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Sample records for bremsstrahlung photons produced

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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)

  7. 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.

  8. 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

  9. 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.

  10. Studies on Neutron, Photon (Bremsstrahlung and Proton Induced Fission of Actinides and Pre-Actinides

    Directory of Open Access Journals (Sweden)

    H. Naik

    2015-08-01

    Full Text Available We present the yields of various fission products determined in the reactor neutron, 3.7-18.1 MeV quasi-mono energetic neutron, 8-80 MeV bremsstrahlung and 20-45 MeV proton induced fission of 232Th and 238U using radiochemical and off-line beta or gamma ray counting. The yields of the fission products in the bremsstrahlung induced fission natPb and 209Bi with 50- 70 MeV and 2.5 GeV based on off-line gamma ray spectrometric technique were also presented. From the yields of fission products, the mass chains yields were obtained using charge distribution correction. From the mass yield distribution, the peak-to-valley (P/V ratio was obtained. The role of excitation energy on the peak-to-valley ratio and fine structure such as effect of shell closure proximity and even-odd effect of mass yield distribution were examined. The higher yields of the fission products around A=133-134, 138-140 and 143-144 and their complementary products explained from the nuclear structure effect and role of standard I and II mode of asymmetric fission. In the neutron, photon (bremsstrahlung and proton induced fission, the asymmetric mass distribution for actinides (Th, U and symmetric distribution for pre-actinides (Pb, Bi were explained from different type of potential fission barrier

  11. 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

  12. 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-

  13. 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.

  14. 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

  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. Photon and photoneutron spectra produced in radiotherapy Linacs

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Martinez O, S. A. [Universidad Pedagogica y Tecnologica de Colombia, Grupo de Fisica Nuclear Aplicada y Simulacion, Av. Central del Norte Km. 1, Via Paipa Tunja, Boyaca (Colombia); Benites R, J. L. [Universidad Autonoma de Nayarit, Postgrado CBAP, Carretera Tepic Compostela Km. 9, Xalisco, Nayarit (Mexico); Lallena, A. M., E-mail: fermineutron@yahoo.com [Universida de Granada, Departamento de Fisica Atomica, Molecular y Nuclear, E-18071 Granada (Spain)

    2011-10-15

    A Monte Carlo calculation, using the MCNPX code, was carried out in order to estimate the photon and neutron spectra in two locations of two linacs operating at 15 and 18 MV. Detailed models of both linac heads were used in the calculations. Spectra were estimated below the flattening filter and at the isocenter. Neutron spectra show two components due to evaporation and knock-on neutrons. Lethargy spectra under the filter were compared to the spectra calculated from the function quoted by Tosi et al. that describes reasonably well neutron spectra beyond 1 MeV, though tends to underestimate the energy region between 10{sup -6} and 1 MeV. Neutron and Bremsstrahlung spectra show the same features regardless of the linac voltage. The amount of photons and neutrons produced by the 15 MV linac is smaller than that found for the 18 MV linac. As expected, Bremsstrahlung spectra ends according to the voltage used to accelerate the electrons. (Author)

  17. Photon and photoneutron spectra produced in radiotherapy Linacs

    International Nuclear Information System (INIS)

    A Monte Carlo calculation, using the MCNPX code, was carried out in order to estimate the photon and neutron spectra in two locations of two linacs operating at 15 and 18 MV. Detailed models of both linac heads were used in the calculations. Spectra were estimated below the flattening filter and at the isocenter. Neutron spectra show two components due to evaporation and knock-on neutrons. Lethargy spectra under the filter were compared to the spectra calculated from the function quoted by Tosi et al. that describes reasonably well neutron spectra beyond 1 MeV, though tends to underestimate the energy region between 10-6 and 1 MeV. Neutron and Bremsstrahlung spectra show the same features regardless of the linac voltage. The amount of photons and neutrons produced by the 15 MV linac is smaller than that found for the 18 MV linac. As expected, Bremsstrahlung spectra ends according to the voltage used to accelerate the electrons. (Author)

  18. Hard Photons Beyond Proton-Neutron Bremsstrahlung in Heavy-Ion Collisions

    OpenAIRE

    Gudima, K.; Ploszajczak, M.

    1999-01-01

    We report on the study of extremely high energy photons, pions and etas, produced in intermediate energy heavy-ion collisions. Possibility of imaging the final-state phase space in these collisions by the Bose-Einstein correlations for photons is critically examined.

  19. 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 ...

  20. 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}_{...

  1. 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...

  2. Measuring fast electron spectra and laser absorption in relativistic laser-solid interactions using differential bremsstrahlung photon detectors

    CERN Document Server

    Scott, R H H; Perez, F; Streeter, M J V; Davies, J R; Schlenvoigt, H -P; Santos, J J; Hulin, S; Lancaster, K L; Baton, S D; Rose, S J; Norreys, P A

    2013-01-01

    A photon detector suitable for the measurement of bremsstrahlung spectra generated in relativistically-intense laser-solid interactions is described. The Monte Carlo techniques used to back-out the fast electron spectrum and laser energy absorbed into fast electrons are detailed. A relativistically-intense laser-solid experiment using frequency doubled laser light is used to demonstrate the effective operation of the detector. The experimental data was interpreted using the 3-spatial-dimension Monte Carlo code MCNPX (Pelowitz 2008), and the fast electron temperature found to be 125 keV.

  3. 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

  4. 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...

  5. 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

  6. 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

  7. 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.

  8. 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)

  9. 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...

  10. 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.

  11. Runaway electrons and Bremsstrahlung

    Science.gov (United States)

    Helander, Per

    2016-09-01

    If an electric field is applied to a plasma, it causes ‘runaway’ acceleration of some electrons—a phenomenon that has been known for almost a century. A paper by Embréus et al (2016 New J. Phys. 18 093023) calculates how the emission of Bremsstrahlung affects the upper end of the energy spectrum of these electrons, and finds that it is important to carefully account for finite energy of the emitted photons.

  12. 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.

  13. 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.

  14. Intravenous coronary angiography utilizing K-emission and bremsstrahlung X-rays produced by electron bombardment

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1992-12-31

    The screening of the general population for coronary artery disease would be practical if a method existed for visualizing the extent of occlusion after an intravenous injection of contrast agent. Measurements performed with synchrotron radiation at SSRL and NSLS have shown that such an intravenous angiography procedure would be possible with an intense source of monochromatic X-rays. Because of the high cost of an electron synchrotron, theoretical analysis and experiments using inanimate phantoms has been undertaken to demonstrate the feasibility of using the spectrum produced by two appropriately chosen anode materials when bombarded with electrons in the 100--500 keV energy range for angiography. By using the X-rays emitted at 120{degree} to the incident electron direction, about 20--30% of the X-ray intensity would be due to K-emission lines. Calculations using the TIGERP Monte Carlo Code, have shown that high quality angiograms of human coronary arteries should be possible with a contrast agent containing ytterbium, if an electron beam pulses of 16 kJ were used for each anode target. The experimental program supported in part by the DOE has consisted of these theoretical calculations and experiments at the Dynamitron Electron Accelerator Facility at BNL.

  15. Radiative Corrections to High Energy Lepton Bremsstrahlung on Heavy Nuclei

    CERN Document Server

    Arbuzov, A B

    2008-01-01

    One-loop radiative corrections to the leptonic tensor in high energy bremsstrahlung on heavy nuclei are calculated. Virtual and real photon radiation is taken into account. Double bremsstrahlung is simulated by means of Monte Carlo. Numerical results are presented for the case of muon bremsstrahlung in conditions of the COMPASS experiment at CERN.

  16. 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.

  17. 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.

  18. Comparison of analytical and Monte Carlo calculations of multi-photon effects in bremsstrahlung emission by high-energy electrons

    DEFF Research Database (Denmark)

    Mangiarotti, Alessio; Sona, Pietro; Ballestrero, Sergio;

    2012-01-01

    Approximate analytical calculations of multi-photon effects in the spectrum of total radiated energy by high-energy electrons crossing thin targets are compared to the results of Monte Carlo type simulations. The limits of validity of the analytical expressions found in the literature are establi...

  19. Goniometer Control System for Coherent Bremsstrahlung Production

    Science.gov (United States)

    Acousta, V. M.

    2002-08-01

    A system for the generation of a high-intensity, quasi-monochromatic photon beam is discussed. The theory behind coherent bremsstrahlung photon beam production is analyzed and developed. The mechanics of a goniometer control system are presented. The software developed for remote control of the goniometer is also discussed. Finally, the results from various performance measurements are included.

  20. Relativistic Non-Thermal Bremsstrahlung Radiation

    CERN Document Server

    Zeković, Vladimir; Dobardzić, Aleksandra; Pavlović, Marko

    2013-01-01

    By applying a method of virtual quanta we derive formulae for relativistic non-thermal bremsstrahlung radiation from relativistic electrons as well as from protons and heavier particles with power-law momentum distribution $N(p)dp = k p^{-q} dp.$ We show that emission which originates from an electron scattering on an ion, represents the most significant component of relativistic non-thermal bremsstrahlung. Radiation from an ion scattering on electron, known as inverse bremsstrahlung, is shown to be negligible in overall non-thermal bremsstrahlung emission. These results arise from theory refinement, where we introduce the dependence of relativistic kinetic energy of an incident particle, upon the energy of scattered photon. In part, it is also a consequence of a different mass of particles and relativistic effects.

  1. Ultrahigh-intensity inverse bremsstrahlung

    Science.gov (United States)

    Kostyukov, I. Yu.; Rax, J.-M.

    1999-01-01

    We study inverse bremsstrahlung in the ultrahigh intensity relativistic regime. The fully relativistic ultrahigh intensity absorption (emission) coefficient is derived for an arbitrary scattering potential and small-angle scattering. We find that in the Coulomb field case this absorption (emission) coefficient can be calculated as a function of the quiver energy, drift momentum, and impact parameter in two complementary regimes: (i) for remote collisions when the impact parameter is larger than the amplitude of the quiver motion, and (ii) for instantaneous collisions when the scattering time is shorter than the period of the wave. Both circular and linear polarizations are considered, and this study reveals that in this relativistic regime inverse bremsstrahlung absorption can be viewed as a harmonic Compton resonance heating of the laser-driven electron by the virtual photon of the ion Coulomb field. The relativistic modification of Marcuse's effect [Bell Syst. Tech. J. 41, 1557 (1962)] are also discussed, and relations with previous nonrelativistic results are elucidated.

  2. Delayed neutron and delayed photon characteristics from photofission of 232Th, 235,238U, and 237Np with endpoint Bremsstrahlung photons in the giant dipole resonance region

    Science.gov (United States)

    Doré, D.; Dighe, P. M.; Berthoumieux, E.; Laborie, J.-M.; Ledoux, X.; Macary, V.; Panebianco, S.; Ridikas, D.

    2009-10-01

    A renewed interest in photonuclear reactions was stimulated by applications as radioactive ion beam production, irradiation stations by high energy photons, shielding of electron accelerators, etc. Today, a particular attention is paid to the non-destructive characterization of waste barrels and the detection of nuclear materials, both based on photofission process and the associated delayed neutron (DN) and delayed photon (DP) emissions. The need of accurate and complete data for DN and DP yields and time characteristics of actinides was the motivation for an experimental campaign, started in 2004. In this paper, the experimental setup and the data analysis method will be presented and the modeling work will be described. Experimental results for DN and DP characteristics will be compared to calculations in the case of photofission of 232Th, 235,238U, and 237Np.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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...

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

    Science.gov (United States)

    Embréus, O.; Stahl, A.; Fülöp, T.

    2016-09-01

    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 by modeling the bremsstrahlung interactions with a Boltzmann collision operator. We find that electrons accelerated by electric fields can reach significantly higher energies than predicted by the commonly used radiative stopping-power model. Furthermore, we show that the emission of soft photons can contribute significantly to the dynamics of electrons with an anisotropic distribution by causing pitch-angle scattering at a rate that increases with energy.

  9. 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.

  10. 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)

  11. Producing the event ready two photon polarization EPR state with linear optics devices

    OpenAIRE

    Xiang-Bin, Wang

    2002-01-01

    We propose a scheme to produce the maximally two photon polarization entangled state(EPR state) with single photon sources and the linear optics devices. In particular, our scheme requires the photon detectors only to distinguish the vacuum and non-vacuum Fock number states. A sophisticated photon detector distinguishing one or two photon states is unnecessary.

  12. 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.

  13. 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.

  14. Characterisation of a MeV Bremsstrahlung x-ray source produced from a high intensity laser for high areal density object radiography

    Energy Technology Data Exchange (ETDEWEB)

    Courtois, C.; Compant La Fontaine, A.; Bazzoli, S.; Bourgade, J. L.; Gazave, J.; Lagrange, J. M.; Landoas, O.; Dain, L. Le; Pichoff, N. [CEA, DAM, DIF, F-91297 Arpajon (France); Edwards, R.; Aedy, C. [AWE Plc., Aldermaston, Reading RG7 4PR (United Kingdom); Mastrosimone, D.; Pien, G.; Stoeckl, C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

    2013-08-15

    Results of an experiment to characterise a MeV Bremsstrahlung x-ray emission created by a short (<10 ps) pulse, high intensity (1.4 × 10{sup 19} W/cm{sup 2}) laser are presented. X-ray emission is characterized using several diagnostics; nuclear activation measurements, a calibrated hard x-ray spectrometer, and dosimeters. Results from the reconstructed x-ray energy spectra are consistent with numerical simulations using the PIC and Monte Carlo codes between 0.3 and 30 MeV. The intense Bremsstrahlung x-ray source is used to radiograph an image quality indicator (IQI) heavily filtered with thick tungsten absorbers. Observations suggest that internal features of the IQI can be resolved up to an external areal density of 85 g/cm{sup 2}. The x-ray source size, inferred by the radiography of a thick resolution grid, is estimated to be approximately 400 μm (full width half maximum of the x-ray source Point Spread Function)

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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...

  20. Treatment of the electrons-photons cascade in the high energy gamma transport; Traitement de la cascade electrons - photons dans le transport des gammas de haute energie

    Energy Technology Data Exchange (ETDEWEB)

    Riz, D

    1999-10-01

    The electrons-photons cascade is an important phenomena occurring in gamma transport. This phenomena called also Bremsstrahlung happens whenever electrons, produced in a photon-atom interaction, trigger emission of photons while slowing down in the matter. Some previous calculations have shown that in particular circumstances, a flux of photons going through a lead plate can be multiplied by 3 when Bremsstrahlung is taken into account. This work is dedicated to a new method developed in CEA to take into account Bremsstrahlung in any gamma transport code using multigroup constants. An electron or a positron produced by an incident photon {gamma} will move till it has lost all its energy in collisions or in emissions of Bremsstrahlung {gamma}'. The path of the electron is short so all the Bremsstrahlung {gamma}' are assumed to be produced at the point of creation of the electron or positron. The result of this method is the knowledge of a transfer probability {gamma}{yields}{gamma}' that can be used in classical gamma transport codes. (A.C.)

  1. 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...

  2. 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.

  3. Coherent bremsstrahlung at the HERA collider

    Energy Technology Data Exchange (ETDEWEB)

    Ginzberg, I.F. (Inst. of Mathematics, Novosibirsk (Russian Federation)); Kotkin, G.L. (Novosibirsk State Univ. (Russian Federation)); Polityko, S.I. (Irkutsk State Univ. (Russian Federation)); Serbo, V.G. (Irkutsk State Univ. (Russian Federation))

    1993-12-01

    We consider a new type of radiation at colliders with short bunches - coherent bremsstrahlung (CBS) which is the radiation of the first bunch particles caused by the collective electromagnetic field of the second bunch. The number of CBS photons for a single collision is dN[sub y][approx]N[sub 0]dE[sub y]/E[sub y] in the energy range E[sub y]< or [approx]E[sub c]=4y[sub 1][sup 2]hc/l[sub 2]. Here y[sub 1]=E[sub 1]/m[sub 1]c[sup 2]; l[sub 2] is the length of the opposing (second) bunch and N[sub 0] is proportional to N[sub 1]N[sub 2][sup 2] where N[sub j] is the j-th bunch population. For the HERA collider N[sub 0]=14, E[sub c]=73 eV in the case when photons are emitted by protons and N[sub 0]=6.10[sup 7], E[sub c]=24 keV - when photons are emitted by electrons. Unusual properties of such a coherent bremsstrahlung and the possibility to use CBS for fast beam steering and for luminosity optimization are discussed. (orig.)

  4. Coherent bremsstrahlung at colliding beams

    Energy Technology Data Exchange (ETDEWEB)

    Ginzburg, I.F. (Inst. of Mathematics, Novosibirsk (Russia)); Kotkin, G.L.; Serbo, V.G. (Novosibirsk State Univ. (Russia)); Polityko, S.I. (Irkutsk State Univ. (Russia))

    1992-07-30

    We consider a new type of radiation at colliders with short bunches - coherent bremsstrahlung (CBS). CBS can be treated as radiation of the first bunch particles caused by the collective electromagnetic field of the short second bunch. A general method for the calculation of this CBS is presented. The number of CBS photons per single collision is dN{sub {gamma}}{approx equal}N{sub 0}dE{sub {gamma}}/E{sub {gamma}} in the energy range E{sub {gamma}}

  5. Vector dark matter annihilation with internal bremsstrahlung

    OpenAIRE

    Bambhaniya, Gulab; Kumar, Jason; Marfatia, Danny; Nayak, Alekha C.; Tomar, Gaurav

    2016-01-01

    We consider scenarios in which the annihilation of self-conjugate spin-1 dark matter to a Standard Model fermion-antifermion final state is chirality suppressed, but where this suppression can be lifted by the emission of an additional photon via internal bremsstrahlung. We find that this scenario can only arise if the initial dark matter state is polarized, which can occur in the context of self-interacting dark matter. In particular, this is possible if the dark matter pair forms a bound st...

  6. Tagged photon facility at Centre for Advanced Technology, Indore: Possible scenarios

    Indian Academy of Sciences (India)

    L M Pant

    2006-05-01

    Photoproduction of in nuclear medium with the ELSA facility at Bonn is discussed in the context of medium modification of hadronic properties. Utilization of Indus-2 at CAT, Indore for producing tagged bremsstrahlung photons and laser backscattered photons has been explored with a comparison between the two techniques for producing tagged high energy photons for the first time in the country with emphasis on the ADSS programme to have a precise information of (; ) reactions.

  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. 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

  9. 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

  10. 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.

  11. 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...

  12. Producing and measuring setup of the twin photons beams obtained by SPDC phenomenon

    Science.gov (United States)

    Rusu, Al.; Rusu, L.

    2012-08-01

    The quantum photon pairs, generated by spontaneous parametric down conversion phenomenon, promise a lot of applications. That's why, a setup including both producing and measuring instrumentation for quantum correlated photon pairs was designed and manufactured in Romania, too. Some significant solved technical challenges are presented. The described measurements and results prove the ability to generate and measure entangled photon pairs. The setup is ready for experimental research and technological development activities.

  13. Vector dark matter annihilation with internal bremsstrahlung

    CERN Document Server

    Bambhaniya, Gulab; Marfatia, Danny; Nayak, Alekha C; Tomar, Gaurav

    2016-01-01

    We consider scenarios in which the annihilation of self-conjugate spin-1 dark matter to a Standard Model fermion-antifermion final state is chirality suppressed, but where this suppression can be lifted by the emission of an additional photon via internal bremsstrahlung. We find that this scenario can only arise if the initial dark matter state is polarized, which can occur in the context of self-interacting dark matter. In particular, this is possible if the dark matter pair forms a bound state that decays to its ground state before the constituents annihilate. We show that the shape of the resulting photon spectrum is the same as for self-conjugate spin-0 and spin-1/2 dark matter, but the normalization is less heavily suppressed in the limit of heavy mediators.

  14. 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.

  15. Transverse polarization of top quarks produced at a photon-photon collider

    CERN Document Server

    Bernreuther, W; McKellar, B H J

    1995-01-01

    At future .gamma..gamma. colliders copious production of tt.bar. pairs is possible. This would allow a detailed investigation of the interactions involving the top quark. We propose some orrelations which are sensitive to tt.bar. final state interactions and we compute the QCD and standard model Higgs boson contributions to these correlations. QCD induced transverse polarization of top quarks is found to be sizeable and measurable at a high-energy e.sup(+)e.sup(-) collider with an integrated luminosity of 10 ({\\rm fb})^{-1} which is converted into a photon collider by backscattering of laser photons.

  16. Coherent bremsstrahlung used for digital subtraction angiography

    Science.gov (United States)

    Überall, Herbert

    2007-05-01

    Digital subtraction angiography (DSA), also known as Dichromography, using synchrotron radiation beams has been developed at Stanford University (R. Hofstadter) and was subsequently taken over at the Brookhaven Synchrotron and later at Hamburg (HASYLAB) [see, e.g., W.R. Dix, Physik in unserer Zeit. 30 (1999) 160]. The imaging of coronary arteries is carried out with an iodine-based contrast agent which need not be injected into the heart. The radiation must be monochromatized and is applied above and below the K-edge of iodine (33.16 keV), with a subsequent digital subtraction of the two images. Monochromatization of the synchrotron radiation causes a loss of intensity of 10 -3. We propose instead the use of coherent bremsstrahlung [see, e.g., A.W. Saenz and H. Uberall, Phys. Rev. B25 (1982) 448] which is inherently monochromatic, furnishing a flux of 10 12 photon/sec. This requires a 10-20 MeV electron linac which can be obtained by many larger hospitals, eliminating the scheduling problems present at synchrotrons. The large, broad incoherent bremsstrahlung background underlying the monochromatic spike would lead to inadmissible overexposure of the patient. This problem can be solved with the use of Kumakhov's capillary optics [see e.g., S.B.Dabagov, Physics-Uspekhi 46 (2003) 1053]: the low-energy spiked radiation can be deflected towards the patient, while the higher energy incoherent background continues forward, avoiding the patient who is placed several meters from the source.

  17. Confirmation of a soft photon signal in excess of Q.E.D. expectations in $\\pi^- p$ interactions at 280 GeV/c

    CERN Document Server

    Belogianni, A; Brodbeck, T J; Evans, D; French, Bernard R; Jacholkowski, A; Kinson, J B; Kirk, A; Lenti, V; Loconsole, R A; Manzari, V; Minashvili, I A; Perepelitsa, V F; Rusakovitch, N A; Sonderegger, P; Spyropoulou-Stassinaki, M; Tchlatchidze, G A; Vasileiadis, G; Vichou, I; Villalobos Baillie, O

    1997-01-01

    Photons produced in \\pip interactions at 280 GeV/$c$ were detected by reconstructing the $e^+e^-$ pairs produced via the materialisation of the photons in a 1 mm thick lead sheet placed in front of the MWPC's of the OMEGA spectrometer at CERN. A soft photon signal $ 7.8\\pm 1.6$ times the Q.E.D. inner bremsstrahlung prediction was observed confirming the results of a previous experiment.

  18. 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.

  19. 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 ...

  20. Entangled Photon Pairs Produced by a Quantum Dot Strongly Coupled to a Microcavity

    Science.gov (United States)

    Johne, R.; Gippius, N. A.; Pavlovic, G.; Solnyshkov, D. D.; Shelykh, I. A.; Malpuech, G.

    2008-06-01

    We show theoretically that entangled photon pairs can be produced on demand through the biexciton decay of a quantum dot strongly coupled to the modes of a photonic crystal. The strong coupling allows us to tune the energy of the mixed exciton-photon (polariton) eigenmodes and to overcome the natural splitting existing between the exciton states coupled with different linear polarizations of light. Polariton states are moreover well protected against dephasing due to their lifetime of ten to a hundred times shorter than that of a bare exciton. Our analysis shows that the scheme proposed is achievable with the present technology.

  1. 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.

  2. 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

  3. Feasibility studies of the diffractive bremsstrahlung measurement at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Chwastowski, Janusz J.; Czekierda, Sabina; Staszewski, Rafal; Turnau, Jacek; Trzebinski, Maciej [The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow (Poland); Kycia, Radoslaw [Cracow University of Technology, Faculty of Physics, Mathematics and Computer Science, Cracow (Poland)

    2016-06-15

    Feasibility studies of an observation of the exclusive diffractive bremsstrahlung in proton-proton scattering at the centre of mass energy 13 TeV at the LHC are reported. These studies aim at the dedicated data taking periods with low instantaneous luminosity delivered by the LHC where the pile-up interactions can be neglected. A simplified approach to the photon and the scattered proton energy reconstruction is used. The background influence is discussed. (orig.)

  4. 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)

  5. 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)

  6. 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.

  7. 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

  8. The small contribution of molecular Bremsstrahlung radiation to the air-fluorescence yield of cosmic ray shower particles

    Science.gov (United States)

    Al Samarai, Imen; Deligny, Olivier; Rosado, Jaime

    2016-10-01

    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 3Πu electronic level of nitrogen molecules to the B 3Πg one amounting to Y[ 337 ] =(6.05 ± 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]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 means that out of ≃175 photons with wavelength between 330 and 400 nm detected by fluorescence detectors, one of them has been produced by molecular Bremsstrahlung radiation. Although small, this contribution is not negligible in regards to the total budget of systematic uncertainties when considering the absolute energy scale of fluorescence detectors.

  9. 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.

  10. 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

  11. 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.

  12. 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 ...

  13. External bremsstrahlung spectra excited by 204Tl β particles in thick targets

    Science.gov (United States)

    Powar, M. S.; Ahmad, Salim; Singh, M.

    1980-06-01

    Spectral distributions of bremsstrahlung produced by 204Tl β particles in thick targets of Perspex, aluminum, copper, tin, and lead have been measured in a sandwich geometry. The contributions of internal bremsstrahlung produced along with the β particles have been determined by magnetic field deflection as well as the Z=O extrapolation method. Experimental results agree with Bethe-Heitler Born-approximation theory, corrected for Coulomb-field effects for low- and medium-Z targets, but show 25% positive deviation for high-Z targets. Again it is found that the bremsstrahlung produced in low-Z targets like Perspex is comparable with internal bremsstrahlung, and the corrections for its contribution to measurements by earlier workers can lead to large uncertainties.

  14. Photon beams for radiosurgery produced by laser Compton backscattering from relativistic electrons

    Science.gov (United States)

    Girolami, B.; Larsson, B.; Preger, M.; Schaerf, C.; Stepanek, J.

    1996-09-01

    The frontal collisions of a laser beam with relativistic electrons result in Compton-backscattered photons. The energy of these photons is dependent on the laser and electron energy in the range from kilo-electron-volts to tens of mega-electron-volts. In a sufficiently narrow backscattering angle the photons are nearly monochromatic. Over the past 30 years there have been several attempts to produce photon beams by laser backscattering from relativistic electrons stored in magnetic ring structures. One aim is to produce photons in the high mega-electron-volt energy range with fluxes useful for nuclear physics research; another is to produce photons in the high kilo-electron-volt energy range, which would be useful for medical applications, such as coronary angiography or treatment of tumour. Our present interest is to investigate the possibility of using 34 keV to 10 MeV photon beams for applications in stereotactic functional radiosurgery. We foresee the possibility of neurosurgical operations through the intact skull with precise and effective destruction of deeply lying millimetre-sized targets with minimal effects on intervening structures, high reproducibility and good prediction of the results. Our paper presents: a Monte Carlo study of radiosurgery based on cross firing with 34 keV to 100 MeV photon beams and 200 and 580 MeV proton beams, a theoretical description of the kinematics of Compton backscattering and estimates of the backscattered photon flux from several combinations of laser cavities at Nd:YAG (1.17 eV) and images/0031-9155/41/9/002/img8.gif" ALIGN="TOP"/> (0.117 eV) laser energies and electron storage rings energies in the range 0.1 - 1.3 GeV. As examples, existing magnetic structures, such as the images/0031-9155/41/9/002/img9.gif" ALIGN="TOP"/> Accumulator in the lower energy range and the Trieste Synchrotron Light Source ELETTRA in the higher energy range have been utilized in the calculations. The Monte Carlo study has shown that

  15. 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.

  16. 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

  17. 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.

  18. Sensitivity analysis the influence of the average energy and FWHM of the initial fluence electrons in the determination of a spectrum of photons Bremsstrahlung of a linear accelerator; Analisis de sensibilidad de la influencia de la energia media y FWHM de la fluencia inicial de electrones en la determinacion de un espectro de fotones Bremsstrahlung de accelerador lineal

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-01

    The main objective of this work is to study the effects of the initial beam characteristics of electrons in the absorbed dose distribution calculated by Monte Carlo for a photons beam of 6 MeV emitted by a medical linear accelerator.

  19. 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...... in a pronounced directional dependence of the energy loss of bare heavy ions at extreme relativistic energies....

  20. Photonics

    CERN Document Server

    Andrews, David L

    2015-01-01

    Discusses the basic physical principles underlying Biomedical Photonics, spectroscopy and microscopy This volume discusses biomedical photonics, spectroscopy and microscopy, the basic physical principles underlying the technology and its applications. The topics discussed in this volume are: Biophotonics; Fluorescence and Phosphorescence; Medical Photonics; Microscopy; Nonlinear Optics; Ophthalmic Technology; Optical Tomography; Optofluidics; Photodynamic Therapy; Image Processing; Imaging Systems; Sensors; Single Molecule Detection; Futurology in Photonics. Comprehensive and accessible cov

  1. Photonics

    CERN Document Server

    Andrews, David L

    2015-01-01

    Discusses the basic physical principles underlying thescience and technology of nanophotonics, its materials andstructures This volume presents nanophotonic structures and Materials.Nanophotonics is photonic science and technology that utilizeslight/matter interactions on the nanoscale where researchers arediscovering new phenomena and developing techniques that go wellbeyond what is possible with conventional photonics andelectronics.The topics discussed in this volume are: CavityPhotonics; Cold Atoms and Bose-Einstein Condensates; Displays;E-paper; Graphene; Integrated Photonics; Liquid Cry

  2. Photonics

    CERN Document Server

    Andrews, David L

    2015-01-01

    This book covers modern photonics accessibly and discusses the basic physical principles underlying all the applications and technology of photonicsThis volume covers the basic physical principles underlying the technology and all applications of photonics from statistical optics to quantum optics. The topics discussed in this volume are: Photons in perspective; Coherence and Statistical Optics; Complex Light and Singular Optics; Electrodynamics of Dielectric Media; Fast and slow Light; Holography; Multiphoton Processes; Optical Angular Momentum; Optical Forces, Trapping and Manipulation; Pol

  3. Photonics

    CERN Document Server

    Andrews, David L

    2015-01-01

    Discusses the basic physical principles underlying the technology instrumentation of photonics This volume discusses photonics technology and instrumentation. The topics discussed in this volume are: Communication Networks; Data Buffers; Defense and Security Applications; Detectors; Fiber Optics and Amplifiers; Green Photonics; Instrumentation and Metrology; Interferometers; Light-Harvesting Materials; Logic Devices; Optical Communications; Remote Sensing; Solar Energy; Solid-State Lighting; Wavelength Conversion Comprehensive and accessible coverage of the whole of modern photonics Emphas

  4. Parameter Estimation with Entangled Photons Produced by Parametric Down-Conversion

    International Nuclear Information System (INIS)

    We explore the advantages offered by twin light beams produced in parametric down-conversion for precision measurement. The symmetry of these bipartite quantum states, even under losses, suggests that monitoring correlations between the divergent beams permits a high-precision inference of any symmetry-breaking effect, e.g., fiber birefringence. We show that the quantity of entanglement is not the key feature for such an instrument. In a lossless setting, scaling of precision at the ultimate ''Heisenberg'' limit is possible with photon counting alone. Even as photon losses approach 100% the precision is shot-noise limited, and we identify the crossover point between quantum and classical precision as a function of detected flux. The predicted hypersensitivity is demonstrated with a Bayesian simulation.

  5. Parameter estimation with entangled photons produced by parametric down-conversion.

    Science.gov (United States)

    Cable, Hugo; Durkin, Gabriel A

    2010-07-01

    We explore the advantages offered by twin light beams produced in parametric down-conversion for precision measurement. The symmetry of these bipartite quantum states, even under losses, suggests that monitoring correlations between the divergent beams permits a high-precision inference of any symmetry-breaking effect, e.g., fiber birefringence. We show that the quantity of entanglement is not the key feature for such an instrument. In a lossless setting, scaling of precision at the ultimate "Heisenberg" limit is possible with photon counting alone. Even as photon losses approach 100% the precision is shot-noise limited, and we identify the crossover point between quantum and classical precision as a function of detected flux. The predicted hypersensitivity is demonstrated with a Bayesian simulation.

  6. Parameter Estimation with Entangled Photons Produced by Parametric Down-Conversion

    Science.gov (United States)

    Cable, Hugo; Durkin, Gabriel A.

    2010-01-01

    We explore the advantages offered by twin light beams produced in parametric down-conversion for precision measurement. The symmetry of these bipartite quantum states, even under losses, suggests that monitoring correlations between the divergent beams permits a high-precision inference of any symmetry-breaking effect, e.g., fiber birefringence. We show that the quantity of entanglement is not the key feature for such an instrument. In a lossless setting, scaling of precision at the ultimate "Heisenberg" limit is possible with photon counting alone. Even as photon losses approach 100% the precision is shot-noise limited, and we identify the crossover point between quantum and classical precision as a function of detected flux. The predicted hypersensitivity is demonstrated with a Bayesian simulation.

