WorldWideScience

Sample records for bremsstrahlung magnetic

  1. Strong linear polarization of bremsstrahlung emissivity in photospheres of magnetic white dwarfs

    Energy Technology Data Exchange (ETDEWEB)

    Bubukina, I I; Koryagin, S A, E-mail: koryagin@appl.sci-nnov.r [Institute of Applied Physics of the Russian Academy of Sciences, 46 Uljanova str., Nizhny Novgorod 603950 (Russian Federation)

    2009-06-01

    We discuss the strong linear polarization and the appreciable decrease of the bremsstrahlung emissivity at frequencies below the electron cyclotron frequency (infrared wave band) in the photospheres of the isolated magnetic white dwarfs. In the photospheres of strongly magnetized white dwarfs (B > 10{sup 7} G, T approx 10{sup 4} K), the electron's Larmor radius becomes smaller than the characteristic impact parameter of close Coulomb collisions in a non-magnetized plasma. Thus, the cyclotron period of the electron becomes smaller than the duration of all distant collisions and of most close collisions. The magnetic field effectively 'freezes' the electron motion in the plane transverse to the magnetic field lines. The resulting motion is nearly one-dimensional and parallel to the magnetic field, inducing a strong linear polarization of the bremsstrahlung emission. Being attached to a magnetic field line, an electron cannot approach an ion as closely as it does in the case in which the magnetic field is absent. Thus, the bremsstrahlung emissivity appreciably decreases. We analytically compute an approximation to the spectrum of the strongly linear polarized bremsstrahlung emissivity at the frequencies below the electron cyclotron frequency.

  2. Effect of bremsstrahlung radiation emission on distributions of runaway electrons in magnetized plasmas

    CERN Document Server

    Embréus, Ola; Newton, Sarah; Papp, Gergely; Hirvijoki, Eero; Fülöp, Tünde

    2015-01-01

    Bremsstrahlung radiation is an important energy loss mechanism for energetic electrons in plasmas. In this paper we investigate the effect of bremsstrahlung radiation reaction on the electron distribution in 2D momentum space. We show that the emission of bremsstrahlung radiation leads to non-monotonic features in the electron distribution function and describe how the simultaneous inclusion of synchrotron and bremsstrahlung radiation losses affects the dynamics of fast electrons. We give quantitative expressions for (1) the maximum electron energy attainable in the presence of bremsstrahlung losses and (2) when bremsstrahlung radiation losses are expected to have a stronger effect than synchrotron losses, and verify these expressions numerically. We find that, in typical tokamak scenarios, synchrotron radiation losses will dominate over bremsstrahlung losses, except in cases of very high density, such as during massive gas injection.

  3. Elimination of bremsstrahlung in activation analysis by the deflection of β-particles in a magnetic field

    International Nuclear Information System (INIS)

    The structureless 'background' at x-ray and low energy γ-ray region, resulting from bremsstrahlung due to the stopping of β-radiations, causes serious problems in nuclear spectroscopy. In order to reduce the background and therefore to increase the sensitivity of the nuclear analytical technique and the number of elements observable, a methodology is developed to deflect the β-particles by a magnetic field. The experimental setup consists of a permanent magnet (∼1 kG), Ge(Li) solid-state detector and multichannel analyzer. (author) 10 refs.; 3 figs.; 3 tabs

  4. Model of the bremsstrahlung emission accompanying interactions between protons and nuclei from low up to intermediate energies: role of magnetic emission

    CERN Document Server

    Maydanyuk, Sergei P

    2012-01-01

    A new model of the bremsstrahlung emission which accompanies proton decay and collisions of protons off nuclei in the energy region from the lowest up to intermediate, has been developed. This model includes spin formalism, potential approach for description of interaction between protons and nuclei, and operator of emission includes component of the magnetic emission (defined on the basis of Pauli equation). In the problem of the bremsstrahlung during the proton decay in the first time a role of the magnetic emission is studied using such a model. For the studied $^{146}{\\rm Tm}$ nucleus it has been studied the following: (1) How much does the magnetic emission change the full bremsstrahlung spectrum? (2) At which angle is the magnetic emission the most intensive relatively electric one? (3) Is there some space region where the magnetic emission increases strongly relatively electric one? (4) How intensive is the magnetic emission in the tunneling region? (5) Which values has the probability at its maximum a...

  5. Graviton bremsstrahlung

    International Nuclear Information System (INIS)

    The graviton bremsstrahlung in the process of scattering of two charged spinless particles is considered. One of the particles is assumed to be massive. The cross sections of this process and of energy losses on graviton radiation are calculated. The possibility to apply the Weizsaecker-Williams method to this process is discussed. The results show that for both relativistic and nonrelativistic energies the graviton bremsstrahlung is approximately Gm2/α times smaller than electromagnetic one (G is the Newton gravitational constant, m - the mass of scattered particle). The results are in agreement with the statement about the weak character of interaction of gravitons with matter

  6. Model for bremsstrahlung emission accompanying interactions between protons and nuclei from low energies up to intermediate energies: Role of magnetic emission

    Science.gov (United States)

    Maydanyuk, Sergei P.

    2012-07-01

    A model of the bremsstrahlung emission which accompanies proton decay and collisions of protons off nuclei in the low- to intermediate-energy region has been developed. This model includes spin formalism, a potential approach for describing the interaction between protons and nuclei, and an emission that includes a component of the magnetic emission (defined on the basis of the Pauli equation). For the problem of bremsstrahlung during proton decay the role of magnetic emission is studied by using such a model. For the 146Tm nucleus the following has been studied: (1) How much does the magnetic emission change the full bremsstrahlung spectrum? (2) At which angle is the magnetic emission the most intensive relative to the electric emission? (3) Is there some spatial region where the magnetic emission increases strongly relative to the electric emission? (4) How intensive is the magnetic emission in the tunneling region? (5) Which is the maximal probability? Which value does it equal to at the zero-energy limit of the emitted photons? It is demonstrated that the model is able to describe well enough experimental data of bremsstrahlung emission which accompanies collisions of protons off 9C, 64Cu, and 107Ag nuclei at an incident energy of Tlab=72 MeV (at a photon energy up to 60 MeV) and off 9Be, 12C, and 208Pb nuclei at an incident energy of Tlab=140 MeV (at a photon energy up to 120 MeV).

  7. Polarization Bremsstrahlung

    CERN Document Server

    Korol, Andrey V

    2014-01-01

    This book introduces and reviews both theory and applications of polarizational bremsstrahlung, i.e. the electromagnetic radiation emitted during collisions of charged particles with structured, thus polarizable targets, such as atoms, molecules and clusters.   The subject, following the first experimental evidence a few decades ago, has gained importance through a number of modern applications.  Thus, the study of several radiative mechanisms is expected to lead to the design of novel light sources, operating in various parts of the electromagnetic spectrum. Conversely, the analysis of the spectral and angular distribution of the photon emission constitutes a new tool for extracting information on the interaction of the colliding particles, and on their internal structure and dynamical properties.   Last but not least, accurate quantitative descriptions of the photon emission processes determine the radiative energy losses of particles in various media, thereby providing essential  information required f...

  8. Polarization bremsstrahlung

    International Nuclear Information System (INIS)

    Authored by leading experts in the field. Self-contained introduction to the subject matter. Suitable as graduate text on the topic. This book introduces and reviews both theory and applications of polarizational bremsstrahlung, i.e. the electromagnetic radiation emitted during collisions of charged particles with structured, thus polarizable targets, such as atoms, molecules and clusters. The subject, following the first experimental evidence a few decades ago, has gained importance through a number of modern applications. Thus, the study of several radiative mechanisms is expected to lead to the design of novel light sources, operating in various parts of the electromagnetic spectrum. Conversely, the analysis of the spectral and angular distribution of the photon emission constitutes a new tool for extracting information on the interaction of the colliding particles, and on their internal structure and dynamical properties. Last but not least, accurate quantitative descriptions of the photon emission processes determine the radiative energy losses of particles in various media, thereby providing essential information required for e.g. plasma diagnostics as well as astrophysical and medical applications (such as radiation therapy). This book primarily addresses graduate students and researchers with a background in atomic, molecular, optical or plasma physics, but will also be of benefit to anyone wishing to enter the field.

  9. Proton-proton bremsstrahlung

    International Nuclear Information System (INIS)

    The use is emphasised of the ppγ process as laboratory to study among others, relativistic effects and role of non-nucleonic degrees of freedom below the pion threshold. The process of bremsstrahlung, in particular pp-bremsstrahlung, forms a very sensitive probe to effects which are often ignored because they are difficult to calculate and are estimated to be small. The proton-proton bremsstrahlung (ppγ) process is unique since it is the simplest process where one is sensitive to the off-shell nucleon-nucleon T-matrix, the role of the Δ-isobar in nuclear Compton scattering and other

  10. Bremsstrahlung in $\\alpha$ Decay

    CERN Document Server

    Takigawa, N; Hagino, K; Ono, A; Brink, D M

    1999-01-01

    A quantum mechanical analysis of the bremsstrahlung in $\\alpha$ decay of $^{210}$Po is performed in close reference to a semiclassical theory. We clarify the contribution from the tunneling, mixed, outside barrier regions and from the wall of the inner potential well to the final spectral distribution, and discuss their interplay. We also comment on the validity of semiclassical calculations, and the possibility to eliminate the ambiguity in the nuclear potential between the alpha particle and daughter nucleus using the bremsstrahlung spectrum.

  11. A measurement of the magnetic dipole moment of the Δ++(1232) from the bremsstrahlung process πp → πpγ

    International Nuclear Information System (INIS)

    We have measured the cross section from the bremsstrahlung process π+p → π+pγ for incident pions of energy 299 MeV. We detected the out going pion in the angular range from 55 to 950 in the lab, and photons were detected near 2400 in the lab. We compare this measured cross-section to the MIT theory in order to extract a measurement of the magnetic dipole moment of the Δ++(1232), μ/sub Δ/. In order to compare our results with the MIT theory, we have folded the MIT theory into the acceptance of our apparatus. We find that for pion angles between 55 and 750 the theory gives us a dipole moment of: 2.3μ/sub p/ 0 we find that the MIT theory predicts a cross-section which is larger than our measured cross-section, and makes it difficult to extract a value of μ/sub Δ/. This over prediction is not understood, but consistent with a similar effect when the MIT theory is fit to previous data. 78 figs., 29 tabs

  12. Polarization of Bremsstrahlung

    International Nuclear Information System (INIS)

    The numerical results for the polarization of Bremsstrahlung are presented. The multiple scattering of electrons in the target is taken into account. The angular-and photon energy dependences are seen on the curves for an incident 25 MeV electron energy. (Author)

  13. Simulation of Bremsstrahlung production

    Energy Technology Data Exchange (ETDEWEB)

    Patau, J.P.; Malbert, M.; Terrissol, M. (Centre de Physique Atomique, Toulouse (France))

    1981-10-01

    Electron slowing down and related phenomena are often greatly affected by bremsstrahlung production. Each creation of photon is individually simulated on the basis of a cross-section pack advised by Koch and Motz with corrections in the high energy frequency limit region. An accurate and fast sampling method is described. Its applicability covers a range between 50 keV and 80 MeV for target atoms whose atomic number is from 5 up to 90.

  14. Polarization bremsstrahlung in α decay

    International Nuclear Information System (INIS)

    A mechanism of formation of electromagnetic radiation that accompanies α decay and is associated with the emission of photons by electrons of atomic shells due to the scattering of α particles by these atoms (polarization bremsstrahlung) is proposed. It is shown that, when the photon energy is no higher than the energy of K electrons of an atom, polarization bremsstrahlung makes a significant contribution to the bremsstrahlung in α decay

  15. Creation of high energy bremsstrahlung and intensity by a multitarget and refocusing of the scattered electrons by small-angle backscatter at the wall of a cone and magnetic fields

    CERN Document Server

    Ulmer, W

    2011-01-01

    The yield of bremsstrahlung from collisions of fast electrons (energy at least 6 MeV) with a tungsten target can be significantly improved by exploitation of Tungsten wall scatter in a multi-layered target. The Tungsten wall can serve to refocuse small angle scattered electrons. It is necessary that the thickness of one Tungsten layer does not exceed 0.02 mm. Further refocusing of electrons results from suitable magnetic fields with field strength between 0.5 Tesla and 6 Tesla (if the cone with multi-layered targets is rather narrow). Linear accelerators in radiation therapy only need refocusing by wall scatter without further magnetic fields (standard case: ca. 100 - 000 plates with 0.01 mm thickness and 1 mm distance between the plates). The construction of a very narrow bremsstrahlung beam with extremely high photon intensity requires an additional strong magnetic field (order 1 - 6 Tesla), which provides the possibility to check Heisenberg-Euler scatter of high energy photons.

  16. Electron polarimetry with bremsstrahlung

    International Nuclear Information System (INIS)

    Due to the spin-orbit interaction, the electron scattering from the nucleus is sensitive to the spin orientation of that electron. This is used for polarimetry of electron beams in the Mott method. The spin-orbit interaction was also observed in bremsstrahlung. In this article we analyze its potential for polarimetry as an alternative to the Mott method. It can simultaneously measure all three electron polarization components. It should work in the energy range of 50 keV up to several MeV and can be applied at beam intensities higher than 100 nA. It needs a thin heavy element target, two or four x-ray detectors and one x-ray linear polarimeter

  17. Coherence effects in nuclear bremsstrahlung

    NARCIS (Netherlands)

    Lohner, H

    2002-01-01

    The production of nuclear bremsstrahlung (Egamma > 30 MeV) has been studied in heavy-ion collisions, as well as proton and alpha-particle collisions with nuclei. In heavy-ion reactions the measured photon spectra show an exponential shape dominated by the incoherent sum of photons produced in first-

  18. Radiative corrections to pion-nucleus bremsstrahlung

    CERN Document Server

    Kaiser, N

    2008-01-01

    We calculate the one-photon loop radiative corrections to virtual pion Compton scattering $\\pi^- \\gamma^* \\to \\pi^- \\gamma$, that subprocess which determines in the one-photon exchange approximation the pion-nucleus bremsstrahlung reaction $\\pi^- Z\\to \\pi^- Z \\gamma$. Ultraviolet and infrared divergencies of the loop integrals are both treated by dimensional regularization. Analytical expressions for the ${\\cal O}(\\alpha)$ corrections to the virtual Compton scattering amplitudes, $A(s,u,Q)$ and $B(s,u,Q)$, are derived with their full dependence on the (small) photon virtuality $Q$ from 9 classes of contributing one-loop diagrams. Infrared finiteness of these virtual radiative corrections is achieved (in the standard way) by including soft photon radiation below an energy cut-off $\\lambda$. In the region of low $\\pi^- \\gamma$ center-of-mass energies, where the pion-nucleus bremsstrahlung process is used to extract the pion electric and magnetic polarizabilities, we find radiative corrections up to about -3% fo...

  19. Coulomb correction calculations of pp Bremsstrahlung

    International Nuclear Information System (INIS)

    The effects of the Coulomb interaction upon the photon cross section and analyzing power from pp Bremsstrahlung have been studied in detail. Off-shell properties of the Coulomb T matrices have been considered but the associated, Coulomb modified, hadronic T matrices are important elements in any analyses of low energy, forward proton scattering data. At the lowest energy considered (5 MeV), the full calculations gave cross sections that were half the size of those found without Coulomb effects or with a simple model approximation to them. With increasing energy, the cross sections varied to those characteristic of magnetic interaction dominance and the specific differences due to Coulomb effects diminished. 47 refs., 7 figs

  20. Diffractive Bremsstrahlung in Hadronic Collisions

    Directory of Open Access Journals (Sweden)

    Roman Pasechnik

    2015-01-01

    Full Text Available Production of heavy photons (Drell-Yan, gauge bosons, Higgs bosons, and heavy flavors, which is treated within the QCD parton model as a result of hard parton-parton collision, can be considered a bremsstrahlung process in the target rest frame. In this review, we discuss the basic features of the diffractive channels of these processes in the framework of color dipole approach. The main observation is a dramatic breakdown of diffractive QCD factorisation due to the interplay between soft and hard interactions, which dominates these processes. This observation is crucial for phenomenological studies of diffractive reactions in high energy hadronic collisions.

  1. Diffractive bremsstrahlung in hadronic collisions

    CERN Document Server

    Pasechnik, Roman; Potashnikova, Irina

    2015-01-01

    Production of heavy photons (Drell-Yan), gauge bosons, Higgs bosons, heavy flavors, which is treated within the QCD parton model as a result of hard parton-parton collision, can be considered as a bremsstrahlung process in the target rest frame. In this review, we discuss the basic features of the diffractive channels of these processes in the framework of color dipole approach. The main observation is a dramatic breakdown of diffractive QCD factorisation due to the interplay between soft and hard interactions, which dominates these processes. This observation is crucial for phenomenological studies of diffractive reactions in high-energy hadronic collisions.

  2. Polarizational bremsstrahlung in non-relativistic collision

    CERN Document Server

    Korol, A V

    2004-01-01

    We review the developments made during the last decade in the theory of polarization bremsstrahlung in the non-relativistic domain. A literature survey covering the latest history of the phenomenon is given. The main features which distinguish the polarization bremsstrahlung from other mechanisms of radiation are discussed and illustrated by the results of numerical calculations.

  3. Neutrino-pair bremsstrahlung in a neutron star crust

    CERN Document Server

    Ofengeim, D D; Yakovlev, D G

    2014-01-01

    Based on the formalism by Kaminker et al. (Astron. Astrophys. 343 (1999) 1009) we derive an analytic approximation for neutrino-pair bremsstrahlung emissivity due to scattering of electrons by atomic nuclei in the neutron star crust of any realistic composition. The emissivity is expressed through generalized Coulomb logarithm which we fit by introducing an effective potential of electron-nucleus scattering. In addition, we study the conditions at which the neutrino bremsstrahlung in the crust is affected by strong magnetic fields. The results can be applied for modelling of many phenomena in neutron stars, such as thermal relaxation in young isolated neutron stars and in accreting neutron stars with overheated crust in soft X-ray transients.

  4. Angular distribution of coherent bremsstrahlung

    International Nuclear Information System (INIS)

    The angular distribution of the linearly polarised photon beam produced by coherent bremsstrahlung from an aligned diamond radiator has been measured at the MAMI A2 tagged photon facility. The measurements were made with a prototype position sensitive photon detector which utilises the pair production process and a double sided silicon strip detector. This polarised photon beam is used for nuclear and hadronic experiments and in their analysis the polarisation is obtained from a calculation, which matches the experimental intensity spectrum. As the polarisation is related to the photon beam angular distribution, the present measurements can be used to test this calculation. The overall agreement is found to be good although there are some regions where significant discrepancies exist.

  5. Nuclear structure effects in high-energy bremsstrahlung from spin-0 and spin-1/2 nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Jakubassa-Amundsen, Doris [University of Munich (Germany)

    2014-07-01

    Bremsstrahlung from relativistic spin-polarized electrons colliding with inert nuclei is calculated by taking into account the nuclear form factors and the kinematical recoil. For the spin-1/2 nuclei additional contributions from the anomalous magnetic moment and the dynamical recoil are considered. Electron bremsstrahlung is described with the help of semirelativistic wavefunctions while nuclear bremsstrahlung, when present, is treated within the Born approximation. The triply differential bremsstrahlung cross section is integrated over the electron scattering angle to study the polarization correlations between the beam electron and the emitted photon. Results are shown for 20-120 MeV electrons colliding with protons, 19F, 64Zn and 89Y. It is also attempted to explain the background in electron spectra from nuclear excitation in terms of bremsstrahlung. As an example the 180 degree spectrum from exciting the giant M2 resonance in 90Zr by 42.7 MeV electrons is analyzed.

  6. Loopy constraints on leptophilic dark matter and internal bremsstrahlung

    International Nuclear Information System (INIS)

    A sharp and spatially extended peak in an astrophysical gamma ray spectrum would provide very strong evidence for the existence of dark matter (DM), given that there are no known astrophysical processes that could mimic such a signal. From the particle physics perspective, perhaps the simplest explanation for a gamma ray peak is internal bremsstrahlung in DM annihilation through a charged t-channel mediator η close in mass to the DM particle χ. Since DM annihilation to quarks is already tightly constrained in this scenario, we focus here on the leptophilic case. We compute the electromagnetic anapole and dipole moments that DM acquires at 1-loop, and we find an interesting enhancement of these moments if the DM particle and the mediator are close in mass. We constrain the DM anapole and dipole moments using direct detection data, and then translate these limits into bounds on the DM annihilation cross section. Our bounds are highly competitive with those from astrophysical gamma ray searches. In the second part of the paper, we derive complementary constraints on internal bremsstrahlung in DM annihilation using LEP mono-photon data, measurements of the anomalous magnetic moments of the electron and the muon, and searches for lepton flavor violation. We also comment on the impact of the internal bremsstrahlung scenario on the hyperfine splitting of true muonium

  7. Bremsstrahlung and synchrotron radiation from planet magnetospheres

    International Nuclear Information System (INIS)

    Bremsstrahlung and synchrotron radiation from the moving charged particles was calculated in planet magnetospheres. A program package RADIATION was developed for these calculations. The radiative intensity is projected on a far sphere. The directional dependence of the radiation during the penetration of charged particles through the polar cusp was calculated. The program package RADIATION can be also used for treating the radiation of plasma cluster penetrating through the electric double layer, MHD and compress magnetic bow shock, plasma fibers and pinches and in other important situations. Intensity of radiation was derived from advanced and retarded potentials calculated from the Maxwell set of equations. Only radiative fields are displayed (I ∼ 1/r2) and the space intensity distribution does not depend on the distance of the projection sphere. In future non-radiative fields will be treated as well. In this case the distance of the projection sphere will be important parameter. The program was written in FORTRAN CVF 6.5A. The Earth magnetosphere and ionosphere form a natural protective shield from cosmic radiation and solar wind. Various models of the magnetosphere are compared (Tsyganenko, Safrankova-Nemecek, IGRF, and others) in the end of the contribution. (author)

  8. Analytic approximate radiation effects due to Bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Zvi I.

    2012-02-01

    The purpose of this note is to provide analytic approximate expressions that can provide quick estimates of the various effects of the Bremsstrahlung radiation produced relatively low energy electrons, such as the dumping of the beam into the beam stop at the ERL or field emission in superconducting cavities. The purpose of this work is not to replace a dependable calculation or, better yet, a measurement under real conditions, but to provide a quick but approximate estimate for guidance purposes only. These effects include dose to personnel, ozone generation in the air volume exposed to the radiation, hydrogen generation in the beam dump water cooling system and radiation damage to near-by magnets. These expressions can be used for other purposes, but one should note that the electron beam energy range is limited. In these calculations the good range is from about 0.5 MeV to 10 MeV. To help in the application of this note, calculations are presented as a worked out example for the beam dump of the R&D Energy Recovery Linac.

  9. Grand partition function of hadronic bremsstrahlung

    International Nuclear Information System (INIS)

    The grand partition function of hadronic bremsstrahlung is obtained using saddle-point procedures. Several levels of approximation are considered. The results are qualitatively consistent with earlier simple approximations

  10. Nucleus-Nucleus Bremsstrahlung from Ultrarelativistic Collisions

    OpenAIRE

    Jeon, Sangyong; Kapusta, Joseph; Chikanian, Alexei; Sandweiss, Jack

    1998-01-01

    The bremsstrahlung produced when heavy nuclei collide is estimated for central collisions at the Relativistic Heavy Ion Collider. Soft photons can be used to infer the rapidity distribution of the outgoing charge. An experimental design is outlined.

  11. Innovative bremsstrahlung research at Physics International Company

    International Nuclear Information System (INIS)

    For bremsstrahlung diodes optimized for X-ray production below 2 MeV, the area-weighted mean dose in the near-field is controlled by the atomic number, Z, of the converter material, and the electrical power, P, into the diode, scaling approximately as ZP. However, given the constraints of a fixed electrical power pulse from a generator, one can still vary the end-point voltage of the bremsstrahlung radiation without significant sacrifice in X-ray dose, or sharpen the risetime of the X-ray pulse without sacrificing the average dose-rate. In this paper, the authors review the design of a triple series diode on the Double-EAGLE generator which reduces the end-point voltage of the bremsstrahlung source from 1.5 MV down to 0.3 MV. In addition, they discuss pulse sharpening of the radiation from a pinched beam diode by optimizing the dimension of the tantalum converter. Also, they review some recent work on a linear bremsstrahlung diode which in principle can form part of a large-area bremsstrahlung source for a multi-module pulsed power generator

  12. Anomalous fluorescence line intensity in megavoltage bremsstrahlung

    Science.gov (United States)

    Pereira, Nino; Litz, Marc; Merkel, George; Schumer, Joseph; Seely, John; Carroll, Jeff

    2009-11-01

    A Cauchois transmission crystal spectrometer intended for laser plasma diagnostics has measured an anomalous ratio between the fluorescence lines in megavoltage bremsstrahlung. When observed in reflection, Kα1 fluorescence is twice as strong as the Kβ line, as is usual. However, in forward-directed bremsstrahlung from a 2 MV end point linear accelerator with a tungsten converter, the Kα1 and Kβ fluorescence are approximately equal. The anomalous fluorescence line ratio, unity, reflects the large amount of fluorescence generated on the side of the converter where the electrons enter, and the differential attenuation of the fluorescence photons as they pass through the converter to opposite side. Understanding of fluorescence in megavoltage bremsstrahlung is relevant to the explanation of anomalous line ratios in spectra produced by high-energy electrons generated by intense femtosecond laser irradiation.

  13. Pb isotopes induced Bremsstrahlung in bone, muscle and teeth

    International Nuclear Information System (INIS)

    The few isotopes Pb such as 210Pb, 211Pb, 212Pb, 213Pb, 214Pb and 215Pb are good beta emitters. These beta emitting Pb isotopes induces Bremsstrahlung radiation and could have different energies and intensities. The Bremsstrahlung yield is a function of two components namely internal Bremsstrahlung and external Bremsstrahlung. The intensity of external Bremsstrahlung (EB) largely depends on the energy of the emitted beta particles an atomic number of the surrounding matrix material. On the other hand, internal Bremsstrahlung component inherently depends on the interaction of the emitted beta particle with the nucleus of the source radionuclide itself. The shapes of Bremsstrahlung spectra are a basic ingredient in the understanding and quantification of beta-ray dosimetry. It is useful to have a convenient reference on the shapes of Bremsstrahlung spectra from various nuclides. The Bremsstrahlung spectra produced by Pb beta isotopes such as 210Pb, 211Pb, 212Pb, 213Pb, 214Pb and 215Pb in bone, muscle and teeth are computed. The computed spectral distributions are presented. The spectral shapes are primarily responsible for variations in the shapes of depth-dose distributions. They are intended to provide a quick and convenient reference for spectral shapes and to give an indication of the wide variation in these shapes. The computed Bremsstrahlung spectrum is used in the evaluation of Bremsstrahlung dose. The evaluated beta Bremsstrahlung dose as a function distance for the studied nuclides is also presented. The beta Bremsstrahlung dose decreases with the increase of distance. (author)

  14. Bremsstrahlung from relativistic heavy ions in matter

    International Nuclear Information System (INIS)

    The emission of electromagnetic radiation by relativistic bare heavy ions penetrating ordinary matter is investigated. Our main aim is to determine the bremsstrahlung which we define as the radiation emitted when the projectile does not break up. It pertains to collisions without nuclear contact ('ultraperipheral collisions'). Requirement of coherent action of the nucleons in order to keep the penetrating projectile intact limits bremsstrahlung to relatively soft photons. The spectrum shows a resonance structure with peak position near 2γ times the position of the giant dipole resonance, that is, near 25γ MeV for a lead ion (γ≡E/Mc2 is the Lorentz factor of the projectile of energy E and mass M). The maximum exceeds the bremsstrahlung from a hypothetical structureless, pointlike particle of the same charge and mass as the incoming nucleus, but rapid depletion follows on the high-energy side of the peak. As a result of its relative softness, bremsstrahlung never dominates the energy-loss process for heavy ions. As to the emission of electromagnetic radiation in collisions with nuclear break-up, it appears modest when pertaining to incoherent action of the projectile nucleons in noncontact collisions. In collisions with nuclear contact, though, substantial radiation is emitted. It overshoots the bremsstrahlung. However, despite the violence of contact events, the associated photon emission only exceeds the radiation from a hypothetical structureless pointlike nucleus [emitted energy per unit photon-energy interval essentially constant up to (γ-1)Mc2] at relatively low photon energies (for lead roughly below 0.2γ GeV, a limit which is about an order of magnitude above the position of the bremsstrahlung peak). Results are presented for bare lead ions penetrating a solid lead target at energies of 158 GeV/n (γ=170) and beyond.

  15. Bremsstrahlung from relativistic heavy ions in matter

    DEFF Research Database (Denmark)

    Sørensen, Allan Hvidkjær

    2010-01-01

     MeV for a lead ion (γ≡E/Mc2 is the Lorentz factor of the projectile of energy E and mass M). The maximum exceeds the bremsstrahlung from a hypothetical structureless, pointlike particle of the same charge and mass as the incoming nucleus, but rapid depletion follows on the high-energy side of the peak. As....... In collisions with nuclear contact, though, substantial radiation is emitted. It overshoots the bremsstrahlung. However, despite the violence of contact events, the associated photon emission only exceeds the radiation from a hypothetical structureless pointlike nucleus [emitted energy per unit...

  16. Polarization of thermal bremsstrahlung emission due to electron pressure anisotropy

    CERN Document Server

    Komarov, S; Churazov, E; Schekochihin, A

    2016-01-01

    Astrophysical plasmas are typically magnetized, with the Larmor radii of the charged particles many orders of magnitude smaller than their collisional mean free paths. The fundamental properties of such plasmas, e.g., conduction and viscosity, may depend on the instabilities driven by the anisotropy of the particle distribution functions and operating at scales comparable to the Larmor scales. We discuss a possibility that the pressure anisotropy of thermal electrons could produce polarization of thermal bremsstrahlung emission. In particular, we consider coherent large-scale motions in galaxy clusters to estimate the level of anisotropy driven by stretching of the magnetic-field lines by plasma flow and by heat fluxes associated with thermal gradients. Our estimate of the degree of polarization is $\\sim 0.1 \\%$ at energies $\\gtrsim kT$. While this value is too low for the forthcoming generation of X-ray polarimeters, it is potentially an important proxy for the processes taking place at extremely small scale...

  17. Bremsstrahlung gamma rays from light dark matter

    International Nuclear Information System (INIS)

    We discuss the often-neglected role of bremsstrahlung processes on the interstellar gas in computing indirect signatures of Dark Matter (DM) annihilation in the Galaxy, particularly for light DM candidates in the phenomenologically interesting O(10) GeV mass range. Especially from directions close to the Galactic Plane, the γ-ray spectrum is altered via two effects: directly, by the photons emitted in the bremsstrahlung process by energetic electrons which are among the DM annihilation byproducts; indirectly, by the modification of the same electron spectrum, due to the additional energy loss process in the diffusion-loss equation (e.g. the resulting inverse Compton emission is altered). We quantify the importance of the bremsstrahlung emission in the GeV energy range, showing that it is sometimes the dominant component of the γ-ray spectrum. We also find that, in regions in which bremsstrahlung dominates energy losses, the related γ-ray emission is only moderately sensitive to possible large variations in the gas density. Still, we stress that, for computing precise spectra in the (sub-)GeV range, it is important to obtain a reliable description of the Galaxy gas distribution as well as to compute self-consistently the γ-ray emission and the solution to the diffusion-loss equation. For example, these are crucial issues to quantify and interpret meaningfully γ-ray map 'residuals' in the inner Galaxy

  18. Bremsstrahlung: an experimentalists personal perspective on the post modern era

    International Nuclear Information System (INIS)

    In this brief review I will discuss the recent experimental work on the doubly differential cross section, i.e. the photon energy and angular distribution, for electron Bremsstrahlung from thin solid film and gas targets. Since the beginning of the modern era in the study of Bremsstrahlung with the publication of the 1971 paper by Ts eng and Pratt, Professor Pratt has been the dominant influence in Bremsstrahlung research. Most, if not all, experimental research during the modern era has been motivated by the interest in comparing data with the theory of Pratt and his coworkers. As Bremsstrahlung research has moved into its post modern era, new experiments with increasing precision are concentrating on determining under what conditions ordinary Bremsstrahlung theory needs to be supplemented by a contribution from polarization Bremsstrahlung. Efforts to improve the comparison of thin-target experiment with theory have also led to new experimental and modeling work on Bremsstrahlung from thick solid targets. Thick-target Bremsstrahlung is interesting in its own right, but we also want to understand it better since it is the ever-present background in the thin-target experiments and the limiting factor in the effort to distinguish the polarization contribution to the total Bremsstrahlung spectrum. Professor Pratt ushered in the modern era in Bremsstrahlung research and has recently guided the transition into the post modern era. It can be expected that he will continue to have a formative influence on the developments of Bremsstrahlung research into the foreseeable future.

  19. Z-dependence of external bremsstrahlung production

    International Nuclear Information System (INIS)

    The n constant which determines Z dependence of external bremsstrahlung (EB) production, in the empirical equation I=KNZsup(n)exp(-σsub(β)t) suggested by Mudhole, has been experimentally calculated using Ge(Li) solid-state detector and β-rays from 32P and compared with theory. It is established that the experimental result (n=1,98+-0.03) is in close agreement by the theory (n=2). (author)

  20. Modeling the bremsstrahlung emission from converters

    CERN Document Server

    Mirea, M; Clapier, F; Hassaïne, M; Ibrahim, F; Müller, A C; Pauwels, N; Proust, J; Verney, D; Antoni, R; Bourgeois, L; Kandri-Rody, S

    2001-01-01

    The bremsstrahlung angular and energy theoretical distributions delivered from W and UCx thick converters are reported. This study is focussed on initial kinetic energies of the electron beam included in the range 30-60 MeV, suitable for the production of large radiative yields able to induce the $^{238}$U fission. These results offer the possibility to evaluate the required shielding for a neutron rich nuclei source.

  1. Radiative corrections to pion-nucleus bremsstrahlung

    OpenAIRE

    Kaiser, N.(Physik Department T39, Technische Universität München, Garching, D-85747, Germany); Friedrich, J. M.

    2008-01-01

    We calculate the one-photon loop radiative corrections to virtual pion Compton scattering $\\pi^- \\gamma^* \\to \\pi^- \\gamma$, that subprocess which determines in the one-photon exchange approximation the pion-nucleus bremsstrahlung reaction $\\pi^- Z\\to \\pi^- Z \\gamma$. Ultraviolet and infrared divergencies of the loop integrals are both treated by dimensional regularization. Analytical expressions for the ${\\cal O}(\\alpha)$ corrections to the virtual Compton scattering amplitudes, $A(s,u,Q)$ a...

  2. Bremsstrahlung Radiation At a Vacuum Bubble Wall

    CERN Document Server

    Lee, Jae-Weon; Lee, Chul H; Jang, Ji-ho

    2007-01-01

    When charged particles collide with a vacuum bubble, they can radiate strong electromagnetic waves due to rapid deceleration. Owing to the energy loss of the particles by this bremsstrahlung radiation, there is a non-negligible damping pressure acting on the bubble wall even when thermal equilibrium is maintained. In the non-relativistic region, this pressure is proportional to the velocity of the wall and could have influenced the bubble dynamics in the early universe.

  3. The LPM effect in sequential bremsstrahlung

    CERN Document Server

    Arnold, Peter

    2015-01-01

    The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. We analyze the case when the coherence lengths of two consecutive splitting processes overlap, which is important for understanding corrections to standard treatments of the LPM effect in QCD. Previous authors have analyzed this problem in the case of overlapping double bremsstrahlung where at least one of the bremsstrahlung gluons is soft. Here we show how to generalize to include the case where both splittings are hard. A number of techniques must be developed, and so in this paper we simplify by (i) restricting attention to a subset of the interference effects, which we call the "crossed" diagrams, and (ii) working in the large-$N_c$ limit. We first develop some general formulas that could in principle be implemented numerically (with substantial difficulty). To make more analytic progress...

  4. Absolute determination of bremsstrahlung deposition (Hydra)

    International Nuclear Information System (INIS)

    A technique developed to measure electron energy deposition in metals has been applied to the determination of bremsstrahlung deposition. In this method a square-wave beam modulation is employed and the time-derivative of a calorimeter temperature is used to obtain the energy deposited. This paper presents the results of bremsstrahlung deposition measurements in gold and aluminum. Data are presented for dose to a material as a function of converter material, converter thickness, and angle of electron incidence for electron energies in the range from 0.2 to 1.0 MeV. In addition, measurements of dose as a function of calorimeter position as it was moved both laterally and axially with respect to the beam axis are reported. Utilizing the facility and technique developed to make these measurements, a thorough study of the bremsstrahlung measuring calorimeters used with the pulsed electron beam machine Hydra was accomplished. The goal of this study was to determine accurately the correction factor for the loading effect of the thermocouple wires. The loading correction factor was measured to be 1.72 with an uncertainty of +- 5 percent. This value should be used when determining true dose to gold with the standard Hydra calorimeters instead of the value of 1.5 obtained from data on Hydra, since there is a larger uncertainty in the latter value. (U.S.)

  5. Proton-proton bremsstrahlung at 280 MeV

    International Nuclear Information System (INIS)

    A proton-proton bremsstrahlung experiment has been carried out at TRIUMF using a 280-MeV polarized proton beam impinging on a liquid-hydrogen target. All three outgoing particles were detected: the higher-energy proton in a magnetic spectrometer, the lower-energy proton with plastic scintillators, and the photon in lead-glass Cherenkov detectors. The experiment shows the first unambiguous evidence for off-shell effects in the free nucleon-nucleon interaction, in that the analyzing powers disagree strongly with the predictions of the soft-photon approximation (which incorporates only on-shell information) but are consistent with the results of calculations using the Bonn and Paris potentials

  6. Thermal Bremsstrahlung Radiation in a Two-Temperature Plasma

    OpenAIRE

    Luo, Bin; Zhang, S. Nan

    2002-01-01

    In the normal one-temperature plasma the motion of ions is usually neglected when calculating the Bremsstrahlung radiation of the plasma. Here we calculate the Bremsstrahlung radiation of a two-temperature plasma by taking into account of the motion of ions. Our results show that the total radiation power is always lower if the motion of ions is considered. We also apply the two-temperature Bremsstrahlung radiation mechanism for an analytical Advection-Dominated Accretion Flow (ADAF) model; w...

  7. Pb isotopes induced Bremsstrahlung in bone, muscle and teeth

    International Nuclear Information System (INIS)

    The few isotopes of lead such as 210Pb, 211Pb, 212Pb, 213Pb, 214Pb and 215Pb are good beta emitters. These beta emitting Pb isotopes induces Bremsstrahlung radiation and could have different energies and intensities. The Bremsstrahlung yield is a function of two components namely internal Bremsstrahlung and external Bremsstrahlung. The intensity of external Bremsstrahlung (EB) largely depends on the energy of the emitted beta particles and atomic number of the surrounding matrix material. On the other hand, internal Bremsstrahlung component inherently depends on the interaction of the emitted beta particle with the nucleus of the source radionuclide itself. The shapes of Bremsstrahlung spectra are a basic ingredient in the understanding and quantification of beta-ray dosimetry. It is useful to have a convenient reference on the shapes of Bremsstrahlung spectra from various nuclides. It is important to study the radiation hazards of lead isotopes. Hence in the present work we have formulated the method to study the Bremsstrahlung dose induced by the lead isotopes in human bone, muscle and teeth

  8. Internal bremsstrahlung spectrum of 139Ce

    International Nuclear Information System (INIS)

    The internal bremsstrahlung spectrum which accompanies the electron capture decay of 139Ce to the first excited state of 139La has been measured in coincidence with the nuclear gamma ray which deexcites that state. The measured intensity above 42 keV is found to be (1.070±0.024) times that predicted by the recent calculations of Suriacute c et al. The QEC value is found to be 264.6±2.0 keV. copyright 1996 The American Physical Society

  9. Time evolution of endpoint energy of Bremsstrahlung spectra and ion production from an electron cyclotron resonance ion source

    Energy Technology Data Exchange (ETDEWEB)

    Tarvainen, Ollie [Los Alamos National Laboratory; Ropponen, Tommi [JYFL; Jones, Peter [JYFL; Kalvas, Taneli [JYFL

    2008-01-01

    Electron cyclotron resonance ion sources (ECRIS) are used to produce high charge state heavy ion beams for the use of nuclear and materials science, for instance. The most powerful ECR ion sources today are superconducting. One of the problems with superconducting ECR ion sources is the use of high radio frequency (RF) power which results in bremsstrahlung radiation adding an extra heat load to the cryostat. In order to understand the electron heating process and timescales in the ECR plasma, time evolution measurement of ECR bremsstrahlung was carried out. In the measurements JYFL 14 GHz ECRIS was operated in a pulsed mode and bremsstrahlung data from several hundred RF pulses was recorded. Time evolution of ion production was also studied and compared to one of the electron heating theories. To analyze the measurement data at C++ program was developed. Endpoint energies of the bremsstrahlung spectra as a function of axial magnetic field strength, pressure and RF power are presented and ion production timescales obtained from the measurements are compared to bremsstrahlung emission timescales and one of the stochastic heating theories.

  10. The Impact of Hot Electrons on X-ray Spectra: e-e Bremsstrahlung and κ Distributions

    Science.gov (United States)

    Smith, Randall K.; Cui, Xiaohong; Foster, Adam; Yuasa, Takayuki

    2016-06-01

    Shocks, turbulence, and winds all influence the electron velocity distribution in hot plasmas, exciting lower-energy electrons and generating a high-energy (typically power-law) tail. Sufficiently energetic electrons will emit via an electron-electron (e-e) bremsstrahlung, a process not previously included in the AtomDB. We have added this process and calculate the impact e-e bremsstrahlung has on the spectra from the post-shock regions of an accreting magnetic cataclysmic variable (CV). We find the contribution of e-e bremsstrahlung to the total spectra exceeds 10% at ~100 keV, with the total emissivity in the post-shock accretion stream differing by more than 10% at energies above 60 keV. More generally a Maxwellian with a power law tail, typically termed a κ distribution, can have significant effects on the line and continuum X-rays emitted. In addition to the e-e bremsstrahlung term, there will be effects due to the impact of the electrons on the charge state distribution and the collisional excitation rates. We use the ``Maxwellian decomposition'' approach as described in Hahn & Savin (2015) to generate the rate coefficients for a κ distributions based on the recently-released AtomDB v3.0 atomic database. These values are compared to exact calculations done for selected recombination and bremsstrahlung rates, and are also compared to results from the CHIANTI KAPPA package.

  11. Soft X-ray bremsstrahlung and recombination radiation

    International Nuclear Information System (INIS)

    This report contains the theoretical background and computer codes for the calculation of soft X-ray bremsstrahlung and recombination radiation. These calculations are then used to calculate the effective Z of a plasma from the measured enhancement of the continuum radiation over that of pure hydrogen bremsstrahlung

  12. Bremsstrahlung spectra from atoms and ions at low relativistic energies

    International Nuclear Information System (INIS)

    Analytic expressions for bremsstrahlung spectra from neutral atoms and ions, including the polarizational bremsstrahlung contribution in a stripped atom approximation, are developed for electron scattering at energies of 10-2000 keV. A modified Elwert factor and a simple higher Born correction are used for the Coulomb spectrum, with ordinary bremsstrahlung screening effects in ions and atoms adequately characterized in the non-relativistic Born approximation. In parallel with the development of this analytic description, new numerical results are obtained for ordinary bremsstrahlung from ions and from bare nuclei, appreciably extending the available data set which can be used to study dependences on element, ionicity, energy and the fraction of incident energy radiated. The accuracy of predictions with the analytic expressions is then determined by comparison with the full numerical relativistic partial-wave results for ordinary bremsstrahlung and with non-relativistic numerical results in the Born approximation or in partial waves for the polarizational amplitude. (author)

  13. Polarization of thermal bremsstrahlung emission due to electron pressure anisotropy

    Science.gov (United States)

    Komarov, S. V.; Khabibullin, I. I.; Churazov, E. M.; Schekochihin, A. A.

    2016-09-01

    Astrophysical plasmas are typically magnetized, with the Larmor radii of the charged particles many orders of magnitude smaller than their collisional mean free paths. The fundamental properties of such plasmas, e.g. conduction and viscosity, may depend on the instabilities driven by the anisotropy of the particle distribution functions and operating at scales comparable to the Larmor scales. We discuss a possibility that the pressure anisotropy of thermal electrons could produce polarization of thermal bremsstrahlung emission. In particular, we consider coherent large-scale motions in galaxy clusters to estimate the level of anisotropy driven by stretching of the magnetic-field lines by plasma flow and by heat fluxes associated with thermal gradients. Our estimate of the degree of polarization is ˜0.1 per cent at energies ≳kT. While this value is too low for the forthcoming generation of X-ray polarimeters, it is potentially an important proxy for the processes taking place at extremely small scales, which are impossible to resolve spatially. The absence of the effect at the predicted level may set a lower limit on the electron collisionality in the ICM. At the same time, the small value of the effect implies that it does not preclude the use of clusters as (unpolarized) calibration sources for X-ray polarimeters at this level of accuracy.

  14. Dynamical model for Pion-Nucleon Bremsstrahlung

    CERN Document Server

    Mariano, A V

    2000-01-01

    A dynamical model based on effective Lagrangians is proposed to describe the bremsstrahlung reaction $ \\pi N \\to \\pi N \\gamma$ at low energies. The $\\Delta(1232)$ degrees of freedom are incorporated in a way consistent with both, electromagnetic gauge invariance and invariance under contact transformations. The model also includes the initial and final state rescattering of hadrons via a T-matrix with off-shell effects. The $\\pi N \\gamma$ differential cross sections are calculated using three different T-matrix models and the results are compared with the soft photon approximation, and with experimental data. The aim of this analysis is to test the off-shell behavior of the different T-matrices under consideration.

  15. Internal bremsstrahlung endpoint energy of 54Mn

    International Nuclear Information System (INIS)

    For 54Mn there is a discrepancy between the QEC obtained from the endpoint energy of the internal bremsstrahlung (IB) spectrum which accompanies the electron capture decay (QEC=1353±8 keV) and that obtained from the accepted mass differences (QEC=1377±1 keV). This Q value is needed to deduce the partial-half life of the astrophysically interesting β- decay of 54Mn from the recently measured β+ partial half-life. To resolve this discrepancy, we have remeasured the endpoint energy of the IB spectrum, by recording coincidences between the IB and the 835-keV γ ray, both detected in Compton-suppressed Ge detectors. The QEC we deduce is 1379±8 keV, in agreement with the accepted mass differences. (c) 2000 The American Physical Society

  16. Exposure of bremsstrahlung from beta-emitting therapeutic radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Manjunatha, H.C. [Department of Physics, Bangalore University, Bangalore-560056, Karnataka (India)], E-mail: manjunathhc@rediffmail.com; Rudraswamy, B. [Department of Physics, Bangalore University, Bangalore-560056, Karnataka (India)

    2009-02-15

    There has been an increased interest in beta therapeutic nuclear medicine, which emits relatively high-energy (>1 MeV) {beta}-rays and the production in vivo of Bremsstrahlung sufficient for external imaging, the produced Bremsstrahlung radiation hazard warrants evaluation. The Bremsstrahlung dose from patient administered {beta}-ray emitted radionuclide has been calculated by extending the national council on Radiation Protection and measurement model of a point source in air to account for biologic elimination of activity. We have estimated the probability of bremsstrahlung production, specific Bremsstrahlung constant (defined by Zanzonico et al.) and activity (A{sub release}) in bone cortical, bone compact, different regions of tooth enamel (enamel dentin junction (EDJ), enamel middle surface, enamel inner surface), different regions of dentin (outer surface, middle surface, enamel dentin junction (EDJ)), soft tissue, lungs and skeleton for different therapeutic beta-emitting radionuclide. In the present calculations we have used modified atomic number (Z{sub mod}) defined for bremsstrahlung process. Proper localization and quantification of incorporated beta emitters in bone and tooth are possible, because Bremsstrahlung production is greater in bone and tooth than soft tissue due to their high modified atomic number (Z{sub mod}). Radionuclide therapy with pure {beta}-ray emitters emitted in bone, tooth, soft tissue, lungs and skeleton does not require medical confinement of patients for radiation protection.

  17. Bremsstrahlung dose of therapeutic beta nuclides in bone and muscle

    OpenAIRE

    Manjunatha, H. C.

    2013-01-01

    In the nuclear medicine, beta nuclides are released during the treatment. This beta interacts with bone and muscle and produces external Bremsstrahlung (EB) radiation. Present work formulated a new method to evaluate the EB spectrum and hence the Bremsstrahlung dose of therapeutic beta nuclides (Lu-177, Sr-90, Sm-153, I-153, Cs-137, Au-201, Dy-165, Mo-99, Sr-89, Fe-59, P-32, Ho-166, Sr-92, Re-188, Y-90, Pr-147, Co-60, K-42) in bone and muscle. The Bremsstrahlung yields of these beta nuclides ...

  18. Polarization Bremsstrahlung in collissions of fast ions with multiatomic targets

    CERN Document Server

    Amusia, M Ya

    2013-01-01

    We consider the processes of polarization bremsstrahlung in collisions of fast ions with linear chains consisting of isolated atoms. We obtained intensities and angular distributions of radiation spectra for arbitrary number of atoms in the chain. It appeared that interference in the photon radiation amplitudes lead to prominent variation of spectral angular distributions of polarization bremsstrahlung as compared to these distribuitions in collisions with an isolated atom. The mean loss of energy due to radiation or the so-called rediative friction is estimated. The results obtained permit standard generalization to the case of polarization bremsstrahlung in fast ion chanelling above surfaces an and in solid body.

  19. Meson exchange currents in neutron-proton bremsstrahlung

    International Nuclear Information System (INIS)

    Background: The meson exchange current (MEC) contribution is important in the neutron-proton bremsstrahlung process (npγ) when the two nucleon-scattering angles are small. However, our understanding of such effects is limited, and the reason why meson exchange current effects dominate the npγ cross section has not been thoroughly investigated. Purpose: The primary focus of this investigation is to understand the origin of the MEC contribution, to identify the leading MEC amplitudes, and to comprehend why these MEC amplitudes dominate the npγ cross sections. Method: We used a new method that combines the one-boson-exchange (OBE) approach with the soft-photon approach to define 10 different npγ amplitudes. These amplitudes are used to calculate npγ cross sections at 225 MeV for nucleon laboratory scattering angles lying between 12 deg. and 43 deg. The results of these calculations are then compared to investigate the meson exchange current effect in npγ. Results: (i) The OBE amplitude Mnpγ,μPS and the two-u-two-t special (TuTts) soft-photon amplitude Mnpγ,μTuTts predict quantitatively similar npγ cross sections. (ii) The MEC effect is found to be significant when the two nucleon-scattering angles are far from the elastic limit (45 deg.), but the effect is insignificant when the nucleon angles approach the elastic limit. (iii) The origin of the MEC effect and the leading MEC amplitudes have been identified in this investigation. Furthermore, the reason is now clear why the leading MEC amplitudes dominate the npγ cross section when the nucleon-scattering angles are small. (iv) The contribution from the anomalous magnetic moments of the proton and the neutron is confirmed to be negligibly small. (v) In general, the theoretical cross sections using the amplitude Mnpγ,μPS, or the amplitude Mnpγ,μTuTts, are consistent with the triple differential cross sections recently measured at the Los Alamos National Laboratory. However, there exists an unexplained

  20. The LPM effect in sequential bremsstrahlung 2: factorization

    CERN Document Server

    Arnold, Peter; Iqbal, Shahin

    2016-01-01

    The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. In this paper, we continue analysis of the case when the coherence lengths of two consecutive splitting processes overlap (which is important for understanding corrections to standard treatments of the LPM effect in QCD), avoiding soft-gluon approximations. In particular, this paper analyzes the subtle problem of how to precisely separate overlapping double splitting (e.g.\\ overlapping double bremsstrahlung) from the case of consecutive, independent bremsstrahlung (which is the case that would be implemented in a Monte Carlo simulation based solely on single splitting rates). As an example of the method, we consider the rate of real double gluon bremsstrahlung from an initial gluon with various simplifying assumptions (thick media; $\\hat q$ approximation; large $N_c$; and neglect for the mome...

  1. Bremsstrahlung spectra produced by kilovolt electron impact on thick targets

    International Nuclear Information System (INIS)

    Measurements of bremsstrahlung spectra generated by 5-25 keV electron impact on thick targets of aluminium, titanium, zirconium, molybdenum and tungsten are reported. The experimental data are compared with the simulation results of X-ray spectra obtained from the general-purpose Monte Carlo code PENELOPE, which implements accurate cross-sections for ordinary bremsstrahlung emission but disregards polarization bremsstrahlung. The agreement between the experimental and simulation results is satisfactory. This is in contrast with a recent study in which large discrepancies were observed between experimental and Monte Carlo simulation results. Our results provide evidence for the reliability of the combined choices of the interaction cross-sections and of the simulation algorithms implemented in PENELOPE for bremsstrahlung emission.

  2. Feasibility Studies of the Diffractive Bremsstrahlung Measurement at the LHC

    OpenAIRE

    J.J. Chwastowski; Czekierda, S.; Kycia, R.; Staszewski, R.(The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Poland); Turnau, J.; Trzebiński, M

    2016-01-01

    Feasibility studies of an observation of the exclusive diffractive bremsstrahlung in proton-proton scattering at the LHC are reported. A simplified approach to the photon and the scattered proton energy reconstruction is used. The background influence is discussed.

  3. Effect of bremsstrahlung radiation emission on fast electrons in plasmas

    OpenAIRE

    Embréus, Ola; Stahl, Adam; Fülöp, Tünde

    2016-01-01

    Bremsstrahlung radiation emission is an important energy loss mechanism for energetic electrons in plasmas. In this paper we investigate the effect of spontaneous bremsstrahlung emission on the momentum-space structure of the electron distribution, fully accounting for the emission of finite-energy photons. We find that electrons accelerated by electric fields can reach significantly higher energies than what is expected from energy-loss considerations. Furthermore, we show that the emission ...

  4. Calculation of the collimated bremsstrahlung flux from thin radiators

    International Nuclear Information System (INIS)

    A method is outlined for calculating the absolute flux of a bremsstrahlung beam created by passing an electron beam through thin radiators. Multiple scattering of the electron beam in the radiator and collimation of the bremsstrahlung flux are considered in this calculation. Separate measurements determine that this calculations has an absolute accuracy of 2.8% for an endpoint energy range from 120 to 360 MeV for a total radiator thickness of less than 0.012 radiation lengths. (orig.)

  5. Angular distribution of the bremsstrahlung emission during lower-hybrid current drive on PLT

    International Nuclear Information System (INIS)

    The bremsstrahlung emission from the PLT tokamak during lower-hybrid current drive has been measured as a function of angle between the magnetic field and the emission direction. The emission is peaked strongly in the forward direction, indicating a strong anisotropy of the electron-velocity distribution. The data demonstrate the existence of a nearly flat tail of the velocity distribution, which extends out to approximately 500 keV and which is interpreted as the plateau created by Landau damping of the lower-hybrid waves

  6. Sum rules for the polarization correlations in photoionization and bremsstrahlung

    Science.gov (United States)

    Pratt, R. H.; Müller, R. A.; Surzhykov, A.

    2016-05-01

    The polarization correlations in doubly differential cross sections are investigated for photoionization and ordinary bremsstrahlung. These correlations describe the polarization transfer between incident light and ejected photoelectrons as well as between an incoming electron beam and bremsstrahlung light, respectively. They are characterized by a set of seven real parameters Ci j. We show that the squares of these parameters are connected by simple "sum rules." These sum rules can be applied for both one-electron systems and also for atoms, if the latter are described within the independent particle approximation. In particular, they are exact in their simplest form (i) for the photoionization of K -, LI ,I I-, and MI ,I I-atomic shells, as well as (ii) for bremsstrahlung in which the electron is scattered into s1 /2 or p1 /2 states, as in the tip (bremsstrahlung) region. Detailed calculations are performed to verify the derived identities and to discuss their possible applications for the analysis of modern photoionization and bremsstrahlung experiments. In particular, we argue that the sum rules may help to determine the entire set of (significant) polarization correlations in the case when not all Ci j are available for experimental observation.

  7. Impulsive solar X-ray bursts. 3: Polarization and directivity of bremsstrahlung radiation from a beam of electrons directed toward the photosphere

    Science.gov (United States)

    Langer, S. H.; Petrosian, V.

    1976-01-01

    The spectrum, directivity and state of polarization is presented of the bremsstrahlung radiation expected from a beam of high energy electrons spiraling along radial magnetic field lines toward the photosphere. The results are used for calculation of the characteristics of the reflected plus direct flux.

  8. Bremsstrahlung source term estimation for high energy electron accelerators

    International Nuclear Information System (INIS)

    Thick target bremsstrahlung source term for 450 MeV and 550 MeV electrons are experimentally determined using booster synchrotron of Indus facility at Raja Ramanna Centre for Advanced Technology, Indore, India. The source term is also simulated using EGSnrc Monte Carlo code. Results from experiment and simulation are found to be in very good agreement. Based on the agreement between experimental and simulated data, the source term is determined up to 3000 MeV by simulation. The paper also describes the studies carried out on the variation of source term when a thin target is considered in place of a thick target, used in earlier studies. - Highlights: • Experimental determination of bremsstrahlung source term at 450 and 550 MeV electrons. • Monte Carlo calculations performed for validation of experimental data. • Thick and thin target bremsstrahlung source term is studied. • Brensstrahlung Source term is determined up to 3 GeV electron energies

  9. Electron collision effects on the bremsstrahlung emission in Lorentzian plasmas

    International Nuclear Information System (INIS)

    The electron-electron collision effects on the electron-ion bemsstranhlung process are investigated in warm Lorentzian plasmas. The effective electron-ion interaction potential is obtained by including the far-field terms caused by the electron-electron collisions with the effective Debye length in Lorentzian plasmas. The bremsstranhlung radiation cross section is obtained as a function of the electron energy, photon energy, collision frequency, spectral index, and Debye length using the Born approximation for the initial and final states of the projectile electron. It is shown that the non-Maxwellian character suppresses the bremsstrahlung radiation cross section. It is also shown that the electron-electron collision effect enhances the bremsstrahlung emission spectrum. In addition, the bremsstrahlung radiation cross section decreases with an increase of the plasma temperature. (author)

  10. The development of a high power bremsstrahlung radiator for the production of monochromatic X-rays

    International Nuclear Information System (INIS)

    An experimental setup for the production of monochromatic X-ray beams tunable in the energy region between 75 KeV and 700 KeV was built at our facility. The concept is based on monochromatization of a broad energy bremsstrahlung spectrum by Laue diffraction on a curved single crystal and by selection of the desired energy with an appropriate slit system, 10.45 meters behind the crystal. The bremsstrahlung spectrum is created when accelerated electrons from a high power 20 kW linac lose energy in a radiator. In this study, the radiator has been optimized for the creation of a bremsstrahlung spectrum suitable for monochromatization with a crystal. Monte-Carlo Simulations (using the BEAM-EGS4 code) of electrons incident with different energies on a radiator with varying composition (aluminum, carbon and tantalum) and thickness were carried out. Furthermore a study of the thermal properties of these materials when being exposed to a high power electron beam was done. This lead to the remarkable conclusion that a thin radiator composed of a low Z material should be used. This result is quite surprising as usually a high Z material is used for efficient transformation of charged particle energy to bremsstrahlung photons. A low Z radiator however will create a less divergent photon beam, leading to more photons on the effective surface area of the crystal. A set of radiators was designed to have an optimal configuration for different monochromatic beams needed. Because only a small fraction of the electrons are stopped in these thin radiators, a cleaning magnet and a beamstop need to be inserted in the setup. Due to the high power of the electron beam on the one hand and its divergency after traversing the radiator on the other, a special magnet system had to be designed to remove the electrons from the photon beam. This was done by means of Monte-Carlo simulations and a ray tracing program. Finally it was estimated that, when using this new setup, the intensity of the

  11. The Stonehenge technique. A method for aligning coherent bremsstrahlung radiators

    International Nuclear Information System (INIS)

    This paper describes a technique for the alignment of crystal radiators used to produce high energy, linearly polarized photons via coherent bremsstrahlung scattering at electron beam facilities. In these experiments the crystal is mounted on a goniometer which is used to adjust its orientation relative to the electron beam. The angles and equations which relate the crystal lattice, goniometer and electron beam direction are presented here, and the method of alignment is illustrated with data taken at MAMI (the Mainz microtron). A practical guide to setting up a coherent bremsstrahlung facility and installing new crystals using this technique is also included.

