WorldWideScience

Sample records for optical transition radiation

  1. Advanced simulations of optical transition and diffraction radiation

    Directory of Open Access Journals (Sweden)

    T. Aumeyr

    2015-04-01

    Full Text Available Charged particle beam diagnostics is a key task in modern and future accelerator installations. The diagnostic tools are practically the “eyes” of the operators. The precision and resolution of the diagnostic equipment are crucial to define the performance of the accelerator. Transition and diffraction radiation (TR and DR are widely used for electron beam parameter monitoring. However, the precision and resolution of those devices are determined by how well the production, transport and detection of these radiation types are understood. This paper reports on simulations of TR and DR spatial-spectral characteristics using the physical optics propagation (POP mode of the Zemax advanced optics simulation software. A good consistency with theory is demonstrated. Also, realistic optical system alignment issues are discussed.

  2. The transition radiation. 2. experimental study of the optical transition radiation; Le rayonnement de transition: 2. etude experimentale du rayonnement de transition optique

    Energy Technology Data Exchange (ETDEWEB)

    Couillaud, Ch.; Haouat, G.; Seguin, S.; Striby, S

    1999-07-01

    Optical-transition-radiation-based diagnostics have been widely used for many years on electron accelerators in order to measure beam energy and transverse and longitudinal emittances. These diagnostics are very attractive for high brightness electron beams used as drivers for radiation sources. Such diagnostics have been performed on the ELSA facility (18 MeV electron energy, 100 A peak current) using both a single interface and an OTR-Wartski interferometer. We present the accelerator, the experimental set-up and the method for analyzing the OTR angular distribution. Then, the experimental results are described and compared with those from the three gradient method. In addition, we present a beam energy measurement using OTR interferogram analysis. (author)

  3. Optical Transition Radiation Measurement of Electron Beam for Beijing Free Electron Laser

    Institute of Scientific and Technical Information of China (English)

    ZHAO Qiang; XIE Jia-Lin; LI Yong-Gui; ZHUANG Jie-Jia

    2001-01-01

    We used transition radiation techniques instead of the original phosphor targets to improve the electronic beam diagnostic system at Beijing Free Electron Laser. The beam profile, size (3.3 × 2.4 mm), position and divergence angle (σrms = 2.5 mrad) in transverse have been obtained from optical transition radiation. We also present the experimental set-up and some preliminary results.

  4. Measurement of Sub-Picosecond Electron Bunches via Electro-Optic Sampling of Coherent Transition Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, Timothy John [Northern Illinois U.

    2012-01-01

    Future collider applications as well as present high-gradient laser plasma wakefield accelerators and free-electron lasers operating with picosecond bunch durations place a higher demand on the time resolution of bunch distribution diagnostics. This demand has led to significant advancements in the field of electro-optic sampling over the past ten years. These methods allow the probing of diagnostic light such as coherent transition radiation or the bunch wakefields with sub-picosecond time resolution. We present results on the single-shot electro-optic spectral decoding of coherent transition radiation from bunches generated at the Fermilab A0 photoinjector laboratory. A longitudinal double-pulse modulation of the electron beam is also realized by transverse beam masking followed by a transverse-to-longitudinal phase-space exchange beamline. Live profile tuning is demonstrated by upstream beam focusing in conjunction with downstream monitoring of single-shot electro-optic spectral decoding of the coherent transition radiation.

  5. Report on the Radiation Effects Testing of the Infrared and Optical Transition Radiation Camera Systems

    Energy Technology Data Exchange (ETDEWEB)

    Holloway, Michael Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-04-20

    Presented in this report are the results tests performed at Argonne National Lab in collaboration with Los Alamos National Lab to assess the reliability of the critical 99Mo production facility beam monitoring diagnostics. The main components of the beam monitoring systems are two cameras that will be exposed to radiation during accelerator operation. The purpose of this test is to assess the reliability of the cameras and related optical components when exposed to operational radiation levels. Both X-ray and neutron radiation could potentially damage camera electronics as well as the optical components such as lenses and windows. This report covers results of the testing of component reliability when exposed to X-ray radiation. With the information from this study we provide recommendations for implementing protective measures for the camera systems in order to minimize the occurrence of radiation-induced failure within a ten month production run cycle.

  6. Single-shot electro-optic sampling of coherent transition radiation at the A0 Photoinjector

    CERN Document Server

    Maxwell, T J; Piot, P; Thurman-Keup, R

    2012-01-01

    Future collider applications and present high-gradient laser plasma wakefield accelerators operating with picosecond bunch durations place a higher demand on the time resolution of bunch distribution diagnostics. This demand has led to significant advancements in the field of electro-optic sampling over the past ten years. These methods allow the probing of diagnostic light such as coherent transition radiation or the bunch wakefields with sub-picosecond time resolution. Potential applications in shot-to-shot, non-interceptive diagnostics continue to be pursued for live beam monitoring of collider and pump-probe experiments. Related to our developing work with electro-optic imaging, we present results on single-shot electro-optic sampling of the coherent transition radiation from bunches generated at the A0 photoinjector.

  7. Very high resolution optical transition radiation imaging system: Comparison between simulation and experiment

    CERN Document Server

    Bolzon, B; Aumeyr, Thomas; Boogert, Stewart Takashi; Karataev, Pavel; Kruchinin, Konstantin; Lefevre, Thibaut; Mazzoni, Stefano; Nevay, Laurence James; Shevelev, M; Terunuma, N; Urakawa, J; Welsch, Carsten

    2015-01-01

    Optical transition radiation (OTR) has become a commonly used method for 2D beam imaging measurements. In the Accelerator Test Facility 2 (ATF2) at KEK, beam sizes smaller than the OTR point spread function have been measured. Simulations of the OTR imaging system have been performed using the ZEMAX software to study the effects of optical errors such as aberrations, diffraction, and misalignments of optical components. This paper presents a comparison of simulations of the OTR point spread function with experimental data obtained at ATF2. It shows how the quantification and control of optical errors impacts on optimizing the resolution of the system. We also show that the OTR point spread function needs to be predicted accurately to optimize any optical system and to predict the error made on measurement.

  8. Very high resolution optical transition radiation imaging system: Comparison between simulation and experiment

    Directory of Open Access Journals (Sweden)

    B. Bolzon

    2015-08-01

    Full Text Available Optical transition radiation (OTR has become a commonly used method for 2D beam imaging measurements. In the Accelerator Test Facility 2 (ATF2 at KEK, beam sizes smaller than the OTR point spread function have been measured. Simulations of the OTR imaging system have been performed using the ZEMAX software to study the effects of optical errors such as aberrations, diffraction, and misalignments of optical components. This paper presents a comparison of simulations of the OTR point spread function with experimental data obtained at ATF2. It shows how the quantification and control of optical errors impacts on optimizing the resolution of the system. We also show that the OTR point spread function needs to be predicted accurately to optimize any optical system and to predict the error made on measurement.

  9. A novel method for sub-micrometer transverse electron beam size measurements using optical transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Aryshev, A; Boogert, S T; Karataev, P [John Adams Institute at Royal Holloway, Egham, Surrey, TW20 0EX (United Kingdom); Howell, D [John Adams Institute at Oxford University, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Terunuma, N; Urakawa, J, E-mail: alar@post.kek.j [KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

    2010-06-01

    Optical Transition Radiation (OTR) appearing when a charged particle crosses a boundary between two media with different dielectric properties has widely been used as a tool for transverse profile measurements of charged particle beams in various facilities worldwide. The resolution of the monitor is defined by so-called Point Spread Function (PSF), source distribution generated by a single electron and projected by an optical system onto a screen. In this paper we represent the development of a novel sub-micrometre electron beam profile monitor based on the measurements of the PSF structure. The first experimental results are presented and future plans on the optimization of the monitor are discussed

  10. Progress on the Flash X-Ray Optical Transition Radiation Diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Tang, V; Houck, T; Brown, C

    2008-03-30

    This document summarizes the Flash X-Ray accelerator (FXR) optical transition radiation (OTR) spot-size diagnostics efforts in FY07. During this year, new analysis, simulation, and experimental approaches were utilized to interpret OTR spot data from both dielectric foils such as Kapton (VN type) and metal coated foils. Significant new findings of the intricacies involved in the diagnostic and of FXR operational issues were achieved. Geometry and temperature based effects were found to affect the beam image profiles from the OTR foils. These effects must be taken into account in order to deduce accurately the beam current density profile.

  11. Electron Beam Spectrum Diagnostics with Optical Transition Radiation on the Beijing Free-Electron Laser

    Institute of Scientific and Technical Information of China (English)

    李泉凤; 吴频; 高建江; 吴刚

    2004-01-01

    A measurement system was developed to measure the electron beam spectrum of the Beijing free-electron laser based on the optical transition radiation (OTR). This paper describes the system, which consists of a 32-channel high resolution of 0.02% OTR detector, especially the spectrometer. The OTR angular-distribution pattern at the focal plane has two apexes, but the two apexes are smoothed out due to the electron beam energy distribution. The energy spectrum can be measured if the magnet energy resolution is higher than 0.7% to distinguish the electron beam energy distribution.

  12. Transverse beam shape measurements of intense proton beams using optical transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Scarpine, Victor E.; /Fermilab

    2012-03-01

    A number of particle physics experiments are being proposed as part of the Department of Energy HEP Intensity Frontier. Many of these experiments will utilize megawatt level proton beams onto targets to form secondary beams of muons, kaons and neutrinos. These experiments require transverse size measurements of the incident proton beam onto target for each beam spill. Because of the high power levels, most beam intercepting profiling techniques will not work at full beam intensity. The possibility of utilizing optical transition radiation (OTR) for high intensity proton beam profiling is discussed. In addition, previous measurements of OTR beam profiles from the NuMI beamline are presented.

  13. Optical transition radiation measurements for the Los Alamos and Boeing Free-Electron Laser experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H.; Feldman, R.B.; Feldman, D.W.; Apgar, S.A.; Calsten, B.E.; Fiorito, R.B.; Rule, D.W.

    1988-01-01

    Optical transition radiation (OTR) measurements of the electron-beam emittance have been performed at a location just before the wiggler in the Los Alamos Free-Electron Laser (FEL) experiment. Beam profiles and beam divergence patterns from a single macropulse were recorded simultaneously using two intensified charge-injection device (CID) television cameras and an optical beamsplitter. Both single-foil OTR and two-foil OTR interference experiments were performed. Preliminary results are compared to a reference variable quadrupole, single screen technique. New aspects of using OTR properties for pointing the e-beam on the FEL oscillator axis, as well as measuring e-beam emittance are addressed. 7 refs., 9 figs.

  14. Optical transition radiation measurements for the Los Alamos and Boeing Free-Electron Laser experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H.; Feldman, R.B.; Feldman, D.W.; Apgar, S.A.; Calsten, B.E.; Fiorito, R.B.; Rule, D.W.

    1988-01-01

    Optical transition radiation (OTR) measurements of the electron-beam emittance have been performed at a location just before the wiggler in the Los Alamos Free-Electron Laser (FEL) experiment. Beam profiles and beam divergence patterns from a single macropulse were recorded simultaneously using two intensified charge-injection device (CID) television cameras and an optical beamsplitter. Both single-foil OTR and two-foil OTR interference experiments were performed. Preliminary results are compared to a reference variable quadrupole, single screen technique. New aspects of using OTR properties for pointing the e-beam on the FEL oscillator axis, as well as measuring e-beam emittance are addressed. 7 refs., 9 figs.

  15. Transverse phase space mapping of relativistic electron beams using optical transition radiation

    Directory of Open Access Journals (Sweden)

    G. P. Le Sage

    1999-12-01

    Full Text Available Optical transition radiation (OTR has proven to be a versatile and effective diagnostic for measuring the profile, divergence, and emittance of relativistic electron beams with a wide range of parameters. Diagnosis of the divergence of modern high brightness beams is especially well suited to OTR interference (OTRI techniques, where multiple dielectric or metal foils are used to generate a spatially coherent interference pattern. Theoretical analysis of measured OTR and OTRI patterns allows precise measurement of electron beam emittance characteristics. Here we describe an extension of this technique to allow mapping of divergence characteristics as a function of transverse coordinates within a measured beam. We present the first experimental analysis of the transverse phase space of an electron beam using all optical techniques. Comparing an optically masked portion of the beam to the entire beam, we measure different angular spread and average direction of the particles. Direct measurement of the phase-space ellipse tilt angle has been demonstrated using this optical masking technique.

  16. Stimulated coherent transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hung-chi Lihn

    1996-03-01

    Coherent radiation emitted from a relativistic electron bunch consists of wavelengths longer than or comparable to the bunch length. The intensity of this radiation out-numbers that of its incoherent counterpart, which extends to wavelengths shorter than the bunch length, by a factor equal to the number of electrons in the bunch. In typical accelerators, this factor is about 8 to 11 orders of magnitude. The spectrum of the coherent radiation is determined by the Fourier transform of the electron bunch distribution and, therefore, contains information of the bunch distribution. Coherent transition radiation emitted from subpicosecond electron bunches at the Stanford SUNSHINE facility is observed in the far-infrared regime through a room-temperature pyroelectric bolometer and characterized through the electron bunch-length study. To measure the bunch length, a new frequency-resolved subpicosecond bunch-length measuring system is developed. This system uses a far-infrared Michelson interferometer to measure the spectrum of coherent transition radiation through optical autocorrelation with resolution far better than existing time-resolved methods. Hence, the radiation spectrum and the bunch length are deduced from the autocorrelation measurement. To study the stimulation of coherent transition radiation, a special cavity named BRAICER is invented. Far-infrared light pulses of coherent transition radiation emitted from electron bunches are delayed and circulated in the cavity to coincide with subsequent incoming electron bunches. This coincidence of light pulses with electron bunches enables the light to do work on electrons, and thus stimulates more radiated energy. The possibilities of extending the bunch-length measuring system to measure the three-dimensional bunch distribution and making the BRAICER cavity a broadband, high-intensity, coherent, far-infrared light source are also discussed.

  17. Evidence for anomalous optical transition radiation linear polarization effects in beam-profile monitors

    Directory of Open Access Journals (Sweden)

    A. H. Lumpkin

    2013-10-01

    Full Text Available Investigations of the effects of optical transition radiation (OTR polarization components on beam profiles are presented. The transverse profiles are examined using the OTR perpendicular and parallel polarization components with respect to the dimension of interest. We observed ∼15% projected profile size reductions with the perpendicularly polarized components on a 65-μm beam image size case at 14 MeV, a 150-μm beam image size at 4.5 GeV, and a 1100-μm beam image size at 7 GeV. These effects are all several times larger than expected (and anomalous in this sense when compared to the standard OTR point-spread function calculations. We propose the time-averaged induced-current distribution which generates the OTR represents the actual beam size more faithfully with the perpendicular polarization component and recommend its routine use and subsequent deconvolution.

  18. Time-resolved electron-beam characterizations with optical transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H. (Argonne National Lab., IL (United States)); Wilke, M.D. (Los Alamos National Lab., NM (United States))

    1992-01-01

    Time-resolved characterizations of electron beams using optical transition radiation (OTR) as a prompt conversion mechanism have recently been extended on the Los Alamos Free-electron Laser (FEL) facility 40-MeV linac. Two key timescales for rf-linac driven FELs are the micropulse (10 ps) and the macropulse (5 {mu}s to 1 ms). In the past we have used gated, intensified cameras to select a single or few micropulses (25 to 400 ns gate width) out of the pulse train to evaluate submacropulse effects. Recently, we have obtained some of the first measurements of micropulse bunch length (7 to 10 ps) and submacropulse spatial position and profile using OTR and a Hamamatsu streak camera. Additionally, micropulse elongation effects and head-to-tail transverse kicks are reported as a function of charge.

  19. Time-resolved electron-beam characterizations with optical transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H. [Argonne National Lab., IL (United States); Wilke, M.D. [Los Alamos National Lab., NM (United States)

    1992-09-01

    Time-resolved characterizations of electron beams using optical transition radiation (OTR) as a prompt conversion mechanism have recently been extended on the Los Alamos Free-electron Laser (FEL) facility 40-MeV linac. Two key timescales for rf-linac driven FELs are the micropulse (10 ps) and the macropulse (5 {mu}s to 1 ms). In the past we have used gated, intensified cameras to select a single or few micropulses (25 to 400 ns gate width) out of the pulse train to evaluate submacropulse effects. Recently, we have obtained some of the first measurements of micropulse bunch length (7 to 10 ps) and submacropulse spatial position and profile using OTR and a Hamamatsu streak camera. Additionally, micropulse elongation effects and head-to-tail transverse kicks are reported as a function of charge.

  20. Further time-resolved electron-beam characterizations with optical transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H. (Argonne National Lab., IL (United States). Advanced Photon Source Accelerator Systems Div.); Wilke, M.D. (Los Alamos National Lab., NM (United States))

    1992-01-01

    Time-resolved characterizations of electron beams using optical transition radiation (OTR) as a prompt conversion mechanism have recently been extended on the Los Alamos Free-electron Laser (FEL) facility 40-MeV linac. Two key timescales for rf-linac driven FELs are the micropulse (10 ps) and the macropulse (5 [mu]s to 1 ms). In the past we have used gated, intensified cameras to select a single or few micropulses (25 to 400 ns gate width) out of the pulse train to evaluate submacropulse effects. Recently, we have obtained some of the first measurements of micropulse bunch length (7 to 10 ps) and submacropulse spatialposition and profile using OTR and a Hamamatsu streak camera. Additionally, micropulse elongation effects and head-to-tail transverse kick effects are reported as a function of charge.

  1. Further time-resolved electron-beam characterizations with optical transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H. [Argonne National Lab., IL (United States). Advanced Photon Source Accelerator Systems Div.; Wilke, M.D. [Los Alamos National Lab., NM (United States)

    1992-12-31

    Time-resolved characterizations of electron beams using optical transition radiation (OTR) as a prompt conversion mechanism have recently been extended on the Los Alamos Free-electron Laser (FEL) facility 40-MeV linac. Two key timescales for rf-linac driven FELs are the micropulse (10 ps) and the macropulse (5 {mu}s to 1 ms). In the past we have used gated, intensified cameras to select a single or few micropulses (25 to 400 ns gate width) out of the pulse train to evaluate submacropulse effects. Recently, we have obtained some of the first measurements of micropulse bunch length (7 to 10 ps) and submacropulse spatialposition and profile using OTR and a Hamamatsu streak camera. Additionally, micropulse elongation effects and head-to-tail transverse kick effects are reported as a function of charge.

  2. Optical transitions in semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Rupasov, Valery I. [ALTAIR Center LLC, Shrewsbury, MA 01545 (United States) and Landau Institute for Theoretical Physics, Moscow (Russian Federation)]. E-mail: rupasov@townisp.com

    2007-03-19

    Employing the Maxwell equations and conventional boundary conditions for the radiation field on the nanostructure interfaces, we compute the radiative spontaneous decay rate of optical transitions in spherical semiconductor nanocrystals, core-shell nanocrystals and nanostructures comprising more than one shell. We also show that the coupling between optical transitions localized in the shell of core-shell nanocrystals and radiation field is determined by both conventional electro-multipole momenta and electro-multipole 'inverse' momenta. The latter are proportional to the core radius even for interband transitions that should result in very strong optical transitions.

  3. Transition radiation by neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Ioannisian, A.N., E-mail: ara.ioannisyan@cern.ch [Yerevan Physics Institute, Alikhanian Br. 2, 375036 Yerevan (Armenia); CERN, Theory Division, CH-1211 Geneva 23 (Switzerland); Institute for Theoretical Physics and Modeling, 375036 Yerevan (Armenia); Ioannisian, D.A. [Yerevan Physics Institute, Alikhanian Br. 2, 375036 Yerevan (Armenia); Institute for Theoretical Physics and Modeling, 375036 Yerevan (Armenia); Physics Department, Yerevan State University, 1 Alex Manoogian (Armenia); Kazarian, N.A. [Institute for Theoretical Physics and Modeling, 375036 Yerevan (Armenia)

    2011-08-19

    We calculate the transition radiation process {nu}{yields}{nu}{gamma} at an interface of two media. The neutrinos are taken to be with only standard-model couplings. The medium fulfills the dual purpose of inducing an effective neutrino-photon vertex and of modifying the photon dispersion relation. The transition radiation occurs when at least one of those quantities have different values in different media. The neutrino mass is ignored due to its negligible contribution. We present a result for the probability of the transition radiation which is both accurate and analytic. For E{sub {nu}=}1 MeV neutrino crossing polyethylene-vacuum interface the transition radiation probability is about 10{sup -39} and the energy intensity is about 10{sup -34} eV. At the surface of the neutron stars the transition radiation probability may be {approx}10{sup -20}. Our result is by the three orders of magnitude larger than those of previous calculations.

  4. Transition radiation by neutrinos

    Science.gov (United States)

    Ioannisian, A. N.; Ioannisian, D. A.; Kazarian, N. A.

    2011-08-01

    We calculate the transition radiation process ν→νγ at an interface of two media. The neutrinos are taken to be with only standard-model couplings. The medium fulfills the dual purpose of inducing an effective neutrino-photon vertex and of modifying the photon dispersion relation. The transition radiation occurs when at least one of those quantities have different values in different media. The neutrino mass is ignored due to its negligible contribution. We present a result for the probability of the transition radiation which is both accurate and analytic. For Eν=1 MeV neutrino crossing polyethylene-vacuum interface the transition radiation probability is about 10 and the energy intensity is about 10 eV. At the surface of the neutron stars the transition radiation probability may be ˜10. Our result is by the three orders of magnitude larger than those of previous calculations.

  5. Transition Radiation Detectors

    CERN Document Server

    Andronic, A

    2012-01-01

    We review the basic features of transition radiation and how they are used for the design of modern Transition Radiation Detectors (TRD). The discussion will include the various realizations of radiators as well as a discussion of the detection media and aspects of detector construction. With regard to particle identification we assess the different methods for efficient discrimination of different particles and outline the methods for the quantification of this property. Since a number of comprehensive reviews already exist, we predominantly focus on the detectors currently operated at the LHC. To a lesser extent we also cover some other TRDs, which are planned or are currently being operated in balloon or space-borne astro-particle physics experiments.

  6. ATLAS Transition Radiation Tracker

    CERN Multimedia

    2006-01-01

    The ATLAS transition radiation tracker is made of 300'000 straw tubes, up to 144cm long. Filled with a gas mixture and threaded with a wire, each straw is a complete mini-detector in its own right. An electric field is applied between the wire and the outside wall of the straw. As particles pass through, they collide with atoms in the gas, knocking out electrons. The avalanche of electrons is detected as an electrical signal on the wire in the centre. The tracker plays two important roles. Firstly, it makes more position measurements, giving more dots for the computers to join up to recreate the particle tracks. Also, together with the ATLAS calorimeters, it distinguishes between different types of particles depending on whether they emit radiation as they make the transition from the surrounding foil into the straws.

  7. ATLAS Transitional Radiation Tracker

    CERN Multimedia

    ATLAS Outreach

    2006-01-01

    This colorful 3D animation is an excerpt from the film "ATLAS-Episode II, The Particles Strike Back." Shot with a bug's eye view of the inside of the detector. The viewer is taken on a tour of the inner workings of the transitional radiation tracker within the ATLAS detector. Subjects covered include what the tracker is used to measure, its structure, what happens when particles pass through the tracker, how it distinguishes between different types of particles within it.

  8. ALICE Transition Radiation Detector

    CERN Multimedia

    Pachmayer, Y

    2013-01-01

    The Transition Radiation Detector (TRD) is the main electron detector in ALICE. In conduction with the TPC and the ITS, it provides the necessary electron identification capability to study: - Production of light and heavy vector mesons as well as the continuum in the di-electron channel, - Semi leptonic decays of hadrons with open charm and open beauty via the single-electron channel using the displaced vertex information provided by the ITS, - Correlated DD and BB pairs via coincidences of electrons in the central barrel and muons in the forward muon arm, - Jets with high Pτ tracks in one single TRD stack.

  9. Anomalous radiative transitions

    CERN Document Server

    Ishikawa, Kenzo; Tobita, Yutaka

    2014-01-01

    Anomalous transitions involving photons derived by many-body interaction of the form, $\\partial_{\\mu} G^{\\mu}$, in the standard model are studied. This does not affect the equation of motion in the bulk, but makes wave functions modified, and causes the unusual transition characterized by the time-independent probability. In the transition probability at a time-interval T expressed generally in the form $P=T \\Gamma_0 +P^{(d)}$, now with $\\Gamma_0=0, P^{(d)} \

  10. Optical systems for synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Howells, M.R.

    1985-12-01

    Various fundamental topics which underlie the design and use of optical systems for synchrotron radiation are considered from the viewpoint of linear system theory. These topics include the damped harmonic oscillator, free space propagation of an optical field, electromagnetic theory of optical properties of materials, theory of dispersion, and the Kramers-Kronig relations. 32 refs., 5 figs. (LEW)

  11. The effect of temperature and pressure on optical absorption spectra of transition zone minerals - Implications for the radiative conductivity of the Earth's interior

    Science.gov (United States)

    Thomas, S.; Jacobsen, S. D.; Bina, C. R.; Goncharov, A. F.; Frost, D. J.; McCammon, C. A.

    2010-12-01

    Optical absorption spectra of high-pressure minerals can be used as indirect tools to calculate radiative conductivities of the Earth’s interior [e.g., 1]. Recent high-pressure studies imply that e.g. ringwoodite, γ-(Mg,Fe)2SiO4, does not become opaque in the near infrared and visible region, as previously assumed, but remains transparent to 21.5 GPa [2]. Therefore, it has been concluded that radiative heat transfer does not necessarily become blocked at high pressures of the mantle and ferromagnesian minerals actually might contribute to the heat flow in the Earth’s interior [2]. However, experimental results on temperature effects on radiative heat transfer are not available. We studied the effect of both, pressure and temperature, on the optical absorption of hydrous Fe-bearing ringwoodite, γ-(Mg,Fe)2SiO4, and hydrous Fe-bearing wadsleyite, β-(Mg,Fe)2SiO4, which are the main components of the Earth’s transition zone. Gem-quality single-crystals were synthesized at 18 GPa and 1400 °C in a 5000t multianvil apparatus. Crystals were analyzed by Mössbauer and Raman spectroscopy, electron microprobe analysis and single-crystal X-ray diffraction. For optical absorption measurements in the IR - VIS - UV spectral range (400 - 50000 cm-1) 50 µm sized single-crystals of ringwoodite and wadsleyite were double polished to thicknesses of 13 µm and 18 µm, respectively, and loaded in resistively heated diamond-anvil cells with argon as pressure medium. After taking measurements at high pressure and room temperature, ringwoodite was studied at 26 GPa up to 650 °C and wadsleyite spectra were recorded at 16 GPa up to 450 °C. At ambient pressure the absorption spectrum of ringwoodite reveals a crystal field band (Fe2+) at 12075 cm-1, an intervalence charge transfer band (Fe2+ to Fe3+) at 16491 cm-1, and an absorption edge due to ligand-metal charge transfer close to 30000 cm-1. The wadsleyite spectrum is characterized by a similar absorption edge in the VIS-UV range

  12. Quantum optical dipole radiation fields

    CERN Document Server

    Stokes, Adam

    2016-01-01

    We introduce quantum optical dipole radiation fields defined in terms of photon creation and annihilation operators. These fields are identified through their spatial dependence, as the components of the total fields that survive infinitely far from the dipole source. We use these radiation fields to perturbatively evaluate the electromagnetic radiated energy-flux of the excited dipole. Our results indicate that the standard interpretation of a bare atom surrounded by a localised virtual photon cloud, is difficult to sustain, because the radiated energy-flux surviving infinitely far from the source contains virtual contributions. It follows that there is a clear distinction to be made between a radiative photon defined in terms of the radiation fields, and a real photon, whose identification depends on whether or not a given process conserves the free energy. This free energy is represented by the difference between the total dipole-field Hamiltonian and its interaction component.

  13. Optics and radiators for RICH

    CERN Document Server

    Ekelöf, T J C

    1999-01-01

    An overview is given of the basic optics-design principles for Ring Imaging Cherenkov (RICH) counters in High-Energy Physics -- of the earlier evolution of these principles and of the new ideas and techniques that are currently being developed. The characteristics of the different gasses, liquids and solids that are employed as Cherenkov radiators, which are of fundamental importance to the optics design of a RICH counter, are also reviewed.

  14. Nanorod optical antennas for dipolar transitions

    CERN Document Server

    Taminiau, Tim H; van Hulst, Niek F

    2009-01-01

    Optical antennas link objects to light. Here, we analyze metal nanorod antennas as cavities with variable reflection coefficients to derive the interaction of dipolar transitions with radiation through the antenna modes. The presented analytical model accurately describes the complete emission process, and is summarized in a phase-matching equation. We show how antenna modes evolve as they become increasingly more bound, i.e. plasmonic. The results illustrate why efficient antennas should not be too plasmonic, and how subradiant even modes can evolve into weakly-interacting dark modes. Our description is valid for the interaction of nanorods with light in general, and is thus widely applicable.

  15. ALICE Transition Radiation Detector (TRD), test beam.

    CERN Multimedia

    2003-01-01

    Electrons and positrons can be discriminated from other charged particles using the emission of transition radiation - X-rays emitted when the particles cross many layers of thin materials. To develop such a Transition Radiation Detector(TRD) for ALICE many detector prototypes were tested in mixed beams of pions and electrons, as in the example shown here.

  16. Fiber optic ionizing radiation detector

    Energy Technology Data Exchange (ETDEWEB)

    Suter, J.J. (Johns Hopkins Univ., Applied Physics Lab., Laurel, MD (United States)); Poret, J.C.; Rosen, M. (Johns Hopkins Univ., Dept. of Materials Science and Engineering, Baltimore, MD (United States))

    1992-08-01

    Radiation detection can be done by various types of devices, such as Geiger counters, thermoluminescent detectors, and electric field sensors. This paper reports on a noel design for an ionizing radiation sensor using coiled optical fibers, which can be placed within or near a radioactive source. This design has several features that make it different from sensors proposed in the past. In order to evaluate this sensor, coiled fiber samples were placed inside metallic and metal-matrix composite cylinders to evaluate the sensitivity of the detector as well as the shielding effectiveness of the materials.

  17. Transition undulator radiation as bright infrared sources

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.J. [Lawrence Berkeley Lab., CA (United States)

    1995-02-01

    Undulator radiation contains, in addition to the usual component with narrow spectral features, a broad-band component in the low frequency region emitted in the near forward direction, peaked at an angle 1/{gamma}, where {gamma} is the relativistic factor. This component is referred to as the transition undulator radiation, as it is caused by the sudden change in the electron`s longitudinal velocity as it enters and leaves the undulator. The characteristic of the transition undulator radiation are analyzed and compared with the infrared radiation from the usual undulator harmonics and from bending magnets.

  18. Simulation Transition Radiation and Electron Identification Ability of the ATLAS Transition Radiation Tracker

    CERN Document Server

    Klinkby, E B; The ATLAS collaboration

    2011-01-01

    Using test-beam as well as collision data, the transition radiation model of the ATLAS simulation is tuned to match data. Furthermore the electron identification abilities of the ATLAS Transition Radiation Tracker are discussed, and example on usage in physics analysis are shown.

  19. Particle identification by Cherenkov and transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Gilmore, R.S.

    1980-09-01

    The Cherenkov counter has a role as a particle identifier for velocities which are too high for Time-of-Flight to be used, and too low for transition radiation detectors to give a useable signal. In beam lines the compensated differential counter is capable of giving the best resolution, but at high momenta the restriction on the spread of particle directions gives unacceptable limits on the beam acceptance. The transition radiation detectors being developed to identify hadrons at relatively low momentum do not have this restriction and might be used instead. For particles produced in an interaction, the ring imaging type of Cherenkov should give the best coverage for multiparticle events, but a threshold counter is much simpler, cheaper and faster where it can give adequate separation. Again at high values of ..gamma.. the resolution of Cherenkov counters will fail and some form of transition radiation detector will be necessary.

  20. Charmonium meson and hybrid radiative transitions

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Peng [Indiana U., JLAB; Yépez-Martínez, Tochtli [Indiana U.; Szczepaniak, Adam P. [Indiana U., JLAB

    2014-06-01

    We consider the non-relativistic limit of the QCD Hamiltonian in the Coulomb gauge, to describe radiative transitions between conventional charmonium states and from the lowest multiplet of cc¯ hybrids to charmonium mesons. The results are compared to potential quark models and lattices calculations.

  1. Evaluation of atomic constants for optical radiation, volume 1

    Science.gov (United States)

    Kylstra, C. D.; Schneider, R. J.

    1974-01-01

    Atomic constants for optical radiation are discussed which include transition probabilities, line strengths, and oscillator strengths for both dipole and quadrupole transitions, as well as the associated matrix elements needed for line broadening calculations. Atomic constants were computed for a wide selection of elements and lines. An existing computer program was used, with modifications to include, in an approximate manner, the effect of equivalent electrons, and to enable reordering and restructuring of the output for publication. This program is suitable for fast, low cost computation of the optical constants, using the Coulomb approximation formalism for LS coupling.

  2. Classical theory of resonant transition radiation in multilayer structures.

    Science.gov (United States)

    Pardo, B; André, J M

    2001-01-01

    A rigorous classical electromagnetic theory of the transition radiation in finite and infinite multilayer structures is presented. It makes the standard results of thin-film optics, such as the matrix formalism, accountable; it allows thus an exact treatment of the propagation of the waves induced by the electron. This method is applied to the particular case of the periodic structures to treat the resonant transition radiation (RTR). It is noted that the present theory gives, in the hard x-ray domain, results previously published. The reason for this approach is to make the numerical calculations rigorous and easy. The numerical results of our theory are compared to experimental RTR data obtained recently by Yamada et al. [Phys. Rev. A 59, 3673 (1999)] with a nickel-carbon multilayer structure.

  3. Optical phased array radiating optical vortex with manipulated topological charges.

    Science.gov (United States)

    Ma, Xiaoliang; Pu, Mingbo; Li, Xiong; Huang, Cheng; Pan, Wenbo; Zhao, Bo; Cui, Jianhua; Luo, Xiangang

    2015-02-23

    Optical antennas are key elements in quantum optics emitting and sensing, and behave wide range applications in optical domain. However, integration of optical antenna radiating orbital angular momentum is still a challenge in nano-scale. We theoretically demonstrate a sub-wavelength phased optical antenna array, which manipulates the distribution of the orbital angular momentum in the near field. Orbital angular momentum with topological charge of 4 can be obtained by controlling the phase distribution of the fundamental mode orbital angular momentum in each antenna element. Our results indicate this phased array may be utilized in high integrated optical communication systems.

  4. Quantum vacuum radiation in optical glass

    CERN Document Server

    Liberati, Stefano; Visser, Matt

    2011-01-01

    A recent experimental claim of the detection of analogue Hawking radiation in an optical system [PRL 105 (2010) 203901] has led to some controversy [PRL 107 (2011) 149401, 149402]. While this experiment strongly suggests some form of particle creation from the quantum vacuum (and hence it is per se very interesting), it is also true that it seems difficult to completely explain all features of the observations by adopting the perspective of a Hawking-like mechanism for the radiation. For instance, the observed photons are emitted parallel to the optical horizon, and the relevant optical horizon is itself defined in an unusual manner by combining group and phase velocities. This raises the question: Is this really Hawking radiation, or some other form of quantum vacuum radiation? Naive estimates of the amount of quantum vacuum radiation generated due to the rapidly changing refractive index --- sometimes called the dynamical Casimir effect --- are not encouraging. However we feel that naive estimates could be ...

  5. Exciton optical transitions in a hexagonal boron nitride single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Museur, L. [Laboratoire de Physique des Lasers - LPL, CNRS UMR 7538, Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Brasse, G.; Maine, S.; Ducastelle, F.; Loiseau, A. [ONERA - Laboratoire d' Etude des Microstructures - LEM, ONERA-CNRS, UMR 104, BP 72, 92322 Chatillon Cedex (France); Pierret, A. [ONERA - Laboratoire d' Etude des Microstructures - LEM, ONERA-CNRS, UMR 104, BP 72, 92322 Chatillon Cedex (France); CEA-CNRS, Institut Neel/CNRS, Universite J. Fourier, CEA/INAC/SP2M, 17 rue des Martyrs, 38 054 Grenoble Cedex 9 (France); Attal-Tretout, B. [ONERA - Departement Mesures Physiques - DMPh, 27 Chemin de la Huniere, 91761 Palaiseau Cedex (France); Barjon, J. [GEMaC, Universite de Versailles St Quentin, CNRS Bellevue, 1 Place Aristide Briand, 92195 Meudon Cedex (France); Watanabe, K.; Taniguchi, T. [National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044 (Japan); Kanaev, A. [Laboratoire des Sciences des Procedes et des Materiaux - LSPM, CNRS UPR 3407, Universite Paris 13, 93430 Villetaneuse (France)

    2011-06-15

    Near band gap photoluminescence (PL) of a hexagonal boron nitride single crystal has been studied at cryogenic temperatures with synchrotron radiation excitation. The PL signal is dominated by trapped-exciton optical transitions, while the photoluminescence excitation (PLE) spectra show features assigned to free excitons. Complementary photoconductivity and PLE measurements set the band gap transition energy to 6.4 eV and the Frenkel exciton binding energy larger than 380 meV. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Ultrafast imaging of terahertz Cherenkov waves and transition-like radiation in LiNbO₃.

    Science.gov (United States)

    Wang, Zhenyou; Su, FuHai; Hegmann, Frank A

    2015-03-23

    We use ultrafast phase-contrast imaging to directly observethe cone-like terahertz (THz) Cherenkov wave generated by optical rectification of femtosecond laser pulses focused into bulk lithium niobate (LiNbO₃) single crystals. The transverse imaging geometry allows the Cherenkov angle, THz wave velocity, and optical pump pulse group velocity to be measured. Furthermore, transition-like THz radiation generated by the femtosecond laser pulse at the air-crystal boundary is observed. The effect of optical pump pulse polarization on the generation of THz Cherenkov waves and transition-like radiation in LiNbO₃ is also investigated.

  7. Radiative Transitions in Charmonium from Lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Jozef Dudek; Robert Edwards; David Richards

    2006-01-17

    Radiative transitions between charmonium states offer an insight into the internal structure of heavy-quark bound states within QCD. We compute, for the first time within lattice QCD, the transition form-factors of various multipolarities between the lightest few charmonium states. In addition, we compute the experimentally unobservable, but physically interesting vector form-factors of the {eta}{sub c}, J/{psi} and {chi}{sub c0}. To this end we apply an ambitious combination of lattice techniques, computing three-point functions with heavy domain wall fermions on an anisotropic lattice within the quenched approximation. With an anisotropy {xi} = 3 at a{sub s} {approx} 0.1 fm we find a reasonable gross spectrum and a hyperfine splitting {approx}90 MeV, which compares favorably with other improved actions. In general, after extrapolation of lattice data at non-zero Q{sup 2} to the photopoint, our results agree within errors with all well measured experimental values. Furthermore, results are compared with the expectations of simple quark models where we find that many features are in agreement; beyond this we propose the possibility of constraining such models using our extracted values of physically unobservable quantities such as the J/{psi} quadrupole moment. We conclude that our methods are successful and propose to apply them to the problem of radiative transitions involving hybrid mesons, with the eventual goal of predicting hybrid meson photoproduction rates at the GlueX experiment.

  8. Turbulent Transitions in Optical Wave Propagation.

    Science.gov (United States)

    Pierangeli, D; Di Mei, F; Di Domenico, G; Agranat, A J; Conti, C; DelRe, E

    2016-10-28

    We report the direct observation of the onset of turbulence in propagating one-dimensional optical waves. The transition occurs as the disordered hosting material passes from being linear to one with extreme nonlinearity. As the response grows, increased wave interaction causes a modulational unstable quasihomogeneous flow to be superseded by a chaotic and spatially incoherent one. Statistical analysis of high-resolution wave behavior in the turbulent regime unveils the emergence of concomitant rogue waves. The transition, observed in a photorefractive ferroelectric crystal, introduces a new and rich experimental setting for the study of optical wave turbulence and information transport in conditions dominated by large fluctuations and extreme nonlinearity.

  9. Performance of the ATLAS Transition Radiation Tracker

    CERN Document Server

    Adelman, J; The ATLAS collaboration

    2011-01-01

    The ATLAS Transition Radiation Tracker (TRT) is a large straw tube tracking system that is the outermost of the three subsystems of the ATLAS Inner Detector (ID). With over 350,000 readout channels, the TRT provides both excellent particle identification capabilities and electron-pion separation, as well as contributing significantly to the resolution for high-pt tracks in the ID. As the instantaneous luminosity of the LHC increases, the occupancy of the TRT will increase as well. The low-occupancy tracking resolution and efficiency will be presented, as will be studies of resolution and PID at higher occupancies.

  10. Simulation of transition radiation based beam imaging from tilted targets

    Science.gov (United States)

    Sukhikh, L. G.; Kube, G.; Potylitsyn, A. P.

    2017-03-01

    Transverse beam profile diagnostics in linear electron accelerators is usually based on direct imaging of a beam spot via visible transition radiation. In this case the fundamental resolution limit is determined by radiation diffraction in the optical system. A method to measure beam sizes beyond the diffraction limit is to perform imaging dominated by a single-particle function (SPF), i.e. when the recorded image is dominated not by the transverse beam profile but by the image function of a point source (single electron). Knowledge of the SPF for an experimental setup allows one to extract the transverse beam size from an SPF dominated image. This paper presents an approach that allows one to calculate two-dimensional SPF dominated beam images, taking into account the target inclination angle and the depth-of-field effect. In conclusion, a simple fit function for beam size determination in the case under consideration is proposed and its applicability is tested under various conditions.

  11. Radiative data for allowed transitions in Ni XXV

    Energy Technology Data Exchange (ETDEWEB)

    Tully, John A [Departement Cassiopee, Observatoire de la Cote d' Azur, BP 4229, 06304 Nice Cedex 4 (France); Chidichimo, Marita C [Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2004-02-14

    Using Hibbert's configuration interaction program CIV3, which allows for relativistic effects by means of the Breit-Pauli approximation, we have computed radiative data for the 272 optically allowed transitions between levels i = 2l{sub 1} 2l{sub 2} S'L'J' and j = 2l{sub 3} n{sub 4}l{sub 4} SLJ with n{sub 4} = 2, 3, 4 in Be-like Ni XXV. Oscillator strengths f, transition probabilities A, line wavelengths {lambda} and energies E{sub ij} in cm{sup -1} are tabulated. We make detailed comparisons with related work done by other authors during the period 1977 to 2000.

  12. Coherent transition radiation diagnostic for electron bunch shape measurement at FELIX

    Science.gov (United States)

    Ding, Meisong; Weits, H. H.; Oepts, D.

    1997-02-01

    An optical autocorrelation system using coherent transition radiation has been set up to determine the electron bunch shape at FELIX. A polarisation interferometer and a 10 × 10 mm 2 pyroelectric detector are used to allow operation over a wide range of wavelength (from 30 μm to 10 mm) without strong variation in efficiency. An evacuated 15 m long overmoded waveguide is used to transport the transition radiation to the experimental area. The intensity of the transition radiation was measured and compared with our calculation. The phase-retrieval technique applied to the measured spectrum provides details of the electron bunch. The bunch shapes have been studied at different buncher phase settings. Measurements of coherent transition radiation and coherent undulator radiation are compared.

  13. Simulation study of transverse optical klystron radiation

    Institute of Scientific and Technical Information of China (English)

    XuHong-Liang; DiaoCao-Zheng; 等

    1997-01-01

    The radiation from a transverse optical klystron(TOK) is calculated by far field approximation and numerical integration,in which the effects of electron-beam emittance and energy spread are considered.Accurate electron-beam profiles have been experimentally determined and modeled by the Monte Carlo method.The calculated spectra illustrate the emittance of Hefei storage ring imposes on the spontaneous radiation of TOK.

  14. Ionizing radiation detector using multimode optical fibers

    Energy Technology Data Exchange (ETDEWEB)

    Suter, J.J. (Johns Hopkins Univ., Laurel, MD (United States). Applied Physics Lab.); Poret, J.C.; Rosen, M. (Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Materials Science and Engineering); Rifkind, J.M. (National Inst. of Health, Baltimore, MD (United States). Lab. of Cellular and Molecular Biology)

    1993-08-01

    An optical ionizing radiation detector, based on the attenuation of 850-nm light in 50/125-[mu]m multimode fibers, is described. The detector is especially well suited for application on spacecraft because of its small design. The detection element consists of a section of coiled fibers that has been designed to strip higher-order optical modes. Cylindrical radiation shields with atomic numbers ranging from Z = 13 (aluminum too) Z = 82 (lead) were placed around the ionizing radiation detector so that the effectiveness of the detector could be measured. By exposing the shields and the detector to 1.25-MeV cobalt 60 radiation, the mass attenuation coefficients of the shields were measured. The detector is based on the phenomenon that radiation creates optical color centers in glass fibers. Electron spin resonance spectroscopy performed on the 50/125-[mu]m fibers showed the presence of germanium oxide and phosphorus-based color centers. The intensity of these centers is directly related to the accumulated gamma radiation.

  15. Optical Radiation Bioeffects TO9

    Science.gov (United States)

    2009-02-01

    Absorption coefficient data from a spectrophotometry study. ............................ 23 Figure 15 Combined data from Figures 13 and 14, showing...distribution unlimited Figure 14 Absorption coefficient data from a spectrophotometry study. The results of Figure 13, and the...G. Y. Swanland, R. J. Thomas, and A. T. Tsin, 2006, Optical properties of ocular tissues in the near infrared region, Ophthalmic Technologies XVI

  16. Radiating subdispersive fractional optical solitons

    Energy Technology Data Exchange (ETDEWEB)

    Fujioka, J., E-mail: fujioka@fisica.unam.mx; Espinosa, A.; Rodríguez, R. F. [Departamento de Física Química, Instituto de Física, Universidad Nacional Autónoma de México, Mexico, DF 04510 (Mexico); Malomed, B. A. [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel)

    2014-09-01

    It was recently found [Fujioka et al., Phys. Lett. A 374, 1126 (2010)] that the propagation of solitary waves can be described by a fractional extension of the nonlinear Schrödinger (NLS) equation which involves a temporal fractional derivative (TFD) of order α > 2. In the present paper, we show that there is also another fractional extension of the NLS equation which contains a TFD with α < 2, and in this case, the new equation describes the propagation of radiating solitons. We show that the emission of the radiation (when α < 2) is explained by resonances at various frequencies between the pulses and the linear modes of the system. It is found that the new fractional NLS equation can be derived from a suitable Lagrangian density, and a fractional Noether's theorem can be applied to it, thus predicting the conservation of the Hamiltonian, momentum and energy.

  17. Interband optical transitions in ellipsoidal shaped nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kereselidze, Tamaz, E-mail: tamaz.kereselidze@tsu.ge [Faculty of Exact and Natural Sciences, Tbilisi State University, 0179 Tbilisi, Georgia (United States); Tchelidze, Tamar [Faculty of Exact and Natural Sciences, Tbilisi State University, 0179 Tbilisi, Georgia (United States); Devdariani, Alexander [St. - Petersburg State University, St. Petersburg 198904 (Russian Federation)

    2017-04-15

    The optical properties of crystalline semiconductor nanoparticles with ellipsoidal shape are investigated and discussed as a function of the shape-anisotropy parameter. The optical transition-matrix elements are calculated in the dipole approximation using perturbation theory and with a direct diagonalization of the appropriate Hamiltonian. The matrix elements involving the ground and first excited states are monotonic functions of the shape-anisotropy parameter, whereas matrix elements involving the highly excited states have zeros and extrema that are reflected in the behaviour of the corresponding transition probabilities. Moreover, some matrix elements involving the excited states have discontinuity. We demonstrate that, nanoparticles with ellipsoidal shape can be grown with the infrared as well as ultraviolet features.

  18. Optical fiber applied to radiation detection

    Energy Technology Data Exchange (ETDEWEB)

    Junior, Francisco A.B.; Costa, Antonella L.; Oliveira, Arno H. de; Vasconcelos, Danilo C., E-mail: fanbra@yahoo.com.br, E-mail: antonella@nuclear.ufmg.br, E-mail: heeren@nuclear.ufmg.br, E-mail: danilochagas@yahoo.com.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Escola de Engenharia. Departamento de Engenharia Nuclear

    2015-07-01

    In the last years, the production of optical fibers cables has make possible the development of a range of spectroscopic probes for in situ analysis performing beyond nondestructive tests, environmental monitoring, security investigation, application in radiotherapy for dose monitoring, verification and validation. In this work, a system using an optical fiber cable to light signal transmission from a NaI(Tl) radiation detector is presented. The innovative device takes advantage mainly of the optical fibers small signal attenuation and immunity to electromagnetic interference to application for radiation detection systems. The main aim was to simplify the detection system making it to reach areas where the conventional device cannot access due to its lack of mobility and external dimensions. Some tests with this innovative system are presented and the results stimulate the continuity of the researches. (author)

  19. Advanced optic fabrication using ultrafast laser radiation

    Science.gov (United States)

    Taylor, Lauren L.; Qiao, Jun; Qiao, Jie

    2016-03-01

    Advanced fabrication and finishing techniques are desired for freeform optics and integrated photonics. Methods including grinding, polishing and magnetorheological finishing used for final figuring and polishing of such optics are time consuming, expensive, and may be unsuitable for complex surface features while common photonics fabrication techniques often limit devices to planar geometries. Laser processing has been investigated as an alternative method for optic forming, surface polishing, structure writing, and welding, as direct tuning of laser parameters and flexible beam delivery are advantageous for complex freeform or photonics elements and material-specific processing. Continuous wave and pulsed laser radiation down to the nanosecond regime have been implemented to achieve nanoscale surface finishes through localized material melting, but the temporal extent of the laser-material interaction often results in the formation of a sub-surface heat affected zone. The temporal brevity of ultrafast laser radiation can allow for the direct vaporization of rough surface asperities with minimal melting, offering the potential for smooth, final surface quality with negligible heat affected material. High intensities achieved in focused ultrafast laser radiation can easily induce phase changes in the bulk of materials for processing applications. We have experimentally tested the effectiveness of ultrafast laser radiation as an alternative laser source for surface processing of monocrystalline silicon. Simulation of material heating associated with ultrafast laser-material interaction has been performed and used to investigate optimized processing parameters including repetition rate. The parameter optimization process and results of experimental processing will be presented.

  20. Radiative transitions from the psi (3095) to ordinary hadrons

    Energy Technology Data Exchange (ETDEWEB)

    Scharre, D.L.

    1980-05-01

    Preliminary results from the Mark II and Crystal Ball experiments on radiative transitions from the psi to ordinary hadrons are presented. In additon to the previously observed transitions to the eta, eta'(958), and f(1270), both groups observe a transition to a state which is tentatively identified as the E(1420).

  1. Coherent transition radiation diagnostic for electron bunch shape measurement at FELIX

    NARCIS (Netherlands)

    Ding, M. S.; Weits, H. H.; Oepts, D.

    1997-01-01

    An optical autocorrelation system using coherent transition radiation has been set up to determine the electron bunch shape at FELIX. A polarisation interferometer and a 10 x 10 mm(2) pyroelectric detector are used to allow operation over a wide range of wavelength (from 30 mu m to 10 mm) without st

  2. Nonlinear Optical Materials for the Smart Filtering of Optical Radiation.

    Science.gov (United States)

    Dini, Danilo; Calvete, Mário J F; Hanack, Michael

    2016-11-23

    The control of luminous radiation has extremely important implications for modern and future technologies as well as in medicine. In this Review, we detail chemical structures and their relevant photophysical features for various groups of materials, including organic dyes such as metalloporphyrins and metallophthalocyanines (and derivatives), other common organic materials, mixed metal complexes and clusters, fullerenes, dendrimeric nanocomposites, polymeric materials (organic and/or inorganic), inorganic semiconductors, and other nanoscopic materials, utilized or potentially useful for the realization of devices able to filter in a smart way an external radiation. The concept of smart is referred to the characteristic of those materials that are capable to filter the radiation in a dynamic way without the need of an ancillary system for the activation of the required transmission change. In particular, this Review gives emphasis to the nonlinear optical properties of photoactive materials for the function of optical power limiting. All known mechanisms of optical limiting have been analyzed and discussed for the different types of materials.

  3. Characteristic, parametric, and diffracted transition X-ray radiation for observation of accelerated particle beam profile

    Science.gov (United States)

    Chaikovska, I.; Chehab, R.; Artru, X.; Shchagin, A. V.

    2017-07-01

    The applicability of X-ray radiation for the observation of accelerated particle beam profiles is studied. Three types of quasi-monochromatic X-ray radiation excited by the particles in crystals are considered: characteristic X-ray radiation, parametric X-ray radiation, diffracted transition X-ray radiation. Radiation is collected at the right angle to the particle beam direction. It is show that the most intensive differential yield of X-ray radiation from Si crystal can be provided by characteristic radiation at incident electron energies up to tens MeV, by parametric radiation at incident electron energies from tens to hundreds MeV, by diffracted transition X-ray radiation at GeV and multi-GeV electron energies. Therefore these kinds of radiation are proposed for application to beam profile observation in the corresponding energy ranges of incident electrons. Some elements of X-ray optics for observation of the beam profile are discussed. The application of the DTR as a source of powerful tunable monochromatic linearly polarized X-ray beam excited by a multi-GeV electron beam on the crystal surface is proposed.

  4. Simulation of transition radiation based beam imaging from tilted targets

    Directory of Open Access Journals (Sweden)

    L. G. Sukhikh

    2017-03-01

    Full Text Available Transverse beam profile diagnostics in linear electron accelerators is usually based on direct imaging of a beam spot via visible transition radiation. In this case the fundamental resolution limit is determined by radiation diffraction in the optical system. A method to measure beam sizes beyond the diffraction limit is to perform imaging dominated by a single-particle function (SPF, i.e. when the recorded image is dominated not by the transverse beam profile but by the image function of a point source (single electron. Knowledge of the SPF for an experimental setup allows one to extract the transverse beam size from an SPF dominated image. This paper presents an approach that allows one to calculate two-dimensional SPF dominated beam images, taking into account the target inclination angle and the depth-of-field effect. In conclusion, a simple fit function for beam size determination in the case under consideration is proposed and its applicability is tested under various conditions.

  5. The ATLAS Transition Radiation Tracker: from dream to reality

    CERN Document Server

    Froidevaux, D

    2008-01-01

    This talk briefly reviews the history of the design, research and development, and construction of the ATLAS Transition Radiation Tracker. It also shows a few highlights of the first results obtained with cosmics and single beams during September 2008.

  6. Gravitational radiation from first-order phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Child, Hillary L.; Giblin, John T. Jr., E-mail: childh@kenyon.edu, E-mail: giblinj@kenyon.edu [Department of Physics, Kenyon College, 201 North College Road, Gambier, OH 43022 (United States)

    2012-10-01

    It is believed that first-order phase transitions at or around the GUT scale will produce high-frequency gravitational radiation. This radiation is a consequence of the collisions and coalescence of multiple bubbles during the transition. We employ high-resolution lattice simulations to numerically evolve a system of bubbles using only scalar fields, track the anisotropic stress during the process and evolve the metric perturbations associated with gravitational radiation. Although the radiation produced during the bubble collisions has previously been estimated, we find that the coalescence phase enhances this radiation even in the absence of a coupled fluid or turbulence. We comment on how these simulations scale and propose that the same enhancement should be found at the Electroweak scale; this modification should make direct detection of a first-order electroweak phase transition easier.

  7. Gravitational Radiation from First-Order Phase Transitions

    CERN Document Server

    Child, Hillary L

    2012-01-01

    It is believed that first order phase transitions at or around the GUT scale will produce high-frequency gravitational radiation. This radiation is a consequence of the collisions and coalescence of multiple bubbles during the transition. We employ high-resolution lattice simulations to numerically evolve a system of bubbles, track the anisotropic stress during the process and evolve the metric perturbations associated with gravitational radiation. Although the radiation produced during the bubble collisions has previously been estimated, we find that the coalescence phase that greatly enhances this radiation even in the absence of turbulence. We comment on how these simulations scale and propose that the same enhancement should be found at the Electroweak scale; this modification should make direct detection of a first-order electroweak phase transition easier.

  8. GEANT4 X-ray transition radiation package

    Science.gov (United States)

    Grichine, V. M.; Sadilov, S. S.

    2006-07-01

    Implementation of particular C++ classes in G EANT4 X-ray transition radiation (XTR) library is discussed. Recent developments concerning the transparent regular XTR radiator and XTR generated in straw tube (consisting three media) are considered in details. Simulation results are compared with experimental data.

  9. ATLAS Transition Radiation Tracker test-beam results

    CERN Document Server

    Åkesson, T; Baker, K; Baron, S; Benjamin, D; Bertelsen, H; Bondarenko, V; Bychkov, V; Callahan, J; Capéans-Garrido, M; Cardiel-Sas, L; Catinaccio, A; Cetin, S A; Cwetanski, Peter; Dam, M; Danielsson, H; Dittus, F; Dolgoshein, B A; Dressnandt, N; Driouichi, C; Ebenstein, W L; Eerola, Paule Anna Mari; Farthouat, Philippe; Fedin, O; Froidevaux, D; Gagnon, P; Grichkevitch, Y; Grigalashvili, N S; Hajduk, Z; Hansen, P; Kayumov, F; Keener, P T; Kekelidze, G D; Khristatchev, A; Konovalov, S; Koudine, L; Kovalenko, S; Kowalski, T; Kramarenko, V A; Krüger, K; Laritchev, A; Lichard, P; Luehring, F C; Lundberg, B; Maleev, V; Markina, I; McFarlane, K W; Mialkovski, V; Mitsou, V A; Mindur, B; Morozov, S; Munar, A; Muraviev, S; Nadtochy, A; Newcomer, F M; Ögren, H O; Oh, S H; Oleshko, S; Olszowska, J; Passmore, S; Patritchev, S; Peshekhonov, V D; Petti, R; Price, M; Rembser, C; Rohne, O; Romaniouk, A; Rust, D R; Ryabov, Yu; Shchegelskii, V; Seliverstov, D M; Shin, T; Shmeleva, A; Smirnov, S; Sosnovtsev, V V; Soutchkov, V; Spiridenkov, E; Tikhomirov, V; Van Berg, R; Vassilakopoulos, V I; Vassilieva, L; Wang, C; Williams, H H; Zalite, A

    2004-01-01

    Several prototypes of the Transition Radiation Tracker for the ATLAS experiment at the LHC have been built and tested at the CERN SPS accelerator. Results from detailed studies of the straw-tube hit registration efficiency and drift-time measurements and of the pion and electron spectra without and with radiators are presented. (10 refs).

  10. Design of a transition radiation detector for cosmic rays

    Science.gov (United States)

    Hartmann, G.; Mueller, D.; Prince, T.

    1975-01-01

    Transition radiation detectors consisting of sandwiches of plastic foam radiators and multiwire proportional chambers can be used to identify cosmic ray particles with energies gamma ? E/mc-squared is greater than 10 to the 3rd and to measure their energy in the region gamma is roughly equal to 10 to the 3rd

  11. Optical substrate materials for synchrotron radiation beamlines

    Energy Technology Data Exchange (ETDEWEB)

    Howells, M.R. [Lawrence Berkeley National Lab., CA (United States). Advanced Light Source; Paquin, R.A. [Univ. of Arizona, Tucson, AZ (United States). Optical Sciences Center

    1997-06-01

    The authors consider the materials choices available for making optical substrates for synchrotron radiation beam lines. They find that currently the optical surfaces can only be polished to the required finish in fused silica and other glasses, silicon, CVD silicon carbide, electroless nickel and 17-4 PH stainless steel. Substrates must therefore be made of one of these materials or of a metal that can be coated with electroless nickel. In the context of material choices for mirrors they explore the issues of dimensional stability, polishing, bending, cooling, and manufacturing strategy. They conclude that metals are best from an engineering and cost standpoint while the ceramics are best from a polishing standpoint. They then give discussions of specific materials as follows: silicon carbide, silicon, electroless nickel, Glidcop{trademark}, aluminum, precipitation-hardening stainless steel, mild steel, invar and superinvar. Finally they summarize conclusions and propose ideas for further research.

  12. Radiation from optically thin accretion discs

    Energy Technology Data Exchange (ETDEWEB)

    Tylenda, R. (Polska Akademia Nauk, Torun. Pracownia Astrofizyki)

    1981-01-01

    Accretion discs in cataclysmic variables with low rates of mass transfer, M < or approx. 10/sup 16/g s/sup -1/, have outer regions optically thin in continuum. A simple approach that allows one to calculate the radiation spectra from such discs is presented. A great number of disc models has been obtained in order to study the influence of various parameters (accretion rate, outer radius of the disc, inclination angle, mass of the accreting degenerate dwarf, viscosity parameter) of discs on the outgoing continuous spectra, emission lines and the UBV colours.

  13. Radiative transfer computations for optical beams

    CERN Document Server

    Kim, A D

    2003-01-01

    In this paper, we present a method for computing direct numerical simulations of narrow optical beam waves propagating and scattering in a plane-parallel medium. For these computations, we use Fourier and Chebyshev spectral methods for three-dimensional radiative transfer that also includes polar and azimuthal angle dependences. We treat anisotropic scattering with peaked forward scattering by using a Clenshaw-Curtis quadrature rule for the polar angle and an extended trapezoid rule for the azimuthal angle. To verify our results, we compare this spectral method to Monte Carlo simulations.

  14. Coherent transition radiation from REB in plasma ripple

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The coherent transition-radiation emission from an underdense relativistic beam of electrons, travelling through a dense plasma ripple, was studied. The evolution of this radiation field is described by a set of self-consistent pendulum-wave equations. Analytic calculations of the small-signal gain and numerical computations of the nonlinear saturation of this emission are presented. It is shown that such a device may provide a source of tunable coherent radiation ranging from the microwave to the infrared region.

  15. Radiation distribution sensing with normal optical fiber

    Energy Technology Data Exchange (ETDEWEB)

    Kawarabayashi, Jun; Mizuno, Ryoji; Naka, Ryotaro; Uritani, Akira; Watanabe, Ken-ichi; Iguchi, Tetsuo [Nagoya Univ., Dept. of Nuclear Engineering, Nagoya, Aichi (Japan); Tsujimura, Norio [Japan Nuclear Cycle Development Inst., Tokai Works, Tokai, Ibaraki (Japan)

    2002-12-01

    The purpose of this study is to develop a radiation distribution monitor using a normal plastic optical fiber. The monitor has a long operating length (10m-100m) and can obtain continuous radiation distributions. A principle of the position sensing is based on a time-of-flight technique. The characteristics of this monitor to beta particles, gamma rays and fast neutrons were obtained. The spatial resolutions for beta particles ({sup 90}Sr{sup -90}Y), gamma rays ({sup 137}Cs) and D-T neutrons were 30 cm, 37 cm and 13 cm, respectively. The detection efficiencies for the beta rays, the gamma rays and D-T neutrons were 0.11%, 1.6x10{sup -5}% and 5.4x10{sup -4}%, respectively. The effective attenuation length of the detection efficiency was 18m. New principle of the position sensing based on spectroscopic analysis was also proposed. A preliminary test showed that the spectrum observed at the end of the fiber depended on the position of the irradiated point. This fact shows that the radiation distributions were calculated from the spectrum by mathematical deconvolution technique. (author)

  16. Experimental observation and investigation of the prewave zone effect in optical diffraction radiation

    Directory of Open Access Journals (Sweden)

    P. Karataev

    2008-03-01

    Full Text Available Transition radiation (TR and diffraction radiation (DR has widely been used for both electron beam diagnostics and generation of intense radiation beams in the millimeter and the submillimeter wavelength range. Recently, it was theoretically predicted that TR and DR properties change either at extremely high energies of electrons or at long radiation wavelengths. This phenomenon was called a prewave zone effect. We have performed the first observation and detailed investigation of the prewave zone effect in optical diffraction radiation at 1.28 GeV electron beam at the KEK-Accelerator Test Facility (KEK-ATF. The beam energy at KEK-ATF is definitely not the highest one achieved in the world. Since we could easily observe the effect, at higher energies it might cause serious problems. We developed and applied a method for prewave zone suppression valid for optical wavelengths. Furthermore, a method for prewave zone suppression applicable for longer radiation wavelengths is discussed.

  17. Optical & Infrared Spectroscopy of Transiting Exoplanets

    Science.gov (United States)

    Griffith, C. A.; Tinetti, G.

    2010-10-01

    Two types of spectra can be measured from transiting extrasolar planets. The primary eclipse provides a transmission spectra of the exoplanet's limb as the planet passes in front of the star. These data probe the gas and particle composition of the atmosphere, as well as the atmospheric scale height. The secondary eclipse measures the emission of mainly the planet's dayside atmosphere from the planet plus star's emission minus the emission of star alone, when it eclipses the planet. These data probe the temperature and composition structure of the exoplanet. Only in the past 3 years, have infrared transmission and emission spectroscopy revealed the presence of the primary carbon and oxygen species (CH4, CO2, CO, and H2O). Efforts to constrain the abundances of these molecules are hindered by degenerate effects of the temperature and composition in the emission spectra. Transmission spectra, while less sensitive to the atmospheric temperatures, are difficult to interpret because the composition derived depends delicately on the assumed radius at a specified pressure level. This talk will discuss the correlations in the degenerate solutions that result from the radiative transfer analyses of both emission and transmission spectroscopy. The physical implications of these correlations are assessed in order to determine the temperature and composition structure of extrasolar planets, and their significance with respect to the exoplanet's chemistry and dynamics.

  18. Radiation optic neuropathy after external beam radiation therapy for acromegaly : report of two cases

    NARCIS (Netherlands)

    van den Bergh, ACM; Hoving, MA; Links, TP; Dullaart, RPF; Ranchor, AV; ter Weeme, CA; Canrinus, AA; Szabo, BG; Pott, JWR

    2003-01-01

    For diagnosing radiation optic neuropathy (RON) ophthalmological and imaging data were evaluated from 63 acromegalic patients, irradiated between 1967 and 1998. Two patients developed RON: one patient in one optic nerve 10 years and another patient in both optic nerves 5 months after radiation thera

  19. Radiation distribution sensing with normal optical fiber

    CERN Document Server

    Kawarabayashi, J; Naka, R; Uritani, A; Watanabe, K I; Iguchi, T; Tsujimura, N

    2002-01-01

    The purpose of this study is to develop a radiation distribution monitor using a normal plastic optical fiber. The monitor has a long operating length (10m-100m) and can obtain continuous radiation distributions. A principle of the position sensing is based on a time-of-flight technique. The characteristics of this monitor to beta particles, gamma rays and fast neutrons were obtained. The spatial resolutions for beta particles ( sup 9 sup 0 Sr sup - sup 9 sup 0 Y), gamma rays ( sup 1 sup 3 sup 7 Cs) and D-T neutrons were 30 cm, 37 cm and 13 cm, respectively. The detection efficiencies for the beta rays, the gamma rays and D-T neutrons were 0.11%, 1.6x10 sup - sup 5 % and 5.4x10 sup - sup 4 %, respectively. The effective attenuation length of the detection efficiency was 18m. New principle of the position sensing based on spectroscopic analysis was also proposed. A preliminary test showed that the spectrum observed at the end of the fiber depended on the position of the irradiated point. This fact shows that t...

  20. Boundary conditions and generalized functions in a transition radiation problem

    Science.gov (United States)

    Villavicencio, M.; Jiménez, J. L.

    2017-03-01

    The aim of this work is to show how all the components of the electromagnetic field involved in the transition radiation problem can be obtained using distribution functions. The handling of the products and derivatives of distributions appearing in the differential equations governing transition radiation, allows to obtain the necessary boundary conditions, additional to those implied by Maxwell's equations, in order to exactly determine the longitudinal components of the electromagnetic field. It is shown that this method is not only useful but it is really convenient to achieve a full analysis of the problem.

  1. Radiation Pressure Force from Optical Cycling on a Polyatomic Molecule

    CERN Document Server

    Kozyryev, Ivan; Matsuda, Kyle; Hemmerling, Boerge; Doyle, John M

    2016-01-01

    We demonstrate multiple photon cycling and radiative force deflection on the triatomic free radical strontium monohydroxide (SrOH). Optical cycling is achieved on SrOH in a cryogenic buffer-gas beam by employing the rotationally closed $P\\left(N''=1\\right)$ branch of the vibronic transition $\\tilde{X}^{2}\\Sigma^{+}\\left(000\\right)\\leftrightarrow\\tilde{A}^{2}\\Pi_{1/2}\\left(000\\right)$. A single repumping laser excites the Sr-O stretching vibrational mode, and photon cycling of the molecule deflects the SrOH beam by an angle of $0.2^{\\circ}$ via scattering of $\\sim100$ photons per molecule. This approach can be used for direct laser cooling of SrOH and more complex, isoelectronic species.

  2. Forbidden transitions in a magneto-optical trap.

    Science.gov (United States)

    Bhattacharya, M; Haimberger, C; Bigelow, N P

    2003-11-21

    We report the first observation of a nondipole transition in an ultracold atomic vapor. We excite the 3P-4P electric quadrupole (E2) transition in 23Na confined in a magneto-optical trap, and we demonstrate its application to high-resolution spectroscopy by making the first measurement of the hyperfine structure of the 4P(1/2) level and extracting the magnetic dipole constant A=30.6+/-0.1 MHz. We use cw optical-optical double resonance accompanied by photoionization to probe the transition.

