WorldWideScience

Sample records for strong intensity scintillations

  1. Strong scintillations during atmospheric occultations Theoretical intensity spectra. [radio scattering during spacecraft occultations by planetary atmospheres

    Science.gov (United States)

    Hinson, D. P.

    1986-01-01

    Each of the two Voyager spacecraft launched in 1977 has completed a reconnaissance of the Jovian and Saturnian systems. In connection with occultation experiments, strong scintillations were observed. Further theoretical work is required before these scintillations can be interpreted. The present study is, therefore, concerned with the derivation of a theory for strong scattering during atmospheric occultation experiments, taking into account as fundamental quantity of interest the spatial spectrum (or spectral density) of intensity fluctuations. Attention is given to a theory for intensity spectra, and numerical calculations. The new formula derived for Phi-i accounts for strong scattering of electromagnetic waves during atmospheric occultations.

  2. arXiv Strong reduction of the effective radiation length in an oriented PWO scintillator crystal

    CERN Document Server

    Bandiera, L.; Romagnoni, M.; Argiolas, N.; Bagli, E.; Ballerini, G.; Berra, A.; Brizzolani, C.; Camattari, R.; De Salvador, D.; Haurylavets, V.; Mascagna, V.; Mazzolari, A.; Prest, M.; Soldani, M.; Sytov, A.; Vallazza, E.

    We measured a considerable increase of the emitted radiation by 120 GeV/c electrons in an axially oriented lead tungstate scintillator crystal, if compared to the case in which the sample was not aligned with the beam direction. This enhancement resulted from the interaction of particles with the strong crystalline field. The data collected at the external lines of CERN SPS were critically compared to Monte Carlo simulations based on the Baier Katkov quasiclassical method, highlighting a reduction of the scintillator radiation length by a factor of five in case of beam alignment with the [001] crystal axes. As a consequence, oriented scintillator crystals may be profitably exploited to reduce the amount of material in electromagnetic calorimeters/detectors for fixed-target experiments in high-energy physics, as well as for satellite-borne gamma-telescopes in astrophysics.

  3. Intense Shock Waves and Strongly Coupled Plasmas

    Science.gov (United States)

    Fortov, Vladimir

    2005-07-01

    The report presents the recent results of experimental investigations of equations of state, compositions, thermodynamical and transport properties, electrical conductivity and opacity of strongly coupled plasmas generated by intense shock and rarefaction waves. The experimental methods for generation of high energy densities in matter, drivers for shock waves and fast diagnostic tools are discussed. Application of intense shock waves to solid and porous targets generates nonideal plasmas in megabar-gigabar pressure range. Compression of plasma by a series of reverberating shock waves allows us to decrease irreversible heating effects. To increase the irreversibility effects and to generate high temperature plasma states the experiments on shock compression of porous samples (fine metal powder, aerogels) were performed. The adiabatic expansion of matter initially compressed by intense shocks up to megabars allows investigating the intermediate region between the solid and vapor phase of nonideal plasmas, including the metal-insulator transition phase and the high temperature saturation curve with critical points of metals. The shock-wave-induced non-equilibrium phenomena at fast melting, spallation and adiabatic condensation are analyzed in the framework of the interspinodal decomposition model. The spall strength of single and polycrystal metals at extremely fast deformation produced by fast shock waves is discussed. The ``pressure ionization'' phenomena in hydrogen, helium, argon, xenon, krypton, neon, iodine, silica, sulfur, fullerenes, and some metals are analyzed on the base of multiple shock compression experiments. For some simple metals (Li, Na, Ca) the effect of ``dielectrization'' as a result of multiple shock compression are discussed.

  4. Outflow structure of the quiet sun corona probed by spacecraft radio scintillations in strong scattering

    Energy Technology Data Exchange (ETDEWEB)

    Imamura, Takeshi; Ando, Hiroki; Toda, Tomoaki; Nakamura, Masato [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Tokumaru, Munetoshi; Shiota, Daikou [Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 484-8601 (Japan); Isobe, Hiroaki; Asai, Ayumi [Unit of Synergetic Studies for Space, Kyoto University, Yamashina, Kyoto 607-8471, Japan. (Japan); Miyamoto, Mayu [Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Häusler, Bernd [Institut für Raumfahrttechnik, Universität der Bundeswehr München, D-85577 Neubiberg (Germany); Pätzold, Martin [Rheinisches Institut für Umweltforschung, Department Planetenforschung, Universität zu Köln, Aachener Strasse 209, D-50931 Köln (Germany); Nabatov, Alexander [The Institute of Radio Astronomy, National Academy of Science of Ukraine, Chervonoprapornaya, Strasse 4, Kharkov 61002 (Ukraine); Yaji, Kentaro [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Yamada, Manabu, E-mail: imamura.takeshi@jaxa.jp [Planetary Exploration Research Center, Chiba Institute of Technology, 2-17-1, Tsudanuma, Narashino, Chiba 275-0016 (Japan)

    2014-06-20

    Radio scintillation observations have been unable to probe flow speeds in the low corona where the scattering of radio waves is exceedingly strong. Here we estimate outflow speeds continuously from the vicinity of the Sun to the outer corona (heliocentric distances of 1.5-20.5 solar radii) by applying the strong scattering theory to radio scintillations for the first time, using the Akatsuki spacecraft as the radio source. Small, nonzero outflow speeds were observed over a wide latitudinal range in the quiet-Sun low corona, suggesting that the supply of plasma from closed loops to the solar wind occurs over an extended area. The existence of power-law density fluctuations down to the scale of 100 m was suggested, which is indicative of well-developed turbulence which can play a key role in heating the corona. At higher altitudes, a rapid acceleration typical of radial open fields is observed, and the temperatures derived from the speed profile show a distinct maximum in the outer corona. This study opened up a possibility of observing detailed flow structures near the Sun from a vast amount of existing interplanetary scintillation data.

  5. Higher order mode laser beam intensity fluctuations in strong oceanic turbulence

    Science.gov (United States)

    Baykal, Yahya

    2017-05-01

    Intensity fluctuations of the higher order mode laser beams are evaluated when these beams propagate in a medium exhibiting strong oceanic turbulence. Our formulation involves the modified Rytov solution that extends the Rytov solution to cover strong turbulence as well, and our recently reported expression that relates the atmospheric turbulence structure constant to the oceanic turbulence parameters and oceanic wireless optical communication link parameters. The variations of the intensity fluctuations are reported against the changes of the ratio of temperature to salinity contributions to the refractive index spectrum, rate of dissipation of kinetic energy per unit mass of fluid, rate of dissipation of mean-squared temperature, viscosity and the source size of the higher order mode laser beam. Our results indicate that under any oceanic turbulence parameters, it is advantageous to employ higher order laser modes in reducing the scintillation noise in wireless optical communication links operating in a strongly turbulent ocean.

  6. Analysis and comparison model for measuring tropospheric scintillation intensity for Ku-band frequency in Malaysia

    Directory of Open Access Journals (Sweden)

    Mandeep JS

    2011-06-01

    Full Text Available This study has been based on understanding local propagation signal data distribution characteristics and identifying and predicting the overall impact of significant attenuating factors regarding the propagation path such as impaired propagation for a signal being transmitted. Predicting propagation impairment is important for accurate link budgeting, thereby leading to better communication network system designation. This study has thus used sample data for one year concerning beacon satellite operation in Malaysia from April 2008 to April 2009. Data concerning 12GHz frequency (Ku-band and 40° elevation angle was collected and analysed, obtaining average signal amplitude value, ÷ and also standard deviation ó which is normally measured in dB to obtain long-term scintillation intensity distribution. This analysis showed that scintillation intensity distribution followed Gaussian distribution for long-term data distribution. A prediction model was then selected based on the above; Karasawa,
    ITU-R, Van de Kamp and Otung models were compared to obtain the best prediction model performance for selected data regarding specific meteorological conditions. This study showed that the Karasawa model had the best performance for predicting scintillation intensity for the selected da ta.

  7. The measurement of interplanetary scintillations in conditions of strong radio interference

    International Nuclear Information System (INIS)

    Duffett-Smith, P.J.

    1980-01-01

    Observations of interplanetary scintillations (IPS) are often severely limited by interference from man-made transmissions within the receiver pass-band. A new method of measuring IPS is described which can give useful data even in conditions of bad interference. (author)

  8. Intensities and strong interaction attenuation of kaonic x-rays

    CERN Document Server

    Backenstoss, Gerhard; Koch, H; Povel, H P; Schwitter, A; Tauscher, Ludwig

    1974-01-01

    Relative intensities of numerous kaonic X-ray transitions have been measured for the elements C, P, S, and Cl, from which level widths due to the strong K-nucleus absorption have been determined. From these and earlier published data, optical potential parameters have been derived and possible consequences on the nuclear matter distribution are discussed. (10 refs).

  9. Earthquake Intensity and Strong Motion Analysis Within SEISCOMP3

    Science.gov (United States)

    Becker, J.; Weber, B.; Ghasemi, H.; Cummins, P. R.; Murjaya, J.; Rudyanto, A.; Rößler, D.

    2017-12-01

    Measuring and predicting ground motion parameters including seismic intensities for earthquakes is crucial and subject to recent research in engineering seismology.gempa has developed the new SIGMA module for Seismic Intensity and Ground Motion Analysis. The module is based on the SeisComP3 framework extending it in the field of seismic hazard assessment and engineering seismology. SIGMA may work with or independently of SeisComP3 by supporting FDSN Web services for importing earthquake or station information and waveforms. It provides a user-friendly and modern graphical interface for semi-automatic and interactive strong motion data processing. SIGMA provides intensity and (P)SA maps based on GMPE's or recorded data. It calculates the most common strong motion parameters, e.g. PGA/PGV/PGD, Arias intensity and duration, Tp, Tm, CAV, SED and Fourier-, power- and response spectra. GMPE's are configurable. Supporting C++ and Python plug-ins, standard and customized GMPE's including the OpenQuake Hazard Library can be easily integrated and compared. Originally tailored to specifications by Geoscience Australia and BMKG (Indonesia) SIGMA has become a popular tool among SeisComP3 users concerned with seismic hazard and strong motion seismology.

  10. Plastic scintillation dosimetry: Optimal selection of scintillating fibers and scintillators

    International Nuclear Information System (INIS)

    Archambault, Louis; Arsenault, Jean; Gingras, Luc; Sam Beddar, A.; Roy, Rene; Beaulieu, Luc

    2005-01-01

    Scintillation dosimetry is a promising avenue for evaluating dose patterns delivered by intensity-modulated radiation therapy plans or for the small fields involved in stereotactic radiosurgery. However, the increase in signal has been the goal for many authors. In this paper, a comparison is made between plastic scintillating fibers and plastic scintillator. The collection of scintillation light was measured experimentally for four commercial models of scintillating fibers (BCF-12, BCF-60, SCSF-78, SCSF-3HF) and two models of plastic scintillators (BC-400, BC-408). The emission spectra of all six scintillators were obtained by using an optical spectrum analyzer and they were compared with theoretical behavior. For scintillation in the blue region, the signal intensity of a singly clad scintillating fiber (BCF-12) was 120% of that of the plastic scintillator (BC-400). For the multiclad fiber (SCSF-78), the signal reached 144% of that of the plastic scintillator. The intensity of the green scintillating fibers was lower than that of the plastic scintillator: 47% for the singly clad fiber (BCF-60) and 77% for the multiclad fiber (SCSF-3HF). The collected light was studied as a function of the scintillator length and radius for a cylindrical probe. We found that symmetric detectors with nearly the same spatial resolution in each direction (2 mm in diameter by 3 mm in length) could be made with a signal equivalent to those of the more commonly used asymmetric scintillators. With augmentation of the signal-to-noise ratio in consideration, this paper presents a series of comparisons that should provide insight into selection of a scintillator type and volume for development of a medical dosimeter

  11. Modification of Karasawa tropospheric scintillation model for Malaysia climate

    Science.gov (United States)

    Yee, C. C.; Mandeep, J. S.; Islam, M. T.

    2013-09-01

    Tropospheric scintillation is the rapid fluctuation and degradation of satellite signals due to changes in refractive index of atmosphere. This phenomenon tends to affect signals more strongly at frequencies above 10 GHz. This paper introduces a new scintillation prediction model created by modifying the existing Karasawa model. The proposed model is compared with currently existing model using scintillation data collected in Parit Buntar, Malaysia. The proposed model can simultaneously predict scintillation intensity of both fade and enhancement scintillation with an error rate below 5 %.

  12. Exploration of the potential of liquid scintillators for real-time 3D dosimetry of intensity modulated proton beams.

    Science.gov (United States)

    Beddar, Sam; Archambault, Louis; Sahoo, Narayan; Poenisch, Falk; Chen, George T; Gillin, Michael T; Mohan, Radhe

    2009-05-01

    In this study, the authors investigated the feasibility of using a 3D liquid scintillator (LS) detector system for the verification and characterization of proton beams in real time for intensity and energy-modulated proton therapy. A plastic tank filled with liquid scintillator was irradiated with pristine proton Bragg peaks. Scintillation light produced during the irradiation was measured with a CCD camera. Acquisition rates of 20 and 10 frames per second (fps) were used to image consecutive frame sequences. These measurements were then compared to ion chamber measurements and Monte Carlo simulations. The light distribution measured from the images acquired at rates of 20 and 10 fps have standard deviations of 1.1% and 0.7%, respectively, in the plateau region of the Bragg curve. Differences were seen between the raw LS signal and the ion chamber due to the quenching effects of the LS and due to the optical properties of the imaging system. The authors showed that this effect can be accounted for and corrected by Monte Carlo simulations. The liquid scintillator detector system has a good potential for performing fast proton beam verification and characterization.

  13. Performance of a Highly Granular Scintillator-SiPM Based Hadron Calorimeter Prototype in Strong Magnetic Fields

    OpenAIRE

    Graf, Christian; collaboration, for the CALICE

    2017-01-01

    Within the CALICE collaboration, several concepts for the hadronic calorimeter of a future linear collider detector are studied. After having demonstrated the capabilities of the measurement methods in "physics prototypes", the focus now lies on improving their implementation in "engineering prototypes", that are scalable to the full linear collider detector. The Analog Hadron Calorimeter (AHCAL) concept is a sampling calorimeter of tungsten or steel absorber plates and plastic scintillator t...

  14. Investigation on the influence of intensity scintillation and beam wander in space optical uplink DWDM communication system

    Science.gov (United States)

    Li, Mi; Chen, Mengji; Zhang, Xuping; Cong, Hengji; Song, Yuejiang; Lu, Yuangang

    2016-04-01

    Dense wavelength division multiplexing (DWDM) has been widely applied in ground optical communication. However, the technology of DWDM is still not mature enough in the space optical communication system. In order to further advance the use of DWDM into space optical communication, the probability density function (PDF) and the bit-error rate (BER) performance of DWDM is investigated in uplink communications under the influence of atmospheric turbulence, consisting of intensity scintillation and beam wander caused by atmospheric turbulence. Numerical results show that the atmospheric turbulence has a great impact on BER and PDF, and wavelength, divergence angel, and other relevant parameters should be carefully considered in this DWDM system. This work can be conducive for improving DWDM design of space optical uplink communication systems.

  15. Scintillating fibres

    International Nuclear Information System (INIS)

    Nahnhauer, R.

    1990-01-01

    In the search for new detector techniques, scintillating fibre technology has already gained a firm foothold, and is a strong contender for the extreme experimental conditions of tomorrow's machines. Organized by a group from the Institute of High Energy Physics, Berlin-Zeuthen, a workshop held from 3-5 September in the nearby village of Blossin brought together experts from East and West, and from science and industry

  16. Relaxation and interaction of electronic excitations induced by intense ultra short light pulses in BaF2 scintillator

    Science.gov (United States)

    Kirm, M.; Nagirnyi, V.; Vielhauer, S.; Feldbach, E.

    2011-06-01

    Excitation density effects have a pronounced influence on relaxation processes in solids. They come into play in scintillating and dosimetric materials exposed to ionizing radiation or in laser materials operating in intense ultraviolet light fields. The scientific understanding of the underlying process is poor, mainly because most of the studies of light emitting materials under short wavelength excitation have been performed at weak and moderate excitation intensities due to limited availability of powerful light sources. Disembodied data on excitation density effects have been reported for wide-gap dielectrics studied by luminescence spectroscopy, by using such excitation sources as powerful ion beams,1,2pulsed electron beams,2,3 and wide-band hard X-ray synchrotron radiation.4 It is obvious that such non-selective excitation is a good tool for revealing density-related phenomena in these materials in general, but for investigating specific features of relaxation processes in insulators, light sources with well defined parameters are necessary. Since the shortwavelength free electron laser (FEL) technology has been devised by an international consortium at HASYLAB of DESY, resulting in the development of TESLA Test facility (TTF)5 and later in the construction of a dedicated FEL source FLASH in Hamburg,6 more advanced studies became possible. The range of interests towards this light source covers the fields from material science and various other branches of physics to structural biology. The pioneering luminescence study revealed excitation density effects in the decay of Ce3+ 5d-4f luminescence in Y3Al5O12 crystals and luminescence of BaF2 crystals in UV-visible range.7 These results motivated systematic investigations of excitation density effects in wide gap crystals using FEL8,9 and high-harmonic-generated VUV radiation,10 and, at lower energies, femtosecond laser pulses in the UV.11,12 The main goal of the present work is to analyze the same phenomenon

  17. Efficient three-photon luminescence with strong polarization dependence from a scintillating silicate glass co-doped with Gd3+ and Tb3+.

    Science.gov (United States)

    Li, Guang-Can; Zhang, Cheng-Yun; Deng, Hai-Dong; Liu, Guang-Yin; Lan, Sheng; Qian, Qi-; Yang, Zhong-Min; Gopal, Achanta Venu

    2013-03-11

    Efficient three-photon luminescence (3PL) from a scintillating silicate glass co-doped with Gd(3+) and Tb(3+) was generated by using a focused femtosecond laser beam at 800 nm. Four emission bands centered at 496, 541, 583, and 620 nm were identified as the electronic transitions between the energy levels of Tb(3+) followed by three-photon absorption (3PA) in Gd(3+) and Tb(3+) and the resonant energy transfer from Gd(3+) to Tb(3+). More interestingly, a strong polarization dependence of the 3PL was observed and it is ascribed to the polarization dependent 3PA in Gd(3+) and Tb(3+) and/or the angular distribution of photogenerated electrons in the glass.

  18. Gas proportional scintillation counter

    International Nuclear Information System (INIS)

    Iguchi, Tetsuo; Nakazawa, Masaharu; Sekiguchi, Akira

    1980-01-01

    As the trial in the first stage of utilizing recoil helium for the measurement of 2 - 14 MeV neutron spectra in the simulated blanket for a nuclear fusion reactor, the He-Xe system gas proportional scintillation counter (GPSC) has been manufactured for trial, giving consideration to the advantages of gas scintillators and further to improve the energy resolution. In GPSC, delayed secondary scintillation pulses are produced, and its amplitude gives the energy resolution the adverse effect. Thus, in order to improve the energy resolution, it is desirable to realize such geometry of proportional counters that the electric field in the vicinity of center wire is sufficiently intense to induce the secondary excitation or ionization. The counters of such construction are called GPSC, in which the actual energy resolution can be improved according to the secondary scintillation pulses without losing the fast primary scintillation pulses useful for fast coincidence technique. The experimental results and the consideration on them are described. As compared with proportional counters, GPSC can give large output pulses even at low voltage, improve the energy resolution greatly as compared with ordinary gas scintillators, and measure the time data by the primary scintillation and the energy data based on the secondary scintillation simultaneously. However, it is likely to be affected by gas impurities more than proportional counters, and inferior in the reproducibility and stability of measurement. (Wakatsuki, Y.)

  19. Growth of L-band scintillation at anomaly crest station in association with strong TEC gradient: A study covering wide solar activity period

    Science.gov (United States)

    Pathak, K.; Devi, M.; Barbara, A. K.; Zahan, Y.

    2018-01-01

    The paper aims at to study the sources associated with growth of L band scintillation over Guwahati, an Appleton anomaly region. Starting with the analysis of diurnal and seasonal characteristic features of scintillation from a minimum sunspot number (Rz) of 10 to a maximum of 140, the paper shows that scintillations are more likely to develop during high solar activity period. It also highlights the explosive increase in occurrence of scintillation from post sunset to pre midnight hours in vernal equinoctial months when the background TEC is 50% more than on a normal day, accompanied by enhanced TEC decay rate. The role of equatorial anomaly effects through EXB drift processes are brought into discussion as possible sources on the growth of small scale irregularities leading to such scintillations.

  20. Cosmic-muon intensity measurement and overburden estimation in a building at surface level and in an underground facility using two BC408 scintillation detectors coincidence counting system.

    Science.gov (United States)

    Zhang, Weihua; Ungar, Kurt; Liu, Chuanlei; Mailhot, Maverick

    2016-10-01

    A series of measurements have been recently conducted to determine the cosmic-muon intensities and attenuation factors at various indoor and underground locations for a gamma spectrometer. For this purpose, a digital coincidence spectrometer was developed by using two BC408 plastic scintillation detectors and an XIA LLC Digital Gamma Finder (DGF)/Pixie-4 software and card package. The results indicate that the overburden in the building at surface level absorbs a large part of cosmic ray protons while attenuating the cosmic-muon intensity by 20-50%. The underground facility has the largest overburden of 39 m water equivalent, where the cosmic-muon intensity is reduced by a factor of 6. The study provides a cosmic-muon intensity measurement and overburden assessment, which are important parameters for analysing the background of an HPGe counting system, or for comparing the background of similar systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Intensity dependent waiting time for strong electron trapping events in speckle stimulated raman scatter

    Energy Technology Data Exchange (ETDEWEB)

    Rose, Harvey [Los Alamos National Laboratory; Daughton, W [Los Alamos National Laboratory; Yin, L [Los Alamos National Laboratory

    2009-01-01

    The onset of Stimulated Raman scatter from an intense laser speckle is the simplest experimentally realizable laser-plasma-interaction environment. Despite this data and recent 3D particle simulations, the controlling mechanism at the onset of backscatter in the kinetic regime when strong electron trapping in the daughter Langmuir wave is a dominant nonlinearity is not understood. This paper explores the consequences of assuming that onset is controlled by large thermal fluctuations. A super exponential dependence of mean reflectivity on speckle intensity in the onset regime is predicted.

  2. A series approximation model for optical light transport and output intensity field distribution in large aspect ratio cylindrical scintillation crystals

    Energy Technology Data Exchange (ETDEWEB)

    Tobias, Benjamin John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2018-01-09

    A series approximation has been derived for the transport of optical photons within a cylindrically symmetric light pipe and applied to the task of evaluating both the origin and angular distribution of light reaching the output plane. This analytic expression finds particular utility in first-pass photonic design applications since it may be evaluated at a very modest computational cost and is readily parameterized for relevant design constraints. It has been applied toward quantitative exploration of various scintillation crystal preparations and their impact on both quantum efficiency and noise, reproducing sensible dependencies and providing physical justification for certain gamma ray camera design choices.

  3. Scintillation Counters

    Science.gov (United States)

    Bell, Zane W.

    Scintillators find wide use in radiation detection as the detecting medium for gamma/X-rays, and charged and neutral particles. Since the first notice in 1895 by Roentgen of the production of light by X-rays on a barium platinocyanide screen, and Thomas Edison's work over the following 2 years resulting in the discovery of calcium tungstate as a superior fluoroscopy screen, much research and experimentation have been undertaken to discover and elucidate the properties of new scintillators. Scintillators with high density and high atomic number are prized for the detection of gamma rays above 1 MeV; lower atomic number, lower-density materials find use for detecting beta particles and heavy charged particles; hydrogenous scintillators find use in fast-neutron detection; and boron-, lithium-, and gadolinium-containing scintillators are used for slow-neutron detection. This chapter provides the practitioner with an overview of the general characteristics of scintillators, including the variation of probability of interaction with density and atomic number, the characteristics of the light pulse, a list and characteristics of commonly available scintillators and their approximate cost, and recommendations regarding the choice of material for a few specific applications. This chapter does not pretend to present an exhaustive list of scintillators and applications.

  4. Experimental observation of strong radiation reaction in the field of an ultra-intense laser

    Science.gov (United States)

    Sarri, G.; Poder, K.; Tamburini, M.; di Piazza, A.; Keitel, C. H.; Zepf, M.

    2017-10-01

    Describing radiation reaction in an electromagnetic field is one of the most fundamental outstanding problems in electrodynamics. It consists of determining the dynamics of a charged particle fully taking into account self-forces (loosely referred to as radiation reaction) resulting from the radiation fields generated by the particle whilst it is accelerated. Radiation reaction has only been invoked to explain the radiative properties of powerful astrophysical objects, such as pulsars and quasars. From a theoretical standpoint, this phenomenon is subject of fervent debate and this impasse is worsened by the lack of experimental data, due to extremely high fields required to trigger these effects. Here, we report on the first experimental evidence of strong radiation reaction during the interaction of an ultra-relativistic electron beam with an intense laser field, beyond a purely classical description.

  5. Experimental Study on Light Flash Radiant Intensity Generated by Strong Shock 2A12 Aluminum Plate

    Science.gov (United States)

    Tang, Enling; Zhang, Lijiao; Zhang, Qingming; Shi, Xiaohan; Wang, Meng; Wang, Di; Xiang, Shenghai; Xia, Jin; Han, Yafei; Xu, Mingyang; Wu, Jin; Zhang, Shuang; Yuan, Jianfei

    2015-07-01

    In order to study the light flash radiant intensity produced by strong shock on a 2A12 aluminum target at the same projectile incidence angles and different shock velocities, experimental measurements were conducted for light flash phenomena of a 2A12 aluminum projectile impacting a 2A12 aluminum target under the conditions of different impact velocity and the same projectile incidence angles of 45° by using an optical pyrometer measurement system and a two-stage light gas gun loading system. Experimental results show that the peak values of the light flash radiant intensity for the wavelength of 550 nm are largest in the wavelength ranges of 600 nm, 650 nm and 700 nm when a 2A12 aluminum projectile impacts a double-layer 2A12 aluminum plate in the present experimental conditions. supported by National Natural Science Foundation of China (Nos. 10972145, 11272218, 11472178), State Key Program of National Natural Science of China (No. 11032003), Program for Liaoning Excellent Talents in University, China (No. LR2013008)

  6. Tiny Stars, Strong Fields: Exploring the Origin of Intense Magnetism in M Stars

    Science.gov (United States)

    Toomre, Juri

    . We bring to this our prior experience with studying dynamo processes in the outer convective envelopes of G- (the Sun) and Ftype stars, briefly of M dwarfs, and in full convective cores within more massive A- and B-type stars. Our previous work suggests that M dwarfs could display a broad range of dynamo behavior, from cyclic reversals to more chaotic variations, and further to both weak and strong dynamo states. We will focus on the latter, exploring how superequipartition magnetic fields could be achieved by dynamo action in M dwarfs, as are likely needed to energize super-flares and huge active regions, and what limits the peak field strengths. M-type stars are distinctive in becoming fully convective with decreasing mass at about M3.5 in spectral type (or about 0.35 solar masses). At this transition, a steep rise in the fraction of magnetically active stars is observed that is accompanied by an increasing rotational velocity. Clearly how mass-loss and spin-down can lead to this is of interest in itself. However, here we propose to study the manner in which dynamos operating in fully convective M dwarf interiors beyond the transition may be able to achieve very strong magnetic fields, and how field strengths and apparent magnetic activity increases with rotation rate as suggested by observations. We believe that global connectivity of flows and fields across the core center will admit new classes of strong behavior, as revealed by our B star core dynamos, not realized when a convective envelope is bounded below by a tachocline. These ideas need to be tested in a self-consistent manner with global ASH simulations to gain theoretical insights into what is the origin of the fierce magnetic activity in some of M dwarfs that may be potential hosts to Earth-like planets. Such 3-D MHD simulations, though challenging, are now feasible and would complement the intensive observational searches under way.

  7. Uranium-scintillator device

    International Nuclear Information System (INIS)

    Smith, S.D.

    1979-01-01

    The calorimeter subgroup of the 1977 ISABELLE Summer Workshop strongly recommended investigation of the uranium-scintillator device because of its several attractive features: (1) increased resolution for hadronic energy, (2) fast time response, (3) high density (i.e., 16 cm of calorimeter per interaction length), and, in comparison with uranium--liquid argon detectors, (4) ease of construction, (5) simple electronics, and (6) lower cost. The AFM group at the CERN ISR became interested in such a calorimeter for substantially the same reasons, and in the fall of 1977 carried out tests on a uranium-scintillator (U-Sc) calorimeter with the same uranium plates used in their 1974 studies of the uranium--liquid argon (U-LA) calorimeter. The chief disadvantage of the scintillator test was that the uranium plates were too small to fully contain the hadronic showers. However, since the scintillator and liquid argon tests were made with the plates, direct comparison of the two types of devices could be made

  8. Computational strong-field quantum dynamics intense light-matter interactions

    CERN Document Server

    2017-01-01

    This graduate textbook introduces the computational techniques to study ultra-fast quantum dynamics of matter exposed to strong laser fields. Coverage includes methods to propagate wavefunctions according to the time-dependent Schrödinger, Klein-Gordon or Dirac equation, the calculation of typical observables, time-dependent density functional theory, multi-configurational time-dependent Hartree-Fock, time-dependent configuration interaction singles, the strong-field approximation, and the microscopic particle-in-cell approach.

  9. Computational strong-field quantum dynamics. Intense light-matter interactions

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Dieter (ed.) [Rostock Univ. (Germany). Inst. fuer Physik

    2017-09-01

    This graduate textbook introduces the computational techniques to study ultra-fast quantum dynamics of matter exposed to strong laser fields. Coverage includes methods to propagate wavefunctions according to the time dependent Schroedinger, Klein-Gordon or Dirac equation, the calculation of typical observables, time-dependent density functional theory, multi configurational time-dependent Hartree-Fock, time-dependent configuration interaction singles, the strong-field approximation, and the microscopic particle-in-cell approach.

  10. Embedding intensity image into a binary hologram with strong noise resistant capability

    Science.gov (United States)

    Zhuang, Zhaoyong; Jiao, Shuming; Zou, Wenbin; Li, Xia

    2017-11-01

    A digital hologram can be employed as a host image for image watermarking applications to protect information security. Past research demonstrates that a gray level intensity image can be embedded into a binary Fresnel hologram by error diffusion method or bit truncation coding method. However, the fidelity of the retrieved watermark image from binary hologram is generally not satisfactory, especially when the binary hologram is contaminated with noise. To address this problem, we propose a JPEG-BCH encoding method in this paper. First, we employ the JPEG standard to compress the intensity image into a binary bit stream. Next, we encode the binary bit stream with BCH code to obtain error correction capability. Finally, the JPEG-BCH code is embedded into the binary hologram. By this way, the intensity image can be retrieved with high fidelity by a BCH-JPEG decoder even if the binary hologram suffers from serious noise contamination. Numerical simulation results show that the image quality of retrieved intensity image with our proposed method is superior to the state-of-the-art work reported.

  11. Role of hot electron transport in scintillators: A theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Huihui [SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, Key Lab. of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen Univ. (China); Li, Qi [Physical Sciences Division, IBM TJ Watson Research Center, Yorktown Heights, NY (United States); Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, IL (United States); Lu, Xinfu; Williams, R.T. [Department of Physics, Wake Forest University, Winston Salem, NC (United States); Qian, Yiyang [College of Engineering and Applied Science, Nanjing University (China); Wu, Yuntao [Scintillation Materials Research Center, University of Tennessee, Knoxville, TN (United States)

    2016-10-15

    Despite recent intensive study on scintillators, several fundamental questions on scintillator properties are still unknown. In this work, we use ab-initio calculations to determine the energy dependent group velocity of the hot electrons from the electronic structures of several typical scintillators. Based on the calculated group velocities and optical phonon frequencies, a Monte-Carlo simulation of hot electron transport in scintillators is carried out to calculate the thermalization time and diffusion range in selected scintillators. Our simulations provide physical insights on a recent trend of improved proportionality and light yield from mixed halide scintillators. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Mounting LHCb hadron calorimeter scintillating tiles

    CERN Multimedia

    Maximilien Brice

    2004-01-01

    Scintillating tiles are carefully mounted in the hadronic calorimeter for the LHCb detector. These calorimeters measure the energy of particles that interact via the strong force, called hadrons. The detectors are made in a sandwich-like structure where these scintillator tiles are placed between metal sheets.

  13. Strong electromagnetic pulses generated in high-intensity laser-matter interactions

    Science.gov (United States)

    Rączka, P.; Dubois, J.-L.; Hulin, S.; Rosiński, M.; Zaraś-Szydłowska, A.; Badziak, J.

    2018-01-01

    Results are reported of an experiment performed at the Eclipse laser facility in CELIA, Bordeaux, on the generation of strong electromagnetic pulses. Measurements were performed of the target neutralization current, the total target charge and the tangential component of the magnetic field for the laser energies ranging from 45 mJ to 92 mJ with the pulse duration approximately 40 fs, and for the pulse durations ranging from 39 fs to 1000 fs, with the laser energy approximately 90 mJ. It was found that the values obtained for thick (mm scale) Cu targets are visibly higher than values reported in previous experiments, which is argued to be a manifestation of a strong dependence of the target electric polarization process on the laser contrast and hence on the amount of preplasma. It was also found that values obtained for thin (μm scale) Al foils were visibly higher than values for thick Cu targets, especially for pulse durations longer than 100 fs. The correlations between the total target charge versus the maximum value of the target neutralization current, and the maximum value of the tangential component of the magnetic field versus the total target charge were analysed. They were found to be in very good agreement with correlations seen in data from previous experiments, which provides a good consistency check on our experimental procedures.