  7. 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

  8. Shielding implications for secondary neutrons and photons produced within the patient during IMPT

    Energy Technology Data Exchange (ETDEWEB)

    DeMarco, J.; Kupelian, P.; Santhanam, A.; Low, D. [UCLA Department of Radiation Oncology, University of California Los Angeles, Los Angeles, California 90095 (United States)

    2013-07-15

    Purpose: Intensity modulated proton therapy (IMPT) uses a combination of computer controlled spot scanning and spot-weight optimized planning to irradiate the tumor volume uniformly. In contrast to passive scattering systems, secondary neutrons and photons produced from inelastic proton interactions within the patient represent the major source of emitted radiation during IMPT delivery. Various published studies evaluated the shielding considerations for passive scattering systems but did not directly address secondary neutron production from IMPT and the ambient dose equivalent on surrounding occupational and nonoccupational work areas. Thus, the purpose of this study was to utilize Monte Carlo simulations to evaluate the energy and angular distributions of secondary neutrons and photons following inelastic proton interactions within a tissue-equivalent phantom for incident proton spot energies between 70 and 250 MeV.Methods: Monte Carlo simulation methods were used to calculate the ambient dose equivalent of secondary neutrons and photons produced from inelastic proton interactions in a tissue-equivalent phantom. The angular distribution of emitted neutrons and photons were scored as a function of incident proton energy throughout a spherical annulus at 1, 2, 3, 4, and 5 m from the phantom center. Appropriate dose equivalent conversion factors were applied to estimate the total ambient dose equivalent from secondary neutrons and photons.Results: A reference distance of 1 m from the center of the patient was used to evaluate the mean energy distribution of secondary neutrons and photons and the resulting ambient dose equivalent. For an incident proton spot energy of 250 MeV, the total ambient dose equivalent (3.6 Multiplication-Sign 10{sup -3} mSv per proton Gy) was greatest along the direction of the incident proton spot (0 Degree-Sign -10 Degree-Sign ) with a mean secondary neutron energy of 71.3 MeV. The dose equivalent decreased by a factor of 5 in the

  9. Shielding implications for secondary neutrons and photons produced within the patient during IMPT

    International Nuclear Information System (INIS)

    Purpose: Intensity modulated proton therapy (IMPT) uses a combination of computer controlled spot scanning and spot-weight optimized planning to irradiate the tumor volume uniformly. In contrast to passive scattering systems, secondary neutrons and photons produced from inelastic proton interactions within the patient represent the major source of emitted radiation during IMPT delivery. Various published studies evaluated the shielding considerations for passive scattering systems but did not directly address secondary neutron production from IMPT and the ambient dose equivalent on surrounding occupational and nonoccupational work areas. Thus, the purpose of this study was to utilize Monte Carlo simulations to evaluate the energy and angular distributions of secondary neutrons and photons following inelastic proton interactions within a tissue-equivalent phantom for incident proton spot energies between 70 and 250 MeV.Methods: Monte Carlo simulation methods were used to calculate the ambient dose equivalent of secondary neutrons and photons produced from inelastic proton interactions in a tissue-equivalent phantom. The angular distribution of emitted neutrons and photons were scored as a function of incident proton energy throughout a spherical annulus at 1, 2, 3, 4, and 5 m from the phantom center. Appropriate dose equivalent conversion factors were applied to estimate the total ambient dose equivalent from secondary neutrons and photons.Results: A reference distance of 1 m from the center of the patient was used to evaluate the mean energy distribution of secondary neutrons and photons and the resulting ambient dose equivalent. For an incident proton spot energy of 250 MeV, the total ambient dose equivalent (3.6 × 10−3 mSv per proton Gy) was greatest along the direction of the incident proton spot (0°–10°) with a mean secondary neutron energy of 71.3 MeV. The dose equivalent decreased by a factor of 5 in the backward direction (170°–180°) with a mean

  10. 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.

  11. 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.

  12. 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.

  13. Sensitivity analysis of the influence of the medium energy and initial fluence FWHM of electron determining a Bremsstrahlung photon spectrum of a linear accelerator; Analisis de sensibilidad de la influencia de la energia media FWHM de la influencia inicial de electrones en la determinacion de un espectro de fotones Bremsstrahlung de un acelerador lineal

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-11-01

    A correct dose calculation in patient under radiotherapy treatments requires and accurate description of the radiation source. The main goal of the present work is to study the effects of initial electron beam characteristics on Monte Carlo calculated absorbed dose distribution for a 6 MeV linac photon beam. To that, we propose a methodology to determine the initial electron fluence before hitting the accelerator target for an Elektra Precis a medical linear accelerator. The method used for the electron radiation source description is based on a Software for Uncertainty and Sensitivity Analysis (SUSA) and Monte Carlo simulations using the MCNP5 transport code. This electron spectrum has been validated by means of comparison of its resulting depth dose curve in a water cube with experimental data being the mean difference below the 1%. (Author)

  14. 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)

  15. Enhancing extreme ultraviolet photons emission in laser produced plasmas for advanced lithography

    International Nuclear Information System (INIS)

    Current challenges in the development of efficient laser produced plasma sources for the next generation extreme ultraviolet lithography (EUVL) are increasing EUV power and maximizing lifetime and therefore, reducing cost of devices. Mass-limited targets such as small tin droplets are considered among the best choices for cleaner operation of the optical system because of lower mass of atomic debris produced by the laser beam. The small diameter of droplets, however, decreases the conversion efficiency (CE) of EUV photons emission, especially in the case of CO2 laser, where laser wavelength has high reflectivity from the tin surface. We investigated ways of improving CE in mass-limited targets. We considered in our modeling various possible target phases and lasers configurations: from solid/liquid droplets subjected to laser beam energy with different intensities and laser wavelength to dual-beam lasers, i.e., a pre-pulse followed by a main pulse with adjusted delay time in between. We studied the dependence of vapor expansion rate, which can be produced as a result of droplet heating by pre-pulse laser energy, on target configuration, size, and laser beam parameters. As a consequence, we studied the influence of these conditions and parameters on the CE and debris mass accumulation. For better understanding and more accurate modeling of all physical processes occurred during various phases of laser beam/target interactions, plasma plume formation and evolution, EUV photons emission and collection, we have implemented in our heights package state-of-the art models and methods, verified, and benchmarked against laboratory experiments in our CMUXE center as well as various worldwide experimental results.

  16. Channeling and coherent bremsstrahlung effects for relativistic positrons and electrons. [16 to 28 MeV, orientation

    Energy Technology Data Exchange (ETDEWEB)

    Walker, R. L.

    1976-03-22

    Channeling of positrons in single crystals of silicon was observed in transmission and scattering measurements for incident energies from 16 to 28 MeV. In addition, the spectral dependence upon crystal orientation of the forward coherent bremsstrahlung produced by beams of 28-MeV positrons and electrons incident upon a 5 ..mu..m thick single crystal of silicon was measured with a NaI photon spectrometer. Effects of channeling and perhaps of the nonvalidity of the first Born approximation were observed for beam directions near the (111) axis of the crystal, and coherent peaks near 0.5 MeV were observed for a compound interference direction, in agreement with first-order theoretical calculations. 32 fig.

  17. Study of charmonia in four-meson final states produced in two-photon collisions

    International Nuclear Information System (INIS)

    We report measurements of charmonia produced in two-photon collisions and decaying to four-meson final states, where the meson is either a charged pion or a charged kaon. The analysis is based on a 395 fb-1 data sample accumulated with the Belle detector at the KEKB electron-positron collider. We observe signals for the three C-even charmonia ηc(1S), χc0(1P) and χc2(1P) in the π+π-π+π-, K+K-π+π- and K+K-K+K- decay modes. No clear signals for ηc(2S) production are found in these decay modes. We have also studied resonant structures in charmonium decays to two-body intermediate meson resonances. We report the products of the two-photon decay width and the branching fractions, ΓγγB, for each of the charmonium decay modes. (orig.)

  18. Study of charmonia in four-meson final states produced in two-photon collisions

    CERN Document Server

    Uehara, S; Aihara, H; Aulchenko, V; Aushev, T; Bakich, A M; Balagura, V; Barberio, E; Bay, A; Belous, K S; Bitenc, U; Bondar, A; Bozek, A; Bracko, M; Brodzicka, J; Browder, T E; Chang, P; Chao, Y; Chen, A; Chen, K F; Chen, W T; Cheon, B G; Cho, I S; Choi, Y; Choi, Y K; Dalseno, J; Dash, M; Drutskoy, A; Eidelman, S; Epifanov, D; Fratina, S; Gabyshev, N; Gokhroo, G; Golob, B; Ha, H; Haba, J; Hayasaka, K; Hayashii, H; Hazumi, M; Heffernan, D; Hokuue, T; Hoshi, Y; Hou, W S; Hyun, H J; Iijima, T; Ikado, K; Inami, K; Ishikawa, A; Itoh, R; Iwasaki, M; Iwasaki, Y; Kah, D H; Kaji, H; Kang, J H; Kawai, H; Kawasaki, T; Kichimi, H; Kim, H O; Kim, S K; Kim, Y J; Korpar, S; Krizan, P; Krokovny, P; Kumar, R; Kuo, C C; Kuzmin, A; Kwon, Y J; Lee, J S; Lee, M J; Lee, S E; Lesiak, T; Li, J; Limosani, A; Lin, S W; Liu, Y; Liventsev, D; Mandl, F; Matsumoto, T; Matyja, A; McOnie, S; Medvedeva, T; Miyake, H; Miyata, H; Miyazaki, Y; Mizuk, R; Nagasaka, Y; Nakano, E; Nakao, M; Nakazawa, H; Natkaniec, Z; Nishida, S; Nitoh, O; Ogawa, S; Ohshima, T; Okuno, S; Olsen, S L; Onuki, Y; Ozaki, H; Pakhlov, P; Pakhlova, G; Palka, H; Park, C W; Park, H; Peak, L S; Pestotnik, R; Piilonen, L E; Sahoo, H; Sakai, Y; Schneider, O; Seidl, R; Senyo, K; Sevior, M E; Shapkin, M; Shibuya, H; Shiu, J G; Shwartz, B; Singh, J B; Sokolov, A; Somov, A; Soni, N; Stanic, S; Staric, M; Stöck, H; Sumiyoshi, T; Takasaki, F; Tamai, K; Tanaka, M; Taylor, G N; Teramoto, Y; Tian, X C; Tikhomirov, I; Tsuboyama, T; Unno, Y; Uno, S; Urquijo, P; Usov, Yu; Varner, G; Vervink, K; Villa, S; Vinokurova, A; Wang, C H; Wang, P; Watanabe, Y; Won, E; Yabsley, B D; Yamaguchi, A; Yamashita, Y; Yuan, C Z; Zhang, C C; Zhang, Z P; Zhilich, V; Zupanc, A

    2008-01-01

    We report measurements of charmonia produced in two-photon collisions and decaying to four-meson final states, where the meson is either a charged pion or a charged kaon. The analysis is based on a 395fb^{-1} data sample accumulated with the Belle detector at the KEKB electron-positron collider. We observe signals for the three C-even charmonia eta_c(1S), chi_{c0}(1P) and chi_{c2}(1P) in the pi^+pi^-pi^+pi^-, K^+K^-pi^+pi^- and K^+K^-K^+K^- decay modes. No clear signals for eta_c(2S) production are found in these decay modes. We have also studied resonant structures in charmonium decays to two-body intermediate meson resonances. We report the products of the two-photon decay width and the branching fractions, Gamma_{gamma gamma}B, for each of the charmonium decay modes.

  19. 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.

  20. Candidate for a W->μν decay, with the W boson produced in association with a photon

    CERN Multimedia

    ATLAS, Experiment

    2014-01-01

    Candidate for a W->μν decay, with the W boson produced in association with a photon, collected on 28 October 2010. The transverse mass of the W boson is 65 GeV. The muon and the photon are well isolated. Further event properties: PT(mu) = 38 GeV PT(gamma) = 39 GeV ETmiss = 30 GeV

  1. Collimator and energy window optimization for ⁹⁰Y bremsstrahlung SPECT imaging: A SIMIND Monte Carlo study.

    Science.gov (United States)

    Roshan, Hoda Rezaei; Mahmoudian, Babak; Gharepapagh, Esmaeil; Azarm, Ahmadreza; Islamian, Jalil Pirayesh

    2016-02-01

    Treatment efficacy of radioembolization using Yttrium-90 ((90)Y) microspheres is assessed by the (90)Y bremsstrahlung single photon emission computed tomography (SPECT) imaging following radioembolization. The radioisotopic image has the potential of providing reliable activity map of (90)Y microspheres distribution. One of the main reasons of the poor image quality in (90)Y bremsstrahlung SPECT imaging is the continuous and broad energy spectrum of the related bremsstrahlung photons. Furthermore, collimator geometry plays an impressive role in the spatial resolution, sensitivity and image contrast. Due to the relatively poor quality of the (90)Y bremsstrahlung SPECT images, we intend to optimize the medium-energy (ME) parallel-hole collimator and energy window. The Siemens e.cam gamma camera equipped with a ME collimator and a voxelized phantom was simulated by the SImulating Medical Imaging Nuclear Detectors (SIMIND) program. We used the SIMIND Monte Carlo program to generate the (90)Y bremsstrahlung SPECT projection of the digital Jaszczak phantom. The phantom consist of the six hot spheres ranging from 9.5 to 31.8mm in diameter, which are used to evaluate the image contrast. In order to assess the effect of the energy window on the image contrast, three energy windows ranging from 60 to 160 KeV, 160 to 400 KeV, and 60 to 400 KeV were set on a (90)Y bremsstrahlung spectrum. As well, the effect of the hole diameter of a ME collimator on the image contrast and bremsstrahlung spectrum were investigated. For the fixed collimator and septa thickness values (3.28 cm and 1.14 mm, respectively), a hole diameter range (2.35-3.3mm) was chosen based on the appropriate balance between the spatial resolution and sensitivity. The optimal energy window for (90)Y bremsstrahlung SPECT imaging was extended energy window from 60 to 400 KeV. Besides, The optimal value of the hole diameter of ME collimator was obtained 3.3mm. Geometry of the ME parallel-hole collimator and energy

  2. Experimental Demonstration of a Hybrid-Quantum-Emitter Producing Individual Entangled Photon Pairs in the Telecom Band

    Science.gov (United States)

    Chen, Geng; Zou, Yang; Zhang, Wen-Hao; Zhang, Zi-Huai; Zhou, Zong-Quan; He, De-Yong; Tang, Jian-Shun; Liu, Bi-Heng; Yu, Ying; Zha, Guo-Wei; Ni, Hai-Qiao; Niu, Zhi-Chuan; Han, Yong-Jian; Li, Chuan-Feng; Guo, Guang-Can

    2016-05-01

    Quantum emitters generating individual entangled photon pairs (IEPP) have significant fundamental advantages over schemes that suffer from multiple photon emission, or schemes that require post-selection techniques or the use of photon-number discriminating detectors. Quantum dots embedded within nanowires (QD-NWs) represent one of the most promising candidate for quantum emitters that provide a high collection efficiency of photons. However, a quantum emitter that generates IEPP in the telecom band is still an issue demanding a prompt solution. Here, we demonstrate in principle that IEPPs in the telecom band can be created by combining a single QD-NW and a nonlinear crystal waveguide. The QD-NW system serves as the single photon source, and the emitted visible single photons are split into IEPPs at approximately 1.55 μm through the process of spontaneous parametric down conversion (SPDC) in a periodically poled lithium niobate (PPLN) waveguide. The compatibility of the QD-PPLN interface is the determinant factor in constructing this novel hybrid-quantum-emitter (HQE). Benefiting from the desirable optical properties of QD-NWs and the extremely high nonlinear conversion efficiency of PPLN waveguides, we successfully generate IEPPs in the telecom band with the polarization degree of freedom. The entanglement of the generated photon pairs is confirmed by the entanglement witness. Our experiment paves the way to producing HQEs inheriting the advantages of multiple systems.

  3. Photon Production Within Storage Capsules

    CERN Document Server

    Rittmann, P D

    2003-01-01

    This report provides tables and electronic worksheets that list the photon production rate within SrF2 and CsC1 storage capsules, particularly the continuous spectrum of bremsstrahlung photons from the slowing down of the emitted electrons (BREMCALC).

  4. 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.

  5. 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.

  6. 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

  7. 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...

  8. 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...

  9. 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.

  10. 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)

  11. 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)

  12. Producing ultrashort Terahertz to UV photons at high repetition rates for research into materials

    Energy Technology Data Exchange (ETDEWEB)

    G. R. Neil; C. Behre; S. V. Benson; G. Biallas; J. Boyce; L.A. Dillon-Townes; D. Douglas; H. F. Dylla; R. Evans; A. Grippo; D. Gruber; J. Gubeli; C. Hernandez-Garcia; K. Jordan; M. J. Kelley; L. Merminga; J. Mammosser; N. Nishimori; J. Preble; R. Rimmer; Michelle D. Shinn; T. Siggins; R. Walker; G. P. Williams; and S. Zhang

    2005-11-01

    A new THz/IR/UV photon source at Jefferson Lab is the first of a new generation of light sources based on a Energy-Recovered, (superconducting) Linac (ERL). The machine has a 160 MeV electron beam and an average current of 10 mA in 75 MHz repetition rate hundred femtosecond bunches. These electron bunches pass through a magnetic chicane and therefore emit synchrotron radiation. For wavelengths longer than the electron bunch the electrons radiate coherently a broadband THz {approx} half cycle pulse whose average brightness is > 5 orders of magnitude higher than synchrotron IR sources. Previous measurements showed 20 W of average power extracted[1]. The new facility offers simultaneous synchrotron light from the visible through the FIR along with broadband THz production of 100 fs pulses with >200 W of average power (see G. P. Williams, this conference). The FELs also provide record-breaking laser power [2]: up to 10 kW of average power in the IR from 1 to 14 microns in 400 fs pulses at up to 74.85 MHz repetition rates and soon will produce similar pulses of 300-1000 nm light at up to 3 kW of average power from the UV FEL. These ultrashort pulses are ideal for maximizing the interaction with material surfaces. The optical beams are Gaussian with nearly perfect beam quality. See www.jlab.org/FEL for details of the operating characteristics; a wide variety of pulse train configurations are feasible from 10 microseconds long at high repetition rates to continuous operation. The THz and IR system has been commissioned. The UV system is to follow in 2005. The light is transported to user laboratories for basic and applied research. Additional lasers synchronized to the FEL are also available. Past activities have included production of carbon nanotubes, studies of vibrational relaxation of interstitial hydrogen in silicon, pulsed laser vapor deposition, nitriding of metals, and energy flow in proteins. This paper will present the status of the system and discuss some of

  13. 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.

  14. 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.

  15. 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...

  16. 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...

  17. A Study of the use of a Crystal as a `Quarter-Wave Plate' to Produce High Energy Circularly Polarized Photons

    CERN Multimedia

    Kononets, I

    2002-01-01

    %NA59 %title\\\\ \\\\We present a proposal to study the use of a crystal as a `quarter-wave plate' to produce high energy circularly polarized photons, starting from unpolarized electrons. The intention is to generate linearly polarized photons by letting electrons pass a crystalline target, where they interact coherently with the lattice nuclei. The photon polarization is subsequently turned into circular polarization after passing another crystal, which acts as a `quarter-wave plate'.

  18. Nuclear Resonance Fluorescence Using Different Photon Sources

    International Nuclear Information System (INIS)

    Nuclear resonance fluorescence (NRF) is a photon-based active interrogation approach that provides isotope-specific signatures that can be used to detect and characterize samples. As NRF systems are designed to address specific applications, an obvious first question to address is the type of photon source to be employed for the application. Our collaboration has conducted a series of NRF measurements using different photon sources to begin to examine this issue. The measurements were designed to be as similar as possible to facilitate a straightforward comparison of the different sources. Measurements were conducted with a high-duty factor electron accelerator using bremsstrahlung photons, with a pulsed linear accelerator using bremsstrahlung photons, and with a narrow bandwidth photon source using Compton backscattered photons. We present our observations on the advantages and disadvantages of each photon source type. Issues such as signal rate, the signal-to-noise ratio, and absorbed dose are discussed

  19. Three-photon process for producing a degenerate gas of metastable alkaline-earth-metal atoms

    Science.gov (United States)

    Barker, D. S.; Pisenti, N. C.; Reschovsky, B. J.; Campbell, G. K.

    2016-05-01

    We present a method for creating a quantum degenerate gas of metastable alkaline-earth-metal atoms. This has yet to be achieved due to inelastic collisions that limit evaporative cooling in the metastable states. Quantum degenerate samples prepared in the 1S0 ground state can be rapidly transferred to either the 3P2 or 3P0 state via a coherent three-photon process. Numerical integration of the density-matrix evolution for the fine structure of bosonic alkaline-earth-metal atoms shows that transfer efficiencies of ≃90 % can be achieved with experimentally feasible laser parameters in both Sr and Yb. Importantly, the three-photon process can be set up such that it imparts no net momentum to the degenerate gas during the excitation, which will allow for studies of metastable samples outside the Lamb-Dicke regime. We discuss several experimental challenges to successfully realizing our scheme, including the minimization of differential ac Stark shifts between the four states connected by the three-photon transition.

  20. A 3-photon process for producing degenerate gases of metastable alkaline-earth atoms

    Science.gov (United States)

    Barker, Daniel S.; Pisenti, Neal C.; Reschovsky, Benjamin J.; Campbell, Gretchen K.

    2016-05-01

    We present a method for creating quantum degenerate gases of metastable alkaline-earth atoms. A degenerate gas in any of the 3 P metastable states has not previously been obtained due to large inelastic collision rates, which are unfavorable for evaporative cooling. Samples prepared in the 1S0 ground state can be rapidly transferred to either the 3P2 or 3P0 state via a coherent 3-photon process. Numerical integration of the density matrix evolution for the fine structure of bosonic alkaline-earth atoms shows that transfer efficiencies of ~= 90 % can be achieved with experimentally feasible laser parameters in both Sr and Yb. Importantly, the 3-photon process does not impart momentum to the degenerate gas during excitation, which allows studies of these metastable samples outside the Lamb-Dicke regime. We discuss several experimental challenges to the successful realization of our scheme, including the minimization of differential AC Stark shifts between the four states connected by the 3-photon transition.

  1. Thermal Bremsstrahlung Radiation in a Two-Temperature Plasma

    Institute of Scientific and Technical Information of China (English)

    Bin Luo; Shuang-Nan Zhang

    2004-01-01

    In normal one-temperature plasma the motion of ions is usually neglected when calculating the Bremsstrahlung radiation of the plasma.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:we find the two-temperature correction to the total Bremsstrahlung radiation for ADAF is negligible.

  2. Surface photon emissivity of bare strange stars

    OpenAIRE

    Cheng, KS; Harko, T.

    2003-01-01

    We consider the bremsstrahlung surface photon emissivity of strange quark stars, by systematically taking into account the effects of the multiple scatterings of highly relativistic quarks in a dense medium (the Landau-Pomeranchuk-Migdal effect). Because of interference between amplitudes of nearby interactions, the bremsstrahlung emissivity from a strange star surface is suppressed for frequencies smaller than a critical frequency. The range of the suppressed frequencies is a function of the...

  3. 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

  4. 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...

  5. 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

  6. QED processes in peripheral kinematics at polarized photon-photon and photon-electron colliders

    CERN Document Server

    Bakmaev, S; Galynsky, M V; Kuraev, E A

    2004-01-01

    For experiments on planned electron-photon and photon-photon colliders with detecting the small angles scattered particles the calibration QED processes cross sections are calculated. These processes describe the creation of two jets moving sufficiently close to the beam axes directions. The jets containing two and three particles including charged leptons, photons and pseudoscalar mesons are considered explicitly. Considering the pair production subprocesses we take into account both bremsstrahlung and double photon mechanisms. The obtained results are suitable for further numerical calculations.

  7. 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

  8. 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

  9. 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

  10. 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)

  11. 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.

  12. 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.

  13. 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

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

    Science.gov (United States)

    Selim, F. A.; Wells, D. P.; Harmon, J. F.; Kwofie, J.; Spaulding, R.; Erickson, G.; Roney, T.

    2002-12-01

    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 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 thick. Bremsstrahlung beams above neutron emission threshold, from a 20 MeV pulsed electron linac, have also been used to produce residual nuclei in excited states via photonuclear reactions allowing the detection of heavy elements via their characteristic γ-rays. This can be developed into a technique to trace some heavy metals in large rocks and soils for environmental applications.

  15. Quantum Phase Estimation with Entangled Photons produced by Parametric Down Conversion

    OpenAIRE

    Cable, Hugo; Durkin, Gabriel A.

    2009-01-01

    We explore the advantages offered by twin light beams produced in parametric down-conversion for precision measurement. The symmetry of these bipartite quantum states, even under losses, suggests that monitoring correlations between the divergent beams permits a high-precision inference of any symmetry-breaking effect, e.g. fiber birefringence. We show that the quantity of entanglement is not the key feature for such an instrument. In a lossless setting, scaling of precision at the ultimate `...

  16. 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).

  17. Electron accelerator-based production of molybdenum-99: Bremsstrahlung and photoneutron generation from molybdenum vs. tungsten

    Science.gov (United States)

    Tsechanski, A.; Bielajew, A. F.; Archambault, J. P.; Mainegra-Hing, E.

    2016-01-01

    A new "one-stage" approach for production of 99Mo and other radioisotopes by means of an electron linear accelerator is described. It is based on using a molybdenum target both as a bremsstrahlung converter and as a radioisotope producing target for the production of 99Mo via the photoneutron reaction 100Mo(γ,n)99Mo. Bremsstrahlung characteristics, such as bremsstrahlung efficiency, angular distribution, and energy deposition for molybdenum targets were obtained by means of the EGSnrc Monte Carlo simulation code system. As a result of our simulations, it is concluded that a 60 MeV electron beam incident on a thick Mo target will have greater bremsstrahlung efficiency than the same thickness (in units of r0) W target, for target thickness z > 1.84r0, where r0 is the electron range. A 50 MeV electron beam incident on a Mo target will result in greater bremsstrahlung efficiency than the same thickness W target (in units of r0) for target thickness case: z ⩾ 2.0r0. It is shown for the one-stage approach with thicknesses of (1.84-2.0)r0, that the 99Mo-production bremsstrahlung efficiency of a molybdenum target is greater by ∼100% at 30 MeV and by ∼70% at 60 MeV compared to the values for tungsten of the same thickness (in units of the appropriate r0) in the traditional two-stage approach (W converter and separate 99Mo producing target). This advantage of the one-stage approach arises from the fact that the bremsstrahlung produced is attenuated only once from attenuation in the molybdenum converter/target. In the traditional, two-stage approach, the bremsstrahlung generated in the W-converter/target is attenuated both in the converter in the 99Mo-producing molybdenum target. The photoneutron production yield of molybdenum and tantalum (as a substitute for tungsten) target was calculated by means of the MCNP5 transport code. On the basis of these data, the specific activity for the one-stage approach of three enriched 100Mo-targets of a 2 cm diameter and

  18. 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

  19. 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

  20. Thick-target external-bremsstrahlung spectra of 147Pm and 35S β rays

    Science.gov (United States)

    Dhaliwal, A. S.; Powar, M. S.; Singh, M.

    1993-08-01

    External-bremsstrahlung spectra excited by soft β particles of 147Pm (Emaxβ=225 keV) and 35S (Emaxβ=167 keV) in targets of Al, Cu, Sn, and Pb have been studied. The experimental and theoretical results are compared in terms of the number of photons of energy k per m0c2 per unit photon yield to exclude the uncertainty in the source strength measurement and overcome the inherent inadequacy of the normalization procedure used by earlier workers. The results of present measurements for medium- and high-Z elements show better agreement with the theory of Tseng and Pratt [Phys. Rev. A 3, 1714 (1976)] than with Elwert's corrections [Ann. Phys. (N.Y.) 34, 78 (1939)] to the Bethe-Heitler theory [Proc. R. Soc. London Ser. A 14, 83 (1934)], particularly at the higher-energy ends. However, for low-Z elements, both theories are found to be adequate.

  1. 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)

  2. 42 MeV bremsstrahlung spectrum analysis by a photoactivation method

    Energy Technology Data Exchange (ETDEWEB)

    Calzado, A.; Vano, E.; Delgado, V.; Gonzalez, L. (Universidad Complutense de Madrid (Spain). Catedra de Fisica Medica; Junta de Energia Nuclear, Madrid (Spain). Inst. de Estudios Nucleares)

    1984-08-01

    The evaluation of 42 MeV, bremsstrahlung spectra from a clinical betatron by using the photoactivation method is described. Photonuclear reactions, mainly of the (..gamma.., n) type, are used as activation detectors. After measurements of photon-induced activities from residual nuclei are performed, the spectral distribution of photons is evaluated by solving the unfolding problem. The latter is carried out through the use of two independent methods, orthonormal expansion and Monte Carlo. In both cases prior conditions to the solution are imposed. Spectra evaluated by both methods and making use of two different size flattening filters are presented. An empirical method to estimate the 'effective' thickness of the Pt target is described.

  3. 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...

  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. Comparison of Yields of neutron rich nuclei in Proton and Photon induced $^{238}$U fission

    CERN Document Server

    Khan, F A; Basu, D N; Farooq, M; Chakrabarti, Alok

    2016-01-01

    A comparative study of fission of actinides specially $^{238}$U, by proton and bremsstrahlung photon is performed. Relative mass distribution of $^{238}$U fission fragments have been explored theoretically for both proton and photon induced fission. The integrated yield along with charge distribution of the products are calculated to find out the neutron richness in comparison to the nuclei produced by r-process in nucleosynthesis. Some r-process nuclei in intermediate mass range for symmetric fission mode are found to be produced almost two order of magnitude more for proton induced fission than photofission, although rest of the neutron rich nuclei in the asymmetric mode are produced in comparable proportion for both the processes.

  6. 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

  7. 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.

  8. Photon Collider Physics with Real Photon Beams

    Energy Technology Data Exchange (ETDEWEB)

    Gronberg, J; Asztalos, S

    2005-11-03

    Photon-photon interactions have been an important probe into fundamental particle physics. Until recently, the only way to produce photon-photon collisions was parasitically in the collision of charged particles. Recent advances in short-pulse laser technology have made it possible to consider producing high intensity, tightly focused beams of real photons through Compton scattering. A linear e{sup +}e{sup -} collider could thus be transformed into a photon-photon collider with the addition of high power lasers. In this paper they show that it is possible to make a competitive photon-photon collider experiment using the currently mothballed Stanford Linear Collider. This would produce photon-photon collisions in the GeV energy range which would allow the discovery and study of exotic heavy mesons with spin states of zero and two.

  9. Preliminary Report on the Evaluation of an Electron-Positron Collider as a source of Monoenergetic Photons

    Energy Technology Data Exchange (ETDEWEB)

    Fast, James E.; Campbell, Luke W.

    2009-11-30

    Abstract Active interrogation methods are being investigated to detect shielded special nuclear material (SNM). These approaches utilize either neutron or photon beams to excite the SNM in concert with either neutron or gamma ray detectors to observe the stimulated emissions. The two primary methodologies with photon beams are photofission and nuclear resonance florescence (NRF). Photofission requires photons energies of 7-10 MeV while NRF requires photon energies around 2 MeV. For both techniques, photons that are not in the appropriate energy band, e.g. the low energy tail of a Bremsstrahlung photon beam, contribute unwanted additional radiation dose to cargo. Typically less than 10% of the photons are in the usable energy band. The additional photon production generates a commensurate amount of additional radiation dose in the source and target areas, impacting shielding requirements and/or dose to operators and equipment and at the expense of a similar increase in power consumption. Hence it is highly desirable to produce narrow energy (“monoenergetic”) photon beams with tunable energy in the range of ~2-20 MeV.

  10. 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.

  11. 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.

  12. 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.

  13. 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)

  14. 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...

  15. Bremsstrahlung signatures of dark matter annihilation in the Sun

    CERN Document Server

    Fukushima, Keita; Kumar, Jason; Marfatia, Danny

    2012-01-01

    The nonrelativistic annihilation of Majorana dark matter in the Sun to a pair of light fermions is chirality-suppressed. Annihilation to 3-body final states $\\ell^+f^-V$, where $V=W,Z,\\gamma$, and $\\ell$ and $f$ are light fermions (that may be the same), becomes dominant since bremsstrahlung relaxes the chirality suppression. We evaluate the neutrino spectra at the source, including spin and helicity dependent effects, and assess the detectability of each significant bremsstrahlung channel at IceCube/DeepCore. We also show how to combine the sensitivities to the dark matter-nucleon scattering cross section in individual channels, since typically several channels contribute in models.

  16. 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

  17. New exclusion limits for dark gauge forces from proton Bremsstrahlung in beam-dump data

    Energy Technology Data Exchange (ETDEWEB)

    Bluemlein, Johannes [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Brunner, Juergen [Aix-Marseille Univ. CNRS/IN2P3 (France). CPPM

    2013-11-15

    We re-analyze published proton beam dump data taken at the U70 accelerator at IHEP Serpukhov with the {nu}-calorimeter I experiment in 1989 to set mass-coupling limits for dark gauge forces. The corresponding data have been used for axion and light Higgs particle searches before. More recently, limits on dark gauge forces have been derived from this data set, considering a dark photon production from {pi}{sup 0}-decay. Here we determine extended mass and coupling exclusion bounds for dark gauge bosons ranging to masses m{sub {gamma}'} of 624 MeV at admixture parameters {epsilon}{approx_equal}10{sup -6} considering high-energy Bremsstrahlung of the U-boson of the initial proton beam and different detection mechanisms.

  18. 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{\

  19. 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

  20. 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

  1. 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.

  2. Measurement of the transverse diffusion and Townsend's first ionisation coefficients from the observation of the photon flux produced in a Townsend discharge in molecular hydrogen

    International Nuclear Information System (INIS)

    The method used to obtain the transport parameters of a Townsend discharge reported by Blevin et al. (J. Phys. D.; 9:1671, 471 and 465 (1976)) from the observation of the photon flux produced in the discharge has been extended to enable measurements of the transverse diffusion coefficient and Townsend's first ionisation to be made. The results obtained in molecular hydrogen are reported in this paper. (author)

  3. 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

  4. 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

  5. The mechanism of producing energy-polarization entangled photon pairs in the cavity-quantum electrodynamics scheme

    Institute of Scientific and Technical Information of China (English)

    Shu Chang-Gan; Xin Xia; Liu Yu-Min; Yu Zhong-Yuan; Yao Wen-Jie; Wang Dong-Lin; Cao Gui

    2012-01-01

    We investigate theoretically two photon entanglement processes in a photonic-crystal cavity embedding a quantum dot in the strong-coupling regime.The model proposed by Johne et al.(Johne R,Gippius N A,Pavlovic G,Solnyshkov D D,Shelykh I A and Malpuech G 2008 Phys.Rev.Lett.100 240404),and by Robert et al.(Robert J,Gippius N A and Malpuech G 2009 Phys.Rev.B 79 155317) is modified by considering irreversible dissipation and incoherent continuous pumping for the quantum dot,which is necessary to connect the realistic experiment.The dynamics of the system is analysed by employing the Born-Markov master equation,through which the spectra for the system are computed as a function of various parameters.By means of this analysis the photon-reabsorption process in the strongcoupling regime is first observed and analysed from the perspective of radiation spectrum and the optimal parameters for observing energy-entangled photon pairs are identified.