  3. Radiative transitions in mesons in a non relativistic quark model

    OpenAIRE

    Bonnaz, R.; Silvestre-Brac, B.; Gignoux, C.

    2001-01-01

    In the framework of the non relativistic quark model, an exhaustive study of radiative transitions in mesons is performed. The emphasis is put on several points. Some traditional approximations (long wave length limit, non relativistic phase space, dipole approximation for E1 transitions, gaussian wave functions) are analyzed in detail and their effects commented. A complete treatment using three different types of realistic quark-antiquark potential is made. The overall agreement with experi...

  4. Radiative transitions in mesons in a non relativistic quark model

    CERN Document Server

    Bonnaz, R; Gignoux, C

    2002-01-01

    In the framework of the non relativistic quark model, an exhaustive study of radiative transitions in mesons is performed. The emphasis is put on several points. Some traditional approximations (long wave length limit, non relativistic phase space, dipole approximation for E1 transitions, gaussian wave functions) are analyzed in detail and their effects commented. A complete treatment using three different types of realistic quark-antiquark potential is made. The overall agreement with experimental data is quite good, but some improvements are suggested.

  5. Transition Radiation as a Secondary Standard Source in the VUV.

    Science.gov (United States)

    Böhm, W; Labs, D

    1971-09-01

    The optical radiation caused by electron bombardment of metallic surfaces was tested for its use as a secondary standard source in the VUV. Aluminum of high purity was found to be a suitable target material. The reproducibility of the radiation is of the order of 4% to 2% for 0.11 source was calibrated absolutely by comparison with a deuterium lamp of known absolute intensity.

  6. Comparison of Coherent Smith-Purcell radiation and Coherent Transition Radiation

    CERN Document Server

    Khodnevych, Vitalii; Bezshyyko, Oleg

    2016-01-01

    Smith-Purcell radiation and Transition Radiation are two radiative phenomenon that occur in charged particles accelerators. For both the emission can be significantly enhanced with sufficiently short pulses and both can be used to measure the form factor of the pulse. We compare the yield of these phenomenon in different configurations and look at their application as bunch length monitors, including background filtering and rejection. We apply these calculations to the specific case of the CLIO Free Electron laser.

  7. Effects of transverse electron beam size on transition radiation angular distribution

    Energy Technology Data Exchange (ETDEWEB)

    Chiadroni, E., E-mail: enrica.chiadroni@lnf.infn.it [Laboratori Nazionali di Frascati-INFN, via E. Fermi, 40, 00044 Frascati (Italy); Castellano, M. [Laboratori Nazionali di Frascati-INFN, via E. Fermi, 40, 00044 Frascati (Italy); Cianchi, A. [University of Rome ' Tor Vergata' and INFN-Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome (Italy); Honkavaara, K.; Kube, G. [Deutsches Elektronen-Synchrotron, Notkestrasse 85, 22607 Hamburg (Germany)

    2012-05-01

    In this paper we consider the effect of the transverse electron beam size on the Optical Transition Radiation (OTR) angular distribution in case of both incoherent and coherent emission. Our results confute the theoretical argumentations presented first in Optics Communications 211, 109 (2002), which predicts a dependence of the incoherent OTR angular distribution on the beam size and emission wavelength. We present here theoretical and experimental data not only to validate the well-established Ginzburg-Frank theory, but also to show the impact of the transverse beam size in case of coherent emission.

  8. Recent progress with the Transition Radiation Tracker

    CERN Document Server

    Froidevaux, D

    Start-up of end-cap assembly in Russia On July 2nd at PNPI (first photo) and on August 1st at JINR Dubna (second photo), the first straws were inserted into the first 4-plane end-cap wheels, each containing 3072 straws. The straws were glued, the radiator stacks were installed and the PNPI wheel was tested for gas leaks. An initial large leak rate was observed and fixed by increasing somewhat the amount of glue around each straw end-piece and improving the leak-tightness of the testing equipment itself. PNPI will assemble a total of 48 4-plane wheels of type A using two assembly lines. JINR Dubna will assemble a total of 32 4-plane wheels of type B using a single assembly line. The next steps are the gluing of the so-called active webs (printed circuit boards connecting high voltage and signal lines from straw/wire to HV supply and front-end boards), followed by wiring, and will take place in November. PNPI and JINR Dubna should start mass production in February-March next year. Barrel module produc...

  9. Coherent optical transitions in implanted nitrogen vacancy centers.

    Science.gov (United States)

    Chu, Y; de Leon, N P; Shields, B J; Hausmann, B; Evans, R; Togan, E; Burek, M J; Markham, M; Stacey, A; Zibrov, A S; Yacoby, A; Twitchen, D J; Loncar, M; Park, H; Maletinsky, P; Lukin, M D

    2014-01-01

    We report the observation of stable optical transitions in nitrogen-vacancy (NV) centers created by ion implantation. Using a combination of high temperature annealing and subsequent surface treatment, we reproducibly create NV centers with zero-phonon lines (ZPL) exhibiting spectral diffusion that is close to the lifetime-limited optical line width. The residual spectral diffusion is further reduced by using resonant optical pumping to maintain the NV(-) charge state. This approach allows for placement of NV centers with excellent optical coherence in a well-defined device layer, which is a crucial step in the development of diamond-based devices for quantum optics, nanophotonics, and quantum information science.

  10. All-optical radiation reaction at 10²¹ W/cm².

    Science.gov (United States)

    Vranic, M; Martins, J L; Vieira, J; Fonseca, R A; Silva, L O

    2014-09-26

    Using full-scale 3D particle-in-cell simulations we show that the radiation reaction dominated regime can be reached in an all-optical configuration through the collision of a ~1 GeV laser wakefield accelerated electron bunch with a counterpropagating laser pulse. In this configuration the radiation reaction significantly reduces the energy of the particle bunch, thus providing clear experimental signatures for the process with currently available lasers. We also show that the transition between the classical and quantum radiation reaction could be investigated in the same configuration with laser intensities of 10²³ W/cm².

  11. Length optimization of an S-shaped transition between offset optical waveguides.

    Science.gov (United States)

    Marcuse, D

    1978-03-01

    We derive expressions for the radiation loss of an S-shaped waveguide transition used to connect two straight integrated optics waveguides that are offset with respect to each other. It is assumed that the diffused integrated optics waveguides are produced with the help of an electron beam machine that allows beam positioning in the y direction only in discrete steps. We thus must consider staircase approximations to the desired smooth S-shaped curves. A waveguide whose axis consists of a staircase suffers radiation losses due to the quasi-periodic deformation of its axis. A second loss contribution comes from the S-shape of the waveguide axis. The sum of these loss contributions assumes a minimum that defines the optimum length of the transition waveguide.

  12. Analysis and Simulation of Adiabatic Bend Transitions in Optical Fibers

    Institute of Scientific and Technical Information of China (English)

    YAO Lei; LOU Shu-Qin; JIAN Shui-Sheng

    2009-01-01

    A low-loss criterion for bend transitions in optical fibers is proposed. An optical fiber can be tightly bent with low loss to be adiabatic for the fundamental mode, provided that an approximate upper bound on the rate of change of bend curvature for a given bend curvature is satisfied. Two typical adiabatic bend transition paths, the optimum profile and linear profile, are analyzed and studied numerically. A realizable adiabatic transition with an Archimedean spiral profile is introduced for low bend loss in tightly bent optical fibers. Design of the transitions is based on modeling of the propagation and coupling characteristics of the core and cladding modes,which clearly illustrate the physical processes involved.

  13. Optical fibers and their applications for radiation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kakuta, Tsunemi [Japan Atomic Energy Research Inst., Tokyo (Japan)

    1998-07-01

    When optical fibers are used in a strong radiation field, it is necessary to increase the radiation-resistant capacity. Aiming at the improvement of such property, the characteristics of recent optical fibers made from quartz-glass were reviewed and the newly developed techniques for radiation measurement using those fibers were summarized in this report. Since optical fibers became able to use in the levels near the core conditions, their applications have started in various fields of technologies related to radiation. By combining the optical fibers and a small sensor, it became possible to act as `Key Component` for measuring wide range radioactivity from a trace activity to a strong radiation field in the reactor core. Presently, the fibers are utilized for investigation of the optical mechanisms related in radiation, evaluation of their validities so on. Further, the optical fibers are expected to utilize in a multi-parametric measuring system which allows to concomitantly determine the radiation, temperature, pressure, flow amount etc. as an incore monitor. (M.N.)

  14. Physics: Optical transition seen in antihydrogen

    Science.gov (United States)

    Ulmer, Stefan

    2017-01-01

    Precise measurements of antimatter systems might cast light on why the Universe is dominated by matter. The observation of a transition in an antihydrogen atom heralds the next wave of high-precision antimatter studies. See Letter p.506

  15. L-shell radiative transition rates by selective synchrotron ionization

    Energy Technology Data Exchange (ETDEWEB)

    Bonetto, R D [Centro de Investigacion y Desarrollo en Ciencias Aplicadas Dr. Jorge J. Ronco, CONICET-UNLP, Calle 47 No. 257-Cc 59 (1900) La Plata (Argentina); Carreras, A C [Facultad de Matematica, AstronomIa y FIsica, Universidad Nacional de Cordoba, Ciudad Universitaria (5000) Cordoba (Argentina); Trincavelli, J [Facultad de Matematica, AstronomIa y FIsica, Universidad Nacional de Cordoba, Ciudad Universitaria (5000) Cordoba (Argentina); Castellano, G [Facultad de Matematica, AstronomIa y FIsica, Universidad Nacional de Cordoba, Ciudad Universitaria (5000) Cordoba (Argentina)

    2004-04-14

    Relative L-shell radiative transition rates were obtained for a number of decays in Gd, Dy, Er, Yb, Hf, Ta and Re by means of a method for refining atomic and experimental parameters involved in the spectral analysis of x-ray irradiated samples. For this purpose, pure samples were bombarded with monochromatic synchrotron radiation tuning the incident x-ray energy in order to allow selective ionization of the different atomic shells. The results presented are compared to experimental and theoretical values published by other authors. A good general agreement was found and some particular discrepancies are discussed.

  16. Performance of the AMS-02 Transition Radiation Detector

    CERN Document Server

    Doetinchem, P; Karpinski, W; Kirn, T; Lübelsmeyer, K; Orboeck, J; Schael, S; Schultz von Dratzig, A; Schwering, G; Siedenburg, T; Siedling, R; Wallraff, W; Becker, U; Bürger, J; Henning, R; Kounine, A; Koutsenko, V F; Wyatt, J

    2006-01-01

    For cosmic particle spectroscopy on the International Space Station the AMS experiment will be equipped with a Transition Radiation Detector (TRD) to improve particle identification. The TRD has 20 layers of fleece radiator with Xe/CO2 proportional mode straw tube chambers. They are supported in a conically shaped octagon structure made of CFC-Al-honeycomb. For low power consumption VA analog multiplexers are used as front-end readout. A 20 layer prototype built from final design components has achieved proton rejections from 100 to 2000 at 90% electron efficiency for proton beam energies up to 250 GeV with cluster counting, likelihood and neural net selection algorithms.

  17. Proton radiation effects on optical constants of Al film reflector

    Institute of Scientific and Technical Information of China (English)

    Liu Hai; Wei Qiang; He Shi-Yu; Zhao Dan

    2006-01-01

    The Al film reflectors can yield a high-reflectance over a broad wavelength region, and have been widely used in the spacecraft optical instruments for high quality optical applications. Under the irradiation of charged particles in the Earth radiation belt, the reflectors could be deteriorated. In order to reveal the deterioration mechanism, the change in optical constants of Al film reflector induced by proton radiation with 60 keV was studied in an environment of vacuum with heat sink. Experimental results showed that when the radiation damage primarily occurs in the Al reflecting film,the extinction coefficient k will gradually decrease with increasing radiation fluence, which results in the decrease of the energies of reflective light. Therefore, the proton radiation induced an obvious degradation of spectral reflectance in the wavelength region from 200 to 800 nm on the Al film reflector.

  18. Optical imaging of radiation-induced metabolic changes in radiation-sensitive and resistant cancer cells

    Science.gov (United States)

    Alhallak, Kinan; Jenkins, Samir V.; Lee, David E.; Greene, Nicholas P.; Quinn, Kyle P.; Griffin, Robert J.; Dings, Ruud P. M.; Rajaram, Narasimhan

    2017-06-01

    Radiation resistance remains a significant problem for cancer patients, especially due to the time required to definitively determine treatment outcome. For fractionated radiation therapy, nearly 7 to 8 weeks can elapse before a tumor is deemed to be radiation-resistant. We used the optical redox ratio of FAD/(FAD+NADH) to identify early metabolic changes in radiation-resistant lung cancer cells. These radiation-resistant human A549 lung cancer cells were developed by exposing the parental A549 cells to repeated doses of radiation (2 Gy). Although there were no significant differences in the optical redox ratio between the parental and resistant cell lines prior to radiation, there was a significant decrease in the optical redox ratio of the radiation-resistant cells 24 h after a single radiation exposure (p=0.01). This change in the redox ratio was indicative of increased catabolism of glucose in the resistant cells after radiation and was associated with significantly greater protein content of hypoxia-inducible factor 1 (HIF-1α), a key promoter of glycolytic metabolism. Our results demonstrate that the optical redox ratio could provide a rapid method of determining radiation resistance status based on early metabolic changes in cancer cells.

  19. Optical imaging of radiation-induced metabolic changes in radiation-sensitive and resistant cancer cells.

    Science.gov (United States)

    Alhallak, Kinan; Jenkins, Samir V; Lee, David E; Greene, Nicholas P; Quinn, Kyle P; Griffin, Robert J; Dings, Ruud P M; Rajaram, Narasimhan

    2017-06-01

    Radiation resistance remains a significant problem for cancer patients, especially due to the time required to definitively determine treatment outcome. For fractionated radiation therapy, nearly 7 to 8 weeks can elapse before a tumor is deemed to be radiation-resistant. We used the optical redox ratio of FAD / ( FAD + NADH ) to identify early metabolic changes in radiation-resistant lung cancer cells. These radiation-resistant human A549 lung cancer cells were developed by exposing the parental A549 cells to repeated doses of radiation (2 Gy). Although there were no significant differences in the optical redox ratio between the parental and resistant cell lines prior to radiation, there was a significant decrease in the optical redox ratio of the radiation-resistant cells 24 h after a single radiation exposure ( p = 0.01 ). This change in the redox ratio was indicative of increased catabolism of glucose in the resistant cells after radiation and was associated with significantly greater protein content of hypoxia-inducible factor 1 ( HIF - 1 ? ), a key promoter of glycolytic metabolism. Our results demonstrate that the optical redox ratio could provide a rapid method of determining radiation resistance status based on early metabolic changes in cancer cells.

  20. Magnetic-dipole transitions in highly charged ions as a basis of ultraprecise optical clocks.

    Science.gov (United States)

    Yudin, V I; Taichenachev, A V; Derevianko, A

    2014-12-05

    We evaluate the feasibility of using magnetic-dipole (M1) transitions in highly charged ions as a basis of an optical atomic clockwork of exceptional accuracy. We consider a range of possibilities, including M1 transitions between clock levels of the same fine-structure and hyperfine-structure manifolds. In highly charged ions these transitions lie in the optical part of the spectra and can be probed with lasers. The most direct advantage of our proposal comes from the low degeneracy of clock levels and the simplicity of atomic structure in combination with negligible quadrupolar shift. We demonstrate that such clocks can have projected fractional accuracies below the 10^{-20}-10^{-21} level for all common systematic effects, such as blackbody radiation, Zeeman, ac-Stark, and quadrupolar shifts.

  1. Virtual single-photon transition interrupted: time-gated optical gain and loss

    CERN Document Server

    Herrmann, Jens; Locher, Reto; Sabbar, Mazyar; Rivière, Paula; Saalmann, Ulf; Rost, Jan-Michael; Gallmann, Lukas; Keller, Ursula

    2012-01-01

    The optical response of a virtual dipole transition triggered by an ultra-short light pulse intrinsically consists of both absorption and emission in time and frequency. So far, this fundamental feature has been hidden by the time-integrated detection. However, as we will demonstrate, the time-dependence during a virtual single-photon transition can be mapped out and controlled by a second electromagnetic field. The resulting time-gated optical signal shows previously unexpected radiation gain and loss at different delays of the control pulse. The model presented here can be applied to any system that assumes a two-level character through near-resonant optical dipole excitation, whether they are of atomic, molecular or even solid-state nature. We validate the theoretical model by an attosecond transient absorption spectroscopy experiment in helium. Our model and the experimental data display excellent qualitative agreement.

  2. Energy levels and radiative rates for transitions in Ti VII

    CERN Document Server

    Aggarwal, KM

    2013-01-01

    We report calculations of energy levels, radiative rates, oscillator strengths and line strengths for transitions among the lowest 231 levels of Ti VII. The general-purpose relativistic atomic structure package ({\\sc grasp}) and flexible atomic code ({\\sc fac}) are adopted for the calculations. Radiative rates, oscillator strengths and line strengths are provided for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2) and magnetic quadrupole (M2) transitions among the 231 levels, although calculations have been performed for a much larger number of levels (159,162). In addition, lifetimes for all 231 levels are listed. Comparisons are made with existing results and the accuracy of the data is assessed. In particular, the most recent calculations reported by Singh {\\em et al} [Can J. Phys. {\\bf 90} (2012) 833] are found to be unreliable, with discrepancies for energy levels of up to 1 Ryd and for radiative rates of up to five orders of magnitude for several transitions, particularly the we...

  3. Successful beam tests for ALICE Transition Radiation Detector

    CERN Multimedia

    2002-01-01

    Another round of beam tests of prototypes for the Transition Radiation Detector (TRD) for ALICE has been completed and there are already some good results. Mass production of the components of the detector will start early next year.   Top view of the setup for the Transition Radiation Detector prototype tests at CERN.On the left, can be seen the full-scale TRD prototype together with four smaller versions. These are busy days for the TRD (Transition Radiation Detector) team of ALICE. Twenty people - mainly from Germany, but also from Russia and Japan - were working hard during the beam tests this autumn at CERN to assess the performance of their detector prototypes. Analysis of the data shows that the TRD can achieve the desired physics goal even for the highest conceivable multiplicities in lead-lead collisions at the LHC. In its final configuration in the ALICE experiment, the TRD will greatly help in identifying high-momentum electrons, which are 'needles in a haystack' that consists mostly of...

  4. Serial Diffusion Tensor Imaging of the Optic Radiations after Acute Optic Neuritis.

    Science.gov (United States)

    Kolbe, Scott C; van der Walt, Anneke; Butzkueven, Helmut; Klistorner, Alexander; Egan, Gary F; Kilpatrick, Trevor J

    2016-01-01

    Previous studies have reported diffusion tensor imaging (DTI) changes within the optic radiations of patients after optic neuritis (ON). We aimed to study optic radiation DTI changes over 12 months following acute ON and to study correlations between DTI parameters and damage to the optic nerve and primary visual cortex (V1). We measured DTI parameters [fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD)] from the optic radiations of 38 acute ON patients at presentation and 6 and 12 months after acute ON. In addition, we measured retinal nerve fibre layer thickness, visual evoked potential amplitude, optic radiation lesion load, and V1 thickness. At baseline, FA was reduced and RD and MD were increased compared to control. Over 12 months, FA reduced in patients at an average rate of -2.6% per annum (control = -0.51%; p = 0.006). Change in FA, RD, and MD correlated with V1 thinning over 12 months (FA: R = 0.450, p = 0.006; RD: R = -0.428, p = 0.009; MD: R = -0.365, p = 0.029). In patients with no optic radiation lesions, AD significantly correlated with RNFL thinning at 12 months (R = 0.489, p = 0.039). In conclusion, DTI can detect optic radiation changes over 12 months following acute ON that correlate with optic nerve and V1 damage.

  5. Serial Diffusion Tensor Imaging of the Optic Radiations after Acute Optic Neuritis

    Directory of Open Access Journals (Sweden)

    Scott C. Kolbe

    2016-01-01

    Full Text Available Previous studies have reported diffusion tensor imaging (DTI changes within the optic radiations of patients after optic neuritis (ON. We aimed to study optic radiation DTI changes over 12 months following acute ON and to study correlations between DTI parameters and damage to the optic nerve and primary visual cortex (V1. We measured DTI parameters [fractional anisotropy (FA, axial diffusivity (AD, radial diffusivity (RD, and mean diffusivity (MD] from the optic radiations of 38 acute ON patients at presentation and 6 and 12 months after acute ON. In addition, we measured retinal nerve fibre layer thickness, visual evoked potential amplitude, optic radiation lesion load, and V1 thickness. At baseline, FA was reduced and RD and MD were increased compared to control. Over 12 months, FA reduced in patients at an average rate of −2.6% per annum (control = −0.51%; p=0.006. Change in FA, RD, and MD correlated with V1 thinning over 12 months (FA: R=0.450, p=0.006; RD: R=-0.428, p=0.009; MD: R=-0.365, p=0.029. In patients with no optic radiation lesions, AD significantly correlated with RNFL thinning at 12 months (R=0.489, p=0.039. In conclusion, DTI can detect optic radiation changes over 12 months following acute ON that correlate with optic nerve and V1 damage.

  6. The extraordinary radiation pattern of an optical rod antenna

    CERN Document Server

    Zhao, Chenglong

    2010-01-01

    We investigated the radiation pattern of an optical rod antenna and found that it had many features compared with its conventional radio-wave equivalents. After defining a parameter {\\Lambda} = {\\lambda}eff /{\\lambda}, which was the ratio of the effective wavelength of the rod antenna to the incident wavelength, we found that {\\Lambda} had a great influence on the radiation pattern. Even the radiation pattern with a higher resonant order is without side lobes and results in a sharper directivity, which provides new design flexibilities in improving the directivities of the optical antennas.

  7. Radiative Thermo-Refractive Noise for Transmissive Optics

    CERN Document Server

    Dwyer, Sheila

    2014-01-01

    Radiative losses have traditionally been neglected in the calculation of thermal noise of transmissive optical elements because for the most commonly used geometries they are small compared to losses due to thermal conduction. We explore the use of such transmissive optical elements in extremely noise-sensitive environments such as the arm cavities of future gravitational-wave interferometers. This drives us to a geometry regime where radiative losses are no longer negligible. In this paper we derive the thermal noise associated with such radiative losses and compare it to other known sources of thermal noise.

  8. Optically induced structural phase transitions in ion Coulomb crystals

    DEFF Research Database (Denmark)

    Horak, Peter; Dantan, Aurelien Romain; Drewsen, Michael

    2012-01-01

    , such as body-centered cubic and face-centered cubic, can be suppressed by a proper choice of the potential depth and periodicity. Furthermore, by varying the harmonic trap parameters and/or the optical potential in time, controlled transitions between crystal structures can be obtained with close to unit......We investigate numerically the structural dynamics of ion Coulomb crystals confined in a three-dimensional harmonic trap when influenced by an additional one-dimensional optically induced periodical potential. We demonstrate that transitions between thermally excited crystal structures...

  9. The absolute frequency of the 87Sr optical clock transition

    DEFF Research Database (Denmark)

    Campbell, Gretchen K.; Ludlow, Andrew D.; Blatt, Sebastian;

    2008-01-01

    The absolute frequency of the 1S0–3P0 clock transition of 87Sr has been measured to be 429 228 004 229 873.65 (37) Hz using lattice-confined atoms, where the fractional uncertainty of 8.6 × 10-16 represents one of the most accurate measurements of an atomic transition frequency to date. After a d...... is made possible using a femtosecond laser based optical frequency comb to phase coherently connect the optical and microwave spectral regions and by a 3.5 km fibre transfer scheme to compare the remotely located clock signals....

  10. Inner-shell magnetic dipole transition in Tm atom as a candidate for optical lattice clocks

    CERN Document Server

    Sukachev, D; Tolstikhina, I; Kalganova, E; Vishnyakova, G; Khabarova, K; Tregubov, D; Golovizin, A; Sorokin, V; Kolachevsky, N

    2016-01-01

    We consider a narrow magneto-dipole transition in the $^{169}$Tm atom at the wavelength of $1.14\\,\\mu$m as a candidate for a 2D optical lattice clock. Calculating dynamic polarizabilities of the two clock levels $[\\text{Xe}]4f^{13}6s^2 (J=7/2)$ and $[\\text{Xe}]4f^{13}6s^2 (J=5/2)$ in the spectral range from $250\\,$nm to $1200\\,$nm, we suggest the "magic" wavelength for the optical lattice at $807\\,$nm. Frequency shifts due to black-body radiation (BBR), the van der Waals interaction, the magnetic dipole-dipole interaction and other effects which can perturb the transition frequency are calculated. The transition at $1.14\\,\\mu$m demonstrates low sensitivity to the BBR shift corresponding to $8\\times10^{-17}$ in fractional units at room temperature which makes it an interesting candidate for high-performance optical clocks. The total estimated frequency uncertainty is less than $5 \\times 10^{-18}$ in fractional units. By direct excitation of the $1.14\\,\\mu$m transition in Tm atoms loaded into an optical dipole ...

  11. Optics of Chromites and Charge-Transfer Transitions

    Directory of Open Access Journals (Sweden)

    Andrei V. Zenkov

    2008-01-01

    Full Text Available Specific features of the charge-transfer (CT states and O2p→Cr3d transitions in the octahedral (CrO69− complex are considered in the cluster approach. The reduced matrix elements of the electric-dipole transition operator are calculated on many-electron wave functions of the complex corresponding to the initial and final states of a CT transition. Modeling the optic spectrum of chromites has yielded a complicated CT band. The model spectrum is in satisfactory agreement with experimental data which demonstrates the limited validity of the generally accepted concept of a simple structure of CT spectra.

  12. A transition radiation detector for kaon/pion separation

    Energy Technology Data Exchange (ETDEWEB)

    Baake, M.; Diekmann, B.; Gebert, F.; Heinloth, K.; Holzkamp, S.; Koersgen, G.; Voigtlaender-Tetzner, A. (Bonn Univ. (Germany, F.R.)); Bagdassarian, L.; Kazarian, C.; Oganessian, A. (Erevanskij Gosudarstvennyj Univ. (USSR))

    1989-09-01

    The experiment WA69 at the CERN Omega spectrometer facility has studied fixed target photon and hadron production of inclusive hadronic final states with tagged photon beams of 65-175 GeV in comparison to charged hadron beams ({pi} and K) of 80 and 140 GeV fixed energies. For the identification of final state pions and kaons above 100 GeV/c a transition radiation detector (TRAD) has been developed. This detector was constructed of 12 modules, each consisting of a polypropylene fibre radiator and a proportional chamber with a xenon/methane gas mixture to detect the transition radiation produced by fast moving charged particles. We give a description of the detector setup and working conditions. As a first result obtained with the TRAD the ratio of photoproduced kaons and pions in the extreme forward regime (x{sub F}>0.7 and -t<1 GeV{sup 2}) is measured to be 10.2(+-1.7)% which is in agreement with VDM predictions. (orig.).

  13. Surface wave chemical detector using optical radiation

    Science.gov (United States)

    Thundat, Thomas G.; Warmack, Robert J.

    2007-07-17

    A surface wave chemical detector comprising at least one surface wave substrate, each of said substrates having a surface wave and at least one measurable surface wave parameter; means for exposing said surface wave substrate to an unknown sample of at least one chemical to be analyzed, said substrate adsorbing said at least one chemical to be sensed if present in said sample; a source of radiation for radiating said surface wave substrate with different wavelengths of said radiation, said surface wave parameter being changed by said adsorbing; and means for recording signals representative of said surface wave parameter of each of said surface wave substrates responsive to said radiation of said different wavelengths, measurable changes of said parameter due to adsorbing said chemical defining a unique signature of a detected chemical.

  14. Fibre Optical Radiation Sensing System for TESLA

    CERN Document Server

    Körfer, M

    2001-01-01

    High energy accelerators generate ionising radiation along the beam-line and at target places. This radiation is related to beam losses or dark currents. The in-situ measurement of this ionising dose that is distributed over long distances or large areas requires a new monitor system. This paper presents first results and the concept of such a monitor system at the Tesla Test Facility.

  15. Optical systems for synchrotron radiation. Lecture 1. Introductory topics. Revision

    Energy Technology Data Exchange (ETDEWEB)

    Howells, M.R.

    1986-02-01

    Various fundamental topics are considered which underlie the design and use of optical systems for synchrotron radiation. The point of view of linear system theory is chosen which acts as a unifying concept throughout the series. In this context the important optical quantities usually appear as either impulse response functions (Green's functions) or frequency transfer functions (Fourier Transforms of the Green's functions). Topics include the damped harmonic oscillator, free-space optical field propagation, optical properties of materials, dispersion, and the Kramers-Kronig relations.

  16. Quantum phase transitions in low-dimensional optical lattices

    NARCIS (Netherlands)

    Di Liberto, M.F.

    2015-01-01

    In this thesis, we discuss quantum phase transitions in low-dimensional optical lattices, namely one- and two-dimensional lattices. The dimensional confinement is realized in experiments by suppressing the hopping in the extra dimensions through a deep potential barrier that prevents the atoms to tu

  17. Optically induced structural phase transitions in ion Coulomb crystals

    DEFF Research Database (Denmark)

    Horak, Peter; Dantan, Aurelien Romain; Drewsen, Michael

    2012-01-01

    , such as body-centered cubic and face-centered cubic, can be suppressed by a proper choice of the potential depth and periodicity. Furthermore, by varying the harmonic trap parameters and/or the optical potential in time, controlled transitions between crystal structures can be obtained with close to unit...

  18. Chirality and angular momentum in optical radiation

    CERN Document Server

    Coles, Matt M

    2012-01-01

    This paper develops, in precise quantum electrodynamic terms, photonic attributes of the "optical chirality density", one of several measures long known to be conserved quantities for a vacuum electromagnetic field. The analysis lends insights into some recent interpretations of chiroptical experiments, in which this measure, and an associated chirality flux, have been treated as representing physically distinctive "superchiral" phenomena. In the fully quantized formalism the chirality density is promoted to operator status, whose exploration with reference to an arbitrary polarization basis reveals relationships to optical angular momentum and helicity operators. Analyzing multi-mode beams with complex wave-front structures, notably Laguerre-Gaussian modes, affords a deeper understanding of the interplay between optical chirality and optical angular momentum. By developing theory with due cognizance of the photonic character of light, it emerges that only the spin angular momentum of light is engaged in such...

  19. Glaucoma severity affects diffusion tensor imaging (DTI) parameters of the optic nerve and optic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Sidek, S. [Department of Biomedical Imaging, University Malaya, Research Imaging Centre, Faculty of Medicine, University Malaya (Malaysia); Medical Imaging Unit, Faculty of Medicine, Universiti Teknologi MARA, Selangor (Malaysia); Ramli, N. [Department of Biomedical Imaging, University Malaya, Research Imaging Centre, Faculty of Medicine, University Malaya (Malaysia); Rahmat, K., E-mail: katt_xr2000@yahoo.com [Department of Biomedical Imaging, University Malaya, Research Imaging Centre, Faculty of Medicine, University Malaya (Malaysia); Ramli, N.M.; Abdulrahman, F. [Department of Ophthalmology, Faculty of Medicine, University Malaya, Kuala Lumpur (Malaysia); Tan, L.K. [Department of Biomedical Imaging, University Malaya, Research Imaging Centre, Faculty of Medicine, University Malaya (Malaysia)

    2014-08-15

    Objectives: To evaluate whether MR diffusion tensor imaging (DTI) of the optic nerve and optic radiation in glaucoma patients provides parameters to discriminate between mild and severe glaucoma and to determine whether DTI derived indices correlate with retinal nerve fibre layer (RNFL) thickness. Methods: 3-Tesla DTI was performed on 90 subjects (30 normal, 30 mild glaucoma and 30 severe glaucoma subjects) and the FA and MD of the optic nerve and optic radiation were measured. The categorisation into mild and severe glaucoma was done using the Hodapp–Parrish–Anderson (HPA) classification. RNFL thickness was also assessed on all subjects using OCT. Receiver operating characteristic (ROC) analysis and Spearman's correlation coefficient was carried out. Results: FA and MD values in the optic nerve and optic radiation decreased and increased respectively as the disease progressed. FA at the optic nerve had the highest sensitivity (87%) and specificity (80%). FA values displayed the strongest correlation with RNFL thickness in the optic nerve (r = 0.684, p ≤ 0.001) while MD at the optic radiation showed the weakest correlation with RNFL thickness (r = −0.360, p ≤ 0.001). Conclusions: The high sensitivity and specificity of DTI-derived FA values in the optic nerve and the strong correlation between DTI-FA and RNFL thickness suggest that these parameters could serve as indicators of disease severity.

  20. A Study of Radiative Bottomonium Transitions using Converted Photons

    Energy Technology Data Exchange (ETDEWEB)

    Lees, J.P.; Poireau, V.; Prencipe, E.; Tisserand, V.; /Annecy, LAPP; Garra Tico, J.; Grauges, E.; /Barcelona U., ECM; Martinelli, M.; /INFN, Bari /Bari U.; Milanes, D.A.; /INFN, Bari; Palano, A.; Pappagallo, M.; /INFN, Bari /Bari U.; Eigen, G.; Stugu, B.; Sun, L.; /Bergen U.; Brown, D.N.; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G.; /UC, Berkeley; Koch, H.; Schroeder, T.; /Ruhr U., Bochum; Asgeirsson, D.J.; Hearty, C.; /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UC, Riverside /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /INFN, Ferrara /Frascati /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /Indian Inst. Tech., Guwahati /Harvard U. /Harvey Mudd Coll. /Heidelberg U. /Humboldt U., Berlin /Imperial Coll., London /Iowa State U. /Iowa State U. /Johns Hopkins U. /Paris U., VI-VII /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Royal Holloway, U. of London /Louisville U. /Mainz U., Inst. Kernphys. /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT /McGill U. /INFN, Milan /Milan U. /INFN, Milan /INFN, Milan /Milan U. /Mississippi U. /Montreal U. /INFN, Naples /Naples U. /NIKHEF, Amsterdam /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /INFN, Padua /INFN, Padua /Padua U. /Paris U., VI-VII /INFN, Perugia /Perugia U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa, Scuola Normale Superiore /INFN, Pisa /Pisa U. /INFN, Pisa /INFN, Pisa /Pisa U. /INFN, Pisa /Princeton U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /Rostock U. /Rutherford /DAPNIA, Saclay /SLAC /South Carolina U. /Southern Methodist U. /Stanford U., Phys. Dept. /SUNY, Albany /Tel Aviv U. /Tennessee U. /Texas Nuclear Corp., Austin /Texas U., Dallas /INFN, Turin /Turin U. /INFN, Trieste /Trieste U. /Valencia U. /Victoria U. /Warwick U. /Wisconsin U., Madison

    2011-08-15

    The authors use (111 {+-} 1) million {Upsilon}(3S) and (89 {+-} 1) million {Upsilon}(2S) events recorded by the BABAR detector at the PEP-II B-factory at SLAC to perform a study of radiative transitions betwen bottomonium states using photons that have been converted to e{sup +}e{sup -} pairs by the detector material. They observe {Upsilon}(3S) {yields} {gamma}{chi}{sub b0,2}(1P) decay, make precise measurements of the branching fractions for {chi}{sub b1,2}(1P, 2P) {yields} {gamma}{Upsilon}(1S) and {chi}{sub b1,2}(2P) {yields} {gamma}{Upsilon}(2S) decays, and search for radiative decay to the {eta}{sub b}(1S) and {eta}{sub b}(2S) states.

  1. Black-body radiation shift of the Ga$^{+}$ clock transition

    CERN Document Server

    Cheng, Yongjun

    2013-01-01

    The blackbody radiation shift of the Ga$^+$ $4s^2 \\ ^1S^e_0 \\to 4s4p \\ ^3P^o_0$ clock transition is computed to be $-$$0.0140 \\pm 0.0048$ Hz at 300 K. The small shift is consistent with the blackbody shifts of the clock transitions of other group III ions which are of a similar size. The polarizabilities of the Ga$^+$ $4s^2 \\ ^1S^e_0$, $4s4p \\ ^3P^o_0$, and $4s4p \\ ^1P^o_1$ states were computed using the configuration interaction method with an underlying semi-empirical core potential. A byproduct of the analysis involved large scale calculations of the low lying spectrum and oscillator strengths of the Ga$^{2+}$ ion.

  2. Glass transition near the free surface studied by synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Sikorski, M.

    2008-06-15

    A comprehensive picture of the glass transition near the liquid/vapor interface of the model organic glass former dibutyl phthalate is presented in this work. Several surface-sensitive techniques using x-ray synchrotron radiation were applied to investigate the static and dynamic aspects of the formation of the glassy state from the supercooled liquid. The amorphous nature of dibutyl phthalate close to the free surface was confirmed by grazing incidence X-ray diffraction studies. Results from X-ray reflectivity measurements indicate a uniform electron density distribution close to the interface excluding the possibility of surface freezing down to 175 K. Dynamics on sub-{mu}m length-scales at the surface was studied with coherent synchrotron radiation via x-ray photon correlation spectroscopy. From the analysis of the dispersion relation of the surface modes, viscoelastic properties of the dibutyl phthalate are deduced. The Kelvin-Voigt model of viscoelastic media was found to describe well the properties of the liquid/vapor interface below room temperature. The data show that the viscosity at the interface matches the values reported for bulk dibutyl phthalate. The scaled relaxation rate at the surface agrees with the bulk data above 210 K. Upon approaching the glass transition temperature the free surface was observed to relax considerably faster close to the liquid/vapor interface than in bulk. The concept of higher relaxation rate at the free surface is also supported by the results of the quasielastic nuclear forward scattering experiment, during which dynamics on molecular length scales around the calorimetric glass transition temperature is studied. The data were analyzed using mode-coupling theory of the glass transition and the model of the liquid(glass)/vapor interface, predicting inhomogeneous dynamics near the surface. The quasielastic nuclear forward scattering data can be explained when the molecular mobility is assumed to decrease with the increasing

  3. Radiation engineering of optical antennas for maximum field enhancement.

    Science.gov (United States)

    Seok, Tae Joon; Jamshidi, Arash; Kim, Myungki; Dhuey, Scott; Lakhani, Amit; Choo, Hyuck; Schuck, Peter James; Cabrini, Stefano; Schwartzberg, Adam M; Bokor, Jeffrey; Yablonovitch, Eli; Wu, Ming C

    2011-07-13

    Optical antennas have generated much interest in recent years due to their ability to focus optical energy beyond the diffraction limit, benefiting a broad range of applications such as sensitive photodetection, magnetic storage, and surface-enhanced Raman spectroscopy. To achieve the maximum field enhancement for an optical antenna, parameters such as the antenna dimensions, loading conditions, and coupling efficiency have been previously studied. Here, we present a framework, based on coupled-mode theory, to achieve maximum field enhancement in optical antennas through optimization of optical antennas' radiation characteristics. We demonstrate that the optimum condition is achieved when the radiation quality factor (Q(rad)) of optical antennas is matched to their absorption quality factor (Q(abs)). We achieve this condition experimentally by fabricating the optical antennas on a dielectric (SiO(2)) coated ground plane (metal substrate) and controlling the antenna radiation through optimizing the dielectric thickness. The dielectric thickness at which the matching condition occurs is approximately half of the quarter-wavelength thickness, typically used to achieve constructive interference, and leads to ∼20% higher field enhancement relative to a quarter-wavelength thick dielectric layer.

  4. Ultrafast Radiation Detection by Modulation of an Optical Probe Beam

    Energy Technology Data Exchange (ETDEWEB)

    Vernon, S P; Lowry, M E

    2006-02-22

    We describe a new class of radiation sensor that utilizes optical interferometry to measure radiation-induced changes in the optical refractive index of a semiconductor sensor medium. Radiation absorption in the sensor material produces a transient, non-equilibrium, electron-hole pair distribution that locally modifies the complex, optical refractive index of the sensor medium. Changes in the real (imaginary) part of the local refractive index produce a differential phase shift (absorption) of an optical probe used to interrogate the sensor material. In contrast to conventional radiation detectors where signal levels are proportional to the incident energy, signal levels in these optical sensors are proportional to the incident radiation energy flux. This allows for reduction of the sensor form factor with no degradation in detection sensitivity. Furthermore, since the radiation induced, non-equilibrium electron-hole pair distribution is effectively measured ''in place'' there is no requirement to spatially separate and collect the generated charges; consequently, the sensor risetime is of the order of the hot-electron thermalization time {le} 10 fs and the duration of the index perturbation is determined by the carrier recombination time which is of order {approx} 600 fs in, direct-bandgap semiconductors, with a high density of recombination defects; consequently, the optical sensors can be engineered with sub-ps temporal response. A series of detectors were designed, and incorporated into Mach Zehnder and Fabry-Perot interferometer-based detection systems: proof of concept, lower detection sensitivity, Mach-Zehnder detectors were characterized at beamline 6.3 at SSRL; three generations of high sensitivity single element and imaging Fabry-Perot detectors were measured at the LLNL Europa facility. Our results indicate that this technology can be used to provide x-ray detectors and x-ray imaging systems with single x-ray sensitivity and S

  5. Radiation effects on rare-earth doped optical fibers

    Energy Technology Data Exchange (ETDEWEB)

    Girard, S.; Marcandella, C. [CEA Bruyeres-le-Chatel, DIF 91 (France); Ouerdane, Y.; Tortech, B.; Boukenter, A.; Meunier, J.P.; Vivona, M. [Lab. Hubert Curien, CNRS, 42 - Saint-Etienne (France); Vivona, M.; Robin, Th.; Cadier, B. [iXFiber SAS, 22 - lannion (France)

    2010-07-01

    In this paper, we reviewed our previous work concerning the responses of rare-earth (RE) doped fibers (Yb, Er and Er/Yb) to various types of radiations like gamma-rays, X-rays and protons. For all these harsh environments, the main measured macroscopic radiation-induced effect is an increase of the linear attenuation of these waveguides due to the generation of point defects in the RE-doped core and silica-based cladding. To evaluate the vulnerability of this class of optical fibers for space missions, we characterize the growth and decay kinetics of their radiation-induced attenuation (RIA) during and after irradiation for various compositions. Laboratory testing reveals that this class of optical fibers is very sensitive to radiations compared to passive (RE-free) samples. As a consequence, despite the small length used for space applications, the understanding of the radiation-induced effects in this class of optical fibers becomes necessary before their integration as part of fiber-based systems like gyroscopes or communication systems. In this paper, we more particularly discussed about the relative influence of the rare-earth ions (Er{sup 3+} and/or Yb{sup 3+}) and of the glass matrix dopants (Al, P, ... ) on the optical degradation due to radiations. This has been done by using a set of five prototype optical fibers designed by the fiber manufacturer iXFiber SAS to enlighten the role of these parameters. Additional spectroscopic tools like con-focal microscopy of luminescence are also used to detect possible changes in the spectroscopy of the rare-earth ions and their consequences on the functionality of the active optical fibers. (authors)

  6. Optics-less Sensors for Localization of Radiation Sources

    OpenAIRE

    Caulfield, H. J.; Yaroslavsky, L. P.; Goerzen, Ch.; Umansky, S.

    2008-01-01

    A new family of radiation sensors is introduced which do not require any optics. The sensors consist of arrays of elementary sub-sensors with natural cosine-law or similar angular sensitivity supplemented with a signal processing unit that computes optimal statistical estimations of source parameters. We show, both theoretically and by computer simulation, that such sensors are capable of accurate localization and intensity estimation of a given number of radiation sources and of imaging of a...

  7. Stimulation of the human auditory nerve with optical radiation

    Science.gov (United States)

    Fishman, Andrew; Winkler, Piotr; Mierzwinski, Jozef; Beuth, Wojciech; Izzo Matic, Agnella; Siedlecki, Zygmunt; Teudt, Ingo; Maier, Hannes; Richter, Claus-Peter

    2009-02-01

    A novel, spatially selective method to stimulate cranial nerves has been proposed: contact free stimulation with optical radiation. The radiation source is an infrared pulsed laser. The Case Report is the first report ever that shows that optical stimulation of the auditory nerve is possible in the human. The ethical approach to conduct any measurements or tests in humans requires efficacy and safety studies in animals, which have been conducted in gerbils. This report represents the first step in a translational research project to initiate a paradigm shift in neural interfaces. A patient was selected who required surgical removal of a large meningioma angiomatum WHO I by a planned transcochlear approach. Prior to cochlear ablation by drilling and subsequent tumor resection, the cochlear nerve was stimulated with a pulsed infrared laser at low radiation energies. Stimulation with optical radiation evoked compound action potentials from the human auditory nerve. Stimulation of the auditory nerve with infrared laser pulses is possible in the human inner ear. The finding is an important step for translating results from animal experiments to human and furthers the development of a novel interface that uses optical radiation to stimulate neurons. Additional measurements are required to optimize the stimulation parameters.

  8. System for recording bivariate intensity distribution of optical radiation

    Energy Technology Data Exchange (ETDEWEB)

    Vil' danov, R.R.; Deryugin, I.A.; Gladyshev, D.A.; Mirzaeu, A.T.

    1986-02-01

    This paper describes a system for recording the space-energy characteristics of optical radiation based on an MF-6 photodetector matrix and an AI-4096-3M multivariate pulse analyzer. The system can record optical images with from 2 to 64 quantization levels with visual monitoring of input data in the form of a space distribution in axonometric projection. The recording time for a complete image is from 11 to 700 msec. The system has been used to determine and monitor the crosssectional intensity distribution of laser beams as a function of radiation mode.

  9. Radiation-induced optic neuropathy: A magnetic resonance imaging study

    Energy Technology Data Exchange (ETDEWEB)

    Guy, J.; Mancuso, A.; Beck, R.; Moster, M.L.; Sedwick, L.A.; Quisling, R.G.; Rhoton, A.L. Jr.; Protzko, E.E.; Schiffman, J. (Univ. of Florida, Gainesville (USA))

    1991-03-01

    Optic neuropathy induced by radiation is an infrequent cause of delayed visual loss that may at times be difficult to differentiate from compression of the visual pathways by recurrent neoplasm. The authors describe six patients with this disorder who experienced loss of vision 6 to 36 months after neurological surgery and radiation therapy. Of the six patients in the series, two had a pituitary adenoma and one each had a metastatic melanoma, multiple myeloma, craniopharyngioma, and lymphoepithelioma. Visual acuity in the affected eyes ranged from 20/25 to no light perception. Magnetic resonance (MR) imaging showed sellar and parasellar recurrence of both pituitary adenomas, but the intrinsic lesions of the optic nerves and optic chiasm induced by radiation were enhanced after gadolinium-diethylenetriaminepenta-acetic acid (DTPA) administration and were clearly distinguishable from the suprasellar compression of tumor. Repeated MR imaging showed spontaneous resolution of gadolinium-DTPA enhancement of the optic nerve in a patient who was initially suspected of harboring recurrence of a metastatic malignant melanoma as the cause of visual loss. The authors found the presumptive diagnosis of radiation-induced optic neuropathy facilitated by MR imaging with gadolinium-DTPA. This neuro-imaging procedure may help avert exploratory surgery in some patients with recurrent neoplasm in whom the etiology of visual loss is uncertain.

  10. Optical limiting of layered transition metal dichalcogenide semiconductors

    CERN Document Server

    Dong, Ningning; Feng, Yanyan; Zhang, Saifeng; Zhang, Xiaoyan; Chang, Chunxia; Fan, Jintai; Zhang, Long; Wang, Jun

    2015-01-01

    Nonlinear optical property of transition metal dichalcogenide (TMDC) nanosheet dispersions, including MoS2, MoSe2, WS2, and WSe2, was performed by using Z-scan technique with ns pulsed laser at 1064 nm and 532 nm. The results demonstrate that the TMDC dispersions exhibit significant optical limiting response at 1064 nm due to nonlinear scattering, in contrast to the combined effect of both saturable absorption and nonlinear scattering at 532 nm. Selenium compounds show better optical limiting performance than that of the sulfides in the near infrared. A liquid dispersion system based theoretical modelling is proposed to estimate the number density of the nanosheet dispersions, the relationship between incident laser fluence and the size of the laser generated micro-bubbles, and hence the Mie scattering-induced broadband optical limiting behavior in the TMDC dispersions.

  11. Heavy irradiation effects in radiation-resistant optical fibers

    Energy Technology Data Exchange (ETDEWEB)

    Shikama, Tatsuo [Tohoku Univ., Oarai, Ibaraki (Japan). Oarai Branch, Inst. for Materials Research

    1998-07-01

    Development of a system for optical measurements in a nuclear reactor has been progressing to investigate dynamic changes in a material caused by heavy irradiation. In such system, transfer of optical signals to out-pile measuring systems is being attempted by the use of optical fibers. In this report, the characteristics of optical fibers in the heavy irradiation field were summarized. It has been known that amorphous silica might produce radiolysis and structural defects by the exposure to ionizing radiation. The effects of heavy irradiation on molten silica were extremely complicated. A large intensity of visible light absorption occurred from an early time during start-up of the reactor. The absorption range was limited below 700 nm for the radiation associating fast neutron and the absorption was mostly attributed to non-bridging oxygen hole center. The depletion of optical transferring capacity under the radiation might be related to the internal stress. Therefore, it seems desirable to use optical fibers in the conditions without leading too much stress. (M.N.)

  12. Thermal radiation from optically driven Kerr (χ{sup (3)}) photonic cavities

    Energy Technology Data Exchange (ETDEWEB)

    Khandekar, Chinmay; Rodriguez, Alejandro W. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08540 (United States); Lin, Zin [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02139 (United States)

    2015-04-13

    We describe thermal radiation from nonlinear (χ{sup (3)}) photonic cavities coupled to external channels and subject to incident monochromatic light. Our work extends related work on nonlinear mechanical oscillators to the problem of thermal radiation, demonstrating that bistability can enhance thermal radiation by orders of magnitude and result in strong lineshape alternations, including “super-narrow spectral peaks” occurring at the onset of kinetic phase transitions. We show that when the cavities are designed to exhibit perfect linear emissivity (rate matching), such thermally activated transitions can be exploited to dramatically tune the output power and radiative properties of the cavity, leading to a kind of Kerr-mediated thermo-optic effect. Finally, we demonstrate that in certain parameter regimes, the output radiation exhibits Stokes and anti-Stokes side peaks whose relative magnitudes can be altered by tuning the internal temperature of the cavity relative to its surroundings, a consequence of strong correlations and interference between the emitted and reflected radiation.

  13. Optical systems for synchrotron radiation. Lecture 2. Mirror systems

    Energy Technology Data Exchange (ETDEWEB)

    Howells, M.R.

    1986-02-01

    The process of reflection of VUV and x-radiation is summarized. The functions of mirrors in synchrotron beamlines are described, which include deflection, filtration, power absorption, formation of a real image, focusing, and collimation. Fabrication of optical surfaces for synchrotron radiation beamlines are described, and include polishing of a near spherical surface as well as bending a cylindrical surface to toroidal shape. The imperfections present in mirrors, aberrations and surface figure inaccuracy, are discussed. Calculation of the thermal load of a mirror in a synchrotron radiation beam and the cooling of the mirror are covered briefly. 50 refs., 7 figs. (LEW)

  14. Supported transition metal nanomaterials: Nanocomposites synthesized by ionizing radiation

    Science.gov (United States)

    Clifford, D. M.; Castano, C. E.; Rojas, J. V.

    2017-03-01

    Nanostructures decorated with transition metal nanoparticles using ionizing radiation as a synthesis method in aqueous solutions represents a clean alternative to existing physical, chemical and physicochemical methods. Gamma irradiation of aqueous solutions generates free radicals, both oxidizing and reducing species, all distributed homogeneously. The presence of oxidant scavengers in situ during irradiation generates a highly reductive environment favoring the reduction of the metal precursors promoting seed formation and nanoparticle growth. Particle growth is controlled by addition of surfactants, polymers or various substrates, otherwise referred to as supports, which enhance the formation of well dispersed nanoparticles. Furthermore, the combination of nanoparticles with supports can offer desirable synergisms not solely presented by the substrate or nanoparticles. Thus, supported nanoparticles offer a huge diversity of applications. Among the ionizing radiation methods to synthesize nanomaterials and modify their characteristics, gamma irradiation is of growing interest and it has shown tremendous potential in morphological control and distribution of particle size by judiciously varying parameters including absorbed dose, dose rate, concentration of metal precursor, and stabilizing agents. In this work, major advances on the synthesis of supported nanoparticles through gamma irradiation are reviewed as well as the opportunities to develop and exploit new composites using gamma-rays and other accessible ionizing radiation sources such as X-rays.

  15. Spectroscopy of intraband optical transitions in anisotropic semiconductor nanocrystals

    Science.gov (United States)

    Turkov, Vadim K.; Baimuratov, Anvar S.; Rukhlenko, Ivan D.; Baranov, Alexander V.; Fedorov, Anatoly V.

    2013-09-01

    We propose a new type of optical spectroscopy of anisotropic semiconductor nanocrystals, which is based on the welldeveloped stationary pump-probe technique, where the pump and probe fields are absorbed upon, respectively, interband and intraband transitions of the nanocrystals' electronic subsystem. We develop a general theory of intraband absorption based on the density matrix formalism. This theory can be applied to study degenerate eigenstates of electrons in semiconductor nanocrystals of different shapes and dimentions. We demonstrate that the angular dependence of intraband absorption by nonspherical nanocrystals enables investigating their shape and orientation, as well as the symmetry of quantum states excited by the probe field and selection rules of electronic transitions.

  16. Radiation-hard/high-speed parallel optical links

    Energy Technology Data Exchange (ETDEWEB)

    Gan, K.K., E-mail: gan@mps.ohio-state.edu [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); Buchholz, P.; Heidbrink, S. [Fachbereich Physik, Universität Siegen, Siegen (Germany); Kagan, H.P.; Kass, R.D.; Moore, J.; Smith, D.S. [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); Vogt, M.; Ziolkowski, M. [Fachbereich Physik, Universität Siegen, Siegen (Germany)

    2016-09-21

    We have designed and fabricated a compact parallel optical engine for transmitting data at 5 Gb/s. The device consists of a 4-channel ASIC driving a VCSEL (Vertical Cavity Surface Emitting Laser) array in an optical package. The ASIC is designed using only core transistors in a 65 nm CMOS process to enhance the radiation-hardness. The ASIC contains an 8-bit DAC to control the bias and modulation currents of the individual channels in the VCSEL array. The performance of the optical engine up at 5 Gb/s is satisfactory.

  17. Radiation-hard/high-speed parallel optical links

    Science.gov (United States)

    Gan, K. K.; Buchholz, P.; Heidbrink, S.; Kagan, H. P.; Kass, R. D.; Moore, J.; Smith, D. S.; Vogt, M.; Ziolkowski, M.

    2016-09-01

    We have designed and fabricated a compact parallel optical engine for transmitting data at 5 Gb/s. The device consists of a 4-channel ASIC driving a VCSEL (Vertical Cavity Surface Emitting Laser) array in an optical package. The ASIC is designed using only core transistors in a 65 nm CMOS process to enhance the radiation-hardness. The ASIC contains an 8-bit DAC to control the bias and modulation currents of the individual channels in the VCSEL array. The performance of the optical engine up at 5 Gb/s is satisfactory.

  18. Simulation of transition radiation and electron identification ability of the ATLAS TRT

    DEFF Research Database (Denmark)

    Klinkby, Esben Bryndt

    2013-01-01

    The Transition Radiation Tracker (TRT) is the outer most tracking detector of the ATLAS experiment. In addition as functioning as atracking detector, it is capable of providing particle identification information through the emission and subsequent absorption and detection of transition radiation....... Below the effort of simulating transition radiation production and detector response is discussed, with emphasis on the data/simulation agreement and tuning. © 2012 CERN. Published by Elsevier B.V. All rights reserved....

  19. Transient optical gratings for pulsed ionizing radiation studies

    CERN Document Server

    Fullagar, Wilfred K; Hall, Chris J

    2011-01-01

    Prior to the invention of holography or lasers, Bragg's X-ray microscope opened the door to optical computation in short-wavelength studies using spatially coherent visible light, including phase retrieval methods. This optical approach lost ground to semiconductor detection and digital computing in the 1960s. Since then, visible optics including spatial light modulators (SLMs), array detectors and femtosecond lasers have become widely available, routinely allowing versatile and computer-interfaced imposition of optical phase, molecular coherent control, and detection. Today, high brilliance X-ray sources begin to offer opportunities for atomic resolution and ultrafast pump-probe studies. Correspondingly, this work considers an overlooked aspect of Bragg's X-ray microscope - the incoherent ionizing radiation to coherent visible (IICV) conversion that is a necessary prerequisite for coherent optical computations. Technologies are suggested that can accomplish this conversion. Approaches to holographic data sto...

  20. Blackbody Radiation in Optically Thick Gases?

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2014-07-01

    Full Text Available In this work, the claim that optically thick gases can emit as blackbodies is refuted. The belief that such behavior exists results from an improper consideration of heat transfer and reflection. When heat is injected into a gas, the energy is primarily redistributed into translational degrees of freedom and is not used to drive emission. The average kinetic energy of the particles in the system simply increases and the temperature rises. In this respect, it is well-know that the emissivity of a gas can drop with increasing temperature. Once reflection and translation are properly considered, it is simple to understand why gases can never emit as blackbodies.

  1. Atomic, molecular, and optical physics electromagnetic radiation

    CERN Document Server

    Dunning, F B; Lucatorto, Thomas

    1997-01-01

    Combined with Volumes 29A and 29B, this volume is a comprehensive treatment of the key experimental methods of atomic, molecular, and optical physics, as well as an excellent experimental handbook for the field. Thewide availability of tunable lasers in the past several years has revolutionized the field and lead to the introduction of many new experimental methods that are covered in these volumes. Traditional methods are also included to ensure that the volumes will be a complete reference source for the field.

  2. Interaction of pulsed CO2 laser radiation with optical materials

    Science.gov (United States)

    Schmitt, Ruediger; Hugenschmidt, Manfred; Geiss, L.; Stechele, E.

    1995-03-01

    Pulsed high power CO2-laser irradiation can cause damage to optical materials. Some results obtained at ISL with a repetitively pulsed CO2-laser with pulse energies up to 24 J are presented in this paper. In production facilities with CO2-lasers, optics transmitting in the visible spectral range like glass or PMMA are used as protection windows against scattered light. These materials have small skin depths for electromagnetic waves at 10,6 micrometers , typically in the order of some micrometers , so the interaction takes place in thin surface layers. Under high power laser radiation the transparency of the optics is lowered. On the other hand infrared transmitting optics like KCl or ZnSe show a low intrinsic absorption for CO2-laser radiation. Theoretical estimations matching with the experimental observations showed, however, that strong heating occurs, if a thin layer of inhomogeneities, typically some micrometers thick, is included in the surrounding material with slightly higher absorption than the surrounding lowless material. Under these assumptions the thermally induced stress inside the materials can explain the experimentally observed mechanical damage. Besides these thermal damage effects mechanical momenta are transferred by pulsed laser radiation to the optics. Experimental results as obtained by a ballistic pendulum are reported.

  3. Older Persons’ Transitions in Care (OPTIC: a study protocol

    Directory of Open Access Journals (Sweden)

    Cummings Greta G

    2012-12-01

    Full Text Available Abstract Background Changes in health status, triggered by events such as infections, falls, and geriatric syndromes, are common among nursing home (NH residents and necessitate transitions between NHs and Emergency Departments (EDs. During transitions, residents frequently experience care that is delayed, unnecessary, not evidence-based, potentially unsafe, and fragmented. Furthermore, a high proportion of residents and their family caregivers report substantial unmet needs during transitions. This study is part of a program of research whose overall aim is to improve quality of care for frail older adults who reside in NHs. The purpose of this study is to identify successful transitions from multiple perspectives and to identify organizational and individual factors related to transition success, in order to inform improvements in care for frail elderly NH residents during transitions to and from acute care. Specific objectives are to: 1. define successful and unsuccessful elements of transitions from multiple perspectives; 2. develop and test a practical tool to assess transition success; 3. assess transition processes in a discrete set of transfers in two study sites over a one year period; 4. assess the influence of organizational factors in key practice locations, e.g., NHs, emergency medical services (EMS, and EDs, on transition success; and 5. identify opportunities for evidence-informed management and quality improvement decisions related to the management of NH – ED transitions. Methods/Design This is a mixed-methods observational study incorporating an integrated knowledge translation (IKT approach. It uses data from multiple levels (facility, care unit, individual and sources (healthcare providers, residents, health records, and administrative databases. Discussion Key to study success is operationalizing the IKT approach by using a partnership model in which the OPTIC governance structure provides for team decision-makers and

  4. Optical characterization of phase transitions in pure polymers and blends

    Energy Technology Data Exchange (ETDEWEB)

    Mannella, Gianluca A.; Brucato, Valerio; La Carrubba, Vincenzo, E-mail: vincenzo.lacarrubba@unipa.it [Department of Civil, Environmental, Aerospace and Materials Engineering (DICAM), University of Palermo, Viale delle Scienze, Ed. 8, 90128 Palermo (Italy)

    2015-12-17

    To study the optical properties of polymeric samples, an experimental apparatus was designed on purpose and set up. The sample is a thin film enclosed between two glass slides and a PTFE frame, with a very thin thermocouple placed on sample for direct temperature measurement. This sample holder was placed between two aluminum slabs, equipped with a narrow slit for optical measurements and with electrical resistances for temperature control. Sample was enlightened by a laser diode, whereas transmitted light was detected with a photodiode. Measurements were carried out on polyethylene-terephtalate (PET) and two different polyamides, tested as pure polymers and blends. The thermal history imposed to the sample consisted in a rapid heating from ambient temperature to a certain temperature below the melting point, a stabilization period, and then a heating at constant rate. After a second stabilization period, the sample was cooled. The data obtained were compared with DSC measurements performed with the same thermal history. In correspondence with transitions detected via DSC (e.g. melting, crystallization and cold crystallization), the optical signal showed a steep variation. In particular, crystallization resulted in a rapid decrease of transmitted light, whereas melting gave up an increase of light transmitted by the sample. Further variations in transmitted light were recorded for blends, after melting: those results may be related to other phase transitions, e.g. liquid-liquid phase separation. All things considered, the apparatus can be used to get reliable data on phase transitions in polymeric systems.

  5. Optical Sensor for Characterizing the Phase Transition in Salted Solutions

    Science.gov (United States)

    Claverie, Rémy; Fontana, Marc D.; Duričković, Ivana; Bourson, Patrice; Marchetti, Mario; Chassot, Jean-Marie

    2010-01-01

    We propose a new optical sensor to characterize the solid-liquid phase transition in salted solutions. The probe mainly consists of a Raman spectrometer that extracts the vibrational properties from the light scattered by the salty medium. The spectrum of the O – H stretching band was shown to be strongly affected by the introduction of NaCl and the temperature change as well. A parameter SD defined as the ratio of the integrated intensities of two parts of this band allows to study the temperature and concentration dependences of the phase transition. Then, an easy and efficient signal processing and the exploitation of a modified Boltzmann equation give information on the phase transition. Validations were done on solutions with varying concentration of NaCl. PMID:22319327

  6. Aging studies for the ATLAS Transition Radiation Tracker (TRT)

    CERN Document Server

    Åkesson, T; Bondarenko, V; Capéans-Garrido, M; Catinaccio, A; Cwetanski, Peter; Danielsson, H; Dittus, F; Dolgoshein, B A; Dressnandt, N; Ebenstein, W L; Eerola, Paule Anna Mari; Farthouat, Philippe; Fedin, O; Froidevaux, D; Gavrilenko, I; Grichkevitch, Y; Gagnon, P; Hajduk, Z; Keener, P T; Kekelidze, G D; Konovalov, S; Kowalski, T; Kramarenko, V A; Laritchev, A; Lichard, P; Lundberg, B; Luehring, F C; Markina, I; Manara, A; McFarlane, K; Mitsou, V; Muraviev, S; Newcomer, F M; Ogren, H; Oh, S H; Olszowska, J; Peshekhonov, V D; Rembser, C; Romaniouk, A; Rhone, O; Rust, D R; Shchegelskii, V; Shmeleva, A; Smirnov, S; Smirnova, L N; Sosnovtsev, V V; Sutchkov, S; Tartarelli, F; Tikhomirov, V; Van Berg, R; Vassilieva, L; Wang, C; Williams, H H

    2003-01-01

    A summary of the aging and material validation studies carried out for the ATLAS Transition Radiation Tracker (TRT) is presented. Particular emphasis is put on the different phenomena observed in straw tubes operating with the chosen Xe/CF//4/CO//2 mixture. The most serious effects observed are silicon deposition on the anode wire and damage of the anode wire gold plating. Etching phenomena and active radical effects are also discussed. With a careful choice of all materials and components, and with good control of the water contamination in the active gas, the ATLAS TRT will operate reliably for 10 years at the LHC design luminosity. To demonstrate this fully, more work is still needed on the gas system purification elements, in particular to understand their interplay with the active species containing fluorine created in the avalanche process under irradiation.

