strain tensor and (b) the corresponding stress-energy tensor. It is found that in the star there are two elasticity tensors. One expresses the familiar elasticity of matter, the other expresses the elasticity of the geometry. This metric elasticity is responsible for coupling the gravitational and matter degrees of freedom. The two coupled scalar wave equations for these degrees of freedom are exhibited. Also exhibited are their characteristics as well as the junction conditions for their solutions across any spherical surface of discontinuity
Physics for radiation protection. 3. upd. ed.
Energy Technology Data Exchange (ETDEWEB)
Martin, James E.
2013-09-01
A highly practical resource for health physicists and other professionals in radiation protection. This third edition has been completely revised and updated with an emphasis on basic concepts as they apply to radiation issues such as the incident at the Fukushima-Daichi plant in Japan. Designed for readers with limited as well as basic science backgrounds, the book presents thorough and up-to-date explanations of radiation physics and the major concepts that underpin it. Extensive discussion is provided of radioactivity, including sources, materials and decay schemes for about 100 of the most common radionuclides encountered by practitioners. The text emphasizes practical calculations for radiation sources and levels in the workplace and the environment, and presents methods, including shielding, for modifying them. Comprehensive appendices and more than 400 figures are provided for such calculations; these are based on current resource data. Excerpts from the Chart of the Nuclides, activation cross sections, fission yields, fission-product chains, photon attenuation coefficients, and nuclear masses are also provided. Real-world examples and exercises demonstrate concepts and their use.
International Nuclear Information System (INIS)
Vega, H.J. de; Sanchez, N.
2002-01-01
We complete our study of the self-gravitating gas by computing the fluctuations around the saddle point solution for the three statistical ensembles (grand canonical, canonical and microcanonical). Although the saddle point is the same for the three ensembles, the fluctuations change from one ensemble to the other. The zeroes of the small fluctuations determinant determine the position of the critical points for each ensemble. This yields the domains of validity of the mean field approach. Only the S-wave determinant exhibits critical points. Closed formulae for the S- and P-wave determinants of fluctuations are derived. The local properties of the self-gravitating gas in thermodynamic equilibrium are studied in detail. The pressure, energy density, particle density and speed of sound are computed and analyzed as functions of the position. The equation of state turns out to be locally p(r→ )=Tρ V (r→ ) as for the ideal gas. Starting from the partition function of the self-gravitating gas, we prove in this microscopic calculation that the hydrostatic description yielding locally the ideal gas equation of state is exact in the N=∞ limit. The dilute nature of the thermodynamic limit (N∼L→∞ with N/L fixed) together with the long range nature of the gravitational forces play a crucial role in obtaining such ideal gas equation. The self-gravitating gas being inhomogeneous, we have PV/[NT]=f(η)≤1 for any finite volume V. The inhomogeneous particle distribution in the ground state suggests a fractal distribution with Haussdorf dimension D, D is slowly decreasing with increasing density, 1< D<3. The average distance between particles is computed in Monte Carlo simulations and analytically in the mean field approach. A dramatic drop at the phase transition is exhibited, clearly illustrating the properties of the collapse
Gravitational Radiation - a New Window Onto the Universe. (Karl Schwarzschild Lecture 1996)
Thorne, K. S.
A summary is given of the current status and plans for gravitational-wave searches at all plausible wavelengths, from the size of the observable universe to a few kilometers. The anticipated scientific payoff from these searches is described, including expectations for detailed studies of black holes and neutron stars, high-accuracy tests of general relativity, and hopes for the discovery of exotic new kinds of objects.
Radiative and Excited State Charmonium Physics
Energy Technology Data Exchange (ETDEWEB)
Jozef Dudek
2007-07-30
Renewed interest in the spectroscopy of charmonium has arisen from recent unexpected observations at $e^+e^-$ colliders. Here we report on a series of works from the previous two years examining the radiative physics of charmonium states as well as the mass spectrum of states of higher spin and internal excitation. Using new techniques applied to Domain-Wall and Clover quark actions on quenched isotropic and anisotropic lattices, radiative transitions and two-photon decays are considered for the first time. Comparisons are made with experimental results and with model approaches. Forthcoming application to the light-quark sector of relevance to experiments like Jefferson Lab's GlueX is discussed.
Human radiation experimentation: a health physics perspective
International Nuclear Information System (INIS)
Kathren, R.L.
1996-01-01
This paper observes ethical human experimentation can be considered in terms of two basic principles or tests: informed, willing and knowledgeable subjects; and expectation of benefits. A number of human experiments are evaluated in terms of these principles, including a sixteenth century toxicology experiment, the deliberate exposure by an x-ray pioneer, and the plutonium injection cases of the 1940's. The following rational ethic is proposed for the practice of health physics with respect to human radiation experimentation: At all levels, the health physicist has a professional as well as personal obligation to ensure that proper human requirements, including proper informed consent and willing subjects, arc carried out with respect to human radiation experimentation, and must be convinced that the real or potential benefits to be derived from the experiment clearly exceed the potential detriment and risk. (author)
Theory of gravitational interactions
Gasperini, Maurizio
2017-01-01
This is the second edition of a well-received book that is a modern, self-contained introduction to the theory of gravitational interactions. The new edition includes more details on gravitational waves of cosmological origin, the so-called brane world scenario, and gravitational time-delay effects. The first part of the book follows the traditional presentation of general relativity as a geometric theory of the macroscopic gravitational field, while the second, more advanced part discusses the deep analogies (and differences) between a geometric theory of gravity and the “gauge” theories of the other fundamental interactions. This fills a gap within the traditional approach to general relativity which usually leaves students puzzled about the role of gravity. The required notions of differential geometry are reduced to the minimum, allowing room for aspects of gravitational physics of current phenomenological and theoretical interest, such as the properties of gravitational waves, the gravitational inter...
Ciufolini, I; Moschella, U; Fre, P
2001-01-01
Gravitational waves (GWs) are a hot topic and promise to play a central role in astrophysics, cosmology, and theoretical physics. Technological developments have led us to the brink of their direct observation, which could become a reality in the coming years. The direct observation of GWs will open an entirely new field: GW astronomy. This is expected to bring a revolution in our knowledge of the universe by allowing the observation of previously unseen phenomena, such as the coalescence of compact objects (neutron stars and black holes), the fall of stars into supermassive black holes, stellar core collapses, big-bang relics, and the new and unexpected.With a wide range of contributions by leading scientists in the field, Gravitational Waves covers topics such as the basics of GWs, various advanced topics, GW detectors, astrophysics of GW sources, numerical applications, and several recent theoretical developments. The material is written at a level suitable for postgraduate students entering the field.
International Nuclear Information System (INIS)
Smalley, L.L.; Alabama Univ., Huntsville
1983-01-01
It is shown that (1) the proper framework for testing Rastall's theory and its generalisations is in the case of non-negligible (i.e. discernible) gravitational effects such as gravity gradients; 2) these theories have conserved integral four-momentum and angular momentum; and (3) the Nordtvedt effect then provides limits on the parameters which arise as the result of the non-zero divergence of the energy-momentum tensor. (author)
Smalley, L. L.
1983-01-01
The proper framework for testing Rastall's theory and its generalizations is in the case of non-negligible (i.e. discernible) gravitational effects such as gravity gradients. These theories have conserved integral four-momentum and angular momentum. The Nordtvedt effect then provides limits on the parameters which arise as the result of the non-zero divergence of the energy-momentum tensor.
International Nuclear Information System (INIS)
Babak, S; Balasubramanian, R; Churches, D; Cokelaer, T; Sathyaprakash, B S
2006-01-01
Gravitational waves from coalescing compact binaries are searched for using the matched filtering technique. As the model waveform depends on a number of parameters, it is necessary to filter the data through a template bank covering the astrophysically interesting region of the parameter space. The choice of templates is defined by the maximum allowed drop in signal-to-noise ratio due to the discreteness of the template bank. In this paper we describe the template-bank algorithm that was used in the analysis of data from the Laser Interferometer Gravitational Wave Observatory (LIGO) and GEO 600 detectors to search for signals from binaries consisting of non-spinning compact objects. Using Monte Carlo simulations, we study the efficiency of the bank and show that its performance is satisfactory for the design sensitivity curves of ground-based interferometric gravitational wave detectors GEO 600, initial LIGO, advanced LIGO and Virgo. The bank is efficient in searching for various compact binaries such as binary primordial black holes, binary neutron stars, binary black holes, as well as a mixed binary consisting of a non-spinning black hole and a neutron star
Optimisation and symmetry in experimental radiation physics
International Nuclear Information System (INIS)
Ghose, A.
1988-01-01
The present monograph is concerned with the optimisation of geometric factors in radiation physics experiments. The discussions are essentially confined to those systems in which optimisation is equivalent to symmetrical configurations of the measurement systems. They include, measurements of interaction cross section of diverse types, determination of polarisations, development of detectors with almost ideal characteristics, production of radiations with continuously variable energies and development of high efficiency spectrometers etc. The monograph is intended for use by experimental physicists investigating primary interactions of radiations with matter and associated technologies. We have illustrated the various optimisation procedures by considering the cases of the so-called ''14 MeV'' on d-t neutrons and gamma rays with energies less than 3 MeV. Developments in fusion technology are critically dependent on the availability accurate cross sections of nuclei for fast neutrons of energies at least as high as d-t neutrons. In this monograph we have discussed various techniques which can be used to improve the accuracy of such measurements and have also presented a method for generating almost monoenergetic neutrons in the 8 MeV to 13 MeV energy range which can be used to measure cross sections in this sparingly investigated region
International Nuclear Information System (INIS)
Yu Yunwei; Cao Xiaofeng; Zheng Xiaoping
2009-01-01
In a second-order r-mode theory, Sa and Tome found that the r-mode oscillation in neutron stars (NSs) could induce stellar differential rotation, which naturally leads to a saturated state of the oscillation. Based on a consideration of the coupling of the r-modes and the stellar spin and thermal evolution, we carefully investigate the influences of the differential rotation on the long-term evolution of isolated NSs and NSs in low-mass X-ray binaries, where the viscous damping of the r-modes and its resultant effects are taken into account. The numerical results show that, for both kinds of NSs, the differential rotation can significantly prolong the duration of the r-modes. As a result, the stars can keep nearly a constant temperature and constant angular velocity for over a thousand years. Moreover, the persistent radiation of a quasi-monochromatic gravitational wave would also be predicted due to the long-term steady r-mode oscillation and stellar rotation. This increases the detectability of gravitational waves from both young isolated and old accreting NSs. (research papers)
Proceedings of the third Radiation Physics Conference. Vol. 1
Energy Technology Data Exchange (ETDEWEB)
Gomaa, M A; El-Behay, A Z; Hassib, G M; El-Naggar, A M [eds.
1997-12-31
The conference of radiation physics was held in 13-17 Nov. 1996 in Cairo. The specialists of Atomic energy authority and Al-Minia University disscused the biological radiation effects, applied radiation physics, radon measurements and material shielding. Studies were discussed at the meeting more than 300 pag. were presented.
Prospective Physics Teachers' Awareness of Radiation and Radioactivity
Tasoglu, Aslihan Kartal; Ates, Özlem; Bakaç, Mustafa
2015-01-01
The purpose of this study is to investigate prospective physics teachers' knowledge of and attitude towards radiation and radioactivity. Participants of this study are 56 prospective physics teachers. A questionnaire related with the knowledge about radiation and radiation fear was conducted. The results of this study showed that most of the…
Proceedings of the third Radiation Physics Conference. Vol. 1
International Nuclear Information System (INIS)
Gomaa, M.A.; El-Behay, A.Z.; Hassib, G.M.; El-Naggar, A.M.
1996-01-01
The conference of radiation physics was held in 13-17 Nov. 1996 in Cairo. The specialists of Atomic energy authority and Al-Minia University disscused the biological radiation effects, applied radiation physics, radon measurements and material shielding. Studies were discussed at the meeting more than 300 pag. were presented
Interaction of gravitational waves with magnetic and electric fields
International Nuclear Information System (INIS)
Barrabes, C.; Hogan, P. A.
2010-01-01
The existence of large-scale magnetic fields in the universe has led to the observation that if gravitational waves propagating in a cosmological environment encounter even a small magnetic field then electromagnetic radiation is produced. To study this phenomenon in more detail we take it out of the cosmological context and at the same time simplify the gravitational radiation to impulsive waves. Specifically, to illustrate our findings, we describe the following three physical situations: (1) a cylindrical impulsive gravitational wave propagating into a universe with a magnetic field, (2) an axially symmetric impulsive gravitational wave propagating into a universe with an electric field and (3) a 'spherical' impulsive gravitational wave propagating into a universe with a small magnetic field. In cases (1) and (3) electromagnetic radiation is produced behind the gravitational wave. In case (2) no electromagnetic radiation appears after the wave unless a current is established behind the wave breaking the Maxwell vacuum. In all three cases the presence of the magnetic or electric fields results in a modification of the amplitude of the incoming gravitational wave which is explicitly calculated using the Einstein-Maxwell vacuum field equations.
Abstracts of 20. International Symposium Radiation Protection Physics
International Nuclear Information System (INIS)
1988-01-01
51 papers are presented as titles with abstracts which are processed individually for the INIS data base. They deal with general aspects of radiation protection physics, international activities in radiation protection, solid state dosimetry, models and calculation methods in radiation protection, and measuring techniques in radiation protection
Proceedings of the Seventh Radiation Physics and Protection Conference (RPC-2004)
International Nuclear Information System (INIS)
2005-04-01
The Conference of radiation physics and protection was held on 27-30 November, 2004 in Egypt. the specialists discussed radiation physics and protection, fundamental radiation physics and application, Natural and man made radiation sources and radiation measurements, radiation protection and environmental, applied radiation physics, physics in medicine and biology were disscused at the conference. More than 800 papers were presented in the conference
Some method for teaching physics to residents in radiation therapy
International Nuclear Information System (INIS)
Hughes, D.B.
A method is presented for teaching physics to residents in radiation therapy. Some of the various responsabilities of a hospital physicist are listed, with particular reference to radiation therapy departments [pt
Lunar Laser Ranging Science: Gravitational Physics and Lunar Interior and Geodesy
Williams, James G.; Turyshev, Slava G.; Boggs, Dale H.; Ratcliff, J. Todd
2004-01-01
Laser pulses fired at retroreflectors on the Moon provide very accurate ranges. Analysis yields information on Earth, Moon, and orbit. The highly accurate retroreflector positions have uncertainties less than a meter. Tides on the Moon show strong dissipation, with Q=33+/-4 at a month and a weak dependence on period. Lunar rotation depends on interior properties; a fluid core is indicated with radius approx.20% that of the Moon. Tests of relativistic gravity verify the equivalence principle to +/-1.4x10(exp -13), limit deviations from Einstein's general relativity, and show no rate for the gravitational constant G/G with uncertainty 9x10(exp -13)/yr.
Hoffmann, William F
1964-01-01
Remarks on the observational basis of general relativity ; Riemannian geometry ; gravitation as geometry ; gravitational waves ; Mach's principle and experiments on mass anisotropy ; the many faces of Mach ; the significance for the solar system of time-varying gravitation ; relativity principles and the role of coordinates in physics ; the superdense star and the critical nucleon number ; gravitation and light ; possible effects on the solar system of φ waves if they exist ; the Lyttleton-Bondi universe and charge equality ; quantization of general relativity ; Mach's principle as boundary condition for Einstein's equations.
Nanouris, N.; Kalimeris, A.; Antonopoulou, E.; Rovithis-Livaniou, H.
2015-03-01
Context. The credibility of an eclipse timing variation (ETV) diagram analysis is investigated for various manifestations of the mass transfer and gravitational radiation processes in binary systems. The monotonicity of the period variations and the morphology of the respective ETV diagrams are thoroughly explored in both the direct impact and the accretion disk mode of mass transfer, accompanied by different types of mass and angular momentum losses (through a hot-spot emission from the gainer and via the L2/L3 points). Aims: Our primary objective concerns the traceability of each physical mechanism by means of an ETV diagram analysis. Also, possible critical mass ratio values are sought for those transfer modes that involve orbital angular momentum losses strong enough to dictate the secular period changes even when highly competitive mechanisms with the opposite direction act simultaneously. Methods: The dot{J-dot{P}} relation that governs the orbital evolution of a binary system is set to provide the exact solution for the period and the function expected to represent the subsequent eclipse timing variations. The angular momentum transport is parameterized through appropriate empirical relations, which are inferred from semi-analytical ballistic models. Then, we numerically determine the minimum temporal range over which a particular mechanism is rendered measurable, as well as the critical mass ratio values that signify monotonicity inversion in the period modulations. Results: Mass transfer rates comparable to or greater than 10-8 M⊙ yr-1 are measurable for typical noise levels of the ETV diagrams, regardless of whether the process is conservative. However, the presence of a transient disk around the more massive component defines a critical mass ratio (qcr ≈ 0.83) above which the period turns out to decrease when still in the conservative regime, rendering the measurability of the anticipated variations a much more complicated task. The effects of
International Nuclear Information System (INIS)
Cabbolet, M.J.T.F.
2010-01-01
Theories of modern physics predict that antimatter having rest mass will be attracted by the earth's gravitational field, but the actual coupling of antimatter with gravitation has not been established experimentally. The purpose of the present research was to identify laws of physics that would govern the universe if antimatter having rest mass would be repulsed by the earth's gravitational field. As a result, a formalized axiomatic system was developed together with interpretation rules for the terms of the language: the intention is that every theorem of the system yields a true statement about physical reality. Seven non-logical axioms of this axiomatic system form the elementary process theory (EPT): this is then a scheme of elementary principles describing the dynamics of individual processes taking place at supersmall scale. It is demonstrated how gravitational repulsion functions in the universe of the EPT, and some observed particles and processes have been formalized in the framework of the EPT. Incompatibility of quantum mechanics (QM) and General Relativity (GR) with the EPT is proven mathematically; to demonstrate applicability to real world problems to which neither QM nor GR applies, the EPT has been applied to a theory of the Planck era of the universe. The main conclusions are that a completely formalized framework for physics has been developed supporting the existence of gravitational repulsion and that the present results give rise to a potentially progressive research program. (Abstract Copyright [2010], Wiley Periodicals, Inc.)
A wide-band laser interferometer for the detection of gravitational radiation
International Nuclear Information System (INIS)
Billing, H.; Maischberger, K.; Ruediger, A.; Schilling, R.; Schnupp, L.; Winkler, W.
1979-02-01
The aim of the current investigations of the model interferometer is to gather quantitative data on different noise effects (some of which were rather unexpected), and to develop methods to cope with them. This knowledge will be the basis for a better design of an interferometer of increased path length. The interferometer, in its present form, is not meant for detecting gravitational waves, and the sensitivity currently obtained does not reach that of resonant bars. If the 1-Watt shot-noise limit could be reached, with 300 reflections in the delay line, this model could, however, be an order of magnitude more sensitive than room-temperature resonant bars. (orig.) 891 WB/orig. 892 MAB
THE BENEFITS OF VLBI ASTROMETRY TO PULSAR TIMING ARRAY SEARCHES FOR GRAVITATIONAL RADIATION
Energy Technology Data Exchange (ETDEWEB)
Madison, D. R.; Chatterjee, S.; Cordes, J. M. [Department of Astronomy and Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14850 (United States)
2013-11-10
Precision astrometry is an integral component of successful pulsar timing campaigns. Astrometric parameters are commonly derived by fitting them as parameters of a timing model to a series of pulse times of arrival (TOAs). TOAs measured to microsecond precision over spans of several years can yield position measurements with sub-milliarcsecond precision. However, timing-based astrometry can become biased if a pulsar displays any red spin noise or a red signal produced by the stochastic gravitational wave background. We investigate how noise of different spectral types is absorbed by timing models, leading to significant estimation biases in the astrometric parameters. We find that commonly used techniques for fitting timing models in the presence of red noise (Cholesky whitening) prevent the absorption of noise into the timing model remarkably well if the time baseline of observations exceeds several years, but are inadequate for dealing with shorter pulsar data sets. Independent of timing, pulsar-optimized very long baseline interferometry (VLBI) is capable of providing position estimates precise to the sub-milliarcsecond levels needed for high-precision timing. In order to make VLBI astrometric parameters useful in pulsar timing models, the transformation between the International Celestial Reference Frame (ICRF) and the dynamical solar system ephemeris used for pulsar timing must be constrained to within a few microarcseconds. We compute a transformation between the ICRF and pulsar timing frames and quantitatively discuss how the transformation will improve in coming years. We find that incorporating VLBI astrometry into the timing models of pulsars for which only a couple of years of timing data exist will lead to more realistic assessments of red spin noise and could enhance the amplitude of gravitational wave signatures in post-fit timing residuals by factors of 20 or more.
Anisotropic gravitational instability
International Nuclear Information System (INIS)
Polyachenko, V.L.; Fridman, A.M.
1988-01-01
Exact solutions of stability problems are obtained for two anisotropic gravitational systems of different geometries - a layer of finite thickness at rest and a rotating cylinder of finite radius. It is shown that the anisotropic gravitational instability which develops in both cases is of Jeans type. However, in contrast to the classical aperiodic Jeans instability, this instability is oscillatory. The physics of the anisotropic gravitational instability is investigated. It is shown that in a gravitating layer this instability is due, in particular, to excitation of previously unknown interchange-Jeans modes. In the cylinder, the oscillatory Jeans instability is associated with excitation of a rotational branch, this also being responsible for the beam gravitational instability. This is the reason why this instability and the anisotropic gravitational instability have so much in common
International Nuclear Information System (INIS)
Scheck, Florian
2010-01-01
Stringent presentation of field theory, mediates the connection from the classicalelectrodynamics up to modern gauge theories. The compact presentation is ideal for the bachelor study. New chapter on general relativity theory. Deepens the learned by numerous application from laser physic, metamaterials and different more. Theoretical physics 3. Classical field theory. On electrodynamics, non-Abelian, and gravitation is the third of five volumes on theoretical physics by professor Scheck. The cycle theoretical physics comprehends: Volume 1: Mechanics. From Newtons law to the deterministic chaos. Volume 2: Nonrelativistic quantum theory. From the hydrogen atom to the many-particle systems. Volume 3: Classical field theory. From the electrodynamics to the gauge theories. Volume 5: From the laws of thermodynamics to the quantum statistics. This textbook mediates modern theoretical physics in string presentation illustrated by many examples. It contains numerous problems with solution hints ore exemplary, complete solutions. The third edition was revised in many single topics, especially the chapter on general relativity theory was supplemented by an extensive analysis of the Schwarzschild solution. [de
Prod'homme, T.; Verhoeve, P.; Oosterbroek, T.; Boudin, N.; Short, A.; Kohley, R.
2014-07-01
Euclid is the ESA mission to map the geometry of the dark universe. It uses weak gravitational lensing, which requires the accurate measurement of galaxy shapes over a large area in the sky. Radiation damage in the 36 Charge-Coupled Devices (CCDs) composing the Euclid visible imager focal plane has already been identified as a major contributor to the weak-lensing error budget; radiation-induced charge transfer inefficiency (CTI) distorts the galaxy images and introduces a bias in the galaxy shape measurement. We designed a laboratory experiment to project Euclid-like sky images onto an irradiated Euclid CCD. In this way - and for the first time - we are able to directly assess the effect of CTI on the Euclid weak-lensing measurement free of modelling uncertainties. We present here the experiment concept, setup, and first results. The results of such an experiment provide test data critical to refine models, design and test the Euclid data processing CTI mitigation scheme, and further optimize the Euclid CCD operation.
Relic gravitational wave spectrum, the trans-Planckian physics and Horava-Lifshitz gravity
International Nuclear Information System (INIS)
Koh, Seoktae
2010-01-01
We calculate the spectrum of the relic gravitational wave due to the trans-Planckian effect in which the standard linear dispersion relations may be modified. Of the modified dispersion relations suggested in the literature which has investigated the trans-Planckian effect, we especially use the Corley-Jacobson dispersion relations. The Corley-Jacobson-type modified dispersion relations can be obtained from Horava-Lifshitz gravity which is non-relativistic and UV complete. Although it is not clear how the transitions from Horava-Lifshitz gravity in the UV regime to Einstein gravity in the IR limit occur, we assume that the Horava-Lifshitz gravity regime is followed by the inflationary phase in Einstein gravity.
Calculation codes in radiation protection, radiation physics and dosimetry
International Nuclear Information System (INIS)
2003-01-01
These scientific days had for objective to draw up the situation of calculation codes of radiation transport, of sources estimation, of radiation doses managements and to draw the future perspectives. (N.C.)
International Nuclear Information System (INIS)
Cokelaer, T.
2007-01-01
Matched filtering is used to search for gravitational waves emitted by inspiralling compact binaries in data from the ground-based interferometers. One of the key aspects of the detection process is the design of a template bank that covers the astrophysically pertinent parameter space. In an earlier paper, we described a template bank that is based on a square lattice. Although robust, we showed that the square placement is overefficient, with the implication that it is computationally more demanding than required. In this paper, we present a template bank based on an hexagonal lattice, which size is reduced by 40% with respect to the proposed square placement. We describe the practical aspects of the hexagonal template bank implementation, its size, and computational cost. We have also performed exhaustive simulations to characterize its efficiency and safeness. We show that the bank is adequate to search for a wide variety of binary systems (primordial black holes, neutron stars, and stellar-mass black holes) and in data from both current detectors (initial LIGO, Virgo and GEO600) as well as future detectors (advanced LIGO and EGO). Remarkably, although our template bank placement uses a metric arising from a particular template family, namely, stationary phase approximation, we show that it can be used successfully with other template families (e.g., Pade resummation and effective one-body approximation). This quality of being effective for different template families makes the proposed bank suitable for a search that would use several of them in parallel (e.g., in a binary black hole search). The hexagonal template bank described in this paper is currently used to search for nonspinning inspiralling compact binaries in data from the Laser Interferometer Gravitational-Wave Observatory (LIGO)
Physics of nuclear radiations concepts, techniques and applications
Rangacharyulu, Chary
2013-01-01
Physics of Nuclear Radiations: Concepts, Techniques and Applications makes the physics of nuclear radiations accessible to students with a basic background in physics and mathematics. Rather than convince students one way or the other about the hazards of nuclear radiations, the text empowers them with tools to calculate and assess nuclear radiations and their impact. It discusses the meaning behind mathematical formulae as well as the areas in which the equations can be applied. After reviewing the physics preliminaries, the author addresses the growth and decay of nuclear radiations, the stability of nuclei or particles against radioactive transformations, and the behavior of heavy charged particles, electrons, photons, and neutrons. He then presents the nomenclature and physics reasoning of dosimetry, covers typical nuclear facilities (such as medical x-ray machines and particle accelerators), and describes the physics principles of diverse detectors. The book also discusses methods for measuring energy a...
Lidov–Kozai Cycles with Gravitational Radiation: Merging Black Holes in Isolated Triple Systems
Energy Technology Data Exchange (ETDEWEB)
Silsbee, Kedron [Department of Astrophysical Sciences, Princeton University, Ivy Lane, Princeton, NJ 08544 (United States); Tremaine, Scott, E-mail: ksilsbee@astro.princeton.edu, E-mail: tremaine@ias.edu [Institute for Advanced Study, 1 Einstein Drive Princeton, NJ 08540 (United States)
2017-02-10
We show that a black-hole binary with an external companion can undergo Lidov–Kozai cycles that cause a close pericenter passage, leading to a rapid merger due to gravitational-wave emission. This scenario occurs most often for systems in which the companion has a mass comparable to the reduced mass of the binary and the companion orbit has a semimajor axis within a factor of ∼10 of the binary semimajor axis. Using a simple population-synthesis model and three-body simulations, we estimate the rate of mergers in triple black-hole systems in the field to be about six per Gpc{sup 3} per year in the absence of natal kicks during black-hole formation. This value is within the low end of the 90% credible interval for the total black hole–black hole merger rate inferred from the current LIGO results. There are many uncertainties in these calculations, the largest of which is the unknown distribution of natal kicks. Even modest natal kicks of 40 km s{sup −1} will reduce the merger rate by a factor of 40. A few percent of these systems will have eccentricity greater than 0.999 when they first enter the frequency band detectable by aLIGO (above 10 Hz).
Lidov–Kozai Cycles with Gravitational Radiation: Merging Black Holes in Isolated Triple Systems
International Nuclear Information System (INIS)
Silsbee, Kedron; Tremaine, Scott
2017-01-01
We show that a black-hole binary with an external companion can undergo Lidov–Kozai cycles that cause a close pericenter passage, leading to a rapid merger due to gravitational-wave emission. This scenario occurs most often for systems in which the companion has a mass comparable to the reduced mass of the binary and the companion orbit has a semimajor axis within a factor of ∼10 of the binary semimajor axis. Using a simple population-synthesis model and three-body simulations, we estimate the rate of mergers in triple black-hole systems in the field to be about six per Gpc 3 per year in the absence of natal kicks during black-hole formation. This value is within the low end of the 90% credible interval for the total black hole–black hole merger rate inferred from the current LIGO results. There are many uncertainties in these calculations, the largest of which is the unknown distribution of natal kicks. Even modest natal kicks of 40 km s −1 will reduce the merger rate by a factor of 40. A few percent of these systems will have eccentricity greater than 0.999 when they first enter the frequency band detectable by aLIGO (above 10 Hz).
Gravitational wave production by Hawking radiation from rotating primordial black holes
Energy Technology Data Exchange (ETDEWEB)
Dong, Ruifeng; Kinney, William H.; Stojkovic, Dejan, E-mail: ruifengd@buffalo.edu, E-mail: whkinney@buffalo.edu, E-mail: ds77@buffalo.edu [HEPCOS, Department of Physics, SUNY, University at Buffalo, Buffalo, NY 14260-1500 (United States)
2016-10-01
In this paper we analyze in detail a rarely discussed question of gravity wave production from evaporating primordial black holes. These black holes emit gravitons which are, at classical level, registered as gravity waves. We use the latest constraints on their abundance, and calculate the power emitted in gravitons at the time of their evaporation. We then solve the coupled system of equations that gives us the evolution of the frequency and amplitude of gravity waves during the expansion of the universe. The spectrum of gravitational waves that can be detected today depends on multiple factors: fraction of the total energy density which was occupied by primordial black holes, the epoch in which they were formed, and quantities like their mass and angular momentum. We conclude that very small primordial black holes which evaporate before the big-bang nucleosynthesis emit gravitons whose spectral energy fraction today can be as large as 10{sup −7.5}. On the other hand, those which are massive enough so that they still exist now can yield a signal as high as 10{sup −6.5}. However, typical frequencies of the gravity waves from primordial black holes are still too high to be observed with the current and near future gravity wave observations.