  6. Optical and energy dependent response of the alanine gel solution produced at IPEN to clinical photons and electrons beams

    International Nuclear Information System (INIS)

    The DL-Alanine (C3H7NO2) is an amino acid tissue equivalent traditionally used as standard dosimetric material in EPR dosimetry. Recently, it has been studied to be applied in gel dosimetry, considering that the addition of Alanine in the Fricke gel solution improves the production of ferric ions radiation induced. The spectrophotometric evaluation technique can be used comparing the two spectrum wavelengths bands: 457 nm band that corresponds to ferrous ions and 588 nm band that corresponds to ferric ions concentration to evaluate the dosimetric properties of this material. The performance of the Alanine gel solution developed at IPEN has been firstly studied using the spectrophotometric technique aiming to apply this material to 3D clinical doses evaluations using MRI technique. In this work, the optical and the energy dependent response of this solution submitted to clinical photons and electrons beams were studied. Different batches of gel solutions were prepared and maintained at low temperature during 12 h to solidification. Before irradiation, the samples were maintained during 1 h at room temperature. The photons and electrons irradiations were carried out using a Varian 2100C Medical Linear Accelerator of the Radiotherapy Department of the Hospital das Clinicas of the University of Sao Paulo with absorbed doses between 1 and 40 Gy; radiation field of 10 x 10 cm2; photon energies of 6 MeV and 15 MeV; and electron with energies between 6 and 15 MeV. The obtained results indicate that signal response dependence for clinical photons and electrons beams, to the same doses, for Alanine gel dosimeter is better than 3.6 % (1σ), and the energy dependence response, to the same doses, is better 3% (1σ) for both beams. These results indicate that the same calibration factor can be used and the optical response is energy independent in the studied dose range and clinical photons and electrons beams energies. (author)

  7. Optical and energy dependent response of the alanine gel solution produced at IPEN to clinical photons and electrons beams

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Cleber F. [Faculdade Metodo de Sao Paulo (FAMESP), SP (Brazil). Radiologia; Campos, Leticia L. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    The DL-Alanine (C{sub 3}H{sub 7}NO{sub 2}) is an amino acid tissue equivalent traditionally used as standard dosimetric material in EPR dosimetry. Recently, it has been studied to be applied in gel dosimetry, considering that the addition of Alanine in the Fricke gel solution improves the production of ferric ions radiation induced. The spectrophotometric evaluation technique can be used comparing the two spectrum wavelengths bands: 457 nm band that corresponds to ferrous ions and 588 nm band that corresponds to ferric ions concentration to evaluate the dosimetric properties of this material. The performance of the Alanine gel solution developed at IPEN has been firstly studied using the spectrophotometric technique aiming to apply this material to 3D clinical doses evaluations using MRI technique. In this work, the optical and the energy dependent response of this solution submitted to clinical photons and electrons beams were studied. Different batches of gel solutions were prepared and maintained at low temperature during 12 h to solidification. Before irradiation, the samples were maintained during 1 h at room temperature. The photons and electrons irradiations were carried out using a Varian 2100C Medical Linear Accelerator of the Radiotherapy Department of the Hospital das Clinicas of the University of Sao Paulo with absorbed doses between 1 and 40 Gy; radiation field of 10 x 10 cm{sup 2}; photon energies of 6 MeV and 15 MeV; and electron with energies between 6 and 15 MeV. The obtained results indicate that signal response dependence for clinical photons and electrons beams, to the same doses, for Alanine gel dosimeter is better than 3.6 % (1{sigma}), and the energy dependence response, to the same doses, is better 3% (1{sigma}) for both beams. These results indicate that the same calibration factor can be used and the optical response is energy independent in the studied dose range and clinical photons and electrons beams energies. (author)

  8. 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...

  9. Photons and photoneutrons spectra of a Linac of 15 MV

    International Nuclear Information System (INIS)

    Using the Monte Carlo code MCNP-5, the photons and photoneutrons spectra generated in the head stock of the lineal accelerator (Linac) Varian of 15 MV of the Cancerology State of Nayarit were determined. For the calculations a heterogeneous head stock was modeled, more compatible with the work conditions. In the center of the head stock a tungsten target was located on a copper support, followed by the flattened filter. The photons and photoneutrons spectra were obtained accelerating electrons and making them collide against the target to produce photons by Bremsstrahlung, these photons were transported inside the head stock and the photons and photoneutrons spectra were calculated in a punctual detector located under the flattened filter and in the isocenter. The spectra were evaluated in punctual detectors that were located in the plane from the isocenter to the long of the X and Y axes each 20 cm, in an equidistant way, up to 2 m, so much in the longitudinal and transversal axes. In the calculations were used histories 5E(6) with the purpose of obtaining smaller uncertainties to 1%. It was found that the photons spectrum in the punctual detector inside the head stock presents a pick of 1.25 MeV in the energy interval of 0.5 and 1.5 MeV, later suffers a filtration and diminishes in asymptote form. This spectrum modifies when the beam reaches the isocenter, diminishing the low energy photons. Inside the head stock the photoneutrons spectrum shows a structure with two picks, one before 1 MeV and other after 1 MeV; this is for effect of the collimators geometry and the distance. Finally an increment of the total neutrons flow to 60 cm of distance of the isocenter on the Y axis was observed, due to the design geometry of the modeling heterogeneous head stock. (Author)

  10. Wigner representation for experiments on quantum cryptography using two-photon polarization entanglement produced in parametric down-conversion

    International Nuclear Information System (INIS)

    In this paper, the theory of parametric down-conversion in the Wigner representation is applied to Ekert's quantum cryptography protocol. We analyse the relation between two-photon entanglement and (non-secure) quantum key distribution within the Wigner framework in the Heisenberg picture. Experiments using two-qubit polarization entanglement generated in nonlinear crystals are analysed in this formalism, along with the effects of eavesdropping attacks in the case of projective measurements

  11. Wigner representation for experiments on quantum cryptography using two-photon polarization entanglement produced in parametric down-conversion

    Energy Technology Data Exchange (ETDEWEB)

    Casado, A [Departamento de Fisica Aplicada III, Escuela Superior de Ingenieros, Universidad de Sevilla, 41092 Sevilla (Spain); Guerra, S [Centro Asociado de la Universidad Nacional de Educacion a Distancia de Las Palmas de Gran Canaria (Spain); Placido, J [Departamento de Fisica, Universidad de Las Palmas de Gran Canaria (Spain)], E-mail: acasado@us.es

    2008-02-28

    In this paper, the theory of parametric down-conversion in the Wigner representation is applied to Ekert's quantum cryptography protocol. We analyse the relation between two-photon entanglement and (non-secure) quantum key distribution within the Wigner framework in the Heisenberg picture. Experiments using two-qubit polarization entanglement generated in nonlinear crystals are analysed in this formalism, along with the effects of eavesdropping attacks in the case of projective measurements.

  12. On the partial-wave analysis of mesonic resonances decaying to multiparticle final states produced by polarized photons

    Energy Technology Data Exchange (ETDEWEB)

    Salgado, Carlos W., E-mail: salgado@jlab.org [Norfolk State University (United States); The Thomas Jefferson National Accelerator Facility (United States); Weygand, Dennis P. [The Thomas Jefferson National Accelerator Facility (United States)

    2014-04-01

    Meson spectroscopy is going through a revival with the advent of high statistics experiments and new advances in the theoretical predictions. The Constituent Quark Model (CQM) is finally being expanded considering more basic principles of field theory and using discrete calculations of Quantum Chromodynamics (lattice QCD). These new calculations are approaching predictive power for the spectrum of hadronic resonances and decay modes. It will be the task of the new experiments to extract the meson spectrum from the data and compare with those predictions. The goal of this report is to describe one particular technique for extracting resonance information from multiparticle final states. The technique described here, partial wave analysis based on the helicity formalism, has been used at Brookhaven National Laboratory (BNL) using pion beams, and Jefferson Laboratory (JLab) using photon beams. In particular this report broadens this technique to include production experiments using linearly polarized real photons or quasi-real photons. This article is of a didactical nature. We describe the process of analysis, detailing assumptions and formalisms, and is directed towards people interested in starting partial wave analysis.

  13. On the Partial-Wave Analysis of Mesonic Resonances Decaying to Multiparticle Final States Produced by Polarized Photons

    Energy Technology Data Exchange (ETDEWEB)

    Salgado, Carlos W. [Norfolk State University, Norfolk, VA (United States) and Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Weygand, Dennis P. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

    2014-04-01

    Meson spectroscopy is going through a revival with the advent of high statistics experiments and new advances in the theoretical predictions. The Constituent Quark Model (CQM) is finally being expanded considering more basic principles of field theory and using discrete calculations of Quantum Chromodynamics (lattice QCD). These new calculations are approaching predictive power for the spectrum of hadronic resonances and decay modes. It will be the task of the new experiments to extract the meson spectrum from the data and compare with those predictions. The goal of this report is to describe one particular technique for extracting resonance information from multiparticle final states. The technique described here, partial wave analysis based on the helicity formalism, has been used at Brookhaven National Laboratory (BNL) using pion beams, and Jefferson Laboratory (Jlab) using photon beams. In particular this report broaden this technique to include production experiments using linearly polarized real photons or quasi-real photons. This article is of a didactical nature. We describe the process of analysis, detailing assumptions and formalisms, and is directed towards people interested in starting partial wave analysis.

  14. Secondary radiation measurements for particle therapy applications: prompt photons produced by $^{4}$He, $^{12}$C and $^{16}$O ion beams in a PMMA target

    CERN Document Server

    Mattei, Ilaria; De Lucia, Erika; Faccini, Riccardo; Frallicciardi, Paola Maria; Mancini-Terracciano, Carlo; Marafini, Michela; Muraro, Silvia; Paramatti, Riccardo; Patera, Vincenzo; Piersanti, Luca; Pinci, Davide; Rucinski, Antoni; Russomando, Andrea; Sarti, Alessio; Sciubba, Adalberto; Camillocci, Elena Solfaroli; Toppi, Marco; Traini, Giacomo; Voena, Cecilia; Battistoni, Giuseppe

    2016-01-01

    Charged particle beams are used in Particle Therapy (PT) to treat oncological patients due to their selective dose deposition in tissues and to their high biological effect in killing cancer cells with respect to photons and electrons used in conventional radiotherapy. Nowadays, protons and carbon ions are used in PT clinical routine but, recently, the interest on the potential application of helium and oxygen beams is growing due to their reduced multiple scattering inside the body and increased linear energy transfer, relative biological effectiveness and oxygen enhancement ratio. The precision of PT demands for online dose monitoring techniques, crucial to improve the quality assurance of treatments. The beam range confined in the irradiated target can be monitored thanks to the neutral or charged secondary radiation emitted by the interactions of hadron beams with matter. Prompt photons are produced by nuclear de-excitation processes and, at present, different dose monitoring and beam range verification t...

  15. Relation between hard photon production and impact parameter in heavy ion collisions at intermediate energies; Dependance de la production de photons durs avec le parametre d`impact dans les collisions entre ions lourds aux energies intermediaires

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Garcia, G.

    1994-06-01

    Hard photons produced in heavy-ions collisions at intermediate energies have been used in order to study hot and compresses nuclear matter created in these collisions (at Ganil). It was found that Bremsstrahlung radiation emitted in np collisions is the main mechanism of hard-photon production for the whole range of impact parameter. Moreover, it was observed a substantial decrease of the hardness of hard-photon spectrum. The BUU model reproduces very well the experimental results, showing that the hardness of the spectrum reflects, mainly, nuclear-matter compression in the first stage of the collision. A new method was developed to measure the density of the nuclear matter created at the beginning of the collision. BUU results and some experimental evidences point out that a significant contribution of hard photons are produced in the last stage of the collision: thermal hard photons. These photons are sensitive to the density oscillation of nuclear matter. Its production cross-section will constitute a measurement of the compressibility of nuclear matter and its spectrum a measure of the temperature. (from author) 64 figs., 60 refs.

  16. 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.

  17. 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.

  18. 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.

  19. 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

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

    Science.gov (United States)

    Okada, Hiroshi; Toma, Takashi

    2015-11-01

    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.

  1. Limits for an inverse bremsstrahlung origin of the diffuse Galactic soft gamma-ray emission

    DEFF Research Database (Denmark)

    Pohl, M.

    1998-01-01

    RXTE, GINGA, and OSSE observations have revealed an intense low-energy gamma-ray continuum emission from the Galactic plane, which is commonly interpreted as evidence for the possible existence of a strong flux of low-energy cosmic ray electrons. In this Paper I discuss the scenario of a hadronic...... origin of the soft Galactic gamma-ray continuum through inverse bremsstrahlung. A flux of low-energy cosmic rays strong enough to produce the observed spectrum of gamma-rays implies substantial gamma-ray emission at a few MeV through nuclear de-excitation. It is shown that the existing limits on excess 3......-7 MeV emission from the Galactic plane, in concert with the constraints from pi(0)-decay gamma-ray emission at higher energies, are in serious conflict with an inverse bremsstrahlung origin of the Galactic soft gamma-ray emission for any physically plausible low-energy cosmic ray spectrum. While...

  2. Photon Scattering in Muon Collisions

    CERN Document Server

    Klasen, M

    1998-01-01

    We estimate the benefit of muon colliders for photon physics. We calculate the rate at which photons are emitted from muon beams in different production mechanisms. Bremsstrahlung is reduced, beamstrahlung disappears, and laser backscattering suffers from a bad conversion of the incoming to the outgoing photon beam in addition to requiring very short wavelengths. As a consequence, the cross sections for jet photoproduction in $\\mu p$ and $\\mu^+\\mu^-$ collisions are reduced by factors of 2.2 and 5 compared to $ep$ and $e^+e^-$ machines. However, the cross sections remain sizable and measurable giving access to the photon and proton parton densities down to $x$ values of $10^{-3}$ to $10^{-4}$.

  3. Photon scattering in muon collisions.

    Energy Technology Data Exchange (ETDEWEB)

    Klasen, M.

    1997-12-18

    The authors estimate the benefit of muon colliders for photon physics. They calculate the rate at which photons are emitted from muon beams in different production mechanisms. Bremsstrahlung is reduced, beamstrahlung disappears, and laser backscattering suffers from a bad conversion of the incoming to the outgoing photon beam in addition to requiring very short wavelengths. As a consequence, the cross sections for jet photoproduction in {mu}p and {mu}{sup +} {mu}{sup {minus}} collisions are reduced by factors of 2.2 and 5 compared to ep and e{sup +} e{sup {minus}} machines. However, the cross sections remain sizable and measurable giving access to the photon and proton parton densities down to x values of 10{sup {minus}3} to 10{sup {minus}4}.

  4. 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

  5. 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...

  6. Structural color produced by a three-dimensional photonic polycrystal in the scales of a longhorn beetle: Pseudomyagrus waterhousei (Coleoptera: Cerambicidae)

    Science.gov (United States)

    Simonis, Priscilla; Vigneron, Jean Pol

    2011-01-01

    The cuticle of the longhorn beetle Pseudomyagrus waterhousei shows a diffuse pattern of mixed blue and violet colors. These colorations arise from a dense layer of droplet-shaped scales covering the dorsal parts of the cuticle. In spite of their lack of iridescence, these colors are shown to be structural and produced by an aggregate of internally ordered photonic-crystal grains. Computer simulations confirm that the blue and violet colors are caused by face-centered-cubic crystallites which dominantly expose their (111) surface to illumination and viewing.

  7. 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

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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...

  13. Generation of Long-Lived Isomeric States via Bremsstrahlung Irradiation

    CERN Document Server

    Cheng, Y; Tang, C; Liu, Y; Jin, Q; Cheng, Yao; Xia, Bing; Tang, Chuanxiang; Liu, Yinong; Jin, Qingxiu

    2006-01-01

    A method to generate long-lived isomeric states effectively for Mossbauer applications is reported. We demonstrate that this method is better and easier to provide highly sensitive Mossbauer effect of long-lived isomers (>1ms) such as 103Rh. Excitation of (gamma,gamma) process by synchrotron radiation is painful due mainly to their limited linewidth. Instead,(gamma,gamma') process of bremsstrahlung excitation is applied to create these long-lived isomers. Isomers of 45Sc, 107Ag, 109Ag, and 103Rh have been generated from this method. Among them, 103Rh is the only one that we have obtained the gravitational effect at room temperature.

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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 ...

  19. Coherent bremsstrahlung and a new possibility to monitor collisions of beams at colliders

    Energy Technology Data Exchange (ETDEWEB)

    Kotkin, G.L. [Novosibirskij Gosudarstvennyj Univ. (Russian Federation); Serbo, V.G. [Novosibirskij Gosudarstvennyj Univ. (Russian Federation)

    1996-09-21

    We consider the coherent bremsstrahlung (CBS) at colliders with short bunches. CBS is radiation of particles of one bunch in the collective electromagnetic field of the oncoming bunch. It seems that CBS can be a potential tool for fast control over collisions and for measuring beam parameters. The bunch length {sigma}{sub z} can be found from the critical energy of the CBS spectrum E{sub c}{proportional_to}1/{sigma}{sub z}; the transverse bunch size {sigma} {sub perpendicular} {sub to} is related to the photon rate dN{sub {gamma}}{proportional_to}1/{sigma} {sub perpendicular} {sub to} {sup 2}. A specific dependence of dN{sub {gamma}} on the impact parameter between the beams allows for a fast control over the beam displacement. We present the main characteristics of CBS calculated for B and {phi} factories, LHC (in the p-p and Pb-Pb modes), RHIC, VEPP-2M and VEPP-4M. (orig.).

  20. Production of Ac-225 for cancer therapy by photon-induced transmutation of Ra-226.

    Science.gov (United States)

    Melville, G; Meriarty, H; Metcalfe, P; Knittel, T; Allen, B J

    2007-09-01

    The increasing application of Ac-225 for cancer therapy indicates the potential need for its increased production and availability. The production of Ac-225 has been achieved using bremsstrahlung photons from an 18 MV medical linear accelerator (linac) to bombard a Ra-226 target. A linac dose of 2800 Gy produced about 64 microCi of Ra-225, which decays to Ac-225. This result, while consistent with the theoretical calculations, is far too low to be of practical use. A more powerful linac is required that runs at a higher current, longer pulse length and higher frequency for practical production. This process could also lead to the reduction of the nuclear waste product Ra-226.

  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. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Nucleon-Nucleon Bremsstrahlung emission of massive Axion

    CERN Document Server

    Giannotti, M

    2005-01-01

    We consider the problem of axion production by bremsstrahlung emission in a nuclear medium. The usual assumption of a massless axion is replaced by more general hypotheses, so that we can describe the emission process for axions with mass up to a few MeV. We point out that in certain physical situations the contribution from non-zero mass is non-negligible. In particular, in the mechanism for the production of Gamma Ray Bursts via emission of heavy axions the axion mass m_a ~ 1MeV is comparable with the temperature of the nuclear medium and thus can not be disregarded. Looking at our results we find, in fact, a fairly considerable reduction of the axion luminosity in that mechanism.

  7. 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.

  8. The double copy: Bremsstrahlung and accelerating black holes

    Science.gov (United States)

    Luna, Andrés; Monteiro, Ricardo; Nicholso, Isobel; O'Connell, Donal; White, Chris D.

    2016-06-01

    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 intro-duced 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.

  9. Real and virtual bremsstrahlung in few-body systems

    NARCIS (Netherlands)

    Bacelar, JCS

    2002-01-01

    The real- and virtual-photon emission during interactions between few-nucleon systems have been investigated at KVI with a 190 MeV proton beam. Here I will concentrate the discussion on the results of the virtual-photon emission for the proton-proton system and proton-deuteron capture. Predictions o

  10. Multiple Bremsstrahlung in gauge theories at high energies. Pt. 3

    International Nuclear Information System (INIS)

    We present a method for calculating the various spin amplitudes for QED processes in which an arbitrary number of photons is radiated in directions nearly parallel to the fermion directions. This is accomplished by introducing explicit polarization vectors for the photons and by working in the high energy limit, where finite mass effects are treated in leading order. (orig.)

  11. Parametric interference effect in nonresonant spontaneous bremsstrahlung of an electron in the field of a nucleus and two pulsed laser waves

    Science.gov (United States)

    Lebed', A. A.; Padusenko, E. A.; Roshchupkin, S. P.; Dubov, V. V.

    2016-07-01

    Nonresonant spontaneous bremsstrahlung of an electron scattered by a nucleus in the field of two moderately strong pulsed waves is studied theoretically. The process is studied in detail within the interference kinematic region. This region is determined by scattering of particles in the same plane at predetermined angles, at which stimulated absorption and emission of photons of external pulsed waves by an electron occur in a correlated manner. It is shown that the probability of the partial process with correlated emission (absorption) by an electron of the equal number of photons of the both waves is of an order of the magnitude greater than the corresponding probability in any other scattering kinematics. The cross section of spontaneous bremsstrahlung in two pulsed waves may be two times greater than the cross section of a free-field process after summation over all stimulated processes of correlated emission and absorption. Obtained results may be experimentally verified, for example, by scientific facilities at sources of pulsed laser radiation (SLAC, FAIR, ELI, XCELS).

  12. Imaging of dopamine D2 and somatostatin receptors in vivo using single-photon emission tomography in a patient with a TSH/PRL-producing pituitary macroadenoma

    International Nuclear Information System (INIS)

    A 28-year-old man with a thyroid stimulating hormone/prolactin (TSH/PRL)-secreting pituitary macroadenoma is discussed in relation to dopamine D2 and somatostatin receptor single-photon emission tomography (SPET). Somatostatin and dopamine D2 receptors were present on the tumour as visualised by SPET with the ligands indium-111-DTPA-octreotide (111In-SMS) and iodine-123 iodobenzamide (123I-IBZM), respectively. Therefore, treatment with octreotide 150 μg t.i.d. subcutaneously and bromocriptine 10 mg b.i.d. orally was given for >12 and >6 weeks, respectively. Following this treatment the visual defects disappeared, although tumour size, as measured by CT scanning, and serum TSH levels did not decrease. SPET with 111In-SMS and 123I-IBZM after therapy relvealed no change or a possible increase in somatostatin receptor binding potential and a possible decrease in dopamine D2 receptor binding potential. The lack of long-term effects of the medical treatment is discussed. It is concluded that a high somatostatin and dopamine D2 receptor binding potential in vivo in a TSH/PRL-producing adenoma does not necessarily predict a successful outcome of medicaal treatment. (orig./MG)

  13. Universal Parametrization of Thermal Photon Production in Hadronic Matter

    Science.gov (United States)

    Heffernan, Matthew; Hohler, Paul; Rapp, Ralf

    2014-09-01

    As the production of photons and dileptons from high-energy collisions is able to provide information on the high temperature and high density phases of nuclear matter, an improved and universal parametrization of the rather involved microscopic calculations is key to honing the theory behind this production. We focus on photon emission rates from hadronic many-body calculations of the in-medium rho spectral function, which includes the effects of baryons and antibaryons. Across a range of temperatures from 0.1 to 0.18 GeV and baryon chemical potentials from 0 to 0.4 GeV, a parametrization of thermal photon rates for energies from 0.2 to 5 GeV is numerically determined through the use of nested fitting methods. This provides a fully functional description of thermal photon production largely within an unprecedented 20% of the calculated values from the spectral function, a significant reduction in error from available parametrizations. The contribution of photons and dileptons from pion-pion bremsstrahlung is evaluated for the importance of its contribution. The functional form, coupled with the comparison to the bremsstrahlung production of thermal photons, will provide a baseline for guiding future studies. As the production of photons and dileptons from high-energy collisions is able to provide information on the high temperature and high density phases of nuclear matter, an improved and universal parametrization of the rather involved microscopic calculations is key to honing the theory behind this production. We focus on photon emission rates from hadronic many-body calculations of the in-medium rho spectral function, which includes the effects of baryons and antibaryons. Across a range of temperatures from 0.1 to 0.18 GeV and baryon chemical potentials from 0 to 0.4 GeV, a parametrization of thermal photon rates for energies from 0.2 to 5 GeV is numerically determined through the use of nested fitting methods. This provides a fully functional description of

  14. Photon-photon colliders

    Energy Technology Data Exchange (ETDEWEB)

    Sessler, A.M.

    1995-04-01

    Since the seminal work by Ginsburg, et at., the subject of giving the Next Linear Collider photon-photon capability, as well as electron-positron capability, has drawn much attention. A 1990 article by V.I. Teinov describes the situation at that time. In March 1994, the first workshop on this subject was held. This report briefly reviews the physics that can be achieved through the photon-photon channel and then focuses on the means of achieving such a collider. Also reviewed is the spectrum of backscattered Compton photons -- the best way of obtaining photons. We emphasize the spectrum actually obtained in a collider with both polarized electrons and photons (peaked at high energy and very different from a Compton spectrum). Luminosity is estimated for the presently considered colliders, and interaction and conversion-point geometries are described. Also specified are laser requirements (such as wavelength, peak power, and average power) and the lasers that might be employed. These include conventional and free-electron lasers. Finally, we describe the R&D necessary to make either of these approaches viable and explore the use of the SLC as a test bed for a photon-photon collider of very high energy.

  15. Photon-photon colliders

    International Nuclear Information System (INIS)

    Since the seminal work by Ginsburg, et at., the subject of giving the Next Linear Collider photon-photon capability, as well as electron-positron capability, has drawn much attention. A 1990 article by V.I. Teinov describes the situation at that time. In March 1994, the first workshop on this subject was held. This report briefly reviews the physics that can be achieved through the photon-photon channel and then focuses on the means of achieving such a collider. Also reviewed is the spectrum of backscattered Compton photons -- the best way of obtaining photons. We emphasize the spectrum actually obtained in a collider with both polarized electrons and photons (peaked at high energy and very different from a Compton spectrum). Luminosity is estimated for the presently considered colliders, and interaction and conversion-point geometries are described. Also specified are laser requirements (such as wavelength, peak power, and average power) and the lasers that might be employed. These include conventional and free-electron lasers. Finally, we describe the R ampersand D necessary to make either of these approaches viable and explore the use of the SLC as a test bed for a photon-photon collider of very high energy

  16. 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.)

  17. 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

  18. 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...

  19. EXPERIMENTAL SET UP TO MEASURE COHERENT BREMSSTRAHLUNG AND BEAM PROFILES IN RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    TRBOJEVIC,D.; GASNER,D.; MACKAY,W.; MCINTYRE,G.; PEGGS,S.; TEPIKIAN,S.; SERBO,V.; KOTKIN,G.

    2002-06-03

    A proposal for an experiment to detect and measure with an array infrared detector either the infrared radiation from the beam-beam coherent bremsstrahlung or from the synchrotron light from the edge effect of large DX RHIC magnet is described. Predictions for the 100 GeV/nucleon gold and 250 GeV proton signals from both bremsstrahlung and synchtrotron radiation magnet edge effect are shown.

  20. 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.

  1. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Peysson, Y.; Imbeaux, F. [Association Euratom-CEA, CEA/Cadarache, Dept. de Recherches sur la Fusion Controlee (DRFC), 13 - Saint-Paul-lez-Durance (France)

    1999-04-01

    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/{gamma}-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)

  3. Photon-photon colliders

    Energy Technology Data Exchange (ETDEWEB)

    Sessler, Andrew M.

    1996-01-01

    Since the seminal work by Ginsburg, et al., the subject of giving the Next Linear Collider photon-photon capability, as well as electron-positron capability, has drawn much attention [1]. A 1990 article by V.I. Telnov describes the situation at that time [2]. In March 1994, the first workshop on this subject was held [3]. This report briefly reviews the physics that can be achieved through the photon-photon channel and then focuses on the means of achieving such a collider. Also reviewed is the spectrum of backscattered Compton photons—the best way of obtaining photons. We emphasize the spectrum actually obtained in a collider with both polarized electrons and photons (peaked at high energy and very different from a Compton spectrum). Luminosity is estimated for the presently considered colliders, and interaction and conversion-point geometries are described. Also specified are laser requirements (such as wavelength, peak power, and average power) and the lasers that might be employed. These include conventional and free-electron lasers. Finally, we describe the R&D necessary to make either of these approaches viable and explore the use of the SLC as a test bed for a photon-photon collider of very high energy.

  4. Photon-photon collisions

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.J.

    1988-07-01

    Highlights of the VIIIth International Workshop on Photon-Photon Collisions are reviewed. New experimental and theoretical results were reported in virtually every area of ..gamma gamma.. physics, particularly in exotic resonance production and tests of quantum chromodynamics where asymptotic freedom and factorization theorems provide predictions for both inclusive and exclusive ..gamma gamma.. reactions at high momentum transfer. 73 refs., 12 figs.

  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. A study of photon production in hadronic events from e sup + e sup - annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Pitzl, D.D.; Greenshaw, T.; Hagemann, J.; Heinzelmann, G.; Kleinwort, C.; Kuhlen, M.; Ould-Saada, F.; Schneekloth, U.; Weber, G. (Hamburg Univ. (Germany, F.R.). 2. Inst. fuer Experimentalphysik); Allison, J.; Barlow, R.J.; Chrin, J.; Duerdoth, I.P.; Loebinger, F.K.; Macbeth, A.A.; Murphy, P.G.; Stephens, K. (Manchester Univ. (UK)); Ambrus, K.; Bethke, S.; Dieckmann, A.; Eckerlin, G.; Elsen, E.; Heintze, J.; Hellenbrand, K.H.; Komamiya, S.; Krogh, J. von; Rieseberg, H.; Smolik, L.; Spitzer, J.; Wagner, A.; Zimmer, M. (Heidelberg Univ. (Germany, F.R.). Physikalisches Inst.); Bartel, W.; Felst, R.; Haidt, D.; Kado, H.; Knies, G.; Krehbiel, H.; Magnussen, N.; Meinke, R.; Naroska, B.; Olsson, J.; Ramcke, R.; Schmidt, D.; Steffen, P. (Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany, F.R.)); Bowdery, C.K.; Finch, A.J.; Foster, F.; Hughes, G.; Nye, J.M.; Walker, I.W. (Lancaster Univ. (UK)); Cartwright, S.L.; Clarke, D.; Marshall, R.; Middleton, R.P. (Rutherford Appleton Lab., Ch; JADE Collaboration

    1990-03-01

    Results are presented on an investigation of photons produced in multihadronic final states from e{sup +}e{sup -} annihilation at 35 GeV and 44 GeV center of mass energies. Scaling violation between 14 and 44 GeV is observed in inclusive photon spectra. Comparing inclusive {pi}{sup 0} spectra with charged pion spectra it is found that the average {pi}{sup 0} multiplicity exceeds the charged pion multiplicity scaled by factor of 0.5 by (16{plus minus}5)% and (21{plus minus}7)% at 35 and 44 GeV respectively. The excess can be attributed to isospin violating decays of hadrons. The {eta} multiplicity is found to be =0.64{plus minus}0.09{plus minus}0.06 at 35 GeV. With a significance of three standard deviations a signal from quark bremsstrahlung is observed. The measured charge asymmetry in hadronic final states, due to the interference between initial and final state radiation, of A=-0.141{plus minus}0.041 is in accord with QED expectations. An interference effect in the azimuth angle distribution of charged jets around the photon direction is observed for the first time. (orig.).

  7. 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)

  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. First Measurement of the Quark-to-Photon Fragmentation Function

    CERN Document Server

    Thompson, J

    1995-01-01

    Earlier measurements at LEP of isolated hard photons in hadronic $Z$ decays attributed to radiation from primary quark pairs, have been extended in the ALEPH experiment to include hard photon production {\\em inside} hadron jets. Events are selected where all particles combine democratically to form hadron jets, one of which contains a photon with a fractional energy $z\\geq 0.7$. After statistical subtraction of non-prompt photons, the quark- to-photon fragmentation function, $D(z)$, is extracted directly from the measured prompt production rate. By taking into account the perturbative contributions to $D(z)$ obtained from an $\\cal{O}(\\alpha \\alpha_S)$ QCD calculation, the unknown non-perturbative component of $D(z)$ is determined at high $z$. This measurement is compared with an earlier theoretical parametrisation widely used to determine the level of quark bremsstrahlung present in prompt photon production at the hadron colliders.

  10. A theoretical model for the production of Ac-225 for cancer therapy by photon-induced transmutation of Ra-226.

    Science.gov (United States)

    Melville, G; Fan Liu, Sau; Allen, B J

    2006-09-01

    Radium needles that were once implanted into tumours as a cancer treatment are now obsolete and constitute a radioactive waste problem, as their half-life is 1600 years. We are investigating the reduction of radium by transmutation on a small scale by bombarding Ra-226 with high-energy photons from a medical linear accelerator (linac) to produce Ra-225, which subsequently decays to Ac-225, which can be used as a generator to produce Bi-213 for use in 'targeted alpha therapy' for cancer. This paper examines the possibility of producing Ac-225 with a linac using an accurate theoretical model in which the bremsstrahlung photon spectrum at 18 MV linac electron energy is convoluted with the corresponding photonuclear cross sections of Ra-226. The total integrated yield can then be obtained and is compared with a computer simulation. This study shows that at 18 MV, the photonuclear reaction on Ra-226 can produce low activities of Ac-225 with a linac. However, a high power linac with high current, pulse length and frequency is needed to produce practical amounts of Ac-225 and a useful reduction of Ra-226.

  11. Hard Photon production from unsaturated quark gluon plasma at two loop level

    CERN Document Server

    Dutta, D; Mohanty, A K; Kumar, K; Choudhury, R K

    2002-01-01

    The hard photon productions from bremsstrahlung and annihilation with scattering that arise at two loop level are estimated from a chemically non-equilibrated quark gluon plasma using the frame work of thermal field theory. Although, the rate of photon production is suppressed due to unsaturated phase space, the above suppression is relatively smaller than expected due to an additional collinear enhancement (arise due to decrease in thermal quark mass) as compared to it's equilibrium counterpart. Interestingly, unlike the one loop case, the reduction in the two loop processes are found to be independent of gluon chemical poential, but strongly depends on quark fugacity. It is also found that, since the phase space suppression is highest for annihilation with scattering, the photon production is entirely dominated by bremsstrahlung mechanism at all energies. This is to be contrasted with the case of the equilibrated plasma where annihilation with scattering dominates the photon production particularly at highe...

  12. Hard photon production from unsaturated quark-gluon plasma at two-loop level

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, D. E-mail: ddutta@apsara.barc.ernet.in; Sastry, S.V.S.; Mohanty, A.K.; Kumar, K

    2002-11-18

    The hard photon production from bremsstrahlung and annihilation with scattering that arise at two-loop level are estimated for a chemically non-equilibrated quark-gluon plasma in the framework of Hard Thermal Loop (HTL) resummed effective field theory. The rate of photon production is found to be suppressed due to unsaturated phase space compared to equilibrated plasma. For an unsaturated plasma, unlike the effective one-loop case, the reduction in the effective two-loop processes is found to be independent of gluon fugacity, due to an additional collinear enhancement arising from the decrease in thermal quark mass but strongly depends on quark and antiquark fugacities. It is also found that the photon production is dominated by bremsstrahlung mechanism, since the phase space suppression is higher for annihilation with scattering, in contrast to the equilibrated plasma where annihilation with scattering dominates the photon production.