  7. The ALICE Transition Radiation Detector: construction, operation, and performance

    CERN Document Server

    Acharya, Shreyasi; The ALICE collaboration; Adamova, Dagmar; Adler, Clemens; Adolfsson, Jonatan; Aggarwal, Madan Mohan; Aglieri Rinella, Gianluca; Agnello, Michelangelo; Agrawal, Neelima; Ahammed, Zubayer; Ahmad, Nazeer; Ahn, Sang Un; Aiola, Salvatore; Akindinov, Alexander; Al-turany, Mohammad; Alam, Sk Noor; Antonczyk, Dariusz; Arend, Andreas; Bazo Alba, Jose Luis; Silva De Albuquerque, Danilo; Aleksandrov, Dmitry; Alessandro, Bruno; Alfaro Molina, Jose Ruben; Alici, Andrea; Alkin, Anton; Alme, Johan; Alt, Torsten; Altenkamper, Lucas; Altsybeev, Igor; Alves Garcia Prado, Caio; Andrei, Cristian; Andreou, Dimitra; Andrews, Harry Arthur; Andronic, Anton; Anguelov, Venelin; Anson, Christopher Daniel; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Anwar, Rafay; Aphecetche, Laurent Bernard; Appelshaeuser, Harald; Arcelli, Silvia; Arnaldi, Roberta; Arnold, Oliver Werner; Arsene, Ionut Cristian; Arslandok, Mesut; Audurier, Benjamin; Augustinus, Andre; Averbeck, Ralf Peter; Azmi, Mohd Danish; Badala, Angela; Baek, Yong Wook; Bagnasco, Stefano; Bailhache, Raphaelle Marie; Bala, Renu; Baldisseri, Alberto; Ball, Markus; Baral, Rama Chandra; Barbano, Anastasia Maria; Barbera, Roberto; Barile, Francesco; Barioglio, Luca; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Ramillien Barret, Valerie; Bartalini, Paolo; Barth, Klaus; Bartos, D; Bartsch, Esther; Basile, Maurizio; Bastid, Nicole; Basu, Sumit; Bathen, Bastian; Batigne, Guillaume; Batyunya, Boris; Batzing, Paul Christoph; Baumann, Christoph; Bearden, Ian Gardner; Beck, Hans; Bedda, Cristina; Behera, Nirbhay Kumar; Belikov, Iouri; Bellini, Francesca; Bello Martinez, Hector; Bellwied, Rene; Espinoza Beltran, Lucina Gabriela; Belyaev, Vladimir; Bencedi, Gyula; Beole, Stefania; Berceanu, I; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Bertens, Redmer Alexander; Berzano, Dario; Betev, Latchezar; Bhasin, Anju; Bhat, Inayat Rasool; Bhati, Ashok Kumar; Bhattacharjee, Buddhadeb; Bhom, Jihyun; Bianchi, Antonio; Bianchi, Livio; Bianchi, Nicola; Bianchin, Chiara; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Biro, Gabor; Biswas, Rathijit; Biswas, Saikat; Blair, Justin Thomas; Blau, Dmitry; Blume, Christoph; Boca, Gianluigi; Bock, Friederike; Bogdanov, Alexey; Boldizsar, Laszlo; Bombara, Marek; Bonomi, Germano; Bonora, Matthias; Book, Julian Heinz; Borel, Herve; Borissov, Alexander; Borri, Marcello; Botta, Elena; Bourjau, Christian; Bratrud, Lars; Braun-munzinger, Peter; Bregant, Marco; Broker, Theo Alexander; Broz, Michal; Brucken, Erik Jens; Bruna, Elena; Bruno, Giuseppe Eugenio; Bucher, Damian; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Buhler, Paul; Buncic, Predrag; Busch, Oliver; Buthelezi, Edith Zinhle; Bashir Butt, Jamila; Buxton, Jesse Thomas; Cabala, Jan; Caffarri, Davide; Caines, Helen Louise; Caliva, Alberto; Calvo Villar, Ernesto; Camerini, Paolo; Capon, Aaron Allan; Caragheorgheopol, G; Carena, Francesco; Carena, Wisla; Carnesecchi, Francesca; Castillo Castellanos, Javier Ernesto; Castro, Andrew John; Casula, Ester Anna Rita; Catanescu, V; Ceballos Sanchez, Cesar; Cerello, Piergiorgio; Chandra, Sinjini; Chang, Beomsu; Chapeland, Sylvain; Chartier, Marielle; Chattopadhyay, Subhasis; Chattopadhyay, Sukalyan; Chauvin, Alex; Chernenko, S; Cherney, Michael Gerard; Cheshkov, Cvetan Valeriev; Cheynis, Brigitte; Chibante Barroso, Vasco Miguel; Dobrigkeit Chinellato, David; Cho, Soyeon; Chochula, Peter; Chojnacki, Marek; Choudhury, Subikash; Chowdhury, Tasnuva; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Ciobanu, M; Cleymans, Jean Willy Andre; Colamaria, Fabio Filippo; Colella, Domenico; Collu, Alberto; Colocci, Manuel; Concas, Matteo; Conesa Balbastre, Gustavo; Conesa Del Valle, Zaida; Connors, Megan Elizabeth; Contreras Nuno, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortes Maldonado, Ismael; Cortese, Pietro; Cosentino, Mauro Rogerio; Costa, Filippo; Costanza, Susanna; Crkovska, Jana; Crochet, Philippe; Cuautle Flores, Eleazar; Cunqueiro Mendez, Leticia; Dahms, Torsten; Dainese, Andrea; Danisch, Meike Charlotte; Danu, Andrea; Das, Debasish; Das, Indranil; Das, Supriya; Dash, Ajay Kumar; Dash, Sadhana; Daues, Heinz; De, Sudipan; De Caro, Annalisa; De Cataldo, Giacinto; De Conti, Camila; de Cuveland, J; De Falco, Alessandro; De Gruttola, Daniele; De Marco, Nora; De Pasquale, Salvatore; Derradi De Souza, Rafael; Franz Degenhardt, Hermann; Deisting, Alexander; Deloff, Andrzej; Deplano, Caterina; Devismes, A; Dhankher, Preeti; Di Bari, Domenico; Di Mauro, Antonio; Di Nezza, Pasquale; Di Ruzza, Benedetto; Dietel, Thomas; Dillenseger, Pascal; Divia, Roberto; Djuvsland, Oeystein; Dobrin, Alexandru Florin; Domenicis Gimenez, Diogenes; Donigus, Benjamin; Dordic, Olja; Van Doremalen, Lennart Vincent; Dubey, Anand Kumar; Dubla, Andrea; Ducroux, Laurent; Duggal, Ashpreet Kaur; Dupieux, Pascal; Duta, V; Ehlers Iii, Raymond James; Elia, Domenico; Emschermann, David; Endress, Eric; Engel, Heiko; Epple, Eliane; Erazmus, Barbara Ewa; Erhardt, Filip; Espagnon, Bruno; Esumi, Shinichi; Eulisse, Giulio; Eum, Jongsik; Evans, David; Evdokimov, Sergey; Fabbietti, Laura; Faivre, Julien; Fantoni, Alessandra; Fasel, Markus; Fateev, O; Feldkamp, Linus; Feliciello, Alessandro; Feofilov, Grigorii; Ferencei, Jozef; Fernandez Tellez, Arturo; Ferretti, Alessandro; Festanti, Andrea; Feuillard, Victor Jose Gaston; Figiel, Jan; Araujo Silva Figueredo, Marcel; Filchagin, Sergey; Finogeev, Dmitry; Fionda, Fiorella; Fleck, M; Floris, Michele; Foertsch, Siegfried Valentin; Foka, Panagiota; Fokin, Sergey; Fragiacomo, Enrico; Francescon, Andrea; Francisco, Audrey; Frankenfeld, Ulrich Michael; Freuen, S; Fronze, Gabriele Gaetano; Fuchs, Ulrich; Furget, Christophe; Furs, Artur; Fusco Girard, Mario; Gaardhoeje, Jens Joergen; Gagliardi, Martino; Gago Medina, Alberto Martin; Gajdosova, Katarina; Gallio, Mauro; Duarte Galvan, Carlos; Ganoti, Paraskevi; Garabatos Cuadrado, Jose; Garcia-solis, Edmundo Javier; Garg, Kunal; Gargiulo, Corrado; Gasik, Piotr Jan; Gatz, Henriette; Gauger, Erin Frances; De Leone Gay, Maria Beatriz; Germain, Marie; Ghosh, Jhuma; Ghosh, Premomoy; Ghosh, Sanjay Kumar; Gianotti, Paola; Giolu, G; Giubellino, Paolo; Giubilato, Piero; Gladysz-dziadus, Ewa; Glasow, Richard; Glassel, Peter; Gremmler, Svenja; Gomez Coral, Diego Mauricio; Gomez Ramirez, Andres; Sanchez Gonzalez, Andres; Gorbunov, Sergey; Gorlich, Lidia Maria; Gotovac, Sven; Gottschalk, Dirk; Gottschlag, Holger; Grabski, Varlen; Graczykowski, Lukasz Kamil; Graham, Katie Leanne; Grajcarek, Robert; Greiner, Leo Clifford; Grelli, Alessandro; Grigoras, Costin; Grigoryev, Vladislav; Grigoryan, Ara; Grigoryan, Smbat; Grimm, Helge; Grion, Nevio; Gronefeld, Julius Maximilian; Grosa, Fabrizio; Grosse-oetringhaus, Jan Fiete; Grosso, Raffaele; Gruber, Lukas; Guber, Fedor; Guernane, Rachid; Guerzoni, Barbara; Gulbrandsen, Kristjan Herlache; Gunji, Taku; Gupta, Anik; Gupta, Ramni; Gutfleisch, M; Bautista Guzman, Irais; Haake, Rudiger; Hadjidakis, Cynthia Marie; Hamagaki, Hideki; Hamar, Gergoe; Hamon, Julien Charles; Haque, Md Rihan; Harris, John William; Hartig, Matthias; Harton, Austin Vincent; Hassan, Hadi; Hatzifotiadou, Despina; Hayashi, Shinichi; Heckel, Stefan Thomas; Hehner, Joerg; Heide, Markus; Hellbar, Ernst; Helstrup, Haavard; Herghelegiu, Andrei Ionut; Herrera Corral, Gerardo Antonio; Herrmann, Florian; Herrmann, Norbert; Hess, Benjamin Andreas; Hetland, Kristin Fanebust; Hillemanns, Hartmut; Hills, Christopher; Hippolyte, Boris; Hladky, Jan; Hohlweger, Bernhard; Horak, David; Hornung, Sebastian; Hosokawa, Ritsuya; Hristov, Peter Zahariev; Huber, Sebastian; Hughes, Charles; Humanic, Thomas; Hussain, Nur; Hussain, Tahir; Hutter, Dirk; Hwang, Dae Sung; Iga Buitron, Sergio Arturo; Ilkaev, Radiy; Inaba, Motoi; Ippolitov, Mikhail; Irfan, Muhammad; Islam, Md Samsul; Ivanov, Marian; Ivanov, Vladimir; Izucheev, Vladimir; Jacak, Barbara; Jacazio, Nicolo; Jacobs, Peter Martin; Jadhav, Manoj Bhanudas; Jadlovsky, Jan; Jaelani, Syaefudin; Jahnke, Cristiane; Jakubowska, Monika Joanna; Janik, Malgorzata Anna; Pahula Hewage, Sandun; Jena, Chitrasen; Jena, Satyajit; Jercic, Marko; Jimenez Bustamante, Raul Tonatiuh; Jones, Peter Graham; Jusko, Anton; Kalinak, Peter; Kalweit, Alexander Philipp; Kang, Ju Hwan; Kaplin, Vladimir; Kar, Somnath; Karasu Uysal, Ayben; Karavichev, Oleg; Karavicheva, Tatiana; Karayan, Lilit; Karczmarczyk, Przemyslaw; Karpechev, Evgeny; Kebschull, Udo Wolfgang; Keidel, Ralf; Keijdener, Darius Laurens; Keil, Markus; Ketzer, Bernhard Franz; Khabanova, Zhanna; Khan, Palash; Khan, Shuaib Ahmad; Khanzadeev, Alexei; Kharlov, Yury; Khatun, Anisa; Khuntia, Arvind; Kielbowicz, Miroslaw Marek; Kileng, Bjarte; Kim, Byungchul; Kim, Daehyeok; Kim, Dong Jo; Kim, Hyeonjoong; Kim, Jinsook; Kim, Jiyoung; Kim, Minjung; Kim, Minwoo; Kim, Se Yong; Kim, Taesoo; Kirsch, Stefan; Kisel, Ivan; Kiselev, Sergey; Kisiel, Adam Ryszard; Kislov, E; Kiss, Gabor; Klay, Jennifer Lynn; Klein, Carsten; Klein, Jochen; Klein-boesing, Christian; "Klein-Boesing", Melanie; Kliemant, Michael; Klingenmeyer, Hannah; Klewin, Sebastian; Kluge, Alexander; Knichel, Michael Linus; Knospe, Anders Garritt; Kobdaj, Chinorat; Kofarago, Monika; Kohn, Martin; Kollegger, Thorsten; Kondratev, Valerii; Kondratyeva, Natalia; Kondratyuk, Evgeny; Konevskikh, Artem; Konno, Masahiro; Konyushikhin, Maxim; Kopcik, Michal; Kour, Mandeep; Kouzinopoulos, Charalampos; Kovalenko, Oleksandr; Kovalenko, Vladimir; Kowalski, Marek; Koyithatta Meethaleveedu, Greeshma; Kralik, Ivan; Kramer, Frederick; Kravcakova, Adela; Krawutschke, Tobias; Kreis, Lukas; Krivda, Marian; Krizek, Filip; Krumbhorn, Dirk; Kryshen, Evgeny; Krzewicki, Mikolaj; Kubera, Andrew Michael; Kucera, Vit; Kuhn, Christian Claude; Kuijer, Paulus Gerardus; Kumar, Ajay; Kumar, Jitendra; Kumar, Lokesh; Kumar, Shyam; Kundu, Sourav; Kurashvili, Podist; Kurepin, Alexander; Kurepin, Alexey; Kuryakin, Alexey; Kushpil, Svetlana; Kweon, Min Jung; Kwon, Youngil; La Pointe, Sarah Louise; La Rocca, Paola; Lagana Fernandes, Caio; Lai, Yue Shi; Lakomov, Igor; Langoy, Rune; Lapidus, Kirill; Lara Martinez, Camilo Ernesto; Lardeux, Antoine Xavier; Lattuca, Alessandra; Laudi, Elisa; Lavicka, Roman; Lea, Ramona; Leardini, Lucia; Lee, Seongjoo; Lehas, Fatiha; Lehmann, T; Lehner, Jorg; Lehner, Sebastian; Lehrbach, Johannes; Lemmon, Roy Crawford; Lenti, Vito; Leogrande, Emilia; Leon Monzon, Ildefonso; Lesser, F; Levai, Peter; Li, Xiaomei; Lien, Jorgen Andre; Lietava, Roman; Lim, Bong-hwi; Lindal, Svein; Lindenstruth, Volker; Lindsay, Scott William; Lippmann, Christian; Lisa, Michael Annan; Litichevskyi, Vladyslav; Llope, William; Lodato, Davide Francesco; Lohner, Daniel; Lonne, Per-ivar; Loginov, Vitaly; Loizides, Constantinos; Loncar, Petra; Lopez, Xavier Bernard; Lopez Torres, Ernesto; Lowe, Andrew John; Lu, XianGuo; Ludolphs, W; Luettig, Philipp Johannes; Luhder, Jens Robert; Lunardon, Marcello; Luparello, Grazia; Lupi, Matteo; Lutz, Tyler Harrison; Maevskaya, Alla; Mager, Magnus; Magureanu, C; Mahajan, Sanjay; Mahmoud, T; Mahmood, Sohail Musa; Maire, Antonin; Majka, Richard Daniel; Malaev, Mikhail; Malinina, Liudmila; Mal'kevich, Dmitry; Malzacher, Peter; Mamonov, Alexander; Manko, Vladislav; Manso, Franck; Manzari, Vito; Mao, Yaxian; Marchisone, Massimiliano; Mares, Jiri; Margagliotti, Giacomo Vito; Margotti, Anselmo; Margutti, Jacopo; Marin, Ana Maria; Markert, Christina; Marquard, Marco; Martin, Nicole Alice; Martinengo, Paolo; Lucio Martinez, Jose Antonio; Martinez Hernandez, Mario Ivan; Martinez-garcia, Gines; Martinez Pedreira, Miguel; Masciocchi, Silvia; Masera, Massimo; Masoni, Alberto; Masson, Erwann; Mastroserio, Annalisa; Mathis, Andreas Michael; Matyja, Adam Tomasz; Mayer, Christoph; Mazer, Joel Anthony; Mazzilli, Marianna; Mazzoni, Alessandra Maria; Meddi, Franco; Melikyan, Yuri; Menchaca-rocha, Arturo Alejandro; Meninno, Elisa; Mercado-perez, Jorge; Meres, Michal; Mhlanga, Sibaliso; Miake, Yasuo; Mieskolainen, Matti Mikael; Mihaylov, Dimitar Lubomirov; Mikhaylov, Konstantin; Milosevic, Jovan; Mischke, Andre; Mishra, Aditya Nath; Miskowiec, Dariusz Czeslaw; Mitra, Jubin; Mitu, Ciprian Mihai; Mohammadi, Naghmeh; Mohanty, Bedangadas; Khan, Mohammed Mohisin; Moreira De Godoy, Denise Aparecida; Perez Moreno, Luis Alberto; Moretto, Sandra; Morino, Yuhei; Morreale, Astrid; Morsch, Andreas; Muccifora, Valeria; Mudnic, Eugen; Muhlheim, Daniel Michael; Muhuri, Sanjib; Mukherjee, Maitreyee; Mulligan, James Declan; Gameiro Munhoz, Marcelo; Munning, Konstantin; Munzer, Robert Helmut; Murakami, Hikari; Murray, Sean; Musa, Luciano; Musinsky, Jan; Myers, Corey James; Myrcha, Julian Wojciech; Mycke, Jan Felix; Nag, Dipanjan; Naik, Bharati; Nair, Rahul; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Narayan, Amrendra; Naru, Muhammad Umair; Ferreira Natal Da Luz, Pedro Hugo; Nattrass, Christine; Rosado Navarro, Sebastian; Nayak, Kishora; Nayak, Ranjit; Nayak, Tapan Kumar; Nazarenko, Sergey; Nedosekin, Alexander; Negrao De Oliveira, Renato Aparecido; Neher, Michael; Nellen, Lukas; Nesbo, Simon Voigt; Ng, Fabian; Nicassio, Maria; Niculescu, Mihai; Niedziela, Jeremi; Nielsen, Borge Svane; Nikolaev, Sergey; Nikulin, Sergey; Nikulin, Vladimir; Noferini, Francesco; Nomokonov, Petr; Nooren, Gerardus; Cabanillas Noris, Juan Carlos; Norman, Jaime; Nyanin, Alexander; Nystrand, Joakim Ingemar; Oeschler, Helmut Oskar; Oh, Saehanseul; Ohlson, Alice Elisabeth; Okubo, Tsubasa; Olah, Laszlo; Oleniacz, Janusz; Oliveira Da Silva, Antonio Carlos; Oliver, Michael Henry; Onderwaater, Jacobus; Oppedisano, Chiara; Orava, Risto; Oravec, Matej; Ortiz Velasquez, Antonio; Oskarsson, Anders Nils Erik; Otwinowski, Jacek Tomasz; Oyama, Ken; Pachmayer, Yvonne Chiara; Pacik, Vojtech; Pagano, Davide; Pagano, Paola; Paic, Guy; Panebratsev, Yu; Palni, Prabhakar; Pan, Jinjin; Pandey, Ashutosh Kumar; Panebianco, Stefano; Papikyan, Vardanush; Pappalardo, Giuseppe; Pareek, Pooja; Park, Jonghan; Park, WooJin; Parmar, Sonia; Passfeld, Annika; Pathak, Surya Prakash; Patra, Rajendra Nath; Paul, Biswarup; Pei, Hua; Peitzmann, Thomas; Peng, Xinye; Pereira, Luis Gustavo; Pereira Da Costa, Hugo Denis Antonio; Peresunko, Dmitry Yurevich; Perez Lezama, Edgar; Peskov, Vladimir; Pestov, Yury; Petracek, Vojtech; Petris, M; Petrov, Viacheslav; Petrovici, Mihai; Petta, Catia; Peretti Pezzi, Rafael; Piano, Stefano; Pikna, Miroslav; Pillot, Philippe; Ozelin De Lima Pimentel, Lais; Pinazza, Ombretta; Pinsky, Lawrence; Pitz, Nora; Piyarathna, Danthasinghe; Ploskon, Mateusz Andrzej; Planinic, Mirko; Pliquett, Fabian; Pluta, Jan Marian; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Polishchuk, Boris; Poljak, Nikola; Poonsawat, Wanchaloem; Pop, Amalia; Poppenborg, Hendrik; Porteboeuf, Sarah Julie; Pozdniakov, Valeriy; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puccio, Maximiliano; Puddu, Giovanna; Pujahari, Prabhat Ranjan; Punin, Valery; Putschke, Jorn Henning; Radomski, Sylwester; Rachevski, Alexandre; Raha, Sibaji; Rajput, Sonia; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Rami, Fouad; Rana, Dhan Bahadur; Raniwala, Rashmi; Raniwala, Sudhir; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Rathee, Deepika; Ratza, Viktor; Ravasenga, Ivan; Read, Kenneth Francis; Redlich, Krzysztof; Rehman, Attiq Ur; Reichelt, Patrick Simon; Reidt, Felix; Reischl, A; Ren, Xiaowen; Renfordt, Rainer Arno Ernst; Reolon, Anna Rita; Reshetin, Andrey; Reygers, Klaus Johannes; Riabov, Viktor; Ricci, Renato Angelo; Richert, Tuva Ora Herenui; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Ristea, Catalin-lucian; Rodriguez Cahuantzi, Mario; Roeed, Ketil; Rogochaya, Elena; Rohr, David Michael; Roehrich, Dieter; Rokita, Przemyslaw Stefan; Ronchetti, Federico; Dominguez Rosas, Edgar; Rosnet, Philippe; Rossi, Andrea; Rotondi, Alberto; Roukoutakis, Filimon; Roy, Ankhi; Roy, Christelle Sophie; Roy, Pradip Kumar; Vazquez Rueda, Omar; Rui, Rinaldo; Rumyantsev, Boris; Rusanov, Ivan; Rustamov, Anar; Ryabinkin, Evgeny; Ryabov, Yury; Rybicki, Andrzej; Saarinen, Sampo; Sadhu, Samrangy; Sadovskiy, Sergey; Safarik, Karel; Saha, Sumit Kumar; Sahlmuller, Baldo; Sahoo, Baidyanath; Sahoo, Pragati; Sahoo, Raghunath; Sahoo, Sarita; Sahu, Pradip Kumar; Saini, Jogender; Sakai, Shingo; Sakata, Dousatsu; Saleh, Mohammad Ahmad; Salzwedel, Jai Samuel Nielsen; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sandoval, Andres; Sann, H; Sano, Masato; Santo, Rainer; Sarkar, Debojit; Sarkar, Nachiketa; Sarma, Pranjal; Sas, Mike Henry Petrus; Scapparone, Eugenio; Scarlassara, Fernando; Schaefer, Brennan; Scharenberg, Rolf Paul; Scheid, Horst Sebastian; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Christian Joachim; Schmidt, Hans Rudolf; Schmidt, Marten Ole; Schmidt, Martin; Schmidt, Nicolas Vincent; Schmiederer, Stefan; Schneider, R; Schukraft, Jurgen; Schulze, R; Schutz, Yves Roland; Schwarz, Kilian Eberhard; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; Scott, Rebecca Michelle; Sedykh, S; Sefcik, Michal; Seger, Janet Elizabeth; Sekiguchi, Yuko; Sekihata, Daiki; Selyuzhenkov, Ilya; Senosi, Kgotlaesele; Senyukov, Serhiy; Serradilla Rodriguez, Eulogio; Sett, Priyanka; Sevcenco, Adrian; Shabanov, Arseniy; Shabetai, Alexandre; Shahoyan, Ruben; Shaikh, Wadut; Shangaraev, Artem; Sharma, Anjali; Sharma, Ankita; Sharma, Mona; Sharma, Monika; Sharma, Natasha; Sheikh, Ashik Ikbal; Shigaki, Kenta; Shimansky, S; Shou, Qiye; Shtejer Diaz, Katherin; Shukla, P; Sibiryak, Yury; Sicking, Eva; Siddhanta, Sabyasachi; Sielewicz, Krzysztof Marek; Siemiarczuk, Teodor; Silaeva, Svetlana; Silvermyr, David Olle Rickard; Silvestre, Catherine Micaela; Simatovic, Goran; Simon, Reinhard S; Simonetti, Giuseppe; Singaraju, Rama Narayana; Singh, Ranbir; Singhal, Vikas; Sarkar - Sinha, Tinku; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Slupecki, Maciej; Smirnov, Nikolai; Smykov, L; Snellings, Raimond; Snellman, Tomas Wilhelm; Solveit, Hans Kristian; Sommer, Wolfgang; Song, Jihye; Song, Myunggeun; Soramel, Francesca; Sorensen, Soren Pontoppidan; Sozzi, Federica; Spiriti, Eleuterio; Sputowska, Iwona Anna; Srivastava, Brijesh Kumar; Stachel, Johanna; Stan, Ionel; Stankus, Paul; Stelzer, Herbert; Stenlund, Evert Anders; Stiller, Johannes; Stocco, Diego; Stockmeyer, MR; Storetvedt, Maksim Melnik; Strmen, Peter; Alarcon Do Passo Suaide, Alexandre; Sugitate, Toru; Suire, Christophe Pierre; Suleymanov, Mais Kazim Oglu; Suljic, Miljenko; Sultanov, Rishat; Sumbera, Michal; Sumowidagdo, Suharyo; Suzuki, Ken; Swain, Sagarika; Szabo, Alexander; Szarka, Imrich; Tabassam, Uzma; Takahashi, Jun; Tambave, Ganesh Jagannath; Tanaka, Naoto; Tarhini, Mohamad; Tariq, Mohammad; Tarzila, Madalina-gabriela; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terasaki, Kohei; Terrevoli, Cristina; Teyssier, Boris; Thakur, Dhananjaya; Thakur, Sanchari; Thomas, Deepa; Thoresen, Freja; Tieulent, Raphael Noel; Tikhonov, Anatoly; Tilsner, Heinz; Timmins, Anthony Robert; Toia, Alberica; Rojas Torres, Solangel; Tripathy, Sushanta; Trogolo, Stefano; Trombetta, Giuseppe; Tropp, Lukas; Trubnikov, Victor; Trzaska, Wladyslaw Henryk; Trzeciak, Barbara Antonina; Tsiledakis, Georgios; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ullaland, Kjetil; Umaka, Ejiro Naomi; Uras, Antonio; Usai, Gianluca; Utrobicic, Antonija; Vala, Martin; Van Der Maarel, Jasper; Van Hoorne, Jacobus Willem; Van Leeuwen, Marco; Vanat, Tomas; Vargas, H; Vande Vyvre, Pierre; Varga, Dezso; Diozcora Vargas Trevino, Aurora; Vargyas, Marton; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vauthier, Astrid; Vazquez Doce, Oton; Vechernin, Vladimir; Veen, Annelies Marianne; Velure, Arild; Vercellin, Ermanno; Vergara Limon, Sergio; Vernet, Renaud; Vertesi, Robert; Vickovic, Linda; Vigolo, Sonia; Viinikainen, Jussi Samuli; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Villatoro Tello, Abraham; Vinogradov, Alexander; Vinogradov, Leonid; Virgili, Tiziano; Vislavicius, Vytautas; Vodopyanov, Alexander; Volkl, Martin Andreas; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; Von Haller, Barthelemy; Vorobyev, Ivan; Voscek, Dominik; Vranic, Danilo; Vrlakova, Janka; Vulpescu, B; Wagner, Boris; Wang, Hongkai; Wang, Mengliang; Wang, Yifei; Watanabe, Daisuke; Watanabe, Kengo; Watanabe, Yosuke; Weber, Michael; Weber, Steffen Georg; Wegerle, Dominik; Weiser, Dennis Franz; Wenzel, Sandro Christian; Wessels, Johannes Peter; Westerhoff, Uwe; Whitehead, Andile Mothegi; Wiechula, Jens; Wikne, Jon; Wilk, Alexander; Wilk, Grzegorz Andrzej; Wilkinson, Jeremy John; Willems, Guido Alexander; Williams, Crispin; Willsher, Emily; Windelband, Bernd Stefan; Winn, Michael; Witt, William Edward; Xu, C; Yalcin, Serpil; Yamakawa, Kosei; Yang, Ping; Yano, Satoshi; Yin, Zhongbao; Yokoyama, Hiroki; Yoo, In-kwon; Yoon, Jin Hee; Yurchenko, Volodymyr; Yurevich, Vladimir; Zaccolo, Valentina; Zaman, Ali; Zampolli, Chiara; Correa Zanoli, Henrique Jose; Zanevski, Yuri; Zardoshti, Nima; Zarochentsev, Andrey; Zavada, Petr; Zavyalov, Nikolay; Zbroszczyk, Hanna Paulina; Zhalov, Mikhail; Zhang, Haitao; Zhang, Xiaoming; Zhang, Yonghong; Chunhui, Zhang; Zhang, Zuman; Zhao, Chengxin; Zhigareva, Natalia; Zhou, Daicui; Zhou, You; Zhou, Zhuo; Zhu, Hongsheng; Zhu, Jianhui; Zichichi, Antonino; Zimmer, Stefan; Zimmermann, Alice; Zimmermann, Markus Bernhard; Zinovjev, Gennady; Zmeskal, Johann; Zou, Shuguang

    2017-01-01

    The Transition Radiation Detector (TRD) was designed and built to enhance the capabilities of the ALICE detector at the Large Hadron Collider (LHC). While aimed at providing electron identification and triggering, the TRD also contributes significantly to the track reconstruction and calibration in the central barrel of ALICE. In this paper the design, construction, operation, and performance of this detector are discussed. A pion rejection factor of up to 410 is achieved at a momentum of 1 GeV/c in p-Pb collisions and the resolution at high transverse momentum improves by about 40% when including the TRD information in track reconstruction. The triggering capability is demonstrated both for jet and for electron selection.

  8. Tracking properties of the ATLAS Transition Radiation Tracker (TRT)

    CERN Document Server

    Krasnopevtsev, Dimitriy; The ATLAS collaboration

    2016-01-01

    The tracking performance parameters of the ATLAS Transition Radiation Tracker (TRT) as part of the ATLAS Inner Detector are described for different data taking conditions in proton-proton, proton-lead and heavy ion collisions at the Large Hadron Collider (LHC). These studies are performed using data collected during the first and the second periods of LHC operation and are compared with Monte Carlo simulations. The performance of the TRT, operating with different gas mixtures (Xenon-based and Argon-based) and for high track multiplicities is presented. These studies show that the tracking performance of the TRT with these two gas mixtures is similar and that the detector still provides a significant contribution to the particle momentum measurement of the overall Inner Detector of the ATLAS experiment.

  9. The effects of radiative and microphysical processes on simulated warm and transition season arctic stratus

    Science.gov (United States)

    Harrington, Jerry Y.

    A cloud-resolving model (CRM) version of RAMS, coupled to explicit bin resolving microphysics and a new two-stream radiative transfer code is used to study various aspects of Arctic stratus clouds (ASC). The two-stream radiative transfer model is coupled in a consistent fashion to the bulk microphysical parameterization of Walko et al., (1995), an explicit liquid bin microphysical model (e.g., Feingold et al., 1996a) and a mixed-phase microphysical model (Reisin et al., 1996). These models are used to study both warm (summer) season and transition (fall and spring) season ASC. Equations are developed for the inclusion of the radiative term in the drop growth equation and the effect is studied in a trajectory parcel model (TPM) and the CRM. Arctic stratus simulated with the new CRM framework compared well with the observations of Curry (1986). Along with CCN concentrations, it is shown that drop distribution shape and optical property methods strongly impact cloud evolution through their effect on the radiative properties. Broader cloud top distributions lead to clouds with more shallow depths and circulation strengths as more shortwave radiation is absorbed while the opposite occurs for narrow distribution functions. Radiative-cloud interactions using mean effective radii are shown to be problematic, while conserving re and N of the distribution function (as per Hu and Stamnes, 1993) produces similar cloud evolution as compared to detailed computations. Radiative effects on drop vapor deposition growth can produce drizzle about 30 minutes earlier and is strongly dependent upon cloud top residence time of the parcels. The same set of trajectories assists drizzle production in the radiation and no-radiation cases. Not only is the growth of larger drops enhanced by the radiative effect, but drops with rCRM show a smaller impact of the radiative influence; this is attributed to the spurious production of cloud top supersaturations by Eulerian models (Stevens et al

  10. The transition radiation. I: numerical study of the angular and spectral distributions; Le rayonnement de transition optique. I: etude numerique des distributions angulaires et spectrales

    Energy Technology Data Exchange (ETDEWEB)

    Couillaud, Ch.; Haouat, G

    1999-07-01

    The optical transition radiation (OTR) is extensively used since many years as a beam visualisation tool on electron accelerators and serves to monitor the beam during its transport adjustment. Its spatial and temporal characteristics make it very attractive as a diagnostic tool and allow measurements of the beam energy and transverse and longitudinal emittances. We present a numerical study of the transition radiation process in the optical region of the radiated spectrum (OTR) and in the higher part (XTR). Spatial and spectral properties are described. They are used to describe experimental observations performed on the ELSA electron-beam facility. An analytical description of the angular distributions of visible radiation emitted by birefringent targets, used as OTR sources, is also proposed. We also analyze interference phenomena between two OTR sources and show the advantage of using this interferometer as a diagnostic tool for tenth MeV electron accelerators. At last, we present an analytical model allowing to design a soft X-ray source to be installed on the ELSA facility and using either a multi-foil stack or a multilayer of two materials of different permittivities. (authors)

  11. Single-cycle Terahertz Pulses with >0.2 V/A Field Amplitudes via Coherent Transition Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Daranciang, Dan; /Stanford U., Chem. Dept.; Goodfellow, John; /Stanford U. Materials Sci. Dept.; Fuchs, Matthias; /SIMES, Stanford /SLAC, PULSE; Wen, Haidan; /ANL, APS; Ghimire, Shambhu; /SLAC, PULSE; Reis, David A.; /SIMES, Sanford /SLAC, PULSE /Stanford U., Appl. Phys. Dept.; Loos, Henrik; Fisher, Alan S.; /SLAC, LCLS; Lindenberg, Aaron M.; /Stanford U. Materials Sci. Dept. /SIMES, Stanford /SLAC, PULSE

    2012-02-15

    We demonstrate terahertz pulses with field amplitudes exceeding 0.2 V/{angstrom} generated by coherent transition radiation. Femtosecond, relativistic electron bunches generated at the Linac Coherent Light Source are passed through a beryllium foil, and the emitted radiation is characterized as a function of the bunch duration and charge. Broadband pulses centered at a frequency of 10 THz with energies of 140 {mu}J are measured. These far-below-bandgap pulses drive a nonlinear optical response in a silicon photodiode, with which we perform nonlinear autocorrelations that yield information regarding the terahertz temporal profile. Simulations of the spatiotemporal profile agree well with experimental results.

  12. Recent aging studies for the ATLAS transition radiation tracker

    CERN Document Server

    Capéans-Garrido, M; Anghinolfi, F; Arik, E; Baker, O K; Baron, S; Benjamin, D; Bertelsen, H; Bondarenko, V; Bychkov, V; Callahan, J; Cardiel-Sas, L; Catinaccio, A; Cetin, S A; Cwetanski, Peter; Dam, M; Danielsson, H; Dittus, F; Dologshein, B; Dressnandt, N; Driouichi, C; Ebenstein, W L; Eerola, Paule Anna Mari; Farthouat, Philippe; Fedin, O; Froidevaux, D; Gagnon, P; Grichkevitch, Y; Grigalashvili, N S; Hajduk, Z; Hansen, P; Kayumov, F; Keener, P T; Kekelidze, G D; Khristatchev, A; Konovalov, S; Koudine, L; Kovalenko, S; Kowalski, T; Kramarenko, V A; Krüger, K; Laritchev, A; Lichard, P; Luehring, F C; Lundberg, B; Maleev, V; Markina, I; McFarlane, K W; Mialkovski, V; Mindur, B; Mitsou, V A; Morozov, S; Munar, A; Muraviev, S; Nadtochy, A; Newcorner, F M; Ogren, H; Oh, S H; Olszowska, J; Passmore, S; Patritchev, S; Peshekhonov, V D; Petti, R; Price, M; Rembser, C; Rohne, O; Romaniouk, A; Rust, D R; Ryabov, Yu; Ryzhov, V; Shchegelskii, V; Seliverstov, D M; Shin, T; Shmeleva, A; Smirnov, S; Sosnovtsev, V V; Soutchkov, V; Spiridenkov, E; Szczygiel, R; Tikhomirov, V; Van Berg, R; Vassilakopoulos, V I; Vassilieva, L; Wang, C; Williams, H H; Zalite, A

    2004-01-01

    The transition radiation tracker (TRT) is one of the three subsystems of the inner detector of the ATLAS experiment. It is designed to operate for 10 yr at the LHC, with integrated charges of similar to 10 C/cm of wire and radiation doses of about 10 Mrad and 2 multiplied by 10**1**4 neutrons/cm**2. These doses translate into unprecedented ionization currents and integrated charges for a large-scale gaseous detector. This paper describes studies leading to the adoption of a new ionization gas regime for the ATLAS TRT. In this new regime, the primary gas mixture is 70%Xe-27%CO**2-3%O**2. It is planned to occasionally flush and operate the TRT detector with an Ar-based ternary mixture, containing a small percentage of CF**4, to remove, if needed, silicon pollution from the anode wires. This procedure has been validated in realistic conditions and would require a few days of dedicated operation. This paper covers both performance and aging studies with the new TRT gas mixture. 12 Refs.

  13. Observation and Characterization of Coherent Optical Radiation and Microbunching Instability in the SLAC Next Linear Collider Test Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Weathersby, S.; Dunning, M.; Hast, C.; Jobe, K.; McCormick, D.; Nelson, J.; Xiang, D.; /SLAC

    2011-06-02

    The NLC Test Accelerator (NLCTA) at SLAC is currently configured for a proof-of-principle echo-enabled harmonic generation (EEHG) experiment using an 120 MeV beam. During commissioning, unexpected coherent optical undulator radiation (CUR) and coherent optical transition radiation (COTR) was observed when beam is accelerated off-crest and compressed after the chicanes. The CUR and COTR is likely due to a microbunching instability where the initial small ripples in cathode drive laser is compressed and amplified. In this paper we present the observation and characterization of the CUR, COTR and microbunching instability at NLCTA.

  14. The dynamics of radiation driven, optically thick winds

    CERN Document Server

    Shen, Rong-Feng; Piran, Tsvi

    2016-01-01

    Recent observation of some luminous transient sources with low color temperatures suggests that the emission is dominated by optically thick winds driven by super-Eddington accretion. We present a general analytical theory of the dynamics of radiation pressure-driven, optically thick winds. Unlike the classical adiabatic stellar wind solution whose dynamics are solely determined by the sonic radius, here the loss of the radiation pressure due to photon diffusion also plays an important role. We identify two high mass loss rate regimes ($\\dot{M} > L_{\\rm Edd\\,}/c^2$). In the large total luminosity regime the solution resembles an adiabatic wind solution. Both the radiative luminosity, $L$, and the kinetic luminosity, $L_k$, are super-Eddington with $L < L_k$ and $L \\propto L_k^{1/3}$. In the lower total luminosity regime most of the energy is carried out by the radiation with $L_k < L \\approx L_{\\rm Edd\\,}$. In a third, low mass loss regime ($\\dot{M} < L_{\\rm Edd\\,}/c^2$), the wind becomes optically t...

  15. Modeling silica aerogel optical performance by determining its radiative properties

    Directory of Open Access Journals (Sweden)

    Lin Zhao

    2016-02-01

    Full Text Available Silica aerogel has been known as a promising candidate for high performance transparent insulation material (TIM. Optical transparency is a crucial metric for silica aerogels in many solar related applications. Both scattering and absorption can reduce the amount of light transmitted through an aerogel slab. Due to multiple scattering, the transmittance deviates from the Beer-Lambert law (exponential attenuation. To better understand its optical performance, we decoupled and quantified the extinction contributions of absorption and scattering separately by identifying two sets of radiative properties. The radiative properties are deduced from the measured total transmittance and reflectance spectra (from 250 nm to 2500 nm of synthesized aerogel samples by solving the inverse problem of the 1-D Radiative Transfer Equation (RTE. The obtained radiative properties are found to be independent of the sample geometry and can be considered intrinsic material properties, which originate from the aerogel’s microstructure. This finding allows for these properties to be directly compared between different samples. We also demonstrate that by using the obtained radiative properties, we can model the photon transport in aerogels of arbitrary shapes, where an analytical solution is difficult to obtain.

  16. Tunnel optical radiation in In{sub x}Ga{sub 1−x}N

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrov, Dimiter; Skerget, Shawn [Semiconductor Research Laboratory, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B5E1 (Canada)

    2014-02-21

    An investigation of tunnel optical radiation in epitaxial layers of n-type In{sub x}Ga{sub 1−x}N grown on p-type GaN by novel plasma based migration enhanced epitaxy is presented. Experimental results of electro-luminescence spectra for In{sub x}Ga{sub 1−x}N/p−GaN hetero-junctions were obtained and they show two well expressed optical bands - one in range 500-540 nm and other in range 550-610 nm. An interesting detail is that each band begins and ends by sharp drops of the radiation, which nearly approach zero. A theoretical investigation of the unusual behavior of these spectra was done using LCAO electron band structure calculations. The optical ranges of these bands show that the radiation occurs in the In{sub x}Ga{sub 1−x}N region. In fact, substitutions of In atoms in Ga sites creates defects in the structure of In{sub x}Ga{sub 1−x}N and the corresponding LCAO matrix elements are found on this basis. The LCAO electron band structures are calculated considering the interactions between nearest-neighbor orbitals. Electron energy pockets are found in both the conduction and the valence bands at the Γ point of the electron band structures. Also it is found that these pockets are separated by distances, for which there is overlapping between the electron wave functions describing localized states belonging to the pockets, and as a result tunnel optical radiation can take place. This type of electron transition - between such a pocket in the conduction band and a pocket in the valence band - occurs in In{sub x}Ga{sub 1−x}N, causing the above described optical bands. This conclusion concurs with the fact that the shapes of these bands change with change of the applied voltage.

  17. Development of a distributed radiation detection system using optical fibers

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, F.; Inouchi, Goro; Takada, Eiji; Takahashi, Hiroyuki; Iguchi, Tetsuo; Nakazawa, Masaharu [Tokyo Univ. (Japan). Faculty of Engineering; Kakuta, Tsunemi

    1996-07-01

    We have confirmed the importance of temperature and dose rate for the response of Ge-doped fibers to radiation. A phenomenological model have been found to account for temperature and dose rate effects. From this model it is possible to make dose predictions from attenuation measurements when the temperature and dose rate are known. Ge-doped fibers have been found to have a relatively low sensitivity to both neutron and gamma radiation. In addition, temperature and dose rate dependencies complicate the analysis. However we point out that these problems may all be solved if we use fibers, such as P-doped fibers, which contain color centers of long lifetime. This would remove both the temperature and dose rate dependencies that complicate the use of Ge-doped fibers, in addition the radiation sensitivity is increased. Finally OTDR has been investigated as a possible read-out method for distributed radiation measurements. For our system the minimum pulse length was 3ns, giving a spatial resolution in the meter range and a response length to radiation of about 10 m if accurate dose values where to be obtained. We found OTDR to be a suitable method for radiation induced attenuation measurements in optical fibers, especially for long fiber lengths and long time scales where questions of light source stability becomes important for other systems. (S.Y.)

  18. Nonintercepting electron beam size monitor using optical diffraction radiation interference

    Directory of Open Access Journals (Sweden)

    A. Cianchi

    2011-10-01

    Full Text Available In recent years, the use of diffraction radiation (DR, emitted when a charged particle beam passes through a rectangular slit, has been proposed and successfully tested as a nonintercepting diagnostic of high brightness beams. However, some problems related to the control of the particle trajectory through the slit still remain. If an additional slit is placed in front of the first one, at a distance shorter than the radiation formation length, interference between the forward diffraction radiation from the upstream slit and the backward diffraction radiation from the downstream slit can be observed. In this paper we report the first experimental observation of this effect, which we call here optical diffraction radiation interference (ODRI. If the two slits have different dimensions and are not aligned on the same axis, the properties of the ODRI pattern can be effectively used for nonintercepting beam diagnostics, especially for the unambiguously determination of the beam size. Indeed, the advantage of ODRI compared with a single aperture DR screen is due to the reduction of synchrotron radiation background, the increase of sensitivity for transverse beam dimensions, and the possibility to separate effects caused by the beam size and by beam offset within the slit.

  19. Optical properties of the PANDA barrel DIRC radiator bars

    Energy Technology Data Exchange (ETDEWEB)

    Kalicy, Grzegorz; Krebs, Marvin; Peters, Klaus [GSI, Darmstadt (Germany); Goethe Universitaet, Frankfurt (Germany); Schwarz, Carsten; Schwiening, Jochen [GSI, Darmstadt (Germany); Collaboration: PANDA-Collaboration

    2015-07-01

    The PANDA experiment at the Facility for Antiproton and Ion Research in Europe (FAIR) at GSI, Darmstadt, will study fundamental questions of hadron physics and QCD. A fast focusing DIRC (Detection of Internally Reflected Cherenkov light) counter will provide hadronic particle identification (PID) in the barrel region of the PANDA detector. To meet the PID requirements, the Barrel DIRC has to provide precise measurements of the Cherenkov angle, which is conserved for Cherenkov photons propagating through the radiator by total internal reflection. The radiators, rectangular bars made from fused silica, have to fulfill very strict optical and mechanical requirements. This includes the squareness and parallelism of the sides of the bars, sharp corners, and a very smooth surface polish, ensuring that the Cherenkov photons reach the optical sensors without angular distortions. Currently the Barrel DIRC is at the final design stage and several different bar shapes and fabrication methods are being considered for the final detector. An optical setup, consisting of a computer-controlled positioning and a multi-wavelength laser system, is used to evaluate the radiator bars to obtain critical values like transmittance and reflectivity. The current results and techniques are presented on this poster.

  20. Optical fingerprint of non-covalently functionalized transition metal dichalcogenides

    Science.gov (United States)

    Feierabend, Maja; Malic, Ermin; Knorr, Andreas; Berghäuser, Gunnar

    2017-09-01

    Atomically thin transition metal dichalcogenides (TMDs) hold promising potential for applications in optoelectronics. Due to their direct band gap and the extraordinarily strong Coulomb interaction, TMDs exhibit efficient light-matter coupling and tightly bound excitons. Moreover, large spin orbit coupling in combination with circular dichroism allows for spin and valley selective optical excitation. As atomically thin materials, they are very sensitive to changes in the surrounding environment. This motivates a functionalization approach, where external molecules are adsorbed to the materials surface to tailor its optical properties. Here, we apply the density matrix theory to investigate the potential of non-covalently functionalized monolayer TMDs. Considering exemplary molecules with a strong dipole moment, we predict spectral redshifts and the appearance of an additional side peak in the absorption spectrum of functionalized TMDs. We show that the molecular characteristics, e.g. coverage, orientation and dipole moment, crucially influence the optical properties of TMDs, leaving a unique optical fingerprint in the absorption spectrum. Furthermore, we find that the molecular dipole moments open a channel for coherent intervalley coupling between the high-symmetry K and K\\prime points which may create new possibilities for spin-valleytronics application.

  1. Optically Thin Metallic Films for High-radiative-efficiency Plasmonics

    CERN Document Server

    Yang, Yi; Hsu, Chia Wei; Miller, Owen D; Joannopoulos, John D; Soljačić, Marin

    2016-01-01

    Plasmonics enables deep-subwavelength concentration of light and has become important for fundamental studies as well as real-life applications. Two major existing platforms of plasmonics are metallic nanoparticles and metallic films. Metallic nanoparticles allow efficient coupling to far field radiation, yet their synthesis typically leads to poor material quality. Metallic films offer substantially higher quality materials, but their coupling to radiation is typically jeopardized due to the large momentum mismatch with free space. Here, we propose and theoretically investigate optically thin metallic films as an ideal platform for high-radiative-efficiency plasmonics. For far-field scattering, adding a thin high-quality metallic substrate enables a higher quality factor while maintaining the localization and tunability that the nanoparticle provides. For near-field spontaneous emission, a thin metallic substrate, of high quality or not, greatly improves the field overlap between the emitter environment and ...

  2. Local Radiative Hydrodynamic and Magnetohydrodynamic Instabilities in Optically Thick Media

    CERN Document Server

    Blaes, Omer M; Blaes, Omer; Socrates, Aristotle

    2003-01-01

    We examine the local conditions for radiative damping and driving of short wavelength, propagating hydrodynamic and magnetohydrodynamic (MHD) waves in static, optically thick, stratified equilibria. We show that so-called strange modes in stellar oscillation theory and magnetic photon bubbles are intimately related and are both fundamentally driven by the background radiation pressure acting on density and opacity fluctuations in compressible waves. We identify the necessary criteria for unstable driving of these waves, and show that this driving can exist in both gas and radiation pressure dominated media, as well as pure Thomson scattering media in the MHD case. We discuss the physical origin of these instabilities, and briefly describe the conditions under which they might be manifested in both stellar envelopes and accretion disks.

  3. Optical Cherenkov radiation in ultrafast cascaded second-harmonic generation

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Zhou, Binbin

    2010-01-01

    the dispersive wave. Finally, an investigation of recent experimental results uncovers a four-wave-mixing phenomenon related to Cherenkov radiation that is an additional generation mechanism of long-wavelength radiation that can occur during soliton compression. We discuss the conditions that lead......We show through theory and numerics that when few-cycle femtosecond solitons are generated through cascaded (phase-mismatched) second-harmonic generation, these broadband solitons can emit optical Cherenkov radiation in the form of linear dispersive waves located in the red part of the spectrum....... The beating between the dispersive wave and the soliton generates trailing temporal oscillations on the compressed soliton. Insertion of a simple short-wave pass filter after the crystal can restore a clean soliton. On the other hand, bandpass filtering around the dispersive wave peak results in near...

  4. Modulatable optical radiators and metasurfaces based on quantum nanoantennas

    KAUST Repository

    Chen, Pai-Yen

    2015-01-20

    We investigate the tunable and switchable optical radiators and metamaterials formed by metallic nanodipole antennas with submicroscopic gaps (1.2 nm), of which linear and third-order nonlinear quantum conductivities are observed due to the photon-assisted tunneling effect. The quantum conductivities induced at the nanogap are relevant to power dissipations, which can be enhanced by the strongly localized optical fields associated with the plasmonic resonance. We demonstrate that the scattering property of an individual quantum nanoantenna and the transparency of a metamasurface constituted of it can be tuned by electrostatically controlling the linear conductivity (electronic tuning) or by adjusting the irradiation intensity that varies the nonlinear quantum conductivity (all-optical tuning).

  5. Optical Synchrotron Radiation Beam Imaging with a Digital Mask

    Energy Technology Data Exchange (ETDEWEB)

    Fiorito, R. B. [University of Maryland, College Park, MD (United States); Zhang, H. D. [University of Maryland, College Park, MD (United States); Corbett, W. J. [SLAC, Menlo Park, CA (United States); Fisher, A. S. [SLAC, Menlo Park, CA (United States); Mok, W. Y. [SLAC, Menlo Park, CA (United States); Tian, K. [SLAC, Menlo Park, CA (United States); Douglas, D. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Wilson, F. G. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Zhang, S. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Mitsuhashi, T. M. [KEK, Tsukuba (Japan); Shkvarunets, A. G. [University of Maryland, College Park, MD (United States)

    2012-11-01

    We have applied a new imaging/optical masking technique, which employs a digital micro-mirror device (DMD) and optical synchrotron radiation (OSR), to perform high dynamic range (DR) beam imaging at the JLAB Energy Recovery Linac and the SLAC/SPEAR3 Synchrotron Light Source. The OSR from the beam is first focused onto the DMD to produce a primary image; selected areas of this image are spatially filtered by controlling the state of individual micro-mirrors; and finally, the filtered image is refocused onto a CCD camera. At JLAB this technique has been used successfully to view the beam halo with a DR ~ 105. At SPEAR3 the DMD was used to filter out the bright core of the stored beam to study the turn-by-turn dynamics of the 10-3 weaker injected beam. We describe the optical performance, present limitations and our plans to improve the DR of both experimental systems.

  6. Near-uv and optical observations of the transiting hot Jupiter WASP-1b

    Science.gov (United States)

    Pearson, K. A.; Zellem, R.; Biddle, L. I.; Amaya, H.; Watson, Z.; Griffith, C.; Small, L.; Hume, J.

    2014-03-01

    We present simultaneous near-UV (U-band) and optical (B-band) photometric observations of the primary transit of the highly irradiated, hot-Jupiter WASP-1b on the Kuiper 61" telescope. We use our results to search for timing transit variations, which would indicate additional planets, and provide new constraints on WASP-1b's physical parameters. Assuming the opacity at these two photometric bands is dominated by Rayleigh scattering by molecular hydrogen, we can place strong upper limits on its radius. Such constraints can limit the degeneracy between an exoplanet's physical radius and atmospheric composition in radiative transfer retrievals. Additionally its host star is chromospherically active and WASP-1b orbits within in the co-rotation radius of the star making it likely that WASP-1b has a bowshock. Therefore, we will search for a planetary magnetic field as indicated by an early ingress in the near-UV light curve compared to the optical due to the bowshock itself. Such measurements would confirm the observational methodology of detecting magnetic fields around transiting exoplanets, place an upper limit on WASP-1b's magnetic field strength, and confirm previous theoretical estimations of hot Jupiter magnetic fields.

  7. Tracking properties of the ATLAS Transition Radiation Tracker (TRT)

    CERN Document Server

    Krasnopevtsev, Dimitrii; The ATLAS collaboration

    2016-01-01

    The tracking performance parameters of the ATLAS Transition Radiation Tracker (TRT) as part of the ATLAS Inner Detector (ID) are described for different data taking conditions in proton-proton collisions at the Large Hadron Collider (LHC). These studies are performed using data collected during the first (Run 1) and the second (Run 2) periods of LHC operation and are compared with Monte Carlo simulations. The performance of the TRT, operating with Xe-based (Xe-based) and Argon-based (Ar-based) gas mixtures and its dependence on the TRT occupancy is presented. No significant degradation of position measurement accuracy was found up to occupancies of about 20\\% in Run 1. The relative number of reconstructed tracks in ID that also have a extension in the TRT was observed to be almost constant with the increase of occupancies up to 50\\%. Even in configurations where tracks are close to each other, the reconstruction algorithm is still able to find the correct TRT hits and properly reconstruct the tracks.

  8. Optical Observations of the Transiting Exoplanet GJ 1214b

    CERN Document Server

    Teske, Johanna K; Mueller, Matthias; Griffith, Caitlin A

    2013-01-01

    We observed nine primary transits of the super-Earth exoplanet GJ 1214b in several optical photometric bands from March to August 2012, with the goal of constraining the short-wavelength slope of the spectrum of GJ 1214b. Our observations were conducted on the Kuiper 1.55 m telescope in Arizona and the STELLA-I robotic 1.2 m telescope in Tenerife, Spain. From the derived light curves we extracted transit depths in R (0.65 {\\mu}m), V (0.55 {\\mu}m), and g' (0.475 {\\mu}m) bands. Most previous observations of this exoplanet suggest a flat spectrum varying little with wavelength from the near-infrared to the optical, corresponding to a low-scale-height, high-molecular-weight atmosphere. However, a handful of observations around Ks band (~2.15 {\\mu}m) and g-band (~0.46 {\\mu}m) are inconsistent with this scenario and suggest a variation on a hydrogen- or water-dominated atmosphere that also contains a haze layer of small particles. In particular, the g-band observations of de Mooij et al. (2012), consistent with Ray...

  9. Transition radiation at radio frequencies from ultra-high energy neutrino-induced showers

    CERN Document Server

    Motloch, Pavel; Privitera, Paolo; Zas, Enrique

    2015-01-01

    Coherent radiation at radio frequencies from high-energy showers fully contained in a dense radio-transparent medium - like ice, salt or regolith - has been extensively investigated as a promising technique to search for ultra-high energy (UHE) neutrinos. Additional emission in the form of transition radiation may occur when a neutrino-induced shower produced close to the Earth surface emerges from the ground into atmospheric air. We present the first detailed evaluation of transition radiation from high-energy showers crossing the boundary between two different media. We found that transition radiation is sizable over a wide solid angle and coherent up to $\\sim$ 1 GHz. These properties encourage further work to evaluate the potential of a large-aperture UHE neutrino experiment based on detection of transition radiation.

  10. Mechanisms of Radiation Damage Generated by Ionizing Radiation in Optical Waveguides

    Science.gov (United States)

    1988-09-01

    SUMMARY OF APPENDIX B "Optical scattering and SPR study of ZBLAN glass : Dependence on preparation and processing methods" LMater. Sci. Forum 19-20...studied the types of centers created by ionizing radiation in ZBLAN (ZrF 4, BaF 2 , LaF 3, AlF 3 , and NaF) glass . Samples of ZBLAN were prepared using...radiation-induced centers in ZBLAN glass depend strongly on the glass -processing conditions. For example, ZBLAN glasses processed with CC14 yield paramagnetic

  11. Simulation of radiation effects on three-dimensional computer optical memories

    Science.gov (United States)

    Moscovitch, M.; Emfietzoglou, D.

    1997-01-01

    A model was developed to simulate the effects of heavy charged-particle (HCP) radiation on the information stored in three-dimensional computer optical memories. The model is based on (i) the HCP track radial dose distribution, (ii) the spatial and temporal distribution of temperature in the track, (iii) the matrix-specific radiation-induced changes that will affect the response, and (iv) the kinetics of transition of photochromic molecules from the colored to the colorless isomeric form (bit flip). It is shown that information stored in a volume of several nanometers radius around the particle's track axis may be lost. The magnitude of the effect is dependent on the particle's track structure.

  12. Optical synchrotron radiation beam imaging with a digital mask

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hao [Univ. of Maryland, College Park, MD (United States); Fiorito, Ralph [Univ. of Maryland, College Park, MD (United States); Corbett, Jeff [SLAC National Accelerator Lab., Menlo Park, CA (United States); Shkvarunets, Anatoly [Univ. of Maryland, College Park, MD (United States); Tian, Kai [SLAC National Accelerator Lab., Menlo Park, CA (United States); Fisher, Alan [SLAC National Accelerator Lab., Menlo Park, CA (United States); Douglas, D. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Wilson, F. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Zhang, S. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Mok, W. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Mitsuhashi, T. [KEK, Tsukuba (Japan)

    2016-01-01

    The 3GeV SPEAR3 synchrotron light source operates in top-up injection mode with up to 500mA circulating in the storage ring (equivalently 392nC). Each injection pulse contains only 40-80 pC producing a contrast ratio between total stored charge and injected charge of about 6500:1. In order to study transient injected beam dynamics during User operations, it is desirable to optically image the injected pulse in the presence of the bright stored beam. In the present work this is done by re-imaging visible synchrotron radiation onto a digital micro-mirror-array device (DMD), which is then used as an optical mask to block out light from the bright central core of the stored beam. The physical masking, together with an asynchronously-gated, ICCD imaging camera makes it is possible to observe the weak injected beam component on a turn-by-turn basis. The DMD optical masking system works similar to a classical solar coronagraph but has some distinct practical advantages: i.e. rapid adaption to changes in the shape of the stored beam, high extinction ratio for unwanted light and minimum scattering from the primary beam into the secondary optics. In this paper we describe the DMD masking method, features of the high dynamic range point spread function for the SPEAR3 optical beam line and measurements of the injected beam in the presence of the stored beam.

  13. Interplay of radiative and nonradiative transitions in surface hopping with radiation-molecule interactions

    Energy Technology Data Exchange (ETDEWEB)

    Bajo, Juan José [Departamento de Química-Física I, Universidad Complutense de Madrid, 28040 Madrid (Spain); Granucci, Giovanni, E-mail: giovanni.granucci@unipi.it; Persico, Maurizio [Università di Pisa, Dipartimento di Chimica e Chimica Industriale, via Risorgimento 35, 56126 Pisa (Italy)

    2014-01-28

    We implemented a method for the treatment of field induced transitions in trajectory surface hopping simulations, in the framework of the local diabatization scheme, especially suited for on-the-fly dynamics. The method is applied to a simple one-dimensional model with an avoided crossing and compared with quantum wavepacket dynamics. The results show the importance of introducing a proper decoherence correction to surface hopping, in order to obtain meaningful results. Also the energy conservation policy of standard surface hopping must be revised: in fact, the quantum wavepacket energetics is well reproduced if energy absorption/emission is allowed for in the hops determined by radiation-molecule coupling. To our knowledge, this is the first time the issues of decoherence and energy conservation have been analyzed in depth to devise a mixed quantum-classical method for dynamics with molecule-field interactions.

  14. Subwavelength optics with hyperbolic metamaterials: Waveguides, scattering, and optical topological transitions

    DEFF Research Database (Denmark)

    Ishii, Satoshi; Babicheva, Viktoriia E.; Shalaginov, Mikhail Y.

    2016-01-01

    Hyperbolic metamaterials possess unique optical properties owing to their hyperbolic dispersion. As hyperbolic metamaterials can be constructed just from periodic multilayers of metals and dielectrics, they have attracted considerable attention in the nanophotonics community. Here, we review some...... of our recent works and demonstrate the benefits of using hyperbolic metamaterials in plasmonic waveguides and light scattering. We also discuss nonlocal topological transitions in the hyperbolic metamaterials that effectively induce a zero refractive index....

  15. Beam Size Measurement by Optical Diffraction Radiation and Laser System for Compton Polarimeter

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chuyu [Peking Univ., Beijing (China)

    2012-12-31

    difficulty of diagnostics. For most cases, intercepting measurements are no longer acceptable, and nonintercepting method like synchrotron radiation monitor can not be applied to linear accelerators. The development of accelerator technology asks for simutanous diagnostics innovations, to expand the performance of diagnostic tools to meet the requirements of the next generation accelerators. Diffraction radiation and inverse Compton scattering are two of the most promising techniques, their nonintercepting nature avoids perturbance to the beam and damage to the instrumentation. This thesis is divided into two parts, beam size measurement by optical diffraction radiation and Laser system for Compton polarimeter. Diffraction radiation, produced by the interaction between the electric field of charged particles and the target, is related to transition radiation. Even though the theory of diffraction radiation has been discussed since 1960s, there are only a few experimental studies in recent years. The successful beam size measurement by optical diffraction radiation at CEBAF machine is a milestone: First of all, we have successfully demonstrated diffraction radiation as an effective nonintercepting diagnostics; Secondly, the simple linear relationship between the diffraction radiation image size and the actual beam size improves the reliability of ODR measurements; And, we measured the polarized components of diffraction radiation for the first time and I analyzed the contribution from edge radiation to diffraction radiation.

  16. Construction and performance of the ALICE Transition Radiation Detector

    Energy Technology Data Exchange (ETDEWEB)

    Emschermann, David

    2010-01-20

    The Transition Radiation Detector (TRD) has been designed to identify electrons in the pion dominated background of heavy-ions collisions. As electrons do not interact strongly, they allow to probe the early phase of the interaction. As trigger on high-p{sub t} e{sup +}e{sup -} pairs within 6.5 {mu}s after collision, the TRD can initiate the readout of the Time Projection Chamber (TPC). The TRD is composed of 18 super modules arranged in a barrel geometry in the central part of the ALICE detector. It offers almost 1.2 million readout channels on a total area of close to 700 m{sup 2}. The particle detection properties of the TRD depend crucially on details in the design of the cathode pad readout plane. The design parameters of the TRD readout pad plane are introduced and analysed regarding their physical properties. The noise patterns observed in the detector can be directly linked to the static pad capacitance distribution and corrected for it. A summary is then given of the TRD services infrastructure at CERN: a 70 kW low voltage system, a 1080 channel 2.5 kV high voltage setup and the Ethernet network serving more than 600 nodes. Two beam tests were conducted at the CERN PS accelerator in 2004 and 2007 using full sized TRD chambers from series production. Details on the setups are presented with particular emphasis on the custom tailored data acquisition systems. Finally the performance of the TRD is studied, focusing on the pion rejection capability and the excellent position resolution. (orig.)

  17. Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO{sub 2} fiber

    Energy Technology Data Exchange (ETDEWEB)

    Katsumata, Toru, E-mail: katsumat@toyo.jp; Morita, Kentaro; Komuro, Shuji; Aizawa, Hiroaki [Faculty of Science and Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585 (Japan)

    2014-08-15

    Visible light thermal radiation from SiO{sub 2} glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO{sub 2} fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900 K. Peak intensities of thermal radiations from rare-earth doped SiO{sub 2} fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO{sub 2} fibers are smaller than those from SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO{sub 2} are potentially applicable for the fiber-optic thermometry above 900 K.

  18. Radiation optic neuropathy and retinopathy with low dose (20 Gy radiation treatment

    Directory of Open Access Journals (Sweden)

    Crandall E. Peeler

    2016-10-01

    Conclusions and importance: Though cumulative radiation doses to the anterior visual pathway of less than 50 Gy are traditionally felt to be safe, it is important to consider not just the total exposure but also the size of individual fractions. The single-dose threshold for RON in proton beam treatment has yet to be defined. Our case suggests that fractions of less than 10 Gy should be delivered to minimize the risk of optic nerve injury.

  19. Passive radiation detection using optically active CMOS sensors

    Science.gov (United States)

    Dosiek, Luke; Schalk, Patrick D.

    2013-05-01

    Recently, there have been a number of small-scale and hobbyist successes in employing commodity CMOS-based camera sensors for radiation detection. For example, several smartphone applications initially developed for use in areas near the Fukushima nuclear disaster are capable of detecting radiation using a cell phone camera, provided opaque tape is placed over the lens. In all current useful implementations, it is required that the sensor not be exposed to visible light. We seek to build a system that does not have this restriction. While building such a system would require sophisticated signal processing, it would nevertheless provide great benefits. In addition to fulfilling their primary function of image capture, cameras would also be able to detect unknown radiation sources even when the danger is considered to be low or non-existent. By experimentally profiling the image artifacts generated by gamma ray and β particle impacts, algorithms are developed to identify the unique features of radiation exposure, while discarding optical interaction and thermal noise effects. Preliminary results focus on achieving this goal in a laboratory setting, without regard to integration time or computational complexity. However, future work will seek to address these additional issues.

  20. Laser-heating-based active optics for synchrotron radiation applications

    CERN Document Server

    Yang, Fugui; Zhang, Xiaowei

    2016-01-01

    Active optics has attracted considerable interest from researchers in synchrotron radiation facilities, because of its capacity for x-ray wavefront correction. Here, we report a novel and efficient technique for correcting or modulating a mirror surface profile based on laser-heating-induced thermal expansion. An experimental study of the characteristics of the surface thermal deformation response indicates that the power of a milliwatt laser yields a bump height as low as sub-nanometer scale, and that variation of the spot size modulates the response function width effectively. In addition, the capacity of the laser-heating technique for free-form surface modulation is demonstrated via a surface correction experiment. The developed method is a promising new approach towards effective x-ray active optics coupled with at-wavelength metrology techniques.

  1. Optical fiber transmission of high power excimer laser radiation.

    Science.gov (United States)

    Pini, R; Salimbeni, R; Vannini, M

    1987-10-01

    An experimental investigation of optical fiber transmission of high power excimer laser radiation is presented. Different types of commercially available UV fiber have been tested, measuring energy handling capabilities and transmission losses of short samples at the XeCl (308-nm) and KrF (249-nm) wavelengths by using a standard excimer laser. A power density dependent damage process has been observed over 1 GW/cm(2). Fiber losses due to different radii of curvature are also reported. Experimental results have been examined to evaluate the effectiveness of excimer laser transmission through optical fibers for such medical uses as laser angioplasty, including also a comparison between the use of KrF or XeCl emission lines for this purpose. Finally, optimum excimer laser characteristics to increase the energy coupling in fibers are discussed.

  2. Optical substrate materials for synchrotron radiation beam lines

    Science.gov (United States)

    Howells, Malcolm R.; Paquin, Roger A.

    1997-09-01

    We consider the materials choices available for making optical substrates for synchrotron radiation beam lines. We find that currently the optical surfaces can only be polished to the required finish in fused silica and other glasses, silicon, CVD silicon carbide, electroless nickel and 17-4 PH stainless steel. Substrates must therefore be made of one of these materials or of a metal that can be coated with electroless nickel. In the context of material choices for mirrors we explore the issues of dimensional stability, polishing, bending, cooling, and manufacturing strategy. We conclude that metals are best from an engineering and cost standpoint while the ceramics are best from a polishing standpoint. We then give discussions of specific materials as follows: silicon carbide, silicon, electroless nickel, GlidcopTM, aluminum, precipitation- hardening stainless steel, mild steel, invar and superinvar. Finally we summarize conclusions and propose ideas for further research.

  3. Radiation-hard/high-speed array-based optical engine

    Science.gov (United States)

    Gan, K. K.; Buchholz, P.; Heidbrink, S.; Kagan, H. P.; Kass, R. D.; Moore, J.; Smith, D. S.; Vogt, M.; Ziolkowski, M.

    2016-12-01

    We have designed and fabricated a compact array-based optical engine for transmitting data at 10 Gb/s. The device consists of a 4-channel ASIC driving a VCSEL (Vertical Cavity Surface Emitting Laser) array in an optical package. The ASIC is designed using only core transistors in a 65 nm CMOS process to enhance the radiation-hardness. The ASIC contains an 8-bit DAC to control the bias and modulation currents of the individual channels in the VCSEL array. The DAC settings are stored in SEU (single event upset) tolerant registers. Several devices were irradiated with 24 GeV/c protons and the performance of the devices is satisfactory after the irradiation.

  4. Optical and radiographical characterization of silica aerogel for Cherenkov radiator

    CERN Document Server

    Tabata, Makoto; Hatakeyama, Yoshikiyo; Kawai, Hideyuki; Morita, Takeshi; Nishikawa, Keiko

    2012-01-01

    We present optical and X-ray radiographical characterization of silica aerogels with refractive index from 1.05 to 1.07 for a Cherenkov radiator. A novel pin-drying method enables us to produce highly transparent hydrophobic aerogels with high refractive index by shrinking wet-gels. In order to investigate the uniformity in the density (i.e., refractive index) of an individual aerogel monolith, we use the laser Fraunhofer method, an X-ray absorption technique, and Cherenkov imaging by a ring imaging Cherenkov detector in a beam test. We observed an increase in density at the edge of the aerogel tiles, produced by pin-drying.

  5. First characterization of coherent optical vortices from harmonic undulator radiation.

    Science.gov (United States)

    Hemsing, E; Dunning, M; Hast, C; Raubenheimer, T; Xiang, Dao

    2014-09-26

    We describe the experimental generation and measurement of coherent light that carries orbital angular momentum from a relativistic electron beam radiating at the second harmonic of a helical undulator. The measured helical phase of the light is shown to be in agreement with predictions of the sign and magnitude of the phase singularity and is more than 2 orders of magnitude greater than the incoherent signal. Our setup demonstrates that such optical vortices can be produced in modern free-electron lasers in a simple afterburner arrangement for novel two-mode pump-probe experiments.

  6. High-current CW beam profile monitors using transition radiation at CEBAF

    Science.gov (United States)

    Piot, P.; Denard, J.-C.; Adderley, P.; Capek, K.; Feldl, E.

    1997-01-01

    One way of measuring the profile of CEBAF's low-emittance, high-power beam is to use the optical transition radiation (OTR) emitted from a thin foil surface when the electron beam passes through it. We present the design of a monitor using the forward OTR emitted from a 0.25-μm carbon foil. We believe that the monitor will resolve three main issues: i) whether the maximum temperature of the foil stays below the melting point, ii) whether the beam loss remains below 0.5%, in order not to trigger the machine protection system, and iii) whether the monitor resolution (unlike that of synchrotron radiation monitors) is better than the product λγ. It seems that the most serious limitation for CEBAF is the beam loss due to beam scattering. We present results from Keil's theory and simulations from the computer code GEANT as well as measurements with aluminum foils with a 45-MeV electron beam. We also present a measurement of a 3.2-GeV beam profile that is much smaller than λγ, supporting Rule and Fiorito's calculations of the OTR resolution limit due to diffraction.

  7. First-Order-Like Transition for Dispersive Optical Bistability

    Institute of Scientific and Technical Information of China (English)

    HE Ying; ZHU Shi-Qun

    2003-01-01

    The first-order-like phase transition (FOLT) in the dispersive optical bistability is investigated when the fluctuation in the incident light field is considered as colored noise. A unified colored-noise approximation is applied to obtain the steady state distribution (SSD) when either the intensity or phase fluctuations of the incident field are included in the system. For intensity fluctuations only, the curve of SSD is changed from single extreme to two extremes, and then to three extremes. The colored nature of the noise can reduce the fluctuation in the system. However, for phase fluctuations only, the FOLT is mainly induced by the colored nature of the noise. The curve of SSD is changed from single extreme to three extremes directly. There is no FOLT existing for white noise.