Low-mass neutron stars: universal relations, the nuclear symmetry energy and gravitational radiation
O. Silva, Hector; Berti, Emanuele; Sotani, Hajime
2016-03-01
Compact objects such as neutron stars are ideal astrophysical laboratories to test our understanding of the fundamental interactions in the regime of supranuclear densities, unachievable by terrestrial experiments. Despite recent progress, the description of matter (i.e., the equation of state) at such densities is still debatable. This translates into uncertainties in the bulk properties of neutron stars, masses and radii for instance. Here we will consider low-mass neutron stars. Such stars are expected to carry important information on nuclear matter near the nuclear saturation point. It has recently been shown that the masses and surface redshifts of low-mass neutron stars smoothly depend on simple functions of the central density and of a characteristic parameter η associated with the choice of equation of state. Here we extend these results to slowly-rotating and tidally deformed stars and obtain empirical relations for various quantities, such as the moment of inertia, quadrupole moment and ellipticity, tidal and rotational Love numbers, and rotational apsidal constants. We discuss how these relations might be used to constrain the equation of state by future observations in the electromagnetic and gravitational-wave spectra.
Proceedings of the Eleventh Radiation Physics and Protection Conference
International Nuclear Information System (INIS)
2013-01-01
The proceeding contains of 404 pages, the available maertial of 35 contributions: and covering of conference topics: Plenary, Invited, Keynote Talks. Nuclear Power Plant Accident. Cosmogenic Radionuclides. Waste Storage and Disposal Solutions. Radiation Medical Physics. Radiation Detection and Measurements. Radioactive in Building Materials. Radiation Protection Regulations and public Protection. Environmental Radioactivity.
Projective relativity, cosmology and gravitation
International Nuclear Information System (INIS)
Arcidiacono, G.
1986-01-01
This book describes the latest applications of projective geometry to cosmology and gravitation. The contents of the book are; the Poincare group and Special Relativity, the thermodynamics and electromagnetism, general relativity, gravitation and cosmology, group theory and models of universe, the special projective relativity, the Fantappie group and Big-Bang cosmology, a new cosmological projective mechanics, the plasma physics and cosmology, the projective magnetohydrodynamics field, projective relativity and waves propagation, the generalizations of the gravitational field, the general projective relativity, the projective gravitational field, the De Sitter Universe and quantum physics, the conformal relativity and Newton gravitation
Radiation oncology physics: A handbook for teachers and students
International Nuclear Information System (INIS)
Podgorsak, E.B.
2005-07-01
Radiotherapy, also referred to as radiation therapy, radiation oncology or therapeutic radiology, is one of the three principal modalities used in the treatment of malignant disease (cancer), the other two being surgery and chemotherapy. In contrast to other medical specialties that rely mainly on the clinical knowledge and experience of medical specialists, radiotherapy, with its use of ionizing radiation in the treatment of cancer, relies heavily on modern technology and the collaborative efforts of several professionals whose coordinated team approach greatly influences the outcome of the treatment. The radiotherapy team consists of radiation oncologists, medical physicists, dosimetrists and radiation therapy technologists: all professionals characterized by widely differing educational backgrounds and one common link - the need to understand the basic elements of radiation physics, and the interaction of ionizing radiation with human tissue in particular. This specialized area of physics is referred to as radiation oncology physics, and proficiency in this branch of physics is an absolute necessity for anyone who aspires to achieve excellence in any of the four professions constituting the radiotherapy team. Current advances in radiation oncology are driven mainly by technological development of equipment for radiotherapy procedures and imaging; however, as in the past, these advances rely heavily on the underlying physics. This book is dedicated to students and teachers involved in programmes that train professionals for work in radiation oncology. It provides a compilation of facts on the physics as applied to radiation oncology and as such will be useful to graduate students and residents in medical physics programmes, to residents in radiation oncology, and to students in dosimetry and radiotherapy technology programmes. The level of understanding of the material covered will, of course, be different for the various student groups; however, the basic
A study for reduction of radiation pressure noise in gravitational wave detectors
Energy Technology Data Exchange (ETDEWEB)
Sakata, S; Sugamoto, A [Graduate School of Humanities and Sciences, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo, 112-8610 (Japan); Leonhardt, V; Kawamura, S; Sato, S; Yamazaki, T; Fukushima, M [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Numata, K [NASA Goddard Space Flight Center, CRESST, Code 663, Greenbelt, MD 20771 (United States); Miyakawa, O [LIGO Laboratory 18-34, California Institute of Technology, Pasadena, CA 91125 (United States); Nishizawa, A [Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501 (Japan); Furusawa, A [Department of Applied Physics, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)], E-mail: shihori.sakata@nao.ac.jp
2008-07-15
We describe an experimental conceptual design for observation and reduction of radiation pressure noise. The radiation pressure noise is increased in a high finesse cavity with a small mass mirror. In our experiment a Fabry-Perot Michelson interferometer with a homodyne detection scheme will be built with Fabry-Perot cavities of finesse of 10000 containing suspended mirrors of 23 mg. To observe the radiation pressure noise, the goal sensitivity is set to 1x10{sup -17} [m/ {radical}Hz] at 1 kHz. Then the radiation pressure noise is reduced by adjusting the homodyne phase. To achieve the sensitivity, the other noise sources such as thermal noises, seismic noise and laser frequency noise should be suppressed below 1x10{sup -18} [m/{radical} Hz] at 1kHz. The whole interferometer is suspended as a double pendulum on double-layer stacks. As a preliminary setup, a Fabry-Perot cavity of finesse of 800 with a suspended mirror of 100 mg was locked. The current best sensitivity is 1x10{sup -15} [m/ {radical}Hz] at 1 kHz.
Energy Technology Data Exchange (ETDEWEB)
Miller, Jonah Maxwell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-10-18
This report has slides on Gravitational Waves; Pound and Rebka: A Shocking Fact; Light is a Ruler; Gravity is the Curvature of Spacetime; Gravitational Waves Made Simple; How a Gravitational Wave Affects Stuff Here; LIGO; This Detection: Neutron Stars; What the Gravitational Wave Looks Like; The Sound of Merging Neutron Stars; Neutron Star Mergers: More than GWs; The Radioactive Cloud; The Kilonova; and finally Summary, Multimessenger Astronomy.
IRMHD: an implicit radiative and magnetohydrodynamical solver for self-gravitating systems
Hujeirat, A.
1998-07-01
The 2D implicit hydrodynamical solver developed by Hujeirat & Rannacher is now modified to include the effects of radiation, magnetic fields and self-gravity in different geometries. The underlying numerical concept is based on the operator splitting approach, and the resulting 2D matrices are inverted using different efficient preconditionings such as ADI (alternating direction implicit), the approximate factorization method and Line-Gauss-Seidel or similar iteration procedures. Second-order finite volume with third-order upwinding and second-order time discretization is used. To speed up convergence and enhance efficiency we have incorporated an adaptive time-step control and monotonic multilevel grid distributions as well as vectorizing the code. Test calculations had shown that it requires only 38 per cent more computational effort than its explicit counterpart, whereas its range of application to astrophysical problems is much larger. For example, strongly time-dependent, quasi-stationary and steady-state solutions for the set of Euler and Navier-Stokes equations can now be sought on a non-linearly distributed and strongly stretched mesh. As most of the numerical techniques used to build up this algorithm have been described by Hujeirat & Rannacher in an earlier paper, we focus in this paper on the inclusion of self-gravity, radiation and magnetic fields. Strategies for satisfying the condition ∇.B=0 in the implicit evolution of MHD flows are given. A new discretization strategy for the vector potential which allows alternating use of the direct method is prescribed. We investigate the efficiencies of several 2D solvers for a Poisson-like equation and compare their convergence rates. We provide a splitting approach for the radiative flux within the FLD (flux-limited diffusion) approximation to enhance consistency and accuracy between regions of different optical depths. The results of some test problems are presented to demonstrate the accuracy and
The sky pattern of the linearized gravitational memory effect
International Nuclear Information System (INIS)
Mädler, Thomas; Winicour, Jeffrey
2016-01-01
The gravitational memory effect leads to a net displacement in the relative positions of test particles. This memory is related to the change in the strain of the gravitational radiation field between infinite past and infinite future retarded times. There are three known sources of the memory effect: (i) the loss of energy to future null infinity by massless fields or particles, (ii) the ejection of massive particles to infinity from a bound system and (iii) homogeneous, source-free gravitational waves. In the context of linearized theory, we show that asymptotic conditions controlling these known sources of the gravitational memory effect rule out any other possible sources with physically reasonable stress–energy tensors. Except for the source-free gravitational waves, the two other known sources produce gravitational memory with E -mode radiation strain, characterized by a certain curl-free sky pattern of their polarization. Thus our results show that the only known source of B -mode gravitational memory is of primordial origin, corresponding in the linearized theory to a homogeneous wave entering from past null infinity. (paper)
Radiation physics in medicine and veterinary medicine studies
International Nuclear Information System (INIS)
Popovic, D.; Djuric, G.
2000-01-01
Medical and veterinary medicine staff and specialists represent an important decision making group in national administration and institutions dealing with radiation protection and environmental protection matters in general. Still, their education in physics, especially in radiation physics is fragmentary and loose, both from technical and theoretical point of view. Within medicine and veterinary medicine studies as well as within other biomedical sciences (biology, pharmacology, biotechnology) radiation physics is usually incorporated in the first year curricula as a part of general physics or biophysics course. Some segments of radiation physics mainly as a technical base for different instrumentation methods and techniques could be also found within different graduate and post-graduate courses of radiology, physical therapy, radiation hygiene, environmental protection, etc. But the traditional approach in presenting the matter and inflexibility of the educational system strongly confront the growing public concern for the environmental problems dealing with radiation and demands for better informing and technical education for those involved in informing and administration. This paper considers some of these problems presenting a new approach in education in radiation physics for medical and veterinary medicine students based on education through student projects and work in the field, as well as on the strong collaboration among administration, universities and professional societies on the national and international level. (author)
Bajargaan, Ruchi; Patel, Arvind
2018-04-01
One-dimensional unsteady adiabatic flow behind an exponential shock wave propagating in a self-gravitating, rotating, axisymmetric dusty gas with heat conduction and radiation heat flux, which has exponentially varying azimuthal and axial fluid velocities, is investigated. The shock wave is driven out by a piston moving with time according to an exponential law. The dusty gas is taken to be a mixture of a non-ideal gas and small solid particles. The density of the ambient medium is assumed to be constant. The equilibrium flow conditions are maintained and energy is varying exponentially, which is continuously supplied by the piston. The heat conduction is expressed in the terms of Fourier's law, and the radiation is assumed of diffusion type for an optically thick grey gas model. The thermal conductivity and the absorption coefficient are assumed to vary with temperature and density according to a power law. The effects of the variation of heat transfer parameters, gravitation parameter and dusty gas parameters on the shock strength, the distance between the piston and the shock front, and on the flow variables are studied out in detail. It is interesting to note that the similarity solution exists under the constant initial angular velocity, and the shock strength is independent from the self gravitation, heat conduction and radiation heat flux.
Radiation physics for medical physicists. 2. enl. ed.
International Nuclear Information System (INIS)
Podgorsak, Ervin B.
2010-01-01
This well-received textbook and reference summarizes the basic knowledge of atomic, nuclear, and radiation physics that professionals working in medical physics and biomedical engineering need for efficient and safe use of ionizing radiation. Concentrating on the underlying principles of radiation physics, it covers the prerequisite knowledge for medical physics courses on the graduate and post-graduate levels in radiotherapy physics, radiation dosimetry, imaging physics, and health physics, thus providing the link between elementary physics on the one hand and the intricacies of the medical physics specialties on the other hand. This expanded and revised second edition offers reorganized and expanded coverage. Several of the original chapters have been split into two with new sections added for completeness and better flow. New chapters on Coulomb scattering; on energy transfer and energy absorption in photon interactions; and on waveguide theory have been added in recognition of their importance. Others training for professions that deal with ionizing radiation in diagnosis and treatment as well as medical residents, students of technology and dosimetry,and biomedical engineering will find many sections interesting and useful for their studies. It also serves as excellent preparatory materials for candidates taking professional certification examinations in medical physics, medical dosimetry, and in medical specialties such as radiotherapy, diagnostic radiology, and nuclear medicine. (orig.)
Topics in radiation at accelerators: Radiation physics for personnel and environmental protection
International Nuclear Information System (INIS)
Cossairt, J.D.
1996-10-01
In the first chapter, terminology, physical and radiological quantities, and units of measurement used to describe the properties of accelerator radiation fields are reviewed. The general considerations of primary radiation fields pertinent to accelerators are discussed. The primary radiation fields produced by electron beams are described qualitatively and quantitatively. In the same manner the primary radiation fields produced by proton and ion beams are described. Subsequent chapters describe: shielding of electrons and photons at accelerators; shielding of proton and ion accelerators; low energy prompt radiation phenomena; induced radioactivity at accelerators; topics in radiation protection instrumentation at accelerators; and accelerator radiation protection program elements
Relativistic gravitation theory
International Nuclear Information System (INIS)
Logunov, A.A.; Mestvirishvili, M.A.
1984-01-01
On the basis of the special relativity and geometrization principle a relativistic gravitation theory (RGT) is unambiguously constructed with the help of a notion of a gravitational field as a physical field in Faraday-Maxwell spirit, which posesses energy momentum and spins 2 and 0. The source of gravitation field is a total conserved energy-momentum tensor for matter and for gravitation field in Minkowski space. In the RGT conservation laws for the energy momentum and angular momentum of matter and gravitational field hold rigorously. The theory explains the whole set of gravitation experiments. Here, due to the geometrization principle the Riemannian space is of a field origin since this space arises effectively as a result of the gravitation field origin since this space arises effectively as a result of the gravitation field action on the matter. The RGT astonishing prediction is that the Universe is not closed but ''flat''. It means that in the Universe there should exist a ''missing'' mass in some form of matter
An introduction to the atomic and radiation physics of plasmas
Tallents, G J
2018-01-01
Plasmas comprise more than 99% of the observable universe. They are important in many technologies and are key potential sources for fusion power. Atomic and radiation physics is critical for the diagnosis, observation and simulation of astrophysical and laboratory plasmas, and plasma physicists working in a range of areas from astrophysics, magnetic fusion, and inertial fusion utilise atomic and radiation physics to interpret measurements. This text develops the physics of emission, absorption and interaction of light in astrophysics and in laboratory plasmas from first principles using the physics of various fields of study including quantum mechanics, electricity and magnetism, and statistical physics. Linking undergraduate level atomic and radiation physics with the advanced material required for postgraduate study and research, this text adopts a highly pedagogical approach and includes numerous exercises within each chapter for students to reinforce their understanding of the key concepts.
Presenting Newtonian gravitation
International Nuclear Information System (INIS)
Counihan, Martin
2007-01-01
The basic principles of the Newtonian theory of gravitation are presented in a way which students may find more logically coherent, mathematically accessible and physically interesting than other approaches. After giving relatively simple derivations of the circular hodograph and the elliptical orbit from the inverse-square law, the concept of gravitational energy is developed from vector calculus. It is argued that the energy density of a gravitational field may reasonably be regarded as -g 2 /8πG, and that the inverse-square law may be replaced by a Schwarzschild-like force law without the need to invoke non-Euclidean geometry
Foundations of radiation physics and radiation protection. 3. rev. and enl. ed.
International Nuclear Information System (INIS)
Krieger, Hanno
2009-01-01
The book under consideration comprehensively reports on the physical, biological and legal fundamentals of the radiology. The book is divided into four large sections. The first section is concerned with the physical fundamentals of the radiology, the terms of the dose as well as the computation of the dose rate in radiation fields. The second section reports on the radiobiological and epidemiological fundamentals of the radiation protection as well as on the natural and civilization radiation exposure. The third section comprehensively describes the legal and practical aspects of radiation protection. The last section contains an updated appendix of tables with the most important fundamental data for the practical radiation protection
Radiation-related impacts for nuclear plant physical modifications
International Nuclear Information System (INIS)
Sciacca, F.; Knudson, R.; Simion, G.; Baca, G.; Behling, H.; Behling, K.; Britz, W.; Cohen, S.
1989-10-01
The radiation fields in nuclear power plants present significant obstacles to accomplishing repairs and modifications to many systems and components in these plants. The NRC's generic cost estimating methodology attempts to account for radiation-related impacts by assigning values to the radiation labor productivity factor. This radiation labor productivity factor is then used as a multiplier on the greenfield or new nuclear plant construction labor to adjust for the actual operating plant conditions. The value assigned to the productivity factor is based on the work-site radiation levels. The relationship among ALARA practices, work-place radiation levels, and radiation-related cost impacts previously had not been adequately characterized or verified. The assumptions made concerning the use and application of radiation-reduction measures such as system decontamination and/or the use of temporary shielding can significantly impact estimates of both labor requirements and radiation exposure associated with a particular activity. Overall guidance was needed for analysts as to typical ALARA practices at nuclear power plants and the effects of these practices in reducing work-site dose rates and overall labor requirements. This effort was undertaken to better characterize the physical modification cost and radiological exposure impacts related to the radiation environment of the work place. More specifically, this work sought to define and clarify the quantitative relationships between or among: radiation levels and ALARA practices, such as the use of temporary shielding, decontamination efforts, or the use of robots and remote tools; radiation levels and labor productivity factors; radiation levels, in-field labor hours, and worker radiation exposure; radiation levels and health physics services costs; and radiation levels, labor hours, and anti-contamination clothing and equipment. 48 refs., 4 figs., 4 tabs
Radiation Protection and Dosimetry An Introduction to Health Physics
Stabin, Michael G
2007-01-01
This comprehensive text provides an overview of all relevant topics in the field of radiation protection (health physics). Radiation Protection and Dosimetry serves as an essential handbook for practicing health physics professionals, and is also ideal as a teaching text for courses at the university level. The book is organized to introduce the reader to basic principles of radiation decay and interactions, to review current knowledge and historical aspects of the biological effects of radiation, and to cover important operational topics such as radiation shielding and dosimetry. In addition to presenting the most up to date treatment of the topics and references to the literature, most chapters contain numerical problems with their solutions for use in teaching or self assessment. One chapter is devoted to Environmental Health Physics, which was written in collaboration with leading professionals in the area.
CERN. Geneva
2016-01-01
In the past year, the LIGO-Virgo Collaboration announced the first secure detection of gravitational waves. This discovery heralds the beginning of gravitational wave astronomy: the use of gravitational waves as a tool for studying the dense and dynamical universe. In this talk, I will describe the full spectrum of gravitational waves, from Hubble-scale modes, through waves with periods of years, hours and milliseconds. I will describe the different techniques one uses to measure the waves in these bands, current and planned facilities for implementing these techniques, and the broad range of sources which produce the radiation. I will discuss what we might expect to learn as more events and sources are measured, and as this field matures into a standard part of the astronomical milieu.
International Nuclear Information System (INIS)
Popovic, D.; Djuric, G.; Andric, S.
2001-01-01
Education in Nuclear Physics, Medical Physics and Radiation Protection in medicine and veterinary medicine studies on Belgrade University is an integral part of the curriculum, incorporated in different courses of graduate and post-graduate studies. During graduate studies students get basic elements of Nuclear Physics through Physics and/or Biophysics courses in the 1 st year, while basic knowledge in Medical Physics and Radiation Protection is implemented in the courses of Radiology, Physical Therapy, Radiation Hygiene, Diagnostic Radiology and Radiation Therapy in the 4 th or 5 th year. Postgraduate studies offer MSc degree in Radiology, Physical Therapy, while courses in Nuclear Physics, Nuclear Instrumentation, Radiation Protection and Radiology are core or optional. On the Faculty of Veterinary Medicine graduated students may continue their professional education and obtain specialization degree in Radiology, Physical Therapy or Radiation Protection. On the Faculty of Medicine there are specialization degrees in Medical Nuclear Physics. Still, a closer analysis reveals a number of problems both from methodological and cognitive point of view. They are related mostly to graduate students ability to apply their knowledge in practise and with the qualifications of the educators, as those engaged in graduate studies lack basic knowledge in biological and medical sciences, while those engaged in post graduate studies mostly lack basic education in physics. Therefore, a reformed curricula resulting from much closer collaboration among educators, universities and professional societies at the national level should be considered. (author)
Metrology of radiation protection. Pt. 1. Physical requirements and terminology
Energy Technology Data Exchange (ETDEWEB)
Wagner, S R
1979-10-01
Starting from a general consideration of the needs for radiation protection the physical requirements of a relevant metrology are developed. The expedient physical quantities are introduced and problems in the realization and dissemination of their units discussed. It is shown that owing to these difficulties, derived or operational quantities have to be developed for the construction and calibration of practical measuring instruments. Finally the relations between the metrology of radiation protection and of medical radiology are pointed out and commented. (orig.).
Impact of UV radiation on the physical properties of polypropylene ...
African Journals Online (AJOL)
The purpose of this study was to analyse the influence of simulated sun light radiation (xenon lamp) on physical properties of polypropylene (PP) nonwoven material, which is used for the production of agrotextiles. The research showed that the properties of row cover change when radiated with UV light. Tensile, tearing ...
The physical basis and future of radiation therapy.
Bortfeld, T; Jeraj, R
2011-06-01
The remarkable progress in radiation therapy over the last century has been largely due to our ability to more effectively focus and deliver radiation to the tumour target volume. Physics discoveries and technology inventions have been an important driving force behind this progress. However, there is still plenty of room left for future improvements through physics, for example image guidance and four-dimensional motion management and particle therapy, as well as increased efficiency of more compact and cheaper technologies. Bigger challenges lie ahead of physicists in radiation therapy beyond the dose localisation problem, for example in the areas of biological target definition, improved modelling for normal tissues and tumours, advanced multicriteria and robust optimisation, and continuous incorporation of advanced technologies such as molecular imaging. The success of physics in radiation therapy has been based on the continued "fuelling" of the field with new discoveries and inventions from physics research. A key to the success has been the application of the rigorous scientific method. In spite of the importance of physics research for radiation therapy, too few physicists are currently involved in cutting-edge research. The increased emphasis on more "professionalism" in medical physics will tip the situation even more off balance. To prevent this from happening, we argue that medical physics needs more research positions, and more and better academic programmes. Only with more emphasis on medical physics research will the future of radiation therapy and other physics-related medical specialties look as bright as the past, and medical physics will maintain a status as one of the most exciting fields of applied physics.
The physical basis and future of radiation therapy
Bortfeld, T; Jeraj, R
2011-01-01
The remarkable progress in radiation therapy over the last century has been largely due to our ability to more effectively focus and deliver radiation to the tumour target volume. Physics discoveries and technology inventions have been an important driving force behind this progress. However, there is still plenty of room left for future improvements through physics, for example image guidance and four-dimensional motion management and particle therapy, as well as increased efficiency of more compact and cheaper technologies. Bigger challenges lie ahead of physicists in radiation therapy beyond the dose localisation problem, for example in the areas of biological target definition, improved modelling for normal tissues and tumours, advanced multicriteria and robust optimisation, and continuous incorporation of advanced technologies such as molecular imaging. The success of physics in radiation therapy has been based on the continued “fuelling” of the field with new discoveries and inventions from physics research. A key to the success has been the application of the rigorous scientific method. In spite of the importance of physics research for radiation therapy, too few physicists are currently involved in cutting-edge research. The increased emphasis on more “professionalism” in medical physics will tip the situation even more off balance. To prevent this from happening, we argue that medical physics needs more research positions, and more and better academic programmes. Only with more emphasis on medical physics research will the future of radiation therapy and other physics-related medical specialties look as bright as the past, and medical physics will maintain a status as one of the most exciting fields of applied physics. PMID:21606068
GLINT. Gravitational-wave laser INterferometry triangle
Aria, Shafa; Azevedo, Rui; Burow, Rick; Cahill, Fiachra; Ducheckova, Lada; Holroyd, Alexa; Huarcaya, Victor; Järvelä, Emilia; Koßagk, Martin; Moeckel, Chris; Rodriguez, Ana; Royer, Fabien; Sypniewski, Richard; Vittori, Edoardo; Yttergren, Madeleine
2017-11-01
When the universe was roughly one billion years old, supermassive black holes (103-106 solar masses) already existed. The occurrence of supermassive black holes on such short time scales are poorly understood in terms of their physical or evolutionary processes. Our current understanding is limited by the lack of observational data due the limits of electromagnetic radiation. Gravitational waves as predicted by the theory of general relativity have provided us with the means to probe deeper into the history of the universe. During the ESA Alpach Summer School of 2015, a group of science and engineering students devised GLINT (Gravitational-wave Laser INterferometry Triangle), a space mission concept capable of measuring gravitational waves emitted by black holes that have formed at the early periods after the big bang. Morespecifically at redshifts of 15 big bang) in the frequency range 0.01 - 1 Hz. GLINT design strain sensitivity of 5× 10^{-24} 1/√ { {Hz}} will theoretically allow the study of early black holes formations as well as merging events and collapses. The laser interferometry, the technology used for measuring gravitational waves, monitors the separation of test masses in free-fall, where a change of separation indicates the passage of a gravitational wave. The test masses will be shielded from disturbing forces in a constellation of three geocentric orbiting satellites.
Requirements for radiation oncology physics in Australia and New Zealand
International Nuclear Information System (INIS)
Oliver, L.; Fitchew, R.; Drew, J.
2001-01-01
This Position Paper reviews the role, standards of practice, education, training and staffing requirements for radiation oncology physics. The role and standard of practice for an expert in radiation oncology physics, as defined by the Australasian College of Physical Scientists and Engineers in Medicine (ACPSEM), are consistent with the IAEA recommendations. International standards of safe practice recommend that this physics expert be authorised by a Regulatory Authority (in consultation with the professional organisation). In order to accommodate the international and AHTAC recommendations or any requirements that may be set by a Regulatory Authority, the ACPSEM has defined the criteria for a physicist-in-training, a base level physicist, an advanced level physicist and an expert radiation oncology physicist. The ACPSEM shall compile separate registers for these different radiation oncology physicist categories. What constitutes a satisfactory means of establishing the number of physicists and support physics staff that is required in radiation oncology continues to be debated. The new ACPSEM workforce formula (Formula 2000) yields similar numbers to other international professional body recommendations. The ACPSEM recommends that Australian and New Zealand radiation oncology centres should aim to employ 223 and 46 radiation oncology physics staff respectively. At least 75% of this workforce should be physicists ( 168 in Australia and 35 in New Zealand). An additional 41 registrar physicist positions (34 in Australia and 7 in New Zealand) should be specifically created for training purposes. These registrar positions cater for the present physicist shortfall, the future expansion of radiation oncology and the expected attrition of radiation oncology physicists in the workforce. Registrar physicists shall undertake suitable tertiary education in medical physics with an organised in-house training program.The rapid advances in the theory and methodology of the new
Nuclear Quantum Gravitation - The Correct Theory
Kotas, Ronald
2016-03-01
Nuclear Quantum Gravitation provides a clear, definitive Scientific explanation of Gravity and Gravitation. It is harmonious with Newtonian and Quantum Mechanics, and with distinct Scientific Logic. Nuclear Quantum Gravitation has 10 certain, Scientific proofs and 21 more good indications. With this theory the Physical Forces are obviously Unified. See: OBSCURANTISM ON EINSTEIN GRAVITATION? http://www.santilli- Foundation.org/inconsistencies-gravitation.php and Einstein's Theory of Relativity versus Classical Mechanics http://www.newtonphysics.on.ca/einstein/
Lemoigne, Yves
2011-01-01
This book introduces the fundamental aspects of Radiation Protection in Medical Physics and covers three main themes: General Radiation Protection Principles; Radiobiology Principles; Radiation Protection in Hospital Medical Physics. Each of these topics is developed by analysing the underlying physics principles and their implementation, quality and safety aspects, clinical performance and recent advances in the field. Some issues specific to the individual techniques are also treated, e.g. calculation of patient dose as well as that of workers in hospital, optimisation of equipment used, shielding design of radiation facilities, radiation in oncology such as use of brachytherapy in gynecology or interventional procedures. All topics are presented with didactical language and style, making this book an appropriate reference for students and professionals seeking a comprehensive introduction to the field as well as a reliable overview of the most recent developments.
International Nuclear Information System (INIS)
Haisch, Bernhard; Rueda, Alfonso
1998-01-01
The basis of most modern technology is the manipulation of electromagnetic phenomena. Haisch, Rueda and Puthoff (1994a) published a controversial but substantive formulation of a concept proposing an explanation of inertia of matter as an electromagnetic phenomenon originating in the zero-point field (ZPF) of the quantum vacuum. This suggests that Newton's equation of motion can be derived from Maxwell's equations of electrodynamics, in that inertial mass is postulated to be not an intrinsic property of matter but rather a kind of electromagnetic drag force (which temporarily is a place holder for a more general quantum vacuum reaction effect) that proves to be acceleration dependent by virtue of the spectral characteristics of the ZPF. Moreover the principle of equivalence implies that in this view gravitation would also be electromagnetic in origin along the lines proposed by Sakharov (1968). A NASA-funded research effort has been underway at the Lockheed Martin Advanced Technology Center in Palo Alto and at California State University in Long Beach to develop and test these ideas. An effort to generalize the 1994 ZPF-inertia concept into a proper relativistic formulation has been successful. With regard to the goals of the NASA Breakthrough Propulsion Physics Program we can, on the basis of the ZPF-inertia concept, definitively rule out one speculatively hypothesized propulsion mechanism: matter possessing negative inertial mass, a concept originated by Bondi (1957). The existence of this is shown to be logically impossible. On the other hand, the linked ZPF-inertia and ZPF-gravity concepts open the conceptual possibility of manipulation of inertia and gravitation, since both are postulated to be electromagnetic phenomena. Whether this will translate into actual technological potential, especially with respect to spacecraft propulsion and future interstellar travel capability, is an open question. The (possibly comparable) time scale for translation of Einstein
International Nuclear Information System (INIS)
Burmeister, Jay; Chen, Zhe; Chetty, Indrin J.; Dieterich, Sonja; Doemer, Anthony; Dominello, Michael M.; Howell, Rebecca M.; McDermott, Patrick; Nalichowski, Adrian; Prisciandaro, Joann; Ritter, Tim; Smith, Chadd; Schreiber, Eric; Shafman, Timothy; Sutlief, Steven; Xiao, Ying
2016-01-01
Purpose: The American Society for Radiation Oncology (ASTRO) Physics Core Curriculum Subcommittee (PCCSC) has updated the recommended physics curriculum for radiation oncology resident education to improve consistency in teaching, intensity, and subject matter. Methods and Materials: The ASTRO PCCSC is composed of physicists and physicians involved in radiation oncology residency education. The PCCSC updated existing sections within the curriculum, created new sections, and attempted to provide additional clinical context to the curricular material through creation of practical clinical experiences. Finally, we reviewed the American Board of Radiology (ABR) blueprint of examination topics for correlation with this curriculum. Results: The new curriculum represents 56 hours of resident physics didactic education, including a 4-hour initial orientation. The committee recommends completion of this curriculum at least twice to assure both timely presentation of material and re-emphasis after clinical experience. In addition, practical clinical physics and treatment planning modules were created as a supplement to the didactic training. Major changes to the curriculum include addition of Fundamental Physics, Stereotactic Radiosurgery/Stereotactic Body Radiation Therapy, and Safety and Incidents sections, and elimination of the Radiopharmaceutical Physics and Dosimetry and Hyperthermia sections. Simulation and Treatment Verification and optional Research and Development in Radiation Oncology sections were also added. A feedback loop was established with the ABR to help assure that the physics component of the ABR radiation oncology initial certification examination remains consistent with this curriculum. Conclusions: The ASTRO physics core curriculum for radiation oncology residents has been updated in an effort to identify the most important physics topics for preparing residents for careers in radiation oncology, to reflect changes in technology and practice since
Radiation and detectors introduction to the physics of radiation and detection devices
Cerrito, Lucio
2017-01-01
This textbook provides an introduction to radiation, the principles of interaction between radiation and matter, and the exploitation of those principles in the design of modern radiation detectors. Both radiation and detectors are given equal attention and their interplay is carefully laid out with few assumptions made about the prior knowledge of the student. Part I is dedicated to radiation, broadly interpreted in terms of energy and type, starting with an overview of particles and forces, an extended review of common natural and man-made sources of radiation, and an introduction to particle accelerators. Particular attention is paid to real life examples, which place the types of radiation and their energy in context. Dosimetry is presented from a modern, user-led point of view, and relativistic kinematics is introduced to give the basic knowledge needed to handle the more formal aspects of radiation dynamics and interaction. The explanation of the physics principles of interaction between radiation an...