  14. Results from a study of scintillation behavior at 12, 20, and 30 GHz using the results from the Virginia Tech Olympus receivers

    Science.gov (United States)

    Pratt, Timothy; Haidara, F.

    1993-01-01

    Tropospheric scintillations are rapid fluctuations of signal caused by multiple scattering from the small scale turbulent refractive index inhomogeneities in the troposphere. They can strongly impair satellite communications links operating at frequency above 10 GHz. The VA Tech OLYMPUS propagation experiment which includes 12, 20, and 30 GHz beacon receivers at an elevation angle of 14 degrees provides us with valuable multifrequency scintillation data. A long term analysis of tropospheric scintillation results from the VA Tech OLYMPUS experiment is presented. It includes statistics of both the scintillation intensity and the attenuation relative to clear air as well as seasonal, diurnal and meteorological trends. A comparison with the Consultative Committee for International Radio (CCIR) predictive model for scintillation fading is presented.

  15. Liquid scintillation solution

    International Nuclear Information System (INIS)

    Long, E.C.

    1977-01-01

    A liquid scintillation solution is described which includes (1) a scintillation solvent (toluene and xylene), (2) a primary scintillation solute (PPO and Butyl PBD), (3) a secondary scintillation solute (POPOP and Dimethyl POPOP), (4) a plurality of substantially different surfactants and (5) a filter dissolving and/or transparentizing agent. 8 claims

  16. Further evidence for the strong steepening of the median radio spectrum with decreasing intensity of sources selected at 5 GHz

    Science.gov (United States)

    Machalski, J.; Rys, S.

    1981-06-01

    Results are presented of a comparison of the spectral indices of radio sources selected at 5 GHz with their 5-GHz intensities which provides further evidence for the strong steepening of the radio spectrum with decreasing flux density. Distributions of spectral index between 5000 and 1400 MHz are compared for radio sources of 5-GHz intensity greater than or equal to 800 mJy of Witzel et al. (1979), sources selected from the S5 installment of the NRAO-Bonn survey with intensity between 250 and 800 mJy, and sources selected from the 4755-MHz survey of Ledden et al. (1980) with intensity between 40 and 250 mJy. As 5-GHz flux density decreases, it is observed that (1) the secondary peak of the spectral index distribution decreases; (2) the main peak of the distribution is shifted to steeper values; and (3) the dispersion systematically decreases. It is pointed out that further optical identifications of faint radio sources at 5 GHz are required to determine whether the observed steepening is due to a decline of quasars, or a variation in quasar spectral properties with increasing distance.

  17. Inorganic scintillating materials and scintillation detectors.

    Science.gov (United States)

    Yanagida, Takayuki

    2018-01-01

    Scintillation materials and detectors that are used in many applications, such as medical imaging, security, oil-logging, high energy physics and non-destructive inspection, are reviewed. The fundamental physics understood today is explained, and common scintillators and scintillation detectors are introduced. The properties explained here are light yield, energy non-proportionality, emission wavelength, energy resolution, decay time, effective atomic number and timing resolution. For further understanding, the emission mechanisms of scintillator materials are also introduced. Furthermore, unresolved problems in scintillation phenomenon are considered, and my recent interpretations are discussed. These topics include positive hysteresis, the co-doping of non-luminescent ions, the introduction of an aimed impurity phase, the excitation density effect and the complementary relationship between scintillators and storage phosphors.

  18. Molecular origins of scintillation in organic scintillators (Conference Presentation)

    Science.gov (United States)

    Feng, Patrick; Mengesha, Wondwosen; Myllenbeck, Nicholas

    2016-09-01

    Organic-based scintillators are indispensable materials for radiation detection owing to their high sensitivity to fast neutrons, low cost, and tailorable properties. There has been a recent resurgence of interest in organic scintillators due to exciting discoveries related to neutron discrimination and gamma-ray spectroscopy, which represent capabilities previously thought not possible in these materials. I will discuss our development of crystalline and polymer-based scintillators for these applications. Structure-property relationships related to intermolecular interactions and host-guest electronic exchange will be discussed in the context of energy-transfer pathways relevant to scintillation. An emphasis will be placed on the rational design of these materials, as guided by first principles and DFT calculations. Two related topics will be discussed: 1) Incorporation of organometallic triplet-harvesting additives to plastic scintillator matrices to confer a 'two-state' (singlet and triplet) luminescence signature to different types of ionizing radiation. This approach relies upon energetic and spatial overlap between the donor and acceptor excited states for efficient electronic exchange. Key considerations also include synthetic modification of the luminescence spectra and kinetics, as well as the addition of secondary additives to increase the recombination efficiency. 2) Design of organotin-containing plastic scintillators as a route towards gamma-ray spectroscopy. Organometallic compounds were selected on the basis of distance-dependent quenching relationships, phase compatibility with the polymer matrix, and the gamma-ray cross sections. This approach is guided by molecular modeling and radiation transport modeling to achieve the highest possible detection sensitivity luminescence intensity.

  19. Liquid scintillation solution

    International Nuclear Information System (INIS)

    Long, E.C.

    1976-01-01

    The invention deals with a liquid scintillation solution which contains 1) a scintillation solvent (toluol), 2) a primary scintillation solute (PPO), 3) a secondary scintillation solute (dimethyl POPOP), 4) several surfactants (iso-octyl-phenol polyethoxy-ethanol and sodium di-hexyl sulfosuccinate) essentially different from one another and 5) a filter resolution and/or transparent-making agent (cyclic ether, especially tetrahydrofuran). (HP) [de

  20. Scintillation response of organic and inorganic scintillators

    CERN Document Server

    Papadopoulos, L M

    1999-01-01

    A method to evaluate the scintillation response of organic and inorganic scintillators to different heavy ionizing particles is suggested. A function describing the rate of the energy consumed as fluorescence emission is derived, i.e., the differential response with respect to time. This function is then integrated for each ion and scintillator (anthracene, stilbene and CsI(Tl)) to determine scintillation response. The resulting scintillation responses are compared to the previously reported measured responses. Agreement to within 2.5% is observed when these data are normalized to each other. In addition, conclusions regarding the quenching parameter kB dependence on the type of the particle and the computed values of kB for certain ions are included. (author)

  1. Measurement of light emission in scintillation vials

    International Nuclear Information System (INIS)

    Duran Ramiro, M. Teresa; Garcia-Torano, Eduardo

    2005-01-01

    The efficiency and energy resolution of liquid scintillation counting (LSC) systems are strongly dependent on the optical characteristics of scintillators, vials, and reflectors. This article presents the results of measurements of the light-emission profile of scintillation vials. Two measurement techniques, autoradiographs and direct measurements with a photomultiplier tube, have been used to obtain light-emission distribution for standard vials of glass, etched glass and polyethylene. Results obtained with both techniques are in good agreement. For the first time, the effect of the meniscus in terms of light contribution has been numerically estimated. These results can help design LSC systems that are more efficient in terms of light collection

  2. About angular dependence of intensity of absent-minded radiation in approach of the strong dissipation of colliding ionic-sound waves

    International Nuclear Information System (INIS)

    Solikhov, D.K.

    2015-01-01

    Present article is devoted to angular dependence of intensity of absent-minded radiation in approach of the strong dissipation of colliding ionic-sound waves. The operation angular dependence of dimensionless of intensity of absent-minded radiation in two-dimensional field of localisation of a wave of a rating in approach of the strong dissipation of passers is ionic-sound waves is viewed. (author)

  3. Energy resolution of scintillation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Moszyński, M., E-mail: M.Moszynski@ncbj.gov.pl; Syntfeld-Każuch, A.; Swiderski, L.; Grodzicka, M.; Iwanowska, J.; Sibczyński, P.; Szczęśniak, T.

    2016-01-01

    According to current knowledge, the non-proportionality of the light yield of scintillators appears to be a fundamental limitation of energy resolution. A good energy resolution is of great importance for most applications of scintillation detectors. Thus, its limitations are discussed below; which arise from the non-proportional response of scintillators to gamma rays and electrons, being of crucial importance to the intrinsic energy resolution of crystals. The important influence of Landau fluctuations and the scattering of secondary electrons (δ-rays) on intrinsic resolution is pointed out here. The study on undoped NaI and CsI at liquid nitrogen temperature with a light readout by avalanche photodiodes strongly suggests that the non-proportionality of many crystals is not their intrinsic property and may be improved by selective co-doping. Finally, several observations that have been collected in the last 15 years on the influence of the slow components of light pulses on energy resolution suggest that more complex processes are taking place in the scintillators. This was observed with CsI(Tl), CsI(Na), ZnSe(Te), and undoped NaI at liquid nitrogen temperature and, finally, for NaI(Tl) at temperatures reduced below 0 °C. A common conclusion of these observations is that the highest energy resolution, and particularly intrinsic resolution measured with the scintillators, characterized by two or more components of the light pulse decay, is obtainable when the spectrometry equipment integrates the whole light of the components. In contrast, the slow components observed in many other crystals degrade the intrinsic resolution. In the limiting case, afterglow could also be considered as a very slow component that spoils the energy resolution. The aim of this work is to summarize all of the above observations by looking for their origin.

  4. Scintillator Design Via Codoping

    Science.gov (United States)

    Melcher, C. L.; Koschan, M.; Zhuravleva, M.; Wu, Y.; Rothfuss, H.; Meng, F.; Tyagi, M.; Donnald, S.; Yang, K.; Hayward, J. P.; Eriksson, L.

    Scintillation materials that lack intrinsic luminescence centers must be doped with optically active ions in order to provide luminescent centers that radiatively de-excite as the final step of the scintillation process. Codoping, on the other hand, can be defined as the incorporation of additional specific impurity species usually for the purpose of modifying the scintillation properties, mechanical properties, or the crystal growth behavior. In recent years codoping has become an increasingly popular approach for engineering scintillators with optimal performance for targeted applications. This report reviews several successful examples and its effect on specific properties.

  5. Mid-latitude ionospheric scintillation anomaly in the Far East

    Directory of Open Access Journals (Sweden)

    L. A. Hajkowicz

    2003-02-01

    Full Text Available A long-term (over 3 years study has been undertaken to obtain a comprehensive evaluation of VHF ionospheric scintillation morphology in East Asia (at Kokobunji in Japan, using amplitude records from Transit satellites. It is now evident that summer day and night scintillation enhancement in this mid-latitude region is a long-term evidence of a well-known Asian ionospheric disturbance anomaly. The scintillation activity is particularly strong during summer nights (21:00–24:00 LT and on occasion, all satellite passes recorded on consecutive days are associated with pronounced scintillation activity. A second sub-maximum is observed in the summer pre-noon period (09:00–12:00 LT. The scintillation regions extend latitudinally for a distance of 400–600 km in the F-region and 100–200 km in the E-region, mostly equatorwards of Kokobunji. For comparison similar scintillation data obtained for one year at the same longitudinal sector but in southern mid-latitudes (Brisbane in Australia were compared with the simultaneous northern scintillation data. The scintillation activity at Brisbane was much less pronounced in the southern summer but was of the same low level during other seasons as that for Kokobunji. This consistent scintillation anomaly, as yet, has not been included in the global scintillation models, which are essential for radio-satellite communications.Key words. Ionosphere (mid-latitude ionosphere; ionospheric irregularities

  6. Mid-latitude ionospheric scintillation anomaly in the Far East

    Directory of Open Access Journals (Sweden)

    L. A. Hajkowicz

    Full Text Available A long-term (over 3 years study has been undertaken to obtain a comprehensive evaluation of VHF ionospheric scintillation morphology in East Asia (at Kokobunji in Japan, using amplitude records from Transit satellites. It is now evident that summer day and night scintillation enhancement in this mid-latitude region is a long-term evidence of a well-known Asian ionospheric disturbance anomaly. The scintillation activity is particularly strong during summer nights (21:00–24:00 LT and on occasion, all satellite passes recorded on consecutive days are associated with pronounced scintillation activity. A second sub-maximum is observed in the summer pre-noon period (09:00–12:00 LT. The scintillation regions extend latitudinally for a distance of 400–600 km in the F-region and 100–200 km in the E-region, mostly equatorwards of Kokobunji. For comparison similar scintillation data obtained for one year at the same longitudinal sector but in southern mid-latitudes (Brisbane in Australia were compared with the simultaneous northern scintillation data. The scintillation activity at Brisbane was much less pronounced in the southern summer but was of the same low level during other seasons as that for Kokobunji. This consistent scintillation anomaly, as yet, has not been included in the global scintillation models, which are essential for radio-satellite communications.

    Key words. Ionosphere (mid-latitude ionosphere; ionospheric irregularities

  7. Influence of coma aberration on aperture averaged scintillations in oceanic turbulence

    Science.gov (United States)

    Luo, Yujuan; Ji, Xiaoling; Yu, Hong

    2018-01-01

    The influence of coma aberration on aperture averaged scintillations in oceanic turbulence is studied in detail by using the numerical simulation method. In general, in weak oceanic turbulence, the aperture averaged scintillation can be effectively suppressed by means of the coma aberration, and the aperture averaged scintillation decreases as the coma aberration coefficient increases. However, in moderate and strong oceanic turbulence the influence of coma aberration on aperture averaged scintillations can be ignored. In addition, the aperture averaged scintillation dominated by salinity-induced turbulence is larger than that dominated by temperature-induced turbulence. In particular, it is shown that for coma-aberrated Gaussian beams, the behavior of aperture averaged scintillation index is quite different from the behavior of point scintillation index, and the aperture averaged scintillation index is more suitable for characterizing scintillations in practice.

  8. Anticoincidence scintillation counter

    CERN Multimedia

    CERN PhotoLab

    1966-01-01

    This anticoincidence scintillation counter will be mounted in a hydrogen target vessel to be used in a measurement of the .beta. parameter in the .LAMBDA0. decay. The geometry of the counter optimizes light collection in the central part where a scintillation disk of variable thickness can be fitted.

  9. Plastic Organic Scintillator Chemistry

    Science.gov (United States)

    Brightwell, C. R.; Temanson, E. S.; Febbraro, M. T.

    2017-09-01

    Due to their high light output, quick decay time, affordability, durability and ability to be molded, plastic organic scintillators are increasingly becoming a more viable method of particle detection. Since the plastic is composed entirely of single molecular chains with repeating units, scintillating properties remain stable despite changes in experimental conditions. Different scintillating plastics can be modified and tailored to suit specific experiments depending on a variety of requirements such as light output, scintillating wavelength, and PMT compatibility. The synthesis chemistry of a recent but well-known scintillating polyester, polyethylene naphthalate (PEN) will be presented to demonstrate how plastic organic scintillators can be modified for different particle detection experiments. PEN has been successfully synthesized at ORNL, and procedures are currently being investigated to modify PEN using different reactants and catalysts. The goal is to achieve a transparent scintillating plastic with an incorporated wavelength shifter in the chain that scintillates with a wavelength around 440 nm. The status of this project will be presented. This research is supported by the U. S. Department of Energy Office of Science.

  10. Ionospheric scintillation observations

    International Nuclear Information System (INIS)

    Kakane, V.C.K.

    1982-12-01

    Ionospheric scintillation observations made at Legon, Ghana (5.63 deg. N, 0.19 deg. E, dip angle 8.50) during the year 1979 are reported for two geostationary satellites, Marisat and Sirio, transmitting at 257 MHz and 136 MHz, respectively. The night-time scintillation showed a single peak around 2200-3000 hours local time (GMT). Seasonally, Marisat showed a fast decay of scintillation for the months April-June and June-September from around midnight whilst it persisted for the other months January-March and October-December. (author)

  11. Polarized scintillator targets

    Science.gov (United States)

    van den Brandt, B.; Bunyatova, E. I.; Hautle, P.; Konter, J. A.; Mango, S.

    2000-05-01

    The hydrogen nuclei in an organic scintillator have been polarized to more than 80% and the deuterons in its fully deuterated version to 24%. The scintillator, doped with TEMPO, has been polarized dynamically in a field of 2.5 T in a vertical dilution refrigerator in which a plastic lightguide transports the scintillation light from the sample in the mixing chamber to a photomultiplier outside the cryostat. Sizeable solid samples with acceptable optical properties and light output have been prepared and successfully operated as "live" polarized targets in nuclear physics experiments.

  12. Polarized scintillator targets

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, B. van den E-mail: vandenbrandt@psi.ch; Bunyatova, E.I.; Hautle, P.; Konter, J.A.; Mango, S

    2000-05-21

    The hydrogen nuclei in an organic scintillator have been polarized to more than 80% and the deuterons in its fully deuterated version to 24%. The scintillator, doped with TEMPO, has been polarized dynamically in a field of 2.5 T in a vertical dilution refrigerator in which a plastic lightguide transports the scintillation light from the sample in the mixing chamber to a photomultiplier outside the cryostat. Sizeable solid samples with acceptable optical properties and light output have been prepared and successfully operated as 'live' polarized targets in nuclear physics experiments.

  13. Development of ZnO:Ga as an Ultrafast Scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Bourret-Courchesne, E.D.; Derenzo, S.E.; Weber, M.J.

    2008-12-10

    We report on several methods for synthesizing the ultra-fast scintillator ZnO(Ga), and measurements of the resulting products. This material has characteristics that make it an excellent alpha detector for tagging the time and direction of individual neutrons produced by t-d and d-d neutron generators (associated particle imaging). The intensity and decay time are strongly dependent on the method used for dopant incorporation. We compare samples made by diffusion of Ga metal to samples made by solid state reaction between ZnO and Ga2O3 followed by reduction in hydrogen. The latter is much more successful and has a pure, strong near-band-edge fluorescence and an ultra-fast decay time of the x-ray-excited luminescence. The luminescence increases dramatically as the temperature is reduced to 10K. We also present results of an alternate low-temperature synthesis that produces luminescent particles with a more uniform size distribution. We examine possible mechanisms for the bright near-band-edge scintillation and favor the explanation that it is due to the recombination of Ga3+ donor electrons with ionization holes trapped on H+ ion acceptors.

  14. Scintillation γ spectrography. Physical principles. Apparatus. Operation

    International Nuclear Information System (INIS)

    Julliot, C.

    1960-01-01

    The scintillation detector forms the main part of the instrument used, the electronic unit presenting the results produced. After a brief description of the process of γ photon absorption in the material, the particular case of NaI (T1), the scintillator used, is examined. The intensity of the scintillation caused by γ ray absorption and the characteristics of the photomultiplier play a determining part in the energy resolution of the instrument. For the γ recording spectrograph, we show to what extent the technique for using the electronic unit can modify the results. A detailed description is given of the activity measurement of a γ-emitting radioelement by the spectrographic method. (author) [fr

  15. Improved light yield of lead tungstate scintillators

    CERN Document Server

    Annenkov, A N; Hofstäetter, A; Korzhik, M V; Ligun, V; Lecoq, P; Missevitch, O V; Novotny, R; Peigneux, J P

    2000-01-01

    The application at medium and low energies of lead tungstate scintillators, so far optimized for the ECAL calorimeter of CMS for the future LHC, is strongly limited by their poor light yield. Suitable dopants like molybdenum and terbium can help to overcome this problem. Concepts, results, advantages and drawbacks of this approach are discussed. (11 refs).

  16. Phosphor scintillator structure

    International Nuclear Information System (INIS)

    Cusano, D.A.; Prener, J.S.

    1980-01-01

    A method of fabricating scintillators is described in which the phosphor is distributed within the structure in such a way as to enhance the escape of the visible wavelength radiation that would otherwise be dissipated within the scintillator body. Two embodiments of the present invention are disclosed: one in which the phosphor is distributed in a layered structure and another in which the phosphor is dispersed throughout a transparent matrix. (U.K.)

  17. New heavy plastic scintillators

    International Nuclear Information System (INIS)

    Britvich, G.I.; Vasil'chenko, V.G.; Lapshin, V.G.; Solov'ev, A.S.

    2000-01-01

    The possibility of manufacturing through the quenching method new transparent heavy scintillators on the basis of polystyrene with the light yield of approximately 32% from anthracene by general concentration of metalloorganic additions of approximately 17% by weight is shown. Doping of plastic scintillators through a set of various metalloorganic additives makes it possible to achieve more efficient and homogeneous by energy absorption of soft γ-quanta therein [ru

  18. Comparative photoluminescence study of crystalline and nanostructured scintillators

    Science.gov (United States)

    McKinney, George; McDonald, Warren; Tzolov, Marian

    2014-03-01

    Scintillators are widely used for conversion of high energy radiation/particles to visible light which can be either directly observed or further converted to electrical signal in photomultipliers or solid state detectors. We compare the light emission properties of traditional crystalline scintillators with nanostructured films created in our laboratory with the potential for use as scintillators. We have studied zinc oxide (ZnO) nanowires, zinc tungstate (ZnWO4) thin films, commercially available crystals of ZnO, ZnWO4 and commercial scintillators of yttrium aluminum garnet (YAG) and yttrium aluminum perovskite (YAP). We will present the photoluminescence emission spectra, the intensity dependence of the emission, and the photoluminescence excitation spectra. We have found that the emission spectrum of zinc oxide nanowires becomes very intense at high excitation intensities and becomes comparable with the emission from the commercial scintillators. The excitation spectra indicate the presence of subgap electronic states in the nanostructured samples and in the commercial scintillators. This study contributes to our effort of creating electron detectors for scanning electron microscopy using nanostructured scintillators.

  19. Scintillation effects on radio wave propagation through solar corona

    Science.gov (United States)

    Ho, C. M.; Sue, M. K.; Bedrossian, A.; Sniffin, R. W.

    2002-01-01

    When RF waves pass through the solar corona and solar wind regions close to the Sun, strong scintillation effects appear at their amplitude, frequency and phase, especially in the regions very close to the Sun (less than 4 solar radius).

  20. Fast-scintillator measurements

    International Nuclear Information System (INIS)

    Graves, W.R.; Slaughter, D.R.; Lerche, R.A.

    1985-01-01

    The authors are investigating scintillators because their fast timing properties may be applied to the development of neutron diagnostics. Measuring the history of a target burn by direct observation of DT neutrons requires a time resolution of 20 ps. An instrument designed to measure the plasma ion temperature by neutron time of flight, when the flight path is less than or equal to 1m, requires a detector system with resolution of 60 to 100 ps. Fast plastic scintillators like NE111, BC-422, and SG180 typically have decay constants of about 1400 ps. With quenching, the decay constant can be decreased to about 700 ps - still to slow for the instruments that they would like to build. One yet-unexploited property of fast scintillators is their rise time. In 1984, they began experiments designed to measure scintillator rise times. For our application - the measurement of target burn histories - they are especially concerned with the temporal width of the sample excitation pulse, the temporal resolution of our measurement system, and the need to characterize the excitation pulse and the scintillator output simultaneously. Application of plastic scintillators to a neutron streak camera is described

  1. Role of the magnetospheric and ionospheric currents in the generation of the equatorial scintillations during geomagnetic storms

    Directory of Open Access Journals (Sweden)

    L. Z. Biktash

    2004-09-01

    Full Text Available The equatorial ionosphere parameters, Kp, Dst, AU and AL indices characterized contribution of different magnetospheric and ionospheric currents to the H-component of geomagnetic field are examined to test the geomagnetic activity effect on the generation of ionospheric irregularities producing VLF scintillations. According to the results of the current statistical studies, one can predict near 70% of scintillations from Aarons' criteria using the Dst index, which mainly depicts the magnetospheric ring current field. To amplify Aarons' criteria or to propose new criteria for predicting scintillation characteristics is the question. In the present phase of the experimental investigations of electron density irregularities in the ionosphere new ways are opened up because observations in the interaction between the solar wind - magnetosphere - ionosphere during magnetic storms have progressed greatly. According to present view, the intensity of the electric fields and currents at the polar regions, as well as the magnetospheric ring current intensity, are strongly dependent on the variations of the interplanetary magnetic field. The magnetospheric ring current cannot directly penetrate the equatorial ionosphere and because of this difficulties emerge in explaining its relation to scintillation activity. On the other hand, the equatorial scintillations can be observed in the absence of the magnetospheric ring current. It is shown that in addition to Aarons' criteria for the prediction of the ionospheric scintillations, models can be used to explain the relationship between the equatorial ionospheric parameters, h'F, foF2, and the equatorial geomagnetic variations with the polar ionosphere currents and the solar wind.

  2. A Minor Modification of Leading Edge Discriminator Circuitry with a Delay Line for Baseline Restoration of Scintillation Detectors

    International Nuclear Information System (INIS)

    Izumi, N

    2003-01-01

    Multi-channel neutron time-of-flight detector arrays LaNSA, T-ion, Medusa, and Mandala, have been used for neutron spectroscopy in inertial confinement fusion experiments. These multi-channel neutron detector arrays consist of many identical scintillation detectors (842 ∼ 1024 channel), data acquisition electronics (discriminators, time-to digital converters, and controller). Each detector element is operated in neutron counting mode. Time-of-flight of individual detected neutrons are recorded by time to digital converters. The energy of each detected neutrons is determined from its time-of-flight. The accurate time measurement (Δt ∼ 0.5 ns) and straightforward statistical features of the data obtained with these systems provides good integrity and reliability. The elements detector used in these systems are organic scintillators coupled with photo multiplier tubes. A scintillation detector operated in particle-counting mode requires finite recovery time after each detection event. The recovery time is determined by the time responses of scintillators, photo multiplier tubes, and the dead times of following discriminators and time-to digital converters. The harsh gamma ray background environment of fast ignitor experiments requires detectors that have fast recovery times. In high intensity laser experiments (I > 10 19 W/cm 2 ), strong gamma ray bursts are produced by relativistic laser plasma interactions. Prior to the neutron signal, these strong gamma ray bursts hit the detectors and interfere with the detection of following neutron signals. In these situations, the recovery time of the system after preceding gamma ray bursts is determined mainly by the base line shift of the PMT signal (due to slower decay components of scintillators ''after glow''). Discriminators cannot detect following signal pulses until the proceeding burst decays below its threshold voltage. The base line shift caused by the after glow prolongs the recovery time of the discriminators

  3. Scintillating properties of frozen new liquid scintillators

    CERN Document Server

    Britvich, G I; Golovkin, S V; Martellotti, G; Medvedkov, A M; Penso, G; Soloviev, A S; Vasilchenko, V G

    1999-01-01

    The light emission from scintillators which are liquid at room temperature was studied in the interval between $+20$~$^{\\circ}$C and $-120$~$^{\\circ}$C, where the phase transition from liquid to solid takes place. The light yield measured at $-120$~$^{\\circ}$C is about twice as much as that observed at $+20$~$^{\\circ}$C. By cooling the scintillator from $+20$~$^{\\circ}$C to $-120$~$^{\\circ}$C and then heating it from $-120$~$^{\\circ}$C to $+20$~$^{\\circ}$C, the light yield varies in steps at well defined temperatures, which are different for the cooling and heating processes. These hysteresis phenomena appear to be related to the solvent rather than to the dopant. The decay time of scintillation light was measured at $+20$~$^{\\circ}$C and $-120$~$^{\\circ}$C. Whilst at room temperature most of the light is emitted with a decay time of 6--8 ns, at $-120$~$^{\\circ}$C a slower component, with a decay time of 25--35 ns, becomes important.

  4. Wavefront sensing and adaptive optics in strong turbulence

    Science.gov (United States)

    Mackey, Ruth; Dainty, Christopher

    2005-06-01

    When light propagates through the atmosphere the fluctuating refractive index caused by temperature gradients, humidity fluctuations and the wind mixing of air cause the phase of the optical field to be corrupted. In strong turbulence, over horizontal paths or at large zenith angles, the phase aberration is converted to intensity variation (scintillation) as interference within the beam and diffraction effects produce the peaks and zeros of a speckle-like pattern. At the zeros of intensity the phase becomes indeterminate as both the real and imaginary parts of the field go to zero. The wavefront is no longer continuous but contains dislocations along lines connecting phase singularities of opposite rotation. Conventional adaptive optics techniques of wavefront sensing and wavefront reconstruction do not account for discontinuous phase functions and hence can only conjugate an averaged, continuous wavefront. We are developing an adaptive optics system that can cope with dislocations in the phase function for potential use in a line-of-sight optical communications link. Using a ferroelectric liquid crystal spatial light modulator (FLC SLM) to generate dynamic atmospheric phase screens in the laboratory, we simulate strong scintillation conditions where high densities of phase singularities exist in order to compare wavefront sensors for tolerance to scintillation and accuracy of wavefront recovery.

  5. Non-Proportionality of Organic Scintillators and BGO

    Science.gov (United States)

    Nassalski, A.; Moszy¿ski, M.; Syntfeld-Ka¿uch, A.; ¿widerski, ¿.; Szcze¿¿niak, T.

    2008-06-01

    According to the present knowledge the non-proportionality of the light yield of scintillators appears to be the fundamental limitation of energy resolution. Thus, the understanding of its origin is of the great importance for a development of new scintillators with enhanced energy resolution. In this respect, the non-proportional response of the typical organic scintillators was studied in comparison to that of a BGO crystal. The studies covered tests of BC408 plastic, BC501A liquid scintillator and anthracene organic crystal. The measurements showed a much larger range of energies presenting non-proportional response compared to that known for inorganic scintillators. In the case of anthracene the non-proportionality covers energy range up to about 500 keV, while for the BC408 plastic and BC501A liquid scintillators, it is above 4 MeV energy lost by gamma quanta. The observed effect can be related to a strong quenching of the light for charged particles in organic scintillators, which is much larger than that observed in inorganic scintillators.

  6. A study of GPS ionospheric scintillations observed at Guilin

    Science.gov (United States)

    Zou, Yuhua; Wang, Dongli

    2009-12-01

    The occurrence of strong ionospheric scintillations with S4>=0.2 was studied using global positioning system (GPS) measurements at Guilin (25.29°N, 110.33°E; geomagnetic: 15.04°N, 181.98°E), a station located near the northern crest of equatorial anomaly in China. The results are presented for data collected from January 2007 to December 2008. The results show that amplitude scintillations occurred only during the first five months of the considered years. Nighttime amplitude scintillations, observed mainly in the south of Guilin, always occurred with phase scintillations, total electron content (TEC) depletions, and Rate Of change of TEC (ROT) fluctuations. However, TEC depletions and ROT fluctuations were weak during daytime amplitude scintillations, and daytime amplitude scintillations usually occurred in most of the azimuth directions. GPS scintillation/TEC observations recorded at Guilin and signal-to-noise-ratio measurements obtained from GPS-COSMIC radio occultation indicate that nighttime and daytime scintillations are very likely caused by ionospheric F region irregularities and sporadic E, respectively.

  7. Inorganic liquid scintillator

    International Nuclear Information System (INIS)

    Pavlicek, Z.; Barta, C.; Jursova, L.

    1986-01-01

    An inorganic liquid scintillator is designed which contains 1 to 30 wt.% of an inorganic molecular compound as the basic active component; the compound contains a cation with an atomic number higher than 47 and a halogen anion. The basic inorganic component is dissolved in water or in an organic solvent in form of non-dissociated molecules or self-complexes in which the bond is preserved between the cation and anion components. The light yield from these scintillators ranges between 70 and 150% of the light yield of a standard organic scintillator based on toluene. They are advantageous in that that they allow to increase the water content in the sample to up to 100%. (M.D.)

  8. Response of ultrafast scintillators

    International Nuclear Information System (INIS)

    Cheng, J.C.; Lerche, R.A.; Tirsell, K.G.; Tripp, G.R.

    1976-01-01

    Measurements of the properties of subnanosecond, quenched NE111 plastic scintillators with various concentrations of acetophenone and benzophenone are presented. These quenching agents have been found to very significantly decrease the NE111 decay time. Measurements are made using UV and laser produced x-ray radiations. The scintillations are detected using a visible streak camera with 10 ps resolution. The paper will include measurements of: (1) 10-90 percent rise time, (2) FWHM, (3) decay time, (4) relative scintillator efficiencies, (5) amplitudes vs. time measurements of the long decay component. All temporal measurements are obtained from a gold cathode ultrafast x-ray streak camera, and the detailed x-ray energy spectrum above 1 keV is also measured using an array of x-ray PIN diodes equipped with the appropriate K-edge filters. Details of the experimental measurements are discussed and anticipated applications are included

  9. Response of ultrafast scintillators

    International Nuclear Information System (INIS)

    Cheng, J.C.; Lerche, R.A.; Tripp, G.R.; Coleman, L.W.

    1976-09-01

    Measurements of the properties of subnanosecond, quenched NE111 plastic scintillators with various concentrations of acetophenone and benzophenone are presented. These quenching agents have been found to very significantly decrease the NE111 decay time. Measurements are made using UV and laser produced x-ray radiations. The scintillations are detected using a visible streak camera with 10 ps resolution. Measurements of: (1) 10-90 percent rise time, (2) FWHM, (3) decay time, (4) relative scintillator efficiencies, and (5) amplitudes vs. time measurements of the long decay component are presented. All temporal measurements are obtained from a gold cathode ultrafast x-ray streak camera, and the detailed x-ray energy spectrum above 1 keV is also measured using an array of x-ray PIN diodes equipped with the appropriate K-edge filters. Details of the experimental measurements are discussed and anticipated applications are included

  10. Microfluidic Scintillation Detectors

    CERN Multimedia

    Microfluidic scintillation detectors are devices of recent introduction for the detection of high energy particles, developed within the EP-DT group at CERN. Most of the interest for such technology comes from the use of liquid scintillators, which entails the possibility of changing the active material in the detector, leading to an increased radiation resistance. This feature, together with the high spatial resolution and low thickness deriving from the microfabrication techniques used to manufacture such devices, is desirable not only in instrumentation for high energy physics experiments but also in medical detectors such as beam monitors for hadron therapy.