  8. Nanofocusing optics for synchrotron radiation made from polycrystalline diamond.

    Science.gov (United States)

    Fox, O J L; Alianelli, L; Malik, A M; Pape, I; May, P W; Sawhney, K J S

    2014-04-07

    Diamond possesses many extreme properties that make it an ideal material for fabricating nanofocusing x-ray optics. Refractive lenses made from diamond are able to focus x-ray radiation with high efficiency but without compromising the brilliance of the beam. Electron-beam lithography and deep reactive-ion etching of silicon substrates have been used in a transfer-molding technique to fabricate diamond optics with vertical and smooth sidewalls. Latest generation compound refractive lenses have seen an improvement in the quality and uniformity of the optical structures, resulting in an increase in their focusing ability. Synchrotron beamline tests of two recent lens arrays, corresponding to two different diamond morphologies, are described. Focal line-widths down to 210 nm, using a nanocrystalline diamond lens array and a beam energy of E = 11 keV, and 230 nm, using a microcrystalline diamond lens at E = 15 keV, have been measured using the Diamond Light Source Ltd. B16 beamline. This focusing prowess is combined with relatively high transmission through the lenses compared with silicon refractive designs and other diffractive optics.

  9. Tuning optical radiation for visual and nonvisual impact

    Science.gov (United States)

    Royer, Michael P.

    2011-12-01

    Spectral tuning---the allocation of radiant energy emitted by a lamp---is a fundamental element of illuminating engineering. Proper placement of optical radiation allows for reduced energy consumption, increased brightness perception, and improved color rendition. It can also result in lamps that have a greater impact on nonvisual human functions such as circadian rhythms, sleep, mood, and cognition. For an architectural lighting system, careful consideration must be given to all of these areas; recent advancements in understanding nonvisual photoreception must be balanced with the traditional emphasis on visual quality and energy efficiency. The three research projects described herein investigated spectral tuning by examining the effects of optical radiation or seeking ideal spectral power distributions. In all three cases, emphasis was placed on developing an architectural lighting system based on red, green, and blue (RGB) light emitting diodes (LEDs) that is capable of providing maximum stimulation to nonvisual systems while maintaining visual quality standards. In particular, the elderly were considered as a target population because they have an increased risk of developing disorders linked to illumination deficits. The three endeavors can be summarized as follows: Light Therapy for Seniors in Long-term Care AIM: To examine the effect of optical radiation on circadian rhythms, sleep, mood, and cognition for frail elderly in a long-term care environment. METHODOLOGY: A double-blind, placebo-controlled clinical trial of light therapy was conducted using circadian-effective short-wavelength (blue) optical radiation to treat a sample of residents recruited for participation without bias for existing medical diagnoses. KEY FINDINGS: Light therapy treatment improved cognitive functioning compared to placebo but no changes were detected in nighttime sleep statistics, reports of daytime sleepiness, circadian rhythms, or depression inventory parameters. Perceived

  10. Experimental Study on Fast Electrons Transport in Ultra-intense Laser Irradiated Solid Targets by Transition Radiation

    Science.gov (United States)

    Zhijian, Zheng; Guangcan, Wang; Yuqiu, Gu

    2008-11-01

    The experiment was performed with SILEX laser facility(Ti-saphhire) at LFRC in China. The SILEX parameter: wavelength 0.8μm, duration 35fs, output power 280TW, contrast 5*105, The focal spot φ10μm(F/1.7), intensity on target surface 1*10^19W/cm^2(F/3). The main diagnostic equipments are the electron spectrometer, OMA spectrometer, optical streak camera. Some experimental results are given: The spectrum of optical emission from rear surface is rather narrow around some particular frequencies(1φ, 2φ, 3φ), We ascribe and confirm that the spike-like spectral line that is coherent transition radiation; The coherent light is also seen on time-integrated image with ring-patter due to Weibel instability of the fast electron transport; Obtained experimental cure of target thickness vs OTR image intensity is relative to mean free path of fast electron; The measuring optical transition radiation(OTR) duration of 171ps much longer than 1ps duration of fast electron transport target, the possible explanation is that the OTR duration to be determined magnetic diffusion time.

  11. Demonstration of Coherent Terahertz Transition Radiation from Relativistic Laser-Solid Interactions

    Science.gov (United States)

    Liao, Guo-Qian; Li, Yu-Tong; Zhang, Yi-Hang; Liu, Hao; Ge, Xu-Lei; Yang, Su; Wei, Wen-Qing; Yuan, Xiao-Hui; Deng, Yan-Qing; Zhu, Bao-Jun; Zhang, Zhe; Wang, Wei-Min; Sheng, Zheng-Ming; Chen, Li-Ming; Lu, Xin; Ma, Jing-Long; Wang, Xuan; Zhang, Jie

    2016-05-01

    Coherent transition radiation in the terahertz (THz) region with energies of sub-mJ/pulse has been demonstrated by relativistic laser-driven electron beams crossing the solid-vacuum boundary. Targets including mass-limited foils and layered metal-plastic targets are used to verify the radiation mechanism and characterize the radiation properties. Observations of THz emissions as a function of target parameters agree well with the formation-zone and diffraction model of transition radiation. Particle-in-cell simulations also well reproduce the observed characteristics of THz emissions. The present THz transition radiation enables not only a potential tabletop brilliant THz source, but also a novel noninvasive diagnostic for fast electron generation and transport in laser-plasma interactions.

  12. Generation of linearly polarized resonant transition radiation X-ray beam

    Energy Technology Data Exchange (ETDEWEB)

    Yajima, Kazuaki; Awata, Takaaki; Ikeda, Mitsuharu; Ikeda, Kenichi; Yogo, Akifumi; Itoh, Akio; Imanishi, Nobutsugu [Kyoto Univ. (Japan). Dept. of Nuclear Engineering

    2000-03-01

    We have proposed a method to generate almost linearly polarized resonant transition radiation X rays by using a rectangular slit placed on an electron beam axis. Our calculation predicted that the linearity is 93.5% for the resonant transition radiation X-ray beam extracted through a slit of 0.5 mrad long and 0.2 mrad wide in case of 1-GeV electron beam irradiating a 7.5-{mu}m thick Kapton foil stack. (author)

  13. Artificial Optical Radiation photobiological hazards in arc welding.

    Science.gov (United States)

    Gourzoulidis, G A; Achtipis, A; Topalis, F V; Kazasidis, M E; Pantelis, D; Markoulis, A; Kappas, C; Bourousis, C A

    2016-08-01

    Occupational Health and Safety (OHS) is associated with crucial social, economic, cultural and technical issues. A highly specialized OHS sector deals with the photobiological hazards from artificial optical radiation (AOR), which is divided into visible light, UV and IR emitted during various activities and which is legally covered by European Directive 2006/25/EC. Among the enormous amount of sources emitting AOR, the most important non-coherent ones to consider for health effects to the whole optical range, are arcs created during metal welding. This survey presents the effort to assess the complicated exposure limits of the Directive in the controlled environment of a welding laboratory. Sensors covering the UV and blue light range were set to measure typical welding procedures reproduced in the laboratory. Initial results, apart from apparently justifying the use of Personal Protective Equipment (PPE) due to even subsecond overexposures measured, also set the basis to evaluate PPE's properties and support an integrated risk assessment of the complex welding environment. These results can also improve workers' and employer's information and training about radiation hazards, which is a crucial OHS demand.

  14. CCD imaging for optical tomography of gel radiation dosimeters.

    Science.gov (United States)

    Wolodzko, J G; Marsden, C; Appleby, A

    1999-11-01

    Several investigations have been carried out by a number of researchers over the past few years to evaluate the utility of imaging gel dosimeters for the three-dimensional measurement of radiation fields. These have been proposed to be of particular value in mapping radiation dose distributions associated with emerging and complex approaches to cancer treatment such as conformal (CRT), intensity modulated (IMRT), "gamma knife," and pencil beam radiotherapies. Imaging of the gels has been successfully accomplished with clinical MRI units and via laser-based optical scanning. However, neither of these methods is generally accessible to all potential users, limiting the broader study and implementation of this valuable tool. We report here the design, methodology, and results of a preliminary study carried out to evaluate the utility of a new, inexpensive, and simplified approach to tomographic imaging of gel radiation dosimeters. For the purpose of this initial investigation, an array of liquid scintillation vials was prepared, containing a ferrous sulphate xylenol orange (FSX) gelatin formulation. The FSX formulation undergoes a change in optical absorption characteristics following irradiation, and the resulting color change can be observed visually. The vials were irradiated individually to different doses. Three-dimensional imaging was accomplished by tomographic reconstruction from two-dimensional optical images acquired using a diffuse, fluorescent light source, a digital charge-coupled device camera, single-photon-emission-computed tomography software, and other simple components designed by the authors. The resulting transverse images were evaluated through a region-of-interest (ROI) analysis to obtain the average change in image density in each vial as a function of radiation dose. These measured ROI values were subjected to a linear regression analysis to fit them to a straight line, and to determine the goodness of fit. Results from multiple imaging trials

  15. Optical characterization of OLED emitter properties by radiation pattern analyses

    Energy Technology Data Exchange (ETDEWEB)

    Flaemmich, Michael

    2011-09-08

    Researches in both, academia and industry are investigating optical loss channels in OLED layered systems by means of optical simulation tools in order to derive promising concepts for a further enhancement of the overall device performance. Besides other factors, the prospects of success of such optimization strategies rely severely on the credibility of the optical input data. The present thesis provides a guideline to measure the active optical properties of OLED emitter materials in situ by radiation pattern analyses. Reliable and widely applicable methods are introduced to determine the internal electroluminescence spectrum, the profile of the emission zone, the dipole emitter orientation, and the internal luminescence quantum efficiency of emissive materials from the optical far field emission of OLEDs in electrical operation. The proposed characterization procedures are applied to sets of OLEDs containing both, fluorescent polymeric materials as well as phosphorescent small-molecular emitters, respectively. On the one hand, quite expected results are obtained. On the other hand, several novel and truly surprising results are found. Most importantly, this thesis contains the first report of a non-isotropic, mainly parallel emitter orientation in a phosphorescent small-molecular guest-host system (Ir(MDQ)2(acac) in a-NPD). Due to the latter result, emitter orientation based optimization of phosphorescent OLEDs seems to be within reach. Since parallel dipoles emit preferably into air, the utilization of smart emissive materials with advantageous molecular orientation is capable to boost the efficiency of phosphorescent OLEDs by 50%. Materials design, the influence of the matrix material and the substrate, as well as film deposition conditions are just a few parameters that need to be studied further in order to exploit the huge potential of the dipole emitter orientation in phosphorescent OLEDs.

  16. Characterization of optical transitions of Eu3+ in lanthanum oxychloride nanophosphor

    Institute of Scientific and Technical Information of China (English)

    A. Choubey; S. Som; M. Biswas; S.K. Sharma

    2011-01-01

    This paper presented the studies on the optical properties and calculation of spectral parameters of europium doped lanthanum oxychloride nanophosphor for their possible applications in optoelectronic devices. The compound was doped with 0.1 mol% Eu3+ ions. The X-ray diffraction study of prepared sample suggested the tetragonal structure with particle size in the range of 18-21 nm. The photoluminescence (PL) emission spectra showed the bright emission in orange-red region from 580 to 630 nm. The most intense emission peak at 621 nmwas due to transition 5D0→7F2 in energy levels of Eu3+ ions. The spectral parameters were calculated from the absorption and emission spectra using Judd-Ofelt intensity parameters. The calculated values of the oscillator strength corresponding to the three transitions 7F1→2D1, 7F1→SD2 and 7F0→5D2 observed at 535, 472 and 465 nm in absorption spectra were 0.30×10-6, 1.36×106 and 0.63×10-6, respectively. The value of transi tion probability (A), stimulated emission cross-sect1on (σEP) and radiative lifetime (τrad) corresponding to 621 nm emission peak (transition 5D0→7F2) were 308 s-1, 1.22× 10-21 cm2 and 3.24×10-3 s, respectively.

  17. Measurements of the spectrum and energy dependence of X-ray transition radiation

    Science.gov (United States)

    Cherry, M. L.

    1978-01-01

    The results of experiments designed to test the theory of X-ray transition radiation and to verify the predicted dependence of the characteristic features of the radiation on the radiator dimensions are presented. The X-ray frequency spectrum produced by 5- to 9-GeV electrons over the range 4 to 30 keV was measured with a calibrated single-crystal Bragg spectrometer, and at frequencies up to 100 keV with an NaI scintillator. The interference pattern in the spectrum and the hardening of the radiation with increasing foil thickness are clearly observed. The energy dependence of the total transition-radiation intensity was studied using a radiator with large dimensions designed to yield energy-dependent signals at very high particle energies, up to E/mc-squared approximately equal to 100,000. The results are in good agreement with the theoretical predictions.

  18. A Concept for z-Dependent Microbunching Measurements with Coherent X-ray Transition Radiation in a SASE FEL

    CERN Document Server

    Lumpkin, Alex H

    2004-01-01

    Previously, measurements in the visible to VUV regimes of z-dependent microbunching in a self-amplified spontaneous emission (SASE) free-electron laser (FEL) have provided important information about the fundamental mechanisms. In those experiments a thin metal foil was used to block the more intense SASE radiation and to generate coherent optical transition radiation (COTR) as one source in a two-foil interferometer. However, for the proposed Linac Coherent Light Source (LCLS), the intense SASE emission is either too strongly transmitted at 1.5 angstroms or the needed foil thickness for blocking scatters the electron beam too much. Since coherent x-ray transition radiation (CXTR) is emitted in an annulus with opening angle 1/γ = 36 µrad for 14.09-GeV electrons, one could use a thin foil or foil stack to generate the XTR and CXTR and an annular crystal to wavelength sort the radiation. The combined selectivity will favor the CXTR over SASE by about eight orders of magnitude. Time-dependent GINGER si...

  19. Optical radiation measurements for photovoltaic applications: instrumentation uncertainty and performance

    Science.gov (United States)

    Myers, Daryl R.; Reda, Ibrahim; Wilcox, Stephen; Andreas, Afshin

    2004-11-01

    Evaluating the performance of photovoltaic (PV) devices in the laboratory and in the field requires accurate knowledge of the optical radiation stimulating the devices. We briefly describe the radiometric instrumentation used for characterizing broadband and spectral irradiance for PV applications. Spectral radiometric measurement systems are used to characterize solar simulators (continuous and pulsed, or flash sources) and natural sunlight. Broadband radiometers (pyranometers and pyrheliometers) are used to assess solar resources for renewable applications and develop and validate broadband solar radiation models for estimating system performance. We describe the sources and magnitudes of uncertainty associated with calibrations and measuremens using these instruments. The basic calibration and measurement uncertainty associated with this instrumentaion are based on the guidlines described in the International Standards Organization (ISO) and Bureau INternationale des Poids et Mesures (BIPM) Guide to Uncertainty in Measurement. The additional contributions to uncertainty arising from the uncertainty in characterization functions and correction schemes are discussed and ilustrated. Finally, empirical comparisons of several solar radiometer instrumentation sets illustrate that the best measurement accuracy for broadband radiation is on the order of 3%, and spectrally dependent uncertainty for spectroradiometer systems range from 4% in the visible to 8% to 10% in the ultraviolet and infrared.

  20. Hybrid formulation of radiation transport in optically thick divertor plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Rosato, J.; Marandet, Y.; Bufferand, H.; Stamm, R. [PIIM, UMR 7345 Aix-Marseille Universite / CNRS, Centre de St-Jerome, Marseille (France); Reiter, D. [IEK-4 Plasmaphysik, Forschungszentrum Juelich GmbH, Juelich (Germany)

    2016-08-15

    Kinetic Monte Carlo simulations of coupled atom-radiation transport in optically thick divertor plasmas can be computationally very demanding, in particular in ITER relevant conditions or even larger devices, e.g. for power plant divertor studies. At high (∝ 10{sup 15} cm{sup -3}) atomic densities, it can be shown that sufficiently large divertors behave in certain areas like a black body near the first resonance line of hydrogen (Lyman α). This suggests that, at least in part, the use of continuum model (radiation hydrodynamics) can be sufficiently accurate, while being less time consuming. In this work, we report on the development of a hybrid model devoted to switch automatically between a kinetic and a continuum description according to the plasma conditions. Calculations of the photo-excitation rate in a homogeneous slab are performed as an illustration. The outlined hybrid concept might be also applicable to neutral atom transport, due to mathematical analogy of transport equations for neutrals and radiation. (copyright 2016 The Authors. Contributions to Plasma Physics published by Wiley-VCH Verlag GmbH and Co. KGaA Weinheim. This)

  1. Cancellation of coherent synchrotron radiation kicks with optics balance.

    Science.gov (United States)

    Di Mitri, S; Cornacchia, M; Spampinati, S

    2013-01-04

    Minimizing transverse emittance is essential in linear accelerators designed to deliver very high brightness electron beams. Emission of coherent synchrotron radiation (CSR), as a contributing factor to emittance degradation, is an important phenomenon to this respect. A manner in which to cancel this perturbation by imposing certain symmetric conditions on the electron transport system has been suggested.We first expand on this idea by quantitatively relating the beam Courant-Snyder parameters to the emittance growth and by providing a general scheme of CSR suppression with asymmetric optics, provided it is properly balanced along the line. We present the first experimental evidence of this cancellation with the resultant optics balance of multiple CSR kicks: the transverse emittance of a 500 pC, sub-picosecond, high brightness electron beam is being preserved after the passage through the achromatic transfer line of the FERMI@Elettra free electron laser, and emittance growth is observed when the optics balance is intentionally broken. We finally show the agreement between the theoretical model and the experimental results. This study holds the promise of compact dispersive lines with relatively large bending angles, thus reducing costs for future electron facilities.

  2. Inhomogeneous broadening of optical transitions of 87Rb atoms in an optical nanofiber trap

    CERN Document Server

    Lee, J; Hoffman, J E; Orozco, L A; Rolston, S L

    2014-01-01

    We experimentally demonstrate optical trapping of 87Rb atoms using a two-color evanescent field around an optical nanofiber. In our trapping geometry, a blue-detuned traveling wave whose polarization is nearly parallel to the polarization of a red-detuned standing wave produce significant vector light shifts that lead to broadening of the absorption profile of a near-resonant beam at the trapping site. A model that includes scalar, vector, and tensor light shifts of the probe transition $5S_{1/2}$-$5P_{3/2}$ from the trapping beams; weighted by the temperature-dependent position of the atoms in the trap qualitatively describe the observed asymmetric profile, and explained differences with previous experiments that used Cs atoms. The model provides a consistent way to extract the number of atoms in the trap.

  3. ATLAS Transition Radiation Tracker (TRT) Electronics Operation Experience at High Rates

    CERN Document Server

    Mistry, Khilesh; The ATLAS collaboration

    2015-01-01

    The ATLAS Transition Radiation Tracker (TRT) is a gaseous drift tube tracker which combines continuous tracking capabilities with particle identification based on transition radiation. The TRT Data Acquisition system uses custom front-end ASICs and boards for trigger and timing control as well as data read-out. To prepare for LHC run 2, changes were made to support the increased ATLAS trigger rate of 100 kHz, increased TRT occupancy caused by higher LHC luminosity, and gas mixture changes in some TRT straw tubes. Radiation studies were performed following an observed gain loss at the front-end during the 2012 run.

  4. A study on the real-time radiation dosimetry measurement system based on optically stimulated luminescence

    Institute of Scientific and Technical Information of China (English)

    LIU Yan-Ping; CHEN Zhao-Yang; BA Wei-Zhen; FAN Yan-Wei; DU Yan-Zhao; PAN Shi-Lie; GUO Qi

    2008-01-01

    The optically stimulated luminescent (OSL) radiation dosimeter technically surveys a wide dynamic measurement range and a high sensitivity.Optical fiber dosimeters provide capability for remote monitoring of the radiation in the locations which are difficult-to-acoess and hazardous.In addition.optical fiber dosimeters are immune to electrical and radio-frequency interference.In this paper,a novel remote optical fiber radiation dosimeter is described.The optical fiber dosimeter takes advantage of the charge trapping materials CaS:Ce, Sm that exhibit OSL.The measuring range of the dosimeter is from 0.1 to 100 Gy.The equipment is relatively simple and small in size,and has low power consumption.This device is suitable for measuring the space radiation dose and also can be used in high radiation dose condition and other dangerous radiation occasions.

  5. Edge-core interplay in transition to radiative improved mode

    Energy Technology Data Exchange (ETDEWEB)

    Tokar, M.Z.; Unterberg, B. [Association Euratom-Forschungszentrum Juelich GmbH (Germany). Inst. fuer Plasmaphysik; Jaspers, R. [Associatie Euratom-FOM, Nieuwegein (Netherlands). FOM-Instituut voor Plasmafysica

    1998-05-01

    A new radiative improved-mode (RI-mode) has been found in TEXTOR-94 in experiments aimed to prove feasibility of the concept of a radiating plasma mantle under quasi-stationary conditions of auxiliary heated discharges. By puffing of neon, silane or argon, up to 95% of the total input power can be radiated without detachment of the plasma from the limiter. Contrary to the common belief, the high edge radiation level does not lead to a degradation of the energy confinement, but can cause a substantial improvement with an appropriate heating and operational scenario. Investigation of the mechanisms of the confinement improvement in the RI-mode by means of predictive transport modeling is the aim of this contribution. (orig.) 6 refs.

  6. Emission Angles for Soft X-Ray Coherent Transition Radiation.

    Science.gov (United States)

    1987-09-01

    School is used to study radiation effects and damage, radiation characteristics and nuclear structure. The LINAC is capable of operating from...Private communication.) 43 ........ 11. "PCD Linear Image Sensors (S3201 Series)," HAMAMATSU Technical Data Sheet, July 1985. 12. "Application of Reticon ...Photodiode Arrays as Electron and X-Ray Detectors," EG&G Reticon Application Notes No. 101, 1975. 13. Chu, A.N., M.A. Piestrup and R.H. Pantell

  7. Temperature dependence of radiation-induced attenuation of optical fibers

    Institute of Scientific and Technical Information of China (English)

    Jingming Song; Jianhua Guo; Xueqin Wang; Jing Jin

    2012-01-01

    We investigate the temperature dependence of radiation-induced attenuation (RIA) at 1 310 nm for a Ge/P co-doped fiber after a steady-state γ-ray irradiation.A γ irradiation facility 60Co source is used to irradiate the fiber at a dose rate of 0.5 Gy/min,satisfying a total dose of 100 Gy.The test temperature ranges from-40 to 60 ℃ by 20 ℃,and the RIA of the fiber is obtained using a power measuring device.The experimental result demonstrates that RIA exhibits a steady,monotonic,and remarkable temperature dependence after approximately 48 h of accelerated annealing at 70 ℃.The optical fiber irradiated with a high dose and annealed sufficiently can be used as a temperature sensor.

  8. Observation of coherent transition radiation using relativistic pico second electron pulse

    Energy Technology Data Exchange (ETDEWEB)

    Jones, C.R.; Kosai, H.; Dutt, J.M. [North Carolina Central Univ., Durham, NC (United States)

    1995-12-31

    When an electron beams passes through boundaries of two different media with different dielectric constants, it generates radiation. The radiation emitted by the prebunched electron beam becomes coherent if the size of the bunch is smaller than the wavelength. Therefore, transition radiation can be considered as a possible broad band radiation source as well as a probe to the pico second and sub picosecond electron beam profiles. Using 1.2 MeV, 200 mA, macropulse electron beam, transition radiation was generated. The electron gun consists of 2.856 GHz Klystron, thermionic cathode. The emitted electron beam was bunched by passing through an alpha magnet. As a result of the combination, a pico second pulse (1.2 MeV, up to 80 A micropulse) was obtained. Experimental results, comparisons with the theory, and simulated electron beam profiles will be presented.

  9. OPTICAL DIFFERENCE FREQUENCY GENERATION OF FAR INFRARED RADIATION

    Energy Technology Data Exchange (ETDEWEB)

    Morris, J.R.

    1977-07-01

    Three investigations of difference frequency generation (DFG) of far-infrared radiation by optical mixing are described: a theory of DFG by monochromatic, focused Gaussian pump laser beams, a theory of DFG by a picosecond pump laser pulse, and an experiment using ruby-pumped dye lasers. First, the theory of far-infrared generation by optical mixing of monochromatic, focused Gaussian beams in a uniaxial crystal is developed, taking into account the effects of diffraction, absorption, double refraction, and multiple reflections and total reflection at the boundary surfaces. (Reflection and transmission coefficients of a uniaxial crystal slab are derived by a new matrix technique.) Results of numerical calculations are presented. Focusing the pump beams appreciably enhances the far-infrared output despite the strong far-infrared diffraction. In a 1-cm long crystal, the optimum focal spot size is approximately equal to or smaller than the far-infrared wavelength for output frequencies less than 100 cm{sup -1}. Double refraction of the pump beams is relatively unimportant. Both far-infrared absorption and boundary reflections have major effects on the far-infrared output and its angular distribution. The former is often the factor which limits the output power. We show that a simple model treating the nonlinear polarization as a constant lie-radius Gaussian distribution of radiating dipoles adequately describes the effect of pump-beam focusing. We also compare the results of our calculations with those for second-harmonic generation. Second, a theoretical calculation of far-infrared power spectra generated by picosecond pulses in a nonlinear crystal is developed. The results are illustrated with two practical examples: LiNbO{sub 3} slabs oriented for rectification of the optical e-ray and for beating of the optical o-ray with the optical e-ray. The former is phase matched at 0 cm{sup -1}; the latter, at both the forward-(FCPM) and backward-collinear phase

  10. Convection and radiation effects in hollow, compound optical fibers

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, J.I. [Room I-320-D, ETS Ingenieros Industriales, Universidad de Malaga, Plaza El Ejido, s/n, 29013 Malaga (Spain)

    2005-09-01

    A coupled model for the study of hollow, compound optical fiber drawing processes that accounts for the heat transfer in the preform and fiber and for the motion of the gases surrounding the preform and fiber by means of two-dimensional equations, employs a net radiative model for the radiative heat exchanges amongst the preform, fiber, irises and furnace walls, and uses asymptotic one-dimensional equations for the geometry, axial velocity component and temperature along the fiber for small Biot numbers is presented. It is shown that the coupled model predicts that radiative heat exchanges are about three times larger than forced convection effects, and free convection is not important. It is also shown that the fiber's geometry, axial velocity and temperature predicted by the coupled model are in remarkable good agreement with those obtained with only the one-dimensional model for hollow, compound fibers using a properly chosen constant Biot number. The results of the one-dimensional model for hollow, compound fibers show that, as the heat transfer losses from the fiber increase, the fiber's dynamic viscosity increases, the fiber exhibits a strong necking phenomenon and the fiber's axial velocity increases rapidly from its value at the die's exit to a constant value downstream and then remains constant. For the boundary conditions considered in this paper, it is shown that the activation energies of the viscosity laws for the inner and outer materials of the hollow, compound fiber do not have very strong effects on the fiber's geometry, axial velocity component and temperature, whereas the fiber's solidification point moves towards the die as the thermal Peclet number is decreased. It is also shown that the pre-exponential factor and activation energy of the dynamic viscosity law do not play a key role in determining the fiber's geometry and temperature for the conditions analyzed in this paper. (authors)

  11. Ultraviolet radiation and bio-optics in Crater Lake, Oregon

    Science.gov (United States)

    Hargreaves, B.R.; Girdner, S.F.; Buktenica, M.W.; Collier, R.W.; Urbach, E.; Larson, G.L.

    2007-01-01

    Crater Lake, Oregon, is a mid-latitude caldera lake famous for its depth (594 m) and blue color. Recent underwater spectral measurements of solar radiation (300-800 nm) support earlier observations of unusual transparency and extend these to UV-B wavelengths. New data suggest that penetration of solar UVR into Crater Lake has a significant ecological impact. Evidence includes a correlation between water column chlorophyll-a and stratospheric ozone since 1984, the scarcity of organisms in the upper water column, and apparent UV screening pigments in phytoplankton that vary with depth. The lowest UV-B diffuse attenuation coefficients (K d,320) were similar to those reported for the clearest natural waters elsewhere, and were lower than estimates for pure water published in 1981. Optical proxies for UVR attenuation were correlated with chlorophyll-a concentration (0-30 m) during typical dry summer months from 1984 to 2002. Using all proxies and measurements of UV transparency, decadal and longer cycles were apparent but no long-term trend since the first optical measurement in 1896. ?? 2007 Springer Science+Business Media B.V.

  12. ALL-OPTICAL CONTROL OF THZ RADIATION IN PARALLEL PLATE WAVEGUIDES

    DEFF Research Database (Denmark)

    2010-01-01

    The invention relates to control of THz radiation in parallel plate waveguides (PPWG) by forming components in the waveguide by use of optical radiation pulses. Patterns of excited regions induced in the PPWG by an optical excitation pulses changes the electromagnetic properties of the waveguide...... medium in the THz regime, thereby forming transient passive and active components for controlling THz radiation signals. The excitation can be generation of free charge carriers in a semiconductor material in the PPWG, to create metallic regions that form mirrors, lenses or photonic crystal structures......-on-a-chip applications. The optical and THz radiation can be ultrashort pulses with picosecond or femtosecond pulse durations. L...

  13. Diffusion tensor imaging detects rarefaction of optic radiation in glaucoma patients.

    Science.gov (United States)

    Engelhorn, Tobias; Michelson, Georg; Waerntges, Simone; Struffert, Tobias; Haider, Sultan; Doerfler, Arnd

    2011-06-01

    Diffusion tensor imaging (DTI) can depict rarefaction of the optical fibres. Hence, we applied DTI to assess pathological changes of the optic radiation in glaucoma patients. Fifty glaucoma patients and 50 healthy age-matched controls were examined by a 3T high-field magnetic resonance scanner. Fiber tracts were volume rendered using a semiquantitative approach to assess rarefaction and results were correlated with the extent of optic nerve atrophy and reduced spatial-temporal contrast sensitivity of the retina using established ophthalmological examinations. Twenty-two glaucoma patients (44%) showed significant rarefaction of the optic radiation: the volume was reduced to 67 ± 16% compared with controls. Hereby, the glaucomatous optic nerve atrophy stage correlated with the presence of DTI-derived rarefied optic radiation (Kendall tau-b 0.272, P = .016). Aside, cerebral microangiopathy affecting the optic radiation was significantly higher among glaucoma patients compared to controls (10 patients compared with 2 patients, P < .05). In patients with glaucomatous optic nerve atrophy, there is anterograde and-most likely because of microangiopathic lesions within the optic radiation-retrograde transneuronal rarefaction of the optic radiation that can be assessed in vivo using DTI with good correlation to established ophthalmological examinations. Copyright © 2011 AUR. Published by Elsevier Inc. All rights reserved.

  14. Progress on Radiative Transition Probabilities in Neutral Cerium

    Science.gov (United States)

    Curry, J. J.

    2009-10-01

    Cerium is a rare-earth atom that is currently used in energy-efficient metal-halide lamps because of its rich visible emission spectrum. More than 20,000 lines have been observed and classified for neutral cerium in the wavelength range of 340 nm to 1 μm (Bill Martin, unpublished). We recently derived more than 500 absolute transition probabilities from existing experimental data (J. Phys. D: Appl. Phys. 2009). Lawler and Den Hartog at the University of Wisconsin have made measurements that are expected to produce a few thousand transition probabilities. These advances, however, leave the data situation far short of what is needed to simulate an accurate global emission spectrum in numerical models of metal-halide lamps containing cerium. One possibility for closing this gap is through atomic structure calculations. Although it may be difficult for calculations to match the accuracy of measurements for any given transition, the global spectral distribution produced with calculated transition probabilities may still be satisfactory. For such a large number of lines, calculations may be the only realistic way to produce a reasonably complete set of data. We will discuss our recent atomic structure calculations of neutral cerium with the Cowan code based on a parametric fit of calculated energy level values to experimental values.

  15. Acoustical and optical radiation pressure and the development of single beam acoustical tweezers

    Science.gov (United States)

    Thomas, Jean-Louis; Marchiano, Régis; Baresch, Diego

    2017-07-01

    Studies on radiation pressure in acoustics and optics have enriched one another and have a long common history. Acoustic radiation pressure is used for metrology, levitation, particle trapping and actuation. However, the dexterity and selectivity of single-beam optical tweezers are still to be matched with acoustical devices. Optical tweezers can trap, move and position micron size particles, biological samples or even atoms with subnanometer accuracy in three dimensions. One limitation of optical tweezers is the weak force that can be applied without thermal damage due to optical absorption. Acoustical tweezers overcome this limitation since the radiation pressure scales as the field intensity divided by the speed of propagation of the wave. However, the feasibility of single beam acoustical tweezers was demonstrated only recently. In this paper, we propose a historical review of the strong similarities but also the specificities of acoustical and optical radiation pressures, from the expression of the force to the development of single-beam acoustical tweezers.

  16. Lack of radiation optic neuropathy in 72 patients treated for pituitary adenoma

    NARCIS (Netherlands)

    van den Bergh, ACM; Dullaart, RPF; van der Vliet, AM; Szabo, BG; ter Weeme, CA; Pott, JWR

    The incidence of radiation optic neuropathy (RON) after external photon beam radiation therapy for nonfunctioning pituitary adenoma (NFA) is not well-studied. Retrospective review of ophthalmological and imaging data in 72 patients with NFA treated between 1985 and 1998 with external beam radiation

  17. Multimode mean-field model for the quantum phase transition of a Bose-Einstein condensate in an optical resonator

    Science.gov (United States)

    Kónya, G.; Szirmai, G.; Domokos, P.

    2011-11-01

    We develop a mean-field model describing the Hamiltonian interaction of ultracold atoms and the optical field in a cavity. The Bose-Einstein condensate is properly defined by means of a grand-canonical approach. The model is efficient because only the relevant excitation modes are taken into account. However, the model goes beyond the two-mode subspace necessary to describe the self-organization quantum phase transition observed recently. We calculate all the second-order correlations of the coupled atom field and radiation field hybrid bosonic system, including the entanglement between the two types of fields.

  18. Multimode mean-field model for the quantum phase transition of a Bose-Einstein condensate in an optical resonator

    CERN Document Server

    Konya, G; Domokos, P

    2011-01-01

    We develop a mean-field model describing the Hamiltonian interaction of ultracold atoms and the optical field in a cavity. The Bose-Einstein condensate is properly defined by means of a grand-canonical approach. The model is efficient because only the relevant excitation modes are taken into account. However, the model goes beyond the two-mode subspace necessary to describe the self-organization quantum phase transition observed recently. We calculate all the second-order correlations of the coupled atom field and radiation field hybrid bosonic system, including the entanglement between the two types of fields.

  19. Calibrated, multiband radiometric measurements of the optical radiation from lightning

    Science.gov (United States)

    Quick, Mason G.

    Calibrated, multiband radiometric measurements of the optical radiation emitted by rocket-triggered lightning (RTL) have been made in the ultraviolet (UV, 200-360 nm), the visible and near infrared (VNIR, 400-1000 nm), and the long wave infrared (LWIR, 8-12 microm) spectral bands. Measurements were recorded from a distance of 198 m at the University of Florida International Center for Lightning Research and Testing (ICLRT) during the summers of 2011 and 2012. The ICLRT provided time-correlated measurements of the current at the base of the RTL channels. Following the onset of a return stroke, the dominant mechanism for the initial rise of the UV and VNIR waveforms was the geometrical growth of the channel in the field-of-view of the sensors. The UV emissions peaked about 0.7 micros after the current peak, with a peak spectral power emitted by the source per unit length of channel of 10 +/- 7 kW/(nm-m) in the UV. The VNIR emissions peaked 0.9 micros after the current peak, with a spectral power of at 7 +/- 4 kW/(nm-m). The LWIR emissions peaked 30-50 micros after the current peak, and the mean peak spectral power was 940 +/- 380 mW/(nm-m), a value that is about 4 orders of magnitude lower than the other spectral band emissions. In some returns strokes the LWIR peak coincides with a secondary maximum in the VNIR band that occurs during a steady decrease in channel current. Examples of the optical waveforms in each spectral band are shown as a function of time and are discussed in the context of the current measured at the channel base. Source power estimates in the VNIR band have a mean and standard deviation of 2.5 +/- 2.2 MW/m and are in excellent agreement with similar estimates of the emission from natural subsequent strokes that remain in a pre-existing channel which have a mean and standard deviation of 2.3 +/- 3.4 MW/m. The peak optical power emitted by RTL in the UV and VNIR bands are observed to be proportional to the square of the peak current at the

  20. A transition radiation detector for RHIC featuring accurate tracking and dE/dx particle identification

    Energy Technology Data Exchange (ETDEWEB)

    O`Brien, E.; Lissauer, D.; McCorkle, S.; Polychronakos, V.; Takai, H. [Brookhaven National Lab., Upton, NY (United States); Chi, C.Y.; Nagamiya, S.; Sippach, W.; Toy, M.; Wang, D.; Wang, Y.F.; Wiggins, C.; Willis, W. [Columbia Univ., New York, NY (United States); Cherniatin, V.; Dolgoshein, B. [Moscow Institute of Physics and Engineering, (Russian Federation); Bennett, M.; Chikanian, A.; Kumar, S.; Mitchell, J.T.; Pope, K. [Yale Univ., New Haven, CT (United States)

    1991-12-31

    We describe the results of a test ran involving a Transition Radiation Detector that can both distinguish electrons from pions which momenta greater titan 0.7 GeV/c and simultaneously track particles passing through the detector. The particle identification is accomplished through a combination of the detection of Transition Radiation from the electron and the differences in electron and pion energy loss (dE/dx) in the detector. The dE/dx particle separation is most, efficient below 2 GeV/c while particle ID utilizing Transition Radiation effective above 1.5 GeV/c. Combined, the electron-pion separation is-better than 5 {times} 10{sup 2}. The single-wire, track-position resolution for the TRD is {approximately}230 {mu}m.

  1. A transition radiation detector which features accurate tracking and dE/dx particle identification

    Energy Technology Data Exchange (ETDEWEB)

    O`Brien, E.; Lissauer, D.; McCorkle, S.; Polychronakos, V.; Takai, H. [Brookhaven National Lab., Upton, NY (United States); Chi, C.Y.; Nagamiya, S.; Sippach, W.; Toy, M.; Wang, D.; Wang, Y.F.; Wiggins, C.; Willis, W. [Columbia Univ., New York, NY (United States); Cherniatin, V.; Dolgoshein, B. [Moscow Inst. of Physics and Engineering, Moscow (Russia Federation); Bennett, M.; Chikanian, A.; Kumar, S.; Mitchell, J.T.; Pope, K. [Yale Univ., New Haven, CT (United States)

    1991-12-31

    We describe the results of a test run involving a Transition Radiation Detector that can both distinguish electrons from pions with momenta greater than 0.7 GeV/c and simultaneously track particles passing through the detector. The particle identification is accomplished through a combination of the detection of Transition Radiation from the electron and the differences in electron and pion energy loss (dE/dx) in the detector. The dE/dx particle separation is most efficient below 2 GeV/c while particle ID utilizing Transition Radiation is effective above 1.5 GeV/c. Combined, the electron-pion separation is better than 5 {times} l0{sup 2}. The single-wire, track-position resolution for the TRD is {approximately}230{mu}m.

  2. A transition radiation detector which features accurate tracking and dE/dx particle identification

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, E.; Lissauer, D.; McCorkle, S.; Polychronakos, V.; Takai, H. (Brookhaven National Lab., Upton, NY (United States)); Chi, C.Y.; Nagamiya, S.; Sippach, W.; Toy, M.; Wang, D.; Wang, Y.F.; Wiggins, C.; Willis, W. (Columbia Univ., New York, NY (United States)); Cherniatin, V.; Dolgoshein, B. (Moscow Inst. of Physics and Engineering (Russian Federation)); Bennett, M.; Chikanian, A.; Kumar, S.; Mitchell, J.T.; Pope, K. (Yale Univ., New Haven, CT (United States))

    1993-04-01

    The authors describe the results of a test run involving a Transition Radiation Detector that can both distinguish electrons from pions with momenta greater than 0.7 GeV/c and simultaneously track particles passing through the detector. The particle identification is accomplished through a combination of the detection of Transition Radiation from the electron and the differences in electron and pion energy loss (dE/dx) in the detector. The dE/dx particle separation is most efficient below 2 GeV/c while particle ID utilizing Transition Radiation is effective above 1.5 GeV/c. Combined, the electron-pion separation is better than 5 x 10[sup 2]. The single-wire, track-position resolution for the TRD is [approximately] [mu]m.

  3. A novel DC Magnetron sputtering facility for space research and synchrotron radiation optics

    DEFF Research Database (Denmark)

    Hussain, A.M.; Christensen, Finn Erland; Pareschi, G.;

    1998-01-01

    A new DC magnetron sputtering facility has been build up at the Danish Space Research Institute (DSRI), specially designed to enable uniform coatings of large area curved optics, such as Wolter-I mirror optics used in space telescopes and curved optics used in synchrotron radiation facilities...

  4. Predictors of Psychosocial Adjustment During the Post-Radiation Treatment Transition

    OpenAIRE

    Mazanec, Susan; Daly, Barbara J.; Douglas, Sara; Musil, Carol

    2010-01-01

    The aim of this study was to examine the role of cognitive appraisal in predicting psychosocial adjustment during the post-radiation treatment transition. A predictive correlational design was used in a convenience sample of 80 patients with breast, lung, and prostate cancer who were receiving radiation therapy. Two weeks prior to completion of treatment, subjects completed instruments to measure symptom distress, uncertainty, cognitive appraisal, social support and self-efficacy for coping. ...

  5. Formation region effects in transition radiation, bremsstrahlung, and ionization loss of ultrarelativistic electrons

    Directory of Open Access Journals (Sweden)

    S. V. Trofymenko

    2016-11-01

    Full Text Available The processes of transition radiation and bremsstrahlung by an ultrarelativistic electron as well as the effect of transition radiation influence upon the electron ionization loss in thin layer of substance are theoretically investigated in the case when radiation formation region has macroscopically large size. Special attention is drawn to transition radiation (TR generated during the traversal of thin metallic plate by the electron previously deflected from its initial direction of motion. In this case TR characteristics are calculated for realistic (circular shape of the electron deflection trajectory. The difference of such characteristics under certain conditions from the ones obtained previously with the use of approximation of anglelike shape of the electron trajectory (instant deflection is shown. The problem of measurement of bremsstrahlung characteristics in the prewave zone is investigated. The expressions defining the measured radiation distribution for arbitrary values of the size and the position of the detector used for radiation registration are derived. The problem of TR influence upon the electron ionization loss in thin plate and in a system of two plates is discussed. The proposal for experimental investigation of such effect is formulated.

  6. Formation region effects in transition radiation, bremsstrahlung, and ionization loss of ultrarelativistic electrons

    Science.gov (United States)

    Trofymenko, S. V.; Shul'ga, N. F.

    2016-11-01

    The processes of transition radiation and bremsstrahlung by an ultrarelativistic electron as well as the effect of transition radiation influence upon the electron ionization loss in thin layer of substance are theoretically investigated in the case when radiation formation region has macroscopically large size. Special attention is drawn to transition radiation (TR) generated during the traversal of thin metallic plate by the electron previously deflected from its initial direction of motion. In this case TR characteristics are calculated for realistic (circular) shape of the electron deflection trajectory. The difference of such characteristics under certain conditions from the ones obtained previously with the use of approximation of anglelike shape of the electron trajectory (instant deflection) is shown. The problem of measurement of bremsstrahlung characteristics in the prewave zone is investigated. The expressions defining the measured radiation distribution for arbitrary values of the size and the position of the detector used for radiation registration are derived. The problem of TR influence upon the electron ionization loss in thin plate and in a system of two plates is discussed. The proposal for experimental investigation of such effect is formulated.

  7. Particle Identification: Time-of-Flight, Cherenkov and Transition Radiation Detectors - Particle Detectors and Detector Systems

    CERN Document Server

    Ullaland, O

    2011-01-01

    Particle Identification: Time-of-Flight, Cherenkov and Transition Radiation Detectors in 'Particle Detectors and Detector Systems', part of 'Landolt-Börnstein - Group I Elementary Particles, Nuclei and Atoms: Numerical Data and Functional Relationships in Science and Technology, Volume 21B1: Detectors for Particles and Radiation. Part 1: Principles and Methods'. This document is part of Part 1 'Principles and Methods' of Subvolume B 'Detectors for Particles and Radiation' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Section '3.3 Particle Identification: Time-of-Flight, Cherenkov and Transition Radiation Detectors' of Chapter '3 Particle Detectors and Detector Systems' with the content: 3.3 Particle Identification: Time-of-Flight, Cherenkov and Transition Radiation Detectors 3.3.1 Introduction 3.3.2 Time of Flight Measurements 3.3.2.1 Scintillator hodoscopes 3.3.2.2 Parallel plate ToF detectors 3.3.3 Cherenkov Radiation 3.3.3.1 ...

  8. Phenomenology of heavy quarkonium radiative E1 transitions

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Hector E. [Physik-Department, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany)

    2016-01-22

    We present preliminary results of the evaluation of the next-to-leading-order (NLO) relativistic corrections to the heavy quarkonium electric dipole transition (E1) rate. In our evaluation we use the quark-antiquark potential up to 1/m{sup 2} corrections that includes the effective string theory expression for the long range, a review on the method to construct this potential is given. Our results compare favorable with the experiments and may provide predictions for the rates for which no experimental data is yet available.

  9. All-optical radiation reaction in head-on laser electron interaction

    Science.gov (United States)

    Vranic, Marija; Grismayer, Thomas; Martins, Joana L.; Fonseca, Ricardo A.; Silva, Luis O.

    2016-10-01

    Radiation reaction (RR) accounts for the slowdown of a charged particle that occurs when a significant fraction of its kinetic energy is emitted as radiation. Here we show that this effect could be measured in an all-optical setup using a laser wakefield accelerated electron beam colliding with an intense laser pulse. We employ full-scale 3D PIC simulations to show that one can enter a radiation reaction dominated regime with a GeV electron beam and a 30 fs laser of I = 1021W/cm2. The electrons can lose up to 40% of their initial energy, which can be used as an experimental signature in the spectra. Our results indicate that modern laser facilities provide an exciting opportunity to explore classical RR and the near-future laser facilities can be employed to study the RR beyond classical description. By using higher laser intensities (1022-1023W/cm2) , quantum effects such as Compton scattering and Breit-Wheeler pair production become relevant. We have included these quantum effects in our PIC code OSIRIS through a Monte Carlo module, and performed a detailed numerical study of the transition from classical to quantum RR dominated regime. We identified the distinct features in the electron distribution function that could serve as signatures of quantum radiation reaction, and showed that large-scale infrastructures (e.g. NIF and ELI and next generation of PW-class lasers (e. g. CoReLS, Bella-i, Texas Petawatt, Apollon 10 PW) could be employed to test the physics in these extreme scenarios.

  10. Coherent control of a strongly driven silicon vacancy optical transition in diamond

    CERN Document Server

    Zhou, Yu; Li, Ke; Xiong, Qihua; Aharonovich, Igor; Gao, Wei-bo

    2016-01-01

    The ability to prepare, optically read out and coherently control single quantum states is a key requirement for quantum information processing. Optically active solid state emitters have emerged as promising candidates with their prospects for on chip integration as quantum nodes and sources of coherent photons for connecting these nodes. Under strongly driving resonant laser field, such quantum emitter can exhibit quantum behavior such as Autler-Townes splitting and Mollow triplet spectrum. Here we demonstrate coherent control of a strongly driven optical transition in silicon vacancy (SiV) center in diamond. Rapid optical detection of photons enabled the observation of time resolved coherent Rabi oscillations and the Mollow triplet from an optical transition of a single SiV defect. Detection with a probing transition further confirmed Autler-Townes splitting generated by a strong laser field. Coherence time of the emitted photons is shown to be comparable to its lifetime and robust under very strong drivin...

  11. Measurements of longitudinal gamma ray distribution using a multichannel fiber-optic Cerenkov radiation sensor

    Science.gov (United States)

    Shin, S. H.; Jeon, D.; Kim, J. S.; Jang, J. S.; Jang, K. W.; Yoo, W. J.; Moon, J. H.; Park, B. G.; Kim, S.; Lee, B.

    2014-11-01

    Cerenkov radiation occurs when charged particles are moving faster than the speed of light in a transparent dielectric medium. In optical fibers, Cerenkov radiation can also be generated due to the fiber’s dielectric components. Accordingly, the radiation-induced light signals can be obtained using the optical fibers without any scintillating material. In this study, we fabricated a multichannel, fiber-optic Cerenkov radiation sensor (FOCRS) system using silica optical fibers (SOFs), plastic optical fibers (POFs), an optical spectrometer, multi-anode photomultiplier tubes (MA-PMTs) and a scanning system to measure the light intensities of Cerenkov radiation induced by gamma rays. To evaluate the fading effects in optical fibers, the spectra of Cerenkov radiation generated in the SOFs and POFs were measured based on the irradiation time by using an optical spectrometer. In addition, we measured the longitudinal distribution of gamma rays emitted from the cylindrical type Co-60 source by using MA-PMTs. The result was also compared with the distribution of the electron flux calculated by using the Monte Carlo N-particle transport code (MCNPX).

  12. Terahertz coherent transition radiation based on an ultrashort electron bunching beam

    Science.gov (United States)

    Liu, Wen-Xin; Huang, Wen-Hui; Du, Ying-Chao; Yan, Li-Xin; Wu, Dai; Tang, Chuan-Xiang

    2011-07-01

    The experimental result of terahertz (THz) coherent transition radiation generated from an ultrashort electron bunching beam is reported. During this experiment, the window for THz transmission from ultrahigh vacuum to free air is tested. The compact measurement system which can simultaneously test the THz wave power and frequency is built and proofed. With the help of improved Martin—Puplett interferometer and Kramers—Krong transform, the longitudinal bunch length is measured. The results show that the peak power of THz radiation wave is more than 80 kW, and its radiation frequency is from 0.1 THz to 1.5 THz.

  13. Optical imaging of oral pathological tissue using optical coherence tomography and synchrotron radiation computed microtomography

    Science.gov (United States)

    Cânjǎu, Silvana; Todea, Carmen; Sinescu, Cosmin; Negrutiu, Meda L.; Duma, Virgil; Mǎnescu, Adrian; Topalǎ, Florin I.; Podoleanu, Adrian Gh.

    2013-06-01

    The efforts aimed at early diagnosis of oral cancer should be prioritized towards developing a new screening instrument, based on optical coherence tomography (OCT), to be used directly intraorally, able to perform a fast, real time, 3D and non-invasive diagnosis of oral malignancies. The first step in this direction would be to optimize the OCT image interpretation of oral tissues. Therefore we propose plastination as a tissue preparation method that better preserves three-dimensional structure for study by new optical imaging techniques. The OCT and the synchrotron radiation computed microtomography (micro-CT) were employed for tissue sample analyze. For validating the OCT results we used the gold standard diagnostic procedure for any suspicious lesion - histopathology. This is a preliminary study of comparing features provided by OCT and Micro-CT. In the conditions of the present study, OCT proves to be a highly promising imaging modality. The use of x-ray based topographic imaging of small biological samples has been limited by the low intrinsic x-ray absorption of non-mineralized tissue and the lack of established contrast agents. Plastination can be used to enhance optical imagies of oral soft tissue samples.

  14. Radiation-hard/high-speed parallel optical links

    Energy Technology Data Exchange (ETDEWEB)

    Gan, K.K., E-mail: gan@mps.ohio-state.edu [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); Buchholz, P. [Fachbereich Physik, Universität Siegen, Siegen (Germany); Kagan, H.P.; Kass, R.D.; Moore, J.; Smith, D.S. [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); Wiese, A.; Ziolkowski, M. [Fachbereich Physik, Universität Siegen, Siegen (Germany)

    2013-12-11

    We have designed an ASIC for use in a parallel optical engine for a new layer of the ATLAS pixel detector in the initial phase of the LHC luminosity upgrade. The ASIC is a 12-channel Vertical Cavity Surface Emitting Laser (VCSEL) array driver capable of operating up to 5 Gb/s per channel. The ASIC is designed using a 130 nm CMOS process to enhance the radiation-hardness. A scheme for redundancy has also been implemented to allow bypassing of a broken VCSEL. The ASIC also contains a power-on reset circuit that sets the ASIC to a default configuration with no signal steering. In addition, the bias and modulation currents of the individual channels are programmable. We have tested the ASIC and the performance up to 5 Gb/s is satisfactory. Furthermore, we are able to program the bias and modulation currents and to bypass a broken VCSEL channel. We are currently upgrading our design to allow operation at 10 Gb/s per channel yielding an aggregated bandwidth of 120 Gb/s. Preliminary results of the design will be presented.

  15. Radiation-hard/high-speed parallel optical links

    Energy Technology Data Exchange (ETDEWEB)

    Gan, K.K., E-mail: gan@mps.ohio-state.edu [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); Buchholz, P. [Fachbereich Physik, Universität Siegen, Siegen (Germany); Kagan, H.P.; Kass, R.D.; Moore, J.; Smith, D.S. [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); Wiese, A.; Ziolkowski, M. [Fachbereich Physik, Universität Siegen, Siegen (Germany)

    2014-11-21

    We have designed an ASIC for use in a parallel optical engine for a new layer of the ATLAS pixel detector in the initial phase of the LHC luminosity upgrade. The ASIC is a 12-channel VCSEL (Vertical Cavity Surface Emitting Laser) array driver capable of operating up to 5 Gb/s per channel. The ASIC is designed using a 130 nm CMOS process to enhance the radiation-hardness. A scheme for redundancy has also been implemented to allow bypassing of a broken VCSEL. The ASIC also contains a power-on reset circuit that sets the ASIC to a default configuration with no signal steering. In addition, the bias and modulation currents of the individual channels are programmable. The performance of the first prototype ASIC up to 5 Gb/s is satisfactory. Furthermore, we are able to program the bias and modulation currents and to bypass a broken VCSEL channel. We are currently upgrading our design to allow operation at 10 Gb/s per channel yielding an aggregated bandwidth of 120 Gb/s. Some preliminary results of the design will be presented.

  16. War Induced Aerosol Optical, Microphysical and Radiative Effects

    Science.gov (United States)

    Munshi, Pavel; Tiwari, Shubhansh

    2017-01-01

    The effect of war on air pollution and climate is assessed in this communication. War today in respect of civil wars and armed conflict in the Middle East area is taken into consideration. Impacts of war are not only in loss of human life and property, but also in the environment. It is well known that war effects air pollution and in the long run contribute to anthropogenic climate change, but general studies on this subject are few because of the difficulties of observations involved. In the current scenario of the ongoing conflict in the Middle East regions, deductions in parameters of atmosphere are discussed. Aerosol Optical Depth, Aerosol loads, Black Carbon, Ozone,Dust, regional haze and many more are analyzed using various satellite data. Multi-model analysis is also studied to verify the analysis. Type segregation of aerosols, in-depth constraints to atmospheric chemistry, biological effects and particularly atmospheric physics in terms of radiative forcing, etc. are discussed. Undergraduate in Earth Sciences.

  17. Theory of optical transitions in conjugated polymers. I. Ideal systems

    Energy Technology Data Exchange (ETDEWEB)

    Barford, William, E-mail: william.barford@chem.ox.ac.uk [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ (United Kingdom); Marcus, Max [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ (United Kingdom); Magdalen College, University of Oxford, Oxford OX1 4AU (United Kingdom)

    2014-10-28

    We describe a theory of linear optical transitions in conjugated polymers. The theory is based on three assumptions. The first is that the low-lying excited states of conjugated polymers are Frenkel excitons coupled to local normal modes, described by the Frenkel-Holstein model. Second, we assume that the relevant parameter regime is ℏω ≪ J, i.e., the adiabatic regime, and thus the Born-Oppenheimer factorization of the electronic and nuclear degrees of freedom is generally applicable. Finally, we assume that the Condon approximation is valid, i.e., the exciton-polaron wavefunction is essentially independent of the normal modes. Using these assumptions we derive an expression for an effective Huang-Rhys parameter for a chain (or chromophore) of N monomers, given by S(N) = S(1)/IPR, where S(1) is the Huang-Rhys parameter for an isolated monomer. IPR is the inverse participation ratio, defined by IPR = (∑{sub n}|Ψ{sub n}|{sup 4}){sup −1}, where Ψ{sub n} is the exciton center-of-mass wavefunction. Since the IPR is proportional to the spread of the exciton center-of-mass wavefunction, this is a key result, as it shows that S(N) decreases with chain length. As in molecules, in a polymer S(N) has two interpretations. First, ℏωS(N) is the relaxation energy of an excited state caused by its coupling to the normal modes. Second, S(N) appears in the definition of an effective Franck-Condon factor, F{sub 0v}(N) = S(N){sup v}exp ( − S(N))/v! for the vth vibronic manifold. We show that the 0 − 0 and 0 − 1 optical intensities are proportional to F{sub 00}(N) and F{sub 01}(N), respectively, and thus the ratio of the 0 − 1 to 0 − 0 absorption and emission intensities are proportional to S(N). These analytical results are checked by extensive DMRG calculations and found to be generally valid, particularly for emission. However, for large chain lengths higher-lying quasimomentum exciton states become degenerate with the lowest vibrational excitation of the

  18. Engineering of radiation of optically active molecules with chiral nano-meta-particles

    CERN Document Server

    Klimov, Vasily V; Ducloy, Martial

    2011-01-01

    The radiation of optically active (chiral) molecule placed near chiral nanoparticle is investigated. The optimal conditions for engineering of radiation of optically active (chiral) molecules with the help of chiral nanoparticles are derived. It is shown that for this purpose, the substance of the chiral particle must have both \\epsilon_and \\mu_negative (double negative material (DNG)) or negative \\mu_and positive \\epsilon_(\\mu_negative material (MNG)). Our results pave the way to an effective engineering of radiation of "left" and "right" molecules and to creating pure optical devices for separation of drugs enantiomers.

  19. Engineering of radiation of optically active molecules with chiral nano-meta-particles

    Science.gov (United States)

    Klimov, V. V.; Guzatov, D. V.; Ducloy, M.

    2012-02-01

    The radiation of an optically active (chiral) molecule placed near a chiral nanosphere is investigated. The optimal conditions for engineering of radiation of optically active (chiral) molecules with the help of chiral nanoparticles are derived. It is shown that for this purpose, the substance of the chiral particle must have both ɛ and μ negative (double negative material (DNG)) or negative μ and positive ɛ (μ negative material (MNG)). Our results pave the way to an effective engineering of radiation of "left" and "right" molecules and to creating pure optical devices for separation of drugs enantiomers.

  20. Potential of electric quadrupole transitions in radium isotopes for single-ion optical frequency standards

    NARCIS (Netherlands)

    Versolato, O. O.; Wansbeek, L. W.; Jungmann, K.; Timmermans, R. G. E.; Willmann, L.; Wilschut, H. W.

    2011-01-01

    We explore the potential of the electric quadrupole transitions 7s (2)S(1/2)-(6)d (2)D(3/2), 6d (2)D(5/2) in radium isotopes as single-ion optical frequency standards. The frequency shifts of the clock transitions due to external fields and the corresponding uncertainties are calculated. Several

  1. Radiation Pressure Force from Optical Cycling on a Polyatomic Molecule SrOH

    Science.gov (United States)

    Kozyryev, Ivan; Baum, Louis; Matsuda, Kyle; Sedlack, Alex; Hemmerling, Boerge; Doyle, John

    2016-05-01

    Polyatomic molecules hold promise for many applications in physics and chemistry due to their rotational and vibrational degrees of freedom. The starting point for our approach to the production of ultracold strontium monohydroxide (SrOH) is buffer-gas cooling followed by laser manipulation. Linear geometry, diagonal Franck-Condon factors, short radiative lifetimes and unresolved hyperfine splittings make SrOH a particularly attractive candidate for direct laser cooling. We report deflection of the SrOH beam through radiative force from optical cycling on the X~2Σ+ Ã2Π1 / 2 transition. We observe × 12 fluorescence enhancement with closed spin-rotation splitting and demonstrate cycling between different vibrational levels with the Sr O mode repumping laser. Observed deflection and detection signals correspond to the scattering of ~ 100 photons. Additional repumping laser for the bending mode would lead to scattering of ~ 1 , 000 photons allowing for transverse laser cooling of the SrOH beam. We will also describe our experimental efforts towards laser slowing and trapping of SrOH.

  2. Modelling of Noise and Straw to Straw Variations in the ATLAS Transition Radiation Tracker

    CERN Document Server

    Kittelmann, T H

    2006-01-01

    In this note a procedure is presented for modelling noise and straw to straw variations in the ATLAS Transition Radiation Tracker which can ultimately be based on reliable off-beam occupancy maps. The model is tuned and validated against the results of a test beam study, and its implementation in offline digitisation software is discussed.

  3. Modeling simulation of the thermal radiation for high-speed flight vehicles' aero-optical windows

    Science.gov (United States)

    Chen, Lei; Zhang, Liqin; Guo, Mingjiang

    2015-10-01

    When high-speed flight vehicles fly in the atmosphere, they can generate serious aero-optical effect. The optical window temperature rises sharply because of aerodynamic heating. It will form radiation interference that can lead infrared detectors to producing non-uniform radiation backgrounds, decreasing system SNR and detection range. Besides, there exits temperature difference due to uneven heating. Under the thermo-optical and elastic-optical effects, optical windows change into inhomogeneous mediums which influence the ray propagation. In this paper, a model of thermal radiation effect was built by a finite element analysis method. Firstly, the optical window was divided into uniform grids. Then, radiation distribution on the focal planes at different angles of the window's normal line and optical axis was obtained by tracing light rays of each grid. Finally, simulation results indicate that radiation distribution reflects the two directions-the length and width-of temperature distribution, and the change of angle causes the center of radiation distribution to shift to one direction of the image surface under the same window temperature.

  4. Effect of gamma radiation on optical and electrical properties of tellurium dioxide thin films

    Indian Academy of Sciences (India)

    T K Maity; S L Sharma

    2008-11-01

    Gamma radiation induced changes in the optical and electrical properties of tellurium dioxide (TeO2) thin films, prepared by thermal evaporation, have been studied in detail. The optical characterization of the as-deposited thin films and that of the thin films exposed to various levels of gamma radiation dose clearly show that the optical bandgap decreases with increase in the gamma radiation dose up to a certain dose. At gamma radiation doses above this value, however, the optical bandgap has been found to increase. On the other hand, the current vs voltage plots for the as-deposited thin films and those for the thin films exposed to various levels of gamma radiation dose show that the current increases with the gamma radiation dose up to a certain dose and that the value of this particular dose depends upon the thickness of the film. The current has, however, been found to decrease with further increase in gamma radiation dose. The observed changes in both the optical and electrical properties indicate that TeO2 thin films can be used as the real time gamma radiation dosimeter up to a certain dose, a quantity that depends upon the thickness of the film.

  5. Ionizing Radiation Detectors Based on Ge-Doped Optical Fibers Inserted in Resonant Cavities

    Directory of Open Access Journals (Sweden)

    Saverio Avino

    2015-02-01

    Full Text Available The measurement of ionizing radiation (IR is a crucial issue in different areas of interest, from environmental safety and industrial monitoring to aerospace and medicine. Optical fiber sensors have recently proven good candidates as radiation dosimeters. Here we investigate the effect of IR on germanosilicate optical fibers. A piece of Ge-doped fiber enclosed between two fiber Bragg gratings (FBGs is irradiated with gamma radiation generated by a 6 MV medical linear accelerator. With respect to other FBG-based IR dosimeters, here the sensor is only the bare fiber without any special internal structure. A near infrared laser is frequency locked to the cavity modes for high resolution measurement of radiation induced effects on the fiber optical parameters. In particular, we observe a variation of the fiber thermo-optic response with the radiation dose delivered, as expected from the interaction with Ge defect centers, and demonstrate a detection limit of 360 mGy. This method can have an impact in those contexts where low radiation doses have to be measured both in small volumes or over large areas, such as radiation therapy and radiation protection, while bare optical fibers are cheap and disposable.

  6. Fundamental research on a cerenkov radiation sensor based on optical glass for detecting beta-rays

    Science.gov (United States)

    Kim, Jae Seok; Jang, Kyoung Won; Shin, Sang Hun; Jeon, Dayeong; Hong, Seunghan; Sim, Hyeok In; Kim, Seon Geun; Yoo, Wook Jae; Lee, Bongsoo; Moon, Joo Hyun; Park, Byung Gi

    2015-01-01

    In this study, a Cerenkov radiation sensor for detecting low-energy beta-particles was fabricated using various Cerenkov radiators such as an aerogel and CaF2-, SiO2-, and Al2O3-based optical glasses. Because the Cerenkov threshold energy (CTE) is determined by the refractive index of the Cerenkov radiator, the intensity of Cerenkov radiation varies according to the refractive indices of the Cerenkov radiators. Therefore, we measured the intensities of Cerenkov radiation induced by beta-particles generated from a radioactive isotope as a function of the refractive indices of the Cerenkov radiators. Also, the electron fluxes were calculated for various Cerenkov radiators by using a Monte Carlo N-Particle extended transport code (MCNPX) to determine the relationship between the intensities of the Cerenkov radiation and the electron fluxes.

  7. Longitudinal electron bunch diagnostics using coherent transition radiation at the IRFEL

    Science.gov (United States)

    Zhou, T. Y.; Yang, Y. L.; Sun, B. G.; Tang, L. L.; Lu, P.; Zhou, Z. R.; Wu, F. F.; Liu, X. Y.

    2016-09-01

    A longitudinal electron bunch diagnostics system is developing to measure the longitudinal bunch charge distribution for the new IRFEL at National Synchrotron Radiation Laboratory (NSRL). We use a Martin-Puplett interferometer, which is essentially a Michelson interferometer, to measure the spectrum of the coherent transition radiation produced by electrons through a thin metallic foil. Frequency components of coherent transition radiation have a relationship with the bunch form factor, which is described by the square modulus of the Fourier transform of the bunch distribution. Then several techniques, including a Kramers-Kronig analysis, have been applied to determine the longitudinal bunch charge distribution. The details of the design and theoretical investigation will be described in this paper.

  8. Control of Optical Transitions with Magnetic Fields in Weakly Bound Molecules

    CERN Document Server

    McGuyer, B H; Iwata, G Z; Skomorowski, W; Moszynski, R; Zelevinsky, T

    2015-01-01

    Forbidden optical transitions in weakly bound $^{88}$Sr$_2$ molecules become strongly enabled with moderate applied magnetic fields. We report the control of transition strengths by five orders of magnitude and measurements of highly nonlinear Zeeman shifts, which we explain with an accurate {\\it ab initio} model. Mixed quantization in an optical lattice enables the experimental procedure. Our observation of formerly inaccessible $f$-parity excited states offers a new avenue for improving theoretical models for divalent atom dimers. Furthermore, magnetically enabled transitions may lead to an extremely precise subradiant molecular lattice clock.

  9. Influence of variable tungsten valency on optical transmittance and radiation hardness of lead tungstate (PWO) scintillation crystals

    CERN Document Server

    Burachas, S; Makov, I; Saveliev, Yu; Ippolitov, M S; Man'ko, V; Nikulin, S P; Nyanin, A; Vasilev, A; Apanasenko, A; Tamulaitis, G

    2003-01-01

    A new approach to interpret the radiation hardness of PbWO//4 (PWO) scintillators is developed by revealing importance of the inclusions of tungsten oxides WO//3//-//x with variable valency. It is demonstrated that the influence of the ionizing radiation on PWO is, in many aspects, similar to the effect of the high-temperature annealing in oxygenless ambient. In both cases, a valency change of the tungsten oxides is initiated and results in induced absorption and, consequently, in crystal coloration. In the PWO crystals doped with L//2O//3 (L = Y, La, Gd), the radiation hardness and the optical properties are mainly affected by inclusions of W//1//-//yL//yO//3//- //x (0 less than x less than 0.3) instead of inclusions of WO//3//- //x prevailing in the undoped samples. It is demonstrated that the radiation-induced bleaching and the photochromic effect of PWO are caused by phase transitions in the inclusions of tungsten oxide. Thermodynamic conditions for the phase transitions are discussed and the optimal oxid...

  10. Abrupt transition from natural to anthropogenic aerosol radiative forcing: Observations at the ABC-Maldives Climate Observatory

    Science.gov (United States)

    Ramana, M. V.; Ramanathan, V.