International Nuclear Information System (INIS)
Redmount, I.H.
1984-01-01
This dissertation consists of two studies on the general-relativistic theory of black holes. The first work concerns the fundamental issue of black-hole formation: in it geometric constraints are sought on gravitating matter systems, in the special case of axial symmetry, which determine whether or not those systems undergo gravitational collapse to form black holes. The second project deals with mechanical behavior of a black hole: specifically, the tidal deformation of a static black hole is studied by the gravitational fields of external bodies
Relativistic theory of gravitation
International Nuclear Information System (INIS)
Logunov, A.A.; Mestvirishvilli, M.A.
1985-01-01
In the present paper a relativistic theory of gravitation (RTG) is constructed in a unique way on the basis of the special relativity and geometrization principle. In this, a gravitational field is treated as the Faraday-Maxwell spin-2 and spin-0 physical field possessing energy and momentum. The source of a gravitational field is the total conserved energy-momentum tensor of matter and of a gravitational field in Minkowski space. In the RTG, the conservation laws are strictly fulfilled for the energy-momentum and for the angular momentum of matter and a gravitational field. The theory explains the whole available set of experiments on gravitation. In virtue of the geometrization principle, the Riemannian space in our theory is of field origin, since it appears as an effective force space due to the action of a gravitational field on matter. The RTg leads to an exceptionally strong prediction: The Universe is not closed but just ''flat''. This suggests that in the Universe a ''hidden mass'' should exist in some form of matter
Hartley, April; Gregson, Celia L; Hannam, Kimberly; Deere, Kevin C; Clark, Emma M; Tobias, Jon H
2018-04-17
Sarcopenia has been associated with reduced physical activity (PA). We aimed to determine if sarcopenia, and specific components of muscle size, function, and physical performance, are associated with high impacts achieved during habitual PA, as these are related to bone strength in community-dwelling older women. Participants were older women from the Cohort of Skeletal Health in Bristol and Avon. We defined sarcopenia using the EWGSOP criteria. Lower limb peak muscle power and force were assessed using Jumping Mechanography (JM). High vertical impacts were assessed by tri-axial accelerometry (at least 1.5g above gravity). Cross-sectional associations were analyzed by linear regression, adjusting for age, height and weight (or fat mass for models including appendicular lean mass index), comorbidities, smoking, alcohol, and Index of Multiple Deprivation. Our analyses included 380 participants, with mean age 76.7 (SD 3.0) years; 242 (64%) also completed JM. In age-adjusted analysis, a negative relationship was observed between severity of sarcopenia and high, but not medium or low, impacts (p = .03 for trend). Regarding components of sarcopenia underlying this relationship, multivariable analyses revealed that gait speed (β 1.47 [95% CI 1.14, 1.89], [β-1] reflects the proportionate increase in high impacts per SD increase in exposure) and peak force (1.40 [1.07, 1.84]) were independently associated with high impacts. Older women with sarcopenia experienced fewer bone-strengthening high impacts than those with presarcopenia or without sarcopenia. To increase bone strengthening activity in older women, interventions need to improve both lower limb muscle force and walking speed.
Physics contributions to radiation protection in nuclear power plants
International Nuclear Information System (INIS)
Krueger, F.W.
1980-01-01
Physical research and physical methods can essentially contribute to radiation protection in nuclear power plants. With their aid, properties of radiation sources can be determined, and calculations of radiation shields can be performed. In the present paper, such tasks are analyzed, the state of the art of their solution is evaluated, and trends of further work are shown. Focal points of the present study are the calculation of properties of radiation sources outside the reactor (fission products, activated corrosion products, decontamination facilities for contaminated media), exact and engineering methods for calculating radiation fields also in inhomogeneous shields, and classification of concretes for gamma-ray shielding. Objectives, possibilities, and problems of standardization of such activities are discussed. (author)
Energy Technology Data Exchange (ETDEWEB)
NONE
2009-06-15
The special volume of the journal covers the abstracts of the DEGRO 2009 meeting on radiation oncology, medical physics, and radiation biology, covering the following topics: seldom diseases, gastrointestinal tumors, radiation reactions and radiation protection, medical care and science, central nervous system, medical physics, the non-parvicellular lung carcinomas, ear-nose-and throat, target-oriented radiotherapy plus ''X'', radio-oncology - young academics, lymphomas, mammary glands, modern radiotherapy, life quality and palliative radiotherapy, radiotherapy of the prostate carcinoma, imaging for planning and therapy, the digital documentation in clinics and practical experiences, NMR imaging and tomography, hadrons - actual status in Germany, urinal tract oncology, radiotoxicity.
Workshop on the interface between radiation chemistry and radiation physics
International Nuclear Information System (INIS)
1983-03-01
Twenty-four papers are grouped under the session headings: measurements of physical and chemical properties, track structure modeling, spurs and track structure, and the 10 - 16 to 10 - 12 second region. Separate abstracts were prepared for 12 of the papers; four of the remaining papers had previously been abstracted
Radiation, photon orbits, and torsion in strongly curved spacetimes
International Nuclear Information System (INIS)
Sandberg, V.D.
1975-01-01
Four topics on the strong field aspects of general relativity are presented. These are the role of constraining forces for ultrarelativistic particle motion as a source of gravitational radiation, the study of electromagnetic radiation due to space-time oscillations, the light scattering properties of a class of naked singularities, and the relation of gravitation theories with torsion to general relativity. The astrophysical implications and unusual physical phenomena associated with very intense gravitational fields are discussed for these four topics
Hilbert's 'Foundations of Physics': Gravitation and electromagnetism within the axiomatic method
Brading, K. A.; Ryckman, T. A.
2008-01-01
In November and December 1915, Hilbert presented two communications to the Göttingen Academy of Sciences under the common title 'The Foundations of Physics'. Versions of each eventually appeared in the Nachrichten of the Academy. Hilbert's first communication has received significant reconsideration in recent years, following the discovery of printer's proofs of this paper, dated 6 December 1915. The focus has been primarily on the 'priority dispute' over the Einstein field equations. Our contention, in contrast, is that the discovery of the December proofs makes it possible to see the thematic linkage between the material that Hilbert cut from the published version of the first communication and the content of the second, as published in 1917. The latter has been largely either disregarded or misinterpreted, and our aim is to show that (a) Hilbert's two communications should be regarded as part of a wider research program within the overarching framework of 'the axiomatic method' (as Hilbert expressly stated was the case), and (b) the second communication is a fine and coherent piece of work within this framework, whose principal aim is to address an apparent tension between general invariance and causality (in the precise sense of Cauchy determination), pinpointed in Theorem I of the first communication. This is not the same problem as that found in Einstein's 'hole argument'-something that, we argue, never confused Hilbert.
UV-Radiation: From Physics to Impacts
Directory of Open Access Journals (Sweden)
Hanns Moshammer
2017-02-01
Full Text Available Ultraviolet (UV radiation has affected life at least since the first life forms moved out of the seas and crawled onto the land. Therefore, one might assume that evolution has adapted to natural UV radiation. However, evolution is mostly concerned with the propagation of the genetic code, not with a long, happy, and fulfilling life. Because rickets is bad for a woman giving birth, the beneficial effects of UV-radiation outweigh the adverse effects like aged skin and skin tumors of various grades of malignancy that usually only afflict us at older age. Anthropogenic damage to the stratospheric ozone layer and frighteningly high rates of melanoma skin cancer in the light-skinned descendants of British settlers in Australia piqued interest in the health impacts of UV radiation. A changing cultural perception of the beauty of tanned versus light skin and commercial interests in selling UV-emitting devices such as tanning booths caught public health experts off-guard. Counseling and health communication are extremely difficult when dealing with a “natural” risk factor, especially when this risk factor cannot (and should not be completely avoided. How much is too much for whom or for which skin type? How even measure “much”? Is it the (cumulative dose or the dose rate that matters most? Or should we even construct a more complex metric such as the cumulative dose above a certain dose rate threshold? We find there are still many open questions, and we are glad that this special issue offered us the opportunity to present many interesting aspects of this important topic.
Orbital radiation imaging with various physical principles
Energy Technology Data Exchange (ETDEWEB)
Takeda, Toru; Itai, Yuji [Tsukuba Univ., Ibaraki (Japan). Inst. of Clinical Medicine
2001-06-01
This paper describes the characteristics of orbital radiation and authors' investigations on the high spatial resolution X ray-CT, fluorescence X ray-CT and phase-type X ray imaging. Orbital radiation is an X ray generated by relativistic electron bended by magnet in the synchrotron and possesses the high photon density/unit area (>100,000 times higher than that of the ordinary X ray generated by the tube) and broad energy spectrum, which make it possible to select the X ray with appropriate energy for the target. The high spatial resolution X-CT has the resolution of 0.05 mm in contrast to 0.5 mm of the ordinary X-CT and is used for the hard structure like tooth and bone. The CT images of rat lumbar vertebrae and artificial bone are presented. Fluorescence X-CT is utilized for detection of trace elements. Images of the thyroid are presented on iodine detection. Concerning the phase-type X-imaging, the principle using the X ray interferometer is described and actual phase-images of blood vessels and 3-demensional ones of metastatic colon cancer in the liver are given. Imaging with the orbital radiation can be a useful technique in the near future. (K.H.)
Photonuclear Physics in Radiation Transport - II: Implementation
International Nuclear Information System (INIS)
White, M.C.; Little, R.C.; Chadwick, M.B.; Young, P.G.; MacFarlane, R.E.
2003-01-01
This is the second of two companion papers. The first paper describes model calculations and nuclear data evaluations of photonuclear reactions on isotopes of C, O, Al, Si, Ca, Fe, Cu, Ta, W, and Pb for incident photon energies up to 150 MeV. This paper describes the steps taken to process these files into transport libraries and to update the Monte Carlo N-Particle (MCNP) and MCNPX radiation transport codes to use tabular photonuclear reaction data. The evaluated photonuclear data files are created in the standard evaluated nuclear data file (ENDF) format. These files must be processed by the NJOY data processing system into A Compact ENDF (ACE) files suitable for radiation transport calculations. MCNP and MCNPX have been modified to use these new data in a self-consistent and fully integrated manner. Verification problems were used at each step along the path to check the integrity of the methodology. The resulting methodology and tools provide a comprehensive system for using photonuclear data in radiation transport calculations. Also described are initial validation simulations used to benchmark several of the photonuclear transport tables
Orbital radiation imaging with various physical principles
International Nuclear Information System (INIS)
Takeda, Toru; Itai, Yuji
2001-01-01
This paper describes the characteristics of orbital radiation and authors' investigations on the high spatial resolution X ray-CT, fluorescence X ray-CT and phase-type X ray imaging. Orbital radiation is an X ray generated by relativistic electron bended by magnet in the synchrotron and possesses the high photon density/unit area (>100,000 times higher than that of the ordinary X ray generated by the tube) and broad energy spectrum, which make it possible to select the X ray with appropriate energy for the target. The high spatial resolution X-CT has the resolution of 0.05 mm in contrast to 0.5 mm of the ordinary X-CT and is used for the hard structure like tooth and bone. The CT images of rat lumbar vertebrae and artificial bone are presented. Fluorescence X-CT is utilized for detection of trace elements. Images of the thyroid are presented on iodine detection. Concerning the phase-type X-imaging, the principle using the X ray interferometer is described and actual phase-images of blood vessels and 3-demensional ones of metastatic colon cancer in the liver are given. Imaging with the orbital radiation can be a useful technique in the near future. (K.H.)
Topics in gravitation and gauge fields
International Nuclear Information System (INIS)
Leen, T.K.
1982-01-01
The theoretical studies presented here address three distinct topics. The first deals with quantum-mechanical effects of classical gravitational radiation. Specifically, the use of the interstellar medium itself as a remote quantum-mechanical detector of gravitational waves is investigated. This study is motivated by the presumed existence of atomic hydrogen in the vicinity of astrophysical sources of gravitational radiation. Space-time curvature produces uniquely identifiable shifts in atomic hydrogen energy levels. The oscillating level shifts induced by a passing gravitational wave could conceivably be detected spectroscopically. Accordingly the level shifts for both low-lying and highly excited states of single electron atoms immersed in gravitational radiation have been studied. The second two topics deal with the theory of quantized fields on curved space-times. In the first of these studies, a naive model of cosmological baryon synthesis is examined. The model incorporates a hard CP violation as well as a baryon (and lepton) non-conserving interaction and is thus capable of generating an excess of matter over antimatter. The time dependent background geometry of the early universe drives the interaction producing net excess of baryon/lepton pairs. In the final topic, the question of renormalizability of non-Abelian gauge fields theories in a general curved space-time is addressed. All modern theories of elementary particle physics are gauge theories and one would like to know if their perturbative expansions continue to be well defined (i.e. renormalizable) on curved backgrounds. In general, one is interested in knowing if field theories renormalizable in Minkowski space remain so in a general curved space-time
Gravitational-wave research: Current status and future prospects
International Nuclear Information System (INIS)
Thorne, K.S.
1980-01-01
There is a reasonably good change that in the 1980s cosmic gravitational waves will be discovered and will become a powerful tool for astronomy. This prospect has stimulated a three-pronged research effort. First, relativity theorists are developing new mathematical tools for the analysis of gravitational radiation: including (i) methods of analyzing the generation of gravity waves by sources with strong self-gravity and large internal velocities (e.g., collisions of black holes), (ii) methods of computing radiation reaction in sources, and (iii) methods of analyzing how gravitational waves propagate through our lumpy curved-space Universe. Second, astrophysicists are attempting to identify the most promissing sources of gravitational waves, and are using the relativity theorists' mathematical tools to estimate the characteristics of the waves they emit. Third, with the estimated wave characteristics in mind, experimenters are designing and constructing a second generation of gravitational-wave detectors: detectors of three types: Doppler tracking of interplanetary spacecraft, Earth-based laser interferometers, and Earth-based Weber-type resonant bars. This article reviews, in brief, all three prongs of the research effort and gives references to more detailed articles about specialized aspects of gravitational-wave physics
Medical Physics expert and competence in radiation protection
International Nuclear Information System (INIS)
Vano, E.; Lamn, I. N.; Guerra, A. del; Van Kleffens, H. J.
2003-01-01
The Council Directive 97/43/EURATOM on health protection of individuals against the dangers of ionizing radiation in relation to medical exposure, defines the Medical Physical Expert as an expert in radiation physics or radiation technology applied to exposure, within the scope of the Directive, whose training and competence to act is recognized by the competent authorities; and who, as appropriate, acts or gives advice on patient dosimetry, on the development and use of complex techniques and equipment, on optimization, on quality assurance, including quality control, and on other matters relating to radiation protection, concerning exposure within the scope of this Directive. As a consequence, it might be implied that his competence in radiation protection should also cover the staff and the public. In fact, the training programmes of medical physics experts include all the aspects concerning these topics. Some confusion could arise in the medical area when the Qualified Expert defined in the Council Directive 96/29/Euratom laying down basic safety standards for the protection of the health of workers and the general public against the dangers arising from ionizing radiation is considered. The Qualified Expert is defined as a person having the knowledge and training needed to carry out physical, technical or radiochemical tests enabling doses to be assessed, and to give advice in order to ensure effective protection of individuals and the correct operation of protective equipment, whose capacity to act a qualified expert is recognized by the competent authorities. A qualified expert may be assigned the technical responsibility for the tasks of radiation protection of workers and members of the public. In Europe, the Qualified Expert is acting at present in the Medical Area in countries where there are not enough Medical Physics Experts or in countries where this role was established before the publication of the Council Directive 97/43/EURATOM. Now, the coherent
Heuristic introduction to gravitational waves
International Nuclear Information System (INIS)
Sandberg, V.D.
1982-01-01
The purpose of this article is to provide a rough and somewhat heuristic theoretical background and introduction to gravitational radiation, its generation, and its detection based on Einstein's general theory of relativity
Radiative corrections to two photon physics
International Nuclear Information System (INIS)
Neervan, W.L. van; Vermaseren, J.A.M.
1983-06-01
The authors develop a method to calculate radiative corrections to two photon reactions of the type e + e - →e + e - X where X is an arbitrary final state. To illustrate this they take the example where X stands for a point-like pseudoscalar. It will be shown that the method is an improvement on the standard way in adding real and virtual photon contributions to the (differential) cross-sections. This makes it possible to compute differential and total cross-sections to a very high precision and with a minimum of computer time which is not possible by using more conventional methods. (Auth.)
Gravitation. [Book on general relativity
Misner, C. W.; Thorne, K. S.; Wheeler, J. A.
1973-01-01
This textbook on gravitation physics (Einstein's general relativity or geometrodynamics) is designed for a rigorous full-year course at the graduate level. The material is presented in two parallel tracks in an attempt to divide key physical ideas from more complex enrichment material to be selected at the discretion of the reader or teacher. The full book is intended to provide competence relative to the laws of physics in flat space-time, Einstein's geometric framework for physics, applications with pulsars and neutron stars, cosmology, the Schwarzschild geometry and gravitational collapse, gravitational waves, experimental tests of Einstein's theory, and mathematical concepts of differential geometry.
International Nuclear Information System (INIS)
1981-07-01
Separate abstracts were prepared for the 29 papers in this progress report which deal with radiobiological physics, the biological effects of ionizing radiations, and the modification of these effects by chemical and pharmacological agents
The physics of radiation driven ICF hohlraums
International Nuclear Information System (INIS)
Rosen, M.D.
1995-01-01
On the Nova Laser at LLNL, we have recently demonstrated many of the key elements required for assuring that the next proposed laser, the National Ignition Facility (NIF) will drive an Inertial Confinement Fusion (ICF) target to ignition. The target uses the recently declassified indirect drive (sometimes referred to as open-quotes radiation driveclose quotes) approach which converts laser light to x-rays inside a gold cylinder, which then acts as an x-ray open-quotes ovenclose quotes (called a hohlraum) to drive the fusion capsule in its center. On Nova we've demonstrated good understanding of the temperatures reached in hohlraums and of the ways to control the uniformity with which the x-rays drive the spherical fusion capsules. In this lecture we briefly review the fundamentals of ICF, and describe the capsule implosion symmetry advantages of the hohlraum approach. We then concentrate on a quantitative understanding of the scaling of radiation drive with hohlraum size and wall material, and with laser pulse length and power. We demonstrate that coupling efficiency of x-ray drive to the capsule increases as we proceed from Nova to the NIF and eventually to a reactor, thus increasing the gain of the system
Radiation physical chemistry effects on organic detectors
International Nuclear Information System (INIS)
Mesquita, C.H.; Duarte, C.L.; Hamada, M.M.
2003-01-01
The radiation damage effect on a liquid scintillating system was evaluated in the PPO and POPOP solutes. Samples containing PPO (1%w/v) and POPOP (0.2%w/v) diluted in toluene were irradiated at different doses, using a 60 Co irradiator at 1.8 Gy/s. The transmittance and the chemical degradation of those solutes were evaluated as a function of dose. The PPO transmittance at 360 nm decayed exponentially with the dose, while the POPOP transmittance at 420 nm decayed linearly. The chemical degradation on the PPO and POPOP was fitted to a bi-exponential mathematical model as a function of dose. The first exponential (fast slope) was interpreted as damage produced by toluene radiolytics whereas the second exponential (slow slope) was interpreted as the damage caused by primary interaction of the γ-radiation with targets, i.e., γ photons that hit PPO and POPOP directly. The w (eV/damage molecule) and G (damaged molecules/100 eV) parameters were estimated in this paper
Overview. Department of Environmental and Radiation Transport Physics. Section 6
Energy Technology Data Exchange (ETDEWEB)
Loskiewicz, J. [Institute of Nuclear Physics, Cracow (Poland)
1995-12-31
Research activities in the Department of Environmental and Radiation Transport Physics are carried out by three Laboratories: Laboratory of Environmental Physics, Laboratory of Neutron Transport Physics and Laboratory of Physics and Modeling of Radiation Transport. The researches provided in 1994 cover: tracer transport and flows in porous media, studies on pollution in atmospheric air, physics of molecular phenomena in chromatographic detectors, studies on neutron transport in heterogenous media, studies on evaluation of neutron cross-section in the thermal region, studies on theory and utilization of neural network in data evaluation, numerical modelling of particle cascades for particle accelerator shielding purpose. In this section the description of mentioned activities as well as the information about personnel employed in the Department, papers and reports published in 1994, contribution to conferences and grants is also given.
Overview. Department of Environmental and Radiation Transport Physics. Section 6
Energy Technology Data Exchange (ETDEWEB)
Loskiewicz, J [Institute of Nuclear Physics, Cracow (Poland)
1996-12-31
Research activities in the Department of Environmental and Radiation Transport Physics are carried out by three Laboratories: Laboratory of Environmental Physics, Laboratory of Neutron Transport Physics and Laboratory of Physics and Modeling of Radiation Transport. The researches provided in 1994 cover: tracer transport and flows in porous media, studies on pollution in atmospheric air, physics of molecular phenomena in chromatographic detectors, studies on neutron transport in heterogenous media, studies on evaluation of neutron cross-section in the thermal region, studies on theory and utilization of neural network in data evaluation, numerical modelling of particle cascades for particle accelerator shielding purpose. In this section the description of mentioned activities as well as the information about personnel employed in the Department, papers and reports published in 1994, contribution to conferences and grants is also given.
Department of Cosmic Radiation Physics: Overview
International Nuclear Information System (INIS)
Gawin, J.
1999-01-01
Full text: The Department of Cosmic Ray Physics in Lodz is involved in basic research in the area of high energy physics and cosmic ray physics related to: - Studies of asymptotic properties of hadronic interactions based on the analysis of cosmic ray propagation in the atmosphere. - Experimental and phenomenological studies of Extensive Air Showers induced by cosmic ray particles. - Search for point sources of high energy cosmic rays. - Studies of cosmic ray propagation in the Galaxy and mechanisms of particle acceleration. - Studies of mass composition of cosmic rays in the energy range 10 15 - 10 17 eV. Theoretical and experimental studies of Extensive Air Shower properties are performed mostly based on the results obtained by the Lodz Extensive Air Shower Array. We analysed nearly 100,000 events of energies above 10 15 eV registered by the Lodz hodoscope. We have developed the method of data analysis which allows us to verify different models of cosmic ray mass composition. In our research in high energy cosmic rays we also used experimental data from other collaborating experiments in Karlsruhe, Baksan and THEMISTOCLE. The Lodz group collaborates with many foreign institutes and laboratories in construction and data interpretation of cosmic ray experiments. Our most important partners are: Forschungszentrum in Karlsruhe (Germany), College de France, Institute for Nuclear Studies of the Russian Academy of Science, University of Perpignan and Uppsala University (Sweden). (author)
Department of Cosmic Radiation Physics - Overview
International Nuclear Information System (INIS)
Gawin, J.
1997-01-01
Full text: The Department of Cosmic Ray Physics in Lodz is involved in basic research in the area of high energy physics and cosmic ray physics related to: -Studies of the asymptotic properties of hadronic interactions from the analysis of cosmic ray propagation in the atmosphere. -Studies of structure and properties of Extensive Air Showers induced by cosmic ray particles. -Search for point sources of high energy cosmic rays. -Studies of cosmic ray propagation in the Galaxy and mechanisms of particle acceleration. -Studies of the mass composition of cosmic rays in the energy range 10 15 -10 17 eV. Theoretical and experimental studies of nuclear interactions for energies exceeding those obtained by modern particle accelerators are performed employing results obtained by the Lodz Extensive Air Shower Array. The Lodz hodoscope can register electromagnetic components of cosmic ray showers in the atmosphere as well as muons at two energy thresholds. Data collected by the Lodz array are also used to study mass composition of cosmic rays in the energy range 10 15 - 10 17 eV. The Lodz group collaborates with foreign institutes and laboratories on construction and data interpretation of cosmic ray experiments. Our most important partners are: Forschungszentrum Karlsruhe (Germany), College de France, the Institute for Nuclear Studies of the Russian Academy of Sciences, the University of Durham, and the University of Perpignan. (author)
Department of Cosmic Radiation Physics: Overview
International Nuclear Information System (INIS)
Szabelski, J.
2000-01-01
Full text: Department of Cosmic Ray Physics in Lodz is involved in basic research in the area of high-energy physics and cosmic ray physics related to: -Studies of asymptotic properties of hadronic interactions based on the analysis of cosmic ray propagation through the atmosphere. -Experimental and phenomenological studies of Extensive Air Showers induced by cosmic ray particles. - Search for high-energy cosmic ray point sources. - Studies of cosmic ray propagation in the Galaxy and particle acceleration mechanisms. -Studies of mass composition of cosmic rays in the energy range 10 15 -10 17 eV. Theoretical and experimental studies of Extensive Air Shower properties are performed mainly on the basis of the results obtained by the Lodz Extensive Air Shower Array. We have analysed nearly 100,000 events of energies above 10 15 eV registered in the Lodz hodoscope. We have developed a method to verify different models of cosmic ray mass composition. The Lodz group collaborates with many foreign institutes and laboratories in construction and data interpretation of cosmic ray experiments. Our most important partners are: Forschungszentrum in Karlsruhe (Germany), College de France, Institute for Nuclear Studies of the Russian Academy of Sciences and Uppsala University (Sweden). (author)
Department of Cosmic Radiation Physics: Overview
International Nuclear Information System (INIS)
Gawin, J.
1998-01-01
(full text) The Department of Cosmic Ray Physics in Lodz is involved in basic research in the area of high energy physics and cosmic ray physics related to: -Studies of asymptotic properties of hadronic interactions based on the analysis of cosmic ray propagation in the atmosphere. -Studies of the structure and properties of Extensive Air Showers induced by cosmic ray particles. - Search for point sources of high energy cosmic rays. - Studies of cosmic ray propagation in the Galaxy and mechanisms of particle acceleration. - Studies of mass composition of cosmic rays in the energy range l0 15 -10 17 eV. Theoretical and experimental studies of nuclear interactions for energies exceeding those obtained by modern particle accelerators are performed based on the results obtained by the Lodz Extensive Air Shower Array. The Lodz hodoscope can register the electromagnetic component of cosmic ray showers developing in the atmosphere as well as muons of two energy thresholds. Data collected by the Lodz array are also used to study the mass composition of cosmic rays in the energy range 10 15 -10 17 eV. The Lodz group collaborates with many foreign institutes and laboratories in construction and data interpretation of cosmic ray experiments. Our most important partners are: Forschungszentrum Karlsruhe (Germany), College de' France, the Institute for Nuclear Studies of the Russian Academy of Science, the University of Perpignan (France) and Uppsala University (Sweden). (author)
Proceedings of the Eigth Radiation Physics and Protection Conference (RPC-2006)
Energy Technology Data Exchange (ETDEWEB)
NONE
2007-06-15
The publication's has been set up in 487 papers and also as electronic of the conference of Radiation Physics and Protection, it consists of the following session (1) nuclear physics; (2) neutron physics, shielding and applications; (3) radiation detection and dosimetry; (4) environmental and protection; (5) nuclear physics; (6) radiation effects; (7) medical physics and biophysics; (8) atmospheric dispersion, atomic physics; (9) radiation physics and protection awarded contribution.
Proceedings of the Eigth Radiation Physics and Protection Conference (RPC-2006)
International Nuclear Information System (INIS)
2007-06-01
The publication's has been set up in 487 papers and also as electronic of the conference of Radiation Physics and Protection, it consists of the following session (1) nuclear physics; (2) neutron physics, shielding and applications; (3) radiation detection and dosimetry; (4) environmental and protection; (5) nuclear physics; (6) radiation effects; (7) medical physics and biophysics; (8) atmospheric dispersion, atomic physics; (9) radiation physics and protection awarded contribution
Radiation Diffusion: An Overview of Physical and Numerical Concepts
International Nuclear Information System (INIS)
Graziani, F R
2005-01-01
An overview of the physical and mathematical foundations of radiation transport is given. Emphasis is placed on how the diffusion approximation and its transport corrections arise. An overview of the numerical handling of radiation diffusion coupled to matter is also given. Discussions center on partial temperature and grey methods with comments concerning fully implicit methods. In addition finite difference, finite element and Pert representations of the div-grad operator is also discussed
New astrophysical school of thermodynamics. Space dynamics and gravitism
Energy Technology Data Exchange (ETDEWEB)
Gal-Or, B [Technion-Israel Inst. of Tech., Haifa. Dept. of Aeronautical Engineering
1978-07-01
Much verified information has been accumulated in recent years which shows that many fundamental concepts involving classical physics, thermodynamics, astrophysics and the general theory of relativity are strongly coupled together. This evidence is employed in this paper to explain principles of the astrophysical school of thermodynamics; a growing revolutionary school which deduces thermodynamics, energy dissipation, and time anisotropies from the Newtonian and Einsteinian theories of gravitation and from the dynamics of radiation in 'unsaturable' (intercluster) space. Accordingly, the density of radiation and the dynamics of ('unsaturable') outer space affect all processes in the galactic media, in the solar system, in the magnetosphere and on Earth. The origin of all observed irreversibilities in nature - of time, of all time anisotropics, of energy dissipation, of T-violations in 'elementary particles', of retarded potentials in electrodynamics, of the biological clocks, and of biological arrows of time - is one; it is the radiation unsaturability of space. But, since this unsaturability and gravitation are interconnected, the origin of asymmetries, structure, and thermodynamics is explained within the framework of the Newtonian and Einsteinian theories of gravitation. The theory presented here forms a part of a general approach called gravitism, which unifies some other disciplinary studies in the natural sciences with a unified approach to gravitation and the theory of time.
Relativistic theory of gravitation
International Nuclear Information System (INIS)
Logunov, A.A.; Mestvirishvili, M.A.