  11. Polarized Scintillating Targets at Psi

    Science.gov (United States)

    van den Brandt, B.; Bunyatova, E. I.; Hautle, P.; Konter, J. A.; Mango, S.

    2001-02-01

    Scintillating polarized targets are now routinely available: blocks of 18×18×5 mm scintillating organic polymer, doped with TEMPO, polarized dynamically in a field of 2.5 T in a vertical 3He-4He dilution refrigerator. A 19 mm diameter plastic lightguide transports the scintillation light from the sample in the mixing chamber to a photomultiplier outside the cryostat.

  12. Liquid scintillation, counting, and compositions

    International Nuclear Information System (INIS)

    Sena, E.A.; Tolbert, B.M.; Sutula, C.L.

    1975-01-01

    The emissions of radioactive isotopes in both aqueous and organic samples can be measured by liquid scintillation counting in micellar systems. The micellar systems are made up of scintillation solvent, scintillation solute and a mixture of surfactants, preferably at least one of which is relatively oil-soluble water-insoluble and another which is relatively water-soluble oil-insoluble

  13. Scintillation properties of acrylate based plastic scintillator by photoploymerization method

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Hwan [Dept. of Radiological Science, Cheongju University, Cheongju (Korea, Republic of); Lee, Joo Il [Dept. of of Radiology, Daegu Health College, Daegu (Korea, Republic of)

    2016-12-15

    In this study, we prepared and characterized a acrylate based UV-curable plastic scintillator. It was used co-polymers TMPTA, DHPA and Ultima GoldTM LLT organic scintillator. The emission spectrum of the plastic scintillator was located in the range of 380⁓520 nm, peaking at 423 nm. And the scintillator is more than 50% transparent in the range of 400⁓ 800 nm. The emission spectrum is well match to the quantum efficiency of photo-multiplier tube and the fast decay time of the scintillation is 12 ns, approximately. This scintillation material provides the possibility of combining 3D printing technology, and then the applications of the plastic scintillator may be expected in human dosimetry etc.

  14. Seismic Intensity Map Triggered by Observed Strong Motion Records Considering Site Amplification and its service based on Geo-spatial International Standard

    International Nuclear Information System (INIS)

    Matsuoka, Masashi

    2014-01-01

    Instrumental seismic intensity measurement is carried out at approximately 4,200 points in Japan, but the correct values at points without seismometers cannot always be provided because seismic motion depends on geologic and geomorphologic features. Quick provision of accurate information on seismic intensity distribution over wide areas is required for disaster mitigation. To estimate seismic intensity at specific points, it is important to prepare ground amplification characteristics for local areas beforehand and use an interpolation algorithm. The QuiQuake system (quick estimation system for earthquake maps triggered by using observation records from K-NET and KiK-net that have been released by the National Research Institute for Earth Science and Disaster Prevention), which uses these, was developed; it can be started up automatically using seismograms and can immediately display a seismic intensity distribution map. The calculation results are sent to IAEA and JNES in the form of strong motion evaluation maps with a mesh size of 250 x 250 m. These maps are also sent to the general public via social networking web sites. (author)

  15. Suppression of parasitic noise by strong Langmuir wave damping in quasitransient regimes of backward Raman amplification of intense laser pulses in plasmas.

    Science.gov (United States)

    Malkin, Vladimir; Fisch, Nathaniel

    2009-11-01

    Currently built powerful soft x-ray sources may be able to access intensities needed for backward Raman amplification (BRA) of x-ray pulses in plasmas. However, high plasma densities, needed to provide enough coupling between the pump and seed x-ray pulsed, cause strong damping of the Langmuir wave that mediates energy transfer from the pump to the seed pulse. Such damping could reduce the coupling, thus making efficient BRA impossible. This work shows that efficient BRA can survive despite the Langmuir wave damping significantly exceeding the linear BRA growth rate. Moreover, the strong Langmuir wave damping can suppress deleterious instabilities of BRA seeded by the thermal noise. This shows that it may be feasible to observe x-ray BRA for the first time soon.

  16. GPS TEC, scintillation and cycle slips observed at high latitudes during solar minimum

    Directory of Open Access Journals (Sweden)

    P. Prikryl

    2010-06-01

    Full Text Available High-latitude irregularities can impair the operation of GPS-based devices by causing fluctuations of GPS signal amplitude and phase, also known as scintillation. Severe scintillation events lead to losses of phase lock, which result in cycle slips. We have used data from the Canadian High Arctic Ionospheric Network (CHAIN to measure amplitude and phase scintillation from L1 GPS signals and total electron content (TEC from L1 and L2 GPS signals to study the relative role that various high-latitude irregularity generation mechanisms have in producing scintillation. In the first year of operation during the current solar minimum the amplitude scintillation has remained very low but events of strong phase scintillation have been observed. We have found, as expected, that auroral arc and substorm intensifications as well as cusp region dynamics are strong sources of phase scintillation and potential cycle slips. In addition, we have found clear seasonal and universal time dependencies of TEC and phase scintillation over the polar cap region. A comparison with radio instruments from the Canadian GeoSpace Monitoring (CGSM network strongly suggests that the polar cap scintillation and TEC variations are associated with polar cap patches which we therefore infer to be main contributors to scintillation-causing irregularities in the polar cap.

  17. Performance of molded plastic scintillators

    International Nuclear Information System (INIS)

    Gen, N.S.; Leman, V.E.; Solomonov, V.M.

    1989-01-01

    The performance of molded plastic scintillators is studied. The plastic scintillators studied were formed by transfer molding and intrusion from a scintillation composition consisting of polystyrene and a standard system of luminescent additives: 2 mass % of paraterphenyl + 0.06 mass % 1,4-di-/2-[5-phenyloxazoyly]/benzene and a plasticizer. The combined effect of mechanical load and temperature was studied. The effect of radiation on molded plastic scintillators was studied using gamma radiation from a 60 Co source. The studies show that the main operating characteristics of molded plastic scintillators are on a par with those of polymerized plastic scintillators. At the same time, molded plastic scintillators are superior in thermal stability at temperatures below the glass transition temperature and with respect to their working temperature range

  18. SPORT: A new sub-nanosecond time-resolved instrument to study swift heavy ion-beam induced luminescence - Application to luminescence degradation of a fast plastic scintillator

    Science.gov (United States)

    Gardés, E.; Balanzat, E.; Ban-d'Etat, B.; Cassimi, A.; Durantel, F.; Grygiel, C.; Madi, T.; Monnet, I.; Ramillon, J.-M.; Ropars, F.; Lebius, H.

    2013-02-01

    We developed a new sub-nanosecond time-resolved instrument to study the dynamics of UV-visible luminescence under high stopping power heavy ion irradiation. We applied our instrument, called SPORT, on a fast plastic scintillator (BC-400) irradiated with 27-MeV Ar ions having high mean electronic stopping power of 2.6 MeV/μm. As a consequence of increasing permanent radiation damages with increasing ion fluence, our investigations reveal a degradation of scintillation intensity together with, thanks to the time-resolved measurement, a decrease in the decay constant of the scintillator. This combination indicates that luminescence degradation processes by both dynamic and static quenching, the latter mechanism being predominant. Under such high density excitation, the scintillation deterioration of BC-400 is significantly enhanced compared to that observed in previous investigations, mainly performed using light ions. The observed non-linear behaviour implies that the dose at which luminescence starts deteriorating is not independent on particles' stopping power, thus illustrating that the radiation hardness of plastic scintillators can be strongly weakened under high excitation density in heavy ion environments.

  19. The creation of strongly coupled plasmas using an intense heavy ion beam: low-entropy compression of hydrogen and the problem of hydrogen metallization

    CERN Document Server

    Tahir, N A; Shutov, A; Varentsov, D; Udrea, S; Hoffmann, Dieter H H; Juranek, H; Redmer, R; Portugues, R F; Lomonosov, I V; Fortov, V E

    2003-01-01

    Intense heavy ion beams deposit energy very efficiently over extended volumes of solid density targets, thereby creating large samples of strongly coupled plasmas. Intense beams of energetic heavy ions are therefore an ideal tool to research this interesting field. It is also possible to design experiments using special beam-target geometries to achieve low-entropy compression of samples of matter. This type of experiments is of particular interest for studying the problem of hydrogen metallization. In this paper we present a design study of such a proposed experiment that will be carried out at the future heavy ion synchrotron facility SIS100, at the Gesellschaft fuer Schwerionenforschung, Darmstadt. This study has been done using a two-dimensional hydrodynamic computer code. The target consists of a solid hydrogen cylinder that is enclosed in a thick shell of lead whose one face is irradiated with an ion beam which has an annular (ring shaped) focal spot. The beam intensity and other parameters are consider...

  20. Attenuation of GPS scintillation in Brazil due to magnetic storms

    Science.gov (United States)

    Bonelli, E.

    2008-09-01

    Amplitude scintillations in satellite signals can cause errors in communications, because of signal fading, but can be very useful for scientists trying to improve their understanding of the physics of the ionosphere. Usually, magnetic storms are expected to affect the ionosphere in such way as to increase ionospheric irregularities responsible for scintillations. To help change the view of scientists and engineers, in this respect, we show that amplitude scintillation on GPS signals show dramatic decrease during selected magnetic storms, at Brazilian GPS stations. These stations are located on magnetic latitudes that go from equatorial (São Luís) to low-latitude (São José dos Campos and Cachoeira Paulista) so that a region of several thousand kilometers is represented by the data. We present 4 months of data chosen from 2003 to 2005 to represent the strongest storms during each scintillation season. Although there is lack of data for some days from the different stations, it is possible to see, especially for the Halloween Storm (October 2003), that scintillations are attenuated in this wide range of latitudes. During magnetically calm periods scintillations are strong, in this region, from August to March, during solar maxima. Although the data are clear about the attenuation of scintillations during greater magnetic storms, it is not possible to easily conclude which physical mechanism was responsible for this phenomenon, even with the aid of more detailed data like Dst and AE.

  1. Cerium doped lanthanum halides: fast scintillators for medical imaging

    International Nuclear Information System (INIS)

    Selles, O.

    2006-12-01

    This work is dedicated to two recently discovered scintillating crystals: cerium doped lanthanum halides (LaCl 3 :Ce 3+ and LaBr 3 :Ce 3+ ).These scintillators exhibit interesting properties for gamma detection, more particularly in the field of medical imaging: a short decay time, a high light yield and an excellent energy resolution. The strong hygroscopicity of these materials requires adapting the usual experimental methods for determining physico-chemical properties. Once determined, these can be used for the development of the industrial manufacturing process of the crystals. A proper comprehension of the scintillation mechanism and of the effect of defects within the material lead to new possible ways for optimizing the scintillator performance. Therefore, different techniques are used (EPR, radioluminescence, laser excitation, thermally stimulated luminescence). Alongside Ce 3+ ions, self-trapped excitons are involved in the scintillation mechanism. Their nature and their role are detailed. The knowledge of the different processes involved in the scintillation mechanism leads to the prediction of the effect of temperature and doping level on the performance of the scintillator. A mechanism is proposed to explain the thermally stimulated luminescence processes that cause slow components in the light emission and a loss of light yield. Eventually the study of afterglow reveals a charge transfer to deep traps involved in the high temperature thermally stimulated luminescence. (author)

  2. Robust GPS carrier tracking under ionospheric scintillation

    Science.gov (United States)

    Susi, M.; Andreotti, M.; Aquino, M. H.; Dodson, A.

    2013-12-01

    of the proposed tracking scheme is assessed by using both simulated and real data. Real data have been collected in Vietnam by using a USRP (Universal Software Radio Peripheral) N210 front end connected to a rubidium oscillator. Selected events are exploited in order to challenge the algorithm with strong phase and amplitude variations. Moreover, simulated data have been collected by using the prototype of a digital front end developed by Novatel, namely the 'Firehose'. Since the latter includes a TCXO oscillator, the proposed tracking scheme is also opportunely modified to take in account the clock error contribution. References 1. R.S., Conker, M. B. El-Arini, C. J. Hegarty, and T. Hsiao, Modelling the effects of ionospheric scintillation on GPS/satellite-based augmentation system availability. Radio Sci., 38, 1, 1001, doi: 10.1029/2000RS002604, 2003. 2. B. Bougard et al, 'CIGALA: Challenging the Solar Maximum in Brazil with PolaRxS,' ION GNSS, Portland, Sept. 2011.

  3. DETECTORS: scintillating fibres

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    In the continual search for improved detection techniques, new materials are continually proving profitable. A good example is scintillating plastic fibres - tiny transparent threads sometimes finer than a human hair which transmit light. The narrowness and flexibility of these fibres was a major breakthrough for endoscopy - non-invasive techniques for viewing the otherwise inaccessible in surgery or machine inspection. In a more sophisticated form, these fibres find ready application in communications technology, where the goal is to transmit information rather than electrical power, replacing conventional and unwieldy current-carrying wire conductors. In particle physics, fibres have long been used to take the tiny scintillations produced when high energy particles hit fluorescent materials and 'conduct' them to photosensitive detectors some distance away

  4. Alpha scintillation radon counting

    International Nuclear Information System (INIS)

    Lucas, H.F. Jr.

    1977-01-01

    Radon counting chambers which utilize the alpha-scintillation properties of silver activated zinc sulfide are simple to construct, have a high efficiency, and, with proper design, may be relatively insensitive to variations in the pressure or purity of the counter filling. Chambers which were constructed from glass, metal, or plastic in a wide variety of shapes and sizes were evaluated for the accuracy and the precision of the radon counting. The principles affecting the alpha-scintillation radon counting chamber design and an analytic system suitable for a large scale study of the 222 Rn and 226 Ra content of either air or other environmental samples are described. Particular note is taken of those factors which affect the accuracy and the precision of the method for monitoring radioactivity around uranium mines

  5. Scintillator detector array

    International Nuclear Information System (INIS)

    Cusano, D.A.; Dibianca, F.A.

    1981-01-01

    This patent application relates to a scintillator detector array for use in computerized tomography and comprises a housing including a plurality of chambers, the said housing having a front wall transmissive to x-rays and side walls opaque to x-rays, such as of tungsten and tantalum, a liquid scintillation medium including a soluble fluor, the solvent for the fluor being disposed in the chambers. The solvent comprises either an intrinsically high Z solvent or a solvent which has dissolved therein a high Z compound e.g. iodo or bromonaphthalene; or toluene, xylene or trimethylbenzene with a lead or tin alkyl dissolved therein. Also disposed about the chambers are a plurality of photoelectric devices. (author)

  6. Modular scintillation camera

    International Nuclear Information System (INIS)

    Barrett, H. H.

    1985-01-01

    Improved optical coupling modules to be used in coded-aperture-type radiographic imaging systems. In a first system, a rotating slit coded-aperture is employed between the radioactive object and the module. The module consists of one pair of side-by-side photomultipliers receiving light rays from a scintillation crystal exposed to the object via the coded-aperture. The light rays are guided to the photomultipliers by a mask having a central transverse transparent window, or by a cylindrical lens, the mask or lens being mounted in a light-conveying quartz block assembly providing internal reflections at opposite faces of the assembly. This generates output signals from the photomultipliers which can be utilized to compute one-dimensional coordinate values for restoring the image of the radioactive object on a display screen. In another form of optical coupling module, usable with other types of coded-apertures, four square photomultipliers form a substantially square block and receive light rays from scintillations from a scintillation crystal exposed to the radioactive object via the coded-aperture. The light rays are guided to the photomultipliers by a square mask or a centrally transparent square lens configuration mounted in a light-conveying assembly formed by internally reflecting quartz blocks, the optical rays being directed to the respective photomultipliers so as to generate resultant output signals which can be utilized to compute image coordinate values for two-dimensional representation of the radioactive object being examined

  7. Abnormal vital signs are strong predictors for Intensive Care Unit admission and in-hospital mortality in adults triaged in the Emergency Department - A prospective cohort study

    DEFF Research Database (Denmark)

    Barfod, Charlotte; Laurtizen, Marlene Mp; Danker, Jakob K

    2012-01-01

    ABSTRACT: BACKGROUND: Assessment and treatment of the acutely ill patient have improved by introducing systematic assessment and accelerated protocols for specific patient groups. Triage systems are widely used, but few studies have investigated the ability of the triage systems in predicting...... outcome in the unselected acute population. The aim of this study was to quantify the association between the main component of the Hillerod Acute Process Triage (HAPT) system and the outcome measures; Admission to Intensive Care Unit (ICU) and in-hospital mortality, and to identify the vital signs......, scored and categorized at admission, that are most strongly associated with the outcome measures. METHODS: The HAPT system is a minor modification of the Swedish Adaptive Process Triage (ADAPT) and ranks patients into five level colour-coded triage categories. Each patient is assigned a triage category...

  8. Higher order mode laser beam scintillations in oceanic medium

    Science.gov (United States)

    Baykal, Yahya

    2016-01-01

    In a horizontal oceanic optical wireless communication link, the scintillation index (the measure for the intensity fluctuations) of the received intensity caused by the oceanic turbulence is formulated and evaluated when the source is a higher order mode laser. Variations in the scintillation index vs. the underwater turbulence parameters, size of the higher order mode laser source, link length, and the wavelength are examined. Underwater turbulence parameters are the ratio that determines the relative strength of temperature and salinity in driving the index fluctuations, the rate of dissipation of the mean squared temperature, the rate of dissipation of the turbulent kinetic energy, and the Kolmogorov microscale length.

  9. [PS II photochemical efficiency in flag leaf of wheat varieties and its adaptation to strong sun- light intensity on farmland of Xiangride in Qinghai Province, Northwest China].

    Science.gov (United States)

    Shi, Sheng-Bo; Chen, Wen-Jie; Shi, Rui; Li, Miao; Zhang, Huai-Gang; Sun, Ya-Nan

    2014-09-01

    Taking four wheat varieties developed by Northwest Institute of Plateau Biology, Chinese Academy of Sciences, as test materials, with the measurement of content of photosynthetic pigments, leaf area, fresh and dry mass of flag leaf, the PS II photochemistry efficiency of abaxial and adaxial surface of flag leaf and its adaptation to strong solar radiation during the period of heading stage in Xiangride region were investigated with the pulse-modulated in-vivo chlorophyll fluorescence technique. The results indicated that flag leaf angle mainly grew in horizontal state in Gaoyuan 314, Gaoyuan 363 and Gaoyuan 584, and mainly in vertical state in Gaoyuan 913 because of its smaller leaf area and larger width. Photosynthetic pigments were different among the 4 varieties, and positively correlated with intrinsic PS II photochemistry efficiencies (Fv/Fm). In clear days, especially at noon, the photosynthetic photoinhibition was more serious in abaxial surface of flag leaf due to directly facing the solar radiation, but it could recover after reduction of sunlight intensity in the afternoon, which meant that no inactive damage happened in PS II reaction centers. There were significant differences of PS II actual and maximum photochemical efficiencies at the actinic light intensity (ΦPS II and Fv'/Fm') between abaxial and adaxial surface, and their relative variation trends were on the contrary. The photochemical and non-photochemical quenching coefficients (qP and NPQ) had a similar tendency in both abaxial and adaxial surfaces. Although ΦPS II and qP were lower in adaxial surface of flag leaf, the Fv'/Fm' was significantly higher, which indicated that the potential PS II capture efficiency of excited energy was higher. The results demonstrated that process of photochemical and non-photochemical quenching could effectively dissipate excited energy caused by strong solar radiation, and there were higher adaptation capacities in wheat varieties natively cultivated in

  10. Diffractive interstellar scintillation of the quasar J1819+3845 at lambda 21 cm

    NARCIS (Netherlands)

    Macquart, JP; de Bruyn, AG

    We report the discovery of fast, frequency-dependent intensity variations from the scintillating intra-day variable quasar J1819 + 3845 at lambda 21 cm which resemble diffractive interstellar scintillations observed in pulsars. The observations were taken with the Westerbork Synthesis Radio

  11. Results of the R and D activity on the NOE scintillating fiber calorimeter

    International Nuclear Information System (INIS)

    Demitri, I.

    2001-01-01

    The NOE scintillating fiber calorimeter has undergone four years of intense R and D activity. Measurements of light attenuation and time resolution have been carried out on a variety of commercially available scintillating fibers. Both these parameters are important for the optimisation of the design of the calorimeter which will be part of the ICANOE detector

  12. Results of the R and D activity on the NOE scintillating fiber calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Demitri, I. E-mail: ivan.demitri@le.infr.it

    2001-04-01

    The NOE scintillating fiber calorimeter has undergone four years of intense R and D activity. Measurements of light attenuation and time resolution have been carried out on a variety of commercially available scintillating fibers. Both these parameters are important for the optimisation of the design of the calorimeter which will be part of the ICANOE detector.

  13. Effect of spherical aberration on scintillations of Gaussian beams in atmospheric turbulence

    International Nuclear Information System (INIS)

    Ji, Xiaoling; Deng, Jinping

    2014-01-01

    The effect of spherical aberration on scintillations of Gaussian beams in weak, moderate and strong turbulence is studied using numerical simulation method. It is found that the effect of the negative spherical aberration on the on-axis scintillation index is quite different from that of the positive spherical aberration. In weak turbulence, the positive spherical aberration results in a decrease of the on-axis scintillation index on propagation, but the negative spherical aberration results in an increase of the on-axis scintillation index when the propagation distance is not large. In particular, in weak turbulence the negative spherical aberration may cause peaks of the on-axis scintillation index, and the peaks disappear in moderate and strong turbulence, which is explained in physics. The strong turbulence leads to less discrepancy among scintillations of Gaussian beams with and without spherical aberration. - Highlights: • In weak turbulence scintillations can be suppressed using positive spherical aberration. • In weak turbulence scintillations may be very large due to negative spherical aberration. • The effect of spherical aberration on scintillations is less with increasing of turbulence

  14. Effect of spherical aberration on scintillations of Gaussian beams in atmospheric turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Xiaoling, E-mail: jiXL100@163.com; Deng, Jinping

    2014-07-18

    The effect of spherical aberration on scintillations of Gaussian beams in weak, moderate and strong turbulence is studied using numerical simulation method. It is found that the effect of the negative spherical aberration on the on-axis scintillation index is quite different from that of the positive spherical aberration. In weak turbulence, the positive spherical aberration results in a decrease of the on-axis scintillation index on propagation, but the negative spherical aberration results in an increase of the on-axis scintillation index when the propagation distance is not large. In particular, in weak turbulence the negative spherical aberration may cause peaks of the on-axis scintillation index, and the peaks disappear in moderate and strong turbulence, which is explained in physics. The strong turbulence leads to less discrepancy among scintillations of Gaussian beams with and without spherical aberration. - Highlights: • In weak turbulence scintillations can be suppressed using positive spherical aberration. • In weak turbulence scintillations may be very large due to negative spherical aberration. • The effect of spherical aberration on scintillations is less with increasing of turbulence.

  15. The creation of strongly coupled plasmas using an intense heavy ion beam: low-entropy compression of hydrogen and the problem of hydrogen metallization

    Energy Technology Data Exchange (ETDEWEB)

    Tahir, N A [Institut fuer Theoretische Physik, Universitaet Frankfurt, Postfach 11 19 32, 60054 Frankfurt (Germany); Piriz, A R [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Shutov, A [Institute for Problems in Chemical Physics Research, Chernogolovka, Russia (Russian Federation); Varentsov, D [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgarten Str. 9, 64289 Darmstadt (Germany); Udrea, S [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgarten Str. 9, 64289 Darmstadt (Germany); Hoffmann, D H H [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgarten Str. 9, 64289 Darmstadt (Germany); Juranek, H [Fachbereich Physik, Universitaet Rostock, 18051 Rostock (Germany); Redmer, R [Fachbereich Physik, Universitaet Rostock, 18051 Rostock (Germany); Portugues, R F [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Lomonosov, I [Institute for Problems in Chemical Physics Research, Chernogolovka, Russia (Russian Federation); Fortov, V E [Institute for Problems in Chemical Physics Research, Chernogolovka, Russia (Russian Federation)

    2003-06-06

    Intense heavy ion beams deposit energy very efficiently over extended volumes of solid density targets, thereby creating large samples of strongly coupled plasmas. Intense beams of energetic heavy ions are therefore an ideal tool to research this interesting field. It is also possible to design experiments using special beam-target geometries to achieve low-entropy compression of samples of matter. This type of experiments is of particular interest for studying the problem of hydrogen metallization. In this paper we present a design study of such a proposed experiment that will be carried out at the future heavy ion synchrotron facility SIS100, at the Gesellschaft fuer Schwerionenforschung, Darmstadt. This study has been done using a two-dimensional hydrodynamic computer code. The target consists of a solid hydrogen cylinder that is enclosed in a thick shell of lead whose one face is irradiated with an ion beam which has an annular (ring shaped) focal spot. The beam intensity and other parameters are considered to be the same as expected at the future SIS100 facility. The simulations show that due to multiple shock reflection between the cylinder axis and the lead-hydrogen boundary, one can achieve up to 20 times solid density in hydrogen while keeping the temperature as low as a few thousand K. The corresponding pressure is of the order of 10 Mbar. These values of the physical parameters lie within the range of theoretically predicted values for hydrogen metallization. We have also carried out a parameter study of this problem by varying the target and beam parameters over a wide range. It has been found that the results are very insensitive to such changes in the input parameters.

  16. Liquid scintillation alpha particle spectrometry. Progress report

    International Nuclear Information System (INIS)

    Bell, L.L.; Hakooz, S.A.; Johnson, L.O.; Nieschmidt, E.B.; Meikrantz, D.H.

    1979-12-01

    Objective to develop a technique whereby Pu may be put into solution, extracted by solvent extraction into a suitable extractive scintillant and subsequently counted. Presented here are results of attempts to separate beta and alpha activities through pulse shape discrimination. A qualitative discussion is given which yields alpha particle peak widths, resolution and response. The detection efficiency for alpha particles in a liquid scintillant is 100%. Present detection sensitivities of the equipment being used are: 4.5 x 10 -6 μCi (100 s), 1.2 x 10 -6 μCi (1000 s), and 4.0 x 10 -7 μCi (10,000 s) at the 3 sigma level. The detectability of a particular alpha-emitting species is strongly dependent upon the population of other species. The ability to discriminate depends upon the system resolution. 14 figures, 2 tables

  17. Feasibility of precise navigation in high and low latitude regions under scintillation conditions

    Science.gov (United States)

    Juan, José Miguel; Sanz, Jaume; González-Casado, Guillermo; Rovira-Garcia, Adrià; Camps, Adriano; Riba, Jaume; Barbosa, José; Blanch, Estefania; Altadill, David; Orus, Raul

    2018-02-01

    Scintillation is one of the most challenging problems in Global Navigation Satellite Systems (GNSS) navigation. This phenomenon appears when the radio signal passes through ionospheric irregularities. These irregularities represent rapid changes on the refraction index and, depending on their size, they can produce also diffractive effects affecting the signal amplitude and, eventually producing cycle slips. In this work, we show that the scintillation effects on the GNSS signal are quite different in low and high latitudes. For low latitude receivers, the main effects, from the point of view of precise navigation, are the increase of the carrier phase noise (measured by σϕ) and the fade on the signal intensity (measured by S4) that can produce cycle slips in the GNSS signal. With several examples, we show that the detection of these cycle slips is the most challenging problem for precise navigation, in such a way that, if these cycle slips are detected, precise navigation can be achieved in these regions under scintillation conditions. For high-latitude receivers the situation differs. In this region the size of the irregularities is typically larger than the Fresnel length, so the main effects are related with the fast change on the refractive index associated to the fast movement of the irregularities (which can reach velocities up to several km/s). Consequently, the main effect on the GNSS signals is a fast fluctuation of the carrier phase (large σϕ), but with a moderate fade in the amplitude (moderate S4). Therefore, as shown through several examples, fluctuations at high-latitude usually do not produce cycle slips, being the effect quite limited on the ionosphere-free combination and, in general, precise navigation can be achieved also during strong scintillation conditions.

  18. Ionospheric scintillations at Guilin detected by GPS ground-based and radio occultation observations

    Science.gov (United States)

    Zou, Yuhua

    2011-03-01

    The occurrence of ionospheric scintillations with S4 ⩾ 0.2 was studied using GPS measurements at Guilin, China (25.29°N, 110.33°E; geomagnetic: 15.04°N, 181.98°E), a station located near the northern crest of the equatorial anomaly. The results are presented for data collected from January 2009 to March 2010. The results show that nighttime amplitude scintillations only took place in February and March of the considered years, while daytime amplitude scintillations occurred in August and December of 2009. Nighttime amplitude scintillations, observed in the south of Guilin, always occurred with phase scintillations, TEC (Total Electron Content) depletions, and ROT (Rate Of change of TEC) fluctuations. However, TEC depletions and ROT fluctuations were weak during daytime amplitude scintillations, and daytime amplitude scintillations always took place simultaneously for most of the GPS satellites which appeared over Guilin in different azimuth directions. Ground-based GPS scintillation/TEC observations recorded at Guilin and signal-to-noise-ratio (SNR) measurements obtained from GPS-COSMIC radio occultation indicate that nighttime and daytime scintillations are very likely caused by ionospheric F region irregularities and sporadic E, respectively. Moreover, strong daytime amplitude scintillations may be associated with the plasma density enhancements in ionospheric E region caused by the Perseid and Geminid meteor shower activities.

  19. Scintillating fiber detector

    CERN Document Server

    Vozak, Matous

    2016-01-01

    NA61 is one of the physics experiments at CERN dedicated to study hadron states coming from interactions of SPS beams with various targets. To determine the position of a secondary beam, three proportional chambers are placed along the beamline. However, these chambers tend to have slow response. In order to obtain more precise time information, use of another detector is being considered. Fast response and compact size is making scintillation fiber (SciFi) with silicon photomultiplier (Si-PM) read out a good candidate. This report is focused on analysing data from SciFi collected in a test beam at the beginning of July 2016.

  20. Scintillating-fibre calorimetry

    International Nuclear Information System (INIS)

    Livan, M.; Vercesi, V.; Wigmans, R.

    1995-01-01

    In the past decade, calorimetry based on scintillating plastic fibres as active elements was developed from a conceptual idea to a mature detector technology, which is nowadays widely applied in particle physics experiments. This development and the performance characteristics of representative calorimeters, both for the detection of electromagnetic and hadronic showers, are reviewed. We also discuss new information on shower development processes in dense matter and its application to calorimetric principles that has emerged from some very thorough studies that were performed in the framework of this development. (orig.)

  1. Hybrid scintillators for neutron discrimination

    Science.gov (United States)

    Feng, Patrick L; Cordaro, Joseph G; Anstey, Mitchell R; Morales, Alfredo M

    2015-05-12

    A composition capable of producing a unique scintillation response to neutrons and gamma rays, comprising (i) at least one surfactant; (ii) a polar hydrogen-bonding solvent; and (iii) at least one luminophore. A method including combining at least one surfactant, a polar hydrogen-bonding solvent and at least one luminophore in a scintillation cell under vacuum or an inert atmosphere.

  2. Laser Beam Scintillation with Applications

    CERN Document Server

    Andrews, Larry C; Young, Cynthia

    2001-01-01

    Renewed interest in laser communication systems has sparked development of useful new analytic models. This book discusses optical scintillation and its impact on system performance in free-space optical communication and laser radar applications, with a detailed look at propagation phenomena and the role of scintillation on system behavior. Intended for practicing engineers, scientists, and students.

  3. Liquid scintillation in medical diagnosis

    International Nuclear Information System (INIS)

    Painter, K.

    1976-01-01

    With the tremendous increase in the application of radioassay, particularly radioimmunoassay, in the clinical laboratory liquid scintillation counting became an indispensable tool in diagnostic medicine. Few publications, however, have concerned themselves with problem areas which occur with the method in the clinical laboratory. The purpose of this presentation is to summarize our experiences with the liquid scintillation technique in the clinical situation

  4. Equatorial plasma bubbles and L-band scintillations in Africa during solar minimum

    Directory of Open Access Journals (Sweden)

    V. V. Paznukhov

    2012-04-01

    Full Text Available We report on the longitudinal, local time and seasonal occurrence of equatorial plasma bubbles (EPBs and L band (GPS scintillations over equatorial Africa. The measurements were made in 2010, as a first step toward establishing the climatology of ionospheric irregularities over Africa. The scintillation intensity is obtained by measuring the standard deviation of normalized GPS signal power. The EPBs are detected using an automated technique, where spectral analysis is used to extract and identify EPB events from the GPS TEC measurements. Overall, the observed seasonal climatology of the EPBs as well as GPS scintillations in equatorial Africa is adequately explained by geometric arguments, i.e., by the alignment of the solar terminator and local geomagnetic field, or STBA hypothesis (Tsunoda, 1985, 2010a. While plasma bubbles and scintillations are primarily observed during equinoctial periods, there are longitudinal differences in their seasonal occurrence statistics. The Atlantic sector has the most intense, longest lasting, and highest scintillation occurrence rate in-season. There is also a pronounced increase in the EPB occurrence rate during the June solstice moving west to east. In Africa, the seasonal occurrence shifts towards boreal summer solstice, with fewer occurrences and shorter durations in equinox seasons. Our results also suggest that the occurrence of plasma bubbles and GPS scintillations over Africa are well correlated, with scintillation intensity depending on depletion depth. A question remains about the possible physical mechanisms responsible for the difference in the occurrence phenomenology of EPBs and GPS scintillations between different regions in equatorial Africa.