    2006-10-01

    Using aerosol-radiation observations over the north Indian Ocean, we show how the monsoon transition from southwest to northeast flow gives rise to a similar transition in the direct aerosol radiative forcing from natural to anthropogenic forcing. These observations were taken at the newly built aerosol-radiation-climate observatory at the island of Hanimaadhoo (6.776°N, 73.183°E) in the Republic of Maldives. This observatory is established as a part of Project Atmospheric Brown Clouds (ABC) and is referred to as the ABC-Maldives Climate Observatory at Hanimaadhoo (ABC_MCOH). The transition from the southwest monsoon during October to the northeast monsoon flow during early November occurs abruptly over a period of few weeks over ABC-MCOH and reveals a dramatic contrast between the natural marine aerosols transported from the south Indian Ocean by the southwest monsoon and that of the polluted aerosols transported from the south and Southeast Asian region by the northeast monsoon. We document the change in the microphysical properties and the irradiance at the surface, to identify the human signature on aerosol radiative forcing. We first establish the precision of surface radiometric observations by comparing simultaneous observations using calibrated Kipp & Zonen and Eppley pyrheliometers and pyranometers for direct, diffuse and global solar radiation. We show that the direct, diffuse and global radiation can be measured within a precision of about 3 to 5 Wm-2. Furthermore, when we include the observed aerosol optical properties as input into the Monte Carlo Aerosol Cloud Radiation (MACR) model (developed by us using Indian Ocean Experiment data), the simulated fluxes agree with the observed direct, diffuse and global fluxes within the measurement accuracy. A steady southwest monsoon flow of about 5 to 7 ms-1 persists until middle of October which switches to an abrupt change in direction to northeast flow of similar speeds bringing in polluted air from south

  11. Uncovering forbidden optical transitions in PbSe nanocrystals.

    Science.gov (United States)

    Peterson, Jeffrey J; Huang, Libai; Delerue, Christophe; Allan, Guy; Krauss, Todd D

    2007-12-01

    The 1S(h,e)-1P(e,h) exciton transition energy of PbSe nanocrystals was determined via two-photon photoluminescence excitation spectroscopy and was found to be in good agreement with predictions from a tight-binding calculation. The two-photon excitation peak occurs at energies very close to a strong feature in the one-photon absorption spectrum and suggests that it should be assigned as a formally forbidden S-P transition. Leading explanations for the unusual strength of the forbidden transition are discussed.

  12. Elimination of Cerenkov interference in a fibre-optic-coupled radiation dosemeter.

    Science.gov (United States)

    Justus, Brian L; Falkenstein, Paul; Huston, Alan L; Plazas, Maria C; Ning, Holly; Miller, Robert W

    2006-01-01

    An optical fibre point dosemeter based on the gated detection of the luminescence from a Cu(1+)-doped fused quartz detector effectively eliminated errors due to Cerenkov radiation and native fibre fluorescence. The gated optical fibre dosemeter overcomes serious problems faced by scintillation and optically stimulated luminescence approaches to optical fibre point dosimetry. The dosemeter was tested using an external beam radiotherapy machine that provided pulses of 6 MV X rays. Gated detection was used to discriminate the signal collected during the radiation pulses, which included contributions from Cerenkov radiation and native fibre fluorescence, from the signal collected between the radiation pulses, which contained only the long-lived luminescence from the Cu(1+)-doped fused quartz detector. Gated detection of the luminescence provided accurate, real-time dose measurements that were linear with absorbed dose, independent of dose rate and that were accurate for all field sizes studied.

  13. The effect of the earth's radiation belts on an optical system.

    Science.gov (United States)

    Wolff, C

    1966-11-01

    A photoelectric optical imaging system has survived one year in the earth's radiation belts with no measurable (radiation belts twice every 64 hr, and experiences a noise level equivalent to 400 photons/sec when in their most intense regions. While this noise is far less than that of other photoelectric systems operating in the belts because of the small effective area of the photocathode, the noise per unit cathode area is 1.3 x 10(5) photons/sec-cm(2), and is similar to the best of the other systems. The number and energy distribution of incident particles is calculated and then combined with shielding estimates to give the total energy absorbed in the optical elements. Radiation damage reports in the literature are shown to be consistent with the lack of a sensitivity change in this orbiting optical system. The effects of particle radiation on optical systems in general is briefly summarized, with emphasis on recent work of others.

  14. Directional Radiometry and Radiative Transfer: the Convoluted Path From Centuries-old Phenomenology to Physical Optics

    Science.gov (United States)

    Mishchenko, Michael I.

    2014-01-01

    This Essay traces the centuries-long history of the phenomenological disciplines of directional radiometry and radiative transfer in turbid media, discusses their fundamental weaknesses, and outlines the convoluted process of their conversion into legitimate branches of physical optics.

  15. Electrodynamical enhancement of optical transitions in semiconductor and metal-semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Rupasov, Valery I. [ALTAIR Center LLC, Shrewsbury, MA 01545 (United States) and Landau Institute for Theoretical Physics, Moscow (Russian Federation)]. E-mail: rupasov@townisp.com

    2007-03-19

    Semiconductor and metal-semiconductor nanostructures are shown to exhibit electrodynamical resonances analogous to the Froehlich resonance for metal nanoparticles in a dielectric host. If the transition frequency of an optical transition in the nanostructure core coincides with one of the resonance frequencies of the nanostructure, the strength of the optical transition is dramatically enhanced by up to 4-6 orders of magnitude. The resonance frequencies are determined by dielectric permittivities of materials of host and nanostructure, and by sizes of the nanostructure. That enables to tune the resonance frequencies to desired values in an extremely wide spectral range-from ultraviolet to terahertz, engineering thus optical properties of high-efficiency nanostructured optical materials for numerous applications.

  16. Radiation Hard Multi-Layer Optical Coatings Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Next generation space telescopes require advanced optical coatings to provide low loss transmission of light in a variety of spectral ranges and protect optical...

  17. Optically pumped infrared stimulated radiation in pr3+:Y2SiO5

    Institute of Scientific and Technical Information of China (English)

    Yanliang Zhang(张衍亮); Zhenrong Sun(孙真荣); Yuqiong Li(李玉琼); Liang'en Ding(丁良恩); Zugeng Wang(王祖赓)

    2003-01-01

    The infrared stimulated radiation of 1D2 → 3F.2 and 1D2 → 3H6 transitions in Pr3+:Y2SiO5 (YSO) viapulsed laser pumping has been observed. The threshold energy, temperature dependence and divergenceangle for the stimulated radiation are also measured.

  18. Revisiting radiative deep-level transitions in CuGaSe{sub 2} by photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Spindler, Conrad, E-mail: conrad.spindler@uni.lu; Regesch, David; Siebentritt, Susanne [Laboratory for Photovoltaics, Physics and Material Science Research Unit, University of Luxembourg, Rue du Brill 41, L-4422 Belvaux (Luxembourg)

    2016-07-18

    Recent defect calculations suggest that the open circuit voltage of CuGaSe{sub 2} solar cells can be limited by deep intrinsic electron traps by Ga{sub Cu} antisites and their complexes with Cu-vacancies. To gain experimental evidence, two radiative defect transitions at 1.10 eV and 1.24 eV are characterized by steady-state photoluminescence on epitaxial-grown CuGaSe{sub 2} thin films. Cu-rich samples are studied, since they show highest crystal quality, exciton luminescence, and no potential fluctuations. Variations of the laser intensity and temperature dependent measurements suggest that emission occurs from two deep donor-like levels into the same shallow acceptor. At 10 K, power-law exponents of 1 (low excitation regime) and 1/2 (high excitation regime) are observed identically for both transitions. The theory and a fitting function for the double power law is derived. It is concluded that the acceptor becomes saturated by excess carriers which changes the exponent of all transitions. Activation energies determined from the temperature quenching depend on the excitation level and show unexpected values of 600 meV and higher. The thermal activation of non-radiative processes can explain the distortion of the ionization energies. Both the deep levels play a major role as radiative and non-radiative recombination centers for electrons and can be detrimental for photovoltaic applications.

  19. Effects of Polarization-Maintaining Fibre Degrading on Precision of Fibre Optic Gyroscopes in Radiation Environment

    Institute of Scientific and Technical Information of China (English)

    XIAO Wen; LIU De-Wen; LIU Yang; YI Xiao-Su; CONG Lin

    2008-01-01

    @@ In the space environment, the precision of fibre optic gyroscopes (FOGs) degrades because of space radiation.Photonic components of FOGs axe affected by radiation, especially the polaxization-maintaining (PM) fibre coil.In relation to the space radiation environment characteristic, we have carried out a series of radiation experiments on a PM fibre coil with 60Co radiation source at different dose rates. Based on the experimental results, the formula between the PM-fibre loss and radiation dose rata is built, and the relation between the precision of FOG and radiation dose is obtained accordingly. The results strongly show that the precision of our FOG degrades owing to the attenuation of the polarization-maintaining fibre, which provides theoretical foundation for the radiation-resistant design of the FOG.

  20. Implementation of European Directive on Optical Radiation Safety takes place in May 2010

    NARCIS (Netherlands)

    Wieringa, F.P.

    2009-01-01

    At the latest by May 10th 2010, Directive 2006/25/EC regarding the exposure of workers to risks arising from artificial optical radiation must be implemented by all EU-member states, thus legally adopting ICNIRP limit values for ultraviolet, visible and infrared radiation. For IUVA-members the

  1. Proton radiation testing of laser optical components for NASA Jupiter Europa Orbiter Mission

    Science.gov (United States)

    Thomes, W. Joe, Jr.; Cavanaugh, John F.; Ott, Melanie N.

    2011-09-01

    The Jupiter Europa Orbiter (JEO) is NASA's element of the joint Europa Jupiter System Mission (EJSM). Based on current trajectories, the spacecraft will spend a significant amount of time in the Jovian radiation belts. Therefore, research endeavors are underway to study the radiation effects on the various parts and components needed to implement the instruments. Data from these studies will be used for component selection and system design to ensure reliable operation throughout the mission duration. The radiation environment en route to Jupiter is nothing new for NASA designed systems, however, the long durations orbiting Jupiter and Europa present new challenges for radiation exposure. High-energy trapped electrons and protons at Jupiter dominate the expected radiation environment. Therefore, most of the initial component level radiation testing is being conducted with proton exposure. In this paper we will present in-situ monitoring of the optical transmission of various laser optical components during proton irradiation. Radiation induced optical attenuation of some components is less than would be expected, based on the authors experiences, and is attributed to the interaction of the protons with the materials. The results are an encouraging first step in screening these optical materials for spaceflight in a high radiation environment.

  2. Search for Detour Transitions in the Radiative EC Decay of $^{81}$Kr

    CERN Multimedia

    Rykaczewski, K

    2002-01-01

    % IS355 \\\\ \\\\ It is proposed to produce at ISOLDE the $^{81}$Kr activity and to study its 1-st forbidden unique (1u) radiative electron-capture decay in low background conditions available in Warsaw. The intensity of the photon spectrum will be compared to predictions of the internal-bremsstrahlung theory. A question is whether an excess of the intensity will be observed, indicating the role of detour $\\gamma$/$\\beta$ transitions via intermediate virtual nuclear states, as detected already for the 1u radiative decay of $^{41}$Ca.

  3. Multilevel radiative thermal memory realized by the hysteretic metal-insulator transition of vanadium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Kota, E-mail: kotaito@mosk.tytlabs.co.jp; Nishikawa, Kazutaka; Iizuka, Hideo [Toyota Central Research and Development Labs, Nagakute, Aichi 480-1192 (Japan)

    2016-02-01

    Thermal information processing is attracting much interest as an analog of electronic computing. We experimentally demonstrated a radiative thermal memory utilizing a phase change material. The hysteretic metal-insulator transition of vanadium dioxide (VO{sub 2}) allows us to obtain a multilevel memory. We developed a Preisach model to explain the hysteretic radiative heat transfer between a VO{sub 2} film and a fused quartz substrate. The transient response of our memory predicted by the Preisach model agrees well with the measured response. Our multilevel thermal memory paves the way for thermal information processing as well as contactless thermal management.

  4. Radiative transitions in charm-strange meson from Nf = 2 twisted mass lattice QCD

    Science.gov (United States)

    Li, Ning; Wu, Ya-Jie

    2016-07-01

    We present an exploratory study on the radiative transition for the charm-strange meson: Ds∗→ D sγ using Nf = 2 twisted mass lattice quantum chromodynamics gauge configurations. The form factor for Ds meson is also determined. The simulation is performed on lattices with lattice spacings a = 0.067 fm and lattice size 323 × 64, and a = 0.085 fm and lattice size 243 × 48, respectively. Our numerical results for radiative decay width and the experimental data overlap within the margin of error.

  5. Homogeneous Broadening of Optical Transitions in Organic Mixed Crystals

    NARCIS (Netherlands)

    Vries, Harmen de; Wiersma, Douwe A.

    1976-01-01

    We have used the phenomenon of laser-induced molecular photodissociation to determine the homogeneous linewidth at 2 K of the origin (zero-phonon line) and a vibronic transition in the mixed-crystal absorption spectrum of dimethyl s-tetrazine in durene. From the measured 55-MHz (upper limit) homogen

  6. Measurement of "optical" transition probabilities in the silver atom

    NARCIS (Netherlands)

    Terpstra, J.; Smit, J.A.

    1958-01-01

    For 22 spectral lines of the silver atom the probability of spontaneous transition has been derived from measurements of the emission intensity of the line and the population of the corresponding upper level. The medium of excitation was the column of a vertical arc discharge in air of atmospheric

  7. Macro-Bending Influence on Radiation Induced Attenuation Measurement in Optical Fibres

    CERN Document Server

    Guillermain, E; Ricci, D; Weinand, U

    2014-01-01

    Influence of the bending radius on the measurement of radiation induced attenuation in glass optical fibres is discussed in this paper. Radiation induced attenuation measured in two single-mode fibre types shows discrepancies when coiled around a low bending radius spool: the observed attenuation is lower than expected. A series of dedicated tests reveals that this invalid measurement is related to the displacement of the mode field towards the cladding when the fibre is bent with a low radius, and to the different radiation resistances of the core and cladding glasses. For irradiation tests of optical fibres, the spool radius should therefore be carefully chosen.

  8. Improved Framework for Tractography Reconstruction of the Optic Radiation.

    Directory of Open Access Journals (Sweden)

    Eloy Martínez-Heras

    Full Text Available The optic radiation (OR is one of the major components of the visual system and a key structure at risk in white matter diseases such as multiple sclerosis (MS. However, it is challenging to perform track reconstruction of the OR using diffusion MRI due to a sharp change of direction in the Meyer's loop and the presence of kissing and crossing fibers along the pathway. As such, we aimed to provide a highly precise and reproducible framework for tracking the OR from thalamic and visual cortex masks. The framework combined the generation of probabilistic streamlines by high order fiber orientation distributions estimated with constrained spherical deconvolution and an automatic post-processing based on anatomical exclusion criteria (AEC to compensate for the presence of anatomically implausible streamlines. Specifically, those ending in the contralateral hemisphere, cerebrospinal fluid or grey matter outside the visual cortex were automatically excluded. We applied the framework to two distinct high angular resolution diffusion-weighted imaging (HARDI acquisition protocols on one cohort, comprised of ten healthy volunteers and five MS patients. The OR was successfully delineated in both HARDI acquisitions in the healthy volunteers and MS patients. Quantitative evaluation of the OR position was done by comparing the results with histological reference data. Compared with histological mask, the OR reconstruction into a template (OR-TCT was highly precise (percentage of voxels within the OR-TCT correctly defined as OR, ranging from 0.71 to 0.83. The sensitivity (percentage of voxels in histological reference mask correctly defined as OR in OR-TCT ranged from 0.65 to 0.81 and the accuracy (measured by F1 score was 0.73 to 0.77 in healthy volunteers. When AEC was not applied the precision and accuracy decreased. The absolute agreement between both HARDI datasets measured by the intraclass correlation coefficient was 0.73. This improved framework

  9. The Impacts of Optical Properties on Radiative Forcing Due to Dust Aerosol

    Institute of Scientific and Technical Information of China (English)

    WANG Hong; SHI Guangyu; LI Shuyan; LI Wei; WANG Biao; HUANG Yanbin

    2006-01-01

    There are large uncertainties in the quantitative assessment of radiative effects due to atmospheric dust aerosol. The optical properties contribute much to those uncertainties. The authors perform several sensitivity experiments to estimate the impacts of optical characteristics on regional radiative forcing in this paper. The experiments involve in refractive indices, single scattering albedo, asymmetry factor and optical depth. An updated dataset of refractive indices representing East Asian dust and the one recommended by the World Meteorology Organization (WMO) are contrastively analyzed and used. A radiative transfer code for solar and thermal infrared radiation with detailed aerosol parameterization is employed. The strongest emphasis is on the refractive indices since other optical parameters strongly depend on it, and the authors found a strong sensitivity of radiative forcing on refractive indices. Studies show stronger scattering, weaker absorption and forward scattering of the East Asian dust particles at solar wavelengths, which leads to higher negative forcing, lower positive forcing and bigger net forcing at the top of the atmosphere (TOA) than that of the WMO dust model. It is also found that the TOA forcings resulting from these two dust models have opposite signs in certain regions, which implies the importance of accurate measurements of optical properties in the quantitative estimation of radiative forcing.

  10. Recombination of charge carriers on radiation-induced defects in silicon doped by transition metals impurities

    CERN Document Server

    Kazakevich, L A

    2003-01-01

    It has been studied the peculiarities of recombination of nonequilibrium charge carriers on radiation-induced defects in received according to Czochralski method p-silicon (p approx 3 - 20 Ohm centre dot cm), doped by one of the impurities of transition metals of the IV-th group of periodic table (titanium, zirconium, hafnium). Experimental results are obtained out of the analysis of temperature and injection dependence of the life time of charge carriers. The results are explained taking into consideration the influences of elastic stress fields created by the aggregates of transition metals atoms on space distribution over the crystal of oxygen and carbon background impurities as well as on the migration of movable radiation-induced defects during irradiation. (authors).

  11. A Novel Highly Ionizing Particle Trigger using the ATLAS Transition Radiation Tracker

    CERN Document Server

    Penwell, J; The ATLAS collaboration

    2011-01-01

    The ATLAS Transition Radiation Tracker (TRT) is an important part of the experiment’s charged particle tracking system. It also provides the ability to discriminate electrons from pions efficiently using large signal amplitudes induced in the TRT straw tubes by transition radiation. This amplitude information can also be used to identify heavily ionizing particles, such as monopoles, or Q-balls, that traverse the straws. Because of their large ionization losses, these particles can range out before they reach the ATLAS calorimeter, making them difficult to identify by the experiment’s first level trigger. Much of this inefficiency could be regained by making use of a feature of the TRT electronics that allows fast access to information on whether large-amplitude signals were produced in regions of the detector. A modest upgrade to existing electronics could allow triggers sensitive to heavily ionizing particles at level-1 to be constructed by counting such large-amplitude signals in roads corresponding to...

  12. Radiative Hydrodynamic Models of Optical and Ultraviolet Emission from M Dwarf Flares

    CERN Document Server

    Allred, J C; Carlsson, M; Hawley, S L; Abbett, William P.; Allred, Joel C.; Carlsson, Mats; Hawley, Suzanne L.

    2006-01-01

    We report on radiative hydrodynamic simulations of M dwarf stellar flares and compare the model predictions to observations of several flares. The flares were simulated by calculating the hydrodynamic response of a model M dwarf atmosphere to a beam of non-thermal electrons. Radiative backwarming through numerous soft X-ray, extreme ultraviolet, and ultraviolet transitions are also included. The equations of radiative transfer and statistical equilibrium are treated in non-LTE for many transitions of hydrogen, helium and the Ca II ion allowing the calculation of detailed line profiles and continuum radiation. Two simulations were carried out, with electron beam fluxes corresponding to moderate and strong beam heating. In both cases we find the dynamics can be naturally divided into two phases: an initial gentle phase in which hydrogen and helium radiate away much of the beam energy, and an explosive phase characterized by large hydrodynamic waves. During the initial phase, lower chromospheric material is evap...

  13. Diffusion tensor imaging for in vivo detection of degenerated optic radiation.

    Science.gov (United States)

    Michelson, Georg; Engelhorn, Tobias; Waerntges, Simone; Doerfler, Arnd

    2011-01-01

    Glaucomatous optic nerve atrophy may continue to the linked optic radiation by transneuronal degeneration, as described in animal models of glaucoma. In vivo visualization of the visual pathway represents a new challenge in the field of ophthalmology. We present a new approach for illustration of the optic radiation by diffusion tensor imaging (DTI) based on magnetic resonance imaging (MRI). The DTI was established by use of a 3T high-field scanner. The case of a patient with primary open-angle glaucoma is opposed to this one of a healthy subject to demonstrate the visible rarefication of the optic radiation. The goal was to introduce the technique of the DTI also in ophthalmology and to demonstrate that it may be useful to judge glaucoma-related differences.

  14. Real-time fibre optic radiation dosimeters for nuclear environment monitoring around thermonuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, A. Fernandez; Brichard, B. [SCK .CEN, Belgian Nuclear Research Centre, Boeretang 200, B-2400 Mol (Belgium); O' Keeffe, S.; Fitzpatrick, C.; Lewis, E. [Electronic and Computer Engineering Department, University of Limerick, Limerick (Ireland); Vaille, J.-R.; Dusseau, L. [CEM2-Universite Montpellier II, cc083 place E. Bataillon, 34095 Montpellier Cedex 05 (France); Jackson, D.A. [School of Physical Sciences, University of Kent, Kent CT2 7NR (United Kingdom); Ravotti, F.; Glaser, M. [European Organization for Nuclear Research CERN, TS-LEA-RAD/PH-DT2-SD, CH-1211 Geneva 23 (Switzerland); El-Rabii, H. [Laboratoire de Combustion et de Detonique, ENSMA/CNRS, 1 av. Clement Ader, 86961 Chasseneuil-Futuroscope (France)], E-mail: afernand@sckcen.be

    2008-01-15

    The ability of fibre optic sensors to operate in hazardous nuclear environments and their intrinsic immunity to electro-magnetic interference make fibre optic sensing a very promising technology for the future ITER thermonuclear fusion reactor. In this paper, we evaluate fibre optic sensing technology for monitoring radiation dose in the vicinity of ITER during its operation and during the maintenance periods. First, the performance of an OSL dosimeter interrogated remotely using radiation tolerant optical fibres is evaluated both for real-time and integrating measurements for doses exceeding 100 Gy. We demonstrate its satisfactory operation in a mixed gamma neutron field. Second, we discuss the successful calibration of a new scintillating fibre optic radiation probe based on CsI(TI) crystals for operation in the dose-rate range 0.3-3000 mGy/h. The CsI(TI) crystal scintillator is mounted at the end of a 10-m long multimode fibre transceiver link to allow for remote deployment. The probes can detect and measure gamma dose rates ranging from 1 to 1000 mGy/h. Finally, we investigate the possible use of commercially available PMMA plastic optical fibres as on-line dosimeters up to 34 kGy. The dose measurement is derived from the radiation-induced attenuation in the optical fibre itself. A novel interrogation scheme based on a ratiometric technique is proposed for real-time dosimetry.

  15. Stretching and squeezing of sessile dielectric drops by the optical radiation pressure.

    Science.gov (United States)

    Chraïbi, Hamza; Lasseux, Didier; Arquis, Eric; Wunenburger, Régis; Delville, Jean-Pierre

    2008-06-01

    We study numerically the deformation of sessile dielectric drops immersed in a second fluid when submitted to the optical radiation pressure of a continuous Gaussian laser wave. Both drop stretching and drop squeezing are investigated at steady state where capillary effects balance the optical radiation pressure. A boundary integral method is implemented to solve the axisymmetric Stokes flow in the two fluids. In the stretching case, we find that the drop shape goes from prolate to near-conical for increasing optical radiation pressure whatever the drop to beam radius ratio and the refractive index contrast between the two fluids. The semiangle of the cone at equilibrium decreases with the drop to beam radius ratio and is weakly influenced by the index contrast. Above a threshold value of the radiation pressure, these "optical cones" become unstable and a disruption is observed. Conversely, when optically squeezed, the drop shifts from an oblate to a concave shape leading to the formation of a stable "optical torus." These findings extend the electrohydrodynamics approach of drop deformation to the much less investigated "optical domain" and reveal the openings offered by laser waves to actively manipulate droplets at the micrometer scale.

  16. Operation of the ATLAS Transition Radiation Tracker under very high irradiation at the CERN LHC

    CERN Document Server

    Åkesson, T; Baker, K; Baron, S; Benjamin, D; Bertelsen, H; Bondarenko, V; Bychkov, V; Callahan, J; Capéans-Garrido, M; Cardiel-Sas, L; Catinaccio, A; Cetin, S A; Cwetanski, Peter; Dam, M; Danielsson, H; Dittus, F; Dolgoshein, B A; Dressnandt, N; Driouichi, C; Ebenstein, W L; Eerola, Paule Anna Mari; Farthouat, Philippe; Fedin, O; Froidevaux, D; Gagnon, P; Grichkevitch, Y; Grigalashvili, N S; Hajduk, Z; Hansen, P; Kayumov, F; Keener, P T; Kekelidze, G D; Khristatchev, A; Konovalov, S; Koudine, L; Kovalenko, S; Kowalski, T; Kramarenko, V A; Krüger, K; Laritchev, A; Lichard, P; Luehring, F C; Lundberg, B; Maleev, V; McFarlane, K W; Mialkovski, V; Mindur, B; Mitsou, V A; Morozov, S; Munar, A; Muraviev, S; Nadtochy, A; Newcomer, F M; Ögren, H O; Oleshko, S; Olszowska, J; Passmore, S; Patritchev, S; Peshekhonov, V D; Petti, R; Price, M; Rembser, C; Rohne, O; Romaniouk, A; Rust, D R; Ryabov, Yu; Shchegelskii, V; Seliverstov, D M; Shin, T; Shmeleva, A; Smirnov, S; Sosnovtsev, V V; Soutchkov, V; Spiridenkov, E; Tikhomirov, V; Van Berg, R; Vassilakopoulos, V I; Vassilieva, L; Wang, C; Williams, H H; Zalite, A

    2004-01-01

    The ATLAS Transition Radiation Tracker (TRT) performance depends critically on the choice of the active gas and on its properties. The most important operational aspects, which have led to the final choice of the active gas for the operation of the TRT at the LHC design luminosity, are presented. The TRT performance expected at these conditions is reviewed, including pile-up effects at high luminosity. (9 refs).

  17. Optical Waveguiding Organic Nanorods Coated with Reversibly Switchable Fe(II Spin Transition Nanoparticles

    Directory of Open Access Journals (Sweden)

    Supratim Basak

    2013-01-01

    Full Text Available A dual functional nanohybrid object combining photonic and magnetic properties was successfully prepared through a “bottom-up” self-assembly approach. In this method, spin transition Fe(II coordination nanoparticles and optical wave guiding organic nanorods were generated in situ and successfully integrated together in a single pot through self-assembly. The Fe(II nanoparticles coated on organic nanorods (nanohybrids display temperature dependent reversible spin transition (Paramagnetic; diamagnetic; behavior. The nano-hybrids show efficient optical wave guiding behavior, which demonstrates the future possibility to perform light induced excited spin state trapping (LIESST experiments on a single spin transition nanoparticle level. These photonic and magnetic “nanohybrids” offer promising option to externally manipulate spin state of the spin transition nanoparticles using temperature as well as remote laser light.

  18. Optically induced phase transition of excitons in coupled quantum dots

    Institute of Scientific and Technical Information of China (English)

    Chen Zi-Dong

    2008-01-01

    The weak classical light excitations in many semiconductor quantum dots have been chosen as important solidstate quantum systems for processing quantum information and implementing quantum computing. For strong classical light we predict theoretically a novel phase transition as a function of magnitude of this classical light from the deformed to the normal phases in resonance case, and the essential features of criticality such as the scaling behaviour, critical exponent and universality are also present in this paper.

  19. Ultraviolet radiation-induced modifications of the optical and registration properties of a CR-39 nuclear track detector

    Energy Technology Data Exchange (ETDEWEB)

    Saad, A.F., E-mail: abdallahsaad56@hotmail.com [Physics Department, Faculty of Science, University of Benghazi, Benghazi (Libya); Physics Department, Faculty of Science, Zagazig University, Zagazig (Egypt); Al-Faitory, N.M. [Physics Department, Faculty of Science, University of Benghazi, Benghazi (Libya); Hussein, M. [Physics Department, Faculty of Science, Zagazig University, Zagazig (Egypt); Mohamed, R.A. [Physics Department, Faculty of Science, University of Benghazi, Benghazi (Libya)

    2015-09-15

    The UV–VIS (ultraviolet–visible) spectra and etching characteristics of poly allyl diglycol carbonate (PADC, a form of the CR-39 polymer) detector films after exposure to UV radiation for various times have been studied. Etching experiments were carried out on the UV-exposed CR-39 detectors after alpha particle and fission-fragment irradiation using a {sup 252}Cf source. The bulk and track etch rates were measured using the alpha and fission-fragment track diameters, and the sensitivity and the detection efficiency were also determined. The optical band gap for both indirect and direct transitions was calculated based on the absorption edge of the UV spectra of the pristine and variously UV-exposed detectors. The optical band gap evidently indicates a gradual change in the optical properties of the CR-39 detector that is induced by the UV radiation. This study shows that the UV-exposed CR-39 detectors were demonstrated to be highly sensitive to alpha particles, but proved to be somewhat less sensitive to the fission fragments.

  20. γ-radiation Sensor Using Optical and Electrical Properties of Manganese Phthalocyanine (MnPc Thick Film

    Directory of Open Access Journals (Sweden)

    K. Arshak

    2002-05-01

    Full Text Available Manganese phthaloyanine polymer thick films were fabricated using screenprinting techniques. The optical parameters were obtained from the analysis of the absorption spectra over a wavelength range of 385-900nm. The d.c. electrical measurements were carried out in a range of 0-30 volts. The effects of γ-radiation on the optical and the electrical properties were investigated for dosimetry applications. The optical energy band gaps of these films showed a decrease in their values with the increase in the radiation dose. The electronic transition has changed from direct allowed for the as-printed films (unexposed to γ-rays to indirect allowed for the irradiated samples. Both the as-printed and irradiated Ag/MnPc/Ag devices demonstrated a Schottky conduction mechanism. Both the absorbance and the capacitance of the MnPc thick films displayed a highly consistent linear response to γ-ray exposure.

  1. Determination of electron bunch shape using transition radiation and phase-energy measurements

    Energy Technology Data Exchange (ETDEWEB)

    Crosson, E.R.; Berryman, K.W.; Richman, B.A. [Stanford Univ., CA (United States)] [and others

    1995-12-31

    We present data comparing microbunch temporal information obtained from electron beam phase-energy measurements with that obtained from transition radiation auto-correlation measurements. The data was taken to resolve some of the ambiguities in previous transition radiation results. By measuring the energy spectrum of the electron beam as a function of its phase relative to the accelerating field, phase-energy information was extracted. This data was analyzed using tomographic techniques to reconstruct the phase-space distribution assuming an electron energy dependence of E({var_phi}) = E{sub o} + E{sub acc}cos({var_phi}), where E{sub o} is the energy of an electron entering the field, E{sub acc} is the peak energy gain, and {var_phi} is the phase between the crest of the RF wave and an electron. Temporal information about the beam was obtained from the phase space distribution by taking the one dimensional projection along the time axis. We discuss the use of this technique to verify other transition radiation analysis methods.

  2. Saturation of atomic transitions using sub-wavelength diameter tapered optical fibers in rubidium vapor

    CERN Document Server

    Jones, D E; Pittman, T B

    2014-01-01

    We experimentally investigate ultralow-power saturation of the rubidium D2 transitions using a tapered optical fiber (TOF) suspended in a warm Rb vapor. A direct comparison of nonlinear absorption measurements for the TOF system with those obtained in a standard free-space vapor cell system highlights the differences in saturation behavior for the two systems. The effects of hyperfine pumping in the TOF system are found to be minimized due to the short atomic transit times through the highly confined evanescent optical mode guided by the TOF. The TOF system data is well-fit by a relatively simple empirical absorption model that indicates nanoWatt-level saturation powers.

  3. New trends in the optical and electronic applications of polymers containing transition-metal complexes.

    Science.gov (United States)

    Liu, Shu-Juan; Chen, Yang; Xu, Wen-Juan; Zhao, Qiang; Huang, Wei

    2012-04-13

    Polymers containing transition-metal complexes exhibit excellent optical and electronic properties, which are different from those of polymers with a pure organic skeleton and combine the advantages of both polymers and metal complexes. Hence, research about this class of polymers has attracted more and more interest in recent years. Up to now, a number of novel polymers containing transition-metal complexes have been exploited, and significant advances in their optical and electronic applications have been achieved. In this article, we summarize some new research trends in the applications of this important class of optoelectronic polymers, such as chemo/biosensors, electronic memory devices and photovoltaic devices.

  4. Pumping of nuclear spins by optical excitation of spin-forbidden transitions in a quantum dot.

    Science.gov (United States)

    Chekhovich, E A; Makhonin, M N; Kavokin, K V; Krysa, A B; Skolnick, M S; Tartakovskii, A I

    2010-02-12

    We demonstrate that efficient optical pumping of nuclear spins in semiconductor quantum dots (QDs) can be achieved by resonant pumping of optically forbidden transitions. This process corresponds to one-to-one conversion of a photon absorbed by the dot into a polarized nuclear spin, and also has potential for initialization of hole spin in QDs. We find that by employing this spin-forbidden process, nuclear polarization of 65% can be achieved, markedly higher than from pumping the allowed transition, which saturates due to the low probability of electron-nuclear spin flip-flop.

  5. Study of structural and optical properties of lead borate glasses containing transition metal ion

    Science.gov (United States)

    Sanjay, Kaushik, A.; Kishore, N.; Agarwal, A.; Pal, I.; Dhar, R.

    2012-06-01

    Glasses with compositions xFe2O3.(40-x)PbO.60B2O3: V2O5 (2 mol%) have been prepared by the standard melt-quenching technique. Various properties such as glass transition temperature, density, IR spectra and optical band gap energy have been studied. The structural changes in these glasses have been monitored by IR spectroscopy. The values of optical band gap for indirect allowed and indirect forbidden transitions have been determined using available theories. The Urbach's energy is used to characterize the degree of disorder in amorphous solids.

  6. ORAL ISSUE OF THE JOURNAL "USPEKHI FIZICHESKIKH NAUK": Transition radiation: scientific implications and applications in high-energy physics

    Science.gov (United States)

    Denisov, Sergei P.

    2007-04-01

    In their pioneering work on transition radiation, Ginzburg and Frank showed for the first time that a charge may radiate electromagnetic waves not only because of its accelerated motion but also because of time variation of the phase velocity of electromagnetic waves in the ambient medium. This result is of very general importance for physics. For example, a charge at rest can radiate in a nonstationary medium. Transition radiation is widely used in high-energy particle detectors, mainly for identification of ultrarelativistic electrons in accelerator and collider experiments.

  7. Optical Real-Time Space Radiation Monitor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Real-time dosimetry is needed to provide immediate feedback, so astronauts can minimize their exposure to ionizing radiation during periods of high solar activity....

  8. Linking optic radiation volume to visual perception in schizophrenia and bipolar disorder.

    Science.gov (United States)

    Reavis, Eric A; Lee, Junghee; Wynn, Jonathan K; Narr, Katherine L; Njau, Stephanie N; Engel, Stephen A; Green, Michael F

    2017-03-16

    People with schizophrenia typically show visual processing deficits on masking tasks and other performance-based measures, while people with bipolar disorder may have related deficits. The etiology of these deficits is not well understood. Most neuroscientific studies of perception in schizophrenia and bipolar disorder have focused on visual processing areas in the cerebral cortex, but perception also depends on earlier components of the visual system that few studies have examined in these disorders. Using diffusion weighted imaging (DWI), we investigated the structure of the primary sensory input pathway to the cortical visual system: the optic radiations. We used probabilistic tractography to identify the optic radiations in 32 patients with schizophrenia, 31 patients with bipolar disorder, and 30 healthy controls. The same participants also performed a visual masking task outside the scanner. We characterized the optic radiations with three structural measures: fractional anisotropy, mean diffusivity, and tract volume. We did not find significant differences in those structural measures across groups. However, we did find a significant correlation between the volume of the optic radiations and visual masking thresholds that was unique to the schizophrenia group and explained variance in masking performance above and beyond that previously accounted for by differences in visual cortex. Thus, individual differences in the volume of the optic radiations explained more variance in visual masking performance in the schizophrenia group than the bipolar or control groups. This suggests that individual differences in the structure of the subcortical visual system have an important influence on visual processing in schizophrenia.

  9. Cerenkov Radiation Energy Transfer (CRET) Imaging: A Novel Method for Optical Imaging of PET Isotopes in Biological Systems: e13300

    National Research Council Canada - National Science Library

    Robin S Dothager; Reece J Goiffon; Erin Jackson; Scott Harpstrite; David Piwnica-Worms

    2010-01-01

    .... Principal Findings To improve optical imaging of Cerenkov radiation in biological systems, we demonstrate that Cerenkov radiation from decay of the PET isotopes 64Cu and 18F can be spectrally coupled...

  10. Radiation-induced optic neuropathy 4 years after radiation: report of a case followed up with MRI

    Energy Technology Data Exchange (ETDEWEB)

    Piquemal, R.; Renard, J.P. [Service de Medecine Interne A, Hopital Bretonneau, Tours (France); Cottier, J.P.; Herbreteau, D. [Service de Neuroradiologie, Hopital Bretonneau, Tours (France); Arsene, S.; Rospars, C. [Service d`Ophthalmologie, Hopital Bretonneau, Tpurs (France); Lioret, E.; Jan, M. [Service de Neurochirurgie, Hopital Bretonneau, Tours (France)

    1998-07-01

    We report a case of radiation-induced optic neuropathy in a 32-year-old man with Cushing`s disease and a recurrent tumour of the left cavernous sinus. The patient experienced rapid, painless loss of vision 4 years after treatment without recurrence of tumour or other visual disorder. MRI showed enlargement and contrast enhancement of the optic chiasm. A year later the patient was almost blind and MRI showed atrophy and persistent contrast enhancement of the chiasm. (orig.) With 3 figs., 13 refs.

  11. Radiation Hard Multi-Layer Optical Coatings Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Next-generation space telescopes require advanced optical coatings to provide low-loss polarization-preserving transmission/reflection of light in a variety of...

  12. Radiation Effects on Ytterbium-doped Optical Fibers

    Science.gov (United States)

    2014-06-02

    response of optical fibers can change 4 drastically depending on a wide variety of intrinsic and extrinsic factors such as the type of optical...a molehill. He kept me focused by consistently reminding me of the joy of teaching and advising that is my reward for completing this dissertation...light at specific wavelengths. The concentration of defects created along with the wavelength of light that is absorbed is dependent upon the intrinsic

  13. A Study on the Response Characteristics of a Fiber-Optic Radiation Sensor Model Based on Cerenkov Principle

    Energy Technology Data Exchange (ETDEWEB)

    Han, Hwa Jeong; Kim, Beom Kyu; Park, Byung Gi [Soonchunhyang Univ., Asan (Korea, Republic of)

    2016-10-15

    In recent year, various fiber-optic radiation sensors using Cerenkov principle have been developed without employing any scintillators for measuring high-energy photon, electron, etc. The main advantages of the optical fibers are the remote transmission of the light signal and immunity to pressure and electromagnetic waves. Therefore, the sensors utilizing the optical fibers can be used in hazardous radiation environments, such as the high-level radiation areas of a nuclear facility. The study to be simulated a fiber-optic radiation sensor based on Cerenkov principle and to be analyzed the response characteristics of the sensor. For the aforementioned study, the GEANT simulation toolkit was used. It is able to take into all the optical properties of fibers and is found to be appropriate to realistically describe the response of fiber-optic radiation sensor. In the recently, the fiber-optic radiation sensor have been developed in nuclear industry. Because sensor can detect gamma ray in harsh nuclear environments. In this study, we analyzed response characteristics of the fiber-optic radiation sensor. We have simulated the Monte Carlo model, for detecting the Cerenkov radiation using the fiber-optic radiation sensor. And the y-axis distribution of Cerenkov photons was obtained using output file. Simulation is performed with reference to the method of the previous research, and then the simulation results exhibited a good agreement with the previous research.

  14. Coherent regime and far-to-near-field transition for radiative heat transfer

    Science.gov (United States)

    Tsurimaki, Yoichiro; Chapuis, Pierre-Olivier; Okajima, Junnosuke; Komiya, Atsuki; Maruyama, Shigenao; Vaillon, Rodolphe

    2017-01-01

    Radiative heat transfer between two semi-infinite parallel media is analyzed in the transition zone between the near-field and the classical macroscopic, i.e. incoherent far-field, regimes of thermal radiation, first for model gray materials and then for real metallic (Al) and dielectric (SiC) materials. The presence of a minimum in the flux-distance curve is observed for the propagative component of the radiative heat transfer coefficient, and in some cases for the total coefficient, i.e. the sum of the propagative and evanescent components. At best this reduction can reach 15% below the far-field limit in the case of aluminum. The far-to-near-field regime taking place for the distance range between the near-field and the classical macroscopic regime involves a coherent far-field regime. One of its limits can be practically defined by the distance at which the incoherent far-field regime breaks down. This separation distance below which the standard theory of incoherent thermal radiation cannot be applied anymore is found to be larger than the usual estimate based on Wien's law and varies as a function of temperature. The aforementioned effects are due to coherence, which is present despite the broadband spectral nature of thermal radiation, and has a stronger impact for reflective materials.

  15. Optical properties of bcc transition metals in the range 0-40 eV

    NARCIS (Netherlands)

    Romaniello, P; de Boeij, PL; Carbone, F; van der Marel, D

    2006-01-01

    We present a systematic analysis of the optical properties of bcc transition metals in the groups VB: V, Nb, and Ta, and VIB: paramagnetic Cr, Mo, and W. For this we use our formulation of time-dependent current-density-functional theory for the linear response of metals. The calculated dielectric a

  16. Optical properties of bcc transition metals in the range 0–40 eV

    NARCIS (Netherlands)

    Romaniello, P.; Boeij, P.L. de; Carbone, F.; Marel, D. van der

    2006-01-01

    We present a systematic analysis of the optical properties of bcc transition metals in the groups VB: V, Nb, and Ta, and VIB: paramagnetic Cr, Mo, and W. For this we use our formulation of time-dependent current-density-functional theory for the linear response of metals. The calculated dielectric a

  17. Optical properties of bcc transition metals in the range 0-40 eV

    NARCIS (Netherlands)

    Romaniello, P.; de Boeij, PL; Carbone, F; van der Marel, D

    We present a systematic analysis of the optical properties of bcc transition metals in the groups VB: V, Nb, and Ta, and VIB: paramagnetic Cr, Mo, and W. For this we use our formulation of time-dependent current-density-functional theory for the linear response of metals. The calculated dielectric

  18. Optical, thermal and phase transition studies in Sn1–GeTe

    Indian Academy of Sciences (India)

    M Sivabharathy; N Sankar; R Saravanan; K Ramachandran

    2005-12-01

    The optical and thermal properties of the mixed semiconducting alloy, Sn1–GeTe, is studied by photo acoustics, for various Ge concentrations and phase transition for a particular concentration is also studied by the same method. The results are compared with the available literature values and discussed.

  19. First-principles characterization of native-defect-related optical transitions in ZnO

    Science.gov (United States)

    Lyons, J. L.; Varley, J. B.; Steiauf, D.; Janotti, A.; Van de Walle, C. G.

    2017-07-01

    We investigate the electrical and optical properties of oxygen vacancies (VO), zinc vacancies (VZn), hydrogenated VZn, and isolated dangling bonds in ZnO using hybrid functional calculations. While the formation energy of VO is high in n-type ZnO, indicating that this center is unlikely to form, our results for optical absorption signals associated with VO are consistent with those observed in irradiated samples, and give rise to emission with a peak at less than 1 eV. Under realistic growth conditions, we find that VZn is the lowest-energy native defect in n-type ZnO, acting as an acceptor that is likely to compensate donor doping. Turning to optical transitions, we first examine NO as a case study, since N-related transitions have been identified in experiments on ZnO. We also examine how hydrogen, often unintentionally present in ZnO, forms stable complexes with VZn and modifies its optical properties. Compared with isolated VZn, VZn-H complexes have charge-state transition levels lower in the band gap as well as have lower formation energies. These complexes also lead to characteristic vibrational frequencies which compare favorably with experiment. Oxygen dangling bonds show behavior mostly consistent with VZn, while zinc dangling bonds give rise to transition levels near the ZnO conduction-band minimum and emission peaking near 2.4 eV. We discuss our results in view of the available experimental literature.

  20. The optical properties of equatorial cirrus in the pilot radiation observation experiment

    Energy Technology Data Exchange (ETDEWEB)

    Platt, C.M.R.; Young, S.A.; Manson, P.; Patterson, G.R. [CSIRO, Victoria (Australia)] [and others

    1996-04-01

    The development of a sensitive filter radiometer for the Atmospheric Radiation Measurement (ARM) Program has been reported. The aim was to develop a reliable and fast instrument that could be used alongside a lidar to obtain near realtime optical properties of clouds, particularly high ice clouds, as they drifted over an ARM Cloud and Radiation Testbed (CART) site allowing calculation of the radiation divergence in the atmosphere over the site. Obtaining cloud optical properties by the lidar/radiometer, or LIRAD, method was described by Platt et al.; the latter paper also describes a year`s data on mid-latitude cirrus. The optical properties of equatorial cirrus (i.e., cirrus within a few degrees of the equator) have hardly been studied at all. The same is true of tropical cirrus, although a few observations have been reported by Davis and Platt et al.This paper describes obersvations performed on cirrus clouds, analysis methods used, and results.

  1. Radiation-Suppressed plasmonic open resonators designed by nonmagnetic transformation optics

    Science.gov (United States)

    Xu, Hongyi; Wang, Xingjue; Yu, Tianyuan; Sun, Handong; Zhang, Baile

    2012-01-01

    How to confine light energy associated with surface plasmon polaritons (SPPs) in a physical space with minimal radiation loss whereas creating maximum interacting section with surrounding environment is of particular interest in plasmonic optics. By virtue of transformation optics, we propose a design method of forming a polygonal surface-plasmonic resonator in fully open structures by applying the nonmagnetic affine transformation optics strategy. The radiation loss can be suppressed because SPPs that propagate in the designed open structures will be deceived as if they were propagating on a flat metal/dielectric interface without radiation. Because of the nonmagnetic nature of the transformation strategy, this design can be implemented with dielectric materials available in nature. An experimentally verifiable model is subsequently proposed for future experimental demonstration. Our design may find potential applications in omnidirectional sensing, light harvesting, energy storage and plasmonic lasing. PMID:23136641

  2. Hyperbaric oxygen in the treatment of radiation-induced optic neuropathy

    Energy Technology Data Exchange (ETDEWEB)

    Guy, J.; Schatz, N.J.

    1986-08-01

    Four patients with radiation-induced optic neuropathies were treated with hyperbaric oxygen. They had received radiation therapy for treatment of pituitary tumors, reticulum cell sarcoma, and meningioma. Two presented with amaurosis fugax before the onset of unilateral visual loss and began hyperbaria within 72 hours after development of unilateral optic neuropathy. Both had return of visual function to baseline levels. The others initiated treatment two to six weeks after visual loss occurred in the second eye and had no significant improvement of vision. Treatment consisted of daily administration of 100% oxygen under 2.8 atmospheres of pressure for 14-28 days. There were no medical complications of hyperbaria. While hyperbaric oxygen is effective in the treatment of radiation-induced optic neuropathy, it must be instituted within several days of deterioration in vision for restoration of baseline function.

  3. Radiation tolerant fiber optic humidity sensors for High Energy Physics applications

    CERN Document Server

    Berruti, Gaia Maria; Cusano, Andrea

    This work is devoted to the development of fiber optic humidity sensors to be applied in high-energy physics applications and in particular in experiments currently running at CERN. The high radiation level resulting from the operation of the accelerator at full luminosity can cause serious performance deterioration of the silicon sensors which are responsible for the particle tracking. To increase their lifetime, the sensors must be kept cold at temperatures below 0 C. At such low temperatures, any condensation risk has to be prevented and a precise thermal and hygrometric control of the air filling and surrounding the tracker detector cold volumes is mandatory. The technologies proposed at CERN for relative humidity monitoring are mainly based on capacitive sensing elements which are not designed with radiation resistance characteristic. In this scenario, fiber optic sensors seem to be perfectly suitable. Indeed, the fiber itself, if properly selected, can tolerate a very high level of radiation, optical fi...

  4. Magnetic field-induced spectroscopy of forbidden optical transitions with application to lattice-based optical atomic clocks.

    Science.gov (United States)

    Taichenachev, A V; Yudin, V I; Oates, C W; Hoyt, C W; Barber, Z W; Hollberg, L

    2006-03-01

    We develop a method of spectroscopy that uses a weak static magnetic field to enable direct optical excitation of forbidden electric-dipole transitions that are otherwise prohibitively weak. The power of this scheme is demonstrated using the important application of optical atomic clocks based on neutral atoms confined to an optical lattice. The simple experimental implementation of this method--a single clock laser combined with a dc magnetic field--relaxes stringent requirements in current lattice-based clocks (e.g., magnetic field shielding and light polarization), and could therefore expedite the realization of the extraordinary performance level predicted for these clocks. We estimate that a clock using alkaline-earth-like atoms such as Yb could achieve a fractional frequency uncertainty of well below 10(-17) for the metrologically preferred even isotopes.

  5. X-Ray Polarization Optics and Coherent Nuclear Resonance Scattering Using Synchrotron Radiation.

    Science.gov (United States)

    Shastri, Sarvjit Devdat

    1995-01-01

    Two projects, both involving X-ray scattering with synchrotron radiation, are presented in this dissertation. (1) A system of diffracting perfect crystals for the generation of variable, elliptically polarized X-rays was tested at the Cornell High Energy Synchrotron Source under the conditions of a standard undulator source. The phase retarding optical component was a 4-bounce, Ge(220) Bragg reflection channel -cut crystal. The full polarization state (density matrix) of the output beam, including the circular polarization purity P_3, was determined using the multiple-beam Bragg diffraction technique with a GaAs crystal polarimeter and was found to agree with calculations. In addition to measuring the optics' efficiency, the ability to scan the system in energy, while frequently reversing the circular helicity, was demonstrated at the vicinity of the Fe K-edge at 7.1 keV. The setup was applied to a circular magnetic X-ray dichroism measurement. (2) The time distribution of delayed photons from resonant forward scattering of 14.4 keV synchrotron radiation pulses by ^{57}Fe nuclei was investigated over the temperature range from 9 K to just above the Curie point at 1043 K, with particular attention to precise measurements of the Lamb-Mossbauer factor f_{LM } ~ e^{- } , whose change was determined from its influence on the "speed-up" of coherent decay. Apart from its importance in Mossbauer effect studies, knowing the temperature dependence of f_{LM} can be valuable for studies of lattice dynamics and structural phase transitions. The change in the nuclear hyperfine splitting was also measured. The synchrotron technique has precision-enhancing advantages over conventional Mossbauer spectroscopy methods employing radioactive sources because dealing with source effects and absolute intensity measurements is eliminated. The results also straightforwardly illustrate an interesting principle concerning the temperature dependence of scattering --that for "slow" resonance

  6. Changes of the optical characteristics of radiochromic films in the transition from EBT3 to EBT-XD films

    Science.gov (United States)

    Schoenfeld, Andreas A.; Wieker, Soeren; Harder, Dietrich; Poppe, Bjoern

    2016-07-01

    A new type of radiochromic film, the EBT-XD film, has been introduced with the aim to reduce the orientation effect and the lateral response artifact occurring in the use of radiochromic films together with flatbed scanners. The task of the present study is to quantify the changes of optical characteristics involved with the transition from the well-known EBT3 films to the new EBT-XD films, using the optical bench arrangement already applied by Schoenfeld et al (2014 Phys. Med. Biol. 59 3575-97). Largely reduced polarization effects and the almost complete loss of the anisotropy of the scattered light produced in a radiation-exposed film have been observed. The Rayleigh-Debye-Gans theory is used to understand these optical changes as arising from the reduced length-to-width ratio of the LiPCDA polymer crystals in the active layer of the EBT-XD film. The effect of these changes on the flatbed scanning artifacts will be shortly addressed, but treated in more detail in a further paper.

  7. Radioactivity measurement of radioactive contaminated soil by using a fiber-optic radiation sensor

    Science.gov (United States)

    Joo, Hanyoung; Kim, Rinah; Moon, Joo Hyun

    2016-06-01

    A fiber-optic radiation sensor (FORS) was developed to measure the gamma radiation from radioactive contaminated soil. The FORS was fabricated using an inorganic scintillator (Lu,Y)2SiO5:Ce (LYSO:Ce), a mixture of epoxy resin and hardener, aluminum foil, and a plastic optical fiber. Before its real application, the FORS was tested to determine if it performed adequately. The test result showed that the measurements by the FORS adequately followed the theoretically estimated values. Then, the FORS was applied to measure the gamma radiation from radioactive contaminated soil. For comparison, a commercial radiation detector was also applied to measure the same soil samples. The measurement data were analyzed by using a statistical parameter, the critical level to determine if net radioactivity statistically different from background was present in the soil sample. The analysis showed that the soil sample had radioactivity distinguishable from background.

  8. Phase Transition and Optical Properties of Solid Oxygen under High Pressure: A Density Functional Theory Study

    Institute of Scientific and Technical Information of China (English)

    LIU Yan-Hui; TIAN Fu-Bo; MA Yan-Ming; HE Zhi; CUI Tian; LIU Bing-Bing; ZOU Guang-Tian

    2008-01-01

    Crystal structures and optical properties of the δ-O,2 phase and the ε-O,8 phase have been investigated by using the ab initio pseudopotential plane-wave method. It is found that the phase transition is of the first order with a discontinuous volumetric change from the antiferromagnetic δ-O,2 phase to the nonmagnetic ε-O8 phase, consistent with the experimental findings. The energy band calculations show that the direct band gap changes into an indirect band gap after the phase transition. The apparent change in the optical properties can be used for identifying the phase transition from δ-O2 to ε-O,8.

  9. Computer modelling of the optical properties of transition-metal ions in solids

    Energy Technology Data Exchange (ETDEWEB)

    Bartram, R.H. [Univ. of Connecticut, Storrs, CT (United States)

    1994-12-31

    Computational methods for modeling the optical properties of substitutional transition-metal impurities in insulating solids, potentially applicable to some scintillator and phosphor materials, are reviewed. Methods considered include crystal-field and semiempirical ligand-field models; SCF-X{alpha}-SW, SCF-RHF-LCAO, SCF-UHF-LCAO and CI ab initio methods; and ICECAP and HADESR embedded-cluster methods with lattice relaxation. A detailed example of the application of the HADESR method to crystal-field spectra of Cr{sup 3+} in halide elpasolites is described. In this method, ab initio molecular-orbital calculations with effective core potentials are performed for selected ionic configurations. Simultaneous relaxation of the cluster and surrounding lattice, with mutual pair-potential interactions, is accomplished by a modified lattice statics program. properties include pressure-dependent optical transition energies, vibration frequencies and radiationless transition rates.

  10. Radiative transitions in InGaN quantum-well structures

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, Noad Asaf [Univ. of California, Berkeley, CA (United States)

    2002-01-01

    InGaN based light emitting devices demonstrate excellent luminescence properties and have great potential in lighting applications. Though these devices are already being produced on an industrial scale, the nature of their radiative transition is still not well understood. In particular, the role of the huge (>1MV/cm), built-in electric field in these transitions is still under debate. The luminescence characteristics of InGaN quantum well structures were investigated as a function of excitation power, temperature, and biaxial strain, with an intent of discerning the effects of the electric field and inhomogeneous indium distribution in the QW on the radiative transition. It was found that the luminescence energy did not scale only with the indium concentration but that the QW thickness must also be taken into account. The thickness affects the transition energy due to quantum confinement and carrier separation across a potential drop in the QW. The luminescence peak width was shown to increase with increased indium fraction, due to increased indium inhomogeneity. The carrier lifetime increased exponentially with QW thickness and luminescence wavelength, due to increased carrier separation. Measuring the luminescence energy and carrier lifetime as a function of excitation density showed that the electric field can be screened by strong excitation and, as a consequence, the carrier separation reduced. The temperature dependence of the luminescence showed evidence for bandtails in the density of states, a phenomenon that has been previously related to transition in indium-rich nano-clusters, yet could be accounted for by fluctuations in other parameters that affect the transition energy. Room temperature luminescence efficiency was shown to weakly decrease with increased QW thickness. The application of biaxial strain resulted in either a redshift or blueshift of the luminescence, depending on the sample. The direction and magnitude of the shift in luminescence

  11. Radiative transitions in InGaN quantum-well structures

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, Noad Asaf

    2002-06-27

    InGaN based light emitting devices demonstrate excellent luminescence properties and have great potential in lighting applications. Though these devices are already being produced on an industrial scale, the nature of their radiative transition is still not well understood. In particular, the role of the huge (>1MV/cm), built-in electric field in these transitions is still under debate. The luminescence characteristics of InGaN quantum well structures were investigated as a function of excitation power, temperature, and biaxial strain, with an intent of discerning the effects of the electric field and inhomogeneous indium distribution in the QW on the radiative transition. It was found that the luminescence energy did not scale only with the indium concentration but that the QW thickness must also be taken into account. The thickness affects the transition energy due to quantum confinement and carrier separation across a potential drop in the QW. The luminescence peak width was shown to increase with increased indium fraction, due to increased indium inhomogeneity. The carrier lifetime increased exponentially with QW thickness and luminescence wavelength, due to increased carrier separation. Measuring the luminescence energy and carrier lifetime as a function of excitation density showed that the electric field can be screened by strong excitation and, as a consequence, the carrier separation reduced. The temperature dependence of the luminescence showed evidence for bandtails in the density of states, a phenomenon that has been previously related to transition in indium-rich nano-clusters, yet could be accounted for by fluctuations in other parameters that affect the transition energy. Room temperature luminescence efficiency was shown to weakly decrease with increased QW thickness. The application of biaxial strain resulted in either a redshift or blueshift of the luminescence, depending on the sample. The direction and magnitude of the shift in luminescence

  12. Changes in the optical absorption induced by sequential exposition to short- and long-wavelength radiation in the BTO:Al crystal

    Science.gov (United States)

    Shandarov, S. M.; Dyu, V. G.; Kisteneva, M. G.; Khudyakova, E. S.; Smirnov, S. V.; Akrestina, A. S.; Kargin, Yu F.

    2017-02-01

    Modifications of the spectral dependences of the optical absorption induced in the Bi12TiO20:Al crystal as a result of sequential exposition to cw laser radiation first with the wavelength λ g = 532 nm and then with the longer wavelength λ l,n = 588, 633, 655, 658, 663, 700, 780, 871, or 1064 nm are investigated. We revealed that after the short-wavelength exposition to radiation with λg = 532 nm, the optical absorption in the crystal increases, and in the range 470–1000 nm, yields the spectrum whose form is independent of a prehistory. The subsequent exposition to longer-wavelength radiation leads to bleaching of the crystal in the examined spectral range. A maximum diminishing of the optical absorption in the crystal is observed upon exposure to radiation with the wavelength λ l,5 = 663 nm. To describe the experimentally observed reversible changes in the optical absorption spectrum in the Bi12TiO20:Al we use the impurity absorption model that takes into account the photoinduced transitions between two metastable states of a deep defect center leading to the change of its position in the crystal lattice under conditions of strong lattice relaxation.

  13. Transition radiation detectors for electron identification beyond 1 GeV/ c

    Science.gov (United States)

    Appuhn, R. D.; Heinloth, K.; Lange, E.; Oedingen, R.; Schlösser, A.

    1988-01-01

    Transition radiation detectors (TRDs) have been tested for the separation of electrons from pions in the momentum range between 1 and 6 GeV/ c. Foams as well as fibres and foils served as radiator materials while two types of chambers, a longitudinal drift chamber (DC) and a multiwire proportional chamber (MWPC), both of 16 mm depth and dominantly filled with xenon, were used for detecting the transition radiation photons with a setup of four chambers. Analyzing the data we compared the methods of mean, truncated mean and of maximum likelihood of the total charge measurements and several methods of cluster analysis. As a result of the total charge measurements performed at test beams at CERN and DESY we obtained about 1% pion contamination at 90% electron efficiency for the polypropylene materials in the configuration of four modules with a total length of 40 cm. An improvement by a factor of about two for the electron/pion discrimination can be obtained in the case of a detailed analysis of the clusters.

  14. Bio-optics of the Chesapeake Bay from measurements and radiative transfer closure

    Science.gov (United States)

    Tzortziou, Maria; Herman, Jay R.; Gallegos, Charles L.; Neale, Patrick J.; Subramaniam, Ajit; Harding, Lawrence W., Jr.; Ahmad, Ziauddin

    2006-06-01

    We combined detailed bio-optical measurements and radiative transfer modeling to perform an 'optical closure' experiment for an optically complex and biologically productive region of the Chesapeake Bay. We used this experiment to evaluate certain assumptions commonly used in bio-optical models, and to investigate which optical characteristics are most important to accurately model and interpret remote sensing ocean-color observations in these Case 2 waters. Direct measurements were made of the magnitude, variability, and spectral characteristics of backscattering and absorption that are critical for accurate parameterizations in satellite bio-optical algorithms and underwater radiative transfer simulations. We found that the ratio of backscattering to total scattering (i.e. the backscattering fraction, bb/ b) varied considerably depending on particulate loading, distance from land, and mixing processes, and had an average value of 0.0128 at 530 nm. Incorporating information on the magnitude, variability, and spectral characteristics of particulate backscattering into the radiative transfer model, rather than using a volume scattering function commonly assumed for turbid waters, was critical to obtaining agreement between model calculations and measured radiometric quantities. In-situ measurements of absorption coefficients need to be corrected for systematic overestimation due to scattering errors, and this correction commonly employs the assumption that absorption by particulate matter at near-infrared wavelengths is zero. Direct measurements, however, showed that particulate matter in the Bay had small, but non-zero, absorption in the 700-730 nm wavelength region. Accounting for this residual particulate absorption when correcting in-situ measured absorption spectra for scattering errors was important in model simulations of water reflectance in the green wavelengths, where reflectance spectra in estuarine waters peak. Sun-induced chlorophyll fluorescence

  15. Moessbauer optics of synchrotron radiation at an isotope interface

    CERN Document Server

    Belyakov, V A

    2000-01-01

    Coherent inelastic Moessbauer scattering (CIMS) of synchrotron radiation (SR) at an isotope interface (plane interface between two regions differing only in the concentration of the Moessbauer isotope) is investigated theoretically. Main attention is paid to the CIMS component resulting from SR quanta absorption by Moessbauer nuclei accompanied by creation or annihilation of the phonons in sample and following recoilless reemission of Moessbauer quanta.

  16. A study of the radiative transition $\\pi \\pi \\to \\pi \\gamma^{*}$ with lattice QCD

    CERN Document Server

    Leskovec, Luka; Koutsou, Giannis; Meinel, Stefan; Negele, John W; Paul, Srijit; Petschlies, Marcus; Pochinsky, Andrew; Rendon, Gumaro; Syritsyn, Sergey

    2016-01-01

    Lattice QCD calculations of radiative transitions between hadrons have in the past been limited to processes of hadrons stable under the strong interaction. Recently developed methods for $1\\to2$ transition matrix elements in a finite volume now enable the determination of radiative decay rates of strongly unstable particles. Our lattice QCD study focuses on the process $\\pi \\pi \\to \\pi \\gamma^{*}$, where the $\\rho$ meson is present as an enhancement in the cross-section. We use $2+1$ flavors of clover fermions at a pion mass of approximately $320$ MeV and a lattice size of approximately $3.6$ fm. The required $2$-point and $3$-point correlation functions are constructed from a set of forward, sequential and stochastic light quark propagators. In addition to determining the $\\rho$ meson resonance parameters via the L\\"uscher method, the scattering phase shift is used in conjunction with the $1\\to2$ transition matrix element formalism of Brice\\~no, Hansen and Walker-Loud to compute the $\\pi\\pi\\to\\pi\\gamma^{*}$...

  17. Radiation-enhanced optical antenna based on nonperiodic metallic nanoparticle dimer chain

    Science.gov (United States)

    Chen, Xiaolin; Yu, Wenhai; Yue, Wencheng; Yao, Peijun; Liu, Wen

    2015-07-01

    With the aid of multi-sphere dyadic Green's function, we present a design of optical nanoantenna which is composed of a nonperiodic nanoparticle dimer chain. By breaking the periodicity of the dimer chain, the radiative emission of the dimer chain is significantly enhanced because the strong coupling which limits radiation enhancement is inhibited when the separations between dimers are reduced. Our work clearly shows the crucial role of nonperiodicity in the design of the Yagi-Uda nanoantenna.

  18. Distributed Optical Fiber Radiation and Temperature Sensing at High Energy Accelerators and Experiments

    CERN Document Server

    AUTHOR|(CDS)2090137; Brugger, Markus

    The aim of this Thesis is to investigate the feasibility of a distributed optical fiber radiation sensing system to be used at high energy physics accelerators and experiments where complex mixed-field environments are present. In particular, after having characterized the response of a selection of radiation sensitive optical fibers to ionizing radiation coming from a 60Co source, the results of distributed optical fiber radiation measurements in a mixed-field environment are presented along with the method to actually estimate the dose variation. This study demonstrates that distributed optical fiber dosimetry in the above mentioned mixed-field radiation environment is feasible, allowing to detect dose variations of about 10-15 Gy with a 1 m spatial resolution. The proof of principle has fully succeeded and we can now tackle the challenge of an industrial installation taking into account that some optimizations need to be done both on the control unit of the system as well as on the choice of the sensing f...

  19. Large-Scale Procurement of Radiation Resistant Single-Mode Optical Fibers for CERN

    CERN Document Server

    Guillermain, Elisa; Kuhnhenn, Jochen; Ricci, Daniel; Weinand, Udo

    2015-01-01

    2400 km of special radiation resistant optical fibres were procured by CERN (European Organization for Nuclear Research), for the installation of more than 55 km of optical fibre cables in the accelerator complex underground during the Long Shutdown 1 (LS1). In the frame of this large-scale industrial production, a thorough quality assurance plan (QAP) was put in place and followed at each step of the process. In-depth qualification of optical fibres preceded the 17-month procurement process. All supplied batches were tested for their resistance to radiation, leading to more than 65 quality control irradiation tests. During the cable assembly process and the installations works, a full traceability down to the optical fibre level was ensured. The actions put in place in the frame of the QAP led to successful installation works and to full respect of the LS1 planning.

  20. Diagnostics of Electron Beams Based on Cherenkov Radiation in an Optical Fiber

    Science.gov (United States)

    Vukolov, A. V.; Novokshonov, A. I.; Potylitsyn, A. P.; Uglov, S. R.

    2017-02-01

    The use of an optical fiber in which Cherenkov radiation is generated instead of a metal wire for scanning a beam profile allows a compact and noise-proof device for diagnostics of charged particle beams in a wide energy range to be developed. Results of experimental investigation of the yield of Vavilov-Cherenkov radiation generated in optical fibers with thickness in the range from 0.125 to 1 mm by electrons with energy of 5.7 MeV are presented.

  1. Confocal acoustic radiation force optical coherence elastography using a ring ultrasonic transducer

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Wenjuan [Beckman Laser Institute, University of California, Irvine, 1002 Health Sciences Road East, Irvine, California 92612 (United States); Department of Chemical Engineering and Materials Science, University of California, Irvine, Irvine, California 92697 (United States); Li, Rui [Beckman Laser Institute, University of California, Irvine, 1002 Health Sciences Road East, Irvine, California 92612 (United States); Ma, Teng; Kirk Shung, K.; Zhou, Qifa [Department of Biomedical Engineering, NIH Ultrasonic Transducer Resource Center, University of Southern California, Los Angeles, California 90089 (United States); Chen, Zhongping, E-mail: z2chen@uci.edu [Beckman Laser Institute, University of California, Irvine, 1002 Health Sciences Road East, Irvine, California 92612 (United States); Department of Chemical Engineering and Materials Science, University of California, Irvine, Irvine, California 92697 (United States); Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92697 (United States)

    2014-03-24

    We designed and developed a confocal acoustic radiation force optical coherence elastography system. A ring ultrasound transducer was used to achieve reflection mode excitation and generate an oscillating acoustic radiation force in order to generate displacements within the tissue, which were detected using the phase-resolved optical coherence elastography method. Both phantom and human tissue tests indicate that this system is able to sense the stiffness difference of samples and quantitatively map the elastic property of materials. Our confocal setup promises a great potential for point by point elastic imaging in vivo and differentiation of diseased tissues from normal tissue.

  2. Interaction of a moving charged particle with a spatially dispersive medium. II. Čerenkov and transition radiation

    NARCIS (Netherlands)

    Hoenders, B.J.; Pattanayak, D.N.

    1976-01-01

    In the preceding paper, we obtained expressions for the electromagnetic field generated by the interaction of a uniformly moving electron with a spatially dispersive half-space. One part of the field was identified with Čerenkov radiation and the other part with transition radiation. In this paper i

  3. Compact metallo-dielectric optical antenna for ultra directional and enhanced radiative emission

    CERN Document Server

    Devilez, Alexis; Stout, Brian

    2010-01-01

    We report the design of highly efficient optical antennas employing a judicious synthesis of metallic and dielectric materials. In the proposed scheme, a pair of metallic coupled nanoparticles permits large enhancements in both excitation strength and radiative decay rates, while a high refractive index dielectric microsphere is employed to efficiently collect light without spoiling the emitter quantum efficiency. Our simulations indicate potential fluorescence rate enhancements of 3 orders of magnitude over the entire optical frequency range.