  13. High energy photon-photon collisions

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.J. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Zerwas, P.M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    1994-07-01

    The collisions of high energy photons produced at a electron-positron collider provide a comprehensive laboratory for testing QCD, electroweak interactions and extensions of the standard model. The luminosity and energy of the colliding photons produced by back-scattering laser beams is expected to be comparable to that of the primary e{sup +}e{sup {minus}} collisions. In this overview, we shall focus on tests of electroweak theory in photon-photon annihilation, particularly {gamma}{gamma} {yields} W{sup +}W{sup {minus}}, {gamma}{gamma} {yields} Higgs bosons, and higher-order loop processes, such as {gamma}{gamma} {yields} {gamma}{gamma}, Z{gamma} and ZZ. Since each photon can be resolved into a W{sup +}W{sup minus} pair, high energy photon-photon collisions can also provide a remarkably background-free laboratory for studying WW collisions and annihilation. We also review high energy {gamma}{gamma} tests of quantum chromodynamics, such as the scaling of the photon structure function, t{bar t} production, mini-jet processes, and diffractive reactions.

  14. Transmutation of nuclear wastes using photonuclear reactions triggered by Compton backscattering photons at the Shanghai laser electrongamma source

    Institute of Scientific and Technical Information of China (English)

    CHEN Jin-Gen; YUAN Ren-Yong; XU Jia-Qiang; YAN Zhe; FAN Gong-Tao; SHEN Wen-Qing; XU Wang; WANG Hong-Wei; GUO Wei; MA Yu-Gang; CAI Xiang-Zhou; LU Guang-Cheng; XU Yi; PAN Qiang-Yan

    2008-01-01

    Based on the facility of the Shanghai Laser Electron Gamma Source (SLEGS),the transmutation for nuclear wastes such as 137Cs and 129I is investigated.It is found that nuclear waste can be transmuted efficiently via photonuclear reaction triggered by gamma photons generated from Compton backscattering between CO2 laser photons and 3.5 GeV electrons.The nuclear activities of 137Cs and 129I are evaluated and compared with the results of transmutation triggered by bremsstrahlung gamma photons driven by ultra intense laser.Due to the better character of gamma photon spectrum as well as the high brightness of gamma photons,the transmutation rate of Compton backscattering method is much higher than that of the bremsstrahlung method.

  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. 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.

  17. 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

  18. ASCA View of the Supernova Remnant Gamma Cygni (G78.2+2.1) Bremsstrahlung X-ray Spectrum from Loss-flattened Electron Distribution

    CERN Document Server

    Uchiyama, Y; Aharonian, F A; Mattox, J R; Uchiyama, Yasunobu; Takahashi, Tadayuki; Aharonian, Felix; Mattox, John

    2002-01-01

    We perform X-ray studies of the shell-type supernova remnant (SNR) gamma-Cygni associated with the brightest EGRET unidentified source 3EG J2020+4017. In addition to the thermal emissions with characteristic temperature of kT = 0.5-0.9 keV, we found an extremely hard X-ray component from several clumps localized in the northern part of the remnant. This component is described by a power-law with a photon index of 0.8-1.5. Both the absolute flux and the spectral shape of the nonthermal X-rays cannot be explained by the synchrotron or inverse-Compton mechanisms. We argue that the unusually hard X-ray spectrum can be naturally interpreted in terms of nonthermal bremsstrahlung from Coulomb-loss-flattened electron distribution in dense environs with the gas density about 10 to 100 cm^-3 . For given spectrum of the electron population, the ratio of the bremsstrahlung X- and gamma-ray fluxes depends on the position of the ``Coulomb break'' in the electron spectrum. The bulk of gamma-rays detected by EGRET would come...

  19. Photon-photon collisions

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.J.

    1985-01-01

    The study of photon-photon collisions has progressed enormously, stimulated by new data and new calculational tools for QCD. In the future we can expect precise determinations of ..cap alpha../sub s/ and ..lambda../sup ms/ from the ..gamma..*..gamma.. ..-->.. ..pi../sup 0/ form factor and the photon structure function, as well as detailed checks of QCD, determination of the shape of the hadron distribution amplitudes from ..gamma gamma.. ..-->.. H anti H, reconstruction of sigma/sub ..gamma gamma../ from exclusive channels at low W/sub ..gamma gamma../, definitive studies of high p/sub T/ hadron and jet production, and studies of threshold production of charmed systems. Photon-photon collisions, along with radiative decays of the psi and UPSILON, are ideal for the study of multiquark and gluonic resonances. We have emphasized the potential for resonance formation near threshold in virtually every hadronic exclusive channel, including heavy quark states c anti c c anti c, c anti c u anti u, etc. At higher energies SLC, LEP, ...) parity-violating electroweak effects and Higgs production due to equivalent Z/sup 0/ and W/sup + -/ beams from e ..-->.. eZ/sup 0/ and e ..-->.. nu W will become important. 44 references.

  20. Hybrid photon detectors

    CERN Document Server

    D'Ambrosio, C

    2003-01-01

    Hybrid photon detectors detect light via vacuum photocathodes and accelerate the emitted photoelectrons by an electric field towards inversely polarized silicon anodes, where they are absorbed, thus producing electron-hole pairs. These, in turn, are collected and generate electronic signals on their ohmic contacts. This review first describes the characteristic properties of the main components of hybrid photon detectors: light entrance windows, photocathodes, and silicon anodes. Then, essential relations describing the trajectories of photoelectrons in electric and magnetic fields and their backscattering from the silicon anodes are derived. Depending on their anode configurations, three families of hybrid photon detectors are presented: hybrid photomultiplier tubes with single anodes for photon counting with high sensitivity and for gamma spectroscopy; multi-anode photon detector tubes with anodes subdivided into square or hexagonal pads for position-sensitive photon detection; imaging silicon pixel array t...

  1. 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.

  2. Thermalisation and hard X-ray bremsstrahlung efficiency of self-interacting solar flare fast electrons

    CERN Document Server

    Galloway, R K; MacKinnon, A L; Brown, J C

    2010-01-01

    Most theoretical descriptions of the production of solar flare bremsstrahlung radiation assume the collision of dilute accelerated particles with a cold, dense target plasma, neglecting interactions of the fast particles with each other. This is inadequate for situations where collisions with this background plasma are not completely dominant, as may be the case in, for example, low-density coronal sources. We aim to formulate a model of a self-interacting, entirely fast electron population in the absence of a dense background plasma, to investigate its implications for observed bremsstrahlung spectra and the flare energy budget. We derive approximate expressions for the time-dependent distribution function of the fast electrons using a Fokker-Planck approach. We use these expressions to generate synthetic bremsstrahlung X-ray spectra as would be seen from a corresponding coronal source. We find that our model qualitatively reproduces the observed behaviour of some flares. As the flare progresses, the model's...

  3. 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.)

  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. 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 ...

  6. 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.

  7. On the Variational method for LPM Suppression of Photon Emission from Quark-Gluon Plasma

    CERN Document Server

    Sastry, S

    2002-01-01

    The photon emission rates from the quark gluon plasma have been studied considering LPM suppression effects. The integral equation for the transverse vector function (f(p)) that consists of multiple scattering effects has been solved using self-consistent iterations method. Empirical fits to the peak positions of the distributions from iteration method have been obtained for bremsstrahlung and annihilation with scattering (AWS) processes. The variational approach for f(p) calculation has been simplified considerably making some assumptions. Using this method, the photon emission rates at finite baryon density have been estimated. The LPM suppression factors for bremsstrahlung and annihilation with scattering (AWS) processes have been obtained as a function of photon energy and baryon density. The effect of baryon density has been shown to be rather weak and the suppression factors are similar to the zero density case. The suppression factors for AWS processes can be taken at zero density, whereas the bremsstr...

  8. Photons and photoneutrons spectra of a Linac of 15 MV; Espectros de fotones y fotoneutrones de un LINAC de 15 MV

    Energy Technology Data Exchange (ETDEWEB)

    Benites R, J. L.; Carrillo C, A. [Centro Estatal de Cancerologia de Nayarit, Av. Enfermeria, Fracc. Fray Junipero Serra, 63000 Tepic, Nayarit (Mexico); Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Velazquez F, J. B., E-mail: jlbenitesr@prodigy.net.mx [Universidad Autonoma de Nayarit, Posgrado CBAP, Carretera Tepic Compostela Km. 9, Xalisco, Nayarit (Mexico)

    2011-10-15

    Using the Monte Carlo code MCNP-5, the photons and photoneutrons spectra generated in the head stock of the lineal accelerator (Linac) Varian of 15 MV of the Cancerology State of Nayarit were determined. For the calculations a heterogeneous head stock was modeled, more compatible with the work conditions. In the center of the head stock a tungsten target was located on a copper support, followed by the flattened filter. The photons and photoneutrons spectra were obtained accelerating electrons and making them collide against the target to produce photons by Bremsstrahlung, these photons were transported inside the head stock and the photons and photoneutrons spectra were calculated in a punctual detector located under the flattened filter and in the isocenter. The spectra were evaluated in punctual detectors that were located in the plane from the isocenter to the long of the X and Y axes each 20 cm, in an equidistant way, up to 2 m, so much in the longitudinal and transversal axes. In the calculations were used histories 5E(6) with the purpose of obtaining smaller uncertainties to 1%. It was found that the photons spectrum in the punctual detector inside the head stock presents a pick of 1.25 MeV in the energy interval of 0.5 and 1.5 MeV, later suffers a filtration and diminishes in asymptote form. This spectrum modifies when the beam reaches the isocenter, diminishing the low energy photons. Inside the head stock the photoneutrons spectrum shows a structure with two picks, one before 1 MeV and other after 1 MeV; this is for effect of the collimators geometry and the distance. Finally an increment of the total neutrons flow to 60 cm of distance of the isocenter on the Y axis was observed, due to the design geometry of the modeling heterogeneous head stock. (Author)

  9. Secondary radiation measurements for particle therapy applications: prompt photons produced by $^{4}$He, $^{12}$C and $^{16}$O ion beams in a PMMA target

    OpenAIRE

    Mattei, Ilaria; Collamati, Francesco; De Lucia, Erika; Faccini, Riccardo; Frallicciardi, Paola Maria; Mancini-Terracciano, Carlo; Marafini, Michela; Muraro, Silvia; Paramatti, Riccardo; Patera, Vincenzo; Piersanti, Luca; Pinci, Davide; Rucinski, Antoni; Russomando, Andrea; Sarti, Alessio

    2016-01-01

    Charged particle beams are used in Particle Therapy (PT) to treat oncological patients due to their selective dose deposition in tissues and to their high biological effect in killing cancer cells with respect to photons and electrons used in conventional radiotherapy. Nowadays, protons and carbon ions are used in PT clinical routine but, recently, the interest on the potential application of helium and oxygen beams is growing due to their reduced multiple scattering inside the body and incre...

  10. Photon emission produced by Kr{sup +} ions bombardment of Cr and Cr{sub 2}O{sub 3} targets

    Energy Technology Data Exchange (ETDEWEB)

    Boujlaidi, A. El, E-mail: a.elboujlaidi@uca.ma [Equipe de Spectroscopie and Imagerie Atomiques des Matériaux, Université Cadi Ayyad, Marrakech (Morocco); Hammoum, K. [Laboratoire de Mécanique, Structures et Energétique, Université Mouloud Mammeri de Tizi-Ouzou (Algeria); Jadoual, L.; Jourdani, R. [Equipe de Spectroscopie and Imagerie Atomiques des Matériaux, Université Cadi Ayyad, Marrakech (Morocco); Ait El Fqih, M. [Equipe de Spectroscopie and Imagerie Atomiques des Matériaux, Université Cadi Ayyad, Marrakech (Morocco); Ecole Nationale Supérieure d’Arts et Métiers (ENSAM), Université Hassan II Mohammedia – Casablanca (Morocco); Aouchiche, H. [Laboratoire de Mécanique, Structures et Energétique, Université Mouloud Mammeri de Tizi-Ouzou (Algeria); Kaddouri, A. [Equipe de Spectroscopie and Imagerie Atomiques des Matériaux, Université Cadi Ayyad, Marrakech (Morocco)

    2015-01-15

    The sputter induced photon spectroscopy technique was used to study the luminescence spectra of the species sputtered from chromium powder and its oxide Cr{sub 2}O{sub 3}, during 5 keV Kr{sup +} ions bombardment in vacuum better than 10{sup −7} torr. The optical spectra recorded between 350 and 470 nm exhibit discrete lines which are attributed to neutral excited atoms of chromium (Cr I lines). The experiments are also performed under 10{sup −5} torr ultra pure oxygen partial pressure. The results demonstrate that the measured intensities of the emitted photons are always higher in the presence of oxygen and even higher than those obtained for Cr{sub 2}O{sub 3} target. In the presence of oxygen vapor we assume that an oxide film is formed on the chromium surface which is responsible of the increase of photon emission. This variation in the intensities is correctly explained in the model of electron transfer processes between the excited sputtered atom and the bombarded surface. This model suggests that the structure formed on the Cr surface in the case of oxygenated chromium is closer to that of Cr{sub 2}O{sub 3} oxide.

  11. A Comparison of Laser-induced Bremsstrahlung and Laser Compton Scattering for (γ, n) Photo-transmutation of Hazardous Nuclear Waste

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Haseeb ur; Lee, Jiyoung; Kim, Yonghee [KAIST, Daejeon (Korea, Republic of)

    2015-10-15

    This paper also presents sensitivity analysis to yield the maximum possible photo-transmutation rates. In general the possibility of radionuclide transmutation using photo-neutron reaction is evaluated in this work. In this paper a detailed methodology to calculate transmutation reaction rates using Laser Induced Bremsstrahlung (LIB) and Laser Compton Scattering (LCS) has been discussed. The methodology was validated by comparing the calculated reaction rates against published data in publically accessed literatures. In the second half of the paper, the authors present a novel concept to narrow down the LCS photon spectrum to an energy range that matches with the resonance region of a particular radionuclide. This is particularly useful considering hazardous waste is usually a mix of different isotopes. As such, being able to tune the LCS photon into any narrow energy range so as to selectively transmute any particular isotope of interest in the hazardous waste mixture would be very desirable. LCS spectrum is highly sensitive to the electron beam energy, laser power, laser luminosity and Compton backscattering angle. From the results it is quite evident that LCS is much better option for the radionuclide transmutation as reaction rates for the LCS is much higher than LIB method even for very small laser power. It can be seen even for the optimistic reaction rate calculations with Bremsstrahlung method reaction rate is much lower than LCS case for 10 Hz repetition rate. If repetition rate of laser 100 Hz then LIB reaction rate has the same order of the magnitude as the reaction rate via LCS. Higher Laser Powers can yield very high transmutation rates.

  12. 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

  13. 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

  14. 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

  15. 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.

  16. Experimental bremsstrahlung yields for MeV proton bombardment of beryllium and carbon

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, David D. [Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW 2234 (Australia)], E-mail: dcz@ansto.gov.au; Stelcer, Eduard; Siegele, Rainer; Ionescu, Mihail; Prior, Michael [Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW 2234 (Australia)

    2008-04-15

    Experimental bremsstrahlung yields for 2, 3 and 4 MeV protons on thin beryllium and carbon targets have been measured. The yields have been corrected for detector efficiency, self-absorption in the target and fitted to 9th order polynomials over the X-ray energy range 1-10 keV for easy comparison with theoretical calculations.

  17. Coherent Bremsstrahlung, Coherent Pair Production, Birefringence and Polarimetry in the 20-170 GeV energy range using aligned crystals

    CERN Document Server

    Apyan, A; Badelek, B; Ballestrero, S; Biino, C; Birol, I; Cenci, P; Connell, S H; Eichblatt, S; Fonseca, T; Freund, A; Gorini, B; Groess, R; Ispirian, K; Ketel, T; Kononets, Y V; López, A; Mangiarotti, A; Sellschop, J P Friedel; Shieh, M; Sona, P; Strakhovenko, V M; Uggerhøj, U; Uggerhøj, Erik; Van Rens, B; Velasco, M; Vilakazi, Z Z; Wessely, O; Ünel, G; Kononets, Yu V

    2008-01-01

    The processes of coherent bremsstrahlung (CB) and coherent pair production (CPP) based on aligned crystal targets have been studied in the energy range 20-170 GeV. The experimental arrangement allowed these phenomena as well as their polarization dependence to be evaluated under conditions where single-photon cross-sections could be measured. This proved very important as the theoretical description of CB and CPP is an area of active theoretical debate and development. The theoretical approach used in this paper predicts both the cross sections and polarization observables very well for the experimental conditions investigated, indicating that the understanding of CB and CPP is reliable up to energies of 170 GeV. A birefringence effect in CPP was studied and it was demonstrated this enabled new technologies for high energy photon beam optics, such as polarimeters (for both linear and circular polarization) and phase plates. We also present new results regarding the features of coherent high energy photon emis...

  18. Azimuthal asymmetry and correlations of hard photons in intermediate energy heavy ion collisions

    International Nuclear Information System (INIS)

    Hard photon emitted from energetic heavy ion collisions is of very interesting since it does not experience the late-stage nuclear interaction, therefore it is useful to explore the early-stage information of matter phase. In this work, we investigated the directed flow and elliptic flow for proton-neutron Bremsstrahlung hard photons in intermediate energy heavy-ion collisions. The positive directed flow and negative elliptic flow of directed photons are illustrated and they seem to be anti-correlated to the free proton's flow. Also we calculated the two-photon correlation functions from which the information of photon source was extracted, and while two-photon azimuthal correlations are presented as a good method to extract the elliptic flow parameter v2 of direct hard photons. (author)

  19. Photon energy scale determination and commissioning with radiative Z decays

    Directory of Open Access Journals (Sweden)

    Bondu Olivier

    2012-06-01

    Full Text Available The CMS electromagnetic calorimeter (ECAL is composed of 75848 lead-tungstate scintillating crystals. It has been designed to be fast, compact, and radiation hard, with fine granularity and excellent energy resolution. Obtaining the design resolution is a crucial challenge for the SM Higgs search in the two photon channel at the LHC, and more generally good photon calibration and knowledge of the photon energy scale is required for analyses with photons in the final state. The behavior of photons and electrons in the calorimeter is not identical, making the use of a dedicated standard candle for photons, complementary to the canonical highyield Z decay to electrons, highly desirable. The use of Z decays to a pair of muons, where one of the muons emits a Bremsstrahlung photon, can be such a standard candle. These events, which can be cleanly selected, are a source of high-purity, relatively high-pt photons. Their kinematics are well-constrained by the Z boson mass and the precision on the muon momenta, and can be used for numerous calibration and measurement purposes. This proceeding presents the event selection method and the results of the photon energy scale measurement via Z0 → μμγ events as well as their use in evaluating the efficiency of photon identification requirements, based on data recorded by the CMS experiment in 2010.

  20. Photon regeneration plans

    Energy Technology Data Exchange (ETDEWEB)

    Ringwald, A.

    2006-12-15

    Precision experiments exploiting low-energy photons may yield information on particle physics complementary to experiments at high-energy colliders, in particular on new very light and very weakly interacting particles, predicted in many extensions of the standard model. Such particles may be produced by laser photons send along a transverse magnetic field. The laser polarization experiment PVLAS may have seen the first indirect signal of such particles by observing an anomalously large rotation of the polarization plane of photons after the passage through a magnetic field. This can be interpreted as evidence for photon disappearance due to particle production. There are a number of experimental proposals to test independently the particle interpretation of PVLAS. Many of them are based on the search for photon reappearance or regeneration, i.e. for ''light shining through a wall''. At DESY, the Axion-Like Particle Search (ALPS) collaboration is currently setting up such an experiment. (orig.)

  1. Phosphene perception is due to the ultra-weak photon emission produced in various parts of the visual system: glutamate in the focus.

    Science.gov (United States)

    Császár, Noémi; Scholkmann, Felix; Salari, Vahid; Szőke, Henrik; Bókkon, István

    2016-04-01

    Phosphenes are experienced sensations of light, when there is no light causing them. The physiological processes underlying this phenomenon are still not well understood. Previously, we proposed a novel biopsychophysical approach concerning the cause of phosphenes based on the assumption that cellular endogenous ultra-weak photon emission (UPE) is the biophysical cause leading to the sensation of phosphenes. Briefly summarized, the visual sensation of light (phosphenes) is likely to be due to the inherent perception of UPE of cells in the visual system. If the intensity of spontaneous or induced photon emission of cells in the visual system exceeds a distinct threshold, it is hypothesized that it can become a conscious light sensation. Discussing several new and previous experiments, we point out that the UPE theory of phosphenes should be really considered as a scientifically appropriate and provable mechanism to explain the physiological basis of phosphenes. In the present paper, we also present our idea that some experiments may support that the cortical phosphene lights are due to the glutamate-related excess UPE in the occipital cortex. PMID:26544101

  2. Experimental investigations of hard photon emission from strong crystalline fields

    Science.gov (United States)

    Medenwaldt, R.; Møller, S. P.; Jensen, B. N.; Strakhovenko, V. M.; Uggerhøj, E.; Worm, T.; Elsener, K.; Sona, P.; Connell, S. H.; Sellschop, J. P. F.; Avakian, R. O.; Avetisian, A. E.; Taroian, S. P.

    1992-05-01

    For the first time very pronounced high-energy photon peaks have been measured in the radiation emission from 70, 150 and 240 GeV electrons incident at 0.1-1.0 mrad to the axis in diamond and Si crystals. The energy of the photons in the peaks is 0.7-0.8 times the particle energy with yields of 50 times the Bethe-Heitler one (in diamond). The peaks consist of single photons and are caused by the influence of strong crystalline fields on emission of coherent bremsstrahlung, emitted when the ultrarelativistic electrons cross the rows of atoms in a crystal plane. The effect should be envisaged as a source for nearly monoenergetic photons in the multihundred GeV-region.

  3. Experimental investigations of hard photon emission from strong crystalline fields

    Energy Technology Data Exchange (ETDEWEB)

    Medenwaldt, R.; Moeller, S.P.; Jensen, B.N.; Strakhovenko, V.M.; Uggerhoej, E.; Worm, T. (ISA, Aarhus Univ. (Denmark)); Elsener, K. (CERN, Geneva (Switzerland)); Sona, P. (Dipt. di Fisica, Univ. Florence (Italy) Ist. Nazionale di Fisica Nucleare, Florence (Italy)); Connell, S.H.; Sellschop, J.P.F. (Schonland Research Centre for Nuclear Sciences, Univ. of Witwatersrand, Johannesburg (South Africa)); Avakian, R.O.; Avetisian, A.E.; Taroian, S.P. (Yerevan Physics Inst. (Armenia))

    1992-05-07

    For the first time very pronounced high-energy photon peaks have been measured in the radiation emission from 70, 150 and 240 GeV electrons incident at 0.1-1.0 mrad to the axis in diamond and Si crystals. The energy of the photons in the peaks is 0.7-0.8 times the particle energy with yields of 50 times the Bethe-Heitler one (in diamond). The peaks consist of single photons and are caused by the influence of strong crystalline fields on emission of coherent bremsstrahlung, emitted when the ultrarelativistic electrons cross the rows of atoms in a crystal plane. The effect should be envisaged as a source for nearly monoenergetic photons in the multihundred GeV-region. (orig.).

  4. Microwave Photonics

    OpenAIRE

    A J Seeds; Liu, C. P.; Ismail, T; Fice, M. J.; Pozzi, F.; Steed, R. J.; Rouvalis, E.; Renaud, C.C.

    2010-01-01

    Microwave photonics is the use of photonic techniques for the generation, transmission, processing and reception of signals having spectral components at microwave frequencies. This tutorial reviews the technologies used and gives applications examples.

  5. Features of multiphoton-stimulated bremsstrahlung in a quantized field

    Science.gov (United States)

    Burenkov, Ivan A.; Tikhonova, Olga V.

    2010-12-01

    The process of absorption and emission of external field quanta by a free electron during the scattering on a potential centre is investigated in the case of interaction with a quantized electromagnetic field. The analytical expression for differential cross-sections and probabilities of different multiphoton channels are obtained. We demonstrate that in the case of a non-classical 'squeezed vacuum' initial field state the probability for the electron to absorb a large number of photons appears to be larger by several orders of magnitude in comparison to the classical field and leads to the formation of the high-energy plateau in the electron energy spectrum. The generalization of the Marcuse effect to the case of the quantized field is worked out. The total probability of energy absorption by electron from the non-classical light is analysed.

  6. Features of multiphoton-stimulated bremsstrahlung in a quantized field

    Energy Technology Data Exchange (ETDEWEB)

    Burenkov, Ivan A; Tikhonova, Olga V, E-mail: ovtikhonova@mail.r [Institute of Nuclear Physics, Moscow State University, Leninskie Gory 1, Moscow, 119991 (Russian Federation)

    2010-12-14

    The process of absorption and emission of external field quanta by a free electron during the scattering on a potential centre is investigated in the case of interaction with a quantized electromagnetic field. The analytical expression for differential cross-sections and probabilities of different multiphoton channels are obtained. We demonstrate that in the case of a non-classical 'squeezed vacuum' initial field state the probability for the electron to absorb a large number of photons appears to be larger by several orders of magnitude in comparison to the classical field and leads to the formation of the high-energy plateau in the electron energy spectrum. The generalization of the Marcuse effect to the case of the quantized field is worked out. The total probability of energy absorption by electron from the non-classical light is analysed.

  7. Apparatus for photon activation positron annihilation analysis

    Science.gov (United States)

    Akers, Douglas W.

    2007-06-12

    Non-destructive testing apparatus according to one embodiment of the invention comprises a photon source. The photon source produces photons having predetermined energies and directs the photons toward a specimen being tested. The photons from the photon source result in the creation of positrons within the specimen being tested. A detector positioned adjacent the specimen being tested detects gamma rays produced by annihilation of positrons with electrons. A data processing system operatively associated with the detector produces output data indicative of a lattice characteristic of the specimen being tested.

  8. Photon Structure

    OpenAIRE

    Grindhammer, Guenter

    2001-01-01

    Large pT processes at HERA, initiated by almost real and by virtual photons, provide information on the structure of the photon. We report on the latest measurements of dijets and large pT particle production with the H1 detector. This includes a leading order determination of an effective virtual photon parton density, of the gluon density of the photon, and comparisons with models.

  9. Photo-neutron reaction cross-sections for natMo in the bremsstrahlung end-point energies of 12-16 and 45-70 MeV

    Science.gov (United States)

    Naik, H.; Kim, G. N.; Kapote Noy, R.; Schwengner, R.; Kim, K.; Zaman, M.; Shin, S. G.; Gey, Y.; Massarczyk, R.; John, R.; Junghans, A.; Wagner, A.; Cho, M.-H.

    2016-07-01

    The natMo( γ, xn)90, 91, 99Mo reaction cross-sections were experimentally determined for the bremsstrahlung end-point energies of 12, 14, 16, 45, 50, 55, 60 and 70MeV by activation and off-line γ -ray spectrometric technique and using the 20MeV electron linac (ELBE) at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany, and the 100MeV electron linac at the Pohang Accelerator Laboratory (PAL), Pohang, Korea. The natMo( γ, xn)88, 89, 90, 91, 99Mo reaction cross-sections as a function of photon energy were also calculated using the computer code TALYS 1.6. The flux-weighted average cross-sections were obtained from the literature data and the calculated values of TALYS based on mono-energetic photons and are found to be in general agreement with the present results. The flux-weighted average experimental and theoretical cross-sections for the natMo( γ, xn)88, 89, 90, 91, 99Mo reactions increase with the bremsstrahlung end-point energy, which indicates the role of excitation energy. After a certain energy, the individual natMo( γ, xn) reaction cross-sections decrease with the increase of bremsstrahlung energy due to opening of other reactions, which indicates sharing of energy in different reaction channels. The 100Mo( γ, n) reaction cross-section is important for the production of 99Mo , which is a probable alternative to the 98Mo(n, γ) and 235U(n, f ) reactions.

  10. Measurement of flux-weighted average cross-sections and isomeric yield ratios for 103Rh(γ,xn) reactions in the bremsstrahlung end-point energies of 55 and 60 MeV

    Science.gov (United States)

    Shakilur Rahman, Md.; Kim, Kwangsoo; Kim, Guinyun; Naik, Haladhara; Nadeem, Muhammad; Thi Hien, Nguyen; Shahid, Muhammad; Yang, Sung-Chul; Cho, Young-Sik; Lee, Young-Ouk; Shin, Sung-Gyun; Cho, Moo-Hyun; Woo Lee, Man; Kang, Yeong-Rok; Yang, Gwang-Mo; Ro, Tae-Ik

    2016-07-01

    We measured the flux-weighted average cross-sections and the isomeric yield ratios of 99m, g, 100m, g, 101m, g, 102m, gRh in the 103Rh( γ, xn) reactions with the bremsstrahlung end-point energies of 55 and 60MeV by the activation and the off-line γ-ray spectrometric technique, using the 100MeV electron linac at the Pohang Accelerator Laboratory (PAL), Korea. The flux-weighted average cross-sections were calculated by using the computer code TALYS 1.6 based on mono-energetic photons, and compared with the present experimental data. The flux-weighted average cross-sections of 103Rh( γ, xn) reactions in intermediate bremsstrahlung energies are the first time measurement and are found to increase from their threshold value to a particular value, where the other reaction channels open up. Thereafter, it decreases with bremsstrahlung energy due to its partition in different reaction channels. The isomeric yield ratios (IR) of 99m, g, 100m, g, 101m, g, 102m, gRh in the 103Rh( γ, xn) reactions from the present work were compared with the literature data in the 103Rh(d, x), 102-99Ru(p, x) , 103Rh( α, αn) , 103Rh( α, 2p3n) , 102Ru(3He, x), and 103Rh( γ, xn) reactions. It was found that the IR values of 102, 101, 100, 99Rh in all these reactions increase with the projectile energy, which indicates the role of excitation energy. At the same excitation energy, the IR values of 102, 101, 100, 99Rh are higher in the charged particle-induced reactions than in the photon-induced reaction, which indicates the role of input angular momentum.

  11. Direct Photons at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Gabor,D.

    2008-07-29

    Direct photons are ideal tools to investigate kinematical and thermodynamical conditions of heavy ion collisions since they are emitted from all stages of the collision and once produced they leave the interaction region without further modification by the medium. The PHENIX experiment at RHIC has measured direct photon production in p+p and Au+Au collisions at 200 GeV over a wide transverse momentum (p{sub T}) range. The p+p measurements allow a fundamental test of QCD, and serve as a baseline when we try to disentangle more complex mechanisms producing high p{sub T} direct photons in Au+Au. As for thermal photons in Au+Au we overcome the difficulties due to the large background from hadronic decays by measuring 'almost real' virtual photons which appear as low invariant mass e{sup +}e{sup -} pairs: a significant excess of direct photons is measured above the above next-to-leading order perturbative quantum chromodynamics calculations. Additional insights on the origin of direct photons can be gained with the study of the azimuthal anisotropy which benefits from the increased statistics and reaction plane resolution achieved in RHIC Year-7 data.

  12. Constraining the electric dipole photon strength function in {sup 130}Te

    Energy Technology Data Exchange (ETDEWEB)

    Isaak, J.; Loeher, B.; Savran, D.; Silva, J. [ExtreMe Matter Institute EMMI and Research Division, Darmstadt (Germany); FIAS, Frankfurt (Germany); Ahmed, M.W.; Kelley, J.H.; Tornow, W.; Weller, H.R. [Department of Physics, Duke University, TUNL (United States); Beller, J.; Pietralla, N.; Romig, C.; Zweidinger, M. [Institut fuer Kernphysik, TU Darmstadt (Germany); Glorius, J.; Sonnabend, K. [Institut fuer Angewandte Physik, Goethe-Universitaet Frankfurt (Germany); Krticka, M. [Faculty of Mathematics and Physics, Charles University, Prague (Czech Republic); Rusev, G. [Chemistry Division, LANL (United States); Scheck, M. [School of Engineering, University of the West of Scotland (United Kingdom); Tonchev, A.P. [Physics Division, LLNL (United States)

    2014-07-01

    The decay properties of photo-excited states in {sup 130}Te have been investigated by means of Nuclear Resonance Fluorescence experiments at the Darmstadt High Intensity Photon Setup (DHIPS) and the High Intensity γ-ray Source (HIγS). The combination of continuous-energy bremsstrahlung on the one hand and the quasi-monoenergetic and linearly polarized photon beam on the other enables a detailed insight into the photoabsorption cross section and the decay behavior of spin-1 states. Comparing these results to simulations within the statistical model allow for constraining the electric dipole photon strength function (E1-PSF). Results are presented and discussed.

  13. Soft X-ray production by photon scattering in pulsating binary neutron star sources

    Science.gov (United States)

    Bussard, R. W.; Meszaros, P.; Alexander, S.

    1985-01-01

    A new mechanism is proposed as a source of soft (less than 1 keV) radiation in binary pulsating X-ray sources, in the form of photon scattering which leaves the electron in an excited Landau level. In a plasma with parameters typical of such sources, the low-energy X-ray emissivity of this mechanism far exceeds that of bremsstrahlung. This copious source of soft photons is quite adequate to provide the seed photons needed to explain the power-law hard X-ray spectrum by inverse Comptonization on the hot electrons at the base of the accretion column.

  14. Numerical test of polarization sum rules for the triply differential bremsstrahlung cross section in electron-nucleus encounters

    CERN Document Server

    Jakubassa-Amundsen, D H

    2016-01-01

    Inspired by the work of Pratt and coworkers on a sum rule for the polarization correlations in electron bremsstrahlung when the outgoing electron is not observed, we derive the corresponding sum rule for the elementary process of bremsstrahlung. This sum rule is valid for arbitrary electron wavefunctions provided the electron is emitted in the reaction plane. The numerical evaluation of this sum rule within the Dirac partial-wave theory for bare inert spin-zero nuclei and collision energies in the range of 1-10 MeV reveals violations for high nuclear charge. Such violations serve as a measure of the inaccuracies in the bremsstrahlung calculations.