  12. Revisiting Bremsstrahlung emission associated with Light Dark Matter annihilations

    OpenAIRE

    Boehm, C; Uwer, P.

    2006-01-01

    We compute the single bremsstrahlung emission associated with the pair annihilation of spin-0 particles into electrons and positrons, via the t-channel exchange of a heavy fermion. We compare our result with the work of Beacom et al. . Unlike what is stated in the literature, we show that the Bremsstrahlung cross section is not necessarily given by the tree-level annihilation cross section (for a generalized kinematics) times a factor related to the emission of a soft photon. Such a factoriza...

  13. Muon bremsstrahlung and muonic pair production in air showers

    International Nuclear Information System (INIS)

    The objective of this work is to report on the modifications in air shower development due to muon bremsstrahlung and muonic pair production. In order to do that we have implemented new muon bremsstrahlung and muonic pair production procedures in the AIRES air shower simulation system, and have used it to simulate ultra high energy showers in different conditions. The influence of the mentioned processes in the global development of the air shower is important for primary particles of large zenith angles, while they do not introduce significant changes in the position of the shower maximum

  14. High-power bremsstrahlung sources for radiation sterilization

    International Nuclear Information System (INIS)

    A theoretical investigation has been made of the radiation processing rate that can be achieved using Bremsstrahlung radiation produced by electrons from an electrostatic accelerator. Computer calculations were made using experimentally measured angular distributions to calculate the spatial distribution of Bremsstrahlung produced by scanned electron beams of 4 and 5 MeV. The calculations take into account scan angle, scan height, and source-product distance to calculate the dose distribution in a homogeneous absorber of uniform density. Several conveyor configurations are examined in order to determine the optimum in terms of overall power efficiency for a given dose uniformity requirement. (author)

  15. Elastic photonuclear cross sections for bremsstrahlung from relativistic ions

    OpenAIRE

    Mikkelsen, R. E.; Sørensen, A H; Uggerhøj, U. I.

    2015-01-01

    In this paper, we provide a procedure to calculate the bremsstrahlung spectrum for virtually any relativistic bare ion with charge 6$e$ or beyond, $Z\\ge 6$, in ultraperipheral collisions with target nuclei. We apply the Weizs\\"{a}cker-Williams method of virtual quanta to model the effect of the distribution of nuclear constituents on the interaction of the ion with the radiation target. This leads to a bremsstrahlung spectrum peaking at $2\\gamma$ times the energy of the giant dipole resonance...

  16. Effect of bremsstrahlung radiation emission on fast electrons in plasmas

    CERN Document Server

    Embréus, Ola; Fülöp, Tünde

    2016-01-01

    Bremsstrahlung radiation emission is an important energy loss mechanism for energetic electrons in plasmas. In this paper we investigate the effect of spontaneous bremsstrahlung emission on the momentum-space structure of the electron distribution, fully accounting for the emission of finite-energy photons. We find that electrons accelerated by electric fields can reach significantly higher energies than what is expected from energy-loss considerations. Furthermore, we show that the emission of soft photons can contribute significantly to the dynamics of electrons with an anisotropic distribution.

  17. Electron-electron bremsstrahlung emission and the inference of electron flux spectra in solar flares

    OpenAIRE

    Kontar, E. P.; Emslie, A. G.; Massone, A. M.; Piana, M.; Brown, J.C.; Prato, M.

    2007-01-01

    Although both electron-ion and electron-electron bremsstrahlung contribute to the hard X-ray emission from solar flares, the latter is normally ignored. Such an omission is not justified at electron (and photon) energies above $\\sim 300$ keV, and inclusion of the additional electron-electron bremsstrahlung in general makes the electron spectrum required to produce a given hard X-ray spectrum steeper at high energies. Unlike electron-ion bremsstrahlung, electron-electron bremsstrahlung cannot ...

  18. Nuclear bremsstrahlung, a tool to study the free and in-medium NN interaction

    International Nuclear Information System (INIS)

    At the AGOR cyclotron of the KVI a series of bremsstrahlung measurements has been carried out with proton and α beams. The elementary bremsstrahlung process for real and virtual photons has been studied in the pp system. Coherent bremsstrahlung has been found in the α+p system. A strong quenching of bremsstrahlung is observed in the low-energy regime of the photon spectrum in p+nucleus reactions

  19. A detector for use in high energy bremsstrahlung shielding studies

    International Nuclear Information System (INIS)

    The design, development and calibration of a detector based on the principle of the Moxon-Rae detector is discussed. It is ideally suited to the measurement of the energy fluence of photons transmitted through a thick shield which has been irradiated with high energy bremsstrahlung. The detection sensitivity is 104 to 105 times that of the P2 ion chamber

  20. Spectra and rates of bremsstrahlung neutrino emission in stars

    CERN Document Server

    Guo, Gang

    2016-01-01

    We calculate the energy-differential rate for neutrino emission from electron-nucleus bremsstrahlung in stellar interiors taking into account the effects of electron screening and ionic correlations. We compare the energy-differential and the net rates, as well as the average $\\bar{\

  1. Exact Bremsstrahlung Function in N=2 Superconformal Field Theories.

    Science.gov (United States)

    Fiol, Bartomeu; Gerchkovitz, Efrat; Komargodski, Zohar

    2016-02-26

    We propose an exact formula for the energy radiated by an accelerating quark in N=2 superconformal theories in four dimensions. This formula reproduces the known bremsstrahlung function for N=4 theories and provides a prediction for all the perturbative and instanton corrections in N=2 theories. We perform a perturbative check of our proposal up to three loops. PMID:26967407

  2. Observation of the Muon Inner Bremsstrahlung at LEP1

    CERN Document Server

    Abdallah, J; Adam, W; Adzic, P; Albrecht, T; Alemany-Fernandez, R; Allmendinger, T; Allport, P P; Amaldi, U; Amapane, N; Amato, S; Anashkin, E; Andreazza, A; Andringa, S; Anjos, N; Antilogus, P; Apel, W D; Arnoud, Y; Ask, S; Åsman, B; Augustin, J E; Augustinus, A; Baillon, P; Ballestrero, A; Bambade, P; Barbier, R; Bardin, D; Barker, G J; Baroncelli, A; Battaglia, M; Baubillier, M; Becks, K H; Begalli, M; Behrmann, A; Ben-Haim, E; Benekos, N; Benvenuti, A; Bérat, C; Berggren, M; Bertrand, D; Besançon, M; Besson, N; Bloch, D; Blom, M; Bluj, M; Bonesini, M; Boonekamp, M; Booth, P S L; Borisov, G; Botner, O; Bouquet, B; Bowcock, T J V; Boyko, I; Bracko, M; Brenner, R; Brodet, E; Brückman, P; Brunet, J M; Buschbeck, B; Buschmann, P; Calvi, M; Camporesi, T; Canale, V; Carena, F; Castro, N; Cavallo, F; Chapkin, M; Charpentier, P; Checchia, P; Chierici, R; Shlyapnikov, P; Chudoba, J; Chung, S U; Cieslik, K; Collins, P; Contri, R; Cosme, G; Cossutti, F; Costa, M J; Crennell, D J; Cuevas-Maestro, J; D'Hondt, J; Da Silva, T; Da Silva, W; Della Ricca, G; De Angelis, A; de Boer, Wim; De Clercq, C; De Lotto, B; De Maria, N; De Min, A; De Paula, L; Di Ciaccio, L; Di Simone, A; Doroba, K; Drees, J; Eigen, G; Ekelöf, T J C; Ellert, M; Elsing, M; Espirito-Santo, M C; Fanourakis, G K; Fassouliotis, D; Feindt, M; Fernández, J; Ferrer, A; Ferro, F; Flagmeyer, U; Föth, H; Fokitis, E; Fulda-Quenzer, F; Fuster, J; Gandelman, M; García, C; Gavillet, P; Gazis, E; Gokieli, R; Golob, B; Gómez-Ceballos, G; Gonçalves, P; Graziani, E; Grosdidier, G; Grzelak, K; Guy, J; Haag, C; Hallgren, A; Hamacher, K; Hamilton, K; Haug, S; Hauler, F; Hedberg, V; Hennecke, M; Herr, H; Hoffman, J; Holmgren, S O; Holt, P J; Houlden, M A; Jackson, J N; Jarlskog, G; Jarry, P; Jeans, D; Johansson, E K; Jonsson, P; Joram, C; Jungermann, L; Kapusta, F; Katsanevas, S; Kokkinias, P; Leinonen, L; Katsoufis, E; Kernel, G; Kersevan, B P; Krumshtein, Z; Lesiak, T; Kerzel, U; Liebig, W; King, B T; Lamsa, J; Liko, D; Kjaer, N J; Leder, G; Kluit, P; Kourkoumelis, C; Leitner, R; Kuznetsov, O; Kucharczyk, M; Ledroit, F; Lopes, J H; Lemonne, J; Lepeltier, V; Lipniacka, A; López, J M; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J; Malek, A; Maltezos, S; Mandl, F; Marco, J; Marco, R; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martínez-Rivero, C; Masik, J; Mastroyiannopoulos, N; Matorras, F; Matteuzzi, C; Mazzucato, F; Mazzucato, M; McNulty, R; Meroni, C; Migliore, E; Mitaroff, W A; Mjörnmark, U; Moa, T; Moch, M; Mönig, K; Monge, R; Montenegro, J; Moraes, D; Moreno, S; Morettini, P; Müller, U; Münich, K; Mulders, M; Mundim, L; Murray, W; Muryn, B; Myatt, G; Myklebust, T; Paganoni, M; Nassiakou, M; Paiano, S; Navarria, F; Nawrocki, K; Nicolaidou, R; Nikolenko, M; Ouraou, A; Parkes, C; Oblakowska-Mucha, A; Oyanguren, A; Obraztsov, V F; Olshevski, A; Palacios, J P; Onofre, A; Palka, H; Orava, R; Österberg, K; Pape, L; Papadopoulou, T D; Parodi, F; Parzefall, U; Passeri, A; Passon, O; Peralta, L; Perepelitsa, V; Perrotta, A; Petrolini, A; Piedra, J; Pieri, L; Pierre, F; Pimenta, M; Piotto, E; Podobnik, T; Poireau, V; Pol, M E; Polok, G; Pozdnyakov, V; Pukhaeva, N; Pullia, A; Rames, J; Read, A; Rebecchi, P; Rehn, J; Reid, D; Reinhardt, R; Renton, P B; Richard, F; Rídky, J; Rivero, M; Rodríguez, D; Romero, A; Ronchese, P; Roudeau, P; Rovelli, T; Ruhlmann-Kleider, V; Ryabtchikov, D; Sadovskii, A; Salmi, L; Salt, J; Sander, C; Savoy-Navarro, A; Schwickerath, U; Sekulin, R; Siebel, M; Sisakian, A; Smadja, G; Smirnova, O; Sokolov, A; Sopczak, A; Sosnowski, R; Spassoff, Tz; Stanitzki, M; Stocchi, A; Strauss, J; Stugu, B; Szczekowski, M; Szeptycka, M; Szumlak, T; Tabarelli de Fatis, T; Tegenfeldt, F; Timmermans, J; Tkatchev, L; Tobin, M; Todorovova, S; Tomé, B; Tonazzo, A; Tortosa, P; Travnicek, P; Treille, D; Tristram, G; Trochimczuk, M; Troncon, C; Turluer, M L; Tyapkin, I A; Tyapkin, P; Tzamarias, S; Uvarov, V; Valenti, G; van Dam, P; Van Eldik, J; Van Remortel, N; Van Vulpen, I; Vegni, G; Veloso, F; Venus, W; Verdier, P; Verzi, V; Vilanova, D; Vitale, L; Vrba, V; Wahlen, H; Washbrook, A J; Weiser, C; Wicke, D; Wickens, J; Wilkinson, G; Winter, M; Witek, M; Yushchenko, O; Zalewska-Bak, A; Zalewski, P; Zavrtanik, D; Zhuravlov, V; Zimin, N I; Zintchenko, A; Zupan, M

    2008-01-01

    Muon bremsstrahlung photons converted in front of the DELPHI main tracker (TPC) in dimuon events at LEP1 were studied in two photon kinematic ranges: 0.2 < E_gamma <= 1 GeV and transverse momentum with respect to the parent muon p_T < 40 MeV/c, and 1 < E_gamma <= 10 GeV and p_T < 80 MeV/c . A good agreement of the observed photon rate with predictions from QED for the muon inner bremsstrahlung was found, contrary to the anomalous soft photon excess that has been observed recently in hadronic Z^0 decays. The obtained ratios of the observed signal to the predicted level of the muon bremsstrahlung are 1.06 +/- 0.12 +/- 0.07 in the photon energy range 0.2 < E_gamma <= 1 GeV and 1.04 +/- 0.09 +/- 0.12 in the photon energy range 1 < E_gamma <= 10 GeV. The bremsstrahlung dead cone is observed for the first time in the direct photon production at LEP.

  3. Feasibility Studies of Exclusive Diffractive Bremsstrahlung Measurement at RHIC Energies

    OpenAIRE

    Chwastowski, Janusz; Cyz, Antoni; Fulek, Łukasz; Kycia, Radosław; Pawlik, Bogdan; Sikora, Rafał; Turnau, Jacek

    2015-01-01

    Feasibility studies of an observation of the exclusive diffractive bremsstrahlung at RHIC at $\\sqrt{s} = 200$~GeV and at $\\sqrt{s} = 500$~GeV are reported. A simplified approach to the photon and the scattered proton energy reconstruction is used. Influence of possible backgrounds is discussed.

  4. Neutrino signals from electroweak bremsstrahlung in solar WIMP annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Nicole F.; Brennan, Amelia J.; Jacques, Thomas D., E-mail: n.bell@unimelb.edu.au, E-mail: a.brennan@pgrad.unimelb.edu.au, E-mail: thomas.jacques@asu.edu [ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics, The University of Melbourne, Victoria 3010 (Australia)

    2012-10-01

    Bremsstrahlung of W and Z gauge bosons, or photons, can be an important dark matter annihilation channel. In many popular models in which the annihilation to a pair of light fermions is helicity suppressed, these bremsstrahlung processes can lift the suppression and thus become the dominant annihilation channels. The resulting dark matter annihilation products contain a large, energetic, neutrino component. We consider solar WIMP annihilation in the case where electroweak bremsstrahlung dominates, and calculate the resulting neutrino spectra. The flux consists of primary neutrinos produced in processes such as χχ→ν-bar νZ and χχ→ν-bar lW, and secondary neutrinos produced via the decays of gauge bosons and charged leptons. After dealing with the neutrino propagation and flavour evolution in the Sun, we consider the prospects for detection in neutrino experiments on Earth. We compare our signal with that for annihilation to W{sup +}W{sup −}, and show that, for a given annihilation rate, the bremsstrahlung annihilation channel produces a larger signal by a factor of a few.

  5. Proton-proton bremsstrahlung towards the elastic limit

    International Nuclear Information System (INIS)

    In oder to study proton-proton bremsstrahlung moving towards the elastic limit, a detection system, consisting of Plastic-ball and SALAD, was set up and an experiment at 190 MeV incident beam energy was performed. Here, the experimental setup and the data analysis procedure along with some results obtained in the measurement are discussed

  6. Constructing the nuclear caloric curve from thermal bremsstrahlung

    NARCIS (Netherlands)

    Ortega, R

    2004-01-01

    The behavior of the emission of thermal bremsstrahlung with the reaction centrality has been studied in Xe-121 + Sn-nat reactions at 50A MeV. A thermal hard photon component is present along the measured impact parameter range (0.1 less than or equal to b/b(max) less than or equal to 0.6) showing th

  7. Bremsstrahlung Pair Production In Relativistic Heavy Ion Collision

    OpenAIRE

    Meier, H; Hencken, K.; Trautmann, D.; Baur, G.

    1997-01-01

    We calculate production of electron- and muon-pairs by the bremsstrahlung process in hadron collisions and compare it with the dominant two-photon process. Results for the total cross section are given for proton-proton and heavy-ion collisions at energies of the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC).

  8. Infrared phenomena in quantum electrodynamics : II. Bremsstrahlung and compton scattering

    NARCIS (Netherlands)

    Haeringen, W. van

    1960-01-01

    The infrared aspects of quantum electrodynamics are discussed by treating two examples of scattering processes, bremsstrahlung and Compton scattering. As in the previous paper one uses a non-covariant diagram technique which gives very clear insight in the cancelling of infrared divergences between

  9. Initial studies of Bremsstrahlung energy deposition in small-bore superconducting undulator structures in linac environments

    Energy Technology Data Exchange (ETDEWEB)

    Cremer, T.; Tatchyn, R. [Stanford Univ., CA (United States)

    1995-12-31

    One of the more promising technologies for developing minimal-length insertion devices for linac-driven, single-pass Free Electron Lasers (FELs) operating in the x-ray range is based on the use of superconducting (SC) materials. In recent FEL simulations, for example, a bifilar helical SC device with a 2 cm period and 1.8 T field was found to require a 30 m saturation length for operation at 1.5{Angstrom} on a 15 GeV linac, more than 40% shorter than an alternative hybrid/permanent magnet (hybrid/PM) undulator. AT the same time, however, SC technology is known to present characteristic difficulties for insertion device design, both in engineering detail and in operation. Perhaps the most critical problem, as observed, e.g., by Madey and co-workers in their initial FEL experiments, was the frequent quenching induced by scattered electrons upstream of their (bifilar) device. Postulating that this quenching was precipitated by directly-scattered or bremsstrahlung-induced particle energy deposited into the SC material or into material contiguous with it, the importance of numerical and experimental characterizations of this phenomenon for linac-based, user-facility SC undulator design becomes evident. In this paper we discuss selected prior experimental results and report on initial EGS4 code studies of scattered and bremsstrahlung induced particle energy deposition into SC structures with geometries comparable to a small-bore bifilar helical undulator.

  10. SU-E-E-08: Applications of the Quantization of Coupled Circuits in Radiation Physics (design of Klystron, Bremsstrahlung, Synchrotron)

    International Nuclear Information System (INIS)

    Purpose: During the past decade the quantization of coupled/forced electromagnetic circuits with or without Ohm’s resistance has gained the subject of some fundamental studies, since even problems of quantum electrodynamics can be solved in an elegant manner, e.g. the creation of quantized electromagnetic fields. In this communication, we shall use these principles to describe optimization procedures in the design of klystrons, synchrotron irradiation and high energy bremsstrahlung. Methods: The base is the Hamiltonian of an electromagnetic circuit and the extension to coupled circuits, which allow the study of symmetries and perturbed symmetries in a very apparent way (SU2, SU3, SU4). The introduction resistance and forced oscillators for the emission and absorption in such coupled systems provides characteristic resonance conditions, and atomic orbitals can be described by that. The extension to virtual orbitals leads to creation of bremsstrahlung, if the incident electron (velocity v nearly c) is described by a current, which is associated with its inductivitance and the virtual orbital to the charge distribution (capacitance). Coupled systems with forced oscillators can be used to amplify drastically the resonance frequencies to describe klystrons and synchrotron radiation. Results: The cross-section formula for bremsstrahlung given by the propagator method of Feynman can readily be derived. The design of klystrons and synchrotrons inclusive the radiation outcome can be described and optimized by the determination of the mutual magnetic couplings between the oscillators induced by the currents. Conclusions: The presented methods of quantization of circuits inclusive resistance provide rather a straightforward way to understand complex technical processes such as creation of bremsstrahlung or creation of radiation by klystrons and synchrotrons. They can either be used for optimization procedures and, last but not least, for pedagogical purposes with regard to

  11. Bremsstrahlung during $\\alpha$-decay: quantum multipolar model

    CERN Document Server

    Maydanyuk, Sergei P

    2008-01-01

    In this paper the improved multipolar model of bremsstrahlung accompanied the $\\alpha$-decay is presented. The angular formalism of calculations of the matrix elements, being enough complicated component of the model, is stated in details. A new definition of the angular (differential) probability of the photon emission in the $\\alpha$-decay is proposed where direction of motion of the $\\alpha$-particle outside (with its tunneling inside barrier) is defined on the basis of angular distribution of its spacial wave function. In such approach, the model gives values of the angular probability of the photons emission in absolute scale, without its normalization on experimental data. Effectiveness of the proposed definition and accuracy of the spectra calculations of the bremsstrahlung spectra are analyzed in their comparison with experimental data for the $^{210}{\\rm Po}$, $^{214}{\\rm Po}$, $^{226}{\\rm Ra}$ and $^{244}{\\rm Cm}$ nuclei, and for some other nuclei predictions are performed (in absolute scale). With ...

  12. The LPM effect in sequential bremsstrahlung: 4-gluon vertices

    CERN Document Server

    Arnold, Peter; Iqbal, Shahin

    2016-01-01

    The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. In this paper, we continue study of the case when the coherence lengths of two consecutive splitting processes overlap (which is important for understanding corrections to standard treatments of the LPM effect in QCD), avoiding soft-gluon approximations. In particular, this paper completes the calculation of the rate for real double gluon bremsstrahlung from an initial gluon with various simplifying assumptions (thick media; $\\hat q$ approximation; and large $N_c$) by now including processes involving 4-gluon vertices.

  13. Axial coherent bremsstrahlung of type A in a diamond crystal

    International Nuclear Information System (INIS)

    Axial coherent bremsstrahlung of type A (ACBA) has not been intensively investigated either theoretically or experimentally. Making use of the many-beam (two-dimensional quantum treatment) formalism for transversely bound electrons moving through crystal lattices, we have computed ACBA spectra for 17 MeV electrons passing through a 10 μm thick diamond (C) crystal. We found that the momentum transfer occurs in the plane perpendicular to the axis of interest. Only momentum transfers along the scan direction (electron transverse momentum direction) result in a photon emission in the forward direction. Two different scans have shown that the energies of the coherent bremsstrahlung peaks depend strongly on the direction of the electron transverse momentum. We also present a comparison of the first order Born approximation and the many-beam formalism

  14. Δ-excitation and exchange corrections for NN-Bremsstrahlung

    International Nuclear Information System (INIS)

    The role of the relativistic amplitudes for a number of O(k) processes usually neglected in potential model calculations of NN-bremsstrahlung is investigated. In particular, we consider the Δ-excitation pole contributions related to the one-pion and one-rho exchange and in addition include the exchange contributions induced by the radiative w, p → πγ decays. The contributions are calculated from relativistic Born amplitudes fitted to Δ-production and absorption data in the energy range up to 1 GeV and then used to supplement potential model and soft photon calculations for nucleon-nucleon bremsstrahlung. The effects on N N γ-observables, although moderate in general, are found to be important in some kinematic domains. (author). 39 refs., 1 tab., 6 figs

  15. Bremsstrahlung and fluorescence in PMTs causing fast afterpulses

    International Nuclear Information System (INIS)

    LENA (Low Energy Neutrino Astronomy) is a next-generation liquid-scintillator neutrino detector with 50kt target mass. The broad spectrum of physics goals ranging from the sub-MeV to the GeV regime sets high demands on the photosensors. Currently, photomultipliers (PMTs) are the sensor of choice. However, besides detecting photons, they also emit light through bremsstrahlung or fluorescence induced by the electron avalanche in the dynode chain, which can produce further pulses in the same PMT or adjacent sensors. In order to study these effects and their connection to afterpulses occurring in the PMT, measurements of light emission and fast afterpulses have been carried through in collaboration with the CTA project. Both bremsstrahlung and fluorescence have been observed, with the first also being the origin of a type of fast afterpulses.

  16. Distributed converter for high-brightness bremsstrahlung generation

    International Nuclear Information System (INIS)

    The novel type of the converter to transform a high-density electron beam into bremsstrahlung has been developed and investigated. To increase the thermal stability of the converter by means of a growth of the heat-exchange effectiveness in the area of the bremsstrahlung generation a braking media has been performed as the shot evenly distributed in the cooling water. The results of the computer simulation, thermophysical analysis and experimental study of the converter version on the basis of Pb shot are represented. The possibility of essential increase of the permissible electron beam density as well as reduction of the induced activity and water discharge in comparison with plate- type converter from tantalum is shown.

  17. K shell parameters of some lanthanide elements using bremsstrahlung

    International Nuclear Information System (INIS)

    The spectrum of external bremsstrahlung (EB) transmitted through Tb and Ho is measured using a HPGe detector spectrometer. A sudden drop in transmitted intensity at K shell binding energy has been used to determine the K shell photoelectric parameters. The unwanted characteristic K x-ray photons generated just below the K edge has been avoided by carrying out a separate experiment in the same geometry. The measured values of K shell parameters have been compared with FFAST values. - Highlights: • Bremsstrahlung attenuation in Tb and Ho targets is measured. • At K edge a sharp decrease in intensity is used to determine the K shell parameters. • The K x-ray photons appear just below the K edge hinders the precise measurement. • This hindrance is avoided using monochromatic gamma source. • Measured values are compared with those obtained from FFAST tabulations

  18. Cross sections for bremsstrahlung production and electron-impact ionization

    International Nuclear Information System (INIS)

    Electron transport codes require extensive information on the cross sections that govern electron interactions with the atoms that make up the medium. These processes include bremsstrahlung production in the atomic field, excitation and ionization of atomic electrons, and elastic scattering by screened atomic nuclei. These fundamental processes are of basic interest in many fields, but their inclusion in general purpose Monte Carlo transport codes imposes the requirement that reasonably accurate cross-section data be available over a very wide range of energies and for virtually any material. In this chapter, the author discusses two of these processes: bremsstrahlung production and electron-impact ionization. Both of these interactions result in the production of secondary radiations that can be important in radiation transport calculations

  19. Reconstruction of 12 MV bremsstrahlung spectra from measured transmission data

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Transmission data for 12 MV bremsstrahlung beams produced by the process for continuous-pulsed 12 MV electrons coming from a linear accelerator hitting a 1.2mm thick plane tantalum target have been acquired with a combination of iron and Telfon attenuators. Two solid state dosimeters with LiF-TLD material surrounded Telfon were used as detectors. It has been checked that the experimental system achieves reasonably narrow-beam geometry by Monte Carlo simulations. From these transmission data, the original energy photon spectrum has been reconstructed using the iterative least-squares technique and compared with the spectrum calculated with Monte Carlo code system EGSnrc. The comparison shows that the numerical technique for analysis of transmission data can represent 12 MV bremsstrahlung spectrum acceptably well. The purpose of our work is to provide an effective way to reconstruct an unknown photon spectrum with high energy component and prove the correctness of this way.

  20. Axial coherent bremsstrahlung of type A in a diamond crystal

    Energy Technology Data Exchange (ETDEWEB)

    Chouffani, K. E-mail: khalid@athena.physics.isu.edu; Endo, I.; Ueberall, H

    2003-01-01

    Axial coherent bremsstrahlung of type A (ACBA) has not been intensively investigated either theoretically or experimentally. Making use of the many-beam (two-dimensional quantum treatment) formalism for transversely bound electrons moving through crystal lattices, we have computed ACBA spectra for 17 MeV electrons passing through a 10 {mu}m thick diamond (C) crystal. We found that the momentum transfer occurs in the plane perpendicular to the axis of interest. Only momentum transfers along the scan direction (electron transverse momentum direction) result in a photon emission in the forward direction. Two different scans have shown that the energies of the coherent bremsstrahlung peaks depend strongly on the direction of the electron transverse momentum. We also present a comparison of the first order Born approximation and the many-beam formalism.

  1. PIXE spectrum analysis taking into account bremsstrahlung spectra

    International Nuclear Information System (INIS)

    Continuous background appearing over the wide region of X-ray energy in the PIXE spectrum is very troublesome presence in the peak fitting. In the usual manner, the spectrum of continuous background is predicted as a function of polynomial and is subtracted from the X-ray spectrum. However, the parameters of the polynomial are determined with difficulty in the case that the continuous background exists under many peaks of characteristic X-rays. We calculated the production cross sections of continuous X-rays for several elements on the basis of the theories of quasi-free electron bremsstrahlung (QFEB), secondary electron bremsstrahlung (SEB) and atomic bremsstrahlung (AB), and obtained the continuous X-ray spectrum as a function of atomic number and X-ray energy. X-ray spectra of a standard sample and of a bovine liver sample were analyzed by a pattern analysis method assuming the reference spectra consisting of characteristic X-rays and continuous X-rays for each element. The results of analysis are quite satisfactory. By the present method, the PIXE spectra can be analyzed under little influence of the background subtraction, and it enables us a full auto-analysis of PIXE spectrum

  2. Cherenkov radiation versus Bremsstrahlung in the Tamm problem

    International Nuclear Information System (INIS)

    The charge motion in medium on a finite space interval is considered. We analyze recent alternative attempts to interpret the radiation described by the Tamm formula as an interference of two instantaneous accelerations arising at the beginning and termination of motion. Exact solution of the Tamm problem in the time representation shows that in some time interval only the Bremsstrahlung shock wave associated with the beginning of motion and the Cherenkov shock wave exist, and there is no Bremsstrahlung shock wave associated with the end of motion. This proves that in the time representation the Cherenkov radiation is not necessarily related to the interference of initial and final Bremsstrahlung shock waves. In the spectral representation, we consider the motion consisting of accelerated, decelerated, and uniform parts. Analytic formulae are obtained describing electromagnetic fields and radiation intensities corresponding to this motion. Approximating the instantaneous acceleration in the original Tamm problem by the acceleration on a finite path and then tending its length to zero, we prove that the radiation intensity produced on the accelerated part of the charge trajectory also tends to zero (despite the infinite value of acceleration in this limit). This means that in the original Tamm problem the instantaneous acceleration and deceleration do not contribute to the radiation intensity (as it is usually believed). It seems that only the combined consideration of the Tamm problem in the time and spectral representations shows that the above-mentioned alternative interpretation of the Cherenkov relation fails

  3. Measurement of the mean ionic charge on Tore supra by visible bremsstrahlung radiation

    International Nuclear Information System (INIS)

    The effective plasma charge Zeff (proportional to plasma impurity ratio) is of prime importance for controlled fusion by magnetic confinement because it is involved for plasma ignition. From bremsstrahlung radiation theory in the visible part of the spectrum it is shown how effective charge in the plasma is deduced. A validity criterion is established from experiments (radiation at λ = 5235 A) to obtain Zeff profile and error estimation. This profile allows the calculation of resistivity profiles from different theories which are compared to a magnetohydrodynamic code. Calculation time is reduced by a fast analysis method from global parameters given time evolution of Zeff. This last measurement is essentially used for interpretation of experimental results of the Tore Supra physical program

  4. Bremsstrahlung of Fast Charged Particles on Clusters in a Wide Spectral Range

    International Nuclear Information System (INIS)

    Within the framework of the first Born approximation and a simple model of the structural factor, the bremsstrahlung of fast charged particles on polyatomic clusters is calculated and analyzed with regard to the polarization mechanism in a wide spectral range including a domain of high frequencies. The role of cooperative phenomena in the static and polarization channels of bremsstrahlung is investigated. It is established that these phenomena, being negligible for static bremsstrahlung, substantially influence the polarization bremsstrahlung. It is shown that the constructive interference between the contributions of the atoms of a cluster to the polarization bremsstrahlung substantially increases its intensity and changes its dependence on the basic parameters of the problem compared with the case of bremsstrahlung on an isolated atom

  5. Bremsstrahlung of fast charged particles when scattering on clusters in wide spectral range

    International Nuclear Information System (INIS)

    Within the framework of the first Born approximation and a simple model of the structural factor, the bremsstrahlung of fast charged particles on polyatomic clusters is calculated and analyzed with regard to the polarization mechanism in a wide spectral range including a domain of high frequencies. The role of cooperative phenomena in the static and polarization channels of bremsstrahlung is investigated. It is established that these phenomena, being negligible for static bremsstrahlung, substantially influence the polarization bremsstrahlung. It is shown that the constructive interference between the contributions of the atoms of a cluster to the polarization bremsstrahlung substantially increases its intensity and changes its dependence on the basic parameters of the problem compared with the case of bremsstrahlung on an isolated atom

  6. Irradiation effect on zooplankton eggs applied by bremsstrahlung induced from pulsed intense electron beam

    International Nuclear Information System (INIS)

    We have considered an irradiation effect on zooplankton eggs applied by bremsstrahlung induced from pulsed intense electron beam. Zooplankton eggs about 200 have been successfully inactivated using a bremsstrahlung at 3 kGy. We found that 63.9% of zooplankton eggs are inactivated by bremsstrahlung irradiation. It was the increase of 30 points in comparisons with 33.3% of zooplankton eggs inactivated for non-irradiation case. (author)

  7. Usefulness of Bremsstrahlung Images after Intra arterial Y 90 Resin Microphere Radioembolization for Hepatic Tumors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Chul; Kim, Wun Hwan; Um, Soon Ho; Seo, Yeon Seok; Park, Eun Kyung; Oh, Sun Young; Han, You Mie [Korea Univ. Anam Hospital, Seoul (Korea, Republic of); Choe, Jae Gol [Hallym Univ. Hangang Secred Heart Hospital, Seoul (Korea, Republic of)

    2011-03-15

    Y 90 resin microsphere radioembolization is used to treat inoperable hepatic tumors. After injection of Y 90 resin microsphere, the only method to visualize the distribution of Y 90 is the scintigraphic imaging of bremsstrahlung radiation. The purpose of this study was to evaluate the characteristics and usefulness of bremsstrahlung imaging in Y 90 resin microsphere treatment. Twenty patients (22 administrations) underwent intra arterial Y 90 resin microsphere treatment. For pretreatment planning, images of Tc 99m albumin macroag gregate (MAA) arterial injection and hepatic contrast angiography were obtained. Post treatment bremsstrahlung images were taken and compared with pre treatment images. The extrahepatic activity was evaluated on bremsstrahlung images. To correlate the size and vascularity of the tumors with tumor visualization on bremsstrahlung images, the individual tumors were grouped according to visualization on each image and compared with one another by size and tumor to normal ratio. All post therapeutic bremsstrahlung images showed similar contours of the liver with pre treatment angiography. No extrahepatic activity was seen in all cases. The visualized tumors on bremsstrahlung images were significantly larger than the non visualized tumors on bremsstrahlung images were significantly higher than those of the non visualized tumors. Bremsstrahlung images after intra arterial Y 90 resin microsphere treatment are useful in evaluating the intrahepatic distribution of radioisotope and detecting possible extrahepatic activity.

  8. Internal bremsstrahlung signatures in light of direct dark matter searches

    International Nuclear Information System (INIS)

    Although proposed long ago, the search for internal bremsstrahlung signatures has only recently been made possible by the excellent energy resolution of ground-based and satellite-borne gamma-ray instruments. Here, we investigate thoroughly the current status of internal bremsstrahlung searches in light of the results of direct dark matter searches and in the framework of a minimal mass-degenerate scenario consisting of a Majorana dark matter particle that couples to a fermion and a scalar via a Yukawa coupling. The upper limits on the annihilation cross section set by Fermi-LAT and H.E.S.S. extend uninterrupted from tens of GeV up to tens of TeV and are rather insensitive to the mass degeneracy in the particle physics model. In contrast, direct searches are best in the moderate to low mass splitting regime, where XENON100 limits overshadow Fermi-LAT and H.E.S.S. up to TeV masses if dark matter couples to one of the light quarks. In our minimal scenario we examine carefully the prospects for GAMMA-400, CTA and XENON1T, all planned to come online in the near future, and find that: (a) CTA and XENON1T are fully complementary, with CTA most sensitive to multi-TeV masses and mass splittings around 10%, and XENON1T probing best small mass splittings up to TeV masses; and (b) current constraints from XENON100 already preclude the observation of any spectral feature with GAMMA-400 in spite of its impressive energy resolution, unless dark matter does not couple predominantly to light quarks. Finally, we point out that, unlike for direct searches, the possibility of detecting thermal relics in upcoming internal bremsstrahlung searches requires, depending on the concrete scenario, boost factors larger than 5–10

  9. Internal bremsstrahlung signatures in light of direct dark matter searches

    International Nuclear Information System (INIS)

    Although proposed long ago, the search for internal bremsstrahlung signatures has only recently been made possible by the excellent energy resolution of ground-based and satellite-borne gamma-ray instruments. Here, we investigate thoroughly the current status of internal bremsstrahlung searches in light of the results of direct dark matter searches and in the framework of minimal mass-degenerate scenarios. The constraints set by Fermi-LAT and H.E.S.S. extend uninterrupted from tens of GeV up to tens of TeV and are rather insensitive to the mass degeneracy in the particle physics model. In contrast, direct searches are best in the moderate to low mass splitting regime, where XENON100 limits overshadow Fermi-LAT and H.E.S.S. up to TeV masses if dark matter couples to (light) quarks. We examine carefully the prospects for GAMMA-400, CTA and XENON1T, all planned to come online in the near future, and find that: (a) CTA and XENON1T are fully complementary, with CTA most sensitive to multi-TeV masses and mass splittings around 10%, and XENON1T probing best small mass splittings up to TeV masses; and (b) current constraints from XENON100 already preclude the observation of any spectral feature with GAMMA-400 in spite of its impressive energy resolution, unless dark matter does not couple to light quarks. Finally, we point out that, unlike for direct searches, the possibility of detecting thermal relics in upcoming internal bremsstrahlung searches requires boost factors larger than ∝10.

  10. Internal bremsstrahlung signatures in light of direct dark matter searches

    Energy Technology Data Exchange (ETDEWEB)

    Garny, Mathias [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ibarra, Alejandro; Pato, Miguel; Vogl, Stefan [Technische Univ. Muenchen, Garching (Germany). Physik Dept. T30d

    2013-06-15

    Although proposed long ago, the search for internal bremsstrahlung signatures has only recently been made possible by the excellent energy resolution of ground-based and satellite-borne gamma-ray instruments. Here, we investigate thoroughly the current status of internal bremsstrahlung searches in light of the results of direct dark matter searches and in the framework of minimal mass-degenerate scenarios. The constraints set by Fermi-LAT and H.E.S.S. extend uninterrupted from tens of GeV up to tens of TeV and are rather insensitive to the mass degeneracy in the particle physics model. In contrast, direct searches are best in the moderate to low mass splitting regime, where XENON100 limits overshadow Fermi-LAT and H.E.S.S. up to TeV masses if dark matter couples to (light) quarks. We examine carefully the prospects for GAMMA-400, CTA and XENON1T, all planned to come online in the near future, and find that: (a) CTA and XENON1T are fully complementary, with CTA most sensitive to multi-TeV masses and mass splittings around 10%, and XENON1T probing best small mass splittings up to TeV masses; and (b) current constraints from XENON100 already preclude the observation of any spectral feature with GAMMA-400 in spite of its impressive energy resolution, unless dark matter does not couple to light quarks. Finally, we point out that, unlike for direct searches, the possibility of detecting thermal relics in upcoming internal bremsstrahlung searches requires boost factors larger than {proportional_to}10.

  11. Formation of bremsstrahlung in an absorptive QED/QCD medium

    OpenAIRE

    Bluhm, Marcus; Gossiaux, Pol Bernard; Gousset, Thierry; Aichelin, Joerg

    2012-01-01

    The radiative energy loss of a relativistic charge in a dense, absorptive medium can be affected significantly by damping phenomena. The effect is more pronounced for large energies of the charge and/or large damping of the radiation. This can be understood in terms of a competition between the formation time of bremsstrahlung and a damping time scale. We discuss this competition in detail for the absorptive QED and QCD medium, focusing on the case in which the mass of the charge is large com...

  12. Laser field effects on the collective inverse Bremsstrahlung process

    International Nuclear Information System (INIS)

    The energy loss method has been applied to a large variety of transport problems in optics, solid state and fusion research. Usually, the transport equations are linearized, so they cannot deal with the multiphoton interaction in the presence of an intense laser field. In particular, not much attention has been given to collective contribution to the rates of the energy loss and inverse Bremsstrahlung process from a quantum mechanical viewpoint. On the basis of the center of mass approach, we show the proper way to calculate the collective part of these rates, which depend on the energy loss function Im{-1/ε(q-vector,w)}. (author). 31 refs

  13. Angular Distribution of Photons in Coherent Bremsstrahlung in Deformed Crystals

    CERN Document Server

    Parazian, V V

    2010-01-01

    We investigate the angular distribution of photons in the coherent bremsstrahlung process by high-energy electrons in a periodically deformed single crystal with a complex base. The formula for the corresponding differential cross-section is derived for an arbitrary deformation field. The case is considered in detail when the electron enters into the crystal at small angles with respect to a crystallographic axis. The results of the numerical calculations are presented for SiO2 single crystal and Moliere parameterization of the screened atomic potentials in the case of the deformation field generated by the acoustic wave of S -type.

  14. Diffraction structures in high-energy electron–nucleus bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Jakubassa-Amundsen, D.H.

    2013-10-30

    The emission of hard bremsstrahlung during the collision of relativistic spin-polarized electrons with inert spin 0 and spin 1/2 nuclei is calculated within the weak-potential approximation. Diffraction structures in the polarization correlations between the beam electron and the emitted photon are predicted for collision energies in the region 50–120 MeV if the photon is emitted at backward angles. The dynamical recoil plays a dominant role concerning the location and the shape of the structures. The target nuclei {sup 19}F, {sup 64}Zn and {sup 89}Y are investigated.

  15. Atomic Bremsstrahlung in ion-atom collisions (stripping)

    International Nuclear Information System (INIS)

    Atomic Bremsstrahlung produced in high energy (non relativistic) ion-atom collisions including retardation effects is studied. Mechanical states of the system are described by the symmetrical eikonal approximation and Hartree-Fock electronic wave functions for the calculation of the shape factor of each atom. Photon energy spectra are presented for collisions of protons against noble gases, Ne, Ar, Kr and Xe. The contribution of each atomic shell to these spectra is studied, where lowest shell (1s) corresponds to the hard X-ray region and the higher shells correspond to lower photon energies. (Author)

  16. Molecular Bremsstrahlung Radiation at GHz Frequencies in Air

    CERN Document Server

    Samarai, I Al; Deligny, O; Letessier-Selvon, A; Montanet, F; Settimo, M; Stassi, P

    2016-01-01

    A detection technique for ultra-high energy cosmic rays, complementary to the fluorescence technique, would be the use of the molecular Bremsstrahlung radiation emitted by low-energy ionization electrons left after the passage of the showers in the atmosphere. In this article, a detailed estimate of the spectral intensity of photons at ground level originating from this radiation is presented. The spectral intensity expected from the passage of the high-energy electrons of the cascade is also estimated. The absorption of the photons in the plasma of electrons/neutral molecules is shown to be negligible. The obtained spectral intensity is shown to be $2\\times10^{-21} $W cm$^{-2}$ GHz$^{-1}$ at 10 km from the shower core for a vertical shower induced by a proton of $10^{17.5}$ eV. In addition, a recent measurement of Bremsstrahlung radiation in air at gigahertz frequencies from a beam of electrons produced at 95 keV by an electron gun is also discussed and reasonably reproduced by the model.

  17. Molecular bremsstrahlung radiation at GHz frequencies in air

    Science.gov (United States)

    Al Samarai, Imen; Bérat, Corinne; Deligny, Olivier; Letessier-Selvon, Antoine; Montanet, François; Settimo, Mariangela; Stassi, Patrick

    2016-03-01

    A detection technique for ultra-high-energy cosmic rays, complementary to the fluorescence technique, would be the use of the molecular bremsstrahlung radiation emitted by low-energy ionization electrons left after the passage of the showers in the atmosphere. In this article, a detailed estimate of the spectral intensity of photons at ground level originating from this radiation is presented. The spectral intensity expected from the passage of the high-energy electrons of the cascade is also estimated. The absorption of the photons in the plasma of electrons and neutral molecules is shown to be negligible. The obtained spectral intensity is shown to be 2 ×1 0-21 W cm-2 GHz-1 at 10 km from the shower core for a vertical shower induced by a proton of 1 017.5 eV . In addition, a recent measurement of bremsstrahlung radiation in air at gigahertz frequencies from a beam of electrons produced at 95 keV by an electron gun is also discussed and reasonably reproduced by the model.

  18. Polarization of bremsstrahlung at electron scattering in an anisotropic medium

    International Nuclear Information System (INIS)

    Bremsstrahlung from relativistic electrons is considered under conditions when some transverse direction of momentum transfer is statistically preferred. It is shown that in the dipole approximation all the medium anisotropy effects can be accumulated into a special modulus-bound transverse vector, N. To exemplify a target with N2∼1, we calculate radiation from an electron incident at a small angle on an atomic row in an oriented crystal. Radiation intensity and polarization dependencies on the emission angle and frequency for constant N are investigated. Net polarization for the angle-integral cross section is evaluated, which appears to be proportional to N2/2, and decreases with the increase of the photon energy fraction. A prominent feature of the radiation angular distribution is the existence of an angle at which the radiation may be completely polarized, in spite of the target complete or partial isotropy; that owes to existence of an origin-centered tangential circle for polarization in the fully differential radiation probability kernel. Possibilities for utilizing various properties of the polarized bremsstrahlung flux for preparation of polarized photon beams and for probing intrinsic anisotropy of the medium are analyzed.

  19. Temperature diagnostics of ECR plasma by measurement of electron bremsstrahlung

    International Nuclear Information System (INIS)

    The x-ray bremsstrahlung spectrum emitted by the electron population in a 14.5 GHz ECR plasma source has been measured using a NaI(Tl) detector, and hence the electron temperature of the higher energy electron population in the plasma has been determined. The x-ray spectra for Ne and Ar gases have been systematically studied as a function of inlet gas pressure from 7 × 10−7 mbar to 7 × 10−5 mbar and for input microwave power ∼1 W to ∼300 W. At the highest input power and optimum pressure conditions, the end point bremsstrahlung energies are seen to reach ∼700 keV. The estimated electron temperatures (Te) were found to be in the range 20 keV–80 keV. The Te is found to be peaking at a pressure of 1 × 10−5 mbar for both gases. The Te is seen to increase with increasing input power in the intermediate power region, i.e., between 100 and 200 W, but shows different behaviour for different gases in the low and high power regions. Both gases show very weak dependence of electron temperature on inlet gas pressure, but the trends in each gas are different.

  20. Measurement of absorbed dose by 7-GeV bremsstrahlung in a PMMA phantom

    CERN Document Server

    Job, P K; Semones, E

    1999-01-01

    High-energy electron storage rings generate energetic bremsstrahlung photons through radiative interaction of the particle beam with the residual gas molecules and other components inside the storage ring. At synchrotron radiation facilities, where beamlines are channeled out of the storage ring, a continuous bremsstrahlung spectrum, with a maximum energy of the stored particle beam, will be present. At the advanced photon source (APS), where the stored beam energy is 7 GeV, bremsstrahlung generated in the straight sections of the insertion device beamlines, which are a total of 15.38 m in length, can be significant. The contribution from each bremsstrahlung interaction adds up to produce a narrow mono-directional bremsstrahlung beam that comes down through the insertion device beamlines. The resulting absorbed dose distributions by this radiation in a 300 mmx300 mmx300 mm tissue substitute cube phantom were measured with LiF:Mg,Ti (TLD-700) thermoluminescent dosemeters. The normalized absorbed dose, in a cro...

  1. Search of gamma-rays Bremsstrahlung mirror reflection

    International Nuclear Information System (INIS)

    Full text: Total external reflection of soft X-rays is widely used in many X-ray optic systems. At the same time in the wavelength range of gamma rays the corresponding total external reflection on macroscopic smooth surface hasn't been surely verified yet. Samarkand microtron MT-22S with 330 meter flying distance was used for a search experiment of detecting gamma-ray total external reflection. Measured slip angles (i.e. angles between incident ray and reflector surface) are negligible and don't exceed tens of micro-radian. And it is a complicated problem to get required characteristics of collimating, reflecting and detecting gamma rays. The experimental setup was described earlier. Here we report experimental results of very small-angle Bremsstrahlung scattering only in comparison with results of computer simulation by Monte-Carlo method. It is continuous energy spectrum of Bremsstrahlung gamma rays (described by Shift formula) that is the first characteristic property of the experiment. And it is air in the way of gamma rays that is the second one. Continuous energy spectrum provides a use of some range of reflector inclinations (but bounded above) that satisfy the conditions of the total reflection for a corresponding part of gamma ray beam. As for air it absorbs gamma rays on their long way to detectors lowering the ratio of searching effect to background. Horizontal belt type Bremsstrahlung beam was collimated for the experiment. So the beam's horizontal acceptance was relatively wide (∼ 34 mrad). A collimator with gap heights of 100, 50 and 20 μ limited the beam in vertical that results in beam vertical divergences of 125, 62 and 25 μrad, correspondingly. The gap height of 100 μ used for positioning procedure, and the ones of 50 and 20 μ used for measurements. No separate peak of reflected gamma rays was observed at the experiment. However when vertical profiles measured at the reflector inclinations of 0 and 40 μrad are compared one can see gamma

  2. Vacuum Cherenkov radiation and bremsstrahlung from disformal couplings

    Science.gov (United States)

    van de Bruck, Carsten; Burrage, Clare; Morrice, Jack

    2016-08-01

    The simplest way to modify gravity is to extend the gravitational sector to include an additional scalar degree of freedom. The most general metric that can be built in such a theory includes disformal terms, so that standard model fields move on a metric which is the sum of the space time metric and a tensor constructed from first derivatives of the scalar. In such a theory gravitational waves and photons can propagate at different speeds, and these can in turn be different from the maximum speed limit for matter particles. In this work we show that disformal couplings can cause charged particles to emit Cherenkov radiation and bremsstrahlung apparently in vacuum, depending on the background evolution of the scalar field. We discuss the implications of this for observations of cosmic rays, and the constraints that arise for models of dark energy with disformal couplings.

  3. Vacuum Cherenkov radiation and bremsstrahlung from disformal couplings

    CERN Document Server

    van de Bruck, Carsten; Morrice, Jack

    2016-01-01

    The simplest way to modify gravity is to extend the gravitational sector to include an additional scalar degree of freedom. The most general metric that can be built in such a theory includes disformal terms, so that standard model fields move on a metric which is the sum of the space time metric and a tensor constructed from first derivatives of the scalar. In such a theory gravitational waves and photons can propagate at different speeds, and these can in turn be different from the maximum speed limit for matter particles. In this work we show that disformal couplings can cause charged particles to emit Cherenkov radiation and bremsstrahlung apparently in vacuum, depending on the background evolution of the scalar field. We discuss the implications of this for observations of cosmic rays, and the constraints that arise for models of dark energy with disformal couplings.

  4. Decay energy of 55Fe from its inner Bremsstrahlung spectrum

    Indian Academy of Sciences (India)

    S L Keshava; K Gopala; P Venkataramaiah

    2001-06-01

    Several measurements of decay energy using the inner Bremsstrahlung spectrum (IB) due to radiative electron capture in 55Fe has been made. But the results are not uniform. Hence another attempt has been made at the same. Experimental data was obtained with a 4.445 cm. dia × 5.08 cm thick NaI (Tl) detector. It was subjected to suitable statistical treatment and various corrections using Liden and Starfelt procedure. The corrected spectrum agrees well with the Glauber and Martin theory for 1s electron capture beyond 100 keV. From the Jauch plot, the decay energy of 232.36 ± 0.64 keV was obtained.

  5. Spectra and rates of bremsstrahlung neutrino emission in stars

    Science.gov (United States)

    Guo, Gang; Qian, Yong-Zhong

    2016-08-01

    We calculate the energy-differential rate for neutrino emission from electron-nucleus bremsstrahlung in stellar interiors taking into account the effects of electron screening and ionic correlations. We compare the energy-differential and the net rates, as well as the average ν¯e and ν¯x(x =μ ,τ ) energies, for this process with those for e± pair annihilation, plasmon decay, and photoneutrino emission over a wide range of temperature and density. We also compare our updated energy loss rates for the above thermal neutrino emission processes with the fitting formulas widely used in stellar evolution models and determine the temperature and density domain in which each process dominates. We discuss the implications of our results for detection of ν¯e from massive stars during their presupernova evolution and find that pair annihilation makes the predominant contribution to the signal from the thermal emission processes.

  6. Internal bremsstrahlung endpoint energy of {sup 54}Mn

    Energy Technology Data Exchange (ETDEWEB)

    Hindi, M. M. [Physics Department, Tennessee Technological University, Cookeville, Tennessee 38505 (United States); Larimer, R.-M. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Norman, E. B. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Rech, G. A. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2000-05-01

    For {sup 54}Mn there is a discrepancy between the Q{sub EC} obtained from the endpoint energy of the internal bremsstrahlung (IB) spectrum which accompanies the electron capture decay (Q{sub EC}=1353{+-}8 keV) and that obtained from the accepted mass differences (Q{sub EC}=1377{+-}1 keV). This Q value is needed to deduce the partial-half life of the astrophysically interesting {beta}{sup -} decay of {sup 54}Mn from the recently measured {beta}{sup +} partial half-life. To resolve this discrepancy, we have remeasured the endpoint energy of the IB spectrum, by recording coincidences between the IB and the 835-keV {gamma} ray, both detected in Compton-suppressed Ge detectors. The Q{sub EC} we deduce is 1379{+-}8 keV, in agreement with the accepted mass differences. (c) 2000 The American Physical Society.

  7. The LPM effect in sequential bremsstrahlung: dimensional regularization

    CERN Document Server

    Arnold, Peter; Iqbal, Shahin

    2016-01-01

    The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. Of recent interest is the case when the coherence lengths of two consecutive splitting processes overlap (which is important for understanding corrections to standard treatments of the LPM effect in QCD). In previous papers, we have developed methods for computing such corrections without making soft-gluon approximations. However, our methods require consistent treatment of canceling ultraviolet (UV) divergences associated with coincident emission times, even for processes with tree-level amplitudes. In this paper, we show how to use dimensional regularization to properly handle the UV contributions. We also present a simple diagnostic test that any consistent UV regularization method for this problem needs to pass.

  8. Calculation of electron and bremsstrahlung fields in heterogenous material layers

    International Nuclear Information System (INIS)

    The Ssub(N)-method, a numerical technique to solve the general transport equation is used to describe the passage of electrons through material layers and is discussed with respect to precision and difficulty in comparision with the Monte-Carlo-method. The production and tracking of secondary electrons and bremsstrahlung photons is taken into account. Therefore, the procedure allows investigations in a broad spectral region which is of interest for medical and technical applications. As results energy spectra and distributions in arrangements of different textures are reported for electron energies up to 20 MeV. With a reasonable need of computer time the influence of an inhomogeneous electron irradiation can be studied which is of great importance in electron radiation therapy. The integration of the necessary computer codes in the modular program system RSYST allows an almost automatic performance of calculation and data transfer. (orig./ORU)

  9. The double copy: Bremsstrahlung and accelerating black holes

    CERN Document Server

    Luna, Andres; Nicholson, Isobel; O'Connell, Donal; White, Chris D

    2016-01-01

    Advances in our understanding of perturbation theory suggest the existence of a correspondence between classical general relativity and Yang-Mills theory. A concrete example of this correspondence, which is known as the double copy, was recently introduced for the case of stationary Kerr-Schild spacetimes. Building on this foundation, we examine the simple time-dependent case of an accelerating, radiating point source. The gravitational solution, which generalises the Schwarzschild solution, includes a non-trivial stress-energy tensor. This stress-energy tensor corresponds to a gauge theoretic current in the double copy. We interpret both of these sources as representing the radiative part of the field. Furthermore, in the simple example of Bremsstrahlung, we determine a scattering amplitude describing the radiation, maintaining the double copy throughout. Our results provide the strongest evidence yet that the classical double copy is directly related to the BCJ double copy for scattering amplitudes.

  10. Neutrino-pair bremsstrahlung and the number of lepton generations

    Science.gov (United States)

    Tung, Wu-Ki

    1980-12-01

    Neutrino pair creation in bremsstrahlung processes of the typel to l{text{ }}v{text{ }}bar v contains vital information on the number of lepton generations, and is catalyzed by the coherent nuclear Coulomb effect or other forms of intense fields. Of particular interest is the ratioR_{vbar v} = σ [1mathop to limits_A l(vbar v)]/σ [1mathop to limits_A l'(vbar v)] (where l, l' are distinct charged leptons). It is sensitive to the number of neurino types and their couplings in the same way that the ratioR_{qbar q} = σ [e^ + e^ - to {text{hadrons}}]/σ [e^ + e^ - to μ ^ + μ ^ - ] is to those of quarks. In the Weinberg-Salam model with N lepton generations, the ratioR_{vbar v} is approximately given by[(N + 4) + 4(1 - 4sin ^2 θ _W )]/8.

  11. Rhodium M(o)ssbauer Effect Generated by Bremsstrahlung Excitation

    Institute of Scientific and Technical Information of China (English)

    CHENG Yao; XIA Bing; LIU Yi-Nong; JIN Qing-Xiu

    2005-01-01

    @@ A method for effectively generating long-lived Mossbauer photons and methods for proving the associated Mossbauer effects are reported. For the first time, we observed resonant propagation and resonant absorption of 40-keV Mossbauer photons emitted from 103Rh through (γ,γ′) process excited by bremsstrahlung. This is a new efficient way to generate long-lived isomer (> 1 ms) for Mossbauer spectroscopy with sufficient brilliance.An abnormally large ratio of resonant absorption between horizontal and vertical directions indicates horizontal trapping of Mossbauer photons and anisotropic Mossbauer emission, which can be attributed to gravitational effect on the 103Rh Mossbauer isomer with extremely narrow 10-19 eV linewidth.

  12. Vircator in regime of x-ray Bremsstrahlung

    International Nuclear Information System (INIS)

    The power vircator with multi-flight electrons cross optical thin anode foil power pulses generation of X-ray radiation created and operated in first. The vircator realized on the base of direct action electron accelerator with supplies of inductive energy storage with plasma switch of current. In paper results of 2-D self-consistent calculations of electron beam dynamics in vircator camera and determined spectra of arise UHF-radiation. The results of first experiments on vircator X-ray Bremsstrahlung for thin (10 mkm, Ta) and thick (100 mkm, Ta) anode foils are presented. The dose of X-ray radiation for thin foil (Eγ > 30 keV) in 8 greater than dose received for thick anode, middle photon energy reduced from 80 keV to 30 keV

  13. The influence of Bremsstrahlung induced photoionization for the streamer motion in various gas mixtures

    Science.gov (United States)

    Koehn, Christoph; Chanrion, Olivier; Neubert, Torsten

    2016-04-01

    Streamers, the beginning stages of electric discharges, evolve differently depending on their polarity and on the ambient gas composition. One of the well-known supporting mechanisms is "UVphotoionization" where, in air, excited nitrogen emits a UV photon subsequently ionizing oxygen. In pure nitrogen, however, this mechanism is suppressed because of the lack of oxygen; hence this mechanism strongly depends on the ambient gas medium. In this paper we introduce Bremsstrahlung induced photoionization: In the ambient electric field,electrons gain energy and produce Bremsstrahlung photons through the collision with the ambient gas molecules; similarly to "UV-photoionization", the Bremsstrahlung photons ionize the gas molecules and, as such, create electron populations detached from the initial electron patch. For the study of this process we implemented the electron-nucleus Bremsstrahlung process as well as the photoionization by individual photons into an already existing 2.5 D Monte Carlo particle code for the simulation of streamers. We initiated plasma patches of electrons and ions with varying initial electron energies and peak densities in different ambient fields in air and pure nitrogen. We will compare the temporal evolution of the electron densities as well as of the electric field with and without modelling Bremsstrahlung. In air we will test the influence of Bremsstrahlung induced photoionization against "UV-photoionization". We will show that the influence of Bremsstrahlung is negligible in air, but plays a significant role in pure nitrogen at standard temperature and pressure.