1986-01-01
In the present paper a relativistic theory of gravitation (RTG) is unambiguously constructed on the basis of the special relativity and geometrization principle. In this a gravitational field is treated as the Faraday--Maxwell spin-2 and spin-0 physical field possessing energy and momentum. The source of a gravitational field is the total conserved energy-momentum tensor of matter and of a gravitational field in Minkowski space. In the RTG the conservation laws are strictly fulfilled for the energy-moment and for the angular momentum of matter and a gravitational field. The theory explains the whole available set of experiments on gravity. By virtue of the geometrization principle, the Riemannian space in our theory is of field origin, since it appears as an effective force space due to the action of a gravitational field on matter. The RTG leads to an exceptionally strong prediction: The universe is not closed but just ''flat.'' This suggests that in the universe a ''missing mass'' should exist in a form of matter
Scaling, scattering, and blackbody radiation in classical physics
International Nuclear Information System (INIS)
Boyer, Timothy H
2017-01-01
Here we discuss blackbody radiation within the context of classical theory. We note that nonrelativistic classical mechanics and relativistic classical electrodynamics have contrasting scaling symmetries which influence the scattering of radiation. Also, nonrelativistic mechanical systems can be accurately combined with relativistic electromagnetic radiation only provided the nonrelativistic mechanical systems are the low-velocity limits of fully relativistic systems. Application of the no-interaction theorem for relativistic systems limits the scattering mechanical systems for thermal radiation to relativistic classical electrodynamic systems, which involve the Coulomb potential. Whereas the naive use of nonrelativistic scatterers or nonrelativistic classical statistical mechanics leads to the Rayleigh–Jeans spectrum, the use of fully relativistic scatterers leads to the Planck spectrum for blackbody radiation within classical physics. (paper)
Basics of radiation physics and instrumentation
International Nuclear Information System (INIS)
Royal, H.D.
1985-01-01
Continued technical developments are greatly changing medical diagnosis and medical care. In the field of cardiology, a number of new imaging techniques are currently available. This chapter reviews several topics that are important in the practice of nuclear cardiology. The first section discusses some of the basics of nuclear physics. Familiarity with these fundamentals is essential for an in-depth understanding of nuclear cardiology. The second section presents information on radiotracers and provides dosimetry estimates for commonly performed studies. The third section reviews the instruments used to detect radioactivity. The final section discusses computers and their applications and limitations in nuclear cardiology
Atomic, molecular, and optical physics electromagnetic radiation
Dunning, F B; Lucatorto, Thomas
1997-01-01
Combined with Volumes 29A and 29B, this volume is a comprehensive treatment of the key experimental methods of atomic, molecular, and optical physics, as well as an excellent experimental handbook for the field. Thewide availability of tunable lasers in the past several years has revolutionized the field and lead to the introduction of many new experimental methods that are covered in these volumes. Traditional methods are also included to ensure that the volumes will be a complete reference source for the field.
Computing in radiation protection and health physics - 10 years further
International Nuclear Information System (INIS)
Behrens, R.; Greif, N.; Struwe, H.; Wissmann, F.
2008-01-01
Computing influences radiation protection and health physics more extensively as ever before. The good old data processing and main frame computing has changed towards information technology in a wider sense. Technologies and operating systems out of workplace computing have amended microprocessor technology in measuring devices. The boundaries between them are constantly in a state of flux. The use of the world wide web has become indispensable. No radiation protection expert could still manage without a workplace computer. Measuring networks, radiation protection information systems, data bases, computer simulation and other challenging applications form the image of today. (orig.)
Multiscale approach to the physics of radiation damage with ions
Energy Technology Data Exchange (ETDEWEB)
Surdutovich, Eugene [Physics Department, Oakland University, 2200 N. Squirrel Rd., Rochester MI 48309 (United States); Solov' yov, Andrey V. [Frankfurt Institute for Advanced Studies, Goethe University, Ruth-Moufang-Str. 1, Frankfurt am Main 60438 (Germany)
2013-04-19
We review a multiscale approach to the physics of ion-beam cancer therapy, an approach suggested in order to understand the interplay of a large number of phenomena involved in radiation damage scenario occurring on a range of temporal, spatial, and energy scales. We briefly overview its history and present the current stage of its development. The differences of the multiscale approach from other methods of understanding and assessment of radiation damage are discussed as well as its relationship to other branches of physics, chemistry and biology.
Khan's lectures handbook of the physics of radiation therapy
Khan, Faiz M; Mihailidis, Dimitris
2011-01-01
Khan's Lectures: Handbook of the Physics of Radiation Therapy will provide a digest of the material contained in The Physics of Radiation Therapy. Lectures will be presented somewhat similar to a PowerPoint format, discussing key points of individual chapters. Selected diagrams from the textbook will be used to initiate the discussion. New illustrations will used, wherever needed, to enhance the understanding of important concepts. Discussion will be condensed and often bulleted. Theoretical details will be referred to the textbook and the cited literature. A problem set (practice questions) w
Bárcenas, R. B.; Hernández, H. H. H.; Sabido, M.
2015-11-01
The collection of papers in this volume was presented during the X Mexican School on Gravitation and Mathematical Physics, which was held in Playa del Carmen, Quintana Roo, México, December 1-5, 2014. The Mexican School on Gravitation and Mathematical Physics is a series of conferences sponsored by the Mexican Physical Society that started in 1994 with the purposes of discussing and exchanging current ideas in gravitational physics. Each Mexican School has been devoted to a particular subject, and these have included supergravity, branes, black holes, the early Universe, observational cosmology, quantum gravity and numerical relativity. In this ocasion the theme of the school was Reaching a Century: Classical and Modified General Relativity's Attempts to explain the evolution of the Universe, which focused on the discussion of classical and modified aspects of general relativity. Following our previous Schools, world leaders in the field were invited to give courses and plenary lectures. More specialized talks were also presented in parallel sessions, and some of them have been included in these proceedings. The contributions in this volume have been reviewed and represent some of the courses, plenary talks and contributed talks presented during our X School. We are indebted to the contributors of these proceedings as well as to the rest of the participants in our Mexican School all for making of it a complete success. As for financial support we should mention the Mexican National Science and Technology Council (CONACyT), the Royal Society of London (UK), the Mexican Physical Society (SMF), as well as several Institutions including: Centro de Investigación y Estudios Avanzados (CINVESTAV), Universidad Autónoma Metropolitana Iztapalapa (UAM-I), Universidad de Guanajuato (UG), and Universidad Nacional Autónoma de México (UNAM).
Quantum phenomena in gravitational field
Bourdel, Th.; Doser, M.; Ernest, A. D.; Voronin, A. Yu.; Voronin, V. V.
2011-10-01
The subjects presented here are very different. Their common feature is that they all involve quantum phenomena in a gravitational field: gravitational quantum states of ultracold antihydrogen above a material surface and measuring a gravitational interaction of antihydrogen in AEGIS, a quantum trampoline for ultracold atoms, and a hypothesis on naturally occurring gravitational quantum states, an Eötvös-type experiment with cold neutrons and others. Considering them together, however, we could learn that they have many common points both in physics and in methodology.
Quantum phenomena in gravitational field
International Nuclear Information System (INIS)
Bourdel, Th.; Doser, M.; Ernest, A.D.; Voronin, A.Y.; Voronin, V.V.
2010-01-01
The subjects presented here are very different. Their common feature is that they all involve quantum phenomena in a gravitational field: gravitational quantum states of ultracold anti-hydrogen above a material surface and measuring a gravitational interaction of anti-hydrogen in AEGIS, a quantum trampoline for ultracold atoms, and a hypothesis on naturally occurring gravitational quantum states, an Eoetvoes-type experiment with cold neutrons and others. Considering them together, however, we could learn that they have many common points both in physics and in methodology. (authors)
International Nuclear Information System (INIS)
Bondi, H.
1979-01-01
In spite of the strength of gravitational focres between celestial bodies, gravitational capture is not a simple concept. The principles of conservation of linear momentum and of conservation of angular momentum, always impose severe constraints, while conservation of energy and the vital distinction between dissipative and non-dissipative systems allows one to rule out capture in a wide variety of cases. In complex systems especially those without dissipation, long dwell time is a more significant concept than permanent capture. (author)
International Nuclear Information System (INIS)
Anon.
2012-01-01
The volume includes the abstracts of the contributions and posters of the 18th annual congress of the German Radiation Oncology Society DEGRO 2012. The lectures covered the following topics: Radiation physics, therapy planning; gastrointestinal tumors; radiation biology; stererotactic radiotherapy/breast carcinomas; quality management - life quality; head-neck-tumors/lymphomas; NSCL (non-small cell lung carcinomas); pelvic tumors; brain tumors/pediatric tumors. The poster sessions included the following topics: quality management, recurrent tumor therapy; brachytherapy; breast carcinomas and gynecological tumors; pelvis tumors; brain tumors; stereotactic radiotherapy; head-neck carcinomas; NSCL, proton therapy, supporting therapy; clinical radio-oncology, radiation biology, IGRT/IMRT.
Problems and progress in radiation physics of semiconductors
International Nuclear Information System (INIS)
Vinetskij, V.L.
1982-01-01
A survey of the current status of radiation physics of semiconductors comprises the analysis of some new problems and poses the statement of concern. The essential difference between the probability of interstitial-vacancy pair occurrence W(T) in elastic collisions and the generally accepted step distribution with a typical ''threshold'' energy Tsub(d) is indicated. The role of diffusion and reaction evolution of primary defects leading to specific properties of the cluster formation process is shown. Special features of defect formation in spatially inhomogeneous semiconductors, in particular for elastic stresses present, are described. Among most important advances in the radiation physics of semiconductors there are the discovery of non-activation motion of the ''extra'' atom in silicon, the observation of a low activation energy value for the vacancy diffusion, the understanding of subthreshold mechanism of defect formation and radiation-induced diffusion, the effects of laser annealing of defects and oriented crystallization
The gravitational Schwinger effect and attenuation of gravitational waves
McDougall, Patrick Guarneri
This paper will discuss the possible production of photons from gravitational waves. This process is shown to be possible by examining Feynman diagrams, the Schwinger Effect, and Hawking Radiation. The end goal of this project is to find the decay length of a gravitational wave and assert that this decay is due to photons being created at the expense of the gravitational wave. To do this, we first find the state function using the Klein Gordon equation, then find the current due to this state function. We then take the current to be directly proportional to the production rate per volume. This is then used to find the decay length that this kind of production would produce, gives a prediction of how this effect will change the distance an event creating a gravitational wave will be located, and shows that this effect is small but can be significant near the source of a gravitational wave.
International Nuclear Information System (INIS)
Halpern, L.
1987-01-01
The author, who was Schroedinger's assistant during his last years in Vienna, gives an account of Schroedinger's views and activities during that time which lead him to a different approach to research on the relations between gravitation and quantum phenomena. Various features of past research are outlined in nontechnical terms. A heuristic argument is presented for the role of the zero-point energy of massive particles in counteracting gravitational collapse and the formation of horizons. Arguments are presented for the view that progress in describing extreme gravitational phenomena can be achieved by the new outlook obtained from the introduction of the analog of Maxwell's vacuum displacement term with a quasiconstant parameter, rather than from renormalization of special processes, even if this is successful. The results can be expected to be in accord with Schroedinger's conjectures. A physical interpretation for the change of sign of the differential invariant of Karlhede, Lindstroem, and Aman at the horizon is suggested. Some important historical details about Schroedinger are touched upon
Gravitational waves from gravitational collapse
Energy Technology Data Exchange (ETDEWEB)
Fryer, Christopher L [Los Alamos National Laboratory; New, Kimberly C [Los Alamos National Laboratory
2008-01-01
Gravitational wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars.
Gravitational Waves from Gravitational Collapse
Directory of Open Access Journals (Sweden)
Chris L. Fryer
2011-01-01
Full Text Available Gravitational-wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion-induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars.
Gravitational Waves from Gravitational Collapse.
Fryer, Chris L; New, Kimberly C B
2011-01-01
Gravitational-wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion-induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars. Supplementary material is available for this article at 10.12942/lrr-2011-1.
Radiation protection knowledge in the undergraduate level for physics students
International Nuclear Information System (INIS)
Frutos-Baraja, J. M.; Sanchez-Carmona, G.; Hernando-Gonzalez, I.; Cid-Galache, A.; Castillo-Belmonte, A. del; Barrio-Lazo, F. J.; Pereda-Barroeta, N.; Iniguez de la Torre, M. P.; Barquero-Sanz, R.; Lopez-Lara-Martin, F.
2004-01-01
Medical physics knowledge and the ionising radiations use with medical purposes are a matter of growing interest among students will be titled in physics University degree. To familiarize to students of Physics University degree with this field is considered important so much so that they relate part of that learned in the curriculum ruled as to show them a possible unknown professional field for many. To detect necessities in this field it is carried out an evaluation of knowledge that it help to program activities with those that to satisfy formative necessities in this field. (Author) 17 refs
Radiative sky cooling: fundamental physics, materials, structures, and applications
Sun, Xingshu; Sun, Yubo; Zhou, Zhiguang; Alam, Muhammad Ashraful; Bermel, Peter
2017-07-01
Radiative sky cooling reduces the temperature of a system by promoting heat exchange with the sky; its key advantage is that no input energy is required. We will review the origins of radiative sky cooling from ancient times to the modern day, and illustrate how the fundamental physics of radiative cooling calls for a combination of properties that may not occur in bulk materials. A detailed comparison with recent modeling and experiments on nanophotonic structures will then illustrate the advantages of this recently emerging approach. Potential applications of these radiative cooling materials to a variety of temperature-sensitive optoelectronic devices, such as photovoltaics, thermophotovoltaics, rectennas, and infrared detectors, will then be discussed. This review will conclude by forecasting the prospects for the field as a whole in both terrestrial and space-based systems.
Radiative sky cooling: fundamental physics, materials, structures, and applications
Directory of Open Access Journals (Sweden)
Sun Xingshu
2017-07-01
Full Text Available Radiative sky cooling reduces the temperature of a system by promoting heat exchange with the sky; its key advantage is that no input energy is required. We will review the origins of radiative sky cooling from ancient times to the modern day, and illustrate how the fundamental physics of radiative cooling calls for a combination of properties that may not occur in bulk materials. A detailed comparison with recent modeling and experiments on nanophotonic structures will then illustrate the advantages of this recently emerging approach. Potential applications of these radiative cooling materials to a variety of temperature-sensitive optoelectronic devices, such as photovoltaics, thermophotovoltaics, rectennas, and infrared detectors, will then be discussed. This review will conclude by forecasting the prospects for the field as a whole in both terrestrial and space-based systems.
Radiation Physics for Personnel and Environmental Protection
International Nuclear Information System (INIS)
Cossairt, J.D.
1999-01-01
preparation and revision of these materials. Alex Elwyn deserves special recognition for his helpful advice during the initial preparation of this work and, indeed, during his entire distinguished career at Fermilab in which he, in so many ways, has been my scientific mentor. Nancy Grossman, Kamran Vaziri, and Vernon Cupps have provided me with very constructive criticism in connection with their assistance in presenting these materials to students in the USPAS. Others whose comments have been very helpful are David Boehnlein, Kathy Graden, Paul Kesich, and Elaine Marshall. William Griffing has supported my efforts in producing the present revision. The original version of this text was presented as part of a course taught at the session of the U. S. Particle Accelerator School held at Florida State University in January 1993. Subsequently, the material was further refined and presented as a course at Fermilab in the spring of 1993 and autumn of 1994. Later, the course was presented at the USPAS sessions held at Duke University in January 1995, at the University of California in January 1997, and at Vanderbilt University in January 1999. This fourth revision represents a compilation of the work of numerous people and it is hoped that the reference citations lead the reader to the original work of those individuals who have developed this field of applied physics. Over the years, I have been greatly .enriched to have been acquainted personally with many of these fine scientists. The problems supplied with each chapter were developed with the goal of promoting better understanding of the text
Overview of physical safety of radiation sources in Brazil
International Nuclear Information System (INIS)
Lima, A.R.; Silva, F.C.A. da
2017-01-01
The threat of 'radiological terrorism' has been recognized worldwide after the event of September 11, 2001. Radioactive sources can be used for the development of DDR ('dirty bomb') devices. Studies show that the use of a DDR could cause health damage, psychosocial and economic and environmental damage. Brazil follows this worldwide concern, since it has a large medical-industrial park that uses radioactive sources. This paper presents an overview of the physical safety of radioactive sources in Brazil, based on the inventory of radiative facilities, regulatory aspects and international recommendations. For the preparation of the study, the database of radioactive sources of the regulatory body, the current normative status and the international recommendations were used. In Brazil there are approximately 2,500 radiative installations, with about 400 radioactive sources Category 1 and 2, which are the biggest concern in terms of physical safety. The Brazilian licensing standard addresses only some aspects of physical protection, not providing a clear orientation for the elaboration and implementation of physical protection systems, in accordance with international recommendations. For Brazil to be included in the world scenario of physical safety of radioactive sources, it is urgent to elaborate specific legislation with well-defined regulatory criteria. The lack of more detailed requirements makes it difficult to make a more careful regulatory assessment of the physical protection conditions of the facilities, either through the evaluation of plans and other physical protection documents or through regulatory inspections
ASTRO's core physics curriculum for radiation oncology residents
International Nuclear Information System (INIS)
Klein, Eric E.; Balter, James M.; Chaney, Edward L.; Gerbi, Bruce J.; Hughes, Lesley
2004-01-01
In 2002, the Radiation Physics Committee of the American Society of Therapeutic Radiology and Oncology (ASTRO) appointed an Ad-hoc Committee on Physics Teaching to Medical Residents. The main initiative of the committee was to develop a core curriculum for physics education. Prior publications that have analyzed physics teaching have pointed to wide discrepancies among teaching programs. The committee was composed of physicists or physicians from various residency program based institutions. Simultaneously, members had associations with the American Association of Physicists in Medicine (AAPM), ASTRO, Association of Residents in Radiation Oncology (ARRO), American Board of Radiology (ABR), and the American College of Radiology (ACR). The latter two organizations' representatives were on the physics examination committees, as one of the main agendas was to provide a feedback loop between the examining organizations and ASTRO. The document resulted in a recommended 54-h course. Some of the subjects were based on American College of Graduate Medical Education (ACGME) requirements (particles, hyperthermia), whereas the majority of the subjects along with the appropriated hours per subject were devised and agreed upon by the committee. For each subject there are learning objectives and for each hour there is a detailed outline of material to be covered. Some of the required subjects/h are being taught in most institutions (i.e., Radiation Measurement and Calibration for 4 h), whereas some may be new subjects (4 h of Imaging for Radiation Oncology). The curriculum was completed and approved by the ASTRO Board in late 2003 and is slated for dissemination to the community in 2004. It is our hope that teaching physicists will adopt the recommended curriculum for their classes, and simultaneously that the ABR for its written physics examination and the ACR for its training examination will use the recommended curriculum as the basis for subject matter and depth of
International Nuclear Information System (INIS)
Hall, E.J.; Zaider, M.
1994-05-01
Research at the Center for Radiological Research is a blend of physics, chemistry and biology and epitomizes the multidisciplinary approach towards understanding the mechanisms involved in the health problems resulting from human exposure to ionizing radiations. To an increasing extent, the focus of attention is on biochemistry and the application of the techniques of molecular biology to the problems of radiation biology. Research highlights from the past year are briefly described
Energy Technology Data Exchange (ETDEWEB)
Hall, E.J.; Zaider, M.
1994-05-01
Research at the Center for Radiological Research is a blend of physics, chemistry and biology and epitomizes the multidisciplinary approach towards understanding the mechanisms involved in the health problems resulting from human exposure to ionizing radiations. To an increasing extent, the focus of attention is on biochemistry and the application of the techniques of molecular biology to the problems of radiation biology. Research highlights from the past year are briefly described.
Anisotropic solutions by gravitational decoupling
Ovalle, J.; Casadio, R.; da Rocha, R.; Sotomayor, A.
2018-02-01
We investigate the extension of isotropic interior solutions for static self-gravitating systems to include the effects of anisotropic spherically symmetric gravitational sources by means of the gravitational decoupling realised via the minimal geometric deformation approach. In particular, the matching conditions at the surface of the star with the outer Schwarzschild space-time are studied in great detail, and we describe how to generate, from a single physically acceptable isotropic solution, new families of anisotropic solutions whose physical acceptability is also inherited from their isotropic parent.
Anisotropic solutions by gravitational decoupling
Energy Technology Data Exchange (ETDEWEB)
Ovalle, J. [Silesian University in Opava, Institute of Physics and Research Centre of Theoretical Physics and Astrophysics, Faculty of Philosophy and Science, Opava (Czech Republic); Universidad Simon Bolivar, Departamento de Fisica, Caracas (Venezuela, Bolivarian Republic of); Casadio, R. [Alma Mater Universita di Bologna, Dipartimento di Fisica e Astronomia, Bologna (Italy); Istituto Nazionale di Fisica Nucleare, Bologna (Italy); Rocha, R. da [Universidade Federal do ABC (UFABC), Centro de Matematica, Computacao e Cognicao, Santo Andre, SP (Brazil); Sotomayor, A. [Universidad de Antofagasta, Departamento de Matematicas, Antofagasta (Chile)
2018-02-15
We investigate the extension of isotropic interior solutions for static self-gravitating systems to include the effects of anisotropic spherically symmetric gravitational sources by means of the gravitational decoupling realised via the minimal geometric deformation approach. In particular, the matching conditions at the surface of the star with the outer Schwarzschild space-time are studied in great detail, and we describe how to generate, from a single physically acceptable isotropic solution, new families of anisotropic solutions whose physical acceptability is also inherited from their isotropic parent. (orig.)
Constraints on new physics from radiative B decays
Energy Technology Data Exchange (ETDEWEB)
Paul, Ayan [INFN, Sezione di Roma,I-00185 Rome (Italy); Straub, David M. [Excellence Cluster Universe, TUM,Boltzmannstr. 2, 85748 Garching (Germany)
2017-04-05
A new phase for the measurements of radiative decay modes in b→s transitions has started with new measurements of exclusive modes by LHCb and with Belle-II showing distinctive promises in both inclusive and exclusive channels. After critically reviewing the hadronic uncertainties in exclusive radiative decays, we analyze the impact of recent measurements of the branching ratio and mass-eigenstate rate asymmetry in B{sub s}→ϕγ and of the angular distribution of B→K{sup ∗}e{sup +}e{sup −} at low q{sup 2} on new physics in the b→sγ transition.
Institute of Scientific and Technical Information of China (English)
Zhan-Kui Lü; Shi-Wei Wu; Zhi-Cheng Zeng
2009-01-01
Like the investigation of double white dwarf (DWD) systems, strange dwarf (SD) - white dwarf (WD) system evolution in Laser Interferometer Space Antenna (LISA)'s absolute amplitude-frequency diagram is investigated. Since there is a strange quark core inside an SD, SDs' radii are significantly smaller than the value predicted by the standard WD model, which may strongly affect the gravitational wave (GW) signal in the mass-transferring phases of binary systems. We study how an SD-WD binary evolves across LISA's absolute amplitude-frequency diagram. In principle, we provide an executable way to detect SDs in the Galaxy's DWD systems by radically new windows offered by GW detectors.
International Nuclear Information System (INIS)
1971-01-01
Radiation dosimetry is a fundamental part of all radiation protection work. The measurements are made with a variety of instruments, and health physicists, after professional interpretation of the data, can assess the levels of exposure which might be encountered in a given area or the individual doses received by workers, visitors and others at places where the possibility of radiation exposure exists. The types of radiation concerned here are photon radiations, ranging from soft X-rays to gamma rays, and particulate radiations such as β-rays, α-particles, protons, neutrons and fission fragments. The type of technique used depends not only on the type of radiation but also on such factors as whether the radiation is from a source internal or external to the body. Radiation dosimetry is not only used at nuclear facilities; it has diverse applications, for example in determining doses when radiation sources are employed for medical diagnostics and therapy, in safeguarding workers in any industry where isotopes are used, and in assessing the effect of both naturally occurring and man-made radiations on the general public and the environment. The advances of modern technology have increased the variety of sources; an example can be given from colour television, where the high potential necessary in certain colour cathode-ray tubes generates a non-negligible amount of X-rays. The Symposium on New Developments in Physical and Biological Radiation Detectors was one of a continuing series of meetings in which the International Atomic Energy Agency furthers the exchange of information on all aspects of personnel and area dosimetry. The Symposium was devoted in particular to a study of the dose meters themselves - their radiation-sensitive elements (both physical and biological),their instrumentation, and calibration and standardization. Several speakers suggested that the situation in the standardization and calibration of measuring equipment and sources was
Radiation-Induced Prompt Photocurrents in Microelectronics Physics
Dodd, P E; Buller, D L; Doyle, B L; Vizkelethy, G; Walsh, D S
2003-01-01
The effects of photocurrents in nuclear weapons induced by proximal nuclear detonations are well known and remain a serious hostile environment threat for the US stockpile. This report describes the final results of an LDRD study of the physical phenomena underlying prompt photocurrents in microelectronic devices and circuits. The goals of this project were to obtain an improved understanding of these phenomena, and to incorporate improved models of photocurrent effects into simulation codes to assist designers in meeting hostile radiation requirements with minimum build and test cycles. We have also developed a new capability on the ion microbeam accelerator in Sandia's Ion Beam Materials Research Laboratory (the Transient Radiation Microscope, or TRM) to supply ionizing radiation in selected micro-regions of a device. The dose rates achieved in this new facility approach those possible with conventional large-scale dose-rate sources at Sandia such as HERMES III and Saturn. It is now possible to test the phy...
Kopczyński, W.; Trautman, A.
This book is a revised translation of the Polish original "Czasoprzestrzeń i grawitacja", Warszawa (Poland), Państwowe Wydawnictwo Naukowe, 1984. Ideas about space and time are at the root of one's understanding of nature, both at the intuitive level of everyday experience and in the framework of sophisticated physical theories. These ideas have led to the development of geometry and its applications to physics. The contemporary physical theory of space and time, including its extention to the phenomena of gravitation, is Einstein's theory of relativity. The book is a short introduction to this theory. A great deal of emphasis is given to the geometrical aspects of relativity theory and its comparison with the Newtonian view of the world. There are short chapters on the origins of Einstein's theory, gravitational waves, cosmology, spinors and the Einstein-Cartan theory.
International Nuclear Information System (INIS)
Bassi, Angelo; Großardt, André; Ulbricht, Hendrik
2017-01-01
We discuss effects of loss of coherence in low energy quantum systems caused by or related to gravitation, referred to as gravitational decoherence. These effects, resulting from random metric fluctuations, for instance, promise to be accessible by relatively inexpensive table-top experiments, way before the scales where true quantum gravity effects become important. Therefore, they can provide a first experimental view on gravity in the quantum regime. We will survey models of decoherence induced both by classical and quantum gravitational fluctuations; it will be manifest that a clear understanding of gravitational decoherence is still lacking. Next we will review models where quantum theory is modified, under the assumption that gravity causes the collapse of the wave functions, when systems are large enough. These models challenge the quantum-gravity interplay, and can be tested experimentally. In the last part we have a look at the state of the art of experimental research. We will review efforts aiming at more and more accurate measurements of gravity ( G and g ) and ideas for measuring conventional and unconventional gravity effects on nonrelativistic quantum systems. (topical review)
Rahvar, Sohrab
2018-05-01
In this work, we study the interaction of the electromagnetic wave (EW) from a distant quasar with the gravitational wave (GW) sourced by the binary stars. While in the regime of geometric optics, the light bending due to this interaction is negligible, we show that the phase shifting on the wavefront of an EW can produce the diffraction pattern on the observer plane. The diffraction of the light (with the wavelength of λe) by the gravitational wave playing the role of gravitational grating (with the wavelength of λg) has the diffraction angle of Δβ ˜ λe/λg. The relative motion of the observer, the source of gravitational wave and the quasar results in a relative motion of the observer through the interference pattern on the observer plane. The consequence of this fringe crossing is the modulation in the light curve of a quasar with the period of few hours in the microwave wavelength. The optical depth for the observation of this phenomenon for a Quasar with the multiple images strongly lensed by a galaxy where the light trajectory of some of the images crosses the lensing galaxy is τ ≃ 0.2. By shifting the time-delay of the light curves of the multiple images in a strong lensed quasar and removing the intrinsic variations of a quasar, our desired signals, as a new method for detection of GWs can be detected.
International Nuclear Information System (INIS)
Nyambuya, Golden Gadzirayi
2010-01-01
This paper is part of a series on the Azimuthally Symmetric Theory of Gravitation (ASTG). This theory is built on Laplace-Poisson's well known equation and it has been shown that the ASTG is capable of explaining, from a purely classical physics standpoint, the precession of the perihelion of solar planets as a consequence of the azimuthal symmetry emerging from the spin of the Sun. This symmetry has and must have an influence on the emergent gravitational field. We show herein that the emergent equations from the ASTG, under some critical conditions determined by the spin, do possess repulsive gravitational fields in the polar regions of the gravitating body in question. This places the ASTG on an interesting pedestal to infer the origins of outflows as a repulsive gravitational phenomenon. Outflows are a ubiquitous phenomenon found in star forming systems and their true origin is a question yet to be settled. Given the current thinking on their origin, the direction that the present paper takes is nothing short of an asymptotic break from conventional wisdom; at the very least, it is a complete paradigm shift because gravitation is not at all associated with this process, but rather it is thought to be an all-attractive force that only tries to squash matter together onto a single point. Additionally, we show that the emergent Azimuthally Symmetric Gravitational Field from the ASTG strongly suggests a solution to the supposed Radiation Problem that is thought to be faced by massive stars in their process of formation. That is, at ∼ 8-10 M sun , radiation from the nascent star is expected to halt the accretion of matter. We show that in-falling material will fall onto the equatorial disk and from there, this material will be channeled onto the forming star via the equatorial plane, thus accretion of mass continues well past the value of ∼ 8-10 M sun , albeit via the disk. Along the equatorial plane, the net force (with the radiation force included) on any
The physics of blackbody radiation: A review | Jain | JASSA: Journal ...
African Journals Online (AJOL)
The physics of blackbody radiation: A review. Pushpendra K Jain, Latit K Sharma. http://dx.doi.org/10.4314/jassa.v4i2.16899 · AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL · News.
Healy, James; Lousto, Carlos O.
2018-04-01
We present the results of 74 new simulations of nonprecessing spinning black hole binaries with mass ratios q =m1/m2 in the range 1 /7 ≤q ≤1 and individual spins covering the parameter space -0.95 ≤α1 ,2≤0.95 . We supplement those runs with 107 previous simulations to study the hangup effect in black hole mergers, i.e. the delay or prompt merger of spinning holes with respect to nonspinning binaries. We perform the numerical evolution for typically the last ten orbits before the merger and down to the formation of the final remnant black hole. This allows us to study the hangup effect for unequal mass binaries leading us to identify the spin variable that controls the number of orbits before merger as S→ hu.L ^ , where S→ hu=(1 +1/2 m/2 m1 )S→ 1+(1 +1/2 m/1 m2 )S→ 2 . We also combine the total results of those 181 simulations to obtain improved fitting formulas for the remnant final black hole mass, spin and recoil velocity as well as for the peak luminosity and peak frequency of the gravitational strain, and find new correlations among them. This accurate new set of simulations enhances the number of available numerical relativity waveforms available for parameter estimation of gravitational wave observations.