  4. Compact metallo-dielectric optical antenna for ultra directional and enhanced radiative emission.

    Science.gov (United States)

    Devilez, Alexis; Stout, Brian; Bonod, Nicolas

    2010-06-22

    We report the design of highly efficient optical antennas employing a judicious synthesis of metallic and dielectric materials. In the proposed scheme, a pair of metallic coupled nanoparticles permits large enhancements in both excitation strength and radiative decay rates, while a high refractive index dielectric microsphere is employed to efficiently collect light without spoiling the emitter quantum efficiency. Our simulations indicate potential fluorescence rate enhancements of 3 orders of magnitude over the entire optical frequency range.

  5. Acousto-optic modulation and deflection of terahertz electromagnetic radiation in nonpolar liquids

    Science.gov (United States)

    Nikitin, P. A.; Voloshinov, V. B.; Gerasimov, V. V.; Knyazev, B. A.

    2017-07-01

    The results of a series of experiments on controlled deflection of electromagnetic radiation of a free-electron laser upon diffraction by an acoustic wave in nonpolar liquids are presented. Acoustic and optical properties of liquids that are transparent in the terahertz range are discussed. It is demonstrated that nonpolar liquids may turn out to be a more efficient acousto-optic interaction medium than dielectric crystals or semiconductors.

  6. Internal field induced exciton binding energy and the optical transition in a strained Mg based II–VI quantum well

    Energy Technology Data Exchange (ETDEWEB)

    Elangovan, P. [Department of Physics, Maamallan Institute of Technology, Chennai 602105 (India); John Peter, A., E-mail: a.john.peter@gmail.com [Department of Physics, Government Arts College, Melur 625 106. Madurai (India); Kyoo Yoo, Chang [Center for Environmental Studies/Green Energy Center, Deptartment of Environmental Science and Engineering, College of Engineering, Kyung Hee University, Seocheon-dong 1, Giheung-gu, Yongin-Si, Gyeonggi-Do, 446-701 (Korea, Republic of)

    2013-11-15

    Binding energy of an exciton in a wurtzite ZnO/Zn{sub 1−x}Mg{sub x}O strained quantum well is investigated theoretically in which the strong built-in electric field due to the spontaneous and piezoelectric polarizations is included. Numerical calculations are performed using variational procedure within the single band effective mass approximation by varying the Mg composition in the barrier. The exciton oscillator strength and the exciton lifetime for radiative recombination as functions of well width and Mg content have been computed. The internal field induced interband emission energy of strained ZnO/Zn{sub 1−x}Mg{sub x}O well is investigated with the various structural parameters. The total optical absorption coefficients and the changes of refractive index as a function of normalized photon energy in the presence of built-in internal field are analyzed. The result shows that the strong built-in electric field has influence on the oscillator strength and the recombination life time of the exciton. The optical absorption coefficients and the refractive index changes strongly depend on Mg composition. The occurred blue shift of the resonant peak due to the incorporation of Mg ions will give the information about the variation of two energy levels in the quantum well. -- Highlights: • Binding energy of an exciton in a wurtzite ZnO/Zn{sub 1−x}Mg{sub x}O strained quantum well is investigated. • The built-in internal fields due to the spontaneous and piezoelectric polarizations are included. • The oscillator strength and the exciton lifetime for radiative recombination are computed. • The internal field induced transition energy of strained ZnO/Zn{sub 1−x}Mg{sub x}O well is investigated. • The results show that the nonlinear optical properties strongly depend on Mg composition.

  7. Metal-insulator transition in epitaxial NdNiO3 thin film: A structural, electrical and optical study

    Science.gov (United States)

    Shao, Tao; Qi, Zeming; Wang, Yuyin; Li, Yuanyuan; Yang, Mei; Hu, Chuansheng

    2017-03-01

    NdNiO3 thin film has been prepared by pulsed laser deposition on LaAlO3 (001) single crystalline substrate. Temperature-dependent resistivity measurement shows a sharp metal-insulator transition in such thin film. The phase transition temperature can be tuned from 90 K to 121 K by changing the thickness of thin film. The structure evolution during phase transition is studied by Raman spectroscopy. Optical conductivity reveals that the variation carrier density in the process of phase transition. The results of structural, electrical and optical studies provide useful insights to understand the mechanism of metal-insulator transition of NdNiO3 thin film.

  8. Monitoring of electron bunch length by using Terahertz coherent transition radiation

    Science.gov (United States)

    Su, Xiaolu; Yan, Lixin; Du, Yingchao; Zhang, Zhen; Zhou, Zheng; Wang, Dong; Zheng, Lianmin; Tian, Qili; Huang, Wenhui; Tang, Chuanxiang

    2017-07-01

    In this paper, ultrashort bunch length monitoring was demonstrated based on Terahertz (THz) coherent transition radiation (CTR) in Tsinghua Thomson scattering X-ray (TTX) source. The radiation produced by electron bunch is split into three paths: one of them is used to detect the total energy, while the other two paths are filtered with different THz band-pass filters before detection. The bunch length variation can be obtained by calculating the ratio between the filtered energy and the total energy. The bunch is compressed by a chicane and via changing the current of chicane, the ratio of filtered energy and total energy changed correspondingly. It is a simple supplemental approach to monitor the bunch length during beam conditioning and facility operation. Bunch arrival-time jitter and nonlinear effects in chicane are observed in the experiment during the measurement of filtered energy and total energy.

  9. Performance of the transition radiation detector of the PAMELA space mission

    CERN Document Server

    Ambriola, M

    2002-01-01

    The performance of the transition radiation detector (TRD) of the PAMELA telescope has been studied using beam test data and simulation tools. PAMELA is a satellite-borne magnetic spectrometer designed to measure particles and antiparticles spectra in cosmic rays. The particle identification at high energy will be achieved by combining the measurements by the TRD and a Si-W imaging calorimeter. The TRD is composed of 9 planes of straw tubes, interleaved with carbon fiber radiators. A prototype of the detector has been exposed to particle beams of electrons, pions and muons of various momenta at the CERN-PS and SPS accelerator facilities. In addition a dedicated Monte Carlo code has been developed to simulate the detector. Here we illustrate both simulation results and experimental data analysis procedures and we will discuss the estimated TRD performance. (15 refs).

  10. Ground-based measurements of aerosol optical properties and radiative forcing in North China

    Institute of Scientific and Technical Information of China (English)

    Hongbin Chen; Xiangao Xia; Pucai Wang; Wenxing Zhang

    2007-01-01

    In order to gain an insight into the aerosol properties and their climatic effect over the continental source regions of China, it is of significance to carry out long-term ground-based measurements of aerosol optical properties and radiative forcing. A couple of temporary and permanent Aerosol Robotic Network (AERONET) sites and three comprehensive radiative sites were established in China as a result of international cooperation in recent years. Heavy aerosol loading and significant temporal and spatial variation over North China are revealed by the AERONET data.Aerosol-induced reductions in surface radiation budget are examined on the basis of collocated observations by sun photometers and pyranometers.

  11. NONLINEAR OPTICAL FREQUENCY CONVERTER OF LASER RADIATION ON THE LBO TYPE I CRYSTALS

    Directory of Open Access Journals (Sweden)

    N. V. Kondratyuk

    2014-01-01

    Full Text Available Describes nonlinear optical frequency converter of laser radiation based on the two LBO type I crystals allowing to receive pulses of radiation at three wavelengths of 1064 nm, 532 nm and 355 nm with an adjustable pulse energy. For fine adjustment of the output pulse energy used two dual phase plates that change the orientation of the plane of polarization of the two waves in cascade third harmonic generation. Measured the efficiency of the generation of harmonics of the intensity of radiation at 1064 nm.

  12. Third-Order Nonlinear Optic and Optical Limiting Properties of a Mn(iii) Transition Metal Complex

    Science.gov (United States)

    Karakas, Asli; Elmali, Ayhan; Yahsi, Yasemin; Kara, Hulya

    N,N‧-bis(5-bromosalicylidene)propane-1,2-diamine-O,O‧,N,N‧)-manganese(III) chloride transition metal complex has been synthesized and characterized by elemental analysis and UV-vis spectroscopy. Its crystal structure has been determined using X-ray diffraction analysis. To provide an insight into the optical limiting (OL) behavior of the title compound, the third-order nonlinear optical (NLO) properties, one-photon absorption (OPA) and two-photon absorption (TPA) characterizations have been theoretically investigated by means of the time-dependent Hartree-Fock (TDHF), AM1 and configuration interaction (CI) methods, respectively. According to ab initio calculation results, the examined molecule exhibits second hyperpolarizabilities (γ) with non-zero values at the positions of TPA peaks, implying microscopic third-order optical nonlinearity. The maximum OPA wavelengths recorded by linear optical experiment and quantum mechanical computations are estimated in the UV region to be shorter than 400 nm, showing good optical transparency to the visible light. The TPA cross-sections (δ(ω)) at λ max(2) values indicate that the synthesized compound might possess OL phenomena, which are in accord with the experimental observations on the manganese complexes in the literature.

  13. Observation of coherently enhanced tunable narrow-band terahertz transition radiation from a relativistic sub-picosecond electron bunch train

    Energy Technology Data Exchange (ETDEWEB)

    Piot, P. [Northern Illinois Univ., DeKalb, IL (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Sun, Y. -E [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Maxwell, T. J. [Northern Illinois Univ., DeKalb, IL (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Ruan, J. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Lumpkin, A. H. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Rihaoui, M. M. [Northern Illinois Univ., DeKalb, IL (United States); Thurman-Keup, R. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)

    2011-06-27

    We experimentally demonstrate the production of narrow-band (δf/f ~ =20% at f ~ = 0.5 THz) THz transition radiation with tunable frequency over [0.37, 0.86] THz. The radiation is produced as a train of sub-picosecond relativistic electron bunches transits at the vacuum-aluminum interface of an aluminum converter screen. In addition, we show a possible application of modulated beams to extend the dynamical range of a popular bunch length diagnostic technique based on the spectral analysis of coherent radiation.

  14. Determining optical and radiation characteristics of cathode ray tubes' glass to be reused as radiation shielding glass

    Science.gov (United States)

    Zughbi, A.; Kharita, M. H.; Shehada, A. M.

    2017-07-01

    A new method of recycling glass of Cathode Ray Tubes (CRTs) has been presented in this paper. The glass from CRTs suggested being used as raw materials for the production of radiation shielding glass. Cathode ray tubes glass contains considerable amounts of environmentally hazardous toxic wastes, namely heavy metal oxides such as lead oxide (PbO). This method makes CRTs glass a favorable choice to be used as raw material for Radiation Shielding Glass and concrete. The heavy metal oxides increase its density, which make this type of glass nearly equivalent to commercially available shielding glass. CRTs glass have been characterized to determine heavy oxides content, density, refractive index, and radiation shielding properties for different Gamma-Ray energies. Empirical methods have been used by using the Gamma-Ray source cobalt-60 and computational method by using the code XCOM. Measured and calculated values were in a good compatibility. The effects of irradiation by gamma rays of cobalt-60 on the optical transparency for each part of the CRTs glass have been studied. The Results had shown that some parts of CRTs glass have more resistant to Gamma radiation than others. The study had shown that the glass of cathode ray tubes could be recycled to be used as radiation shielding glass. This proposed use of CRT glass is only limited to the available quantity of CRT world-wide.

  15. Band structure and optical transitions in LaFeO3: theory and experiment.

    Science.gov (United States)

    Scafetta, Mark D; Cordi, Adam M; Rondinelli, James M; May, Steven J

    2014-12-17

    The optical absorption properties of LaFeO(3) (LFO) have been calculated using density functional theory and experimentally measured from several high quality epitaxial films using variable angle spectroscopic ellipsometry. We have analyzed the calculated absorption spectrum using different Tauc models and find the model based on a direct-forbidden transition gives the best agreement with the ab initio band gap energies and band dispersions. We have applied this model to the experimental data and determine the band gap of epitaxial LFO to be ∼2.34 eV, with a slight dependence on strain state. This approach has also been used to analyze the higher indirect transition at ∼3.4 eV. Temperature dependent ellipsometry measurements further confirm our theoretical analysis of the nature of the transitions. This works helps to provide a general approach for accurate determination of band gaps and transition energies in complex oxide materials.

  16. Quantitative identification of dynamical transitions in a semiconductor laser with optical feedback

    Science.gov (United States)

    Quintero-Quiroz, C.; Tiana-Alsina, J.; Romà, J.; Torrent, M. C.; Masoller, C.

    2016-01-01

    Identifying transitions to complex dynamical regimes is a fundamental open problem with many practical applications. Semi- conductor lasers with optical feedback are excellent testbeds for studying such transitions, as they can generate a rich variety of output signals. Here we apply three analysis tools to quantify various aspects of the dynamical transitions that occur as the laser pump current increases. These tools allow to quantitatively detect the onset of two different regimes, low-frequency fluctuations and coherence collapse, and can be used for identifying the operating conditions that result in specific dynamical properties of the laser output. These tools can also be valuable for analyzing regime transitions in other complex systems. PMID:27857229

  17. Modelling radiation emission in the transition from the classical to the quantum regime

    CERN Document Server

    Martins, J L; Grismayer, T; Vieira, J; Fonseca, R A; Silva, L O

    2015-01-01

    An emissivity formula is derived using the generalised Fermi-Weizacker-Williams method of virtual photons which accounts for the recoil the charged particle experiences as it emits radiation. It is found that through this derivation the formula obtained by Sokolov et al using QED perturbation theory is recovered. The corrected emissivity formula is applied to nonlinear Thomson scattering scenarios in the transition from the classical to the quantum regime, for small values of the nonlinear quantum parameter \\chi. Good agreement is found between this method and a QED probabilistic approach for scenarios where both are valid. In addition, signatures of the quantum corrections are identified and explored.

  18. High-energy cosmic-ray electrons - A new measurement using transition-radiation detectors

    Science.gov (United States)

    Hartmann, G.; Mueller, D.; Prince, T.

    1977-01-01

    A new detector for cosmic-ray electrons, consisting of a combination of a transition-radiation detector and a shower detector, has been constructed, calibrated at accelerator beams, and exposed in a balloon flight under 5 g/sq cm of atmosphere. The design of this instrument and the methods of data analysis are described. Preliminary results in the energy range 9-300 GeV are presented. The energy spectrum of electrons is found to be significantly steeper than that of protons, consistent with a long escape lifetime of cosmic rays in the galaxy.

  19. Energy levels, radiative rates and electron impact excitation rates for transitions in Si III

    CERN Document Server

    Aggarwal, K M

    2016-01-01

    Energy levels and radiative rates (A-values) for four types of transitions (E1, E2, M1, and M2) are reported for an astrophysically important Mg-like ion Si~III, whose emission lines have been observed in a variety of plasmas. For the calculations, well-known and widely-used GRASP code has been adopted, and results are listed for transitions among the 141 levels of the 3$\\ell3\\ell'$ and 3$\\ell$4$\\ell$ configurations. Experimental energies are available for only the lowest 58 levels but there is no major discrepancy with theoretical results. Similarly, the A-values and lifetimes show a satisfactory agreement with other available results, particularly for strong E1 transitions. Collision strengths are also calculated, with the DARC code, and listed for resonance transitions over a wide energy range, up to 30~Ryd. No similar results are available in the literature for comparisons. However, comparisons are made with the more important parameter, effective collision strength ($\\Upsilon$), for which recent $R$-matr...

  20. Dielectric function spectra and inter-band optical transitions in TlGaS{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Kawabata, Toshiyuki [Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, Gakuen-cho 1-1, Nakaku, Sakai, Osaka 599-8531 (Japan); Shim, YongGu, E-mail: shim@pe.osakafu-u.ac.jp [Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, Gakuen-cho 1-1, Nakaku, Sakai, Osaka 599-8531 (Japan); Wakita, Kazuki [Department of Electrical, Electronics and Computer Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino 275-0016 (Japan); Mamedov, Nazim [Department of Ellipsometry, Institute of Physics, Azerbaijan National Academy of Sciences, H. Javid Ave. 33, Baku AZ-1143 (Azerbaijan)

    2014-11-28

    TlGaS{sub 2} with a quasi-two-dimensional structure has been accessed by spectroscopic ellipsometry over the 1.5–6.0 eV spectral range. A uniaxial approach applicable to monoclinic TlGaS{sub 2} at room temperature has been employed for ellipsometric data treatment. Principal components of the dielectric function tensor have then been retrieved. Inter-band optical transitions associated with the obtained dielectric function have been determined by using standard critical point analysis. The transitions have been assigned within the electronic band structure obtained for TlGaS{sub 2} from calculations based on density functional theory. - Highlights: • We investigate the dielectric function spectra of TlGaS{sub 2}. • Inter-band optical transition energies are extracted by critical point analysis. • The electronic band structure and the dielectric functions of TlGaS{sub 2} are calculated. • The electronic band states related to the optical transitions are assigned.

  1. Quantum confinement effects on optical transitions in nanodiamonds containing nitrogen vacancies

    Science.gov (United States)

    Petrone, Alessio; Goings, Joshua J.; Li, Xiaosong

    2016-10-01

    Colored nitrogen-vacancy (NV) centers in nanosize diamonds (d ˜5 nm) are promising probe materials because their optical transitions are sensitive to mechanical, vibrational, and spin changes in the surroundings. Here, a linear response time-dependent density functional theory approach is used to describe the optical transitions in several NV-doped diamond quantum dots (QDs) in order to investigate size effects on the absorption spectra. By computing the full optical spectrum up to band-to-band transitions, we analyze both the localized "pinned" midgap and the charge-transfer excitations for an isolated reduced NV center. Subband charge-transfer excitations are shown to be size dependent, involving the excitation of the dopant s p3 electrons to the diamond conduction band. Additionally, the NV-doped systems exhibit characteristic s p3-s p3 excitations whose experimental energies are reproduced well and do not depend on QD size. However, the NV position and global cluster symmetry can affect the amount of the energy splitting of the vertical excitation energies of the midgap transitions.

  2. Anticlastic curvature measurements on unribbed crystal optics for synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Quintana, J.P.; Dolin, Y.; Georgopoulos, P. (DND-CAT Synchrotron Research Center, APS/ANL Sector 5, Building 400, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)); Kushnir, V.I. (APS/XFD, Bldg. 362, 9700 South Cass Ave., Argonne, Illinois 60439 (United States))

    1995-02-01

    Various methods have been proposed for measuring the distortion in perfect crystals using double-crystal methods. The majority of these methods rely on making comparisons between double-crystal rocking curve measurements under the spatial extent of an extended x-ray beam. Unless the beam is large and parallel (such as at a synchrotron bending magnet), these methods are not easily scalable to large crystals (e.g., crystal focusing elements for synchrotron beamlines) due to the mechanical inaccuracies inherent in moving the various optical components. We present a method based on a scanning source which simplifies the problems in scaling double-crystal methods to large optics. In addition, results using this method are presented on a ribless sagittal focusing Si(111) crystal demonstrating that the anticlastic deviation can be made to be less than [plus minus]1 s of arc over a 1-cm-long section parallel to the sagittal axis.

  3. Giant Zeeman shifts in the optical transitions of yttrium iron garnet thin films

    Science.gov (United States)

    Vidyasagar, R.; Alves Santos, O.; Holanda, J.; Cunha, R. O.; Machado, F. L. A.; Ribeiro, P. R. T.; Rodrigues, A. R.; Mendes, J. B. S.; Azevedo, A.; Rezende, S. M.

    2016-09-01

    We report the observation of giant Zeeman shifts in the optical transitions of high-quality very thin films of yttrium iron garnet (YIG) grown by rf sputtering on gadolinium gallium garnet substrates. The optical absorption profile measured with magneto-optical absorption spectroscopy shows dual optical transition in the UV-visible frequency region attributed to transitions from the O-2p valence band to the Fe-3d conduction band and from the O-2p valence band to Fe-2p53d6 excitonic states at the Γ-symmetry point of the YIG band structure. The application of a static magnetic field of only 0.6 kOe produces giant Zeeman shifts of ˜100 meV in the YIG band structure and ˜60 meV in the excitonic states corresponding to effective g-factors on the order of 104. The giant Zeeman effects are attributed to changes in energy levels by the large exchange fields of the Fe-3d orbitals during the magnetization process.

  4. Cavity Optical Pulse Extraction: ultra-short pulse generation as seeded Hawking radiation.

    Science.gov (United States)

    Eilenberger, Falk; Kabakova, Irina V; de Sterke, C Martijn; Eggleton, Benjamin J; Pertsch, Thomas

    2013-01-01

    We show that light trapped in an optical cavity can be extracted from that cavity in an ultrashort burst by means of a trigger pulse. We find a simple analytic description of this process and show that while the extracted pulse inherits its pulse length from that of the trigger pulse, its wavelength can be completely different. Cavity Optical Pulse Extraction is thus well suited for the development of ultrashort laser sources in new wavelength ranges. We discuss similarities between this process and the generation of Hawking radiation at the optical analogue of an event horizon with extremely high Hawking temperature. Our analytic predictions are confirmed by thorough numerical simulations.

  5. Transitional regimes of natural convection in a differentially heated cubical cavity under the effects of wall and molecular gas radiation

    Science.gov (United States)

    Soucasse, L.; Rivière, Ph.; Soufiani, A.; Xin, S.; Le Quéré, P.

    2014-02-01

    The transition to unsteadiness and the dynamics of weakly turbulent natural convection, coupled to wall or gas radiation in a differentially heated cubical cavity with adiabatic lateral walls, are studied numerically. The working fluid is air with small contents of water vapor and carbon dioxide whose infrared spectral radiative properties are modelled by the absorption distribution function model. A pseudo spectral Chebyshev collocation method is used to solve the flow field equations and is coupled to a direct ray tracing method for radiation transport. Flow structures are identified by means of either the proper orthogonal decomposition or the dynamic mode decomposition methods. We first retrieve the classical mechanism of transition to unsteadiness without radiation, characterized by counter-rotating streamwise-oriented vortices generated at the exit of the vertical boundary layers. Wall radiation through a transparent medium leads to a homogenization of lateral wall temperatures and the resulting transition mechanism is similar to that obtained with perfectly conducting lateral walls. The transition is due to an unstable stratification upstream the vertical boundary layers and is characterized by periodically oscillating transverse rolls of axis perpendicular to the main flow. When molecular gas radiation is accounted for, no periodic solution is found and the transition to unsteadiness displays complex structures with chimneys-like rolls whose axes are again parallel to the main flow. The origin of this instability is probably due to centrifugal forces, as suggested previously for the case without radiation. Above the transition to unsteadiness, at Ra = 3 × 108, it is shown that both wall and gas radiation significantly intensify turbulent fluctuations, decrease the thermal stratification in the core of the cavity, and increase the global circulation.

  6. Simultaneous infrared and optical observations of the transiting debris cloud around WD 1145+017

    CERN Document Server

    Zhou, G; Bailey, J; Marshall, J P; Bayliss, D D R; Stockade, C; Nelson, P; Tan, T G; Rodriguez, J E; Tinney, C G; Dragomir, D; Colon, K; Shporer, A; Bento, J; Sefako, R; Horne, K; Cochran, W

    2016-01-01

    We present multi-wavelength photometric monitoring of WD 1145+017, a white dwarf exhibiting periodic dimming events interpreted to be the transits of orbiting, disintegrating planetesimals. Our observations include the first set of near-infrared light curves for the object, obtained on multiple nights over the span of one month, and recorded multiple transit events with depths ranging from ~20% to 50%. Simultaneous near-infrared and optical observations of the deepest and longest duration transit event were obtained at two epochs with the Anglo-Australian Telescope and three optical facilities, over the wavelength range of 0.5-1.2 microns. These observations revealed no measurable difference in transit depths for multiple photometric pass bands, allowing us to place a 2 sigma lower limit of 0.8 microns on the grain size in the putative transiting debris cloud. The lack of small grains is consistent with the infrared excess about the white dwarf, and may point towards a collision-dominated debris disc.

  7. Optical properties and radiation response of Ce{sup 3+}-doped GdScO{sub 3} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yamaji, Akihiro; Fujimoto, Yutaka; Futami, Yoshisuke; Yokota, Yuui; Kurosawa, Shunsuke [Institute of Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Kochurikhin, Vladimir [General Physics Institute, 38 Vavilov Str., 119991 Moscow (Russian Federation); Yanagida, Takayuki [New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Yoshikawa, Akira [Institute of Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

    2012-12-15

    10%-Ce doped GdScO{sub 3} perovskite type single crystal was grown by the Czochralski process. The Ce concentration in the crystal was measured. No impurity phases were observed by powder X-ray diffraction analysis. We evaluated the optical and radiation properties of the grown crystal. Ce:GdScO{sub 3} crystal showed photo- and radio-luminescence peaks due to Ce{sup 3+} of 5d-4f transition and colour centre. The photoluminescence decay time was sub-ns order. The relative light yield under 5.5 MeV alpha-ray excitation was calculated to be approximately 9% of BGO. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Semitransparent curtains for control of optical radiation hazards

    Science.gov (United States)

    Sliney, D. H.; Moss, C. E.; Miller, C. G.; Stephens, J. B.

    1981-01-01

    The purposes and functions of semitransparent eye protective curtains are analyzed. Based upon this analysis, functional requirements are developed, and design requirements are specified for optimum curtains to be used with open arc welding and arc cutting processes. Such curtains also protect against other high intensity broad-spectral-band sources such as compact arc lamps. The requirements for filtering out hazardous UV radiation and blue light must be balanced against the need for transparency in the visible spectrum and the need for reduced glare. Infrared attenuation is shown to be of very little importance.

  9. Radiation-induced effects in polarization-maintaining optical fibers for interferometric gyroscope

    Institute of Scientific and Technical Information of China (English)

    Xueqin Wang; Chunxi Zhang; Jing Jin; Ningfang Song

    2011-01-01

    @@ Radiation-induced attenuation (RIA) in four types of polarization-maintaining optical fibers for interferometric fiberoptic gyroscope (IFOG) at 1310 nm is measured.The measurements are conducted during and after steady-state γ-ray irradiation using a 60Co source in order to observe significantly different RIA behavior and recovery kinetics.Mechanisms involving dopants and manufacturing process are introduced to analyze the RIA discrepancy as well as to guide the choice and hardening of optical fibers during the design of IFOG.Medium-accuracy IFOG using Ge-F-codoped fiber and pure silica core fiber can survive in the space radiation environment.%Radiation-induced attenuation (RIA) in four types of polarization-maintaining optical fibers for interferometric fiberoptic gyroscope (IFOG) at 1310 nm is measured. The measurements are conducted during and after steady-state γ-ray irradiation using a 60Co source in order to observe significantly different RIA behavior and recovery kinetics. Mechanisms involving dopants and manufacturing process are introduced to analyze the RIA discrepancy as well as to guide the choice and hardening of optical fibers during the design of IFOG. Medium-accuracy IFOG using Ge-F-codoped fiber and pure silica core fiber can survive in the space radiation environment.

  10. Retinal damage by optical radiation. An alternative approach to current, ACGIH-inspired guidelines

    NARCIS (Netherlands)

    Vos, J.J.; Norren, D. van

    2005-01-01

    Background: The ACGIH guidelines for protection against retinal damage by optical radiation are often difficult to apply due to their lack of transparency. The less known guidelines by the Netherlands Health Council (HCN), dating from 1978 and updated in 1993, might offer a way out in many cases. Me

  11. Measurement of the optical fiber numeric aperture exposed to thermal and radiation aging

    Science.gov (United States)

    Vanderka, Ales; Bednarek, Lukas; Hajek, Lukas; Latal, Jan; Poboril, Radek; Zavodny, Petr; Vasinek, Vladimir

    2016-12-01

    This paper deals with the aging of optical fibers influenced by temperature and radiation. There are analyzed changes in the structure of the optical fiber, related to the propagation of light in the fiber structure. In this case for numerical aperture. For experimental measurement was used MM fiber OM1 with core diameter 62.5 μm, cladding diameter 125 μm in 2.8 mm secondary coating. Aging of the optical fiber was achieved with dry heat and radiation. For this purpose, we were using a temperature chamber with a stable temperature of 105 °C where the cables after two months. Cables were then irradiated with gamma radiation 60Co in doses of 1.5 kGy and then 60 kGy. These conditions simulated 50 years aging process of optical cables. According to European Standard EN 60793-1-43:2015 was created the automatic device for angular scan working with LabVIEW software interface. Numerical aperture was tested at a wavelength of 850 nm, with an output power 1 mW. Scanning angle was set to 50° with step 0.25°. Numerical aperture was calculated from the position where power has fallen from maximal power at e2 power. The measurement of each sample was performed 10 hours after thermal and radiation aging. The samples were subsequently tested after six months from the last irradiation. In conclusion, the results of the experiment were analyzed and compared.

  12. Hybrid optical-thermal devices and materials for light manipulation and radiative cooling

    CERN Document Server

    Boriskina, Svetlana V; Hsu, Wei-Chun; Weinstein, Lee; Huang, Xiaopeng; Loomis, James; Xu, Yanfei; Chen, Gang

    2015-01-01

    We report on optical design and applications of hybrid meso-scale devices and materials that combine optical and thermal management functionalities owing to their tailored resonant interaction with light in visible and infrared frequency bands. We outline a general approach to designing such materials, and discuss two specific applications in detail. One example is a hybrid optical-thermal antenna with sub-wavelength light focusing, which simultaneously enables intensity enhancement at the operating wavelength in the visible and reduction of the operating temperature. The enhancement is achieved via light recycling in the form of whispering-gallery modes trapped in an optical microcavity, while cooling functionality is realized via a combination of reduced optical absorption and radiative cooling. The other example is a fabric that is opaque in the visible range yet highly transparent in the infrared, which allows the human body to efficiently shed energy in the form of thermal emission. Such fabrics can find...

  13. Optical solar energy adaptations and radiative temperature control of green leaves and tree barks

    Energy Technology Data Exchange (ETDEWEB)

    Henrion, Wolfgang; Tributsch, Helmut [Department of Si-Photovoltaik and Solare Energetik, Hahn-Meitner-Institut Berlin, 14109 Berlin (Germany)

    2009-01-15

    Trees have adapted to keep leaves and barks cool in sunshine and can serve as interesting bionic model systems for radiative cooling. Silicon solar cells, on the other hand, loose up to one third of their energy efficiency due to heating in intensive sunshine. It is shown that green leaves minimize absorption of useful radiation and allow efficient infrared thermal emission. Since elevated temperatures are detrimental for tensile water flow in the Xylem tissue below barks, the optical properties of barks should also have evolved so as to avoid excessive heating. This was tested by performing optical studies with tree bark samples from representative trees. It was found that tree barks have optimized their reflection of incoming sunlight between 0.7 and 2 {mu}m. This is approximately the optical window in which solar light is transmitted and reflected by green vegetation. Simultaneously, the tree bark is highly absorbing and thus radiation emitting between 6 and 10 {mu}m. These two properties, mainly provided by tannins, create optimal conditions for radiative temperature control. In addition, tannins seem to have adopted a function as mediators for excitation energy towards photo-antioxidative activity for control of radiation damage. The results obtained are used to discuss challenges for future solar cell optimization. (author)

  14. Analysis of the blackbody-radiation shift in an ytterbium optical lattice clock

    Science.gov (United States)

    Xu, Yi-Lin; Xu, Xin-Ye

    2016-10-01

    We accurately evaluate the blackbody-radiation shift in a 171Yb optical lattice clock by utilizing temperature measurement and numerical simulation. In this work. three main radiation sources are considered for the blackbody-radiation shift, including the heated atomic oven, the warm vacuum chamber, and the room-temperature vacuum windows. The temperatures on the outer surface of the vacuum chamber are measured during the clock operation period by utilizing seven calibrated temperature sensors. Then we infer the temperature distribution inside the vacuum chamber by numerical simulation according to the measured temperatures. Furthermore, we simulate the temperature variation around the cold atoms while the environmental temperature is fluctuating. Finally, we obtain that the total blackbody-radiation shift is -1.289(7) Hz with an uncertainty of 1.25 × 10-17 for our 171Yb optical lattice clock. The presented method is quite suitable for accurately evaluating the blackbody-radiation shift of the optical lattice clock in the case of lacking the sensors inside the vacuum chamber. Project supported by the National Key Basic Research and Development Program of China (Grant No. 2012CB821302), the National Natural Science Foundation of China (Grant No. 11134003), the National High Technology Research and Development Program of China (Grant No. 2014AA123401), and the Shanghai Excellent Academic Leaders Program of China (Grant No. 12XD1402400).

  15. Distribution measurement of radiation intensity with optical fiber at narrow space

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Chizuo [Nagoya Univ. (Japan). School of Engineering

    1998-07-01

    Recently, in the field or radiation measurement, optical fiber and scintillation fiber are also begun to use. In order to investigate a new application method of the optical fiber to radiation measurement, a lithium compound for neutron converter and a ZnS(Ag) scintillator are kneaded with epoxy type adhesives, and much few weight of them is coated at an end of optical fiber with 1 to 2 mm in diameter, which is further overcoated with black paint or an aluminum cap for its shielding light to produce a thermal neutron detector. The thermal neutron detector is found to be measurable to neutron flux distribution very rapidly and in high position resolution by moving with computer automatically. This method can be measured selctively aimed radiation such as thermal neutron, rapid neutron, {gamma}-ray, and so forth by means of changing the neutron converter. And, the developed fiber method could be widely used for measurement of neutron and {gamma}-ray intensity distribution at fine interval in the nuclear radiation facilities such as neighbors of accelerator facilities, medical radiation facilities. (G.K.)

  16. First-Principles Investigations of the Phase Transition and Optical Properties of Solid Oxygen

    Institute of Scientific and Technical Information of China (English)

    LIU Yan-Hui; DUAN De-Fang; WANG Lian-Cheng; ZHU Chun-Ye; CUI Tian

    2010-01-01

    @@ Using density-functional-theory calculations,a monoclinic metallic post-ζ phase(space group C2/c)is predicted at 215 GPa.The calculated phonon dispersion curves suggest that this structure is stable at least up to 310 GPa.Oxygen rema/ns a molecular crystal and there is no dissociation in the related pressure range.Moreover,it is found that the phase transition from ζ to post-ζ phase is attributed to phonon softening.The significant change in the optical properties can be used to identify the phase transition.

  17. Phase Transition and Superfluid of Photons and Photon Pairs in a Two-Dimensional Optical Microcavity

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jian-Jun; YUAN Jian-Hui; ZHANG Jun-Pei; CHENG Ze

    2012-01-01

    We analyze the ground-state properties and the excitation spectrum of Bose Einstein condensates of photons and PPs in a two-dimensional optical microcavity. First, using the variational method, we discuss the ground- state phase transition of the two-component system. We also investigate the energy gap between the ground state and the first excited state. Moreover, by investigating the excitation spectrum, we also illustrate how the superfluid behavior of photons and PPs can be associated with the phase transition of the system.

  18. Theory of optically forbidden d-d transitions in strongly correlated crystals.

    Science.gov (United States)

    Katsnelson, M I; Lichtenstein, A I

    2010-09-29

    A general multiband formulation of the linear and nonlinear optical response functions for realistic models of correlated crystals is presented. Dipole-forbidden d-d optical transitions originate from vertex functions, which we consider assuming the locality of an irreducible four-leg vertex. The unified formulation for second- and third-order response functions in terms of the three-leg vertex is suitable for practical calculations in solids. We illustrate the general approach by consideration of intra-atomic spin-flip contributions, with an energy of 2J, where J is a Hund exchange, in the simplest two-orbital model.

  19. A linear optical link using radiation hard VCSELs

    CERN Document Server

    Lozano-Bahilo, J; Zsenei, A

    2001-01-01

    A four-channel linear optical link has been developed to enable analogue data transmission in LHC experiments for the analogue front- end chip SCT128A. Signals from a prototype ATLAS SCT module, consisting of 12 cm long silicon strip detectors, connected to six 128 channel SCTA chips, have been transmitted at 40 MHz using the Mitel 4D469 VCSEL and matching PIN diode at a wavelength of 850 nm. Results are presented showing static and dynamic linearity, frequency response and noise. The overall performance of the complete chain is shown for /sup 241/Am spectra. (4 refs).

  20. A promising new mechanism of ionizing radiation detection for positron emission tomography: modulation of optical properties

    Science.gov (United States)

    Tao, Li; Daghighian, Henry M.; Levin, Craig S.

    2016-11-01

    Using conventional scintillation detection, the fundamental limit in positron emission tomography (PET) time resolution is strongly dependent on the inherent temporal variances generated during the scintillation process, yielding an intrinsic physical limit for the coincidence time resolution of around 100 ps. On the other hand, modulation mechanisms of the optical properties of a material exploited in the optical telecommunications industry can be orders of magnitude faster. In this paper we borrow from the concept of optics pump-probe measurement to for the first time study whether ionizing radiation can produce modulations of optical properties, which can be utilized as a novel method for radiation detection. We show that a refractive index modulation of approximately 5× {{10}-6} is induced by interactions in a cadmium telluride (CdTe) crystal from a 511 keV photon source. Furthermore, using additional radionuclide sources, we show that the amplitude of the optical modulation signal varies linearly with both the detected event rate and average photon energy of the radiation source.

  1. Paradoxical reaction in tubercular meningitis resulting in involvement of optic radiation

    Directory of Open Access Journals (Sweden)

    Monga Parveen

    2009-01-01

    Full Text Available A 25-year-old woman was diagnosed to have tubercular meningitis (TBM with a right parietal infarct. She responded well to four-drug anti-tubercular treatment (ATT, systemic steroids and pyridoxine. Steroids were tapered off in one and a half months; she was put on two-drug ATT after two months. Six months after initial diagnosis she presented with sudden, bilateral visual loss. Vision was 3/200 with afferent pupillary defect and un-recordable field in the right eye; vision was 20/60 in the left eye, pupillary reaction was sluggish and the field showed a temporal hemianopia. On reintroduction of systemic corticosteroids vision improved (20/120 in right eye and 20/30 in left eye within three days; the field defects improved sequentially to a left homonymous hemianopia, then a left homonymous inferior quadrantonopia. A diagnosis of TBM, on treatment, with bilateral optic neuritis, and right optic radiation involvement was made. Since the patient had been off ethambutol for four months, the optic neuritis and optic radiation lesion were attributed to a paradoxical reaction to tubercular allergen, corroborated by prompt recovery in response to corticosteroids. This is the first report of optic radiation involvement in a paradoxical reaction in neuro-tuberculosis in a young adult.

  2. Amorphous and crystalline optical materials used as instruments for high gamma radiation doses estimations

    Energy Technology Data Exchange (ETDEWEB)

    Ioan, M-R., E-mail: razvan.ioan@nipne.ro

    2016-06-15

    Highlights: • The damage induced by gamma rays to optical materials was highlighted and quantified, using laser techniques. • Polarized light and the particularities of the laser light (monochromaticity, directionality and coherence) were used. • The correlation between the damage and the gamma rays absorbed dose was made. • The comparison between different types of optical materials and their dose related calibrations were made. • The uncertainty associated to the technique was determined. - Abstract: Nuclear radiation induce some changes to the structure of exposed materials. The main effect of ionizing radiation when interacting with optical materials is the occurrence of color centers, which are quantitatively proportional to the up-taken doses. In this paper, a relation between browning effect magnitude and dose values was found. Using this relation, the estimation of a gamma radiation dose can be done. By using two types of laser wavelengths (532 nm and 633 nm), the optical powers transmitted thru glass samples irradiated to different doses between 0 and 59.1 kGy, were measured and the associated optical browning densities were determined. The use of laser light gives the opportunity of using its particularities: monochromaticity, directionality and coherence. Polarized light was also used for enhancing measurements quality. These preliminary results bring the opportunity of using glasses as detectors for the estimation of the dose in a certain point in space and for certain energy, especially in particles accelerators experiments, where the occurred nuclear reactions are involving the presence of high gamma rays fields.

  3. A new mechanism of ionizing radiation detection for positron emission tomography: modulation of optical properties

    Science.gov (United States)

    Tao, Li; Daghighian, Henry M.; Levin, Craig S.

    2016-10-01

    Using conventional scintillation detection, the fundamental limit in positron emission tomography (PET) annihilation photon pair coincidence time resolution is strongly dependent on the inherent temporal variances generated during the scintillation process, yielding an intrinsic physical limit of around 100 ps. On the other hand, modulation mechanisms of a material's optical properties as exploited in the optical telecommunications industry can be orders of magnitude faster. In this paper we borrow from the concept of optics pump-probe measurement to study whether ionizing radiation can also produce fast modulations of optical properties, which can be utilized as a novel method for radiation detection. We show that a refractive index modulation of approximately 5x10-6 is induced by interactions in a cadmium telluride (CdTe) crystal from a 511 keV photon source. Furthermore, using additional radionuclide sources, we show that the amplitude of the optical modulation signal varies linearly with both the radiation source flux rate and average photon energy.

  4. Aerosol Optical Properties and Its Radiative Forcing over Yulin, China in 2001 and 2002

    Institute of Scientific and Technical Information of China (English)

    CHE Huizheng; ZHANG Xiaoye; Stephane ALFRARO; Bernadette CHATENET; Laurent GOMES; ZHAO Jianqi

    2009-01-01

    The aerosol optical properties and direct radiative forcing over the Mu Us desert of northern China, acquired through a CE318 sunphotometer of the ground-bascd Aerosol Robotic Network (AERONET), are analyzed. The seasonal variations in the aerosol optical properties are examined. The effect of meteorological elements (pressure, temperature, water vapor pressure, relative humidity and wind speed) on the aerosol optical properties is also studied. Then, the sources and optical properties under two different cases, a dust event and a pollution event, are compared. The results show that the high aerosol optical depth (AOD) found in Yulin was mostly attributed to the occurrence of dust events in spring from the Mu Us desert and deserts of West China and Mongolia, as well as the impacts of anthropogenic pollutant particles from the middle part of China in the other seasons. The seasonal variation and the probability distribution of the radiative forcing and the radiative forcing efficiency at the surface and the top of the atmosphere are analyzed and regressed using the linear and Gaussian regression methods.

  5. Transition operators in electromagnetic-wave diffraction theory. II - Applications to optics

    Science.gov (United States)

    Hahne, G. E.

    1993-01-01

    The theory developed by Hahne (1992) for the diffraction of time-harmonic electromagnetic waves from fixed obstacles is briefly summarized and extended. Applications of the theory are considered which comprise, first, a spherical harmonic expansion of the so-called radiation impedance operator in the theory, for a spherical surface, and second, a reconsideration of familiar short-wavelength approximation from the new standpoint, including a derivation of the so-called physical optics method on the basis of quasi-planar approximation to the radiation impedance operator, augmented by the method of stationary phase. The latter includes a rederivation of the geometrical optics approximation for the complete Green's function for the electromagnetic field in the presence of a smooth- and a convex-surfaced perfectly electrically conductive obstacle.

  6. The role of transition radiation in cathodoluminescence imaging and spectroscopy of thin-foils

    Energy Technology Data Exchange (ETDEWEB)

    Mendis, B.G. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Howkins, A. [Experimental Techniques Centre, Brunel University, Uxbridge UB8 3PH (United Kingdom); Stowe, D. [Gatan UK, 25 Nuffield Way, Abingdon, Oxfordshire OX14 1RL (United Kingdom); Major, J.D.; Durose, K. [Stephenson Institute for Renewable Energy, University of Liverpool, Liverpool L69 7ZF (United Kingdom)

    2016-08-15

    There is renewed interest in cathodoluminescence (CL) in the transmission electron microscope, since it can be combined with low energy loss spectroscopy measurements and can also be used to probe defects, such as grain boundaries and dislocations, at high spatial resolution. Transition radiation (TR), which is emitted when the incident electron crosses the vacuum-specimen interface, is however an important artefact that has received very little attention. The importance of TR is demonstrated on a wedge shaped CdTe specimen of varying thickness. For small specimen thicknesses (<250 nm) grain boundaries are not visible in the panchromatic CL image. Grain boundary contrast is produced by electron–hole recombination within the foil, and a large fraction of that light is lost to multiple-beam interference, so that thicker specimens are required before the grain boundary signal is above the TR background. This is undesirable for high spatial resolution. Furthermore, the CL spectrum contains additional features due to TR which are not part of the ‘bulk’ specimen. Strategies to minimise the effects of TR are also discussed. - Highlights: • Grain boundary cathodoluminescence contrast is anomalously low in the TEM. • This is due to transition radiation (TR) generated at the vacuum-specimen interface. • Thick foils are required for the recombination luminescence to suppress TR. • This is undesirable for high spatial resolution analysis of grain boundaries. • Strategies to minimise TR are also discussed.

  7. Straw Performance Studies and Quality Assurance for the ATLAS Transition Radiation Tracker

    CERN Document Server

    Cwetanski, Peter; Orava, Risto

    2006-01-01

    The Transition Radiation Tracker (TRT) of the ATLAS experiment at the LHC is part of the Inner Detector. It is designed as a robust and powerful gaseous detector that provides tracking through individual drift-tubes (straws) as well as particle identification via transition radiation (TR) detection. The straw tubes are operated with Xe-CO2-O2 70/27/3, a gas that combines the advantages of efficient TR absorption, a short electron drift time and minimum ageing effects. The modules of the barrel part of the TRT were built in the United States while the end-cap wheels are assembled at two Russian institutes. Acceptance tests of barrel modules and end-cap wheels are performed at CERN before assembly and integration with the Semiconductor Tracker (SCT) and the Pixel Detector. This thesis first describes simulations the TRT straw tube. The argon-based acceptance gas mixture as well as two xenon-based operating gases are examined for its properties. Drift velocities and Townsend coefficients are computed with the he...

  8. ATLAS Transition Radiation Tracker (TRT): Straw Tube Gaseous Detectors at High Rates

    CERN Document Server

    Vogel, A; The ATLAS collaboration

    2013-01-01

    The ATLAS Transition Radiation Tracker (TRT) is the outermost of the three tracking subsystems of the ATLAS Inner Detector. The ATLAS detector is located at LHC/CERN. We report on how these gaseous detectors (“straw tubes”) are performing during the ATLAS 2011 and 2012 runs where the TRT experiences higher rates than previously encountered. The TRT contains ~300000 thin-walled proportional-mode drift tubes providing on average 30 two-dimensional space points with ~130 µm resolution for charged particle tracks with |η| 0.5 GeV. Along with continuous tracking, the TRT provides electron identification capability through the detection of transition radiation X-ray photons. During the ATLAS 2012 proton-proton data runs, the TRT is operating successfully while being subjected to the highest rates of incident particles ever experienced by a large scale gaseous tracking system. In the second half of 2012, the TRT has collected data in an environment with instantaneous proton-proton luminosity of ~0.8 × 10³�...

  9. ATLAS Transition Radiation Tracker (TRT): Straw Tube Gaseous Detectors at High Rates

    CERN Document Server

    Vogel, A; The ATLAS collaboration

    2013-01-01

    The ATLAS Transition Radiation Tracker (TRT) is the outermost of the three tracking subsystems of the ATLAS Inner Detector. The ATLAS detector is located at LHC/CERN. We report on how these gaseous detectors (“straw tubes”) are performing during the ATLAS 2011 and 2012 runs where the TRT experiences higher rates than previously encountered. The TRT contains ~300000 thin-walled proportional-mode drift tubes providing on average 30 two-dimensional space points with ~130 µm resolution for charged particle tracks with |η|  0.5 GeV. Along with continuous tracking, the TRT provides electron identification capability through the detection of transition radiation X-ray photons. During the ATLAS 2012 proton-proton data runs, the TRT is operating successfully while being subjected to the highest rates of incident particles ever experienced by a large scale gaseous tracking system. As of the submission date of this abstract, the TRT has collected data in an environment with instantaneous proton-proton luminosi...

  10. Photonic chip based optical frequency comb using soliton induced Cherenkov radiation

    CERN Document Server

    Brasch, Victor; Geiselmann, Michael; Lihachev, Grigoriy; Pfeiffer, Martin H P; Gorodetsky, Michael L; Kippenberg, Tobias J

    2014-01-01

    By continuous wave pumping of a dispersion engineered, planar silicon nitride microresonator, continuously circulating, sub-30fs short temporal dissipative solitons are generated, that correspond to pulses of 6 optical cycles and constitute a coherent optical frequency comb in the spectral domain. Emission of soliton induced Cherenkov radiation caused by higher order dispersion broadens the spectral bandwidth to 2/3 of an octave, sufficient for self referencing, in excellent agreement with recent theoretical predictions and the broadest coherent microresonator frequency comb generated to date. The ability to preserve coherence over a broad spectral bandwidth using soliton induced Cherenkov radiation marks a critical milestone in the development of planar optical frequency combs, enabling on one hand application in e.g. coherent communications, broadband dual comb spectroscopy and Raman spectral imaging, while on the other hand significantly relaxing dispersion requirements for broadband microresonator frequen...

  11. Optical design of a high radiative flux solar furnace for Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Riveros-Rosas, D.; Perez-Rabago, C.A.; Arancibia-Bulnes, C.A.; Jaramillo, O.A.; Estrada, C.A. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Av. Xochicalco s/n, A.P. 34, Temixco, 62580 Morelos (Mexico); Herrera-Vazquez, J.; Vazquez-Montiel, S.; Granados-Agustin, F. [Instituto Nacional de Astrofisica, Optica y Electronica, Luis Enrique Erro 1, Tonantzintla, A.P. 216, 72000 Puebla (Mexico); Sanchez-Gonzalez, M. [Centro Nacional de Energias Renovables, Calle Somera 7-9, 28026 Madrid (Spain)

    2010-05-15

    In the present work, the optical design of a new high radiative flux solar furnace is described. Several optical configurations for the concentrator of the system have been considered. Ray tracing simulations were carried out in order to determine the concentrated radiative flux distributions in the focal zone of the system, for comparing the different proposals. The best configuration was chosen in terms of maximum peak concentration, but also in terms of economical and other practical considerations. It consists of an arrangement of 409 first surface spherical facets with hexagonal shape, mounted on a spherical frame. The individual orientation of the facets is corrected in order to compensate for aberrations. The design considers an intercepted power of 30 kW and a target peak concentration above 10,000 suns. The effect of optical errors was also considered in the simulations. (author)

  12. DTI parameters of axonal integrity and demyelination of the optic radiation correlate with glaucoma indices.

    Science.gov (United States)

    Michelson, Georg; Engelhorn, Tobias; Wärntges, Simone; El Rafei, Ahmed; Hornegger, Joachim; Doerfler, Arnd

    2013-01-01

    In glaucoma, damage of retinal ganglion cells may continue to the linked optic radiations. This study investigates the correlation of glaucoma severity indicators with parameters of axonal and myelin integrity of the optic radiations. In this observational case-control study, 13 patients with normal-tension glaucoma, 13 patients with primary open-angle glaucoma, and seven control subjects (mean age, 57.6 ± 12.5 years) were randomly selected for diffusion tensor imaging (DTI) of the optic radiations. The results of the frequency doubling test (FDT) and the HRT-based linear discriminant functions of Burk (BLDF) and Mikelberg (MLDF) were correlated with the mean of the fractional anisotropy (FA), apparent diffusion coefficient (ADC), and radial diffusivity (RD) of the optic radiations. Multiple correlation analysis, corrected for age, stage of cerebral microangiopathy, diagnosis group, and gender was conducted at increasing thresholds of linear anisotropy (C(L)) to reduce mismeasurements because of complex fiber situations. The best correlations were found for BLDF with FA at C(L) threshold 0.3 (0.594, p = 0.001), with ADC at C(L) 0.4 (-0.511, p = 0.005), and with RD at C(L) 0.4 (-0.585, p = 0.001). MLDF correlated with FA at C(L) 0.4 (0.393, p = 0.035). The FDT score correlated with FA at C(L) 0 (-0.491, p = 0.007) and with RD at C(L) 0 (-0.375, p = 0.045). In glaucoma, DTI-derived parameters of the axonal integrity (FA, ADC) and demyelination (RD) of the optic radiation are linked to HRT-based indices of glaucoma severity and to impairment of the spatial-temporal contrast sensitivity.

  13. Brilliant radiation sources by laser-plasma accelerators and optical undulators

    Energy Technology Data Exchange (ETDEWEB)

    Debus, Alexander

    2012-09-06

    This thesis investigates the use of high-power lasers for synchrotron radiation sources with high brilliance, from the EUV to the hard X-ray spectral range. Hereby lasers accelerate electrons by laser-wakefield acceleration (LWFA), act as optical undulators, or both. Experimental evidence shows for the first time that LWFA electron bunches are shorter than the driving laser and have a length scale comparable to the plasma wavelength. Furthermore, a first proof of principle experiment demonstrates that LWFA electrons can be exploited to generate undulator radiation. Building upon these experimental findings, as well as extensive numerical simulations of Thomson scattering, the theoretical foundations of a novel interaction geometry for laser-matter interaction are developed. This new method is very general and when tailored towards relativistically moving targets not being limited by the focusability (Rayleigh length) of the laser, while it does not require a waveguide. In a theoretical investigation of Thomson scattering, the optical analogue of undulator radiation, the limits of Thomson sources in scaling towards higher peak brilliances are highlighted. This leads to a novel method for generating brilliant, highly tunable X-ray sources, which is highly energy efficient by circumventing the laser Rayleigh limit through a novel traveling-wave Thomson scattering (TWTS) geometry. This new method suggests increases in X-ray photon yields of 2-3 orders of magnitudes using existing lasers and a way towards efficient, optical undulators to drive a free-electron laser. The results presented here extend far beyond the scope of this work. The possibility to use lasers as particle accelerators, as well as optical undulators, leads to very compact and energy efficient synchrotron sources. The resulting monoenergetic radiation of high brilliance in a range from extreme ultraviolet (EUV) to hard X-ray radiation is of fundamental importance for basic research, medical

  14. Modeling photosynthesis of discontinuous plant canopies by linking Geometric Optical Radiative Transfer model with biochemical processes

    Science.gov (United States)

    Xin, Q.; Gong, P.; Li, W.

    2015-02-01

    Modeling vegetation photosynthesis is essential for understanding carbon exchanges between terrestrial ecosystems and the atmosphere. The radiative transfer process within plant canopies is one of the key drivers that regulate canopy photosynthesis. Most vegetation cover consists of discrete plant crowns, of which the physical observation departs from the underlying assumption of a homogenous and uniform medium in classic radiative transfer theory. Here we advance the Geometric Optical Radiative Transfer (GORT) model to simulate photosynthesis activities for discontinuous plant canopies. We separate radiation absorption into two components that are absorbed by sunlit and shaded leaves, and derive analytical solutions by integrating over the canopy layer. To model leaf-level and canopy-level photosynthesis, leaf light absorption is then linked to the biochemical process of gas diffusion through leaf stomata. The canopy gap probability derived from GORT differs from classic radiative transfer theory, especially when the leaf area index is high, due to leaf clumping effects. Tree characteristics such as tree density, crown shape, and canopy length affect leaf clumping and regulate radiation interception. Modeled gross primary production (GPP) for two deciduous forest stands could explain more than 80% of the variance of flux tower measurements at both near hourly and daily time scales. We also demonstrate that the ambient CO2 concentration influences daytime vegetation photosynthesis, which needs to be considered in state-of-the-art biogeochemical models. The proposed model is complementary to classic radiative transfer theory and shows promise in modeling the radiative transfer process and photosynthetic activities over discontinuous forest canopies.

  15. Theory of edge-state optical absorption in two-dimensional transition metal dichalcogenide flakes

    Science.gov (United States)

    Trushin, Maxim; Kelleher, Edmund J. R.; Hasan, Tawfique

    2016-10-01

    We develop an analytical model to describe sub-band-gap optical absorption in two-dimensional semiconducting transition metal dichalcogenide (s-TMD) nanoflakes. The material system represents an array of few-layer molybdenum disulfide crystals, randomly orientated in a polymer matrix. We propose that optical absorption involves direct transitions between electronic edge states and bulk bands, depends strongly on the carrier population, and is saturable with sufficient fluence. For excitation energies above half the band gap, the excess energy is absorbed by the edge-state electrons, elevating their effective temperature. Our analytical expressions for the linear and nonlinear absorption could prove useful tools in the design of practical photonic devices based on s-TMDs.

  16. Effective optical Faraday rotations of semiconductor EuS nanocrystals with paramagnetic transition-metal ions.

    Science.gov (United States)

    Hasegawa, Yasuchika; Maeda, Masashi; Nakanishi, Takayuki; Doi, Yoshihiro; Hinatsu, Yukio; Fujita, Koji; Tanaka, Katsuhisa; Koizumi, Hitoshi; Fushimi, Koji

    2013-02-20

    Novel EuS nanocrystals containing paramagnetic Mn(II), Co(II), or Fe(II) ions have been reported as advanced semiconductor materials with effective optical rotation under a magnetic field, Faraday rotation. EuS nanocrystals with transition-metal ions, EuS:M nanocrystals, were prepared by the reduction of the Eu(III) dithiocarbamate complex tetraphenylphosphonium tetrakis(diethyldithiocarbamate)europium(III) with transition-metal complexes at 300 °C. The EuS:M nanocrystals thus prepared were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), inductively coupled plasma atomic emission spectroanalysis (ICP-AES), and a superconducting quantum interference device (SQUID) magnetometer. Enhanced Faraday rotations of the EuS:M nanocrystals were observed around 550 nm, and their enhanced spin polarization was estimated using electron paramagnetic resonance (EPR) measurements. In this report, the magneto-optical relationship between the Faraday rotation efficiency and spin polarization is discussed.

  17. Increased OLED radiative efficiency using a directive optical antenna.

    Science.gov (United States)

    McDaniel, S; Blair, S

    2010-08-02

    We investigate the improvement in efficiency of organic light emitting diodes/displays (OLEDs) by embedding a typical OLED structure within a metallic patch grating resonator. A patch grating resonator is similar to the more familiar Fabry-Perot resonator, except that one mirror of the resonator is a metallic patch grating with a pitch approximately lambda /2 that reduces lateral propagation of radiative emission. FDTD simulations of the proposed structure indicate a potential 71% increase in emitted power over that of a reference OLED structure, and an additional 5% gain from adding an ITO spacer adjacent to the metallic electrode layer (for a total 76% increase). Implementation of this structure requires little to no modification of the OLED manufacturing process.

  18. Statistical optics approach to the design of beamlines for synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, G.; Saldin, E.; Schneidmiller, E.; Yurkov, M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2006-04-15

    In this paper we analyze the image formation problem for undulator radiation through an optical system, accounting for the influence of the electron beam emittance. On the one hand, image formation with Synchrotron Radiation is governed by the laws of Statistical Optics. On the other hand, the widely used Gaussian-Shell model cannot be applied to describe the coherence properties of X-ray beams from third generation Synchrotron Radiation sources. As a result, a more rigorous analysis of coherence properties is required. We propose a technique to explicitly calculate the cross-spectral density of an undulator source, that we subsequently propagate through an optical imaging system. At first we focus on the case of an ideal lens with a non-limiting pupil aperture. Our theory, which makes consistent use of dimensionless analysis, also allows treatment and physical understanding of many asymptotes of the parameter space, together with their applicability region. Particular emphasis is given to the asymptotic situation when the horizontal emittance is much larger than the radiation wavelength, which is relevant for third generation Synchrotron Radiation sources. First principle calculations of undulator radiation characteristics (i.e. ten-dimensional integrals) are then reduced to one-dimensional convolutions of analytical functions with universal functions specific for undulator radiation sources. We also consider the imaging problem for a non-ideal lens in presence of abberations and a limiting pupil aperture, which increases the dimension of the convolution from one to three. In particular we give emphasis to cases when the intensity at the observation plane can be presented as a convolution of an impulse response function and the intensity from an ideal lens. Our results may be used in practical cases as well as in benchmarks for numerical methods.

  19. Nonlinear dynamics of wave packets in PT-symmetric optical lattices near the phase transition point

    CERN Document Server

    Nixon, Sean; Yang, Jianke

    2012-01-01

    Nonlinear dynamics of wave packets in PT-symmetric optical lattices near the phase-transition point are analytically studied. A nonlinear Klein-Gordon equation is derived for the envelope of these wave packets. A variety of novel phenomena known to exist in this envelope equation are shown to also exist in the full equation including wave blowup, periodic bound states and solitary wave solutions.

  20. Evaluation of atomic constants for optical radiation, volume 2

    Science.gov (United States)

    Kylstra, C. D.; Schneider, R. J.

    1974-01-01

    Various atomic constant for 23 elements from helium to mercury were computed and are presented in tables. The data given for each element start with the element name, its atomic number, its ionic state, and the designation and series limit for each parent configuration. This is followed by information on the energy level, parent configuration, and designation for each term available to the program. The matrix elements subtables are ordered by the sequence numbers, which represent the initial and final levels of the transitions. Each subtable gives the following: configuration of the core or parent, designation and energy level for the reference state, effective principal quantum number, energy of the series limit, value of the matrix element for the reference state interacting with itself, and sum of all of the dipole matrix elements listed in the subtable. Dipole and quadrupole interaction data are also given.

  1. Excited meson radiative transitions from lattice QCD using variationally optimized operators

    Energy Technology Data Exchange (ETDEWEB)

    Shultz, Christian J. [Old Dominion Univ., Norfolk, VA (United States); Dudek, Jozef J. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States); Edwards, Robert G. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2015-06-02

    We explore the use of 'optimized' operators, designed to interpolate only a single meson eigenstate, in three-point correlation functions with a vector-current insertion. These operators are constructed as linear combinations in a large basis of meson interpolating fields using a variational analysis of matrices of two-point correlation functions. After performing such a determination at both zero and non-zero momentum, we compute three-point functions and are able to study radiative transition matrix elements featuring excited state mesons. The required two- and three-point correlation functions are efficiently computed using the distillation framework in which there is a factorization between quark propagation and operator construction, allowing for a large number of meson operators of definite momentum to be considered. We illustrate the method with a calculation using anisotopic lattices having three flavors of dynamical quark all tuned to the physical strange quark mass, considering form-factors and transitions of pseudoscalar and vector meson excitations. In conclusion, the dependence on photon virtuality for a number of form-factors and transitions is extracted and some discussion of excited-state phenomenology is presented.

  2. Hot accretion flow with radiative cooling: state transitions in black hole X-ray binaries

    Science.gov (United States)

    Wu, Mao-Chun; Xie, Fu-Guo; Yuan, Ye-Fei; Gan, Zhaoming

    2016-06-01

    We investigate state transitions in black hole X-ray binaries through different parameters by using two-dimensional axisymmetric hydrodynamical simulation method. For radiative cooling in hot accretion flow, we take into account the bremsstrahlung, synchrotron and synchrotron self-Comptonization self-consistently in the dynamics. Our main result is that the state transitions occur when the accretion rate reaches a critical value dot{M} ˜ 3α dot{M}_Edd, above which cold and dense clumpy/filamentary structures are formed, embedded within the hot gas. We argued this mode likely corresponds to the proposed two-phase accretion model, which may be responsible for the intermediate state of black hole X-ray binaries. When the accretion rate becomes sufficiently high, the clumpy/filamentary structures gradually merge and settle down on to the mid-plane. Eventually the accretion geometry transforms to a disc-corona configuration. In summary, our results are consistent with the truncated accretion scenario for the state transition.

  3. Optically induced metal-to-dielectric transition in Epsilon-Near-Zero metamaterials

    CERN Document Server

    Kaipurath, R M; Caspani, L; Roger, T; Clerici, M; Rizza, C; Ciattoni, A; Di Falco, A; Faccio, D

    2016-01-01

    Epsilon-Near-Zero materials exhibit a transition in the real part of the dielectric permittivity from positive to negative value as a function of wavelength. Here we study metal-dielectric layered metamaterials in the homogenised regime (each layer has strongly subwavelength thickness) with zero real part of the permittivity in the near-infrared region. By optically pumping the metamaterial we experimentally show that close to the Epsilon-Equal-to-Zero (EEZ) wavelength the permittivity exhibits a marked transition from metallic (negative permittivity) to dielectric (positive permittivity) as a function of the optical power. Remarkably, this transition is linear as a function of pump power and occurs on time scales of the order of the 100 fs pump pulse that need not be tuned to a specific wavelength. The linearity of the permittivity increase allows us to express the response of the metamaterial in terms of a standard third order optical nonlinearity: this shows a clear inversion of the roles of the real and i...

  4. Spectrophotometric method for optical band gap and electronic transitions determination of semiconductor materials

    Science.gov (United States)

    Sangiorgi, Nicola; Aversa, Lucrezia; Tatti, Roberta; Verucchi, Roberto; Sanson, Alessandra

    2017-02-01

    The optical band gap energy and the electronic processes involved are important parameters of a semiconductor material and it is therefore important to determine their correct values. Among the possible methods, the spectrophotometric is one of the most common. Several methods can be applied to determine the optical band gap energy and still now a defined consensus on the most suitable one has not been established. A highly diffused and accurate optical method is based on Tauc relationship, however to apply this equation is necessary to know the nature of the electronic transitions involved commonly related to the coefficient n. For this purpose, a spectrophotometric technique was used and we developed a graphical method for electronic transitions and band gap energy determination for samples in powder form. In particular, the n coefficient of Tauc equation was determined thorough mathematical elaboration of experimental results on TiO2 (anatase), ZnO, and SnO2. The results were used to calculate the band gap energy values and then compared with the information obtained by Ultraviolet Photoelectron Spectroscopy (UPS). This approach provides a quick and accurate method for band gap determination through n coefficient calculation. Moreover, this simple but reliable method can be used to evaluate the nature of electronic transition that occurs in a semiconductor material in powder form.

  5. Theoretical Investigation of Nonlinear Optical Properties of Organic and Transition Metal Hybrid Azobenzene Dendrimers

    Institute of Scientific and Technical Information of China (English)

    LIU Cai-Ping; LIU Ping; WU Ke-Chen

    2008-01-01

    In this work, we report a theoretical exploration of the responses of organic azo-benzene dendrimers. The polarizabilities, the first and second hyperpolarizabilities of the azobenzene monomers (GO), and the first, second and third generation (G1, G2 and G3, respectively) are investigated by semi-empirical methods. The calculated results show that the nonlinear optical (NLO)properties of these organic dendrimers are mainly determined by the azobenzene chromospheres.Additionally, the values of β and γ increase almost in proportion to the number of chromophores. On the other hand, two types of transition metal hybrid azobenzene dendrimers (core-hybrid and branch-end hybrid according to the sites combined with transition metals) are simulated and discussed in detail in the framework of time-dependent density functional theory (TDDFT). The calculated results reveal that the NLO responses of these metal dendrimers distinctly varied as a result of altering the charge transfer transition scale and the excitation energies.

  6. Using a Semiconductor-to-Metal Transition to Control Optical Transmission through Subwavelength Hole Arrays

    Directory of Open Access Journals (Sweden)

    E. U. Donev

    2008-01-01

    Full Text Available We describe a simple configuration in which the extraordinary optical transmission effect through subwavelength hole arrays in noble-metal films can be switched by the semiconductor-to-metal transition in an underlying thin film of vanadium dioxide. In these experiments, the transition is brought about by thermal heating of the bilayer film. The surprising reverse hysteretic behavior of the transmission through the subwavelength holes in the vanadium oxide suggest that this modulation is accomplished by a dielectric-matching condition rather than plasmon coupling through the bilayer film. The results of this switching, including the wavelength dependence, are qualitatively reproduced by a transfer matrix model. The prospects for effecting a similar modulation on a much faster time scale by using ultrafast laser pulses to trigger the semiconductor-to-metal transition are also discussed.

  7. Phase transitions in ensembles of solitons induced by an optical pumping or a strong electric field

    Science.gov (United States)

    Karpov, P.; Brazovskii, S.

    2016-09-01

    The latest trend in studies of modern electronically and/or optically active materials is to provoke phase transformations induced by high electric fields or by short (femtosecond) powerful optical pulses. The systems of choice are cooperative electronic states whose broken symmetries give rise to topological defects. For typical quasi-one-dimensional architectures, those are the microscopic solitons taking from electrons the major roles as carriers of charge or spin. Because of the long-range ordering, the solitons experience unusual super-long-range forces leading to a sequence of phase transitions in their ensembles: the higher-temperature transition of the confinement and the lower one of aggregation into macroscopic walls. Here we present results of an extensive numerical modeling for ensembles of both neutral and charged solitons in both two- and three-dimensional systems. We suggest a specific Monte Carlo algorithm preserving the number of solitons, which substantially facilitates the calculations, allows to extend them to the three-dimensional case and to include the important long-range Coulomb interactions. The results confirm the first confinement transition, except for a very strong Coulomb repulsion, and demonstrate a pattern formation at the second transition of aggregation.

  8. Investigations in silicate glasses. I. Radiation damage. II. Optical nonlinearity. [Gamma rays and electrons

    Energy Technology Data Exchange (ETDEWEB)

    Moran, M.J.