  14. Study of compound nucleus formation via bremsstrahlung emission in proton $\\alpha$-particle scattering

    CERN Document Server

    Maydanyuk, Sergei P

    2016-01-01

    In this paper a role of many-nucleon dynamics in formation of the compound $^{5}{\\rm Li}$ nucleus in the scattering of protons off $\\alpha$-particles at the proton incident energies up to 20 MeV is investigated. We propose a bremsstrahlung model allowing to extract information about probabilities of formation of such nucleus on the basis of analysis of experimental cross-sections of the bremsstrahlung photons. In order to realize this approach, the model includes elements of microscopic theory and also probabilities of formation of the short-lived compound nucleus. Results of calculations of the bremsstrahlung spectra are in good agreement with the experimental cross-sections.

  15. Electron spectroscopy in the fundamental process of electron-nucleus bremsstrahlung

    International Nuclear Information System (INIS)

    Within the scope of this thesis the fundamental process of electron-nucleus bremsstrahlung was studied in inverse kinematics at the Experimental Storage Ring ESR at GSI. For the system U88+ + N2 at 90 MeV/u it was shown, that by using inverse kinematics coincidence measurements between the scattered electron and the emitted photon can be performed for the case, in which the incoming electron transfers almost all of its kinetic energy onto the emitted photon. The sensitivity to the fundamental process could be achieved by measuring triple differential cross sections as a function of the emission angle of the photon and the scattered electron as well as the energy of the scattered electron. The optics of the magnetic electron spectrometer used were thoroughly revised and optimized to the experimental requirements. Analyzing different coincidences in this collision system, it was possible to determine the contributions to the electron distribution arising from radiative electron capture to the projectile continuum, nonradiative electron capture to the projectile continuum, and electron loss to the projectile continuum. The experimental results of each of these processes were compared to theoretical calculations. The electron spectra for the radiative and the nonradiative electron capture to continuum clearly reproduce the opposite asymmetry predicted by theory. Furthermore electron spectra for collisions of U28+ with different gases were measured.

  16. The bremsstrahlung tagged photon beam in Hall B at the Jefferson Laboratory

    International Nuclear Information System (INIS)

    We describe the design and commissioning of the photon tagging beamline installed in experimental Hall B at the Thomas Jefferson National Accelerator Facility (Jlab). This system can tag photon energies over a range from 20% to 95% of the incident electron energy, and is capable of operation with beam energies up to 6.1 GeV. A single dipole magnet is combined with a hodoscope containing two planar arrays of plastic scintillators to detect energy-degraded electrons from a thin bremsstrahlung radiator. The first layer of 384 partially overlapping small scintillators provides photon energy resolution, while the second layer of 61 larger scintillators provides the timing resolution necessary to form a coincidence with the corresponding nuclear interaction triggered by the tagged photon. The definitions of overlap channels in the first counter plane and of geometric correlation between the two planes are determined using digitized time information from the individual counters. Auxiliary beamline devices are briefly described, and performance results to date under real operating conditions are presented. The entire photon-tagging system has met or exceeded its design goals

  17. Calculation of beta induced Bremsstrahlung exposure from therapeutic radionuclide 198Au in tissues, DNA and RNA

    International Nuclear Information System (INIS)

    Gold-198 (βmax= 0.96 MeV (98.6%), γmax= 0.412 MeV (95.5%) and T1/2 = 2.7 days) is a well-known therapeutic beta emitter in the field of nuclear medicine, and is being used for the treatment of many different cancers. In the present study, the Bremsstrahlung exposure induced by 198Au in different human tissues, DNA and RNA has been calculated. The specific Bremsstrahlung constant (ΓBr), Probability of energy loss by beta during Bremsstrahlung emission (PBr) and Bremsstrahlung activity (Arelease)Br were estimated. We strongly recommend these parameters should be considered in absorbed dose calculations of radionuclide therapy via 198Au. (orig.)

  18. Calculation of molecular bremsstrahlung radiation and air shower plasma conditions for CROME

    International Nuclear Information System (INIS)

    The possibility of the detection of extensive air showers by observation of isotropic microwave radiation due to molecular bremsstrahlung has been proposed in 2008. Ionization electrons, forming a short-lived, tenuous plasma in the wake of the shower, interact with atmospheric neutrals and produce bremsstrahlung. Concurrent with first measurements of microwave radiation by the CROME experiment in Karlsruhe, an independent, theory based model for emission of isotropic bremsstrahlung emission has been developed. In this talk, the assumptions of the model for bremsstrahlung emission and the findings concerning the state of the plasma in an air shower are discussed. The magnitude of the expected signal is calculated and compared to predictions made in the original proposal by Gorham et al. and to the observed GHz signals.

  19. Energy spectra of secondary neutrons produced by high energy bremsstrahlung in carbon, nitrogen, oxygen and tissue

    International Nuclear Information System (INIS)

    Neutron energy spectra in carbon, nitrogen and oxygen were calculated for various bremsstrahlung end-point energies and, from these, tissue spectra were calculated using the tissue equivalent molecular formula C5H40O18N. The method involves folding the known bremsstrahlung spectrum shape with the cross section for each possible decay mode in each element which leads to neutron production. The partial photoneutron cross sections used have been derived from published data

  20. Bremsstrahlung radiation from electron-atom collisions in high pressure mercury lamps

    International Nuclear Information System (INIS)

    Bremsstrahlung coefficients for electron-mercury-atom collisions were computed using the corrected phase-shift approximation. These corrected bremsstrahlung coefficients are a weighted average of coefficients from the phase-shift and momentum transfer approximations. Phase-shifts determined from solutions of the Dirac-Fock scattering equations including both static and dynamic polarization potentials and exchange effects were used. The corrected coefficients approach the same limit at longer wavelengths as coefficients from the simpler momentum transfer approximation, but are generally larger

  1. Bremsstrahlung radiation from electron-atom collisions in high pressure mercury lamps

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, J E [Department of Physics, University of Wisconsin, 1150 University Avenue, Madison, WI 53706 (United States)

    2004-06-07

    Bremsstrahlung coefficients for electron-mercury-atom collisions were computed using the corrected phase-shift approximation. These corrected bremsstrahlung coefficients are a weighted average of coefficients from the phase-shift and momentum transfer approximations. Phase-shifts determined from solutions of the Dirac-Fock scattering equations including both static and dynamic polarization potentials and exchange effects were used. The corrected coefficients approach the same limit at longer wavelengths as coefficients from the simpler momentum transfer approximation, but are generally larger.

  2. Electron heating, time evolution of bremsstrahlung and ion beam current in electron cyclotron resonance ion sources

    OpenAIRE

    Ropponen, Tommi

    2010-01-01

    This thesis is a study of Electron Cyclotron Resonance Ion Source (ECRIS) plasmas and their properties. The focus has been on time evolution studies of bremsstrahlung emission, ion beam current production and numerical studies of electron heating in ECRIS plasmas. The time scales for reaching steady state bremsstrahlung production at electron energies greater than 30 keV is shown to be on the order of several hundreds of milliseconds. The ion beam currents of different elements...

  3. Screening Effects on Nonrelativistic Bremsstrahlung in the Scattering of Electrons by Neutral Atoms

    Science.gov (United States)

    Jung, Young-Dae; Lee, Kun-Sang

    1995-01-01

    Atomic screening effects on nonrelativistic electron-atom bremsstrahlung radiation are investigated using a simple analytic solution of the Thomas-Fermi model for many-electron atoms. The Born approximation is assumed for the initial and final states of the projectile electron. The results show that the screening effect is important in the soft radiation region and is decreasing with increasing radiation. These results help provide correct information about the behavior of bound electrons in the target atom in bremsstrahlung processes.

  4. Effects of electron temperature and density on ion-dust bremsstrahlung

    OpenAIRE

    Jung, Young-Dae; MURAKAMI, Izumi

    2009-01-01

    The effects of electron temperature and density on the ion-dust grain bremsstrahlung process industy plasmas are studied. The ion-dust bremsstrahlung radiation cross section is obtained as afunction of the dust charge, dust radius, Debye length, collision energy, radiation energy, electrondensity, and electron temperature by using the Born approximation. It is shown that the ion-dustbremsstrahlung radiation cross section decreases with an increase in the electron density in dustyplasmas. It i...

  5. Dose assessment of Bremsstrahlung induced by beta isotopes of Uranium-238 series in human tissues

    International Nuclear Information System (INIS)

    In the natural Uranium-238 decay series, pure beta isotopes such as 234Th, 234Pa, 214Pb, 214Bi, 210Pb and 210Bi are released. These beta isotopes having maximum beta energies and it induces the Bremsstrahlung radiation. The Bremsstrahlung component of these beta isotopes has been traditionally ignored in dosimetry calculations. This may be due to a lack of available methods for including this component in the calculations or to the belief that the contribution of this component is negligible compared to that of other emissions. The resulting hazard of Bremsstrahlung radiation may therefore be some of concern, at least theoretically, and should be systematically evaluated. In the present investigation, it has been estimated that the Bremsstrahlung dose of beta isotopes of Uranium-238 series such as 234Th, 234Pa, 214Pb, 214Bi, 210Pb and 210Bi in various body organs (Adrenals, Brain, Breasts, Gallbladder Wall, LLI Wall, Small Intestine, Stomach, ULI Wall, Heart Wall, Kidneys, Liver, Lungs, Muscle, Ovaries, Pancreas, Red Marrow, Bone Surfaces, Skin, Spleen, Testes, Thymus, Thyroid, Urine Bladder Wall, Uterus, Fetus, Placenta and Total Body). We have considered bone and muscle is target organs. These estimated values shows that the Bremsstrahlung radiation absorbed dose contribution from an organ to itself is very small compared to that from the beta source, but contribution to other organs is not always negligible. Hence the component of Bremsstrahlung dose to total dose should be considered in the environmental radioactivity dose calculations. (author)

  6. Graded-Z flash-bremsstrahlung depth-dose spectrometer

    International Nuclear Information System (INIS)

    A depth-dose spectrometer is described for measuring photon spectra from a single, short, intense burst of photons in the energy range of 30-1000 keV. It consists of 13 layers of three each thermoluminescent dosimeters (TLDs) separated by metallic foils graded in Z and thickness such that depth-dose responses Dsub(j)(I) to photons of energy Esub(j) are step functions with positive initial slope and with an endpoint that increases monotonically with Esub(j), giving a unique measure of energy. These features enhance the stability of the solution phi(J) of the matrix equation D(I)=A(I, J)phi(J) to oscillations. The response vectors Dsub(j)(I) that make up the detector response matrix A(I, J) were calculated and compared with measurements using thin teflon TLDs loaded with a low-Z(LiF) and a medium-Z(CaF2) phosphor. These three sets of data yield phosphor grain-size corrections for CaF2 (manganese activated). A comparison with an independent measurement for a 1 MeV endpoint bremsstrahlung spectrum gives a measure of the confidence interval of the spectrometer. (Auth.)

  7. Coherent Bremsstrahlung and Channeling Radiation at low energies

    International Nuclear Information System (INIS)

    The theory of the two radiative processes, Channeling Radiation (CR) and Coherent Bremsstrahlung (CB), is studied using the dynamical theory of scattering familiar in electron diffraction. The results are applicable to low energies where photon energies are much less than the electron rest energy (at higher energies some spin effects become important). The dynamical theory is reviewed. The interaction of the electron with the photon field is described in the electron frame of reference and then transformed to the lab. Fine structure is predicted for the CB (or juddering radiation) due to the effect of transitions between many different Bloch waves. The splitting may be useful in accurately determining interatomic potentials. CR is seen to be the special case of CB when there is no Umklapp. Explicit analytic results for the energy dependence of the emission energies and intensities are given, and compared with that of a dipole radiator. Experimental results for CB from higher order reciprocal lattice planes are presented and discussed, including the first study of axial CB variation with specimen tilt

  8. Bremsstrahlung in carbon thick targets by proton incidence

    International Nuclear Information System (INIS)

    The subtraction of the continuum from an X-ray spectrum emitted by proton bombardment is usually carried out by means of a mathematical fitting. The purpose of the present work is to develop an analytical function to model the continuous spectrum generated in a PIXE experiment for different incident beam energies in carbon thick targets. With this purpose, PIXE spectra of a carbon bulk sample were measured in an ion accelerator. The proton beam energies were varied between 0.7 MeV and 2 MeV and the X-rays generated were collected by an energy dispersive spectrometer. The spectra analysis was performed taking into account the main effects underlying the production of the continuous spectrum. Nevertheless, for the cases considered here, it was found that the atomic bremsstrahlung is the most important and other contributions were neglected. The experimental spectra from carbon thick targets were corrected by self-absorption and detector efficiency. The results show that the spectral shape corresponding to thick targets corrected by these effects is similar to the functional behavior presented by thin targets

  9. Beam-target interaction experiments for Bremsstrahlung converter applications

    International Nuclear Information System (INIS)

    The authors are investigating the possible adverse effects of (1) backstreaming ion emission from the Bremsstrahlung converter target and (2) the interaction of the resultant plasma with the electron beam during subsequent pulses for multi-pulse radiography facilities. These effects would primarily manifest themselves in a static focusing system as a rapidly varying x-ray spot. To study these effects, they are conducting beam-target interaction experiments on the ETA-II accelerator (a 6.0 MeV, 2.5 kA, 70 ns FWHM pulsed, electron accelerator). They are measuring spot dynamics and characterizing the resultant plasma for various configurations. Thus far, their experiments show that the first effect is not strongly present when the beam initially interacts with the target. Electron beam pulses delivered to the target after formation of a plasma are strongly affected. They have also performed initial experiments to determine the effect of the beam propagating through the plasma. This data shows that the head of the beam is relatively robust, but that backstreaming ions from the plasma can still manifest itself as a dynamic focus toward the tail of the beam. They report on the details of the experimental work to suppress these effects

  10. A Single Bremsstrahlung Monitor to Measure Luminosity at LEP

    CERN Multimedia

    2002-01-01

    The luminosity, the beam divergence and the longitudinal polarization can be measured at an interaction point of LEP by dectecting the energy, the angular distribution and the circular polarization of the single bremsstrahlung photons (SB) emitted at very forward angle. The luminosity can be measured by this met than by the conventional method of detecting small angle Bhabha scattering. The bunch to bunch relative luminosity can be monitored at a few per mil level in few minutes. Absolute values of the luminosity and of the polarization can be measured with a precision of the order of 1\\%. \\\\ \\\\ The apparatus to detect SB photons consists of a low Z absorber and of an EM calorimeter made of lead and scintillating fibres. Both the total energy and the space distribution of the SB photons are measured. This apparatus has been designed and built at the Department of Physics and INFN Section of the University of Rome ``La Sapienza''. Later on, together with suitable monocrystal converters, it may be used also for...

  11. Development of bremsstrahlung detection type tritium gas monitoring system, (1)

    International Nuclear Information System (INIS)

    A tritium monitoring system by means of bremsstrahlung detecting was developed. A prototype system consisted of a sampling cylinder, a gas circulating apparatus, an NaI(T1) detector, an amplifier and a multichannel analyzer. The sizes of sampling cylinders used 208 mm phi x 290; 170; 70 mmH, 133 mm phi x 292; 172; 72 mmH and 55 mm phi x 294; 174; 74 mmH, respectively. The sensitivity of prototype system was from 12 to 57 cps/μCi.cm-3, depending on the size of sampling cylinder and an efficiency of NaI(T1) detector. When pulses due to breamsstrahlungs with energy from 4 to 17 keV were counted, the minimum detectable concentration of the prototype tritium monitoring system was obtained to be 5.2 x 10-3 μCi/cm3. It was evaluated that the detectable range of concentration was from 1 x 10-2 to 1 x 103 μCi/cm3. (author)

  12. Studies of some isomeric yield ratios produced with bremsstrahlung

    CERN Document Server

    Kolev, D

    1998-01-01

    The experimental isomeric ratios for sup 5 sup 2 sup m sup , sup g Mn, sup 8 sup 6 sup m sup , sup g Y, sup 8 sup 7 sup m sup , sup g Y, sup 8 sup 9 sup m sup , sup g Zr, sup 1 sup 1 sup 0 sup m sup , sup g In, sup 1 sup 1 sup 1 sup m sup , sup g In, sup 1 sup 1 sup 2 sup m sup , sup g In, sup 1 sup 5 sup 2 sup m sup 1 sup , sup g Pm, sup 1 sup 5 sup 2 sup m sup 2 sup , sup m sup 1 Eu, sup 1 sup 6 sup 2 sup m sup , sup g Ho, sup 1 sup 6 sup 4 sup m sup , sup g Ho and sup 1 sup 7 sup 8 sup m sup , sup g Lu measured by the activation technique from different targets in (gamma, xnp) reactions (x<=3) at the bremsstrahlung end-point energy of 43 MeV are presented. The predictions of calculations performed by means of compound nucleus particle evaporation and final gamma-deexcitation were critically discussed. The importance of inclusion in the calculations of nonequilibrium particle emission and an adequate gamma-decay mode of isomeric nuclei was considered for some of the reactions investigated.

  13. Tomography of the fast electron Bremsstrahlung emission during lower hybrid current drive on Tore Supra

    International Nuclear Information System (INIS)

    A new tomography dedicated to detailed studies of the fast electron Bremsstrahlung emission in the hard X-ray (HXR) energy range between 20 and 200 keV during lower hybrid (LH) current drive experiments on the TORE SUPRA tokamak [Equipe TORE SUPRA, in Proceedings of the 15. Conference on Plasma Physics and Controlled Nuclear Fusion Research, Seville (International Atomic Energy Agency, Vienna, 1995), 1, AIEA-CN-60 / A1-5, p. 105] is presented. Radiation detection is performed by cadmium telluride (CdTe) semiconductors, which have most of the desirable features for a powerful diagnosing of magnetically confined hot plasmas - compact size, high X-ray stopping efficiency, fast timing characteristics, good energy resolution, no sensitivity to magnetic field, reasonable susceptibility to performance degradation from neutron/γ-induced damages. This instrument is made of two independent cameras viewing a poloidal cross-section of the plasma, with respectively 21 and 38 detectors. A coarse spectrometry - 8 energy channels - is carried out for each chord, with an energy resolution of 20 keV. The spatial resolution in the core of the plasma is 4-5 cm, while the time sampling may be lowered down to of 2-4 ms. Powerful inversion techniques based on maximum entropy or regularization algorithms take fully advantage of the large number of line-integrated measurements for very robust estimates of the local HXR profiles as a function of time and photon energy. A detailed account of main characteristics and performances of the diagnostic is reported as well as preliminary results on LH current drive experiments. (authors)

  14. Impulsive solar X-ray bursts. III - Polarization, directivity, and spectrum of the reflected and total bremsstrahlung radiation from a beam of electrons directed toward the photosphere

    Science.gov (United States)

    Langer, S. H.; Petrosian, V.

    1977-01-01

    The paper presents the spectrum, directivity, and state of polarization of the bremsstrahlung radiation expected from a beam of high-energy electrons spiraling along radial magnetic field lines toward the photosphere. A Monte Carlo method is then described for evaluation of the spectrum, directivity, and polarization of X-rays diffusely reflected from stellar photospheres. The accuracy of the technique is evaluated through comparison with analytic results. The calculated characteristics of the incident X-rays are used to evaluate the spectrum, directivity, and polarization of the reflected and total X-ray fluxes. The results are compared with observations.

  15. PEBSI - A Monte Carlo simulator for bremsstrahlung arising from electrons colliding with thin solid-state targets

    CERN Document Server

    Weber, G; Surzhykov, A; Yasuda, M; Yerokhin, V A; Stöhlker, Th

    2012-01-01

    We present a Monte Carlo code dedicated to the simulation of bremsstrahlung arising in collisions of polarized electrons with thin target foils. The program consists of an electron transport algorithm taking into account elastic electron-nucleus scattering and inelastic collisions with target electrons as well as a treatment of polarized-electron bremsstrahlung emission. Good agreement is found between the predictions of the electron transport code and data stemming from other simulation programs and experiments. In addition, we present first results from the bremsstrahlung simulation which indicate a significant decrease in the degree of linear polarization of bremsstrahlung even for the thinnest gold targets considered.

  16. The free and In medium N-N interaction studied by nuclear Bremsstrahlung

    International Nuclear Information System (INIS)

    Full text: At the AGOR cyclotron of the KVI a series of Bremsstrahlung measurements has been carried out with proton and c beams using the combination of a highly segmented photon spectrometer (TAPS) with the smallangle large-acceptance detector (SALAD) for charged-particles. High precision cross sections and analysing powers have been measured for p+p Bremsstrahlung with 190 MeV polarized protons. For the first time exclusive differential cross sections of virtual bremsstrahlung could be determined. In 200 MeV +p reactions coherent Bremsstrahlung has been found, dominated by direct capture into the unbound 5 Li ground and first excited state. The dynamic range of the present bremsstrahlung data allows one to test for the first time the consistency of models that attempt to describe these two aspects within a single theoretical framework. In 190 MeV proton-nucleus reactions the influence of the nuclear medium on the photon production has been studied by analyzing coincidences of photons with leading protons. Stronger than at lower incident energies, our data reveal a suppression of the soft-photon yield with respect to the expectation from quasi-free scattering. This effect can partly be attributed to soft-photon quenching due to an interference of photon amplitudes in multiple- collision processes. Other possible mechanisms might be considered such as a medium-modified elementary photon production cross section. The new data indicate the need for a quantum transport theory which includes consistently the medium modifications and the interference phenomena. First results from calculations of Bremsstrahlung production in nuclear matter derived from a realistic NN interaction indicate the suppression of Bremsstrahlung in the soft part of the photon spectrum. An alternative approach based on the formalism of two-particle Greens functions in non-equilibrium matter yields similar results and relates the soft-photon suppression to the scattering properties in nuclear

  17. The free and In medium N-N interaction studied by nuclear Bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Lohner, H.; Van Goethem, M.J.; Hoefman, M.; Wilschut, H.W. [Kernfysisch Versneller Institut, Groningen (Netherlands)

    2001-09-01

    Full text: At the AGOR cyclotron of the KVI a series of Bremsstrahlung measurements has been carried out with proton and c beams using the combination of a highly segmented photon spectrometer (TAPS) with the smallangle large-acceptance detector (SALAD) for charged-particles. High precision cross sections and analysing powers have been measured for p+p Bremsstrahlung with 190 MeV polarized protons. For the first time exclusive differential cross sections of virtual bremsstrahlung could be determined. In 200 MeV +p reactions coherent Bremsstrahlung has been found, dominated by direct capture into the unbound {sup 5} Li ground and first excited state. The dynamic range of the present bremsstrahlung data allows one to test for the first time the consistency of models that attempt to describe these two aspects within a single theoretical framework. In 190 MeV proton-nucleus reactions the influence of the nuclear medium on the photon production has been studied by analyzing coincidences of photons with leading protons. Stronger than at lower incident energies, our data reveal a suppression of the soft-photon yield with respect to the expectation from quasi-free scattering. This effect can partly be attributed to soft-photon quenching due to an interference of photon amplitudes in multiple- collision processes. Other possible mechanisms might be considered such as a medium-modified elementary photon production cross section. The new data indicate the need for a quantum transport theory which includes consistently the medium modifications and the interference phenomena. First results from calculations of Bremsstrahlung production in nuclear matter derived from a realistic NN interaction indicate the suppression of Bremsstrahlung in the soft part of the photon spectrum. An alternative approach based on the formalism of two-particle Greens functions in non-equilibrium matter yields similar results and relates the soft-photon suppression to the scattering properties in

  18. Gas bremsstrahlung studies for medium energy electron storage rings using FLUKA Monte Carlo code

    Science.gov (United States)

    Sahani, Prasanta Kumar; Haridas, G.; Sinha, Anil K.; Hannurkar, P. R.

    2016-02-01

    Gas bremsstrahlung is generated due to the interaction of the stored electron beam with residual gas molecules of the vacuum chamber in a storage ring. As the opening angle of the bremsstrahlung is very small, the scoring area used in Monte Carlo simulation plays a dominant role in evaluating the absorbed dose. In the present work gas bremsstrahlung angular distribution and absorbed dose for the energies ranging from 1 to 5 GeV electron storage rings are studied using the Monte Carlo code, FLUKA. From the study, an empirical formula for gas bremsstrahlung dose estimation was deduced. The results were compared with the data obtained from reported experimental values. The results obtained from simulations are found to be in very good agreement with the reported experimental data. The results obtained are applied in estimating the gas bremsstrahlung dose for 2.5 GeV synchrotron radiation source, Indus-2 at Raja Ramanna Centre for Advanced Technology, India. The paper discusses the details of the simulation and the results obtained.

  19. Effective dose and organ doses due to gas Bremsstrahlung from electron storage rings

    International Nuclear Information System (INIS)

    Bremsstrahlung on residual gas is an important source of beam losses in electron-positron storage rings. The Bremsstrahlung photons are emitted in a narrow cone in the forward direction, which produces a 'hot spot' of dose at the end of a straight section. Estimates of radiation hazard due to gas Bremsstrahlung have so far been performed by calculating the maximum dose equivalent (MADE) or similar quantities. However, the use of quantities conceived for broad parallel beams in the case of very narrow beams significantly overestimates the organ doses and effective dose. In this paper a more sophisticated computational model was used to calculate values of effective dose and absorbed doses in various organs due to gas Bremsstrahlung X-rays generated by 0.1-10 GeV electrons. The Bremsstrahlung photons generated by the interaction of a mono-energetic electron beam in a 1 m long air target were made to impinge on a selected organ of an hermaphrodite anthropomorphic mathematical model placed at 1 and 10 m distances from the end of the target. Organ dose and effective dose were calculated for five representative organs, namely the right eye, ovaries, breast, testes and thyroid. Fits to the calculated values are given, as well as the dependence of photon fluence and dosimetric quantities on various parameters. The results are compared with previous estimates based on MADE and with values of ambient dose equivalent. (authors)

  20. Z-dependence of thick-target bremsstrahlung produced by monoenergetic low-energy electrons

    Science.gov (United States)

    Czarnecki, S.; Short, A.; Williams, S.

    2016-07-01

    The dependence of thick-target bremsstrahlung emitted by low-energy beams of monoenergetic electrons on the atomic number of the target material has been investigated experimentally for incident electron energies of 4.25 keV and 5.00 keV using thick aluminum, copper, silver, tungsten, and gold targets. Experimental data suggest that the intensity of the thick-target bremsstrahlung emitted is more strongly dependent on the atomic number of the target material for photons with energies that are approximately equal to the energy of the incident electrons than at lower energies, and also that the dependence of thick-target bremsstrahlung on the atomic number of the target material is stronger for incident electrons of higher energies than for incident electrons of lower energies. The results of the experiments are compared to the results of simulations performed using the PENELOPE program (which is commonly used in medical physics) and to thin-target bremsstrahlung theory, as well. Comparisons suggest that the experimental dependence of thick-target bremsstrahlung on the atomic number of the target material may be slightly stronger than the results of the PENELOPE code suggest.

  1. Can a many-nucleon structure be visible in bremsstrahlung emission during $\\alpha$ decay?

    CERN Document Server

    Maydanyuk, Sergei P; Zou, Li-Ping

    2015-01-01

    We analyze if the nucleon structure of the $\\alpha$ decaying nucleus can be visible in the experimental bremsstrahlung spectra of the emitted photons which accompany such a decay. We develop a new formalism of the bremsstrahlung model taking into account distribution of nucleons in the $\\alpha$ decaying nuclear system. We conclude the following: (1) After inclusion of the nucleon structure into the model the calculated bremsstrahlung spectrum is changed very slowly for a majority of the $\\alpha$ decaying nuclei. However, we have observed that visible changes really exist for the $^{106}{\\rm Te}$ nucleus ($Q_{\\alpha}=4.29$ MeV, $T_{1/2}$=70 mks) even for the energy of the emitted photons up to 1 MeV. This nucleus is a good candidate for future experimental study of this task. (2) Inclusion of the nucleon structure into the model increases the bremsstrahlung probability of the emitted photons. (3) We find the following tendencies for obtaining the nuclei, which have bremsstrahlung spectra more sensitive to the ...

  2. Vector bremsstrahlung by ultrarelativistic collisions in higher dimensions

    International Nuclear Information System (INIS)

    A classical computation of vector bremsstrahlung in ultrarelativistic gravitational-force collisions of massive point particles is presented in an arbitrary number d of extra dimensions. Our method adapts the post-linear formalism of General Relativity to the multidimensional case. The total emitted energy, as well as its angular and frequency distribution and characteristic values, are discussed in detail. For an electromagnetic mediation propagated in the bulk, the emitted energy Eem of scattering with impact parameter b has magnitude Eem∼e4e′2γd+2 /(m2b3d+3), with dominant frequency ωem∼γ2 /b. For the gravitational force the charge emits via vector field, propagated in the bulk, energy Erad∼[GDm′e]2γd+2 /b3d+3 for d⩾2, with dominant frequency ω∼γ2 /b; and energy Erad∼[G5m′e5]2 γ3ln γ/b6 for d=1, with most of the energy coming from a wide frequency region ω∈[O(γ/b),O(γ2 /b)]. For the UED model with extra space volume V=(2πR)d the emitted energy is EUED∼(bd/V)2Erad. Finally, for the ADD model, including four dimensions, the electromagnetic field living on 3-brane, loses on emission the energy EADD∼[GDm′e]2 γ3 /(Vb2d+3), with characteristic frequency ωADD∼γ/b. The contribution of the low frequency part of the radiation (soft photons) to the total radiated energy is shown to be negligible for all values of d. The domain of validity of the classical result is discussed. The result is analyzed from the viewpoint of the de Witt-Brehme-Hobbs equation (and corresponding equations in higher dimensions). The different frequency domains and their competition mentioned above, may be explained as coming from different terms in this equation. Thus the whole emission process may be naturally split in two sub-processes with drastically different spectral and temporal characteristics

  3. Anomalous inverse bremsstrahlung heating of laser-driven plasmas

    Science.gov (United States)

    Kundu, Mrityunjay

    2016-05-01

    Absorption of laser light in plasma via electron-ion collision (inverse bremsstrahlung) is known to decrease with the laser intensity as I 0 -3/2 or with the electron temperature as T e -3/2 where Coulomb logarithm ln Λ = 0.5ln(1 + k 2 min/k 2 max) in the expression of electron-ion collision frequency v ei is assumed to be independent of ponderomotive velocity v 0 = E0/ω which is unjustified. Here k -1 min = v th/max(ω, ω p), and k -1 max = Z/v 2 th are maximum and minimum cut-off distances of the colliding electron from the ion, v th = √T e is its thermal velocity, ω, ω p are laser and plasma frequency. Earlier with a total velocity v = (v 2 0 + v 2 th)1/2 dependent ln Λ(v) it was reported that v ei and corresponding fractional laser absorption (α) initially increases with increasing intensity, reaches a maximum value, and then fall according to the conventional I 0 -3/2 scaling. This anomalous increase in v ei and α may be objected due to an artifact introduced in ln Λ(v) through k-1 min ∝ v. Here we show similar anomalous increase of v ei and α versus I 0 (in the low temperature and under-dense density regime) with quantum and classical kinetic models of v ei without using ln Λ, but a proper choice of the total velocity dependent inverse cut-off length kmax -1 ∝ v 2 (in classical case) or kmax ∝ v (in quantum case). For a given I 0 15 eV, anomalous growth of vei and a disappear. The total velocity dependent k max in kinetic models, as proposed here, may explain anomalous increase of a with I 0 measured in some earlier laser-plasma experiments. This work may be important to understand collisional absorption in the under-dense pre-plasma region due to low intensity pre-pulses and amplified spontaneous emission (ASE) pedestal in the context of laser induced inertial confinement fusion.

  4. Impact of Nucleon-Nucleon Bremsstrahlung Rates Beyond One-Pion Exchange

    CERN Document Server

    Bartl, Alexander; Janka, Hans-Thomas; Schwenk, Achim

    2016-01-01

    Neutrino-pair production and annihilation through nucleon-nucleon bremsstrahlung is included in current supernova simulations by rates that are based on the one-pion-exchange approximation. Here we explore the consequences of bremsstrahlung rates based on a modern nuclear interactions for proto-neutron star cooling and the corresponding neutrino emission. We find that despite a reduction of the bremsstrahlung emission by a factor of 2-5 in the neutrinospheric region, models with the improved treatment exhibit only $\\lesssim$5% changes of the neutrino luminosities and an increase of $\\lesssim$0.7 MeV of the average energies of the radiated neutrino spectra, with the largest effects for the antineutrinos of all flavors and at late times. Overall, the proto-neutron star cooling evolution is slowed down modestly by $\\lesssim$0.5-1 s.

  5. Bremsstrahlung emission probability in the {alpha} decay of {sup 210}Po

    Energy Technology Data Exchange (ETDEWEB)

    Boie, Hans-Hermann

    2009-06-03

    A high-statistics measurement of bremsstrahlung emitted in the {alpha} decay of {sup 210}Po has been performed. The measured differential emission probabilities, which could be followed up to {gamma}-energies of {proportional_to} 500 keV, allow for the first time for a serious test of various model calculations of the bremsstrahlung accompanied {alpha} decay. It is shown that corrections to the {alpha}-{gamma} angular correlation due to the interference between the electric dipole and quadrupole amplitudes and due to the relativistic character of the process have to be taken into account. With the experimentally derived angular correlation the measured energydifferential bremsstrahlung emission probabilities show excellent agreement with the fully quantum mechanical calculation. (orig.)

  6. Electron spectroscopy at the high-energy endpoint of electron-nucleus bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Hillenbrand, Pierre-Michel [GSI Darmstadt (Germany); Univ. Giessen (Germany); Hagmann, Siegbert [GSI Darmstadt (Germany); Univ. Frankfurt (Germany); Banas, Dariusz [Univ. Kielce (Poland); Brandau, Carsten [Extreme Matter Institute Darmstadt (Germany); Univ. Giessen (Germany); Doerner, Reinhard [Univ. Frankfurt (Germany); De Filippo, Enrico [INFN Catania (Italy); Gumberidze, Alexandre [Extreme Matter Institute Darmstadt (Germany); Guo, Dalong [IMP Lanzhou (China); Univ. Beijing (China); Jakubassa-Amundsen, Doris [Univ. Muenchen (Germany); Lestinsky, Michael; Spillmann, Uwe [GSI Darmstadt (Germany); Litvinov, Yuri [GSI Darmstadt (Germany); Univ. Heidelberg (Germany); Mueller, Alfred; Schippers, Stefan [Univ. Giessen (Germany); Rothard, Hermann [CIRIL GANIL Caen (France); Surzhykov, Andrey [Helmholtz-Institut Jena (Germany); Trotsenko, Sergey [GSI Darmstadt (Germany); Helmholtz-Institut Jena (Germany); Voitkiv, Alexander [MPI-K Heidelberg (Germany); Yerokhin, Vladimir [Petersburg State Univ. (Russian Federation); Stoehlker, Thomas [GSI Darmstadt (Germany); Helmholtz-Institut Jena (Germany); Univ. Jena (Germany)

    2014-07-01

    The high-energy endpoint of electron-nucleus bremsstrahlung has been studied in inverse kinematics: For collisions U{sup 88+}+N{sub 2} → U{sup 88+}+[N{sub 2}{sup +}]{sup *} + e{sup -} + γ the energy distribution of electrons scattered under θ{sub e}{sup lab} = 0 {sup circle} with v{sub e} ∼ v{sub proj} was measured coincident with the bremsstrahlung photons emitted under various angles θ{sub γ}{sup lab}. The triple-differential cross sections provide a stringent test for the fully relativistic theory of electron-nucleus bremsstrahlung. Furthermore the studied process, also termed radiative electron capture to continuum RECC, was compared to the competing processes of non-radiative electron capture to continuum ECC and the electron loss to continuum ELC.

  7. Measurement of gas bremsstrahlung from the insertion device beamlines of the advanced photon source

    International Nuclear Information System (INIS)

    High energy electron storage rings generate energetic bremsstrahlung photons through radiative interaction of the electrons (or positrons) with the residual gas molecules inside the storage ring. The resulting radiation exits at an average emittance angle of (m0c2/E) radian with respect to the electron beam path, where m0c2 is the rest mass of E the electron and E its kinetic energy. Thus, at straight sections of the storage rings, moving electrons will produce a narrow and intense monodirectional photon beam. At synchrotron radiation facilities, where beamlines are channeled out of the storage ring, a continuous gas bremsstrahlung spectrum, with a maximum energy of the electron beam, will be present. There are a number of compelling reasons that a measurement of the bremsstrahlung characteristics be conducted at the Advanced Photon Source (APS) storage ring. Although the number of residual gas molecules present in the storage ring at typical nTorr vacuum is low, because of the long straight paths of the electrons in the storage ring at APS, significant production of bremsstrahlung will be produced. This may pose a radiation hazard. It is then imperative that personnel be shielded from dose rates due to this radiation. There are not many measurements available for gas bremsstrahlung, especially for higher electron beam energies. The quantitative estimates of gas bremsstrahlung from storage rings as evaluated by Monte Carlo codes also have several uncertainties. They are in general calculated for air at atmospheric pressure, the results of which are then extrapolated to typical storage ring vacuum values (of the order of 10-9 Torr). Realistically, the actual pressure profile can vary inside the narrow vacuum chamber. Also, the actual chemical composition of the residual gas inside the storage ring is generally different from that of air

  8. Measurement of gas bremsstrahlung from the insertion device beamlines of the advanced photon source

    Energy Technology Data Exchange (ETDEWEB)

    Pisharody, M.; Job, P.K.; Magill, S. [and others

    1997-03-01

    High energy electron storage rings generate energetic bremsstrahlung photons through radiative interaction of the electrons (or positrons) with the residual gas molecules inside the storage ring. The resulting radiation exits at an average emittance angle of (m{sub 0}c{sub 2}/E) radian with respect to the electron beam path, where m{sub 0}c{sup 2} is the rest mass of E the electron and E its kinetic energy. Thus, at straight sections of the storage rings, moving electrons will produce a narrow and intense monodirectional photon beam. At synchrotron radiation facilities, where beamlines are channeled out of the storage ring, a continuous gas bremsstrahlung spectrum, with a maximum energy of the electron beam, will be present. There are a number of compelling reasons that a measurement of the bremsstrahlung characteristics be conducted at the Advanced Photon Source (APS) storage ring. Although the number of residual gas molecules present in the storage ring at typical nTorr vacuum is low, because of the long straight paths of the electrons in the storage ring at APS, significant production of bremsstrahlung will be produced. This may pose a radiation hazard. It is then imperative that personnel be shielded from dose rates due to this radiation. There are not many measurements available for gas bremsstrahlung, especially for higher electron beam energies. The quantitative estimates of gas bremsstrahlung from storage rings as evaluated by Monte Carlo codes also have several uncertainties. They are in general calculated for air at atmospheric pressure, the results of which are then extrapolated to typical storage ring vacuum values (of the order of 10{sup -9} Torr). Realistically, the actual pressure profile can vary inside the narrow vacuum chamber. Also, the actual chemical composition of the residual gas inside the storage ring is generally different from that of air.

  9. ELBA, Bremsstrahlung Dose from Isotropic Electron Flux on Plane Al Shield

    International Nuclear Information System (INIS)

    1 - Description of problem or function: ELBA takes an incident isotropic electron flux with a given differential energy spectrum and calculates the dose rate received from Bremsstrahlung produced in a plane aluminium shield placed in front of the receiver. There is an option to also calculate the electron dose rate from the same source. 2 - Method of solution: The electron differential spectrum as a function of depth is inferred by assuming that electrons travel straight ahead and that distance travelled and energy are related by a range-energy relationship. The electron dose rate at a given depth is calculated by integrating, over energy and direction, the product of the electron flux, the stopping power, and the appropriate flux- to-dose rate conversion factor. The Bremsstrahlung source is assumed to be plane and isotropic at a given depth. This source is defined as the integral over energy and direction of the product of photon energy, the differential Bremsstrahlung spectrum from electrons of a given energy, and the electron flux differential spectrum. The differential Bremsstrahlung spectrum is derived from the Born approximation cross section multiplied by a correction factor. The Bremsstrahlung dose rate is obtained by integrating, over photon energy and slab volume, the product of the Bremsstrahlung source, photon energy flux-to-dose rate conversion factor, buildup factor, and attenuation kernel. The buildup factor assumed is a plane isotropic buildup factor generate by Monte Carlo calculations. The integrations are performed by evaluating the integrand at the midpoint of each integration step, multiplying by the step width, and summing the result. The incident electron spectrum, dose rate conversion factors, and range formula coefficients are input by the user. The buildup factor information is contained in three Data statements in subroutine BURP. 3 - Restrictions on the complexity of the problem: There are limitations on the dimensions of certain arrays

  10. Evaluation of bremsstrahlung contribution to photon transport in coupled photon-electron problems

    Science.gov (United States)

    Fernández, Jorge E.; Scot, Viviana; Di Giulio, Eugenio; Salvat, Francesc

    2015-11-01

    The most accurate description of the radiation field in x-ray spectrometry requires the modeling of coupled photon-electron transport. Compton scattering and the photoelectric effect actually produce electrons as secondary particles which contribute to the photon field through conversion mechanisms like bremsstrahlung (which produces a continuous photon energy spectrum) and inner-shell impact ionization (ISII) (which gives characteristic lines). The solution of the coupled problem is time consuming because the electrons interact continuously and therefore, the number of electron collisions to be considered is always very high. This complex problem is frequently simplified by neglecting the contributions of the secondary electrons. Recent works (Fernández et al., 2013; Fernández et al., 2014) have shown the possibility to include a separately computed coupled photon-electron contribution like ISII in a photon calculation for improving such a crude approximation while preserving the speed of the pure photon transport model. By means of a similar approach and the Monte Carlo code PENELOPE (coupled photon-electron Monte Carlo), the bremsstrahlung contribution is characterized in this work. The angular distribution of the photons due to bremsstrahlung can be safely considered as isotropic, with the point of emission located at the same place of the photon collision. A new photon kernel describing the bremsstrahlung contribution is introduced: it can be included in photon transport codes (deterministic or Monte Carlo) with a minimal effort. A data library to describe the energy dependence of the bremsstrahlung emission has been generated for all elements Z=1-92 in the energy range 1-150 keV. The bremsstrahlung energy distribution for an arbitrary energy is obtained by interpolating in the database. A comparison between a PENELOPE direct simulation and the interpolated distribution using the data base shows an almost perfect agreement. The use of the data base increases

  11. 89Sr bremsstrahlung single photon emission computed tomography using a gamma camera for bone metastases

    International Nuclear Information System (INIS)

    Strontium-89 chloride (89Sr) bremsstrahlung single photon emission computed tomography (SPECT) imaging was evaluated for detecting more detailed whole body 89Sr distribution. 89Sr bremsstrahlung whole body planar and merged SPECT images were acquired using two-detector SPECT system. Energy window A (100 keV ± 50%) for planar imaging and energy window A plus adjacent energy window B (300 keV ± 50%) for SPECT imaging were set on the continuous spectrum. Thirteen patients with multiple bone metastases were evaluated. Bone metastases can be detected with 99mTc-HMDP whole body planar and merged SPECT images and compared with 89Sr bremsstrahlung whole body planar and merged SPECT images. Based on the location of metastatic lesions seen as hot spots on 99mTc-HMDP images as a reference, the hot spots on 89Sr bremsstrahlung images were divided into the same bone parts as 99mTc-HMDP images (a total of 35 parts in the whole body), and the number of hot spots were counted. We also evaluated the incidence of extra-osseous uptakes in the intestine on 89Sr bremsstrahlung whole body planar images. A total of 195 bone metastatic lesions were detected in both 99mTc-HMDP whole body planar and merged SPECT images. Detection of hot spot lesions in 89Sr merged SPECT images (127 of 195; 66%) was more frequent than in 89Sr whole body planar images (108 of 195; 56%), based on metastatic bone lesions in 99mTc-HMDP whole body planar and merged SPECT images. A large intestinal 89Sr accumulation was detected in 5 of the 13 patients (38%). 89Sr bremsstrahlung-merged SPECT imaging could be more useful for detailed detection of whole body 89Sr distribution than planar imaging. Intestinal 89Sr accumulation due to 89Sr physiologic excretion was detected in feces for 4 days after tracer injection. (author)

  12. Investigation of external bremsstrahlung produced in various elements by beta rays

    International Nuclear Information System (INIS)

    Variation of external bremsstrahlung yield with thickness of some elements with atomic numbers between 13 and 82, is determined by using a Ge(Li) solid-state detector and multi-channel analyzer. It is observed that the thickness which corresponds to the maximum yield is a characteristic of target material. Assuming external bremsstrahlung yield changes with the empirical equation, I = KNZsup(n)exp(-σsub(B)t) suggested by Mudhole, the coefficient σsub(B) has been determined and the possibility of σsub(B) being the mass absorption coefficient is discussed. (author)

  13. Complete gluon bremsstrahlung corrections to the process b -> s l+ l-

    OpenAIRE

    Asatryan, H. H.; Asatrian, H. M.; Greub, C.; M. Walker

    2002-01-01

    In a recent paper, we presented the calculation of the order (alpha_s) virtual corrections to b->s l+ l- and of those bremsstrahlung terms which are needed to cancel the infrared divergences. In the present paper we work out the remaining order(alpha_s) bremsstrahlung corrections to b->s l+ l- which do not suffer from infrared and collinear singularities. These new contributions turn out to be small numerically. In addition, we also investigate the impact of the definition of the charm quark ...

  14. Complete gluon bremsstrahlung corrections to the process b -> s l+ l-

    CERN Document Server

    Asatryan, H H; Greub, Christoph; Walker, M

    2002-01-01

    In a recent paper, we presented the calculation of the order (alpha_s) virtual corrections to b->s l+ l- and of those bremsstrahlung terms which are needed to cancel the infrared divergences. In the present paper we work out the remaining order(alpha_s) bremsstrahlung corrections to b->s l+ l- which do not suffer from infrared and collinear singularities. These new contributions turn out to be small numerically. In addition, we also investigate the impact of the definition of the charm quark mass on the numerical results.

  15. The importance of electron–electron bremsstrahlung for terrestrial gamma-ray flashes, electron beams and electron–positron beams

    International Nuclear Information System (INIS)

    Thunderstorms emit terrestrial gamma-ray flashes with photon energies of up to tens of MeV and electron-positron beams that are created by photons with energies above 1.022 MeV. These photons are produced through the bremsstrahlung process when energetic electrons collide with air molecules. However, presently used cross sections for bremsstrahlung treat only the interaction of the electrons with the nuclei of molecules while we here include their interaction with shell electrons. We simulate the production of energetic photons by a negative stepped lightning leader, and we find that electron–electron bremsstrahlung contributes significantly, although the direct photon emission is less than from electron–nucleus bremsstrahlung. However, electron–electron bremsstrahlung also ejects shell electrons and therefore feeds the electron population above 1 MeV significantly. We find that it hence dominates the photon spectrum of the stepped lightning leader at 10 MeV. (fast track communication)

  16. Modeling of the electron distribution based on bremsstrahlung emission during lower hybrid current drive on PLT

    International Nuclear Information System (INIS)

    Lower hybrid current drive requires the generation of a high energy electron tail anisotropic in velocity. Measurements of bremsstrahlung emission produced by this tail are compared with the calculated emission from reasonable model distributions. The physical basis and the sensitivity of this modeling process are described and the plasma properties of current driven discharges which can be derived from the model are discussed

  17. Determination of the effective charge number of plasma ions from bremsstrahlung in the near infrared

    International Nuclear Information System (INIS)

    The ASDEX Thomson scattering apparatus measures the scattered light of the laserbeam (λ=10640 A) in the near infrared to obtain density and temperature profiles. Furthermore this kind of apparatus can be used to analyse plasma radiation for determining radial Zeff profiles, as has been demonstrated at ASDEX for the first time. This method provides correct results, if the measured plasma radiation consists almost completly of bremsstrahlung. But besides bremsstrahlung the plasma emits recombination and line radiation. As shown by theoretical deliberations, recombination radiation is negligible, but line radiation can't be excluded. Therefore a spectral resolved measurement was performed, which made it possible to choose those of the different spectral measuring ranges of the Thomson scattering apparatus which are influenced least by line radiation. Furthermore the obtained results enables to allow for the remaining line radiation in order to get a radial profile of bremsstrahlung. This profile and the data of the Thomson scattering apparatus is used to determine Zeff. The statistical errors are less then 10% in the plasma centre. There is a good agreement between Zeff-profiles obtained by bremsstrahlung and the results of the charge exchange recombination spectroscopy. (orig.)

  18. Dilepton bremsstrahlung from pion-pion scattering in a relativistic one boson exchange model

    International Nuclear Information System (INIS)

    We have made a detailed and quantitative study of dilepton production via bremsstrahlung of a virtual photon during collisions of two free pions. Most calculations of electromagnetic radiation from strong interaction processes rely on the soft photon approximation (SPA). The conditions underlying this approximation are generally violated when dilepton spectra are calculated in terms of their invariant mass, so that an approach going beyond the SPA becomes necessary. Superseding previous derivations, we derive an exact formula for the bremsstrahlung cross section. The resulting formulation is compared to various forms based on the SPA, the two-particle phase space approximation, and Rueckl close-quote s formula using a relativistic one boson exchange (OBE) model. Within the OBE approach, we show that approximations to the bremsstrahlung dilepton cross sections often differ greatly from the exact result; discrepancies become greater both with rising temperature and with invariant mass. Integrated dilepton production rates are overestimated by Rueckl-based approximations by factors 1.5 endash 8.0. The largest discrepancies occur for the reaction π+π+→π+π+l+l-, where such approximations overestimate the exact rate by factors ranging from 2 to 30 for invariant masses between 10 and 500 MeV. Our findings, combined with recent estimates of the Landau-Pomeranchuk effect, indicate that bremsstrahlung dilepton rates in ultrarelativistic heavy ion collisions should be even more suppressed than had been thought before. copyright 1996 The American Physical Society

  19. Bremsstrahlung polarization correlations and their application for polarimetry of electron beams

    International Nuclear Information System (INIS)

    The correlation between electron spin and photon linear polarization in atomic-field bremsstrahlung was measured with a polarized electron beam. The angle of photon polarization and the photon emission intensity were found to be correlated with the spin orientation. These effects are interpreted in terms of spin-orbit interaction. They lead to a new technique of electron beam polarimetry.

  20. THE BREMSSTRAHLUNG ISOCHROMAT SPECTRA OF D(0) TRANSITION-METAL OXIDES

    NARCIS (Netherlands)

    SORIANO, L; ABBATE, M; ALDERS, D; SANZ, JM

    1994-01-01

    We present and discuss the bremsstrahlung isochromat spectra (BIS) of four d0 transition-metal oxides, namely ZrO2, HfO2, Nb2O5, and Ta2O5. The spectra are related to the density of unoccupied states in the conduction band. They give directly the magnitude of the crystal-field splitting and the disp

  1. Bremsstrahlung from relativistic bare heavy ions: Nuclear and electronic contributions in amorphous and crystalline materials

    DEFF Research Database (Denmark)

    Jensen, Tue Vissing; Sørensen, Allan Hvidkjær

    2013-01-01

    A charged particle emits bremsstrahlung while traversing matter. We calculate the radiation cross section for bare heavy ions penetrating amorphous materials and single crystals at highly relativistic energies. The main component originates in scattering of the virtual photons of screened target...... a pronounced directional dependence of the energy loss of bare heavy ions at extreme relativistic energies....

  2. Virtual-bremsstrahlung production in proton-proton scattering and proton-deuteron capture

    NARCIS (Netherlands)

    Messchendorp, Johannes Gerhardus

    1999-01-01

    The well-known coupling of the photon with the nucleon together with the fact that photons (or any electromagnetic (e.m.) probe) interact only relatively weakly with nucleons, make bremsstrahlung production an ideal tool to study details of the nucleon-nucleon interaction. In this thesis dilepton pr

  3. EFFECTS OF MESON-DECAY DIAGRAMS IN PROTON-PROTON BREMSSTRAHLUNG

    NARCIS (Netherlands)

    DEJONG, F; NAKAYAMA, K

    1995-01-01

    We investigate the effect of meson-decay diagrams on the proton-proton bremsstrahlung process. We explicitly include short-range correlations by calculating single- and double-scattering diagrams using an NN T-matrix interaction. We find that in general these diagrams interfere destructively with th

  4. Bremsstrahlung from Electrons and Positrons in Peripheral Relativistic Heavy Ion Collisions

    OpenAIRE

    Hencken, Kai; Trautmann, Dirk; Baur, Gerhard

    1999-01-01

    We study the spectrum of the bremsstrahlung photons coming from the electrons and positrons, which are produced in the strong electromagnetic fields present in peripheral relativistic heavy ion collisions. We compare different approaches, making use of the exact pair production cross section in heavy ion collisions as well as the double equivalent photon approximation.

  5. Absolute intensity of internal bremsstrahlung from the electron capture decay of 125I

    International Nuclear Information System (INIS)

    The absolute intensity of the internal bremsstrahlung spectrum accompanying the electron capture decay of 125I has been measured and compared to the recent calculation of Suric et al. The measured intensity above the 1s end point is found to be (86±10)% of the calculated intensity

  6. An accurate absolute-scale measurement of bremsstrahlung following absorption of incident X and γ rays

    International Nuclear Information System (INIS)

    The spectrum of bremsstrahlung due to photoelectrons ejected by incident photons of energy 59.5 keV was measured. The coincidence setup with two HP germanium detectors was applied, in which the target-detector recorded the energy of ejected photoelectron after it radiated a bremsstrahlung photon, and another (second) detector detected energy of radiated bremsstrahlung photon. A detailed analysis of the measurement was made taking into account various detector-to-detector cross-talk processes. As expected, the experimental method gave a clean spectrum, which can be reliably determined on absolute scale in the low- and mid-energy range. The condition for reliable measurement are that the asymmetry ratio (the ratio of number of incident photons which reached the target detector and the second detector) is higher than approximately 1000 to reduce reverse-Compton scattering, and solid angle is smaller than about 0.15 sr to reduce the influence of double-cross-talk processes. (We name a group of processes double-cross-talk processes in which incident radiation produces secondary radiation in target detector, the secondary radiation escapes it and reaches the second detector where it induces tertiary radiation, which reaches the target detector and is absorbed therein.) Almost any line source of photons can be used even if of a complex spectrum. Therefore, simultaneous measurements at several incident energies are possible in one experiment. Application of a very weak source is possible because of very high signal-to-background ratio and high efficiency of the applied experimental method. The simple theoretical model of bremsstrahlung radiation due to photoelectrons in infinity-thick target gives results in a good agreement with the experimental data. The bremsstrahlung cross-section calculated using the well-known semi-empirical thick-target formula gives also a good agreement with the experimental data. (author)

  7. Estimation of Electron Dose Delivered by a 0.4 MeV Accelerator from Bremsstrahlung Dose Measurements

    DEFF Research Database (Denmark)

    Karadjov, A. G.; Hansen, Jørgen-Walther

    1980-01-01

    Determination of a 0.4 MeV electron dose from a bremsstrahlung dose measurement using a converter-detector system is considered. The detector used is a Frickle dosimeter, and the converters are aluminum, copper and lead foils. Optimal converter thickness is ascertained experimentally for each...... material, namely: Al, 0.13 g/cm2; Cu, 0.06 g/cm2; and Pb, 0.045 g/cm2. The corresponding peak bremsstrahlung doses at 20 Mrad electron dose in water are 376,460 and 940 rad, respectively. A relation is given enabling prediction of optimal converter thickness and peak bremsstrahlung dose for converter...

  8. Measurement of gas Bremsstrahlung at the Pohang Light Source by using a CeF3 scintillator

    International Nuclear Information System (INIS)

    We have measured the gas Bremsstrahlung photon energy from the 2.5-GeV electron storage ring at the Pohang Light Source (PLS). Gas Bremsstrahlung was generated in the straight section of the beam-diagnosis beamline 1C1 with an effective length of 5.3 m. We present the measurement results for the Bremsstrahlung photon energy spectrum and the photon flux, which were obtained by using a CeF3 calorimeter. The calorimeter consisted of nine CeF3 blocks, each being 3.3 x 3.3 x 33 cm3, stacked into a 3 x 3 array. The Bremsstrahlung photon flux above 40 MeV was measured to be 218 s-1 at an electron beam current of 180 mA.

  9. Experimental and analytical study of the bremsstrahlung radiation production at low energies

    International Nuclear Information System (INIS)

    The bremsstrahlung photon beam from an X-ray tube with chromium anode has been studied, for an electron energy of 60 Kev. In the experimental step, a new measurement method has been developed. This is based on the detection and measurement of the fluorescence produced when the photons from the tube impinge on targets which are used as calibrated flux monitors. The composition and physical characteristics of the targets are well-known. In the steps of experimental data treatment, an analytical study of the theoretical models describing thick target bremsstrahlung yield is performed. A factorization which accounts for the elemental physical processes is obtained, employing simple mathematical functions. The characteristic parameters found in the numerical fit process lead to results in good agreement with the experimental observations from other authors and predict theoretical exposure values in perfect agreement with the exposures measured for X-ray beams generated in several operating conditions. (author)

  10. Bremsstrahlung from relativistic heavy ions in a fixed target experiment at the LHC

    CERN Document Server

    Mikkelsen, Rune E; Uggerhøj, Ulrik I

    2015-01-01

    We calculate the emission of bremsstrahlung from lead and argon ions in A Fixed Target ExpeRiment (AFTER) that uses the LHC beams. With nuclear charges of $Ze$ equal $208$ and $18$ respectively, these ions are accelerated to energies of $7$ TeV$\\times Z $. The bremsstrahlung peaks around $\\approx 100$ GeV and the spectrum exposes the nuclear structure of the incoming ion. The peak structure is significantly different from the flat power spectrum pertaining to a point charge. Photons are predominantly emitted within an angle of $1/\\gamma$ to the direction of ion propagation. Our calculations are based on the Weizs\\"{a}cker-Williams method of virtual quanta with application of existing experimental data on photonuclear interactions.

  11. Photon bremsstrahlung from quark jet via transverse and longitudinal scatterings: single versus multiple scatterings

    CERN Document Server

    Zhang, Le; Qin, Guang-You

    2016-01-01

    We study the production of jet-bremsstrahlung photons through the scattering with the constituents of a dense nuclear matter within the framework of deep-inelastic scattering off a large nucleus. Applying a gradient expansion up to the second order for the exchanged three-dimensional momentum between jet and medium, we derive the single photon bremsstrahlung spectrum with the inclusion of the contributions from the transverse broadening as well as the longitudinal drag and diffusion of the hard parton's momentum. We also compare the medium-induced photon radiation spectra for single scattering and from the resummation of multiple scatterings. It is found that the coupling between different scatterings can give additional contribution to medium-induced photon radiation, while for small momentum exchange, the leading contribution from the drag and diffusions to the photon emission spectra remain the same for single and multiple scatterings.

  12. Determination of effective bremsstrahlung spectra and electron contamination for photon dose calculations

    International Nuclear Information System (INIS)

    A method is described for determining an effective, depth dose consistent bremsstrahlung spectra for high-energy photon beams using depth dose curves measured in water. A simple, analytical model with three parameters, together with the nominal accelerating potential is used to characterise the bremsstrahlung spectra. The model is used to compute weights for depth dose curves from monoenergetic photons. These monoenergetic depth doses, calculated with the convolution method from Monte Carlo generated point spread functions (PSF), are added to yield the pure photon depth dose distribution. The parameters of the analytical spectrum model are determined using an iterative technique to minimise the difference between calculated and measured depth dose curves. The influence from contaminant electrons is determined from the difference between the calculated and the measured depth dose. (author)

  13. Indigenous facility development for studying an elementary radiation process: atomic-field Bremsstrahlung

    International Nuclear Information System (INIS)

    An indigenous setup for studying the process of atomic-field Bremsstrahlung produced from the interaction of keV electrons with a solid or a gaseous target has been developed and described. The setup consists of a high-vacuum scattering chamber, a home-built keV electron gun with a replaceable tungsten filament cathode, an isolated floating high-voltage control unit, signal processing electronic modules and a data-acquisition system comprising of an IBM PC/XT 4-K multichannel analyser. The performance of the setup has been tested and used for accumulating data for Bremsstrahlung spectra from 7.0 keV electrons incident on thin Ag and Au targets. These spectra have been analyzed and discussed in light of the semiclassical and the quantum calculations. The agreement between experiment and theory is found to be satisfactory within the experimental uncertainty of the measurements. (author). 10 refs., 5 figs., 1 tab

  14. Effect of Degenerated Particles on Internal Bremsstrahlung of Majorana Dark Matter

    CERN Document Server

    Okada, Hiroshi

    2014-01-01

    Gamma-ray generated by annihilation or decay of dark matter can be its smoking gun signature. In particular, gamma-ray coming from internal bremsstrahlung of dark matter is promising since it can be a leading emission of sharp gamma-ray. However if thermal production of Majorana dark matter is considered, the derived cross section for internal bremsstrahlung becomes too small to be observed by future gamma-ray experiments. We consider a framework to achieve an enhancement of the cross section by taking into account degenerated particles with dark matter. We find that the enhancement of about order one is possible without conflict with the dark matter relic density. Due to the enhancement, it would be tested by the future experiments such as GAMMA-400 and CTA.