  5. Improved proton CT imaging using a bismuth germanium oxide scintillator

    Science.gov (United States)

    Tanaka, Sodai; Nishio, Teiji; Tsuneda, Masato; Matsushita, Keiichiro; Kabuki, Shigeto; Uesaka, Mitsuru

    2018-02-01

    Range uncertainty is among the most formidable challenges associated with the treatment planning of proton therapy. Proton imaging, which includes proton radiography and proton computed tomography (pCT), is a useful verification tool. We have developed a pCT detection system that uses a thick bismuth germanium oxide (BGO) scintillator and a CCD camera. The current method is based on a previous detection system that used a plastic scintillator, and implements improved image processing techniques. In the new system, the scintillation light intensity is integrated along the proton beam path by the BGO scintillator, and acquired as a two-dimensional distribution with the CCD camera. The range of a penetrating proton is derived from the integrated light intensity using a light-to-range conversion table, and a pCT image can be reconstructed. The proton range in the BGO scintillator is shorter than in the plastic scintillator, so errors due to extended proton ranges can be reduced. To demonstrate the feasibility of the pCT system, an experiment was performed using a 70 MeV proton beam created by the AVF930 cyclotron at the National Institute of Radiological Sciences. The accuracy of the light-to-range conversion table, which is susceptible to errors due to its spatial dependence, was investigated, and the errors in the acquired pixel values were less than 0.5 mm. Images of various materials were acquired, and the pixel-value errors were within 3.1%, which represents an improvement over previous results. We also obtained a pCT image of an edible chicken piece, the first of its kind for a biological material, and internal structures approximately one millimeter in size were clearly observed. This pCT imaging system is fast and simple, and based on these findings, we anticipate that we can acquire 200 MeV pCT images using the BGO scintillator system.

  6. Thermal degradation of plastic scintillators

    International Nuclear Information System (INIS)

    Andreeshchev, E.A.; Kilin, S.F.; Kushakevich, Yu.P.; Rozman, I.M.; Shoniya, V.M.

    1982-01-01

    The methods for investigations of thermal degradation of plastic scintillators (PS) in air at 120 deg C are described and the results of studies are presented. It is shown that at the elevated temperature under conditions of free access of air a decrease in the luminescence yield and reduction in scintillation duration is observed. In the near-surface layer of scintillators a quenching of molecular excited states and absorption of luminescence are observed. No restoration of the scintillation properties in scintillators treated with heat has been observed. A conclusion is drawn that the PS thermal stability could be improved either by the use of a reflector or larger sizes of PS, or by shifting the luminescence spectrum to the long-wave region

  7. The role of post-sunset vertical drifts at the equator in predicting the onset of VHF scintillations during high and low sunspot activity years

    Directory of Open Access Journals (Sweden)

    S. Tulasi Ram

    2006-07-01

    Full Text Available The day-to-day variability in the occurrence of ionospheric scintillations, which are of serious concern in the trans-ionospheric communications, makes their prediction still a challenging problem. This paper reports on a systematic study in quantitatively identifying the precursors responsible, such as pre-reversal E×B drift velocity, geo-magnetic activity index (Kp and the Equatorial Ionization Anomaly (EIA gradient, for the onset of VHF scintillations over a low-latitude station, Waltair (20° N dip, during high (2001 and low (2004 sunspot activity years. The percentage of occurrences of VHF scintillations over Waltair show a good correlation with the monthly mean post-sunset vertical drift velocities at the equator, during both the high and low sunspot activity years. During the days on which intense (>10 dB scintillations occur, the ionization anomaly gradient (dN/dL, measured from ionosonde data of an equatorial (Trivandrum, 0.9° N dip and an off-equatorial station (Waltair, 20° N dip shows an enhancement in the gradient prior to the onset of the scintillations. However, this enhancement is not seen on days when the scintillations are weak (<10 dB or absent. The day-to-day post sunset enhancement in the E×B drift is found to decrease with increasing Kp-index and this decrease is more prominent in the equinoxes, less in winter and insignificant in the summer months. On a day-to-day basis, it is found that the value of the upward drift velocity at the equator should be ≥30 m/s for the onset of strong scintillations over Waltair for magnetically quiet days with average Kp≤2 (6 h prior to the local sunset during the high sunspot year, 2001. This threshold value of the upward drift reduces to 20 m/s with the decrease in the sunspot activity during 2004. Further, these conditions for the onset of intense scintillations is well defined in equinoxes, less in

  8. Time-based position estimation in monolithic scintillator detectors

    NARCIS (Netherlands)

    Tabacchini, V.; Borghi, G.; Schaart, D.R.

    2015-01-01

    Gamma-ray detectors based on bright monolithic scintillation crystals coupled to pixelated photodetectors are currently being considered for several applications in the medical imaging field. In a typical monolithic detector, both the light intensity and the time of arrival of the earliest

  9. Tomography of the Solar Wind using Interplanetary Scintillation ...

    Indian Academy of Sciences (India)

    tribpo

    Tomography—solar wind—interplanetary scintillation. Extended abstract. Interplanetary ... properties of solar wind (SW) along the line of sight (los) to a distant compact radio source. Mapping a los back to ... power spectra of intensity fluctuations, the primary IPS observable, constructed using the distribution of properties of ...

  10. Scintillators and other particle optical detectors

    International Nuclear Information System (INIS)

    Chipaux, R.

    2011-01-01

    The author reports and comments his researcher career in the field of particle optical detectors. He addresses the cases of organic scintillators (scintillating fibers, liquid scintillators), inorganic scintillators (crystals for electromagnetic calorimetry, crystals for solar neutrino spectroscopy), and Cherenkov Effect detectors. He also reports his works on Cd Te detectors and their modelling

  11. Scintillating plate calorimeter optical design

    International Nuclear Information System (INIS)

    McNeil, R.; Fazely, A.; Gunasingha, R.; Imlay, R.; Lim, J.

    1990-01-01

    A major technical challenge facing the builder of a general purpose detector for the SSC is to achieve an optimum design for the calorimeter. Because of its fast response and good energy resolution, scintillating plate sampling calorimeters should be considered as a possible technology option. The work of the Scintillating Plate Calorimeter Collaboration is focused on compensating plate calorimeters. Based on experimental and simulation studies, it is expected that a sampling calorimeter with alternating layers of high-Z absorber (Pb, W, DU, etc.) and plastic scintillator can be made compensating (e/h = 1.00) by suitable choice of the ratio of absorber/scintillator thickness. Two conceptual designs have been pursued by this subsystem collaboration. One is based on lead as the absorber, with read/out of the scintillator plates via wavelength shifter fibers. The other design is based on depleted uranium as the absorber with wavelength shifter (WLS) plate readout. Progress on designs for the optical readout of a compensating scintillator plate calorimeter are presented. These designs include readout of the scintillator plates via wavelength shifter plates or fiber readout. Results from radiation damage studies of the optical components are presented

  12. Sub-nanosecond plastic scintillators

    International Nuclear Information System (INIS)

    Lyons, P.B.; Caldwell, S.E.; Hocker, L.P.; Crandall, D.G.; Zagarino, P.A.; Cheng, J.; Tirsell, G.; Hurlbut, C.R.

    1976-01-01

    Quenched plastic scintillators have been developed that yield much faster short decay components and greatly reduced long decay components compared to conventional plastic scintillators. The plastics are produced through the addition of selected quench agents to NE111 plastic scintillator that result in reduced total light output. Eight different agents have been studied. Benzophenone and piperidine are two of the most effective quench agents. Data are presented both for short and long decay components. The plastics are expected to make significant contributions in areas of plasma diagnostics

  13. Sub-nanosecond plastic scintillators

    International Nuclear Information System (INIS)

    Lyons, P.B.; Caldwell, S.E.; Hocker, L.P.; Crandall, D.G.; Zagarino, P.A.; Cheng, J.; Tirsell, G.; Hurlbut, C.R.

    1977-01-01

    Quenched plastic scintillators have been developed that yield much faster short decay components and greatly reduced long decay components compared to conventional plastic scintillators. The plastics are produced through the addition of selected quench agents to NE111 plastic scintillator that result in reduced total light output. Eight different agents have been studied. Benzophenone and piperidine are two of the most effective quench agents. Data are presented both for short and long decay components. The plastics are expected to make significant contributions in areas of plasma diagnostics

  14. Scintillation counter, segmented shield

    International Nuclear Information System (INIS)

    Olson, R.E.; Thumim, A.D.

    1975-01-01

    A scintillation counter, particularly for counting gamma ray photons, includes a massive lead radiation shield surrounding a sample-receiving zone. The shield is disassembleable into a plurality of segments to allow facile installation and removal of a photomultiplier tube assembly, the segments being so constructed as to prevent straight-line access of external radiation through the shield into radiation-responsive areas. Provisions are made for accurately aligning the photomultiplier tube with respect to one or more sample-transmitting bores extending through the shield to the sample receiving zone. A sample elevator, used in transporting samples into the zone, is designed to provide a maximum gamma-receiving aspect to maximize the gamma detecting efficiency. (U.S.)

  15. Encapsulated scintillation detector

    International Nuclear Information System (INIS)

    Toepke, I.L.

    1982-01-01

    A scintillation detector crystal is encapsulated in a hermetically sealed housing having a glass window. The window may be mounted in a ring by a compression seal formed during cooling of the ring and window after heating. The window may be chemically bonded to the ring with or without a compression seal. The ring is welded to the housing along thin weld flanges to reduce the amount of weld heat which must be applied. A thin section is provided to resist the flow of welding heat to the seal between the ring and the window thereby forming a thermal barrier. The thin section may be provided by a groove cut partially through the wall of the ring. A layer of PTFE between the tubular body and the crystal minimizes friction created by thermal expansion. Spring washers urge the crystal towards the window. (author)

  16. Density gradients in the solar plasma observed by interplanetary scintillation

    International Nuclear Information System (INIS)

    Gapper, G.R.; Hewish, A.

    1981-01-01

    A new technique is described which overcomes the limitation set by Fresnel filtering in previous IPS studies of the small-scale density irregularities in the solar plasma. Phase gradients introduced by irregularities larger than the Fresnel limit cause transverse displacements of the small-scale scintillation pattern. In the presence of the solar wind, such refraction effects may be revealed by simultaneous measurements of intensity scintillation at two radio frequencies. Observations show that the structure corresponding to temporal frequencies approximately 0.02 Hz is in agreement with an extrapolation of the Kolmogorov spectrum derived from spacecraft data at lower frequencies. (author)

  17. Properties of scintillator solutes

    International Nuclear Information System (INIS)

    Fluornoy, J.M.

    1998-06-01

    This special report summarizes measurements of the spectroscopic and other properties of the solutes that were used in the preparation of several new liquid scintillators developed at EG and G/Energy Measurements/Santa Barbara Operations (the precursor to Bechtel Nevada/Special Technologies Laboratory) on the radiation-to-light converter program. The data on the individual compounds are presented in a form similar to that used by Prof. Isadore Berlman in his classic handbook of fluorescence spectra. The temporal properties and relative efficiencies of the new scintillators are presented in Table 1, and the efficiencies as a function of wavelength are presented graphically in Figure 1. In addition, there is a descriptive glossary of the abbreviations used herein. Figure 2 illustrates the basic structures of some of the compounds and of the four solvents reported in this summary. The emission spectra generally exhibit more structure than the absorption spectra, with the result that the peak emission wavelength for a given compound may lie several nm away from the wavelength, λ avg , at the geometric center of the emission spectrum. Therefore, the author has chosen to list absorption peaks, λ max , and emission λ avg values in Figures 3--30, as being most illustrative of the differences between the compounds. The compounds, BHTP, BTPB, ADBT, and DPTPB were all developed on this program. P-terphenyl, PBD, and TPB are commercially available blue emitters. C-480 and the other longer-wavelength emitters are laser dyes available commercially from Exciton Corporation. 1 ref., 30 figs

  18. Random wave fields and scintillated beams

    CSIR Research Space (South Africa)

    Roux, FS

    2009-01-01

    Full Text Available morphologies the circulation values fluctuates, but differs significantly for two topological charges. CSIR National Laser Centre – p.17/29 Forces annihilation To get rid of optical vortices in strongly scintillated optical beams, the idea is to force a vortex... dipole to annihilate sooner by introducing a special phase function. u t Gaussian beam Vortex trajectory t Dipole annihilation u Phase function for forced annihilation CSIR National Laser Centre – p.18/29 Annihilation in Gaussian beam Using our knowledge...

  19. Detectors for proton counting. Si-APD and scintillation detectors

    International Nuclear Information System (INIS)

    Kishimoto, Shunji

    2008-01-01

    Increased intensity of synchrotron radiation requests users to prepare photon pulse detectors having higher counting rates. As detectors for photon counting, silicon-avalanche photodiode (Si-APD) and scintillation detectors were chosen for the fifth series of detectors. Principle of photon detection by pulse and need of amplification function of the detector were described. Structure and working principle, high counting rate measurement system, bunch of electrons vs. counting rate, application example of NMR time spectroscopy measurement and comments for users were described for the Si-APD detector. Structure of scintillator and photomultiplier tube, characteristics of scintillator and performance of detector were shown for the NaI detector. Future development of photon pulse detectors was discussed. (T. Tanaka)

  20. A new type of a gas scintillating chamber

    International Nuclear Information System (INIS)

    Khoury, H.J.

    1981-01-01

    In a previous paper (H.J. Khoury - thesis - 1978) the author has described a new type of a gas scintillating chamber, in which the light emitted by excitation of the gas, due to the passage of a charged incoming particle, has its intensity increased by the action of an applied electric field. New experiments are described which contribute to a deeper understanding of the phenomena involved in the scintillating chamber due to the nature of the gas, the electric field and spatial distribution, etc.. The behaviour of the gas scintillation counter is studied both in the proportional region and in the region of limited proportionality. It is shown that by the use of a suitable gas mixture and applied electric field, the resolution of an alpha particle spectrum is considerably increased and values up to 0,9% can be attained. (Author) [pt

  1. Optical and scintillation properties of bulk ZnO crystal

    Energy Technology Data Exchange (ETDEWEB)

    Yanagida, Takayuki [Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu, Kitakyushu 808-0196 (Japan); Fujimoto, Yutaka; Kurosawa, Shunsuke [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yamanoi, Kohei; Sarukura, Nobuhiko [Institute of Laser Engineering, Osaka University, Suita, Osaka 565-0871 (Japan); Kano, Masataka; Wakamiya, Akira [Daishinku Corporation, 1389 Shinzaike, Hiraoka-cho, Kakogawa, Hyogo 675-0194 (Japan)

    2012-12-15

    Single crystal bulk ZnO scintillator grown by the hydrothermal method was tested on its scintillation performances. In X-ray induced radio luminescence spectrum, it exhibited two intense emission peaks at 400 and 550 nm. The former was ascribed to the free and bound exciton related luminescence and the latter to oxygen vacancy related one, respectively. X-ray induced scintillation decay time of the exciton related emission measured by the pulse X-ray streak camera system resulted {proportional_to} 4 ns. Finally, the light yield under {sup 241}Am 5.5 MeV {alpha}-ray was examined and it resulted {proportional_to} 500 ph/5.5 MeV-{alpha}.(copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Temperature dependence of plastic scintillators

    Science.gov (United States)

    Peralta, L.

    2018-03-01

    Plastic scintillator detectors have been studied as dosimeters, since they provide a cost-effective alternative to conventional ionization chambers. Several articles have reported undesired response dependencies on beam energy and temperature, which provides the motivation to determine appropriate correction factors. In this work, we studied the light yield temperature dependency of four plastic scintillators, BCF-10, BCF-60, BC-404, RP-200A and two clear fibers, BCF-98 and SK-80. Measurements were made using a 50 kVp X-ray beam to produce the scintillation and/or radioluminescence signal. The 0 to 40 °C temperature range was scanned for each scintillator, and temperature coefficients were obtained.

  3. Scintillation properties of transparent ceramic and single crystalline Nd:YAG scintillators

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Kamada, Kei; Fujimoto, Yutaka; Yokota, Yuui; Yoshikawa, Akira; Yagi, Hideki; Yanagitani, Takagimi

    2011-01-01

    Nd 0.1, 1.1, 2, 4, and 6 mol% doped YAG transparent ceramics are manufactured by the sintering method and their scintillation properties are compared with those of single crystalline Nd 1 mol% doped YAG grown by the micro-pulling down method. They show ∼80% transmittance at wavelengths longer than 300 nm and strong emission lines due to Nd 3+ 4f-4f emission in their radio-luminescence spectra. Among them, the single crystalline sample shows the highest light yield of 11,000 ph/MeV under γ-ray excitation and the second highest one is from Nd 1.1 mol% doped transparent ceramic, which shows 6000 ph/MeV. In these scintillators, dominant decay time constant is around 2-3 μs due to Nd 3+ 4f-4f transitions.

  4. Scintillation properties of transparent ceramic and single crystalline Nd:YAG scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Yanagida, Takayuki, E-mail: t_yanagi@tagen.tohoku.ac.j [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Kamada, Kei; Fujimoto, Yutaka; Yokota, Yuui [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yoshikawa, Akira [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Yagi, Hideki; Yanagitani, Takagimi [Konoshima Chemical Co., Ltd., 80 Kouda, Takuma, Mitoyo-gun, Kagawa 769-1103 (Japan)

    2011-03-01

    Nd 0.1, 1.1, 2, 4, and 6 mol% doped YAG transparent ceramics are manufactured by the sintering method and their scintillation properties are compared with those of single crystalline Nd 1 mol% doped YAG grown by the micro-pulling down method. They show {approx}80% transmittance at wavelengths longer than 300 nm and strong emission lines due to Nd{sup 3+} 4f-4f emission in their radio-luminescence spectra. Among them, the single crystalline sample shows the highest light yield of 11,000 ph/MeV under {gamma}-ray excitation and the second highest one is from Nd 1.1 mol% doped transparent ceramic, which shows 6000 ph/MeV. In these scintillators, dominant decay time constant is around 2-3 {mu}s due to Nd{sup 3+} 4f-4f transitions.

  5. Photoluminescence and radiation response properties of Ce3+-doped CsCaCl3 crystalline scintillator

    Science.gov (United States)

    Fujimoto, Yutaka; Saeki, Keiichiro; Tanaka, Hironori; Yahaba, Takuma; Yanagida, Takayuki; Koshimizu, Masanori; Asai, Keisuke

    2016-09-01

    In this paper, we report on the photoluminescence and scintillation properties of a newly developed CsCaCl3:Ce (0.5 mol%) crystalline scintillator grown by the vertical Bridgman method. The fluorescence quantum efficiency for the Ce3+ characteristic emission bands centered at around 350-400 nm was 76% under excitation at 330 nm light. The photoluminescence decay time of the Ce3+ was approximately 32 ns. When x-ray excited the crystal, intense emission bands were observed at 350-400 nm, and could be attributed to the Ce3+ emission. The scintillation light yield of the developed crystal was ˜7600 ph MeV-1 compared to a NaI:Tl commercial scintillator, and the principal scintillation decay time was approximately 340 ns plus two fast components of around 1.6 ns and 45 ns.

  6. Photoluminescence and radiation response properties of Ce3+-doped CsCaCl3 crystalline scintillator

    International Nuclear Information System (INIS)

    Fujimoto, Yutaka; Saeki, Keiichiro; Tanaka, Hironori; Yahaba, Takuma; Koshimizu, Masanori; Asai, Keisuke; Yanagida, Takayuki

    2016-01-01

    In this paper, we report on the photoluminescence and scintillation properties of a newly developed CsCaCl 3 :Ce (0.5 mol%) crystalline scintillator grown by the vertical Bridgman method. The fluorescence quantum efficiency for the Ce 3+ characteristic emission bands centered at around 350–400 nm was 76% under excitation at 330 nm light. The photoluminescence decay time of the Ce 3+ was approximately 32 ns. When x-ray excited the crystal, intense emission bands were observed at 350–400 nm, and could be attributed to the Ce 3+ emission. The scintillation light yield of the developed crystal was ∼7600 ph MeV −1 compared to a NaI:Tl commercial scintillator, and the principal scintillation decay time was approximately 340 ns plus two fast components of around 1.6 ns and 45 ns. (paper)

  7. Extruded plastic scintillator including inorganic powders

    Science.gov (United States)

    Bross, Alan D.; Mellott, Kerry L.; Pla-Dalmau, Anna

    2006-06-27

    A method for producing a plastic scintillator is disclosed. A plurality of nano-sized particles and one or more dopants can be combined with a plastic material for the formation of a plastic scintillator thereof. The nano-sized particles, the dopant and the plastic material can be combined within the dry inert atmosphere of an extruder to produce a reaction that results in the formation of a plastic scintillator thereof and the deposition of energy within the plastic scintillator, such that the plastic scintillator produces light signifying the detection of a radiative element. The nano-sized particles can be treated with an inert gas prior to processing the nano-sized particles, the dopant and the plastic material utilizing the extruder. The plastic scintillator can be a neutron-sensitive scintillator, x-ray sensitive scintillator and/or a scintillator for the detection of minimum ionizing particles.

  8. R&D on scintillation materials for novel ionizing radiation detectors for High Energy Physics, medical imaging and industrial applications

    CERN Multimedia

    Chipaux, R; Vasilev, A; Rinaldi, D; Boursier, Y M; Tikhomirov, V; Morel, C; Choi, Y; Tamulaitis, G

    2002-01-01

    The Crystal Clear Collaboration (CCC) was approved by the Detector R&D Committee as RD18 in 1990 with the objective of developing new inorganic scintillators suitable for crystal electromagnetic calorimeters of LHC experiments. From 1990 to 1994, CCC made an intensive investigation for the quest of the most adequate ideal scintillator for the LHC; three main candidates were identified and extensively studied : CeF$_{3}$, PbWO$_{4}$ and heavy scintillating glasses. Lead tungstate was chosen by CMS and ALICE as the most cost effective crystal compliant to LHC conditions. Today 76648 PWO crystals are installed in CMS and 17920 in ALICE. After this success Crystal clear has continued its investigation on new scintillators and the understanding of scintillation mechanisms and light transfer properties in particular : The understanding of cerium ion as activator, The development of LuAP, LuYAP crystals for medical imaging applications, (CERN patent) Investigation of Ytterbium based scintillators for solar ne...

  9. Scintillation properties and X-ray irradiation hardness of Ce3+-doped Gd2O3-based scintillation glass

    International Nuclear Information System (INIS)

    Liu, Liwan; Shao, Chongyun; Zhang, Yu; Liao, Xili; Yang, Qiuhong; Hu, Lili; Chen, Danping

    2016-01-01

    Ce 3+ -doped Gd 2 O 3 -based scintillation glasses are prepared within an air or CO atmosphere. The effects of fluorine, lutetium, barium, and the melting atmosphere on the optical properties, scintillation properties and irradiation hardness are studied. Absorption spectra, luminescence spectra under UV and X-ray excitation, and the X-ray radiation-induced spectra are presented. The results show that the density can be increased by doping with fluorine, lutetium and barium. The luminescence intensity decreases after X-ray irradiation. Because of charge transfer quenching, fluorine and lutetium enhance the UV-excited and X-ray excited luminescence intensity, but barium decreases. Moreover, fluorine and lutetium are advantageous to irradiation hardness while barium is not. In addition, a non-reducing atmosphere provides a higher irradiation hardness than a reducing atmosphere. Fluorine-doped glass is promising to enhance luminescence intensity, promote irradiation hardness, and increase the density.

  10. Cherenkov and scintillation light separation in organic liquid scintillators

    International Nuclear Information System (INIS)

    Caravaca, J.; Descamps, F.B.; Land, B.J.; Orebi Gann, G.D.; Yeh, M.

    2017-01-01

    The CHErenkov/Scintillation Separation experiment (CHESS) has been used to demonstrate the separation of Cherenkov and scintillation light in both linear alkylbenzene (LAB) and LAB with 2 g/L of PPO as a fluor (LAB/PPO). This is the first successful demonstration of Cherenkov light detection from the more challenging LAB/PPO cocktail and improves on previous results for LAB. A time resolution of 338 ± 12 ps FWHM results in an efficiency for identifying Cherenkov photons in LAB/PPO of 70 ± 3% and 63 ± 8% for time- and charge-based separation, respectively, with scintillation contamination of 36 ± 5% and 38 ± 4. LAB/PPO data is consistent with a rise time of τ r = 0.72 ± 0.33 ns. (orig.)

  11. Cherenkov and scintillation light separation in organic liquid scintillators

    Science.gov (United States)

    Caravaca, J.; Descamps, F. B.; Land, B. J.; Yeh, M.; Orebi Gann, G. D.

    2017-12-01

    The CHErenkov/Scintillation Separation experiment (CHESS) has been used to demonstrate the separation of Cherenkov and scintillation light in both linear alkylbenzene (LAB) and LAB with 2 g/L of PPO as a fluor (LAB/PPO). This is the first successful demonstration of Cherenkov light detection from the more challenging LAB/PPO cocktail and improves on previous results for LAB. A time resolution of 338± 12 ps FWHM results in an efficiency for identifying Cherenkov photons in LAB/PPO of 70 ± 3 % and 63± 8% for time- and charge-based separation, respectively, with scintillation contamination of 36± 5% and 38± 4%. LAB/PPO data is consistent with a rise time of τ _r=0.72± 0.33 ns.

  12. Scintillation of artificial satellite radio waves

    International Nuclear Information System (INIS)

    Ryuguji, Osamu

    1974-01-01

    Scintillation is generally explained. Specifically, phase scintillation, amplitude scintillation, and scintillation index are described. The relationship between Spread-F and scintillation shown in the figures of the results observed at Huancayo in Peru is illustrated. The comparison between the scintillation occurrence frequency in case of Early Bird satellite and the change in fsub(o)Esub(S) observation value at Fort Bervoir is illustrated. The marked correlation between geomagnetic activity Ksub(p) and the scintillation of ATS-3 at Narrsarssuaq is shown. In order to facilitate the understanding of scintillation, scintillation profile, that is the dependence on geographical conditions, reception frequency, angle to elevation, time and season must be made clear. Attention has been directed to the movement of scintillation boundary between latitude zones in north- south direction according to time and season, as shown in the observation of Explorer-22 at Oulu. Scintillation region expanded in proportion to geomagnetic activity as shown in the observation of Transit-4A and Explorer-22 at Sagamore Hill and ATS-3 at Thule. In the mid-latitude as Japan, there is no substantial trouble caused by scintillation. But, in the case of establishing world wide satellite net work, scintillation occurrence and its effect must be taken into consideration. The names of research institutes and researchers in the world are listed. (Iwakiri, K.)

  13. Scintillation and optical stimulated luminescence of Ce-doped CaF2

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Fujimoto, Yutaka; Watanabe, Kenichi; Fukuda, Kentaro; Kawaguchi, Noriaki; Miyamoto, Yuka; Nanto, Hidehito

    2014-01-01

    Scintillation and optical stimulated luminescence of Ce 0.1–20% doped CaF 2 crystals prepared by Tokuyama Corp. were investigated. In X-ray induced scintillation spectra, luminescence due to Ce 3+ 5d–4f transition appeared around 320 nm with typically 40 ns decay time. By 241 Am 5.5 MeV α-ray irradiation, 0.1% doped one showed the highest scintillation light yield and the light yield monotonically decreased with Ce concentrations. Optically stimulated luminescence after X-ray irradiation was observed around 320 nm under 550 or 830 nm stimulation in all samples. As a result, intensities of optically stimulated luminescence were proportional to Ce concentrations. Consequently, scintillation and optically stimulated luminescence resulted to have a complementary relation in Ce-doped CaF 2 system. - Highlights: • Optical, scintillation, and OSL properties of Ce 0.1–20% doped CaF 2 were studied. • Scintillation light yield exhibited inverse proportionality to Ce concentrations. • OSL intensities showed proportionality to Ce concentrations. • Complementary relation of scintillation and OSL was experimentally confirmed

  14. Strong Geoscience Departments in Research-Intensive Universities: How do you Know you are One and how Much Planning is Needed to Stay One?

    Science.gov (United States)

    Richardson, R. M.; Beck, S. L.

    2003-12-01

    How do you know your geoscience department is strong? Can it stay that way without conscious planning, relying instead primarily upon day-to-day decisions? The University of Arizona is a member of the American Association of Universities (AAU), a self-selected group of 63 of the most research-intensive public and private institutions in the United States. We will present results of a concentrated look at our own department from both the perspective of the department head (SLB) and a newly reunited member of the department (RMR), returning from an extended stint in administration. In addition, we will present the results of a survey of selected geoscience departments at other AAU institutions. The survey will include demographic data on these departments in terms of numbers of faculty and students, and grant dollars if available, as well as what department heads see as the largest threats and opportunities for their departments in the next five years. We will also seek information on departmental efforts to recruit and retain both faculty and students, and efforts to integrate/balance research and education within the department and the institution. Finally, we will ask departments the extent to which they rely upon, or value, departmental planning efforts. As a beginning, the Department of Geosciences at the University currently has 27 tenure/tenure eligible faculty, 84 graduate students, and 68 undergraduate majors. Approximate annual grant dollars are on the order of \\$4M. The department head (SLB) feels that faculty retention and lack of space are among the largest threats to the department. Faculty retention is critical in an environment where funding is chronically short, and budget cuts have been significant over the last two years. Retention efforts typically involve collaborative efforts with the dean and/or provost. Among the opportunities for the department are the ability to extend and diversify funding within and beyond the NSF, typically multi- and

  15. Mitigating effect on turbulent scintillation using non-coherent multi-beam overlapped illumination

    Science.gov (United States)

    Zhou, Lu; Tian, Yuzhen; Wang, Rui; Wang, Tingfeng; Sun, Tao; Wang, Canjin; Yang, Xiaotian

    2017-12-01

    In order to find an effective method to mitigate the turbulent scintillation for applications involved laser propagation through atmosphere, we demonstrated one model using non-coherent multi-beam overlapped illumination. Based on lognormal distribution and the statistical moments of overlapped field, the reduction effect on turbulent scintillation of this method was discussed and tested against numerical wave optics simulation and laboratory experiments with phase plates. Our analysis showed that the best mitigating effect, the scintillation index of overlapped field reduced to 1/N of that when using single beam illuminating, could be obtained using this method when the intensity of N emitting beams equaled to each other.

  16. Investigation of linear accelerator pulse delivery using fast organic scintillator measurements

    DEFF Research Database (Denmark)

    Beierholm, Anders Ravnsborg; Andersen, Claus Erik; Lindvold, Lars René

    2010-01-01

    Fiber-coupled organic plastic scintillators present an attractive method for time-resolved dose measurements during radiotherapy. Most organic scintillators exhibit a fast response, making it possible to use them to measure individual high-energy X-ray pulses from a medical linear accelerator....... This can be used in complex treatment procedures such as gated intensity-modulated radiotherapy (IMRT)1, where the advantage of dose rate measurements of high temporal resolution is highly emphasized. We report on development of a fast data acquisition scintillator-based system as well as measurements...

  17. Future flood risk in the tropics as measured by changes in extreme runoff intensity is strongly influenced by plant-physiological responses to rising CO2

    Science.gov (United States)

    Kooperman, G. J.; Hoffman, F. M.; Koven, C.; Lindsay, K. T.; Swann, A. L. S.; Randerson, J. T.

    2017-12-01

    Climate change is expected to increase the frequency of intense flooding events, and thus the risk of flood-related mortality, infrastructure damage, and economic loss. Assessments of future flooding from global climate models based only on precipitation intensity and temperature neglect important processes that occur within the land-surface, particularly the impacts of plant-physiological responses to rising CO2. Higher CO2 reduces stomatal conductance, leading to less water loss through transpiration and higher soil moisture. For a given precipitation rate, higher soil moisture decreases the amount of rainwater that infiltrates the surface and increases runoff. Here we assess the relative impacts of plant-physiological and radiative-greenhouse effects on changes in extreme runoff intensity over tropical continents using the Community Earth System Model. We find that extreme percentile rates increase significantly more than mean runoff in response to higher CO2. Plant-physiological effects contribute to only a small increase in precipitation intensity, but are a dominant driver of runoff intensification, contributing to one-half of the 99th percentile runoff intensity change and one-third of the 99.9th percentile change. Comprehensive assessments of future flooding risk need to account for the physiological as well as radiative impacts of CO2 in order to better inform flood prediction and mitigation practices.

  18. Advantages of GSO Scintillator in Imaging and Law Level Gamma-ray Spectroscopy

    CERN Document Server

    Sharaf, J

    2002-01-01

    The single GSO crystal is an excellent scintillation material featuring a high light yield and short decay time for gamma-ray detection. Its performance characteristics were investigated and directly compared to those of BGO. For this purpose, the two scintillators are cut into small crystals of approximately 4*4*10 mm sup 3 and mounted on a PMT. Energy resolution, detection efficiency and counting precision have been measured for various photon energies. In addition to this spectroscopic characterization, the imaging performance of GSO was studied using a scanning rig. The modulation transfer function was calculated and the spatial resolution evaluated by measurements of the detector's point spread function. It is shown that there exists some source intensity for which the two scintillators yield identical precision for identical count time. Below this intensity, the GSO is superior to the BGO detector. The presented properties of GSO suggest potential applications of this scintillator in gamma-ray spectrosc...

  19. Ionospheric precursors to scintillation activity

    Directory of Open Access Journals (Sweden)

    Paul S.J. Spencer

    2014-03-01

    Full Text Available Ionospheric scintillation is the rapid fluctuation of both phase and amplitude of trans-ionospheric radio waves due to small scale electron density irregularities in the ionosphere. Prediction of the occurrence of scintillation at L band frequencies is needed to mitigate the disruption of space-based communication and navigation systems. The purpose of this paper is to present a method of using tomographic inversions of the ionospheric electron density obtained from ground-based GPS data to infer the location and strength of the post-sunset plasma drift vortex. This vortex is related to the pre-reversal enhancement in the eastwards electric field which has been correlated to the subsequent occurrence of scintillation.