    1976-11-15

    The investigation of two poorly understood but technologically important physical properties of silicate glasses and related materials is described. The use of Electron Paramagnetic Resonance to investigate the nature of radiation-induced damage in glasses exposed to a variety of high-energy radiation sources is discussed first. Second, the measurement of the nonlinear index of refraction coefficient in a variety of optical materials related to the design of high-power laser systems is described. The radiation damage investigations rely heavily on the comparison of experimental results for different experimental situations. The comparison of EPR lineshapes, absolute spin densities and power saturation behavior is used to probe a variety of microscopic and macroscopic aspects of radiation damage in glasses. Comparison of radiation damage associated with exposure to gamma rays and fast neutrons (and combinations thereof) are interpreted in terms of the microscopic damage mechanisms which are expected to be associated with the specific radiations. Comparison of radiation damage behavior in different types of glasses is also interpreted in terms of the behavior expected for the specific materials. The body of data which is generated is found to be internally self-consistent and is also generally consistent with the radiation damage behavior expected for specific situations. A new and versatile technique for measuring the nonlinear index of refraction coefficient, n/sub 2/, in optical materials is described. The technique utilizes a 1 ns pulsed neodymium-glass laser system and time-resolved interferometry to determine the ratio of the coefficient n/sub 2/ of sample materials to the n/sub 2/ of CS/sub 2/. This method avoids some of the complications associated with performing absolute measurements of n/sub 2/ and allows the use of a relatively simple experimental technique. The measurements determine the nonlinear index ratios of the samples with an accuracy of about

  9. Impact of subgrid-scale radiative heating variability on the stratocumulus-to-trade cumulus transition in climate models

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Heng; Gustafson, William I.; Wang, Hailong

    2014-04-29

    Subgrid-scale interactions between turbulence and radiation are potentially important for accurately reproducing marine low clouds in climate models. To better understand the impact of these interactions, the Weather Research and Forecasting (WRF) model is configured for large eddy simulation (LES) to study the stratocumulus-to-trade cumulus (Sc-to-Cu) transition. Using the GEWEX Atmospheric System Studies (GASS) composite Lagrangian transition case and the Atlantic Trade Wind Experiment (ATEX) case, it is shown that the lack of subgrid-scale turbulence-radiation interaction, as is the case in current generation climate models, accelerates the Sc-to-Cu transition. Our analysis suggests that in cloud-topped boundary layers subgrid-scale turbulence-radiation interactions contribute to stronger production of temperature variance, which in turn leads to stronger buoyancy production of turbulent kinetic energy and helps to maintain the Sc cover.

  10. Investigation of radiative effects of the optically thick dust layer over the Indian tropical region

    Energy Technology Data Exchange (ETDEWEB)

    Das, S.K.; Chen, J.P. [National Taiwan Univ. (China). Dept. of Atmospheric Sciences; Ratnam, M. Venkat; Jayaraman, A. [National Atmospheric Research Laboratory, Tirupati (India)

    2013-06-01

    Optical and physical properties of aerosols derived from multi-satellite observations (MODIS-Aqua, OMI-Aura, MISR-Terra, CALIOP-CALIPSO) have been used to estimate radiative effects of the dust layer over southern India. The vertical distribution of aerosol radiative forcing and heating rates are calculated with 100m resolution in the lower atmosphere, using temperature and relative humidity data from balloon-borne radiosonde observations. The present study investigates the optically thick dust layer of optical thickness 0.18 {+-} 0.06 at an altitude of 2.5 {+-} 0.7 km over Gadanki, transported from the Thar Desert, producing radiative forcing and heating rate of 11.5 {+-} 3.3 W m{sup -2} and 0.6 {+-} 0.26 K day{sup -1}, respectively, with a forcing efficiency of 43 W m{sup -2} and an effective heating rate of 4Kday-1 per unit dust optical depth. Presence of the dust layer increases radiative forcing by 60% and heating rate by 60 times at that altitude compared to nondusty cloud-free days. Calculation shows that the radiative effects of the dust layer strongly depend on the boundary layer aerosol type and mass loading. An increase of 25% of heating by the dust layer is found over relatively cleaner regions than urban regions in southern India and further 15% of heating increases over the marine region. Such heating differences in free troposphere may have significant consequences in the atmospheric circulation and hydrological cycle over the tropical Indian region. (orig.)

  11. Blackbody radiation shift in the Sr optical atomic clock

    CERN Document Server

    Safronova, M S; Safronova, U I; Kozlov, M G; Clark, Charles W

    2012-01-01

    We evaluated the static and dynamic polarizabilities of the 5s^2 ^1S_0 and 5s5p ^3P_0^o states of Sr using the high-precision relativistic configuration interaction + all-order method. Our calculation explains the discrepancy between the recent experimental 5s^2 ^1S_0 - 5s5p ^3P_0^o dc Stark shift measurement \\Delta \\alpha = 247.374(7) a.u. [Middelmann et. al, arXiv:1208.2848 (2012)] and the earlier theoretical result of 261(4) a.u. [Porsev and Derevianko, Phys. Rev. A 74, 020502R (2006)]. Our present value of 247.5 a.u. is in excellent agreement with the experimental result. We also evaluated the dynamic correction to the BBR shift with 1 % uncertainty; -0.1492(16) Hz. The dynamic correction to the BBR shift is unusually large in the case of Sr (7 %) and it enters significantly into the uncertainty budget of the Sr optical lattice clock. We suggest future experiments that could further reduce the present uncertainties.

  12. Latest results on solarization of optical glasses with pulsed laser radiation

    Science.gov (United States)

    Jedamzik, Ralf; Petzold, Uwe

    2017-02-01

    Femtosecond lasers are more and more used for material processing and lithography. Femtosecond laser help to generate three dimensional structures in photoresists without using masks in micro lithography. This technology is of growing importance for the field of backend lithography or advanced packaging. Optical glasses used for beam shaping and inspection tools need to withstand high laser pulse energies. Femtosecond laser radiation in the near UV wavelength range generates solarization effects in optical glasses. In this paper results are shown of femtosecond laser solarization experiments on a broad range of optical glasses from SCHOTT. The measurements have been performed by the Laser Zentrum Hannover in Germany. The results and their impact are discussed in comparison to traditional HOK-4 and UVA-B solarization measurements of the same materials. The target is to provide material selection guidance to the optical designer of beam shaping lens systems.

  13. High accuracy correction of blackbody radiation shift in an optical lattice clock

    CERN Document Server

    Middelmann, Thomas; Lisdat, Christian; Sterr, Uwe

    2012-01-01

    We have determined the frequency shift that blackbody radiation is inducing on the $5s^2$ $^1$S$_0$ -- $5s5p$ $^3$P$_0$ clock transition in strontium. Previously its uncertainty limited the uncertainty of strontium lattice clocks to $1\\times10^{-16}$. Now the uncertainty associated to the black body radiation shift correction translates to $5\\times 10^{-18}$ relative frequency uncertainty at room temperature. Our evaluation is based on a measurement of the differential dc-polarizability of the two clock states and on a modeling of the dynamic contribution using this value and experimental data for other atomic properties.

  14. An optically stimulated luminescence study of porcelain related to radiation dosimetry

    DEFF Research Database (Denmark)

    Poolton, N.R.J.; Bøtter-Jensen, L.; Jungner, H.

    1995-01-01

    This article describes the essential features regarding the photo-stimulated luminescence of porcelain: both the main ceramic and glazing materials are studied. In each case, radiation dose dependent signals are observed, superimposed on dose independent luminescence transitions that are both...... Stokes and anti-Stokes shifted in energy. Glazing is shown in some cases to be considerably more sensitive as a radiation dosemeter than the main porcelain ceramic. By comparison with the properties of artifical phosphors, the principal luminescent matrix is identified as being Al2O3...

  15. Ce-doped SiO2 optical fibers for remote radiation sensing and measurement

    Science.gov (United States)

    Chiodini, Norberto; Vedda, Anna; Fasoli, Mauro; Moretti, Federico; Lauria, Alessandro; Cantone, Marie Claire; Veronese, Ivan; Tosi, Giampiero; Brambilla, Marco; Cannillo, Barbara; Mones, Eleonora; Brambilla, Gilberto; Petrovich, Marco

    2009-05-01

    Scintillating materials, able to convert energy of ionizing radiation into light in the visible-UV interval, are presently used in a wide class of applications such as medical imaging, industrial inspection, security controls and high energy physics detectors. In the last few years we studied and developed a new radiation sensor based on silica-glass fiber-optic technology. In its simplest configuration such device is composed by a short portion (about 10 mm) of scintillating fiber coupled to a photomultiplier through a suitably long passive silica fiber. In this work, we present new results concerning the characterization of silica based Ce and Eu doped fibers glasses obtained by a modified sol-gel method and drawn by a conventional drawing tower for optical fibers. The radio-luminescence of Eu doped fibers is rather weak; moreover it displays a marked sensitivity increase during subsequent irradiations, preventing the use of such fibers in dosimetry. On the other hand Ce-doped fibers show very high radiation hardness, signal stability and reproducibility, and high sensitivity to radiations with energies from 10 keV to several tens of MeV. Numerous tests with photons (X and gamma rays), electrons, and protons have already been successfully performed. At the early stage of its market introduction it is the smallest radiation sensor, also compared to MOSFET and diode technology and it appears to be the ideal choice for in vivo measurements in medical field or remote sensing.

  16. Results of a direct search using synchrotron radiation for the low-energy $^{229}$Th nuclear isomeric transition

    CERN Document Server

    Jeet, Justin; Sullivan, Scott T; Rellergert, Wade G; Mirzadeh, Saed; Cassanho, A; Jenssen, H P; Tkalya, Eugene V; Hudson, Eric R

    2015-01-01

    We report the results of a direct search for the $^{229}$Th ($I^{p} = 3/2^+\\leftarrow 5/2^+$) nuclear isomeric transition, performed by exposing $^{229}$Th-doped LiSrAlF$_6$ crystals to tunable vacuum-ultraviolet synchrotron radiation and observing any resulting fluorescence. We also use existing nuclear physics data to establish a range of possible transition strengths for the isomeric transition. We find no evidence for the thorium nuclear transition between $7.3 \\mbox{eV}$ and $8.8 \\mbox{eV}$ with transition lifetime $(1-2)\\mbox{s} \\lesssim \\tau \\lesssim (2000-5600)\\mbox{s}$. This measurement excludes roughly half of the favored transition search area and can be used to direct future searches.

  17. Results of a Direct Search Using Synchrotron Radiation for the Low-Energy (229)Th Nuclear Isomeric Transition.

    Science.gov (United States)

    Jeet, Justin; Schneider, Christian; Sullivan, Scott T; Rellergert, Wade G; Mirzadeh, Saed; Cassanho, A; Jenssen, H P; Tkalya, Eugene V; Hudson, Eric R

    2015-06-26

    We report the results of a direct search for the (229)Th (I(π)=3/2(+)←5/2(+)) nuclear isomeric transition, performed by exposing (229)Th-doped LiSrAlF(6) crystals to tunable vacuum-ultraviolet synchrotron radiation and observing any resulting fluorescence. We also use existing nuclear physics data to establish a range of possible transition strengths for the isomeric transition. We find no evidence for the thorium nuclear transition between 7.3 eV and 8.8 eV with transition lifetime (1-2) s≲τ≲(2000-5600)  s. This measurement excludes roughly half of the favored transition search area and can be used to direct future searches.

  18. Focusing optics of a parallel beam CCD optical tomography apparatus for 3D radiation gel dosimetry.

    Science.gov (United States)

    Krstajić, Nikola; Doran, Simon J

    2006-04-21

    Optical tomography of gel dosimeters is a promising and cost-effective avenue for quality control of radiotherapy treatments such as intensity-modulated radiotherapy (IMRT). Systems based on a laser coupled to a photodiode have so far shown the best results within the context of optical scanning of radiosensitive gels, but are very slow ( approximately 9 min per slice) and poorly suited to measurements that require many slices. Here, we describe a fast, three-dimensional (3D) optical computed tomography (optical-CT) apparatus, based on a broad, collimated beam, obtained from a high power LED and detected by a charged coupled detector (CCD). The main advantages of such a system are (i) an acquisition speed approximately two orders of magnitude higher than a laser-based system when 3D data are required, and (ii) a greater simplicity of design. This paper advances our previous work by introducing a new design of focusing optics, which take information from a suitably positioned focal plane and project an image onto the CCD. An analysis of the ray optics is presented, which explains the roles of telecentricity, focusing, acceptance angle and depth-of-field (DOF) in the formation of projections. A discussion of the approximation involved in measuring the line integrals required for filtered backprojection reconstruction is given. Experimental results demonstrate (i) the effect on projections of changing the position of the focal plane of the apparatus, (ii) how to measure the acceptance angle of the optics, and (iii) the ability of the new scanner to image both absorbing and scattering gel phantoms. The quality of reconstructed images is very promising and suggests that the new apparatus may be useful in a clinical setting for fast and accurate 3D dosimetry.

  19. Sensitive Detection: Photoacoustics, Thermography, and Optical Radiation Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Diebold, Gerald J. [Brown Univ., Providence, RI (United States)

    2017-04-21

    Research during the granting period has been carried out in several areas concerned with sensitive detection. An infrared pyrometer based on the photoacoustic effect has been developed. The sensitivity of this instrument to temperature differentials has been shown to be 50 mK. An investigation of transients that accompany photoacoustic waves generated by pulsed lasers has been carried out. Experiments have shown the existence of the transients, and a theory based on rapid heat diffusion has been developed. The photoacoustic effect in one dimension is known to increase without bound (in the linear acoustics regime) when an optical beam moves in a fluid at the sound speed. A solution to the wave equation for pressure has been found that describes the photoacoustic effect in a cell where an infrared optical grating moves at the sound speed. It was shown that the amplification effect exists along with a cavity resonance that can be used to great advantage in trace gas detection. The theory of the photoacoustic effect in a structure where the acoustic properties periodically vary in a one-dimensional based has been formulated based on solutions to a Mathieu equation. It was found that it is possible to excite photoacoustic waves within the band gaps to produce large amplitude acoustic waves. The idea of self-oscillation in a photoacoustic cell using a continuous laser has been investigated. A theory has been completed showing that in a compressive wave, the absorption increases as a result of the density increase leading to further absorption and hence an increased amplitude photoacoustic effect with the result that in a resonator, self-oscillation can place. Experiments have been carried out where irradiation of a suspension of absorbing carbon particles with a high power laser has been shown to result in cavitation luminescence. That is, following generation of CO and H2 from the carbon particles through the carbon-steam reaction, an expanding gas bubble is

  20. Magnetic resonance diffusion tensor imaging (MRDTI) of the optic nerve and optic radiations at 3T in children with neurofibromatosis type I (NF-1)

    Energy Technology Data Exchange (ETDEWEB)

    Filippi, Christopher G.; Nickerson, Joshua P. [University of Vermont School of Medicine-FAHC, Department of Radiology, Burlington, VT (United States); Bos, Aaron [University of Vermont School of Medicine, Burlington, VT (United States); Salmela, Michael B. [University of Minnesota School of Medicine, Department of Radiology, Minneapolis, MN (United States); Koski, Chris J. [James Madison University, Department of Political Sciences, Harrisonburg, VA (United States); Cauley, Keith A. [University of Massachusetts Memorial Medical Center, Department of Radiology, Worcester, MA (United States)

    2012-02-15

    Optic pathway glioma (OPG) is a characteristic hallmark of neurofibromatosis type I (NF-I). To evaluate the feasibility of magnetic resonance diffusion tensor imaging (MRDTI) at 3T to detect abnormalities of the optic nerves and optic radiations in children with NF-I. 3-T MRDTI was prospectively performed in 9 children with NF-I (7 boys, 2 girls, average age 7.8 years, range 3-17 years) and 44 controls (25 boys, 19 girls, average age 8.1 years, range 3-17 years). Fractional anisotropy (FA) and mean diffusivity were determined by region-of-interest analysis for the optic nerves and radiations. Statistical analysis compared controls to NF-I patients. Two NF-I patients had bilateral optic nerve gliomas, three had chiasmatic gliomas and four had unidentified neurofibromatosis objects (UNOs) along the optic nerve pathways. All NF-I patients had statistically significant decreases in FA and elevations in mean diffusivity in the optic nerves and radiations compared to age-matched controls. MRDTI can evaluate the optic pathways in children with NF-I. Statistically significant abnormalities were detected in the diffusion tensor metrics of the optic nerves and radiations in children with NF-I compared to age-matched controls. (orig.)

  1. System tests of radiation hard optical links for the ATLAS semiconductor tracker

    CERN Document Server

    Charlton, D G; Homer, R James; Jovanovic, P; Kenyon, Ian Richard; Mahout, G; Shaylor, H R; Wilson, J A; Rudge, A; Fopma, J; Mandic, I; Nickerson, R B; Shield, P; Wastie, R L; Weidberg, A R; Eek, L O; Go, A; Lund-Jensen, B; Pearce, M; Söderqvist, J; Morrissey, M; White, D J

    2000-01-01

    A prototype optical data and timing, trigger and control transmission system based on LEDs and PIN-diodes has been constructed. The system would be suitable in terms of radiation hardness and radiation length for use in the ATLAS semiconductor tracker. Bit error rate measurements were performed for the data links and for the links distributing the timing, trigger and control data from the counting room to the front-end modules. The effects of cross-talk between the emitters and receivers were investigated. The advantages of using vertical cavity surface emitting lasers instead of LEDs are discussed. (5 refs).

  2. Tunable optical lens array using viscoelastic material and acoustic radiation force

    Energy Technology Data Exchange (ETDEWEB)

    Koyama, Daisuke, E-mail: dkoyama@mail.doshisha.ac.jp; Kashihara, Yuta; Matsukawa, Mami [Faculty of Science and Engineering, Doshisha University, 1-3 Tataramiyakodani, Kyotanabe 610-0321 (Japan); Wave Electronics Research Center, Doshisha University, 1-3 Tataramiyakodani, Kyotanabe 610-0321 (Japan); Hatanaka, Megumi [Faculty of Life and Medical Sciences, Doshisha University, 1-3 Tataramiyakodani, Kyotanabe 610-0321 (Japan); Wave Electronics Research Center, Doshisha University, 1-3 Tataramiyakodani, Kyotanabe 610-0321 (Japan); Nakamura, Kentaro [Precision and Intelligence Laboratory, Tokyo Institute of Technology, 4259-R2-26, Nagatsutacho, Midoriku, Yokohama 226-8503 (Japan)

    2015-10-28

    A movable optical lens array that uses acoustic radiation force was investigated. The lens array consists of a glass plate, two piezoelectric bimorph transducers, and a transparent viscoelastic gel film. A cylindrical lens array with a lens pitch of 4.6 mm was fabricated using the acoustic radiation force generated by the flexural vibration of the glass plate. The focal point and the positioning of the lenses can be changed using the input voltage and the driving phase difference between the two transducers, respectively.

  3. Optically erasable samarium-doped fluorophosphate glasses for high-dose measurements in microbeam radiation therapy

    Science.gov (United States)

    Morrell, B.; Okada, G.; Vahedi, S.; Koughia, C.; Edgar, A.; Varoy, C.; Belev, G.; Wysokinski, T.; Chapman, D.; Sammynaiken, R.; Kasap, S. O.

    2014-02-01

    Previous work has demonstrated that fluorophosphate (FP) glasses doped with trivalent samarium (Sm3+) can be used as a dosimetric detector in microbeam radiation therapy (MRT) to measure high radiation doses and large dose variations with a resolution in the micrometer range. The present work addresses the use of intense optical radiation at 405 nm to erase the recorded dose information in Sm3+-doped FP glass plates and examines the underlying physics. We have evaluated both the conversion and optical erasure of Sm3+-doped FP glasses using synchrotron-generated high-dose x-rays at the Canadian Light Source. The Sm-ion valency conversion is accompanied by the appearance of x-ray induced optical absorbance due to the trapping of holes and electrons into phosphorus-oxygen hole (POHC) and electron (POEC) capture centers. Nearly complete Sm2+ to Sm3+ reconversion (erasure) may be achieved by intense optical illumination. Combined analysis of absorbance and electron spin resonance measurements indicates that the optical illumination causes partial disappearance of the POHC and the appearance of new POEC. The suggested model for the observed phenomena is based on the release of electrons during the Sm2+ to Sm3+ reconversion process, the capture of these electrons by POHC (and hence their disappearance), or by PO groups, with the appearance of new and/or additional POEC. Optical erasure may be used as a practical means to erase the recorded data and permits the reuse of these Sm-doped FP glasses in monitoring dose in MRT.

  4. Fiber optic Cerenkov radiation sensor system to estimate burn-up of spent fuel: characteristic evaluation of the system using Co-60 source

    Science.gov (United States)

    Shin, S. H.; Jang, K. W.; Jeon, D.; Hong, S.; Kim, S. G.; Sim, H. I.; Yoo, W. J.; Park, B. G.; Lee, B.

    2013-09-01

    Cerenkov radiation occurs when charged particles are moving faster than the speed of light in a transparent dielectric medium. In optical fibers, the Cerenkov light also can be generated due to their dielectric components. Accordingly, the radiation-induced light signals can be obtained using optical fibers without any scintillating material. In this study, to measure the intensities of Cerenkov radiation induced by gamma-rays, we have fabricated the fiber-optic Cerenkov radiation sensor system using silica optical fibers, plastic optical fibers, multi-anode photomultiplier tubes, and a scanning system. To characterize the Cerenkov radiation generated in optical fibers, the spectra of Cerenkov radiation generated in the silica and plastic optical fibers were measured. Also, the intensities of Cerenkov radiation induced by gamma-rays generated from a cylindrical Co-60 source with or without lead shielding were measured using the fiberoptic Cerenkov radiation sensor system.

  5. Transmission of solar radiation through optical fiber and application to solar beam excited laser

    Energy Technology Data Exchange (ETDEWEB)

    Arashi, Haruo; Kaimai, Atsushi; Ishigame, Mareo

    1987-12-01

    This paper describes the transmission of high density solar radiation through optical fiber and application to a solar beam excited laser. Input solar beam, rendered a high density through a solar collector, is transmitted through optical fiber, and is separated into several fluxes. The fluxes of light are introduced into the side of a cylindrical laser mirror, where the optical fibres are made up into a rectangular form. The transmitted beam, passing through a side slit, excites a rod positioned at the centre of the laser. The separation of a solar collecting and an oscillating portion serves to increase the degree of freedom. The core of the optical fiber is composed of quartz, and a polymer cladding type having a large number of apertures. The input end of the fiber is a heat resistant air-cladding type. The fibre has a transmission of 93%, which is satisfactory for use. The optical excitation system is composed of, in combination, an elliptically cylindrical laser mirror and a cylindrical laser mirror, both of which have an internal surface gold-plated throughout. The output beam from the fiber is multiple-refracted to excite the laser efficiently. When laser beam with low intensity excited by a lamp is made to pass through a crystal of the above excitation system, the intensity is amplified. It is planned that direct laser oscillation is realized by increase of solar radiation intensity. (9 figs, 5 refs)

  6. Radiative Effect of Clouds on Tropospheric Chemistry: Sensitivity to Cloud Vertical Distributions and Optical Properties

    Science.gov (United States)

    Liu, H.; Crawford, J. H.; Pierce, R. B.; Considine, D. B.; Logan, J. A.; Duncan, B. N.; Norris, P.; Platnick, S. E.; Chen, G.; Yantosca, R. M.; Evans, M. J.

    2005-12-01

    Representation of clouds in global models poses a significant challenge since most cloud processes occur on sub-grid scales and must be parameterized. Uncertainties in cloud distributions and optical properties are therefore a limiting factor in model assessments of the radiative effect of clouds on global tropospheric chemistry. We present an analysis of the sensitivity of the radiative effect of clouds to cloud vertical distributions and optical properties with the use of the GEOS-CHEM global 3-D chemistry transport model coupled with the Fast-J radiative transfer algorithm. GEOS-CHEM was driven with a series of meteorological archives (GEOS1-STRAT, GEOS-3, and GEOS-4) generated by the Goddard Earth Observing System data assimilation system (GEOS DAS) at the NASA global Modeling and Assimilation Office (GMAO), which have significantly different cloud optical depths and vertical distributions. The column cloud optical depths in GEOS-3 generally agree with the satellite retrieval products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the International Satellite Cloud Climatology Project (ISCCP) within ±10%, while those in GEOS1-STRAT and GEOS-4 are too low by factors of about 5 and 2, respectively. With respect to vertical distribution, clouds in GEOS-4 are optically much thinner in the tropical upper troposphere compared to those in GEOS1-STRAT and GEOS-3. Assuming linear scaling of cloud optical depth with cloud fraction in a grid-box, our model calculations indicate that the changes in global mean hydroxyl radical (OH) due to the radiative effect of clouds in June are about -1% (GEOS1-STRAT), 1% (GEOS-3), and 14% (GEOS-4), respectively. The effects on global mean OH are similar for GEOS1-STRAT and GEOS-3 due to similar vertical distributions of clouds, even though the column cloud optical depths in the two archives differ by a factor of about 5. Clouds in GEOS-4 have a much larger impact on global mean OH because more solar radiation is

  7. Integrated High-Rate Transition Radiation Detector and Tracking Chamber for the LHC

    CERN Multimedia

    2002-01-01

    % RD-6 \\\\ \\\\Over the past five years, RD-6 has developed a transition radiation detector and charged particle tracker for high rate operation at LHC. The detector elements are based on C-fibre reinforced kapton straw tubes of 4~mm diameter filled with a Xenon gas mixture. Detailed measurements with and without magnetic field have been performed in test beams, and in particular have demonstrated the possibility of operating straw tubes at very high rate (up to 20~MHz) with accurate drift-time measurement accuracy. A full-scale engineering prototype containing 10~000 straws is presently under assembly and will be accurately measured with a powerful X-ray tube. Integrated front-end electronics with fast readout have been designed and successfully operated in test beam. \\\\ \\\\Finally extensive simulations performed for ATLAS have shown that such a detector will provide powerful pattern recognition, accurate momentum measurements, efficient level-2 triggering and excellent electron identification, even at the highe...

  8. A transition radiation detector interleaved with low-density targets for the NOE experiment

    CERN Document Server

    Alexandrov, K V; Bernardini, P; Brigida, M; Campana, D; Candela, A M; Caruso, R; Cassese, F; Ceres, A; D'Aquino, B; De Cataldo, G; De Mitri, I; Di Credico, A; Favuzzi, C; Fusco, P; Gargano, F; Giglietto, N; Giordano, F; Grillo, A; Guarino, F; Gustavino, C; Lamanna, E; Lauro, A; Leone, A; Loparco, F; Mancarella, G; Martello, D; Mazziotta, M N; Mikheyev, S P; Mongelli, M; Osteria, G; Palladino, Vittorio; Passeggio, G; Perchiazzi, M; Pontoniere, G; Rainó, A; Rocco, R; Romanucci, E; Rubizzo, U; Sacchetti, A; Scapparone, E; Spinelli, P; Tikhomirov, V; Vaccina, A; Vanzanella, E; Weber, M

    2001-01-01

    The NOE Collaboration has proposed a transition radiation detector (TRD) interleaved with marble targets to tag the electron decay channel of tau leptons produced by nu /sub tau /, eventually originated by nu /sub mu / oscillations in a long base line experiment. A reduced scale TRD detector prototype has been built and exposed to an electron/pion beam at the CERN PS. Discrimination capabilities between electrons and both charged and neutral pions, representing the main source of background for our measurement, have been determined obtaining rejection factors of the order of the tenth of percent for charged pions, and of a few percent for the neutral pion, matching the experiment requirements. The capabilities of this detector to measure the energy released by particles that start showering inside the targets are shown. A momentum resolution sigma /sub p//P

  9. Intense terahertz pulses from SLAC electron beams using coherent transition radiation.

    Science.gov (United States)

    Wu, Ziran; Fisher, Alan S; Goodfellow, John; Fuchs, Matthias; Daranciang, Dan; Hogan, Mark; Loos, Henrik; Lindenberg, Aaron

    2013-02-01

    SLAC has two electron accelerators, the Linac Coherent Light Source (LCLS) and the Facility for Advanced Accelerator Experimental Tests (FACET), providing high-charge, high-peak-current, femtosecond electron bunches. These characteristics are ideal for generating intense broadband terahertz (THz) pulses via coherent transition radiation. For LCLS and FACET respectively, the THz pulse duration is typically 20 and 80 fs RMS and can be tuned via the electron bunch duration; emission spectra span 3-30 THz and 0.5 THz-5 THz; and the energy in a quasi-half-cycle THz pulse is 0.2 and 0.6 mJ. The peak electric field at a THz focus has reached 4.4 GV/m (0.44 V/Å) at LCLS. This paper presents measurements of the terahertz pulses and preliminary observations of nonlinear materials response.

  10. Cosmic Ray Test of Mini-drift Thick Gas Electron Multiplier Chamber for Transition Radiation Detector

    CERN Document Server

    Yang, S; Buck, B; Li, C; Ljubicic, T; Majka, R; Shao, M; Smirnov, N; Visser, G; Xu, Z; Zhou, Y

    2014-01-01

    A thick gas electron multiplier (THGEM) chamber with an effective readout area of 10$\\times$10 cm$^{2}$ and a 11.3 mm ionization gap has been tested along with two regular gas electron multiplier (GEM) chambers in a cosmic ray test system. The thick ionization gap makes the THGEM chamber a mini-drift chamber. This kind mini-drift THGEM chamber is proposed as part of a transition radiation detector (TRD) for identifying electrons at an Electron Ion Collider (EIC) experiment. Through this cosmic ray test, an efficiency larger than 94$\\%$ and a spatial resolution $\\sim$220 $\\mu$m are achieved for the THGEM chamber at -3.65 kV. Thanks to its outstanding spatial resolution and thick ionization gap, the THGEM chamber shows excellent track reconstruction capability. The gain uniformity and stability of the THGEM chamber are also presented.

  11. Measurement of the energy spectrum of underground muons at Gran Sasso with a transition radiation detector

    CERN Document Server

    Ambrosio, M

    1993-01-01

    We have measured directly the residual energy of cosmic ray muons crossing the MACRO detector at the Gran Sasso Laboratory. For this measurement we have used a transition radiation detector consisting of three identical modules, each of about 12 m^2 area, operating in the energy region from 100 GeV to 1 TeV. The results presented here were obtained with the first module collecting data for more than two years. The average single muon energy is found to be 320 +/- 4 (stat.) +/- 11 (syst.) GeV in the rock depth range 3000-6500 hg/cm^2. The results are in agreement with calculations of the energy loss of muons in the rock above the detector.

  12. Energy cross-calibration from the first CREAM flight: transition radiation detector versus calorimeter

    CERN Document Server

    Maestro, P; Allison, P S; Bagliesi, M G; Beatty, J J; Bigongiari, G; Boyle, P J; Brandt, T J; Childers, J T; Conklin, N B; Coutu, S; Duvernois, M A; Ganel, O; Han, J H; Hyun, H J; Jeon, J A; Kim, K C; Lee, J K; Lee, M H; Lutz, L; Marrocchesi, P S; Malinine, A; Minnick, S; Mognet, S I; Nam, S; Nutter, S; Park, H; Park, I H; Park, N H; Seo, E S; Sina, R; Swordy, S; Wakely, S P; Wu, J; Yang, J; Yoon, Y S; Zei, R; Zinn, S Y

    2010-01-01

    The Cosmic Ray Energetics And Mass (CREAM) balloon experiment had two successful flights in 2004/05 and 2005/06. It was designed to perform energy measurements from a few GeV up to 1000 TeV, taking advantage of different detection techniques. The first instrument, CREAM-1, combined a transition radiation detector with a calorimeter to provide independent energy measurements of cosmicraynuclei. Each detector was calibrated with particle beams in a limited range of energies. In order to assess the absolute energy scale of the instrument and to investigate the systematic effects of each technique, a cross-calibration was performed by comparing the two independent energy estimates on selected samples of oxygen and carbon nuclei.

  13. Performance of the ATLAS Transition Radiation Tracker Readout with High Energy Collisions at the LHC

    CERN Document Server

    Wagner, P; The ATLAS collaboration

    2011-01-01

    The ATLAS Transition Radiation Tracker is the outermost of the three subsystems of the ATLAS Inner Detector. It contributes significantly to the precision of the momentum measurement of charged particles and to the identification of electrons. On the TRT front end electronics this is realized by discriminating the straw signal against two separate thresholds: a low one for tracking and a high one for electron identification. The electronics can also be configured to provide a trigger signal, which has been utilized to build a cosmic ray trigger that became extremely useful for the TRT as well as other subdetectors during ATLAS commissioning. This note will describe the TRT readout electronics and data acquisition, with emphasis on the experience gained during the first years of operation.

  14. Local Signal Processing of the ALICE Transition Radiation Detector at LHC (CERN)

    CERN Document Server

    Gutfleisch, Marcus

    2006-01-01

    The transition radiation detector of the heavy ion experiment ALICE at LHC (CERN) integrates parts of the data acquisition and trigger system. Therefore, a multi chip module has been developped which incorporates two microchips. Detector signals are preamplified and shaped (Preamplifier and Shaper Chip, PASA). Thereafter they are converted from analog to digital and are processed (Tracklet Processing Chip, TRAP). This thesis describes the digital signal processing of the TRAP chip. The input signals are filtered digitally. Then, they are analyzed by a preprocessor and four CPUs with respect to segments of tracks. The thesis covers the complete development from hardware design of filter and preprocessor, their calibration, programming of the CPUs, up to first application studies on a prototype system.

  15. Resonance effects of transition radiation emitted from thin foil stacks using electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Awata, Takaaki; Yajima, Kazuaki; Tanaka, Takashi [Kyoto Univ. (Japan). Faculty of Engineering] [and others

    1997-03-01

    Transition Radiation(TR) X rays are expected to be a high brilliant X-ray source because the interference among TR X rays emitted from many thin foils placed periodically in vacuum can increase their intensity and make them quasi-monochromatic. In order to study the interference (resonance) effects of TR, we measured the energy spectra of TR for several sets of thin-foil stacks at various emission angles. It was found that the resonance effects of TR are classified into intrafoil and interfoil resonances and the intensity of TR X rays increases nonlinearly with increasing foil number, attributing to the interfoil resonance. It became evident that the brilliance of TR is as high as that of SR. (author)

  16. Analogical optical modeling of the asymmetric lateral coherence of betatron radiation.

    Science.gov (United States)

    Paroli, B; Chiadroni, E; Ferrario, M; Potenza, M A C

    2015-11-16

    By exploiting analogical optical modeling of the radiation emitted by ultrarelativistic electrons undergoing betatron oscillations, we demonstrate peculiar properties of the spatial coherence through an interferometric method reminiscent of the classical Young's double slit experiment. The expected effects due to the curved trajectory and the broadband emission are accurately reproduced. We show that by properly scaling the fundamental parameters for the wavelength, analogical optical modeling of betatron emission can be realized in many cases of broad interest. Applications to study the feasibility of future experiments and to the characterization of beam diagnostics tools are described.

  17. On the structural-optical correlations in radiation-modified chalcogenide glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kavetskyy, T; Tsmots, V [Solid State Microelectronics Laboratory, Drohobych Ivan Franko State Pedagogical University, 24 I. Franko Str., Drohobych, 82100 (Ukraine); Kaban, I; Hoyer, W [Institute of Physics, Chemnitz University of Technology, 09107 Chemnitz (Germany); Shpotyuk, O, E-mail: kavetskyy@yahoo.com [Institute of Materials, Scientific Research Company ' Carat' , 202 Stryjska Str., Lviv, 79031 (Ukraine)

    2011-04-01

    In this work, we report our recent results on the gamma-irradiation-induced structural transformations in the Ge-Sb-S glasses as observed from the structural studies using high-energy synchrotron x-ray diffraction and extended x-ray absorption fine structure spectroscopy in comparison with the optical measurements using VIS/IR spectroscopy techniques. The structural-optical correlations in the radiation-induced effects are established. The structural changes upon irradiation are explained in the frames of the concept of coordination topological defects formation.

  18. A case of radiation optic neuropathy after irradiation for pituitary adenoma

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, Masahiro; Sasaki, Ushio; Shinohara, Nobuya; Takeda, Tetsuji; Chaki, Takanori; Nishigakiuchi, Keiji; Kusunoki, Katsusuke (Ehime Prefectural Central Hospital, Matsuyama (Japan))

    1992-05-01

    A 60-year-old woman with radiation optic neuropathy 21 months after irradiation is reported. The patient received a total dose of 50 Gy in 25 fractions for 39 days for pituitary adenoma. She presented with bitemporal hemianopsia and loss of recent memory. Gadolinium-enhanced T1-weighted imaging was very useful for detecting lesions in the optic nerves and chiasm to the hypothalamus including mamillary bodies. Two-month steroid therapy was effective in preventing the disease progression, although visual loss and loss of recent memory were not improved. (N.K.).

  19. Magnetic resonance diffusion tensor imaging-based evaluation of optic-radiation shape and position in meningioma.

    Science.gov (United States)

    Lv, Xueming; Chen, Xiaolei; Xu, Bainan; Zhang, Jiashu; Zheng, Gang; Li, Jinjiang; Li, Fangye; Sun, Guochen

    2012-03-25

    Employing magnetic resonance diffusion tensor imaging, three-dimensional white-matter imaging and conventional magnetic resonance imaging can demonstrate the tumor parenchyma, peritumoral edema and compression on surrounding brain tissue. A color-coded tensor map and three-dimensional tracer diagram were applied to clearly display the optic-radiation location, course and damage. Results showed that the altered anisotropy values of meningioma patients corresponded with optic-radiation shape, size and position on both sides. Experimental findings indicate that the magnetic resonance diffusion tensor imaging technique is a means of tracing and clearly visualizing the optic radiation.

  20. Magnetic resonance diffusion tensor imaging-based evaluation of optic-radiation shape and position in meningioma

    Institute of Scientific and Technical Information of China (English)

    Xueming Lv; Xiaolei Chen; Bainan Xu; Gang Zheng; Jinjiang Li; Fangye Li; Guochen Sun; liusan

    2012-01-01

    Employing magnetic resonance diffusion tensor imaging, three-dimensional white-matter imaging and conventional magnetic resonance imaging can demonstrate the tumor parenchyma, peritumoral edema and compression on surrounding brain tissue. A color-coded tensor map and three-dimensional tracer diagram were applied to clearly display the optic-radiation location, course and damage. Results showed that the altered anisotropy values of meningioma patients corresponded with optic-radiation shape, size and position on both sides. Experimental findings indicate that the magnetic resonance diffusion tensor imaging technique is a means of tracing and clearly visualizing the optic radiation.

  1. The GTC exoplanet transit spectroscopy survey . VII. An optical transmission spectrum of WASP-48b

    Science.gov (United States)

    Murgas, F.; Pallé, E.; Parviainen, H.; Chen, G.; Nortmann, L.; Nowak, G.; Cabrera-Lavers, A.; Iro, N.

    2017-09-01

    Context. Transiting planets offer an excellent opportunity for characterizing the atmospheres of extrasolar planets under very different conditions from those found in our solar system. Aims: We are currently carrying out a ground-based survey to obtain the transmission spectra of several extrasolar planets using the 10 m Gran Telescopio Canarias. In this paper we investigate the extrasolar planet WASP-48b, a hot Jupiter orbiting around an F-type star with a period of 2.14 days. Methods: We obtained long-slit optical spectroscopy of one transit of WASP-48b with the Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS) spectrograph. We integrated the spectrum of WASP-48 and one reference star in several channels with different wavelength ranges, creating numerous color light curves of the transit. We fit analytic transit curves to the data taking into account the systematic effects present in the time series in an effort to measure the change of the planet-to-star radius ratio (Rp/Rs) across wavelength. The change in transit depth can be compared with atmosphere models to infer the presence of particular atomic or molecular compounds in the atmosphere of WASP-48b. Results: After removing the transit model and systematic trends to the curves we reached precisions between 261 ppm and 455-755 ppm for the white and spectroscopic light curves, respectively. We obtained Rp/Rs uncertainty values between 0.8 × 10-3 and 1.5 × 10-3 for all the curves analyzed in this work. The measured transit depth for the curves made by integrating the wavelength range between 530 nm and 905 nm is in agreement with previous studies. We report a relatively flat transmission spectrum for WASP-48b with no statistical significant detection of atmospheric species, although the theoretical models that fit the data more closely include TiO and VO. The transit light curves are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http

  2. Revealing hidden optical transitions with tuneable optical-pump THz-probe spectroscopy

    CERN Document Server

    Novelli, Fabio

    2016-01-01

    While a vast amount of theoretical and experimental approaches can be used to study the band structure of simple solids, the investigation of the electronic properties of high-temperature superconductors and other strongly correlated systems is far less simple. Limitations to both theory and experiments arise from e.g. the many-body nature of the mathematical problem and from the non-trivial surface reconstructions, respectively. Here we propose a novel approach able to reveal energy gaps between band extrema that cannot be identified from the equilibrium optical properties. By combining finely-tunable visible pump pulses with terahertz probe fields, we identify changes to the transient conductivity as the pump wavelength is changed and the density of carriers in different parts of the band structure varies. This approach is demonstrated on a typical semiconductor, undoped silicon, where we identify the band minimum at the $L$ point of the conduction band, corresponding to the second lowest energy indirect ga...

  3. High-Q silica zipper cavity for optical radiation pressure driven MOMS switch

    CERN Document Server

    Tetsumoto, Tomohiro

    2014-01-01

    We design a silica zipper cavity that has high optical and mechanical Q (quality factor) values and demonstrate numerically the feasibility of a radiation pressure driven micro opto-mechanical system (MOMS) directional switch. The silica zipper cavity has an optical Q of 6.0x10^4 and an effective mode volume Vmode of 0.66{\\lambda}^3 when the gap between two cavities is 34 nm. We found that this Q/V_mode value is five times higher than can be obtained with a single nanocavity design. The mechanical Q (Q_m) is determined by thermo-elastic damping and is 2.0x10^6 in a vacuum at room temperature. The opto-mechanical coupling rate g_OM is as high as 100 GHz/nm, which allows us to move the directional cavity-waveguide system and switch 1550-nm light with 770-nm light by controlling the radiation pressure.

  4. Plastic optical fibre sensor for in-vivo radiation monitoring during brachytherapy

    Science.gov (United States)

    Woulfe, P.; Sullivan, F. J.; Lewis, E.; O'Keeffe, S.

    2015-09-01

    An optical fibre sensor is presented for applications in real-time in-vivo monitoring of the radiation dose a cancer patient receives during seed implantation in Brachytherapy. The sensor is based on radioluminescence whereby radiation sensitive scintillation material is embedded in the core of a 1mm plastic optical fibre. Three scintillation materials are investigated: thallium-doped caesium iodide (CsI:Tl), terbium-doped gadolinium oxysulphide (Gd2O2S:Tb) and europium-doped lanthanum oxysulphide (La2O2S:Eu). Terbium-doped gadolinium oxysulphide was identified as being the most suitable scintillator and further testing demonstrates its measureable response to different activities of Iodine-125, the radio-active source commonly used in Brachytherapy for treating prostate cancer.

  5. Aging and Gas Filtration Studies in the ATLAS Transition Radiation Tracker

    CERN Document Server

    Sprachmann, Gerald; Störi, Herbert

    2006-01-01

    The Transition Radiation Tracker (TRT) is one of three particle tracking detectors of the ATLAS Inner Detector whose goal is to exploit the highly exciting new physics potential at CERN's next accelerator, the so-called Large Hadron Collider (LHC). The TRT consists of 370000 straw proportional tubes of 4 mm diameter with a 30 micron anode wire, which will be operated with a Xe/CO2/O2 gas mixture at a high voltage of approximately 1.5 kV. This detector enters a new area that requires it to operate at unprecedented high rates and integrated particle fluxes. Full functionality of the detector over the lifetime (10 years) of the experiment is demanded. Aging of gaseous detectors is a term for the degradation of detector performance during exposure to ionizing radiation. This phenomenon involves very complex physical and chemical processes that are induced by pollution originating from very small amounts of silicon-based substances in some components of the gas system. This work presents a review of previous aging...

  6. Energy levels, radiative rates and electron impact excitation rates for transitions in Al X

    CERN Document Server

    Aggarwal, K M

    2013-01-01

    Energy levels, radiative rates and lifetimes are calculated among the lowest 98 levels of the n <= 4 configurations of Be-like Al X. The GRASP (General-purpose Relativistic Atomic Structure Package) is adopted and data are provided for all E1, E2, M1 and M2 transitions. Similar data are also obtained with the Flexible Atomic Code (FAC) to assess the accuracy of the calculations. Based on comparisons between calculations with the two codes as well as with available measurements, our listed energy levels are assessed to be accurate to better than 0.3%. However, the accuracy for radiative rates and lifetimes is estimated to be about 20%. Collision strengths are also calculated for which the Dirac Atomic R-matrix Code (DARC) is used. A wide energy range (up to 380 Ryd) is considered and resonances resolved in a fine energy mesh in the thresholds region. The collision strengths are subsequently averaged over a Maxwellian velocity distribution to determine effective collision strengths up to a temperature of 1.6...

  7. Construction of an end-cap module prototype for the ATLAS transition radiation tracker

    CERN Document Server

    Danielsson, H

    2000-01-01

    We have designed, built and tested an 8-plane module prototype for the end-cap of the ATLAS TRT (Transition Radiation Tracker). The overall mechanics as well as the detailed design of individual components are presented. The prototype contains over 6000 straw tubes with a diameter of 4 mm, filled with an active gas mixture of 70% Xe, 20% CF4 and 10% CO//2. Very tight requirements on radiation hardness (10 Mrad and 2 multiplied by l0**1**4 neutrons per cm**2) straw straightness (sagitta less than 300 m), wire positions and leak tightness put great demands upon design and assembly. In order to verify the design, the stability of the wire tension, straw straightness, high-voltage performance and total leak rate have been measured and the results are presented. Some examples of dedicated assembly tooling and testing procedures are also given. Finally, the results of the calculations and measurements of both mechanical behaviour and wire offset are presented. 6 Refs.

  8. Spin-flip processes and radiative decay of dark intravalley excitons in transition metal dichalcogenide monolayers

    Science.gov (United States)

    Slobodeniuk, A. O.; Basko, D. M.

    2016-09-01

    We perform a theoretical study of radiative decay of dark intravalley excitons in transition metal dichalcogenide monolayers. This decay necessarily involves an electronic spin flip. The intrinsic decay mechanism due to interband spin-flip dipole moment perpendicular to the monolayer plane, gives a rate about 100-1000 times smaller than that of bright excitons. However, we find that this mechanism also introduces an energy splitting due to a local field effect, and the whole oscillator strength is contained in the higher-energy component, while the lowest-energy state remains dark and needs an extrinsic spin-flip mechanism for the decay. Rashba effect due to a perpendicular electric field or a dielectric substrate, gives a negligible radiative decay rate (about 107 times slower than that of bright excitons). Spin flip due to Zeeman effect in a sufficiently strong in-plane magnetic field can give a decay rate comparable to that due to the intrinsic interband spin-flip dipole.

  9. Aging and Gas Filtration Studies in the ATLAS Transition Radiation Tracker

    CERN Document Server

    Sprachmann, Gerald; Störi, Herbert

    2006-01-01

    The Transition Radiation Tracker (TRT) is one of three particle tracking detectors of the ATLAS Inner Detector whose goal is to exploit the highly exciting new physics potential at CERN's next accelerator, the so-called Large Hadron Collider (LHC). The TRT consists of 370000 straw proportional tubes of 4 mm diameter with a 30 micron anode wire, which will be operated with a Xe/CO2/O2 gas mixture at a high voltage of approximately 1.5 kV. This detector enters a new area that requires it to operate at unprecedented high rates and integrated particle fluxes. Full functionality of the detector over the lifetime (10 years) of the experiment is demanded. Aging of gaseous detectors is a term for the degradation of detector performance during exposure to ionizing radiation. This phenomenon involves very complex physical and chemical processes that are induced by pollution originating from very small amounts of silicon-based substances in some components of the gas system. This work presents a review of previous aging...

  10. Optimization of a transition radiation detector for the compressed baryonic matter experiment

    Energy Technology Data Exchange (ETDEWEB)

    Arend, Andreas

    2014-07-01

    The Transition Radiation Detector (TRD) of the compressed baryonic matter (CBM) experiment at FAIR has to provide electron-pion separation as well as charged-particle tracking. Within this work, thin and symmetric Multi-Wire Proportional Chambers (MWPCs) without additional drift region were proposed. the proposed prototypes feature a foil-based entrance window to minimize the material budget and to reduce the absorption probability of the generated TR photon. Based on the conceptual design of thin and symmetric MWPCs without drift region, multiple prototypes were constructed and their performance presented within this thesis. With the constructed prototypes of generations II and III the geometries of the wire and cathode planes were determined to be 4+4 mm and 5+5 mm. Based on the results of a performed test beam campaign in 2011 with this prototypes new prototypes of generation IV were manufactured and tested in a subsequent test beam campaign in 2012. Prototypes of different radiators were developed together with the MWPC prototypes. Along with regular foil radiators, foam-based radiator types made of polyethylene foam were utilized. Also radiators constructed in a sandwich design, which used different fiber materials confined with solid foam sheets, were used. For the prototypes without drift region, simulations of the electrostatic and mechanical properties were performed. The GARFIELD software package was used to simulate the electric field and to determine the resulting drift lines of the generated electrons. The mean gas amplification depending on the utilized gas and the applied anode voltage was simulated and the gas-gain homogeneity was verified. Since the thin foil-based entrance window experiences a deformation due to pressure differences inside and outside the MWPC, the variation on the gas gain depending on the deformation was simulated. The mechanical properties focusing on the stability of the entrance window was determined with a finiteelement

  11. Energy levels, radiative rates and electron impact excitation rates for transitions in C III

    CERN Document Server

    Aggarwal, K M

    2015-01-01

    We report energy levels, radiative rates (A-values) and lifetimes for the astrophysically-important Be-like ion C III. For the calculations, 166 levels belonging to the $n \\le$ 5 configurations are considered and the {\\sc grasp} (General-purpose Relativistic Atomic Structure Package) is adopted. Einstein A-coefficients are provided for all E1, E2, M1 and M2 transitions, while lifetimes are compared with available measurements as well as theoretical results, and no large discrepancies noted. Our energy levels are assessed to be accurate to better than 1\\% for a majority of levels, and A-values to better than 20\\% for most transitions. Collision strengths are also calculated, for which the Dirac Atomic R-matrix Code ({\\sc darc}) is used. A wide energy range, up to 21 Ryd, is considered and resonances resolved in a fine energy mesh in the thresholds region. The collision strengths are subsequently averaged over a Maxwellian velocity distribution to determine effective collision strengths up to a temperature of 8...

  12. Hot accretion flow with radiative cooling: state transitions in black hole X-ray binaries

    CERN Document Server

    Wu, Mao-Chun; Yuan, Ye-Fei; Gan, Zhao-Ming

    2016-01-01

    We investigate state transitions in black hole X-ray binaries through different parameters by using two-dimensional axisymmetric hydrodynamical simulation method. For radiative cooling in hot accretion flow, we take into account the bremsstrahlung, synchrotron and synchrotron-self Comptonization self-consistently in the dynamics. Our main result is that the state transitions occur when the accretion rate reaches a critical value $\\dot M \\sim 3\\alpha\\ \\dot M_{\\rm Edd}$, above which cold and dense clumpy/filamentary structures are formed, embedded within the hot gas. We argued this mode likely corresponds to the proposed two-phase accretion model, which may be responsible for the intermediate state of black hole X-ray binaries. When the accretion rate becomes sufficiently high, the clumpy/filamentary structures gradually merge and settle down onto the mid-plane. Eventually the accretion geometry transforms to a disc-corona configuration. In summary our results are consistent with the truncated accretion scenari...

  13. Thermoluminescence characteristics of different dimensions of Ge-doped optical fibers in radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Begum, M.; Mizanur R, A. K. M.; Abdul R, H. A.; Yusoff, Z. [Multimedia University, Faculty of Engineering, 63100 Cyberjaya, Selangor Darul Ehsan (Malaysia); Begum, M. [Bangladesh Atomic Energy Commission, E-12/A, Agargaon, Sher-e-Blanga Nagar Dhaka-1207 (Bangladesh); Mat-Sharif, K. A. [Lingkaran Teknokrat Timur, Telekom Research and Development, 63000 Cyberjaya, Selangor Darul Ehsan (Malaysia); Amin, Y. M. [University of Malaya, Faculty of Science, Depatment of Physics, 50603 Kuala Lumpur (Malaysia); Bradley, D. A., E-mail: go2munmun@yahoo.com [University of Surrey, Department of Physics, Guildford GU2 7XH (United Kingdom)

    2014-08-15

    Important thermoluminescence (Tl) properties of five (5) different core sizes Ge doped optical fibers have been studied to develop new Tl material with better response. These are drawn from same preform applying different speed and tension during drawing phase. The results of the investigations are also compared with most commonly used standard TLD-100 chips (LiF:Mg,Ti) and commercial multimode Ge doped optical fiber (Yangtze Optical Fiber, China). Scanning Electron Microscope (Sem) and EDX analysis of the fibers are also performed to map Ge distribution across the deposited region. Standard Gamma radiation source in SSDL (Secondary Standard Dosimetry Lab) was used for irradiation covering dose range from 1 Gy to 10 Gy. The essential dosimetric parameters that have been studied are Tl linearity, reproducibility and fading. Prior to irradiation all samples ∼0.5 cm length are annealed at temperature of 400 grades C for 1 hour period to standardize their sensitivities and background. Standard TLD-100 chips are also annealed for 1 hour at 400 grades C and subsequently 2 hours at 100 grades C to yield the highest sensitivity. Tl responses of these fibers show linearity over a wide gamma radiation dose that is an important property for radiation dosimetry. Among all fibers used in this study, 100 μm core diameter fiber provides highest response that is 2.6 times than that of smallest core (20 μm core) optical fiber. These fiber-samples demonstrate better response than commercial multi-mode optical fiber and also provide low degree of fading about 20% over a period of fifteen days for gamma radiation. Effective atomic number (Z{sub eff}) is found in the range (13.25 to 13.69) that is higher than soft tissue (7.5) however within the range of human-bone (11.6-13.8). All the fibers can also be re-used several times as a detector after annealing. Tl properties of the Ge-doped optical fibers indicate promising applications in ionizing radiation dosimetry. (author)

  14. Probing formally forbidden optical transitions in PbSe nanocrystals by time- and energy-resolved transient absorption spectroscopy

    NARCIS (Netherlands)

    Schins, J.M.; Trinh, M.T.; Houtepen, A.J.; Siebbeles, L.D.A.

    2009-01-01

    The first two peaks of the optical extinction spectrum of PbSe nanocrystals in solution have been assigned in the literature to the 1Sh1Se and 1Ph1Pe transitions. In the present work we assign the transitions causing extinction in the energy region between these two lowest-energy peaks. Our femtosec

  15. The influence of different black carbon and sulfate mixing methods on their optical and radiative properties

    Science.gov (United States)

    Zhang, Hua; Zhou, Chen; Wang, Zhili; Zhao, Shuyun; Li, Jiangnan

    2015-08-01

    Three different internal mixing methods (Core-Shell, Maxwell-Garnett, and Bruggeman) and one external mixing method are used to study the impact of mixing methods of black carbon (BC) with sulfate aerosol on their optical properties, radiative flux, and heating rate. The optical properties of a mixture of BC and sulfate aerosol particles are considered for three typical bands. The results show that mixing methods, the volume ratio of BC to sulfate, and relative humidity have a strong influence on the optical properties of mixed aerosols. Compared to internal mixing, external mixing underestimates the particle mass absorption coefficient by 20-70% and the particle mass scattering coefficient by up to 50%, whereas it overestimates the particle single scattering albedo by 20-50% in most cases. However, the asymmetry parameter is strongly sensitive to the equivalent particle radius, but is only weakly sensitive to the different mixing methods. Of the internal methods, there is less than 2% difference in all optical properties between the Maxwell-Garnett and Bruggeman methods in all bands; however, the differences between the Core-Shell and Maxwell-Garnett/Bruggeman methods are usually larger than 15% in the ultraviolet and visible bands. A sensitivity test is conducted with the Beijing Climate Center Radiation transfer model (BCC-RAD) using a simulated BC concentration that is typical of east-central China and a sulfate volume ratio of 75%. The results show that the internal mixing methods could reduce the radiative flux more effectively because they produce a higher absorption. The annual mean instantaneous radiative force due to BC-sulfate aerosol is about -3.18 W/m2 for the external method and -6.91 W/m2 for the internal methods at the surface, and -3.03/-1.56/-1.85 W/m2 for the external/Core-Shell/(Maxwell-Garnett/Bruggeman) methods, respectively, at the tropopause.

  16. Analytic Models for Radiation Induced Loss in Optical Fibers II. A Physical Model,

    Science.gov (United States)

    1984-06-01

    and identify by Mock number) PIEL GRUP UB.GR. Optical fibers Analytical models Radiation effects 19. ABSTRACT (ConinueII. anl mwr,f fneciua,, and...conditions specified in the derivation of the equations existed during the irradiations. This is because the functional form of the equations is not...tion is not necessarily incorrect. If one assumes a relatively simple form of re- covery as a function of time, such as an exponential recovery, it can

  17. Variability of aerosol optical depth and aerosol radiative forcing over Northwest Himalayan region

    Science.gov (United States)

    Saheb, Shaik Darga; Kant, Yogesh; Mitra, D.

    2016-05-01

    In recent years, the aerosol loading in India is increasing that has significant impact on the weather/climatic conditions. The present study discusses the analysis of temporal (monthly and seasonal) variation of aerosol optical depth(AOD) by the ground based observations from sun photometer and estimate the aerosol radiative forcing and heating rate over selected station Dehradun in North western Himalayas, India during 2015. The in-situ measurements data illustrate that the maximum seasonal average AOD observed during summer season AOD at 500nm ≍ 0.59+/-0.27 with an average angstrom exponent, α ≍0.86 while minimum during winter season AOD at 500nm ≍ 0.33+/-0.10 with angstrom exponent, α ≍1.18. The MODIS and MISR derived AOD was also compared with the ground measured values and are good to be in good agreement. Analysis of air mass back trajectories using HYSPLIT model reveal that the transportation of desert dust during summer months. The Optical Properties of Aerosols and clouds (OPAC) model was used to compute the aerosol optical properties like single scattering albedo (SSA), Angstrom coefficient (α) and Asymmetry(g) parameter for each day of measurement and they are incorporated in a Discrete Ordinate Radiative Transfer model, i.e Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) to estimate the direct short-wave (0.25 to 4 μm) Aerosol Radiative forcing at the Surface (SUR), the top-of-atmosphere (TOA) and Atmosphere (ATM). The maximum Aerosol Radiative Forcing (ARF) was observed during summer months at SUR ≍ -56.42 w/m2, at TOA ≍-21.62 w/m2 whereas in ATM ≍+34.79 w/m2 with corresponding to heating rate 1.24°C/day with in lower atmosphere.

  18. Optical transitions and upconversion properties of Er3+-doped chloride tellurite glasses

    Institute of Scientific and Technical Information of China (English)

    Wen Lei; Li Shun-Guang; Huang Guo-Song; Hu Li-Li; Jiang Zhong-Hong

    2004-01-01

    Er3+-doped lead chloride tellurite glasses were prepared using the conventional melting and quenching method.The absorption spectra were measured and the Judd-Ofelt analysis was performed. The spectroscopic parameters such as the intensity parameters, transition probabilities, radiative lifetimes, and branching ratios were obtained. Intense infrared emission and visible upconversion luminescence under 976nm excitation were observed. For the 1.55μm emission, the full width at half maximum and the emission cross sections are more than 50 nm and 8×10-20cm2,respectively. Three efficient visible luminescences centred at 525, 547, and 658 nm are assigned to the transitions from the excited states 2H11/2, 4S3/2, and 4F9/2 to the ground state 4I15/2, respectively. The upconversion mechanisms and the power-dependent intensities are also discussed and evaluated.

  19. Evaluating contextual processing in diffusion MRI: application to optic radiation reconstruction for epilepsy surgery.

    Directory of Open Access Journals (Sweden)

    Chantal M W Tax

    Full Text Available Diffusion MRI and tractography allow for investigation of the architectural configuration of white matter in vivo, offering new avenues for applications like presurgical planning. Despite the promising outlook, there are many pitfalls that complicate its use for (clinical application. Amongst these are inaccuracies in the geometry of the diffusion profiles on which tractography is based, and poor alignment with neighboring profiles. Recently developed contextual processing techniques, including enhancement and well-posed geometric sharpening, have shown to result in sharper and better aligned diffusion profiles. However, the research that has been conducted up to now is mainly of theoretical nature, and so far these techniques have only been evaluated by visual inspection of the diffusion profiles. In this work, the method is evaluated in a clinically relevant application: the reconstruction of the optic radiation for epilepsy surgery. For this evaluation we have developed a framework in which we incorporate a novel scoring procedure for individual pathways. We demonstrate that, using enhancement and sharpening, the extraction of an anatomically plausible reconstruction of the optic radiation from a large amount of probabilistic pathways is greatly improved in three healthy controls, where currently used methods fail to do so. Furthermore, challenging reconstructions of the optic radiation in three epilepsy surgery candidates with extensive brain lesions demonstrate that it is beneficial to integrate these methods in surgical planning.

  20. Atomic loss and gain as a resource for nonequilibrium phase transitions in optical lattices

    Science.gov (United States)

    Everest, B.; Marcuzzi, M.; Lesanovsky, I.

    2016-02-01

    Recent breakthroughs in the experimental manipulation of strongly interacting atomic Rydberg gases in lattice potentials have opened an avenue for the study of many-body phenomena. Considerable efforts are currently being undertaken to achieve clean experimental settings that show a minimal amount of noise and disorder and are close to zero temperature. A complementary direction investigates the interplay between coherent and dissipative processes. Recent experiments have revealed a glimpse into the emergence of a rich nonequilibrium behavior stemming from the competition of laser excitation, strong interactions, and radiative decay of Rydberg atoms. The aim of the present theoretical work is to show that local incoherent loss and gain of atoms can in fact be the source of interesting out-of-equilibrium dynamics. This perspective opens up paths for the exploration of nonequilibrium critical phenomena and, more generally, phase transitions, some of which so far have been rather difficult to study. To demonstrate the richness of the encountered dynamical behavior we consider here three examples. The first two feature local atom loss and gain together with an incoherent excitation of Rydberg states. In this setting either a continuous or a discontinuous phase transition emerges with the former being reminiscent of genuine nonequilibrium transitions of stochastic processes with multiple absorbing states. The third example considers the regime of coherent laser excitation. Here the many-body dynamics is dominated by an equilibrium transition of the "model A" universality class.

  1. Optical properties of beta-iron silicide, ruthenium silicide and osmium silicide: Semiconducting transition metal silicides

    Science.gov (United States)

    Birdwell, Anthony Glen

    2001-09-01

    Various optical techniques were used to study the semiconducting transition metal silicides of β- FeSi2, Ru2Si3, and OsSi2. The Raman spectra of ion beam synthesized (IBS) β-FeSi 2 were shown to provide evidence of a net tensile stress in these IBS materials. Possible origins of the observed stress were suggested and a simple model was proposed in order to calculate a value of the observed stress. A correlation between the tensile stress, the nature of the band gap, and the resulting light emitting properties of IBS β-FeSi2 was suggested. The photoreflectance (PR) spectra of IBS β- FeSi2 reveals a direct gap at 0.815 eV and were shown to agree with the band gap value obtained by photoluminescence (PL) once the adjustments for the temperature difference and trap related recombination effects were made. This provides very convincing evidence for intrinsic light emission from IBS β- FeSi2. Furthermore, a model was developed that helps to clarify the variety of inconsistent results obtained by optical absorption measurements. When the results of PL and PR were inserted into this model, a good agreement was obtained with our measured optical absorption results. We also obtained PR spectra of β-FeSi 2 thin films grown by molecular beam epitaxy. These spectra reveal the multiple direct transitions near the fundamental absorption edge of β-FeSi 2 that were predicted by theory. We suggest an order of these critical point transitions following the trends reported in the theoretical investigations. Doping these β-FeSi2 thin films with small amounts of chromium was shown to have a measurable effect on the interband optical spectra. We also report on the effects of alloying β- FeSi2 with cobalt. A decrease in the critical point transitions nearest the fundamental absorption edge was observed as the cobalt concentration increased. Finally, Raman spectroscopy was used to study the vibrational properties of β-FeSi2. The measured Raman spectra agreed very well with the

  2. Modeling photosynthesis of discontinuous plant canopies by linking Geometric Optical Radiative Transfer model with biochemical processes

    Directory of Open Access Journals (Sweden)

    Q. Xin

    2015-02-01

    Full Text Available Modeling vegetation photosynthesis is essential for understanding carbon exchanges between terrestrial ecosystems and the atmosphere. The radiative transfer process within plant canopies is one of the key drivers that regulate canopy photosynthesis. Most vegetation cover consists of discrete plant crowns, of which the physical observation departs from the underlying assumption of a homogenous and uniform medium in classic radiative transfer theory. Here we advance the Geometric Optical Radiative Transfer (GORT model to simulate photosynthesis activities for discontinuous plant canopies. We separate radiation absorption into two components that are absorbed by sunlit and shaded leaves, and derive analytical solutions by integrating over the canopy layer. To model leaf-level and canopy-level photosynthesis, leaf light absorption is then linked to the biochemical process of gas diffusion through leaf stomata. The canopy gap probability derived from GORT differs from classic radiative transfer theory, especially when the leaf area index is high, due to leaf clumping effects. Tree characteristics such as tree density, crown shape, and canopy length affect leaf clumping and regulate radiation interception. Modeled gross primary production (GPP for two deciduous forest stands could explain more than 80% of the variance of flux tower measurements at both near hourly and daily time scales. We also demonstrate that the ambient CO2 concentration influences daytime vegetation photosynthesis, which needs to be considered in state-of-the-art biogeochemical models. The proposed model is complementary to classic radiative transfer theory and shows promise in modeling the radiative transfer process and photosynthetic activities over discontinuous forest canopies.

  3. Alterations in the optic radiations of very preterm children—Perinatal predictors and relationships with visual outcomes

    Directory of Open Access Journals (Sweden)

    Deanne K. Thompson

    2014-01-01

    This study presents evidence for microstructural alterations in the optic radiations of VPT children, which are largely predicted by white matter abnormality or severe retinopathy of prematurity, and may partially explain the higher rate of visual impairments in VPT children.

  4. Optical transitions in strained InAsSb/GaInSb interband QC lasers

    Institute of Scientific and Technical Information of China (English)

    Ligong Yang(杨立功); Peifu Gu(顾培夫); Xiaoyun Qin(秦小芸)

    2004-01-01

    @@ In this paper a detailed simulation and theoretical analysis based on model-solid theory and the(→κ)·(→ρ)methodare presented to investigate the dependence of the band structure on the strain deformation in a noveltype-Ⅱ quantum well(QW)heterostructure InAs1_ySby/GaxIn1-xSb under the uniaxial approximation,and subsequently the optical transition and the gain in the interband cascade lasers containing it havebeen evaluated with unchanged injection current densities.The simulation results show that the straineffect on the transition in this heterostructure will not behave as a simple monotonic trend with the latticemismatch of InAs1_ySby/GaxIn1_xSb interface,but as a function of the complex strain chain includingthe whole active region.It is important to the subsequent device design and optimization.

  5. Effect of transition metal dopants on the optical and magnetic properties of semiconductor nanocrystals

    Indian Academy of Sciences (India)

    Ranjani Viswanatha

    2015-06-01

    This review discusses the recent developments in doped semiconductor nanocrystals with a special emphasis on the effect of dopant on the electronic structure of the host nanocrystals. The review focusses on 3 transition metal dopants with unique electronic structure making them receptive for dramatic changes in magnetism, absorption and photoluminescence properties by the successful introduction of a small percentage of dopants into the nanocrystals. Many of these properties are shown to be qualitatively different from that of the bulk properties, leading to challenges in understanding the nature and effects of the confinement of the host. The optical and magnetic changes induced by Mn doping is first reviewed, followed by the use of Cu as a probe to understand the bulk and surface electronic structure of the host. The review concludes with a short section on photomagnetism induced by Cu on the host nanocrystal and a summary of the work with other transition metal ions.

  6. Rheological, optical, and thermal characterization of temperature-induced transitions in liquid crystal ferrosuspensions

    Science.gov (United States)

    Diestra-Cruz, Heberth; Rinaldi, Carlos; Acevedo, Aldo

    2012-04-01

    Liquid crystal ferrosuspensions (LCFs) were obtained by inclusion of magnetic microparticles in a nematic liquid crystal (NLC) at mass fractions of up to 20%. The phase transition of the NLC promotes the formation of a space filling particle network and an enhancement of the mechanical properties. Polarized optical microscopy (POM) and differential scanning calorimetry were used to study microparticle network formation. POM images show that an anisotropic particle structure formed when an external magnetic field was applied, whereas a quasihomogeneous cellular network is obtained in the absence of the field. A jump in the viscoelastic moduli at the isotropic-nematic transition temperature of the NLC was observed for all particle concentrations and applied magnetic fields. Experimental results also showed that the rheological response of the LCFs increased with magnetic field and tend to saturate at high fields. A linear relation between the particle mass fraction and the saturation value of the storage modulus was found.

  7. Development of a synchrotron radiation beam monitor for the Integrable Optics Test Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Scarpelli, Andrea [Univ. of Ferrara (Italy)

    2016-01-01

    Nonlinear integrable optics applied to beam dynamics may mitigate multi-particle instabilities, but proof of principle experiments have never been carried out. The Integrable Optics Test Accelerator (IOTA) is an electron and proton storage ring currently being built at Fermilab, which addresses tests of nonlinear lattice elements in a real machine in addition to experiments on optical stochastic cooling and on the single-electron wave function. These experiments require an outstanding control over the lattice parameters, achievable with fast and precise beam monitoring systems. This work describes the steps for designing and building a beam monitor for IOTA based on synchrotron radiation, able to measure intensity, position and transverse cross-section beam.