  15. Modeling the Bremsstrahlung of 30-60 MeV electrons. Source term calculation

    International Nuclear Information System (INIS)

    The photofission process has been recently considered for the production of neutron rich isotopes and the development of radioactive beams. The radioprotection hazard should be studied accordingly. A survey of the radiative electron energy loss theory is reported in order to estimate numerically the Bremsstrahlung production of thick targets. The resulted Bremsstrahlung angular and energy theoretical distributions delivered from W and UCx thick converters are presented and compared with previous results. This study is focused on initial kinetic energies of the electron beam included in the range 30-60 MeV, suitable for the production of large photon yields able to induce the 238U fission. The source term for 50 MeV incident electrons is reported for radioprotection purposes. (authors)

  16. Dose topography of the sample, analyzed by the Bremsstrahlung irradiation on microtron

    International Nuclear Information System (INIS)

    In the radiation experiments on microtron, there are difficulties in determination of exposition and absorbed doses of electron Bremsstrahlung (EB) in irradiated samples. Bremsstrahlung is characterized by anisotropy and therefore one has to take into account the geometry of irradiation. According to our measured differential spectra of EB from thick tungsten target at the electron beam energy of 11.8; 13; 20 MeV it is possible to determine the distribution of doses in front hemisphere, where the sample is usually irradiated. The spectral and angular transformation of EB spectra into doses was done using interpolation and extrapolation. For the determination of absorbed doses in sample of known micro-composition, one can use the values of exposition doses, for which the EB spectrum is used in 'monoenergetic' type

  17. Studies of nucleon-nucleon potentials with pp- and np-Bremsstrahlung

    International Nuclear Information System (INIS)

    A comprehensive study of pp and np bremsstrahlung based upon the potential model formalism was initiated to explore properties of two nucleon t-matrices. Underlying potentials of t-matrices either were generated by Gelfand-Levitan-Marchenko inversion of the latest NN phase shifts or are the Paris and Bonn-R potentials. The bremsstrahlung amplitudes associated with external, internal and exchange currents, by exact treatment of the Coulomb potential in on- and half-off-shell t-matrices, and the relativistic spin corrections were all computed and for both coplanar and non coplanar geometries. The results are a successful analysis of ppγ TRIUMF data and allow us to set experimental boundaries for planned new experiments. They also give a perspective of the off-shell t-matrix information inherent in this reaction. (orig.)

  18. Bayesian analysis of the effective charge from spectroscopic bremsstrahlung measurement in fusion plasmas

    Science.gov (United States)

    Krychowiak, M.; König, R.; Klinger, T.; Fischer, R.

    2004-11-01

    At the stellarator Wendelstein 7-AS (W7-AS) a spectrally resolving two channel system for the measurement of line-of-sight averaged Zeff values has been tested in preparation for its planned installation as a multichannel Zeff-profile measurement system on the stellarator Wendelstein 7-X (W7-X) which is presently under construction. The measurement is performed using the bremsstrahlung intensity in the wavelength region of ultraviolet to near infrared. The spectrally resolved measurement allows to eliminate signal contamination by line radiation. For statistical data analysis a procedure based on Bayesian probability theory has been developed. With this method it is possible to estimate the bremsstrahlung background in the measured signal and its error without the necessity to fit the spectral lines. For evaluation of the random error in Zeff the signal noise has been investigated. Furthermore, the linearity and behavior of the charge-coupled device detector at saturation has been analyzed.

  19. Investigation of the partner-potentials from supersymmetric quantum mechanics by bremsstrahlung

    International Nuclear Information System (INIS)

    With the explicit example of α + α scattering we emphasize the incompleteness of using just the on-shell properties in any inversion procedure. A deep, energy-independent and angular-momentum-independent effective local potential is constructed to reproduce the phase shifts from a single-configuration microscopic resonating-group method (RGM) calculation for α + α scattering up to E = 16 MeV. From this we derive its phase-shift-equivalent shallow supersymmetric partner-potentials by eliminating the bound states which are unphysical due to the Pauli principle. These deep and shallow potentials are used to calculate bremsstrahlung emission in α + α collision and compared with the results from RGM as a means to investigate their wave functions. While the bremsstrahlung cross sections from RGM and the deep potential resemble each other, those of the shallow potentials are distinctly different. (orig.)

  20. Observation of coherent bremsstrahlung in quasicrystalline Al-Cu-Co-Si

    International Nuclear Information System (INIS)

    Quasicrystalline Al-Cu-Co-Si was irradiated with 200 and 400 keV electrons approximately along the zone axes. Under these conditions the X-ray spectrum contains, apart from characteristic X-ray lines, additional peaks. From the dependence of the peak energies on the kinetic electron energy it is concluded that these lines stem from coherent bremsstrahlung. The ratio of some peak energies is very close to the golden mean τ=(51/2 + 1)/2. These measurements show that atoms in quasicrystalline Al-Cu-Co-Si are arranged in fairly well defined planes. It is confirmed for the first time that for the generation of coherent bremsstrahlung a periodic arrangement of atoms is not essential. (author)

  1. An algorithm to include the bremsstrahlung component in the determination of the absorbed dose in electron beams

    International Nuclear Information System (INIS)

    Currently used dosimetry protocols for absolute dose determination of electron beams from accelerators in radiation therapy do not account for the effect of the bremsstrahlung contamination of the beam. This results in slightly erroneous doses calculated from ionization chamber measurements. In this report the deviation is calculated and an improved algorithm, which accounts for the effect of the bremsstrahlung component of the beam, is suggested. (author). 14 refs, 2 figs, 1 tab

  2. Monte Carlo simulation and analytical calculation of coherent Bremsstrahlung and its polarisation

    Energy Technology Data Exchange (ETDEWEB)

    Natter, F.A.; Grabmayr, P. E-mail: grabmayr@uni-tuebingen.de; Hehl, T.; Owens, R.O.; Wunderlich, S

    2003-12-01

    Spectral distributions for coherent and incoherent Bremsstrahlung produced by electrons on thin diamond radiators are calculated accurately by a Monte Carlo procedure. Realistic descriptions of the electron beam and the physical processes within the radiator have been implemented. Results are compared to measured data. A faster calculation at only a slight loss of precision is possible using analytical expressions which can be derived after simplifying assumptions.

  3. An instrument for the investigation of actinides with spin resolved photoelectron spectroscopy and bremsstrahlung isochromat spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yu, S.-W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tobin, J. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chung, B. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2011-01-01

    A new system for spin resolved photoelectron spectroscopy and bremsstrahlung isochromat spectroscopy has been built and commissioned at Lawrence Livermore National Laboratory for the investigation of the electronic structure of the actinides.Actinide materials are very toxic and radioactive and therefore cannot be brought to most general user facilities for spectroscopic studies. The technical details of the new system and preliminary data obtained therein will be presented and discussed.

  4. Dynamical diffraction theory for the parametric X-rays and coherent bremsstrahlung

    OpenAIRE

    Feranchuk, Ilya D.; Lugovskaya, O.; Ulyanenkov, A.

    2005-01-01

    The various mechanisms of X-ray radiation from relativistically charged particles in a crystal are analyzed from a common point of view, based on quantum electrodynamics in a medium. Parametric X-rays (PXR), diffraction radiation (DR) and coherent bremsstrahlung (CB) lead to different contributions to the amplitude of the radiation process but because of their interference they cannot be considered separately in the radiation intensity. The role of the dynamical diffraction effect...

  5. The internal bremsstrahlung accompanying the β-dacay from 185W

    International Nuclear Information System (INIS)

    The internal bremsstrahlung (IB) spectrum accompanying the β-decay from 185W radionuclide has been measured. The obtained spectrum was analyzed into its constituting gamma lines taking into account all the proper corrections. The analyzed spectrum was compared with those theoretically calculated. The experimental results for the IB probability were found to be in good agreement with theoretical calculations especially with the shape corrected modified KUB theory of Nilsson up to 357.7 keV. (author)

  6. Interference Peak in the Spectrum of Bremsstrahlung on Two Amorphous Targets

    OpenAIRE

    Bondarenco, M. V.; Shul'ga, N. F.

    2014-01-01

    We investigate the interference pattern in the spectrum of non-dipole bremsstrahlung on two amorphous foils. Apart from suppression at lowest $\\omega$, the spectrum exhibits an enhancement adjacent to it. In classical electrodynamics, the net effect of suppression and enhancement proves to be zero. We study the location and the origin of the spectral features, comparing predictions of full Moli\\`ere averaging with those of the Gaussian averaging with Coulomb corrections to the rms multiple sc...

  7. Self-absorption correction factor for a sample excited by the bremsstrahlung radiation

    International Nuclear Information System (INIS)

    A method of calculating the self-absorption correction factor for fluorescent X-rays from a sample excited by the bremsstrahlung has been described. As a typical example, the correction factors for Kα of Si and Cu for different tube voltages have been calculated. Polynomial fit of the correction factor against the tube voltage in the range 10-100 kV has been given for both the elements

  8. Possibility of 117mSn production using high-energy electron bremsstrahlung

    International Nuclear Information System (INIS)

    The method of 117mSn production using an electron accelerator is described and its photonuclear reaction yield and specific activities for 117mSn and enriched isotope 118Sn are estimated. The specific activities and photonuclear reaction yields of 117mSn and 111In are also estimated using the high-energy electron bremsstrahlung of the linear electron accelerator of the IREN facility, FLNP, JINR at irradiation of high-purity tin targets

  9. Screening effect on the inverse bremsstrahlung in a plasma in the presence of two laser fields

    International Nuclear Information System (INIS)

    The effect of Coulomb screening on the inverse bremsstrahlung heating process in a plasma illuminated by two laser fields is discussed. It is shown that, although the screening effect actually lowers the Coulomb interaction, one might accomplish a reduction of the weakening effect and consequently and enhancement of the collisional plasma heating, by illuminating the plasma with the two electromagnetic waves having a differnce in frequency close to the plasma frequency. (M.W.O.)

  10. Integrated Bayesian Estimation of Zeff in the TEXTOR Tokamak from Bremsstrahlung and CX Impurity Density Measurements

    International Nuclear Information System (INIS)

    The validation of diagnostic date from a nuclear fusion experiment is an important issue. The concept of an Integrated Data Analysis (IDA) allows the consistent estimation of plasma parameters from heterogeneous data sets. Here, the determination of the ion effective charge (Zeff) is considered. Several diagnostic methods exist for the determination of Zeff, but the results are in general not in agreement. In this work, the problem of Zeff estimation on the TEXTOR tokamak is approached from the perspective of IDA, in the framework of Bayesian probability theory. The ultimate goal is the estimation of a full Zeff profile that is consistent both with measured bremsstrahlung emissivities, as well as individual impurity spectral line intensities obtained from Charge Exchange Recombination Spectroscopy (CXRS). We present an overview of the various uncertainties that enter the calculation of a Zeff profile from bremsstrahlung date on the one hand, and line intensity data on the other hand. We discuss a simple linear and nonlinear Bayesian model permitting the estimation of a central value for Zeff and the electron density ne on TEXTOR from bremsstrahlung emissivity measurements in the visible, and carbon densities derived from CXRS. Both the central Zeff and ne are sampled using an MCMC algorithm. An outlook is given towards possible model improvements

  11. Thermal Bremsstrahlung probing nuclear multifragmentation in nucleus-nucleus collisions around the Fermi energy

    International Nuclear Information System (INIS)

    The thermodynamical properties of nuclear matter at moderate temperatures and densities, in the vicinity of the predicted nuclear liquid-gas phase transition, are studied using as experimental probe the hard-photons (Eγ > 30 MeV) emitted in nucleus-nucleus collisions. Photon and charged-particle production in four different heavy-ion reactions (Ar36 + Au197, Ag107, Ni58, C12 at 60 A*MeV) is measured exclusively and inclusively coupling the TAPS photon spectrometer with two charged-particle and intermediate-mass-fragment detectors covering nearly 4π. We confirm that Bremsstrahlung emission in first-chance (off-equilibrium) proton-neutron collisions (pnγ) is the dominant origin of hard photons. We also firmly establish the existence of a thermal radiation component emitted in second-chance proton-neutron collisions. This thermal Bremsstrahlung emission takes place in semi-central and central nucleus-nucleus reactions involving heavy targets. We exploit this observation i) to demonstrate that thermal equilibrium is reached during the reaction, ii) to establish a new thermometer of nuclear matter based on Bremsstrahlung photons, iii) to derive the thermodynamical properties of the excited nuclear sources and, in particular, to establish a 'caloric curve' (temperature versus excitation energy), and iv) to assess the time-scales of the nuclear break-up process. (author)

  12. Dose calculation and measurement for bremsstrahlung at BL18U beamline of SSRF

    International Nuclear Information System (INIS)

    Background: Gas bremsstrahlung is one of the most important radiation sources that needs to be taken into consideration for shielding design of beamlines at the third generation synchrotron radiation light source. Shanghai Synchrotron Radiation Facility (SSRF) is one of the third generation synchrotron radiation light source in the world. The Protein Micro-crystallography Beamline (BL18U) is one of the commissioning beamlines and is a representative insertion device beamline at SSRF. Purpose: Estimation of radiation dose induced by scattering bremsstrahlung and photoneutrons at BL18U. Methods: Dose rate distribution induced by scattering bremsstrahlung and photoneutrons at BL18U are performed by Monte Carlo simulation code FLUKA. The radiation dose was analyzed with the variation of slits size, beam current at storage ring and the vacuum. Dose rate of photons and photoneutrons at the outside of the optical enclosure of BL18U were measured by using high sensitivity photon and neutron monitors. Results: The measurement results show that the reliability of the simulation. Conclusion: The simulation and measurement methods presented in this study can be applied to evaluate the dose rate level of other beamline stations at SSRF, and provide references to the shielding design for the following beamlines at SSRF in the near future. (authors)

  13. Hard X-ray bremsstrahlung production in solar flares by high-energy proton beams

    Science.gov (United States)

    Emslie, A. G.; Brown, J. C.

    1985-01-01

    The possibility that solar hard X-ray bremsstrahlung is produced by acceleration of stationary electrons by fast-moving protons, rather than vice versa, as commonly assumed, was investigated. It was found that a beam of protons which involves 1836 times fewer particles, each having an energy 1836 times greater than that of the electrons in the equivalent electron beam model, has exactly the same bremsstrahlung yield for a given target, i.e., the mechanism has an energetic efficiency equal to that of conventional bremsstrahlung models. Allowance for the different degrees of target ionization appropriate to the two models (for conventional flare geometries) makes the proton beam model more efficient than the electron beam model, by a factor of order three. The model places less stringent constraints than a conventional electron beam model on the flare energy release mechanism. It is also consistent with observed X-ray burst spectra, intensities, and directivities. The altitude distribution of hard X-rays predicted by the model agrees with observations only if nonvertical injection of the protons is assumed. The model is inconsistent with gamma-ray data in terms of conventional modeling.

  14. Optimal design of Anger camera for bremsstrahlung imaging: Monte Carlo evaluation.

    Directory of Open Access Journals (Sweden)

    Stephan eWalrand

    2014-06-01

    Full Text Available A conventional Anger camera is not adapted to bremsstrahlung imaging and, as a result, even using a reduced energy acquisition window, geometric x-rays represent less than 15% of the recorded events. This increases noise, limits the contrast, and reduces the quantification accuracy.Monte Carlo simulations of energy spectra showed that a camera based on a 30mm-thick BGO crystal and equipped with a high energy pinhole collimator is well adapted to bremsstrahlung imaging. The total scatter contamination is reduced by a factor ten versus a conventional NaI camera equipped with a high energy parallel hole collimator enabling acquisition using an extended energy window ranging from 50 to 350 keV. By using the recorded event energy in the reconstruction method, shorter acquisition time and reduced orbit range will be usable allowing the design of a simplified mobile gantry. This is more convenient for use in a busy catheterization room. After injecting a safe activity, a fast SPECT could be performed without moving the catheter tip in order to assess the liver dosimetry and estimate the additional safe activity that could still be injected.Further long running time Monte Carlo simulations of realistic acquisitions will allow assessing the quantification capability of such system. Simultaneously, a dedicated bremsstrahlung prototype camera reusing PMT-BGO blocks coming from a retired PET system is currently under design for further evaluation.

  15. Investigation of Coulombic bremsstrahlung spectra of metallic targets for the photon energy region of 1-100keV.

    Science.gov (United States)

    Singh, Amrit; Dhaliwal, A S

    2016-09-01

    In the present paper, the formation of bremsstrahlung spectra by ordinary bremsstrahlung (OB) and polarization bremsstrahlung (PB) in metallic targets by (35)S beta particles has been investigated in the photon energy region of 1-100keV. From the experimental measurements and the theoretical results obtained from Elwert corrected (non-relativistic) Bethe Heitler (EBH) theory, modified Elwert factor (relativistic) (FmodBH) theories for OB and Avdonina and Pratt (FmodBH+PB) theory for total bremsstrahlung (BS) having the contribution of PB into OB, it has been found that the contribution of PB into BS in a target is limited to a low energy region only and also varies with the atomic number of target material. The FmodBH+PB theory is in agreement with the experimental results in low energy regions of the target, whereas at high energy region FmodBH is found to give better agreement. Further, the present experimental results indicate that the screening effects in the Coulombic bremsstrahlung process cannot be neglected in the high energy region, and the multiple scattering and secondary electron emissions effects in thick target are required to be taken into account in describing the bremsstrahlung process. PMID:27400163

  16. MAGNET

    CERN Multimedia

    by B. Curé

    2011-01-01

    The magnet operation was very satisfactory till the technical stop at the end of the year 2010. The field was ramped down on 5th December 2010, following the successful regeneration test of the turbine filters at full field on 3rd December 2010. This will limit in the future the quantity of magnet cycles, as it is no longer necessary to ramp down the magnet for this type of intervention. This is made possible by the use of the spare liquid Helium volume to cool the magnet while turbines 1 and 2 are stopped, leaving only the third turbine in operation. This obviously requires full availability of the operators to supervise the operation, as it is not automated. The cryogenics was stopped on 6th December 2010 and the magnet was left without cooling until 18th January 2011, when the cryoplant operation resumed. The magnet temperature reached 93 K. The maintenance of the vacuum pumping was done immediately after the magnet stop, when the magnet was still at very low temperature. Only the vacuum pumping of the ma...

  17. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    Operation of the magnet has gone quite smoothly during the first half of this year. The magnet has been at 4.5K for the full period since January. There was an unplanned short stop due to the CERN-wide power outage on May 28th, which caused a slow dump of the magnet. Since this occurred just before a planned technical stop of the LHC, during which access in the experimental cavern was authorized, it was decided to leave the magnet OFF until 2nd June, when magnet was ramped up again to 3.8T. The magnet system experienced a fault also resulting in a slow dump on April 14th. This was triggered by a thermostat on a filter choke in the 20kA DC power converter. The threshold of this thermostat is 65°C. However, no variation in the water-cooling flow rate or temperature was observed. Vibration may have been the root cause of the fault. All the thermostats have been checked, together with the cables, connectors and the read out card. The tightening of the inductance fixations has also been checked. More tem...

  18. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      Following the unexpected magnet stops last August due to sequences of unfortunate events on the services and cryogenics [see CMS internal report], a few more events and initiatives again disrupted the magnet operation. All the magnet parameters stayed at their nominal values during this period without any fault or alarm on the magnet control and safety systems. The magnet was stopped for the September technical stop to allow interventions in the experimental cavern on the detector services. On 1 October, to prepare the transfer of the liquid nitrogen tank on its new location, several control cables had to be removed. One cable was cut mistakenly, causing a digital input card to switch off, resulting in a cold-box (CB) stop. This tank is used for the pre-cooling of the magnet from room temperature down to 80 K, and for this reason it is controlled through the cryogenics control system. Since the connection of the CB was only allowed for a field below 2 T to avoid the risk of triggering a fast d...

  19. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet was energised at the beginning of March 2012 at a low current to check all the MSS safety chains. Then the magnet was ramped up to 3.8 T on 6 March 2012. Unfortunately two days later an unintentional switch OFF of the power converter caused a slow dump. This was due to a misunderstanding of the CCC (CERN Control Centre) concerning the procedure to apply for the CMS converter control according to the beam-mode status at that time. Following this event, the third one since 2009, a discussion was initiated to define possible improvement, not only on software and procedures in the CCC, but also to evaluate the possibility to upgrade the CMS hardware to prevent such discharge from occurring because of incorrect procedure implementations. The magnet operation itself was smooth, and no power cuts took place. As a result, the number of magnetic cycles was reduced to the minimum, with only two full magnetic cycles from 0 T to 3.8 T. Nevertheless the magnet suffered four stops of the cryogeni...

  20. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet was successfully operated at the end of the year 2009 despite some technical problems on the cryogenics. The magnet was ramped up to 3.8 T at the end of November until December 16th when the shutdown started. The magnet operation met a few unexpected stops. The field was reduced to 3.5 T for about 5 hours on December 3rd due to a faulty pressure sensor on the helium compressor. The following day the CERN CCC stopped unintentionally the power converters of the LHC and the experiments, triggering a ramp down that was stopped at 2.7 T. The magnet was back at 3.8 T about 6 hours after CCC sent the CERN-wide command. Three days later, a slow dump was triggered due to a stop of the pump feeding the power converter water-cooling circuit, during an intervention on the water-cooling plant done after several disturbances on the electrical distribution network. The magnet was back at 3.8 T in the evening the same day. On December 10th a break occurred in one turbine of the cold box producing the liquid ...

  1. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

      The magnet was operated without any problem until the end of the LHC run in February 2013, apart from a CERN-wide power glitch on 10 January 2013 that affected the CMS refrigerator, causing a ramp down to 2 T in order to reconnect the coldbox. Another CERN-wide power glitch on 15 January 2013 didn’t affect the magnet subsystems, the cryoplant or the power converter. At the end of the magnet run, the reconnection of the coldbox at 2.5 T was tested. The process will be updated, in particular the parameters of some PID valve controllers. The helium flow of the current leads was reduced but only for a few seconds. The exercise will be repeated with the revised parameters to validate the automatic reconnection process of the coldbox. During LS1, the water-cooling services will be reduced and many interventions are planned on the electrical services. Therefore, the magnet cryogenics and subsystems will be stopped for several months, and the magnet cannot be kept cold. In order to avoid unc...

  2. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet and its sub-systems were stopped at the beginning of the winter shutdown on 8th December 2011. The magnet was left without cooling during the cryogenics maintenance until 17th January 2012, when the cryoplant operation resumed. The magnet temperature reached 93 K. The vacuum pumping was maintained during this period. During this shutdown, the yearly maintenance was performed on the cryogenics, the vacuum pumps, the magnet control and safety systems, and the power converter and discharge lines. Several preventive actions led to the replacement of the electrovalve command coils, and the 20A DC power supplies of the magnet control system. The filters were cleaned on the demineralised water circuits. The oil of the diffusion pumps was changed. On the cryogenics, warm nitrogen at 343 K was circulated in the cold box to regenerate the filters and the heat exchangers. The coalescing filters have been replaced at the inlet of both the turbines and the lubricant trapping unit. The active cha...

  3. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The CMS magnet has been running steadily and smoothly since the summer, with no detected flaw. The magnet instrumentation is entirely operational and all the parameters are at their nominal values. Three power cuts on the electrical network affected the magnet run in the past five months, with no impact on the data-taking as the accelerator was also affected at the same time. On 22nd June, a thunderstorm caused a power glitch on the service electrical network. The primary water cooling at Point 5 was stopped. Despite a quick restart of the water cooling, the inlet temperature of the demineralised water on the busbar cooling circuit increased by 5 °C, up to 23.3 °C. It was kept below the threshold of 27 °C by switching off other cooling circuits to avoid the trigger of a slow dump of the magnet. The cold box of the cryogenics also stopped. Part of the spare liquid helium volume was used to maintain the cooling of the magnet at 4.5 K. The operators of the cryogenics quickly restarted ...

  4. Bremsstrahlung parameters of praseodymium-142 in different human tissues. A dosimetric perspective for 142Pr radionuclide therapy

    International Nuclear Information System (INIS)

    Praseodymium-142 [T1/2=19.12 h, Eβ-=2.162 MeV (96.3%), Eγ=1575 keV (3.7%)] is one of the 141Pr radioisotopes. Many studies have been attempted to assess the significance of usage 142Pr in radionuclide therapy. In many studies, the dosimetric parameters of 142Pr sources were calculated by modeling 142Pr sources in the water phantom and scoring the energy deposited around it. However, the medical dosimetry calculations in water phantom consider Bremsstrahlung production, raising the question: ''How important is to simulate human tissues instead of using water phantom?'' This study answers these questions by estimation of 142Pr Bremsstrahlung parameters. The Bremsstrahlung parameters of 142Pr as therapeutic beta nuclides in different human tissues (adipose, blood, brain, breast, cell nucleus, eye lens, gastrointestinal tract, heart, kidney, liver, lung deflated, lymph, muscle, ovary, pancreas, cartilage, red marrow, spongiosa, yellow marrow, skin, spleen, testis, thyroid and different skeleton bones) were calculated by extending the national council for radiation protection model. The specific Bremsstrahlung constant (ΓBr), probability of energy loss by beta during Bremsstrahlung emission (PBr) and Bremsstrahlung activity (Arelease)Br were estimated. It should be mentioned that Monte Carlo simulation was used for estimation of 142Pr Bremsstrahlung activity based on the element compositions of different human tissues and the calculated exposures from the anthropomorphic phantoms. ΓBr for yellow marrow was smallest amount (1.1962 x 10-3 C/kg-cm2/MBq-h) compared to the other tissues and highest for cortical bone (2.4764 x 10-3 C/kg-cm2/MBq-h), and, overall, ΓBr for skeletal tissues were greater than other tissues. In addition, ΓBr breast was 1.8261 x 10-3 C/kg-cm2/MBq-h which was greater than sacrum and spongiosa bones. Moreover, according to (Arelease)Br of 142Pr, the patients receiving 142Pr do not have to be hospitalized for radiation precautions and the

  5. The synergistic effect of bremsstrahlung photons and intense laser radiation on the structural properties of carbon nanotubes

    International Nuclear Information System (INIS)

    We present in this paper the influence of a synergistic radiation effect of both bremsstrahlung photons with maximum energy of 60 MeV and intense laser radiation (up to 60 KW cm−2) on the structural properties of carbon nanotubes (CNTs). The defect formation (damage) in CNTs under separate irradiations of 60 MeV bremsstrahlung photon or intense laser and their combined irradiations has been investigated by Raman spectroscopy. The experimental results show that (i) our obtained natural CNTs are multi-walled carbon nanotubes (MWCNTs) with a large number of structural defects, which are non-nanotube carbon impurities; (ii) the MWCNTs were not damaged by the irradiations of an intense laser and a bremsstrahlung photon beam with low electron fluency and the irradiation even leads to more purification/ordering; (iii) the reversible modification in non-irradiated and 60 MeV bremsstrahlung photon irradiated MWCNTs with variation of laser power density (LPD) have been received; (iv) the influence on the structural properties of MWCNTs induced by the combined irradiation was greater than the separate irradiation of a 60 MeV bremsstrahlung photon or intense laser radiation. The result also demonstrates that micro-Raman spectroscopy is a valuable, fast and non-destructive tool for the investigation of purification/ordering of CNTs

  6. RHESSI IMAGING SURVEY OF γ-RAY BREMSSTRAHLUNG EMISSION IN SOLAR FLARES

    International Nuclear Information System (INIS)

    We present a high-energy (>150 keV) imaging survey of all solar γ-ray flares observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) to study bremsstrahlung emission from relativistic electrons. Using RHESSI rear segment data, images in the energy range from 150 to 450 keV integrated over the total duration of the impulsive phase of the flare are derived. Out of the 29 γ-ray peaks in 26 RHESSI flares, we successfully obtained images for 21 γ-ray peaks in 20 flares. The remaining eight peaks have >150 keV fluences of less than a few hundred photons per cm2 and counting statistics are too poor for detailed imaging. The flux ratio of the footpoint sources is found to be similar at 50 keV and above 150 keV, indicating that relativistic electrons are present in both footpoints of the flare loop. No correlation between the footpoint separation and the fluence ratio of the 2.2 MeV line and the >300 keV photons is found. This indicates that the relative efficiency of proton to electron acceleration does not depend on loop length, as could have been expected from stochastic acceleration models. As previously reported, the three flares with the best counting statistics show not only footpoint emission, but also a coronal γ-ray bremsstrahlung source. For events with lower counting statistics, no coronal source could be identified. However, instrumental limitation could easily hide a coronal source for events with lower statistics, suggesting that coronal γ-ray bremsstrahlung sources are nevertheless a general feature of γ-ray flares.

  7. On meson exchange currents and nucleon polarizability effects in proton-proton Bremsstrahlung

    International Nuclear Information System (INIS)

    The proton-proton Bremsstrahlung below the pion production threshold is considered. The corrections to leading potential model amplitudes include newly introduced, nucleon polarizability dependent term and the meson exchange currents with account for the Δ-isobar excitation and the vector meson-pion transition currents. Both unpolarized and polarized cross sections are considered with conclusion that measurements of the proton spin-correlation coefficients are most promising to pin down the new, nucleon spin- and structure-dependent corrections. 17 refs., 4 figs

  8. Virtual- and bremsstrahlung corrections to b -> d l+ l- in the standard model

    OpenAIRE

    Asatrian, H. M.; Bieri, K.; Greub, C.; M. Walker

    2003-01-01

    We present the calculation of the virtual- and bremsstrahlung corrections of O(alpha_s) to the matrix elements . This is the missing piece in the NNLL results for various observables associated with the process B-> X_d l+ l-, like the branching ratio, the CP-rate asymmetry and the forward-backward asymmetry. This paper is an extension of analogous calculations done by some of us for the process B-> X_s l+ l-. As the contributions of the diagrams induced by the operators O_1^u and O_2^u with a...

  9. Pion mass effects on axion emission from neutron stars through NN bremsstrahlung processes

    International Nuclear Information System (INIS)

    The rates of axion emission by nucleon-nucleon bremsstrahlung are calculated with the inclusion of the full momentum contribution from a nuclear one pion exchange (OPE) potential. The contributions of the neutron-neutron (nn), proton-proton ( pp) and neutron-proton (np) processes in both the non-degenerate and degenerate limits are explicitly given. We find that the finite-momentum corrections to the emissivities are quantitatively significant for the non-degenerate regime and temperature-dependent, and should affect the existing axion mass bounds. The trend of these nuclear effects is to diminish the emissivities.

  10. Interference Peak in the Spectrum of Bremsstrahlung on Two Amorphous Targets

    CERN Document Server

    Bondarenco, M V

    2014-01-01

    We investigate the interference pattern in the spectrum of non-dipole bremsstrahlung on two amorphous foils. Apart from suppression at lowest $\\omega$, the spectrum exhibits an enhancement adjacent to it. In classical electrodynamics, the net effect of suppression and enhancement proves to be zero. We study the location and the origin of the spectral features, comparing predictions of full Moli\\`ere averaging with those of the Gaussian averaging with Coulomb corrections to the rms multiple scattering angle. Comparison with experimental data, and with previous theoretical predictions is presented.

  11. Monte Carlo 20 and 45 MeV Bremsstrahlung and dose-reduction calculations

    International Nuclear Information System (INIS)

    The SANDYL electron-photon coupled Monte Carlo code has been compared with previously published experimental bremsstrahlung data at 20.9 MeV electron energy. The code was then used to calculate forward-directed spectra, angular distributions and dose-reduction factors for three practical configurations. These are: 20 MeV electrons incident on 1 mm of W + 59 mm of Be, 45 MeV electrons of 1 mm of W and 45 MeV electrons on 1 mm of W + 147 mm of Be. The application of these results to flash radiography is discussed. 7 references, 12 figures, 1 table

  12. Inverse bremsstrahlung stabilization of noise in the generation of ultrashort intense pulses by backward Raman amplification

    International Nuclear Information System (INIS)

    Inverse bremsstrahlung absorption of the pump laser beam in a backward Raman amplifier over the round-trip light transit time through the subcritical density plasma can more than double the electron temperature of the plasma and produce time-varying axial temperature gradients. The resulting increased Landau damping of the plasma wave and detuning of the resonance can act to stabilize the pump against unwanted amplification of Langmuir noise without disrupting nonlinear amplification of the femtosecond seed pulse. Because the heating rate increases with the charge state Z, only low-Z plasmas (hydrogen, helium, or helium-hydrogen mixtures) will maintain a low enough temperature for efficient operation

  13. Electronic temperature measurement on the deca II plasma using the Bremsstrahlung

    International Nuclear Information System (INIS)

    The electronic temperature of the DECA II machine's plasma is determined by studying the Bremsstrahlung. Two types of detectors are used for this measurement, a set scintillator-photo-multiplicator and a photoelectric effect detector with a massive silver target. The method used is the classical 'absorbent method', The absorbents used are thin formvar foils whose thickness is between 600 and 12 500 angstrom. The measurements done in two different working conditions of the DECA II machine have given: Te ≅ 200 eV in the first case and Te ≅ 70 eV in the second case. (author)

  14. High-power vircator in the regime of warm bremsstrahlung X-ray pulses generation

    International Nuclear Information System (INIS)

    The article presents the results of 2D self-consistent calculations of electron beam dynamics in vircator cell alongside with the resulting spectra of the accompanying microwave radiation. Also presented are the results of 1D calculations of electron beam dynamics with consideration for dissipation at the anode foil alongside with the resulting spectra of X-ray radiation. Being presented are the results of the first experiments aimed at investigation of bremsstrahlung X-ray radiation of the vircator for thin (10 μm, Ta) and thick (100 μm, Ta) anode foil

  15. On the bremsstrahlung background correction to the high-energy Compton spectroscopy

    Indian Academy of Sciences (India)

    S Mathur; B L Ahuja

    2005-07-01

    A methodology for bremsstrahlung (BS) background correction to extract a true Compton profile in high-energy Compton scattering experiments is presented. The BS background profiles for Hg, computed within the Born approximation, are estimated for different values of incident energy. It is seen for the first time that the BS background contribution in high-energy Compton profile experiments like those employing third generation synchrotron radiation sources comes out to be significant and non-linear. Further, it is found that the incorporation of BS correction in data reduction of such an experiment performed on Hg at 662 keV energy helps in reconciliation of theory and experiment.

  16. Emerging Hawking-Like Radiation from Gravitational Bremsstrahlung Beyond the Planck Scale

    Science.gov (United States)

    Ciafaloni, Marcello; Colferai, Dimitri; Veneziano, Gabriele

    2015-10-01

    We argue that, as a consequence of the graviton's spin-2, its bremsstrahlung in trans-Planckian-energy (E ≫MP ) gravitational scattering at small deflection angle can be nicely expressed in terms of helicity-transformation phases and their transfer within the scattering process. The resulting spectrum exhibits deeply sub-Planckian characteristic energies of order MP2/E ≪MP (reminiscent of Hawking radiation), a suppressed fragmentation region, and a reduced rapidity plateau, in broad agreement with recent classical estimates.

  17. Emerging Hawking-Like Radiation from Gravitational Bremsstrahlung Beyond the Planck Scale

    CERN Document Server

    Ciafaloni, Marcello; Veneziano, Gabriele

    2015-01-01

    We argue that, as a consequence of the graviton's spin-2, its bremsstrahlung in trans-planckian-energy ($E\\gg M_P$) gravitational scattering at small deflection angle can be nicely expressed in terms of helicity-transformation phases and their transfer within the scattering process. The resulting spectrum exhibits deeply sub-planckian characteristic energies of order $M_P^2/E \\ll M_P$ (reminiscent of Hawking radiation), a suppressed fragmentation region, and a reduced rapidity plateau, in broad agreement with recent classical estimates.

  18. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The magnet ran smoothly in the last few months until a fast dump occurred on 9th May 2011. Fortunately, this occurred in the afternoon of the first day of the technical stop. The fast dump was due to a valve position controller that caused the sudden closure of a valve. This valve is used to regulate the helium flow on one of the two current leads, which electrically connects the coil at 4.5 K to the busbars at room temperature. With no helium flow on the lead, the voltage drop and the temperatures across the leads increase up to the defined thresholds, triggering a fast dump through the Magnet Safety System (MSS). The automatic reaction triggered by the MSS worked properly. The helium release was limited as the pressure rise was just at the limit of the safety valve opening pressure. The average temperature of the magnet reached 72 K. It took four days to recover the temperature and refill the helium volumes. The faulty valve controller was replaced by a spare one before the magnet ramp-up resumed....

  19. Dynamical structure of magnetized dissipative accretion flow around black holes

    OpenAIRE

    Sarkar, Biplob; Das, Santabrata

    2016-01-01

    We study the global structure of optically thin, advection dominated, magnetized accretion flow around black holes. We consider the magnetic field to be turbulent in nature and dominated by the toroidal component. With this, we obtain the complete set of accretion solutions for dissipative flows where bremsstrahlung process is regarded as the dominant cooling mechanism. We show that rotating magnetized accretion flow experiences virtual barrier around black hole due to centrifugal repulsion t...

  20. Neutron–proton bremsstrahlung as a possible probe of high-momentum component in nucleon momentum distribution

    Directory of Open Access Journals (Sweden)

    Hui Xue

    2016-04-01

    Full Text Available Neutron-proton bremsstrahlung in intermediate energy nucleus–nucleus collisions is proposed as a possible probe to study the high-momentum component in nucleon momentum distribution of finite nucleus. Based on the Boltzmann–Uehling–Uhlenbeck (BUU transport model, the effects of high-momentum component on the production of bremsstrahlung photons in the reaction of C12+12C collisions at different incident beam energies are studied. It is found that the high-momentum component increases the high-energy bremsstrahlung photon production remarkably. Furthermore, the ratio of photon production at different incident beam energies is suggested as a potential observable to probe the high-momentum component in nucleon momentum distribution of finite nucleus.

  1. Experimental investigation of synchrotron and Bremsstrahlung hazards at lithography beam line of Indus-2 SRS

    International Nuclear Information System (INIS)

    Radiation hazard at synchrotron radiation (SR) beam lines of Indus-2 Synchrotron Radiation Source (SRS) consists of synchrotron radiation (SR) and Bremsstrahlung radiation (BR). These hazards were quantified experimentally in Lithography beam line (BL-07) of Indus-2 SRS. Measurement was performed during the initial trial operation of the beam line. Transmission of SR through the beam line was optimized by providing bump to the electron beam, prior to the measurement. Thin window ion chamber was used for the SR measurement in the direct beam. Ion current obtained is converted to exposure rate using a calibration factor obtained w.r.t. 60Co source. Copper absorber of 6 mm thick was used for eliminating SR contribution during BR dose measurement. The exposure rates obtained are 3.83E05 R/h-mA and 0.042 R/h-mA for SR and BR respectively. Energy of Bremsstrahlung radiation was also experimentally evaluated using attenuation technique. Details of these measurement and results are presented in this paper. (author)

  2. Bremsstrahlung-induced highly penetrating probes for nondestructive assay and defect analysis

    CERN Document Server

    Selim, F A; Harmon, J F; Kwofie, J; Spaulding, R; Erickson, G; Roney, T

    2002-01-01

    Nondestructive assay and defect analysis probes based on bremsstrahlung-induced processes have been developed to identify elements and probe defects in large volume samples. Bremsstrahlung beams from (electron accelerators) with end-point energies both above and below neutron emission threshold have been used. Below neutron emission threshold these beams (from 6 MeV small pulsed linacs), which exhibit high penetration, create positrons via pair production inside the material and produce X-ray fluorescence (XRF) radiation. Chemical assays of heavy elements in thick samples up to 10 g/cm sup 2 thick are provided by energy dispersive XRF measurements. The pair-produced positrons annihilate within the material, thereby emitting 511 keV gamma radiation. Doppler broadening spectroscopy of the 511 keV radiation can be performed to characterize the material and measure defects in samples of any desired thickness. This technique has successfully measured induced strain due to tensile stress in steel samples of 0.64 cm...

  3. Z-effective from Bremsstrahlung Emission in the C-2*FRC

    Science.gov (United States)

    Garate, Eusebio; Bolte, Nathan; Gupta, Deepak; Gota, Hiroshi; Allfrey, Ian; Kinley, John; Knapp, Kurt; TAE Team

    2014-10-01

    An absolutely-calibrated 12-chord Bremsstrahlung array has been implemented on C-2 and is being used to infer Z-effective profiles and line-averaged values. Electron-ion Bremsstrahlung light at a given wavelength is a function of electron temperature, electron density, and the average ionic charge, Z-effective. Electron density is measured with interferometry and electron temperature is measured directly with Thompson scattering or is inferred by pressure balance. Custom band-pass filters at 523.4 nm were chosen to avoid line-radiation. Z-effective radial profiles show a peak near the separatrix and line-averaged values show an increase in time. For shots where density and temperature profiles were available, Z-effective inside the separatrix was found to be 1.28 for the first ms. These data suggest that C-2 FRC's do not suffer from high levels of edge-light contamination, which allows Z-effective monitoring with a single chord. M. W. Binderbauer, High Performance Field Reversed Configurations (APS DPP 2014 Invited Talk).

  4. Dose build up correction for radiation monitors in high-energy Bremsstrahlung photon radiation fields

    International Nuclear Information System (INIS)

    Conventional radiation monitors have been found to underestimate the personal dose equivalent in the high-energy Bremsstrahlung photon radiation fields encountered near electron storage rings. Depth-dose measurements in a water phantom were carried out with a radiation survey meter in the Bremsstrahlung photon radiation fields from a 450 MeV electron storage ring to find out the magnitude of the underestimation. Dose equivalent indicated by the survey meter was found to build up with increase in thickness of water placed in front of the meter up to certain depth and then reduce with further increase in thickness. A dose equivalent build up factor was estimated from the measurements. An absorbed dose build up factor in a water phantom was also estimated from calculations performed using the Monte Carlo codes, EGS-4 and EGSnrc. The calculations are found to be in very good agreement with the measurements. The studies indicate inadequacy of commercially available radiation monitors for radiation monitoring within shielded enclosures and in streaming high-energy photon radiation fields from electron storage rings, and the need for proper correction for use in such radiation fields. (authors)

  5. Photoactivation of the p-nucleus {sup 92}Mo with bremsstrahlung at ELBE

    Energy Technology Data Exchange (ETDEWEB)

    Erhard, M; Grosse, E; Junghans, A R; Klug, J; Nair, C; Rusev, G; Schilling, K D; Schwengner, R; Wagner, A, E-mail: erhard@pd.infn.i [Institut f. Strahlenphysik, Forschungszentrum Dresden-Rossendorf, 01314 Dresden (Germany)

    2010-01-01

    In nuclear network calculations especially the p-nucleus {sup 92}Mo is frequently underproduced. Since experimental data of the photodisintegration of {sup 92}Mo so far do not exist, it was necessary to measure the reaction yields with the photoactivation method using the brems-strahlung facility ELBE at FZ Dresden-Rossendorf. Also the reaction {sup 100}Mo({gamma},n) could be tested while irradiating Mo samples of natural composition. The photon fluence was measured with nuclear resonance fluorescence (NRF) of strong and well-known transitions in {sup 11}B. As a normalization standard the photoactivation reaction {sup 197}Au({gamma},n) was used. For the 65 s half-life of {sup 91m}Mo a fast pneumatic delivery was used. The photoactivation yields of the ({gamma},p) and ({gamma},n) reactions are compared to yield integrals of the bremsstrahlung spectral shape folded with the cross sections derived from Hauser-Feshbach nuclear model calculations using the TALYS program and cross sections from earlier experiments.

  6. Photoactivation of the p-nucleus 92Mo with bremsstrahlung at ELBE

    Science.gov (United States)

    Erhard, M.; Grosse, E.; Junghans, A. R.; Klug, J.; Nair, C.; Rusev, G.; Schilling, K. D.; Schwengner, R.; Wagner, A.

    2010-01-01

    In nuclear network calculations especially the p-nucleus 92Mo is frequently underproduced. Since experimental data of the photodisintegration of 92Mo so far do not exist, it was necessary to measure the reaction yields with the photoactivation method using the brems-strahlung facility ELBE at FZ Dresden-Rossendorf. Also the reaction 100Mo(γ,n) could be tested while irradiating Mo samples of natural composition. The photon fluence was measured with nuclear resonance fluorescence (NRF) of strong and well-known transitions in 11B. As a normalization standard the photoactivation reaction 197Au(γ,n) was used. For the 65 s half-life of 91mMo a fast pneumatic delivery was used. The photoactivation yields of the (γ,p) and (γ,n) reactions are compared to yield integrals of the bremsstrahlung spectral shape folded with the cross sections derived from Hauser-Feshbach nuclear model calculations using the TALYS program and cross sections from earlier experiments.

  7. Bremsstrahlung from nuclear scattering at low energy near a resonance. Final report

    International Nuclear Information System (INIS)

    The understanding of almost all low-energy reaction processes depends upon a distorted wave Born approximation (DWBA) analysis. DWBA procedures, in turn, depend crucially upon a correct optical model description of the projectile-target elastic scattering process. An assumption that the potential is local together with measurements of the elastic scattering data at all energies (0 -infinity) would completely determine that potential, including its off-shell or short-range properties. However, one does not have the luxury of knowing the elastic scattering phase shifts for all energies nor are we so naive as to believe that the potential is completely local. Thus, an alternative approach is called for. The present proposal describes a program to contribute to the general understanding of nuclear reactions by determining as many of the off-shell properties of the proton-nucleus interaction as possible through the study of the proton-nucleus bremsstrahlung process. We seek to establish the limits of validity of a model independent analysis of these reactions in the neighborhood of a resonance or a breakup threshold, and to utilize the differences between this analysis and the data to elucidate those off-shell constraints which any valid proton-nucleus model interaction must satisfy. The bremsstrahlung process provides a method for determining the off-shell properties of the proton-nucleus potential, and the Brooklyn College program offers a unique opportunity to measure these crucial aspects of the low energy proton-nucleus interaction. 18 references

  8. A high-power vircator operating as an X-ray bremsstrahlung generator

    International Nuclear Information System (INIS)

    A vircator capable of generating high-power X-ray pulses due to the multiple transitions of electrons through a thin anode foil transparent to X radiation has been created and put into operation for the first time. The vircator is created on the basis of a direct-action electron accelerator supplied from an inductive energy storage operating with a plasma opening switch. Self-consistent two-dimensional simulations of the electron beam dynamics in the vircator chamber are performed, and the spectra of the generated microwave radiation are determined. Self-consistent one-dimensional simulations of the beam dynamics with allowance for electron scattering in the foil were also carried out, and the X-ray bremsstrahlung spectra were measured. Results are presented from the first experiments on the generation of X-ray bremsstrahlung in vircators with thin (10 μm) and thick (100 μm) tantalum anode foils. For a thin foil, the X-ray (Eγ > 30 keV) dose is eight times as high as that for a thick foil and the average photon energy is 30 keV (against 80 keV for a thick foil)

  9. Effect of degenerate particles on internal bremsstrahlung of Majorana dark matter

    Directory of Open Access Journals (Sweden)

    Hiroshi Okada

    2015-11-01

    Full Text Available Gamma-rays induced by annihilation or decay of dark matter can be its smoking gun signature. In particular, gamma-rays generated by internal bremsstrahlung of Majorana and real scalar dark matter is promising since it can be a leading emission of sharp gamma-rays. However in the case of Majorana dark matter, its cross section for internal bremsstrahlung cannot be large enough to be observed by future gamma-ray experiments if the observed relic density is assumed to be thermally produced. In this paper, we introduce some degenerate particles with Majorana dark matter, and show they lead enhancement of the cross section. As a result, increase of about one order of magnitude for the cross section is possible without conflict with the observed relic density, and it would be tested by the future gamma-ray experiments such as GAMMA-400 and Cherenkov Telescope Array (CTA. In addition, the constraints of perturbativity, positron observation by the AMS experiment and direct search for dark matter are discussed.

  10. High-energy gluon bremsstrahlung in a finite medium: Harmonic oscillator versus single-scattering approximation

    International Nuclear Information System (INIS)

    A particle produced in a hard collision can lose energy through bremsstrahlung. It has long been of interest to calculate the effect on bremsstrahlung if the particle is produced inside a finite-size QCD medium such as a quark-gluon plasma. For the case of very high-energy particles traveling through the background of a weakly coupled quark-gluon plasma, it is known how to reduce this problem to an equivalent problem in nonrelativistic two-dimensional quantum mechanics. Analytic solutions, however, have always resorted to further approximations. One is a harmonic oscillator approximation to the corresponding quantum mechanics problem, which is appropriate for sufficiently thick media. Another is to formally treat the particle as having only a single significant scattering from the plasma (known as the N=1 term of the opacity expansion), which is appropriate for sufficiently thin media. In a broad range of intermediate cases, these two very different approximations give surprisingly similar but slightly differing results if one works to leading logarithmic order in the particle energy, and there has been confusion about the range of validity of each approximation. In this paper, I sort out in detail the parametric range of validity of these two approximations at leading logarithmic order. For simplicity, I study the problem for small αs and large logarithms but αslog<<1.

  11. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

    The magnet is fully stopped and at room temperature. The maintenance works and consolidation activities on the magnet sub-systems are progressing. To consolidate the cryogenic installation, two redundant helium compressors will be installed as ‘hot spares’, to avoid the risk of a magnet downtime in case of a major failure of a compressor unit during operation. The screw compressors, their motors, the mechanical couplings and the concrete blocks are already available and stored at P5. The metallic structure used to access the existing compressors in SH5 will be modified to allow the installation of the two redundant ones. The plan is to finish the installation and commissioning of the hot spare compressors before the summer 2014. In the meantime, a bypass on the high-pressure helium piping will be installed for the connection of a helium drier unit later during the Long Shutdown 1, keeping this installation out of the schedule critical path. A proposal is now being prepared for the con...

  12. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet worked very well at 3.8 T as expected, despite a technical issue that manifested twice in the cryogenics since June. All the other magnet sub-systems worked without flaw. The issue in the cryogenics was with the cold box: it could be observed that the cold box was getting progressively blocked, due to some residual humidity and air accumulating in the first thermal exchanger and in the adsorber at 65 K. This was later confirmed by the analysis during the regeneration phases. An increase in the temperature difference between the helium inlet and outlet across the heat exchanger and a pressure drop increase on the filter of the adsorber were observed. The consequence was a reduction of the helium flow, first compensated by the automatic opening of the regulation valves. But once they were fully opened, the flow and refrigeration power reduced as a consequence. In such a situation, the liquid helium level in the helium Dewar decreased, eventually causing a ramp down of the magnet current and a field...

  13. MAGNET

    CERN Multimedia

    Benoit Curé.

    The magnet operation restarted end of June this year. Quick routine checks of the magnet sub-systems were performed at low current before starting the ramps up to higher field. It appeared clearly that the end of the field ramp down to zero was too long to be compatible with the detector commissioning and operations plans. It was decided to perform an upgrade to keep the ramp down from 3.8T to zero within 4 hours. On July 10th, when a field of 1.5T was reached, small movements were observed in the forward region support table and it was decided to fix this problem before going to higher field. At the end of July the ramps could be resumed. On July 28th, the field was at 3.8T and the summer CRAFT exercise could start. This run in August went smoothly until a general CERN wide power cut took place on August 3rd, due to an insulation fault on the high voltage network outside point 5. It affected the magnet powering electrical circuit, as it caused the opening of the main circuit breakers, resulting in a fast du...

  14. MAGNET

    CERN Multimedia

    B. Curé

    MAGNET During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bough...

  15. Investigation of the plasma bremsstrahlung in the near infrared for Zeff determination and electron density feedback control in tokamak devices

    International Nuclear Information System (INIS)

    In the ASDEX Thomson scattering system the scattered light of a Nd:YAG laser beam (λ = 1064 nm) is measured to obtain electron density and temperature profiles every 16 ms. The same system is continuously used to measure bremsstrahlung in the near infrared, allowing determination of radial Zeff profiles. Furthermore, the diagnostic can also be used for real time control of the electron density. This applies in particular in cases where large sawteeth and pellet injection generate counting errors in the interferometer signal. The relation between the line density n and the central chord bremsstrahlung signal Ub was investigated for different heating scenarios in a wide density range. (orig.)

  16. MAGNET

    CERN Multimedia

    B. Curé

    During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bought. Th...

  17. MAGNET

    CERN Multimedia

    Benoit Curé

    The magnet subsystems resumed operation early this spring. The vacuum pumping was restarted mid March, and the cryogenic power plant was restarted on March 30th. Three and a half weeks later, the magnet was at 4.5 K. The vacuum pumping system is performing well. One of the newly installed vacuum gauges had to be replaced at the end of the cool-down phase, as the values indicated were not coherent with the other pressure measurements. The correction had to be implemented quickly to be sure no helium leak could be at the origin of this anomaly. The pressure measurements have been stable and coherent since the change. The cryogenics worked well, and the cool-down went quite smoothly, without any particular difficulty. The automated start of the turbines had to be fine-tuned to get a smooth transition, as it was observed that the cooling power delivered by the turbines was slightly higher than needed, causing the cold box to stop automatically. This had no consequence as the cold box safety system acts to keep ...

  18. Secondary bremsstrahlung and the energy-conservation aspects of kerma in photon-irradiated media

    Science.gov (United States)

    Kumar, Sudhir; Nahum, Alan E.

    2016-02-01

    Kerma, collision kerma and absorbed dose in media irradiated by megavoltage photons are analysed with respect to energy conservation. The user-code DOSRZnrc was employed to compute absorbed dose D, kerma K and a special form of kerma, K ncpt, obtained by setting the charged-particle transport energy cut-off very high, thereby preventing the generation of ‘secondary bremsstrahlung’ along the charged-particle paths. The user-code FLURZnrc was employed to compute photon fluence, differential in energy, from which collision kerma, K col and K were derived. The ratios K/D, K ncpt/D and K col/D have thereby been determined over a very large volumes of water, aluminium and copper irradiated by broad, parallel beams of 0.1 to 25 MeV monoenergetic photons, and 6, 10 and 15 MV ‘clinical’ radiotherapy qualities. Concerning depth-dependence, the ‘area under the kerma, K, curve’ exceeded that under the dose curve, demonstrating that kerma does not conserve energy when computed over a large volume. This is due to the ‘double counting’ of the energy of the secondary bremsstrahlung photons, this energy being (implicitly) included in the kerma ‘liberated’ in the irradiated medium, at the same time as this secondary bremsstrahlung is included in the photon fluence which gives rise to kerma elsewhere in the medium. For 25 MeV photons this ‘violation’ amounts to 8.6%, 14.2% and 25.5% in large volumes of water, aluminium and copper respectively but only 0.6% for a ‘clinical’ 6 MV beam in water. By contrast, K col/D and K ncpt/D, also computed over very large phantoms of the same three media, for the same beam qualities, are equal to unity within (very low) statistical uncertainties, demonstrating that collision kerma and the special type of kerma, K ncpt, do conserve energy over a large volume. A comparison of photon fluence spectra for the 25 MeV beam at a depth of  ≈51 g cm-2 for both very high and very low charged-particle transport cut

  19. Methodological investigations and test measurements for the pp-bremsstrahlung experiment at the COSY-TOF spectrometer

    International Nuclear Information System (INIS)

    A time-of-flight spectrometer is being installed at the COSY accelerator for experimental investigations of the proton-proton bremsstrahlung. The TOF spectrometer is to detect the times of flight, the flight directions, and the multiplicities of charged particles. The design of the start detector is explained as well as initial test results for the ppγ experiment. (orig./HP)

  20. Efficient far-infrared thermal bremsstrahlung radiation from a heterojunction bipolar transistor

    International Nuclear Information System (INIS)

    We investigate the far-infrared thermal radiation properties of a heterojunction bipolar transistor. The device conveniently provides a high electric field for electrons to heat the lattice and the electron gas in a background with ions embedded. Because of very high effective temperature of the electron gas in the collector, the electron-ion bremsstrahlung makes efficient the thermal radiation in the far-infrared region. The transistor can yield a radiation power of 0.1 mW with the spectral region between 2 and 75 THz and a power conversion efficiency of 6 × 10−4. Such output contains a power of 20 μW in the low-frequency part (2–20 THz) of the spectrum

  1. On the formation of bremsstrahlung in an absorptive QED/QCD medium

    CERN Document Server

    Bluhm, Marcus; Gousset, Thierry; Aichelin, Joerg

    2012-01-01

    The radiative energy loss of a relativistic charge in a dense, absorptive medium can be affected significantly by damping phenomena. The effect is more pronounced for large energies of the charge and/or large damping of the radiation. This can be understood in terms of a competition between the formation time of bremsstrahlung and a damping time scale. Discussing this competition in detail for the absorptive QED and QCD medium, we identify the regions in energy and parameter space, in which either coherence or damping effects are of major importance for the radiation spectrum. We show that damping mechanisms lead to a stronger suppression of the spectrum than coherence effects. This might be visible experimentally in correlations between hadrons at large momenta.

  2. Bremsstrahlung x ray spectra of Jupiter and Saturn: Predictions for future planetary spacecraft

    International Nuclear Information System (INIS)

    Calculations of X ray spectra due to bremsstrahlung from precipitating auroral electrons at Jupiter and Saturn are presented. The model assumes that a field-aligned potential drop accelerates a primary beam of electrons into the atmosphere where a population of secondary electrons having a power law energy dependence is generated. The spectrum at Jupiter is normalized to the soft X ray observations of Metzger et al (1983) at the low-energy end and constrained at the high-energy end by UV auroral energy requirements. The spectrum at Saturn is constructed by analogy to the Jovian case allowing for variation of the beam energy, energy flux, and scale size of the Saturnian aurora. The resulting indicate that a significant flux of X rays is emanating from both planets which may serve as a basis for conducting planetary X ray astronomy as part of future spacecraft missions to the planets

  3. The Efficiency of Gravitational Bremsstrahlung Production in the Collision of Two Schwarzschild Black Holes

    CERN Document Server

    Aranha, R F; Soares, I Damião; Tonini, E V

    2008-01-01

    We examine the efficiency of gravitational bremsstrahlung production in the process of head-on collision of two boosted Schwarzschild black holes. We constructed initial data for the characteristic initial value problem in Robinson-Trautman spacetimes, that represent two instantaneously stationary Schwarzschild black holes in motion towards each other with the same velocity. The Robinson-Trautman equation was integrated for these initial data using a numerical code based on the Galerkin method. The final resulting configuration is a boosted black hole with Bondi mass greater than the sum of the individual mass of each initial black hole. Two relevant aspects of the process are presented. The first relates the efficiency $\\Delta$ of the energy extraction by gravitational wave emission to the mass of the final black hole. This relation is fitted by a distribution function of non-extensive thermostatistics with entropic parameter $q \\simeq 1/2$; the result extends and validates analysis based on the linearized t...

  4. Higher-order gravitational deflection and soft bremsstrahlung in planckian energy superstring collisions

    International Nuclear Information System (INIS)

    The leading behaviour of planckian energy superstring scattering in D space-time dimensions was described in previous papers by an eikonal function which, at large distances, could be interpreted in terms of an effective Aichelburg-Sexl metric yielding the first-order Einstein deflection. We compute here the subleading terms of such an eikonal function up to two loops and, for D=4, we find: a finite and positive classical correction to the Einstein deflection, implying a deviation from the external metric picture; an IR divergent absorptive part which admits a Bloch-Nordsieck interpretation in terms of soft graviton bremsstrahlung. The derivation of the above results is based on a novel treatment of the IR behaviour of quantum gravity around D=4, proving the absence of inelastic Coulomb singularities and the lack of renormalization of the infinite Coulomb phase. (orig.)