  20. Scintillation-Hardened GPS Receiver

    Science.gov (United States)

    Stephens, Donald R.

    2015-01-01

    CommLargo, Inc., has developed a scintillation-hardened Global Positioning System (GPS) receiver that improves reliability for low-orbit missions and complies with NASA's Space Telecommunications Radio System (STRS) architecture standards. A software-defined radio (SDR) implementation allows a single hardware element to function as either a conventional radio or as a GPS receiver, providing backup and redundancy for platforms such as the International Space Station (ISS) and high-value remote sensing platforms. The innovation's flexible SDR implementation reduces cost, weight, and power requirements. Scintillation hardening improves mission reliability and variability. In Phase I, CommLargo refactored an open-source GPS software package with Kalman filter-based tracking loops to improve performance during scintillation and also demonstrated improved navigation during a geomagnetic storm. In Phase II, the company generated a new field-programmable gate array (FPGA)-based GPS waveform to demonstrate on NASA's Space Communication and Navigation (SCaN) test bed.

  1. Unitary scintillation detector and system

    Science.gov (United States)

    McElhaney, S.A.; Chiles, M.M.

    1994-05-31

    The invention is a unitary alpha, beta, and gamma scintillation detector and system for sensing the presence of alpha, beta, and gamma radiations selectively or simultaneously. The scintillators are mounted in a light-tight housing provided with an entrance window for admitting alpha, beta, and gamma radiation and excluding ambient light from the housing. Light pulses from each scintillator have different decay constants that are converted by a photosensitive device into corresponding differently shaped electrical pulses. A pulse discrimination system identifies the electrical pulses by their respective pulse shapes which are determined by decay time. The identified electrical pulses are counted in separate channel analyzers to indicate the respective levels of sensed alpha, beta, and gamma radiations. 10 figs.

  2. Nanophosphor composite scintillator with a liquid matrix

    Science.gov (United States)

    McKigney, Edward Allen; Burrell, Anthony Keiran; Bennett, Bryan L.; Cooke, David Wayne; Ott, Kevin Curtis; Bacrania, Minesh Kantilal; Del Sesto, Rico Emilio; Gilbertson, Robert David; Muenchausen, Ross Edward; McCleskey, Thomas Mark

    2010-03-16

    An improved nanophosphor scintillator liquid comprises nanophosphor particles in a liquid matrix. The nanophosphor particles are optionally surface modified with an organic ligand. The surface modified nanophosphor particle is essentially surface charge neutral, thereby preventing agglomeration of the nanophosphor particles during dispersion in a liquid scintillator matrix. The improved nanophosphor scintillator liquid may be used in any conventional liquid scintillator application, including in a radiation detector.

  3. Eu and Rb co-doped LiCaAlF6 scintillators for neutron detection

    International Nuclear Information System (INIS)

    Yamaji, Akihiro; Yanagida, Takayuki; Kawaguchi, Noriaki; Yokota, Yuui; Fujimoto, Yutaka; Kurosawa, Shunsuke; Pejchal, Jan; Watanabe, Kenichi; Yamazaki, Atsushi; Yoshikawa, Akira

    2013-01-01

    Eu and Rb co-doped LiCaAlF 6 (LiCAF) single crystals with different dopant concentrations were grown by the micro-pulling-down method for neutron detection. Their transmittance spectra showed strong absorption bands at 200–220 and 290–350 nm, and under 241 Am alpha-ray excitation, their radioluminescence spectra exhibited an intense emission peak at 373 nm that was attributed to the Eu 2+ 5d–4f transition. These results were consistent with those for the Rb-free Eu:LiCAF. The highest light yield among the grown crystals was 36,000 ph/n, which was 20% greater than that of the Rb-free crystal. In addition, the neutron-excited scintillation decay times were 650–750 ns slower than that of the Rb-free Eu:LiCAF. -- Highlights: •Eu and Rb co-doped LiCaAlF 6 crystals were grown by the micro-pulling down method. •Transmittance, photoluminescence and radioluminescence spectra were measured. •The light yields and scintillation decays were evaluated under 252 Cf neutron irradiation

  4. Development of scintillating fiber tracker

    International Nuclear Information System (INIS)

    Ishikawa, Shuzo; Kawai, Toshihide; Kozaki, Tetsuo

    1995-01-01

    In order to use thin scintillating fiber (diameter 500 micron) as a particle tracking detector, we have developed a method to construct precise multi-layer scintillating fiber sheets. We have also developed dedicated machines for this purpose. This paper presents the details of the method and the machines. Using these machines, we have produced fiber sheets for CERN WA95/CHORUS, which intend to detect a neutrino oscillation in the νμ-ντ channel using Hybrid Emulsion Set-up. Fiber Trackers are used as a vertex detector which support the neutrino event location in the nuclear emulsion target. (author)

  5. Hygroscopicity Evaluation of Halide Scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Zhuravleva, M [The University of Tennessee; Stand, L [The University of Tennessee; Wei, H [The University of Tennessee; Hobbs, C. L. [University of Tennessee, Knoxville (UTK); Boatner, Lynn A [ORNL; Ramey, Joanne Oxendine [ORNL; Burger, Arnold [Fisk University, Nashville; Rowe, E [Fisk University, Nashville; Bhattacharya, P. [Fisk University, Nashville; Tupitsyn, E [Fisk University, Nashville; Melcher, Charles L [University of Tennessee, Knoxville (UTK)

    2014-01-01

    A collaborative study of relative hygroscopicity of anhydrous halide scintillators grown at various laboratories is presented. We have developed a technique to evaluate moisture sensitivity of both raw materials and grown crystals, in which the moisture absorption rate is measured using a gravimetric analysis. Degradation of the scintillation performance was investigated by recording gamma-ray spectra and monitoring the photopeak position, count rate and energy resolution. The accompanying physical degradation of the samples exposed to ambient atmosphere was photographically recorded as well. The results were compared with ben

  6. Magnetic fields and scintillator performance

    International Nuclear Information System (INIS)

    Green, D.; Ronzhin, A.; Hagopian, V.

    1995-06-01

    Experimental data have shown that the light output of a scintillator depends on the magnitude of the externally applied magnetic fields, and that this variation can affect the calorimeter calibration and possibly resolution. The goal of the measurements presented here is to study the light yield of scintillators in high magnetic fields in conditions that are similar to those anticipated for the LHC CMS detector. Two independent measurements were performed, the first at Fermilab and the second at the National High Magnetic Field Laboratory at Florida State University

  7. Composite scintillators for detection of ionizing radiation

    Science.gov (United States)

    Dai, Sheng [Knoxville, TN; Stephan, Andrew Curtis [Knoxville, TN; Brown, Suree S [Knoxville, TN; Wallace, Steven A [Knoxville, TN; Rondinone, Adam J [Knoxville, TN

    2010-12-28

    Applicant's present invention is a composite scintillator having enhanced transparency for detecting ionizing radiation comprising a material having optical transparency wherein said material comprises nano-sized objects having a size in at least one dimension that is less than the wavelength of light emitted by the composite scintillator wherein the composite scintillator is designed to have selected properties suitable for a particular application.

  8. Time resolution research in liquid scintillating detection

    International Nuclear Information System (INIS)

    He Hongkun; Shi Haoshan

    2006-01-01

    The signal processing design method is introduced into liquid scintillating detection system design. By analyzing the signal of liquid scintillating detection, improving time resolution is propitious to upgrade efficiency of detecting. The scheme of realization and satisfactory experiment data is demonstrated. Besides other types of liquid scintillating detection is the same, just using more high speed data signal processing techniques and elements. (authors)

  9. Thin Scintillating Polarized Targets for Spin Physics

    Science.gov (United States)

    van den Brandt, B.; Bunyatova, E. I.; Hautle, P.; Konter, J. A.

    2003-07-01

    At PSI polarized scintillating targets are available since 1996. Proton polarizations of more than 80%, and deuteron polarizations of 25% in polystyrene-based scintillators can be reached under optimum conditions in a vertical dilution refrigerator with optical access, suited for nuclear and particle physics experiments. New preparation procedures allow to provide very thin polarizable scintillating targets and widen the spectrum of conceivable experiments.

  10. Pulse Shape Discrimination with EJ299 scintillators

    Science.gov (United States)

    Muoio, A.; Cappuzzello, F.; Carbone, D.; Cavallaro, M.; Lanzalone, G.; Pappalardo, A.; Santagati, G.; Trifirò, A.; Tudisco, S.

    2018-02-01

    Recently a new generation plastic scintillator PPO have been developed. They promise excellent performances in terms of neutron/gamma discrimination. In this work we will present the activity made at INFN-LNS on the plastic scintillator EJ299 in comparison with the most traditional liquid scintillator EJ301 used in several nuclear physics experiments.

  11. Photonic crystal scintillators and methods of manufacture

    Science.gov (United States)

    Torres, Ricardo D.; Sexton, Lindsay T.; Fuentes, Roderick E.; Cortes-Concepcion, Jose

    2015-08-11

    Photonic crystal scintillators and their methods of manufacture are provided. Exemplary methods of manufacture include using a highly-ordered porous anodic alumina membrane as a pattern transfer mask for either the etching of underlying material or for the deposition of additional material onto the surface of a scintillator. Exemplary detectors utilizing such photonic crystal scintillators are also provided.

  12. Complex oxide scintillators: material defects and scintillation performace

    Czech Academy of Sciences Publication Activity Database

    Nikl, Martin; Laguta, Valentyn; Vedda, A.

    2008-01-01

    Roč. 245, č. 9 (2008), 1701-1722 ISSN 0370-1972 R&D Projects: GA AV ČR IAA100100810 Institutional research plan: CEZ:AV0Z10100521 Keywords : scintillator * structural defects * impurities * trapping states * electron paramagnetic resonance * thermoluminescence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.166, year: 2008

  13. Day and nighttime L-Band amplitude scintillations during low solar activity at a low latitude station in the South Pacific region

    Science.gov (United States)

    Prasad, Ramendra; Kumar, Sushil

    2017-12-01

    A morphological study of GPS L-band amplitude scintillations observed at a low latitude station, Suva (18.1°S, 178.4°E), Fiji, during low solar activity year 2010 of solar cycle 24, has been presented. Out of a total of 480 scintillation events recorded during 2010, 84.4% were weak (0.2 ≤ S4 lightning activity around the observing station. Annual percentage occurrence shows that scintillations occurred mostly in the daytime with peak occurrence at around 05:00-09:00 LT. The daytime strong scintillation events were not associated with vTEC depletions and phase scintillations, but the signal to noise ratio during the scintillation events decreased with increase in scintillation index (S4). However, the post-midnight strong amplitude scintillations were associated with vTEC depletions and phase scintillations indicative of large scale irregularities (spread-F). The geomagnetic activity effect showed enhanced occurrence on geomagnetically disturbed days as compared to quite conditions. The geomagnetic storm effect on scintillations for 17 storms of different strengths (Dst ≤ 50 nT) during 2010-2011 showed an increase in the occurrence of post-storm scintillations, on the days following the storm.

  14. Time- and frequency-resolved detection of atomic coherence in the regime of strong-field interaction with intense femtosecond laser pulses

    International Nuclear Information System (INIS)

    Konorov, S. O.; Hepburn, J. W.; Milner, V.

    2011-01-01

    Understanding the effect of strong laser pulses on the evolution of an atomic or molecular wave function is important in the context of coherent control in the strong-field regime, when power broadening and dynamic Stark shifts become comparable with or bigger than the bandwidth of the control field. We experimentally demonstrate the method of complete characterization of a complex-valued amplitude of a quantum state driven by a strong two-photon field. The method is based on coherent scattering of a weak probe pulse from the strong-field-induced atomic coherence, followed by the detection of the time- and frequency-resolved parametric four-wave-mixing signal. We show that the proposed technique corresponds to a cross-correlation frequency-resolved optical gating (XFROG) of the highly perturbed evolution of an atomic quantum state. Utilizing the XFROG retrieval algorithm, we determine both the amplitude and phase of an atomic wave function at any time moment throughout the interaction with the driving field. The direct retrieval of the time-dependent phase of the wave function, rather than the population dynamics only, enables us to observe the strong-field effects with arbitrary time and frequency resolution.

  15. Semiconductor scintillator detector for gamma radiation

    International Nuclear Information System (INIS)

    Laan, F.T.V. der; Borges, V.; Zabadal, J.R.S.

    2015-01-01

    Nowadays the devices employed to evaluate individual radiation exposition are based on dosimetric films and thermoluminescent crystals, whose measurements must be processed in specific transductors. Hence, these devices carry out indirect measurements. Although a new generation of detectors based on semiconductors which are employed in EPD's (Electronic Personal Dosemeters) being yet available, it high producing costs and large dimensions prevents the application in personal dosimetry. Recent research works reports the development of new detection devices based on photovoltaic PIN diodes, which were successfully employed for detecting and monitoring exposition to X rays. In this work, we step forward by coupling a 2mm anthracene scintillator NE1, which converts the high energy radiation in visible light, generating a Strong signal which allows dispensing the use of photomultipliers. A low gain high performance amplifier and a digital acquisition device are employed to measure instantaneous and cumulative doses for energies ranging from X rays to Gamma radiation up to 2 MeV. One of the most important features of the PIN diode relies in the fact that it can be employed as a detector for ionization radiation, since it requires a small energy amount for releasing electrons. Since the photodiode does not amplify the corresponding photon current, it must be coupled to a low gain amplifier. Therefore, the new sensor works as a scintillator coupled with a photodiode PIN. Preliminary experiments are being performed with this sensor, showing good results for a wide range of energy spectrum. (author)

  16. Search for missing baryons through scintillation

    International Nuclear Information System (INIS)

    Habibi, F.

    2011-06-01

    Cool molecular hydrogen H 2 may be the ultimate possible constituent to the Milky-Way missing baryon. We describe a new way to search for such transparent matter in the Galactic disc and halo, through the diffractive and refractive effects on the light of background stars. By simulating the phase delay induced by a turbulent medium, we computed the corresponding illumination pattern on the earth for an extended source and a given passband. We show that in favorable cases, the light of a background star can be subjected to stochastic fluctuations of the order of a few percent at a characteristic time scale of a few minutes. We have searched for scintillation induced by molecular gas in visible dark nebulae as well as by hypothetical halo clumpuscules of cool molecular hydrogen (H 2 -He) during two nights, using the NTT telescope and the IR SOFI detector. Amongst a few thousands of monitored stars, we found one light-curve that is compatible with a strong scintillation effect through a turbulent structure in the B68 nebula. Because no candidate were found toward the SMC (Small Magellan Cloud), we are able to establish upper limits on the contribution of gas clumpuscules to the Galactic halo mass. We show that the short time-scale monitoring of a few 10 6 star*hour in the visible band with a >4 m telescope and a fast readout camera should allow one to interestingly quantify or constrain the contribution of turbulent molecular gas to the Galactic halo. (author)

  17. Tine-of-flight characteristics of the scintillation counters with microgrid photomultipliers

    International Nuclear Information System (INIS)

    Akindinov, A.V.; Kiselev, Yu.T.; Martem'yanov, A.N.; Ushakov, V.I.

    2003-01-01

    The time-of-flight characteristics of the scintillation counters with the microgrid dynodes magnetically stable photomultipliers are measured. The scintillation counters with thin plastic scintillators 1.3 and 5 mm thick were intended for operation in the relatively strong scattered magnetic fields up to several kilogauss. The measurements were accomplished in the proton synchrotron beams with the protons and π + -mesons pulses of 0.63 and 1.03 GeV/s and with the π - -mesons pulses of 1.28 GeV/s. The time resolutions in the interval of 45-180 ps are obtained [ru

  18. Flicker of extragalactic radio sources and refractive interstellar scintillation

    International Nuclear Information System (INIS)

    Blandford, R.; Narayan, R.; Romani, R.W.

    1986-01-01

    Recent work has identified variability of flat-spectrum extragalactic radio sources at lambdaroughly-equal10 cm with rms amplitude of approx.2%--3% and time scale of days. We show that this ''flicker'' is consistent with intensity fluctuations caused by refractive scintillation in an extended interstellar medium in our Galaxy. Further observation of flicker may allow the structure of suitable sources to be partially resolved on angular scales smaller than those probed by VLBI

  19. Optimum plastic scintillator and optical fiber combination for brachytherapy dosimetry

    International Nuclear Information System (INIS)

    Arnfield, Mark R.; Gaballa, Hani E.; Zwicker, Robert D.; Islam, Quazi; Schmidt-Ullrich, Rupert

    1995-01-01

    iridium 192 source were measured in the range 200 to 700 nm. The spectra of three commercial plastic scintillators were also measured. The fiber core-generated light was predominantly at UV and blue wavelengths, with a main peak at 285 nm. Two fibers had intense peaks at 400 or 450 nm that were absent from the other 4 fibers. These 2 fibers also had much higher total light output than the others. Under the same irradiation conditions, the integrated light from 3 of the fibers was comparable. The emission spectra of the scintillators showed several apparent discrepancies with the manufacturer's specifications. An 'orange' scintillator with claimed emission at 520-640 nm emitted mostly at shorter wavelengths, with bands at 370 nm and 470nm. A 'green' scintillator showed both green and UV bands, while a 'blue' scintillator had a single band at 420 nm, as claimed. Interestingly, the total, spectrally integrated light output of the three scintillators was the same, within experimental uncertainty. The selection of the optimum fiber and scintillator combination was based on the requirement to keep background light to a minimum. We have eliminated as much as possible of the background light by optical filtration. The best combination for this purpose was the blue scintillator together with one of the relatively weakly emitting fibers. A filter with short wavelength cutoff at 400 nm selectively removed all fiber core emission below 400 nm (57% of the total), while allowing essentially all of the scintillator light to pass through. Conclusions: The often close proximity of the dosimeter stem to brachytherapy sources makes background noise a primary consideration in brachytherapy, since background subtraction alone is insufficient to eliminate noise-based measurement errors. By selecting a scintillator with emission at longer wavelengths, most of the fiber core emission could be selectively removed by optical filtration, without significantly reducing scintillator output. The

  20. Fast plastic scintillator SPS-B18

    International Nuclear Information System (INIS)

    Andreeshchev, E.A.; Avetisyan, V.S.; Veronyan, S.M.

    1988-01-01

    The test results of fast response of SPS-B18 scintillators with 25 mm diameter and height are presented. The scintillators are made by thermal polymerization of solution by two luminescent additions in highly refined styrene. As a first luminescent addition n-terphenyl with 3.5 % concentration is used. The scintillator fast response is obtained by introduction of the second luminescent addition, which atoms (halogen atoms) have small excited state lifetime. The use of the effect of intramolecular quenching of the luminescent addition permits to make a plastic scintillator having scintillation pulse duration at halfheight of 0.15 ns

  1. New scintillating media based on liquid crystals for particle detectors

    CERN Document Server

    Barnik, M I; Vasilchenko, V G; Golovkin, S V; Medvedkov, A M; Soloviev, A S

    2000-01-01

    The study results of optical, photoluminiscent and scintillation properties of a liquid crystal 4-pentyl-4'-cyanobiphenyl are presented. The scintillation light output of this liquid crystal is about 35% of crystal anthracene, its main decay time constants are 4 and 14 ns, and the maximum of light emission spectrum is about 400 nm. The light output of a dissolution of green emitting light scintillation dopant R6 in the liquid crystal is about 120% of crystal anthracene. The light output of the frozen dissolution measured at -112 deg. C is about 2.5 times higher as observed at +20 deg. C. In the uniaxially oriented liquid crystal, the predominant intensity direction of emitted light is pointed perpendicular to the liquid crystal director and an appreciable part of the emitted light is elliptically polarized. The possibility to use scintillation properties of liquid crystals is considered both for the improvement of existing particle detector characteristics and for the creation of new gated particle detectors.

  2. Physics of lead tungstate scintillators

    Czech Academy of Sciences Publication Activity Database

    Laguta, Valentyn; Nikl, Martin; Zazubovich, S.

    2008-01-01

    Roč. 55, č. 3 (2008), s. 1275-1282 ISSN 0018-9499 Institutional research plan: CEZ:AV0Z10100521 Keywords : scintillator * PbWO 4 * luminiscence * photothermal defect creation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.518, year: 2008

  3. Scintillators for positron emission tomography

    International Nuclear Information System (INIS)

    Moses, W.W.; Derenzo, S.E.

    1995-09-01

    Like most applications that utilize scintillators for gamma detection, Positron Emission Tomography (PET) desires materials with high light output, short decay time, and excellent stopping power that are also inexpensive, mechanically rugged, and chemically inert. Realizing that this ''ultimate'' scintillator may not exist, this paper evaluates the relative importance of these qualities and describes their impact on the imaging performance of PET. The most important PET scintillator quality is the ability to absorb 511 keV photons in a small volume, which affects the spatial resolution of the camera. The dominant factor is a short attenuation length (≤ 1.5 cm is required), although a high photoelectric fraction is also important (> 30% is desired). The next most important quality is a short decay time, which affects both the dead time and the coincidence timing resolution. Detection rates for single 511 keV photons can be extremely high, so decay times ≤ 500 ns are essential to avoid dead time losses. In addition, positron annihilations are identified by time coincidence so ≤5 ns fwhm coincidence pair timing resolution is required to identify events with narrow coincidence windows, reducing contamination due to accidental coincidences. Current trends in PET cameras are toward septaless, ''fully-3D'' cameras, which have significantly higher count rates than conventional 2-D cameras and so place higher demands on scintillator decay time. Light output affects energy resolution, and thus the ability of the camera to identify and reject events where the initial 511 keV photon has undergone Compton scatter in the patient. The scatter to true event fraction is much higher in fully-3D cameras than in 2-D cameras, so future PET cameras would benefit from scintillators with a 511 keV energy resolution < 10--12% fwhm

  4. Study of helium and beryllium atoms with strong and short laser field; Etude des atomes d'helium et de beryllium en champ laser intense et bref

    Energy Technology Data Exchange (ETDEWEB)

    Laulan, St

    2004-09-01

    We present a theoretical study of the interaction between a two-active electron atom and an intense (10{sup 14} to 10{sup 15} W/cm{sup 2}) and ultrashort (from a few 10{sup -15} to a few 10{sup -18} s) laser field. In the first part, we describe the current experimental techniques able to produce a coherent radiation of high power in the UV-XUV regime and with femtosecond time duration. A theoretical model of a laser pulse is defined with such characteristics. Then, we develop a numerical approach based on B-spline functions to describe the atomic structure of the two-active electron system. A spectral non perturbative method is proposed to solve the time dependent Schroedinger equation. We focalize our attention on the description of the atomic double continuum states. Finally, we expose results on the double ionization of helium and beryllium atoms with intense and short laser field. In particular, we present total cross section calculations and ejected electron energy distributions in the double continuum after one- and two-photon absorption. (author)

  5. Highly lead-loaded red plastic scintillators as an X-ray imaging system for the Laser Mega Joule

    Energy Technology Data Exchange (ETDEWEB)

    Hamel, M.; Normand, S. [CEA, LIST, Laboratoire Capteurs et Architectures Electroniques, F-91191 Gif-sur-Yvette (France); Turk, G.; Darbon, S. [CEA, DAM, DIF, F-91297 Arpajon (France)

    2011-07-01

    The scope of this project intends to record spatially resolved images of core shape and size of a DT micro-balloon during Inertial Confinement Fusion (ICF) experiments at Laser Mega Joule facility (LMJ). We need to develop an X-ray imaging system which can operate in the radiative background generated by an ignition shot of ICF. The scintillator is a part of the imaging system and has to gather a compromise of scintillating properties (scintillating efficiency, decay time, emission wavelength) so as to both operate in the hard radiative environment and to allow the acquisition of spatially resolved images. Inorganic scintillators cannot be used because no compromise can be found regarding the expected scintillating properties, most of them are not fast enough and emit blue light. Organic scintillators are generally fast, but present low X-ray absorption in the 10 to 40 keV range, that does not permit the acquisition of spatially resolved images. To this aim, we have developed highly lead-loaded and red-fluorescent fast plastic scintillators. Such a combination is not currently available via scintillator suppliers, since they propose only blue-fluorescent plastic scintillators doped with up to 12%w Pb. Thus, incorporation ratio up to 27%w Pb has been reached in our laboratory, which can afford a plastic scintillator with an outstanding Z{sub eff} close to 50. X-rays in the 10 to 40 keV range can thus be detected with a higher probability of photoelectric effect than for classic organic scintillators, such as NE102. The strong orange-red fluorescence can be filtered, so that we can eliminate residual Cerenkov light, generated by {gamma}-ray absorption in glass parts of the imaging system. Decay times of our scintillators evaluated under UV excitation were estimated to be in the range 10 to 13 ns. (authors)

  6. Genomic selection strategies in breeding programs: Strong positive interaction between application of genotypic information and intensive use of young bulls on genetic gain

    DEFF Research Database (Denmark)

    Buch, Line Hjortø; Sørensen, Morten Kargo; Berg, Peer

    2012-01-01

    ) a positive interaction exists between the use of genotypic information and a short generation interval on ΔGAG and (iii) the inclusion of an indicator trait in the selection index will only result in a negligible increase in ΔGAG if genotypic information about the breeding goal trait is known. We examined......We tested the following hypotheses: (i) breeding schemes with genomic selection are superior to breeding schemes without genomic selection regarding annual genetic gain of the aggregate genotype (ΔGAG), annual genetic gain of the functional traits and rate of inbreeding per generation (ΔF), (ii...... four breeding schemes with or without genomic selection and with or without intensive use of young bulls using pseudo-genomic stochastic simulations. The breeding goal consisted of a milk production trait and a functional trait. The two breeding schemes with genomic selection resulted in higher ΔGAG...

  7. Chemical and colour quenching in liquid scintillation counting

    International Nuclear Information System (INIS)

    Scott G, P. E.; Grau M, A.

    1987-01-01

    Chemical and colour quenching for H-3 and C-14 was studied. The method includes spectral analysis of colouring agents; methyl red, (4'-dimethylamine-azobenzene 2-carboxylic acid) dimethyl yellow (4'-dimethylamine-azobenzene) and malachite green (methane, bis .(4-dimethyl aminophenyl) - (phenyl)). External standard channels ratio was applied for the liquid scintillation counting of samples. The introduction of an isolated external standard seems to be a strong tool for the correction of chemical and colour quenching curves. (Author) 12 refs

  8. A helical scintillating fiber hodoscope

    CERN Document Server

    Altmeier, M; Bisplinghoff, J; Bissel, T; Bollmann, R; Busch, M; Büsser, K; Colberg, T; Demiroers, L; Diehl, O; Dohrmann, F; Engelhardt, H P; Eversheim, P D; Felden, O; Gebel, R; Glende, M; Greiff, J; Gross, A; Gross-Hardt, R; Hinterberger, F; Jahn, R; Jeske, M; Jonas, E; Krause, H; Lahr, U; Langkau, R; Lindemann, T; Lindlein, J; Maier, R; Maschuw, R; Mayer-Kuckuck, T; Meinerzhagen, A; Naehle, O; Pfuff, M; Prasuhn, D; Rohdjess, H; Rosendaal, D; Von Rossen, P; Sanz, B; Schirm, N; Schulz-Rojahn, M; Schwarz, V; Scobel, W; Thomas, S; Trelle, H J; Weise, E; Wellinghausen, A; Wiedmann, W; Woller, K; Ziegler, R

    1999-01-01

    A novel scintillating fiber hodoscope in helically cylindric geometry has been developed for detection of low multiplicity events of fast protons and other light charged particles in the internal target experiment EDDA at the Cooler Synchrotron COSY. The hodoscope consists of 640 scintillating fibers (2.5 mm diameter), arranged in four layers surrounding the COSY beam pipe. The fibers are helically wound in opposing directions and read out individually using 16-channel photomultipliers connected to a modified commercial encoding system. The detector covers an angular range of 9 deg. <= THETA<=72 deg. and 0 deg. <=phi (cursive,open) Greek<=360 deg. in the lab frame. The detector length is 590 mm, the inner diameter 161 mm. Geometry and granularity of the hodoscope afford a position resolution of about 1.3 mm. The detector design took into consideration a maximum of reliability and a minimum of maintenance. An LED array may be used for monitoring purposes. (author)

  9. LHCb Upgrade: Scintillating Fibre Tracker

    International Nuclear Information System (INIS)

    Tobin, Mark

    2016-01-01

    The LHCb detector will be upgraded during the Long Shutdown 2 (LS2) of the LHC in order to cope with higher instantaneous luminosities and to read out the data at 40 MHz using a trigger-less read-out system. All front-end electronics will be replaced and several sub-detectors must be redesigned to cope with higher occupancy. The current tracking detectors downstream of the LHCb dipole magnet will be replaced by the Scintillating Fibre (SciFi) Tracker. The SciFi Tracker will use scintillating fibres read out by Silicon Photomultipliers (SiPMs). State-of-the-art multi-channel SiPM arrays are being developed to read out the fibres and a custom ASIC will be used to digitise the signals from the SiPMs. The evolution of the design since the Technical Design Report in 2014 and the latest R & D results are presented.

  10. Studies of novel plastic scintillators

    International Nuclear Information System (INIS)

    McInally, I.D.

    1979-08-01

    The general aim of this study was to synthesize fluorescent compounds which are capable of polymerisation, to prepare polymers and co-polymers from these compounds and to study the photophysical properties of these materials. In this way it is hoped to produce plastic scintillators exhibiting improved energy transfer efficiency. Materials studied included POS(2-phenyl-5-(p vinyl) phenyloxazole) vinyl naphthalene, methyl anthracene terminated poly vinyl toluene) and derivatives of BuPBD. (author)

  11. Buried plastic scintillator muon telescope

    Science.gov (United States)

    Sanchez, F.; Medina-Tanco, G.A.; D'Olivo, J.C.; Paic, G.; Patino Salazar, M.E.; Nahmad-Achar, E.; Valdes Galicia, J.F.; Sandoval, A.; Alfaro Molina, R.; Salazar Ibarguen, H.; Diozcora Vargas Trevino, M.A.; Vergara Limon, S.; Villasenor, L.M.

    Muon telescopes can have several applications, ranging from astrophysical to solar-terrestrial interaction studies, and fundamental particle physics. We show the design parameters, characterization and end-to-end simulations of a detector composed by a set of three parallel dual-layer scintillator planes, buried at fix depths ranging from 0.30 m to 3 m. Each layer is 4 m2 and is composed by 50 rectangular pixels of 4cm x 2 m, oriented at a 90 deg angle with respect to its companion layer. The scintillators are MINOS extruded polystyrene strips with two Bicron wavelength shifting fibers mounted on machined grooves. Scintillation light is collected by multi-anode PMTs of 64 pixels, accommodating two fibers per pixel. The front-end electronics has a time resolution of 7.5 nsec. Any strip signal above threshold opens a GPS-tagged 2 micro-seconds data collection window. All data, including signal and background, are saved to hard disk. Separation of extensive air shower signals from secondary cosmic-ray background muons and electrons is done offline using the GPS-tagged threefold coincidence signal from surface water cerenkov detectors located nearby in a triangular array. Cosmic-ray showers above 6 PeV are selected. The data acquisition system is designed to keep both, background and signals from extensive air showers for a detailed offline data.

  12. Multi element high resolution scintillator structure

    International Nuclear Information System (INIS)

    Cusano, D.A.

    1980-01-01

    A gamma camera scintillator structure, suitable for detecting high energy gamma photons which, in a single scintillator camera, would require a comparatively thick scintillator crystal, so resulting in unacceptable dispersion of light photons, comprises a collimator array of a high Z material with elongated, parallel wall channels with the scintillator material being disposed in one end of the channels so as to form an integrated collimator/scintillator structure. The collimator channel walls are preferably coated with light reflective material and further light reflective surfaces being translucent to gamma photons, may be provided in each channel. The scintillators may be single crystals or preferably comprise a phosphor dispersed in a thermosetting translucent matrix as disclosed in GB2012800A. The light detectors of the assembled camera may be photomultiplier tubes charge coupled devices or charge injection devices. (author)

  13. A Review of Ionospheric Scintillation Models.

    Science.gov (United States)

    Priyadarshi, S

    This is a general review of the existing climatological models of ionospheric radio scintillation for high and equatorial latitudes. Trans-ionospheric communication of radio waves from transmitter to user is affected by the ionosphere which is highly variable and dynamic in both time and space. Scintillation is the term given to irregular amplitude and phase fluctuations of the received signals and related to the electron density irregularities in the ionosphere. Key sources of ionospheric irregularities are plasma instabilities; every irregularities model is based on the theory of radio wave propagation in random media. It is important to understand scintillation phenomena and the approach of different theories. Therefore, we have briefly discussed the theories that are used to interpret ionospheric scintillation data. The global morphology of ionospheric scintillation is also discussed briefly. The most important (in our opinion) analytical and physical models of scintillation are reviewed here.

  14. Morphology of auroral zone radio wave scintillation

    International Nuclear Information System (INIS)

    Rino, C.L.; Matthews, S.J.