  15. Polychromatic photons

    DEFF Research Database (Denmark)

    Keller, Ole

    2002-01-01

    A review is given of the space-time wave mechanics of single photons, a subject with an almost century long history. The Landau-Peierls photon wave function, which is related nonlocally to the electromagnetic field is first described, and thereafter the so-called energy wave function, based...... train quantum electrodynamics. A brief description of particle (photon) position operators is given, and it is shown that photons usually are only algebraically confined in an emission process. Finally, it is demonstrated that the profile of the birth domain of a radio-frequency photon emitted...

  16. 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.

  17. Detector for high-energy photon backscatter

    Science.gov (United States)

    Silver, Michael D.; Erker, Joseph W.; Duncan, Michael Z.; Hartford, Thomas J.; Sivers, E. A.; Hopkinson, James F.

    1993-12-01

    High energy photon backscatter uses pair production to probe deep beneath surfaces with single side accessibility or to image thick, radiographically opaque objects. At the higher photon energies needed to penetrate thick and/or highly attenuating objects, Compton backscatter becomes strongly forward peaked with relatively little backscatter flux. Furthermore, the downward energy shift of the backscattered photon makes it more susceptible to attenuation on its outbound path. Above 1.022 MeV, pair production is possible; at about 10 MeV, pari production crosses over Compton scatter as the dominant x-ray interaction mechanism. The backscattered photons can be hard x rays from the bremsstrahlung of the electrons and positrons or 0.511 MeV photons from the annihilation of the positron. Monte Carlo computer simulations of such a backscatter system were done to characterize the output signals and to optimize a high energy detector design. This paper touches on the physics of high energy backscatter imaging and describes at some length the detector design for tomographic and radiographic imaging.

  18. Roadmap on silicon photonics

    Science.gov (United States)

    Thomson, David; Zilkie, Aaron; Bowers, John E.; Komljenovic, Tin; Reed, Graham T.; Vivien, Laurent; Marris-Morini, Delphine; Cassan, Eric; Virot, Léopold; Fédéli, Jean-Marc; Hartmann, Jean-Michel; Schmid, Jens H.; Xu, Dan-Xia; Boeuf, Frédéric; O'Brien, Peter; Mashanovich, Goran Z.; Nedeljkovic, M.

    2016-07-01

    Silicon photonics research can be dated back to the 1980s. However, the previous decade has witnessed an explosive growth in the field. Silicon photonics is a disruptive technology that is poised to revolutionize a number of application areas, for example, data centers, high-performance computing and sensing. The key driving force behind silicon photonics is the ability to use CMOS-like fabrication resulting in high-volume production at low cost. This is a key enabling factor for bringing photonics to a range of technology areas where the costs of implementation using traditional photonic elements such as those used for the telecommunications industry would be prohibitive. Silicon does however have a number of shortcomings as a photonic material. In its basic form it is not an ideal material in which to produce light sources, optical modulators or photodetectors for example. A wealth of research effort from both academia and industry in recent years has fueled the demonstration of multiple solutions to these and other problems, and as time progresses new approaches are increasingly being conceived. It is clear that silicon photonics has a bright future. However, with a growing number of approaches available, what will the silicon photonic integrated circuit of the future look like? This roadmap on silicon photonics delves into the different technology and application areas of the field giving an insight into the state-of-the-art as well as current and future challenges faced by researchers worldwide. Contributions authored by experts from both industry and academia provide an overview and outlook for the silicon waveguide platform, optical sources, optical modulators, photodetectors, integration approaches, packaging, applications of silicon photonics and approaches required to satisfy applications at mid-infrared wavelengths. Advances in science and technology required to meet challenges faced by the field in each of these areas are also addressed together with

  19. First e-/Photon Commissioning Results for the GlueX Experiment/Hall D at CEBAF

    Energy Technology Data Exchange (ETDEWEB)

    McCaughan, Michael D. [Jefferson Lab, Newport News, VA; Satogata, Todd J. [Jefferson Lab, Newport News, VA; Roblin, Yves R. [Jefferson Lab, Newport News, VA; Benesch, Jay F. [Jefferson Laboratory, 12000 Jeerson Avenue, Newport News, VA 23606, USA

    2015-09-01

    Experimental Hall D, with flagship experiment GlueX, was constructed as part of the 12 GeV CEBAF upgrade. A new magnetically extracted electron beam line was installed to support this hall. Bremsstrahlung photons from retractable radiators, are delivered to the experiment through a series of collimators following a long drift to allow for beam convergence. Coherent Bremsstrahlung generated by interaction with a diamond radiator will achieve a nominal 40% linear polarization and photon energies between 8.5 and 9 GeV from 12.1 GeV electrons, which are then tagged or diverted to a medium power 60kW electron dump. The expected photon flux is 107-108 Hz. This paper discusses the experimental line design, commissioning experience gained since first beam in spring 2014, and the present results of beam commissioning by the experiment.

  20. 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.

  1. 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.

  2. 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.)

  3. Two photon physics. Personal recollection

    CERN Document Server

    Ginzburg, Ilya F

    2015-01-01

    The term two--photon processes is used for the reactions in which some system of particles is produced in collision of two photons, either real or virtual. In the study of these processes our main goal was to suggest approach, allowing to extract from the data information on proper two--photon process separating it from mechanism which responsible for the production of photons. Here I present my view for history of two--photon physics. I don't try to give complete review, concentrating mainly on works of our team (which cover essential part of the topic) and some colleagues. My citation is strongly incomplete. I cite here only papers which were essential in our understanding of the problems. The choice of presented details is the result of my discussions with Gleb Kotkin and Valery Serbo. 1. Prehistory. 2. Two photon processes at e^+e^- colliders. 3. Photon colliders. 4. Notes on physical program.

  4. 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...

  5. 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.

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

    CERN Document Server

    Mandal, A C; Mitra, D; Sarkar, M; Bhattacharya, D P

    2002-01-01

    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 K subalpha 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.

  7. 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)

  8. 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.

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

    Science.gov (United States)

    Verdoolaege, G.; Von Hellermann, M. G.; Jaspers, R.; Ichir, M. M.; Van Oost, G.

    2006-11-01

    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.

  10. Photonic Lantern

    CERN Document Server

    Leon-Saval, Sergio; Bland-Hawthorn, Joss

    2015-01-01

    Photonic lanterns allow for a low-loss transformation of a multimode waveguide into a discrete number of single-mode waveguides and vice versa, thus, enabling the use of single-mode photonic technologies in multimode systems. In this review, we will discuss the theory and function of the photonic lantern, along with several different variants of the technology. We will also discuss some of its applications in more detail.

  11. CERN manufactured hybrid photon detectors

    CERN Multimedia

    Maximilien Brice

    2004-01-01

    These hybrid photon detectors (HPDs) produce an electric signal from a single photon. An electron is liberated from a photocathode and accelerated to a silicon pixel array allowing the location of the photon on the cathode to be recorded. The electronics and optics for these devices have been developed in close collaboration with industry. HPDs have potential for further use in astrophysics and medical imaging.

  12. Microwave photonics

    CERN Document Server

    Lee, Chi H

    2006-01-01

    Wireless, optical, and electronic networks continue to converge, prompting heavy research into the interface between microwave electronics, ultrafast optics, and photonic technologies. New developments arrive nearly as fast as the photons under investigation, and their commercial impact depends on the ability to stay abreast of new findings, techniques, and technologies. Presenting a broad yet in-depth survey, Microwave Photonics examines the major advances that are affecting new applications in this rapidly expanding field.This book reviews important achievements made in microwave photonics o

  13. Search for new light resonances decaying to jet pairs and produced in association with a photon in proton-proton collisions at $\\sqrt{s}=13$~TeV with the ATLAS detector

    CERN Document Server

    The ATLAS collaboration

    2016-01-01

    This note describes a search for new resonances decaying to pairs of jets in 3.2 fb$^{-1}$ of proton-proton collisions with a centre-of-mass energy of $\\sqrt{s}=13$~TeV recorded during 2015 by the ATLAS detector at the Large Hadron Collider. The search requires the new resonance is produced in association with a high-$p_{\\textrm{T}}$ photon, such as a photon radiated from the colliding partons, in order to efficiently trigger on light resonances. The distribution of the invariant mass of the two leading jets is examined for local excesses above a data-derived estimate of the smoothly falling background. No evidence of anomalous phenomena is observed in the data, which are used to exclude effective cross-sections of processes with Gaussian-shaped contributions to the observed dijet mass distribution and regions of the parameter space of a lepto-phobic axial-vector $Z^\\prime$ benchmark model. These results extend the limits on light dijet resonances obtained at lower centre-of-mass energies.

  14. Response of monitoring instruments to high-energy photon radiation

    CERN Document Server

    Haridas, G; Pradhan, S D; Nayak, A R; Bhagwat, A M

    2000-01-01

    Response of commercially available monitoring instruments to high-energy photon radiation was studied under the stored beam condition of a few milliamperes in the storage ring of the Synchrotron Radiation Source, INDUS-I, at Centre for Advanced Technology (CAT), Indore. The storage ring has a circumference of 18.96 m, where electrons at 450 MeV are stored for a few hours, during which the emitted synchrotron radiation is exploited for scientific research and other applications. Radiation environment near storage ring has bremsstrahlung photons of various energies (maximum 450 MeV). A study has indicated underestimation of dose by conventional radiation monitoring instruments by a factor of 2-4. Response after transmission of photons through massive shield was also studied, which indicated spectral degradation and good response by the survey meters.

  15. Search for large extra dimensions in final states containing one photon or jet and large missing transverse energy produced in pp collisions at square root[s]=1.96 TeV.

    Science.gov (United States)

    Aaltonen, T; Adelman, J; Akimoto, T; Albrow, M G; Alvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Apresyan, A; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzurri, P; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Bednar, P; Beecher, D; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Beringer, J; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Bridgeman, A; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Calancha, C; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Compostella, G; Convery, M E; Conway, J; Copic, K; Cordelli, M; Cortiana, G; Cox, D J; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cully, J C; Dagenhart, D; Datta, M; Davies, T; de Barbaro, P; De Cecco, S; Deisher, A; De Lorenzo, G; Dell'orso, M; Deluca, C; Demortier, L; Deng, J; Deninno, M; Derwent, P F; di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Elagin, A; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Ferrazza, C; Field, R; Flanagan, G; Forrest, R; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garberson, F; Garcia, J E; Garfinkel, A F; Genser, K; Gerberich, H; Gerdes, D; Gessler, A; Giagu, S; Giakoumopoulou, V; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C M; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hewamanage, S; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jayatilaka, B; Jeon, E J; Jha, M K; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Kar, D; Karchin, P E; Kato, Y; Kephart, R; Keung, J; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Knuteson, B; Ko, B R; Koay, S A; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kreps, M; Kroll, J; Krop, D; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhr, T; Kulkarni, N P; Kurata, M; Kusakabe, Y; Kwang, S; Laasanen, A T; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; Lecompte, T; Lee, E; Lee, H S; Lee, S W; Leone, S; Lewis, J D; Lin, C S; Linacre, J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, C; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lovas, L; Lu, R-S; Lucchesi, D; Lueck, J; Luci, C; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; Macqueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis-Katsikakis, A; Margaroli, F; Marino, C; Marino, C P; Martin, A; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Mattson, M E; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzione, A; Merkel, P; Mesropian, C; Miao, T; Miladinovic, N; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyake, H; Moggi, N; Moon, C S; Moore, R; Morello, M J; Morlok, J; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norman, M; Norniella, O; Nurse, E; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Osterberg, K; Pagan Griso, S; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A

    2008-10-31

    We present the results of searches for large extra dimensions in samples of events with large missing transverse energy E_{T} and either a photon or a jet produced in pp[over ] collisions at sqrt[s]=1.96 TeV collected with the Collider Detector at Fermilab II. For gamma+E_{T} and jet+E_{T} candidate samples corresponding to 2.0 and 1.1 fb;{-1} of integrated luminosity, respectively, we observe good agreement with standard model expectations and obtain a combined lower limit on the fundamental parameter of the large extra dimensions model M_{D} as a function of the number of extra dimensions in the model. PMID:18999815

  16. Some theoretical aspects of electron and photon dosimetry

    International Nuclear Information System (INIS)

    The dosimetry standardization programme at the National Bureau of Standards (NBS) has a number of theoretical components. These include the compilation of standard cross-section data sets, the theoretical analysis of detector response to various radiations, the spectral and directional characterization of radiation sources, and the determination of absorbed-dose distributions in irradiated media. This paper describes recent results, with emphasis on photon and electron dosimetry. A discussion is given of some recent developments pertaining to photon attenuation coefficients and electron stopping powers. Response functions are presented for intrinsic germanium detectors (used to measure the output of diagnostic X-ray machines) and for sodium iodide detectors (used to measure the spectral characteristics of one of the NBS 60Co irradiation facilities). As examples of source characterization, calculations are described pertaining to the passage of high-energy electron beams through foils. Consideration is given to thin foils used to spread the electron beam, and to thick foils used as bremsstrahlung converters. The results include the energy spectra and angular distributions of the transmitted electrons and emergent bremsstrahlung photons. An example of the calculation of absorbed-dose distributions is given for irradiation of a carbon phantom by a 60Co gamma-ray beam. (author)

  17. Two-order Interference of Single Photon

    Institute of Scientific and Technical Information of China (English)

    JIANG Yunkun; LI Jian; SHI Baosen; FAN Xiaofeng; GUO Guangcan

    2000-01-01

    A pair of photons called signal and idler photons, respectively, are produced through the nonlinear process of type-I spontaneous parametric downconversion in BBO crystal pumped by the second-harmonic wave of a Ti:sapphire femtosecond laser pulse. The two-order interference phenomenon of the signal photon in Michelson interferometer is observed and give an analysis in detail.

  18. The search for an unknown low-lying nucleon resonance with a real photon beam

    International Nuclear Information System (INIS)

    Full text: Results obtained by different collaborations of eta-photoproduction off the neutron led to speculations about a yet unknown nucleon resonance suggesting surprising properties such as a low mass of about 1685 MeV and a narrow width of 30 MeV. A possible candidate for such a state would be the non-strange member of the antidecuplet of pentaquarks. The existence of this kind of states is however highly doubted. In addition various models succeed to interpret the experimental results of eta-photoproduction off the neutron without the introduction of a new nucleon resonance. On the other hand recent findings in Compton scattering on the neutron give further evidence for the scenario of an unknown resonance. Preliminary results on this question from the Crystal Ball/TAPS collaboration are presented. The experiment was performed using a liquid deuterium target. The beam of tagged photons was produced via Bremsstrahlung of the 1.5 GeV electron beam provided by the MAMI accelerator facility in Mainz (Germany). Particles were detected in the two calorimeters Crystal Ball and TAPS covering around 94% of full solid angle. (author)

  19. Electron, Photon, and Ion Beams from the Relativistic Interaction of Petawatt Laser Pulses with Solid Targets

    International Nuclear Information System (INIS)

    In our Petawatt laser experiments several hundred joules of 1 (micro)m laser light in 0.5-5.0 ps pulses with intensities up to 3 x 1020Wcm-2 were incident on solid targets producing a strongly relativistic interaction. The energy content, spectra, and angular patterns of the photon, electron, and ion radiations were diagnosed in a number of ways, including several novel (to laser physics) nuclear activation techniques. From the beamed bremsstrahlung we infer that about 40-50% of the laser energy is converted to broadly beamed hot electrons. Their direction centroid varies from shot to shot, but the beam has a consistent width. Extraordinarily luminous ion beams almost precisely normal to the rear of various targets are seen--up to 3 x 1013 protons with kTion ∼ several MeV representing ∼6% of the laser energy. We observe ion energies up to at least 55 MeV. The ions appear to originate from the rear target surfaces. The edge of the ion beam is very sharp, and collimation increases with ion energy. At the highest energies, a narrow feature appears in the ion spectra, and the apparent size of the emitting spot is smaller than the full back surface area. Any ion emission from the front of the targets is much less than from the rear and is not sharply beamed. The hot electrons generate a Debye sheath with electrostatic fields of order MV per micron which apparently accelerate the ions

  20. Personnel monitoring for exposure from high energy electron-photon radiation

    International Nuclear Information System (INIS)

    India's first synchrotron radiation source, Indus-1 , is commissioned at the Centre for Advanced Technology (CAT), Indore. Radiation environment of this facility is quite different in comparison to that of nuclear or irradiator facilities and proton or heavy ion accelerator facilities. The primary particle accelerated being the electron, the radiation environment mainly comprises of Bremsstrahlung photons followed by photo-neutrons, whereas electron contamination too exists within the containment area. Due to the complex nature of the radiation viz. high energy, broad energy spectrum, pulsed, mixed field, sharp angular distribution etc. quantification of radiation dose becomes a difficult task. In this paper, the suitability of dosimetry devices for personnel monitoring due to exposure from such a radiation environment is described. Underestimation of radiation doses observed using standard measuring devices is found to be 1.4 to 1.9 for radiation produced from 20 MeV electrons and 1.7 to 38 for 450 MeV electrons. Measures to correct the dose estimation are suggested. (author)

  1. Observation of Tri-photon K-Shell X-Rays

    Institute of Scientific and Technical Information of China (English)

    CHENG Yao; XIA Bing; LI Jin

    2006-01-01

    @@ We report the observation of coincidence of three K-shell x-rays generated from the long-lived rhodium isomer excited by bremsstrahlung irradiation. Our previous report revealed that the E3 Mossbauer transition has anisotropic emission due to anisotropic gravitational acceleration [Chin. Phys. Lett. 22 (2005) 2530]. Now, from broader energy-resolved spectra, we further discover abnormal coincidences and abnormalsum energies of the three K-shell x-rays. The coincidence cannot be explained by currently understood photon statistics, since the measured tri-photon count and the pile-up estimate differ by three orders of magnitude.

  2. Hallo photons calls photon; Allo photon appelle photon

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1997-09-01

    When a pair of photons is created, it seems that these 2 photons are bound together by a mysterious link. This phenomenon has been discovered at the beginning of the seventies. In this new experiment the 2 photons are separated and have to follow different ways through optic cables until they face a quantum gate. At this point they have to chose between a short and a long itinerary. Statistically they have the same probability to take either. In all cases the 2 photons agree to do the same choice even if the 2 quantum gates are distant of about 10 kilometers. Some applications in ciphering and coding of messages are expected. (A.C.)

  3. Diffraction of collinear correlated photon pairs by an ultrasonic wave

    OpenAIRE

    Kwiek, Piotr

    2013-01-01

    The phenomenon of collinear correlated photon pairs diffraction by an ultrasonic wave is investigated for Bragg incidence. A BBO crystal was used for producing collinear correlated photon pairs via type-I spontaneous parametric down-conversion (SPDC I-type). It is shown experimentally that the Bragg angle for photon pairs diffraction is identical to the one corresponding to single photons diffraction. The numbers of single photons and photon pairs counts in discrete diffraction orders were me...

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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...

  11. 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

  12. Photonic Nanojets

    OpenAIRE

    Heifetz, Alexander; Kong, Soon-Cheol; Alan V. Sahakian; Taflove, Allen; Backman, Vadim

    2009-01-01

    This paper reviews the substantial body of literature emerging since 2004 concerning photonic nanojets. The photonic nanojet is a narrow, high-intensity, non-evanescent light beam that can propagate over a distance longer than the wavelength λ after emerging from the shadow-side surface of an illuminated lossless dielectric microcylinder or microsphere of diameter larger than λ. The nanojet’s minimum beamwidth can be smaller than the classical diffraction limit, in fact as small as ~λ/3 for m...

  13. 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.

  14. Photonic lanterns

    Science.gov (United States)

    Leon-Saval, Sergio G.; Argyros, Alexander; Bland-Hawthorn, Joss

    2013-12-01

    Multimode optical fibers have been primarily (and almost solely) used as "light pipes" in short distance telecommunications and in remote and astronomical spectroscopy. The modal properties of the multimode waveguides are rarely exploited and mostly discussed in the context of guiding light. Until recently, most photonic applications in the applied sciences have arisen from developments in telecommunications. However, the photonic lantern is one of several devices that arose to solve problems in astrophotonics and space photonics. Interestingly, these devices are now being explored for use in telecommunications and are likely to find commercial use in the next few years, particularly in the development of compact spectrographs. Photonic lanterns allow for a low-loss transformation of a multimode waveguide into a discrete number of single-mode waveguides and vice versa, thus enabling the use of single-mode photonic technologies in multimode systems. In this review, we will discuss the theory and function of the photonic lantern, along with several different variants of the technology. We will also discuss some of its applications in more detail. Furthermore, we foreshadow future applications of this technology to the field of nanophotonics.

  15. Entangled-photon coincidence fluorescence imaging

    OpenAIRE

    Scarcelli, Giuliano; Yun, Seok H.

    2008-01-01

    We describe fluorescence imaging using the second-order correlation of entangled photon pairs. The proposed method is based on the principle that one photon of the pair carries information on where the other photon has been absorbed and has produced fluorescence in a sample. Because fluorescent molecules serve as “detectors” breaking the entanglement, multiply-scattered fluorescence photons within the sample do not cause image blur. We discuss experimental implementations.

  16. Study of the Dependence of Direct Soft Photon Production on the Jet Characteristics in Hadronic $Z^0$ Decays

    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; Asman, 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; Berat, C; Berggren, M; Bertrand, D; Besancon, 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; Bruckman, P; Brunet, J M; Buschbeck, B; Buschmann, P; Calvi, M; Camporesi, T; Canale, V; Carena, F; Castro, N; Cavallo, F; Chapkin, M; Charpentier, Ph; Checchia, P; Chierici, R; Chliapnikov, P; Chudoba, J; Chung, S U; Cieslik, K; Collins, P; Contri, R; Cosme, G; Cossutti, F; Costa, M J; Crennell, D; Cuevas, J; D'Hondt, J; da Silva, T; Da Silva, W; Della Ricca, G; De Angelis, A; De Boer, W; 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; Ekelof, T; Ellert, M; Elsing, M; Espirito Santo, M C; Fanourakis, G; Fassouliotis, D; Feindt, M; Fernandez, J; Ferrer, A; Ferro, F; Flagmeyer, U; Foeth, H; Fokitis, E; Fulda-Quenzer, F; Fuster, J; Gandelman, M; Garcia, C; Gavillet, Ph; Gazis, E; Gokieli, R; Golob, B; Gomez-Ceballos, G; Goncalves, 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; 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; Katsoufis, E; Kernel, G; Kersevan, B P; Kerzel, U; King, B T; Kjaer, N J; Kluit, P; Kokkinias, P; Kourkoumelis, C; Kouznetsov, O; Krumstein, Z; Kucharczyk, M; Lamsa, J; Leder, G; Ledroit, F; Leinonen, L; Leitner, R; Lemonne, J; Lepeltier, V; Lesiak, T; Liebig, W; Liko, D; Lipniacka, A; Lopes, J H; Lopez, J M; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J; Malek, A; Maltezos, S; Mandl, F; Marco, J; Marco, R; Marechal, B; Margoni, M; Marin, J-C; Mariotti, C; Markou, A; Martinez-Rivero, C; Masik, J; Mastroyiannopoulos, N; Matorras, F; Matteuzzi, C; Mazzucato, F; Mazzucato, M; Mc Nulty, R; Meroni, C; Migliore, E; Mitaroff, W; Mjoernmark, U; Moa, T; Moch, M; Moenig, K; Monge, R; Montenegro, J; Moraes, D; Moreno, S; Morettini, P; Mueller, U; Muenich, K; Mulders, M; Mundim, L; Murray, W; Muryn, B; Myatt, G; Myklebust, T; Nassiakou, M; Navarria, F; Nawrocki, K; Nemecek, S; Nicolaidou, R; Nikolenko, M; Oblakowska-Mucha, A; Obraztsov, V; Olshevski, A; Onofre, A; Orava, R; Österberg, K; Ouraou, A; Oyanguren, A; Paganoni, M; Paiano, S; Palacios, J P; Palka, H; Papadopoulou, Th D; Pape, L; Parkes, C; 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; Pozdniakov, V; Pukhaeva, N; Pullia, A; Radojicic, D; Rebecchi, P; Rehn, J; Reid, D; Reinhardt, R; Renton, P; Richard, F; Ridky, J; Rivero, M; Rodriguez, D; Romero, A; Ronchese, P; Roudeau, P; Rovelli, T; Ruhlmann-Kleider, V; Ryabtchikov, D; Sadovsky, 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; Spassov, T; Stanitzki, M; Stocchi, A; Strauss, J; Stugu, B; Szczekowski, M; Szeptycka, M; Szumlak, T; Tabarelli, T; Tegenfeldt, F; Timmermans, J; Tkatchev, L; Tobin, M; Todorovova, S; Tome, 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, A; Zalewski, P; Zavrtanik, D; Zhuravlov, V; Zimin, N I; Zintchenko, A; Zupan, M

    2010-01-01

    An analysis of the direct soft photon production rate as a function of the parent jet characteristics is presented, based on hadronic events collected by the DELPHI experiment at LEP1. The dependences of the photon rates on the jet kinematic characteristics (momentum, mass, etc.) and on the jet charged, neutral and total hadron multiplicities are reported. Up to a scale factor of about four, which characterizes the overall value of the soft photon excess, a similarity of the observed soft photon behaviour to that of the inner hadronic bremsstrahlung predictions is found for the momentum, mass, and jet charged multiplicity dependences. However for the dependence of the soft photon rate on the jet neutral and total hadron multiplicities a prominent difference is found for the observed soft photon signal as compared to the expected bremsstrahlung from final state hadrons. The observed linear increase of the soft photon production rate with the jet total hadron multiplicity and its strong dependence on the jet ne...

  17. Fission and nuclear fragmentation of silver and bromine nuclei by photons of 1-6 GeV

    International Nuclear Information System (INIS)

    The studies of fission and fragmentation of silver and bromine nuclei by Bremsstrahlung photons of 1.6 GeV energy range are presented. The Il ford-KO nuclear emulsion submitted to Bremsstrahlung beams in Deutsches Elektronen Synchrotron (DESY) with total doses of 10'' equivalent photons, was used for nuclear fragment detection. The discrimination of fission and fragmentation events was done analysing angular distribution, range and angles between fragments. The results of fragment range distributions, angular distributions, distributions of angles between fragments, distributions of ratio between range, velocity distributions forward/backward ratio, cross sections of fission and fragmentation, nuclear fissionability and ternary fission frequency are presented and discussed. (M.C.K.)

  18. Neutron and photon spectra in LINACs

    International Nuclear Information System (INIS)

    A Monte Carlo calculation, using the MCNPX code, was carried out in order to estimate the photon and neutron spectra in two locations of two linacs operating at 15 and 18 MV. Detailed models of both linac heads were used in the calculations. Spectra were estimated below the flattening filter and at the isocenter. Neutron spectra show two components due to evaporation and knock-on neutrons. Lethargy spectra under the filter were compared to the spectra calculated from the function quoted by Tosi et al. that describes reasonably well neutron spectra beyond 1 MeV, though tends to underestimate the energy region between 10–6 and 1 MeV. Neutron and the Bremsstrahlung spectra show the same features regardless of the linac voltage. - Highlights: ► With MCNPX code realistic models of two LINACs were built. ► Photon and neutron spectra below the flattening filter and at the isocenter were calculated. ► Neutron spectrum at the flattening filter was compared against the Tosi et al. source-term model. ► Tosi et al. model underestimates the neutron contribution below 1 MeV. ► Photon spectra look alike to those published in literature.

  19. 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)

  20. 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.

  1. 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

  2. The Heavy Photon Search experiment at Jefferson Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    De Napoli, Marzio [Istituto Nazionale di Fisica Nucleare (INFN), Catania (Italy). Lab. et al.

    2015-06-01

    Many beyond Standard Model theories predict a new massive gauge boson, a.k.a. 'dark' or 'heavy photon', directly coupling to hidden sector particles with dark charge. The heavy photon is expected to mix with the Standard Model photon through kinetic mixing and therefore couple weakly to normal charge. The Heavy Photon Search (HPS) experiment will search for the heavy photon at the Thomas Jefferson National Accelerator Facility (JLab), in the mass range 20-1000 MeV/c2 and coupling to electric charge ϵ2 = α'/α in the range 10-5 to 10-10. HPS will look for the e+e- decay channel of heavy photons radiated by electron Bremsstrahlung, employing both invariant mass search and detached vertexing techniques. The experiment employs a compact forward spectrometer comprising silicon microstrip detectors for vertexing and tracking and an electromagnetic calorimeter for particle identification and triggering.

  3. 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)

  4. A measurement of the magnetic dipole moment of the. delta. /sup + +/(1232) from the bremsstrahlung process. pi. p. -->. pi. p. gamma

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, C.A.

    1987-06-01

    We have measured the cross section from the bremsstrahlung process ..pi../sup +/p ..-->.. ..pi../sup +/p..gamma.. for incident pions of energy 299 MeV. We detected the out going pion in the angular range from 55 to 95/sup 0/ in the lab, and photons were detected near 240/sup 0/ 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 ..delta../sup + +/(1232), ..mu../sub ..delta../. 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 75/sup 0/ the theory gives us a dipole moment of: 2.3..mu../sub p/ < ..mu../sub ..delta../ < 3.3..mu../sup p/ where the quoted error arises from an experimental uncertainty of +-0.25..mu../sub p/ and from theoretical uncertainties of +-0.25 ..mu../sub p/. However, for pion angles between 75 and 95/sup 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 ..mu../sub ..delta../. 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.

  5. Testing QCD in Photon-Photon Interactions

    OpenAIRE

    Soldner-Rembold, Stefan

    1998-01-01

    At high energies photon-photon interactions are dominated by quantum fluctuations of the photons into fermion-antifermion pairs and into vector mesons. This is called photon structure. Electron-positron collisions at LEP are an ideal laboratory for studying photon structure and for testing QCD.

  6. Nuclear photonics

    Energy Technology Data Exchange (ETDEWEB)

    Habs, D.; Guenther, M. M.; Jentschel, M.; Thirolf, P. G. [Ludwig-Maximilians-Universitaet Muenchen, D-85748 Garching (Germany); Max Planck Institut fuer Quantenoptik, D-85748 Garching (Germany); Institut Laue-Langevin, F-38042 Grenoble (Germany); Ludwig-Maximilians-Universitaet Muenchen, D-85748 Garching (Germany)

    2012-07-09

    With the planned new {gamma}-beam facilities like MEGa-ray at LLNL (USA) or ELI-NP at Bucharest (Romania) with 10{sup 13}{gamma}/s and a band width of {Delta}E{gamma}/E{gamma} Almost-Equal-To 10{sup -3}, a new era of {gamma} beams with energies up to 20MeV comes into operation, compared to the present world-leading HI{gamma}S facility at Duke University (USA) with 10{sup 8}{gamma}/s and {Delta}E{gamma}/E{gamma} Almost-Equal-To 3 Dot-Operator 10{sup -2}. In the long run even a seeded quantum FEL for {gamma} beams may become possible, with much higher brilliance and spectral flux. At the same time new exciting possibilities open up for focused {gamma} beams. Here we describe a new experiment at the {gamma} beam of the ILL reactor (Grenoble, France), where we observed for the first time that the index of refraction for {gamma} beams is determined by virtual pair creation. Using a combination of refractive and reflective optics, efficient monochromators for {gamma} beams are being developed. Thus, we have to optimize the total system: the {gamma}-beam facility, the {gamma}-beam optics and {gamma} detectors. We can trade {gamma} intensity for band width, going down to {Delta}E{gamma}/E{gamma} Almost-Equal-To 10{sup -6} and address individual nuclear levels. The term 'nuclear photonics' stresses the importance of nuclear applications. We can address with {gamma}-beams individual nuclear isotopes and not just elements like with X-ray beams. Compared to X rays, {gamma} beams can penetrate much deeper into big samples like radioactive waste barrels, motors or batteries. We can perform tomography and microscopy studies by focusing down to {mu}m resolution using Nuclear Resonance Fluorescence (NRF) for detection with eV resolution and high spatial resolution at the same time. We discuss the dominating M1 and E1 excitations like the scissors mode, two-phonon quadrupole octupole excitations, pygmy dipole excitations or giant dipole excitations under the new facet of

  7. Search for dark photons from supersymmetric hidden valleys

    NARCIS (Netherlands)

    V.M. Abazov; . et al; L.S. Ancu; S.J. de Jong; F. Filthaut; C.F. Galea; J.G. Hegeman; P. Houben; M.M. Meijer; P. Svoisky; P.J. van den Berg; W.M. van Leeuwen

    2009-01-01

    We search for a new light gauge boson, a dark photon, with the D0 experiment. In the model we consider, supersymmetric partners are pair produced and cascade to the lightest neutralinos that can decay into the hidden sector state plus either a photon or a dark photon. The dark photon decays through

  8. Skin Inqjuries Reduce Survival and Modulate Corticosterone, C-Reactive Protein, Complement Component 3, IgM, and Prostaglandin E2 after Whole-Body Reactor-Produced Mixed Field (n + γ-Photons Irradiation

    Directory of Open Access Journals (Sweden)

    Juliann G. Kiang

    2013-01-01

    Full Text Available Skin injuries such as wounds or burns following whole-body γ-irradiation (radiation combined injury (RCI increase mortality more than whole-body γ-irradiation alone. Wound-induced decreases in survival after irradiation are triggered by sustained activation of inducible nitric oxide synthase pathways, persistent alteration of cytokine homeostasis, and increased susceptibility to systemic bacterial infection. Among these factors, radiation-induced increases in interleukin-6 (IL-6 concentrations in serum were amplified by skin wound trauma. Herein, the IL-6-induced stress proteins including C-reactive protein (CRP, complement 3 (C3, immunoglobulin M (IgM, and prostaglandin E2 (PGE2 were evaluated after skin injuries given following a mixed radiation environment that might be found after a nuclear incident. In this report, mice received 3 Gy of reactor-produced mixed field (n+γ-photons radiations at 0.38 Gy/min followed by nonlethal skin wounding or burning. Both wounds and burns reduced survival and increased CRP, C3, and PGE2 in serum after radiation. Decreased IgM production along with an early rise in corticosterone followed by a subsequent decrease was noted for each RCI situation. These results suggest that RCI-induced alterations of corticosterone, CRP, C3, IgM, and PGE2 cause homeostatic imbalance and may contribute to reduced survival. Agents inhibiting these responses may prove to be therapeutic for RCI and improve related survival.