  5. Observation of intense radiation during thunderstorm and Monte Carlo simulation of bremsstrahlung generation

    International Nuclear Information System (INIS)

    Following Wilson's suggestion of electron acceleration by the electric fields in thunderclouds, a number of experiments were attempted to investigate whether or not energetic electrons and bremsstrahlung X-rays were generated by thunderstorm electric fields or lightning discharge processes. In recent years, enhanced radiation at high altitude has been detected in experiments using scintillation detectors on a jet and an artificial satellite, demonstrating that radiation is indeed associated with lightning activities. However there are few experimental reports of detection near the ground since Whitmire's investigation using thermoluminescent dosimeters (TLDs) in 1979. In winter, many thunderstorms occur on the west coast of Japan, and it has been suggested that gamma-ray dose may increase occasionally during winter thunderstorms. Recently, a gamma-ray dose enhancement which might be caused by the lightning activity was measured by TLDs and environmental radiation monitors around the site of the fast breeder reactor 'Monju', a nuclear power plant facing the Japan Sea. (author)

  6. Spatially resolved hard X-ray polarization in solar flares: effects of Compton scattering and bremsstrahlung

    CERN Document Server

    Jeffrey, Natasha

    2011-01-01

    This paper aims to study the polarization of hard X-ray (HXR) sources in the solar atmosphere, including Compton backscattering of photons in the photosphere (the albedo effect) and the spatial distribution of polarization across the source. HXR photon polarization and spectra produced via electron-ion bremsstrahlung are calculated from electron distributions typical for solar flares. Compton scattering and photoelectric absorption are then modelled using Monte Carlo simulations of photon transport in the photosphere. Polarization maps across HXR sources (primary and albedo components) for each of the modelled electron distributions are calculated at various source locations from the solar centre to the limb. We show that Compton scattering produces a distinct polarization variation across the albedo patch at peak albedo energies of 20-50 keV for all anisotropies modelled. The results show that there are distinct spatial polarization changes in both the radial and perpendicular to radial directions across the...

  7. An Estimate of the Spectral Intensity Expected from the Molecular Bremsstrahlung Radiation in Extensive Air Showers

    CERN Document Server

    Samarai, I Al; Lebrun, D; Letessier-Selvon, A; Salamida, F

    2014-01-01

    A detection technique of ultra-high energy cosmic rays, complementary to the fluorescence technique, would be the use of the molecular Bremsstrahlung radiation emitted by low-energy electrons left after the passage of the showers in the atmosphere. The emission mechanism is expected from quasi-elastic collisions of electrons produced in the shower by the ionisation of the molecules in the atmosphere. In this article, a detailed calculation of the spectral intensity of photons at ground level originating from the transitions between unquantised energy states of free ionisation electrons is presented. In the absence of absorption of the emitted photons in the plasma, the obtained spectral intensity is shown to be 5 10^{-26} W m^{-2}Hz^{-1} at 10 km from the shower core for a vertical shower induced by a proton of 10^{17.5} eV.

  8. Bremsstrahlung photons - an ideal tool in nuclear structure and nuclear astrophysics

    International Nuclear Information System (INIS)

    Full text of publication follows. Bremsstrahlung photons, produced by decelerating electrons, are a very useful probe to investigate current topics in nuclear structure and nuclear astrophysics. The photon scattering facility of the superconducting electron accelerator S-DALINAC at the Darmstadt University of Technology allows for high resolution Nuclear Resonance Fluorescence (NRF) experiments up to 10 MeV. One current topic of interest in nuclear structure is the investigation of Pygmy Dipole Resonances (PDR), which are located near the particle threshold. Recently, experiments have been carried out on Ca isotopes [1] as well as on several N=82 nuclei [2] in order to understand the structure of the PDR. Moreover, important astrophysical questions can be investigated using real photons (g,n) reaction rates, which play a major role in nucleosynthesis, can be measured at the S-DALINAC by simulating a quasi-stellar photon bath with variable temperature [3,4

  9. Studies on inner bremsstrahlung from a few β-emitting isotopes

    International Nuclear Information System (INIS)

    Past experimental studies on the inner bremsstrahlung (IB) emission from the forbidden β transitions have shown marked deviations from the theoretical calculations of Lewis and Ford, Ford and Martin, Chang and Falkoff, Madansky and Gebhardt. In this paper we have re-analysed the data of IB emissions from four β-emitting isotopes, namely 89Sr, 141Ce, 111Ag and 99Tc, whose transitions are classified as forbidden. The raw experimental data already available in the literature are critically examined in the light of relevant statistics in order to arrive at meaningful conclusions. The unfolding of the IB spectra was done following the step-by-step procedure of Liden and Starfelt. The results obtained were different from those reported in the literature. (author)

  10. Determination of the anomalous scattering factors of high-Z atoms using bremsstrahlung radiation

    International Nuclear Information System (INIS)

    The anomalous scattering factors (f' and f'') of tungsten, gold and lead atoms have been determined using external bremsstrahlung (EB) photons. The EB photons are produced by the interaction of a beta particle from a beta source with a nickel target. These photons are allowed to pass through thin targets of tungsten, gold and lead. The transmitted photons have been measured by using a GMX-type HPGe detector coupled to an 8K multichannel analyser. The transmitted spectra show a sharp decrease in intensity at the K shell binding energies of the target atoms. The regions around the decreased portion have been used to determine the anomalous scattering factors. The experimentally measured values are compared with the available theoretical values.

  11. Determination of the anomalous scattering factors of high-Z atoms using bremsstrahlung radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hosur, Savita B; Naik, L R; Badiger, N M [Department of Physics, Karnatak University, Dharwad 580003 (India)], E-mail: nagappa123@yahoo.co.in

    2009-02-14

    The anomalous scattering factors (f' and f'') of tungsten, gold and lead atoms have been determined using external bremsstrahlung (EB) photons. The EB photons are produced by the interaction of a beta particle from a beta source with a nickel target. These photons are allowed to pass through thin targets of tungsten, gold and lead. The transmitted photons have been measured by using a GMX-type HPGe detector coupled to an 8K multichannel analyser. The transmitted spectra show a sharp decrease in intensity at the K shell binding energies of the target atoms. The regions around the decreased portion have been used to determine the anomalous scattering factors. The experimentally measured values are compared with the available theoretical values.

  12. Energy dependence of hard bremsstrahlung production in proton-proton collisions in the Delta(1232) region

    CERN Document Server

    Tsirkov, D; Azaryan, T; Chiladze, D; Dymov, S; Dzyuba, A; Hartmann, M; Kacharava, A; Khoukaz, A; Kulikov, A; Kurbatov, V; Macharashvili, G; Merzliakov, S; Mielke, M; Mikirtychiants, S; Nekipelov, M; Rathmann, F; Serdyuk, V; Stroeher, H; Uzikov, Yu; Valdau, Yu; Wilkin, C

    2010-01-01

    Hard bremsstrahlung production in proton-proton collisions has been studied with the ANKE spectrometer at COSY-Juelich in the energy range of 353-800 MeV by detecting the final proton pair {pp}_s from the pp -> {pp}_s reaction with very low excitation energy. Differential cross sections were measured at small diproton c.m. angles from 0 to 20 degrees and the average over this angular interval reveals a broad peak at a beam energy around 650 MeV with a FWHM of about 220 MeV, suggesting the influence of Delta(1232)N intermediate states. Comparison with deuteron photodisintegration shows that the cross section for diproton production is up to two orders of magnitude smaller, due largely to differences in the selection rules.

  13. Application of visible bremsstrahlung to Z(eff) measurement on the Experimental Advanced Superconducting Tokamak.

    Science.gov (United States)

    Chen, Yingjie; Wu, Zhenwei; Gao, Wei; Ti, Ang; Zhang, Ling; Jie, Yinxian; Zhang, Jizong; Huang, Juan; Xu, Zong; Zhao, Junyu

    2015-02-01

    The multi-channel visible bremsstrahlung measurement system has been developed on Experimental Advanced Superconducting Tokamak (EAST). In addition to providing effective ion charge Zeff as a routine diagnostic, this diagnostic can also be used to estimate other parameters. With the assumption that Zeff can be seen as constant across the radius and does not change significantly during steady state discharges, central electron temperature, averaged electron density, electron density profile, and plasma current density profile have been obtained based on the scaling of Zeff with electron density and the relations between Zeff and these parameters. The estimated results are in good coincidence with measured values, providing an effective and convenient method to estimate other plasma parameters. PMID:25725844

  14. Study on the dose distribution of 8-MeV bremsstrahlung in mantle field techniques

    International Nuclear Information System (INIS)

    The dose distribution within the patient was studied with 8-MeV bremsstrahlung from a linear accelerator during mantle field irradiation using molded shielding blocks. Doses and dose distributions in the different layers of a modified Alderson phantom were measured by means of film dosimetry and related to the dose in the central ray beam at the middle of the body. Dose distribution within unshielded regions perpendicular to the central ray beam generally being relatively homogeneous, the highest relative doses, amounting to ca. 115%, are found in the region of the mandibular angle and in the supraclavicular region; the dose to superficial lymph nodes at the supraclavicular region reaches 100% of the dose in the central ray beam. As a cause for these important doses near the surface of the body are discussed the extension of mantle fields as well as the increased exit dose of the opposed field and the oblique incidence of radiation. (orig.)

  15. The production of neutral vector mesons by bremsstrahlung in electron-positron colliding beams

    International Nuclear Information System (INIS)

    The authors study the bremsstrahlung production of the rho meson in the reaction e+e- → e+e-rho (→ e+e- π+π-). This reaction gives a C = -1 background which complicates the study of C = +1 two-photon processes at the new colliding-beam facilities. The cross section for the reaction rises from approximately 0.3 nb to 0.7 nb as the beam energy increases from 2 GeV to 15 GeV. From a study of the distributions of the final leptons and pions, one finds a suitable choice of cuts which will reduce the event rate down to a small fraction of R. It is not possible to attribute the three-prong events seen at DELCO and PLUTO to this particular production mechanism. (Auth.)

  16. Search for a 17 keV neutrino in the internal bremsstrahlung spectrum of 125I

    International Nuclear Information System (INIS)

    We have searched for evidence of the emission of a 17 keV neutrino in the internal bremsstrahlung (IB) spectrum accompanying the electron capture decay of 125I. The IB spectrum, recorded in a planar Ge detector, has 1.2x106 counts per keV at 17 keV below the 2p end point. We set an upper limit of 0.4% for the admixture of a 17 keV neutrino, at the 90% confidence level, and exclude a 0.8% admixture at the 99.6% confidence level. The QEC value is found to be 185.77±0.06 keV. We also find that the recent calculations of Suric et al., which employ relativistic self-consistent-field atomic wave functions, reproduce the shape and relative intensity of IB partial spectra within a few percent

  17. Study of the inner Bremsstrahlung following the electron-capture decay of 193 Pt

    International Nuclear Information System (INIS)

    We are measuring the inner Bremsstrahlung (I B) photons emitted in some of the electron-capture decays of 193 Pt. The source was prepared with highly pure metal Pt. It was irradiated with neutron for 52 days and let to cool down for eight months. The remaining activities were due to 193 Ptg (half-life 50 yr) and 192 Ir (half-life 74 d), the latter coming from (n, γ) reactions on a small content of Ir. We have used a radiochemistry method to reduce the Ir content of the source. The resulting Pt compound will be dissolved in a plastic scintillator disk. Most of the 192 Ir decays are β- and their signal in the plastic will be used as a veto for the I B-photon detector. We have performed simulations of the efficiency and absorption effects in the detection geometry. (author)

  18. Modeling Relativistic Electron Precipitation Bremsstrahlung X-Ray Intensities at 10-100 km Manned Vehicle Altitudes

    Science.gov (United States)

    Krause, L. Habsh; Gilchrist, B. E.; Nishikawa, Ken-Ichi

    2013-01-01

    Relativisitic electron precipitation (REP) events occur when beams or bunches of relativistic electrons of magnetospheric origin enter the Earth's atmosphere, typically at auroral latitudes. REP events are associated with a variety of space weather effects, including production of transitional and bremsstrahlung radiation, catalytic depletion of stratospheric ozone, and scintillation of transionospheric radio waves. This study examines the intensities of x-rays produced at airliner, manned balloon, and space reuseable launch vehicles (sRLVs). The monoenergetic beam is modeled in cylindrical symetry using the paraxial ray equation. Bremsstrahlung photon production is calculated using the traditional Sauter-Elwert cross-section, providing x-ray emission spectra differential in energy and angle. Attenuation is computed for a plane-stratified standard atmosphere, and the loss processes include photoionization, Rayleigh and Compton scattering, electron-positron pair production, and photonuclear interaction. Peak altitudes of electron energy deposition and bremsstrahlung x-ray production were calculated for beams of energies from 1 MeV through 100 MeV. The altitude peak of bremsstrahlung deposition was consistently and significantly lower that that of the electron deposition due to the longer mean free paths of x-rays compared to electrons within the atmosphere. For example, for a nadir-directed monoenergetic 5 MeV beam, the peak deposition altitude was calculated to be 42 km, but the resulting bremsstrahlung deposition peaked at 25 km. This has implications for crew and passenger safety, especially with the growth of the space tourism industry. A survey of results covering the 1-100 MeV spectrum for the three altitude ranges of interest will be presented.

  19. MAGNET

    CERN Multimedia

    Benoit Curé

    The cooling down to the nominal temperature of 4.5 K was achieved at the beginning of August, in conjunction with the completion of the installation work of the connection between the power lines and the coil current leads. The temperature gradient on the first exchanger of the cold box is now kept within the nominal range. A leak of lubricant on a gasket of the helium compressor station installed at the surface was observed and several corrective actions were necessary to bring the situation back to normal. The compressor had to be refilled with lubricant and a regeneration of the filters and adsorbers was necessary. The coil cool down was resumed successfully, and the cryogenics is running since then with all parameters being nominal. Preliminary tests of the 20kA coil power supply were done earlier at full current through the discharge lines into the dump resistors, and with the powering busbars from USC5 to UXC5 without the magnet connected. On Monday evening August 25th, at 8pm, the final commissionin...

  20. MAGNET

    CERN Multimedia

    B. Curé

    The first phase of the commissioning ended in August by a triggered fast dump at 3T. All parameters were nominal, and the temperature recovery down to 4.5K was carried out in two days by the cryogenics. In September, series of ramps were achieved up to 3 and finally 3.8T, while checking thoroughly the detectors in the forward region, measuring any movement of and around the HF. After the incident of the LHC accelerator on September 19th, corrective actions could be undertaken in the forward region. When all these displacements were fully characterized and repetitive, with no sign of increments in displacement at each field ramp, it was possible to start the CRAFT, Cosmic Run at Four Tesla (which was in fact at 3.8T). The magnet was ramped up to 18.16kA and the 3 week run went smoothly, with only 4 interruptions: due to the VIP visits on 21st October during the LHC inauguration day; a water leak on the cooling demineralized water circuit, about 1 l/min, that triggered a stop of the cooling pumps, and resulte...

  1. MAGNET

    CERN Multimedia

    Benoit Curé

    2013-01-01

    Maintenance work and consolidation activities on the magnet cryogenics and its power distribution are progressing according to the schedules. The manufacturing of the two new helium compressor frame units has started. The frame units support the valves, all the sensors and the compressors with their motors. This activity is subcontracted. The final installation and the commissioning at CERN are scheduled for March–April 2014. The overhauls of existing cryogenics equipment (compressors, motors) are in progress. The reassembly of the components shall start in early 2014. The helium drier, to be installed on the high-pressure helium piping, has been ordered and will be delivered in the first trimester of 2014. The power distribution for the helium compressors in SH5 on the 3.3kV network is progressing. The 3.3kV switches, between each compressor and its hot spare compressor, are being installed, together with the power cables for the new compressors. The 3.3kV electrical switchboards in SE5 will ...

  2. Bremsstrahlung in Mo and Pt targets produced by 90Sr beta particles in the photon energy region of 1-100 keV

    International Nuclear Information System (INIS)

    Bremsstrahlung spectra in thick targets of Mo and Pt, produced by beta emitter 90Sr (end point energy = 546 keV) have been studied in the photon energy range of 1-100 keV. The experimentally measured bremsstrahlung spectra measured with Si(Li) detector were compared with the theoretical spectral distributions calculated from Elwert corrected (non relativistic) Bethe-Heitler [EBH] theory, modified Elwert factor (relativistic) Bethe-Heitler (FmodBH) theory for ordinary bremsstrahlung (OB) and the modified Elwert factor (relativistic) Bethe-Heitler (FmodBH+PB) theory, which includes the polarization bremsstrahlung (PB) into total bremsstrahlung (BS). The present results indicate the correctness of FmodBH+PB theory in the low energy region, where the contributions of PB into BS are dominant, which is described in terms of stripped atom (SA) approximation. But at the middle and higher energy region of the bremsstrahlung spectrum, where the contribution of PB is negligible, the FmodBH theory is more close to the experimental results. Hence, it is clear that the production of PB in the low energy region, due to the dynamic response of the target atom suppresses the production of bremsstrahlung at higher energy ends

  3. Bremsstrahlung in Mo and Pt targets produced by {sup 90}Sr beta particles in the photon energy region of 1-100 keV

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Amrit; Dhaliwal, A. S., E-mail: dhaliwalas@hotmail.com [Department of Physics, Sant Longowal Institute of Engineering and Technology, Longowal(Sangrur) -148106, Punjab (India)

    2015-08-28

    Bremsstrahlung spectra in thick targets of Mo and Pt, produced by beta emitter {sup 90}Sr (end point energy = 546 keV) have been studied in the photon energy range of 1-100 keV. The experimentally measured bremsstrahlung spectra measured with Si(Li) detector were compared with the theoretical spectral distributions calculated from Elwert corrected (non relativistic) Bethe-Heitler [EBH] theory, modified Elwert factor (relativistic) Bethe-Heitler (F{sub mod}BH) theory for ordinary bremsstrahlung (OB) and the modified Elwert factor (relativistic) Bethe-Heitler (F{sub mod}BH+PB) theory, which includes the polarization bremsstrahlung (PB) into total bremsstrahlung (BS). The present results indicate the correctness of F{sub mod}BH+PB theory in the low energy region, where the contributions of PB into BS are dominant, which is described in terms of stripped atom (SA) approximation. But at the middle and higher energy region of the bremsstrahlung spectrum, where the contribution of PB is negligible, the F{sub mod}BH theory is more close to the experimental results. Hence, it is clear that the production of PB in the low energy region, due to the dynamic response of the target atom suppresses the production of bremsstrahlung at higher energy ends.

  4. Bremsstrahlung in Mo and Pt targets produced by 90Sr beta particles in the photon energy region of 1-100 keV

    Science.gov (United States)

    Singh, Amrit; Dhaliwal, A. S.

    2015-08-01

    Bremsstrahlung spectra in thick targets of Mo and Pt, produced by beta emitter 90Sr (end point energy = 546 keV) have been studied in the photon energy range of 1-100 keV. The experimentally measured bremsstrahlung spectra measured with Si(Li) detector were compared with the theoretical spectral distributions calculated from Elwert corrected (non relativistic) Bethe-Heitler [EBH] theory, modified Elwert factor (relativistic) Bethe-Heitler (FmodBH) theory for ordinary bremsstrahlung (OB) and the modified Elwert factor (relativistic) Bethe-Heitler (FmodBH+PB) theory, which includes the polarization bremsstrahlung (PB) into total bremsstrahlung (BS). The present results indicate the correctness of FmodBH+PB theory in the low energy region, where the contributions of PB into BS are dominant, which is described in terms of stripped atom (SA) approximation. But at the middle and higher energy region of the bremsstrahlung spectrum, where the contribution of PB is negligible, the FmodBH theory is more close to the experimental results. Hence, it is clear that the production of PB in the low energy region, due to the dynamic response of the target atom suppresses the production of bremsstrahlung at higher energy ends.

  5. INTERACTING COSMIC RAYS WITH MOLECULAR CLOUDS: A BREMSSTRAHLUNG ORIGIN OF DIFFUSE HIGH-ENERGY EMISSION FROM THE INNER 2°×1° OF THE GALACTIC CENTER

    International Nuclear Information System (INIS)

    The high-energy activity in the inner few degrees of the Galactic center is traced by diffuse radio, X-ray, and γ-ray emission. The physical relationship between different components of diffuse gas emitting at multiple wavelengths is a focus of this work. We first present radio continuum observations using the Green Bank Telescope and model the nonthermal spectrum in terms of a broken power-law distribution of ∼GeV electrons emitting synchrotron radiation. We show that the emission detected by Fermi is primarily due to nonthermal bremsstrahlung produced by the population of synchrotron emitting electrons in the GeV energy range interacting with neutral gas. The extrapolation of the electron population measured from radio data to low and high energies can also explain the origin of Fe I 6.4 keV line and diffuse TeV emission, as observed with Suzaku, XMM-Newton, Chandra, and the H.E.S.S. observatories. The inferred physical quantities from modeling multiwavelength emission in the context of bremsstrahlung emission from the inner ∼300 × 120 pc of the Galactic center are constrained to have the cosmic-ray ionization rate ∼1-10 × 10–15 s–1, molecular gas heating rate elevating the gas temperature to 75-200 K, fractional ionization of molecular gas 10–6-10–5, large-scale magnetic field 10-20 μG, the density of diffuse and dense molecular gas ∼100 and ∼103 cm–3 over 300 pc and 50 pc path lengths, and the variability of Fe I Kα 6.4 keV line emission on yearly timescales. Important implications of our study are that GeV electrons emitting in radio can explain the GeV γ-rays detected by Fermi and that the cosmic-ray irradiation model, like the model of the X-ray irradiation triggered by past activity of Sgr A*, can also explain the origin of the variable 6.4 keV emission from Galactic center molecular clouds.

  6. A Numerical Study of On-Axis Dose Rate from Ta and W Bremsstrahlung Converter Targets

    International Nuclear Information System (INIS)

    The bremsstrahlung converter target in radiographic accelerators is not, in general, considered a high-technology piece of equipment. In its essential form it is merely a solid plate of high-Z metal, usually tungsten (W) or tantalum (Ta); electrons go in, X-rays come out [1]. However, there are some important factors to keep in mind for this kind of target system. One is a constraint on the target itself: the proper thickness of material. Too little material reduces the probability that an electron will have a significant nuclear collision before exiting the plate. Too much material has a number of effects: small-angle scattering will occur to such an extent that bremsstrahlung photons will not be pointed in the forward direction. Electrons which small-angle scatter away and then back to the forward direction will have moved to larger radii as they traverse the target, increasing the effective source size. Electrons ''backscattered'' from the target --primaries or secondaries ejected from the upstream surface after sufficient angular scatter--exert a defocusing force on the incoming beam due to increased space charge at fixed (or even slightly reduced) current. Finally, a sufficiently thick target will begin to self-attenuate the X-ray photons produced in the upstream portion of the plate. A second constraint is obvious but is harder to accommodate when designing a radiographic accelerator system. The angular distribution of the incoming electron beam will change the forward dose. Just as electrons which have undergone small-angle scatter will no longer produce forward dose, electrons which have large angles before they ever enter the target cannot produce forward dose. Accurate prediction of dose requires incorporating the effect of the initial angle of the electron coming into the target material. The further step of controlling the angular distribution--which means keeping it as close to zero as possible--is difficult since it tends to drive important beam

  7. Thermal Bremsstrahlung probing nuclear multifragmentation in nucleus-nucleus collisions around the Fermi energy; Bremsstrahlung thermique comme sonde de la multifragmentation nucleaire dans les collisions noyau-noyau aux energies de Fermi

    Energy Technology Data Exchange (ETDEWEB)

    D' Enterria, D.G

    2000-05-15

    The thermodynamical properties of nuclear matter at moderate temperatures and densities, in the vicinity of the predicted nuclear liquid-gas phase transition, are studied using as experimental probe the hard-photons (E{sub {gamma}} > 30 MeV) emitted in nucleus-nucleus collisions. Photon and charged-particle production in four different heavy-ion reactions (Ar{sup 36} + Au{sup 197}, Ag{sup 107}, Ni{sup 58}, C{sup 12} at 60 A*MeV) is measured exclusively and inclusively coupling the TAPS photon spectrometer with two charged-particle and intermediate-mass-fragment detectors covering nearly 4{pi}. We confirm that Bremsstrahlung emission in first-chance (off-equilibrium) proton-neutron collisions (pn{gamma}) is the dominant origin of hard photons. We also firmly establish the existence of a thermal radiation component emitted in second-chance proton-neutron collisions. This thermal Bremsstrahlung emission takes place in semi-central and central nucleus-nucleus reactions involving heavy targets. We exploit this observation i) to demonstrate that thermal equilibrium is reached during the reaction, ii) to establish a new thermometer of nuclear matter based on Bremsstrahlung photons, iii) to derive the thermodynamical properties of the excited nuclear sources and, in particular, to establish a 'caloric curve' (temperature versus excitation energy), and iv) to assess the time-scales of the nuclear break-up process. (author)

  8. The luminescence of FSHA-800 type quartz - polymer optical fiber in the Bremsstrahlung gamma irradiation field

    International Nuclear Information System (INIS)

    Full text: The aim of investigations was the study of spectral and relaxation characteristics of radiation induced emission in the FSHA-800 type quartz-polymer optical fibres (OF) which are used as active media of Cherenkov's detectors in the CMS experiment (CERN). The part of OF with the length L turned in to ring of 5 cm of diameter was placed right of the way of a bunch of Bremsstrahlung gamma - rays. At the same time this OF was used for transportation of induced light which has been detected by EPP 2000C model Miniature Fiber Optic Spectrometer. The emission kinetics was measured by TDS 3032 model TEKTRONIX digital storage oscilloscope. Tungstate target plate being irradiated by electrons beam of MT-22C model microthrone (frequency of 400 Hz at a current of 7 μA) was as Bremsstrahlung gamma irradiation source (average energy of 7 MeV). For changing of irradiating dose rate the sample investigated was placed at the different distance from the target. The results of investigations The emission spectra are characterized by several bands with the maximum at 370, 420, 470, 520 and 670 nm. The transformation of the spectra take place for the different length of irradiating (L) of OF. The dose dependence of the observed emission depends on the irradiating length too. For the small value of L (0.5 m) the increasing of irradiation dose result in increasing of emission intensity. In the case of large L (5 m) we have opposite effect. The emission decay kinetics are characterized by (i) fast (time constant τ<1 μs) and slow (II) components (time constant τ- a few μs). The both spectra were measured at the irradiating dose of D=0.36 Mrad. The given curves are corrected on spectral sensitivity of the equipment. The nature of observed emission and its peculiarities are discussed in terms of existing models of radiation defect formation in the quartz glass. The influence of induced absorption on emission spectra transformation is considered. The authors express the

  9. Benchmarking of Monte Carlo simulation of bremsstrahlung from thick targets at radiotherapy energies

    Energy Technology Data Exchange (ETDEWEB)

    Faddegon, Bruce A.; Asai, Makoto; Perl, Joseph; Ross, Carl; Sempau, Josep; Tinslay, Jane; Salvat, Francesc [Department of Radiation Oncology, University of California at San Francisco, San Francisco, California 94143 (United States); Stanford Linear Accelerator Center, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); National Research Council Canada, Institute for National Measurement Standards, 1200 Montreal Road, Building M-36, Ottawa, Ontario K1A 0R6 (Canada); Institut de Tecniques Energetiques, Universitat Politecnica de Catalunya and Centro de Investigacion Biomedica en Red en Bioingenieria, Biomateriales y Nanomedicina (CIBER-BBN), Diagonal 647, 08028 Barcelona (Spain); Stanford Linear Accelerator Center, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Facultat de Fisica (ECM), Universitat de Barcelona, Societat Catalana de Fisica (IEC), Diagonal 647, 08028 Barcelona (Spain)

    2008-10-15

    Several Monte Carlo systems were benchmarked against published measurements of bremsstrahlung yield from thick targets for 10-30 MV beams. The quantity measured was photon fluence at 1 m per unit energy per incident electron (spectra), and total photon fluence, integrated over energy, per incident electron (photon yield). Results were reported at 10-30 MV on the beam axis for Al and Pb targets and at 15 MV at angles out to 90 degree sign for Be, Al, and Pb targets. Beam energy was revised with improved accuracy of 0.5% using an improved energy calibration of the accelerator. Recently released versions of the Monte Carlo systems EGSNRC, GEANT4, and PENELOPE were benchmarked against the published measurements using the revised beam energies. Monte Carlo simulation was capable of calculation of photon yield in the experimental geometry to 5% out to 30 degree sign , 10% at wider angles, and photon spectra to 10% at intermediate photon energies, 15% at lower energies. Accuracy of measured photon yield from 0 to 30 degree sign was 5%, 1 s.d., increasing to 7% for the larger angles. EGSNRC and PENELOPE results were within 2 s.d. of the measured photon yield at all beam energies and angles, GEANT4 within 3 s.d. Photon yield at nonzero angles for angles covering conventional field sizes used in radiotherapy (out to 10 degree sign ), measured with an accuracy of 3%, was calculated within 1 s.d. of measurement for EGSNRC, 2 s.d. for PENELOPE and GEANT4. Calculated spectra closely matched measurement at photon energies over 5 MeV. Photon spectra near 5 MeV were underestimated by as much as 10% by all three codes. The photon spectra below 2-3 MeV for the Be and Al targets and small angles were overestimated by up to 15% when using EGSNRC and PENELOPE, 20% with GEANT4. EGSNRC results with the NIST option for the bremsstrahlung cross section were preferred over the alternative cross section available in EGSNRC and over EGS4. GEANT4 results calculated with the &apos

  10. Absorbed dose distributions in a tissue-equivalent absorber for Bremsstrahlung produced at the beamlines of the European Synchrotron Radiation Facility

    CERN Document Server

    Pisharody, M; Berkvens, P; Colomp, P

    2000-01-01

    The absorbed-dose distributions for Bremsstrahlung, incident on a tissue-equivalent phantom, were measured with LiF : Mg,Ti thermoluminescent dosimeters at two insertion device beamlines of the European Synchrotron Radiation Facility (ESRF). The measurements were carried out for two different electron beam energies of 4 and 6 GeV. The corresponding Bremsstrahlung spectra and power were measured using a high-resolution lead glass total absorption calorimeter. The results are compared with similar measurements carried out at other facilities. The normalized Bremsstrahlung absorbed dose in a cross-sectional area of 100 mm sup sup 2 , at a depth of 150 mm of the phantom, was measured as 6.1 and 3.6 kGy h sup sup - sup sup 1 W sup sup - sup sup 1 for the corresponding Bremsstrahlung spectra of 4 and 6 GeV.

  11. Planar and axial coherent bremsstrahlung of type A from a 17-MeV electron beam in a diamond crystal

    International Nuclear Information System (INIS)

    Making use of the many-beam (one- and two-dimensional quantum treatment) formalism for transversely bound electrons moving through crystal lattices, we have computed planar and axial coherent bremsstrahlung (type A) spectra for 17-MeV electrons passing through a 10-μm thick diamond (C) crystal. We found that in the planar case the momentum transfer occurs in the direction perpendicular to the plane and results in a photon emission in the forward direction (electron-beam direction). In the axial case, the momentum transfer occurs in the plane perpendicular to the axis of interest. Only momentum transfers along the scan direction (electron transverse momentum direction) result in a photon emission in the forward direction. Two different scans have shown that the energies of the coherent bremsstrahlung peaks depend strongly on the direction of the electron transverse momentum but the intensities of the strongest peaks do not show any considerable change

  12. Fragment Characteristics from Photofission of 234U and 238U Induced by 6.0 - 9.0 Mev Bremsstrahlung

    Science.gov (United States)

    Göök, A.; Barday, R.; Chernykh, M.; Eckardt, C.; Enders, J.; Neumann-Cosel, P. Von; Poltoratska, Y.; Wagner, M.; Richter, A.; Oberstedt, S.; Hambsch, F.-J.; Oberstedt, A.

    2011-10-01

    As a preparatory experiment for a search for parity violation in photofission, fission of 238U and 234U induced by 6 - 9 MeV bremsstrahlung has been investigated at the superconducting Darmstadt electron linear accelerator S-DALINAC. Using a twin Frisch grid ionization chamber fission fragment energy and mass distributions have been determined by means of the double kinetic energy technique. The experiment was performed in order to test the ionization chamber's performance in a bremsstrahlung environment. Results on the fission fragment characteristics from the 238U(γ,f) reaction are found to be in good agreement with literature values. In addition results on fission fragment mass and energy distributions from the 234U(γ,f) reaction are presented for the first time in this energy region.

  13. Radiation shielding considerations against gas bremsstrahlung for the BioXAS beamlines at the Canadian Light Source

    International Nuclear Information System (INIS)

    The BioXAS beamlines consist of an undulator beamline followed by two wiggler beamlines sharing the same insertion device. To contain gas bremsstrahlung in the primary optical enclosure (POE), three tungsten blocks are placed, one of which is common to all the three beamlines. A radiation shielding study is carried out for primary and secondary gas bremsstrahlung of the BioXAS beamlines. Dose rates behind the back wall, side wall and the top of the roof are obtained by calculating energy depositions in a water phantom, which surrounds the POE. Discussion is made regarding the adequacy of radiation shielding for the BioXAS beamlines, which will be built in the near future at the Canadian Light Source.

  14. Dosimetry and microdosimetry using LET spectrometer based on the track-etch detector: radiotherapy bremsstrahlung beam, onboard aircraft radiation field

    Czech Academy of Sciences Publication Activity Database

    Jadrníčková, Iva; Spurný, František

    2006-01-01

    Roč. 41, č. 4 (2006), s. 421-429. ISSN 0033-8451 R&D Projects: GA ČR GA202/04/0795; GA ČR(CZ) GD202/05/H031 Institutional research plan: CEZ:AV0Z10480505 Keywords : linear energy transfer * bremsstrahlung beam * onboard aircraft Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders

  15. Blastomogenic action of various doses of bremsstrahlung from the LUEh-5 linear electron accelerator on the rat liver

    International Nuclear Information System (INIS)

    Rat liver removed from the abdominal cavity was subjected to a single local bremsstrahlung exposure from a linear electron accelerator in doses 1000, 2300, 4600 and 6900 R. Such an exposure was shown to have a blastomogenic action which manifested itself mainly in the occurrence of cholangiocellular timours. The most frequent occurrence of neoplasms (55,5%) was observed at the dose of 4600 R

  16. Integral (effective) and differential linear coefficients of X-ray bremsstrahlung attenuation and effective build up factors of scattered radiation

    International Nuclear Information System (INIS)

    Computer calculations of the values of integral (effective) and differential linear factors of X-ray bremsstrahlung attenuation for radiation flaw detection were conducted. The values of effective build up factors of scattered radiation were calculated as well. Calculations were conducted in geometry of ''narrow'' beam in 20-400 kV range of tube voltage for Mg, Al, Ti, Fe base alloys of 1-500 mm thickness. Calculation data are tabulated

  17. One-loop corrections to the process e+e- → tt-bar including hard bremsstrahlung

    International Nuclear Information System (INIS)

    Radiative corrections to the process e+e- → tt-bar are Calculated in one-loop approximation of the Standard Model. There exist results from several groups. This talk provides further comparisons of the complete electroweak contributions, including hard bremsstrahlung. The excellent final agreement of the different groups allows to continue by working on a code for an event generator for TESLA and an extension to e+e- → 6 fermions. (author)

  18. Investigation and realization at the Saclay linear accelerator of a line from a tagged photon beam bremsstrahlung in a wide energy range: Application to the measurement of the total cross section of the photofission (γ, f) of uranium 238

    International Nuclear Information System (INIS)

    A monochromatic tagged photon facility is described. The source is produced by tagging the photons from a continuous bremsstrahlung spectrum resulting from a monoenergetic electron beam traversing a thin target. A magnetic spectrometer is used to detect and measure the energy of the tagged electrons associated with the tagged photons. Tagging system characteristics include: 16 adjacent paths; a tagged energy range equal to 20% to 80% of the energy of the electrons of the incident beam; a constant relative resolution of the tagged energy bands equal to ±4%. The acquisition system is described and an example of the use of the system (measurement of the total cross section of photofission of U238 between 20 and 120 MeV) is shown. Tests show that the system can cover a range of monochromatic photon energy from 12 to 176 MeV, divided into 32 energy bands, with only two adjustements to the accelerator

  19. Reconstruction of extensive air showers using the MIDAS molecular Bremsstrahlung detector

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Andre Ramos de [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Escola Politecnica; Bonifazi, Carla; Santos, Edivaldo Moura; Soares, Elvis do Amaral; Mello Neto, Joao Ramos Torres de [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Fisica; Almeida, Rogerio Menezes de [Universidade Federal Fluminense (EEIMVR/UFF), Volta Redonda, RJ (Brazil). Escola de Engenharia Industrial Metalurgica de Volta Redonda

    2011-07-01

    Full text: The weakly ionized plasma created in the atmosphere after the passage of an Extensive Air Shower (EAS) gives rise to the emission of continuous radiation known as Molecular Bremsstrahlung Radiation (MBR) as free electrons scatter off neutral nitrogen (and less frequently oxygen) molecules. The isotropic and unpolarized nature of MBR rises the possibility of an EAS detection similar to that using fluorescence telescopes to capture the ultraviolet light emitted by the ionized nitrogen molecules. The MBR emission, however, falls into the centimeter wavelength range, requiring the use of radio/microwave antennas instead of optical telescopes. In order to test the feasibility of the technique, the MIDAS (Microwave Detection of Air Showers) Collaboration has built a prototype detector where a parabolical reflector illuminates a multi-pixel camera of commercial TV satellite C-band (3.4-4.2 GHz) feeds. This work addresses the geometrical reconstruction of EAS induced by Ultra High Energy Cosmic Rays (UHECR) using the MIDAS detector. The reconstruction chain is similar to that currently applied to the Auger Fluorescence detector events. We have simulated the shower MBR emission assuming two different scenarios: coherent and incoherent emission, i.e., radiation intensity scaling quadratically and linearly with the energy of the primary particle. The MIDAS prototype detector's response is then simulated. Finally, given the simulated events in real data format, we reconstruct the shower's arrival direction, including direction uncertainties and estimate the expected rate of observed events. (author)

  20. X-rays from Proton Bremsstrahlung: Evidence from Fusion Reactors and Its Implication in Astrophysics

    CERN Document Server

    Luo, Nie

    2009-01-01

    In a fusion reactor, a proton and a neutron generated in previous reactions may again fuse with each other. Or they can in turn fuse with or be captured by an un-reacted deuteron. The average center-of-mass (COM) energy for such reaction is around 10 keV in a typical fusion reactor, but could be as low as 1 keV. At this low COM energy, the reacting nucleons are in an s-wave state in terms of their relative angular momentum. The single-gamma radiation process is thus strongly suppressed due to conservation laws. Instead the gamma ray released is likely to be accompanied by x-ray photons from a nuclear bremsstrahlung process. The x-ray thus generated has a continuous spectrum and peaks around a few hundred eV to a few keV. The average photon energy and spectrum properties of such a process are calculated with a semiclassical approach. The results give a peak near 1.1 keV for the proton-deuteron fusion and a power-to-the-minus-second law in the spectrum's high-energy limit. An analysis of some prior tokamak disc...

  1. Virtual- and bremsstrahlung corrections to b -> d l+ l- in the standard model

    CERN Document Server

    Asatrian, H M; Greub, C; Walker, M

    2003-01-01

    We present the calculation of the virtual- and bremsstrahlung corrections of O(alpha_s) to the matrix elements . This is the missing piece in the NNLL results for various observables associated with the process B-> X_d l+ l-, like the branching ratio, the CP-rate asymmetry and the forward-backward asymmetry. This paper is an extension of analogous calculations done by some of us for the process B-> X_s l+ l-. As the contributions of the diagrams induced by the operators O_1^u and O_2^u with a u-quark running in the quark loop are strongly CKM suppressed, they were omitted in the analysis of B->X_s l+ l-. This is no longer possible for B-> X_d l+ l-, as the corresponding contributions are not suppressed. The main new work therefore consists of calculating the O(alpha_s) corrections to . In this paper we restrict ourselves to the range 0.05 X_d l+ l- as expansions in the small parameters s/m_b^2, z = m_c^2/m_b^2 and s/(4 m_c^2). In the phenomenological analysis at the end of the paper we discuss the impact of ...

  2. Study of the inner Bremsstrahlung following the electron-capture decay of {sup 193} Pt

    Energy Technology Data Exchange (ETDEWEB)

    Chavez, J.Y.Z.; Cruz, M.T.F. da; Martins, M.N.; Santos, R.T. dos [Sao Paulo Univ., SP (Brazil). Inst. de Fisica; Zamboni, C.B.; Hamada, M.M.; Camargo, S.P. de; Medeiros, J.A.G. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil); Hindi, M.M. [Tennessee Technological Univ., Cookeville, TN (United States). Dept. of Physics

    1997-12-31

    We are measuring the inner Bremsstrahlung (I B) photons emitted in some of the electron-capture decays of {sup 193} Pt. The source was prepared with highly pure metal Pt. It was irradiated with neutron for 52 days and let to cool down for eight months. The remaining activities were due to {sup 193} Pt{sup g} (half-life 50 yr) and {sup 192} Ir (half-life 74 d), the latter coming from (n, {gamma}) reactions on a small content of Ir. We have used a radiochemistry method to reduce the Ir content of the source. The resulting Pt compound will be dissolved in a plastic scintillator disk. Most of the {sup 192} Ir decays are {beta}{sup -} and their signal in the plastic will be used as a veto for the I B-photon detector. We have performed simulations of the efficiency and absorption effects in the detection geometry. (author) 6 refs., 1 fig.; juan at if.usp.br; czamboni at net.ipen.br; hindi at hindi.physics.tntech.edu

  3. Reconstruction of extensive air showers using the MIDAS molecular Bremsstrahlung detector

    International Nuclear Information System (INIS)

    Full text: The weakly ionized plasma created in the atmosphere after the passage of an Extensive Air Shower (EAS) gives rise to the emission of continuous radiation known as Molecular Bremsstrahlung Radiation (MBR) as free electrons scatter off neutral nitrogen (and less frequently oxygen) molecules. The isotropic and unpolarized nature of MBR rises the possibility of an EAS detection similar to that using fluorescence telescopes to capture the ultraviolet light emitted by the ionized nitrogen molecules. The MBR emission, however, falls into the centimeter wavelength range, requiring the use of radio/microwave antennas instead of optical telescopes. In order to test the feasibility of the technique, the MIDAS (Microwave Detection of Air Showers) Collaboration has built a prototype detector where a parabolical reflector illuminates a multi-pixel camera of commercial TV satellite C-band (3.4-4.2 GHz) feeds. This work addresses the geometrical reconstruction of EAS induced by Ultra High Energy Cosmic Rays (UHECR) using the MIDAS detector. The reconstruction chain is similar to that currently applied to the Auger Fluorescence detector events. We have simulated the shower MBR emission assuming two different scenarios: coherent and incoherent emission, i.e., radiation intensity scaling quadratically and linearly with the energy of the primary particle. The MIDAS prototype detector's response is then simulated. Finally, given the simulated events in real data format, we reconstruct the shower's arrival direction, including direction uncertainties and estimate the expected rate of observed events. (author)

  4. Hydramite II screening tests of potential bremsstrahlung converter debris shield materials

    International Nuclear Information System (INIS)

    Results of a brief test series aimed at screening a number of potential bremsstrahlung converter debris shield materials are reported. These tests were run on Sandia National Laboratories' Hydramite II accelerator using a diode configuration which produces a pinched electron beam. The materials tested include: (1) laminated Kevlar 49/polyester and E-glass/polyester composites, (2) a low density laminated Kevlar 49 composite, and (3) two types of through-the-thickness reinforced Kevlar 49 composites. As expected, tests using laminated Kevlar 49/polyester shields showed that shield permanent set (i.e., permanent deflection) increased with increasing tantalum conversion foil thickness and decreased with increasing shield thickness. The through-the-thickness reinforced composites developed localized, but severe, back surface damage. The laminated composites displayed little back surface damage, although extensive internal matrix cracking and ply delaminations were generated. Roughly the same degree of permanent set was produced in shields made from the low density Kevlar 49 composite and the Kevlar 49/polyester. The E-glass reinforced shields exhibited relatively low levels of permanent set

  5. Pauli principle in the soft-photon approach to proton-proton bremsstrahlung

    International Nuclear Information System (INIS)

    A relativistic and manifestly gauge-invariant soft-photon amplitude, which is consistent with the soft-photon theorem and satisfies the Pauli principle, is derived for the proton-proton bremsstrahlung process. This soft-photon amplitude is the first two-u-two-t special amplitude to satisfy all theoretical constraints. The conventional Low amplitude can be obtained as a special case. It is demonstrated that previously proposed amplitudes for this process, both the (u,t) and (s,t) classes, violate the Pauli principle at some level. The origin of the Pauli principle violation is shown to come from two sources: (i) For the (s,t) class, the two-s-two-t amplitude transforms into the two-s-two-u amplitude under the interchange of two initial-state (or final-state) protons. (ii) For the (u,t) class, the use of an internal emission amplitude determined from the gauge-invariance constraint alone, without imposition of the Pauli principle, causes a problem. The resulting internal emission amplitude can depend upon an electromagnetic factor which is not invariant under the interchange of the two protons. copyright 1996 The American Physical Society

  6. A consistent meson-field-theoretical description of pp-bremsstrahlung

    CERN Document Server

    Eden, J A

    1996-01-01

    A parameter-free and relativistic extension of the RuhrPot meson-baryon model is used to define the dominant isoscalar meson-exchange currents. We compute pp-bremsstrahlung observables below the \\pi-production threshold using a relativistic hadronic current density that includes impulse, wave function re-orthonormalization, meson-recoil, \\bar{{\\rm N}}N creation and annihilation, \\rho\\pi\\gamma + \\omega\\pi\\gamma + \\rho\\eta\\gamma + \\omega\\eta\\gamma vector-meson decay and N\\Delta\\gamma(\\pi,\\rho) exchange currents. We obtain a good description of the available data. The N\\Delta\\gamma(\\pi) current is shown to dominate the large two-body contributions and closed-form expressions for various non-relativistic approximations are analyzed. An experimental sensitivity to the admixture of pseudo-scalar and pseudo-vector admixture of the NN\\pi interaction is demonstrated. We examine the Lorentz invariance of the NN\\rightleftharpoonsNN t-matrices and show a dominantly pseudo-vector NN\\pi coupling renders impulse approximati...

  7. Hidden Photon Compton and Bremsstrahlung in White Dwarf Anomalous Cooling and Luminosity Functions

    CERN Document Server

    Chang, Chia-Feng

    2016-01-01

    We computed the contribution of the Compton and Bremsstrahlung processes with a hidden light $U(1)_D$ neutral boson $\\gamma_D$ to the white dwarf G117-B15A anomalous cooling rate, as well as the white dwarf luminosity functions (WDLF). We demonstrated that for a light mass of hidden photon ($m_{\\gamma_D} \\ll$ a few keV), compatible results are obtained for the recent Sloan Digital Sky Survey and the SuperCOSMOS Sky Survey observation, but the stringent limits would be imposed on the kinetic mixing $\\epsilon$. We performed $\\chi^2$-tests to acquire a quantitative assessment on the WDLF data in the context of our model, computed under the assumption of different kinetic mixing $\\epsilon$, the age of the oldest computed stars $T_D$, and a constant star formation rate $\\psi$. Then taken together, the WDLF analysis of 2$\\sigma$ confidence interval $\\epsilon = \\left( 0.37^{+0.35}_{-0.37}\\right) \\times 10^{-14}$ is barely consistent with the cooling rate analysis at 2$\\sigma$ regime $\\epsilon = \\left( 0.97^{+0.35}_{...

  8. A proposed experiment to test the hydrodynamic interpretation of quantum mechanics using bremsstrahlung

    CERN Document Server

    Davidson, M P

    2003-01-01

    The mathematical expression for the electromagnetic current of a quantum particle describes an extended charge in the sense that it is non-vanishing over the volume of the wave packet or the Schroedinger wave for the particle. In the hydrodynamic model this charge current and associated density are interpreted as a physical reality. Coupling such a current to a classical electromagnetic field in the soft photon limit then results in a theory for radiation. It is shown that this predicts that bremsstrahlung is sometimes greatly suppressed when the force acting on the particle is due to a classical potential field and when the volume over which the force is active is small compared to the volume of the particle's wave packet. Solving the same problem using conventional quantum radiation theory gives a different result. Therefore it is possible to test this effect experimentally and either confirm or rule out a hydrodynamic model for Schroedinger wave mechanics. An experiment is proposed to make such a test. It ...

  9. Measurement of the virtual bremsstrahlung in the p+p and p+d systems

    International Nuclear Information System (INIS)

    Virtual bremsstrahlung yields measured in p+p→p+p+e+ +e- and p+d→3He+e+ +e- are presented. The experiments were performed with a 190 MeV polarized proton beam obtained from the cyclotron AGOR at KVI in Groningen. Differential cross sections, response functions and analyzing powers were obtained for both reactions in exclusive measurements in which all outgoing particles were measured in a coincidence setup between SALAD and TAPS. The data are compared with gauge-invariant calculations using a NN T-matrix fitted to elastic phase-shifts. For pp→ppe+ e- a reasonable agreement is found for all measured virtual-photon invariant masses, Mγ >15 MeV/c2 up to 80 MeV /c2. For the pd→3He e+e- angular distributions, the calculations underestimate the data for θCM >100 o similar to what is found in the real-photon capture reaction. Refs. 7, figs. 2 (author)

  10. Search for 17-keV neutrinos in the internal bremsstrahlung spectrum of 125I

    International Nuclear Information System (INIS)

    We have conducted an experiment to search for the signature of a 17-keV neutrino in the internal bremsstrahlung (IB) spectrum of 125I. Gamma rays from a ∼ 100 mCi 125I point source were counted in a planar HPGe detector which is 16 mm in diameter and 10 mm in depth and which has a resolution of 560 eV at 122 keV. The source was counted for 61 d and the background for 17 d. At the start of the counting period the count rate was 650 s-1; the number of counts 17 keV below the 2p endpoint is 106 per keV. Data in the energy interval 120-150.5 keV were fitted with a theoretical spectrum calculated using nonrelativistic Hartree-Fock atomic wavefunctions. The preliminary fits reject the hypothesis of a 0.8% 17-keV neutrino at a confidence level of ≥ 98%. We are in the process of reanalyzing the data using recent relativistic theoretical shapes

  11. Isentropic focusing of supersonic plasma jets for magnetized target fusion

    International Nuclear Information System (INIS)

    It is shown that high energy flux densities can be reached by the isentropic Prandtl-Meyer compression flow of a supersonic plasma jet in a convergent nozzle. The energy flux density thereby increases in proportion to M2/(γ-1) where M is the Mach number of the jet and γ the specific heat ratio. With an axial magnetic field set up inside the nozzle by the thermomagnetic Nernst effect, the jet is magnetically insulated from the nozzle wall, reducing the bremsstrahlung radiation and conveniently magnetizing the target plasma. A sufficiently large number of spherically arranged nozzles can then be used for the ignition and confinement of a magnetized thermonuclear target

  12. Spatially resolved hard X-ray polarization in solar flares: effects of Compton scattering and bremsstrahlung

    Science.gov (United States)

    Jeffrey, N. L. S.; Kontar, E. P.

    2011-12-01

    Aims: We study the polarization of hard X-ray (HXR) sources in the solar atmosphere, including Compton backscattering of photons in the photosphere (the albedo effect) and the spatial distribution of polarization across the source. Methods: HXR photon polarization and spectra produced via electron-ion bremsstrahlung emission are calculated from various electron distributions typical for solar flares. Compton scattering and photoelectric absorption are then modelled using Monte Carlo simulations of photon transport in the photosphere to study the observed (primary and albedo) sources. Polarization maps across HXR sources (primary and albedo components) for each of the modelled electron distributions are calculated at various source locations from the solar centre to the limb. Results: We show that Compton scattering produces a distinct polarization variation across the albedo patch at peak albedo energies of 20-50 keV for all anisotropies modelled. The results show that there are distinct spatial polarization changes in both the radial and perpendicular to radial directions across the extent of the HXR source at a given disk location. In the radial direction, the polarization magnitude and direction at specific positions along the HXR source will either increase or decrease with increased photon distribution directivity towards the photosphere. We also show how high electron cutoff energies influence the direction of polarization at above ~100 keV. Conclusions: Spatially resolved HXR polarization measurements can provide important information about the directivity and energetics of the electron distribution. Our results indicate the preferred angular resolution of polarization measurements required to distinguish between the scattered and primary components. We also show how spatially resolved polarization measurements could be used to probe the emission pattern of an HXR source, using both the magnitude and the direction of the polarization.

  13. The nucleon-nucleon interaction in the presence of the electromagnetic field: Nucleon-nucleon bremsstrahlung

    International Nuclear Information System (INIS)

    Nucleon-nucleon bremsstrahlung, NNγ, is a fundamental process, which involves the strong and electromagnetic fields acting simultaneously. Since the electromagnetic interaction is well known, NNγ provides a calculable tool for comparing off-energy-shell effects from different two-nucleon potentials compared to experiment and also provides a simple testing ground, which is sensitive to meson-exchange-current contributions that are so important in electronuclear physics. Historically, experimental studies have focused on ppγ, with only a few measurements of npγ. The present workshop was organized primarily to investigate the interest in, the value of, and the feasibility of doing an npγ experiment using the neutron white source at LANL. An increasing amount of US nuclear physics dollars are being spent on electronuclear physics. npγ is a fundamental process with large meson-exchange currents. In the npγ calculations of Brown and Franklin, the meson-exchange contributions increase the cross section by a factor of roughly two and later the angular distribution of the emitted photon dramatically. The details of these calculated effects have never been verified experimentally, but the proper quantum-mechanical inclusion of meson-exchange contributions, using the methods of brown and Franklin, has proved to be essential in understanding the heavy-ion results. The understanding of the importance of such terms is extremely important inelectronuclear processes, such as are presently under investigation or being planned at Bates, SLAC, and CEBAF. Just one example is in the electrodisintegration of the deuteron, where meson-exchange contributions must be included properly before any conclusions about nuclear models, such as QCD versus meson-exchange potentials can be made

  14. Dependence of spectral shape of bremsstrahlung spectra on atomic number of target materials in the photon energy range of 5-30 keV

    International Nuclear Information System (INIS)

    Dependence of spectral shape of total bremsstrahlung spectra i.e. the sum of ordinary bremsstrahlung (OB) and polarization bremsstrahlung (PB), on the atomic number (Z) of target materials (Al, Ti, Sn and Pb), produced by continuous beta particles of 90Sr and 204Tl, has been investigated in the photon energy region of 5-30 keV. It has been found that the spectral shape of total bremsstrahlung spectra, in terms of S (k, Z) i.e. the number of photons of energy k per moc2 per beta disintegration, is not linearly dependent on the atomic number (Z) of the target material and rather it is proportional to Zn. At lower photon energies, the index values ‘n’ of Z-dependence are much higher than unity, which is due to the larger contribution of PB into OB. The decrease in ‘n’ values with increase of photon energy is due to the decrease in contribution of PB into OB. It is clear that the index ‘n’ values obtained from the modified Elwert factor (relativistic) Bethe-Heitler theory, which include the contribution PB into OB, are in agreement with the experimentally measured results using X-PIPS Si(Li) detector. Hence the contribution of PB into the formation of a spectral shape of total bremsstrahlung spectra plays a vital role.

  15. Electron acceleration by cascading reconnection in the solar corona I Magnetic gradient and curvature effects

    CERN Document Server

    Zhou, X; Barta, M; Gan, W; Liu, S

    2015-01-01

    Aims: We investigate the electron acceleration in convective electric fields of cascading magnetic reconnection in a flaring solar corona and show the resulting hard X-ray (HXR) radiation spectra caused by Bremsstrahlung for the coronal source. Methods: We perform test particle calculation of electron motions in the framework of a guiding center approximation. The electromagnetic fields and their derivatives along electron trajectories are obtained by linearly interpolating the results of high-resolution adaptive mesh refinement (AMR) MHD simulations of cascading magnetic reconnection. Hard X-ray (HXR) spectra are calculated using an optically thin Bremsstrahlung model. Results: Magnetic gradients and curvatures in cascading reconnection current sheet accelerate electrons: trapped in magnetic islands, precipitating to the chromosphere and ejected into the interplanetary space. The final location of an electron is determined by its initial position, pitch angle and velocity. These initial conditions also influ...

  16. Inverse Bremsstrahlung Stabilization of Noise in the Generation of Ultra-short Intense Pulses by Backward Raman Amplification

    International Nuclear Information System (INIS)

    Inverse bremsstrahlung absorption of the pump laser beam in a backward Raman amplifier over the round-trip light transit time through the sub-critical density plasma can more than double the electron temperature of the plasma and produce time-varying axial temperature gradients. The resulting increased Landau damping of the plasma wave and detuning of the resonance can act to stabilize the pump against unwanted amplification of Langmuir noise without disrupting nonlinear amplification of the femtosecond seed pulse. Because the heating rate increases with the charge state Z, only low-Z plasmas (hydrogen, helium, or helium-hydrogen mixtures) will maintain a low enough temperature for efficient operation

  17. Integrated analysis and consistency measurement of bremsstrahlung and charge exchange spectroscopy data for the determination of the ion effective charge

    International Nuclear Information System (INIS)

    In the context of Bayesian probability theory, we discuss a model for estimating the plasma ion effective charge Zeff, integrating data from both bremsstrahlung spectroscopy and individual impurity concentrations obtained via charge exchange spectroscopy (CXS). The validity of the model, taking into account statistical as well as systematic uncertainties, is shown via the deviance information criterion. The consistency of the continuum and CXS data regarding Zeff is improved, as measured by the symmetrized Kullback-Leibler divergence and the geodesic distance between the respective Zeff marginal posterior densities.

  18. Dosimetry and microdosimetry using LET spectrometer based on the track-etch detector: radiotherapy Bremsstrahlung beam, onboard aircraft radiation field

    International Nuclear Information System (INIS)

    The spectrometer of linear energy transfer (Let) based on the chemically etched poly-allyl-diglycol-carbonate (P.A.D.C.) track-etch detector was developed several years ago in our institute. This Let spectrometer enables determining Let of particles approximately from 10 to 700 keV/μm. From the Let spectra, dose characteristics can be calculated. The contribution presents the Let spectra and other dosimetric characteristics obtained onboard a commercial aircraft during more than 6 months long exposure and in the 18 MV radiotherapy Bremsstrahlung beam. (authors)

  19. Neutrino Oscillation in Magnetized Gamma-Ray Burst Fireball

    OpenAIRE

    Sahu, Sarira; Fraija, Nissim; Keum, Yong-Yeon

    2009-01-01

    Neutrinos of energy about 5-20 MeV are produced due to the stellar collapse or merger events that trigger the Gamma-Ray Burst. Also low energy MeV neutrinos are produced within the fireball due to electron positron annihilation and nucleonic bremsstrahlung. Many of these neutrinos will propagate through the dense and relativistic magnetized plasma of the fireball. We have studied the possibility of resonant oscillation of $\

  20. Monte-Carlo method simulation of the Bremsstrahlung mirror reflection experiment

    International Nuclear Information System (INIS)

    Full text: To detect gamma-ray mirror reflection on macroscopic smooth surface a search experiment at microtron MT-22S with 330 meter flying distance is in progress. Measured slip angles (i.e. angles between incident ray and reflector surface) don't exceed tens of micro-radian. Under such angles an effect of the reflection could be easily veiled due to negative background conditions. That is why the process needed to be simulated by Monte-Carlo method as accurate as possible and corresponding computer program was developed. A first operating mode of the MT-22S generates 13 MeV electrons that are incident on a Bremsstrahlung target. So energies of gamma-rays were simulated to be in the range of 0.01†12.5 MeV and be distributed by known Shift formula. When any gamma-quantum was incident on the reflector it resulted in following two cases. If its slip angle was more than the critical one, gamma-quantum was to be absorbed by the reflector and the program started to simulate next event. In the other case the program replaced incident gamma-quantum trajectory parameters by the reflected ones. The gamma-quantum trajectory behind the reflector was traced till its detector. Any gamma-quantum that got the detector was to be registered. As any simulated gamma-quantum was of random energy the critical slip angle of every simulated event was evaluated by the following formula: αcrit = eh/E √ZNAρ/πAm. Table values of the absorption coefficients were used for random simulation of gamma-quanta absorption in the air. And it was assumed that any gamma-quantum interaction with air resulted in its disappearance. Dependence of different flying distances (120 and 330 m), gap heights (10, 20 and 50 μ) of the gap collimator and inclinations (20 and 40 μrad) of the reflector's plane on detected gamma-quanta energy distribution and vertical angle one was studied with a help of the developed program

  1. Test of Compton camera components for prompt gamma imaging at the ELBE bremsstrahlung beam

    Science.gov (United States)

    Hueso-González, F.; Golnik, C.; Berthel, M.; Dreyer, A.; Enghardt, W.; Fiedler, F.; Heidel, K.; Kormoll, T.; Rohling, H.; Schöne, S.; Schwengner, R.; Wagner, A.; Pausch, G.