    1980-01-01

    This paper describes the morphology of midnight sector and morning sector auroral zone scintillation observations made over a two-year period using the Wideband satelite, which is in a sun-synchronous, low-altitude orbit. No definitive seasonal variation was found. The nighttime data showed the highest scintillation ocurrence levels, but significant amounts of morning scintillation were observed. For the most part the scintillation activity followed the general pattern of local magnetic activity. The most prominent feature in the nightime data is a localized amplitude and phase scintillation enhancement at the point where the propagation vector lies within an L shell. A geometrical effect due to a dynamic slab of sheetlike structures in the F region is hypothesized as the source of his enhancement. The data have been sorted by magnetic activity, proximity to local midnight, and season. The general features of the data are in agreement with the accepted morphology of auroral zone scintillation

  15. Accuracy assessment of Precise Point Positioning with multi-constellation GNSS data under ionospheric scintillation effects

    Science.gov (United States)

    Marques, Haroldo Antonio; Marques, Heloísa Alves Silva; Aquino, Marcio; Veettil, Sreeja Vadakke; Monico, João Francisco Galera

    2018-02-01

    GPS and GLONASS are currently the Global Navigation Satellite Systems (GNSS) with full operational capacity. The integration of GPS, GLONASS and future GNSS constellations can provide better accuracy and more reliability in geodetic positioning, in particular for kinematic Precise Point Positioning (PPP), where the satellite geometry is considered a limiting factor to achieve centimeter accuracy. The satellite geometry can change suddenly in kinematic positioning in urban areas or under conditions of strong atmospheric effects such as for instance ionospheric scintillation that may degrade satellite signal quality, causing cycle slips and even loss of lock. Scintillation is caused by small scale irregularities in the ionosphere and is characterized by rapid changes in amplitude and phase of the signal, which are more severe in equatorial and high latitudes geomagnetic regions. In this work, geodetic positioning through the PPP method was evaluated with integrated GPS and GLONASS data collected in the equatorial region under varied scintillation conditions. The GNSS data were processed in kinematic PPP mode and the analyses show accuracy improvements of up to 60% under conditions of strong scintillation when using multi-constellation data instead of GPS data alone. The concepts and analyses related to the ionospheric scintillation effects, the mathematical model involved in PPP with GPS and GLONASS data integration as well as accuracy assessment with data collected under ionospheric scintillation effects are presented.

  16. Accuracy assessment of Precise Point Positioning with multi-constellation GNSS data under ionospheric scintillation effects

    Directory of Open Access Journals (Sweden)

    Marques Haroldo Antonio

    2018-01-01

    Full Text Available GPS and GLONASS are currently the Global Navigation Satellite Systems (GNSS with full operational capacity. The integration of GPS, GLONASS and future GNSS constellations can provide better accuracy and more reliability in geodetic positioning, in particular for kinematic Precise Point Positioning (PPP, where the satellite geometry is considered a limiting factor to achieve centimeter accuracy. The satellite geometry can change suddenly in kinematic positioning in urban areas or under conditions of strong atmospheric effects such as for instance ionospheric scintillation that may degrade satellite signal quality, causing cycle slips and even loss of lock. Scintillation is caused by small scale irregularities in the ionosphere and is characterized by rapid changes in amplitude and phase of the signal, which are more severe in equatorial and high latitudes geomagnetic regions. In this work, geodetic positioning through the PPP method was evaluated with integrated GPS and GLONASS data collected in the equatorial region under varied scintillation conditions. The GNSS data were processed in kinematic PPP mode and the analyses show accuracy improvements of up to 60% under conditions of strong scintillation when using multi-constellation data instead of GPS data alone. The concepts and analyses related to the ionospheric scintillation effects, the mathematical model involved in PPP with GPS and GLONASS data integration as well as accuracy assessment with data collected under ionospheric scintillation effects are presented.

  17. Scintillation detectors as self organized critical systems?

    International Nuclear Information System (INIS)

    Kalinka, G.; Elekes, Z.; Fueloep, Zs.; Saito, A.

    2004-01-01

    Complete text of publication follows. Recently we have constructed a 312 element scintillation detector (SD) system for nuclear physics experiments. Both manufacture and the quality test were carried out under well controlled conditions. One of the main issues during manufacture was the uniformity of performance of the elements. Performance is determined by the signal amplitude delivered (a product of light creation, collection and detection) and the resolution (dispersion of amplitude). It is the mean and the standard deviation of these two parameters, which can be used to characterize the quality of the detector system. More careful analysis of the amplitude and resolution data, taken with 5.5 MeV particles, in addition, reveals fundamental features of scintillation detectors. Those, familiar with electrical noises, easily recognize from the time order series of data (Fig.a,b) the presence of 1/f α or flicker noise. This can be confirmed by Fourier analysis, which provides the spectral density distribution of the fluctuations, resulting in α = 1.85 ± 0.05 for amplitude and resolution alike (Fig.c). For resolution, however, at higher frequencies there is a transition to white noise. It is well known that 1/f α noise has been observed in several systems having temporal, spatial or spatiotemporal degrees of freedom. Earlier examples are electric current in conductors, rotation of Earth, flow of rivers, heartbeat, stock exchange price indices, etc., recent ones are DNA sequence, human cognition, prime numbers, dynamic images, etc., and now scintillation detectors. Despite extensive research, no universal theory for this ubiquitous phenomenon yet exists. One successful explanation, self organized criticality (SOC), seems, however to fit to our case. Systems, with SOC are characterised by strong interdependence between their constituents. This dynamics results in collective behavior which cannot be understood by studying individual constituents in isolation. They

  18. Monte Carlo model of light transport in scintillating fibers and large scintillators

    International Nuclear Information System (INIS)

    Chakarova, R.

    1995-01-01

    A Monte Carlo model is developed which simulates the light transport in a scintillator surrounded by a transparent layer with different surface properties. The model is applied to analyse the light collection properties of scintillating fibers and a large scintillator wrapped in aluminium foil. The influence of the fiber interface characteristics on the light yield is investigated in detail. Light output results as well as time distributions are obtained for the large scintillator case. 15 refs, 16 figs

  19. Scintillation properties of quantum-dot doped styrene based plastic scintillators

    International Nuclear Information System (INIS)

    Park, J.M.; Kim, H.J.; Hwang, Y.S.; Kim, D.H.; Park, H.W.

    2014-01-01

    We fabricated quantum-dot doped plastic scintillators in order to control the emission wavelength. We studied the characterization of the quantum-dots (CdSe/ZnS) and PPO (2, 5-diphenyloxazole) doped styrene based plastic scintillators. PPO is usually used as a dopant to enhance the scintillation properties of organic scintillators with a maximum emission wavelength of 380 nm. In order to study the scintillation properties of the quantum-dots doped plastic scintillators, the samples were irradiated with X-ray, photon, and 45 MeV proton beams. We observed that only PPO doped plastic scintillators shows a luminescence peak around 380 nm. However, both the quantum-dots and PPO doped plastic scintillators shows luminescence peaks around 380 nm and 520 nm. Addition of quantum-dots had shifted the luminescence spectrum from 380 nm (PPO) toward the region of 520 nm (Quantum-dots). Emissions with wavelength controllable plastic scintillators can be matched to various kinds of photosensors such as photomultiplier tubes, photo-diodes, avalanche photo-diodes, and CCDs, etc. Also quantum-dots doped plastic scintillator, which is irradiated 45 MeV proton beams, shows that the light yield of quantum-dots doped plastic scintillator is increases as quantum-dots doping concentration increases at 520 nm. And also the plastic scintillators were irradiated with Cs-137 γ-ray for measuring fluorescence decay time. -- Highlights: • Quantum-dot doped plastic scintillator is grown by the thermal polymerization method. • Quantum-dot doped plastic scintillators can control the emission wavelength to match with photo-sensor. • Quantum-dots and PPO doped plastic scintillators emitted luminescence peaks around 380 nm and 520 nm. • We observed the energy transfer from PPO to quantum-dot in the quantum-dot doped plastic scintillator

  20. Space-time trellis coding with transmit laser selection for FSO links over strong atmospheric turbulence channels.

    Science.gov (United States)

    García-Zambrana, Antonio; Castillo-Vázquez, Carmen; Castillo-Vázquez, Beatriz

    2010-03-15

    Atmospheric turbulence produces fluctuations in the irradiance of the transmitted optical beam, which is known as atmospheric scintillation, severely degrading the link performance. In this paper, a scheme combining transmit laser selection (TLS) and space-time trellis code (STTC) for multiple-input-single-output (MISO) free-space optical (FSO) communication systems with intensity modulation and direct detection (IM/DD) over strong atmospheric turbulence channels is analyzed. Assuming channel state information at the transmitter and receiver, we propose the transmit diversity technique based on the selection of two out of the available L lasers corresponding to the optical paths with greater values of scintillation to transmit the baseline STTCs designed for two transmit antennas. Based on a pairwise error probability (PEP) analysis, results in terms of bit error rate are presented when the scintillation follows negative exponential and K distributions, which cover a wide range of strong atmospheric turbulence conditions. Obtained results show a diversity order of 2L-1 when L transmit lasers are available and a simple two-state STTC with rate 1 bit/(s .Hz) is used. Simulation results are further demonstrated to confirm the analytical results.

  1. High-symmetry organic scintillator systems

    Science.gov (United States)

    Feng, Patrick L.

    2018-02-06

    An ionizing radiation detector or scintillator system includes a scintillating material comprising an organic crystalline compound selected to generate photons in response to the passage of ionizing radiation. The organic compound has a crystalline symmetry of higher order than monoclinic, for example an orthorhombic, trigonal, tetragonal, hexagonal, or cubic symmetry. A photodetector is optically coupled to the scintillating material, and configured to generate electronic signals having pulse shapes based on the photons generated in the scintillating material. A discriminator is coupled to the photon detector, and configured to discriminate between neutrons and gamma rays in the ionizing radiation based on the pulse shapes of the output signals.

  2. Design of Fluorescent Compounds for Scintillation Detection

    Energy Technology Data Exchange (ETDEWEB)

    Pla-Dalmau, Anna [Northern Illinois U.

    1990-01-01

    Plastic scintillation detectors for high energy physics applications require the development of new fluorescent compounds to meet the demands set by the future generation of particle accelerators such as the Superconducting Supercollider (SSe). Plastic scintillators are commonly based on a polymer matrix doped with two fluorescent compounds: the primary dopant and the wavelength shifter. Their main characteristics are fast response time and high quantum efficiency. The exposure to larger radiation doses and demands for larger light output questions their survivability in the future experiments. A new type of plastic scintillator - intrinsic scintillator - has been suggested. It uses a single dopant as primary and wavelength shifter, and should be less susceptible to radiation damage....

  3. Waveshifters and Scintillators for Ionizing Radiation Detection

    Energy Technology Data Exchange (ETDEWEB)

    B.Baumgaugh; J.Bishop; D.Karmgard; J.Marchant; M.McKenna; R.Ruchti; M.Vigneault; L.Hernandez; C.Hurlbut

    2007-12-11

    Scintillation and waveshifter materials have been developed for the detection of ionizing radiation in an STTR program between Ludlum Measurements, Inc. and the University of Notre Dame. Several new waveshifter materials have been developed which are comparable in efficiency and faster in fluorescence decay than the standard material Y11 (K27) used in particle physics for several decades. Additionally, new scintillation materials useful for fiber tracking have been developed which have been compared to 3HF. Lastly, work was done on developing liquid scintillators and paint-on scintillators and waveshifters for high radiation environments.

  4. High-symmetry organic scintillator systems

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Patrick L.

    2018-03-13

    An ionizing radiation detector or scintillator system includes a scintillating material comprising an organic crystalline compound selected to generate photons in response to the passage of ionizing radiation. The organic compound has a crystalline symmetry of higher order than monoclinic, for example an orthorhombic, trigonal, tetragonal, hexagonal, or cubic symmetry. A photodetector is optically coupled to the scintillating material, and configured to generate electronic signals having pulse shapes based on the photons generated in the scintillating material. A discriminator is coupled to the photon detector, and configured to discriminate between neutrons and gamma rays in the ionizing radiation based on the pulse shapes of the output signals.

  5. Designing an optimally proportional inorganic scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jai, E-mail: jai.singh@cdu.edu.au [School of Engineering and IT, B-Purple-12, Faculty of EHSE, Charles Darwin University, NT 0909 (Australia); Koblov, Alexander [School of Engineering and IT, B-Purple-12, Faculty of EHSE, Charles Darwin University, NT 0909 (Australia)

    2012-09-01

    The nonproportionality observed in the light yield of inorganic scintillators is studied theoretically as a function of the rates of bimolecular and Auger quenching processes occurring within the electron track initiated by a gamma- or X-ray photon incident on a scintillator. Assuming a cylindrical track, the influence of the track radius and concentration of excitations created within the track on the scintillator light yield is also studied. Analysing the calculated light yield a guideline for inventing an optimally proportional scintillator with optimal energy resolution is presented.

  6. Growth and scintillation properties of BaMgF4

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Kawaguchi, Noriaki; Fujimoto, Yutaka; Sugiyama, Makoto; Furuya, Yuki; Kamada, Kei; Yokota, Yuui; Yoshikawa, Akira; Chani, Valery

    2010-01-01

    By using the micro-pulling down (μ-PD) method, the barium magnesium fluoride (BaMgF 4 ) single crystalline scintillator was produced. The crystal was cut and mirror polished to the physical dimensions of 1x2x10 mm 3 for examination of scintillation properties. BaMgF 4 demonstrated ∼70% transmittance in wavelength range above 170 nm, and strong emission peaking around 205 nm was observed under X-ray excitation. The absolute light yield of BaMgF 4 was 1300±100 ph/MeV, and the decay time profile showed two components as 0.57±0.01 (70%) and 2.2±0.31 (30%) ns at room temperature.

  7. Climatology of GNSS ionospheric scintillation at high latitudes

    Science.gov (United States)

    Spogli, L.; Alfonsi, L.; de Franceschi, G.; Romano, V.; Aquino, M.; Dodson, A.; Mitchell, C. N.

    2009-12-01

    Under perturbed conditions caused by intense solar wind magnetosphere coupling, the ionosphere may become highly turbulent and irregularities, typically enhancements or depletions of the electron density embedded in the ambient ionosphere, can form. Such irregularities cause diffraction effects, mainly due to the random fluctuations of the refractive index of the ionosphere, on the satellites signals passing through them and consequent perturbations may cause GNSS navigation errors and outages, abruptly corrupting its performance. Due to the morphology of the geomagnetic field, whose lines are almost vertical at high latitude, polar areas are characterized by the presence of significant ionospheric irregularities having scale sizes ranging from hundreds of kilometers down to a few centimeters and with highly dynamic structures. The understanding of the effect of such phenomena is important, not only in preparation for the next solar cycle (24), whose maximum is expected in 2012, but also for a deeper comprehension of the dynamics of the high-latitude ionosphere. We analyze the fluctuations in the carrier frequency of the radio waves received on the ground, commonly referred to as ionospheric amplitude and phase scintillations, to investigate the physical processes causing them. The phase scintillations on GNSS signals are likely caused by ionospheric irregularities of scale size of hundreds of meters to few kilometers. The amplitude scintillations on GNSS signals are caused by ionospheric irregularities of scale size smaller than the Fresnel radius, which is of the order of hundreds of meters for GNSS signals, typically embedded into the patches. The Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the Institute of Engineering Surveying and Space Geodesy (IESSG) of the University of Nottingham manage the same kind of GISTM (GPS Ionospheric Scintillation and TEC Monitor) receivers over the European high and mid latitude regions and over Antarctica. The

  8. Photodetectors for scintillator proportionality measurement

    Energy Technology Data Exchange (ETDEWEB)

    Moses, William W. [Lawrence Berkeley National Laboratory (United States)], E-mail: wwmoses@lbl.gov; Choong, Woon-Seng [Lawrence Berkeley National Laboratory (United States); Hull, Giulia; Payne, Steve; Cherepy, Nerine; Valentine, John D. [Lawrence Livermore National Laboratory (United States)

    2009-10-21

    We evaluate photodetectors for use in a Compton Coincidence apparatus designed for measuring scintillator proportionality. There are many requirements placed on the photodetector in these systems, including active area, linearity, and the ability to accurately measure low light levels (which implies high quantum efficiency and high signal-to-noise ratio). Through a combination of measurement and Monte Carlo simulation, we evaluate a number of potential photodetectors, especially photomultiplier tubes and hybrid photodetectors. Of these, we find that the most promising devices available are photomultiplier tubes with high ({approx}50%) quantum efficiency, although hybrid photodetectors with high quantum efficiency would be preferable.

  9. Scintillating fibre tracking neutron detector

    International Nuclear Information System (INIS)

    Karlsson, Joakim.

    1995-04-01

    A detector for measurements of collimated fluxes of neutrons in the energy range 2-20 MeV is proposed. It utilizes (n.p) elastic scattering in scintillating optical fibres placed in successive orthogonal layers perpendicular to the neutron flux. A test module has been designed, constructed and tested with respect to separation of neutron and gamma events. The pulse height measurements show the feasibility to discriminate between neutron, gamma and background events. Application to measurements of fusion neutrons is considered. 18 refs, 22 figs, 4 tabs

  10. New shaper of scintillation signals

    International Nuclear Information System (INIS)

    Brovchenko, V.G.

    2001-01-01

    Summation of the exponential shape pulse (abrupt front, exponential fall-off) with the pulse, proportional to its integral (the integration time constant is equal to the exponent fall-off constant), results in the pulse, the apex whereof is horizontal (parallel to the base line). Such a pulse is suitable for registration through standard analog-to-digital converters of the consecutive binary approximation, The described scheme is accomplished for verification of the basic principle of the shaper action. The parameters of the scheme are approximated to those ones, necessary for processing scintillation signals NaI(Tl) [ru

  11. Quantum Dots in Liquid Scintillator

    Science.gov (United States)

    Gooding, Diana

    2017-09-01

    Quantum dots are semiconducting crystals with dimensions on the order of nanometers. Due to quantum confinement, their size gives rise to optical properties that resemble those of single atoms, rather than bulk material. One of these is their absorption of light shorter than a characteristic wavelength and reemission in a narrow peak around that wavelength. This unique photoluminescence makes quantum dots ideal wavelength shifters. Moreover, their chemistry provides a straight-forward method to suspend heavy elements in organic scintillators. The NuDot collaboration has been pursuing a variety of new quantum dots, and a review of the current results will be presented.

  12. Supernova Neutrino Detection With Liquid Scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Ianni, Aldo, E-mail: aldo.ianni@lngs.infn.it [I.N.F.N. Gran Sasso Laboratory, S.S. 17bis, 67100, Assergi (Italy)

    2011-08-10

    Core collapse supernovae are a remarkable source of neutrinos. These neutrinos can also be detected by means of massive liquid scintillators located underground. Observations of supernova neutrinos can shed light on the explosion mechanism and on neutrino properties. In this paper we review the detection channels for neutrinos in liquid scintillators. We consider present and future experiments for supernova neutrino searches.

  13. Ionospheric Scintillation Activity Over Ilorin, Nigeria

    Science.gov (United States)

    Oladipo, O. A.; Adeniyi, J. O.; Doherty, P. H.; Radicella, S. M.; Adimula, I. A.; Olawepo, A. O.

    2018-02-01

    Scintillation of radio waves in the L-band frequency is a regular occurrence at the equatorial and auroral regions at night most especially during high solar activity periods. Scintillation is caused by plasma density irregularities, and this could cause loss of lock of Global Navigation Satellite System (GNSS) signals leading to impairment of the applications that rely on this system. A study on the occurrence of scintillation activity over Ilorin (latitude = 8.48°N, longitude = 4.67°W, and geomagnetic latitude = 1.89°S), Nigeria was done using S4 index data from NovAtel GPStation-2 receiver (2009-2012) and NovAtel GPStation-6 receiver (August 2013 to December 2016) which are both located at this station. The solar maximum period of the solar cycle 24 is located well within the period of this investigation; hence, this study provides opportunity to see the occurrence pattern of scintillation during different seasons as well as the pattern from low solar activity to solar maximum. The results obtained showed that scintillation occurs between 21:00 LT and 04:00 LT at the peak of the occurrence in 2014. The time window of occurrence decreases with decrease in solar activity. Similarly, scintillation activity was observed to be more regular during high solar activity and it has two peaks of occurrence in March and October. A solar activity trend was observed in scintillation occurrence; scintillation activity increases with increase in the level of solar activity.

  14. Present development of scintillator counters in France

    International Nuclear Information System (INIS)

    Koechlin, Y.; Koch, L.; Lansiart, A.

    1958-01-01

    For a number of years photomultipliers and scintillators have been produced on an industrial scale in France. The AEC has accepted the task of testing their performance, and advising the industry in consequence. This combined effort has resulted in the wide range of photomultipliers and scintillators summarised in the following paper. (author) [fr

  15. New Organic Scintillators for Neutron Detection

    Science.gov (United States)

    2016-03-01

    New Organic Scintillators for Neutron Detection Distribution Statement A. Approved for public release; distribution is unlimited. March...Title: New Organic Scintillators for Neutron Detection I. Abstract In this project, Radiation Monitoring Devices (RMD) proposes to develop novel...boron containing organic single crystal detectors for neutron detection as an alternative for 3He based detectors that will fulfill the needs of the

  16. Current status on plastic scintillators modifications

    Energy Technology Data Exchange (ETDEWEB)

    Hamel, Matthieu; Bertrand, Guillaume H.V.; Carrel, Frederick; Coulon, Romain; Dumazert, Jonathan; Montbarbon, Eva; Sguerra, Fabien [CEA, LIST, Laboratoire Capteurs and Architectures electroniques, 91191 Gif-sur-Yvette cedex, (France)

    2015-07-01

    Recent developments of plastic scintillators are reviewed, from 2000 to March 2015. All examples are distributed into the main purpose, i.e. the nature of the radionuclide provided with the scope of detection of various radiation particles. The main characteristics of these newly created scintillators and their detection properties are given. (authors)

  17. Infrared scintillation of Yb(10%): YAG crystal

    NARCIS (Netherlands)

    Antonini, P; Belogurov, S.; Bressi, G; Carugno, G.; Iannuzzi, D

    2002-01-01

    Ytterbium-doped yttrium aluminum garnets (Yb:YAG) are known as IR laser crystals. Previously, we have shown that they are also fast scintillators in the near UV region. In this work we report on the measurements of I R scintillation properties of Yb(10%):YAG crystal. It emits at room temperature at

  18. Some possible improvements in scintillation calorimeters

    International Nuclear Information System (INIS)

    Lorenz, E.

    1985-03-01

    Two ideas for improvements of scintillation calorimeters will be presented: a) improved readout of scintillating, totally active electromagnetic calorimeters with combinations of silicon photodiodes and fluorescent panel collectors, b) use of time structure analysis on calorimetry, both for higher rate applications and improved resolution for hadron calorimeters. (orig.)

  19. Plastic scintillator with small pulse duration

    International Nuclear Information System (INIS)

    Andreeshchev, E.A.; Kilin, S.F.; Kovyrzina, K.A.; Kushakevich, Yu.P.; Rozman, I.M.; Shoniya, V.M.

    1983-01-01

    Characteristics of plastic scintillators with small pulse duration are analysed. For manufacturing the latter two methods of quencher introduction are applied: into the scintillator composition and the molecule of luminescent addition. The second method turned to be more effective. The pulse duration < 0.5 nc is attained

  20. Status of timing with plastic scintillation detectors

    International Nuclear Information System (INIS)

    Moszynski, M.; Bengtson, B.

    1979-01-01

    Timing properties of scintillators and photomultipliers as well as theoretical and experimental studies of time resolution of scintillation counters are reviewed. Predictions of the theory of the scintillation pulse generation processes are compared with the data on the light pulse shape from small samples, in which the light pulse shape depends only on the composition of the scintillator. For larger samples the influence of the light collection process and the self-absorption process on the light pulse shape are discussed. The data on rise times, fwhm's, decay times and light yield of several commercial scintillators used in timing are collected. The next part of the paper deals with the properties of photomultipliers. The sources of time uncertainties in photomultipliers as a spread of the initial velocity of photoelectrons, emission of photoelectrons under different angles and from different points at the photocathode, the time spread and the gain dispersion introduced by electron photomultiplier are reviewed. The experimental data on the time jitter, single electron response and photoelectron yield of some fast photomultipliers are collected. As the time resolution of the timing systems with scintillation counters depends also on time pick-off units, a short presentation of the timing methods is given. The discussion of timing theories is followed by a review of experimental studies of the time resolution of scintillation counters. The paper is ended by an analysis of prospects on further progress of the subnanosecond timing with scintillation counters. (Auth.)

  1. Performance and characteristics of a new scintillator

    CERN Document Server

    Czirr, J B; MacGillivray, R R; Seddon, P J

    1999-01-01

    A new class of scintillators for neutron imaging, based upon lithium gadolinium borate, is described. These scintillators offer the ability to tailor their response to the neutron spectrum by varying the relative absorption of neutrons by the key constituents (lithium, gadolinium and boron). The isotopic compositions of each constituent can be varied in order to change the spectral response.

  2. Ionospheric Scintillation Effects on GPS Measurements and Algorithms to Improve Positioning Solution Accuracy

    Science.gov (United States)

    Myer, Gregory Thomas

    The ionosphere is an important cause of disturbances on GNSS signals, especially in high latitudes and equatorial areas. Previous studies indicate that while ionospheric scintillation may cause abrupt, random fluctuations in carrier phase measurements, its impact on pseu- dorange is less serious. Since modern GNSS receivers, especially those for high precision applications, use carrier phase-smoothed pseudoranges to improve accuracy of position solutions, there exists the need to have a better understanding of the scintillation effects on carrier phase measurements and developing means to mitigate scintillation induced errors in navigation solutions. In this thesis, scintillation impacts are demonstrated on carrier phase and pseudorange measurements using real scintillation data collected at high latitudes and equatorial areas, and the effect on positioning is investigated and mitigated. To obtain a more insightful and quantitative understanding of the impact, the data was used to generate position solutions using standard navigation processing algorithms. The results clearly indicate that sudden carrier phase discontinuities during strong scintillation lead to the degradation of carrier-smoothed pseudorange accuracy and consequently, results in large position errors. During strong scintillation with no carrier phase discontinuities, comparatively smaller position er- rors are found due to phase fluctuations that cause small changes in the range measurements. Based on this analysis, we give examples of several approaches to mitigate these problems, and use these approaches to present adaptive positioning techniques to mitigate scintillation induced position errors. One algorithm simply replaces the carrier-smoothed pseudorange with the unsmoothed pseudorange for satellites that are affected by outages on the carrier phase measurements, or if strong scintillation is detected. Another adaptive algorithm uses the GDOP to determine if a scintillating satellite can be

  3. Detector construction for a scintillation camera

    International Nuclear Information System (INIS)

    Ashe, J.B.

    1977-01-01

    An improved transducer construction for a scintillation camera in which a light conducting element is equipped with a layer of moisture impervious material is described. A scintillation crystal is thereafter positioned in optical communication with the moisture impervious layer and the remaining surfaces of the scintillation crystal are encompassed by a moisture shield. Affixing the moisture impervious layer to the light conducting element prior to attachment of the scintillation crystal reduces the requirement for mechanical strength in the moisture impervious layer and thereby allows a layer of reduced thickness to be utilized. Preferably, photodetectors are also positioned in optical communication with the light conducting element prior to positioning the scintillation crystal in contact with the impervious layer. 13 claims, 4 figures

  4. Development of scintillation materials for PET scanners

    CERN Document Server

    Korzhik, Mikhail; Annenkov, Alexander N; Borissevitch, Andrei; Dossovitski, Alexei; Missevitch, Oleg; Lecoq, Paul

    2007-01-01

    The growing demand on PET methodology for a variety of applications ranging from clinical use to fundamental studies triggers research and development of PET scanners providing better spatial resolution and sensitivity. These efforts are primarily focused on the development of advanced PET detector solutions and on the developments of new scintillation materials as well. However Lu containing scintillation materials introduced in the last century such as LSO, LYSO, LuAP, LuYAP crystals still remain the best PET species in spite of the recent developments of bright, fast but relatively low density lanthanum bromide scintillators. At the same time Lu based materials have several drawbacks which are high temperature of crystallization and relatively high cost compared to alkali-halide scintillation materials. Here we describe recent results in the development of new scintillation materials for PET application.

  5. Inorganic-organic rubbery scintillators

    CERN Document Server

    Gektin, A V; Pogorelova, N; Neicheva, S; Sysoeva, E; Gavrilyuk, V

    2002-01-01

    Spectral-kinetic luminescence properties of films, containing homogeneously dispersed scintillation particles of CsI, CsI:Tl, CsI:Na, and NaI:Tl in optically transparent organosiloxane matrix, are presented. Material is flexible and rubbery and in consequence the detectors of convenient shapes can be produced. It is found that luminescence spectra of the received films are identical whereas decay times are much shorter compared to the same ones of the corresponding single crystals. Layers with pure CsI demonstrate only the fast UV emission (307 nm, 10 ns) without blue microsecond afterglow typical for crystals. The films containing NaI:Tl are non-hygroscopic and preserve scintillation properties for a long time in humid atmosphere unlike single crystals. Organosiloxane layers with CsI:Tl particles provide high light output with good energy resolution for sup 5 sup 5 Fe, sup 1 sup 0 sup 9 Cd, sup 2 sup 4 sup 1 Am sources, and are capable of detecting both X-rays and alpha-, beta-particles.

  6. Explosion-proof scintillation counter

    International Nuclear Information System (INIS)

    Opitts, P.; Borkert, R.

    1979-01-01

    It is noted that measuring devices used in the research works conducted with the help of radioactive isotopes on the chemical industry installations dangerous from the point of view of explosions, especially on the installations of the petrochemistry industry, must not limit the exploitation safety of these installations. The said especially concerns with the Geiger-Mueller type counters and scintillation detectors, located immediately in the places of measurements on the installations and supplied by high voltage power supply. It has been shown that electronic circuits for the detector's signals processing and obtaining working voltages can be located out of the explosive dangerous premices, for example, in the car trailer. Description is given of the device, with the help of which explosion safety is provided for the serially produced scintillation counter with forced ventilation (counter of the VA-S-50 type). Due to this device application, the exploitation parameters of the counter do not go down and there is no need for any changes in its design. Description is given of the device for external power supply and control of the counter which can swich off the power supply in the case of an accident, dangerous from the point of view of violation of the explosion safety conditions. The device is described for providing service to 10 measuring chanels, mounted on the car trailer [ru

  7. Light output enhancement for a plastic scintillator using nanofibers

    Science.gov (United States)

    Cheng, Zhangkai J.; Blake, Samuel J.; Vial, Phil; Lu, Ming; Kuncic, Zdenka; Atakaramians, Shaghik

    2017-08-01

    Electronic portal imaging devices (EPIDs) are x-ray detector systems conventionally used for medical imaging applications in cancer radiotherapy. Our group has developed a novel prototype EPID with the unique capability of performing both imaging and dose measurements. Our prototype utilizes an array of plastic scintillating fibers in place of the standard copper and gadolinium dioxysulfide phosphor components1. While our prototype EPID exhibits a detective quantum efficiency that exceeds that of commercial products, there is further scope for improvement. In particular, there is scope to improve optical coupling between the scintillating fiber array and the underlying photodetector where currently an air gap exists. Here, we investigate the effect of a layer of polystyrene nanofibers placed at the end interface of the scintillator array on light extraction efficiency using finite element modelling. We demonstrate that the total light extraction, which depends on the polarization of the incident light, can be enhanced by up to 14%. This enhancement stems from two effects: Bragg diffraction arising from the periodic arrangement of the fibers and Whispering Gallery Modes (WGMs) formed at each fiber's cross-section due to Mie resonances. We show that the nanofibers increase optical transmittance above the critical angle. Moreover, we demonstrate that the light extraction efficiency strongly depends on the polarization of the incident light (s- and p-polarizations), as well as the diameter and periodicity of the nanofibers.

  8. Study of primary energy transfer process in ultrafast plastic scintillators

    International Nuclear Information System (INIS)

    Bengtson, B.; Moszynski, M.

    1978-01-01

    The study of the light-pulse shape, the initial delay of light pulses and the light yield of plastics prepared by a modification of the NE111 scintillator were performed. The NE111 scintillator doped with several quench agents, the plastics prepared as a solution of butyl PBD in PVT of different concentration and PVT alone were studied. The study confirmed that the light pulse shape from fast binary plastics is well described analytically by the convolution of the clipped Gaussian and exponential functions. The investigation of the PVT-butyl PBD plastics shows that even more than three times larger concentration of butyl PBD compared to that of PBD in the NE111 solution does not improve the rise of the light pulse. Thus the rise time seems to be not controlled by the intermolecular energy transfer process. Finally, the observed rise time of the light pulse from the PVT sample was also approximated well by the Gaussian function. Altogether it brought a strong support for the earlier hypothesis that the initial slow rise of light pulses from plastic scintillators may come from the deexcitation of several higher levels of the solvent molecules excited by nuclear particles. (Auth.)

  9. Development of microcolumnar LaBr3:Ce scintillator

    Science.gov (United States)

    Nagarkar, Vivek V.; Miller, Stuart; Singh, Bipin; Thacker, Samta; Gaysinskiy, Valeriy; Miller, Brian W.; Barber, H. Bradford; Wilson, Donald

    2009-08-01

    While a wide variety of new scintillators are now available, new cerium-doped lanthanide halide scintillators have shown a strong potential to move beyond their familiar role in conventional gamma ray spectroscopy, toward fulfilling the needs of highly demanding applications such as radioisotope identification at room temperature, homeland security, and quantitative molecular imaging for medical diagnostics, staging and research. Despite their extraordinary advantages, however, issues related to reliable, large volume manufacturing of these high light yield materials in a rapid and economic manner have not been resolved or purposefully addressed. Also, if microcolumnar films of this material could be fabricated, it would find widespread use in a multitude of high-speed imaging/nuclear medicine applications. Here we report on synthesizing LaBr3:Ce scintillators using a thermal evaporation technique, which permits the fabrication of high spatial resolution microcolumnar films and holds a potential to synthesize large volumes of high quality material in a time efficient and cost effective manner. Performance evaluation of the fabricated films and their application for SPECT imaging are also discussed.