  9. Search for new light resonances decaying to jet pairs and produced in association with a photon or a jet in proton-proton collisions at $\\sqrt{s}=13$~TeV with the ATLAS detector

    CERN Document Server

    The ATLAS collaboration

    2016-01-01

    This note describes a search for new resonances decaying to pairs of jets in 15.5 fb$^{-1}$ of proton-proton collisions with a centre-of-mass energy of $\\sqrt{s}=13$~TeV recorded during 2015 and 2016 by the ATLAS detector at the Large Hadron Collider. The search requires the new resonance would be produced in association with a high-$p_{\\textrm{T}}$ photon or jet, such as those radiated from the colliding partons, in order to efficiently trigger on events containing light resonances. The distribution of the invariant mass of the the pair of jets is examined for local excesses above a data-derived estimate of the smoothly falling background. No evidence of anomalous phenomena is observed in the data, which are used to exclude effective cross-sections of processes with Gaussian-shaped contributions to the observed dijet mass distribution and regions of the parameter space of a lepto-phobic axial-vector $Z^\\prime$ benchmark model. These results extend limits on light dijet resonances obtained by ATLAS with 2015 ...

  10. Photonic crystals

    CERN Document Server

    Busch, Kurt; Wehrspohn, Ralf B; Föll, Helmut

    2006-01-01

    The majority of the contributions in this topically edited book stems from the priority program SPP 1113 ""Photonische Kristalle"" run by the Deutsche Forschungsgemeinschaft (DFG), resulting in a survey of the current state of photonic crystal research in Germany. The first part of the book describes methods for the theoretical analysis of their optical properties as well as the results. The main part is dedicated to the fabrication, characterization and modeling of two- and three-dimensional photonic crystals, while the final section presents a wide spectrum of applications: gas sensors, micr

  11. Vesicle Photonics

    Energy Technology Data Exchange (ETDEWEB)

    Vasdekis, Andreas E.; Scott, E. A.; Roke, Sylvie; Hubbell, J. A.; Psaltis, D.

    2013-04-03

    Thin membranes, under appropriate boundary conditions, can self-assemble into vesicles, nanoscale bubbles that encapsulate and hence protect or transport molecular payloads. In this paper, we review the types and applications of light fields interacting with vesicles. By encapsulating light-emitting molecules (e.g. dyes, fluorescent proteins, or quantum dots), vesicles can act as particles and imaging agents. Vesicle imaging can take place also under second harmonic generation from vesicle membrane, as well as employing mass spectrometry. Light fields can also be employed to transport vesicles using optical tweezers (photon momentum) or directly pertrurbe the stability of vesicles and hence trigger the delivery of the encapsulated payload (photon energy).

  12. Surface-wave photonic quasicrystal

    CERN Document Server

    Gao, Zhen; Zhang, Youming; Xu, Hongyi; Zhang, Baile

    2016-01-01

    In developing strategies of manipulating surface electromagnetic waves, it has been recently recognized that a complete forbidden band gap can exist in a periodic surface-wave photonic crystal, which has subsequently produced various surface-wave photonic devices. However, it is not obvious whether such a concept can be extended to a non-periodic surface-wave system that lacks translational symmetry. Here we experimentally demonstrate that a surface-wave photonic quasicrystal that lacks periodicity can also exhibit a forbidden band gap for surface electromagnetic waves. The lower cutoff of this forbidden band gap is mainly determined by the maximum separation between nearest neighboring pillars. Point defects within this band gap show distinct properties compared to a periodic photonic crystal for the absence of translational symmetry. A line-defect waveguide, which is crafted out of this surface-wave photonic quasicrystal by shortening a random row of metallic rods, is also demonstrated to guide and bend sur...

  13. Photonic crystals principles and applications

    CERN Document Server

    Gong, Qihuang

    2013-01-01

    IntroductionPrimary Properties of Photonic CrystalsFabrication of Photonic CrystalsPhotonic Crystal All-Optical SwitchingTunable Photonic Crystal FilterPhotonic Crystal LaserPhotonic Crystal Logic DevicesPhotonic Crystal Sensors

  14. Photon differentials

    DEFF Research Database (Denmark)

    Schjøth, Lars; Revall Frisvad, Jeppe; Erleben, Kenny;

    2007-01-01

    illumination features. This is often not desirable as these may lose clarity or vanish altogether. We present an accurate method for reconstruction of indirect illumination with photon mapping. Instead of reconstructing illumination using classic density estimation on finite points, we use the correlation...

  15. Photon Differentials

    DEFF Research Database (Denmark)

    Schjøth, Lars; Frisvad, Jeppe Revall; Erleben, Kenny;

    2007-01-01

    illumination features. This is often not desirable as these may lose clarity or vanish altogether. We present an accurate method for reconstruction of indirect illumination with photon mapping. Instead of reconstructing illumination using classic density estimation on finite points, we use the correlation...

  16. 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 mat...

  17. A double FEL oscillator: A possible scheme for a photon-photon collider

    Science.gov (United States)

    Dattoli, G.; Torre, A.

    2013-08-01

    Exploration of the mutual scattering of photons in vacuum is considered as a fundamental test of the quantum electrodynamics theory. In this connection, we propose a "double" free-electron laser oscillator as a possible device for head-on photon-photon collisions. The device is conceived to comprise two undulator sections within the same cavity, where then two laser beams are produced by two counterpropagating electron beams. The latter are in turn exploited to produce gamma photons by backward Compton scattering of the intracavity FEL radiation itself. A preliminary analysis of the collision rate of the backscattered photons is presented specifically at the maximum of the relevant cross section.

  18. What are single photons good for?

    Science.gov (United States)

    Sangouard, Nicolas; Zbinden, Hugo

    2012-10-01

    In a long-held preconception, photons play a central role in present-day quantum technologies. But what are sources producing photons one by one good for precisely? Well, in opposition to what many suggest, we show that single-photon sources are not helpful for point to point quantum key distribution because faint laser pulses do the job comfortably. However, there is no doubt about the usefulness of sources producing single photons for future quantum technologies. In particular, we show how single-photon sources could become the seed of a revolution in the framework of quantum communication, making the security of quantum key distribution device-independent or extending quantum communication over many hundreds of kilometers. Hopefully, these promising applications will provide a guideline for researchers to develop more and more efficient sources, producing narrowband, pure and indistinguishable photons at appropriate wavelengths.

  19. What are single photons good for?

    CERN Document Server

    Sangouard, Nicolas

    2012-01-01

    In a long-held preconception, photons play a central role in present-day quantum technologies. But what are sources producing photons one by one good for precisely? Well, in opposition to what many suggest, we show that single-photon sources are not helpful for point to point quantum key distribution because faint laser pulses do the job comfortably. However, there is no doubt about the usefulness of sources producing single photons for future quantum technologies. In particular, we show how single-photon sources could become the seed of a revolution in the framework of quantum communication, making the security of quantum key distribution device independent or extending quantum communication over many hundreds of kilometers. Hopefully, these promising applications will provide a guideline for researchers to develop more and more efficient sources, producing narrowband, pure and indistinguishable photons at appropriate wavelengths.

  20. Photon-Photon Scattering at the Photon Linear Collider

    OpenAIRE

    Jikia, G.; Tkabladze, A.

    1993-01-01

    Photon-photon scattering at the Photon Linear Collider is considered. Explicit formulas for helicity amplitudes due to $W$ boson loops are presented. It is shown that photon-photon scattering should be easily observable at PLC and separation of the $W$ loop contribution (which dominates at high energies) will be possible at $e^+e^-$ c.m. energy of 500~GeV or higher.

  1. Fermi LAT Search for Internal Bremsstrahlung Signatures from Dark Matter Annihilation

    CERN Document Server

    Bringmann, Torsten; Ibarra, Alejandro; Vogl, Stefan; Weniger, Christoph

    2012-01-01

    A commonly encountered obstacle in indirect searches for galactic dark matter is how to disentangle possible signals from astrophysical backgrounds. Given that such signals are most likely subdominant, the search for pronounced spectral features plays a key role for indirect detection experiments; monochromatic gamma-ray lines or similar features related to internal bremsstrahlung, in particular, provide smoking gun signatures. We perform a dedicated search for the latter in the data taken by the Fermi gamma-ray space telescope during its first 43 months. To this end, we use a new adaptive procedure to select optimal target regions that takes into account both standard and contracted dark matter profiles. The behaviour of our statistical method is tested by a bootstrap analysis of the full sky data and found to reproduce the theoretical expectations very well. The limits on the dark matter annihilation cross-section that we derive are stronger than what can be obtained from the observation of dwarf galaxies a...

  2. 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...

  3. 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)

  4. 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

  5. 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.

  6. The interference effect of laser-assisted bremsstrahlung emission in Coulumb fields of two nuclei

    CERN Document Server

    Li, Ankang; Ren, Na; Wang, Pingxiao; Zhu, Wenjun; Li, Xiaoya; Hoehn, Ross; Kais, S

    2013-01-01

    In this paper, the spontaneous bremsstrahlung emission from an electron scattered by two fixed nuclei in an intense laser field is investigated in details based upon the Volkov state and the Dirac-Volkov propagator. It has been found that the fundamental harmonic spectrum from the electron radiation exhibits distinctive fringes, which is dependent not only upon the internucleus distance and orientation, but also upon the initial energy of the electron and the laser intensity. By analyzing the differential cross section, we are able to explain these effects in terms of interference among the electron scattering by the nuclei. These results could have promising applications in probing the atomic or molecular dressed potentials in intense laser fields.

  7. 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

  8. Groomed jets in heavy-ion collisions: sensitivity to medium-induced bremsstrahlung

    CERN Document Server

    Mehtar-Tani, Yacine

    2016-01-01

    We argue that contemporary jet substructure techniques might facilitate a more direct measurement of hard medium-induced gluon bremsstrahlung in heavy-ion collisions, and focus specifically on the "soft drop declustering" procedure that singles out the two leading jet substructures. Assuming coherent jet energy loss, we find an enhancement of the distribution of the energy fractions shared by the two substructures at small subjet energy caused by hard medium-induced gluon radiation. Departures from this approximation are discussed, in particular, the effects of colour decoherence and the contamination of the grooming procedure by soft background. Finally, we propose a complementary observable, that is the ratio of the two-pronged probability in Pb-Pb to proton-proton collisions and discuss its sensitivity to various energy loss mechanisms.

  9. 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.)

  10. 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)

  11. Detection of 1 - 100 keV x-rays from high intensity, 500 fs laser- produced plasmas using charge-coupled devices

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, J.; Young, B.K.F.; Conder, A.D.; Stewart, R.E.

    1996-01-01

    We describe a compact, vacuum compatible, large format, charge- coupled device (CCD) camera for scientific imaging and detection of 1- 100 keV x rays in experiments at LLNL JANUS-1ps laser. A standard, front-illuminated, multi-pin phase device with 250 k electron full well capacity, low dark current (10 pA/cm{sup 2} at 20 C) and low read noise (5 electron rms) is cooled to -35 C to give the camera excellent 15-bit dynamic range and signal-to-noise response. Intensity and x-ray energy linear response were determined for optical and x-ray (<65 keV) photons and are in excellent agreement. Departure from linearity was less than 0.7%. Inherent linearity and energy dispersive characteristics of CCD cameras are well suited for hard x-ray photon counting. X-rays absorbed within the depletion and field-free regions can be distinguished by studying the pulse height spectrum. Results are presented for the detection of 1-100 keV Bremsstrahlung continuum, K-shell and L-shell fluorescence spectra emitted from high intensity (10{sup 18}W cm{sup -2}), 500 fs laser- produced plasmas.

  12. Photon Production through Multi-step Processes Important in Nuclear Fluorescence Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Hagmann, C; Pruet, J

    2006-10-26

    The authors present calculations describing the production of photons through multi-step processes occurring when a beam of gamma rays interacts with a macroscopic material. These processes involve the creation of energetic electrons through Compton scattering, photo-absorption and pair production, the subsequent scattering of these electrons, and the creation of energetic photons occurring as these electrons are slowed through Bremsstrahlung emission. Unlike single Compton collisions, during which an energetic photon that is scattered through a large angle loses most of its energy, these multi-step processes result in a sizable flux of energetic photons traveling at large angles relative to an incident photon beam. These multi-step processes are also a key background in experiments that measure nuclear resonance fluorescence by shining photons on a thin foil and observing the spectrum of back-scattered photons. Effective cross sections describing the production of backscattered photons are presented in a tabular form that allows simple estimates of backgrounds expected in a variety of experiments. Incident photons with energies between 0.5 MeV and 8 MeV are considered. These calculations of effective cross sections may be useful for those designing NRF experiments or systems that detect specific isotopes in well-shielded environments through observation of resonance fluorescence.

  13. Microalgae photonics

    Science.gov (United States)

    Floume, Timmy; Coquil, Thomas; Sylvestre, Julien

    2011-05-01

    Due to their metabolic flexibility and fast growth rate, microscopic aquatic phototrophs like algae have a potential to become industrial photochemical converters. Algae photosynthesis could enable the large scale production of clean and renewable liquid fuels and chemicals with major environmental, economic and societal benefits. Capital and operational costs are the main issues to address through optical, process and biochemical engineering improvements. In this perspective, a variety of photonic approaches have been proposed - we introduce them here and describe their potential, limitations and compatibility with separate biotechnology and engineering progresses. We show that only sunlight-based approaches are economically realistic. One of photonics' main goals in the algae field is to dilute light to overcome photosaturation effects that impact upon cultures exposed to full sunlight. Among other approaches, we introduce a widely-compatible broadband spectral adaptation technique called AlgoSun® that uses luminescence to optimize sunlight spectrum in view of the bioconverter's requirements.

  14. New information on photon fragmentation functions

    CERN Document Server

    Klasen, M

    2014-01-01

    Thermal photons radiated in heavy-ion collisions represent an important signal for a recently discovered new state of matter, the deconfined quark-gluon plasma. However, a clean identification of this signal requires precise knowledge of the prompt photons produced simultaneously in hard collisions of quarks and gluons, mostly through their fragmentation. In this Letter, we demonstrate that PHENIX data on photons produced in proton-proton collisions with low transverse momenta allow to extract new information on this fragmentation process. In particular, these data favor one parameterization (BFG II) over the two other frequently used photon fragmentation functions (BFG I and GRV NLO).

  15. Photon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Va`vra, J.

    1995-10-01

    J. Seguinot and T. Ypsilantis have recently described the theory and history of Ring Imaging Cherenkov (RICH) detectors. In this paper, I will expand on these excellent review papers, by covering the various photon detector designs in greater detail, and by including discussion of mistakes made, and detector problems encountered, along the way. Photon detectors are among the most difficult devices used in physics experiments, because they must achieve high efficiency for photon transport and for the detection of single photo-electrons. For gaseous devices, this requires the correct choice of gas gain in order to prevent breakdown and wire aging, together with the use of low noise electronics having the maximum possible amplification. In addition, the detector must be constructed of materials which resist corrosion due to photosensitive materials such as, the detector enclosure must be tightly sealed in order to prevent oxygen leaks, etc. The most critical step is the selection of the photocathode material. Typically, a choice must be made between a solid (CsI) or gaseous photocathode (TMAE, TEA). A conservative approach favors a gaseous photocathode, since it is continuously being replaced by flushing, and permits the photon detectors to be easily serviced (the air sensitive photocathode can be removed at any time). In addition, it can be argued that we now know how to handle TMAE, which, as is generally accepted, is the best photocathode material available as far as quantum efficiency is concerned. However, it is a very fragile molecule, and therefore its use may result in relatively fast wire aging. A possible alternative is TEA, which, in the early days, was rejected because it requires expensive CaF{sub 2} windows, which could be contaminated easily in the region of 8.3 eV and thus lose their UV transmission.

  16. Photon detectors

    International Nuclear Information System (INIS)

    J. Seguinot and T. Ypsilantis have recently described the theory and history of Ring Imaging Cherenkov (RICH) detectors. In this paper, I will expand on these excellent review papers, by covering the various photon detector designs in greater detail, and by including discussion of mistakes made, and detector problems encountered, along the way. Photon detectors are among the most difficult devices used in physics experiments, because they must achieve high efficiency for photon transport and for the detection of single photo-electrons. For gaseous devices, this requires the correct choice of gas gain in order to prevent breakdown and wire aging, together with the use of low noise electronics having the maximum possible amplification. In addition, the detector must be constructed of materials which resist corrosion due to photosensitive materials such as, the detector enclosure must be tightly sealed in order to prevent oxygen leaks, etc. The most critical step is the selection of the photocathode material. Typically, a choice must be made between a solid (CsI) or gaseous photocathode (TMAE, TEA). A conservative approach favors a gaseous photocathode, since it is continuously being replaced by flushing, and permits the photon detectors to be easily serviced (the air sensitive photocathode can be removed at any time). In addition, it can be argued that we now know how to handle TMAE, which, as is generally accepted, is the best photocathode material available as far as quantum efficiency is concerned. However, it is a very fragile molecule, and therefore its use may result in relatively fast wire aging. A possible alternative is TEA, which, in the early days, was rejected because it requires expensive CaF2 windows, which could be contaminated easily in the region of 8.3 eV and thus lose their UV transmission

  17. Nanowire photonics

    OpenAIRE

    Peter J. Pauzauskie; Peidong Yang

    2006-01-01

    The development of integrated electronic circuitry ranks among the most disruptive and transformative technologies of the 20th century. Even though integrated circuits are ubiquitous in modern life, both fundamental and technical constraints will eventually test the limits of Moore's law. Nanowire photonic circuitry constructed from myriad one-dimensional building blocks offers numerous opportunities for the development of next-generation optical information processors and spectroscopy. Howev...

  18. Topological photonics

    OpenAIRE

    Lu, Ling; Joannopoulos, John D.; Soljačić, Marin

    2014-01-01

    The application of topology, the mathematics of conserved properties under continuous deformations, is creating a range of new opportunities throughout photonics. This field was inspired by the discovery of topological insulators, in which interfacial electrons transport without dissipation, even in the presence of impurities. Similarly, the use of carefully designed wavevector-space topologies allows the creation of interfaces that support new states of light with useful and interesting prop...

  19. Calibration processes for photon-photon colliders

    CERN Document Server

    Bartos, E; Galynsky, M V; Kuraev, E A

    2004-01-01

    Processes with creation of a pair charged particles with emission of hard photon and two pairs of charged particles are considered for colliding partially polarized photon photon beams. The effects of circular and linear polarization of the initial photons are discussed in more detail.

  20. The low energy frontier: probes with photons

    Energy Technology Data Exchange (ETDEWEB)

    Redondo, J.

    2008-05-15

    I discuss different aspects of the phenomenology of hypothetical sub eV mass particles arising in the context of extensions of the standard model. I focus on a simple extension based on an additional U(1) gauge symmetry and its corresponding gauge boson, called ''hidden photon''. Kinetic mixing with the standard photon leads to photon-hidden photon oscillations that are searched for in laboratory experiments like ALPS at DESY. Hidden photons produced in the interior of the Sun could be also detected in axion helioscopes like CAST at CERN and could play an interesting role in late cosmology, where the presence of additional feebly interacting relativistic particles seems to be favored. All these effects disappear as the hidden photon mass decreases, allowing phenomenologically large kinetic mixings. However, in this case such a hidden photon will even play a role in gauge coupling unification. (orig.)

  1. Adaptive Photon Mapping Based on Gradient

    Institute of Scientific and Technical Information of China (English)

    Chun-Meng Kang; Lu Wang; Yan-Ning Xu; Xiang-Xu Meng; Yuan-Jie Song

    2016-01-01

    Photon mapping can simulate some special effects efficiently such as shadows and caustics. Photon mapping runs in two phases: the photon map generating phase and the radiance estimation phase. In this paper, we focus on the bandwidth selection process in the second phase, as it can affect the final quality significantly. Poor results with noise arise if few photons are collected, while bias appears if a large number of photons are collected. In order to solve this issue, we propose an adaptive radiance estimation solution to obtain trade-offs between noise and bias by changing the number of neighboring photons and the shape of the collected area according to the radiance gradient. Our approach can be applied in both the direct and the indirect illumination computation. Finally, experimental results show that our approach can produce smoother quality while keeping the high frequency features perfectly compared with the original photon mapping algorithm.

  2. Internal Bremsstrahlung spectrum from 57Co in coincidence with K-X rays

    International Nuclear Information System (INIS)

    In the present study, the IB photons from 57Co are measured in coincidence with 6.4 keV x rays emitted due to the EC process. The IB photons are measured using a (1.75 x 2.0 ) NaI(Tl) scintillation detector and k-x rays are detected using a proportional counter

  3. MCNP: Photon benchmark problems

    Energy Technology Data Exchange (ETDEWEB)

    Whalen, D.J.; Hollowell, D.E.; Hendricks, J.S.

    1991-09-01

    The recent widespread, markedly increased use of radiation transport codes has produced greater user and institutional demand for assurance that such codes give correct results. Responding to these pressing requirements for code validation, the general purpose Monte Carlo transport code MCNP has been tested on six different photon problem families. MCNP was used to simulate these six sets numerically. Results for each were compared to the set's analytical or experimental data. MCNP successfully predicted the analytical or experimental results of all six families within the statistical uncertainty inherent in the Monte Carlo method. From this we conclude that MCNP can accurately model a broad spectrum of photon transport problems. 8 refs., 30 figs., 5 tabs.

  4. Phase zone photon sieve

    Institute of Scientific and Technical Information of China (English)

    Jia Jia; Xie Chang-Qing

    2009-01-01

    A novel diffractive optical element, named phase zone photon sieve (PZPS), is presented. There are three kinds of phase plates in PZPSs: PZPS1, PZPS2, and PZPS3. Each of the PZPSs has its own structure and is made on quartz substrate by etching. The three PZPSs have stronger diffraction peak intensity than a photon sieve (PS) when the margin pinhole and zone line width are kept the same. The PZPS3 can produce a smaller central diffractive spot than the ordinary PS with the same number of zones on the Fresnel zone plate. We have given the design method for and the simulation of PZPS and PS. PZPS has potential applications in optical maskless lithography.

  5. Photonic molecules and spectral engineering

    CERN Document Server

    Boriskina, Svetlana V

    2012-01-01

    This chapter reviews the fundamental optical properties and applications of pho-tonic molecules (PMs) - photonic structures formed by electromagnetic coupling of two or more optical microcavities (photonic atoms). Controllable interaction between light and matter in photonic atoms can be further modified and en-hanced by the manipulation of their mutual coupling. Mechanical and optical tunability of PMs not only adds new functionalities to microcavity-based optical components but also paves the way for their use as testbeds for the exploration of novel physical regimes in atomic physics and quantum optics. Theoretical studies carried on for over a decade yielded novel PM designs that make possible lowering thresholds of semiconductor microlasers, producing directional light emission, achieving optically-induced transparency, and enhancing sensitivity of microcavity-based bio-, stress- and rotation-sensors. Recent advances in material science and nano-fabrication techniques make possible the realization of opt...

  6. Nanosilicon: a new platform for photonics

    Energy Technology Data Exchange (ETDEWEB)

    Bettotti, Paolo; Pavesi, Lorenzo [Nanoscience Laboratory, Department of Physics, University of Trento, via Sommarive 14, 38123 Povo, Trento (Italy)

    2011-09-15

    Silicon photonics has produced the first all-optical components integrated into systems available already on the market. Nanosilicon, where low dimensional silicon allows new phenomena and devices, is a way to expand the reach of silicon photonics. In this article we review some of our past research activities focused on the demonstration of innovative photonic integrated circuits building blocks. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Atomic Memory for Correlated Photon States

    OpenAIRE

    van der Wal, C. H.; Eisaman, M. D.; André, A.; Walsworth, R.L.; Phillips, D. F.; Zibrov, A. S.; Lukin, M. D.

    2003-01-01

    We experimentally demonstrate emission of two quantum-mechanically correlated light pulses with a time delay that is coherently controlled via temporal storage of photonic states in an ensemble of rubidium atoms. The experiment is based on Raman scattering, which produces correlated pairs of spin-flipped atoms and photons, followed by coherent conversion of the atomic states into a different photon beam after a controllable delay. This resonant nonlinear optical process is a promising techniq...

  8. Nanowire photonics

    Directory of Open Access Journals (Sweden)

    Peter J. Pauzauskie

    2006-10-01

    Full Text Available The development of integrated electronic circuitry ranks among the most disruptive and transformative technologies of the 20th century. Even though integrated circuits are ubiquitous in modern life, both fundamental and technical constraints will eventually test the limits of Moore's law. Nanowire photonic circuitry constructed from myriad one-dimensional building blocks offers numerous opportunities for the development of next-generation optical information processors and spectroscopy. However, several challenges remain before the potential of nanowire building blocks is fully realized. We cover recent advances in nanowire synthesis, characterization, lasing, integration, and the eventual application to relevant technical and scientific questions.

  9. 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

  10. 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.

  11. 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

  12. Measurement of direct photons in Au+Au collisions at √(s(NN))=200 GeV.

    Science.gov (United States)

    Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Jamel, A; Alexander, J; Aoki, K; Aphecetche, L; Armendariz, R; Aronson, S H; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Baldisseri, A; Barish, K N; Barnes, P D; Bassalleck, B; Bathe, S; Batsouli, S; Baublis, V; Bauer, F; Bazilevsky, A; Belikov, S; Bennett, R; Berdnikov, Y; Bjorndal, M T; Boissevain, J G; Borel, H; Boyle, K; Brooks, M L; Brown, D S; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J M; Butsyk, S; Campbell, S; Chai, J-S; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choi, I J; Chujo, T; Cianciolo, V; Cleven, C R; Cobigo, Y; Cole, B A; Comets, M P; Connors, M; Constantin, P; Csanád, M; Csörgő, T; Dahms, T; Das, K; David, G; Delagrange, H; Denisov, A; d'Enterria, D; Deshpande, A; Desmond, E J; Dietzsch, O; Dion, A; Drachenberg, J L; Drapier, O; Drees, A; Dubey, A K; Durum, A; Dzhordzhadze, V; Efremenko, Y V; Egdemir, J; Enokizono, A; En'yo, H; Espagnon, B; Esumi, S; Fields, D E; Fleuret, F; Fokin, S L; Forestier, B; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fukao, Y; Fung, S-Y; Gadrat, S; Gastineau, F; Germain, M; Glenn, A; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse Perdekamp, M; Gunji, T; Gustafsson, H-Å; Hachiya, T; Hadj Henni, A; Haggerty, J S; Hagiwara, M N; Hamagaki, H; Harada, H; Hartouni, E P; Haruna, K; Harvey, M; Haslum, E; Hasuko, K; Hayano, R; He, X; Heffner, M; Hemmick, T K; Heuser, J M; Hiejima, H; Hill, J C; Hobbs, R; Holmes, M; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hur, M G; Ichihara, T; Iinuma, H; Imai, K; Imrek, J; Inaba, M; Isenhower, D; Isenhower, L; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Jacak, B V; Jia, J; Jin, J; Jinnouchi, O; Johnson, B M; Joo, K S; Jouan, D; Kajihara, F; Kametani, S; Kamihara, N; Kaneta, M; Kang, J H; Kawagishi, T; Kazantsev, A V; Kelly, S; Khanzadeev, A; Kim, D J; Kim, E; Kim, Y-S; Kinney, E; Kiss, A; Kistenev, E; Kiyomichi, A; Klein-Boesing, C; Kochenda, L; Kochetkov, V; Komkov, B; Konno, M; Kotchetkov, D; Kozlov, A; Kroon, P J; Kunde, G J; Kurihara, N; Kurita, K; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lajoie, J G; Lebedev, A; Le Bornec, Y; Leckey, S; Lee, D M; Lee, M K; Leitch, M J; Leite, M A L; Li, X H; Lim, H; Litvinenko, A; Liu, M X; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Masui, H; Matathias, F; McCain, M C; McGaughey, P L; Miake, Y; Miller, T E; Milov, A; Mioduszewski, S; Mishra, G C; Mitchell, J T; Morrison, D P; Moss, J M; Moukhanova, T V; Mukhopadhyay, D; Murata, J; Nagamiya, S; Nagata, Y; Nagle, J L; Naglis, M; Nakamura, T; Newby, J; Nguyen, M; Norman, B E; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Okada, K; Omiwade, O O; Oskarsson, A; Otterlund, I; Ozawa, K; Pak, R; Pal, D; Palounek, A P T; Pantuev, V; Papavassiliou, V; Park, J; Park, W J; Pate, S F; Pei, H; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, D Yu; Pinkenburg, C; Pisani, R P; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Ravinovich, I; Read, K F; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roche, G; Romana, A; Rosati, M; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Rykov, V L; Ryu, S S; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakai, S; Samsonov, V; Sato, H D; Sato, S; Sawada, S; Semenov, V; Seto, R; Sharma, D; Shea, T K; Shein, I; Shibata, T-A; Shigaki, K; Shimomura, M; Shohjoh, T; Shoji, K; Sickles, A; Silva, C L; Silvermyr, D; Sim, K S; Singh, C P; Singh, V; Skutnik, S; Smith, W C; Soldatov, A; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Suire, C; Sullivan, J P; Sziklai, J; Tabaru, T; Takagi, S; Takagui, E M; Taketani, A; Tanaka, K H; Tanaka, Y; Tanida, K; Tannenbaum, M J; Taranenko, A; Tarján, P; Thomas, T L; Togawa, M; Tojo, J; Torii, H; Towell, R S; Tram, V-N; Tserruya, I; Tsuchimoto, Y; Tuli, S K; Tydesjö, H; Tyurin, N; Vale, C; Valle, H; van Hecke, H W; Velkovska, J; Vértesi, R; Vinogradov, A A; Vznuzdaev, E; Wagner, M; Wang, X R; Watanabe, Y; Wessels, J; White, S N; Willis, N; Winter, D; Woody, C L; Wysocki, M; Xie, W; Yanovich, A; Yokkaichi, S; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zaudtke, O; Zhang, C; Zimányi, J; Zolin, L

    2012-10-12

    We report the measurement of direct photons at midrapidity in Au+Au collisions at √(s(NN))=200 GeV. The direct photon signal was extracted for the transverse momentum range of 4 GeV/cphotons from the inclusive photon sample. The direct photon nuclear modification factor R(AA) was calculated as a function of p(T) for different Au+Au collision centralities using the measured p+p direct photon spectrum and compared to theoretical predictions. R(AA) was found to be consistent with unity for all centralities over the entire measured p(T) range. Theoretical models that account for modifications of initial direct photon production due to modified parton distribution functions in Au and the different isospin composition of the nuclei predict a modest change of R(AA) from unity. They are consistent with the data. Models with compensating effects of the quark-gluon plasma on high-energy photons, such as suppression of jet-fragmentation photons and induced-photon bremsstrahlung from partons traversing the medium, are also consistent with this measurement. PMID:23102300

  13. Photon dosimetry using plastic scintillators in pulsed radiation fields

    Energy Technology Data Exchange (ETDEWEB)

    David L. Chichester; Brandon W. Blackburn; James T. Johnson; Scott W. Watson

    2007-04-01

    Simulations and experiments have been carried out to explore using a plastic scintillator as a dosimetry probe in the vicinity of a pulsed bremsstrahlung source in the range 4 to 20 MeV. Taking advantage of the tissue-equivalent properties of this detector in conjunction with the use of a fast digital signal processor near real-time dosimetry was shown to be possible. The importance of accounting for a broad energy electron beam in bremsstrahlung production, and photon scattering and build-up, in correctly interpreting dosimetry results at long stand-off distances is highlighted by comparing real world experiments with ideal geometry simulations. Close agreement was found between absorbed energy calculations based upon spectroscopic techniques and calculations based upon signal integration, showing a ratio between 10 MeV absorbed dose to 12 MeV absorbed dose of 0.66 at a distance of 91.4 m from the accelerator. This is compared with an idealized model simulation with a monoenergetic electron beam and without scattering, where the ratio was 0.46.

  14. 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

  15. Instrumental photon activation analysis of coal fly ashes using the internal standard method coupled with the standard addition method

    International Nuclear Information System (INIS)

    Multielement determinations of coal fly ashes (NIST SRM-1633a and BCR CRM-38) have been carried out by instrumental photon activation analysis using 30 MeV bremsstrahlung and the internal standard method coupled with the standard addition method. In these determinations, some major and minor constituent elements in the samples were properly used as effective internal standards. As a result, it was demonstrated that concentrations of 18 elements were determined accurately and precisely. Furthermore, a similar multielement determination has also been examined using 20 MeV bremsstrahlung. In this case, it was proved that better results can be achieved, because all interfering reactions were eliminated completely. (author) 14 refs.; 5 tabs

  16. Hadronic and partonic sources of direct photons in relativistic heavy-ion collisions

    CERN Document Server

    Linnyk, O; Steinert, T; Cassing, W; Bratkovskaya, E L

    2015-01-01

    The direct photon spectra and flow ($v_2$, $v_3$) in heavy-ion collisions at SPS, RHIC and LHC energies are investigated within a relativistic transport approach incorporating both hadronic and partonic phases -- the Parton-Hadron-String Dynamics (PHSD). In the present work, four extensions are introduced compared to our previous calculations: (i) going beyond the soft-photon approximation (SPA) in the calculation of the bremsstrahlung processes $meson+meson\\to meson+meson+\\gamma$, (ii) quantifying the suppression due to the Landau-Pomeranchuk-Migdal (LPM) coherence effect, (iii) adding the additional channels $V+N\\to N+\\gamma$ and $\\Delta\\to N+\\gamma$ and (iv) providing predictions for Pb+Pb collisions at $\\sqrt{s_{NN}}$ = 2.76 TeV. The first issue extends the applicability of the bremsstrahlung calculations to higher photon energies in order to understand the relevant sources in the region $p_T=0.5-1.5$~GeV, while the LPM correction turns out to be important for $p_T<0.4$~GeV in the partonic phase. The r...

  17. Characterization of γ-ray detectors using the photon tagger NEPTUN for energies up to 20 MeV

    Science.gov (United States)

    Schnorrenberger, L.; Savran, D.; Glorius, J.; Lindenberg, K.; Löher, B.; Pietralla, N.; Sonnabend, K.

    2014-01-01

    A new setup for the characterization of γ-ray detectors has been installed at the NEPTUN photon tagger facility of TU Darmstadt. The tagging technique used at NEPTUN provides a quasi monoenergetic photon source up to about 20 MeV by selecting single γ-ray energies within a bremsstrahlung spectrum. The energy is freely selectable by changing the tagging condition. The detector response function (DRF) of γ-ray detectors for quasi monoenergetic incident photons can be measured. This allows to investigate DRFs of various photon detectors as a function of the incident γ-ray energy. Simulations of DRFs that are intensively used in the analysis of nuclear physics experiments can be tested and compared to experimental data. The experimental setup is presented and the measurement of the DRF of a large volume high-purity Germanium detector is described as an example.