  8. Nuclear reactor pulse calibration using a CdZnTe electro-optic radiation detector

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Kyle A., E-mail: knelson1@ksu.edu [S.M.A.R.T. Laboratory, Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS 66506 (United States); Geuther, Jeffrey A. [TRIGA Mark II Nuclear Reactor, Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS 66506 (United States); Neihart, James L.; Riedel, Todd A. [S.M.A.R.T. Laboratory, Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS 66506 (United States); Rojeski, Ronald A. [Nanometrics, Inc., 1550 Buckeye Drive, Milpitas, CA 95035 (United States); Saddler, Jeffrey L. [TRIGA Mark II Nuclear Reactor, Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS 66506 (United States); Schmidt, Aaron J.; McGregor, Douglas S. [S.M.A.R.T. Laboratory, Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS 66506 (United States)

    2012-07-15

    A CdZnTe electro-optic radiation detector was used to calibrate nuclear reactor pulses. The standard configuration of the Pockels cell has collimated light passing through an optically transparent CdZnTe crystal located between crossed polarizers. The transmitted light was focused onto an IR sensitive photodiode. Calibrations of reactor pulses were performed using the CdZnTe Pockels cell by measuring the change in the photodiode current, repeated 10 times for each set of reactor pulses, set between 1.00 and 2.50 dollars in 0.50 increments of reactivity. - Highlights: Black-Right-Pointing-Pointer We demonstrated the first use of an electro-optic device to trace reactor pulses in real-time. Black-Right-Pointing-Pointer We examined the changes in photodiode current for different reactivity insertions. Black-Right-Pointing-Pointer Created a linear best fit line from the data set to predict peak pulse powers.

  9. The Impact of Radiation on the GABLS3 Large-Eddy Simulation through the Night and during the Morning Transition

    NARCIS (Netherlands)

    Edwards, J.M.; Basu, S.; Bosveld, F.C.; Holtslag, A.A.M.

    2014-01-01

    Large-eddy simulation in the GABLS3 intercomparison is concerned with the developed stable boundary layer (SBL) and the ensuing morning transition. The impact of radiative transfer on simulations of this case is assessed. By the time of the reversal of the surface buoyancy flux, a modest reduction o

  10. Electronic properties of [core+exo]-type gold clusters: factors affecting the unique optical transitions.

    Science.gov (United States)

    Shichibu, Yukatsu; Konishi, Katsuaki

    2013-06-03

    Unusual visible absorption properties of [core+exo]-type Au6 (1), Au8 (2), and Au11 (3) clusters were studied from experimental and theoretical aspects, based on previously determined crystal structures. Unlike conventional core-only clusters having no exo gold atoms, these nonspherical clusters all showed an isolated visible absorption band in solution. Density functional theory (DFT) studies on corresponding nonphenyl models (1'-3') revealed that they had similar electronic structures with discrete highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) bands. The theoretical spectra generated by time-dependent DFT (TD-DFT) calculations agreed well with the experimentally measured properties of 1-3, allowing assignment of the characteristic visible bands to HOMO-LUMO transitions. The calculated HOMO-LUMO transition energies increased in the order Au11 exo gold atom, with the HOMO → LUMO transition occurring in the core → exo direction. The HOMO/LUMO distribution patterns of 1' and 3' were similar to each other but were markedly different from that of 2', which has longer core-to-exo distances. These findings showed that not only nuclearity (size) but also geometric structures have profound effects on electronic properties and optical transitions of the [core+exo]-type clusters.

  11. Role of Symmetry Breaking on the Optical Transitions in Lead-Salt Quantum Dots

    KAUST Repository

    Nootz, Gero

    2010-09-08

    The influence of quantum confinement on the one- and two-photon absorption spectra (1PA and 2PA) of PbS and PbSe semiconductor quantum dots (QDs) is investigated. The results show 2PA peaks at energies where only 1PA transitions are predicted and 1PA peaks where only 2PA transitions are predicted by the often used isotropic k•p four-band envelope function formalism. The first experimentally identified two-photon absorption peak coincides with the energy of the first one photon allowed transition. This first two-photon peak cannot be explained by band anisotropy, verifying that the inversion symmetry of the wave functions is broken and relaxation of the parity selection rules has to be taken into account to explain optical transitions in lead-salt QDs. Thus, while the band anisotropy of the bulk semiconductor plays a role in the absorption spectra, especially for the more anisotropic PbSe QDs, a complete model of the absorption spectra, for both 1PA and 2PA, must also include symmetry breaking of the quantum confined wave functions. These studies clarify the controversy of the origin of spectral features in lead-salt QDs. © 2010 American Chemical Society.

  12. High-accuracy optical clock based on the octupole transition in 171Yb+

    CERN Document Server

    Huntemann, N; Lipphardt, B; Weyers, S; Tamm, Chr; Peik, E

    2011-01-01

    We experimentally investigate an optical frequency standard based on the 467 nm (642 THz) electric-octupole reference transition 2S1/2(F=0) -> F7/2(F=3) in a single trapped 171Yb+ ion. The extraordinary features of this transition result from the long natural lifetime and from the 4f136s2 configuration of the upper state. The electric quadrupole moment of the 2F7/2 state is measured as -0.041(5) e(a0)^2, where e is the elementary charge and a0 the Bohr radius. We also obtain information on the differential scalar and tensorial components of the static polarizability and of the probe light induced ac Stark shift of the octupole transition. With a real-time extrapolation scheme that eliminates this shift, the unperturbed transition frequency is realized with a fractional uncertainty of 7.1x10^(-17). The frequency is measured as 642 121 496 772 645.15(52) Hz with the uncertainty essentially determined by the employed caesium fountain reference.

  13. High-accuracy optical clock based on the octupole transition in 171Yb+.

    Science.gov (United States)

    Huntemann, N; Okhapkin, M; Lipphardt, B; Weyers, S; Tamm, Chr; Peik, E

    2012-03-02

    We experimentally investigate an optical frequency standard based on the 467 nm (642 THz) electric-octupole reference transition (2)S(1/2)(F=0)→(2)F(7/2)(F=3) in a single trapped (171)Yb(+) ion. The extraordinary features of this transition result from the long natural lifetime and from the 4f(13)6s(2) configuration of the upper state. The electric-quadrupole moment of the (2)F(7/2) state is measured as -0.041(5)ea(0)(2), where e is the elementary charge and a(0) the Bohr radius. We also obtain information on the differential scalar and tensorial components of the static polarizability and of the probe-light-induced ac Stark shift of the octupole transition. With a real-time extrapolation scheme that eliminates this shift, the unperturbed transition frequency is realized with a fractional uncertainty of 7.1×10(-17). The frequency is measured as 642 121 496 772 645.15(52) Hz.

  14. Bandwidth smearing in optical interferometry: Analytic model of the transition to the double fringe packet

    CERN Document Server

    Lachaume, Régis

    2012-01-01

    Bandwidth smearing is a chromatic aberration due to the finite frequency bandwidth. In long-baseline optical interferometry terms, it is when the angular extension of the source is greater than the coherence length of the interferogram. As a consequence, separated parts of the source will contribute to fringe packets that are not fully overlapping; it is a transition from the classical interferometric regime to a double or multiple fringe packet. While studied in radio interferometry, there has been little work on the matter in the optical, where observables are measured and derived in a different manner, and are more strongly impacted by the turbulent atmosphere. We provide here the formalism and a set of usable equations to model and correct for the impact of smearing on the fringe contrast and phase, with the case of multiple stellar systems in mind. The atmosphere is briefly modeled and discussed.

  15. Optically and thermally controlled terahertz metamaterial via transition between direct and indirect electromagnetically induced transparency

    Directory of Open Access Journals (Sweden)

    Jiawei Sui

    2014-12-01

    Full Text Available This passage presents a design of tunable terahertz metamaterials via transition between indirect and direct electromagnetically induced transparency (EIT effects by changing semiconductor InSb’s properties to terahertz wave under optical and thermal stimuli. Mechanical model and its electrical circuit model are utilized in analytically calculating maximum transmission of transparency window. Simulated results show consistency with the analytical expressions. The results show that the metamaterials hold 98.4% modulation depth at 189 GHz between 300 K, σInSb =256000 S/m, and 80 K, σInSb =0.0162 S/m conditions , 1360 ps recovery time of the excited electrons in InSb under optical stimulus at 300 K mainly considering the direct EIT effect, and minimum bandwidth 1 GHz.

  16. Strain-induced fundamental optical transition in (In,Ga)As/GaP quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Robert, C., E-mail: cedric.robert@insa-rennes.fr, E-mail: cedric.robert@tyndall.ie; Pedesseau, L.; Cornet, C.; Jancu, J.-M.; Even, J.; Durand, O. [Université Européenne de Bretagne, INSA Rennes, France and CNRS, UMR 6082 Foton, 20 Avenue des Buttes de Coësmes, 35708 Rennes (France); Nestoklon, M. O. [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Pereira da Silva, K. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); Departamento de Física, Universidade Federal do Ceará, P.O. Box 6030, Fortaleza–CE, 60455-970 (Brazil); Alonso, M. I. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); Goñi, A. R. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); ICREA, Passeig Lluís Companys 23, 08010 Barcelona (Spain); Turban, P. [Equipe de Physique des Surfaces et Interfaces, Institut de Physique de Rennes UMR UR1-CNRS 6251, Université de Rennes 1, F-35042 Rennes Cedex (France)

    2014-01-06

    The nature of the ground optical transition in an (In,Ga)As/GaP quantum dot is thoroughly investigated through a million atoms supercell tight-binding simulation. Precise quantum dot morphology is deduced from previously reported scanning-tunneling-microscopy images. The strain field is calculated with the valence force field method and has a strong influence on the confinement potentials, principally, for the conduction band states. Indeed, the wavefunction of the ground electron state is spatially confined in the GaP matrix, close to the dot apex, in a large tensile strain region, having mainly Xz character. Photoluminescence experiments under hydrostatic pressure strongly support the theoretical conclusions.

  17. Synthesis and Characterization of Layered Double Hydroxides Containing Optically Active Transition Metal Ion

    Science.gov (United States)

    Tyagi, S. B.; Kharkwal, Aneeta; Nitu; Kharkwal, Mamta; Sharma, Raghunandan

    2017-01-01

    The acetate intercalated layered double hydroxides of Zn and Mn, have been synthesized by chimie douce method. The materials were characterized by XRD, TGA, CHN, IR, XPS, SEM-EDX and UV-visible spectroscopy. The photoluminescence properties was also studied. The optical properties of layered hydroxides are active transition metal ion dependent, particularly d1-10 system plays an important role. Simultaneously the role of host - guest orientation has been considered the basis of photoluminescence. Acetate ion can be exchanged with iodide and sulphate ions. The decomposed product resulted the pure phase Mn doped zinc oxide are also reported.

  18. Optical nonlinearities of excitonic states in atomically thin 2D transition metal dichalcogenides.

    Energy Technology Data Exchange (ETDEWEB)

    Soh, Daniel Beom Soo

    2017-09-01

    We calculated the optical nonlinearities of the atomically thin monolayer transition metal dichalcogenide material (particularly MoS 2 ), particularly for those linear and nonlinear tran- sition processes that utilize the bound exciton states. We adopted the bound and the unbound exciton states as the basis for the Hilbert space, and derived all the dynamical density matri- ces that provides the induced current density, from which the nonlinear susceptibilities can be drawn order-by-order via perturbative calculations. We provide the nonlinear susceptibil- ities for the linear, the second-harmonic, the third-harmonic, and the kerr-type two-photon processes.

  19. Structural, optical and glass transition studies on Nd{sup 3+}-doped lead bismuth borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Karthikeyan, B.; Mohan, S

    2003-07-01

    Nd{sup 3+}-doped lead bismuth borate (PbO-Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3}) glasses were prepared with different concentrations of Nd{sup 3+}. The structural studies were done through FTIR spectral analysis. The glass transition studies were done through differential scanning calorimetry. The optical analysis was done by using Judd-Ofelt theory. The structural study reveals that the glass has [BiO{sub 3}], BO{sub 4}, BO{sub 3} and PbO{sub 4} units as the local structures.

  20. Synthetic dimensions and spin-orbit coupling with an optical clock transition

    CERN Document Server

    Livi, L F; Diem, M; Franchi, L; Clivati, C; Frittelli, M; Levi, F; Calonico, D; Catani, J; Inguscio, M; Fallani, L

    2016-01-01

    We demonstrate a novel way of synthesizing spin-orbit interactions in ultracold quantum gases, based on a single-photon optical clock transition coupling two long-lived electronic states of two-electron $^{173}$Yb atoms. By mapping the electronic states onto effective sites along a synthetic "electronic" dimension, we have engineered synthetic fermionic ladders with tunable magnetic fluxes. We have detected the spin-orbit coupling with fiber-link-enhanced clock spectroscopy and directly measured the emergence of chiral edge currents, probing them as a function of the magnetic field flux. These results open new directions for the investigation of topological states of matter with ultracold atomic gases.

  1. Optical fingerprint of dark 2p-states in transition metal dichalcogenides

    Science.gov (United States)

    Berghäuser, Gunnar; Knorr, Andreas; Malic, Ermin

    2017-03-01

    Atomically thin transition metal dichalcogenides exhibit a remarkably strong Coulomb interaction. This results in a fascinating many-particle physics including a variety of bright and dark excitonic states that determine optical and electronic properties of these materials. So far, the impact of dark states has remained literally in the dark to a large extent, since a measurement of these optically forbidden states is very challenging. Here we demonstrate a strategy to measure a direct fingerprint of dark states even in standard linear absorption spectroscopy. We present a microscopic study on bright and dark higher excitonic states in the presence of disorder for the exemplary material of tungsten disulfide (WS2). We show that the geometric phase cancels the degeneration of 2s and 2p states and that a significant disorder-induced coupling of these bright and dark states offers a strategy to circumvent optical selection rules. As a proof, we show a clear fingerprint of dark 2p states in the absorption spectrum of WS2. The predicted softening of optical selection rules through exciton-disorder coupling is of general nature and therefore applicable to related two-dimensional semiconductors.

  2. Frequency shifts in an optical lattice clock due to magnetic-dipole and electric-quadrupole transitions.

    Science.gov (United States)

    Taichenachev, A V; Yudin, V I; Ovsiannikov, V D; Pal'chikov, V G; Oates, C W

    2008-11-01

    We report a hitherto undiscovered frequency shift for forbidden J = 0-->J = 0 clock transitions excited in atoms confined to an optical lattice. These shifts result from magnetic-dipole and electric-quadrupole transitions, which have a spatial dependence in an optical lattice that differs from that of the stronger electric-dipole transitions. In combination with the residual translational motion of atoms in an optical lattice, this spatial mismatch leads to a frequency shift via differential energy level spacing in the lattice wells for ground state and excited state atoms. We estimate that this effect could lead to fractional frequency shifts as large as 10(-16), which might prevent lattice-based optical clocks from reaching their predicted performance levels. Moreover, these effects could shift the magic wavelength in lattice clocks in three dimensions by as much as 100 MHz, depending on the lattice configuration.

  3. Modelling single shot damage thresholds of multilayer optics for high-intensity short-wavelength radiation sources.

    Science.gov (United States)

    Loch, R A; Sobierajski, R; Louis, E; Bosgra, J; Bijkerk, F

    2012-12-17

    The single shot damage thresholds of multilayer optics for high-intensity short-wavelength radiation sources are theoretically investigated, using a model developed on the basis of experimental data obtained at the FLASH and LCLS free electron lasers. We compare the radiation hardness of commonly used multilayer optics and propose new material combinations selected for a high damage threshold. Our study demonstrates that the damage thresholds of multilayer optics can vary over a large range of incidence fluences and can be as high as several hundreds of mJ/cm(2). This strongly suggests that multilayer mirrors are serious candidates for damage resistant optics. Especially, multilayer optics based on Li(2)O spacers are very promising for use in current and future short-wavelength radiation sources.

  4. Development of a wavelength-separated type scintillator with optical fiber (SOF) dosimeter to compensate for the Cerenkov radiation effect.

    Science.gov (United States)

    Ishikawa, Masayori; Nagase, Naomi; Matsuura, Taeko; Hiratsuka, Junichi; Suzuki, Ryusuke; Miyamoto, Naoki; Sutherland, Kenneth Lee; Fujita, Katsuhisa; Shirato, Hiroki

    2015-03-01

    The scintillator with optical fiber (SOF) dosimeter consists of a miniature scintillator mounted on the tip of an optical fiber. The scintillator of the current SOF dosimeter is a 1-mm diameter hemisphere. For a scintillation dosimeter coupled with an optical fiber, measurement accuracy is influenced by signals due to Cerenkov radiation in the optical fiber. We have implemented a spectral filtering technique for compensating for the Cerenkov radiation effect specifically for our plastic scintillator-based dosimeter, using a wavelength-separated counting method. A dichroic mirror was used for separating input light signals. Individual signal counting was performed for high- and low-wavelength light signals. To confirm the accuracy, measurements with various amounts of Cerenkov radiation were performed by changing the incident direction while keeping the Ir-192 source-to-dosimeter distance constant, resulting in a fluctuation of Optical fiber bending was also addressed; no bending effect was observed for our wavelength-separated SOF dosimeter.

  5. Changes of radial diffusivity and fractional anisotropy in the optic nerve and optic radiation of glaucoma patients.

    Science.gov (United States)

    Engelhorn, Tobias; Michelson, Georg; Waerntges, Simone; Otto, Marlen; El-Rafei, Ahmed; Struffert, Tobias; Doerfler, Arnd

    2012-01-01

    Purpose of this study was to evaluate with diffusion-tensor imaging (DTI) changes of radial diffusivity (RD) and fractional anisotropy (FA) in the optic nerve (ON) and optic radiation (OR) in glaucoma and to determine whether changes in RD and FA correlate with disease severity. Therefore, glaucoma patients and controls were examined using 3T. Regions of interest were positioned on RD and FA maps, and mean values were calculated for ON and OR and correlated with optic nerve atrophy and reduced spatial-temporal contrast sensitivity (STCS) of the retina. We found, that RD in glaucoma patients was significantly higher in the ON (0.74 ± 0.21 versus 0.58 ± 0.17·10(-3) mm(2) s(-1); P 0.77). In conclusion, DTI at 3 Tesla allows robust RD and FA measurements in the ON and OR. Hereby, the extent of RD increase and FA decrease in glaucoma correlate with established ophthalmological examinations.

  6. Changes of Radial Diffusivity and Fractional Anisotopy in the Optic Nerve and Optic Radiation of Glaucoma Patients

    Directory of Open Access Journals (Sweden)

    Tobias Engelhorn

    2012-01-01

    Full Text Available Purpose of this study was to evaluate with diffusion-tensor imaging (DTI changes of radial diffusivity (RD and fractional anisotropy (FA in the optic nerve (ON and optic radiation (OR in glaucoma and to determine whether changes in RD and FA correlate with disease severity. Therefore, glaucoma patients and controls were examined using 3T. Regions of interest were positioned on RD and FA maps, and mean values were calculated for ON and OR and correlated with optic nerve atrophy and reduced spatial-temporal contrast sensitivity (STCS of the retina. We found, that RD in glaucoma patients was significantly higher in the ON (0.74 ± 0.21 versus 0.58 ± 0.17⋅10−3 mm2 s−1; P0.77. In conclusion, DTI at 3 Tesla allows robust RD and FA measurements in the ON and OR. Hereby, the extent of RD increase and FA decrease in glaucoma correlate with established ophthalmological examinations.

  7. Accuracy of Analog Fiber-Optic Links in Pulsed Radiation Environments

    Energy Technology Data Exchange (ETDEWEB)

    E. K. Miller, G. S. Macrum, I. J. McKenna, et al.

    2007-12-01

    Interferometric fiber-optic links used in pulsed-power experiments are evaluated for accuracy in the presence of radiation fields which alter fiber transmission. Amplitude-modulated format (e.g., Mach-Zehnder) and phase-modulated formats are compared. Historically, studies of radiation effects on optical fibers have focused on degradation and recovery of the fibers transmission properties; such work is either in the context of survivability of fibers in catastrophic conditions or suitability of fibers installed for command and control systems within an experimental facility [1], [2]. In this work, we consider links used to transmit realtime diagnostic data, and we analyze the error introduced by radiation effects during the drive pulse. The result is increased uncertainties in key parameters required to unfold the sinusoidal transfer function. Two types of modulation are considered: amplitude modulation typical of a Mach-Zehnder (M-Z) modulator [3], and phase modulation, which offers more flexible demodulation options but relies on the spatiotemporal coherence of the light in the fiber. The M-Z link is shown schematically in Fig. 1, and the phase-modulated link is shown in Fig. 2. We present data from two experimental environments: one with intense, controlled radiation fields to simulate conditions expected at the next generation of pulsed-power facilities, and the second with radiation effects below the noise level of the recording system. In the first case, we intentionally expose three types of single-mode fiber (SMF) to ionizing radiation and study the response by simultaneously monitoring phase and amplitude of the transmitted light. The phase and amplitude effects are evidently dominated by different physical phenomena, as their recovery dynamics are markedly different; both effects, though, show similar short-term behavior during exposure, integrating the dose at the dose levels studied, from 1 to 300 kRad, over the exposure times of 50 ps and 30 ns. In the

  8. Optically stimulated luminescence (OSL) of dental enamel for retrospective assessment of radiation exposure

    Energy Technology Data Exchange (ETDEWEB)

    Yukihara, E.G. [Department of Physics, Oklahoma State University, Stillwater, OK 74078 (United States)], E-mail: eduardo.yukihara@okstate.edu; Mittani, J.; McKeever, S.W.S. [Department of Physics, Oklahoma State University, Stillwater, OK 74078 (United States); Simon, S.L. [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-7238 (United States)

    2007-07-15

    This paper briefly reviews the optically stimulated luminescence (OSL) properties of dental enamel and discusses the potential and challenges of OSL for filling the technology gap in biodosimetry required for medical triage following a radiological/nuclear accident or terrorist event. The OSL technique uses light to stimulate a radiation-induced luminescence signal from materials previously exposed to ionizing radiation. This luminescence originates from radiation-induced defects in insulating crystals and is proportional to the absorbed dose of ionizing radiation. In our research conducted to date, we focused on fundamental investigations of the OSL properties of dental enamel using extracted teeth and tabletop OSL readers. The objective was to obtain information to support the development of the necessary instrumentation for retrospective dosimetry using dental enamel in laboratory, or for in situ and non-invasive accident dosimetry using dental enamel in emergency triage. An OSL signal from human dental enamel was detected using blue, green, or IR stimulation. Blue/green stimulation associated with UV emission detection seems to be the most appropriate combination in the sense that there is no signal from un-irradiated samples and the shape of the OSL decay is clear. Improvements in the minimum detection level were achieved by incorporating an ellipsoidal mirror in the OSL system to maximize light collection. Other possibilities to improve the sensitivity and research steps necessary to establish the feasibility of the technique for retrospective assessment of radiation exposure are also discussed.

  9. Optical characteristics of the aerosol in Spain and Austria and its effect on radiative forcing

    Science.gov (United States)

    Horvath, H.; Alados Arboledas, L.; Olmo, F. J.; Jovanović, O.; Gangl, M.; Kaller, W.; SáNchez, C.; Sauerzopf, H.; Seidl, S.

    2002-10-01

    The horizontal and vertical attenuation of the aerosol, the sky radiance, and the light absorption coefficient of the aerosol have been determined at wavelengths in the visible. From this set of data the following optical characteristics of the atmospheric aerosol could be derived: vertical optical depth, horizontal extinction and absorption coefficient, scattering phase function, asymmetry parameter, and single scattering albedo. Campaigns have been performed in Almería, Spain, and Vienna, Austria. The aerosol undergoes a considerable variation, as experienced by many other studies. Sometimes the vertical and the horizontal measurements gave similar data; on other days the aerosol at the surface and the aerosol aloft were completely different. The "clearest" aerosol always had the smallest single scattering albedo and thus relatively the highest light absorption. The optical characteristics of the aerosol in the two very different locations were very similar. Using the measured optical data, a radiative transfer calculation was performed, and the radiation reaching the ground was calculated. Comparing the values for the clear aerosol and the days with higher aerosol load, the radiative forcing due to the additional aerosol particles could be determined. The forcing of the aerosol at the ground is always negative, and at the top of the atmosphere it is close to zero or slightly negative. Its dependence on wavelength and zenith angle is presented. The preindustrial aerosol in Europe was estimated, and the forcing due to the present-day aerosol was determined. At the surface it is negative, but at the top of the atmosphere it is close to zero or positive. This is caused by the light absorption of the European aerosol, which is higher than in most other locations.

  10. Parameterization of sea-salt optical properties and physics of the associated radiative forcing

    Science.gov (United States)

    Li, J.; Ma, X.; von Salzen, K.; Dobbie, S.

    2008-08-01

    The optical properties of sea-salt aerosol have been parameterized at shortwave and longwave wavelengths. The optical properties were parameterized in a simple functional form in terms of the ambient relative humidity based on Mie optical property calculations. The proposed parameterization is tested relative to Mie calculations and is found to be accurate to within a few percent. In the parameterization, the effects of the size distribution on the optical properties are accounted for in terms of effective radius of the sea-salt size distribution. This parameterization differs from previous works by being formulated directly with the wet sea-salt size distribution and, to our knowledge, this is the first published sea-salt parameterization to provide a parameterization for both shortwave and longwave wavelengths. We have used this parameterization in a set of idealized 1-D radiative transfer calculations to investigate the sensitivity of various attributes of sea-salt forcing, including the dependency on sea-salt column loading, effective variance, solar angle, and surface albedo. From these sensitivity tests, it is found that sea-salt forcings for both shortwave and longwave spectra are linearly related to the sea-salt loading for realistic values of loadings. The radiative forcing results illustrate that the shortwave forcing is an order of magnitude greater than the longwave forcing results and opposite in sign, for various loadings. Forcing sensitivity studies show that the influence of effective variance for sea-salt is minor; therefore, only one value of effective variance is used in the parameterization. The dependence of sea-salt forcing with solar zenith angle illustrates an interesting result that sea-salt can generate a positive top-of-the-atmosphere result (i.e. warming) when the solar zenith angle is relatively small (i.e. <30°). Finally, it is found that the surface albedo significantly affects the shortwave radiative forcing, with the forcing

  11. An investigation of the production of thin films of some materials which undergo phase transitions for optical applications

    CERN Document Server

    Pedlar, I D

    1995-01-01

    The aim of this work was to study the possibility of producing a fast switching optical thin film device to react to laser radiation in the visible/near infrared region of the spectrum. The switching mechanism was to be thermally driven. A computer program was written to enable the effects of changes of the refractive index of a component of a multilayer thin film stack to be modelled. Attempts to use the phase transition in vanadium dioxide were unsuccessful because, in the spectral region of interest, the 'open-state' absorption was too great. A class of materials known as 'the bronzes' was identified as being potentially useful. Attempts were made to produce thin films of bronze compounds of vanadium, tungsten and molybdenum by the techniques of conventional thermal evaporation and laser ablation for further studies. The former technique appeared to suffer from problems of decomposition of the source material. The latter technique showed greater promise although loss of oxygen was a constant problem. Selec...

  12. LIGHT MODULATION: Wide-aperture diffraction of unpolarised radiation in a system of two acousto-optic filters

    Science.gov (United States)

    Magdich, L. N.; Yushkov, K. B.; Voloshinov, V. B.

    2009-04-01

    Light diffraction is studied in two tandem acousto-optic cells filtering unpolarised radiation with a wide angular spectrum. It is shown that the side lobes of the ultrasonic radiation pattern of a piezoelectric transducer produce side diffraction intensity maxima at the output of the system consisting of two filters. Diffraction in paratellurite filters is studied experimentally at 1.06 μm.

  13. Optical Transients Powered by Magnetars: Dynamics, Light Curves, and Transition to the Nebular Phase

    CERN Document Server

    Wang, L J; Dai, Z G; Xu, Dong; Han, Yan-Hui; Wu, X F; Wei, Jian-Yan

    2016-01-01

    Millisecond magnetars can be formed via several channels: core-collapse of massive stars, accretion-induced collapse of white dwarfs (WDs), double WD mergers, double neutron star (NS) mergers, and WD-NS mergers. Because the mass of ejecta from these channels could be quite different, their light curves are also expected to be diverse. We evaluate the dynamic evolution of optical transients powered by millisecond magnetars. We find that the magnetar with short spin-down timescale converts its rotational energy mostly into the kinetic energy of the transient, while the energy of a magnetar with long spin-down timescale goes into radiation of the transient. This leads us to speculate that hypernovae could be powered by magnetars with short spin-down timescales. At late times the optical transients will gradually evolve into a nebular phase because of the photospheric recession. We treat the photosphere and nebula separately because their radiation mechanisms are different. In some cases the ejecta could be light...

  14. Optical fiber detectors as in-vivo dosimetry method of quality assurance in radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Plazas, M.C. [Universidad Nacional de Colombia, Bogota (Colombia). Physics Dept. Medical Physics Group; Justus, B.L.; Falkenstein, P.; Huston, A.L. [Naval Research Laboratory, Washington, DC (United States). Optical Sciences Div.; Ning, H.; Miller, R. [National Cancer Institute, Bethesda, MD (United States). Radiation Oncology Branch

    2004-07-01

    A new in-vivo dosimetry system has been under development for some time using radio luminescent phosphors. These phosphors are activated, metal ion doped glasses (Ex: Cu{sup 1{+-}} doped quartz fiber), have excellent optical transparency and offer several potential advantages for radiation dosimetry; including: small size, high sensitivity, linearity of dose response insensitivity to electromagnetic interference. The utility of these phosphors as a detection modality has been limited in real-time dosimetry applications due to the production of Cerenkov radiation in the carrier fiber, which produces a contaminant signal proportional to dose rate as well as the size of the radiation field. One possible method for eliminating this signal is using an electronic gating signal from the accelerator to delay data acquisition during the actual beam pulse, when Cerenkov radiation is produced. Due to the intrinsic properties of our particular scintillator, this method offers the best mechanism for eliminating Cerenkov noise, while retaining the ability to detect individual beam pulses. The dosimeter was tested using an external beam radiotherapy machine that provided pulses of 6 MeV x-rays. Gated detection was used to discriminate the signal collected during the radiation pulses, which included contributions from Cerenkov radiation and native fiber fluorescence, from the signal collected between the radiation pulses, which contained only the long-lived phosphorescence from the Cu{sup 1{+-}} doped fused quartz detector. Gated detection of the phosphorescence provided accurate, real-time dose measurements that were linear with absorbed dose, independent of dose rate and that were accurate for all field sizes studied. (author)

  15. Optical transition and thermal quenching mechanism in CaSnO{sub 3}:Eu{sup 3+} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jinsu, E-mail: zhangjinsu@gmail.com; Chen, Baojiu, E-mail: baojiu.chen@gmail.com; Liang, Zuoqiu; Li, Xiangping; Sun, Jiashi; Cheng, Lihong; Zhong, Haiyang

    2014-11-05

    Highlights: • A red emitting phosphor of CaSnO{sub 3}: Eu{sup 3+} is synthesized. • The Judd–Ofelt theory analysis has been applied to deal with the optical transition. • Thermal behavior is discussed in detail due to the temperature dependence population. - Abstract: CaSnO{sub 3} phosphors doped with various Eu{sup 3+} concentrations are synthesized by a solid-state reaction. The crystal structure of the phosphors is identified by the XRD technique, and it is found that the pure phase CaSnO{sub 3} phosphor can be obtained when the Eu{sup 3+} doping concentration lower than 2 mol%. The emission spectra consisting of a group of sharp lines from blue to red light originating from {sup 5}D{sub 3,2,1,0} → {sup 7}F{sub J} transitions of Eu{sup 3+} are observed in phosphors with various Eu{sup 3+} doping concentrations. The radiative lifetimes of {sup 5}D{sub 0} level are measured for the samples with various Eu{sup 3+} concentrations, and for the sample with 2 mol% Eu{sup 3+} at various temperatures. The oscillator strengths parameters (Judd–Ofelt parameters) Ω{sub λ}(λ = 2, 4, 6) of Eu{sup 3+} in CaSnO{sub 3} phosphors are calculated to be 3.21 × 10{sup −20}, 0.88 × 10{sup −20} and 0.35 × 10{sup −20} cm{sup 2}. The photoluminescence excitation and photoluminescence spectra are measured in the temperature range 300–750 K. The thermo-dynamical behavior for {sup 5}D{sub 3}, {sup 5}D{sub 2}, {sup 5}D{sub 1} and {sup 5}D{sub 0} populations are analyzed based on the temperature-dependent emission spectra of {sup 5}D{sub J} levels.

  16. The Effects of Electron Radiation on the Glass Transition Temperature of a Polyetherimide.

    Science.gov (United States)

    Kern, Kristen Tulloch

    The effects of electron radiation on a polyetherimide (PEI), Ultem^{cdot}, were investigated. In particular, the changes in the glass transition temperature (T_{g} ) with absorbed radiation dose were studied. The polymer was exposed to mono-energetic beams of 100-keV electrons and 1.0-MeV electrons for doses up to 100 megagray (MGy). Dosimetry for the exposures was based on Monte -Carlo simulations of the transfer of energy from an energetic electron to the polymer and on comparison to Nylon standards. Dynamic mechanical analysis was used to determine the T _{g} for non-exposed PEI and the changes in T_{g} resulting from irradiation. The T_{g} did not change significantly for doses up to and including 75 MGy, while a significant increase in T_ {g} occurred for a dose of 100 MGy. The cross-link and chain scission densities in the irradiated PEI were determined using infrared spectroscopy. The cross -link density increased with dose for all doses investigated. The chain scission density increased with dose for doses up to 75 MGy, but was lower for a dose of 100 MGy than for a dose of 75 MGy. Radical population kinetics, based in part on data from an electron paramagnetic resonance study, were correlated with the cross-link density and chain scission density to investigate the mechanism for the observed density variations with dose. The radical population simulations suggest that chain scissioning occurs less readily when the average radical separation during the exposure is less than three molecular radii. Finally, a model for the combined effects of cross-linking and chain scissioning is proposed which combines a statistical-mechanical model for the change in T_{g} with cross-link density and a free-volume model for the change in T _{g} with chain scission density.

  17. The maximum tolerated dose of gamma radiation to the optic nerve during γ knife radiosurgery in an animal study.

    Science.gov (United States)

    Deng, Xingli; Yang, Zhiyong; Liu, Ruen; Yi, Meiying; Lei, Deqiang; Wang, Zhi; Zhao, Hongyang

    2013-01-01

    The safety of gamma knife radiosurgery should be considered when treating pituitary adenomas. To determine the maximum tolerated dose of radiation delivered by gamma knife radiosurgery to optic nerves. An animal model designed to establish prolonged balloon compression of the optic chiasm and parasellar region was developed to mimic the optic nerve compression caused by pituitary adenomas. Twenty cats underwent surgery to place a balloon for compression effect and 20 cats in a sham operation group received microsurgery without any treatment. The effects of gamma knife irradiation at 10-13 Gy on normal (sham operation group) and compressed (optic nerve compression group) optic nerves were investigated by pattern visual evoked potential examination and histopathology. Gamma knife radiosurgery at 10 Gy had almost no effect. At 11 Gy, P100 latency was significantly prolonged and P100 amplitude was significantly decreased in compressed optic nerves, but there was little change in the normal optic nerves. Doses of 11 Gy and higher induced significant electrophysiological variations and degeneration of the myelin sheath and axons in both normal and compressed optic nerves. Compressed optic nerves are more sensitive to gamma knife radiosurgery than normal optic nerves. The minimum dose of gamma knife radiosurgery that causes radiation injury in normal optic nerves is 12 Gy; however, the minimum dose is 11 Gy in compressed optic nerves. Copyright © 2013 S. Karger AG, Basel.

  18. Optical gain for the interband optical transition in InAsP/InP quantum well wire in the influence of laser field intensity

    Energy Technology Data Exchange (ETDEWEB)

    Saravanan, S. [Dept.of Physics, GTN Arts College, Dindigul-624 005. India (India); Peter, A. John, E-mail: a.john.peter@gmail.com [P.G & Research Dept.of Physics, Government Arts College, Melur-625 106. Madurai. India (India)

    2016-05-23

    Intense high frequency laser field induced electronic and optical properties of heavy hole exciton in the InAs{sub 0.8}P{sub 0.2}/InP quantum wire is studied taking into account the geometrical confinement effect. Laser field related exciton binding energies and the optical band gap in the InAs{sub 0.8}P{sub 0.2}/InP quantum well wire are investigated. The optical gain, for the interband optical transition, as a function of photon energy, in the InAs{sub 0.8}P{sub 0.2}/InP quantum wire, is obtained in the presence of intense laser field. The compact density matrix method is employed to obtain the optical gain. The obtained optical gain in group III-V narrow quantum wire can be applied for achieving the preferred telecommunication wavelength.

  19. Energy band gap and optical transition of metal ion modified double crossover DNA lattices.

    Science.gov (United States)

    Dugasani, Sreekantha Reddy; Ha, Taewoo; Gnapareddy, Bramaramba; Choi, Kyujin; Lee, Junwye; Kim, Byeonghoon; Kim, Jae Hoon; Park, Sung Ha

    2014-10-22

    We report on the energy band gap and optical transition of a series of divalent metal ion (Cu(2+), Ni(2+), Zn(2+), and Co(2+)) modified DNA (M-DNA) double crossover (DX) lattices fabricated on fused silica by the substrate-assisted growth (SAG) method. We demonstrate how the degree of coverage of the DX lattices is influenced by the DX monomer concentration and also analyze the band gaps of the M-DNA lattices. The energy band gap of the M-DNA, between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO), ranges from 4.67 to 4.98 eV as judged by optical transitions. Relative to the band gap of a pristine DNA molecule (4.69 eV), the band gap of the M-DNA lattices increases with metal ion doping up to a critical concentration and then decreases with further doping. Interestingly, except for the case of Ni(2+), the onset of the second absorption band shifts to a lower energy until a critical concentration and then shifts to a higher energy with further increasing the metal ion concentration, which is consistent with the evolution of electrical transport characteristics. Our results show that controllable metal ion doping is an effective method to tune the band gap energy of DNA-based nanostructures.

  20. Infrared spectrum involving forbidden transitions & coriolis interaction and identification of optically pumped far infrared laser lines in asymmetrically mono-deuterated methanol (Methanol-D1)

    Science.gov (United States)

    Mukhopadhyay, Indra

    2016-05-01

    In this paper new type of ΔK = 2 and 0 transitions have been identified in the Fourier Transform spectrum of Methanol-D1 (CH2DOH). These transitions are normally forbidden but a "Coriolis" type interaction with nearby states is believed to be contributing sufficient transition strength through intensity borrowing effect. This is the first time such forbidden transitions are reported to be identified in the excited states, in this molecule. The present conjecture is supported by observation of a many strong allowed transitions to upper terminating levels which are seen to be highly perturbed. This conclusion has been reached by comparing calculated energy levels using known molecular parameters (Pearson et al., 2012; Coudert et al., 2014; El Hilali et al., 2011; Quade et al., 1998; Richard Quade, 1998, 1999; Mukhopadhyay, 1997) and the actually observed FIR lines. The upper levels are seen to be upshifted from expected position. A closer look at the calculated energy values seems to indicate a possible interaction between the above states and other proximate torsional-rotational states could occur. The possible candidates for the interacting level manifolds are narrowed down through the presence of the forbidden transition. We also take the opportunity to propose alternate rotational quantum numbers for some of the assignments recently reported in the literature (El Hilali et al., 2011). Some ambiguities are pointed out on the data and the reported analysis. There remain too many such irregularities and we propose to gather a large body assigned transitions in a future catalog. Assignments and relevant comments on optically pumped FIR laser radiation are also made.

  1. In vivo optical imaging of tumor and microvascular response to ionizing radiation.

    Directory of Open Access Journals (Sweden)

    Azusa Maeda

    Full Text Available Radiotherapy is a widely used cancer treatment. However, understanding how ionizing radiation affects tumor cells and their vasculature, particularly at cellular, subcellular, genetic, and protein levels, has been limited by an inability to visualize the response of these interdependent components within solid tumors over time and in vivo. Here we describe a new preclinical experimental platform combining intravital multimodal optical microscopy for cellular-level longitudinal imaging, a small animal x-ray microirradiator for reproducible spatially-localized millimeter-scale irradiations, and laser-capture microdissection of ex vivo tissues for transcriptomic profiling. Using this platform, we have developed new methods that exploit the power of optically-enabled microscopic imaging techniques to reveal the important role of the tumor microvasculature in radiation response of tumors. Furthermore, we demonstrate the potential of this preclinical platform to study quantitatively--with cellular and sub-cellular details--the spatio-temporal dynamics of the biological response of solid tumors to ionizing radiation in vivo.

  2. In vivo optical imaging of tumor and microvascular response to ionizing radiation.

    Science.gov (United States)

    Maeda, Azusa; Leung, Michael K K; Conroy, Leigh; Chen, Yonghong; Bu, Jiachuan; Lindsay, Patricia E; Mintzberg, Shani; Virtanen, Carl; Tsao, Julissa; Winegarden, Neil A; Wang, Yanchun; Morikawa, Lily; Vitkin, I Alex; Jaffray, David A; Hill, Richard P; DaCosta, Ralph S

    2012-01-01

    Radiotherapy is a widely used cancer treatment. However, understanding how ionizing radiation affects tumor cells and their vasculature, particularly at cellular, subcellular, genetic, and protein levels, has been limited by an inability to visualize the response of these interdependent components within solid tumors over time and in vivo. Here we describe a new preclinical experimental platform combining intravital multimodal optical microscopy for cellular-level longitudinal imaging, a small animal x-ray microirradiator for reproducible spatially-localized millimeter-scale irradiations, and laser-capture microdissection of ex vivo tissues for transcriptomic profiling. Using this platform, we have developed new methods that exploit the power of optically-enabled microscopic imaging techniques to reveal the important role of the tumor microvasculature in radiation response of tumors. Furthermore, we demonstrate the potential of this preclinical platform to study quantitatively--with cellular and sub-cellular details--the spatio-temporal dynamics of the biological response of solid tumors to ionizing radiation in vivo.

  3. Antivascular Endothelial Growth Factor Bevacizumab for Radiation Optic Neuropathy: Secondary to Plaque Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Finger, Paul T., E-mail: pfinger@eyecancer.com [New York Eye Cancer Center, New York, NY (United States); Chin, Kimberly J. [New York Eye Cancer Center, New York, NY (United States)

    2012-02-01

    Purpose: To evaluate the intravitreal antivascular endothelial growth factor, bevacizumab, for treatment of radiation optic neuropathy (RON). Methods and Materials: A prospective interventional clinical case series was performed of 14 patients with RON related to plaque radiotherapy for choroidal melanoma. The RON was characterized by optic disc edema, hemorrhages, microangiopathy, and neovascularization. The entry criteria included a subjective or objective loss of vision, coupled with findings of RON. The study subjects received a minimum of two initial injections of intravitreal bevacizumab (1.25 mg in 0.05 mL) every 6-8 weeks. The primary objectives included safety and tolerability. The secondary objectives included the efficacy as measured using the Early Treatment Diabetic Retinopathy Study chart for visual acuity, fundus photography, angiography, and optical coherence tomography/scanning laser ophthalmoscopy. Results: Reductions in optic disc hemorrhage and edema were noted in all patients. The visual acuity was stable or improved in 9 (64%) of the 14 patients. Of the 5 patients who had lost vision, 2 had relatively large posterior tumors, 1 had had the vision decrease because of intraocular hemorrhage, and 1 had developed optic atrophy. The fifth patient who lost vision was noncompliant. No treatment-related ocular or systemic side effects were observed. Conclusions: Intravitreal antivascular endothelial growth factor bevacizumab was tolerated and generally associated with improved vision, reduced papillary hemorrhage, and resolution of optic disc edema. Persistent optic disc neovascularization and fluorescein angiographic leakage were invariably noted. The results of the present study support additional evaluation of antivascular endothelial growth factor medications as treatment of RON.

  4. Radiation-hard ASICs for optical data transmission in the ATLAS pixel detector

    CERN Document Server

    Ziolkowski, M; Buchholz, P; Ciliox, A; Gan, K K; Holder, M; Johnson, M; Kagan, H; Kass, R; Nderitu, S; Rahimi, A; Rush, C J; Smith, S; Ter-Antonian, R; Zoeller, M M

    2004-01-01

    We have developed two radiation-hard ASICs for optical data transmission in the ATLAS pixel detector at the CERN Large Hadron Collider (LHC). The first circuit is a driver chip for a Vertical Cavity Surface Emitting Laser (VCSEL) diode to be used for 80 Mbit/s data transmission from the detector. The second circuit is a Bi-Phase Mark, decoder chip to recover the control data and 40 MHz clock received optically by a PIN diode on the detector side. During ten years of operation at the LHC, the ATLAS optical link circuitry will be exposed to a maximum total fluence of 10/sup 15/ 1-MeV-equivalent neutrons per cm/sup 2/. We have successfully implemented both ASICs in a commercial 0.25 mu m CMOS technology using standard layout techniques to enhance the radiation tolerance. Both chips are four- channel devices compatible with common cathode PIN and VCSEL arrays. We present results from final prototype circuits and from irradiation studies of both circuits with 24 GeV protons up to a total dose of 57 Mrad. (3 refs).

  5. Performance of the ATLAS Transition Radiation Tracker with Comic Rays and First High Energy Collisions at LHC

    CERN Document Server

    Degenhardt, J D; The ATLAS collaboration

    2010-01-01

    The ATLAS Transition Radiation Tracker (TRT) is the outermost of the three sub-systems of the ATLAS Inner Detector at the Large Hadron Collider (LHC) at CERN. It consists of close to 300000 thin-wall drift tubes (straws) providing on average 30 two-dimensional space points with 130 μm resolution for charged particle tracks with |η| < 2 and pT > 0.5 GeV. Along with continuous tracking, it provides particle identification capability through the detection of transition radiation X-ray photons generated by high velocity particles in the many polymer fibers or films that fill the spaces between the straws. The custom-made radiation-hard front-end electronics implements two thresholds to discriminate the signals: a low threshold (< 300 eV) for registering the passage of minimum ionizing particles, and a high threshold (> 6 keV) to flag the absorption of transition radiation X-rays. The TRT was successfully commissioned with data collected from several million cosmic ray muons. A specia...

  6. Stochastic dynamic study of optical transition properties of single GFP-like molecules.

    Science.gov (United States)

    Lin, Hanbing; Yuan, Jian-Min

    2016-03-01

    Due to high fluctuations and quantum uncertainty, the processes of single-molecules should be treated by stochastic methods. To study fluorescence time series and their statistical properties, we have applied two stochastic methods, one of which is an analytic method to study the off-time distributions of certain fluorescence transitions and the other is Gillespie's method of stochastic simulations. These methods have been applied to study the optical transition properties of two single-molecule systems, GFPmut2 and a Dronpa-like molecule, to yield results in approximate agreement with experimental observations on these systems. Rigorous oscillatory time series of GFPmut2 before it unfolds in the presence of denaturants have not been obtained based on the stochastic method used, but, on the other hand, the stochastic treatment puts constraints on the conditions under which such oscillatory behavior is possible. Furthermore, a sensitivity analysis is carried out on GFPmut2 to assess the effects of transition rates on the observables, such as fluorescence intensities.

  7. Wavelength dependent measurements of optical fiber transit time, material dispersion, and attenuation

    Energy Technology Data Exchange (ETDEWEB)

    COCHRANE,KYLE ROBERT; BAILEY,JAMES E.; LAKE,PATRICK WAYNE; CARLSON,ALAN L.

    2000-04-18

    A new method for measuring the wavelength dependence of the transit time, material dispersion, and attenuation of an optical fiber is described. The authors inject light from a 4-ns risetime pulsed broad-band flashlamp into various length fibers and record the transmitted signals with a time-resolved spectrograph. Segments of data spanning an approximately 3,000 {angstrom} range are recorded from a single flashlamp pulse. Comparison of data acquired with short and long fibers enables the determination of the transit time and the material dispersion as functions of wavelength dependence for the entire recorded spectrum simultaneously. The wavelength dependent attenuation is also determined from the signal intensities. The method is demonstrated with experiments using a step index 200-{micro}m-diameter SiO{sub 2} fiber. The results agree with the transit time determined from the bulk glass refractive index to within {+-} 0.035% for the visible (4,000--7,200 {angstrom}) spectrum and 0.12% for the ultraviolet (2,650--4,000 {angstrom}) spectrum, and with the attenuation specified by the fiber manufacturer to within {+-} 10%.

  8. $W$ mass measurement and simulation of the transition radiation tracker at the ATLAS experiment

    CERN Document Server

    Klinkby, Esben Bryndt

    2008-01-01

    At the time of writing, the final preparation toward LHC startup is ongoing. All the magnets of the machine have been installed and are currently being cooled. Most sub-detectors of the four experiments situated at the LHC ring are installed in their final positions and are being integrated into their respective data acquisition systems. This thesis concerns itself with the ATLAS experiment, focusing on a sub-detector called the Transition Radiation Tracker (TRT). Some attention is given to the hardware testing of the detector modules, but the main focus lies on the simulation of the detector and the comparison of the simulation with test-beam data, as well as with data collected during the commissioning phase using cosmic muons. There is little doubt that LHC will bring insight with respect to the understanding of the universe on the fundamental level. In particular, it is anticipated that light will be shed on the origin of mass which according to our current understanding proceeds via the Higgs mechanism. ...

  9. Performance of the ATLAS Transition Radiation Tracker in Run 1 of the LHC: tracker properties

    CERN Document Server

    Aaboud, Morad; Abbott, Brad; Abdallah, Jalal; Abdinov, Ovsat; Abeloos, Baptiste; Abidi, Syed Haider; AbouZeid, Ossama; Abraham, Nicola; Abramowicz, Halina; Abreu, Henso; Abreu, Ricardo; Abulaiti, Yiming; Acharya, Bobby Samir; Adachi, Shunsuke; Adamczyk, Leszek; Adams, David; Adelman, Jahred; Adersberger, Michael; Adye, Tim; Affolder, Tony; Agatonovic-Jovin, Tatjana; Agheorghiesei, Catalin; Aguilar-Saavedra, Juan Antonio; Ahlen, Steven; Ahmadov, Faig; Aielli, Giulio; Akatsuka, Shunichi; Akerstedt, Henrik; Åkesson, Torsten Paul Ake; Akimov, Andrei; Alberghi, Gian Luigi; Albert, Justin; Alconada Verzini, Maria Josefina; Aleksa, Martin; Aleksandrov, Igor; Alexa, Calin; Alexander, Gideon; Alexopoulos, Theodoros; Alhroob, Muhammad; Ali, Babar; Aliev, Malik; Alimonti, Gianluca; Alison, John; Alkire, Steven Patrick; Allbrooke, Benedict; Allen, Benjamin William; Allport, Phillip; Aloisio, Alberto; Alonso, Alejandro; Alonso, Francisco; Alpigiani, Cristiano; Alshehri, Azzah Aziz; Alstaty, Mahmoud; Alvarez Gonzalez, Barbara; Άlvarez Piqueras, Damián; Alviggi, Mariagrazia; Amadio, Brian Thomas; Amaral Coutinho, Yara; Amelung, Christoph; Amidei, Dante; Amor Dos Santos, Susana Patricia; Amorim, Antonio; Amoroso, Simone; Amundsen, Glenn; Anastopoulos, Christos; Ancu, Lucian Stefan; Andari, Nansi; Andeen, Timothy; Anders, Christoph Falk; Anders, John Kenneth; Anderson, Kelby; Andreazza, Attilio; Andrei, George Victor; Angelidakis, Stylianos; Angelozzi, Ivan; Angerami, Aaron; Anghinolfi, Francis; Anisenkov, Alexey; Anjos, Nuno; Annovi, Alberto; Antel, Claire; Antonelli, Mario; Antonov, Alexey; Antrim, Daniel Joseph; Anulli, Fabio; Aoki, Masato; Aperio Bella, Ludovica; Arabidze, Giorgi; Arai, Yasuo; Araque, Juan Pedro; Araujo Ferraz, Victor; Arce, Ayana; Ardell, Rose Elisabeth; Arduh, Francisco Anuar; Arguin, Jean-Francois; Argyropoulos, Spyridon; Arik, Metin; Armbruster, Aaron James; Armitage, Lewis James; Arnaez, Olivier; Arnold, Hannah; Arratia, Miguel; Arslan, Ozan; Artamonov, Andrei; Artoni, Giacomo; Artz, Sebastian; Asai, Shoji; Asbah, Nedaa; Ashkenazi, Adi; Asquith, Lily; Assamagan, Ketevi; Astalos, Robert; Atkinson, Markus; Atlay, Naim Bora; Augsten, Kamil; Avolio, Giuseppe; Axen, Bradley; Ayoub, Mohamad Kassem; Azuelos, Georges; Baas, Alessandra; Baca, Matthew John; Bachacou, Henri; Bachas, Konstantinos; Backes, Moritz; Backhaus, Malte; Bagiacchi, Paolo; Bagnaia, Paolo; Baines, John; Bajic, Milena; Baker, Oliver Keith; Baldin, Evgenii; Balek, Petr; Balestri, Thomas; Balli, Fabrice; Balunas, William Keaton; Banas, Elzbieta; Banerjee, Swagato; Bannoura, Arwa A E; Barak, Liron; Barberio, Elisabetta Luigia; Barberis, Dario; Barbero, Marlon; Barillari, Teresa; Barisits, Martin-Stefan; Barklow, Timothy; Barlow, Nick; Barnes, Sarah Louise; Barnett, Bruce; Barnett, Michael; Barnovska-Blenessy, Zuzana; Baroncelli, Antonio; Barone, Gaetano; Barr, Alan; Barranco Navarro, Laura; Barreiro, Fernando; Barreiro Guimarães da Costa, João; Bartoldus, Rainer; Barton, Adam Edward; Bartos, Pavol; Basalaev, Artem; Bassalat, Ahmed; Bates, Richard; Batista, Santiago Juan; Batley, Richard; Battaglia, Marco; Bauce, Matteo; Bauer, Florian; Bawa, Harinder Singh; Beacham, James; Beattie, Michael David; Beau, Tristan; Beauchemin, Pierre-Hugues; Bechtle, Philip; Beck, Hans~Peter; Becker, Kathrin; Becker, Maurice; Beckingham, Matthew; Becot, Cyril; Beddall, Andrew; Beddall, Ayda; Bednyakov, Vadim; Bedognetti, Matteo; Bee, Christopher; Beermann, Thomas; Begalli, Marcia; Begel, Michael; Behr, Janna Katharina; Bell, Andrew Stuart; Bella, Gideon; Bellagamba, Lorenzo; Bellerive, Alain; Bellomo, Massimiliano; Belotskiy, Konstantin; Beltramello, Olga; Belyaev, Nikita; Benary, Odette; Benchekroun, Driss; Bender, Michael; Bendtz, Katarina; Benekos, Nektarios; Benhammou, Yan; Benhar Noccioli, Eleonora; Benitez, Jose; Benjamin, Douglas; Benoit, Mathieu; Bensinger, James; Bentvelsen, Stan; Beresford, Lydia; Beretta, Matteo; Berge, David; Bergeaas Kuutmann, Elin; Berger, Nicolas; Beringer, Jürg; Berlendis, Simon; Bernard, Nathan Rogers; Bernardi, Gregorio; Bernius, Catrin; Bernlochner, Florian Urs; Berry, Tracey; Berta, Peter; Bertella, Claudia; Bertoli, Gabriele; Bertolucci, Federico; Bertram, Iain Alexander; Bertsche, Carolyn; Bertsche, David; Besjes, Geert-Jan; Bessidskaia Bylund, Olga; Bessner, Martin Florian; Besson, Nathalie; Betancourt, Christopher; Bethani, Agni; Bethke, Siegfried; Bevan, Adrian John; Bianchi, Riccardo-Maria; Bianco, Michele; Biebel, Otmar; Biedermann, Dustin; Bielski, Rafal; Biesuz, Nicolo Vladi; Biglietti, Michela

    2017-01-01

    The tracking performance parameters of the ATLAS Transition Radiation Tracker (TRT) as part of the ATLAS inner detector are described in this paper for different data-taking conditions in proton--proton, proton--lead and lead--lead collisions at the Large Hadron Collider (LHC). The performance is studied using data collected for different data-taking conditions in proton--proton, proton--lead and lead--lead collisions at the Large Hadron Collider (LHC). The performance is studied using data collected during the first period of LHC operation (Run 1) and is compared with Monte Carlo simulations. The performance of the TRT, operating with two different gas mixtures (xenon-based and argon-based) and its dependence on the TRT occupancy is presented. These studies show that the tracking performance of the TRT is similar for the two gas mixtures and that a significant contribution to the particle momentum resolution is made by the TRT up to high particle densities.

  10. A new transition radiation detector to detect heavy nuclei around the knee

    Science.gov (United States)

    Boyle, Patrick J.; Swordy, Simon P.; Wakely, Scott P.

    2003-02-01

    The overall cosmic ray intensity spectrum falls as a constant power law over at least 11 decades of particle energy. One of the only features in this spectrum is the slight change in power law index near 1015 eV, often called the ‘knee" of the spectrum. Accurate measurements of cosmic ray elemental abundances into this energy region are expected to reveal the origin of this feature, and possibly the nature of cosmic ray sources. The extremely low intensity of particles at these energies (a few per m2 per year) makes the detection challenging. Since only direct measurements have so far proved reliable for the accurate determination of elemental composition, a large-area, light weight, device is needed to achieve long exposures above the atmosphere either on high-altitude balloons or spacecraft. Here we report on a detector which uses the x-ray transition radiation yield from plastic foams to provide a response into the knee region for heavy elements. We use individual xenon-filled gas proportional tubes as detectors, combined with Amplex ASIC chip electronics for readout. The construction of this type of detector, and its implementation in the upcoming NASA CREAM 100 day high-altitude balloon payload is described. Also discussed is the calibration of the detector in an accelerator beam at CERN and a comparison with GEANT4 Monet Carlo simulations.

  11. A new transition radiation detector to detect heavy nuclei around the knee

    CERN Document Server

    Boyle, P J; Wakely, S P

    2002-01-01

    The overall cosmic ray intensity spectrum falls as a constant power law over at least 11 decades of particle energy. One of the only features in this spectrum is the slight change in power law index near 10**1**5eV, often called the 'knee' of the spectrum. Accurate measurements of cosmic ray elemental abundances into this energy region are expected to reveal the origin of this feature, and possibly the nature of cosmic ray sources. The extremely low intensity of particles at these energies (a few per m**2 per year) makes the detection challenging. Since only direct measurements have so far proved reliable for the accurate determination of elemental composition, a large-area, light weight, device is needed to achieve long exposures above the atmosphere - either on high-altitude balloons or spacecraft. Here we report on a detector which uses the x-ray transition radiation yield from plastic foams to provide a response into the knee region for heavy elements. We use individual xenon-filled gas proportional tubes...

  12. Performance of the ATLAS Transition Radiation Tracker Readout with High Energy Collisions at the LHC

    CERN Document Server

    Wagner, P; The ATLAS collaboration

    2011-01-01

    The ATLAS Transition Radiation Tracker (TRT) is the outermost of the three subsystems of the ATLAS Inner Detector containing close to 350,000 thin-wall drift tubes (straws) operated with a Xenon-based gas mixture. The TRT data acquisition uses two separate front-end ASICS: the ASDBLR (analog) and DTMROC (digital). The eight-channel ASDBLR (Amplifier, Shaper, Discriminator and BaseLine Restorer) provides a three level out using two thresholds: a low one for tracking and a high one for electron identification. Two ASDBLR chips input into a single, sixteen-channel DTMROC (Digital Time Measurement and ReadOut Chip), which encodes the time over low (high) threshold in 3.125 ns (25 ns) time steps in a programmable depth pipeline awaiting a level 1 trigger. When a level 1 trigger is received, three LHC bunch crossings worth of data (75 ns) are read out. The DTMROC also provides a "Fast-OR" signal of its inputs, which has been utilized to build a level 1 trigger for cosmic rays traversing the ATLAS Inner Detector. Th...

  13. Ultrafast all-optical order-to-chaos transition in silicon photonic crystal chips

    KAUST Repository

    Bruck, Roman

    2016-06-08

    The interaction of light with nanostructured materials provides exciting new opportunities for investigating classical wave analogies of quantum phenomena. A topic of particular interest forms the interplay between wave physics and chaos in systems where a small perturbation can drive the behavior from the classical to chaotic regime. Here, we report an all-optical laser-driven transition from order to chaos in integrated chips on a silicon photonics platform. A square photonic crystal microcavity at telecom wavelengths is tuned from an ordered into a chaotic regime through a perturbation induced by ultrafast laser pulses in the ultraviolet range. The chaotic dynamics of weak probe pulses in the near infrared is characterized for different pump-probe delay times and at various positions in the cavity, with high spatial accuracy. Our experimental analysis, confirmed by numerical modelling based on random matrices, demonstrates that nonlinear optics can be used to control reversibly the chaotic behavior of light in optical resonators. (Figure presented.) . © 2016 by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  14. Size-dependent nonlinear optical properties of atomically thin transition metal dichalcogenide nanosheets.

    Science.gov (United States)

    Zhou, Kai-Ge; Zhao, Min; Chang, Meng-Jie; Wang, Qiang; Wu, Xin-Zhi; Song, Yinglin; Zhang, Hao-Li

    2015-02-11

    Size-dependent nonlinear optical properties of modification-free transition metal dichalcogenide (TMD) nanosheets are reported, including MoS2 , WS2 , and NbSe2 . Firstly, a gradient centrifugation method is demonstrated to separate the TMD nanosheets into different sizes. The successful size separation allows the study of size-dependent nonlinear optical properties of nanoscale TMD materials for the first time. Z-scan measurements indicate that the dispersion of MoS2 and WS2 nanosheets that are 50-60 nm thick leads to reverse saturable absorption (RSA), which is in contrast to the saturable absorption (SA) seen in the thicker samples. Moreover, the NbSe2 nanosheets show no size-dependent effects because of their metallic nature. The mechanism behind the size-dependent nonlinear optical properties of the semiconductive TMD nanosheets is revealed by transient transmission spectra measurements. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Application of red and near infrared emission from rare earth ions for radiation measurements based on optical fibers

    Energy Technology Data Exchange (ETDEWEB)

    Takada, E.; Hosono, Y.; Takahashi, H.; Nakazawa, M. [Univ. of Tokyo (Japan). Dept. of Quantum Engineering and Systems Science; Kakuta, T. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan); Yamazaki, M. [Sumita Optical Glass, Inc., Urawa, Saitama (Japan)

    1998-06-01

    When optical fiber radiation measurements are applied for a high dose rate area, there has been a problem of radiation induced loss in the optical fibers. In this study, red and near infrared (IR) fluorescence from rare earth ions has been used to reduce the problem. From continuous measurements using Gd{sub 2}O{sub 2}S:Pr{sup 3+}, the superiority of using long wavelength emission has been shown from the view point of radiation hardness. Linear relation between dose rate and peak counts was confirmed and it shows the possibility of using the long wavelength emission for radiation measurements. For calibration of the radiation induced loss, the Optical Time Domain Reflectometry (OTDR) technique has been applied. It has been shown that this method can broaden the dose rate limit of the optical fiber based measurements. Also, glass samples doped with rare-earth ions have been made and irradiated by gamma rays. Emission at longer wavelength than 700 nm has been observed for Eu{sup 3+} ions doped into silica, fluorophosphate and ZBLAN glass samples. Considering that it is easy to make silica glass and to connect it to usual silica glass optical fiber, silica glass doped with Eu{sup 3+} is thought to be the most promising material for new scintillating fibers with high radiation resistivity.

  16. Optical and luminescence studies of ZnMoO 4 using vacuum ultraviolet synchrotron radiation

    Science.gov (United States)

    Mikhailik, V. B.; Kraus, H.; Wahl, D.; Ehrenberg, H.; Mykhaylyk, M. S.

    2006-06-01

    In this paper we present a characterisation of ZnMoO 4 using spectroscopic techniques. Reflection, luminescence and luminescence excitation spectra were measured over the temperature range 8-295 K using VUV synchrotron radiation. The emission spectrum of the crystal exhibits a broad band with a maximum around 1.95 eV at 80 K that is attributed to the radiative transitions within MO 42- oxyanion complex. An interpretation of the observed features of the electronic excitations in the crystal is given based on present knowledge of the electronic structure and emission properties of molybdate crystals. The results of this study suggest that ZnMoO 4 is a suitable candidate for further testing for implementation as a target material in cryogenic scintillation searches for rare events.

  17. Optical and luminescence studies of ZnMoO{sub 4} using vacuum ultraviolet synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Mikhailik, V.B. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom)]. E-mail: vmikhai@hotmail.com; Kraus, H. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Wahl, D. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Ehrenberg, H. [Material Science, Darmstadt University of Technology, Petersenstr. 23, Darmstadt 64287 (Germany); Mykhaylyk, M.S. [Physics Department, Lviv National University, 8 Kyryla and Mefodiya str., Lviv, 79005 (Ukraine)

    2006-06-15

    In this paper we present a characterisation of ZnMoO{sub 4} using spectroscopic techniques. Reflection, luminescence and luminescence excitation spectra were measured over the temperature range 8-295 K using VUV synchrotron radiation. The emission spectrum of the crystal exhibits a broad band with a maximum around 1.95 eV at 80 K that is attributed to the radiative transitions within MO{sub 4} {sup 2-} oxyanion complex. An interpretation of the observed features of the electronic excitations in the crystal is given based on present knowledge of the electronic structure and emission properties of molybdate crystals. The results of this study suggest that ZnMoO{sub 4} is a suitable candidate for further testing for implementation as a target material in cryogenic scintillation searches for rare events.

  18. Planar KrCl* excilamp pumped by transverse self-sustained discharge with optical system for radiation concentration

    Energy Technology Data Exchange (ETDEWEB)

    Panchenko, A N [High-current Electronics Institute, Academicheskiy Av., 2/3, Tomsk 634055 (Russian Federation); Tarasenko, V F [High-current Electronics Institute, Academicheskiy Av., 2/3, Tomsk 634055 (Russian Federation); Belokurov, A N [INVAP S.E. Company, F.P.Moreno, 1089, CP8400, S.C. de Bariloche, Rio Negro (Argentina); Mendoza, P [INVAP S.E. Company, F.P.Moreno, 1089, CP8400, S.C. de Bariloche, Rio Negro (Argentina); Rios, I [INVAP S.E. Company, F.P.Moreno, 1089, CP8400, S.C. de Bariloche, Rio Negro (Argentina)

    2006-07-15

    The design and emission parameters of a spontaneous radiation source (excilamp) at a 222 nm wavelength are presented. To obtain a high-power UV radiation, a volume transverse discharge was used in the high-pressure Ne-Kr-HCl mixture. A radiation power density of 1 kW cm{sup -2} was gained at the excilamp output at a 2 mJ pulse energy. Successful attempts were made to synchronize the excilamp pulse with the pulse of second laser source. An optical system was developed to deliver and concentrate the UV radiation on to the area with a specified geometry. The method of modelling and analysis technique of the optical system using the OptiCAD 9.3 Optical Analysis Program software is described, as well.

  19. Optical effects of exposing intact human lenses to ultraviolet radiation and visible light

    DEFF Research Database (Denmark)

    Kessel, Line; Eskildsen, Lars; Lundeman, Jesper Holm

    2011-01-01

    BACKGROUND: The human lens is continuously exposed to high levels of light. Ultraviolet radiation is believed to play a causative role in the development of cataract. In vivo, however, the lens is mainly exposed to visible light and the ageing lens absorbs a great part of the short wavelength...... region of incoming visible light. The aim of the present study was to examine the optical effects on human lenses of short wavelength visible light and ultraviolet radiation. METHODS: Naturally aged human donor lenses were irradiated with UVA (355 nm), violet (400 and 405 nm) and green (532 nm) lasers....... The effect of irradiation was evaluated qualitatively by photography and quantitatively by measuring the direct transmission before and after irradiation. Furthermore, the effect of pulsed and continuous laser systems was compared as was the effect of short, intermediate and prolonged exposures. RESULTS...

  20. Optical effects of exposing intact human lenses to ultraviolet radiation and visible light

    DEFF Research Database (Denmark)

    Kessel, Line; Eskildsen, Lars Baunsgaard; Lundeman, Jesper Holm

    2011-01-01

    ABSTRACT: BACKGROUND: The human lens is continuously exposed to high levels of light. Ultraviolet radiation is believed to play a causative role in the development of cataract. In vivo, however, the lens is mainly exposed to visible light and the ageing lens absorbs a great part of the short...... wavelength region of incoming visible light. The aim of the present study was to examine the optical effects on human lenses of short wavelength visible light and ultraviolet radiation. METHODS: Naturally aged human donor lenses were irradiated with UVA (355 nm), violet (400 and 405 nm) and green (532 nm......) lasers. The effect of irradiation was evaluated qualitatively by photography and quantitatively by measuring the direct transmission before and after irradiation. Furthermore, the effect of pulsed and continuous laser systems was compared as was the effect of short, intermediate and prolonged exposures...