    2014-05-01

    In the context of ion beam therapy, particle range verification is a major challenge for the quality assurance of the treatment. One approach is the measurement of the prompt gamma rays resulting from the tissue irradiation. A Compton camera based on several position sensitive gamma ray detectors, together with an imaging algorithm, is expected to reconstruct the prompt gamma ray emission density map, which is correlated with the dose distribution. At OncoRay and Helmholtz-Zentrum Dresden-Rossendorf (HZDR), a Compton camera setup is being developed consisting of two scatter planes: two CdZnTe (CZT) cross strip detectors, and an absorber consisting of one Lu2SiO5 (LSO) block detector. The data acquisition is based on VME electronics and handled by software developed on the ROOT framework. The setup has been tested at the linear electron accelerator ELBE at HZDR, which is used in this experiment to produce bunched bremsstrahlung photons with up to 12.5 MeV energy and a repetition rate of 13 MHz. Their spectrum has similarities with the shape expected from prompt gamma rays in the clinical environment, and the flux is also bunched with the accelerator frequency. The charge sharing effect of the CZT detector is studied qualitatively for different energy ranges. The LSO detector pixel discrimination resolution is analyzed and it shows a trend to improve for high energy depositions. The time correlation between the pulsed prompt photons and the measured detector signals, to be used for background suppression, exhibits a time resolution of 3 ns FWHM for the CZT detector and of 2 ns for the LSO detector. A time walk correction and pixel-wise calibration is applied for the LSO detector, whose resolution improves up to 630 ps. In conclusion, the detector setup is suitable for time-resolved background suppression in pulsed clinical particle accelerators. Ongoing tasks are the quantitative comparison with simulations and the test of imaging algorithms. Experiments at proton

  2. Low-frequency radio emission caused by coherent magnetic Bremsstrahlung of charged particles of extensive air showers

    International Nuclear Information System (INIS)

    The possibility of detecting the high-energy cosmic rays by the magnetobremsstrahlung coherent low-frequency radiation of the extensive air shower is studied. It is shown that the field intensity for such a radio emission constitutes approximately 200 μkV/m MHz at the distance of 100 km for the particle with the initial energy of 1021 eV. The high intensity of the field, caused by this radiation mechanism, makes it possible to consider that it is the cause of the earlier determined high intensity of the shower radio emission on the low frequencies. The possibility of radio detection of the cosmic rays with the energy above 1021 eV is considered. The studies on the radio pulses accompanying the extensive air shower (EAS), are carried out by means of high-speed electronics. The EAS signal duration is evaluated as 10-20 μs

  3. Coronal Magnetic Fields Derived from Simultaneous Microwave and EUV Observations and Comparison with the Potential Field Model

    CERN Document Server

    Miyawaki, Shun; Shibasaki, Kiyoto; Shiota, Daikou; Nozawa, Satoshi

    2015-01-01

    We estimated the accuracy of coronal magnetic fields derived from radio observations by comparing them to potential field calculations and the DEM measurements using EUV observations. We derived line of sight component of the coronal magnetic field from polarization observations of the thermal bremsstrahlung in the NOAA active region 11150, observed around 3:00 UT on February 3, 2011 using the Nobeyama Radioheliograph at 17 GHz. Because the thermal bremsstrahlung intensity at 17 GHz includes both chromospheric and coronal components, we extracted only the coronal component by measuring the coronal emission measure in EUV observations. In addition, we derived only the radio polarization component of the corona by selecting the region of coronal loops and weak magnetic field strength in the chromosphere along the line of sight. The upper limit of the coronal longitudinal magnetic fields were determined as 100 - 210 G. We also calculated the coronal longitudinal magnetic fields from the potential field extrapola...

  4. Dose calculations using MARS for Bremsstrahlung beam stops and collimators in APS beamline stations.

    Energy Technology Data Exchange (ETDEWEB)

    Dooling, J.; Accelerator Systems Division (APS)

    2010-11-01

    The Monte Carlo radiation transport code MARS is used to model the generation of gas bremsstrahlung (GB) radiation from 7-GeV electrons which scatter from residual gas atoms in undulator straight sections within the Advanced Photon Source (APS) storage ring. Additionally, MARS is employed to model the interactions of the GB radiation with components along the x-ray beamlines and then determine the expected radiation dose-rates that result. In this manner, MARS can be used to assess the adequacy of existing shielding or the specifications for new shielding when required. The GB radiation generated in the 'thin-target' of an ID straight section will consist only of photons in a 1/E-distribution up to the full energy of the stored electron beam. Using this analytical model, the predicted GB power for a typical APS 15.38-m insertion device (ID) straight section is 4.59 x 10{sup -7} W/nTorr/mA, assuming a background gas composed of air (Z{sub eff} = 7.31) at room temperature (293K). The total GB power provides a useful benchmark for comparisons between analytical and numerical approaches. We find good agreement between MARS and analytical estimates for total GB power. The extended straight section 'target' creates a radial profile of GB, which is highly peaked centered on the electron beam. The GB distribution reflects the size of the electron beam that creates the radiation. Optimizing the performance of MARS in terms of CPU time per incident trajectory requires the use of a relatively short, high-density gas target (air); in this report, the target density is {rho}L = 2.89 x 10{sup -2} g/cm{sup 2} over a length of 24 cm. MARS results are compared with the contact dose levels reported in TB-20, which used EGS4 for radiation transport simulations. Maximum dose-rates in 1 cc of tissue phantom form the initial basis for comparison. MARS and EGS4 results are approximately the same for maximum 1-cc dose-rates and attenuation in the photon

  5. Determination of fission product yields in the 14 MeV photon (Bremsstrahlung) induced fission of 232Th

    International Nuclear Information System (INIS)

    The cumulative yields of various fission products in the 232Th(γ,f) with end-point Bremsstrahlung energy of 14 MeV having have been determined using off-line γ-ray spectrometric technique. The end-point Bremsstrahlung energy of 14 MeV was generated by impinging the electron beam on a solid graphite beam dump of the 20 electron LINAC (ELBE) at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany. From the cumulative fission yields, the mass chain yields were obtained by using charge distribution correction of medium energy. The fine structure in the mass yield distribution was interpreted from the point of nuclear structure effect such as shell closure proximity and even-odd effect. The mass yield distribution in 232Th(γ,f) is triple humped unlike 238U(γ,f), where it is double humped. This different behaviour in between 232Th* and 238U* was explained from the point of different potential energy surfaces between two systems. (author)

  6. Fission product yield distribution in the 12, 14, and 16 MeV bremsstrahlung-induced fission of 232Th

    International Nuclear Information System (INIS)

    The absolute cumulative yields of various fission products in the 12, 14, and 16 MeV bremsstrahlung-induced fission of 232Th were determined using a recoil catcher and an off-line γ -ray spectrometric technique using the ELBE electron linac of Helmholtz-Zentrum Dresden-Rossendorf in Dresden, Germany. The mass chain yields were obtained from the absolute cumulative yields by correcting the charge distribution. The peak-to-valley ratio, average light mass (left angle AL right angle) and heavy mass (left angle AH right angle) values, and average number of neutrons (left angle n right angle exp) in the bremsstrahlung-induced fission of 232Th at different excitation energies were obtained from the mass chain yield data. The present study and existing literature data for the 232Th(γ, f) reaction are compared with similar data for the 238U(γ, f) reaction at various excitation energies, and surprisingly different behavior was found in the two fissioning systems. (orig.)

  7. Attenuation of bremsstrahlung from 90Sr-90Y, 147Pm and 204Tl in thick target compounds

    Science.gov (United States)

    Manjunatha, H. C.

    2014-11-01

    The external bremsstrahlung (EB) produced by beta particles such as from 90Sr-90Y, 147Pm and 204Tl in PbCl2, PbF2, Pb(NO3)2 and CdO were measured using NaI(Tl) crystal. The beta stopper technique is employed to measure the integral intensities above 100 keV energy in different absorber thicknesses. Attenuation of the external bremsstrahlung, excited by 90Sr-90Y, 147Pm and 204Tl beta-emitters in the same compounds has also been studied. The measured attenuation parameter is not constant with absorber thickness and it increases with increasing Zmod of the absorber. Whereas, the mass attenuation coefficient of gamma rays of equivalent energy is independent of the absorber thickness. This confirms that the attenuation of EB in an absorber does not conform to a single exponential law, unlike the absorption of monoenergetic gamma rays. Rather it may be a combination of a large number of exponential terms.

  8. Coherent bremsstrahlung and channeling radiation from electrons of one to three MeV in silicon and gold

    International Nuclear Information System (INIS)

    The observation of sharp peaks in the x-ray spectrum from 1 to 3 MeV electrons striking thin single crystals of silicon and gold is reported. These peaks were observed in the range 1 to 25 keV. The peaks are of two different origins, both direct results of the periodic nature of the target crystals. The first kind of radiation is caused by the interference of incoming and scattered electron wave functions. Because of the periodicity of the target material there is a coherence effect for certain bremsstrahlung wave vectors. This coherent bremsstrahlung, though well known at very high electron energies, has never been adequately studied at electron energies below several hundred MeV. Detailed agreement between theoretical prediction and observation in silicon is shown. The second kind of radiation is caused by electrons channeled along major crystal axes. The electrons enter certain quantized orbits as they channel and may emit photons as a consequence of transitions between the various orbits. Observations of channeling radiation for various crystal axes in silicon are presented. Both phenomena were observed in gold, the first such observation for any metallic target

  9. SPECT using bremsstrahlung to quantify 90Y uptake in Baker's cysts: Its application in radiation synovectomy of the knee

    International Nuclear Information System (INIS)

    The use of SPECT with bremsstrahlung radiation has been investigated in studies on patients undergoing 90Y therapy for persistent synovitis of the knee. In particular, its value in the estimation of 90Y uptake into Baker's cysts was assessed and, to this end, realistic 'knee phantoms' were employed in order to calibrate for cysts of different size. Problems associated with the measurement of the extensive bremsstrahlung spectrum and the estimation of cyst volume have been discussed. It is shown that, although the apparent volume of a cyst is markedly dependent on the chosen count rate threshold, volumes greater than about 30 ml can be estimated with reasonable accuracy using a threshold of 50%. The uptake of 90Y in cysts, measured on 3 occasions within the first 2 days in 10 patients, showed wide variation (0%-40%) between patients and was poorly related to the size of cysts on arthrograms and to the clinical response to therapy. In these studies, the ability to analyse SPECT slices provided a distinct advantage over planar imaging for discriminating between 90Y uptake in cysts and adjacent sites. Retention of 90Y in the total knee was also widely variable, with losses of 2%-38% observed 2 days after injection which, in general, were not fully accounted for by uptake in liver or lymph nodes. The changing distribution of 90Y colloid in the knee during the first two days, as observed in some patients, might explain part of the discrepancy. (orig.)

  10. Modeling a one-dimensional bremsstrahlung and neutron imaging array for use on Sandia close-quote s Z machine

    International Nuclear Information System (INIS)

    Inertial confinement fusion is being studied on the Z facility at Sandia National Laboratories. Z is a large z-pinch machine which can provide 20 MA of current to z-pinch loads producing ∼1.8 MJ of soft x rays in less than 10 ns. Within the pinch region, decelerated electrons produce a strong source of bremsstrahlung radiation which varies from shot to shot. Additionally, a variety of inertial confinement fusion targets may produce fusion neutrons, the intensity and distribution of which depend on the temperature and density of the pinch. In this article, we describe the computer modeling behind the shielding design of a simple time-resolved, one-dimensional imaging array. This diagnostic will provide a time history for both the bremsstrahlung and neutron production as a function of height in the target. Calculations show that by building an array of scintillator fibers separated by long, thin tungsten collimator plates, a sampling rate of 0.254 mm at the target can be achieved. The corresponding channel-to-channel discrimination for such a design is shown to be better than 1000 ampersand as;1 for <4 MeV photons and 100 ampersand as;1 for 2.45 MeV neutrons. By coupling scintillator fibers to a fiber-optic streak camera system, the system time response is expected to be dominated by the scintillator response (∼1.2 ns). copyright 1999 American Institute of Physics

  11. The Small Contribution of Molecular Bremsstrahlung Radiation to the Air-Fluorescence Yield of Cosmic Ray Shower Particles

    CERN Document Server

    Samarai, I Al; Rosado, J

    2016-01-01

    A small contribution of molecular Bremsstrahlung radiation to the air-fluorescence yield in the UV range is estimated based on an approach previously developed in the framework of the radio-detection of showers in the gigahertz frequency range. First, this approach is shown to provide an estimate of the main contribution of the fluorescence yield due to the de-excitation of the C $^3\\Pi_{\\mathrm{u}}$ electronic level of nitrogen molecules to the B $^3\\Pi_{\\mathrm{g}}$ one amounting to $Y_{[337]}=(6.05\\pm 1.50)~$ MeV$^{-1}$ at 800 hPa pressure and 293 K temperature conditions, which compares well to previous dedicated works and to experimental results. Then, under the same pressure and temperature conditions, the fluorescence yield induced by molecular Bremsstrahlung radiation is found to be $Y_{[330-400]}^{\\mathrm{MBR}}=0.10~$ MeV$^{-1}$ in the wavelength range of interest for the air-fluorescence detectors used to detect extensive air showers induced in the atmosphere by ultra-high energy cosmic rays. This m...

  12. Energy spectra of secondary neutrons produced by high-energy bremsstrahlung in carbon, nitrogen, oxygen and tissue

    International Nuclear Information System (INIS)

    The energy spectra of secondary neutrons produced when bremsstrahlung of end-point energy in the range 10-30 MeV is incident on oxygen, carbon and nitrogen have been calculated. Photonuclear reactions of the type (γ,n) and (γ,pn) have been included. The respective contributions of various nuclear reactions have been adjusted using the published values of experimentally determined cross-sections, or branching ratios, where these are available. Where no such information exists in the literature, the values have been empirically estimated. Agreement has been obtained between the calculated photoneutron spectra from C, N and O at various energies and the available experimentally-measured spectra. The photoneutron spectra from C,N and O have been combined in the right proportion (C5H40O18N) to compute the spectra of secondary neutrons from tissue irradiated with bremsstrahlung of end-point energy from 10-30 MeV. Mean neutron energies and kerma factors for these spectra have been calculated. (author)

  13. Classical and quantum many-body description of bremsstrahlung in dense matter. Landau-Pomeranchuk-Migdal-effect

    International Nuclear Information System (INIS)

    Some considerations about the importance of coherence effects for bremsstrahlung processes in non-equilibrium dense matter (Landau-Pomeranchuk-Migdal-effect) are presented. They are of particular relevance for the application to photon - and di-lepton production from high energy nuclear collisions, to gluon radiation in QCD transport, or parton kinetics and to neutrino and axion radiation from supernova explosion and from hot neutron stars. The soft behavior of the bremsstrahlung from a source described by classical transport models is discussed and pocket correction formulas for the in-matter radiation cross sections are suggested in terms of standard transport coefficients. The radiation rates are also discussed within a non-equilibrium quantum field theory (Schwinger-Kadanoff-Baym-Keldysh) formulation. A classification of diagrams and corresponding resummation in physically meaningful terms is proposed, which considers the finite damping width of all source particles in matter. This way each diagram in this expansion is already free from the infra-red divergences. Both, the correct quasi-particle and quasi-classical limits are recovered from this subset of graphs. Explicit results are given for dense matter in thermal equilibrium. The diagrammatic description may suggest a formulation of a transport theory that includes the propagation of off-shell particles in non-equilibrium dense matter. (orig.)

  14. Angular distribution of Bremsstrahlung photons and of positrons for calculations of terrestrial gamma-ray flashes and positron beams

    CERN Document Server

    Koehn, Christoph

    2012-01-01

    Within thunderstorms electrons can gain energies of up to hundred(s) of MeV. These electrons can create X-rays and gamma-rays as Bremsstrahlung when they collide with air molecules. Here we calculate the distribution of angles between incident electrons and emitted photons as a function of electron and photon energy. We derive these doubly differential cross-sections by integrating analytically over the triply differential cross-sections derived by Bethe and Heitler; this is appropriate for light atoms like nitrogen and oxygen and for electron energies between 1 keV and 1 GeV. We also discuss some simplifying limit cases, and we derive some simple approximation for the most probable scattering angle. We also provide cross sections for the production of electron positron pairs from energetic photons when they interact with air molecules. This process is related to the Bremsstrahlung process by some physical symmetry. Therefore the results above can be transferred to predictions on the angles between incident p...

  15. Attenuation of bremsstrahlung from 90Sr–90Y, 147Pm and 204Tl in thick target compounds

    International Nuclear Information System (INIS)

    The external bremsstrahlung (EB) produced by beta particles such as from 90Sr–90Y, 147Pm and 204Tl in PbCl2, PbF2, Pb(NO3)2 and CdO were measured using NaI(Tl) crystal. The beta stopper technique is employed to measure the integral intensities above 100 keV energy in different absorber thicknesses. Attenuation of the external bremsstrahlung, excited by 90Sr–90Y, 147Pm and 204Tl beta-emitters in the same compounds has also been studied. The measured attenuation parameter is not constant with absorber thickness and it increases with increasing Zmod of the absorber. Whereas, the mass attenuation coefficient of gamma rays of equivalent energy is independent of the absorber thickness. This confirms that the attenuation of EB in an absorber does not conform to a single exponential law, unlike the absorption of monoenergetic gamma rays. Rather it may be a combination of a large number of exponential terms

  16. Dosimetric characteristics of thermoluminescent detectors for bremsstrahlung and electron radiation of the betatron B5M-25

    International Nuclear Information System (INIS)

    The results of experimental and calculational determination of coefficients for transition from readings of thermoluminescent detectors made of alumophosphate glass with manganese to absorbed dose in water for bremsstrahlung spectra generated at the voltage of 25 MV and 10-20 MeV electrons obtained in a betatron with electron beam sharping device are presented. Comparative measurements of absorbed dose have been obtained by means of ferrosulphate chemical system and two dosemeters with ionization chambers. Measurements have been conducted in water phantom. It is shown that the absorbed dose total measuring error does not exceed +-10% for 95% confidence interval. The obtained relations for calculation of coefficients for transition to absorbed dose and physical characteristics of thermoluminescent detectors can be used to forecast their behaviour in high-energy bremsstrahlung fields with arbitrary spectra as well as for determination of electron spectra with energy up to 25 MeV. It is established that for electrons with average energy of 10 and 20 MeV the dependence of the detector readings on the phantom depth does not exceed +-2% at depths from zero to 90% of electron range

  17. Soft x-ray bremsstrahlung and flourescent line production in the atmosphere by low energy electrons

    International Nuclear Information System (INIS)

    Several clues, such as pulse height distribution and angular distribution, that reveal the presence of low energy quasi-trapped or precipitating electrons capable of by-passing magnetic rejection schemes and penetrating the counter windows of soft x-ray detectors are discussed. (U.S.)

  18. Measurements and effects of backstreaming ions produced at bremsstrahlung converter target in Dragon-I linear induction accelerator

    International Nuclear Information System (INIS)

    Positive ions released from x-ray converter target impacted by electron beam of millimeter spot size can be trapped and accelerated in the incident beam's potential well. As the ions move upstream, the beam will be pinched first and then defocused at the target. Four Faraday cups are used to collect backstreaming ions produced at the bremsstrahlung converter target in Dragon-I linear induction accelerator (LIA). Experimental and theoretical results show that the backstreaming positive ions density and velocity are about 1021/m3 and 2-3 mm/μs, respectively. The theoretical and experimental results of electron beam envelope with ions and without ions are also presented. The discussions show that the backstreaming positive ions will not affect the electron beam focusing and envelope radius in Dragon-I LIA.

  19. Role of medium modifications for neutrino-pair processes from nucleon-nucleon bremsstrahlung - Impact on the protoneutron star deleptonization

    CERN Document Server

    Fischer, Tobias

    2016-01-01

    In this article the neutrino-pair production from nucleon-nucleon (NN) bremsstrahlung is explored via medium-modifications of the strong interactions at the level of the one-pion exchange approximation. It governs the bulk part of the NN interaction at low densities relevant for the neutrino physics in core-collapse supernova studies. The resulting medium modified one-pion exchange rate for the neutrino-pair processes is implemented in simulations of core collapse supernovae in order to study the impact on the neutrino signal emitted from the deleptonization of the nascent proto-neutron star. Consequences for the nucleosynthesis of heavy elements of the material ejected from the PNS surface are discussed.

  20. Fragment properties from fission of actinide nuclei induced by 6-10 MeV bremsstrahlungI

    Science.gov (United States)

    Gook, A.; Eckardt, C.; Enders, J.; Freudenberger, M.; von Neumann-Cosel, P.; Oberstedt, A.; Oberstedt, S.; Richter, A.

    Experiments to investigate the photon-induced fission of actinide nuclei at excitation energies in the vicinity of the fission barrier are carried out at the superconducting Darmstadt linear electron accelerator S-DALINAC. A twin-Frisch-grid ionization chamber is used to deduce mass, total kinetic energy, and angular distributions of the fission fragments. First experiments on 238U and 234U have shown that the experimental setup provides excellent conditions for investigating low-energy bremsstrahlung induced fission. Further experiments on 234U and 232Th are currently in progress. In this contribution results from the first experiment on fission fragment mass and total kinetic energy distributions from 234,238U are presented along with preliminary data from an on-going investigation of angular distributions from 234U(γ, f)

  1. A comparison of experiment, CEPXS/ONETRAN, TIGERP, and TIGER net electron emission coefficients for various bremsstrahlung spectra

    International Nuclear Information System (INIS)

    This work compares a carefully designed experiment to measure photoemission with the predictions of three different codes (CEPXS/ONETRAN, TIGERP, and TIGER) for the complex bremsstrahlung spectra typical of very intense pulsed power x-ray generators. The Monte Carlo codes TIGER and TIGERP can calculate the net photon-induced electron emission but accurate results may require that statistical error be minimized. CEPXS/ONETRAN is a new deterministic coupled electron/photon transport code that is faster than Monte Carlo and is not subject to statistical error. The comparison of net yields is a sensitive test of the relative accuracy and efficiency of these various codes. The authors find that all of the codes substantially agree with the experiments for the forward net yields. However, for reverse net yields from high-Z materials, the codes overpredict relative to measurements

  2. Production of isotopes and isomers with irradiation of Z = 47–50 targets by 23-MeV bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Karamian, S. A., E-mail: karamian@nrmail.jinr.ru [Joint Institute for Nuclear Research (Russian Federation); Carroll, J. J. [US Army Research Laboratory (United States); Aksenov, N. V.; Albin, Yu. A.; Belov, A. G.; Bozhikov, G. A.; Dmitriev, S. N.; Starodub, G. Ya. [Joint Institute for Nuclear Research (Russian Federation)

    2015-09-15

    The irradiations of Ag to Sn targets by bremsstrahlung generated with 23-MeV electron beams are performed at the MT-25 microtron. Gamma spectra of the induced activities have been measured and the yields of all detected radionuclides and isomers are carefully measured and analyzed. A regular dependence of yields versus changed reaction threshold is confirmed. Many isomers are detected and the suppression of the production probability is observed with growing product spin. Special peculiarities for the isomer-to-ground state ratios were deduced for the {sup 106m}Ag, {sup 108m}Ag, {sup 113m}In, {sup 115m}In, and {sup 123m}Sn isomers. The production of such nuclides as {sup 108m}Ag, {sup 115m}In, {sup 117g}In, and {sup 113m}Cd is of interest for applications, especially when economic methods are available.

  3. Study of the K shell photoelectric parameters of Dy, Yb and W atoms using low energy Bremsstrahlung radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hosur, S.B.; Naika, L.R.; Badiger, N.M. [Department of Studies in PhysicsKarnatak University, Dharwad - 580003 (India)

    2011-04-15

    Low energy external Bremsstrahlung (EB) photons were used to estimate the K shell photoelectric parameters; the K shell photoelectric cross section at the K edge, the K shell binding energy, the K shell jump ratio, the K shell jump factors, the Davisson-Kirchner ratio and the K shell oscillator strength for dysprosium (Dy), ytterbium (Yb) and tungsten (W) atoms. The EB photons are produced in the nickel (Ni) target by using the beta particles from a weak beta source of {sup 90}Sr-{sup 90}Y. These photons are made to fall on these elemental targets of our interest and the transmitted spectrum is measured using GMX 10P HPGe detector coupled to an 8K multichannel analyzer. The sharp decrease at the K edge in the measured spectrum is used to determine the K shell photoelectric parameters of these elements. The experimental results are in good agreement with the theoretical values. (authors)

  4. Study of the K shell photoelectric parameters of Dy, Yb and W atoms using low energy Bremsstrahlung radiation

    International Nuclear Information System (INIS)

    Low energy external Bremsstrahlung (EB) photons were used to estimate the K shell photoelectric parameters; the K shell photoelectric cross section at the K edge, the K shell binding energy, the K shell jump ratio, the K shell jump factors, the Davisson-Kirchner ratio and the K shell oscillator strength for dysprosium (Dy), ytterbium (Yb) and tungsten (W) atoms. The EB photons are produced in the nickel (Ni) target by using the beta particles from a weak beta source of 90Sr-90Y. These photons are made to fall on these elemental targets of our interest and the transmitted spectrum is measured using GMX 10P HPGe detector coupled to an 8K multichannel analyzer. The sharp decrease at the K edge in the measured spectrum is used to determine the K shell photoelectric parameters of these elements. The experimental results are in good agreement with the theoretical values. (authors)

  5. Higher-order corrections to electron-nucleus bremsstrahlung cross sections above a few MeV

    Science.gov (United States)

    Mangiarotti, A.; Martins, M. N.

    2016-08-01

    Despite the fact that the first calculations of nuclear bremsstrahlung cross sections were performed for relativistic electrons more than 80 years ago by Sauter, Bethe and Heitler, and Racah, a fully satisfactory solution to this problem is still missing up to the present day. Numerical approaches are impractical for electrons with energies above a few MeV because they require a prohibitively large number of partial waves. Analytic formulae need to describe simultaneously and accurately the interaction with the Coulomb field of the nucleus and the screening effect of the atomic electrons. In the present paper, a state-of-the-art analytic calculation will be discussed. In particular, higher-order corrections to the interaction with the Coulomb field of the nucleus, a subject seldom tackled in the past, are included and compared extensively with published data. The emerged difficulties will be highlighted, but unfortunately they can be overcome only with future large coordinated theoretical and experimental efforts.

  6. Observation of planar three-jet events in e+e- annihilation and evidence for gluon bremsstrahlung

    International Nuclear Information System (INIS)

    Topological distributions of charged and neutral hadrons from the reaction e+e%YI multihadrons are studied at √s of about 30 GeV. An excess of planar events is observed at a rate which cannot be explained by statistical fluctuations in the two-jet process. The planar events, mostly consisting of a slim jet on one side and a broader jet on the other, are shown actually to possess three-jet structure by demonstrating that the broader jet itself consists of two collinear jets in its own rest system. Detailed agreement between data and predictions is obtained if the process e+e- → q anti q g is taken into account. This strongly suggests gluon bremsstrahlung as the origin of the planar three-jet events. The data are consistent with a strong coupling constant αs (q2) of about 0.17. (orig.) 891 HSI/orig. 892 RDG

  7. Production of isotopes and isomers with irradiation of Z = 47–50 targets by 23-MeV bremsstrahlung

    International Nuclear Information System (INIS)

    The irradiations of Ag to Sn targets by bremsstrahlung generated with 23-MeV electron beams are performed at the MT-25 microtron. Gamma spectra of the induced activities have been measured and the yields of all detected radionuclides and isomers are carefully measured and analyzed. A regular dependence of yields versus changed reaction threshold is confirmed. Many isomers are detected and the suppression of the production probability is observed with growing product spin. Special peculiarities for the isomer-to-ground state ratios were deduced for the 106mAg, 108mAg, 113mIn, 115mIn, and 123mSn isomers. The production of such nuclides as 108mAg, 115mIn, 117gIn, and 113mCd is of interest for applications, especially when economic methods are available

  8. Quantitative comparison of PET and Bremsstrahlung SPECT for imaging the in vivo yttrium-90 microsphere distribution after liver radioembolization.

    Directory of Open Access Journals (Sweden)

    Mattijs Elschot

    Full Text Available BACKGROUND: After yttrium-90 ((90Y microsphere radioembolization (RE, evaluation of extrahepatic activity and liver dosimetry is typically performed on (90Y Bremsstrahlung SPECT images. Since these images demonstrate a low quantitative accuracy, (90Y PET has been suggested as an alternative. The aim of this study is to quantitatively compare SPECT and state-of-the-art PET on the ability to detect small accumulations of (90Y and on the accuracy of liver dosimetry. METHODOLOGY/PRINCIPAL FINDINGS: SPECT/CT and PET/CT phantom data were acquired using several acquisition and reconstruction protocols, including resolution recovery and Time-Of-Flight (TOF PET. Image contrast and noise were compared using a torso-shaped phantom containing six hot spheres of various sizes. The ability to detect extra- and intrahepatic accumulations of activity was tested by quantitative evaluation of the visibility and unique detectability of the phantom hot spheres. Image-based dose estimates of the phantom were compared to the true dose. For clinical illustration, the SPECT and PET-based estimated liver dose distributions of five RE patients were compared. At equal noise level, PET showed higher contrast recovery coefficients than SPECT. The highest contrast recovery coefficients were obtained with TOF PET reconstruction including resolution recovery. All six spheres were consistently visible on SPECT and PET images, but PET was able to uniquely detect smaller spheres than SPECT. TOF PET-based estimates of the dose in the phantom spheres were more accurate than SPECT-based dose estimates, with underestimations ranging from 45% (10-mm sphere to 11% (37-mm sphere for PET, and 75% to 58% for SPECT, respectively. The differences between TOF PET and SPECT dose-estimates were supported by the patient data. CONCLUSIONS/SIGNIFICANCE: In this study we quantitatively demonstrated that the image quality of state-of-the-art PET is superior over Bremsstrahlung SPECT for the

  9. Studies of total bremsstrahlung in thick targets of Al, Ti, Sn and Pb for 90Sr beta particles in the photon energy region of 1-100 keV

    Science.gov (United States)

    Singh, Amrit; Dhaliwal, A. S.

    2016-02-01

    Total bremsstrahlung (BS) spectra in thick targets of Al, Ti, Sn and Pb produced by beta emitter 90Sr (End point energy=546 keV) are studied in the photon energy range of 1-100 keV. The experimentally measured BS spectra are compared with the theoretical spectral distributions calculated from Elwert corrected (non relativistic) Bethe-Heitler [EBH] theory, modified Elwert factor (relativistic) Bethe-Heitler [Fmod BH] theory for ordinary bremsstrahlung (OB) and the Avdonina and Pratt [Fmod BH+PB] theory, which include the contribution of polarization bremsstrahlung (PB) into OB. The present results are indicating the correctness of Fmod BH+PB theory in the low energy region, where PB dominates into the BS, but at the middle and higher photon energy region of the bremsstrahlung spectrum, the Fmod BH theory is more close to the experimental results. The description of the bremsstrahlung process in stripped atom (SA) approximation, which indicates the suppression of the bremsstrahlung at higher energy ends due to the production of PB in the low energy region, needs further considerations. Hence, the present measurements for BS for different target materials indicates that the considerations of the screening effects along with other secondary effects during the interaction of incident electrons with the target nuclei are important while describing the production of bremsstrahlung, particularly for the higher energy regions.

  10. INTERACTING COSMIC RAYS WITH MOLECULAR CLOUDS: A BREMSSTRAHLUNG ORIGIN OF DIFFUSE HIGH-ENERGY EMISSION FROM THE INNER 2 Degree-Sign Multiplication-Sign 1 Degree-Sign OF THE GALACTIC CENTER

    Energy Technology Data Exchange (ETDEWEB)

    Yusef-Zadeh, F.; Roberts, D. A.; Royster, M. [Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States); Hewitt, J. W. [Code 662, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Wardle, M. [Department of Physics and Astronomy, and Research Center for Astronomy, Astrophysics and Astrophotonics, Macquarie University, Sydney, NSW 2109 (Australia); Tatischeff, V. [Center de Spectrometrie Nucleaire et de Spectrometrie de Massse, IN2P3/CNRS and Univ. Paris-Sud, F-91405 Orsay Campus (France); Cotton, W. [NRAO, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Uchiyama, H.; Nobukawa, M.; Tsuru, T. G. [Cosmic Ray Group, Physics, Kyoto University, Kitashirakawa-Oiwake-Cho, Sakyo, Kyoto 606-8502 (Japan); Heinke, C. [Department of Physics, Room 238 CEB, University of Alberta, Edmonton, AB T6G 2G7 (Canada)

    2013-01-01

    The high-energy activity in the inner few degrees of the Galactic center is traced by diffuse radio, X-ray, and {gamma}-ray emission. The physical relationship between different components of diffuse gas emitting at multiple wavelengths is a focus of this work. We first present radio continuum observations using the Green Bank Telescope and model the nonthermal spectrum in terms of a broken power-law distribution of {approx}GeV electrons emitting synchrotron radiation. We show that the emission detected by Fermi is primarily due to nonthermal bremsstrahlung produced by the population of synchrotron emitting electrons in the GeV energy range interacting with neutral gas. The extrapolation of the electron population measured from radio data to low and high energies can also explain the origin of Fe I 6.4 keV line and diffuse TeV emission, as observed with Suzaku, XMM-Newton, Chandra, and the H.E.S.S. observatories. The inferred physical quantities from modeling multiwavelength emission in the context of bremsstrahlung emission from the inner {approx}300 Multiplication-Sign 120 pc of the Galactic center are constrained to have the cosmic-ray ionization rate {approx}1-10 Multiplication-Sign 10{sup -15} s{sup -1}, molecular gas heating rate elevating the gas temperature to 75-200 K, fractional ionization of molecular gas 10{sup -6}-10{sup -5}, large-scale magnetic field 10-20 {mu}G, the density of diffuse and dense molecular gas {approx}100 and {approx}10{sup 3} cm{sup -3} over 300 pc and 50 pc path lengths, and the variability of Fe I K{alpha} 6.4 keV line emission on yearly timescales. Important implications of our study are that GeV electrons emitting in radio can explain the GeV {gamma}-rays detected by Fermi and that the cosmic-ray irradiation model, like the model of the X-ray irradiation triggered by past activity of Sgr A*, can also explain the origin of the variable 6.4 keV emission from Galactic center molecular clouds.

  11. Kinetic modeling of Nernst effect in magnetized hohlraums

    Science.gov (United States)

    Joglekar, A. S.; Ridgers, C. P.; Kingham, R. J.; Thomas, A. G. R.

    2016-04-01

    We present nanosecond time-scale Vlasov-Fokker-Planck-Maxwell modeling of magnetized plasma transport and dynamics in a hohlraum with an applied external magnetic field, under conditions similar to recent experiments. Self-consistent modeling of the kinetic electron momentum equation allows for a complete treatment of the heat flow equation and Ohm's law, including Nernst advection of magnetic fields. In addition to showing the prevalence of nonlocal behavior, we demonstrate that effects such as anomalous heat flow are induced by inverse bremsstrahlung heating. We show magnetic field amplification up to a factor of 3 from Nernst compression into the hohlraum wall. The magnetic field is also expelled towards the hohlraum axis due to Nernst advection faster than frozen-in flux would suggest. Nonlocality contributes to the heat flow towards the hohlraum axis and results in an augmented Nernst advection mechanism that is included self-consistently through kinetic modeling.

  12. Influence of the electron cyclotron resonance plasma confinement on reducing the bremsstrahlung production of an electron cyclotron resonance ion source with metal-dielectric structures.

    Science.gov (United States)

    Schachter, L; Stiebing, K E; Dobrescu, S

    2009-01-01

    The influence of metal-dielectric (MD) layers (MD structures) inserted into the plasma chamber of an electron cyclotron resonance ion source (ECRIS) onto the production of electron bremsstrahlung radiation has been studied in a series of dedicated experiments at the 14 GHz ECRIS of the Institut für Kernphysik der Universität Frankfurt. The IKF-ECRIS was equipped with a MD liner, covering the inner walls of the plasma chamber, and a MD electrode, covering the plasma-facing side of the extraction electrode. On the basis of similar extracted currents of highly charged ions, significantly reduced yields of bremsstrahlung radiation for the "MD source" as compared to the standard (stainless steel) source have been measured and can be explained by the significantly better plasma confinement in a MD source as compared to an "all stainless steel" ECRIS. PMID:19191430

  13. Optimization of energy window for {sup 90}Y bremsstrahlung SPECT imaging for detection tasks using the ideal observer with model-mismatch

    Energy Technology Data Exchange (ETDEWEB)

    Rong Xing; Ghaly, Michael; Frey, Eric C. [Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21287-0859 (United States)

    2013-06-15

    Purpose: In yttrium-90 ({sup 90}Y) microsphere brachytherapy (radioembolization) of unresectable liver cancer, posttherapy {sup 90}Y bremsstrahlung single photon emission computed tomography (SPECT) has been used to document the distribution of microspheres in the patient and to help predict potential side effects. The energy window used during projection acquisition can have a significant effect on image quality. Thus, using an optimal energy window is desirable. However, there has been great variability in the choice of energy window due to the continuous and broad energy distribution of {sup 90}Y bremsstrahlung photons. The area under the receiver operating characteristic curve (AUC) for the ideal observer (IO) is a widely used figure of merit (FOM) for optimizing the imaging system for detection tasks. The IO implicitly assumes a perfect model of the image formation process. However, for {sup 90}Y bremsstrahlung SPECT there can be substantial model-mismatch (i.e., difference between the actual image formation process and the model of it assumed in reconstruction), and the amount of the model-mismatch depends on the energy window. It is thus important to account for the degradation of the observer performance due to model-mismatch in the optimization of the energy window. The purpose of this paper is to optimize the energy window for {sup 90}Y bremsstrahlung SPECT for a detection task while taking into account the effects of the model-mismatch. Methods: An observer, termed the ideal observer with model-mismatch (IO-MM), has been proposed previously to account for the effects of the model-mismatch on IO performance. In this work, the AUC for the IO-MM was used as the FOM for the optimization. To provide a clinically realistic object model and imaging simulation, the authors used a background-known-statistically and signal-known-statistically task. The background was modeled as multiple compartments in the liver with activity parameters independently following a

  14. Optimization of energy window for 90Y bremsstrahlung SPECT imaging for detection tasks using the ideal observer with model-mismatch

    International Nuclear Information System (INIS)

    Purpose: In yttrium-90 (90Y) microsphere brachytherapy (radioembolization) of unresectable liver cancer, posttherapy 90Y bremsstrahlung single photon emission computed tomography (SPECT) has been used to document the distribution of microspheres in the patient and to help predict potential side effects. The energy window used during projection acquisition can have a significant effect on image quality. Thus, using an optimal energy window is desirable. However, there has been great variability in the choice of energy window due to the continuous and broad energy distribution of 90Y bremsstrahlung photons. The area under the receiver operating characteristic curve (AUC) for the ideal observer (IO) is a widely used figure of merit (FOM) for optimizing the imaging system for detection tasks. The IO implicitly assumes a perfect model of the image formation process. However, for 90Y bremsstrahlung SPECT there can be substantial model-mismatch (i.e., difference between the actual image formation process and the model of it assumed in reconstruction), and the amount of the model-mismatch depends on the energy window. It is thus important to account for the degradation of the observer performance due to model-mismatch in the optimization of the energy window. The purpose of this paper is to optimize the energy window for 90Y bremsstrahlung SPECT for a detection task while taking into account the effects of the model-mismatch. Methods: An observer, termed the ideal observer with model-mismatch (IO-MM), has been proposed previously to account for the effects of the model-mismatch on IO performance. In this work, the AUC for the IO-MM was used as the FOM for the optimization. To provide a clinically realistic object model and imaging simulation, the authors used a background-known-statistically and signal-known-statistically task. The background was modeled as multiple compartments in the liver with activity parameters independently following a Gaussian distribution; the

  15. Reconstruction of the Bremsstrahlung spectrum a medical linear accelerator from the gradient of the depth dose curve in a water container; Reconstruccion del espectro Bremsstrahlung emitido por un acelerador lineal medico a partir del gradiente de las curvas de dosisen profundidad en una cuba de agua

    Energy Technology Data Exchange (ETDEWEB)

    Juste, B.; Miro, R.; Verdu, G.; Diez, S.; Campayo, J. M.

    2010-07-01

    Determining the spectral distribution of the emitted photon medical linear accelerator (linac) used in radiotherapy treatment is extremely important for performing dosimetry calculations as to accurately calculate the therapeutic dose distributions. Since directly measure the spectrum is very complicated, this paper presents an indirect technique to accurately calculate the spectra of Bremsstrahlung photons emitted by linacs.

  16. Magnetic ripple and the modeling of lower-hybrid current drive in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Peysson, Y.; Arslanbekov, R.; Basiuk, V.; Carrasco, J.; Litaudon, X.; Moreau, D. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Bizarro, J.P. [Instituto Superior Tecnico, Lisbon (Portugal). Lab. de Quimica Organica

    1996-01-01

    Using ray-tracing, a detailed investigation of the lower hybrid (LH) wave propagation in presence of toroidal magnetic field ripple is presented. By coupling ray tracing with a one-dimensional relativistic Fokker-Planck code, simulations of LH experiments have been performed for the Tore Supra tokamak. Taking into account magnetic ripple in LH simulations, a better agreement is found between numerical predictions and experimental observations, such as non-thermal Bremsstrahlung emission, current profile, ripple-induced power losses in local magnetic mirrors, when plasma conditions correspond to the ` `few passes` regime. (author). 47 refs.

  17. Magnetic ripple and the modeling of lower-hybrid current drive in tokamaks

    International Nuclear Information System (INIS)

    Using ray-tracing, a detailed investigation of the lower hybrid (LH) wave propagation in presence of toroidal magnetic field ripple is presented. By coupling ray tracing with a one-dimensional relativistic Fokker-Planck code, simulations of LH experiments have been performed for the Tore Supra tokamak. Taking into account magnetic ripple in LH simulations, a better agreement is found between numerical predictions and experimental observations, such as non-thermal Bremsstrahlung emission, current profile, ripple-induced power losses in local magnetic mirrors, when plasma conditions correspond to the ' 'few passes' regime. (author)

  18. Photoactivation of the p-nucleus {sup 92}Mo at the bremsstrahlung measurement place of ELBE; Photoaktivierung des p-Kerns {sup 92}Mo am Bremsstrahlungsmessplatz von ELBE

    Energy Technology Data Exchange (ETDEWEB)

    Erhard, Martin Andreas

    2010-02-26

    By the high intensity of the bremsstrahlung of up to 20 MeV to 10{sup 9} MeV{sup -1}cm{sup -2}s{sup -1} in the energy range up to 20 MeV in the framework of this thesis for the first time not only the ({gamma},n), but also the ({gamma},p) reactions could be studied on {sup 92}Mo at astrophysically relevant energies.

  19. New electron-proton Bremsstrahlung rates for a hot plasma where the electron temperature is much smaller than the proton temperature

    OpenAIRE

    Mayer, M.

    2006-01-01

    Context: Observations of X-Ray sources harbouring a black hole and an accretion disc show the presence of at least two spectral components. One component is black-body radiation from an optically thick standard accretion disc. The other is produced in a optically thin corona and usually shows a powerlaw behaviour. Electron-proton (ep) bremsstrahlung is one of the contributing radiation mechanisms in the corona. Soft photons from the optically thick disc can Compton cool the electrons in the c...

  20. Measurement of Bremsstrahlung radiation for in vivo monitoring of 14C tracer distribution between fruit and roots of kiwifruit (Actinidia arguta) cuttings.

    Science.gov (United States)

    Black, Marykate Z; Minchin, Peter E H; Gould, Nick; Patterson, Kevin J; Clearwater, Michael J

    2012-10-01

    In vivo measurements of (14)C tracer distribution have usually involved monitoring the β(-) particles produced as (14)C decays. These particles are only detectable over short distances, limiting the use of this technique to thin plant material. In the present experiments, X-ray detectors were used to monitor the Bremsstrahlung radiation emitted since β(-) particles were absorbed in plant tissues. Bremsstrahlung radiation is detectable through larger tissue depths. The aim of these experiments was to demonstrate the Bremsstrahlung method by monitoring in vivo tracer-labelled photosynthate partitioning in small kiwifruit (Actinidia arguta (Siebold & Zucc.) Planch. ex Miq.) plants in response to root pruning. A source shoot, consisting of four leaves, was pulse labelled with (14)CO(2). Detectors monitored import into a fruit and the root system, and export from a source leaf. Repeat pulse labelling enabled the comparison of pre- and post-treatment observations within an individual plant. Diurnal trends were observed in the distribution of tracer, with leaf export reduced at night. Tracer accumulated in the roots declined after approximately 48 h, which may have resulted from export of (14)C from the roots in carbon skeletons. Cutting off half the roots did not affect tracer distribution to the remaining half. Tracer distribution to the fruit was increased after root pruning, demonstrating the higher competitive strength of the fruit than the roots for carbohydrate supply. Increased partitioning to the fruit following root pruning has also been demonstrated in kiwifruit field trials. PMID:22729822

  1. Numerical investigation into the highly nonlinear heat transfer equation with bremsstrahlung emission in the inertial confinement fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Habibi, M.; Oloumi, M.; Hosseinkhani, H.; Magidi, S. [Plasma and Fusion Research School, Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of)

    2015-10-15

    A highly nonlinear parabolic partial differential equation that models the electron heat transfer process in laser inertial fusion has been solved numerically. The strong temperature dependence of the electron thermal conductivity and heat loss term (Bremsstrahlung emission) makes this a highly nonlinear process. In this case, an efficient numerical method is developed for the energy transport mechanism from the region of energy deposition into the ablation surface by a combination of the Crank-Nicolson scheme and the Newton-Raphson method. The quantitative behavior of the electron temperature and the comparison between analytic and numerical solutions are also investigated. For more clarification, the accuracy and conservation of energy in the computations are tested. The numerical results can be used to evaluate the nonlinear electron heat conduction, considering the released energy of the laser pulse at the Deuterium-Tritium (DT) targets and preheating by heat conduction ahead of a compression shock in the inertial confinement fusion (ICF) approach. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. A bremsstrahlung gamma-ray source based on stable ionization injection of electrons into a laser wakefield accelerator

    CERN Document Server

    Döpp, A; Thaury, C; Lifschitz, A; Sylla, F; Goddet, J-P; Tafzi, A; Iaquanello, G; Lefrou, T; Rousseau, P; Conejero, E; Ruiz, C; Phuoc, K Ta; Malka, V

    2016-01-01

    Laser wakefield acceleration permits the generation of ultra-short, high-brightness relativistic electron beams on a millimeter scale. While those features are of interest for many applications, the source remains constraint by the poor stability of the electron injection process. Here we present results on injection and acceleration of electrons in pure nitrogen and argon. We observe stable, continuous ionization-induced injection of electrons into the wakefield for laser powers exceeding a threshold of 7 TW. The beam charge scales approximately linear with the laser energy and is limited by beam loading. For 40 TW laser pulses we measure a maximum charge of almost 1 nC per shot, originating mostly from electrons of less than 10 MeV energy. The relatively low energy, the high charge and its stability make this source well-suited for applications such as non-destructive testing. Hence, we demonstrate the production of energetic radiation via bremsstrahlung conversion at 1 Hz repetition rate. In accordance wit...

  3. Numerical investigation into the highly nonlinear heat transfer equation with bremsstrahlung emission in the inertial confinement fusion plasmas

    International Nuclear Information System (INIS)

    A highly nonlinear parabolic partial differential equation that models the electron heat transfer process in laser inertial fusion has been solved numerically. The strong temperature dependence of the electron thermal conductivity and heat loss term (Bremsstrahlung emission) makes this a highly nonlinear process. In this case, an efficient numerical method is developed for the energy transport mechanism from the region of energy deposition into the ablation surface by a combination of the Crank-Nicolson scheme and the Newton-Raphson method. The quantitative behavior of the electron temperature and the comparison between analytic and numerical solutions are also investigated. For more clarification, the accuracy and conservation of energy in the computations are tested. The numerical results can be used to evaluate the nonlinear electron heat conduction, considering the released energy of the laser pulse at the Deuterium-Tritium (DT) targets and preheating by heat conduction ahead of a compression shock in the inertial confinement fusion (ICF) approach. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Neutron-proton bremsstrahlung from intermediate energy heavy-ion reactions as a probe of the nuclear symmetry energy?

    International Nuclear Information System (INIS)

    Hard photons from neutron-proton bremsstrahlung in intermediate energy heavy-ion reactions are examined as a potential probe of the nuclear symmetry energy within a transport model. Effects of the symmetry energy on the yields and spectra of hard photons are found to be generally smaller than those due to the currently existing uncertainties of both the in-medium nucleon-nucleon cross sections and the photon production probability in the elementary process pn→pnγ. Very interestingly, nevertheless, the ratio of hard photon spectra R1/2(γ) from two reactions using isotopes of the same element is not only approximately independent of these uncertainties but also quite sensitive to the symmetry energy. For the head-on reactions of 132Sn + 124Sn and 112Sn + 112Sn at Ebeam/A=50 MeV, for example, the R1/2(γ) displays a rise up to 15% when the symmetry energy is reduced by about 20% at ρ=1.3ρ0 which is the maximum density reached in these reactions

  5. Electron elastic scattering and low-frequency bremsstrahlung on A@$C_{60}$: A model static approximation

    CERN Document Server

    Dolmatov, V K; Cooper, M B; Hunter, M E

    2015-01-01

    Electron elastic-scattering phase shifts and cross sections along with the differential and total cross sections and polarization of low-frequency bremsstrahlung upon low-energy electron collision with endohedral fullerenes $A$@C$_{60}$ are theoretically scrutinized versus the nature, size and spin of the encapsulated atom $A$. The case-study-atoms $A$ are N, Ar, Cr, Mn, Mo, Tc, Xe, Ba, and Eu. They are thoughtfully picked out of different rows of the periodic table. The study is performed in the framework of a model static approximation. There, both the encapsulated atom $A$ and C$_{60}$ cage are regarded as non-polarizable targets. The C$_{60}$ cage is modeled by an attractive spherical annular potential well. The study provides the most complete initial understanding of how the processes of interest might evolve upon electron collision with various $A$@C$_{60}$. Calculated results identify the most interesting and/or useful future measurements or more rigorous calculations of an electron+$A$@C$_{60}$ colli...

  6. The scattering of a bremsstrahlung radiation of electrons with energy 13 and 22 MeV from plane targets

    CERN Document Server

    Asatov, U T

    2002-01-01

    In the present work the characteristics of backward (90 sup d egbremsstrahlung radiation of electrons with energy 13 and 22 MeV with plane targets of different thickness from glass textolite, aluminium, iron, lead and their combination are investigated. The dependence of thickness of saturation of 'forward' scattered gamma radiation, a on angles of detection (theta sub s) and orientation (phi) of plane targets depending on a direction of probing beam was observed for the first time. For the first time, the numerical performances of beams of forward scattered gamma radiation from different targets were investigated and determined depending on their orientation and thickness. The new and corrected data on numerical performances of beams of the inverse scattered gamma radiation is obtained. The distinction in characteristics of beams of the scattered gamma radiation is s...

  7. Optical time of flight studies of lithium plasma in double pulse laser ablation: Evidence of inverse Bremsstrahlung absorption

    International Nuclear Information System (INIS)

    The early stage of formation of lithium plasma in a collinear—double pulse laser ablation mode has been studied using optical time of flight (OTOF) spectroscopy as a function of inter-pulse delay time, the distance from the target surface and the fluence of the ablation lasers. The experimental TOF measurements were carried out for lithium neutral (670.8 nm and 610.3 nm), and ionic (548.4 nm and 478.8 nm) lines. These experimental observations have been compared with that for single pulse laser ablation mode. It is found that depending on the fluence and laser pulse shape of the first pre-ablation laser and the second main ablation laser, the plasma plume formation and its characteristic features can be described in terms of plume-plume or laser-plume interaction processes. Moreover, the enhancement in the intensity of Li neutral and ionic lines is observed when the laser-plume interaction is the dominant process. Here, we see the evidence of the role of inverse Bremsstrahlung absorption process in the initial stage of formation of lithium plasma in this case

  8. Determination of the K absorption edge energy of Ho in element and its compounds using the bremsstrahlung technique

    Science.gov (United States)

    Niranjana, K. M.; Badiger, N. M.

    2013-05-01

    The K shell binding energies of Ho in element and in compounds Ho2O3 and HoF3 have been measured for the first time by adopting a novel method. The method involves a weak beta source, an external bremsstrahlung (EB) converter, element and compound targets and a high-resolution HPGe detector coupled to a 16K multichannel analyser. A spectrum of continuous EB photons, produced by the interaction of beta particles from a 90Sr-90Y radioactive source with an iron foil, is allowed to pass through the element and compound targets of Ho. The spectrum of transmitted EB photons is measured with a high-resolution HPGe detector spectrometer. The transmitted spectrum shows a sudden drop in intensity at K shell binding energy of the target. Such a sudden drop, which is essentially due to the onset of the K shell photoelectric effect, has been used to determine the K shell binding energy of Ho in element. The K shell binding energies of Ho in Ho2O3 and HoF3 compounds have also been determined using the same technique. From these data, the chemical shift in the K shell binding energy has been measured. It is found to be positive for Ho2O3 and negative for HoF3, indicating the dependence of the chemical shift on the crystal structure.

  9. A bremsstrahlung gamma-ray source based on stable ionization injection of electrons into a laser wakefield accelerator

    Science.gov (United States)

    Döpp, A.; Guillaume, E.; Thaury, C.; Lifschitz, A.; Sylla, F.; Goddet, J.-P.; Tafzi, A.; Iaquanello, G.; Lefrou, T.; Rousseau, P.; Conejero, E.; Ruiz, C.; Ta Phuoc, K.; Malka, V.

    2016-09-01

    Laser wakefield acceleration permits the generation of ultra-short, high-brightness relativistic electron beams on a millimeter scale. While those features are of interest for many applications, the source remains constraint by the poor stability of the electron injection process. Here we present results on injection and acceleration of electrons in pure nitrogen and argon. We observe stable, continuous ionization-induced injection of electrons into the wakefield for laser powers exceeding a threshold of 7 TW. The beam charge scales approximately with the laser energy and is limited by beam loading. For 40 TW laser pulses we measure a maximum charge of almost 1 nC per shot, originating mostly from electrons of less than 10 MeV energy. The relatively low energy, the high charge and its stability make this source well-suited for applications such as non-destructive testing. Hence, we demonstrate the production of energetic radiation via bremsstrahlung conversion at 1 Hz repetition rate. In accordance with GEANT4 Monte-Carlo simulations, we measure a γ-ray source size of less than 100 μm for a 0.5 mm tantalum converter placed at 2 mm from the accelerator exit. Furthermore we present radiographs of image quality indicators.

  10. Dynamical structure of magnetized dissipative accretion flow around black holes

    CERN Document Server

    Sarkar, Biplob

    2016-01-01

    We study the global structure of optically thin, advection dominated, magnetized accretion flow around black holes. We consider the magnetic field to be turbulent in nature and dominated by the toroidal component. With this, we obtain the complete set of accretion solutions for dissipative flows where bremsstrahlung process is regarded as the dominant cooling mechanism. We show that rotating magnetized accretion flow experiences virtual barrier around black hole due to centrifugal repulsion that can trigger the discontinuous transition of the flow variables in the form of shock waves. We examine the properties of the shock waves and find that the dynamics of the post-shock corona (PSC) is controlled by the flow parameters, namely viscosity, cooling rate and strength of the magnetic field, respectively. We separate the effective region of the parameter space for standing shock and observe that shock can form for wide range of flow parameters. We obtain the critical viscosity parameter that allows global accret...

  11. Neutrino oscillation in Magnetized Gamma-Ray Burst Fireball

    International Nuclear Information System (INIS)

    Energy MeV neutrinos are produced within the fireball due to electron positron annihilation and nucleonic bremsstrahlung. Many of these neutrinos will propagate through the dense and relativistic magnetized plasma of the fireball. We have studied the possibility of resonant oscillation of νe ↔ νμ,τ by taking into account the neutrino oscillation parameters from SuperKamiokande (SK). Using the resonance condition we have calculated the resonance length, lepton asymmetry and the baryon load for a fireball radius of 100 Km.

  12. Double Compton and Cyclo-Synchrotron in Super-Eddington Disks, Magnetized Coronae, and Jets

    CERN Document Server

    McKinney, Jonathan C; Wielgus, Maciek; Narayan, Ramesh; Sadowski, Aleksander

    2016-01-01

    We present an extension to the general relativistic radiation magnetohydrodynamic code HARMRAD to account for emission and absorption by thermal cyclo-synchrotron, double Compton, bremsstrahlung, low-temperature OPAL opacities as well as Thomson and Compton scattering. We approximate the radiation field as a Bose-Einstein distribution and evolve it using the radiation number-energy-momentum conservation equations in order to track photon hardening. We perform various simulations to study how these extensions affect the radiative properties of magnetically-arrested disks accreting at Eddington to super-Eddington rates. We find that double Compton dominates bremsstrahlung in the disk within a radius of $r\\sim 15r_g$ (gravitational radii) at a hundred times the Eddington accretion rate, and within smaller radii at lower accretion rates. Double Compton and cyclo-synchrotron regulate radiation and gas temperatures in the corona, while cyclo-synchrotron regulates temperatures in the jet. Interestingly, as the accre...