  10. Suppression background device in neutron detection by a scintillation detector

    International Nuclear Information System (INIS)

    Degtyarev, A.P.; Kozyr', Yu.E.; Prokopets, G.A.

    1980-01-01

    A pulse shape discriminator for suppression of cosmic and gamma background as well as for suppression of intrinsic noises of a photomultiplier is described. Identification of signals of background and neutrons is performed by means of comparison of relative intensity of fast and slow components of scintillator luminescence. Basic discriminator flowsheet which contains integrating and differential RC circuits and time-to-amplitude converter is given. The discriminator provides minimum energy of detected neutrons equal to 500 keV when using a FEhU-36 neutron detector with a stilbene crystal [ru

  11. New liquid scintillators for detectors based on capillary fibers

    International Nuclear Information System (INIS)

    Vasil'chenko, V.G.; Golovkin, S.V.; Zimin, K.V.

    1997-01-01

    Results of investigations of luminescent and optical characteristics of liquid scintillators intended for using in track detectors and calorimeters are presented. The scintillation efficiency of the vacuumed scintillators is by 22-32% higher than in air. Capillaries filled by liquid scintillators are compared with plastic fibers. 19 refs

  12. Estimation of Fano factor in inorganic scintillators

    International Nuclear Information System (INIS)

    Bora, Vaibhav; Barrett, Harrison H.; Fastje, David; Clarkson, Eric; Furenlid, Lars; Bousselham, Abdelkader; Shah, Kanai S.; Glodo, Jarek

    2016-01-01

    The Fano factor of an integer-valued random variable is defined as the ratio of its variance to its mean. Correlation between the outputs of two photomultiplier tubes on opposite faces of a scintillation crystal was used to estimate the Fano factor of photoelectrons and scintillation photons. Correlations between the integrals of the detector outputs were used to estimate the photoelectron and photon Fano factor for YAP:Ce, SrI 2 :Eu and CsI:Na scintillator crystals. At 662 keV, SrI 2 :Eu was found to be sub-Poisson, while CsI:Na and YAP:Ce were found to be super-Poisson. An experiment setup inspired from the Hanbury Brown and Twiss experiment was used to measure the correlations as a function of time between the outputs of two photomultiplier tubes looking at the same scintillation event. A model of the scintillation and the detection processes was used to generate simulated detector outputs as a function of time for different values of Fano factor. The simulated outputs from the model for different Fano factors was compared to the experimentally measured detector outputs to estimate the Fano factor of the scintillation photons for YAP:Ce, LaBr 3 :Ce scintillator crystals. At 662 keV, LaBr 3 :Ce was found to be sub-Poisson, while YAP:Ce was found to be close to Poisson.

  13. Latitudinal extension of low-latitude scintillations measured with a network of GPS receivers

    Directory of Open Access Journals (Sweden)

    C. E. Valladares

    2004-09-01

    Full Text Available A latitudinal-distributed network of GPS receivers has been operating within Colombia, Peru and Chile with sufficient latitudinal span to measure the absolute total electron content (TEC at both crests of the equatorial anomaly. The network also provides the latitudinal extension of GPS scintillations and TEC depletions. The GPS-based information has been supplemented with density profiles collected with the Jicamarca digisonde and JULIA power maps to investigate the background conditions of the nighttime ionosphere that prevail during the formation and the persistence of plasma depletions. This paper presents case-study events in which the latitudinal extension of GPS scintillations, the maximum latitude of TEC depletion detections, and the altitude extension of radar plumes are correlated with the location and extension of the equatorial anomaly. Then it shows the combined statistics of GPS scintillations, TEC depletions, TEC latitudinal profiles, and bottomside density profiles collected between September 2001 and June 2002. It is demonstrated that multiple sights of TEC depletions from different stations can be used to estimate the drift of the background plasma, the tilt of the plasma plumes, and in some cases even the approximate time and location of the depletion onset. This study corroborates the fact that TEC depletions and radar plumes coincide with intense levels of GPS scintillations. Bottomside radar traces do not seem to be associated with GPS scintillations. It is demonstrated that scintillations/depletions can occur when the TEC latitude profiles are symmetric, asymmetric or highly asymmetric; this is during the absence of one crest. Comparison of the location of the northern crest of the equatorial anomaly and the maximum latitude of scintillations reveals that for 90% of the days, scintillations are confined within the boundaries of the 50% decay limit of the anomaly crests. The crests of the anomaly are the regions where the

  14. Low background techniques in liquid scintillator detectors

    Science.gov (United States)

    Miramonti, Lino

    2017-10-01

    Many neutrino physics experiments use organic liquid scintillators, which present a unique advantage: enormous masses (in the order of tens ktons) with very low radioactive background can be reached by assembling a detector with organic liquid scintillators. Thanks to the very fast decay rate, it is possible to localize the event in space and time and discriminate it from the background signals. Furthermore, organic liquid scintillators are very efficient in alfa/beta discrimination and offer the possibility to dissolve solvents in the chemical compounds to enhance the signal.

  15. Advanced plastic scintillators for fast neutron discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Patrick L [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Anstey, Mitchell [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Doty, F. Patrick [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Mengesha, Wondwosen [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2014-09-01

    The present work addresses the need for solid-state, fast neutron discriminating scintillators that possess higher light yields and faster decay kinetics than existing organic scintillators. These respective attributes are of critical importance for improving the gamma-rejection capabilities and increasing the neutron discrimination performance under high-rate conditions. Two key applications that will benefit from these improvements include large-volume passive detection scenarios as well as active interrogation search for special nuclear materials. Molecular design principles were employed throughout this work, resulting in synthetically tailored materials that possess the targeted scintillation properties.

  16. Scintillation of rare earth doped fluoride nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jacobsohn, L. G.; McPherson, C. L.; Sprinkle, K. B.; Ballato, J. [Center for Optical Materials Science and Engineering Technologies (COMSET), and School of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634 (United States); Yukihara, E. G. [Physics Department, Oklahoma State University, Stillwater, Oklahoma 74078-3072 (United States); DeVol, T. A. [Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, South Carolina 29634-0905 (United States)

    2011-09-12

    The scintillation response of rare earth (RE) doped core/undoped (multi-)shell fluoride nanoparticles was investigated under x-ray and alpha particle irradiation. A significant enhancement of the scintillation response was observed with increasing shells due: (i) to the passivation of surface quenching defects together with the activation of the REs on the surface of the core nanoparticle after the growth of a shell, and (ii) to the increase of the volume of the nanoparticles. These results are expected to reflect a general aspect of the scintillation process in nanoparticles, and to impact radiation sensing technologies that make use of nanoparticles.

  17. Scintillation camera with second order resolution

    International Nuclear Information System (INIS)

    Muehllehner, G.

    1976-01-01

    A scintillation camera for use in radioisotope imaging to determine the concentration of radionuclides in a two-dimensional area is described in which means is provided for second order positional resolution. The phototubes, which normally provide only a single order of resolution, are modified to provide second order positional resolution of radiation within an object positioned for viewing by the scintillation camera. The phototubes are modified in that multiple anodes are provided to receive signals from the photocathode in a manner such that each anode is particularly responsive to photoemissions from a limited portion of the photocathode. Resolution of radioactive events appearing as an output of this scintillation camera is thereby improved

  18. POLARIS: Portable Liquid Argon Imaging Scintillator

    Science.gov (United States)

    Jia, Yanyu; Kovacs, Benjamin; Kamp, Nicholas; Aidala, Christine; Polaris Team

    2017-09-01

    Liquefied noble gas detectors have become widely used in nuclear and particle physics, in particular for detecting neutrinos and in dark matter searches. However, their potential for neutron detection in low-energy nuclear physics has not yet been realized. The University of Michigan has been constructing a hybrid scintillating time projection chamber for detection of neutrons in the 200 keV 10 MeV range. The scintillation material is argon, and various dopants to improve detector efficiency are being explored. With collection of both scintillation light and ionization charge, improved energy resolution for neutrons is expected compared to existing measurement techniques.

  19. Scintillation particle detection based on microfluidics

    CERN Document Server

    Mapelli, A; Renaud, P; Gorini, B; Trivino, N Vico; Jiguet, S; Vandelli, W; Haguenauer, M

    2010-01-01

    A novel type of particle detector based on scintillation, with precise spatial resolution and high radiation hardness, is being studied. It consists of a single microfluidic channel filled with a liquid scintillator and is designed to define an array of scintillating waveguides each independently coupled to a photodetector. Prototype detectors built using an SU-8 epoxy resin have been tested with electrons from a radioactive source. The experimental results show a light yield compatible with the theoretical expectations and confirm the validity of the approach. (C) 2010 Elsevier B.V. All rights reserved.

  20. Scintillation counter: photomultiplier tube alignment

    International Nuclear Information System (INIS)

    Olson, R.E.

    1975-01-01

    A scintillation counter, particularly for counting gamma ray photons, includes a massive lead radiation shield surrounding a sample-receiving zone. The shield is disassembleable into a plurality of segments to allow facile installation and removal of a photomultiplier tube assembly, the segments being so constructed as to prevent straight-line access of external radiation through the shield into the sample receiving zone. Provisions are made for accurately aligning the photomultiplier tube with respect to one or more sample-transmitting bores extending through the shield to the sample receiving zone. A sample elevator, used in transporting samples into the zone, is designed to provide a maximum gamma-receiving aspect to maximize the gamma detecting efficiency. (auth)

  1. Scintillation counter, maximum gamma aspect

    International Nuclear Information System (INIS)

    Thumim, A.D.

    1975-01-01

    A scintillation counter, particularly for counting gamma ray photons, includes a massive lead radiation shield surrounding a sample-receiving zone. The shield is disassembleable into a plurality of segments to allow facile installation and removal of a photomultiplier tube assembly, the segments being so constructed as to prevent straight-line access of external radiation through the shield into radiation-responsive areas. Provisions are made for accurately aligning the photomultiplier tube with respect to one or more sample-transmitting bores extending through the shield to the sample receiving zone. A sample elevator, used in transporting samples into the zone, is designed to provide a maximum gamma-receiving aspect to maximize the gamma detecting efficiency. (U.S.)

  2. Chemical and colour quenching in liquid scintillation counting

    International Nuclear Information System (INIS)

    Grau Malonda, A.; Scott Guilleard, P.E.

    1986-01-01

    Chemical and colour quenching for H-3 and C-14 was studied. The method includes spectral analysis of colouring agents; methyl red (4'-dimethylamine-azobenzene 2-carboxilic acid) dimethyl yellow (4'-dimethylamine-azobenzene) and melachite green (metane, bis (4'-dimethyl aminophenyl)-(phenyl)). External standard channels ratio was applied for the liquid scintillation counting of samples. The introduction of an isolated external standard seems to be a strong tool for the correction of chemical and colour quenching curves. (author). 10 figs., 12 refs

  3. A study of multi-GNSS ionospheric scintillation and cycle-slip over Hong Kong region for moderate solar flux conditions

    Science.gov (United States)

    Luo, Xiaomin; Liu, Zhizhao; Lou, Yidong; Gu, Shengfeng; Chen, Biyan

    2017-09-01

    This study presents the characteristics of Multiple Global Navigation Satellite System (Multi-GNSS) ionospheric scintillation and cycle-slip occurrence through the analysis of Multi-GNSS data collected by a newly installed receiver located at Sha Tin of Hong Kong from 6 October 2015 to 31 December 2016. This period of time was under a moderate solar activity condition with average sunspot number and F10.7 as 44 and 92, respectively. Considering the frequent occurrence of loss of lock in satellites measurements in the presence of ionospheric scintillation, a rate of geometry-free (ROGF) combination is proposed to take the time gap size between two data arcs into account in the cycle-slip detection. The results show that most ionospheric scintillation events and cycle-slips are observed from 20:00 LT to 0:00 LT. Under the strong scintillation (S4 > 0.6) conditions, it is found that the time series of wide-land (WL) ambiguity NWL and ROGF vary significantly and their range can reach more than 50 cycles and 0.1 m/s, respectively. However, the variations of the NWL and ROGF are generally small under weak scintillation (0.2 < S4 ≤ 0.6) or non-scintillation (S4 ≤ 0.2) conditions. A strong correlation of scintillation and cycle-slip occurrence is also verified by the daily and spatial statistics results. In addition, it is found that on average every 1000 strong scintillation events can result in 200, 124, and 171 cycle-slip occurrences in GPS, GLONASS, and BDS, respectively, whereas these values are 7, 12, and 12 per 1000 under weak scintillation conditions. This study suggests that cautions be taken when GNSS measurements are contaminated by the strong ionospheric scintillation in GNSS applications such as real-time kinematic (RTK) and precise point positioning (PPP).

  4. Quantum-fluid-dynamics approach for strong-field processes: Application to the study of multiphoton ionization and high-order harmonic generation of He and Ne atoms in intense laser fields

    International Nuclear Information System (INIS)

    Roy, Amlan K.; Chu, Shih-I

    2002-01-01

    We explore the feasibility of extending the quantum-fluid dynamics (QFD) approach for quantitative investigation of nonlinear optical processes of many-electron quantum systems in intense laser fields. Through the amalgamation of the QFD and density-functional theory (DFT), a single time-dependent hydrodynamical equation of motion can be derived. This equation has the form of a generalized nonlinear Schroedinger equation (GNLSE) but includes the many-body effects through a local time-dependent exchange-correlation potential. The time-dependent generalized pseudospectral method is extended to the solution of the GNLSE in spherical coordinates, allowing nonuniform spatial discretization and efficient, accurate solution of the hydrodynamical density and wave function in space and time. The procedure is applied to the study of multiphoton ionization (MPI) and high-order harmonic generation (HHG) of He and Ne atoms in intense laser fields. Excellent agreement with other recent self-interaction-free time-dependent DFT calculations is obtained for He, while for Ne, good agreement is achieved. Four different exchange-correlation energy functionals are used in the study with an aim to explore the roles of exchange and correlation on MPI/HHG processes in details. The method offers a conceptually appealing and computationally practical approach for nonperturbative treatment of strong-field processes of many-electron systems beyond the time-dependent Hartree-Fock level

  5. Quantum-fluid-dynamics approach for strong-field processes: Application to the study of multiphoton ionization and high-order harmonic generation of He and Ne atoms in intense laser fields

    Science.gov (United States)

    Roy, Amlan K.; Chu, Shih-I.

    2002-04-01

    We explore the feasibility of extending the quantum-fluid dynamics (QFD) approach for quantitative investigation of nonlinear optical processes of many-electron quantum systems in intense laser fields. Through the amalgamation of the QFD and density-functional theory (DFT), a single time-dependent hydrodynamical equation of motion can be derived. This equation has the form of a generalized nonlinear Schrödinger equation (GNLSE) but includes the many-body effects through a local time-dependent exchange-correlation potential. The time-dependent generalized pseudospectral method is extended to the solution of the GNLSE in spherical coordinates, allowing nonuniform spatial discretization and efficient, accurate solution of the hydrodynamical density and wave function in space and time. The procedure is applied to the study of multiphoton ionization (MPI) and high-order harmonic generation (HHG) of He and Ne atoms in intense laser fields. Excellent agreement with other recent self-interaction-free time-dependent DFT calculations is obtained for He, while for Ne, good agreement is achieved. Four different exchange-correlation energy functionals are used in the study with an aim to explore the roles of exchange and correlation on MPI/HHG processes in details. The method offers a conceptually appealing and computationally practical approach for nonperturbative treatment of strong-field processes of many-electron systems beyond the time-dependent Hartree-Fock level.

  6. Monte Carlo simulations and measurements for efficiency determination of lead shielded plastic scintillator detectors

    Science.gov (United States)

    Yasin, Zafar; Negoita, Florin; Tabbassum, Sana; Borcea, Ruxandra; Kisyov, Stanimir

    2017-12-01

    The plastic scintillators are used in different areas of science and technology. One of the use of these scintillator detectors is as beam loss monitors (BLM) for new generation of high intensity heavy ion in superconducting linear accelerators. Operated in pulse counting mode with rather high thresholds and shielded by few centimeters of lead in order to cope with radiofrequency noise and X-ray background emitted by accelerator cavities, they preserve high efficiency for high energy gamma ray and neutrons produced in the nuclear reactions of lost beam particles with accelerator components. Efficiency calculation and calibration of detectors is very important before their practical usage. In the present work, the efficiency of plastic scintillator detectors is simulated using FLUKA for different gamma and neutron sources like, 60Co, 137Cs and 238Pu-Be. The sources are placed at different positions around the detector. Calculated values are compared with the measured values and a reasonable agreement is observed.

  7. Radiation damage studies on the optical and mechanical properties of plastic scintillators

    International Nuclear Information System (INIS)

    Mizue Hamada, Margarida; Roberto Rela, Paulo; Eduardo da Costa, Fabio; Henrique de Mesquita, Carlos

    1999-01-01

    This paper describes the radiation damage studies on a large volume plastic scintillator based in polystyrene doped with PPO and POPOP. The consequences on their mechanical and scintillation properties were evaluated before and after irradiation with different dose rates of 60 Co gamma radiation, in several doses. The optical results show a significant difference in the radiation susceptibility, when the plastic scintillator is irradiated at low rate (0.1 kGy/h) with that irradiated at high dose rate (85 kGy/h). The losses in the optical and mechanical properties increase as the irradiation dose is increased. The damage evaluated by the transmittance, emission intensity, pulse height and tensile strength was normalized as a damage fraction and fitted by a bi-exponential function. It was observed that the damage for irradiation is not permanent and it obeys a bi-exponential function

  8. Neutron-gamma discrimination based on pulse shape discrimination in a Ce:LiCaAlF6 scintillator

    International Nuclear Information System (INIS)

    Yamazaki, Atsushi; Watanabe, Kenichi; Uritani, Akira; Iguchi, Tetsuo; Kawaguchi, Noriaki; Yanagida, Takayuki; Fujimoto, Yutaka; Yokota, Yuui; Kamada, Kei; Fukuda, Kentaro; Suyama, Toshihisa; Yoshikawa, Akira

    2011-01-01

    We demonstrate neutron-gamma discrimination based on a pulse shape discrimination method in a Ce:LiCAF scintillator. We have tried neutron-gamma discrimination using a difference in the pulse shape or the decay time of the scintillation light pulse. The decay time is converted into the rise time through an integrating circuit. A 252 Cf enclosed in a polyethylene container is used as the source of thermal neutrons and prompt gamma-rays. Obvious separation of neutron and gamma-ray events is achieved using the information of the rise time of the scintillation light pulse. In the separated neutron spectrum, the gamma-ray events are effectively suppressed with little loss of neutron events. The pulse shape discrimination is confirmed to be useful to detect neutrons with the Ce:LiCAF scintillator under an intense high-energy gamma-ray condition.

  9. Neutron-gamma discrimination based on pulse shape discrimination in a Ce:LiCaAlF{sub 6} scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Yamazaki, Atsushi, E-mail: a-yamazaki@nucl.nagoya-u.ac.jp [Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University (Japan); Watanabe, Kenichi; Uritani, Akira [Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University (Japan); Iguchi, Tetsuo [Department of Quantum Engineering, Graduate School of Engineering, Nagoya University (Japan); Kawaguchi, Noriaki [Tokuyama Corporation (Japan); Yanagida, Takayuki; Fujimoto, Yutaka; Yokota, Yuui; Kamada, Kei [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University (Japan); Fukuda, Kentaro; Suyama, Toshihisa [Tokuyama Corporation (Japan); Yoshikawa, Akira [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University (Japan)

    2011-10-01

    We demonstrate neutron-gamma discrimination based on a pulse shape discrimination method in a Ce:LiCAF scintillator. We have tried neutron-gamma discrimination using a difference in the pulse shape or the decay time of the scintillation light pulse. The decay time is converted into the rise time through an integrating circuit. A {sup 252}Cf enclosed in a polyethylene container is used as the source of thermal neutrons and prompt gamma-rays. Obvious separation of neutron and gamma-ray events is achieved using the information of the rise time of the scintillation light pulse. In the separated neutron spectrum, the gamma-ray events are effectively suppressed with little loss of neutron events. The pulse shape discrimination is confirmed to be useful to detect neutrons with the Ce:LiCAF scintillator under an intense high-energy gamma-ray condition.

  10. GEM scintillation readout with avalanche photodiodes

    CERN Document Server

    Conceição, A S; Fernandes, L M P; Monteiro, C M B; Coelho, L C C; Azevedo, C D R; Veloso, J F C A; Lopesac, J A M; dos Santosa, J M F

    2007-01-01

    The use of the scintillation produced in the charge avalanches in GEM holes as signal amplification and readout is investigated for xenon. A VUV-sensitive avalanche photodiode has been used as photosensor. Detector gains of about 4 × 104 are achieved in scintillation readout mode, for GEM voltages of 490 V and for a photosensor gain of 150. Those gains are more than one order of magnitude larger than what is obtained using charge readout. In addition, the energy resolutions achieved with the scintillation readout are lower than those achieved with charge readout. The GEM scintillation yield in xenon was measured as a function of GEM voltage, presenting values that are about a half of those achieved for the charge yield, and reach about 730 photons per primary electron at GEM voltages of 490 V.

  11. High-efficiency organic glass scintillators

    Science.gov (United States)

    Feng, Patrick L.; Carlson, Joseph S.

    2017-12-19

    A new family of neutron/gamma discriminating scintillators is disclosed that comprises stable organic glasses that may be melt-cast into transparent monoliths. These materials have been shown to provide light yields greater than solution-grown trans-stilbene crystals and efficient PSD capabilities when combined with 0.01 to 0.05% by weight of the total composition of a wavelength-shifting fluorophore. Photoluminescence measurements reveal fluorescence quantum yields that are 2 to 5 times greater than conventional plastic or liquid scintillator matrices, which accounts for the superior light yield of these glasses. The unique combination of high scintillation light-yields, efficient neutron/gamma PSD, and straightforward scale-up via melt-casting distinguishes the developed organic glasses from existing scintillators.

  12. Cementation of radioactive liquid scintillator waste simulate

    International Nuclear Information System (INIS)

    Bayoumi, T.A.

    2010-01-01

    Liquid scintillation counting is an important analytical tool with extensive applications in medicine and basic applied research and used in quantification of □ -particles, weak □ and x-rays. The generated spent liquid scintillator radioactive waste should be limited and controlled to protect man and his environment. In this study, the radioactive spent liquid scintillator waste simulate (SLS) was immobilized in cement matrix using a surfactant in order to facilitate and increase the amount of SLS incorporated into the cementitious materials. Mechanical properties of the final cement waste form were acceptable for blocks containing up to 20% SLS in presence of surfactant. X-ray diffraction, IR analysis and scanning electron microscope proved that the hydration of cement materials is not significantly affected by organic scintillator waste. Therefore, the cement matrix could be recommended for solidification of SLS for the acceptable mechanical, physical and chemical characterizations reached.

  13. Liquid scintillators for optical fiber applications

    International Nuclear Information System (INIS)

    Franks, L.A.; Lutz, S.S.

    1982-01-01

    A multicomponent liquid scintillator solution for use as a radiation-to-light converter in conjunction with a fiber optic transmission system. The scintillator includes a quantity of 1, 2 , 4, 5, 3H, 6H, 1 OH, tetrahydro-8-trifluoromethyl (1) benzopyrano (9, 9a, 1-gh) quinolizin-10-one (Coumarin) as a solute in a fluor solvent such as benzyl alcohol or pseudocumene. The use of bibuq as an additional or primary solute is also disclosed

  14. Composition for use in scintillator systems

    International Nuclear Information System (INIS)

    Tarkkanen, V.

    1976-01-01

    A liquid scintillation counting composition of the type comprising an aromatic hydrocarbon solvent, an ethoxylated alkyl phenol surfactant, and a scintillation solute, containing a small amount of a substituted ethoxylated carboxylate acid and/or a tertiary amine salt or a quaternary ammonium salt of such acid is described. The free acid reduces chemiluminescence upon the addition of an alkaline sample to the composition, while the tertiary amine or quaternary ammonium salt enhances the water miscibility of the composition

  15. Real-time volumetric scintillation dosimetry

    Science.gov (United States)

    Beddar, S.

    2015-01-01

    The goal of this brief review is to review the current status of real-time 3D scintillation dosimetry and what has been done so far in this area. The basic concept is to use a large volume of a scintillator material (liquid or solid) to measure or image the dose distributions from external radiation therapy (RT) beams in three dimensions. In this configuration, the scintillator material fulfills the dual role of being the detector and the phantom material in which the measurements are being performed. In this case, dose perturbations caused by the introduction of a detector within a phantom will not be at issue. All the detector configurations that have been conceived to date used a Charge-Coupled Device (CCD) camera to measure the light produced within the scintillator. In order to accurately measure the scintillation light, one must correct for various optical artefacts that arise as the light propagates from the scintillating centers through the optical chain to the CCD chip. Quenching, defined in its simplest form as a nonlinear response to high-linear energy transfer (LET) charged particles, is one of the disadvantages when such systems are used to measure the absorbed dose from high-LET particles such protons. However, correction methods that restore the linear dose response through the whole proton range have been proven to be effective for both liquid and plastic scintillators. Volumetric scintillation dosimetry has the potential to provide fast, high-resolution and accurate 3D imaging of RT dose distributions. Further research is warranted to optimize the necessary image reconstruction methods and optical corrections needed to achieve its full potential.

  16. Elastic scintillation materials based on polyorganosiloxane

    International Nuclear Information System (INIS)

    Grinev, B.V.; Andryushchenko, L.A.; Shershukov, V.M.; Ulanenko, K.B.; Minakova, R.A.; Sevastjanova, I.V.

    1994-01-01

    The developed elastic scintillators based on polymethyl-phenylsiloxane rubber are characterized by an elevated light output and a low toxicity. The increase of their light output is achieved by raising the content of phenyl chains, varying the chemical structure of luminescent additions and using isopropylnaphthalene. This high-boiling solvent introduced into the scintillation siloxane compositions is confined within siloxane matrix after the hardening of the rubber

  17. Scintillation response of nuclear particle detectors

    International Nuclear Information System (INIS)

    Michaelian, K.; Menchaca-Rocha, A.; Belmont-Moreno, E.

    1995-01-01

    We derive simple algebraic expressions for the ion-induced light output response of most of the popular scintillation detectors used in nuclear and particle physics. The analytical calculation is based on a model for the energy deposition by secondary electrons scattered along the track of the ion, and the subsequent energy transport to luminescence centers. Predictions are compared with published experimental data for various scintillating materials over a wide range of incident ions and energies. ((orig.))

  18. Spectrometric characteristics of polystyrene scintillation films

    CERN Document Server

    Astvatsaturov, A R; Gavalyan, V B; Gavalyan, V G

    1999-01-01

    The spectrometric characteristics of five types of polystyrene scintillation films with thicknesses of 10, 30, 50 and 80 mu m and of analogous 250 mu m thick plates irradiated with sup 2 sup 3 sup 9 Pu, sup 2 sup 3 sup 8 Pu and sup 2 sup 2 sup 6 Ra sources of alpha-particles have been studied. The prospects of utilization of scintillation films as radiators for detection of heavy charged particles and measurement of their energy was experimentally shown.

  19. A new technique for infrared scintillation measurements

    OpenAIRE

    Chiossi, F.; Brylew, K.; Borghesani, A. F.; Braggio, C.; Carugno, G.; Drozdowski, W.; Guarise, M.

    2016-01-01

    We propose a new technique to measure the infrared scintillation light yield of rare earth (RE) doped crystals by comparing it to near UV-visible scintillation of a calibrated Pr:(Lu$_{0.75}$Y$_{0.25}$)$_{3}$Al$_5$O$_{12}$ sample. As an example, we apply this technique to provide the light yield in visible and infrared range up to \\SI{1700}{nm} of this crystal.

  20. A new technique for infrared scintillation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Chiossi, F., E-mail: federico.chiossi@studenti.unipd.it [Dip. di Fisica e Astronomia and INFN, University of Padua, Via F. Marzolo 8, I-35131 Padova (Italy); Brylew, K. [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Borghesani, A.F. [CNISM Unit and Dip. di Fisica e Astronomia, University of Padua, Via F. Marzolo 8, I-35131 Padova (Italy); Braggio, C.; Carugno, G. [Dip. di Fisica e Astronomia and INFN, University of Padua, Via F. Marzolo 8, I-35131 Padova (Italy); Drozdowski, W. [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Guarise, M. [Dip. di Fisica e Astronomia and INFN, University of Padua, Via F. Marzolo 8, I-35131 Padova (Italy)

    2017-05-21

    We propose a new technique to measure the infrared scintillation light yield of rare earth doped crystals by comparing it to near UV–visible scintillation of a calibrated Pr:(Lu{sub 0.75}Y{sub 0.25}){sub 3}Al{sub 5}O{sub 12} sample. As an example, we apply this technique to provide the light yield in visible and infrared range up to 1700 nm of this crystal.

  1. New Opportunities for Remote Sensing Ionospheric Irregularities by Fitting Scintillation Spectra

    Science.gov (United States)

    Carrano, C. S.; Rino, C. L.; Groves, K. M.

    2017-12-01

    In a recent paper, we presented a phase screen theory for the spectrum of intensity scintillations when the refractive index irregularities follow a two-component power law [Carrano and Rino, DOI: 10.1002/2015RS005903]. More recently we have investigated the inverse problem, whereby phase screen parameters are inferred from scintillation time series. This is accomplished by fitting the spectrum of intensity fluctuations with a parametrized theoretical model using Maximum Likelihood (ML) methods. The Markov-Chain Monte-Carlo technique provides a-posteriori errors and confidence intervals. The Akaike Information Criterion (AIC) provides justification for the use of one- or two-component irregularity models. We refer to this fitting as Irregularity Parameter Estimation (IPE) since it provides a statistical description of the irregularities from the scintillations they produce. In this talk, we explore some new opportunities for remote sensing ionospheric irregularities afforded by IPE. Statistical characterization of irregularities and the plasma bubbles in which they are embedded provides insight into the development of the underlying instability. In a companion paper by Rino et al., IPE is used to interpret scintillation due to simulated EPB structure. IPE can be used to reconcile multi-frequency scintillation observations and to construct high fidelity scintillation simulation tools. In space-to-ground propagation scenarios, for which an estimate of the distance to the scattering region is available a-priori, IPE enables retrieval of zonal irregularity drift. In radio occultation scenarios, the distance to the irregularities is generally unknown but IPE enables retrieval of Fresnel frequency. A geometric model for the effective scan velocity maps Fresnel frequency to Fresnel scale, yielding the distance to the irregularities. We demonstrate this approach by geolocating irregularities observed by the CORISS instrument onboard the C/NOFS satellite.

  2. New Developments in Scintillators for Security Applications

    Science.gov (United States)

    Glodo, Jarek; Wang, Yimin; Shawgo, Ryan; Brecher, Charles; Hawrami, Rastgo H.; Tower, Joshua; Shah, Kanai S.

    Radiation is an important part of security space: It is detected either passively in search of special nuclear materials or actively to monitor or interrogate objects of interest. Systems relying on radiation require adequate detectors. The most common radiation detectors are based on scintillating materials that convert hard (gamma, x-ray or neutron) radiation into visible light registered by a photodetector. The last decade has seen development of new materials driven by various security applications. This included the search for He-3 replacement technologies, which resulted in development of neutron sensing scintillators such as Ce-doped Cs2LiYCl6 (CLYC) or more recently Cs2LiLa(Br,Cl)6 (CLLBC). Since they are also good gamma-ray scintillators, they have also penetrated the detection market for passive dual-mode (gamma and neutron) detection systems, replacing scintillators such as NaI(Tl) or CsI(Tl) and competing with LaBr3(Ce). High-energy Non-Intrusive Inspection is another area where active research is being pursued in order to replace existing scintillator choices such as CdWO4, which is commonly used in simple radiography, and PbWO4, which is being studied for spectroscopic alternatives to radiography. For radiography, in particular, new ceramic scintillators such as Ce-doped GLuGAG (garnet) are considered, and for spectroscopy, Yb doped Lu2O3. In this paper we provide a short overview of these technologies.

  3. Survey meter using novel inorganic scintillators

    International Nuclear Information System (INIS)

    Yoshikawa, Akira; Fukuda, Kentaro; Kawaguchi, Noriaki; Kamada, Kei; Fujimoto, Yutaka; Yokota, Yuui; Kurosawa, Shunsuke; Yanagida, Takayuki

    2012-01-01

    Single crystal scintillator materials are widely used for detection of high-energy photons and particles. There is continuous demand for new scintillator materials with higher performance because of increasing number of medical, industrial, security and other applications. This article presents the recent development of three novel inorganic scintillators; Pr-doped Lu 3 Al 5 O 12 (Pr:LuAG), Ce doped Gd 3 (Al, Ga) 5 O 12 (Ce:GAGG) and Ce or Eu-doped 6 LiCaAlF 6 (Ce:LiCAF, Eu:LiCAF). Pr:LuAG shows very interesting scintillation properties including very fast decay time, high light yield and excellent energy resolution. Taking the advantage of these properties, positron emission mammography (PEM) equipped with Pr:LuAG were developed. Ce:GAGG shows very high light yield, which is much higher than that of Ce:LYSO. Survey meter using Ce:GAGG is developed using this scintillator. Ce:LiCAF and Eu:LiCAF were developed for neutron detection. The advantage and disadvantage are discussed comparing with halide scintillators. Eu-doped LiCAF indicated five times higher light yield than that of existing Li-glass. It is expected to be used as the alternative of 3 He. (author)

  4. Removal of ring artifacts in microtomography by characterization of scintillator variations.

    Science.gov (United States)

    Vågberg, William; Larsson, Jakob C; Hertz, Hans M

    2017-09-18

    Ring artifacts reduce image quality in tomography, and arise from faulty detector calibration. In microtomography, we have identified that ring artifacts can arise due to high-spatial frequency variations in the scintillator thickness. Such variations are normally removed by a flat-field correction. However, as the spectrum changes, e.g. due to beam hardening, the detector response varies non-uniformly introducing ring artifacts that persist after flat-field correction. In this paper, we present a method to correct for ring artifacts from variations in scintillator thickness by using a simple method to characterize the local scintillator response. The method addresses the actual physical cause of the ring artifacts, in contrary to many other ring artifact removal methods which rely only on image post-processing. By applying the technique to an experimental phantom tomography, we show that ring artifacts are strongly reduced compared to only making a flat-field correction.