  18. Characterization of γ-ray detectors using the photon tagger NEPTUN for energies up to 20 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Schnorrenberger, L., E-mail: schnorrenberger@ikp.tu-darmstadt.de [Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstr. 9, D-64289 Darmstadt (Germany); Savran, D. [ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany); Frankfurt Institute for Advanced Studies FIAS, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany); Glorius, J. [Institut für Angewandte Physik, Goethe-Universität Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); Lindenberg, K. [Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstr. 9, D-64289 Darmstadt (Germany); Löher, B. [ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany); Frankfurt Institute for Advanced Studies FIAS, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany); Pietralla, N. [Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstr. 9, D-64289 Darmstadt (Germany); Sonnabend, K. [Institut für Angewandte Physik, Goethe-Universität Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany)

    2014-01-21

    A new setup for the characterization of γ-ray detectors has been installed at the NEPTUN photon tagger facility of TU Darmstadt. The tagging technique used at NEPTUN provides a quasi monoenergetic photon source up to about 20 MeV by selecting single γ-ray energies within a bremsstrahlung spectrum. The energy is freely selectable by changing the tagging condition. The detector response function (DRF) of γ-ray detectors for quasi monoenergetic incident photons can be measured. This allows to investigate DRFs of various photon detectors as a function of the incident γ-ray energy. Simulations of DRFs that are intensively used in the analysis of nuclear physics experiments can be tested and compared to experimental data. The experimental setup is presented and the measurement of the DRF of a large volume high-purity Germanium detector is described as an example.

  19. Ambiguities in the determination of the elementary pn→pnγ bremsstrahlung cross section

    International Nuclear Information System (INIS)

    Assuming an equilibrated fireball, we calculate γ yields in the incoherent limit and compare the results to the standard Weisskopf approach. The classical soft-photon approximation is shown to be slightly incorrect depending on excitation energy and gamma emission energy. Our calculation supports the results of a covariant photon production mechanism from p-n collisions in a vector (ω) and scalar (σ) meson exchange model, for beam energies >40 MeV/nucleon

  20. 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

  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. 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...

  3. Physics at High Energy Photon Photon Colliders

    OpenAIRE

    Chanowitz, Michael S.

    1994-01-01

    I review the physics prospects for high energy photon photon colliders, emphasizing results presented at the LBL Gamma Gamma Collider Workshop. Advantages and difficulties are reported for studies of QCD, the electroweak gauge sector, supersymmetry, and electroweak symmetry breaking.

  4. Photon Aided and Inhibited Tunneling of Photons

    CERN Document Server

    liu, xuele

    2013-01-01

    In the light of the interest in the transport of single photons in arrays of waveguides, fiber couplers, photonic crystals, etc., we consider the quantum mechanical process of the tunneling of photons through evanescently or otherwise coupled structures. We specifically examine the issue of tunneling between two structures when one structure already contains few photons. We demonstrate the possibility of both photon aided and inhibited tunneling of photons. The Bosonic nature of photons enhances the tunneling probability. We also show how the multiphoton tunneling probability can be either enhanced or inhibited due to the presence of photons. We find similar results for the higher order tunneling. Finally, we show that the presence of a squeezed field changes the nature of tunneling considerably.

  5. Weak localization of photon noise

    NARCIS (Netherlands)

    Scalia, Paolo S.; Muskens, Otto L.; Lagendijk, Ad

    2013-01-01

    We present an experimental study of coherent backscattering (CBS) of photon noise from multiple scattering media. We use a pseudothermal light source with a microsecond coherence time to produce a noise spectrum covering a continuous transition, from wave fluctuations to shot noise over several MHz.

  6. Jets in Photon-Photon Collisions

    OpenAIRE

    Fontannaz, M.

    1994-01-01

    We study jet production in photon-photon reactions at the next-to-leading logarithm accuracy. The discussion of the theoretical uncertainties and the role of the quark and gluon distributions in the photon is emphasized. The phenomenology at TRISTAN energies is discussed and predictions are made for LEP 200.

  7. Massive hidden photons as lukewarm dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Redondo, Javier [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Postma, Marieke [Nationaal Inst. voor Kernfysica en Hoge-Energiefysica (NIKHEF), Amsterdam (Netherlands)

    2008-11-15

    We study the possibility that a keV-MeV mass hidden photon (HP), i.e. a hidden sector U(1) gauge boson, accounts for the observed amount of dark matter. We focus on the case where the HP interacts with the standard model sector only through kinetic mixing with the photon. The relic abundance is computed including all relevant plasma effects into the photon's self-energy, which leads to a resonant yield almost independent of the HP mass. The HP can decay into three photons. Moreover, if light enough it can be copiously produced in stars. Including bounds from cosmic photon backgrounds and stellar evolution, we find that the hidden photon can only give a subdominant contribution to the dark matter. This negative conclusion may be avoided if another production mechanism besides kinetic mixing is operative. (orig.)

  8. Massive hidden photons as lukewarm dark matter

    CERN Document Server

    Postma, Marieke

    2008-01-01

    We study the possibility that a keV-MeV mass hidden photon (HP), i.e. a hidden sector U(1) gauge boson, accounts for the observed amount of dark matter. We focus on the case where the HP interacts with the standard model sector only through kinetic mixing with the photon. The relic abundance is computed including all relevant plasma effects into the photon's self-energy, which leads to a resonant yield almost independent of the HP mass. The HP can decay into three photons. Moreover, if light enough it can be copiously produced in stars. Including bounds from cosmic photon backgrounds and stellar evolution, we find that the hidden photon can only give a subdominant contribution to the dark matter. This negative conclusion may be avoided if another production mechanism besides kinetic mixing is operative.

  9. Monte Carlo simulation of small electron fields collimated by the integrated photon MLC

    Science.gov (United States)

    Mihaljevic, Josip; Soukup, Martin; Dohm, Oliver; Alber, Markus

    2011-02-01

    In this study, a Monte Carlo (MC)-based beam model for an ELEKTA linear accelerator was established. The beam model is based on the EGSnrc Monte Carlo code, whereby electron beams with nominal energies of 10, 12 and 15 MeV were considered. For collimation of the electron beam, only the integrated photon multi-leaf-collimators (MLCs) were used. No additional secondary or tertiary add-ons like applicators, cutouts or dedicated electron MLCs were included. The source parameters of the initial electron beam were derived semi-automatically from measurements of depth-dose curves and lateral profiles in a water phantom. A routine to determine the initial electron energy spectra was developed which fits a Gaussian spectrum to the most prominent features of depth-dose curves. The comparisons of calculated and measured depth-dose curves demonstrated agreement within 1%/1 mm. The source divergence angle of initial electrons was fitted to lateral dose profiles beyond the range of electrons, where the imparted dose is mainly due to bremsstrahlung produced in the scattering foils. For accurate modelling of narrow beam segments, the influence of air density on dose calculation was studied. The air density for simulations was adjusted to local values (433 m above sea level) and compared with the standard air supplied by the ICRU data set. The results indicate that the air density is an influential parameter for dose calculations. Furthermore, the default value of the BEAMnrc parameter 'skin depth' for the boundary crossing algorithm was found to be inadequate for the modelling of small electron fields. A higher value for this parameter eliminated discrepancies in too broad dose profiles and an increased dose along the central axis. The beam model was validated with measurements, whereby an agreement mostly within 3%/3 mm was found.

  10. Electron, photon, and ion beams from the relativistic interaction of Petawatt laser pulses with solid targets

    International Nuclear Information System (INIS)

    In recent Petawatt laser experiments at Lawrence Livermore National Laboratory, several hundred joules of 1 μm laser light in 0.5-5.0-ps pulses with intensities up to 3x1020 W cm-2 were incident on solid targets and produced a strongly relativistic interaction. The energy content, spectra, and angular patterns of the photon, electron, and ion radiations have all been diagnosed in a number of ways, including several novel (to laser physics) nuclear activation techniques. About 40%-50% of the laser energy is converted to broadly beamed hot electrons. Their beam centroid direction varies from shot to shot, but the resulting bremsstrahlung beam has a consistent width. Extraordinarily luminous ion beams (primarily protons) almost precisely normal to the rear of various targets are seen--up to 3x1013 protons with kTion∼several MeV representing ∼6% of the laser energy. Ion energies up to at least 55 MeV are observed. The ions appear to originate from the rear target surfaces. The edge of the ion beam is very sharp, and collimation increases with ion energy. At the highest energies, a narrow feature appears in the ion spectra, and the apparent size of the emitting spot is smaller than the full back surface area. Any ion emission from the front of the targets is much less than from the rear and is not sharply beamed. The hot electrons generate a Debye sheath with electrostatic fields of order MV per micron, which apparently accelerate the ions. (c) 2000 American Institute of Physics

  11. Transverse target spin asymmetry in inclusive DIS with two-photon exchange

    Energy Technology Data Exchange (ETDEWEB)

    Andrei Afanasev; Mark Strikman; Christian Weiss

    2007-09-06

    We study the transverse target spin dependence of the cross section for the inclusive electron-nucleon scattering with unpolarized beam. Such dependence is absent in the one-photon exchange approximation (Christ-Lee theorem) and arises only in higher orders of the QED expansion, from the interference of one-photon and absorptive two-photon exchange amplitudes as well as from real photon emission (bremsstrahlung). We demonstrate that the transverse spin-dependent two-photon exchange cross section is free of QED infrared and collinear divergences. We argue that in DIS kinematics the transverse spin dependence should be governed by a "parton-like" mechanism in which the two-photon exchange couples mainly to a single quark. We calculate the normal spin asymmetry in an approximation where the dominant contribution arises from quark helicity flip due to interactions with non-perturbative vacuum fields (constituent quark picture) and is proportional to the quark transversity distribution in the nucleon. Such helicity-flip processes are not significantly Sudakov-suppressed if the infrared scale for gluon emission in the photon-quark subprocess is of the order of the chiral symmetry breaking scale, mu^2_chiral>>Lambda^2_QCD. We estimate the asymmetry in the kinematics of the planned Jefferson Lab Hall A experiment to be of the order 10^-4, with different sign for proton and neutron. We also comment on the spin dependence in the limit of soft high-energy scattering.

  12. 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

  13. Initial-State Bremsstrahlung versus Final-State Hydrodynamic Sources of Azimuthal Harmonics in p+A at RHIC and LHC

    CERN Document Server

    Gyulassy, Miklos; Vitev, Ivan; Biro, Tamas S

    2014-01-01

    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 azimuthal $v_n\\{2m\\}(p_T)$ ``transeverse flow'' harmonics in $p+Pb$ and $Pb+Pb$ at LHC have challenged the uniqueness of local equilibrium ``perfect fluid'' interpretations of those data. We report results at QM14 on azimuthal harmonics associated with 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.

  14. 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.

  15. Noise affecting photon pair generation in silicon wire waveguide

    CERN Document Server

    Clemmen, S; Bogaerts, W; Baets, R; Emplit, Ph; Massar, S

    2011-01-01

    We study quantitatively the weak source of noise that is present when correlated photons are produced via four wave mixing in silicon nanophotonic waveguides. First, we deduce the amont of noise from the dependance of the photon flux on the pump power. Second we caracterise the spectrum of the noise and of the pairs of photons which shows that the noise is due to a scattering of photons by a thermal bath. Third we show that the photon flux (noise plus pairs) is essentially instantaneous, and cannot therefore be attributed to carrier induced effects. We discuss our results and compare them to photon pair generation in silica fibers.

  16. Quantum Logic with Cavity Photons From Single Atoms

    Science.gov (United States)

    Holleczek, Annemarie; Barter, Oliver; Rubenok, Allison; Dilley, Jerome; Nisbet-Jones, Peter B. R.; Langfahl-Klabes, Gunnar; Marshall, Graham D.; Sparrow, Chris; O'Brien, Jeremy L.; Poulios, Konstantinos; Kuhn, Axel; Matthews, Jonathan C. F.

    2016-07-01

    We demonstrate quantum logic using narrow linewidth photons that are produced with an a priori nonprobabilistic scheme from a single 87Rb atom strongly coupled to a high-finesse cavity. We use a controlled-not gate integrated into a photonic chip to entangle these photons, and we observe nonclassical correlations between photon detection events separated by periods exceeding the travel time across the chip by 3 orders of magnitude. This enables quantum technology that will use the properties of both narrow-band single photon sources and integrated quantum photonics.

  17. Intrinsically narrowband pair photon generation in microstructured fibres

    OpenAIRE

    Alibart, Olivier; Clark, Alex; Bell, Bryn; Fulconis, Jérémie; M Halder, Matthäus; Cemlyn, Ben; Xiong, Chunle; J Wadsworth, William; G Rarity, John

    2011-01-01

    In this paper we study the tailoring of photon spectral properties generated by four-wave mixing in a birefringent photonic crystal fibre (PCF). The aim is to produce intrinsically narrow-band photons and hence to achieve high non-classical interference visibility and generate high fidelity entanglement without any requirement for spectral filtering, leading to high effective detection efficiencies. We show unfiltered Hong-Ou-Mandel interference visibilities of 77% between photons from the sa...

  18. n-p-γ Bremsstrahlung below 210 MeV bombarding energy

    International Nuclear Information System (INIS)

    The experimental knowledge of the neutron-proton-gamma below 210 MeV bombarding energy is discussed. The knowledge of this process is poor and due to the small intensity and bad resolution of the neutron beams. In this energy region the one-pion exchange is the main source of high energy photons. The different models proposed to explain the process are summarized. As at higher bombarding energies heavier mesons are also expected to couple with the photons, the investigation of the elementary process above the pion threshold is suggested

  19. Measurement of direct photon emission in the K(L) ---> pi+ pi- gamma decay mode

    Energy Technology Data Exchange (ETDEWEB)

    Abouzaid, E.; /Chicago U., EFI; Arenton, M.; /Virginia U.; Barker, A.R.; /Colorado U.; Bellantoni, L.; /Fermilab; Bellavance, A.; /Rice U.; Blucher, E.; /Chicago U., EFI; Bock,; /Fermilab; Cheu, E.; /Arizona U.; Coleman, R.; /Fermilab; Corcoran, M.D.; /Rice U.; Corti, G.; /Virginia U. /Wisconsin U., Madison

    2006-04-01

    In this paper the KTeV collaboration reports the analysis of 112.1 x 10{sup 3} candidate K{sub L} {yields} {pi}{sup +}{pi}{sup -}{gamma} decays including a background of 671 {+-} 41 events with the objective of determining the photon production mechanisms intrinsic to the decay process. These decays have been analyzed to extract the relative contributions of the Cp violating bremsstrahlung process and the CP conserving M1 and CP violating E1 direct photon emission processes. The M1 direct photon emission amplitude and its associated vector form factor parameterized as |{bar g}{sub M1}|(1 + a{sub 1}/a{sub 2}/(M{sub {rho}}{sup 2}-M{sub K}{sup 2}) + 2M{sub K}E{sub {gamma}}) have been measured to be |{bar g}{sub M1}| = 1.198 {+-} 0.035(stat) {+-} 0.086(syst) and a{sub 1}/a{sub 2} = =0.738 {+-} 0.007(stat) {+-} 0.018(syst) GeV{sup 2}/c{sup 2} respectively. An upper limit for the CP violating E1 direct emission amplitude |g{sub E1}| {le} 0.1 (90%CL) has been found. The overall ratio of direct photon emission (DE) to total photon emission including the bremsstrahlung process (IB) has been determined to be DE/(DE + IB) = 0.689 {+-} 0.021 for E{sub {gamma}} {ge} 20 MeV.

  20. Photon-Photon Collisions -- Past and Future

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC

    2005-12-02

    I give a brief review of the history of photon-photon physics and a survey of its potential at future electron-positron colliders. Exclusive hadron production processes in photon-photon and electron-photon collisions provide important tests of QCD at the amplitude level, particularly as measures of hadron distribution amplitudes. There are also important high energy {gamma}{gamma} and e{gamma} tests of quantum chromodynamics, including the production of jets in photon-photon collisions, deeply virtual Compton scattering on a photon target, and leading-twist single-spin asymmetries for a photon polarized normal to a production plane. Since photons couple directly to all fundamental fields carrying the electromagnetic current including leptons, quarks, W's and supersymmetric particles, high energy {gamma}{gamma} collisions will provide a comprehensive laboratory for Higgs production and exploring virtually every aspect of the Standard Model and its extensions. High energy back-scattered laser beams will thus greatly extend the range of physics of the International Linear Collider.

  1. The myth of the photon

    CERN Document Server

    Marshall, T W; Marshall, Trevor W.; Santos, Emilio

    1997-01-01

    We have shown that all "single-photon" and "photon-pair" states, produced in atomic transitions, and in parametric down conversion by nonlinear optical crystals, may be represented by positive Wigner densities of the relevant sets of mode amplitudes. The light fields of all such states are represented as a real probability ensemble (not a pseudoensemble) of solutions of the unquantized Maxwell equation. The local realist analysis of light-detection events in spatially separated detectors requires a theory of detection which goes beyond the currently fashionable single-mode photon theory. It also requires us to recognize that there is a payoff between detector efficiency and signal-noise discrimination. Using such a theory, we have demonstrated that all experimental data, both in atomic cascades and in parametric down conversions, have a consistent local realist explanation based on the unquantized Maxwell field. Finally we discuss current attempts to demonstrate Schroedinger-cat-like behaviour of microwave ca...

  2. Bright Solid State Source of Photon Triplets

    CERN Document Server

    Khoshnegar, Milad; Predojević, Ana; Dalacu, Dan; Prilmüller, Maximilian; Lapointe, Jean; Wu, Xiaohua; Tamarat, Philippe; Lounis, Brahim; Poole, Philip; Weihs, Gregor; Majedi, Hamed

    2015-01-01

    Producing advanced quantum states of light is a priority in quantum information technologies. While remarkable progress has been made on single photons and photon pairs, multipartite correlated photon states are usually produced in purely optical systems by post-selection or cascading, with extremely low efficiency and exponentially poor scaling. Multipartite states enable improved tests of the foundations of quantum mechanics as well as implementations of complex quantum optical networks and protocols. It would be favorable to directly generate these states using solid state systems, for better scaling, simpler handling, and the promise of reversible transfer of quantum information between stationary and flying qubits. Here we use the ground states of two optically active coupled quantum dots to directly produce photon triplets. The wavefunctions of photogenerated excitons localized in these ground states are correlated via molecular hybridization and Coulomb interactions. The formation of a triexciton leads...

  3. Two-photon interference : spatial aspects of two-photon entanglement, diffraction, and scattering

    NARCIS (Netherlands)

    Peeters, Wouter Herman

    2010-01-01

    This dissertation contains scientific research within the realm of quantum optics, which is a branch of physics. An experimental and theoretical study is made of two-photon interference phenomena in various optical systems. Spatially entangled photon pairs are produced via the nonlinear optical proc

  4. Physics with photons at the ATLAS experiment

    CERN Document Server

    Pérez-Réale, V

    2008-01-01

    ATLAS is a general-purpose detector due to start operation next year at the Large Hadron Collider (LHC). The LHC will collide pairs of protons at a centre-of-mass energy of 14 TeV, with a bunch-crossing frequency of 40 MHz, and luminosities up to L = 10^34 cm^-2s^-1. The identification of photons is crucial for the study of a number of physics channels, including the search for a Higgs boson decaying to photon pairs, and measurements of direct production of single photons and photon pairs. Events containing true high-p_T photons must be selected with high efficiency, while rejecting the bulk of high-p_T jet events produced with enormously larger rate through QCD processes. The photon--photon and photon--jet channels are interesting in their own right, allowing the study of QCD at high energy. It is also essential to understand these proceses as the dominant background in the search for certain new physics processes, notably the production and decay of Higgs bosons to photon pairs. There are large uncertaintin...

  5. Search for dark matter and graviton produced in association with a photon in pp collisions at $\\sqrt{s}=13~\\mathrm{TeV}$ with an integrated luminosity of $12.9~\\mathrm{fb}^{-1}$

    CERN Document Server

    CMS Collaboration

    2016-01-01

    A search is conducted for dark matter pair-production and for graviton production predicted by the ADD large extra dimensions model in a final state with a photon and missing transverse energy in pp collisions at $\\sqrt{s}=13~\\mathrm{TeV}$. Data taken by the CMS experiment in 2016 corresponding to an integrated luminosity of $12.9~\\mathrm{fb}^{-1}$ is analyzed. A Poisson counting technique is used to assess a potential excess of events with respect to background, estimated through simulation and data-driven methods. No such excess is observed. The results of the searches are interpreted as exclusion limits in the model parameter spaces.

  6. Photonic Crystals Towards Nanoscale Photonic Devices

    CERN Document Server

    Lourtioz, Jean-Michel; Berger, Vincent; Gérard, Jean-Michel; Maystre, Daniel; Tchelnokov, Alexis

    2005-01-01

    Just like the periodical crystalline potential in solid-state crystals determines their properties for the conduction of electrons, the periodical structuring of photonic crystals leads to envisioning the possibility of achieving a control of the photon flux in dielectric and metallic materials. The use of photonic crystals as a cage for storing, filtering or guiding light at the wavelength scale thus paves the way to the realisation of optical and optoelectronic devices with ultimate properties and dimensions. This should contribute toward meeting the demands for a greater miniaturisation that the processing of an ever increasing number of data requires. Photonic Crystals intends at providing students and researchers from different fields with the theoretical background needed for modelling photonic crystals and their optical properties, while at the same time presenting the large variety of devices, from optics to microwaves, where photonic crystals have found applications. As such, it aims at building brid...

  7. Photonic Crystals Towards Nanoscale Photonic Devices

    CERN Document Server

    Lourtioz, Jean-Michel; Berger, Vincent; Gérard, Jean-Michel; Maystre, Daniel; Tchelnokov, Alexei; Pagnoux, Dominique

    2008-01-01

    Just like the periodical crystalline potential in solid state crystals determines their properties for the conduction of electrons, the periodical structuring of photonic crystals leads to envisioning the possibility of achieving a control of the photon flux in dielectric and metallic materials. The use of photonic crystals as cages for storing, filtering or guiding light at the wavelength scale paves the way to the realization of optical and optoelectronic devices with ultimate properties and dimensions. This will contribute towards meeting the demands for greater miniaturization imposed by the processing of an ever increasing number of data. Photonic Crystals will provide students and researchers from different fields with the theoretical background required for modelling photonic crystals and their optical properties, while at the same time presenting the large variety of devices, ranging from optics to microwaves, where photonic crystals have found application. As such, it aims at building bridges between...

  8. A search for bremsstrahlung solar axions using the Majorana low-background BEGe detector at Kimballton (MALBEK)

    CERN Document Server

    Abgrall, N; Avignone, F T; Barabash, A S; Bertrand, F E; Boswell, M; Brudanin, V; Busch, M; Caldwell, A S; Chan, Y-D; Christofferson, C D; Combs, D C; Cooper, R J; Creswick, R J; Detwiler, J A; Doe, P J; Efremenko, Yu; Egorov, V; Elliott, S R; Fast, J E; Finnerty, P; Giovanetti, G K; Goett, J; Green, M P; Gruszko, J; Guiseppe, V E; Gusev, K; Hegai, A; Henning, R; Hoppe, E W; Howard, S; Howe, M A; Keeter, K J; Kidd, M F; Knecht, A; Kochetov, O; Konovalov, S I; Kouzes, R T; LaFerriere, B D; Leon, J; Leviner, L E; Loach, J C; MacMullin, J; MacMullin, S; Marino, M G; Martin, R D; Mertens, S; Orrell, J L; O'Shaughnessy, C; Overman, N R; Phillips, D G; Poon, A W P; Pushkin, K; Radford, D C; Robertson, R G H; Ronquest, M C; Schubert, A G; Shanks, B; Shirchenko, M; Snavely, K J; Snyder, N; Steele, D; Suriano, A M; Thompson, J; Timkin, V; Varner, R L; Vasilyev, S; Vetter, K; Vorren, K; White, B R; Wilkerson, J F; Xu, W; Yakushev, E; Young, A R; Yu, C H; Yumatov, V

    2014-01-01

    A low-background, high-purity germanium detector has been used to search for evidence of low-energy, bremsstrahlung-generated solar axions. An upper bound of $1.36\\times 10^{-11}$ $(95\\% CL)$ is placed on the direct coupling of DFSZ model axions to electrons. The prospects for the sensitivity of the Majorana Demonstrator array of point-contact germanium detectors to solar axions are discussed in the context of the model-independent annual modulation due to the seasonal variation of the earth-sun distance.

  9. Photon-Photon Interactions via Rydberg Blockade

    OpenAIRE

    Fleischhauer, Michael; Pohl, Thomas; Gorshkov, Alexey Vyacheslavovich; Otterbach, Johannes; Lukin, Mikhail D.

    2011-01-01

    We develop the theory of light propagation under the conditions of electromagnetically induced transparency (EIT) in systems involving strongly interacting Rydberg states. Taking into account the quantum nature and the spatial propagation of light, we analyze interactions involving few-photon pulses. We demonstrate that this system can be used for the generation of nonclassical states of light including trains of single photons with an avoided volume between them, for implementing photon-phot...

  10. Aspherical Photon and Anti-Photon Surfaces

    CERN Document Server

    Gibbons, G W

    2016-01-01

    In this note we identify photon surfaces and anti-photon surfaces in some physically interesting spacetimes, which are not spherically symmetric. All of our examples solve physically reasonable field equations, including for some cases the vacuum Einstein equations, albeit they are not asymptotically flat. Our examples include the vacuum C-metric, the Melvin solution of Einstein-Maxwell theory and generalisations including dilaton fields. The (anti-)photon surfaces are not round spheres, and the lapse function is not always constant.

  11. Initial electron energy spectra in water irradiated by photons with energies to 1 GeV

    International Nuclear Information System (INIS)

    This work was undertaken to provide basic physical data for use in the dosimetry of high-energy photons. Present and future sources of such photons are described, and the relevant literature is reviewed and summarized. Calculations were performed with a Monte Carlo computer code, PHOEL-3, which is also described. Tables of initial electron and positron energies are presented for monoenergetic photons undergoing single interactions in water. Photon energies to 1 GeV are treated. The code treats explicitly the production of electron-positron pairs, Compton scattering, photoelectric absorption, and the emission of Auger electrons following the occurrence of K-shell vacancies in oxygen. The tables give directly the information needed to specify the absolute single-collision kerma in water, which approximates tissue, at each photon energy. Results for continuous photon energy spectra can be obtained by using linear interpolation with the tables. (Continuous spectra can also be used directly in PHOEL-3.) The conditions under whch first-collision kerma approximate absorbed dose are discussed. A formula is given for estimating bremsstrahlung energy loss, one of the principal differences between kerma and absorbed dose in practical cases. 31 references, 4 figures, 18 tables

  12. Empirical Emission Functions for LPM Suppression of Photon Emission from Quark-Gluon Plasma

    CERN Document Server

    Sastry, S

    2003-01-01

    The LPM suppression of photon emission rates from the quark gluon plasma have been studied at different physical conditions of the plasma given by temperature and chemical potentials.The integral equation for the transverse vector function (f(p_t)) consisting of multiple scattering effects is solved for the parameter set {p,k,kappa,T}, for bremsstrahlung and AWS processes. The peak positions of these distributions depend only on the dynamical variable x=(T/kappa)|1/p-1/(p+k)|. Integration over these distributions multiplied by x^2 factor also depends on this variable x,leading to a unique global emission function g(x) for all parameters. Empirical fits to this dimensionless emission function, g(x), are obtained. The photon emission rate calculations with LPM suppression effects reduce to one dimensional integrals involving folding over the empirical g(x) function with appropriate distribution functions and the kinematic factors. Using this approach, the suppression factors for both bremsstrahlung and AWS have...

  13. Quantum Computing using Photons

    Science.gov (United States)

    Elhalawany, Ahmed; Leuenberger, Michael

    2013-03-01

    In this work, we propose a theoretical model of two-quantum bit gates for quantum computation using the polarization states of two photons in a microcavity. By letting the two photons interact non-resonantly with four quantum dots inside the cavity, we obtain an effective photon-photon interaction which we exploit for the implementation of an universal XOR gate. The two-photon Hamiltonian is written in terms of the photons' total angular momentum operators and their states are written using the Schwinger representation of the total angular momentum.

  14. 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

  15. 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...

  16. Photon and proton induced fission on heavy nuclei at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Andrade-II, E.; Karapetyan, G.S.; Deppman, A.; Guimaraes, V. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Fisica; Balabekyan, A.R. [Yerevan State University, Alex Manoogian 1, Yerevan (Armenia); Demekhina, N.A. [Yerevan Physics Institute, Alikhanyan Brothers 2, Yerevan (Armenia); Joint Institute for Nuclear Research (JINR), Flerov Laboratory of Nuclear Reactions (LNR), Moscow (Russian Federation)

    2014-07-01

    We present an analysis of fission induced by intermediate energy protons or photons on actinides. The 660 MeV proton induced reactions are on {sup 241}Am, {sup 238}U, and {sup 237}Np targets and the Bremsstrahlung-photons with end-point energies at 50 MeV and 3500 MeV are on {sup 232}Th and {sup 238}U targets. The study was performed by means of the Monte Carlo simulation code CRISP. A multimodal fission extension was added to the code within an approach which accounts for the contribution of symmetric and asymmetric fission. This procedure allowed the investigation of fission cross sections, fissility, number of evaporated nucleons and fission-fragment charge distributions. The comparison with experimental data show a good agreement between calculations and experiments. (author)

  17. 6 MV photon beam modeling for Varian Clinac iX using GEANT4 virtual jaw

    CERN Document Server

    Kim, Byung Yong; Kim, Dong Ho; Baek, Jong Geun; Moon, Su Ho; Rho, Gwang Won; Kang, Jeong Ku; Kim, Sung Kyu

    2015-01-01

    Most virtual source models (VSM) use beam modeling, with the exception of the patient-dependent secondary collimator (jaw). Unlike other components of the treatment head, the jaw absorbs many photons generated by the bremsstrahlung, which decreases the efficiency of the simulation. In the present study, a new method of beam modeling using a virtual jaw was applied to improve the calculation efficiency of VSM. The results for the percentage depth dose and profile of the virtual jaw VSM calculated in a homogeneous water phantom agreed with the measurement results for the CC13 cylinder type ion chamber within an error rate of 2%, and the 80 to 20% penumbra width agreed with the measurement results within an error of 0.6 mm. Compared with the existing VSM, in which a great number of photons are absorbed, the calculation efficiency of the VSM using the virtual jaw was expected to increase by approximately 67%.

  18. Possibility to study photon scattering by proton in the reaction ep→epγ

    International Nuclear Information System (INIS)

    A theoretical possibility to determine proton Compton scattering cross section from the reaction ep→epγ is studied in the kinematics with a small transversal momentum transfer in the electron leg. With the exception of the region of forward photon directions and extreme photon energies close to the maximal ones or zero, registration of the particles γ and p in the final state can enable one to distinguish subprocess of the Compton scattering from the electron bremsstrahlung background and measure in details energy and angular dependence of the γp-scattering cross section. Counting rate expected with a storage ring like NEP having the luminosity L≅2x1035 cm-2xs-1 as projected is ∼103 events/hour. Such measurements might help to determine proton polarizabilities with high statistical accuracy. 21 refs.; 4 figs

  19. Depth dose and angular dose distribution experiments with high energy electron-photon radiation

    International Nuclear Information System (INIS)

    India's first synchrotron radiation source, Indus-1, is commissioned at the Centre for Advanced Technology (CAT), Indore. Radiation environment of this facility is quite different in comparison to that of nuclear or irradiator facilities and proton or heavy ion accelerator facilities. The primary particle accelerated being the electron, the radiation environment mainly comprises of Bremsstrahlung photons followed by photo-neutrons, whereas electron contamination too exists within the containment area. Due to the complex nature of the radiation viz. high energy, broad energy spectrum, pulsed, mixed field, sharp angular distribution etc. quantification of radiation dose becomes a difficult task. In this paper, experiments on depth dose and angular dose distribution done with 450 MeV electron-photon radiation are described

  20. Production of relativistic positronium in collisions of photons and electrons with nuclei and atoms

    CERN Document Server

    Gevorkyan, S R; Schiller, A; Serbo, V G; Tarasov, A V

    1998-01-01

    We consider the production of ultrarelativistic positronium (Ps) in $\\gamma A is an atom or a nucleus with charge $Ze$. For the photoproduction of para- and ortho-Ps and the electroproduction of para-Ps we obtain the most complete description compared with previous works. It includes high order $Z \\alpha$ corrections and polarization effects. The accuracy of the obtained cross sections is determined by omitted terms of the order of the inverse Ps Lorentz factor squared. The studied high order multi-photon electroproduction of ortho-Ps dominates for the collision of electrons with heavy atoms over the bremsstrahlung production from the electron via a virtual photon proposed by Holvik and Olsen. Our results complete and correct the studies of those authors.

  1. Controllable photon source

    Science.gov (United States)

    Oszetzky, Dániel; Nagy, Attila; Czitrovszky, Aladár

    2006-10-01

    We have developed our pervious experimental setup using correlated photon pairs (to the calibration of photo detectors) to realize a controllable photon source. For the generation of such photon pairs we use the non-linear process of parametric down conversion. When a photon of the pump beam is incident to a nonlinear crystal with phase matching condition, a pair of photons (signal and idler) is created at the same time with certain probability. We detect the photons in the signal beam with a single photon counting module (SPCM), while delaying those in the idler beam. Recently we have developed a fast electronic unit to control an optical shutter (a Pockels cell) placed to the optical output of the idler beam. When we detect a signal photon with the controlling electronic unit we are also able to open or close the fast optical shutter. Thus we can control which idler photons can propagate through the Pockels cell. So with this photon source we are able to program the number of photons in a certain time window. This controllable photon source that is able to generate a known number of photons with specified wavelength, direction, and polarization could be useful for applications in high-accuracy optical characterisation of photometric devices at the ultra-low intensities. This light source can also serve as a standard in testing of optical image intensifiers, night vision devices, and in the accurate measurement of spectral distribution of transmission and absorption in optical materials.