The role of Einstein's general relativity theory in today's physics
International Nuclear Information System (INIS)
Bicak, J.
The relationships are discussed of the general relativity theory to other fields of today's physics. Recent results are reported of studies into gravitational radiation, relativistic astrophysics, cosmology and the quantum theory. (Z.M.)
International Nuclear Information System (INIS)
Rossi, H.H.; Hall, E.J.
1978-02-01
Research under Contract EY-76-C-02-3243 has been carried out in the area of Radiation Physics, Biophysics and Radiation Biology. During the period of this contract the major accomplishments include, in Physics, the refinement of tissue equivalent dosimetry, the formulation of the concepts of microdosimetry, the development of apparatus used in microdosimetry, and the development of ionization chambers with internal gas multiplication. Principal contributions in Radiobiology have included the determination of RBE and OER as a function of neutron energy, the study of combined effects of radiation and a variety of other agents, and the investigation of the transformation of cells in tissue culture. Theoretical research centered around the development of the theoretical framework of microdosimetry and the establishment of the Theory of Dual Radiation Action. In a cooperative effort with Brookhaven National Laboratory, a major accelerator facility dedicated exclusively to Radiobiology and Radiation Physics, has been developed. Members of the laboratory have performed extensive service to national and international organizations
Radiations at the physics-biology interface. Utilization of radiations for research
International Nuclear Information System (INIS)
Douzou, P.
1997-01-01
Structural biology, which study the relation between the structure of biomolecules and their function, is at the interface between physics and biology. With the help of large radiation instruments such as X ray diffraction and neutron scattering, important advancements have been accomplished in the understanding of specific biological functions and led to the development of protein engineering (such as directed mutagenesis)
Physics of Acoustic Radiation from Jet Engine Inlets
Tam, Christopher K. W.; Parrish, Sarah A.; Envia, Edmane; Chien, Eugene W.
2012-01-01
Numerical simulations of acoustic radiation from a jet engine inlet are performed using advanced computational aeroacoustics (CAA) algorithms and high-quality numerical boundary treatments. As a model of modern commercial jet engine inlets, the inlet geometry of the NASA Source Diagnostic Test (SDT) is used. Fan noise consists of tones and broadband sound. This investigation considers the radiation of tones associated with upstream propagating duct modes. The primary objective is to identify the dominant physical processes that determine the directivity of the radiated sound. Two such processes have been identified. They are acoustic diffraction and refraction. Diffraction is the natural tendency for an acoustic wave to follow a curved solid surface as it propagates. Refraction is the turning of the direction of propagation of sound waves by mean flow gradients. Parametric studies on the changes in the directivity of radiated sound due to variations in forward flight Mach number and duct mode frequency, azimuthal mode number, and radial mode number are carried out. It is found there is a significant difference in directivity for the radiation of the same duct mode from an engine inlet when operating in static condition and in forward flight. It will be shown that the large change in directivity is the result of the combined effects of diffraction and refraction.
Comics in Modern Physics: Learning Blackbody Radiation through Quasi-History of Physics
Ozdemir, Ertugrul
2017-01-01
The purpose of this study is to create a short comic story about historical emergence of Planck's explanation of blackbody radiation and to investigate what students learn from it and what they think about the usage of comics in modern physics course. The participants are a small group of undergraduate students studying at department of science…
Osmaston, Miles F.
2013-09-01
the means for displacing its local density exist; that, we show, is the nature of gravitational action and brings gravitation into the electromagnetic family of forces. Under (B) the particle mass is measured by the aether-sucking capability of its vortex, positiveonly gravitation being because the outward-diminishing force developed by each makes mutual convergence at any given point the statistically prevalent expectation. This activity maintains a radial aether (charge) density gradient - the Gravity-Electric (G-E) Field - around and within any gravitationally retained assemblage. So Newton's is an incomplete description of gravitation; the corresponding G-E field is an inseparable facet of the action. The effect on c of that charge density gradient yields gravitational lensing. We find that G-E field action on plasma is astronomically ubiquitous. This strictly radial outward force on ions has the property of increasing the orbital angular momentum of material, by moving it outwards, but at constant tangential velocity. Spiral galaxies no longer require Cold Dark Matter (CDM) to explain this. The force (maybe 30 V.m-1 at solar surface) has comprehensive relevance to the high orbital a.m. achieved during solar planet formation, to their prograde spins and to exoplanet observations. The growth of high-mass stars is impossible if radiation pressure rules, whereas G-E field repulsion is low during dust-opaque infall, driving their prodigious mass loss rates when infall ceases and the star establishes an ionized environment. Its biggest force-effect (~1012 V.m-1) is developed at neutron stars, where it is likely the force of supernova explosions, and leads to a fertile model for pulsars and the acceleration of 1019 eV extreme-energy cosmic rays. Our only directly observed measure of the G-E field is recorded at about 1 V.m-1 in the ionosphere-to-Earth electric potential. And temporary local changes of ionosphere electron density, monitored by radio and satellite, have
Leetz, Hans-Karl; Eipper, Hermann Hans; Gfirtner, Hans; Schneider, Peter; Welker, Klaus
2003-10-01
To get a general idea of the actual staffing level situation in medical radiation physics in 1999 a survey was carried out by the task-group "Personalbedarf" of Deutsche Gesellschaft für Medizinische Physik (DGMP) among all DGMP-members who are active in this field. Main components for equipment and activities are defined in Report 8 and 10 of DGMP for staffing requirements in medical radiation physics. 322 forms were sent out, 173 of them have been evaluated. From the answers regarding equipment and activities numbers for staff are calculated by the methods given in Report 8 and 10 for this spot check target and compared with effective staffing levels. The data of the spot check are then extrapolated on total Germany. The result is a calculated deficit of 865 medical physicists for the whole physics staff, 166 of them in radiation therapy. From the age distribution of DGMP-members and the calculated deficit resulted a training capacity of about 100 medical physicists at all per year (19 in radiation therapy) if the deficit shall be cut back in 10 years.
Department of Environmental and Radiation Transport Physics - Overview
International Nuclear Information System (INIS)
Woznicka, U.
2001-01-01
Full text: We deal with environmental physics and the radiation transport physics, both theoretically and experimentally. Some results find their way to practical applications. Our environmental physics research encompasses hydrogeological problems as well as measurements of trace elements in the atmosphere and in the water. Theoretical (analytical and numerical) and experimental issues of the radiation transport and radiation fields are our main field of research. The interest in radiation transport phenomena is stimulated by their importance for the environmental physics, industrial and nuclear facilities and methods of geophysical. Environmental isotopes and noble gases are used in the investigation of water-bearing geological formations in order to determine the origin and age of groundwater. The papers listed below and three ''Reports on research'' present recent achievements in this field. The gas chromatography methods are used for monitoring the anthropogenic trace gases (SF 6 and freons), which participate in the Earth green-house effect. A very high detection level of SF 6 in water, 0.0028 fg/cm 3 H 2 0, has been reached as required for hydrogeological purposes. A preliminary verification of the SF 6 tracer method for dating young groundwaters by the tritium method has been carried out. We carried on the work on a method of radon measurement in soil in connection with geological conditions. The national seminar ''Radon in Environment'' organized at the INP aroused an interest of Polish scientific centres in that field. The seminar gathered 60 participants who presented 24 oral reports and 8 posters. Within the scope of the radiation transport physics we studied thermal neutron transport in finite hydrogenous media. Advantages and limitations of a Monte Carlo code (MCNP) in thermal neutron transport simulations have been examined by both the analytical solution and the experiment on the INP pulsed neutron generator. An interesting contribution to the
Solar Radiation Received by Slopes Using COMS Imagery, a Physically Based Radiation Model, and GLOBE
Directory of Open Access Journals (Sweden)
Jong-Min Yeom
2016-01-01
Full Text Available This study mapped the solar radiation received by slopes for all of Korea, including areas that are not measured by ground station measurements, through using satellites and topographical data. When estimating insolation with satellite, we used a physical model to measure the amount of hourly based solar surface insolation. Furthermore, we also considered the effects of topography using the Global Land One-Kilometer Base Elevation (GLOBE digital elevation model (DEM for the actual amount of incident solar radiation according to solar geometry. The surface insolation mapping, by integrating a physical model with the Communication, Ocean, and Meteorological Satellite (COMS Meteorological Imager (MI image, was performed through a comparative analysis with ground-based observation data (pyranometer. Original and topographically corrected solar radiation maps were created and their characteristics analyzed. Both the original and the topographically corrected solar energy resource maps captured the temporal variations in atmospheric conditions, such as the movement of seasonal rain fronts during summer. In contrast, although the original solar radiation map had a low insolation value over mountain areas with a high rate of cloudiness, the topographically corrected solar radiation map provided a better description of the actual surface geometric characteristics.
Hakim, Rémi
1994-01-01
Il existe à l'heure actuelle un certain nombre de théories relativistes de la gravitation compatibles avec l'expérience et l'observation. Toutefois, la relativité générale d'Einstein fut historiquement la première à fournir des résultats théoriques corrects en accord précis avec les faits.
Gravitation, Symmetry and Undergraduates
Jorgensen, Jamie
2001-04-01
This talk will discuss "Project Petrov" Which is designed to investigate gravitational fields with symmetry. Project Petrov represents a collaboration involving physicists, mathematicians as well as graduate and undergraduate math and physics students. An overview of Project Petrov will be given, with an emphasis on students' contributions, including software to classify and generate Lie algebras, to classify isometry groups, and to compute the isometry group of a given metric.
General Relativity and Gravitation
Ehlers, J.; Murdin, P.
2000-11-01
The General Theory of Relativity (GR), created by Albert Einstein between 1907 and 1915, is a theory both of gravitation and of spacetime structure. It is based on the assumption that matter, via its energy-momentum, interacts with the metric of spacetime, which is considered (in contrast to Newtonian physics and SPECIAL RELATIVITY) as a dynamical field having degrees of freedom of its own (GRAVI...
Radiation shielding and health physics instrumentation for PET medical cyclotrons
International Nuclear Information System (INIS)
Mukherjee, B.
2002-01-01
Full text: Modern Medical Cyclotrons produce a variety of short-lived positron emitting PET radioisotopes, and as a result are the source of intense neutron and gamma radiations. Since such cyclotrons are housed within hospitals or medical clinics, there is significant potential for un-intentional exposure to staff or patients in proximity to cyclotron facilities. Consequently, the radiological hazards associated with Cyclotrons provide the impetus for an effective radiological shielding and continuous monitoring of various radiation levels in the cyclotron environment. Management of radiological hazards is of paramount importance for the safe operation of a Medical Cyclotron facility. This work summarised the methods of shielding calculations for a compact hospital based Medical Cyclotron currently operating in Canada, USA and Australia. The design principle and operational history of a real-time health physics monitoring system (Watchdog) operating at a large multi-energy Medical Cyclotron is also highlighted
Quantum biological gravitational wave detectors
International Nuclear Information System (INIS)
Kopvillem, U.Kh.
1985-01-01
A possibility of producing biological detectors of gravitational waves is considered. High sensitivity of biological systems to outer effects can be ensured by existence of molecule subgroups in Dicke states. Existence of clusters in Dicke state-giant electric dipoles (GED) is supposed in the Froehlich theory. Comparison of biological and physical detectors shows that GED systems have unique properties for detection of gravitational waves if the reception range is narrow
International Nuclear Information System (INIS)
Ngoumou, Judith; Hubber, David; Dale, James E.; Burkert, Andreas
2015-01-01
Massive stars shape the surrounding interstellar matter (ISM) by emitting ionizing photons and ejecting material through stellar winds. To study the impact of the momentum from the wind of a massive star on the surrounding neutral or ionized material, we implemented a new HEALPix-based momentum-conserving wind scheme in the smoothed particle hydrodynamics (SPH) code SEREN. A qualitative study of the impact of the feedback from an O7.5-like star on a self-gravitating sphere shows that on its own, the transfer of momentum from a wind onto cold surrounding gas has both a compressing and dispersing effect. It mostly affects gas at low and intermediate densities. When combined with a stellar source's ionizing ultraviolet (UV) radiation, we find the momentum-driven wind to have little direct effect on the gas. We conclude that during a massive star's main sequence, the UV ionizing radiation is the main feedback mechanism shaping and compressing the cold gas. Overall, the wind's effects on the dense gas dynamics and on the triggering of star formation are very modest. The structures formed in the ionization-only simulation and in the combined feedback simulation are remarkably similar. However, in the combined feedback case, different SPH particles end up being compressed. This indicates that the microphysics of gas mixing differ between the two feedback simulations and that the winds can contribute to the localized redistribution and reshuffling of gas
Françoise Benz
2006-01-01
2005-2006 ACADEMIC TRAINING PROGRAMME LECTURE SERIES 27, 28, 29 June 11:00-12:00 - TH Conference Room, bldg. 4 The use of Monte Carlo radiation transport codes in radiation physics and dosimetry F. Salvat Gavalda,Univ. de Barcelona, A. FERRARI, CERN-AB, M. SILARI, CERN-SC Lecture 1. Transport and interaction of electromagnetic radiation F. Salvat Gavalda,Univ. de Barcelona Interaction models and simulation schemes implemented in modern Monte Carlo codes for the simulation of coupled electron-photon transport will be briefly reviewed. Different schemes for simulating electron transport will be discussed. Condensed algorithms, which rely on multiple-scattering theories, are comparatively fast, but less accurate than mixed algorithms, in which hard interactions (with energy loss or angular deflection larger than certain cut-off values) are simulated individually. The reliability, and limitations, of electron-interaction models and multiple-scattering theories will be analyzed. Benchmark comparisons of simu...
International Nuclear Information System (INIS)
Hall, E.J.
1986-07-01
This is the annual report of the Radiological Research Laboratory of the Department of Radiation Oncology, Columbia University. The bulk of the research of the Laboratory involves basic and fundamental aims, not confined to radiotherapy. Research carried out in the Laboratory covers the determination of microdosimetry quantities, computer simulation of particle tracks, determination of oncogenic transformation, and the transfection of DNA into cells. The Hallmark of the Laboratory is the interaction between physics and biology
International Nuclear Information System (INIS)
Hall, E.J.; Zaider, M.; Delegianis, M.J.
1988-07-01
Research at the Radiological Research Laboratory is a blend of physics, chemistry, and biology, involving research at the basic level with the admixture of a small proportion of pragmatic or applied research in support of radiation protection and/or radiation therapy. At the current level of funding, approximately one quarter of the research of the Laboratory could be regarded as in support of radiotherapy, with the remainder addressing more basic issues. The new initiatives have been in two directions. First, there has been an increased emphasis on research in radiation chemistry, inasmuch as this subject which involves the study of free radicals and fast radiation chemistry processes starts to bridge the gap between physics and biology, between the initial deposition of radiant energy and its final expression in terms of biological consequences. Second, the emphasis in the biological research has moved towards studies at the molecular level, with the appointment of new members of staff with expertise in this area. Individual chapters were processed separately for the data base
International Nuclear Information System (INIS)
Fluke, D.J.
1984-08-01
The report comprises a teaching text, encompassing all physical radiations likely to be of biological interest, and the relevant biological effects and their significance. Topics include human radiobiology, delayed effects, radiation absorption in organisms, aqueous radiation chemistry, cell radiobiology, mutagenesis, and photobiology
Energy Technology Data Exchange (ETDEWEB)
Leutwyler, H; Mallik, S
1986-12-01
The effective action for fermions moving in external gravitational and gauge fields is analyzed in terms of the corresponding external field propagator. The central object in our approach is the covariant energy-momentum tensor which is extracted from the regular part of the propagator at short distances. It is shown that the Lorentz anomaly, the conformal anomaly and the gauge anomaly can be expressed in terms of the local polynomials which determine the singular part of the propagator. (There are no coordinate anomalies). Except for the conformal anomaly, for which we give explicit representations only in dless than or equal to4, we consider an arbitrary number of dimensions.
International Nuclear Information System (INIS)
Turner, E.L.
1989-01-01
The author discusses how gravitational lens studies is becoming a major focus of extragalactic astronomy and cosmology. This review is organized into five parts: an overview of the observational situation, a look at the state of theoretical work on lenses, a detailed look at three recently discovered types of lensing phenomena (luminous arcs, radio rings, quasar-galaxy associations), a review of progress on two old problems in lens studies (deriving unique lens mass distribution models, measurements of differential time delays), and an attempt to look into the future of lens studies
Vectorial and plane energy fluences - useful concepts in radiation physics
International Nuclear Information System (INIS)
Carlsson, C.A.
1977-06-01
The vectorial physical quantities describing the radiation field are defined in this report. The use of these quantities is rare in the radiation dosimetry literature since a knowledge of the directions of motion of the ionizing particle is often uninteresting when determining absorbed doses. However the plane energy fluence rate is a useful quantity in cases with plane irradiation geometries. The plane energy fluence rate is closely related to the vectorial energy fluence rate. The backscattering properties of a medium can be expressed in terms either of its albedo or its reflection-coefficient (backscatter-coefficient). These quantities are discussed in order to derive useful relations between the plane energy fluence and the energy fluence at points on an extended plane surface. Examples are also given of erroneous use of energy fluence instead of vectorial or plane energy fluence. The examples are taken from roentgen diagnostic examinations. To prevent further mistakes it could be valuable if the quantities of vectorial and plane fluences were introduced in text books in radiation dosimetry. Awaiting for this, this report may hopefully be useful. (E.R.)
Compatibility analysis of DUPIC fuel (part 3) - radiation physics analysis
International Nuclear Information System (INIS)
Kim, Chun Soo; Bae, Dae Seok; Kim, Kyung Su; Park, Byung Yun; Koh, Young Kown
2000-04-01
As a part of the compatibility analysis of DUPIC fuel in CANDU reactors, the radiation physics calculations have been performed for the CANDU primary shielding system, thermal shield, radiation damage, transportation cask and storage. At first, the primary shield system was assessed for the DUPIC fuel core, which has shown that the dose rates and heat deposition rates through the primary shield of the DUPIC fuel core are not much different from those of natural uranium core because the power levels on the core periphery are similar for both cores. Secondly, the radiation effects on the critical components and the themal shields were assessed when the DUPIC fuel is loaded in CANDU reactors. Compared with the displacement per atom (DPA) of the critical component for natural uranium core, that for the DUPIC fuel core was increased by -30% for the innermost groove and the weld points and by -10% for the corner of the calandria subshells and annular plates in the calandria, respectivdely. Finally, the feasibility study of the DUPIC fuel handling was performed, which has shown that all handling and inspection of the DUPIC fuel bundles be done remotely and behind a shielding wall. For the transportation of the DUPIC fuel, the preliminary study has shown that there shold be no technical problem th design a transportation cask for the fresh and spent DUPIC fuel bundles. For the storage of the fresh and spent DUPIC fuels, there is no the criticality safety problem unless the fuel bundle geometry is destroyed
Compatibility analysis of DUPIC fuel (part 3) - radiation physics analysis
Energy Technology Data Exchange (ETDEWEB)
Kim, Chun Soo; Bae, Dae Seok; Kim, Kyung Su; Park, Byung Yun; Koh, Young Kown
2000-04-01
As a part of the compatibility analysis of DUPIC fuel in CANDU reactors, the radiation physics calculations have been performed for the CANDU primary shielding system, thermal shield, radiation damage, transportation cask and storage. At first, the primary shield system was assessed for the DUPIC fuel core, which has shown that the dose rates and heat deposition rates through the primary shield of the DUPIC fuel core are not much different from those of natural uranium core because the power levels on the core periphery are similar for both cores. Secondly, the radiation effects on the critical components and the themal shields were assessed when the DUPIC fuel is loaded in CANDU reactors. Compared with the displacement per atom (DPA) of the critical component for natural uranium core, that for the DUPIC fuel core was increased by -30% for the innermost groove and the weld points and by -10% for the corner of the calandria subshells and annular plates in the calandria, respectivdely. Finally, the feasibility study of the DUPIC fuel handling was performed, which has shown that all handling and inspection of the DUPIC fuel bundles be done remotely and behind a shielding wall. For the transportation of the DUPIC fuel, the preliminary study has shown that there shold be no technical problem th design a transportation cask for the fresh and spent DUPIC fuel bundles. For the storage of the fresh and spent DUPIC fuels, there is no the criticality safety problem unless the fuel bundle geometry is destroyed.
A study of the neutrino-gravitation interaction
International Nuclear Information System (INIS)
Soares, I.D.
1976-01-01
A study of the neutrino-gravitation interaction is made in the framework of Einstein-Dirac coupled equations. Two classes of solutions are obtained, corresponding to two specific physical situations. One cosmological model with expansion is obtained, having neutrinos as the only curvature source; their properties and the parameters which can to characterize the solution as a cosmological model are studied. The second class of solutions corresponds to a naive complete model of a spherically symmetric star emitting neutrinos: the inner region is suposed to be built up of a spherically symmetric distribution of a perfect fluid, bounded in space and which emitts neutrinos; the star matter is considered transparent for neutrinos; the outer region contains only neutrinos and gravitational field. The problem of neutrino compatibility with spherically symmetric gravitational fields is examined. The local conservation laws and the function conditions of the inner and outer solutions in the fluid surface are studied and permit to characterize two kinds of solutions. In one case, the solution describes the neutrino emission phase, with consequent configuration contraction, immediately before the fluid to be completely contained in the interior of the schwarzchild radius, when the neutrino emission and the star contraction stop. The other possibility can correspond to a quasi-stationary configuration, with neutrino emission, where the relativistic equation of radiative equilibrium permits to define the equivalent of 'Radiation pressure' for neutrinos, which acts in the same sense of the gravitational pressure. (L.C.) [pt
Major Gravitational Phenomena Explained by the Micro-Quanta Paradigm
Directory of Open Access Journals (Sweden)
Michelini M.
2010-01-01
Full Text Available Some major problems of physics, which remained unsolved within classical and rel- ativistic gravitation theories, are explained adopting the quantum gravity interaction descending from the micro-quanta paradigm. The energy source of the gravitational power P g r , which heats and contracts the Bok’s gas globules harbouring the future stars, is identified and defined as well as the gravitational power generated on the solid / fluid planets. Calculations are carried out to make the comparison between P g r predicted for the solar giant planets and the measured infrared radiation power P int coming from the interior. The case of planets with solid crust (Earth, etc. requires a particular attention due to the threat to stability produced by the thermal dilatation. An analysis is done of the Earth’s planetary equilibrium which may be attained eliminating the temperature rise through the migration of hot internal magma across the crust fractured by earth- quakes. The temperatures observed up to 420,000 years ago in Antartica through Vostok and Epica ice cores suggest the possibility that the Earth gravitational power P g r may be radiated in space through these temperature cycles (Glacial Eras. In this general frame the Earth’s high seismicity and the dynamics of Plate tectonics may find their origin.
Major Gravitational Phenomena Explained by the Micro-Quanta Paradigm
Directory of Open Access Journals (Sweden)
Michelini M.
2010-01-01
Full Text Available Some major problems of physics, which remained unsolved within classical and relativistic gravitation theories, are explained adopting the quantum gravity interaction descending from the micro-quanta paradigm. The energy source of the gravitational power $P_{gr}$, which heats and contracts the Bok's gas globules harbouring the future stars, is identified and defined as well as the gravitational power generated on the solid/fluid planets. Calculations are carried out to make the comparison between $P_{gr}$ predicted for the solar giant planets and the measured infrared radiation power $P_{int}$ coming from the interior. The case of planets with solid crust (Earth, etc. requires a particular attention due to the threat to stability produced by the thermal dilatation. An analysis is done of the Earth's planetary equilibrium which may be attained eliminating the temperature rise through the migration of hot internal magma across the crust fractured by earthquakes. The temperatures observed up to 420,000 years ago in Antartica through Vostok and Epica ice cores suggest the possibility that the Earth gravitational power $P_{gr}$ may be radiated in space through these temperature cycles (Glacial Eras. In this general frame the Earth's high seismicity and the dynamics of Plate tectonics may find their origin.
Multiscale approach to the physics of radiation damage with ions
International Nuclear Information System (INIS)
Surdutovich, E.; Solov'yov, A.
2014-01-01
The multiscale approach to the assessment of bio-damage resulting upon irradiation of biological media with ions is reviewed, explained and compared to other approaches. The processes of ion propagation in the medium concurrent with ionization and excitation of molecules, transport of secondary products, dynamics of the medium, and biological damage take place on a number of different temporal, spatial and energy scales. The multiscale approach, a physical phenomenon-based analysis of the scenario that leads to radiation damage, has been designed to consider all relevant effects on a variety of scales and develop an approach to the quantitative assessment of biological damage as a result of irradiation with ions. Presently, physical and chemical effects are included in the scenario while the biological effects such as DNA repair are only mentioned. This paper explains the scenario of radiation damage with ions, overviews its major parts, and applies the multiscale approach to different experimental conditions. On the basis of this experience, the recipe for application of the multiscale approach is formulated. The recipe leads to the calculation of relative biological effectiveness. (authors)
A quality management model for radiation oncology physics
International Nuclear Information System (INIS)
Sternick, E.S.
1991-01-01
State-of-the-art radiation physics quality programs operate in a data rich environment. Given the abundance of recordable events, any formalism that serves to identify and monitor a set of attributes correlated with quality is to be regarded as an important management tool. The hierarchical tree structure model describes one such useful planning method. Of the several different types of tree structures, one of the most appropriate for quality management is the pyramid model. In this model, the associations between an overall program objective and the intermediate steps leading to its attainment, are indicated by both horizontal and vertical connectors. The overall objective of the system under study occupies the vertex of the pyramid, while the level immediately below contains its principal components. Further subdivisions of each component occur in successively lower levels. The tree finally terminates at a base level consisting of actions or requirements that must be fulfilled in order to satisfy the overall objective. A pyramid model for a radiation oncology physics quality program is discussed in detail. (author). 21 refs., 4 figs., 6 tabs
Physical factors in cataractogenesis: ambient ultraviolet radiation and temperature
International Nuclear Information System (INIS)
Sliney, D.H.
1986-01-01
A number of environmental cofactors have been implicated in cataracto-genesis. Two have received the greatest attention: ultraviolet radiation (UVR) and ambient temperature. Unfortunately, both temperature and UVR levels vary similarly with geographical latitude. Careful attention to several more refined physical variables and the geometry of exposure may permit investigators to separate the contributory effects of these two physical agents. This paper briefly reviews the available data, estimates the variation of lenticular temperature with ambient temperature, and provides measurements of short-wavelength (UV-B) UVR exposure to the human eye with different meterological conditions. The study attempts to provide epidemiological investigators with more detailed information necessary to perform more accurate studies of cataract and other ocular pathologies that appear to be related to environmental factors. Ocular UV-B radiation exposure levels were measured at nine locations in the USA near 40 degrees latitude at elevations from sea level to 8000 ft. Terrain reflectance is shown to be much more important than terrain elevation; cloud cover and haze may actually increase ocular exposure; and the value of wearing brimmed hats and spectacles varies with the environment. Several avenues for future research are suggested
Radiation oncology medical physics education and training in Queensland
International Nuclear Information System (INIS)
West, M.P.; Thomas, B.J.
2011-01-01
Full text: The training education and accreditation program (TEAP) for radiation oncology commenced formally in Queensland in 2008 with an initial intake of nine registrars. In 2011 there are 17 registrars across four ACPSEM accredited Queensland Health departments (Mater Radiation Oncology Centre, Princess Alexandria Hospital, Royal Brisbane and Women's Hospital, Townsville Hospital). The Queensland Statewide Cancer Services Plan 2008-2017 outlines significant expansion to oncology services including increases in total number of treatment machines from 14 (2007) to 29-31 (2017) across existing and new clinical departments. A direct implication of this will be the number of qualified ROMPs needed to maintain and develop medical physics services. This presentation will outline ongoing work in the ROMP education and Training portfolio to develop, facilitate and provide training activities for ROMPs undertaking TEAP in the Queensland public system. Initiatives such as Department of Health and Aging scholarships for medical physics students, and the educational challenges associated with competency attainment will also be discussed in greater detail.
Energy Technology Data Exchange (ETDEWEB)
Hall, E.J.; Zaider, M.
1993-05-01
Research at the Center for Radiological Research is a multidisciplenary blend of physics, chemistry and biology aimed at understanding the mechanisms involved in the health problems resulting from human exposure to ionizing radiations. The focus is increased on biochemistry and the application of the techniques of molecular biology to the problems of radiation biology. Research highlights of the program from the past year are described. A mathematical model describing the production of single-strand and double-strand breaks in DNA as a function radiation quality has been completed. For the first time Monte Carlo techniques have been used to obtain directly the spatial distribution of DNA moieties altered by radiation. This information was obtained by including the transport codes a realistic description of the electronic structure of DNA. We have investigated structure activity relationships for the potential oncogenicity of a new generation of bioreductive drugs that function as hypoxic cytotoxins. Experimental and theoretical investigation of the inverse dose rate effect, whereby medium LET radiations actually produce an c effect when the dose is protracted, is now at a point where the basic mechanisms are reasonably understood and the complex interplay between dose, dose rate and radiation quality which is necessary for the effect to be present can now be predicted at least in vitro. In terms of early radiobiological damage, a quantitative link has been established between basic energy deposition and locally multiply damaged sites, the radiochemical precursor of DNA double strand breaks; specifically, the spatial and energy deposition requirements necessary to form LMDs have been evaluated. For the first time, a mechanically understood ``biological fingerprint`` of high-LET radiation has been established. Specifically measurement of the ratio of inter-to intra-chromosomal aberrations produces a unique signature from alpha-particles or neutrons.
Gravitational-Wave Luminosity of Binary Neutron Stars Mergers
Zappa, Francesco; Bernuzzi, Sebastiano; Radice, David; Perego, Albino; Dietrich, Tim
2018-03-01
We study the gravitational-wave peak luminosity and radiated energy of quasicircular neutron star mergers using a large sample of numerical relativity simulations with different binary parameters and input physics. The peak luminosity for all the binaries can be described in terms of the mass ratio and of the leading-order post-Newtonian tidal parameter solely. The mergers resulting in a prompt collapse to black hole have the largest peak luminosities. However, the largest amount of energy per unit mass is radiated by mergers that produce a hypermassive neutron star or a massive neutron star remnant. We quantify the gravitational-wave luminosity of binary neutron star merger events, and set upper limits on the radiated energy and the remnant angular momentum from these events. We find that there is an empirical universal relation connecting the total gravitational radiation and the angular momentum of the remnant. Our results constrain the final spin of the remnant black hole and also indicate that stable neutron star remnant forms with super-Keplerian angular momentum.