  13. Design of electron beam bending magnet system using three sector magnets for electron and photon therapy: a simulation approach

    International Nuclear Information System (INIS)

    The 270 degree doubly achromatic beam bending magnet system using three sector magnets has been designed mainly for treating cancer and skin diseases. The main requirements of the design of three magnet system is to focus an electron beam having a spot size less than 3mm x 3mm, energy spread within 3% and divergence angle ≤ 3 mrad at the target. To achieve these parameters the simulation was carried out using Lorentz-3EM software. The beam spot, divergence angle and energy spread were observed with respect to the variation in angles of sector magnets and drift distances. From the simulated results, it has been optimized that all the three sector magnets has an angle of 62 degree and the drift distance 68 mm. It is also observed that at the 1637, 2425, 3278, 4165 and 5690 Amp-turn, the optimized design produces 3851, 5754, 7434, 9356 and 11425 Gauss of magnetic field at median plane require to bend 6, 9, 12, 15 and 18 MeV energy of electron respectively for electron therapy. The output parameters of the optimized design are energy spread 3%, divergence angle ∼ 3 mrad and spot size 2.8 mm. Moreover, for 6 MV and 15 MV photon therapy application, an electron beam of energy 6.5 MeV and 15.5 MeV extracted from magnet system and focussed on the Bremsstrahlung target. For the photon therapy the 1780, and 4456 amp-turn, an optimized design produces 4148 and 9682 Gauss of magnetic field at median plane require to bend 6.5 and 15.5 MeV energy of electron respectively, which further produces Bremsstrahlung in Tungsten target. (author)

  14. WE-E-18A-05: Bremsstrahlung of Laser-Plasma Interaction at KeV Temperature: Forward Dose and Attenuation Factors

    International Nuclear Information System (INIS)

    Purpose: To obtain an analytical empirical formula for the photon dose source term in forward direction from bremsstrahlung generated from laser-plasma accelerated electron beams in aluminum solid targets, with electron-plasma temperatures in the 10–100 keV energy range, and to calculate transmission factors for iron, aluminum, methacrylate, lead and concrete and air, materials most commonly found in vacuum chamber labs. Methods: Bremsstrahlung fluence is calculated from the convolution of thin-target bremsstrahlung spectrum for monoenergetic electrons and the relativistic Maxwell-Juettner energy distribution for the electron-plasma. Unattenuatted dose in tissue is calculated by integrating the photon spectrum with the mass-energy absorption coefficient. For the attenuated dose, energy dependent absorption coefficient, build-up factors and finite shielding correction factors were also taken into account. For the source term we use a modified formula from Hayashi et al., and we fitted the proportionality constant from experiments with the aid of the previously calculated transmission factors. Results: The forward dose has a quadratic dependence on electron-plasma temperature: 1 joule of effective laser energy transferred to the electrons at 1 m in vacuum yields 0,72 Sv per MeV squared of electron-plasma temperature. Air strongly filters the softer part of the photon spectrum and reduce the dose to one tenth in the first centimeter. Exponential higher energy tail of maxwellian spectrum contributes mainly to the transmitted dose. Conclusion: A simple formula for forward photon dose from keV range temperature plasma is obtained, similar to those found in kilovoltage x-rays but with higher dose per dissipated electron energy, due to thin target and absence of filtration

  15. Strings in AdS 4 × ℂℙ 3 , Wilson loops in N $$ \\mathcal{N} $$ = 6 super Chern-Simons-matter and bremsstrahlung functions

    OpenAIRE

    Jeremías Aguilera-Damia; Diego H. Correa; Silva, Guillermo A.

    2014-01-01

    We find 1/6 BPS string configurations in AdS 4 × ℂℙ 3 , which we identify as the duals of certain 1/6 BPS circular Wilson loops in N $$ \\mathcal{N} $$ = 6 super Chern-Simons-matter gauge theory. We use our results to verify -in the strong coupling limit- a proposal made in arXiv:1402.4128 for a relation between the expectation value of these Wilson loops and the Bremsstrahlung function from deforming 1/2 BPS Wilson lines with a cusp. We also derive an analogous relation between the expectatio...

  16. Absolute sensitivity calibration of vacuum and extreme ultraviolet spectrometer systems and Z(eff) measurement based on bremsstrahlung continuum in HL-2A tokamak.

    Science.gov (United States)

    Zhou, Hangyu; Cui, Zhengying; Morita, Shigeru; Fu, Bingzhong; Goto, Motoshi; Sun, Ping; Dong, Chunfeng; Gao, Yadong; Xu, Yuan; Lu, Ping; Yang, Qingwei; Duan, Xuru

    2012-10-01

    A grazing-incidence flat-field extreme ultraviolet (EUV) spectrometer has been newly developed in HL-2A tokamak. Typical spectral lines are observed from intrinsic impurities of carbon, oxygen, iron, and extrinsic impurity of helium in the wavelength range of 20 Å-500 Å. Bremsstrahlung continuum is measured at different electron densities of HL-2A discharges to calibrate absolute sensitivity of the EUV spectrometer system and to measure effective ionic charge, Z(eff). The sensitivity of a vacuum ultraviolet (VUV) spectrometer system is also absolutely calibrated in overlapped wavelength range of 300 Å-500 Å by comparing the intensity between VUV and EUV line emissions. PMID:23126850

  17. Study of the Z-dependence of external bremsstrahlung produced by beta particles of sup 1 sup 4 sup 7 Pm and sup 3 sup 2 P

    CERN Document Server

    Dhaliwal, A S

    2003-01-01

    The Z-dependence of external bremsstrahlung (EB) produced by beta particles of sup 1 sup 4 sup 7 Pm and sup 3 sup 2 P beta emitters in Al, Cu, Sn, and Pb targets has been studied, as a function of photon energy, on the basis of the theoretical and experimental EB spectral distributions. The present results show that the values of the Z-dependence index, obtained both from Elwert-corrected Bethe-Heitler and Tseng and Pratt theories and from experiments, are not constant. It is found that the index n increases with increasing photon energy.

  18. The effect of the dc bias voltage on the x-ray bremsstrahlung and beam intensities of medium and highly charged ions of argon.

    Science.gov (United States)

    Rodrigues, G; Lakshmy, P S; Baskaran, R; Kanjilal, D; Roy, A

    2010-02-01

    X-ray bremsstrahlung measurements from the 18 GHz High Temperature Superconducting Electron Cyclotron Resonance Ion Source, Pantechnik-Delhi Ion Source were measured as a function of negative dc bias voltage, keeping all other source operating parameters fixed and the extraction voltage in the off condition. The optimization of medium and highly charged ions of argon with similar source operating parameters is described. It is observed that the high temperature component of the electron is altered significantly with the help of bias voltage, and the electron population has to be maximized for obtaining higher current. PMID:20192344

  19. The effect of the dc bias voltage on the x-ray bremsstrahlung and beam intensities of medium and highly charged ions of argon

    International Nuclear Information System (INIS)

    X-ray bremsstrahlung measurements from the 18 GHz High Temperature Superconducting Electron Cyclotron Resonance Ion Source, Pantechnik-Delhi Ion Source were measured as a function of negative dc bias voltage, keeping all other source operating parameters fixed and the extraction voltage in the off condition. The optimization of medium and highly charged ions of argon with similar source operating parameters is described. It is observed that the high temperature component of the electron is altered significantly with the help of bias voltage, and the electron population has to be maximized for obtaining higher current.

  20. Feasibility of bremsstrahlung dosimetry for direct dose estimation in patients undergoing treatment with {sup 90}Y-ibritumomab tiuxetan

    Energy Technology Data Exchange (ETDEWEB)

    Arrichiello, C.; Aloj, L.; Mormile, M.; D' Ambrosio, L.; Caraco, C.; De Martinis, F. [Istituto Nazionale per lo Studio e la Cura dei Tumori, Fondazione ' ' G. Pascale' ' , Nuclear Medicine Department, Napoli (Italy); Frigeri, F.; Arcamone, M.; Pinto, A. [Istituto Nazionale per lo Studio e la Cura dei Tumori, Fondazione ' ' G. Pascale' ' , Hematology-Oncology, Napoli (Italy); Stem Cells Transplantation Unit, Department of Hematology, Napoli (Italy); Lastoria, S. [Istituto Nazionale per lo Studio e la Cura dei Tumori, Fondazione ' ' G. Pascale' ' , Nuclear Medicine Department, Napoli (Italy); Istituto Nazionale per lo Studio e la Cura dei Tumori, Fondazione ' ' G. Pascale' ' , IRCCS, Napoli (Italy)

    2012-06-15

    on patient-specific dosimetry, the administered activity may be increased by an average factor of 2.4, indicating that most patients could be undertreated. The relative dosimetry approach based on planar imaging largely underestimates doses relative to reference values. Dosimetry based on planar bremsstrahlung imaging is not a dependable alternative to {sup 111}In dosimetry. (orig.)

  1. Neutrino emission in neutron matter from magnetic moment interactions

    CERN Document Server

    Jaikumar, P; Gale, C; Jaikumar, Prashanth; Gale, Charles

    2004-01-01

    Neutrino emission drives neutron star cooling for the first several hundreds of years after its birth. Given the low energy ($\\sim$ keV) nature of this process, one expects very few nonstandard particle physics contributions which could affect this rate. Requiring that any new physics contributions involve light degrees of freedom, one of the likely candidates which can affect the cooling process would be a nonzero magnetic moment for the neutrino. To illustrate, we compute the emission rate for neutrino pair bremsstrahlung in neutron-neutron scattering through photon-neutrino magnetic moment coupling. We also present analogous differential rates for neutrino scattering off nucleons and electrons that determine neutrino opacities in supernovae. Employing current upper bounds from collider experiments on the tau magnetic moment, we find that the neutrino emission rate can exceed the rate through neutral current electroweak interaction by a factor two, signalling the importance of new particle physics input to ...

  2. Interacting Cosmic Rays with Molecular Clouds: A Bremsstrahlung Origin of Diffuse High Energy Emission from the Inner 2deg by 1deg of the Galactic Center

    CERN Document Server

    Yusef-Zadeh, F; Wardle, M; Tatischeff, V; Roberts, D; Cotton, W; Uchiyama, H; Nobukawa, M; Tsuru, T G; Heinke, C; Royster, M

    2012-01-01

    The high energy activity in the inner few degrees of the Galactic center is traced by diffuse radio, X-ray and gamma-ray emission. The physical relationship between different components of diffuse gas emitting at multiple wavelengths is a focus of this work. We first present radio continuum observations using Green Bank Telescope and model the nonthermal spectrum in terms of a broken power-law distribution of GeV electrons emitting synchrotron radiation. We show that the emission detected by Fermi is primarily due to nonthermal bremsstrahlung produced by the population of synchrotron emitting electrons in the GeV energy range interacting with neutral gas. The extrapolation of the electron population measured from radio data to low and high energies can also explain the origin of FeI 6.4 keV line and diffuse TeV emission, as observed with Suzaku, XMM-Newton, Chandra and the H.E.S.S. observatories. The inferred physical quantities from modeling multi-wavelength emission in the context of bremsstrahlung emission...

  3. Optimization of the image contrast in SPECT-CT bremsstrahlung imaging for Selective Internal Radiation Therapy of liver malignancies with Y-90 microspheres

    CERN Document Server

    Bonutti, Faustino; Magro, Giuseppe; Cecotti, Andrea; Della Schiava, Emanuele; Del Dò, Elena; Longo, Francesco; Herassi, Yassine; Bentayeb, Farida; Rossi, Marina; Ferretti, Guido; Geatti, Onelio; Padovani, Renato

    2015-01-01

    The quality of SPECT Bremsstrahlung images of patients treated with Y-90 is poor, mainly because of scattered radiation and collimator septa penetration. To minimize the latter effect, High Energy (HE) or Medium Energy (ME) collimators can be used. Scatter correction is not possible through the methods commonly used for the diagnostic radionuclides (Tc-99m, etc.) because the Bremsstrahlung radiation does not have distinct photopeaks, but a broad spectrum of energies ranging from zero to the maximum one detectable by the gamma-camera crystal is registered. Scatter radiation and collimator septa penetration affect the Contrast and the Contrast Recovery Coefficient (CRC) : our research focused on finding the best energy position for the acquisition window in order to maximize these parameters. To be guided in this finding, we first made a Monte Carlo (MC) simulation of a SPECT acquisition of a Y-90 cylindrical phantom and then we measured at different energies the Line Spread Function (LSF) of a linear Y-90 sour...

  4. Measurement of the bremsstrahlung spectra generated from thick targets with =2–78 under the impact of 10 keV electrons

    Indian Academy of Sciences (India)

    Namita Yadav; Pragya Bhatt; Raj Singh; V S Subrahmanyam; R Shanker

    2010-04-01

    We present new experimental data on thick target bremsstrahlung spectra generated from the interaction of energetic electrons with bulk matter. The ‘photon yields’ in terms of double differential cross-sections (DDCS) are measured for pure elements of thick targets: Ti ( = 22), Ag ( = 47), W ( = 74) and Pt ( = 78) under the impact of 10 keV electrons. Comparison of DDCS obtained from the experimental data is made with those predicted by Monte-Carlo (MC) calculations using PENELOPE code. A close agreement between the experimental data and the MC calculations is found for all the four targets within the experimental error of 16%. Furthermore, the ratios of DDCS of bremsstrahlung photons emitted from Ag, W and Pt with those from Ti as a function of photon energy are examined with a relatively lower uncertainty of about 10% and they are compared with MC calculations. A satisfactory agreement is found between the experiment and the calculations within some normalizing factors. The variations of DDCS as a function of Z and of photon energy are also studied which show that the DDCS vary closely with Z; however, some deviations are observed for ‘tip’ photons emitted from high Z targets.

  5. Magnetic field dissipation in converging flows

    International Nuclear Information System (INIS)

    Converging flows (e.g., gas accreting on to compact objects) are often ionized and magnetized. As the gas in these systems compresses towards smaller radii, flux conservation acts to intensify the magnetic field B, which can attain superequipartition values. (Throughout this paper, equipartition is meant to imply a comparison between the energy density in the field and that of the particles only, not including turbulence.) Since such a field probably cannot remain anchored in the gas, it is often assumed that the field intensity in excess of equipartition (i.e., Beq) is dissipated as heat, and that B therefore saturates at its Beq value -the so-called 'equipartition assumption'. In this paper we make an attempt at developing a model for magnetic field dissipation based on resistive magnetic tearing, in order to provide a more realistic means of determining the evolution of B in cases where the contribution to the spectrum from magnetic bremsstrahlung is important. We find that the violation of equipartition can vary in degree from large to small radii, and in either direction. Thus the spectrum predicted on the basis of the equipartition assumption is not always an adequate representation of the actual state of the system. However, several major shortcomings remain in our formulation. For example, our approach in this paper is to consider the turbulence as being initiated primarily by hydrodynamic processes. Arguing that the magnetic field is frozen into the highly ionized plasma, we therefore adopt a magnetic field spatial distribution that mirrors that of the gas. This may be valid Only when the field is subequipartition, for otherwise the turbulent cascade may be influenced primarily by magnetic dissipation, rather than the hydrodynamics

  6. Fragment characteristics from fission of 238U and 234U induced by 6.5-9.0 MeV bremsstrahlung

    Science.gov (United States)

    Göök, A.; Chernykh, M.; Eckardt, C.; Enders, J.; von Neumann-Cosel, P.; Oberstedt, A.; Oberstedt, S.; Richter, A.

    2011-02-01

    Fission of 238U and 234U induced by bremsstrahlung of 6.5-9.0 MeV endpoint energy has been investigated at the superconducting Darmstadt electron linear accelerator S-DALINAC. Using a twin Frisch grid ionization chamber, fission-fragment energy and mass distributions have been determined by means of the double kinetic-energy technique. Results on the fission-fragment characteristics from U238(γ,f) are in agreement with results from the literature. In addition fission-fragment mass and energy distributions from U234(γ,f) are presented for the first time in this energy region. An analysis of fission modes within the Brosa model has been performed. The relative yield of the S1 mode was found to be (13±3)% in 234U and (35±2)% in 238U.

  7. Mixed optical Cherenkov-Bremsstrahlung radiation in vicinity of the Cherenkov cone from relativistic heavy ions: Unusual dependence of the angular distribution width on the radiator thickness

    Science.gov (United States)

    Rozhkova, E. I.; Pivovarov, Yu. L.

    2016-07-01

    The Cherenkov radiation (ChR) angular distribution is usually described by the Tamm-Frank (TF) theory, which assumes that relativistic charged particle moves uniformly and rectilinearly in the optically transparent radiator. According to the TF theory, the full width at half maximum (FWHM) of the ChR angular distribution inversely depends on the radiator thickness. In the case of relativistic heavy ions (RHI) a slowing-down in the radiator may sufficiently change the angular distribution of optical radiation in vicinity of the Cherenkov cone, since there appears a mixed ChR-Bremsstrahlung radiation. As a result, there occurs a drastic transformation of the FWHM of optical radiation angular distribution in dependence on the radiator thickness: from inversely proportional (TF theory) to the linearly proportional one. In our paper we present the first analysis of this transformation taking account of the gradual velocity decrease of RHI penetrating through a radiator.

  8. Measurement of yields for the {sup 197}Au(γ,xn){sup 197-x}Au reactions induced by 2.5 GeV Bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Hien, Nguyen Thi; Kim, Guinyun; Kim, Kwangsoo; Shahid, Muhammad; Zaman, Muhammah; Nadeem, Muhammad [Kyungpook National University, Daegu (Korea, Republic of); Khue, Pham Duc; Thanh, Kim Tien; Do, Nguyen Van [Vietnam Academy of Science and Technology, Hanoi (Viet Nam)

    2015-05-15

    Studies of high-energy nuclear reactions are of great important. It may help in deeper understanding of the reaction mechanisms and in extending of various fields of applications such as astrophysics, radiation physics, intense neutron source production and nuclear waste transmutation. The aim of the present work is to investigate the multineutron photonuclear on {sup 197}Au bombarded by 2.5 GeV Bremsstrahlung. Most of the photodisintegration products of gold with half-lives sufficient for the activity measurement. In this work, the necessary corrections were made in order to improve the accuracy of the experimental results The obtained experimental results are in good agreement with the calculated values. The yields for the {sup 197}Au(γ,xn){sup 197}-xAu reactions depend not only on the excitation energies but also on the number of neutrons ejected.

  9. Application of the photon-fluence scaling theorem to absorbed dose calorimetry for bremsstrahlung peak energy >1.02 MeV

    International Nuclear Information System (INIS)

    Application of the 'photon fluence scaling theorem' allows the ionization chamber to be placed at points in media where the photon fluence is the same, hence eliminating problems with energy response. The theorem is applicable to Compton scattered photons. For photon energies greater than 1.02 MeV, pair production alters the photon fluence in such a way as to invalidate the scaling theorem. In this report the effect of pair production is examined, so that a correction may be applied to the photon fluence scaling theorem. This correction extends application of the theorem for bremsstrahlung spectra up to at least 25 MeV peak energy. 10 refs., 4 tabs., 1 fig

  10. Low temperature in-situ measurements of FVP-300 type quartz - quartz optical fiber transmission in the Bremsstrahlung gamma irradiation field

    International Nuclear Information System (INIS)

    The aim of investigations was the study of spectral and relaxation characteristics of radiation induced absorption in the FVP-300 type quartz-quartz optical fibres (OF) which are used both as detector of charged particles and as collector of the induced Cherenkov radiation. The part of OF with the length l m turned in to ring of 5 cm of diameter directly, in thermostat, was irradiated by a bunch of Bremsstrahlung gamma - rays. (T=77 K, P=170 R/s, W=32 min). At the same time the other part of OF was used for transportation of probing light which has been detected by EPP 2000 deg. C model Miniature Fiber Optic Spectrometer. Tungstate target plate being irradiated by electrons beam of MT-22C model microthrone (frequency of 400 Hz at a current of 7 μA) was as Bremsstrahlung gamma irradiation source (average energy of 7 MeV). The OF transmission has been measured before, in-situ, and after stopping of irradiation at the temperature of liquid nitrogen. The result obtained enable us to calculate induced absorption spectra. The results of investigations are as follows: 1. The induced absorption spectra are characterized by several bands with the maximum at 560, 340 and 260 nm. 2. The induced absorption growth kinetic in the same for all bands and carriers two-stage character. 3. The relaxation of the induced absorption at temperature of liquid nitrogen is found out in the OF investigated. The investigation kinetics with a high degree of accuracy coincides for absorption canters of 560 and 340 nm. The results of investigation are discussed in terms of existing models of radiation defect formation in the quartz glass and data of low temperature thermoglow (TG). The analysis carried out will allow to serene a nature of nonstationary losses in the OF being in fields of ionizing radiations

  11. Observation of material, thickness, and bremsstrahlung x-ray intensity dependent effects in moderate and high Z targets in a gamma and x-ray LIDAR experiment

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaodong, E-mail: xzhang39@utk.edu [Department of Nuclear Engineering, University of Tennessee, TN 37996 (United States); Ayaz-Maierhafer, Birsen; Laubach, Mitchell A. [Department of Nuclear Engineering, University of Tennessee, TN 37996 (United States); Hayward, Jason P. [Department of Nuclear Engineering, University of Tennessee, TN 37996 (United States); Oak Ridge National Lab, Oak Ridge, TN 37831 (United States)

    2015-06-01

    A high energy gamma and x-ray LIDAR system consisting of a fast pulse (~50 ps, FWHM) LINAC and a Cherenkov detection system was used to investigate response differences among materials, their thicknesses, and bremsstrahlung x-ray intensities. The energies and pulse width of electrons used to produce bremsstrahlung x-rays were set at 20 or 40 MeV and 50 ps FWHM duration, respectively. The Cherenkov detector was built with a fused silica glass optically coupled to a 51 mm fast timing photomultiplier tube, which has an intrinsic energy threshold of 340.7 keV for Compton backscattered gammas. Such a fast detection system yields a coincidence resolving time of 93 ps FWHM, which is equivalent to a depth resolving capability of about 3 cm FWHM. The thicknesses of iron and lead targets were varied from 1 in. to 7 in. with a step of 1 in., and the thicknesses of DU were varied from 1/3 in. to 1 in. with a step of 1/3 in. The experimental results show that iron targets tend to produce a factor of five less observed x-rays and gammas, with less energetic photoelectron frequency distributions, compared with DU and lead targets for the same beam intensity and target thicknesses. Additionally, the self-shielding effect causes the lead to yield more gammas than the DU considering the experimental observation point. For the setup used in this study, a charge per pulse in the range of 1–2.5 nC yields the best resolving capability between the DU and lead targets.

  12. Observation of material, thickness, and bremsstrahlung x-ray intensity dependent effects in moderate and high Z targets in a gamma and x-ray LIDAR experiment

    Science.gov (United States)

    Zhang, Xiaodong; Ayaz-Maierhafer, Birsen; Laubach, Mitchell A.; Hayward, Jason P.

    2015-06-01

    A high energy gamma and x-ray LIDAR system consisting of a fast pulse (~50 ps, FWHM) LINAC and a Cherenkov detection system was used to investigate response differences among materials, their thicknesses, and bremsstrahlung x-ray intensities. The energies and pulse width of electrons used to produce bremsstrahlung x-rays were set at 20 or 40 MeV and 50 ps FWHM duration, respectively. The Cherenkov detector was built with a fused silica glass optically coupled to a 51 mm fast timing photomultiplier tube, which has an intrinsic energy threshold of 340.7 keV for Compton backscattered gammas. Such a fast detection system yields a coincidence resolving time of 93 ps FWHM, which is equivalent to a depth resolving capability of about 3 cm FWHM. The thicknesses of iron and lead targets were varied from 1 in. to 7 in. with a step of 1 in., and the thicknesses of DU were varied from 1/3 in. to 1 in. with a step of 1/3 in. The experimental results show that iron targets tend to produce a factor of five less observed x-rays and gammas, with less energetic photoelectron frequency distributions, compared with DU and lead targets for the same beam intensity and target thicknesses. Additionally, the self-shielding effect causes the lead to yield more gammas than the DU considering the experimental observation point. For the setup used in this study, a charge per pulse in the range of 1-2.5 nC yields the best resolving capability between the DU and lead targets.

  13. Magnetism and magnetic materials

    CERN Document Server

    Coey, J M D

    2010-01-01

    Covering basic physical concepts, experimental methods, and applications, this book is an indispensable text on the fascinating science of magnetism, and an invaluable source of practical reference data. Accessible, authoritative, and assuming undergraduate familiarity with vectors, electromagnetism and quantum mechanics, this textbook is well suited to graduate courses. Emphasis is placed on practical calculations and numerical magnitudes - from nanoscale to astronomical scale - focussing on modern applications, including permanent magnet structures and spin electronic devices. Each self-contained chapter begins with a summary, and ends with exercises and further reading. The book is thoroughly illustrated with over 600 figures to help convey concepts and clearly explain ideas. Easily digestible tables and data sheets provide a wealth of useful information on magnetic properties. The 38 principal magnetic materials, and many more related compounds, are treated in detail

  14. Photonuclear Studies for the Isomeric Yield Ratios in the Production of natFe(γ,xnp)52m,gMn with 50-,60-, and 70-MeV Bremsstrahlung

    Science.gov (United States)

    Shakilur Rahman, Md.; Kim, Guinyun; Kim, Kyung-Sook; Lee, Manwoo; Moinul Haque Meaze, A. K. M.

    2016-02-01

    The isomeric yield ratios in the production of natFe(γ,xnp)52m,gMn have been measured with photonuclear reactions. The high purity natural Fe metallic foils were used and irradiated with bremsstrahlung beams of end point energy 50-, 60-, and 70-MeV. The bremsstrahlung beams are produced with high energy electron beam struck with 0.1mm thin tungsten target. The activation method has been used and hence the induced activities in the irradiated foils were measured by off-line γ-ray spectrometric technique using HPGe detector coupled to a PC-based 4K MCA. The experimental values of isomeric ratios are compared with the theoretical values by statistical model code TALYS. The detail of the formation of isomers by photonuclear reactions together with the literature values of the investigated nuclides are compared and discussed.

  15. A FOURIER-TRANSFORMED BREMSSTRAHLUNG FLASH MODEL FOR THE PRODUCTION OF X-RAY TIME LAGS IN ACCRETING BLACK HOLE SOURCES

    International Nuclear Information System (INIS)

    Accreting black hole sources show a wide variety of rapid time variability, including the manifestation of time lags during X-ray transients, in which a delay (phase shift) is observed between the Fourier components of the hard and soft spectra. Despite a large body of observational evidence for time lags, no fundamental physical explanation for the origin of this phenomenon has been presented. We develop a new theoretical model for the production of X-ray time lags based on an exact analytical solution for the Fourier transform describing the diffusion and Comptonization of seed photons propagating through a spherical corona. The resulting Green's function can be convolved with any source distribution to compute the associated Fourier transform and time lags, hence allowing us to explore a wide variety of injection scenarios. We show that thermal Comptonization is able to self-consistently explain both the X-ray time lags and the steady-state (quiescent) X-ray spectrum observed in the low-hard state of Cyg X-1. The reprocessing of bremsstrahlung seed photons produces X-ray time lags that diminish with increasing Fourier frequency, in agreement with the observations for a wide range of sources

  16. Technical Considerations of Phosphorous-32 Bremsstrahlung SPECT Imaging after Radio embolization of Hepatic Tumors: A Clinical Assessment with a Review of Imaging Parameters

    International Nuclear Information System (INIS)

    Bremsstrahlung (BS) imaging during radio embolization (RE) confirms the deposition of radiotracer in hepatic/extrahepatic tumors. The aim of this study is to demonstrate '32P images and to optimize the imaging parameters. Materials and Methods. Thirty-nine patients with variable types of hepatic tumors, treated with the intra-arterial injection of 32P, were included. All patients underwent BS SPECT imaging 24-72 h after tracer administration, using low energy high resolution (LEHR) (18 patients) or medium energy general purpose (MEGP) (21 patients) collimators. A grading scale from 1 to 4 was used to express the compatibility of the 32P images with those obtained from CT/MRI. Results. Although the image quality obtained with the MEGP collimator was visually and quantitatively better than with the LEHR (76% concordance score versus 71%, resp.), there was no statistically significant difference between them. Conclusion. The MEGP collimator is the first choice for BS SPECT imaging. However, if the collimator change is time consuming (as in a busy center) or an MEGP collimator is not available, the LEHR collimator could be practical with acceptable images, especially in a SPECT study. In addition, BS imaging is a useful method to confirm the proper distribution of radiotherapeutic agents and has good correlation with anatomical findings.

  17. A FOURIER-TRANSFORMED BREMSSTRAHLUNG FLASH MODEL FOR THE PRODUCTION OF X-RAY TIME LAGS IN ACCRETING BLACK HOLE SOURCES

    Energy Technology Data Exchange (ETDEWEB)

    Kroon, John J.; Becker, Peter A., E-mail: jkroon@gmu.edu, E-mail: pbecker@gmu.edu [School of Physics, Astronomy, and Computational Sciences, George Mason University, Fairfax, VA 22030-4444 (United States)

    2014-04-20

    Accreting black hole sources show a wide variety of rapid time variability, including the manifestation of time lags during X-ray transients, in which a delay (phase shift) is observed between the Fourier components of the hard and soft spectra. Despite a large body of observational evidence for time lags, no fundamental physical explanation for the origin of this phenomenon has been presented. We develop a new theoretical model for the production of X-ray time lags based on an exact analytical solution for the Fourier transform describing the diffusion and Comptonization of seed photons propagating through a spherical corona. The resulting Green's function can be convolved with any source distribution to compute the associated Fourier transform and time lags, hence allowing us to explore a wide variety of injection scenarios. We show that thermal Comptonization is able to self-consistently explain both the X-ray time lags and the steady-state (quiescent) X-ray spectrum observed in the low-hard state of Cyg X-1. The reprocessing of bremsstrahlung seed photons produces X-ray time lags that diminish with increasing Fourier frequency, in agreement with the observations for a wide range of sources.

  18. Initial-state bremsstrahlung versus final-state hydrodynamic sources of azimuthal harmonics in p+A at RHIC and LHC

    Energy Technology Data Exchange (ETDEWEB)

    Gyulassy, M. [MTA WIGNER Research Centre for Physics, RMI, Budapest (Hungary); Department of Physics, Columbia University, New York, NY 10027 (United States); Levai, P. [MTA WIGNER Research Centre for Physics, RMI, Budapest (Hungary); Vitev, I. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Biró, T.S. [MTA WIGNER Research Centre for Physics, RMI, Budapest (Hungary)

    2014-11-15

    Recent p{sub T}<2 GeV azimuthal correlation data from the Beam Energy Scan (BES) and d+Au runs at RHIC/BNL and, especially, the surprising similarity of 2ℓ=2,4,⋯-particle cummulant azimuthal n=2,3,4,5 harmonics, v{sub n}{2ℓ}(p{sub T}), in p+Pb and Pb+Pb at LHC have challenged the uniqueness of local equilibrium “perfect fluid” interpretations of those data. We report results derived in [1] on azimuthal harmonics arising from non-equilibrium initial-state non-abelian “wave interference” effects predicted by perturbative QCD gluon bremsstrahlung and sourced by Color Scintillation Arrays (CSA) of color antennas. CSA are naturally identified with multiple projectile and target beam jets produced in inelastic p+A reactions. We find a remarkable similarity between azimuthal harmonics sourced by initial state CSA and those predicted with final state perfect fluid models of high energy p+A reactions. The question of which mechanism dominates in p+A and A+A remains open at this time.

  19. Technical Considerations of Phosphorous-32 Bremsstrahlung SPECT Imaging after Radioembolization of Hepatic Tumors: A Clinical Assessment with a Review of Imaging Parameters

    International Nuclear Information System (INIS)

    Background. Bremsstrahlung (BS) imaging during radioembolization (RE) confirms the deposition of radiotracer in hepatic/extrahepatic tumors. The aim of this study is to demonstrate 32P images and to optimize the imaging parameters. Materials and Methods. Thirty-nine patients with variable types of hepatic tumors, treated with the intra-arterial injection of 32P, were included. All patients underwent BS SPECT imaging 24–72 h after tracer administration, using low energy high resolution (LEHR) (18 patients) or medium energy general purpose (MEGP) (21 patients) collimators. A grading scale from 1 to 4 was used to express the compatibility of the 32P images with those obtained from CT/MRI. Results. Although the image quality obtained with the MEGP collimator was visually and quantitatively better than with the LEHR (76% concordance score versus 71%, resp.), there was no statistically significant difference between them. Conclusion. The MEGP collimator is the first choice for BS SPECT imaging. However, if the collimator change is time consuming (as in a busy center) or an MEGP collimator is not available, the LEHR collimator could be practical with acceptable images, especially in a SPECT study. In addition, BS imaging is a useful method to confirm the proper distribution of radiotherapeutic agents and has good correlation with anatomical findings

  20. Assay methods for U-238, Th-232, and Pb-210 in lead and calibration of Bi-210 bremsstrahlung emission from lead

    CERN Document Server

    Orrell, John L; Arnquist, Isaac J; Eggemeyer, Tere A; Glasgow, Brian D; Hoppe, Eric W; Keillor, Martin E; Morley, Shannon M; Myers, Allan W; Overman, Cory T; Shaff, Sarah M; Thommasson, Kimbrelle S

    2015-01-01

    Assay methods for measuring 238U, 232Th, and 210Pb concentrations in refined lead are presented. The 238U and 232Th concentrations are determined using isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) after anion exchange column separation of dissolved lead samples. The 210Pb concentration is inferred through {\\alpha}-spectroscopy of a daughter isotope, 210Po, after chemical precipitation separation on dissolved lead samples. Subsequent to the 210Po {\\alpha}-spectroscopy assay, a method for evaluating 210Pb concentrations in solid lead samples was developed via measurement of bremsstrahlung radiation from \\b{eta}-decay of a daughter isotope, 210Bi, by employing a 14-crystal array of high purity germanium (HPGe) detectors. Ten sources of refined lead were assayed. The 238U concentrations were <34 microBq/kg and the 232Th concentrations ranged <0.6-15 microBq/kg, as determined by the ICP-MS assay method. The 210Pb concentrations ranged from ~0.1-75 Bq/kg, as inferred by the 210Po ...

  1. Vertical profile of the environmental gamma-ray in Kashiwazaki Kariwa area. Detection of bremsstrahlung X-ray generated by winter thunderstorms

    International Nuclear Information System (INIS)

    Cumulative dose measurements have been performed at the points from 1 m to 117 m above the ground on the arrester tower located at the site of the Kashiwazaki Kariwa nuclear power station using radiophotoluminescence glass dosimeter (RPLD) and thermoluminescence dosimeter (TLD). From the measurement results, the mean dose rates both from RPLD and TLD gradually decrease with height in summer season. On the other hand, the vertical profile of upper regions showed in the reverse attenuation in winter season. It was assumed that the increasing trend of dose rates with height is caused by some external radiation source peculiar to winter season. In this winter, many thunderstorms occurred and dose rates from both NaI(Tl) and ionization chamber (IC) detectors increased occasionally at monitoring stations. According to the Monte Carlo calculation of the behaviour of electrons and photons in the model thundercloud, it was suggested that bremsstrahlung X-rays generated at high altitude has been attributed to the radiation source. (author)

  2. Initial-state bremsstrahlung versus final-state hydrodynamic sources of azimuthal harmonics in p+A at RHIC and LHC

    International Nuclear Information System (INIS)

    Recent pT<2 GeV azimuthal correlation data from the Beam Energy Scan (BES) and d+Au runs at RHIC/BNL and, especially, the surprising similarity of 2ℓ=2,4,⋯-particle cummulant azimuthal n=2,3,4,5 harmonics, vn{2ℓ}(pT), in p+Pb and Pb+Pb at LHC have challenged the uniqueness of local equilibrium “perfect fluid” interpretations of those data. We report results derived in [1] on azimuthal harmonics arising from non-equilibrium initial-state non-abelian “wave interference” effects predicted by perturbative QCD gluon bremsstrahlung and sourced by Color Scintillation Arrays (CSA) of color antennas. CSA are naturally identified with multiple projectile and target beam jets produced in inelastic p+A reactions. We find a remarkable similarity between azimuthal harmonics sourced by initial state CSA and those predicted with final state perfect fluid models of high energy p+A reactions. The question of which mechanism dominates in p+A and A+A remains open at this time

  3. Coherent Bremsstrahlung effect observed during STEM analysis of dopant distribution in silicon devices using large area silicon drift EDX detectors and high brightness electron source.

    Science.gov (United States)

    Pantel, R

    2011-11-01

    In this paper, during dopant analysis of silicon devices, we have observed a phenomenon generally neglected in EDX analysis: the coherent Bremsstrahlung (CB). We discussed the reason why and came to the conclusion that the analytical TEM used for these experiments presents a configuration and performances, which makes this equipment very sensitive to the CB effect. This is due to large collection solid angle and high counting rate of the four silicon drift EDX detectors (SDD), a high brightness electron source providing large probe current and moreover a geometry favorable to on axis crystal observations. We analyzed silicon devices containing Si [110] and Si [100] crystal areas at different energies (80-120-200keV). We also observed relaxed SiGe (27 and 40at% of Ge). The CB effect, whose intensity is maximum near zone axis beam alignment, manifests as characteristic broad peaks present in the X-ray spectrum background. The peak energies are predicted by a simple formula deduced for the CB models found in the literature and that we present simply. We evaluate also the CB peak intensities and discuss the importance of this effect on the detection and quantification traces of impurities. The CB peaks also give information on the analyzed crystal structure (measurement of the periodicity along the zone axis) and allow, in every particular experiment or system, to determine the median take off angle of the EDX detectors. PMID:21946001

  4. Electronic temperature measurement on the deca II plasma using the Bremsstrahlung; Mesure de la temperature electronique du plasma de deca II par etude du rayonnement de freinage

    Energy Technology Data Exchange (ETDEWEB)

    Dumas, A. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-06-01

    The electronic temperature of the DECA II machine's plasma is determined by studying the Bremsstrahlung. Two types of detectors are used for this measurement, a set scintillator-photo-multiplicator and a photoelectric effect detector with a massive silver target. The method used is the classical 'absorbent method', The absorbents used are thin formvar foils whose thickness is between 600 and 12 500 angstrom. The measurements done in two different working conditions of the DECA II machine have given: Te {approx_equal} 200 eV in the first case and Te {approx_equal} 70 eV in the second case. (author) [French] Nous avons determine la temperature electronique du plasma de la machine DECA II par l'etude du rayonnement de freinage. Pour cette mesure nous avons utilise deux types de detecteurs: des ensembles scintillateur-photomultiplicateur et un detecteur a effet photoelectrique a cible massive en argent. La methode utilisee pour cette mesure est la classique methode des absorbants. Nous avons utilise des feuilles de format tres mince (de 600 a 12 500 angstrom) comme absorbant. Les mesures faites dans deux regimes de travail differents de la machine DECA II nous ont conduit a: Te {approx_equal} 200 eV dans un cas et Te {approx_equal} eV dans l'autre cas. (auteur)

  5. Dynamics of radiation losses in Z-pinch plasma with taking into account generation of turbulent magnetic fields

    International Nuclear Information System (INIS)

    We estimated the total radiation losses from argon Z-pinches. Radiation losses due to excitation, di-electronic recombination, Bremsstrahlung, radiative recombination and also ionization, were considered. Each separate ion is analyzed in detail and the influence of density is taken into account. Our pinch dynamics includes Joule heating, anomalous plasma resistance, plasma outflow in Z-direction, electron beam generation, magnetic field pressure, radiation losses. Main novelty of the given model is generation of chaotic/turbulent magnetic fields. It is shown, that turbulent magnetic fields affect the dynamics of plasma parameters. The influence of turbulent magnetic field is analyzed on the dynamics of plasma temperature, density, radiation losses, line emission. (author)

  6. Magnetic Levitation.

    Science.gov (United States)

    Rossing, Thomas D.; Hull, John R.

    1991-01-01

    Discusses the principles of magnetic levitation presented in the physics classroom and applied to transportation systems. Topics discussed include three classroom demonstrations to illustrate magnetic levitation, the concept of eddy currents, lift and drag forces on a moving magnet, magnetic levitation vehicles, levitation with permanent magnets…

  7. Magnetic Nanocapsules

    Institute of Scientific and Technical Information of China (English)

    Zhidong ZHANG

    2007-01-01

    A brief review on recent advances in the area of the magnetic nanocapsules is given. The most applicable nanoencapsulation procedures are introduced, which include: (1) physical techniques such as arc-discharge,evaporating, etc.; (2) chemical techniques such as chemical vapor deposition, solid-state reactions, etc. The structure and magnetic properties of various nanocapsules with different core/shell structures are studied in details, for possibly applications in magnetic recording, magnetic refrigerator, magnetic fluids, superconductors and medicine.

  8. Coherent Bremsstrahlung effect observed during STEM analysis of dopant distribution in silicon devices using large area silicon drift EDX detectors and high brightness electron source

    International Nuclear Information System (INIS)

    In this paper, during dopant analysis of silicon devices, we have observed a phenomenon generally neglected in EDX analysis: the coherent Bremsstrahlung (CB). We discussed the reason why and came to the conclusion that the analytical TEM used for these experiments presents a configuration and performances, which makes this equipment very sensitive to the CB effect. This is due to large collection solid angle and high counting rate of the four silicon drift EDX detectors (SDD), a high brightness electron source providing large probe current and moreover a geometry favorable to on axis crystal observations. We analyzed silicon devices containing Si [110] and Si [100] crystal areas at different energies (80–120–200 keV). We also observed relaxed SiGe (27 and 40 at% of Ge). The CB effect, whose intensity is maximum near zone axis beam alignment, manifests as characteristic broad peaks present in the X-ray spectrum background. The peak energies are predicted by a simple formula deduced for the CB models found in the literature and that we present simply. We evaluate also the CB peak intensities and discuss the importance of this effect on the detection and quantification traces of impurities. The CB peaks also give information on the analyzed crystal structure (measurement of the periodicity along the zone axis) and allow, in every particular experiment or system, to determine the median take off angle of the EDX detectors. -- Highlights: ► STEM EDX dopant distribution analysis (As and P) in Si devices is carried out. ► High brightness electron source and four EDX Silicon Drift detectors are used. ► The obtained signal dynamics (four decades) allows detection down to 0.01 at%. ► During silicon axis analysis coherent Bremmsstrahlung is observed. ► This effect is studied at different energies and Si crystal orientations.

  9. Dynamical structure of magnetized dissipative accretion flow around black holes

    Science.gov (United States)

    Sarkar, Biplob; Das, Santabrata

    2016-09-01

    We study the global structure of optically thin, advection dominated, magnetized accretion flow around black holes. We consider the magnetic field to be turbulent in nature and dominated by the toroidal component. With this, we obtain the complete set of accretion solutions for dissipative flows where bremsstrahlung process is regarded as the dominant cooling mechanism. We show that rotating magnetized accretion flow experiences virtual barrier around black hole due to centrifugal repulsion that can trigger the discontinuous transition of the flow variables in the form of shock waves. We examine the properties of the shock waves and find that the dynamics of the post-shock corona (PSC) is controlled by the flow parameters, namely viscosity, cooling rate and strength of the magnetic field, respectively. We separate the effective region of the parameter space for standing shock and observe that shock can form for wide range of flow parameters. We obtain the critical viscosity parameter that allows global accretion solutions including shocks. We estimate the energy dissipation at the PSC from where a part of the accreting matter can deflect as outflows and jets. We compare the maximum energy that could be extracted from the PSC and the observed radio luminosity values for several supermassive black hole sources and the observational implications of our present analysis are discussed.

  10. Dynamical structure of magnetized dissipative accretion flow around black holes

    Science.gov (United States)

    Sarkar, Biplob; Das, Santabrata

    2016-06-01

    We study the global structure of optically thin, advection dominated, magnetized accretion flow around black holes. We consider the magnetic field to be turbulent in nature and dominated by the toroidal component. With this, we obtain the complete set of accretion solutions for dissipative flows where bremsstrahlung process is regarded as the dominant cooling mechanism. We show that rotating magnetized accretion flow experiences virtual barrier around black hole due to centrifugal repulsion that can trigger the discontinuous transition of the flow variables in the form of shock waves. We examine the properties of the shock waves and find that the dynamics of the post-shock corona (PSC) is controlled by the flow parameters, namely viscosity, cooling rate and strength of the magnetic field, respectively. We separate the effective region of the parameter space for standing shock and observe that shock can form for wide range of flow parameters. We obtain the critical viscosity parameter that allows global accretion solutions including shocks. We estimate the energy dissipation at the PSC from where a part of the accreting matter can deflect as outflows and jets. We compare the maximum energy that could be extracted from the PSC and the observed radio luminosity values for several super-massive black hole sources and the observational implications of our present analysis are discussed.

  11. Neutrino emission in neutron matter from magnetic moment interactions

    International Nuclear Information System (INIS)

    Neutrino emission drives neutron star cooling for the first several hundreds of years after its birth. Given the low-energy (∼keV) nature of this process, one expects very few nonstandard particle-physics contributions which could affect this rate. Requiring that any new physics contributions involve light degrees of freedom, one of the likely candidates which can affect the cooling process would be a nonzero magnetic moment for the neutrino. To illustrate, we compute the emission rate for neutrino pair bremsstrahlung in neutron-neutron scattering through photon-neutrino magnetic moment coupling. We also present analogous differential rates for neutrino scattering off nucleons and electrons that determine neutrino opacities in supernovae. Employing current upper bounds from collider experiments on the τ magnetic moment, we find that the neutrino emission rate can exceed the rate through neutral current electroweak interaction by a factor 2, signaling the importance of new particle physics input to a standard calculation of relevance to neutron star cooling. However, astrophysical bounds on the neutrino magnetic moment imply smaller effects

  12. Development of an efficient scanning and purging magnet system for IMRT with narrow high energy photon beams

    Science.gov (United States)

    Andreassen, Björn; Svensson, Roger; Holmberg, Rickard; Danared, Håkan; Brahme, Anders

    2009-12-01

    Due to the clinical advantages of Intensity Modulated Radiation Therapy (IMRT) high flexibility and accuracy in intensity modulated dose delivery is desirable to really maximize treatment outcome. Although it is possible to deliver IMRT by using broad beams in combination with dynamic multileaf collimation the process is rather time consuming and inefficient. By using narrow scanned high energy photon beams the treatment outcome can be improved, the treatment time reduced and accurate 3D in vivo dose delivery monitoring is possible by PET-CT based dose delivery imaging of photo nuclear reactions in human tissues. Narrow photon beams can be produced by directing a low emittance high energy electron beam on a thin target, and then cleaning the therapeutic photon beam from transmitted high energy electrons, and photon generated charged leptons, with a dedicated purging magnet placed directly downstream of the target. To have an effective scanning and purging magnet system the purging magnet should be placed immediately after the bremsstrahlung target to deflect the transmitted electrons to an efficient electron stopper. In the static electron stopper the electrons should be safely collected independent of the desired direction of the therapeutic scanned photon beam. The SID (Source to Isocenter Distance) should preferably be short while retaining the ability to scan over a large area on the patient and consequently there are severe requirements both on the strength and the geometry of the scanning and purging magnets. In the present study an efficient magnet configuration with a purging and scanning magnet assembly is developed for electron energies in the 50-75 MeV range and a SID of 75 cm. For a bremsstrahlung target of 3 mm Be these electron energies produce a photon beam of 25-17 mm FWHM (Full Width Half Maximum) at a SID of 75 cm. The magnet system was examined both in terms of the efficiency in scanning the narrow bremsstrahlung beam and the deflection of

  13. Development of an efficient scanning and purging magnet system for IMRT with narrow high energy photon beams

    International Nuclear Information System (INIS)

    Due to the clinical advantages of Intensity Modulated Radiation Therapy (IMRT) high flexibility and accuracy in intensity modulated dose delivery is desirable to really maximize treatment outcome. Although it is possible to deliver IMRT by using broad beams in combination with dynamic multileaf collimation the process is rather time consuming and inefficient. By using narrow scanned high energy photon beams the treatment outcome can be improved, the treatment time reduced and accurate 3D in vivo dose delivery monitoring is possible by PET-CT based dose delivery imaging of photo nuclear reactions in human tissues. Narrow photon beams can be produced by directing a low emittance high energy electron beam on a thin target, and then cleaning the therapeutic photon beam from transmitted high energy electrons, and photon generated charged leptons, with a dedicated purging magnet placed directly downstream of the target. To have an effective scanning and purging magnet system the purging magnet should be placed immediately after the bremsstrahlung target to deflect the transmitted electrons to an efficient electron stopper. In the static electron stopper the electrons should be safely collected independent of the desired direction of the therapeutic scanned photon beam. The SID (Source to Isocenter Distance) should preferably be short while retaining the ability to scan over a large area on the patient and consequently there are severe requirements both on the strength and the geometry of the scanning and purging magnets. In the present study an efficient magnet configuration with a purging and scanning magnet assembly is developed for electron energies in the 50-75 MeV range and a SID of 75 cm. For a bremsstrahlung target of 3 mm Be these electron energies produce a photon beam of 25-17 mm FWHM (Full Width Half Maximum) at a SID of 75 cm. The magnet system was examined both in terms of the efficiency in scanning the narrow bremsstrahlung beam and the deflection of

  14. Quasi-periodic oscillations in accreting magnetic white dwarfs II. The asset of numerical modelling for interpreting observations

    CERN Document Server

    Busschaert, C; Michaut, C; Bonnet-Bidaud, J -M; Mouchet, M

    2015-01-01

    Magnetic cataclysmic variables are close binary systems containing a strongly magnetized white dwarf that accretes matter coming from an M-dwarf companion. High-energy radiation coming from those objects is emitted from the accretion column close to the white dwarf photosphere at the impact region. Its properties depend on the characteristics of the white dwarf and an accurate accretion column model allows the properties of the binary system to be inferred, such as the white dwarf mass, its magnetic field, and the accretion rate. We study the temporal and spectral behaviour of the accretion region and use the tools we developed to accurately connect the simulation results to the X-ray and optical astronomical observations. The radiation hydrodynamics code Hades was adapted to simulate this specific accretion phenomena. Classical approaches were used to model the radiative losses of the two main radiative processes: bremsstrahlung and cyclotron. The oscillation frequencies and amplitudes in the X-ray and optic...

  15. Superconducting magnets

    International Nuclear Information System (INIS)

    This report discusses the following topics on superconducting magnets: D19B and -C: The next steps for a record-setting magnet; D20: The push beyond 10 T: Beyond D20: Speculations on the 16-T regime; other advanced magnets for accelerators; spinoff applications; APC materials development; cable and cabling-machine development; and high-Tc superconductor at low temperature

  16. Magnetizing of permanent magnets using HTS bulk magnets

    Science.gov (United States)

    Oka, Tetsuo; Muraya, Tomoki; Kawasaki, Nobutaka; Fukui, Satoshi; Ogawa, Jun; Sato, Takao; Terasawa, Toshihisa

    2012-01-01

    A demagnetized Nd-Fe-B permanent magnet was scanned just above the magnetic pole which contains the HTS bulk magnet generating a magnetic field of 3.27 T. The magnet sample was subsequently found to be fully magnetized in the open space of the static magnetic fields. We examined the magnetic field distributions when the magnetic poles were scanned twice to activate the magnet plate inversely with various overlap distances between the tracks of the bulk magnet. The magnetic field of the "rewritten" magnet reached the values of the magnetically saturated region of the material, showing steep gradients at the border of each magnetic pole. As a replacement for conventional pulse field magnetizing methods, this technique is proposed to expand the degree of freedom in the design of electromagnetic devices, and is proposed as a novel practical method for magnetizing rare-earth magnets, which have excellent magnetic performance and require intense fields of more than 3 T to be activated.

  17. Exact Bremsstrahlung and effective couplings

    Energy Technology Data Exchange (ETDEWEB)

    Mitev, Vladimir [Mainz Univ. (Germany). Inst. fuer Physik, WA THEP; Humboldt-Univ. Berlin (Germany). Inst. fuer Mathematik und Inst. fuer Physik; Pomoni, Elli [DESY Hamburg (Germany). Theory Group; National Technical Univ., Athens (Greece). Physics Div.

    2015-11-15

    We calculate supersymmetric Wilson loops on the ellipsoid for a large class of N=2 SCFT using the localization formula of Hama and Hosomichi. From them we extract the radiation emitted by an accelerating heavy probe quark as well as the entanglement entropy following the recent works of Lewkowycz-Maldacena and Fiol-Gerchkovitz-Komargodski. Comparing our results with the N=4 SYM ones, we obtain interpolating functions f(g{sup 2}) such that a given N=2 SCFT observable is obtained by replacing in the corresponding N=4 SYM result the coupling constant by f(g{sup 2}). These ''exact effective couplings'' encode the finite, relative renormalization between the N = 2 and the N = 4 gluon propagator, they interpolate between the weak and the strong coupling. We discuss the range of their applicability.

  18. Exact Bremsstrahlung and effective couplings

    Science.gov (United States)

    Mitev, Vladimir; Pomoni, Elli

    2016-06-01

    We calculate supersymmetric Wilson loops on the ellipsoid for a large class of mathcal{N} = 2 SCFT using the localization formula of Hama and Hosomichi. From them we extract the radiation emitted by an accelerating heavy probe quark as well as the entanglement entropy following the recent works of Lewkowycz-Maldacena and Fiol-Gerchkovitz-Komargodski. Comparing our results with the mathcal{N} = 4 SYM ones, we obtain interpolating functions f ( g 2) such that a given mathcal{N} = 2 SCFT observable is obtained by replacing in the corresponding mathcal{N} = 4 SYM result the coupling constant by f ( g 2). These "exact effective couplings" encode the finite, relative renormalization between the mathcal{N} = 2 and the mathcal{N} = 4 gluon propagator and they interpolate between the weak and the strong coupling. We discuss the range of their applicability.

  19. Exact Bremsstrahlung and Effective Couplings

    CERN Document Server

    Mitev, Vladimir

    2015-01-01

    We calculate supersymmetric Wilson loops on the ellipsoid for a large class of $\\mathcal{N}=2$ SCFT using the localization formula of Hama and Hosomichi. From them we extract the radiation emitted by an accelerating heavy probe quark as well as the entanglement entropy following the recent works of Lewkowycz-Maldacena and Fiol-Gerchkovitz-Komargodski. Comparing our results with the $\\mathcal{N}=4$ SYM ones, we obtain interpolating functions $f(g^2)$ such that a given $\\mathcal{N}=2$ SCFT observable is obtained by replacing in the corresponding $\\mathcal{N}=4$ SYM result the coupling constant by $f(g^2)$. These ``exact effective couplings'' encode the finite, relative renormalization between the $\\mathcal{N}=2$ and the $\\mathcal{N}=4$ gluon propagator, they interpolate between the weak and the strong coupling. We discuss the range of their applicability.

  20. Exact Bremsstrahlung and effective couplings

    International Nuclear Information System (INIS)

    We calculate supersymmetric Wilson loops on the ellipsoid for a large class of N=2 SCFT using the localization formula of Hama and Hosomichi. From them we extract the radiation emitted by an accelerating heavy probe quark as well as the entanglement entropy following the recent works of Lewkowycz-Maldacena and Fiol-Gerchkovitz-Komargodski. Comparing our results with the N=4 SYM ones, we obtain interpolating functions f(g2) such that a given N=2 SCFT observable is obtained by replacing in the corresponding N=4 SYM result the coupling constant by f(g2). These ''exact effective couplings'' encode the finite, relative renormalization between the N = 2 and the N = 4 gluon propagator, they interpolate between the weak and the strong coupling. We discuss the range of their applicability.

  1. Measurement of isomeric yield ratios in the photo-production of 133m,g;137m,gCe from natCe using 55-, 60-, and 65-MeV bremsstrahlung

    International Nuclear Information System (INIS)

    The isomeric yield ratios of 133m,gCe and 137m,gCe produced from the natCe(γ,xn) reactions were determined by using the activation and the off-line γ-ray spectrometric technique with the end-point bremsstrahlung energies of 55-, 60-, and 65-MeV at 100-MeV electron linac of the Pohang accelerator laboratory. The induced activities in the irradiated foils were measured by using an energy- and efficiency-calibrated HPGe detector coupled to a PC based multi-channel analyzer. The necessary corrections were made to improve the accuracy of the experimental results. The experimental results at bremsstrahlung energies of 55-, 60-, and 65-MeV were 0.324 ± 0.089, 0.331 ± 0.086, and 0.403 ± 0.089 for the 133m,gCe, and 0.210 ± 0.062, 0.221 ± 0.061, and 0.262 ± 0.061 for the 137m,gCe, respectively. The present results for natCe(γ,xn)133m,g;137m,gCe in this energy region were obtained for the first time which has no comparable literature data. The obtained isomeric yield ratios are compared with the calculated values based on the statistical model code TALYS 1.6

  2. Quantum Magnetism

    CERN Document Server

    Barbara, Bernard; Sawatzky, G; Stamp, P. C. E

    2008-01-01

    This book is based on some of the lectures during the Pacific Institute of Theoretical Physics (PITP) summer school on "Quantum Magnetism", held during June 2006 in Les Houches, in the French Alps. The school was funded jointly by NATO, the CNRS, and PITP, and entirely organized by PITP. Magnetism is a somewhat peculiar research field. It clearly has a quantum-mechanical basis – the microsopic exchange interactions arise entirely from the exclusion principle, in conjunction with respulsive interactions between electrons. And yet until recently the vast majority of magnetism researchers and users of magnetic phenomena around the world paid no attention to these quantum-mechanical roots. Thus, eg., the huge ($400 billion per annum) industry which manufactures hard discs, and other components in the information technology sector, depends entirely on room-temperature properties of magnets - yet at the macroscopic or mesoscopic scales of interest to this industry, room-temperature magnets behave entirely classic...

  3. Planetary Magnetism

    Science.gov (United States)

    Connerney, J. E. P.

    2007-01-01

    The chapter on Planetary Magnetism by Connerney describes the magnetic fields of the planets, from Mercury to Neptune, including the large satellites (Moon, Ganymede) that have or once had active dynamos. The chapter describes the spacecraft missions and observations that, along with select remote observations, form the basis of our knowledge of planetary magnetic fields. Connerney describes the methods of analysis used to characterize planetary magnetic fields, and the models used to represent the main field (due to dynamo action in the planet's interior) and/or remnant magnetic fields locked in the planet's crust, where appropriate. These observations provide valuable insights into dynamo generation of magnetic fields, the structure and composition of planetary interiors, and the evolution of planets.

  4. Magnetic switching

    International Nuclear Information System (INIS)

    Magnetic switching is a pulse compression technique that uses a saturable inductor (reactor) to pass pulses of energy between two capacitors. A high degree of pulse compression can be achieved in a network when several of these simple, magnetically switched circuits are connected in series. Individual inductors are designed to saturate in cascade as a pulse moves along the network. The technique is particularly useful when a single-pulse network must be very reliable or when a multi-pulse network must operate at a high pulse repetition frequency (PRF). Today, magnetic switches trigger spark gaps, sharpen the risetimes of high energy pulses, power large lasers, and drive high PRF linear induction accelerators. This paper will describe the technique of magnetic pulse compression using simple networks and design equations. A brief review of modern magnetic materials and of their role in magnetic switch design will be presented. 12 refs., 8 figs., 1 tab

  5. Magnetic transducer

    International Nuclear Information System (INIS)

    A description is given of a transducer system for identifying the presence and location of ferromagnetic materials and ferromagnetic discontinuities associated with a sample. This equipment includes a first source of a magnetic field in magnetic connection with the surface of the sample and so mounted that it may be moved along this surface and a Hall effect cell in magnetic connection with the first source, in a fixed position in relation to this first source and placed so as to be in magnetic connection with the sample. The object of this invention is a transducer able to detect the accumulation of corrosion products (scale) on the outer surfaces of steam generator tubes

  6. Magnet Systems

    Data.gov (United States)

    Federal Laboratory Consortium — Over the decades, Fermilab has been responsible for the design, construction, test and analysis of hundreds of conventional and superconducting accelerator magnets...

  7. MO-G-17A-06: Kernel Based Dosimetry for 90Y Microsphere Liver Therapy Using 90Y Bremsstrahlung SPECT/CT

    Energy Technology Data Exchange (ETDEWEB)

    Mikell, J; Siman, W; Kappadath, S [The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX (United States); University of Texas MD Anderson Cancer Center, Houston, TX (United States); Mahvash, A [University of Texas MD Anderson Cancer Center, Houston, TX (United States); Mourtada, F [Christiana Care Hospital, Newark, DE (United States)

    2014-06-15

    Purpose: 90Y microsphere therapy in liver presents a situation where beta transport is dominant and the tissue is relatively homogenous. We compare voxel-based absorbed doses from a 90Y kernel to Monte Carlo (MC) using quantitative 90Y bremsstrahlung SPECT/CT as source distribution. Methods: Liver, normal liver, and tumors were delineated by an interventional radiologist using contrast-enhanced CT registered with 90Y SPECT/CT scans for 14 therapies. Right lung was segmented via region growing. The kernel was generated with 1.04 g/cc soft tissue for 4.8 mm voxel matching the SPECT. MC simulation materials included air, lung, soft tissue, and bone with varying densities. We report percent difference between kernel and MC (%Δ(K,MC)) for mean absorbed dose, D70, and V20Gy in total liver, normal liver, tumors, and right lung. We also report %Δ(K,MC) for heterogeneity metrics: coefficient of variation (COV) and D10/D90. The impact of spatial resolution (0, 10, 20 mm FWHM) and lung shunt fraction (LSF) (1,5,10,20%) on the accuracy of MC and kernel doses near the liver-lung interface was modeled in 1D. We report the distance from the interface where errors become <10% of unblurred MC as d10(side of interface, dose calculation, FWHM blurring, LSF). Results: The %Δ(K,MC) for mean, D70, and V20Gy in tumor and liver was <7% while right lung differences varied from 60–90%. The %Δ(K,MC) for COV was <4.8% for tumor and liver and <54% for the right lung. The %Δ(K,MC) for D10/D90 was <5% for 22/23 tumors. d10(liver,MC,10,1–20) awere <9mm and d10(liver,MC,20,1–20) awere <15mm; both agreed within 3mm to the kernel. d10(lung,MC,10,20), d10(lung,MC,10,1), d10(lung,MC,20,20), and d10(lung,MC,20,1) awere 6, 25, 15, and 34mm, respectively. Kernel calculations on blurred distributions in lung had errors > 10%. Conclusions: Liver and tumor voxel doses with 90Y kernel and MC agree within 7%. Large differences exist between the two methods in right lung. Research reported in this

  8. Secondary neutron production from patients during therapy with Bremsstrahlung and hadrons: are there potential risks with hadrons; especially C-ions?