  2. Fission and fragmentation of silver and bromine nuclei by 1-6 GeV energy photons

    International Nuclear Information System (INIS)

    Fission and fragmentation of silver and bromine nuclei induced by bremsstrahlung photons in the maximum energy range of 1-6 GeV are studied. A special technique of nuclear emulsion for the highly ionizing nuclear fragment detection is used in the discrimination between nuclear fission and fragmentation events. Films of Ilford-KO nuclear emulsion (approximatelly 1020 atoms/cm2 of Ag, Br) which had been exposed to bremsstrahlung beams in 'Deutsches Elektronen Synchrotron' (DESY, Hamburg) with total doses of approximatelly 1011 equivalent photons are used. Through a detailed analysis of range, angular and angle between fragment distributions, and empirical relations which permit to estimate nuclear fragment energy, range and velocity, the discrimination between fission and fragmentation events is made. Results related to fragment range distribution, angular distribution, distribution of angle between fragments, distribution of ratio between ranges, velocity distributions, forward/backward ratio, fission and fragmentation cross sections, nuclear fissionability and ternary fission frequency are presented and discussed. The results show that the mean photofragmentation cross section in the internal 1-6 GeV (0,09+-0,02mb) is significant when compared to the photofission (0,29+-0,05mb). It is also shown that the mean photofission cross section between 1 and 6 GeV is great by a factor of approximatelly 10 when compared to the foreseen by the cascade-evaporation nuclear model for monoenergetic photons of 0,6 GeV. (L.C.)

  3. The 750 GeV excess from photon-photon and quark-quark processes

    CERN Document Server

    Mandal, Tanumoy; Enberg, Rikard; Ingelman, Gunnar

    2016-01-01

    The observed excess in the diphoton mass spectrum around 750 GeV at the 13 TeV LHC possibly indicates the presence of a photonphilic resonance. We show that the excess can be explained by a scalar of the type involved in Bekenstein's framework for varying electromagnetic coupling theories. The scalar, in our model, couples dominantly to photons and is mainly produced by the quark-quark fusion at the LHC. In addition, it can also be produced in photon-photon fusion. Our model has only two free parameters, the mass of the scalar and the scale of the new physics, which are fixed by the LHC excess to 750 GeV and 1.5 - 2 TeV, respectively. The scalar has a large three-body decay to a fermion pair and a photon, which provides an interesting search channel with a dilepton-photon resonance around 750 GeV.

  4. 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...

  5. Covariance mapping of two-photon double core hole states in C 2 H 2 and C 2 H 6 produced by an x-ray free electron laser

    International Nuclear Information System (INIS)

    Few-photon ionization and relaxation processes in acetylene (C2H2) and ethane (C2H6) were investigated at the linac coherent light source x-ray free electron laser (FEL) at SLAC, Stanford using a highly efficient multi-particle correlation spectroscopy technique based on a magnetic bottle. The analysis method of covariance mapping has been applied and enhanced, allowing us to identify electron pairs associated with double core hole (DCH) production and competing multiple ionization processes including Auger decay sequences. The experimental technique and the analysis procedure are discussed in the light of earlier investigations of DCH studies carried out at the same FEL and at third generation synchrotron radiation sources. In particular, we demonstrate the capability of the covariance mapping technique to disentangle the formation of molecular DCH states which is barely feasible with conventional electron spectroscopy methods

  6. Jet and hadron production in photon-photon collisions

    OpenAIRE

    Soldner-Rembold, Stefan

    1999-01-01

    Di-jet and inclusive charged hadron production cross-sections measured in photon-photon collisions by OPAL are compared to NLO pQCD calculations. Jet shapes measured in photon-photon scattering by OPAL, in deep-inelastic ep scattering by H1 and in photon-proton scattering by ZEUS are shown to be consistent in similar kinematic ranges. New results from TOPAZ on prompt photon production in photon-photon interactions are presented.

  7. Polychromatic photon absorptiometry

    International Nuclear Information System (INIS)

    Photon absorptiometry is a popular method for determining the mineral contents of body components, such as bone. The single photon absorptiometry introduced by Cameron and Sorenson (1963) has become widely accepted. Dichromatic absorptiometry using two monochromatic photon beams was recently introduced by Witt and Mazess (1978). The photon absorptiometry described here involves as unlimited number of monochromatic photon beams and component materials. Formulation for this polychromatic photon absorptiometry (PCPA) can be described as the linear algebraic expression using the least square method, by measuring photon intensities for each photon beam attenuated by the sample. For example, the lead content of lead-containing acrylic resin sheets was measured by PCPA using fluorescent X-ray from appropriate secondary targets which had been excited by white X-rays. The values obtained were in good agreement with the real contents and proved accurate to within 1%. (author)

  8. Photonic Design for Photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Kosten, E.; Callahan, D.; Horowitz, K.; Pala, R.; Atwater, H.

    2014-08-28

    We describe photonic design approaches for silicon photovoltaics including i) trapezoidal broadband light trapping structures ii) broadband light trapping with photonic crystal superlattices iii) III-V/Si nanowire arrays designed for broadband light trapping.

  9. Nonlinear Integrated Microwave Photonics

    OpenAIRE

    Marpaung, David; Eggleton, Benjamin J.

    2013-01-01

    Harnessing nonlinear optical effects in a photonic chip scale has been proven useful for a number of key applications in optical communications. Microwave photonics can also benefit from the adoption of such a technology, creating a new concept of nonlinear integrated microwave photonics. Here, we discuss the potential of on-chip nonlinear processing towards the creation of robust and multifunctional microwave photonic (MWP) processors. We also highlight key recent results in the field, inclu...

  10. Photonics. Present and future

    OpenAIRE

    K. I. Silakov; T. T. Silakova

    2011-01-01

    Short review of the literature in the field of photonics, which reflects the new technology of ultra-compact optical communications components, the use of generators to transmission light instead of wires is represented. This is - silicon photonics - finding ways to use semiconductor components and of standard semiconductor technology to create optical devices, silicon photonics - the creation of a silicon photonic waveguide. All of these components can be used in the construction of computer...

  11. Switching to Photonics

    OpenAIRE

    Hinton, Harvard S.

    1992-01-01

    The use of hardware that exploits the interplay of photons and electrons to switch voice, data, and video is discussed. The two directions being taken by current research-guided-wave and free-space photonics-are examined. Photonic time-slot interchanges are described. Multidivisional fabrics, based on a combination of space-division and time-division multiplexing, are considered, as is the wavelength-division-based photonic packet switch, another kind of multidimensional fabric. The use of se...

  12. Characterisation of silicon photonics devices

    OpenAIRE

    Leung, David

    2013-01-01

    Silicon based integrated circuits has been dominating the electronics technology industry in the last few decades. As the telecommunications and the computing industry slowly converges together, the need for a material to build photonics integrated circuits (PIC) that can be cost-effective and be produced in mass market has become very important. This thesis describes and outlines the characteristics of high index contrast waveguides as a building blocks that can be designed, fabricated a...

  13. New information on photon fragmentation functions

    Energy Technology Data Exchange (ETDEWEB)

    Klasen, Michael; Koenig, Florian [Westfaelische Wilhelms-Universitaet Muenster, Institut fuer Theoretische Physik, Muenster (Germany)

    2014-08-15

    Thermal photons radiated in heavy-ion collisions represent an important signal for a recently discovered new state of matter, the deconfined quark-gluon plasma. However, a clean identification of this signal requires precise knowledge of the prompt photons produced simultaneously in hard collisions of quarks and gluons, mostly through their fragmentation. In this paper, we demonstrate that PHENIX data on photons produced in proton-proton collisions with low transverse momenta allow one to extract new information on this fragmentation process. While existing data do not yet convincingly favor one parameterization (BFG II) over the two other frequently used photon fragmentation functions (BFG I and GRV NLO), the data sets recorded by PHENIX and STAR at BNL RHIC in 2013 with tenfold higher statistics should allow for such an analysis. (orig.)

  14. UK photonics in defence and security

    Science.gov (United States)

    Gracie, C.; Tooley, I.; Wilson, A.

    2008-10-01

    The UK is globally recognised as strong in Photonics. However its Photonics sector is fragmented and the size and sectors of interest have not previously been established. The UK government has instigated the formation of the Photonics Knowledge Transfer Network (PKTN) to bring the Photonics community together. The UK features in Defence & Security; Communications; Measurement; Medical Technology; Lighting; Solar Energy; Information Technology and Flat Panels. This expertise is scattered through out the UK in geographic areas each with a breadth of Photonic interests. The PKTN has mapped the UK capability in all Photonics sectors. This paper will present the capability of the Companies, Research Institutions and Infrastructure making up the Defence & Security Photonics scene in the UK. Large Defence companies in the UK are well known throughout the world. However, there are a large number of SMEs, which may not be as well known in the supply chain. These are being actively encouraged by the UK MoD to engage with the Defence & Security Market and shall be discussed here. The presentation will reference a number of organisations which help to fund and network the community, such as the Defence Technology Centres. In addition the Roadmap for Defence & Security in the UK, produced for the UK Photonics Strategy (July 2006) by the Scottish Optoelectronics Association will be described and the plans in taking it forward under the PKTN will be revealed.

  15. Measuring photon-photon interactions via photon detection

    OpenAIRE

    Macovei, Mihai A.

    2010-01-01

    The strong non-linearity plays a significant role in physics, particularly, in designing novel quantum sources of light and matter as well as in quantum chemistry or quantum biology. In simple systems, the photon-photon interaction can be determined analytically. However, it becomes challenging to obtain it for more compex systems. Therefore, we show here how to measure strong non-linearities via allowing the sample to interact with a weakly pumped quantized leaking optical mode. We found tha...

  16. Photonic crystal fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Hansen, K P; Nielsen, M D;

    2003-01-01

    Photonic crystal fibers having a complex microstructure in the transverse plane constitute a new and promising class of optical fibers. Such fibers can either guide light through total internal reflection or the photonic bandgap effect, In this paper, we review the different types and applications...... of photonic crystal fibers with particular emphasis on recent advances in the field....

  17. Diffusion Based Photon Mapping

    DEFF Research Database (Denmark)

    Schjøth, Lars; Fogh Olsen, Ole; Sporring, Jon

    2007-01-01

    . To address this problem we introduce a novel photon mapping algorithm based on nonlinear anisotropic diffusion. Our algorithm adapts according to the structure of the photon map such that smoothing occurs along edges and structures and not across. In this way we preserve the important illumination features......, while eliminating noise. We call our method diffusion based photon mapping....

  18. Direct photon interferometry

    OpenAIRE

    Peressounko, D.

    2005-01-01

    We consider recent developments in the theory of the two-photon interferometry in ultrarelativistic heavy ion collisions with emphasis on the difference between photon and hadron interferometry. We review the available experimental results and discuss possibilities of measurement of the photon Bose-Einstein correlations in ongoing and future experiments.

  19. Ionizing photon budget: constraints from galaxies

    Science.gov (United States)

    Östlin, Göran

    2015-08-01

    I will discuss the the production and propagation of ionizing photons in galaxies. Multi wavelength HST imaging and spectroscopy of local starbursts, including candidate Lyman continuum leakers, from the UV to the i-band plus Halpha and Hbeta are used to investigate where ionizing protons are produced and absorbed. We add IFU data, e.g. from MUSE, to further constrain the optical depth to Lyman continuum photons. I will further discuss rest frame UV observations of galaxies at higher redshifts, and their implications for the ionizing photon budget.

  20. Photon Pickup by Intense Poynting Flows

    CERN Document Server

    Eichler, D

    2003-01-01

    It is suggested that a Poynting flux-dominated outflow with a sufficiently strong magnetic field can pick up hard X-ray photons when the magnetic field is of sufficient strength. The zeroth generation X-rays pair produce, and the pairs radiate extremely energetic first generation photons that could be detected by extensive air shower arrays and/or MILAGRO if they escape the production site intact. Giant flares from magnetars may thus yield bursts of UHE photons. GRB-associated Poynting flows may be unstable to pair production near their source, and their energy rapidly converted to pairs.

  1. A photon-photon collider in a vacuum hohlraum

    Science.gov (United States)

    Pike, O. J.; Mackenroth, F.; Hill, E. G.; Rose, S. J.

    2014-06-01

    The ability to create matter from light is amongst the most striking predictions of quantum electrodynamics. Experimental signatures of this have been reported in the scattering of ultra-relativistic electron beams with laser beams, intense laser-plasma interactions and laser-driven solid target scattering. However, all such routes involve massive particles. The simplest mechanism by which pure light can be transformed into matter, Breit-Wheeler pair production (γγ' --> e+e-), has never been observed in the laboratory. Here, we present the design of a new class of photon-photon collider in which a gamma-ray beam is fired into the high-temperature radiation field of a laser-heated hohlraum. Matching experimental parameters to current-generation facilities, Monte Carlo simulations suggest that this scheme is capable of producing of the order of 105 Breit-Wheeler pairs in a single shot. This would provide the first realization of a pure photon-photon collider, representing the advent of a new type of high-energy physics experiment.

  2. Electrically tunable liquid crystal photonic bandgap fiber laser

    DEFF Research Database (Denmark)

    Olausson, Christina Bjarnal Thulin; Scolari, Lara; Wei, Lei;

    2010-01-01

    We demonstrate electrical tunability of a fiber laser by using a liquid crystal photonic bandgap fiber. Tuning of the laser is achieved by combining the wavelength filtering effect of a liquid crystal photonic bandgap fiber device with an ytterbium-doped photonic crystal fiber. We fabricate an all......-spliced laser cavity based on a liquid crystal photonic bandgap fiber mounted on a silicon assembly, a pump/signal combiner with single-mode signal feed-through and an ytterbium-doped photonic crystal fiber. The laser cavity produces a single-mode output and is tuned in the range 1040-1065nm by applying...

  3. Ultrafast photonic crystal optical switching

    Institute of Scientific and Technical Information of China (English)

    GONG Qi-huang; HU Xiao-yong

    2006-01-01

    Photonic crystal,a novel and artificial photonic material with periodic dielectric distribution,possesses photonic bandgap and can control the propagation states of photons.Photonic crystal has been considered to be a promising candidate for the future integrated photonic devices.The properties and the fabrication method of photonic crystal are expounded.The progresses of the study of ultrafast photonic crystal optical switching are discussed in detail.

  4. Applications of Integrated Photonic Spectrographs in astronomy.

    OpenAIRE

    Harris, R. J.; Allington-Smith, J. R.

    2013-01-01

    One of the problems of producing instruments for extremely large telescopes (ELTs) is that their size (and hence cost) scales rapidly with telescope aperture. To try to break this relation alternative new technologies have been proposed, such as the use of the Integrated Photonic Spectrograph (IPS). Due to their diffraction-limited nature, the IPS is claimed to defeat the harsh scaling law applying to conventional instruments. In contrast to photonic applications, devices for astronomy are no...

  5. Experimental generation of complex noisy photonic entanglement

    International Nuclear Information System (INIS)

    We present an experimental scheme based on spontaneous parametric down-conversion to produce multiple-photon pairs in maximally entangled polarization states using an arrangement of two type-I nonlinear crystals. By introducing correlated polarization noise in the paths of the generated photons we prepare mixed-entangled states whose properties illustrate fundamental results obtained recently in quantum information theory, in particular those concerning bound entanglement and privacy. (paper)

  6. Beam-helicity azimuthal asymmetry measured with the recoil detector in exclusive electroproduction of real photons at HERMES

    Energy Technology Data Exchange (ETDEWEB)

    Yu Weilin

    2009-11-15

    The experiments at the HERA storage ring at DESY yielded a large contribution to the understanding of the nucleon structure. They used for this the deep inelastic scattering (DIS) in the collision of electrons/positrons and protons. The HERMES experiment at DESY applied the longitudinally polarized electron or positron beam with an energy of 27.6 GeV together with a polarized or unpolarized gas target in order to study the spin structure of the nucleon. By the measurement of deeply virtual Compton scattering (DVCS) the generalized parton distributions (GPDs) can be determined. These allow a unified description of the nucleon structure. Furthermore they give an experimental approach to the orbital angular momenta of the quarks. However the DVCS process is not discriminable from the Bethe-Heitler (BH) process, in which the scattered electron produces by bremsstrahlung processes a real photon. But it was proved that the interference caused by this indiscriminability of BH and DVCS presents the approach to the DVCS amplitude. This pursues by the measurement of asymmetries of the BH-DVCS cross section in relation to the beam charge, the beam polarization, or the target polarization. The HERMES spectrometer was constructed in order to measure semi-inclusive and inclusive DIS processes. The extraction of the azimutal asymmetries in relation to the beam helicity from the data of 2007 at the hydrogen target were performed in this thesis. The extracted asymmetry amplitudes from the elastic BH/DVCS process agree well with the earlier measurements of HERMES. Furthermore for the first time the asymmetry of {delta}{sup +} resonances was extracted, however the events are because of the low statistics affect with large uncertainties.

  7. Internal bremsstrahlung signature of real scalar dark matter and consistency with thermal relic density.

    Science.gov (United States)

    Toma, Takashi

    2013-08-30

    A gamma-ray excess from the Galactic center consistent with line emission around 130 GeV was recently found in the Fermi-LAT data. Although the Fermi-LAT Collaboration has not confirmed its significance, such a signal would be a clear signature of dark matter annihilation. Until now, there have been many attempts to explain the excess by dark matter. However, these efforts tend to give too-small cross sections into photons if consistency with the correct thermal relic density of dark matter is required. In this Letter, we consider a simple Yukawa interaction that can be compatible with both aspects and show which parameters are favored.

  8. Inclusive hard processes in photon-photon and photon-proton interactions

    OpenAIRE

    Glasman, Claudia

    1999-01-01

    Measurements of jet, prompt photon, high-pT hadron and heavy quark production in photon-induced processes provide tests of QCD and are sensitive to the photon parton densities. A review of the latest experimental results in photon-photon and photon-proton interactions is presented. Next-to-leading-order QCD calculations for these measurements are discussed.

  9. 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.

  10. The effect of polarization entanglement in photon-photon scattering

    CERN Document Server

    Rätzel, Dennis; Menzel, Ralf

    2016-01-01

    It is found that the differential cross section of photon-photon scattering is a function of the degree of entanglement of the two-photon state, and an analytic expression is derived. The interaction between photons in the symmetric Bell state is stronger than between not entangled photons. In contrast, the interaction between photons in the anti-symmetric Bell state is weaker than between not entangled photons.

  11. Universal Parametrization of Thermal Photon Rates in Hadronic Matter

    CERN Document Server

    Heffernan, Matthew; Rapp, Ralf

    2014-01-01

    Electromagnetic (EM) radiation off strongly interacting matter created in high-energy heavy-ion collisions (HICs) encodes information on the high-temperature phases of nuclear matter. Microscopic calculations of thermal EM emission rates are usually rather involved and not readily accessible to broad applications in models of the fireball evolution which are required to compare to experimental data. An accurate and universal parametrization of the microscopic calculations is thus key to honing the theory behind the EM spectra. Here we provide such a parametrization for photon emission rates from hadronic matter, including the contributions from in-medium rho mesons (which incorporate effects from anti-/baryons), as well as Bremsstrahlung from pi-pi scattering. Individual parametrizations for each contribution are numerically determined through nested fitting functions for photon energies from 0.2 to 5 GeV in chemically equilibrated matter of temperatures 100-180 MeV and baryon chemical potentials 0-400 MeV. S...

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. Superconducting nanowire photon number resolving detector at telecom wavelength

    CERN Document Server

    Divochiy, Aleksander; Bitauld, David; Gaggero, Alessandro; Leoni, Roberto; Mattioli, Francesco; Korneev, Alexander; Seleznev, Vitaliy; Kaurova, Nataliya; Minaeva, Olga; Goltsman, Gregory; Lagoudakis, Konstantinos G; Benkhaoul, Moushab; Levy, Francis; Fiore, Andrea

    2007-01-01

    The optical-to-electrical conversion, which is the basis of optical detectors, can be linear or nonlinear. When high sensitivities are needed single-photon detectors (SPDs) are used, which operate in a strongly nonlinear mode, their response being independent of the photon number. Nevertheless, photon-number resolving (PNR) detectors are needed, particularly in quantum optics, where n-photon states are routinely produced. In quantum communication, the PNR functionality is key to many protocols for establishing, swapping and measuring entanglement, and can be used to detect photon-number-splitting attacks. A linear detector with single-photon sensitivity can also be used for measuring a temporal waveform at extremely low light levels, e.g. in long-distance optical communications, fluorescence spectroscopy, optical time-domain reflectometry. We demonstrate here a PNR detector based on parallel superconducting nanowires and capable of counting up to 4 photons at telecommunication wavelengths, with ultralow dark ...

  17. Photon statistics of the micromaser with a Kerr medium

    Institute of Scientific and Technical Information of China (English)

    吴曙东; 詹志明; 金丽霞

    2002-01-01

    We have established the master equation for the micromaser with a Kerr medium. We have studied the photon statistics of the micromaser with a Kerr medium field and analysed the influence of the Kerr effect on the photon statistics. The influence of the Kerr effect on the photon statistics is different in two regimes. In the thermal-atom regime, the Kerr effect produces quantum noise, and decreases the mean photon number. In the ultracold-atom regime,with the increase of the nonlinear parameter of the Kerr medium, the stability of the mean photon number and the normalized variance enhances the mean photon number, and the normalized variance exhibits collapse-revival phenomena periodically, their resonance peaks become lower, and the photon statistics of more and more regions are sub-Poissonian.

  18. 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

  19. Photonic band gap structure simulator

    Science.gov (United States)

    Chen, Chiping; Shapiro, Michael A.; Smirnova, Evgenya I.; Temkin, Richard J.; Sirigiri, Jagadishwar R.

    2006-10-03

    A system and method for designing photonic band gap structures. The system and method provide a user with the capability to produce a model of a two-dimensional array of conductors corresponding to a unit cell. The model involves a linear equation. Boundary conditions representative of conditions at the boundary of the unit cell are applied to a solution of the Helmholtz equation defined for the unit cell. The linear equation can be approximated by a Hermitian matrix. An eigenvalue of the Helmholtz equation is calculated. One computation approach involves calculating finite differences. The model can include a symmetry element, such as a center of inversion, a rotation axis, and a mirror plane. A graphical user interface is provided for the user's convenience. A display is provided to display to a user the calculated eigenvalue, corresponding to a photonic energy level in the Brilloin zone of the unit cell.

  20. Photonic MEMS tunable laser sources

    Institute of Scientific and Technical Information of China (English)

    LIU Ai-qun

    2009-01-01

    This article covers laser configurations, design and experiments of photonic microelectromechanical systems (MEMS) tunable laser sources. Three different types of MEMS tunable lasers such as MEMS coupled-cavity lasers, injection-locked laser systems and dual-wavelength tunable lasers are demonstrated as examples of natural synergy of MEMS with photonics. The expansion and penetration of the MEMS technology to silicon optoelectronic creates on-chip optical systems at an unprecedented scale of integration. While producing better integration with robustness and compactness, MEMS improves the functionalities and specifications of laser chips. Additionally, MEMS tunable lasers are featured with small size, high tuning speed, wide tuning range and CMOS compatible integration, which broaden their applications to many fields.

  1. Video recording true single-photon double-slit interference

    CERN Document Server

    Aspden, Reuben S; Spalding, Gabriel C

    2016-01-01

    As normally used, no commercially available camera has a low-enough dark noise to directly produce video recordings of double-slit interference at the photon-by-photon level, because readout noise significantly contaminates or overwhelms the signal. In this work, noise levels are significantly reduced by turning on the camera only when the presence of a photon has been heralded by the arrival, at an independent detector, of a time-correlated photon produced via parametric down-conversion. This triggering scheme provides the improvement required for direct video imaging of Young's double-slit experiment with single photons, allowing clarified versions of this foundational demonstration. Further, we introduce variations on this experiment aimed at promoting discussion of the role spatial coherence plays in such a measurement. We also emphasize complementary aspects of single-photon measurement, where imaging yields (transverse) position information, while diffraction yields the transverse momentum, and highligh...

  2. Single-photon imaging

    CERN Document Server

    Seitz, Peter

    2011-01-01

    The acquisition and interpretation of images is a central capability in almost all scientific and technological domains. In particular, the acquisition of electromagnetic radiation, in the form of visible light, UV, infrared, X-ray, etc. is of enormous practical importance. The ultimate sensitivity in electronic imaging is the detection of individual photons. With this book, the first comprehensive review of all aspects of single-photon electronic imaging has been created. Topics include theoretical basics, semiconductor fabrication, single-photon detection principles, imager design and applications of different spectral domains. Today, the solid-state fabrication capabilities for several types of image sensors has advanced to a point, where uncoooled single-photon electronic imaging will soon become a consumer product. This book is giving a specialist´s view from different domains to the forthcoming “single-photon imaging” revolution. The various aspects of single-photon imaging are treated by internati...

  3. Heavy Quark Pair Production in Polarized Photon--Photon Collisions

    OpenAIRE

    Jikia, George; Tkabladze, Avto

    2000-01-01

    We present the next-to-leading-order cross sections of the heavy quark-antiquark pair production in polarized photon-photon collision for the general case of photon polarizations. The numerical results for top-antitop production cross sections together with production asymmetries are obtained for linearly polarized photon-photon collisions, including one-loop QCD radiative corrections.

  4. Photons from nuclear collisions at RHIC energies

    CERN Document Server

    Gale, Charles; Frodermann, Evan; Heinz, Ulrich

    2008-01-01

    We model the hot and dense strongly interacting mater produced in high energy heavy ion collisions using relativistic hydrodynamics. Several different sources of real photons produced during these collisions are considered and their relative importance is assessed. We include contributions from QCD jets, which are allowed to loose and gain energy as they proceed through the hot matter. This is treated within the AMY formalism. We obtain photon spectra, R_{AA}, and v_2 in agreement with measurements performed by the PHENIX collaboration.

  5. NLC photon collider option progress and plans

    Energy Technology Data Exchange (ETDEWEB)

    Gronberg, J

    2000-08-31

    The idea of producing beams of high energy photons by Compton backscattering of laser photons was proposed over 20 years ago. At the time, producing the required laser pulses was not feasible. However, recent advances in high average power, diode pumped lasers appear to have solved this problem. The US Collaboration is now turning its attention to the engineering requirement of mating the laser and optics components with the accelerator structures in the confined space of the a colliding beam interaction region. The demonstration of a technically feasible interaction region design is planned for the Snowmass conference in 2001.

  6. Photonic Crystal Waveguide Fabrication

    OpenAIRE

    Høvik, Jens

    2012-01-01

    This research is entirely devoted to the study and fabrication of structures with periodic dielectric constants, also known as photonic crystals (PhCs). These structures show interesting dispersion characteristics which give them a range of prohibited frequencies that are not allowed to propagate within the crystal. This property makes them suited for a wide array of photonic-based components. One-dimensional photonic crystals are already commercialized and are of widespread use in for exampl...

  7. Two photon reactions

    International Nuclear Information System (INIS)

    Some recent results from the field of photon-photon interaction are presented. After a brief general introduction author discusses resonance production, exclusive processes with the four pion final state (γγ→π+π-π+π-), exclusive reaction γγ→psi psi, γγ - 2 body final state and jet production. Total hadronic cross sections for γγ - interactions and the photon structure function are also considered. (M.F.W.)

  8. Integrated microwave photonics

    OpenAIRE

    Marpaung, David; Roeloffzen, Chris; Heideman, Rene; Leinse, Arne; Sales, Salvador; Capmany, Jose

    2012-01-01

    Microwave photonics (MWP) is an emerging field in which radio frequency (RF) signals are generated, distributed, processed and analyzed using the strength of photonic techniques. It is a technology that enables various functionalities which are not feasible to achieve only in the microwave domain. A particular aspect that recently gains significant interests is the use of photonic integrated circuit (PIC) technology in the MWP field for enhanced functionalities and robustness as well as the r...

  9. Green silicon photonics

    OpenAIRE

    Jalali, B.; Fathpour, S.; Tsia, K

    2009-01-01

    Silicon photonics have provided low-cost communication components for Internet applications and are now aimed towards providing environmentally friendly and green optical solutions. The need for energy-efficient photonics is due to the excessive energy dissipated in advanced electronics and an increase in power density that has posed a challenge to the most advanced chip-cooling technologies. The two-photon absorption (TPA)-generated free carriers need to be actively removed from the waveguid...

  10. Two-photon physics

    Energy Technology Data Exchange (ETDEWEB)

    Bardeen, W.A.

    1981-10-01

    A new experimental frontier has recently been opened to the study of two photon processes. The first results of many aspects of these reactions are being presented at this conference. In contrast, the theoretical development of research ito two photon processes has a much longer history. This talk reviews the many different theoretical ideas which provide a detailed framework for our understanding of two photon processes.

  11. Fractal Photonic Crystal Waveguides

    OpenAIRE

    Monsoriu, Juan A.; Zapata-Rodriguez, Carlos J.; Silvestre, Enrique; Furlan, Walter D.

    2004-01-01

    We propose a new class of one-dimensional (1D) photonic waveguides: the fractal photonic crystal waveguides (FPCWs). These structures are photonic crystal waveguides (PCWs) etched with fratal distribution of grooves such as Cantor bars. The transmission properties of the FPCWs are investigated and compared with those of the conventional 1D PCWs. It is shown that the FPCW transmission spectrum has self-similarity properties associated with the fractal distribution of grooves. Furthermore, FPCW...

  12. Integrated microwave photonics

    CERN Document Server

    Marpaung, David; Heideman, Rene; Leinse, Arne; Sales, Salvador; Capmany, Jose

    2012-01-01

    Microwave photonics (MWP) is an emerging field in which radio frequency (RF) signals are generated, distributed, processed and analyzed using the strength of photonic techniques. It is a technology that enables various functionalities which are not feasible to achieve only in the microwave domain. A particular aspect that recently gains significant interests is the use of photonic integrated circuit (PIC) technology in the MWP field for enhanced functionalities and robustness as well as the reduction of size, weight, cost and power consumption. This article reviews the recent advances in this emerging field which is dubbed as integrated microwave photonics. Key integrated MWP technologies are reviewed and the prospective of the field is discussed.

  13. Photonic Integrated Circuits

    Science.gov (United States)

    Merritt, Scott; Krainak, Michael

    2016-01-01

    Integrated photonics generally is the integration of multiple lithographically defined photonic and electronic components and devices (e.g. lasers, detectors, waveguides passive structures, modulators, electronic control and optical interconnects) on a single platform with nanometer-scale feature sizes. The development of photonic integrated circuits permits size, weight, power and cost reductions for spacecraft microprocessors, optical communication, processor buses, advanced data processing, and integrated optic science instrument optical systems, subsystems and components. This is particularly critical for small spacecraft platforms. We will give an overview of some NASA applications for integrated photonics.

  14. Review on Dark Photon

    Directory of Open Access Journals (Sweden)

    Curciarello Francesca

    2016-01-01

    Full Text Available e+e− collider experiments at the intensity frontier are naturally suited to probe the existence of a force beyond the Standard Model between WIMPs, the most viable dark matter candidates. The mediator of this new force, known as dark photon, should be a new vector gauge boson very weakly coupled to the Standard Model photon. No significant signal has been observed so far. I will report on current limits set on the coupling factor ε2 between the photon and the dark photon by e+e− collider experiments.

  15. Photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Sanchez Bjarklev, Araceli

    optical fibres, have spun an interest from almost all areas of optics and photonics. The aim of this book is to provide an understanding of the different types of photonic crystal fibres and to outline some of the many new and exciting applications that these fibres offer. The book is intended for both...... readers with a general interest in photonic crystals, as well as for scientists who are entering the field and desire a broad overview as well as a solid starting point for further specialized stuides. Teh book, therefore, covers bothe general aspects such as the link from classical optics to photonic...

  16. Photonics. Present and future

    Directory of Open Access Journals (Sweden)

    K. I. Silakov

    2011-03-01

    Full Text Available Short review of the literature in the field of photonics, which reflects the new technology of ultra-compact optical communications components, the use of generators to transmission light instead of wires is represented. This is - silicon photonics - finding ways to use semiconductor components and of standard semiconductor technology to create optical devices, silicon photonics - the creation of a silicon photonic waveguide. All of these components can be used in the construction of computer systems linked by powerful optical data networks. Optical communication system will eliminate the "bottleneck" due to the difference in memory bandwidth and processor speed, and improve overall performance computing plate-tformy.

  17. Towards THz integrated photonics

    OpenAIRE

    Hübers, Heinz-Wilhelm

    2010-01-01

    The demonstration of an integrated terahertz transceiver featuring a quantum cascade laser and a Schottky diode mixer promises new applications for compact and convenient terahertz photonic instrumentation.

  18. Nonlinear Integrated Microwave Photonics

    CERN Document Server

    Marpaung, David

    2013-01-01

    Harnessing nonlinear optical effects in a photonic chip scale has been proven useful for a number of key applications in optical communications. Microwave photonics can also benefit from the adoption of such a technology, creating a new concept of nonlinear integrated microwave photonics. Here, we discuss the potential of on-chip nonlinear processing towards the creation of robust and multifunctional microwave photonic (MWP) processors. We also highlight key recent results in the field, including frequency agile MWP filters and ultra-wideband signal generators.

  19. Biomedical photonics handbook

    CERN Document Server

    Vo-Dinh, Tuan

    2003-01-01

    1.Biomedical Photonics: A Revolution at the Interface of Science and Technology, T. Vo-DinhPHOTONICS AND TISSUE OPTICS2.Optical Properties of Tissues, J. Mobley and T. Vo-Dinh3.Light-Tissue Interactions, V.V. Tuchin 4.Theoretical Models and Algorithms in Optical Diffusion Tomography, S.J. Norton and T. Vo-DinhPHOTONIC DEVICES5.Laser Light in Biomedicine and the Life Sciences: From the Present to the Future, V.S. Letokhov6.Basic Instrumentation in Photonics, T. Vo-Dinh7.Optical Fibers and Waveguides for Medical Applications, I. Gannot and

  20. On the comparison of matrix element calculations of O(ααs) with the measurement of photon emission in hadronic Z 0 decays

    Science.gov (United States)

    Mättig, P.; Spiesberger, H.; Zeuner, W.

    1993-12-01

    The uncertainties in interpreting photon bremsstrahlung in the processe^ + e^ - to Z^0 to qbar q with matrix element calculations of O(ααs) are discussed. We address the stability of the calculations with respect to the emission of collinear photons and to higher-order QCD corrections and discuss the bias due to experimental photon isolation cuts. We analyze the resulting uncertainties for various procedures to define an event with a final state photon. Of particular interest are (i) a two-step procedure where first jets are reconstructed from hadrons alone and in a second step the photon is required to be isolated from these jets, and (ii) a ‘democratic’ procedure where the photon is inculded in the jet reconstruction but a certain maximum hadronic energy is allowed in the photon jet. In both cases we estimate that the uncertainties of the theoretical predictions, hadronization effects and the experimental photon isolation are of the order of 4%. To obtain this level of accuracy, however, the democratic procedure requires very hard cuts that reduce the event samples significantly.