Gravitational-Wave Luminosity of Binary Neutron Stars Mergers.
Zappa, Francesco; Bernuzzi, Sebastiano; Radice, David; Perego, Albino; Dietrich, Tim
2018-03-16
We study the gravitational-wave peak luminosity and radiated energy of quasicircular neutron star mergers using a large sample of numerical relativity simulations with different binary parameters and input physics. The peak luminosity for all the binaries can be described in terms of the mass ratio and of the leading-order post-Newtonian tidal parameter solely. The mergers resulting in a prompt collapse to black hole have the largest peak luminosities. However, the largest amount of energy per unit mass is radiated by mergers that produce a hypermassive neutron star or a massive neutron star remnant. We quantify the gravitational-wave luminosity of binary neutron star merger events, and set upper limits on the radiated energy and the remnant angular momentum from these events. We find that there is an empirical universal relation connecting the total gravitational radiation and the angular momentum of the remnant. Our results constrain the final spin of the remnant black hole and also indicate that stable neutron star remnant forms with super-Keplerian angular momentum.
Use of ionising radiation in the teaching of physics and chemistry
International Nuclear Information System (INIS)
2000-01-01
The guide lays down the safety requirements for the use of radiation in school education, as well as the principles regulating the use of radiation sources without the safety licence referred to in section 16 of the Finnish Radiation Act (592/1991). The guide covers the use of radiation sources emitting ionising radiation in elementary schools and high schools, as well as the use of radiation in the teaching of physics and chemistry in vocational training institutions and corresponding educational institutions
Use of ionizing radiation in the teaching of physics and chemistry
International Nuclear Information System (INIS)
1993-01-01
The guide specifies the safety requirements for the use of radiation in school education as well as the principles regulating the use of radiation sources without the safety license referred to the Section 16 of the Finnish Radiation Act (592/91). The guide covers the use of radiation sources emitting ionizing radiation in elementary schools and high schools, as well as the use of radiation in the teaching of physics and chemistry in vocational training institutions and corresponding educational institutions. (3 refs.)
Gravitational properties of antimatter
International Nuclear Information System (INIS)
Goldman, T.; Nieto, M.M.
1985-01-01
Quantum gravity is at the forefront of modern particle physics, yet there are no direct tests, for antimatter, of even the principle of equivalence. We note that modern descriptions of gravity, such as fibre bundles and higher dimensional spacetimes, allow violations of the commonly stated form of the principle of equivalence, and of CPT. We review both indirect arguments and experimental tests of the expected gravitational properties of CPT-conjugate states. We conclude that a direct experimental test of the gravitational properties of antimatter, at the 1% (or better) level, would be of great value. We identify some experimental reasons which make the antiproton a prime candidate for this test, and we strongly urge that such an experiment be done at LEAR. 21 references
Gravitation and electromagnetism
Apsel, D
1979-01-01
Through an examination of the Bohm-Aharonov experiment, a new theory of gravitation and electromagnetism is proposed. The fundamental assumption of the theory is that the motion of a particle in a combination of gravitational and electromagnetic fields is determined from a variational principle of the form delta integral /sub A//sup B /d tau =0. The form of the physical time is determined from an examination of the Maxwell-Einstein action function. The field and motion equations are formally identical to those of Maxwell-Einstein theory. The theory predicts that even in a field-free region of space, electromagnetic potentials can alter the phase of a wave function and the lifetime of a charged particle. The phase alteration has been observed in the Bohm-Aharonov experiment. There is an indication that the lifetime alteration has shown up in a recent CERN storage ring experiment. Experimental tests are proposed. (11 refs).
Xiao, Ying; Bernstein, Karen De Amorim; Chetty, Indrin J; Eifel, Patricia; Hughes, Lesley; Klein, Eric E; McDermott, Patrick; Prisciandaro, Joann; Paliwal, Bhudatt; Price, Robert A; Werner-Wasik, Maria; Palta, Jatinder R
2011-11-15
In 2004, the American Society for Radiation Oncology (ASTRO) published its first physics education curriculum for residents, which was updated in 2007. A committee composed of physicists and physicians from various residency program teaching institutions was reconvened again to update the curriculum in 2009. Members of this committee have associations with ASTRO, the American Association of Physicists in Medicine, the Association of Residents in Radiation Oncology, the American Board of Radiology (ABR), and the American College of Radiology. Members reviewed and updated assigned subjects from the last curriculum. The updated curriculum was carefully reviewed by a representative from the ABR and other physics and clinical experts. The new curriculum resulted in a recommended 56-h course, excluding initial orientation. Learning objectives are provided for each subject area, and a detailed outline of material to be covered is given for each lecture hour. Some recent changes in the curriculum include the addition of Radiation Incidents and Bioterrorism Response Training as a subject and updates that reflect new treatment techniques and modalities in a number of core subjects. The new curriculum was approved by the ASTRO board in April 2010. We anticipate that physicists will use this curriculum for structuring their teaching programs, and subsequently the ABR will adopt this educational program for its written examination. Currently, the American College of Radiology uses the ASTRO curriculum for their training examination topics. In addition to the curriculum, the committee updated suggested references and the glossary. The ASTRO physics education curriculum for radiation oncology residents has been updated. To ensure continued commitment to a current and relevant curriculum, the subject matter will be updated again in 2 years. Copyright © 2011 Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Xiao Ying; De Amorim Bernstein, Karen; Chetty, Indrin J.; Eifel, Patricia; Hughes, Lesley; Klein, Eric E.; McDermott, Patrick; Prisciandaro, Joann; Paliwal, Bhudatt; Price, Robert A.; Werner-Wasik, Maria; Palta, Jatinder R.
2011-01-01
Purpose: In 2004, the American Society for Radiation Oncology (ASTRO) published its first physics education curriculum for residents, which was updated in 2007. A committee composed of physicists and physicians from various residency program teaching institutions was reconvened again to update the curriculum in 2009. Methods and Materials: Members of this committee have associations with ASTRO, the American Association of Physicists in Medicine, the Association of Residents in Radiation Oncology, the American Board of Radiology (ABR), and the American College of Radiology. Members reviewed and updated assigned subjects from the last curriculum. The updated curriculum was carefully reviewed by a representative from the ABR and other physics and clinical experts. Results: The new curriculum resulted in a recommended 56-h course, excluding initial orientation. Learning objectives are provided for each subject area, and a detailed outline of material to be covered is given for each lecture hour. Some recent changes in the curriculum include the addition of Radiation Incidents and Bioterrorism Response Training as a subject and updates that reflect new treatment techniques and modalities in a number of core subjects. The new curriculum was approved by the ASTRO board in April 2010. We anticipate that physicists will use this curriculum for structuring their teaching programs, and subsequently the ABR will adopt this educational program for its written examination. Currently, the American College of Radiology uses the ASTRO curriculum for their training examination topics. In addition to the curriculum, the committee updated suggested references and the glossary. Conclusions: The ASTRO physics education curriculum for radiation oncology residents has been updated. To ensure continued commitment to a current and relevant curriculum, the subject matter will be updated again in 2 years.
International Nuclear Information System (INIS)
Logunov, A.A.
1989-01-01
The author believes that the General Relativity Theory (GRT) suffers from a substantial deficiency since it ignors the fundamental laws of conservation of energy. Einstein neglected the classical concept of the field due to his belief in the truth of the principle of equivalence between forces of inertid gravitation. This equivalence leads, as the author says, to nonequivalence of these forces, making GRT logically contradictory from the physical point of view. The author considers GRT as a certain stage in the course of the study of space-time and gravitation, and suggests a new theory called the Relativistic Theory of Gravitation (RTG) which obeys the fundamental laws of conservation, and which is justified in some of its aspects by astronomical observations. RTG does not suffer from some deficiencies met in Einsteins theory. One is nonunique predictions of gravitation effects within the boundaries of the solar system. Also, RTG refuses some hypothesis as that of black holes. 7 refs
Kuhn, Jochen; Vogt, Patrik
2013-01-01
New media technology becomes more and more important for our daily life as well as for teaching physics. Within the scope of our N.E.T. research project we develop experiments using New Media Experimental Tools (N.E.T.) in physics education and study their influence on students learning abilities. We want to present the possibilities e.g. of…
General relativity and gravitation, 1989
International Nuclear Information System (INIS)
Ashby, N.; Bartlett, D.F.; Wyss, W.
1990-01-01
This volume records the lectures and symposia of the 12th International Conference on General Relativity and Gravitation. Plenary lecturers reviewed the major advances since the previous conference in 1986. The reviews cover classical and quantum theory of gravity, colliding gravitational waves, gravitational lensing, relativistic effects on pulsars, tests of the inverse square law, numerical relativity, cosmic microwave background radiation, experimental tests of gravity theory, gravitational wave detectors, and cosmology. The plenary lectures are complemented by summaries of symposia, provided by the chairmen. Almost 700 contributed papers were presented at these and they cover an even wider range of topics than the plenary talks. The book provides a comprehensive guide to research activity in both experimental and theoretical gravitation and its applications in astrophysics and cosmology. It will be essential reading for research workers in these fields, as well as theoretical and experimental physicists, astronomers, and mathematicians who wish to be acquainted with modern developments in gravitational theory and general relativity. All the papers and summaries of the workshop sessions are indexed separately. (16 united talks, 20 workshop sessions). (author)
Energy Technology Data Exchange (ETDEWEB)
Krieger, Hanno
2017-07-01
The following topics are dealt with: Types of radiation and radiation fields, the atomic structure, radioactive decays, decay law, natural and artificial radioactivity, interactions of ionizing photon radiation, attenuation of neutral-particle beams, interactions of neutron radiation, interactions of charged particles, ionization and energy transfer, radiation doses, radiation protection phantoms, foundations of the radiation biology of cells, effects and risks of ionizing radiation, radiation expositions of men with ionizing radiation, radiation protection law, practical radiation protection against ionizing radiations, radiation eposures in medical radiology. (HSI)
Energy Technology Data Exchange (ETDEWEB)
Burmeister, Jay, E-mail: burmeist@karmanos.org [Department of Oncology, Karmanos Cancer Center/Wayne State University, Detroit, Michigan (United States); Chen, Zhe [Department of Therapeutic Radiology, Yale University, New Haven, Connecticut (United States); Chetty, Indrin J. [Department of Radiation Oncology, Henry Ford Hospital, Detroit, Michigan (United States); Dieterich, Sonja [Department of Radiation Oncology, University of California – Davis, Sacramento, California (United States); Doemer, Anthony [Department of Radiation Oncology, Henry Ford Hospital, Detroit, Michigan (United States); Dominello, Michael M. [Department of Oncology, Karmanos Cancer Center/Wayne State University, Detroit, Michigan (United States); Howell, Rebecca M. [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); McDermott, Patrick [Department of Radiation Oncology, Beaumont Health, Royal Oak, Michigan (United States); Nalichowski, Adrian [Karmanos Cancer Center, Detroit, Michigan (United States); Prisciandaro, Joann [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Ritter, Tim [VA Ann Arbor Healthcare and the University of Michigan, Ann Arbor, Michigan (United States); Smith, Chadd [Department of Radiation Oncology, Henry Ford Hospital, Detroit, Michigan (United States); Schreiber, Eric [Department of Radiation Oncology, University of North Carolina, Chapel Hill, North Carolina (United States); Shafman, Timothy [21st Century Oncology, Fort Myers, Florida (United States); Sutlief, Steven [Department of Radiation Oncology, University of California – San Diego, La Jolla, California (United States); Xiao, Ying [Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania (United States)
2016-07-15
Purpose: The American Society for Radiation Oncology (ASTRO) Physics Core Curriculum Subcommittee (PCCSC) has updated the recommended physics curriculum for radiation oncology resident education to improve consistency in teaching, intensity, and subject matter. Methods and Materials: The ASTRO PCCSC is composed of physicists and physicians involved in radiation oncology residency education. The PCCSC updated existing sections within the curriculum, created new sections, and attempted to provide additional clinical context to the curricular material through creation of practical clinical experiences. Finally, we reviewed the American Board of Radiology (ABR) blueprint of examination topics for correlation with this curriculum. Results: The new curriculum represents 56 hours of resident physics didactic education, including a 4-hour initial orientation. The committee recommends completion of this curriculum at least twice to assure both timely presentation of material and re-emphasis after clinical experience. In addition, practical clinical physics and treatment planning modules were created as a supplement to the didactic training. Major changes to the curriculum include addition of Fundamental Physics, Stereotactic Radiosurgery/Stereotactic Body Radiation Therapy, and Safety and Incidents sections, and elimination of the Radiopharmaceutical Physics and Dosimetry and Hyperthermia sections. Simulation and Treatment Verification and optional Research and Development in Radiation Oncology sections were also added. A feedback loop was established with the ABR to help assure that the physics component of the ABR radiation oncology initial certification examination remains consistent with this curriculum. Conclusions: The ASTRO physics core curriculum for radiation oncology residents has been updated in an effort to identify the most important physics topics for preparing residents for careers in radiation oncology, to reflect changes in technology and practice since
Progress in gravitational wave detection: Interferometers
International Nuclear Information System (INIS)
Kuroda, Kazuaki
2002-01-01
A gravitational wave (GW) is a physical entity of space-time derived from Einstein's theory of general relativity. Challenging projects to observe gravitational waves are being conducted throughout the world. A Japanese project involving a 300 m baseline laser interferometer, TAMA, achieved 1000 hr of continuous observation with the best sensitivity in the world during the summer of 2001. After achieving promising results, the realization of LCGT (Large-scale Cryogenic Gravitational wave Telescope) will become possible in the near future
The MCART radiation physics core: the quest for radiation dosimetry standardization.
Kazi, Abdul M; MacVittie, Thomas J; Lasio, Giovanni; Lu, Wei; Prado, Karl L
2014-01-01
Dose-related radiobiological research results can only be compared meaningfully when radiation dosimetry is standardized. To this purpose, the National Institute of Allergy and Infectious Diseases (NIAID)-sponsored Medical Countermeasures Against Radiological Threats (MCART) consortium recently created a Radiation Physics Core (RPC) as an entity to assume responsibility of standardizing radiation dosimetry practices among its member laboratories. The animal research activities in these laboratories use a variety of ionizing photon beams from several irradiators such as 250-320 kVp x-ray generators, Cs irradiators, Co teletherapy machines, and medical linear accelerators (LINACs). In addition to this variety of sources, these centers use a range of irradiation techniques and make use of different dose calculation schemes to conduct their experiments. An extremely important objective in these research activities is to obtain a Dose Response Relationship (DRR) appropriate to their respective organ-specific models of acute and delayed radiation effects. A clear and unambiguous definition of the DRR is essential for the development of medical countermeasures. It is imperative that these DRRs are transparent between centers. The MCART RPC has initiated the establishment of standard dosimetry practices among member centers and is introducing a Remote Dosimetry Monitoring Service (RDMS) to ascertain ongoing quality assurance. This paper will describe the initial activities of the MCART RPC toward implementing these standardization goals. It is appropriate to report a summary of initial activities with the intent of reporting the full implementation at a later date.
Energy Technology Data Exchange (ETDEWEB)
Zakharov, Aleksandr F [Russian Federation State Scientific Center ' A.I. Alikhanov Institute for Theoretical and Experimental Physics' , Moscow (Russian Federation); Sazhin, Mikhail V [P.K. Shternberg State Astronomical Institute at the M.V. Lomonosov Moscow State University, Moscow (Russian Federation)
1998-10-31
The foundations of standard microlensing theory are discussed as applied to stars in the Galactic bulge, Magellanic Clouds or other nearby galaxies and gravitational microlenses assumed to lie in-between these stars and the terrestrial observer. In contrast to the review article by Gurevich et al. [48], microlensing by compact objects is mainly considered. Criteria for the identification of microlensing events are discussed as also are microlensing events not satisfying these criteria, such as non-symmetrical light curves and chromatic and polarization effects. The Large Magellanic Cloud (LMC) and Galactic bulge microlensing data of the MACHO group are discussed in detail and also the LMC data of EROS and the Galactic bulge data of OGLE are presented. A detailed comparison of theoretical predictions and observations is given. (reviews of topical problems)
International Nuclear Information System (INIS)
Zakharov, Aleksandr F; Sazhin, Mikhail V
1998-01-01
The foundations of standard microlensing theory are discussed as applied to stars in the Galactic bulge, Magellanic Clouds or other nearby galaxies and gravitational microlenses assumed to lie in-between these stars and the terrestrial observer. In contrast to the review article by Gurevich et al. [48], microlensing by compact objects is mainly considered. Criteria for the identification of microlensing events are discussed as also are microlensing events not satisfying these criteria, such as non-symmetrical light curves and chromatic and polarization effects. The Large Magellanic Cloud (LMC) and Galactic bulge microlensing data of the MACHO group are discussed in detail and also the LMC data of EROS and the Galactic bulge data of OGLE are presented. A detailed comparison of theoretical predictions and observations is given. (reviews of topical problems)
Astrometric and Timing Effects of Gravitational Waves from Localized Sources
Kopeikin, Sergei M.; Schafer, Gerhard; Gwinn, Carl R.; Eubanks, T. Marshall
1998-01-01
A consistent approach for an exhaustive solution of the problem of propagation of light rays in the field of gravitational waves emitted by a localized source of gravitational radiation is developed in the first post-Minkowskian and quadrupole approximation of General Relativity. We demonstrate that the equations of light propagation in the retarded gravitational field of an arbitrary localized source emitting quadrupolar gravitational waves can be integrated exactly. The influence of the gra...
Chiral primordial gravitational waves from a Lifshitz point.
Takahashi, Tomohiro; Soda, Jiro
2009-06-12
We study primordial gravitational waves produced during inflation in quantum gravity at a Lifshitz point proposed by Horava. Assuming power-counting renormalizability, foliation-preserving diffeomorphism invariance, and the condition of detailed balance, we show that primordial gravitational waves are circularly polarized due to parity violation. The chirality of primordial gravitational waves is a quite robust prediction of quantum gravity at a Lifshitz point which can be tested through observations of cosmic microwave background radiation and stochastic gravitational waves.
Energy Technology Data Exchange (ETDEWEB)
Scheck, Florian [Mainz Univ. (Germany). Inst. fuer Physik
2017-09-01
The following topics are dealt with: Maxwell's equations together with their symmetry and covariance, the Maxwell theory as classical field theory, simple applications of Maxwell's theory, local gauge theories, classical field theory of gravitation. (HSI)
Fundamentals of interferometric gravitational wave detectors
Saulson, Peter R
2017-01-01
LIGO's recent discovery of gravitational waves was headline news around the world. Many people will want to understand more about what a gravitational wave is, how LIGO works, and how LIGO functions as a detector of gravitational waves.This book aims to communicate the basic logic of interferometric gravitational wave detectors to students who are new to the field. It assumes that the reader has a basic knowledge of physics, but no special familiarity with gravitational waves, with general relativity, or with the special techniques of experimental physics. All of the necessary ideas are developed in the book.The first edition was published in 1994. Since the book is aimed at explaining the physical ideas behind the design of LIGO, it stands the test of time. For the second edition, an Epilogue has been added; it brings the treatment of technical details up to date, and provides references that would allow a student to become proficient with today's designs.
Possible role of torsion in gravitational theories
International Nuclear Information System (INIS)
Nieh, H.T.
1983-01-01
Torsion is of interest in an indirect way, in that it has the potential of being an important ingredient in a future successful quantum theory of gravitation. Einstein's theory of gravitation, despite its simplicity and elegance, and its successes in large-scale gravitational phenomena, can only be regarded as a macroscopic classical theory. It is a non-renormalizable quantum field theory, and, therefore, lacks the status of a good microscopic theory. It is the search for a successful quantum field theory of gravitation that poses as one of the great challenges to theoretical physics today. (Auth.)
Actuality of the Einstein theory of gravitation
International Nuclear Information System (INIS)
Ivanenko, D.D.
1982-01-01
Problems of actuality of the Einstein theory of gravitation are lightened. The great Einstein theory of gravitation is shown to remain a reliable base of understanding of modern physical world pattern and its inevitable further inexhaustible precising. The main GRT difficulties are enumirated: determination of reference systems, presence of singularities in the theory, absence of consistent determination of the gravity energy, impossibility of accounting the relations between atomic, gravitational and cosmological characteristics. The attention is paid to gauge, twistor problems and to unified interaction theory. The great contribution of the soviet science in the theory of gravitation is stressed
Chirality and gravitational parity violation.
Bargueño, Pedro
2015-06-01
In this review, parity-violating gravitational potentials are presented as possible sources of both true and false chirality. In particular, whereas phenomenological long-range spin-dependent gravitational potentials contain both truly and falsely chiral terms, it is shown that there are models that extend general relativity including also coupling of fermionic degrees of freedom to gravity in the presence of torsion, which give place to short-range truly chiral interactions similar to that usually considered in molecular physics. Physical mechanisms which give place to gravitational parity violation together with the expected size of the effects and their experimental constraints are discussed. Finally, the possible role of parity-violating gravity in the origin of homochirality and a road map for future research works in quantum chemistry is presented. © 2015 Wiley Periodicals, Inc.
ASTRO's 2007 Core Physics Curriculum for Radiation Oncology Residents
International Nuclear Information System (INIS)
Klein, Eric E.; Gerbi, Bruce J.; Price, Robert A.; Balter, James M.; Paliwal, Bhudatt; Hughes, Lesley; Huang, Eugene
2007-01-01
In 2004, American Society for Therapeutic Radiology and Oncology (ASTRO) published a curriculum for physics education. The document described a 54-hour course. In 2006, the committee reconvened to update the curriculum. The committee is composed of physicists and physicians from various residency program teaching institutions. Simultaneously, members have associations with American Association of Physicists in Medicine, ASTRO, Association of Residents in Radiation Oncology, American Board of Radiology, and American College of Radiology. Representatives from the latter two organizations are key to provide feedback between the examining organizations and ASTRO. Subjects are based on Accreditation Council for Graduate Medical Education requirements (particles and hyperthermia), whereas the majority of subjects and appropriated hours/subject were developed by consensus. The new curriculum is 55 hours, containing new subjects, redistribution of subjects with updates, and reorganization of core topics. For each subject, learning objectives are provided, and for each lecture hour, a detailed outline of material to be covered is provided. Some changes include a decrease in basic radiologic physics, addition of informatics as a subject, increase in intensity-modulated radiotherapy, and migration of some brachytherapy hours to radiopharmaceuticals. The new curriculum was approved by the ASTRO board in late 2006. It is hoped that physicists will adopt the curriculum for structuring their didactic teaching program, and simultaneously, American Board of Radiology, for its written examination. American College of Radiology uses the ASTRO curriculum for their training examination topics. In addition to the curriculum, the committee added suggested references, a glossary, and a condensed version of lectures for a Postgraduate Year 2 resident physics orientation. To ensure continued commitment to a current and relevant curriculum, subject matter will be updated again in 2 years
Gravitational Waves from Oscillons with Cuspy Potentials.
Liu, Jing; Guo, Zong-Kuan; Cai, Rong-Gen; Shiu, Gary
2018-01-19
We study the production of gravitational waves during oscillations of the inflaton around the minimum of a cuspy potential after inflation. We find that a cusp in the potential can trigger copious oscillon formation, which sources a characteristic energy spectrum of gravitational waves with double peaks. The discovery of such a double-peak spectrum could test the underlying inflationary physics.
Gravitational waves from instabilities in relativistic stars
International Nuclear Information System (INIS)
Andersson, Nils
2003-01-01
This paper provides an overview of stellar instabilities as sources of gravitational waves. The aim is to put recent work on secular and dynamical instabilities in compact stars in context, and to summarize the current thinking about the detectability of gravitational waves from various scenarios. As a new generation of kilometre length interferometric detectors is now coming online this is a highly topical theme. The review is motivated by two key questions for future gravitational-wave astronomy: are the gravitational waves from various instabilities detectable? If so, what can these gravitational-wave signals teach us about neutron star physics? Even though we may not have clear answers to these questions, recent studies of the dynamical bar-mode instability and the secular r-mode instability have provided new insights into many of the difficult issues involved in modelling unstable stars as gravitational-wave sources. (topical review)
Post-Newtonian gravitational bremsstrahlung
International Nuclear Information System (INIS)
Turner, M.; Will, C.M.
1978-01-01
We present formulae and numerical results for the gravitational radiation emitted during a low-deflection encounter between two massive bodies (''gravitational bremsstrahlung''). Our results are valid through post-Newtonian order within general relativity. We discuss in detail the gravitational waveform (transverse-traceless part of the metric perturbation tensor), the toal luminosity and total emitted energy, the angular distribution of emitted energy (antenna pattern), and the frequency spectrum. We also present a method of ''boosting'' the accuracy of these quantities to post-3/2-Newtonian order. A numerical comparison of our results with those of Peters and of Kovacs and Thorne shows that the post-Newtonian method is reliable to better than 0.1% at v=0.1c, to a few percent at v=0.35c, and to 10--20% at v=0.5c. We also compare our results with those of Smarr
International Nuclear Information System (INIS)
Narayana, K.L.
1986-01-01
Supergravity theories indicate drastic modifications and entirely new thoughts of approach for study of the physical processes. In a separate paper, the author has emphasized the importance of SU(8) symmetric group within the frame work of a U(10,2) supergravity theory. This has also been cited in literature, subsequently, for a spinorial theoretic formulation of light and classification of photon and W-meson multiplets. The object of the present paper is to present an example of a specific gauge-gravity theory that employs SL(2,C) infinitesional group together with a SU(2) group. The reason of the choice is its close analogy with the Einstein's theory, that leads to automatically the important physical quantities. The difference, however, arises in a relevant version of quantized theory. At first, he emphasizes the basic structure of the model, discusses the symmetry breaking patterns which ensures ISL(2,C) X SU(2) as the low energy symmetry. He next points out the new interactions present in the extended framework and obtain the reasonable physical processes that may play an important role in the super gravity cosmic entities
W, F, and I : Three quantities basic to radiation physics
International Nuclear Information System (INIS)
Inokuti, M.
1998-01-01
The W value is an index of the mean number of ions produced in a gas subjected to ionizing radiation. Formally, it is defined as the radiation energy absorbed (usually expressed in units of eV) ''per ion pair of either sign produced'', or, in a simpler language, ''per electron liberated''. The basic knowledge up to 1961 is eloquently articulated in a classic essay by Platzman [1], which Professor Doke loves to cite. The theme of Platzman was to explain from the point of view of basic physics the magnitude and characteristics of the ratio W/I, where I is the (first) ionization threshold energy. In summary, major characteristics are as follows. (1) The W value for a given gas depends weakly on the properties of the radiation such as the mass and charge of particles or initial energies (provided they are sufficiently high). This makes the ionization measurement useful as a method of dosimetry, viz., the determination of the absorbed energy. (2) The ratio W/I is always greater than unity because a part of the absorbed energy must be used in nonionizing events such as discrete excitation or molecular dissociation into neutral fragments and also in producing subexcitation electrons, viz., electrons with kinetic energies too low to cause electronic excitation or ionization [2]. (3) The ratio W/I is 1.7-1.8 for rare gases, and 2.1-2.6 for gases of common molecules (depending on the electronic structure, going from ''hard'' to ''soft''). Calculation of the W value is possible from three approaches: (i) the energy balance of Platzman, heuristic for general understanding and appropriate for an estimate; (ii) the Fowler equation [3] for the direct evaluation of the mean number of ions produced; and (iii) the method of Spencer and Fano [4] through the degradation spectra (or the track length distributions) of charged particles, most importantly of electrons, present in the medium. The Fowler method is good for obtaining the mean number of ions or excited states resulting from
Glycolic Acid Physical Properties, Impurities, And Radiation Effects Assessment
International Nuclear Information System (INIS)
Pickenheim, B.; Bibler, N.
2010-01-01
The DWPF is pursuing alternative reductants/flowsheets to increase attainment to meet closure commitment dates. In fiscal year 2009, SRNL evaluated several options and recommended the further assessment of the nitric/formic/glycolic acid flowsheet. SRNL is currently performing testing with this flowsheet to support the DWPF down-select of alternate reductants. As part of the evaluation, SRNL was requested to determine the physical properties of formic and glycolic acid blends. Blends of formic acid in glycolic acid were prepared and their physical properties tested. Increasing amounts of glycolic acid led to increases in blend density, viscosity and surface tension as compared to the 90 wt% formic acid that is currently used at DWPF. These increases are small, however, and are not expected to present any difficulties in terms of processing. The effect of sulfur impurities in technical grade glycolic acid was studied for its impact on DWPF glass quality. While the glycolic acid specification allows for more sulfate than the current formic acid specification, the ultimate impact is expected to be on the order of 0.03 wt% sulfur in glass. Note that lower sulfur content glycolic acid could likely be procured at some increased cost if deemed necessary. A paper study on the effects of radiation on glycolic acid was performed. The analysis indicates that substitution of glycolic acid for formic acid would not increase the radiolytic production rate of H 2 and cause an adverse effect in the SRAT or SME process. It has been cited that glycolic acid solutions that are depleted of O 2 when subjected to large radiation doses produced considerable quantities of a non-diffusive polymeric material. Considering a constant air purge is maintained in the SRAT and the solution is continuously mixed, oxygen depletion seems unlikely, however, if this polymer is formed in the SRAT solution, the rheology of the solution may be affected and pumping of the solution may be hindered. A
Gravitational waves from supernova matter
International Nuclear Information System (INIS)
Scheidegger, S; Whitehouse, S C; Kaeppeli, R; Liebendoerfer, M
2010-01-01
We have performed a set of 11 three-dimensional magnetohydrodynamical (MHD) core-collapse supernova simulations in order to investigate the dependences of the gravitational wave signal on the progenitor's initial conditions. We study the effects of the initial central angular velocity and different variants of neutrino transport. Our models are started up from a 15M o-dot progenitor and incorporate an effective general relativistic gravitational potential and a finite temperature nuclear equation of state. Furthermore, the electron flavour neutrino transport is tracked by efficient algorithms for the radiative transfer of massless fermions. We find that non- and slowly rotating models show gravitational wave emission due to prompt- and lepton driven convection that reveals details about the hydrodynamical state of the fluid inside the protoneutron stars. Furthermore we show that protoneutron stars can become dynamically unstable to rotational instabilities at T/|W| values as low as ∼2% at core bounce. We point out that the inclusion of deleptonization during the postbounce phase is very important for the quantitative gravitational wave (GW) prediction, as it enhances the absolute values of the gravitational wave trains up to a factor of ten with respect to a lepton-conserving treatment.