    International Nuclear Information System (INIS)

    Full text: We were the first group in the world who accurately and unambiguously calculated and measured the secondary neutron produced from patients undergoing therapy with Bremsstrahlung from 2-28 MeV end-point energies, and also estimated the corresponding radiation doses. Keeping in mind that the cross sections of neutron production from tissue are much higher under irradiation with heavier particles, such as protons, alpha particles, carbon and neon ions, etc. than photon bombardment, it would be expected that a lot more neutrons would be produced from tissue during radiotherapy with hadrons (protons, alphas, carbon ions, Ne-ions, etc.).There is no reliable and useful data available on this subject in the literature. By making use of the experimental neutron out put studies from different elements, we have been able to estimate the fluence and energy distribution of these secondary neutrons from tissue under irradiation with different hadrons. Our results indicate that at least 4.2 neutrons , with energies greater than 5 MeV, are produced for every carbon ion of 400 MeV / u energy incident on tissue. This number reduces to 3, 1.4 and 0.3 respectively at carbon energies of 300, 200 and 100 MeV /u. The energy range of carbon ions considered here, 100 MeV/u to 400 MeV/u, corresponds to that being actually used in therapy. In the case of neon ions these figures (number of secondary neutrons / incident neon ion) are slightly higher. For irradiation with alpha particles the number of these secondary neutrons reduces to about 1 per alpha particle with incident energy of 200 MeV / nucleon. There would no doubt be even more neutrons with energies lesser than 5 MeV which so far could not be estimated due to the lack of experimental data. In the case of proton therapy the numbers of secondary neutrons of all energies (including those with energies of lesser than 5 MeV) from tissue are estimated to be 0.05, 0.2 and 0.4 per proton of energies 100, 200 and 300 Me

  9. Magnetic nanotubes

    Science.gov (United States)

    Matsui, Hiroshi; Matsunaga, Tadashi

    2010-11-16

    A magnetic nanotube includes bacterial magnetic nanocrystals contacted onto a nanotube which absorbs the nanocrystals. The nanocrystals are contacted on at least one surface of the nanotube. A method of fabricating a magnetic nanotube includes synthesizing the bacterial magnetic nanocrystals, which have an outer layer of proteins. A nanotube provided is capable of absorbing the nanocrystals and contacting the nanotube with the nanocrystals. The nanotube is preferably a peptide bolaamphiphile. A nanotube solution and a nanocrystal solution including a buffer and a concentration of nanocrystals are mixed. The concentration of nanocrystals is optimized, resulting in a nanocrystal to nanotube ratio for which bacterial magnetic nanocrystals are immobilized on at least one surface of the nanotubes. The ratio controls whether the nanocrystals bind only to the interior or to the exterior surfaces of the nanotubes. Uses include cell manipulation and separation, biological assay, enzyme recovery, and biosensors.

  10. Magnetic Field

    DEFF Research Database (Denmark)

    Olsen, Nils

    2015-01-01

    of the fluid flow at the top of the core. However, what is measured at or near the surface of the Earth is the superposition of the core field and fields caused by magnetized rocks in the Earth’s crust, by electric currents flowing in the ionosphere, magnetosphere, and oceans, and by currents induced......he Earth has a large and complicated magnetic field, the major part of which is produced by a self-sustaining dynamo operating in the fluid outer core. Magnetic field observations provide one of the few tools for remote sensing the Earth’s deep interior, especially regarding the dynamics...... in the Earth by time-varying external fields. These sources have their specific characteristics in terms of spatial and temporal variations, and their proper separation, based on magnetic measurements, is a major challenge. Such a separation is a prerequisite for remote sensing by means of magnetic field...

  11. Lunar magnetism

    Science.gov (United States)

    Hood, L. L.; Sonett, C. P.; Srnka, L. J.

    1984-01-01

    Aspects of lunar paleomagnetic and electromagnetic sounding results which appear inconsistent with the hypothesis that an ancient core dynamo was the dominant source of the observed crustal magnetism are discussed. Evidence is summarized involving a correlation between observed magnetic anomalies and ejecta blankets from impact events which indicates the possible importance of local mechanisms involving meteoroid impact processes in generating strong magnetic fields at the lunar surface. A reply is given to the latter argument which also presents recent evidence of a lunar iron core.

  12. Compression and Cavitation of Externally Applied Magnetic Field on a Hohlraum due to Non-Local Heat Flow Effects

    Science.gov (United States)

    Joglekar, Archis; Thomas, Alec; Ridgers, Chris; Kingham, Rob

    2015-11-01

    In this study, we present full-scale 2D kinetic modeling of externally imposed magnetic fields on hohlraums with laser heating. We observe magnetic field cavitation and compression due to thermal energy transport. Self-consistent modeling of the electron momentum equation allows for a complete treatment of the heat flow equation and Ohm's Law. A complete Ohm's Law contains magnetic field advection through the Nernst mechanism that arises due to the heat flow. Magnetic field amplification by a factor of 3 occurs due to magnetic flux pile-up from Nernst convection. The magnetic field cavitates towards the hohlraum axis over a 0.5 ns time scale due to Nernst convection. This results in significantly different magnetic field profiles and slower cavitation than can be expected due to the plasma bulk flow. Non-local electrons contribute to the heat flow down the density gradient resulting in an augmented Nernst convection mechanism that is included self-consistently through kinetic modeling. In addition to showing the prevalence of non-local heat flows, we show effects such as anomalous heat flow up the density gradient induced by inverse bremsstrahlung heating. This research was supported by the DOE through Grant No. DE SC0010621 and in part through computational resources and services provided by Advanced Research Computing at the University of Michigan, Ann Arbor.

  13. Electron Acceleration by Cascading Reconnection in the Solar Corona. I. Magnetic Gradient and Curvature Drift Effects

    Science.gov (United States)

    Zhou, X.; Büchner, J.; Bárta, M.; Gan, W.; Liu, S.

    2015-12-01

    We investigate the electron acceleration by magnetic gradient and curvature drift effects in cascading magnetic reconnection of a coronal current sheet via a test particle method in the framework of the guiding center approximation. After several Alfvén transit times, most of the electrons injected at the current sheet are still trapped in the magnetic islands. A small fraction of the injected electrons precipitate into the chromosphere. The acceleration of trapped electrons is dominated by the magnetic curvature drifts, which change the parallel momentum of the electron, and appears to be more efficient than the acceleration of precipitating electrons, which is dominated by the perpendicular momentum change caused by the magnetic gradient drifts. With the resulting trapped energetic electron distribution, the corresponding hard X-ray (HXR) radiation spectra are calculated using an optically thin Bremsstrahlung model. Trapped electrons may explain flare loop top HXR emission as well as the observed bright spots along current sheets trailing coronal mass ejections. The asymmetry of precipitating electrons with respect to the polarity inversion line may contribute to the observed asymmetry of footpoint emission.

  14. Magnetic guns with cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, David; Beleggia, Marco; Heller, Luděk

    2012-01-01

    The motion of a cylindrical permanent magnet (projectile) inside a tubular permanent magnet, with both magnets magnetized axially, illustrates nicely the physical principles behind the operation of magnetic guns. The force acting upon the projectile is expressed semi-analytically as derivative of...... the generated forces and motion of the inner cylindrical magnet....

  15. Superconducting magnets

    International Nuclear Information System (INIS)

    This report provides a self-consistent description of a magnetic field in the aperture of a superconducting magnet and details how this field can be calculated in a magnet with cos θ current distribution in the coils. A description of an apparatus that can be used to measure the field uniformity in the aperture has been given. Finally, a detailed description of the magnet being developed for use in the Superconducting Super Collider is given. When this machine is built, it will be by far the largest application of superconductivity to date and promises to make possible the experimental discoveries needed to understand the basic laws of nature governing the world in which we live

  16. Magnetic monopoles

    International Nuclear Information System (INIS)

    In this talk on magnetic monopoles, first the author briefly reviews some historical background; then, the author describes what several different types of monopoles might look like; and finally the author discusses the experimental situation. 81 references

  17. Magnetic monopoles

    Energy Technology Data Exchange (ETDEWEB)

    Fryberger, D.

    1984-12-01

    In this talk on magnetic monopoles, first the author briefly reviews some historical background; then, the author describes what several different types of monopoles might look like; and finally the author discusses the experimental situation. 81 references.

  18. Quantum magnetism

    CERN Document Server

    Richter, Johannes; Farnell, Damian; Bishop, Raymod

    2004-01-01

    The investigation of magnetic systems where quantum effects play a dominant role has become a very active branch of solid-state-physics research in its own right. The first three chapters of the "Quantum Magnetism" survey conceptual problems and provide insights into the classes of systems considered, namely one-dimensional, two-dimensional and molecular magnets. The following chapters introduce the methods used in the field of quantum magnetism, including spin wave analysis, exact diagonalization, quantum field theory, coupled cluster methods and the Bethe ansatz. The book closes with a chapter on quantum phase transitions and a contribution that puts the wealth of phenomena into the context of experimental solid-state physics. Closing a gap in the literature, this volume is intended both as an introductory text at postgraduate level and as a modern, comprehensive reference for researchers in the field.

  19. General Relativistic Magnetohydrodynamic Simulations of the Hard State as a Magnetically-Dominated Accretion Flow

    CERN Document Server

    Fragile, P Chris

    2008-01-01

    (Abridged) We present one of the first physically-motivated two-dimensional general relativistic magnetohydrodynamic (GRMHD) numerical simulations of a radiatively-cooled black-hole accretion disk. The fiducial simulation combines a total-energy-conserving formulation with a radiative cooling function, which includes bremsstrahlung, synchrotron, and Compton effects. By comparison with other simulations we show that in optically thin advection-dominated accretion flows, radiative cooling can significantly affect the structure, without necessarily leading to an optically thick, geometrically thin accretion disk. We further compare the results of our radiatively-cooled simulation to the predictions of a previously developed analytic model for such flows. For the very low stress parameter and accretion rate found in our simulated disk, we closely match a state called the "transition" solution between an outer advection-dominated accretion flow and what would be a magnetically-dominated accretion flow (MDAF) in th...

  20. Magnetic monopoles and dipoles

    CERN Multimedia

    Dominguez, Daniel

    2016-01-01

    Conventional bar magnets are also called ‘magnetic dipoles’ because they have two magnetic poles (a “North” and a “South” magnetic pole, like the Earth). In theory, “magnetic monopoles” could exist that act like an isolated “magnetic charge”, i.e. either a “North” or a “South” magnetic pole.

  1. Magnetism Materials and Applications

    CERN Document Server

    Trémolet de Lacheisserie, Étienne; Schlenker, Michel

    2005-01-01

    This book treats permanent magnet (hard) materials, magnetically soft materials for low-frequency applications and for high-frequency electronics, magnetostrictive materials, superconductors, magnetic-thin films and multilayers, and ferrofluids. Chapters are dedicated to magnetic recording, the role of magnetism in magnetic resonance imaging (MRI), and instrumentation for magnetic measurements.   

  2. Designing a magnet for magnetic refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Bjoerk, R.

    2010-03-15

    This thesis investigates the design and optimization of a permanent magnet assembly for use in a magnetic refrigeration device. The heart of magnetic refrigeration is the adiabatic temperature change in the magnetocaloric material which is caused by the magnetic field. In order to design an ideal magnet assembly the magnetocaloric materials and the refrigeration process itself and their properties and performance as a function of magnetic field are investigated. For the magnetocaloric materials it is the magnetization, specific heat capacity and adiabatic temperature that are investigated as functions of the magnetic field. Following this the process utilized by a magnetic refrigerator to provide cooling is investigated using a publicly available one dimensional numerical model. This process is called active magnetic regeneration (AMR). The aim is to determine the performance of the AMR as a function of the magnetic field in order to learn the properties of the optimal magnet assembly. The performance of the AMR as a function of the synchronization and width of the magnetic field with respect to the AMR cycle, the ramp rate and maximum value of the magnetic field are investigated. Other published magnet designs used in magnetic refrigeration devices are also evaluated, using a figure of merit based on the properties of the investigated magnetocaloric materials, to learn the properties of the best magnet designs to date. Following this investigation the Halbach cylinder, which is a hollow permanent magnet cylinder with a rotating remanent flux density, is investigated in detail as it forms the basis of many magnet designs used in magnetic refrigeration. Here the optimal dimensions of a Halbach cylinder, as well as analytical calculations of the magnetic field for a Halbach cylinder of infinite length, are presented. Once it has been determined which properties are desirable for a magnet used in magnetic refrigeration the design of a new magnet is described. This is

  3. Magnetic collectors

    International Nuclear Information System (INIS)

    A collector for use in a magnetic separator is formed by isostatically pressing a metal which is resistant to attack by acid about ferromagnetic bodies whereby to encase the bodies in the metal. In one arrangement, as shown, the bodies are encapsulated between inner and outer cylinders. In other arrangements the encapsulating metal is in the form of a tube or planar sheets. The bodies are of Fe or an oxide thereof and the acid-resistant metal parts may be of stainless steel, Au, Pt, Pa or an alloy. The magnetic separator is intended for use in removing particles from liquids during the reprocessing of nuclear fuel materials. (author)

  4. Random magnetism

    International Nuclear Information System (INIS)

    The 'ingredients' which control a phase transition in well defined systems as well as in random ones (e.q. random magnetic systems) are listed and discussed within a somehow unifying perspective. Among these 'ingredients' the couplings and elements responsible for the cooperative phenomenon, the topological connectivity as well as possible topological incompatibilities, the influence of new degrees of freedom, the order parameter dimensionality, the ground state degeneracy and finally the 'quanticity' of the system are found. The general trends, though illustrated in magnetic systems, essentially hold for all phase transitions, and give a basis for connection of this area with Field theory, Theory of dynamical systems, etc. (Author)

  5. USE OF SUPERCONDUCTING MAGNETS IN MAGNETIC SEPARATION

    OpenAIRE

    Parker, M.

    1984-01-01

    A review is given assessing the potential for superconducting high-field magnet systems in magnetic separation. Particular attention is given to the advantages of the reciprocating canister approach to high gradient magnetic separation and to the use of quadrupole magnets in open gradient magnetic separation.

  6. THERMAL EQUILIBRIA OF OPTICALLY THIN, MAGNETICALLY SUPPORTED, TWO-TEMPERATURE, BLACK HOLE ACCRETION DISKS

    International Nuclear Information System (INIS)

    We obtained thermal equilibrium solutions for optically thin, two-temperature black hole accretion disks incorporating magnetic fields. The main objective of this study is to explain the bright/hard state observed during the bright/slow transition of galactic black hole candidates. We assume that the energy transfer from ions to electrons occurs via Coulomb collisions. Bremsstrahlung, synchrotron, and inverse Compton scattering are considered as the radiative cooling processes. In order to complete the set of basic equations, we specify the magnetic flux advection rate instead of β = pgas/pmag. We find magnetically supported (low-β), thermally stable solutions. In these solutions, the total amount of the heating via the dissipation of turbulent magnetic fields goes into electrons and balances the radiative cooling. The low-β solutions extend to high mass accretion rates (∼>α2M-dotEdd) and the electron temperature is moderately cool (Te ∼ 108-109.5 K). High luminosities (∼>0.1LEdd) and moderately high energy cutoffs in the X-ray spectrum (∼50-200 keV) observed in the bright/hard state can be explained by the low-β solutions.

  7. Magnetic Catalysis vs Magnetic Inhibition

    CERN Document Server

    Fukushima, Kenji

    2012-01-01

    We discuss the fate of chiral symmetry in an extremely strong magnetic field B. We investigate not only quark fluctuations but also neutral meson effects. The former would enhance the chiral-symmetry breaking at finite B according to the Magnetic Catalysis, while the latter would suppress the chiral condensate once B exceeds the scale of the hadron structure. Using a chiral model we demonstrate how neutral mesons are subject to the dimensional reduction and the low dimensionality favors the chiral-symmetric phase. We point out that this effect, the Magnetic Inhibition, can be a feasible explanation for recent lattice-QCD data indicating the decreasing behavior of the chiral-restoration temperature with increasing B.

  8. ITER magnets

    International Nuclear Information System (INIS)

    As part of the summary of the Conceptual Design Activities (CDA) for the International Thermonuclear Experimental Reactor (ITER), this document describes the magnet systems for ITER, including the Toroidal Field (TF) and Poloidal Field (PF) Magnets, the Structural Support System and Cryostat, the Cryogenic System, the TF and PF Power and Protection Systems, and Coil Services and Diagnostics. After an Introduction and Summary, the document discusses the (i) Design Basis, including General Requirements, Design Criteria, Design Philosophy, and the Database (a.o., engineering data on key materials and components), and (ii) the Subsystem Design and Analysis, including Conductor Design, TF Coil and Structure Design, TF Structural Analysis, PF Coil and Structure Design, PF Structural Performance, Fatigue Assessment of Structures, AC Loss Performance, Thermohydraulic Performance, Stability, Cryogenic System, Power Supply Systems, and Coil Services. All magnets are superconducting, (based on Nb3Sn) except the Active Control Coils inside the Vacuum Vessel. The fault analysis has been taken to a level consistent with the design definition, showing that the present design meets the requirement for passive safety or can be made to meet it with only minor modifications. A more detailed assessment in this regard is needed but must await further development of the design. In conclusion, the magnet design concepts presently proposed can be developed into an engineering design. Refs, figs and tabs

  9. Magnetic reconnection

    International Nuclear Information System (INIS)

    A review is given of the theory of magnetic reconnection in the framework of resistive magnetohydrodynamics (MHD). While most of the material refers to two-dimensional systems, the final sections give a brief outlook of problems arising in fully three-dimensional configurations. (orig.)

  10. Magnetic monopoles

    CERN Document Server

    Giacomelli, G

    2000-01-01

    The main aim of this lecture is to give an update on the lectures on MagneticMonopoles (MMs) of the 1995 Trieste School. The update concerns theoreticaldevelopments, searches for GUT monopoles in the penetrating cosmic radiation atever lower fluxes, study of the energy losses of MMs in the Earth and indetectors,searches for low mass monopoles, and finally mention byproducts of MMsearches.

  11. Permanent magnet array for the magnetic refrigerator

    Science.gov (United States)

    Lee, S. J.; Kenkel, J. M.; Pecharsky, V. K.; Jiles, D. C.

    2002-05-01

    Recent research into the development of magnetic refrigeration (MR) operating at room temperature has shown that it can provide a reliable, energy-efficient cooling system. To enhance the cooling power of the magnetic refrigerator, it is required to use a magnetic refrigerant material with large magnetocaloric effect (MCE) at the appropriate temperature. Most advanced magnetic refrigerant materials show largest MCE at high applied magnetic fields generated by a superconducting magnet. For application of MCE to air conditioners or household refrigerators, it is essential to develop a permanent magnet array to form a compact, strong, and energy-efficient magnetic field generator. Generating a magnetic field well above the remanence of a permanent magnet material is hard to achieve through conventional designs. A permanent magnet array based on a hollow cylindrical flux source is found to provide an appropriate geometry and magnetic field strength for MR applications.

  12. Magnetic Fluids: Biomedical Applications and Magnetic Fractionation

    OpenAIRE

    Rheinländer, Thomas; Kötitz, Róman; Weitschies, Werner; Semmler, Wolfhard

    2000-01-01

    In addition to engineering applications, magnetic fluids containing magnetic nanoparticles are being increasingly applied to biomedical purposes. Besides the well established use of magnetic particles for biological separation or as contrast agents for magnetic resonance imaging, magnetic particles are also being tested for the inductive heat treatment of tumors or as markers for the quantification of biologically active substances. The properties of magnetic nanoparticles usually exhibit a b...

  13. Neutron Scattering studies of magnetic molecular magnets

    International Nuclear Information System (INIS)

    This work deals with inelastic neutron scattering studies of magnetic molecular magnets and focuses on their magnetic properties at low temperature and low energies. Several molecular magnets (Mn12, V15, Ni12, Mn4, etc.) are reviewed. Inelastic neutron scattering is shown to be a perfectly suited spectroscopy tool to -a) probe magnetic energy levels in such systems and -b) provide key information to understand the quantum tunnel effect of the magnetization in molecular spin clusters. (author)

  14. Studies of an extractor geometry magnetically insulated ion diode with an exploding metal film anode plasma

    International Nuclear Information System (INIS)

    Magnetically insulated diodes (MIDs) are of interest as ion sources for inertial confinement fusion. The authors examined several issues that are of concern with MIDs, including ion turn-on delay and anode plasma production, and diode impedance history and particle current scaling with the applied magnetic field and gas spacing. The LION pulsed power generator (1.5 MV, 4 Ω, 40 ns pulse length) was used to power an extractor geometry magnetically insulated (radical magnetic field) ion beam diode. The diode was studied with three anode configurations. In the first, with epoxy-filled-groove (epoxy) anodes, scaling of the ion and electron currents with the gap and the magnetic field was examined. He found that the observed ion current is consistent with a diode model that has been successful with barrel geometry MIDs. The electron leakage current scaled proportionally to 1/Bd2, where d is the anode-cathode gap spacing and B is the magnetic field strength. Studies of ion beam propagation in vacuum showed that space charge non-neutrality near the magnetic field coils caused the beam to expand initially. Later in the ion pulse (20 to 30 ns), the beam expansion became much less severe. The second anode configuration utilized an electron collector protruding above an epoxy anode surface. With the collector, he observed less bremsstrahlung across the active anode region. The last anode configuration studied was the exploding metal film active anode plasma source (EMFAAPS). Current from the accelerator was directed by an electron collector or a plasma opening switch through a thin aluminum film, which exploded to form the anode plasma

  15. magnetic horn

    CERN Multimedia

    Neutrinos and antineutrinos are ideal for probing the weak force because it is effectively the only force they feel. How were they made? Protons fired into a metal target produce a tangle of secondary particles. A magnetic horn like this one, invented by Simon Van der Meer, selected pions and focused them into a sharp beam. Pions decay into muons and neutrinos or antineutrinos. The muons were stopped in a wall of 3000 tons of iron and 1000 tons of concrete, leaving the neutrinos or antineutrinos to reach the Gargamelle bubble chamber. A simple change of magnetic field direction on the horn flipped between focusing positively- or negatively-charged pion beams, and so between neutrinos and antineutrinos.

  16. Planetary magnetism

    International Nuclear Information System (INIS)

    Experimental data on magnetic fields of planets are surveyed. The magnetic fields of the Earth, Jupiter, Mars, Mercury, Venus, and the Moon are considered in detail. A similarity of the physical models of both the planets of the Earth group and the giant planets was revealed. The fields of the planets and of the Earth are compared in the scheme of the precession dynamo and in the kinematic scheme. Proceeding from the assumption that the Poincare forces and their ratio to other forces are model-similar in the cores of all the planets, the values of Hsub(i)/Hsub(E) are calculated, where Hsub(i) and Hsub(E) are the field strengths of the i-th planet and that of the Earth. The experimental data on the dynamic compression of the Mercury confirm the calculations made. It is concluded that the problem of the origin and moving forces of the terrestrial magnetic field may be resolved only within the framework of comparative planetology

  17. MAGNET / INFRASTRUCTURE

    CERN Multimedia

    D. Campi

    The final fast discharge of the Magnet took place on 3rd of November. The Coil reached a temperature of 70K by internal energy dissipation. By injecting a current of 200 A room temperature was reached on the 23rd November. During the heating of the coil un-connecting of the first magnet connectors on YBO was started to give the earliest possible access to the assembly groups and to continue the installation of the muon chambers. The removal of the pumping lines and the disconnection of the vacuum system was instead done as soon as the room temperature was reached: more precisely from the 4 to the 18 December. The disconnection of the transfer line from the cold box and the completion of the removal of the control cables of the vacuum system and cryogenics was done at last. In January 2007 the disconnection of MCS-MSS, CDS, vacuum racks and their cable trays was also achieved. After coil disconnection the effort of the magnet team has been mainly devoted in optimizing the lowering and reassembly of the a...

  18. Magnetic Reconnection

    International Nuclear Information System (INIS)

    We review the fundamental physics of magnetic reconnection in laboratory and space plasmas, by discussing results from theory, numerical simulations, observations from space satellites, and the recent results from laboratory plasma experiments. After a brief review of the well-known early work, we discuss representative recent experimental and theoretical work and attempt to interpret the essence of significant modern findings. In the area of local reconnection physics, many significant findings have been made with regard to two-fluid physics and are related to the cause of fast reconnection. Profiles of the neutral sheet, Hall currents, and the effects of guide field, collisions, and micro-turbulence are discussed to understand the fundamental processes in a local reconnection layer both in space and laboratory plasmas. While the understanding of the global reconnection dynamics is less developed, notable findings have been made on this issue through detailed documentation of magnetic self-organization phenomena in fusion plasmas. Application of magnetic reconnection physics to astrophysical plasmas is also briefly discussed.

  19. Magnetic Reconnection

    Energy Technology Data Exchange (ETDEWEB)

    Masaaki Yamada, Russell Kulsrud and Hantao Ji

    2009-09-17

    We review the fundamental physics of magnetic reconnection in laboratory and space plasmas, by discussing results from theory, numerical simulations, observations from space satellites, and the recent results from laboratory plasma experiments. After a brief review of the well-known early work, we discuss representative recent experimental and theoretical work and attempt to interpret the essence of significant modern findings. In the area of local reconnection physics, many significant findings have been made with regard to two- uid physics and are related to the cause of fast reconnection. Profiles of the neutral sheet, Hall currents, and the effects of guide field, collisions, and micro-turbulence are discussed to understand the fundamental processes in a local reconnection layer both in space and laboratory plasmas. While the understanding of the global reconnection dynamics is less developed, notable findings have been made on this issue through detailed documentation of magnetic self-organization phenomena in fusion plasmas. Application of magnetic reconnection physics to astrophysical plasmas is also brie y discussed.

  20. Magnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bihler, Christoph

    2009-04-15

    In this thesis we investigated in detail the properties of Ga{sub 1-x}Mn{sub x}As, Ga{sub 1-x}Mn{sub x}P, and Ga{sub 1-x}Mn{sub x}N dilute magnetic semiconductor thin films with a focus on the magnetic anisotropy and the changes of their properties upon hydrogenation. We applied two complementary spectroscopic techniques to address the position of H in magnetic semiconductors: (i) Electron paramagnetic resonance, which provides direct information on the symmetry of the crystal field of the Mn{sup 2+} atoms and (ii) x-ray absorption fine structure analysis which allows to probe the local crystallographic neighborhood of the absorbing Mn atom via analysing the fine structure at the Mn K absorption edge. Finally, we discussed the obstacles that have to be overcome to achieve Curie temperatures above the current maximum in Ga{sub 1-x}Mn{sub x}As of 185 K. Here, we outlined in detail the generic problem of the formation of precipitates at the example of Ge:MN. (orig.)

  1. Tuning the Magnetic Transport of an Induction LINAC using Emittance

    Energy Technology Data Exchange (ETDEWEB)

    Houck, T L; Brown, C G; Ong, M M; Paul, A C; Wargo, P E; Zentler, J M

    2006-08-11

    The Lawrence Livermore National Laboratory Flash X-Ray (FXR) machine is a linear induction accelerator used to produce a nominal 18 MeV, 3 kA, 65 ns pulse width electron beam for hydrodynamic radiographs. A common figure of merit for this type of radiographic machine is the x-ray dose divided by the spot area on the bremsstrahlung converter where a higher FOM is desired. Several characteristics of the beam affect the minimum attainable x-ray spot size. The most significant are emittance (chaotic transverse energy), chromatic aberration (energy variation), and beam motion (transverse instabilities and corkscrew motion). FXR is in the midst of a multi-year optimization project to reduce the spot size. This paper describes the effort to reduce beam emittance by adjusting the fields of the transport solenoids and position of the cathode. If the magnetic transport is not correct, the beam will be mismatched and undergo envelope oscillations increasing the emittance. We measure the divergence and radius of the beam in a drift section after the accelerator by imaging the optical transition radiation (OTR) and beam envelope on a foil. These measurements are used to determine an emittance. Relative changes in the emittance can be quickly estimated from the foil measurements allowing for an efficient, real-time study. Once an optimized transport field is determined, the final focus can be adjusted and the new x-ray spot measured. A description of the diagnostics and analysis is presented.

  2. Tuning the Magnetic Transport of an Induction LINAC using Emittance

    International Nuclear Information System (INIS)

    The Lawrence Livermore National Laboratory Flash X-Ray (FXR) machine is a linear induction accelerator used to produce a nominal 18 MeV, 3 kA, 65 ns pulse width electron beam for hydrodynamic radiographs. A common figure of merit for this type of radiographic machine is the x-ray dose divided by the spot area on the bremsstrahlung converter where a higher FOM is desired. Several characteristics of the beam affect the minimum attainable x-ray spot size. The most significant are emittance (chaotic transverse energy), chromatic aberration (energy variation), and beam motion (transverse instabilities and corkscrew motion). FXR is in the midst of a multi-year optimization project to reduce the spot size. This paper describes the effort to reduce beam emittance by adjusting the fields of the transport solenoids and position of the cathode. If the magnetic transport is not correct, the beam will be mismatched and undergo envelope oscillations increasing the emittance. We measure the divergence and radius of the beam in a drift section after the accelerator by imaging the optical transition radiation (OTR) and beam envelope on a foil. These measurements are used to determine an emittance. Relative changes in the emittance can be quickly estimated from the foil measurements allowing for an efficient, real-time study. Once an optimized transport field is determined, the final focus can be adjusted and the new x-ray spot measured. A description of the diagnostics and analysis is presented

  3. An optimized magnet for magnetic refrigeration

    OpenAIRE

    Bjørk, Rasmus; Bahl, Christian Robert Haffenden; Smith, Anders; Christensen, Dennis; Pryds, Nini

    2014-01-01

    A magnet designed for use in a magnetic refrigeration device is presented. The magnet is designed by applying two general schemes for improving a magnet design to a concentric Halbach cylinder magnet design and dimensioning and segmenting this design in an optimum way followed by the construction of the actual magnet. The final design generates a peak value of 1.24 T, an average flux density of 0.9 T in a volume of 2 L using only 7.3 L of magnet, and has an average low flux density of 0.08 T ...

  4. An optimized magnet for magnetic refrigeration

    CERN Document Server

    Bjørk, R; Smith, A; Christensen, D V; Pryds, N

    2014-01-01

    A magnet designed for use in a magnetic refrigeration device is presented. The magnet is designed by applying two general schemes for improving a magnet design to a concentric Halbach cylinder magnet design and dimensioning and segmenting this design in an optimum way followed by the construction of the actual magnet. The final design generates a peak value of 1.24 T, an average flux density of 0.9 T in a volume of 2 L using only 7.3 L of magnet, and has an average low flux density of 0.08 T also in a 2 L volume. The working point of all the permanent magnet blocks in the design is very close to the maximum energy density. The final design is characterized in terms of a performance parameter, and it is shown that it is one of the best performing magnet designs published for magnetic refrigeration.

  5. Designing a magnet for magnetic refrigeration

    DEFF Research Database (Denmark)

    Bjørk, Rasmus

    This thesis investigates the design and optimization of a permanent magnet assembly for use in a magnetic refrigeration device. The heart of magnetic refrigeration is the adiabatic temperature change in the magnetocaloric material which is caused by the magnetic field. In order to design an ideal...... magnet assembly the magnetocaloric materials and the refrigeration process itself and their properties and performance as a function of magnetic field are investigated. For the magnetocaloric materials it is the magnetization, specific heat capacity and adiabatic temperature that are investigated as...... functions of the magnetic field. Following this the process utilized by a magnetic refrigerator to provide cooling is investigated using a publicly available one dimensional numerical model. This process is called active magnetic regeneration (AMR). The aim is to determine the performance of the AMR as a...

  6. An optimized magnet for magnetic refrigeration

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Bahl, Christian Robert Haffenden; Smith, Anders;

    2010-01-01

    A magnet designed for use in a magnetic refrigeration device is presented. The magnet is designed by applying two general schemes for improving a magnet design to a concentric Halbach cylinder magnet design and dimensioning and segmenting this design in an optimum way followed by the construction...... of the actual magnet. The final design generates a peak value of 1.24 T, an average flux density of 0.9 T in a volume of 2 L using only 7.3 L of magnet, and has an average low flux density of 0.08 T also in a 2 L volume. The working point of all the permanent magnet blocks in the design is very close...... to the maximum energy density. The final design is characterized in terms of a performance parameter, and it is shown that it is one of the best performing magnet designs published for magnetic refrigeration....

  7. Magnetic helicity and cosmological magnetic field

    OpenAIRE

    Semikoz, V. B.; Sokoloff, D. D.

    2004-01-01

    The magnetic helicity has paramount significance in nonlinear saturation of galactic dynamo. We argue that the magnetic helicity conservation is violated at the lepton stage in the evolution of early Universe. As a result, a cosmological magnetic field which can be a seed for the galactic dynamo obtains from the beginning a substantial magnetic helicity which has to be taken into account in the magnetic helicity balance at the later stage of galactic dynamo.

  8. MHD simulations of magnetized laser-plasma interaction for laboratory astrophysics

    Science.gov (United States)

    Khiar, Benjamin; Ciardi, Andrea; Vinci, Tommaso; Revet, Guilhem; Fuchs, Julien; Higginson, Drew

    2015-11-01

    Laser-driven plasmas coupled with externally applied strong, steady-state, magnetic fields have applications that range from ICF to astrophysical studies of jet collimation, accretion shock dynamics in young stars and streaming instabilities in space plasmas. We have recently included the modelling of laser energy deposition in our three-dimensional, resistive two-temperature MHD code GORGON. The model assumes linear inverse-bremsstrahlung absorption and the laser propagation is done in the geometrical optics approximation. We present full scale numerical simulations of actual experiments performed on the ELFIE installation at LULI, including plasma generated from single and multiple laser plasmas embedded in a magnetic field of strength up to 20 T, and experiments and astrophysical simulations that have shown the viability of poloidal magnetic fields to directly result in the collimation of outflows and the formation of jets in astrophysical accreting systems, such as in young stellar objects. The authors acknowledge the support from the Ile-de-France DIM ACAV, from the LABEX Plas@par and from the ANR grant SILAMPA.

  9. Properties of carbon-based structures synthesized in nuclear reactions induced by bremsstrahlung γ quanta with threshold energy of 10 MeV at helium pressure of 1.1 kbar

    Science.gov (United States)

    Didyk, A. Yu.; Wiśniewski, R.

    2016-07-01

    Helium gas with an initial pressure of about 1.1 kbar inside a high-pressure chamber (HeHPC) has been irradiated by bremsstrahlung γ quanta with a threshold energy of 10 MeV for 1.0 × 105 s produced by an electron-beam current of 22-24 μA. After opening the HeHPC, the residual pressure of helium is equal to 430 bar. Synthesized black foils with a variety of other objects are found inside the HeHPC. They are located on the inner surfaces of the reaction chamber made of high-purity copper (99.99%), the entrance the window of γ quanta made of beryllium bronze and a copper container of nuclear and chemical reaction products. Elemental analysis with the use of scanning electron microscopy and X-ray microprobe analysis has revealed that the foils contain predominantly carbon and small quantities of other elements from carbon to iron. The results are in good agreement with the cycle of investigations of the authors devoted to the γ-quanta irradiation of dense hydrogen and helium gases in the presence (absence) of metals in a reaction chamber.

  10. Associated Particle Tagging (APT) in Magnetic Spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, David V.; Baciak, James E.; Stave, Sean C.; Chichester, David; Dale, Daniel; Kim, Yujong; Harmon, Frank

    2012-10-16

    Summary In Brief The Associated Particle Tagging (APT) project, a collaboration of Pacific Northwest National Laboratory (PNNL), Idaho National Laboratory (INL) and the Idaho State University (ISU)/Idaho Accelerator Center (IAC), has completed an exploratory study to assess the role of magnetic spectrometers as the linchpin technology in next-generation tagged-neutron and tagged-photon active interrogation (AI). The computational study considered two principle concepts: (1) the application of a solenoidal alpha-particle spectrometer to a next-generation, large-emittance neutron generator for use in the associated particle imaging technique, and (2) the application of tagged photon beams to the detection of fissile material via active interrogation. In both cases, a magnetic spectrometer momentum-analyzes charged particles (in the neutron case, alpha particles accompanying neutron generation in the D-T reaction; in the tagged photon case, post-bremsstrahlung electrons) to define kinematic properties of the relevant neutral interrogation probe particle (i.e. neutron or photon). The main conclusions of the study can be briefly summarized as follows: Neutron generator: • For the solenoidal spectrometer concept, magnetic field strengths of order 1 Tesla or greater are required to keep the transverse size of the spectrometer smaller than 1 meter. The notional magnetic spectrometer design evaluated in this feasibility study uses a 5-T magnetic field and a borehole radius of 18 cm. • The design shows a potential for 4.5 Sr tagged neutron solid angle, a factor of 4.5 larger than achievable with current API neutron-generator designs. • The potential angular resolution for such a tagged neutron beam can be less than 0.5o for modest Si-detector position resolution (3 mm). Further improvement in angular resolution can be made by using Si-detectors with better position resolution. • The report documents several features of a notional generator design incorporating the

  11. Magnetic Storms

    Science.gov (United States)

    Tsurutani, Bruce T.; Gonzalez, Walter D.

    1998-01-01

    One of the oldest mysteries in geomagnetism is the linkage between solar and geomagnetic activity. The 11-year cycles of both the numbers of sunspots and Earth geomagnetic storms were first noted by Sabine. A few years later, speculation on a causal relationship between flares and storms arose when Carrington reported that a large magnetic storm followed the great September 1859 solar flare. However, it was not until this century that a well-accepted statistical survey on large solar flares and geomagnetic storms was performed, and a significant correlation between flares and geomagnetic storms was noted. Although the two phenomena, one on the Sun and the other on the Earth, were statistically correlated, the exact physical linkage was still an unknown at this time. Various hypotheses were proposed, but it was not until interplanetary spacecraft measurements were available that a high-speed plasma stream rich in helium was associated with an intense solar flare. The velocity of the solar wind increased just prior to and during the helium passage, identifying the solar ejecta for the first time. Space plasma measurements and Skylab's coronagraph images of coronal mass elections (CMES) from the Sun firmly established the plasma link between the Sun and the Earth. One phenomenon associated with magnetic storms is brilliant "blood" red auroras, as shown.

  12. Magnetic fluids - suspensions of magnetic dipoles and their magnetic control

    CERN Document Server

    Odenbach, S

    2003-01-01

    Suspensions of magnetic nanoparticles exhibit normal liquid behaviour coupled with superparamagnetic properties. This leads to the possibility to control the properties and the flow of these liquids with moderate magnetic fields. The magnetic control enables various experiments in fluid mechanics and gives rise to the development of numerous technical and medical applications. Ferrofluids and their general properties will be introduced and, as examples for the magnetic control of their flow and properties, thermomagnetic convection and magnetoviscous effects will be discussed in some detail.

  13. MAGNETIC WOVEN FABRICS - PHYSICAL AND MAGNETIC PROPERTIES

    Directory of Open Access Journals (Sweden)

    GROSU Marian C

    2015-05-01

    Full Text Available A coated material is a composite structure that consists of at least two components: base material and coating layer. The purpose of coating is to provide special properties to base material, with potential to be applied in EMI shielding and diverse smart technical fields. This paper reports the results of a study about some physical and magnetic properties of coated woven fabrics made from cotton yarns with fineness of 17 metric count. For this aim, a plain woven fabric was coated with a solution hard magnetic polymer based. As hard magnetic powder, barium hexaferrite (BaFe12O19 was selected. The plain woven fabric used as base has been coated with five solutions having different amounts of hard magnetic powder (15% - 45% in order to obtain five different magnetic woven fabrics. A comparison of physical properties regarding weight (g/m2, thickness (mm, degree of charging (% and magnetic properties of magnetic woven samples were presented. Saturation magnetizing (emu/g, residual magnetizing (emu/g and coercive force (kA/m of pure hard magnetic powder and woven fabrics have been studied as hysteresis characteristics. The magnetic properties of the woven fabrics depend on the mass percentage of magnetic powder from coating solution. Also, the residual magnetism and coercive field of woven fabrics represents only a part of bulk barium hexafferite residual magnetism and coercive field.

  14. Magnetic Nano-structures

    Institute of Scientific and Technical Information of China (English)

    姚永德

    2004-01-01

    Fabrication of magnetic nano-structures with dots array and wires has been paid attention recently due to the application of high-density magnetic recording. In this study, we fabricated the magnetic dots array and wires through several ways that ensure the arrangement of magnetic dots and wires to be the structures we designed. Their magnetic properties are studied experimentally.

  15. Magnetic quantum dots and magnetic edge states

    International Nuclear Information System (INIS)

    Starting with defining the magnetic edge state in a magnetic quantum dot, which becomes quite popular nowadays conjunction with a possible candidate for a high density memory device or spintronic materials, various magnetic nano-quantum structures are reviewed in detail. We study the magnetic edge states of the two dimensional electron gas in strong perpendicular magnetic fields. We find that magnetic edge states are formed along the boundary of the magnetic dot, which is formed by a nonuniform distribution of magnetic fields. These magnetic edge states circulate either clockwise or counterclockwise, depending on the number of missing flux quanta, and exhibit quite different properties, as compared to the conventional ones which are induced by electrostatic confinements in the quantum Hall system. We also find that a close relation between the quantum mechanical eigenstates and the classical trajectories in the magnetic dot. When a magnetic dot is located inside a quantum wire, the edge-channel scattering mechanism by the magnetic quantum dot is very different from that by electrostatic dots. Here, the magnetic dot is formed by two different magnetic fields inside and outside the dot. We study the ballistic edge-channel transport and magnetic edge states in this situation. When the inner field is parallel to the outer one, the two-terminal conductance is quantized and shows the features of a transmission barrier and a resonator. On the other hand, when the inner field is reversed, the conductance is not quantized and all channels can be completely reflected in some energy ranges. The difference between the above two cases results from the distinct magnetic confinements. We also describe successfully the edge states of magnetic quantum rings and others in detail

  16. Magnetism of Carbonados

    Science.gov (United States)

    Kletetschka, G.; Taylor, P. T.; Wasilewski, P. J.

    2000-01-01

    Origin of Carbonado is not clear. Magnetism of Carbonado comes from the surface, indicating contemporary formation of both the surface and magnetic carriers. The interior of carbonado is relatively free of magnetic phases.

  17. MRI (Magnetic Resonance Imaging)

    Science.gov (United States)

    ... Procedures Medical Imaging MRI (Magnetic Resonance Imaging) MRI (Magnetic Resonance Imaging) Share Tweet Linkedin Pin it More sharing options ... 8 MB) Also available in Other Language versions . Magnetic Resonance Imaging (MRI) is a medical imaging procedure for making ...

  18. Magnetic Graphene Nanohole Superlattices

    OpenAIRE

    Yu, Decai; Lupton, Elizabeth M.; Liu, Miao; Wei LIU; Liu, Feng

    2008-01-01

    We investigate the magnetic properties of nano-holes (NHs) patterned in graphene using first principles calculations. We show that superlattices consisting of a periodic array of NHs form a new family of 2D crystalline "bulk" magnets whose collective magnetic behavior is governed by inter-NH spin-spin interaction. They exhibit long-range magnetic order well above room temperature. Furthermore, magnetic semiconductors can be made by doping magnetic NHs into semiconducting NH superlattices. Our...

  19. Magnetic nanoparticle motion in external magnetic field

    International Nuclear Information System (INIS)

    A set of equations describing the motion of a free magnetic nanoparticle in an external magnetic field in a vacuum, or in a medium with negligibly small friction forces is postulated. The conservation of the total particle momentum, i.e. the sum of the mechanical and the total spin momentum of the nanoparticle is taken into account explicitly. It is shown that for the motion of a nanoparticle in uniform magnetic field there are three different modes of precession of the unit magnetization vector and the director that is parallel the particle easy anisotropy axis. These modes differ significantly in the precession frequency. For the high-frequency mode the director points approximately along the external magnetic field, whereas the frequency and the characteristic relaxation time of the precession of the unit magnetization vector are close to the corresponding values for conventional ferromagnetic resonance. On the other hand, for the low-frequency modes the unit magnetization vector and the director are nearly parallel and rotate in unison around the external magnetic field. The characteristic relaxation time for the low-frequency modes is remarkably long. This means that in a rare assembly of magnetic nanoparticles there is a possibility of additional resonant absorption of the energy of alternating magnetic field at a frequency that is much smaller compared to conventional ferromagnetic resonance frequency. The scattering of a beam of magnetic nanoparticles in a vacuum in a non-uniform external magnetic field is also considered taking into account the precession of the unit magnetization vector and director. - Highlights: • There are three different modes of the unit magnetization vector precession for a free magnetic nanoparticle in uniform external magnetic field. • The high-frequency mode is similar to the conventional ferromagnetic resonance. The frequencies of the low-frequency modes can be two orders of magnitude lower. • The characteristic relaxation

  20. Magnetic guns with cylindrical permanent magnets

    Czech Academy of Sciences Publication Activity Database

    Vokoun, David; Beleggia, M.; Heller, Luděk

    2012-01-01

    Roč. 324, č. 9 (2012), s. 1715-1719. ISSN 0304-8853 R&D Projects: GA ČR(CZ) GAP107/11/0391; GA AV ČR IAA100100920 Institutional research plan: CEZ:AV0Z10100520 Keywords : permanent magnet * cylindrical magnet * Earnshaw's theorem * magnetic gun * magnetostatic interaction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.826, year: 2012 http://www.sciencedirect.com/science/article/pii/S0304885311008997

  1. Magnetic Propeller for Uniform Magnetic Field Levitation

    OpenAIRE

    Krinker, Mark; Bolonkin, Alexander

    2008-01-01

    Three new approaches to generating thrust in uniform magnetic fields are proposed. The first direction is based on employing Lorentz force acting on partial magnetically shielded 8-shaped loop with current in external magnetic field, whereby a net force rather than a torque origins. Another approach, called a Virtual Wire System, is based on creating a magnetic field having an energetic symmetry (a virtual wire), with further superposition of external field. The external field breaks the symm...

  2. Magnetic resonance angiography

    Science.gov (United States)

    MRA; Angiography - magnetic resonance ... Kwong RY. Cardiovascular Magnetic Resonance Imaging. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine . ...

  3. Magnetic Barkhausen noise at different magnetization conditions

    Czech Academy of Sciences Publication Activity Database

    Stupakov, Alexandr; Perevertov, Oleksiy; Neslušan, M.

    2015-01-01

    Roč. 66, č. 7 (2015), s. 10-13. ISSN 1335-3632 R&D Projects: GA ČR GA13-18993S Institutional support: RVO:68378271 Keywords : Barkhausen noise * surface magnetic field * magnetization control * magnetic hysteresis * digital feedback loop Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 0.378, year: 2014

  4. Low-Dose-Rate Computed Tomography System Utilizing 25 mm/s-Scan Silicon X-ray Diode and Its Application to Iodine K-Edge Imaging Using Filtered Bremsstrahlung Photons

    Science.gov (United States)

    Matsushita, Ryo; Sato, Eiichi; Yanbe, Yutaka; Chiba, Hiraku; Maeda, Tomoko; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

    2013-03-01

    A low-dose-rate X-ray computed tomography (CT) system is useful for reducing absorbed dose for patients. The CT system with a tube current of sub-mA was developed using a silicon X-ray diode (Si-XD). The Si-XD is a high-sensitivity Si photodiode (PD) selected for detecting X-ray photons, and the X-ray sensitivity of the Si-XD was twice as high as that of Si-PD cerium-doped yttrium aluminum perovskite [YAP(Ce)]. X-ray photons are directly detected using the Si-XD without a scintillator, and the photocurrent from the diode is amplified using current-voltage and voltage-voltage amplifiers. The output voltage is converted into logical pulses using a voltage-frequency converter with a maximum frequency of 500 kHz, and the frequency is proportional to the voltage. The pulses from the converter are sent to the differentiator with a time constant of 500 ns to generate short positive pulses for counting, and the pulses are counted using a counter card. Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan. The exposure time for obtaining a tomogram was 5 min at a scan step of 0.5 mm and a rotation step of 3.0°. The tube current and voltage were 0.55 mA and 60 kV, respectively, and iodine K-edge CT was carried out using filtered bremsstrahlung X-ray spectra with a peak energy of 38 keV.

  5. Environmental magnetism

    CERN Document Server

    Thompson, Roy

    1986-01-01

    The scientist will be forced, in the unenthusiastic words of one of my scientific colleagues, 'to slosh about in the primordial ooze known as inter-disciplinary studies'. John Passmore Man's responsibility for nature The present text has arisen from some thirteen years advances in our perception, appraisal and creative use of collaboration between the two authors. During that of order in natural systems. Out of this can come period, upwards of a dozen postgraduates in enhanced insight into processes, structures and Edinburgh, the New University of Ulster and Liver­ systems interactions on all temporal and spatial scales pool have been closely involved in exploring many of and at all integrative levels from subatomic to cosmic. the applications of magnetic measurements described In the environment, elements of order are often in the second half of the book. Much of the text is difficult to appraise and analyse, not only because of based on their work, both published and unpublished. intrinsic complexity, but ...

  6. Magnetic domains the analysis of magnetic microstructures

    CERN Document Server

    Hubert, Alex

    1998-01-01

    The book gives a systematic and comprehensive survey of the complete area of magnetic microstructures. It reaches from micromagnetism of nanoparticles to complex structures of extended magnetic materials. The book starts with a comprehensive evaluation of traditional and modern experimental methods for the observation of magnetic domains and continues with the treatment of important methods for the theoretical analysis of magnetic microcstructures. A survey of the necessary techniques in materials characterization is given. The book offers an observation and analysis of magnetic domains in all

  7. Study of magnetization reversal in hybrid magnets

    International Nuclear Information System (INIS)

    A study of magnetic interactions and magnetization reversal at room temperature in hybrid magnets consisting of micrometrics particles of strontium ferrite and Magnequench MQP-Q alloy was carried out. Materials with three different compositions were considered. These materials present different intensity of coupling between their components. In each case, the evolution of the DCD reversible (Mrev) and irreversible (Mirr) magnetization components during the magnetization and the demagnetization processes was determined. Mrev(Mirr)Hi curves were built, being Hi the internal field of the sample. In order to investigate the nature of the magnetic interactions between the different grains, a study of the δMd(Hi) plots was developed. The experimental behavior of the Mrev(Mirr)Hi curves suggest the existence of a complex non-uniform mechanism for the magnetization reversal in these materials. The δMd(Hi) plots shown a notable predominance of the demagnetizing-like magnetostatic interactions

  8. X-ray Polarization Signatures of Compton Scattering in Magnetic Cataclysmic Variables

    CERN Document Server

    McNamara, Aimee; Wu, Kinwah

    2008-01-01

    Compton scattering within the accretion column of magnetic cataclysmic variables (mCVs) can induce a net polarization in the X-ray emission. We investigate this process using Monte Carlo simulations and find that significant polarization can arise as a result of the stratified flow structure in the shock-ionized column. We find that the degree of linear polarization can reach levels up to ~8% for systems with high accretion rates and low white-dwarf masses, when viewed at large inclination angles with respect to the accretion column axis. These levels are substantially higher than previously predicted estimates using an accretion column model with uniform density and temperature. We also find that for systems with a relatively low-mass white dwarf accreting at a high accretion rate, the polarization properties may be insensitive to the magnetic field, since most of the scattering occurs at the base of the accretion column where the density structure is determined mainly by bremsstrahlung cooling instead of cy...

  9. Magnetic multilayer structure

    Energy Technology Data Exchange (ETDEWEB)

    Herget, Philipp; O' Sullivan, Eugene J.; Romankiw, Lubomyr T.; Wang, Naigang; Webb, Bucknell C.

    2016-07-05

    A mechanism is provided for an integrated laminated magnetic device. A substrate and a multilayer stack structure form the device. The multilayer stack structure includes alternating magnetic layers and diode structures formed on the substrate. Each magnetic layer in the multilayer stack structure is separated from another magnetic layer in the multilayer stack structure by a diode structure.

  10. Magnetic field line Hamiltonian

    Energy Technology Data Exchange (ETDEWEB)

    Boozer, A.H.

    1985-02-01

    The basic properties of the Hamiltonian representation of magnetic fields in canonical form are reviewed. The theory of canonical magnetic perturbation theory is then developed and applied to the time evolution of a magnetic field embedded in a toroidal plasma. Finally, the extension of the energy principle to tearing modes, utilizing the magnetic field line Hamiltonian, is outlined.

  11. Magnetic field line Hamiltonian

    International Nuclear Information System (INIS)

    The basic properties of the Hamiltonian representation of magnetic fields in canonical form are reviewed. The theory of canonical magnetic perturbation theory is then developed and applied to the time evolution of a magnetic field embedded in a toroidal plasma. Finally, the extension of the energy principle to tearing modes, utilizing the magnetic field line Hamiltonian, is outlined

  12. Superconducting magnets 1992

    International Nuclear Information System (INIS)

    This report discusses the following topics on Superconducting Magnets; SSC Magnet Industrialization; Collider Quadrupole Development; A Record-Setting Magnet; D20: The Push Beyond 10T; Nonaccelerator Applications; APC Materials Development; High-Tc at Low Temperature; Cable and Cabling-Machine Development; and Analytical Magnet Design

  13. High gradient magnetic separation

    International Nuclear Information System (INIS)

    In a process in which magnetic material is trapped in a filter disposed in a magnetic field, and is unloaded by passing a fluid through the filter in the absence of the initial magnetic field, the magnetic field is first reduced to an intermediate value to allow unloading of the more weakly magnetic particles, the more strongly magnetic particles being retained and subsequently unloaded by further reduction of the magnetic field. Stage by stage reduction of the magnetic field during unloading allows separation of different species from the mixture. As an example the method can be applied to the separation of uranium compounds from mine ores. The uranium compounds are magnetic, while most of the other constituents of the ore are non-magnetic. The starting material is a suspension of the ore. Water is used for unloading. The filter material in this case is stainless steel balls. (author)

  14. Integrated magnetic transformer assembly

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to an integrated magnetics transformer assembly comprising a first magnetically permeable core forming a first substantially closed magnetic flux path and a second magnetically permeable core forming a second substantially closed magnetic flux path. A first input...... inductor winding is wound around a first predetermined segment of the first magnetically permeable core and a second input inductor winding is wound around a first predetermined segment of the second magnetically permeable core. The integrated magnetics transformer assembly further comprises a first output...... inductor winding comprising series coupled first and second half-windings wherein the first half-winding is wound around a second predetermined segment of the first magnetically permeable core and the second half-winding is wound around a second predetermined segment of the second magnetically permeable...

  15. Permanent magnet system of alpha magnetic spectrometer

    Institute of Scientific and Technical Information of China (English)

    陈和生

    2000-01-01

    Alpha magnetic spectrometer (AMS) is the first large magnetic spectrometer in space. Its precursor flight was completed successfully in June 1998. The key part of AMS is the permanent magnet system, which was built by the Institute of Electric Engineering, the Institute of High Energy Physics and the Chinese Academy of Launch Vehicle Technology. This system includes a permanent magnet made of high grade NdFeB and a support structure. The unique design of the permanent magnet based on the magic ring fulfills the severe requirements on the magnetic field leakage and the dipole moment for space experiments. The permanent magnet weighs about 2 tons, and provides a geometric acceptance of 0.6 m2·sr and an analyzing power BL2 of 0.135 T·m2. It works up to 40℃ without demagnetization. The main structure is a thin double shell, which undergoes the strong magnetic force and torque of the permanent magnet, as well as the large load during launching and landing. The permanent magnet system fulfills the requirem

  16. Permanent magnet system of alpha magnetic spectrometer

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Alpha magnetic spectrometer (AMS) is the first large magnetic spectrometer in space. Its precursor flight was completed successfully in June 1998. The key part of AMS is the permanent magnet system, which was built by the Institute of Electric Engineering, the Institute of High Energy Physics and the Chinese Academy of Launch Vehicle Technology. This system includes a permanent magnet made of high grade NdFeB and a support structure. The unique design of the permanent magnet based on the magic ring fulfills the severe requirements on the magnetic field leakage and the dipole moment for space experiments. The permanent magnet weighs about 2 tons, and provides a geometric acceptance of 0.6 m2 ·sr and an analyzing power BL2 of 0.135 T·m2. It works up to 40℃ without demagnetization. The main structure is a thin double shell, which undergoes the strong magnetic force and torque of the permanent magnet, as well as the large load during launching and landing. The permanent magnet system fulfills the requirements from AMS, and satisfies the strict safety standards of NASA.

  17. Magnetic Flux and Helicity of Magnetic Clouds

    Science.gov (United States)

    Démoulin, P.; Janvier, M.; Dasso, S.

    2016-02-01

    Magnetic clouds (MCs) are formed by flux ropes (FRs) launched from the Sun as part of coronal mass ejections (CMEs). They carry away a large amount of magnetic flux and helicity. The main aim of this study is to quantify these amounts from in situ measurements of MCs at 1 AU. The fit of these data by a local FR model provides the axial magnetic field strength, the radius, the magnetic flux, and the helicity per unit length along the FR axis. We show that these quantities are statistically independent of the position along the FR axis. We then derive the generic shape and length of the FR axis from two sets of MCs. These results improve the estimation of magnetic helicity. Next, we evaluate the total magnetic flux and helicity that cross the sphere of radius of 1 AU, centred at the Sun, per year and during a solar cycle. We also include in the study two sets of small FRs that do not have all the typical characteristics of MCs. While small FRs are at least ten times more numerous than MCs, the magnetic flux and helicity are dominated by the contribution from the larger MCs. In one year they carry away the magnetic flux of about 25 large active regions and the magnetic helicity of 200 of them. MCs carry away an amount of unsigned magnetic helicity similar to the amount estimated for the solar dynamo and that measured in emerging active regions.

  18. Magnetic Damping For Maglev

    OpenAIRE

    Zhu, S; Cai, Y.; Rote, D.M.; S.S. Chen

    1998-01-01

    Magnetic damping is one of the important parameters that control the response and stability of maglev systems. An experimental study to measure magnetic damping directly is presented. A plate attached to a permanent magnet levitated on a rotating drum was tested to investigate the effect of various parameters, such as conductivity, gap, excitation frequency, and oscillation amplitude, on magnetic damping. The experimental technique is capable of measuring all of the magnetic damping coefficie...

  19. Ultrafast Magnetization Dynamics

    OpenAIRE

    Woodford, S.

    2008-01-01

    This thesis addresses ultrafast magnetization dynamics from a theoretical perspective. The manipulation of magnetization using the inverse Faraday effect has been studied, as well as magnetic relaxation processes in quantum dots. The inverse Faraday effect – the generation of a magnetic field by nonresonant, circularly polarized light – offers the possibility to control and reverse magnetization on a timescale of a few hundred femtoseconds. This is important both for the technological advant...

  20. Integral magnetic field measurement of dipole magnets

    International Nuclear Information System (INIS)

    This article presents the basic principle of dipole integral magnetic field measurement. The integral coil which has the same radius with the dipole magnets was used to measure the integral magnetic field of different magnets in Cooler Storage Ring (HIRFL-CSR). The article also generally introduced the software and hardware systems of the automatic measurement device. According to the repetitive experiments, a suit of better measurement got to be summarized. On the other hand, the article recommends the way of the data processing which were decided by the measuring instrument and environment influence. The practical measured results proved the measurement system is reliable and stable