Relic gravitational waves and cosmology
International Nuclear Information System (INIS)
Grishchuk, Leonid P
2005-01-01
The paper begins with a brief recollection of interactions of the author with Ya B Zeldovich in the context of the study of relic gravitational waves. The principles and early results on the quantum-mechanical generation of cosmological perturbations are then summarized. The expected amplitudes of relic gravitational waves differ in various frequency windows, and therefore the techniques and prospects of their detection are distinct. One section of the paper describes the present state of efforts in direct detection of relic gravitational waves. Another section is devoted to indirect detection via the anisotropy and polarization measurements of the cosmic microwave background (CMB) radiation. It is emphasized throughout the paper that the inference about the existence and expected amount of relic gravitational waves is based on a solid theoretical foundation and the best available cosmological observations. It is also explained in great detail what went wrong with the so-called 'inflationary gravitational waves', whose amount is predicted by inflationary theorists to be negligibly small, thus depriving them of any observational significance. (reviews of topical problems)
International Nuclear Information System (INIS)
Balakin, A.B.; Murzakhanov, Z.G.; Grunskaya, L.V.
1994-01-01
A proposal on the experimental detection of extremely low-frequency variations of the electromagnetic Earth field at the gravitational-wave frequency and method for correlation processing results of the experiments are described. 14 refs
Modular Gravitational Reference Sensor (MGRS) For Astrophysics and Astronomy
Sun, Ke-Xun; Buchman, S.; Byer, R. L.; DeBra, D.; Goebel, J.; Allen, G.; Conklin, J.; Gerardi, D.; Higuchi, S.; Leindecker, N.; Lu, P.; Swank, A.; Torres, E.; Trillter, M.; Zoellner, A.
2009-01-01
The study of space-time for gravitational wave detection and cosmology beyond Einstein will be an important theme for astrophysics and astronomy in decades to come. Laser Interferometric Space Antenna (LISA) is designed for detecting gravitational wave in space. The Modular Gravitational Reference Sensor (MGRS) is developed as the next generation core instrument for space-time research, including gravitational wave detection beyond LISA, and an array of precision experiments in space. The MGRS provide a stable gravitational cardinal point in space-time by using a test sphere, which eliminates the need for orientation control, minimizing disturbances. The MGRS measures the space-time variation via a two step process: measurement between test mass and housing, and between housings of two spacecraft. Our Stanford group is conducting systematic research and development on the MGRS. Our initial objectives are to gain a system perspective of the MGRS, to develop component technologies, and to establish test platforms. We will review our recent progress in system technologies, optical displacement and angle sensing, diffractive optics, proof mass characterization, UV LED charge management system and space qualification, thermal control and sensor development. Some highlights of our recent results are: Demonstration of the extreme radiation hardness of UV LED which sustained 2 trillion protons per square centimeter; measurement of mass center offset down to 300 nm, and measurement of small angle 0.2 nrad per root hertz using a compact grating angular sensor. The Stanford MGRS program has made exceptional contribution to education of next generation scientists and engineers. We have undergraduate and graduate students in aeronautical and astronautic engineering, applied physics, cybernetics, electrical engineering, mechanical engineering, and physics. We have also housed a number of high school students in our labs for education and public outreach.
Physics of radiation therapy of head and neck tumors
International Nuclear Information System (INIS)
Almond, P.R.
1987-01-01
Radiotherapy treatment of head and neck cancers probably requires more individual planning than for any other cancer site because of the large number of variables that exist. The fact that tumors may be superficial or relatively deep-seated, the complex shape of the head and neck region, the presence of significant inhomogeneities such as bone and air spaces, and the need to spare critical structures such as the eyes or central nervous system all add to the need for careful considerations of the physical parameters involved in radiotherapy. In addition, the high mobility of the head allows it to assume a wide variety of positions so that techniques have had to be developed for careful simulation, repositioning, and immobilization during treatment. In the head and neck region shaping of the beam becomes important, and therefore, blocked fields, compensators, or wedges are often used. Although the specific radiotherapy techniques for each site of head and neck cancer are described in the various chapters of this book, a general description of the various types of radiation beams, radioactive sources, beam modifiers, treatment planning techniques, and treatment implementation is given in this chapter. The discussion is divided into three main categories: (1) external beam, (2) brachytherapy, and (3) simulation and immobilization
Electromagnetic radiation due to spacetime oscillations
International Nuclear Information System (INIS)
Chitre, D.M.; Price, R.H.; Sandberg, V.D.
1975-01-01
Wave equations are derived in the Newman-Penrose formalism for mixed electromagnetic and gravitational perturbations on both a flat spacetime background and a slightly charged (Q 2 very-much-less-than GM 2 ) Reissner-Nordstroem background. The physical meaning of these equations is discussed and analytical results are derived for nonrelativistic sources and for ultrarelativistic particle motions. The relationship between even-parity (TM) electromagnetic radiation multipoles in the long-wavelength approximation and static multipoles is shown to be the same as for classical radiation, suggesting a simple picture for electromagnetic radiation induced by gravitational perturbations
Gravitational Wave Experiments - Proceedings of the First Edoardo Amaldi Conference
Coccia, E.; Pizzella, G.; Ronga, F.
1995-07-01
The Table of Contents for the full book PDF is as follows: * Foreword * Notes on Edoardo Amaldi's Life and Activity * PART I. INVITED LECTURES * Sources and Telescopes * Sources of Gravitational Radiation for Detectors of the 21st Century * Neutrino Telescopes * γ-Ray Bursts * Space Detectors * LISA — Laser Interferometer Space Antenna for Gravitational Wave Measurements * Search for Massive Coalescing Binaries with the Spacecraft ULYSSES * Interferometers * The LIGO Project: Progress and Prospects * The VIRGO Experiment: Status of the Art * GEO 600 — A 600-m Laser Interferometric Gravitational Wave Antenna * 300-m Laser Interferometer Gravitational Wave Detector (TAMA300) in Japan * Resonant Detectors * Search for Continuous Gravitational Wave from Pulsars with Resonant Detector * Operation of the ALLEGRO Detector at LSU * Preliminary Results of the New Run of Measurements with the Resonant Antenna EXPLORER * Operation of the Perth Cryogenic Resonant-Bar Gravitational Wave Detector * The NAUTILUS Experiment * Status of the AURIGA Gravitational Wave Antenna and Perspectives for the Gravitational Waves Search with Ultracryogenic Resonant Detectors * Ultralow Temperature Resonant-Mass Gravitational Radiation Detectors: Current Status of the Stanford Program * Electromechanical Transducers and Bandwidth of Resonant-Mass Gravitational-Wave Detectors * Fully Numerical Data Analysis for Resonant Gravitational Wave Detectors: Optimal Filter and Available Information * PART II. CONTRIBUTED PAPERS * Sources and Telescopes * The Local Supernova Production * Periodic Gravitational Signals from Galactic Pulsars * On a Possibility of Scalar Gravitational Wave Detection from the Binary Pulsars PSR 1913+16 * Kazan Gravitational Wave Detector “Dulkyn”: General Concept and Prospects of Construction * Hierarchical Approach to the Theory of Detection of Periodic Gravitational Radiation * Application of Gravitational Antennae for Fundamental Geophysical Problems * On
Feynman Lectures on Gravitation
International Nuclear Information System (INIS)
Borcherds, P
2003-01-01
In the early 1960s Feynman lectured to physics undergraduates and, with the assistance of his colleagues Leighton and Sands, produced the three-volume classic Feynman Lectures in Physics. These lectures were delivered in the mornings. In the afternoons Feynman was giving postgraduate lectures on gravitation. This book is based on notes compiled by two students on that course: Morinigo and Wagner. Their notes were checked and approved by Feynman and were available at Caltech. They have now been edited by Brian Hatfield and made more widely available. The book has a substantial preface by John Preskill and Kip Thorne, and an introduction entitled 'Quantum Gravity' by Brian Hatfield. You should read these before going on to the lectures themselves. Preskill and Thorne identify three categories of potential readers of this book. 1. Those with a postgraduate training in theoretical physics. 2. 'Readers with a solid undergraduate training in physics'. 3. 'Admirers of Feynman who do not have a strong physics background'. The title of the book is perhaps misleading: readers in category 2 who think that this book is an extension of the Feynman Lectures in Physics may be disappointed. It is not: it is a book aimed mainly at those in category 1. If you want to get to grips with gravitation (and general relativity) then you need to read an introductory text first e.g. General Relativity by I R Kenyon (Oxford: Oxford University Press) or A Unified Grand Tour of Theoretical Physics by Ian D Lawrie (Bristol: IoP). But there is no Royal Road. As pointed out in the preface and in the introduction, the book represents Feynman's thinking about gravitation some 40 years ago: the lecture course was part of his attempts to understand the subject himself, and for readers in all three categories it is this that makes the book one of interest: the opportunity to observe how a great physicist attempts to tackle some of the hardest challenges of physics. However, the book was written 40
Sensitivity of a combined gravitational antenna
International Nuclear Information System (INIS)
Kulagin, V.V.; Rudenko, V.N.
1986-01-01
A modification of a combined optico-acoustic gravitational antenna: a long-base laser interferometer, where free masses are changed by Weber resonators, is suggested. The combined gravitational antenna can possess sensitivity h min ∼ 10 -18 without deep cooling of Weber resonators and h min ∼ 10 -19 at helium temperaure of the resonators. This antenna has the following new quantities: presence of three independent responses, that permits to a considerable extent to exclude non-gravitational effects; presence of responses of two separated Weber resonators, that permits to register the wave character of gravitational perturbation by measuring phase shift between relaxation ''tails''. It means that one may with certainty register the wave structure of gravitational radiation for perturbation of metrics h, exceeding the threshold sensitivity of the known detectors by an order
The confrontation between gravitation theory and experiment
International Nuclear Information System (INIS)
Will, C.M.
1979-01-01
After an introductory section, an analysis is given of the foundations of gravitation theory - principles of equivalence, the fundamental criteria for the viability of a gravitational theory, and the experiments that support those criteria. One of the principal conclusions is that the correct, viable theory of gravity must in all probability be a 'metric' theory. Attention is focussed on solar-system tests, using a 'theory of theories' known as the parametrized post-Newtonian formalism that encompasses most metric theories of gravity and that is ideally suited to the solar-system arena. Gravitational radiation is discussed as a possible tool for testing gravitational theory. The binary pulsar, a new , 'stellar-system' testing ground is studied. Tests of gravitation theory in a cosmic arena are described. (U.K.)
Gravitational waves and electrodynamics: new perspectives.
Cabral, Francisco; Lobo, Francisco S N
2017-01-01
Given the recent direct measurement of gravitational waves (GWs) by the LIGO-VIRGO collaboration, the coupling between electromagnetic fields and gravity have a special relevance since it opens new perspectives for future GW detectors and also potentially provides information on the physics of highly energetic GW sources. We explore such couplings using the field equations of electrodynamics on (pseudo) Riemann manifolds and apply it to the background of a GW, seen as a linear perturbation of Minkowski geometry. Electric and magnetic oscillations are induced that propagate as electromagnetic waves and contain information as regards the GW which generates them. The most relevant results are the presence of longitudinal modes and dynamical polarization patterns of electromagnetic radiation induced by GWs. These effects might be amplified using appropriate resonators, effectively improving the signal to noise ratio around a specific frequency. We also briefly address the generation of charge density fluctuations induced by GWs and the implications for astrophysics.
Gravitational waves and electrodynamics: new perspectives
Energy Technology Data Exchange (ETDEWEB)
Cabral, Francisco; Lobo, Francisco S.N. [Faculdade de Ciencias da Universidade de Lisboa, Instituto de Astrofisica e Ciencias do Espaco, Lisbon (Portugal)
2017-04-15
Given the recent direct measurement of gravitational waves (GWs) by the LIGO-VIRGO collaboration, the coupling between electromagnetic fields and gravity have a special relevance since it opens new perspectives for future GW detectors and also potentially provides information on the physics of highly energetic GW sources. We explore such couplings using the field equations of electrodynamics on (pseudo) Riemann manifolds and apply it to the background of a GW, seen as a linear perturbation of Minkowski geometry. Electric and magnetic oscillations are induced that propagate as electromagnetic waves and contain information as regards the GW which generates them. The most relevant results are the presence of longitudinal modes and dynamical polarization patterns of electromagnetic radiation induced by GWs. These effects might be amplified using appropriate resonators, effectively improving the signal to noise ratio around a specific frequency. We also briefly address the generation of charge density fluctuations induced by GWs and the implications for astrophysics. (orig.)
Advanced interferometric gravitational-wave detectors
Saulson, Peter R
2019-01-01
Gravitational waves are one of the most exciting and promising emerging areas of physics and astrophysics today. The detection of gravitational waves will rank among the most significant physics discoveries of the 21st century.Advanced Interferometric Gravitational-Wave Detectors brings together many of the world's top experts to deliver an authoritative and in-depth treatment on current and future detectors. Volume I is devoted to the essentials of gravitational-wave detectors, presenting the physical principles behind large-scale precision interferometry, the physics of the underlying noise sources that limit interferometer sensitivity, and an explanation of the key enabling technologies that are used in the detectors. Volume II provides an in-depth look at the Advanced LIGO and Advanced Virgo interferometers that have just finished construction, as well as examining future interferometric detector concepts. This two-volume set will provide students and researchers the comprehensive background needed to und...
Theorem on axially symmetric gravitational vacuum configurations
Energy Technology Data Exchange (ETDEWEB)
Papadopoulos, A; Le Denmat, G [Paris-6 Univ., 75 (France). Inst. Henri Poincare
1977-01-24
A theorem is proved which asserts the non-existence of axially symmetric gravitational vacuum configurations with non-stationary rotation only. The eventual consequences in black-hole physics are suggested.
Compendium to radiation physics for medical physicists 300 problems and solutions
Podgorsak, Ervin B
2014-01-01
This exercise book contains 300 typical problems and exercises in modern physics and radiation physics with complete solutions, detailed equations and graphs. This textbook is linked directly with the textbook "Radiation Physics for Medical Physicists", Springer (2010) but can also be used in combination with other related textbooks. For ease of use, this textbook has exactly the same organizational layout (14 chapters, 128 sections) as the "Radiation Physics for Medical Physicists" textbook and each section is covered by at least one problem with solution given. Equations, figures and tables are cross-referenced between the two books. It is the only large compilation of textbook material and associated solved problems in medical physics, radiation physics, and biophysics.
175th International School of Physics "Enrico Fermi" : Radiation and Particle Detectors
Bottigli, U; Oliva, P
2010-01-01
High energy physics (HEP) has a crucial role in the context of fundamental physics. HEP experiments make use of a massive array of sophisticated detectors to analyze the particles produced in high-energy scattering events. This book contains the papers from the workshop 'Radiation and Particle Detectors', organized by the International School of Physics, and held in Varenna in July 2009. Its subject is the use of detectors for research in fundamental physics, astro-particle physics and applied physics. Subjects covered include the measurement of: the position and length of ionization trails, time of flight velocity, radius of curvature after bending the paths of charged particles with magnetic fields, coherent transition radiation, synchrotron radiation, electro-magnetic showers produced by calorimetric methods and nuclear cascades produced by hadrons in massive steel detectors using calorimetry. Detecting muons and the detection of Cherenkov radiation are also covered, as is the detection of neutrinos by ste...
Atomic and gravitational clocks
International Nuclear Information System (INIS)
Canuto, V.M.; City Coll., New York; Goldman, I.
1982-01-01
Atomic and gravitational clocks are governed by the laws of electrodynamics and gravity respectively. While the strong equivalence principle (SEP) assumes that the two clocks have been synchronous at all times, recent planetary data seem to suggest a possible violation of the SEP. Past analysis of the implications of an SEP violation on different physical phenomena revealed no disagreement. However, these studies assumed that the two different clocks can be consistently constructed within the framework. The concept of scale invariance, and the physical meaning of different systems of units, are now reviewed and the construction of two clocks that do not remain synchronous-whose rates are related by a non-constant function βsub(a)-is demonstrated. The cosmological character of βsub(a) is also discussed. (author)
Directory of Open Access Journals (Sweden)
D. Bachmann
2004-01-01
Full Text Available Using a new 3-D physical modelling technique we investigated the initiation and evolution of large scale landslides in presence of pre-existing large scale fractures and taking into account the slope material weakening due to the alteration/weathering. The modelling technique is based on the specially developed properly scaled analogue materials, as well as on the original vertical accelerator device enabling increases in the 'gravity acceleration' up to a factor 50. The weathering primarily affects the uppermost layers through the water circulation. We simulated the effect of this process by making models of two parts. The shallower one represents the zone subject to homogeneous weathering and is made of low strength material of compressive strength σl. The deeper (core part of the model is stronger and simulates intact rocks. Deformation of such a model subjected to the gravity force occurred only in its upper (low strength layer. In another set of experiments, low strength (σw narrow planar zones sub-parallel to the slope surface (σwl were introduced into the model's superficial low strength layer to simulate localized highly weathered zones. In this configuration landslides were initiated much easier (at lower 'gravity force', were shallower and had smaller horizontal size largely defined by the weak zone size. Pre-existing fractures were introduced into the model by cutting it along a given plan. They have proved to be of small influence on the slope stability, except when they were associated to highly weathered zones. In this latter case the fractures laterally limited the slides. Deep seated rockslides initiation is thus directly defined by the mechanical structure of the hillslope's uppermost levels and especially by the presence of the weak zones due to the weathering. The large scale fractures play a more passive role and can only influence the shape and the volume of the sliding units.
Gravitational wave generation by stellar core collapse
International Nuclear Information System (INIS)
Moore, T.A.
1981-01-01
Stars which have masses greater than 5 to 8 solar masses are thought to undergo a stage of catastrophic core collapse and subsequent supernova explosion at the end of their lives. If the core is not spherically symmetric, the bounce which halts its collapse at transnuclear densities will generate a pulse of gravitational waves. This thesis presents a fully relativistic model of core collapse which treats deviations from spherical symmetry as small perturbations on a spherical background. This model may be used to predict qualitative and quantitative features of the gravitational radiation emitted by stellar cores with odd-parity, axisymmetric fluid perturbations, and represents a first step in the application of perturbative methods to more general asymmetries. The first chapter reviews the present consensus on the physics of core collapse and outlines the important features, assumptions, and limitations of the model. A series of model runs are presented and discussed. Finally, several proposals for future research are presented. Subsequent chapters explore in detail the mathematical features of the present model and its realization on the computer
Nonlinear coupled Alfven and gravitational waves
International Nuclear Information System (INIS)
Kaellberg, Andreas; Brodin, Gert; Bradley, Michael
2004-01-01
In this paper we consider nonlinear interaction between gravitational and electromagnetic waves in a strongly magnetized plasma. More specifically, we investigate the propagation of gravitational waves with the direction of propagation perpendicular to a background magnetic field and the coupling to compressional Alfven waves. The gravitational waves are considered in the high-frequency limit and the plasma is modeled by a multifluid description. We make a self-consistent, weakly nonlinear analysis of the Einstein-Maxwell system and derive a wave equation for the coupled gravitational and electromagnetic wave modes. A WKB-approximation is then applied and as a result we obtain the nonlinear Schroedinger equation for the slowly varying wave amplitudes. The analysis is extended to 3D wave pulses, and we discuss the applications to radiation generated from pulsar binary mergers. It turns out that the electromagnetic radiation from a binary merger should experience a focusing effect, that in principle could be detected
Gravitational waves from freely precessing neutron stars
International Nuclear Information System (INIS)
Jones, D.I.
2001-01-01
The purpose of this study is to assess the likely detectability of gravitational waves from freely precessing neutron stars. We begin by presenting a neutron star model of sufficient complexity to take into account both the elasticity and fluidity of a realistic neutron star. We then examine the effect of internal dissipation (i.e. heat generation within the star) and gravitational radiation reaction on the wobble. This is followed by an examination of various astrophysical scenarios where some mechanism might pump the precessional motion. We estimate the gravitational wave amplitude in these situations. Finally, we conclude that gravitational radiation from freely precessing neutron stars is almost certainly limited to a level undetectable by a LIGO II detector by internal dissipation. (author)
Physical and biomedical countermeasures for space radiation risk
International Nuclear Information System (INIS)
Durante, Marco
2008-01-01
Radiation exposure represents a serious hindrance for long-term interplanetary missions because of the high uncertainty on risk coefficients, and to the lack of simple countermeasures. Even if uncertainties in risk assessment will he reduced in the next few years, there is little doubt that appropriate countermeasures have to be taken to reduce the exposure or the biological damage produced by cosmic radiation. In addition, it is necessary to provide effective countermeasures against solar particle events, which can produce acute effects, even life threatening, for inadequately protected crews. Strategies that may prove to he effective in reducing exposure, or the effects of the irradiation, include shielding, administration of drugs or dietary supplements to reduce the radiation effects, crew selection based on a screening of individual radiation sensitivity. It is foreseeable that research in passive and active radiation shielding, radioprotective chemicals, and individual susceptibility will boost in the next years to provide efficient countermeasures to the space radiation threat. (orig.)
Topics in radiation at accelerators: Radiation physics for personnel and environmental protection
International Nuclear Information System (INIS)
Cossairt, J.D.
1993-11-01
This report discusses the following topics: Composition of Accelerator Radiation Fields; Shielding of Electrons and Photons at Accelerators; Shielding of Hadrons at Accelerators; Low Energy Prompt Radiation Phenomena; Induced Radioactivity at Accelerators; Topics in Radiation Protection Instrumentation at Accelerators; and Accelerator Radiation Protection Program Elements
Cylindrical collapse and gravitational waves
Energy Technology Data Exchange (ETDEWEB)
Herrera, L [Escuela de FIsica, Faculdad de Ciencias, Universidad Central de Venezuela, Caracas, Venezuela (Venezuela); Santos, N O [Universite Pierre et Marie Curie, CNRS/FRE 2460 LERMA/ERGA, Tour 22-12, 4eme etage, BoIte 142, 4 place Jussieu, 75252 Paris Cedex 05 (France); Laboratorio Nacional de Computacao Cientifica, 25651-070 Petropolis RJ (Brazil); Centro Brasileiro de Pesquisas Fisicas, 22290-180 Rio de Janeiro RJ (Brazil)
2005-06-21
We study the matching conditions for a collapsing anisotropic cylindrical perfect fluid, and we show that its radial pressure is non-zero on the surface of the cylinder and proportional to the time-dependent part of the field produced by the collapsing fluid. This result resembles the one that arises for the radiation-though non-gravitational-in the spherically symmetric collapsing dissipative fluid, in the diffusion approximation.
Physical determinants of radiation sensitivity in bacterial spores
International Nuclear Information System (INIS)
Powers, E.L.
1982-01-01
Several factors modifying radiation sensitivity in dry bacterial spores are described and discussed. Vacuum inducing the loss of critical structural water, very low dose rates of radiation from which the cell may recover, radiations of high linear energy transfer, and the action of temperature over long periods of time on previously irradiated cells are recognized from extensive laboratory work as important in determining survival of spores exposed to low radiation doses at low temperatures for long periods of time. Some extensions of laboratory work are proposed
Physics fundamentals and biological effects of synchrotron radiation therapy
International Nuclear Information System (INIS)
Prezado, Y.
2010-01-01
The main goal of radiation therapy is to deposit a curative dose in the tumor without exceeding the tolerances in the nearby healthy tissues. For some radioresistant tumors, like gliomas, requiring high doses for complete sterilization, the major obstacle for curative treatment with ionizing radiation remains the limited tolerance of the surrounding healthy tissue. This limitation is particularly severe for brain tumors and, especially important in children, due to the high risk of complications in the development of the central nervous system. In addition, the treatment of tumors close to an organ at risk, like the spinal cord, is also restricted. One possible solution is the development of new radiation therapy techniques exploiting radically different irradiation modes and modifying, in this way, the biological equivalent doses. This is the case of synchrotron radiation therapy (SRT). In this work the three new radiation therapy techniques under development at the European Synchrotron Radiation Facility (ESRF), in Grenoble (France) will be described, namely: synchrotron stereotactic radiation therapy (SSRT), microbeam radiation therapy (MRT) and minibeam radiation therapy. The promising results in the treatment of the high grade brain tumors obtained in preclinical studies have paved the way to the clinical trials. The first patients are expected in the fall of 2010. (Author).
Gravitational instability in isotropic MHD plasma waves
Cherkos, Alemayehu Mengesha
2018-04-01
The effect of compressive viscosity, thermal conductivity and radiative heat-loss functions on the gravitational instability of infinitely extended homogeneous MHD plasma has been investigated. By taking in account these parameters we developed the six-order dispersion relation for magnetohydrodynamic (MHD) waves propagating in a homogeneous and isotropic plasma. The general dispersion relation has been developed from set of linearized basic equations and solved analytically to analyse the conditions of instability and instability of self-gravitating plasma embedded in a constant magnetic field. Our result shows that the presence of viscosity and thermal conductivity in a strong magnetic field substantially modifies the fundamental Jeans criterion of gravitational instability.
Quantum field theory in gravitational background
International Nuclear Information System (INIS)
Narnhofer, H.
1986-01-01
The author suggests ignoring the influence of the quantum field on the gravitation as the first step to combine quantum field theory and gravitation theory, but to consider the gravitational field as fixed and thus study quantum field theory on a manifold. This subject evoked interest when thermal radiation of a black hole was predicted. The author concentrates on the free quantum field and can split the problem into two steps: the Weyl-algebra of the free field and the Wightman functional on the tangent space
An electric field in a gravitational field
International Nuclear Information System (INIS)
Harpaz, Amos
2005-01-01
The behaviour of an electric field in a gravitational field is analysed. It is found that due to the mass (energy) of the electric field, it is subjected to gravity and it falls in the gravitational field. This fall curves the electric field, a stress force (a reaction force) is created, and the interaction of this reaction force with the static charge gives rise to the creation of radiation
Prevention of gravitational collapse
International Nuclear Information System (INIS)
Moffat, J.W.; Taylor, J.G.
1981-01-01
We apply a new theory of gravitation to the question of gravitational collapse to show that collapse is prevented in this theory under very reasonable conditions. This result also extends to prevent ultimate collapse of the Universe. (orig.)
Underdevelopment’s gravitation
Directory of Open Access Journals (Sweden)
Marin Dinu
2013-09-01
Full Text Available The energy necessary to escape the gravitational pull of underdevelopment and to enter an evolutional trajectory dependent on the gravitational pull of development is unintelligible in economic terms.
Radiative corrections and Monte Carlo generators for physics at flavor factories
Directory of Open Access Journals (Sweden)
Montagna Guido
2016-01-01
Full Text Available I review the state of the art of precision calculations and related Monte Carlo generators used in physics at flavor factories. The review describes the tools relevant for the measurement of the hadron production cross section (via radiative return, energy scan and in γγ scattering, luminosity monitoring, searches for new physics and physics of the τ lepton.
The teaching of physics and related courses to residents in radiation oncology
International Nuclear Information System (INIS)
Dunscombe, P.
1989-01-01
A survey of physics and related teaching to radiation oncology residents in 21 Canadian cancer centres was undertaken in December 1987 and January 1988. This survey illustrates a very considerable variation in the formal teaching of physics to aspiring radiation oncologists with, for example, the number of hours offered ranging from 40 to 160 in those 10 centres that have a training program. It would appear to be of benefit to radiation oncology residents, those charged with teaching them, and the radiation oncology community as a whole, to develop specific guidelines for this aspect of resident education. (8 refs., tab.)
Black-Hole Binaries, Gravitational Waves, and Numerical Relativity
Kelly, Bernard J.; Centrella, Joan; Baker, John G.; Kelly, Bernard J.; vanMeter, James R.
2010-01-01
Understanding the predictions of general relativity for the dynamical interactions of two black holes has been a long-standing unsolved problem in theoretical physics. Black-hole mergers are monumental astrophysical events ' releasing tremendous amounts of energy in the form of gravitational radiation ' and are key sources for both ground- and spacebased gravitational wave detectors. The black-hole merger dynamics and the resulting gravitational waveforms can only he calculated through numerical simulations of Einstein's equations of general relativity. For many years, numerical relativists attempting to model these mergers encountered a host of problems, causing their codes to crash after just a fraction of a binary orbit cnuld be simulated. Recently ' however, a series of dramatic advances in numerical relativity has ' for the first time, allowed stable / robust black hole merger simulations. We chronicle this remarkable progress in the rapidly maturing field of numerical relativity, and the new understanding of black-hole binary dynamics that is emerging. We also discuss important applications of these fundamental physics results to astrophysics, to gravitationalwave astronomy, and in other areas.
New physical model calculates airline crews' radiation exposure
Schultz, Colin
2013-12-01
Airline pilots and crews, who spend hundreds of hours each year flying at high altitude, are exposed to increased doses of radiation from galactic cosmic rays and solar energy particles, enough that airline crew members are actually considered radiation workers by the International Commission on Radiological Protection.
Gravitational waves from neutron stars and asteroseismology
Ho, Wynn C. G.
2018-05-01
Neutron stars are born in the supernova explosion of massive stars. Neutron stars rotate as stably as atomic clocks and possess densities exceeding that of atomic nuclei and magnetic fields millions to billions of times stronger than those created in laboratories on the Earth. The physical properties of neutron stars are determined by many areas of fundamental physics, and detection of gravitational waves can provide invaluable insights into our understanding of these areas. Here, we describe some of the physics and astrophysics of neutron stars and how traditional electromagnetic wave observations provide clues to the sorts of gravitational waves we expect from these stars. We pay particular attention to neutron star fluid oscillations, examining their impact on electromagnetic and gravitational wave observations when these stars are in a wide binary or isolated system, then during binary inspiral right before merger, and finally at times soon after merger. This article is part of a discussion meeting issue `The promises of gravitational-wave astronomy'.
Ridgely, Charles T.
2011-01-01
When two gravitating bodies reside in a material medium, Newton's law of universal gravitation must be modified to account for the presence of the medium. A modified expression of Newton's law is known in the literature, but lacks a clear connection with existing gravitational theory. Newton's law in the presence of a homogeneous material medium…
Relativity theory and gravitation
International Nuclear Information System (INIS)
Bondi, H.
1986-01-01
The paper on relativity theory and gravitation is presented as a preface to the first of the articles submitted to the Journal on general relativity. Newtonian gravitation and and observation, relativity, and the sources of the gravitational field, are all discussed. (UK)
International Nuclear Information System (INIS)
Milu, C.
2002-01-01
Full text: The Ministry of Health and Family from Romania has its own radiation protection network, including 23 radiation hygiene laboratories (RHLs), within the Institutes of Public Health-Bucharest, Iassy, Cluj-Napoca and Timisoara and the Directions of Public Health from Arges county, Bihor, Brasov, Mures, Maramures, Cluj, Sibiu, Harghita, Suceava, lassy, Bacau, Neamt, Galati, Constanta, Prahova, Dolj, Caras-Severin, Timis and Bucharest City. The RHLs network has 170 persons (physicians, physicists, engineers, chemists, biologists and technicians) and it is technically co-ordinated by the RHL in the Institute of Public Health-Bucharest. Within the local or national activities for physical protection of radioactive materials, the RHLs network closely co-operates with the Ministry of Internal Affairs (MAI) and with the nuclear regulatory authority, named the National Commission for Nuclear Activities Control (CNCAN). In the particular case of theft, sabotage or illicit traffic of radioactive materials, usually the MAI has the main role in the co-ordination of intervention actions of the three authorities. The RHLs network contributes by the expertise of its staff and by using its intervention facilities. The specific tasks for the RHLs network are: identification of the type and size of the radioactive material (by direct dosimetry and/or by gamma spectroscopy); dose reconstructions for the involved persons, the intervention personnel and the population; health management for overexposed persons and the medical response, including biological dosimetry and epidemiological studies. Recent special situations in this field, were: theft of some fuel (defect) tablets of natural uranium, from a production factory; the illicit traffic of radioactive materials, in transition to Western European Countries; an unauthorized decommissioning of a furnace, determining the uncontrolled dispersion of about 30 cobalt-60 sealed sources and the radiation exposure of nearly 20
Topics in Gravitation and Cosmology
Bahrami Taghanaki, Sina
This thesis is focused on two topics in which relativistic gravitational fields play an important role, namely early Universe cosmology and black hole physics. The theory of cosmic inflation has emerged as the most successful theory of the very early Universe with concrete and verifiable predictions for the properties of anisotropies of the cosmic microwave background radiation and large scale structure. Coalescences of black hole binaries have recently been detected by the Laser Interferometer Gravitational Wave Observatory (LIGO), opening a new arena for observationally testing the dynamics of gravity. In part I of this thesis we explore some modifications to the standard theory of inflation. The main predictions of single field slow-roll inflation have been largely consistent with cosmological observations. However, there remain some aspects of the theory that are not presently well understood. Among these are the somewhat interrelated issues of the choice of initial state for perturbations and the potential imprints of pre-inflationary dynamics. It is well known that a key prediction of the standard theory of inflation, namely the Gaussianity of perturbations, is a consequence of choosing a natural vacuum initial state. In chapter 3, we study the generation and detectability of non-Gaussianities in inflationary scalar perturbations that originate from more general choices of initial state. After that, in chapter 4, we study a simple but predictive model of pre-inflationary dynamics in an attempt to test the robustness of inflationary predictions. We find that significant deviations from the standard predictions are unlikely to result from models in which the inflaton field decouples from the pre-inflationary degrees of freedom prior to freeze-out of the observable modes. In part II we turn to a study of an aspect of the thermodynamics of black holes, a subject which has led to important advances in our understanding of quantum gravity. For objects which
Neutron stars, magnetic fields, and gravitational waves
International Nuclear Information System (INIS)
Lamb, F.K.
2001-01-01
The r-modes of rapidly spinning young neutron stars have recently attracted attention as a promising source of detectable gravitational radiation. These neutron stars are expected to have magnetic fields ∼ 10 12 G. The r-mode velocity perturbation causes differential motion of the fluid in the star; this is a kinematic effect. In addition, the radiation-reaction associated with emission of gravitational radiation by r-waves drives additional differential fluid motions; this is a dynamic effect. These differential fluid motions distort the magnetic fields of neutron stars and may therefore play an important role in determining the structure of neutron star magnetic fields. If the stellar field is ∼ 10 16 (Ω/Ω B ) G or stronger, the usual r-modes are no longer normal modes of the star; here Ω and Ω B are the angular velocities of the star and at which mass shedding occurs. Much weaker magnetic fields can prevent gravitational radiation from amplifying the r-modes or damp existing r-mode oscillations on a relatively short timescale by extracting energy from the modes faster than gravitational wave emission can pump energy into them. The onset of proton superconductivity in the cores of newly formed magnetic neutron stars typically increases the effect on the r-modes of the magnetic field in the core by many orders of magnitude. Once the core has become superconducting, magnetic fields of the order of 10 12 G or greater are usually sufficient to damp r-modes that have been excited by emission of gravitational radiation and to suppress any further emission. A rapid drop in the strength of r-mode gravitational radiation from young neutron stars may therefore signal the onset of superconductivity in the core and provide a lower bound on the strength of the magnetic field there. Hence, measurements of r-mode gravitational waves from newly formed neutron stars may provide valuable diagnostic information about magnetic field strengths, cooling processes, and the
Axial gravitational waves in FLRW cosmology and memory effects
Kulczycki, Wojciech; Malec, Edward
2017-09-01
We show initial data for gravitational axial waves that are twice differentiable but that are not C2. They generate wave pulses that interact with matter in the radiation cosmological era. This forces the radiation matter to rotate. This rotation is permanent—it persists after the passage of the gravitational pulse. The observed inhomogeneities of the cosmic microwave background radiation put a bound onto discontinuities of superhorizon metric perturbations. We explicitly show that a class of smooth initial metrics that are at least C2 gives rise to gravitational wave pulses that do not interact with the background during the radiation epoch.
Carbon nano tubes -Buckypaper- radiation studies for medical physics application
Energy Technology Data Exchange (ETDEWEB)
Alanazi, A.; Alkhorayef, M.; Dalton, A.; Bradley, D. A. [University of Surrey, Department of Physics, College for Nuclear and Radiation Physics, Guildford, Surrey GR2 7XH (United Kingdom); Alzimami, K. [King Saud University, Department of Radiological Sciences, P. O. Box 10219, Riyadh 11433 (Saudi Arabia); Abuhadi, N., E-mail: a.alanazi@surrey.ac.uk [Jazan University, Faculty of Medical Applied Sciences, Diagnostic Radiology Department, P. O. Box 114, Jazan (Saudi Arabia)
2015-10-15
Radiation dosimetry underpins safe and effective clinical applications of radiation. Many materials have been used to measure the radiation dose deposited in human tissue, their radiation response requiring the application of correction factors to account for various influencing factors, including sensitivity to dose and energy dependence. In regard to the latter, account needs to be taken of difference from the effective atomic number of human tissue, soft or calcified. Graphite ion chambers and semiconductor diode detectors have been used to make measurements in phantoms but these active devices represent a clear disadvantage when considered for in vivo dosimetry. In both circumstances, dosimeters with atomic number similar to human tissue are needed. Carbon nano tubes have properties that potentially meet the demand, requiring low voltage in active devices and an atomic number similar to adipose tissue. In this study, single-wall carbon nano tubes buckypaper has been used to measure the beta particle dose deposited from a strontium-90 source, the medium displaying thermoluminescence at potentially useful sensitivity. As an example, the samples show a clear response for a dose of 2 Gy. This finding suggests that carbon nano tubes can be used as a passive dosimeter specifically for the high levels of radiation exposures used in radiation therapy. Furthermore, the finding points towards further potential applications such as for space radiation measurements, not least because the medium satisfies a demand for light but strong materials of minimal capacitance. (Author)
V. Physical effects in ionizing radiation passage through matter
International Nuclear Information System (INIS)
1984-01-01
The ionization of the medium during absorption of alpha particles is described. The ranges are given of alpha particles in the air and in certain liquids and solids. The absorption of protons and deuterons takes place similarly as in alpha particles but protons and deuterons have a bigger range at the same energy. The term half-thickness has been introduced for the absorption of beta particles. For different energies of beta particles the absorption of these particles is graphically represented for different materials. The greatest attention is devoted to the absorption of electromagnetic radiation, i.e., X radiation and gamma radiation. The mechanisms are explained of absorption by photoelectric effect, the Compton effect and electron pair formation. In X radiation radiotherapy, filters are used, mostly aluminium, copper or zinc plates. The values are given of radiation intensity for different thicknesses of aluminium and copper filters and a survey is given of combined filters for 220 to 400 kV. For radiotherapy purposes great attention is devoted to the calculation of the depth dose. The effects are discussed of ionizing radiation on photographic emulsion, on changes in the colouring of some substances and fluorescence. Also given are the biological effects of ionizing radiation and the theory of direct and indirect effects is briefly described. (E.S.)
Carbon nano tubes -Buckypaper- radiation studies for medical physics application
International Nuclear Information System (INIS)
Alanazi, A.; Alkhorayef, M.; Dalton, A.; Bradley, D. A.; Alzimami, K.; Abuhadi, N.
2015-10-01
Radiation dosimetry underpins safe and effective clinical applications of radiation. Many materials have been used to measure the radiation dose deposited in human tissue, their radiation response requiring the application of correction factors to account for various influencing factors, including sensitivity to dose and energy dependence. In regard to the latter, account needs to be taken of difference from the effective atomic number of human tissue, soft or calcified. Graphite ion chambers and semiconductor diode detectors have been used to make measurements in phantoms but these active devices represent a clear disadvantage when considered for in vivo dosimetry. In both circumstances, dosimeters with atomic number similar to human tissue are needed. Carbon nano tubes have properties that potentially meet the demand, requiring low voltage in active devices and an atomic number similar to adipose tissue. In this study, single-wall carbon nano tubes buckypaper has been used to measure the beta particle dose deposited from a strontium-90 source, the medium displaying thermoluminescence at potentially useful sensitivity. As an example, the samples show a clear response for a dose of 2 Gy. This finding suggests that carbon nano tubes can be used as a passive dosimeter specifically for the high levels of radiation exposures used in radiation therapy. Furthermore, the finding points towards further potential applications such as for space radiation measurements, not least because the medium satisfies a demand for light but strong materials of minimal capacitance. (Author)
Compendium to radiation physics for medical physicists. 300 problems and solutions
International Nuclear Information System (INIS)
Podgorsak, Ervin B.
2014-01-01
Can be used in combination with other textbooks. Exercise book for graduate and undergraduate students of medical physics and engineering. Well chosen and didactically presented problems. Perfect set for learning in connection with the textbook by Podgorsak and others. Detailed derivation of results with many detailed illustrations. Fully worked-out solutions to exercises/questions. Combines exercises in radiation physics and medical physics. This exercise book contains 300 typical problems and exercises in modern physics and radiation physics with complete solutions, detailed equations and graphs. This textbook is linked directly with the textbook ''Radiation Physics for Medical Physicists'', Springer (2010) but can also be used in combination with other related textbooks. For ease of use, this textbook has exactly the same organizational layout (14 chapters, 128 sections) as the ''Radiation Physics for Medical Physicists'' textbook and each section is covered by at least one problem with solution given. Equations, figures and tables are cross-referenced between the two books. It is the only large compilation of textbook material and associated solved problems in medical physics, radiation physics, and biophysics.
Upgrading environmental radiation data: health physics society committee report HPSR-1 (1980)
International Nuclear Information System (INIS)
1980-08-01
This report is a collection of nine individual Health Physics Society subcommittee reports on different aspects of environmental radiation data associated with nuclear power plants. The subcommittee reports include: Environmental Radiation Monitoring Objectives, Definition of Critical Pathways and Radionuclides for Population Radiation Exposure at Nuclear Power Stations, Propagation of Uncertainties in Environmental Pathway Dose Models, Detection of Changes in Environmental Levels Due to Nuclear Power Plants, Quality Assurance for Environmental Monitoring Programs, Reporting of Environmental Radiation Measurements Data, Statistical Methods for Environmental Radiation Data Interpretation, Effective Communication with the Public, Environmental Radiological Surveillance-Mechanisms for Information Exchange
Moderate Image Spectrometer (MODIS) Fire Radiative Energy: Physics and Applications
Kaufman, Y.
2004-01-01
MODIS fire channel does not saturate in the presence of fires. The fire channel therefore is used to estimate the fire radiative energy, a measure of the rate of biomass consumption in the fire. We found correlation between the fire radiative energy, the rate of formation of burn scars and the rate of emission of aerosol from the fires. Others found correlations between the fire radiative energy and the rate of biomass consumption. This relationships can be used to estimates the emissions from the fires and to estimate the fire hazards.
International Nuclear Information System (INIS)
1994-11-01
The catalogue lists all sales publications of the IAEA dealing with Life Sciences issued during the period 1980-1994. The publications are grouped in the following chapters: Nuclear Medicine (including Radiopharmaceuticals), Radiation Biology and Medical Physics (including Dosimetry)
Mishchenko, Michael I.
2014-01-01
This Essay traces the centuries-long history of the phenomenological disciplines of directional radiometry and radiative transfer in turbid media, discusses their fundamental weaknesses, and outlines the convoluted process of their conversion into legitimate branches of physical optics.
Non-ionizing radiations : physical characteristics, biological effects and health hazard assessment
International Nuclear Information System (INIS)
Repacholi, M.H.
1988-01-01
The Workshop was a project of the International Non-Ionizing Radiation Committee of IRPA and comprised a series of educational lectures and demonstrations intended to give a comprehensive overview of non-ionizing electromagnetic radiation: physical characteristics, sources of concern, levels of exposure, mechanisms of interaction and reported effects of these fields and radiations with biological tissues, human studies, health risk assessment, national and international standards and guidelines, and protective measures
Gravitational waves from spinning eccentric binaries
Csizmadia, Péter; Debreczeni, Gergely; Rácz, István; Vasúth, Mátyás
2012-12-01
This paper is to introduce a new software called CBwaves which provides a fast and accurate computational tool to determine the gravitational waveforms yielded by generic spinning binaries of neutron stars and/or black holes on eccentric orbits. This is done within the post-Newtonian (PN) framework by integrating the equations of motion and the spin precession equations, while the radiation field is determined by a simultaneous evaluation of the analytic waveforms. In applying CBwaves various physically interesting scenarios have been investigated. In particular, we have studied the appropriateness of the adiabatic approximation, and justified that the energy balance relation is indeed insensitive to the specific form of the applied radiation reaction term. By studying eccentric binary systems, it is demonstrated that circular template banks are very ineffective in identifying binaries even if they possess tiny residual orbital eccentricity, thus confirming a similar result obtained by Brown and Zimmerman (2010 Phys. Rev. D 81 024007). In addition, by investigating the validity of the energy balance relation we show that, contrary to the general expectations, the PN approximation should not be applied once the PN parameter gets beyond the critical value ˜0.08 - 0.1. Finally, by studying the early phase of the gravitational waves emitted by strongly eccentric binary systems—which could be formed e.g. in various many-body interactions in the galactic halo—we have found that they possess very specific characteristics which may be used to identify these type of binary systems. This paper is dedicated to the memory of our colleague and friend Péter Csizmadia a young physicist, computer expert and one of the best Hungarian mountaineers who disappeared in China’s Sichuan near the Ren Zhong Feng peak of the Himalayas on 23 Oct. 2009. We started to develop CBwaves jointly with Péter a couple of months before he left for China.
International Nuclear Information System (INIS)
Mishchenko, Michael I.
2014-01-01
This Essay traces the centuries-long history of the phenomenological disciplines of directional radiometry and radiative transfer in turbid media, discusses their fundamental weaknesses, and outlines the convoluted process of their conversion into legitimate branches of physical optics. - Highlights: • History of phenomenological radiometry and radiative transfer is described. • Fundamental weaknesses of these disciplines are discussed. • The process of their conversion into legitimate branches of physical optics is summarized
Testing the gravitational instability hypothesis?
Babul, Arif; Weinberg, David H.; Dekel, Avishai; Ostriker, Jeremiah P.
1994-01-01
that show correlations between galaxy density and velocity fields can rule out some physically interesting models of large-scale structure. In particular, successful reconstructions constrain the nature of any bias between the galaxy and mass distributions, since processes that modulate the efficiency of galaxy formation on large scales in a way that violates the continuity equation also produce a mismatch between the observed galaxy density and the density inferred from the peculiar velocity field. We obtain successful reconstructions for a gravitational model with peaks biasing, but we also show examples of gravitational and nongravitational models that fail reconstruction tests because of more complicated modulations of galaxy formation.
New Metrics from a Fractional Gravitational Field
International Nuclear Information System (INIS)
El-Nabulsi, Rami Ahmad
2017-01-01
Agop et al. proved in Commun. Theor. Phys. (2008) that, a Reissner–Nordstrom type metric is obtained, if gauge gravitational field in a fractal spacetime is constructed by means of concepts of scale relativity. We prove in this short communication that similar result is obtained if gravity in D-spacetime dimensions is fractionalized by means of the Glaeske–Kilbas–Saigo fractional. Besides, non-singular gravitational fields are obtained without using extra-dimensions. We present few examples to show that these gravitational fields hold a number of motivating features in spacetime physics. (paper)
Non-Euclidean Geometry and Gravitation
Directory of Open Access Journals (Sweden)
Stavroulakis N.
2006-04-01
Full Text Available A great deal of misunderstandings and mathematical errors are involved in the currently accepted theory of the gravitational field generated by an isotropic spherical mass. The purpose of the present paper is to provide a short account of the rigorous mathematical theory and exhibit a new formulation of the problem. The solution of the corresponding equations of gravitation points out several new and unusual features of the stationary gravitational field which are related to the non-Euclidean structure of the space. Moreover it precludes the black hole from being a mathematical and physical notion.
Nanodosimetry: The missing link between radiobiology and radiation physics?
International Nuclear Information System (INIS)
Nettelbeck, H.; Rabus, H.
2011-01-01
It has long been assumed that the initiation of radiation induced damage to biological cells is dominated by inelastic interactions occurring at the location of the DNA or within its vicinity. The subcellular distribution of such interactions therefore plays a key role in the biological effectiveness of ionising radiation, where appropriate definitions of concepts such as radiation quality, which cannot be described by macroscopic quantities like absorbed dose, demand a study of particle track structure on the nanometre scale. This has presented an ongoing challenge in the metrology of ionising radiation to either supplement or replace the concept of absorbed dose with another quantity that accounts for the particle track structure within radiosensitive biological targets. A potential means for characterising radiation quality in this way may be that of nanodosimetry, a concept based on the frequency distribution of ionisation cluster sizes induced by single ionising particles interacting in nanometric volumes. This work gives a brief overview of nanodosimetric concepts and recent developments in the field of nanodosimetry.
Review of Nuclear Physics Experiments for Space Radiation
Norbury, John W.; Miller, Jack; Adamczyk, Anne M.; Heilbronn, Lawrence H.; Townsend, Lawrence W.; Blattnig, Steve R.; Norman, Ryan B.; Guetersloh, Stephen B.; Zeitlin, Cary J.
2011-01-01
Human space flight requires protecting astronauts from the harmful effects of space radiation. The availability of measured nuclear cross section data needed for these studies is reviewed in the present paper. The energy range of interest for radiation protection is approximately 100 MeV/n to 10 GeV/n. The majority of data are for projectile fragmentation partial and total cross sections, including both charge changing and isotopic cross sections. The cross section data are organized into categories which include charge changing, elemental, isotopic for total, single and double differential with respect to momentum, energy and angle. Gaps in the data relevant to space radiation protection are discussed and recommendations for future experiments are made.
Department of Environmental and Radiation Transport Physics - Overview
International Nuclear Information System (INIS)
Woznicka, U.
2002-01-01
The scientific activity of the Department in 2001 can be summarised as follows. In the Environmental Physics Laboratory gas chromatography methods are being developed mainly for atmospheric investigations and hydrological applications. A method for measuring the SF 6 contents in water for determining the age of young groundwaters is well advanced. Reconnaissance measurements performed in two aquifers yielded a reasonable agreement with the ages obtained from the tritium method. A proper determination of trace gases dissolved in water requires the measurement of the so-called ''excess air'' resulting from the excessive dissolution of air bubbles at the groundwater table. For this purpose, a new method of analysing the concentrations of argon and neon in water was developed. The separation of argon from oxygen in gas samples, extracted from water, carried out with the help of the catalyst of NiO type. Neon is determined with the aid of a pulse discharge helium detector (type PI-2D, VALCO Ltd) doped with neon. The initial results are promising. Atmospheric investigations were continued by measurements of the concentrations of F-11, F-12, F-113, CHCl 3 , CHCCl 3 , CCl 4 , and SF 6 in the Cracow area. Incidentally, high concentrations of SF 6 are observed. The air flow trajectories available in the BADC Trajectory Service (http://cirrus.badc.rl.ac.uk/trajectory/) were used in an attempt to identify the emission source of these high SF 6 concentrations. So far only the north-west direction was identified. Hydrogeological investigations of the origin and ages of different interesting groundwater systems by environmental isotope methods were also continued, and the origin of chemically unique mineral water in Krynica Spa has been identified as related to dehydration of clay minerals in burial diagenesis. The Natural Radioactivity Laboratory has been involved in interdisciplinary projects on the measurements of radon concentration in soil gas in areas of different
An Experimental Concept for Probing Nonlinear Physics in Radiation Belts
Crabtree, C. E.; Ganguli, G.; Tejero, E. M.; Amatucci, B.; Siefring, C. L.
2017-12-01
A sounding rocket experiment, Space Measurement of Rocket-Released Turbulence (SMART), can be used to probe the nonlinear response to a known stimulus injected into the radiation belt. Release of high-speed neutral barium atoms (8- 10 km/s) generated by a shaped charge explosion in the ionosphere can be used as the source of free energy to seed weak turbulence in the ionosphere. The Ba atoms are photo-ionized forming a ring velocity distribution of heavy Ba+ that is known to generate lower hybrid waves. Induced nonlinear scattering will convert the lower hybrid waves into EM whistler/magnetosonic waves. The escape of the whistlers from the ionospheric region into the radiation belts has been studied and their observable signatures quantified. The novelty of the SMART experiment is to make coordinated measurement of the cause and effect of the turbulence in space plasmas and from that to deduce the role of nonlinear scattering in the radiation belts. Sounding rocket will carry a Ba release module and an instrumented daughter section that includes vector wave magnetic and electric field sensors, Langmuir probes and energetic particle detectors. The goal of these measurements is to determine the whistler and lower hybrid wave amplitudes and spectrum in the ionospheric source region and look for precipitated particles. The Ba release may occur at 600-700 km near apogee. Ground based cameras and radio diagnostics can be used to characterize the Ba and Ba+ release. The Van Allen Probes can be used to detect the propagation of the scattering-generated whistler waves and their effects in the radiation belts. By detecting whistlers and measuring their energy density in the radiation belts the SMART mission will confirm the nonlinear generation of whistlers through scattering of lower hybrid along with other nonlinear responses of the radiation belts and their connection to weak turbulence.
Thomas, EG
2014-01-01
Physics to a Degree provides an extensive collection of problems suitable for self-study or tutorial and group work at the level of an undergraduate physics course. This novel set of exercises draws together the core elements of an undergraduate physics degree and provides students with the problem solving skills needed for general physics' examinations and for real-life situations encountered by the professional physicist. Topics include force, momentum, gravitation, Bernoulli's Theorem, magnetic fields, blackbody radiation, relativistic travel, mechanics near the speed of light, radioactive
Radiation Hardened 10BASE-T Ethernet Physical Layer (PHY)
Lin, Michael R. (Inventor); Petrick, David J. (Inventor); Ballou, Kevin M. (Inventor); Espinosa, Daniel C. (Inventor); James, Edward F. (Inventor); Kliesner, Matthew A. (Inventor)
2017-01-01
Embodiments may provide a radiation hardened 10BASE-T Ethernet interface circuit suitable for space flight and in compliance with the IEEE 802.3 standard for Ethernet. The various embodiments may provide a 10BASE-T Ethernet interface circuit, comprising a field programmable gate array (FPGA), a transmitter circuit connected to the FPGA, a receiver circuit connected to the FPGA, and a transformer connected to the transmitter circuit and the receiver circuit. In the various embodiments, the FPGA, transmitter circuit, receiver circuit, and transformer may be radiation hardened.
Experiments in atomic and applied physics using synchrotron radiation
International Nuclear Information System (INIS)
Jones, K.W.
1987-01-01
A diverse program in atomic and applied physics using x rays produced at the X-26 beam line at the Brookhaven National Synchrotron Light Source is in progress. The atomic physics program studies the properties of multiply-ionized atoms using the x rays for photo-excitation and ionization of neutral atoms and ion beams. The applied physics program builds on the techniques and results of the atomic physics work to develop new analytical techniques for elemental and chemical characterization of materials. The results are then used for a general experimental program in biomedical sciences, geo- and cosmochemistry, and materials sciences. The present status of the program is illustrated by describing selected experiments. Prospects for development of new experimental capabilities are discussed in terms of a heavy ion storage ring for atomic physics experiments and the feasibility of photoelectron microscopy for high spatial resolution analytical work. 21 refs., 11 figs., 2 tabs
Post-Newtonian gravitational bremsstrahlung
International Nuclear Information System (INIS)
Turner, M.; Will, C.M.
1977-07-01
Formulae and numerical results are presented for the gravitational radiation emitted during a low-deflection encounter between two massive bodies. Results are valid through post-Newtonian order within general relativity. The gravitational waveform, the total luminosity and total emitted energy, the angular distribution of emitted energy, and the frequency spectrum are discussed in detail. A method boosting the accuracy of these quantities to post Newtonian order is also presented. A numerical comparison of results with those of Peters, and of Kovacs and Thorne shows that the post Newtonian method is reliable to better than 0.1 percent at v = 0.1 c, to a few percent at v = 0.35 c, and to 10 to 20 percent at v = 0.5 c
Quantum metrology for gravitational wave astronomy.
Schnabel, Roman; Mavalvala, Nergis; McClelland, David E; Lam, Ping K
2010-11-16
Einstein's general theory of relativity predicts that accelerating mass distributions produce gravitational radiation, analogous to electromagnetic radiation from accelerating charges. These gravitational waves (GWs) have not been directly detected to date, but are expected to open a new window to the Universe once the detectors, kilometre-scale laser interferometers measuring the distance between quasi-free-falling mirrors, have achieved adequate sensitivity. Recent advances in quantum metrology may now contribute to provide the required sensitivity boost. The so-called squeezed light is able to quantum entangle the high-power laser fields in the interferometer arms, and could have a key role in the realization of GW astronomy.
Energy Technology Data Exchange (ETDEWEB)
Fiebich, Martin [Technische Hochschule Mittelhessen, Giessen (Germany). Inst. fuer Medizinische Physik und Strahlenschutz
2017-07-01
In the frame of physical dosimetry new dose units have been defined: the depth personal dose (equivalent dose in 10 mm depth) and the surface personal dose (equivalent dose in 0.07 mm depth). Physical dosimetry is applied for the determination of occupational radiation exposure, the radiation protected area control, the estimation of radiation exposure of patients during radiotherapy, for quality assurance and in research projects and optimization challenges. Developments have appeared with respect to punctual measuring chambers, eye lens dosimetry, OSL (optically stimulated luminescence) dosimetry, real-time dosimetry and Monte Carlo methods. New detection limits of about 1 micro Gy were reached.
The Fifth International Ural seminar. Radiation damage physics of metals and alloys. Abstracts
International Nuclear Information System (INIS)
2003-01-01
Presented are the abstracts of The Fifth International Ural seminar Damage physics of metals and alloys. General problems of radiation damage physics, radiation effect on change of microstucture and the properties of metals and alloys, as well as materials for nuclear and thermonuclear energetics are considered. The themes of reports are the following: correlation effects in cascades of atom-atomic collisions; radiation-induced strengthening critical current density in YBa 2 Cu 3 O 7-x superconductors; conditions of forming and hydrides growth in irradiated zirconium alloys [ru
BOOK REVIEW: Gravitational Waves, Volume 1: Theory and Experiments
Poisson, Eric
2008-10-01
discussion is helpful, as it clarifies some of the puzzling aspects of general covariance. Next the treatment becomes more sophisticated: the waves are allowed to propagate in an arbitrary background spacetime, and the energy momentum carried by the wave is identified by the second-order perturbation of the Einstein tensor. In chapter 2 the waves are given a field-theoretic foundation that is less familiar (but refreshing) to a relativist, but would appeal to a practitioner of effective field theories. In an interesting section of chapter 2, the author gives a mass to the (classical) graviton and explores the physical consequences of this proposal. In chapter 3 the author returns to the standard linearized theory and develops the multipolar expansion of the gravitational-wave field in the context of slowly-moving sources; at leading order he obtains the famous quadrupole formula. His treatment is very detailed, and it includes a complete account of symmetric-tracefree tensors and tensorial spherical harmonics. It is, however, necessarily limited to sources with negligible internal gravity. Unfortunately (and this is a familiar complaint of relativists) the author omits to warn the reader of this important limitation. In fact, the chapter opens with a statement of the virial theorem of Newtonian gravity, which may well mislead the reader to believe that the linearized theory can be applied to a system bound by gravitational forces. This misconception is confirmed when, in chapter 4, the author applies the quadrupole formula to gravitationally-bound systems such as an inspiraling compact binary, a rigidly rotating body, and a mass falling toward a black hole. This said, the presentation of these main sources of gravitational waves is otherwise irreproachable, and a wealth of useful information is presented in a clear and lucid manner. For example, the discussion of inspiraling compact binaries includes a derivation of the orbital evolution of circular and eccentric orbits
Maser Emission from Gravitational States on Isolated Neutron Stars
Tepliakov, Nikita V.; Vovk, Tatiana A.; Rukhlenko, Ivan D.; Rozhdestvensky, Yuri V.
2018-04-01
Despite years of research on neutron stars, the source of their radio emission is still under debate. Here we propose a new coherent mechanism of pulsar radio emission based on transitions between gravitational states of electrons confined above the pulsar atmosphere. Our mechanism assumes that the coherent radiation is generated upon the electric and magnetic dipole transitions of electrons falling onto the polar caps of the pulsar, and predicts that this radiation occurs at radio frequencies—in full agreement with the observed emission spectra. We show that while the linearly polarized electric dipole radiation propagates parallel to the neutron star surface and has a fan-shape angular spectrum, the magnetic dipole emission comes from the magnetic poles of the pulsar in the form of two narrow beams and is elliptically polarized due to the spin–orbit coupling of electrons confined by the magnetic field. By explaining the main observables of the pulsar radio emission, the proposed mechanism indicates that gravitational quantum confinement plays an essential role in the physics of neutron stars.
Global aspects of radiation memory
International Nuclear Information System (INIS)
Winicour, J
2014-01-01
Gravitational radiation has a memory effect represented by a net change in the relative positions of test particles. Both the linear and nonlinear sources proposed for this radiation memory are of the ‘electric’ type, or E mode, as characterized by the even parity of the polarization pattern. Although ‘magnetic’ type, or B mode, radiation memory is mathematically possible, no physically realistic source has been identified. There is an electromagnetic counterpart to radiation memory in which the velocity of charged test particles obtain a net ‘kick’. Again, the physically realistic sources of electromagnetic radiation memory that have been identified are of the electric type. In this paper, a global null cone description of the electromagnetic field is applied to establish the non-existence of B-mode radiation memory and the non-existence of E-mode radiation memory due to a bound charge distribution. (paper)
Radiation-hard silicon photonics for high energy physics and beyond
CERN. Geneva
2016-01-01
Silicon photonics (SiPh) is currently being investigated as a promising technology for future radiation hard optical links. The possibility of integrating SiPh devices with electronics and/or silicon particle sensors as well as an expected very high resistance against radiation damage make this technology particularly interesting for potential use close to the interaction points in future in high energy physics experiments and other radiation-sensitive applications. The presentation will summarize the outcomes of the research on radiation hard SiPh conducted within the ICE-DIP projected.
Use of health physics in radiation medicine and its status in India
International Nuclear Information System (INIS)
Srivastva, R.N.L.; Jauhari, R.K.
1993-01-01
Science of health physics has assumed importance in the use of complicated radiation equipment and procedure of radiotherapy. In India there are training facilities in health physics available at Bhabha Atomic Research Centre and in Bombay University. They are described (R.G.)