  5. Further understanding of PbWO4 Scintillator characteristics and their optimisation. LUMEN activity in 1998

    CERN Document Server

    Baccaro, Stefania; Borgia, Bruno; Cecilia, Angelica; Dafinei, Ioan; Diemoz, Marcella; Fabeni, P; Festinesi, Armando; Longo, Egidio; Martini, M; Meinardi, F; Mihoková, E; Montecchi, Marco; Nikl, M; Pazzi, G P; Rosa, J; Sulc, Miroslav

    2000-01-01

    The aim of LUMEN collaboration was the investigation on single crystals of PbWO4 ( PWO): the results performed up to now provide the evidence of the possibility to optimise the optical properties of an intrinsic scintillator such as PWO. The control of essential requirements in the crystal preparation ( raw material purity, growing methods and post-growth annealing) as well as the introduction of selected dopants at suitable concentrations ( particularly trivalent and pentavalent ions) were found to be very successful in lowering the concentration of point defects in the lattice which strongly affect scintillation properties and radiation hardness. The systematic investigation effort to better understand the scintillation characteristics and to improve the quality of PWO crystals is due to their use for the CMS electromagnetic calorimeter.

  6. Study of a scintillating fiber-plane detector

    International Nuclear Information System (INIS)

    Box, P.; Kiener, J.; Bimbot, R.; Gardes, D.; Chabot, M.

    1995-01-01

    A study of a position sensitive detector consisting of a scintillating fiber plane, has been performed in the framework of a European collaboration. The detector will operate in the 'high intensity' experimental area at the SIS storage ring. The basic goal of these experiments is to measure energy losses of heavy ions in a high-density plasma environment. The plasmas will be created by the impact of high intensity energetic beams. The investigation of the stopping power of heavy ions in a dense plasma environment is developed in order to design the geometry of the converters which must be used for converting heavy ion beam energy into thermal X-rays (indirect process). This physics of beam-plasma interactions is a key issue for the inertial fusion program. (R.P.) 4 refs.; 8 figs.; 3 tabs

  7. A method for scintillation characterization using geodetic receivers operating at 1 Hz

    Science.gov (United States)

    Juan, J. M.; Aragon-Angel, A.; Sanz, J.; González-Casado, G.; Rovira-Garcia, A.

    2017-11-01

    Ionospheric scintillation produces strong disruptive effects on global navigation satellite system (GNSS) signals, ranging from degrading performances to rendering these signals useless for accurate navigation. The current paper presents a novel approach to detect scintillation on the GNSS signals based on its effect on the ionospheric-free combination of carrier phases, i.e. the standard combination of measurements used in precise point positioning (PPP). The method is implemented using actual data, thereby having both its feasibility and its usefulness assessed at the same time. The results identify the main effects of scintillation, which consist of an increased level of noise in the ionospheric-free combination of measurements and the introduction of cycle-slips into the signals. Also discussed is how mis-detected cycle-slips contaminate the rate of change of the total electron content index (ROTI) values, which is especially important for low-latitude receivers. By considering the effect of single jumps in the individual frequencies, the proposed method is able to isolate, over the combined signal, the frequency experiencing the cycle-slip. Moreover, because of the use of the ionospheric-free combination, the method captures the diffractive nature of the scintillation phenomena that, in the end, is the relevant effect on PPP. Finally, a new scintillation index is introduced that is associated with the degradation of the performance in navigation.

  8. The MASIV Survey - IV. Relationship between intra-day scintillation and intrinsic variability of radio AGNs

    Science.gov (United States)

    Koay, J. Y.; Macquart, J.-P.; Jauncey, D. L.; Pursimo, T.; Giroletti, M.; Bignall, H. E.; Lovell, J. E. J.; Rickett, B. J.; Kedziora-Chudczer, L.; Ojha, R.; Reynolds, C.

    2018-03-01

    We investigate the relationship between 5 GHz interstellar scintillation (ISS) and 15 GHz intrinsic variability of compact, radio-selected active galactic nuclei (AGNs) drawn from the Microarcsecond Scintillation-Induced Variability (MASIV) Survey and the Owens Valley Radio Observatory blazar monitoring program. We discover that the strongest scintillators at 5 GHz (modulation index, m5 ≥ 0.02) all exhibit strong 15 GHz intrinsic variability (m15 ≥ 0.1). This relationship can be attributed mainly to the mutual dependence of intrinsic variability and ISS amplitudes on radio core compactness at ˜ 100 μas scales, and to a lesser extent, on their mutual dependences on source flux density, arcsec-scale core dominance and redshift. However, not all sources displaying strong intrinsic variations show high amplitude scintillation, since ISS is also strongly dependent on Galactic line-of-sight scattering properties. This observed relationship between intrinsic variability and ISS highlights the importance of optimizing the observing frequency, cadence, timespan and sky coverage of future radio variability surveys, such that these two effects can be better distinguished to study the underlying physics. For the full MASIV sample, we find that Fermi-detected gamma-ray loud sources exhibit significantly higher 5 GHz ISS amplitudes than gamma-ray quiet sources. This relationship is weaker than the known correlation between gamma-ray loudness and the 15 GHz variability amplitudes, most likely due to jet opacity effects.

  9. Conference on Engineering of Scintillation Materials and Radiation Technologies

    CERN Document Server

    Gektin, Alexander

    2017-01-01

    This volume provides a broad overview of the latest achievements in scintillator development, from theory to applications, and aiming for a deeper understanding of fundamental processes, as well as the discovery and availability of components for the production of new generations of scintillation materials. It includes papers on the microtheory of scintillation and the initial phase of luminescence development, applications of the various materials, and development and characterization of ionizing radiation detection equipment. The book also touches upon the increased demand for cryogenic scintillators, the renaissance of  garnet materials for scintillator applications, nano-structuring in scintillator development, development and applications for security, and exploration of hydrocarbons and ecological monitoring.

  10. Aspects of scintillation modelling in LEO-ground free-space optical communications

    Science.gov (United States)

    Moll, Florian

    2017-10-01

    Free-space optical communications can be used to transmit data from low Earth orbit satellites to ground with very high data rate. In the last section of the downlink, the electro-magnetic wave propagates through the turbulent atmosphere which is characterized by random index of refraction fluctuations. The propagating wave experiences phase distortions that lead to intensity scintillation in the aperture plane of the receiving telescope. For quantification, an appropriate scintillation model is needed. Approaches to analytically model the scintillation exist. Parameterization of the underlying turbulence profile (Cn2 profile) is however difficult. The Cn2 profiles are often site-specific and thus inappropriate or generic and thus too complex for a feasible deployment. An approach that directly models the scintillation effect based on measurements without claiming to be generic is therefore more feasible. Since measurements are sparse, a combination with existing theoretical framework is feasible to develop a new scintillation model that focuses on low earth orbit to ground free-space optical communications link design with direct detection. The paper addresses several questions one has to answer while analyzing the measurements data and selection of the theoretical models for the LEO downlink scenario. The first is the question of a suitable yet ease to use simple Cn2 profile. The HAP model is analyzed for its feasibility in this scenario since it includes a more realistic boundary layer profile decay than the HV model. It is found that the HAP model needs to be modified for a feasible deployment in the LEO downlink scenario for night time. The validity of the plane wave assumption in the downlink is discussed by model calculations of the scintillation index for a plane and Gaussian beam wave. Inaccuracies when using the plane earth model instead of the spherical earth model are investigated by analyzing the Rytov index. Impact of beam wander and non

  11. Emission properties of Ce-doped alkaline earth borate glasses for scintillator applications

    Science.gov (United States)

    Torimoto, Aya; Masai, Hirokazu; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

    2017-11-01

    We investigate the photoluminescence (PL) and X-ray-induced luminescence properties of 0.1 mol% Ce-doped MO-B2O3 (M = Ca, Sr, and Ba) glasses. We also determine the Ce3+/(Ce3++Ce4+) ratio by X-ray absorption near-edge structure analyses. The emission intensities of PL, X-ray scintillation, and thermally stimulated luminescence (TSL) depend on the host glass composition. The order of the PL intensity from highest to lowest is as follows: Ca-substituted glass, Ba-substituted glass, and Sr-substituted glass. Our results suggest that the optical absorption edge and quantum yield (QY) are influenced by the local coordination state of Ce3+, which, in turn, is likely to be affected by the optical basicity. The order of the X-ray scintillation intensity from highest to lowest is reverse of that of the PL intensity. This is probably because the interaction probability of X-rays with matter depends on the effective atomic number of the material and the effective atomic number has a stronger influence on the scintillation intensity than does the QY. Though the TSL glow curves reveal that the density and energy depth of the trap sites depend on the substituted alkaline earth oxides, we are unable to correlate the electron spin resonance (ESR) spectra with the TSL results. Therefore, it is considered that the ESR active sites are not responsible for the TSL in these systems.

  12. Direct photon-counting scintillation detector readout using an SSPM

    International Nuclear Information System (INIS)

    Stapels, Christopher J.; Squillante, Michael R.; Lawrence, William G.; Augustine, Frank L.; Christian, James F.

    2007-01-01

    Gamma-ray detector technologies, capable of providing adequate energy information, use photomultiplier tubes (PMTs) or silicon avalanche photodiodes to detect the light pulse from a scintillation crystal. A new approach to detect the light from scintillation materials is to use an array of small photon counting detectors, or a 'detector-on-a-chip' based on a novel 'Solid-state Photomultiplier' (SSPM) concept. A CMOS SSPM coupled to a scintillation crystal uses an array of CMOS Geiger photodiode (GPD) pixels to collect light and produce a signal proportional to the energy of the radiation. Each pixel acts as a binary photon detector, but the summed output is an analog representation of the total photon intensity. We have successfully fabricated arrays of GPD pixels in a CMOS environment, which makes possible the production of miniaturized arrays integrated with the detector electronics in a small silicon chip. This detector technology allows for a substantial cost reduction while preserving the energy resolution needed for radiological measurements. In this work, we compare designs for the SSPM detector. One pixel design achieves maximum detection efficiency (DE) for 632-nm photons approaching 30% with a room temperature dark count rate (DCR) of less than 1 kHz for a 30-μm-diameter pixel. We characterize after pulsing and optical cross talk and discuss their effects on the performance of the SSPM. For 30-μm diameter, passively quenched CMOS GPD pixels, modeling suggests that a pixel spacing of approximately 90 μm optimizes the SSPM performance with respect to DE and cross talk

  13. Low-temperature relative reflectivity measurements of reflective and scintillating foils used in rare event searches

    Science.gov (United States)

    Langenkämper, A.; Ulrich, A.; Defay, X.; Feilitzsch, F. v.; Lanfranchi, J.-C.; Mondragón, E.; Münster, A.; Oppenheimer, C.; Potzel, W.; Roth, S.; Schönert, S.; Steiger, H.; Trinh Thi, H. H.; Wawoczny, S.; Willers, M.; Zöller, A.

    2018-03-01

    In this work we investigate the reflectivity of highly reflective multilayer polymer foils used in the CRESST experiment. The CRESST experiment searches directly for dark matter via operating scintillating CaWO4 crystals as targets for elastic dark matter-nucleon scattering. In order to suppress background events, the experiment employs the so-called phonon-light technique which is based on the simultaneous measurement of the heat signal in the main CaWO4 target crystal and of the emitted scintillation light with a separate cryogenic light detector. Both detectors are surrounded by a highly reflective and scintillating multilayer polymer foil to increase the light collection efficiency and to veto surface backgrounds. While this study is motivated by the CRESST experiment, the results are also relevant for other rare event searches using scintillating cryogenic bolometers in the field of the search of dark matter and neutrinoless double beta decay (0 νββ). In this work a dedicated experiment has been set up to determine the relative reflectivity at 300 K and 20 K of three multilayer foils ("VM2000", "VM2002", "Vikuiti") produced by the company 3M. The intensity of a light beam reflected off the foil is measured with a CCD camera. The ratio of the intensities at 300 K and 20 K corresponds to the relative reflectivity change. The measurements performed in this work show no variation of the reflectivity with temperature at a level of ∼1%.

  14. The Equatorial Scintillations and Space Weather Effects on its Generation during Geomagnetic Storms

    Science.gov (United States)

    Biktash, Lilia

    Great diversity of the ionospheric phenomena leads to a variety of irregularity types with spatial size from many thousands of kilometers to few centimeters and lifetimes from days to fractions of second. Since the ionosphere strongly influences the propagation of radio waves, signal distortions caused by these irregularities affect short-wave transmissions on Earth, transiono-spheric satellite communications and navigation. In this work the solar wind and the equatorial ionosphere parameters, Kp, Dst, AU, AL indices characterized contribution of different mag-netospheric and ionospheric currents to the H-component of geomagnetic field are examined to test the space weather effect on the generation of ionospheric irregularities producing VLF scintillations. According to the results of the current statistical studies, one can predict scintil-lations from Aarons' criteria using the Dst index, which mainly depicts the magnetospheric ring current field. To amplify Aarons' criteria or to propose new criteria for predicting scintillation characteristics is the question. In the present phase of the experimental investigations of elec-tron density irregularities in the ionosphere new ways are opened up because observations in the interaction between the solar wind -magnetosphere -ionosphere during magnetic storms have progressed greatly. We have examined scintillation relation to magnetospheric and ionospheric currents and show that the factor, which presents during magnetic storms to fully inhibit scin-tillation, is the positive Bz-component of the IMF. During the positive Bz IMF F layer cannot raise altitude where scintillations are formed. The auroral indices and Kp do better for the prediction of the ionospheric scintillations at the equator. The interplanetary magnetic field data and models can be used to explain the relationship between the equatorial ionospheric parameters, h'F, foF2, and the equatorial geomagnetic variations with the polar ionosphere cur-rents and

  15. Scintillation Detectors for Charged Particles and Photons

    CERN Document Server

    Lecoq, P

    2011-01-01

    Scintillation Detectors for Charged Particles and Photons in 'Charged Particle Detectors - 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 Subsection '3.1.1 Scintillation Detectors for Charged Particles and Photons' of Section '3.1 Charged Particle Detectors' of Chapter '3 Particle Detectors and Detector Systems' with the content: 3.1.1 Scintillation Detectors for Charged Particles and Photons 3.1.1.1 Basic detector principles and scintillator requirements 3.1.1.1.1 Interaction of ionizing radiation with scintillator material 3.1.1.1.2 Important scint...

  16. Calibration and monitoring of a scintillator HCAL with SiPMs CALICE scintillator HCAL

    International Nuclear Information System (INIS)

    Lucaci-Timoce, Angela

    2009-01-01

    The operational experience with a highly-granular analogue hadronic calorimeter (AHCAL) consisting of 7608 individual scintillator tiles readout via Silicon-Photo-multipliers (SiPM) is presented. The calibration of each cell is based on minimum ionizing particle signals for which in general a muon beam is used. In addition, a correction for the non-linearity introduced by the finite number of pixels (1156) in the SiPM is applied. The aspects of temperature and voltage dependence of SiPM are addressed, and monitoring and calibration procedures are discussed. Such procedures are essential for the extrapolation of calibration factors over several days of data taking with the calorimeter. For this purpose a versatile UV-LED light distribution system was developed, capable of delivering light to all tiles with intensity from a few photo-electrons to the saturation of the SiPM. The procedures are tested using data collected with the AHCAL at the CERN SPS test beam.

  17. Emulation workbench for position sensitive gaseous scintillation detectors

    International Nuclear Information System (INIS)

    Pereira, L.; Margato, L.M.S.; Morozov, A.; Solovov, V.; Fraga, F. A. F.

    2015-01-01

    Position sensitive detectors based on gaseous scintillation proportional counters with Anger-type readout are being used in several research areas such as neutron detection, search for dark matter and neutrinoless double beta decay. Design and optimization of such detectors are complex and time consuming tasks. Simulations, while being a powerful tool, strongly depend on the light transfer models and demand accurate knowledge of many parameters, which are often not available. Here we describe an alternative approach based on the experimental evaluation of a detector using an isotropic point-like light source with precisely controllable light emission properties, installed on a 3D positioning system. The results obtained with the developed setup at validation conditions, when the scattered light is strongly suppressed show good agreement with simulations

  18. ULF Wave Associated Density Irregularities and Scintillation at the Equator

    Science.gov (United States)

    Yizengaw, E.; Moldwin, M.; Zesta, E.

    2017-12-01

    This paper presents independent multi-instrument observations that addresses the physical mechanisms of how ULF wave associated electric fields initiate ionospheric density fluctuations and scintillation at the equator. Since the magnetic field at the equator is entirely embedded in a relatively high collision and high conductivity medium, the condition may not be possible for the geomagnetic field to fluctuate due to the damped/penetrated ULF wave. This implies the fluctuating electric field at the equator may not be produced through equatorial dynamo action due to fluctuating magnetic fields. Instead the oscillating field penetrates from high-latitudes through the TM0 (zero order transverse magnetic) mode and produce fluctuating induced magnetic field, and thus modulate the vertical drift to oscillate. We estimated the ULF associated electric field at high-latitudes and equatorial region, and demonstrated that only 15% of the fluctuating electric field from the auroral region can make to the equatorial region. We also calculated the corresponding vertical drift that oscillate with nearly identical periodicity (6-9 min) as the ULF waves in the Pc5 band. Because of its large amplitude and long periods compared to other ULF wave frequency bands, the Pc5 wave associated electric field can easily penetrate to the lower latitude region. The oscillating vertical drift at the equator has an amplitude of 2.5 - 7.0 m/s, which is 25 -50% of the typical quiet time dayside maximum value of the vertical drift at the equator, which is strong enough fluctuation to easily produce significant ionospheric density fluctuations and trigger scintillation at the equatorial region. In this paper, we present multi-instrument observations that clearly confirm the role of ULF wave penetration for the formation of density irregularities and scintillation at the equator.

  19. Practical use of a plastic scintillator for quality assurance of electron beam therapy

    Science.gov (United States)

    Yogo, Katsunori; Tatsuno, Yuya; Tsuneda, Masato; Aono, Yuki; Mochizuki, Daiki; Fujisawa, Yoshiki; Matsushita, Akihiro; Ishigami, Minoru; Ishiyama, Hiromichi; Hayakawa, Kazushige

    2017-06-01

    Quality assurance (QA) of clinical electron beams is essential for performing accurate and safe radiation therapy. However, with advances in radiation therapy, QA has become increasingly labor-intensive and time-consuming. In this paper, we propose a tissue-equivalent plastic scintillator for quick and easy QA of clinical electron beams. The proposed tool comprises a plastic scintillator plate and a charge-coupled device camera that enable the scintillation light by electron beams to be recorded with high sensitivity and high spatial resolution. Further, the Cerenkov image is directly subtracted from the scintillation image to discriminate Cerenkov emissions and accurately measure the dose profiles of electron beams with high spatial resolution. Compared with conventional methods, discrepancies in the depth profile improved from 7% to 2% in the buildup region via subtractive corrections. Further, the output brightness showed good linearity with dose, good reproducibility (deviations below 1%), and dose rate independence (within 0.5%). The depth of 50% dose measured with the tool, an index of electron beam quality, was within  ±0.5 mm of that obtained with an ionization chamber. Lateral brightness profiles agreed with the lateral dose profiles to within 4% and no significant improvement was obtained using Cerenkov corrections. Field size agreed to within 0.5 mm with those obtained with ionization chamber. For clinical QA of electron boost treatment, a disk scintillator that mimics the shape of a patient’s breast is applied. The brightness distribution and dose, calculated using a treatment planning system, was generally acceptable for clinical use, except in limited zones. Overall, the proposed plastic scintillator plate tool efficiently performs QA for electron beam therapy and enables simultaneous verification of output constancy, beam quality, depth, and lateral dose profiles during monthly QAs at lower doses of irradiation (small monitor units, MUs).

  20. Practical use of a plastic scintillator for quality assurance of electron beam therapy.

    Science.gov (United States)

    Yogo, Katsunori; Tatsuno, Yuya; Tsuneda, Masato; Aono, Yuki; Mochizuki, Daiki; Fujisawa, Yoshiki; Matsushita, Akihiro; Ishigami, Minoru; Ishiyama, Hiromichi; Hayakawa, Kazushige

    2017-06-07

    Quality assurance (QA) of clinical electron beams is essential for performing accurate and safe radiation therapy. However, with advances in radiation therapy, QA has become increasingly labor-intensive and time-consuming. In this paper, we propose a tissue-equivalent plastic scintillator for quick and easy QA of clinical electron beams. The proposed tool comprises a plastic scintillator plate and a charge-coupled device camera that enable the scintillation light by electron beams to be recorded with high sensitivity and high spatial resolution. Further, the Cerenkov image is directly subtracted from the scintillation image to discriminate Cerenkov emissions and accurately measure the dose profiles of electron beams with high spatial resolution. Compared with conventional methods, discrepancies in the depth profile improved from 7% to 2% in the buildup region via subtractive corrections. Further, the output brightness showed good linearity with dose, good reproducibility (deviations below 1%), and dose rate independence (within 0.5%). The depth of 50% dose measured with the tool, an index of electron beam quality, was within  ±0.5 mm of that obtained with an ionization chamber. Lateral brightness profiles agreed with the lateral dose profiles to within 4% and no significant improvement was obtained using Cerenkov corrections. Field size agreed to within 0.5 mm with those obtained with ionization chamber. For clinical QA of electron boost treatment, a disk scintillator that mimics the shape of a patient's breast is applied. The brightness distribution and dose, calculated using a treatment planning system, was generally acceptable for clinical use, except in limited zones. Overall, the proposed plastic scintillator plate tool efficiently performs QA for electron beam therapy and enables simultaneous verification of output constancy, beam quality, depth, and lateral dose profiles during monthly QAs at lower doses of irradiation (small monitor units, MUs).

  1. Radiation imaging with a new scintillator and a CMOS camera

    Czech Academy of Sciences Publication Activity Database

    Kurosawa, S.; Shoji, Y.; Pejchal, Jan; Yokota, Y.; Yoshikawa, A.

    2015-01-01

    Roč. 9, Jul (2015), C07015 ISSN 1748-0221 Institutional support: RVO:68378271 Keywords : scintillators * scintillation and light emission processes * image processin Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.310, year: 2015

  2. An active electron polarized scintillating GSO target for neutrino physics

    Energy Technology Data Exchange (ETDEWEB)

    Baiboussinov, B. [INFN, Sez. di Padova, Via Marzolo 8, 35131 Padova (Italy); Braggio, C., E-mail: braggio@pd.infn.it [INFN, Sez. di Padova, Via Marzolo 8, 35131 Padova (Italy); Dipartimento di Fisica, Universita di Padova, Via Marzolo 8, 35131 Padova (Italy); Cardini, A. [INFN, Sez. di Cagliari, S.P. per Sestu Km 0.700, 09042 Monserrato (Cagliari) (Italy); Carugno, G. [INFN, Sez. di Padova, Via Marzolo 8, 35131 Padova (Italy); Congiu, F. [Dipartimento di Fisica, Universita di Cagliari, S.P. per Sestu Km 0.700, 09042 Monserrato (Cagliari) (Italy); Gain, S. [St. Petersburg State Polytechnical University, 195251 St. Petersburg, Polytekhnicheskaya 29 (Russian Federation); Galeazzi, G. [INFN, Laboratori Nazionali di Legnaro, Viale dell Universita, 2 35020 Legnaro (PD) (Italy); Lai, A. [INFN, Sez. di Cagliari, S.P. per Sestu Km 0.700, 09042 Monserrato (Cagliari) (Italy); Lehman, A.; Mocci, P.; Mura, A.; Quochi, F.; Saba, M. [Dipartimento di Fisica, Universita di Cagliari, S.P. per Sestu Km 0.700, 09042 Monserrato (Cagliari) (Italy); Saitta, B. [INFN, Sez. di Cagliari, S.P. per Sestu Km 0.700, 09042 Monserrato (Cagliari) (Italy); Dipartimento di Fisica, Universita di Cagliari, S.P. per Sestu Km 0.700, 09042 Monserrato (Cagliari) (Italy); Sartori, G. [INFN, Sez. di Padova, Via Marzolo 8, 35131 Padova (Italy)

    2012-12-01

    The feasibility of an electron-polarized, active target to be used as detector in neutrino scattering experiments, suggested by several theoretical papers, has been investigated. We report on the properties of the paramagnetic crystal Gd{sub 2}SiO{sub 5} (GSO), in which 7.7% of the total number of electrons present can be polarized by lowering the temperature and applying an intense external magnetic field. The material magnetic susceptibility has been measured down to cryogenic temperatures showing that for H=5 T and T=4 K about 80% of the maximum allowed magnetization can be attained. Also the spectral and time response of the crystal have been characterized and the scintillation process has been studied using a photomultiplier to measure the response to gamma rays irradiation and cosmic rays operating the GSO crystal at 13.5 K. An avalanche photodiode (APD) readout of the scintillation signal from the GSO crystal has also been performed, since the magnetic field-independent response of this device allows it to be placed close to the crystal in the cryogenic environment.

  3. Current trends in scintillator detectors and materials

    International Nuclear Information System (INIS)

    Moses, William W.

    2001-01-01

    The last decade has seen a renaissance in inorganic scintillator development for gamma ray detection. Lead tungstate (PbWO4) has been developed for high energy physics experiments, and possesses exceptionally high density and radiation hardness, albeit with low luminous efficiency. Lutetium orthosilicate or LSO (Lu2SiO5:Ce) possesses a unique combination of high luminous efficiency, high density, and reasonably short decay time, and is now incorporated in commercial positron emission tomography (PET) cameras. There have been advances in understanding the fundamental mechanisms that limit energy resolution, and several recently discovered materials (such as LaBr3:Ce) possess energy resolution that approaches that of direct solid state detectors. Finally, there are indications that a neglected class of scintillator materials that exhibit near band-edge fluorescence could provide scintillators with sub-nanosecond decay times and high luminescent efficiency

  4. Current trends in scintillator detectors and materials

    CERN Document Server

    Moses, W W

    2002-01-01

    The last decade has seen a renaissance in inorganic scintillator development for gamma ray detection. Lead tungstate (PbWO sub 4) has been developed for high-energy physics experiments, and possesses exceptionally high density and radiation hardness, albeit with low luminous efficiency. Lutetium orthosilicate or LSO (Lu sub 2 SiO sub 5 :Ce) possesses a unique combination of high luminous efficiency, high density, and reasonably short decay time, and is now incorporated in commercial positron emission tomography cameras. There have been advances in understanding the fundamental mechanisms that limit energy resolution, and several recently discovered materials (such as LaBr sub 3 :Ce) possess energy resolution that approaches that of direct solid state detectors. Finally, there are indications that a neglected class of scintillator materials that exhibit near band-edge fluorescence could provide scintillators with sub-nanosecond decay times and high luminescent efficiency.

  5. Development of 300 g scintillating calorimeters

    International Nuclear Information System (INIS)

    Frank, T.; Bruckmayer, M.; Cozzini, C.; Di Stefano, P.; Hauff, D.; Proebst, F.; Seidel, W.; Angloher, G.; Schmidt, J.

    2002-01-01

    The sensitivity for WIMP detection can be improved by an ability to efficiently discriminate the γ and β backgrounds from the nuclear recoil signals. The CRESST phase II detectors will achieve this discrimination by means of simultaneous measurement of phonons and scintillation light. We report on the development of a 300 g detector module consisting of two separate calorimeters fitted with tungsten phase transition thermometers. A 300 g CaWO 4 crystal serves as the target material in which a recoiling WIMP creates both phonons and scintillation light. Phonons are detected by a thermometer on the CaWO 4 crystal. A second smaller detector in close proximity detects the scintillation light. Measurements with this setup will be presented

  6. Current trends in scintillator detectors and materials

    International Nuclear Information System (INIS)

    Moses, W.W.

    2002-01-01

    The last decade has seen a renaissance in inorganic scintillator development for gamma ray detection. Lead tungstate (PbWO 4 ) has been developed for high-energy physics experiments, and possesses exceptionally high density and radiation hardness, albeit with low luminous efficiency. Lutetium orthosilicate or LSO (Lu 2 SiO 5 :Ce) possesses a unique combination of high luminous efficiency, high density, and reasonably short decay time, and is now incorporated in commercial positron emission tomography cameras. There have been advances in understanding the fundamental mechanisms that limit energy resolution, and several recently discovered materials (such as LaBr 3 :Ce) possess energy resolution that approaches that of direct solid state detectors. Finally, there are indications that a neglected class of scintillator materials that exhibit near band-edge fluorescence could provide scintillators with sub-nanosecond decay times and high luminescent efficiency

  7. Determination of light yield from weak scintillations

    International Nuclear Information System (INIS)

    Mandzhukov, I.G.; Mandzhukova, B.V.

    1987-01-01

    Simulation of amplitude distribution of weak scintillation pulses by Puasson distribution is suggestd, if average number of photoelectrons collected on the first dinode of the photomultiplier is of the order of 1. The method permits to determine scintillation yield even in those cases, when the photomultiplier does not have a maximum in monoelectron pulse distribution. Scintillation yields of some aqueous solutions of sodium salicylate and aromatic solvents (benzene, toluene, xylol) at inner α-particle irradiation are determined. It is observed from the given results that efficiency of 239 Pu α-particle detection for aqueous solutions of sodium salicylate with 10% concentration is rather high; it makes up 0.94. They may appear useful for applied problems, paticularly, for measuring α-radiation

  8. Microfluidic Scintillation Detectors for High Energy Physics

    CERN Document Server

    Maoddi, Pietro; Mapelli, Alessandro; CERN

    This thesis deals with the development and study of microfluidic scintillation detectors, a technology of recent introduction for the detection of high energy particles. Most of the interest for such devices comes from the use of a liquid scintillator, which entails the possibility of changing the active material in the detector, leading to increased radiation resistance. A first part of the thesis focuses on the work performed in terms of design and modelling studies of novel prototype devices, hinting to new possibilities and applications. In this framework, the simulations performed to validate selected designs and the main technological choices made in view of their fabrication are addressed. The second part of this thesis deals with the microfabrication of several prototype devices. Two different materials were studied for the manufacturing of microfluidic scintillation detectors, namely the SU-8 photosensitive epoxy and monocrystalline silicon. For what concerns the former, an original fabrication appro...

  9. Scintillation counting: an extrapolation into the future

    International Nuclear Information System (INIS)

    Ross, H.H.

    1983-01-01

    Progress in scintillation counting is intimately related to advances in a variety of other disciplines such as photochemistry, photophysics, and instrumentation. And while there is steady progress in the understanding of luminescent phenomena, there is a virtual explosion in the application of semiconductor technology to detectors, counting systems, and data processing. The exponential growth of this technology has had, and will continue to have, a profound effect on the art of scintillation spectroscopy. This paper will review key events in technology that have had an impact on the development of scintillation science (solid and liquid) and will attempt to extrapolate future directions based on existing and projected capability in associated fields. Along the way there have been occasional pitfalls and several false starts; these too will be discussed as a reminder that if you want the future to be different than the past, study the past

  10. Collimated trans-axial tomographic scintillation camera

    International Nuclear Information System (INIS)

    1980-01-01

    The objects of this invention are first to reduce the time required to obtain statistically significant data in trans-axial tomographic radioisotope scanning using a scintillation camera. Secondly, to provide a scintillation camera system to increase the rate of acceptance of radioactive events to contribute to the positional information obtainable from a known radiation source without sacrificing spatial resolution. Thirdly to reduce the scanning time without loss of image clarity. The system described comprises a scintillation camera detector, means for moving this in orbit about a cranial-caudal axis relative to a patient and a collimator having septa defining apertures such that gamma rays perpendicular to the axis are admitted with high spatial resolution, parallel to the axis with low resolution. The septa may be made of strips of lead. Detailed descriptions are given. (U.K.)

  11. Radiocarbon dating methods using benzene liquid scintillation

    International Nuclear Information System (INIS)

    Togashi, Shigeko; Matsumoto, Eiji

    1983-01-01

    The radiocarbon dating method using benzene liquid scintillation is reported in detail. The results of measurement of NBS oxalic acid agree with the recommended value, indicating that isotopic fractionation during benzene synthesis can be negligible. Ten samples which have been already measured by gas counter are dated by benzene liquid scintillation. There is no significant difference in age for the same sample between benzene liquid scintillation and gas counters. It is shown that quenching has to be corrected for the young sample. Memory effect in stainless steel reaction vessel can be removed by using an exchangeable inner vessel and by baking it in the air. Using this method, the oldest age that can be measured with 2.3 g carbon is 40,000 years B.P. (author)

  12. Optics study of liquid scintillation counting systems

    International Nuclear Information System (INIS)

    Duran Ramiro, M. T.; Garcia-Torano, E.

    2005-01-01

    Optics is a key issue in the development of any liquid scintillation counting (LSC) system. Light emission in the scintillating solution, transmission through the vial and reflector design are some aspects that need to be considered in detail. This paper describes measurements and calculations carried out to optimise these factors for the design of a new family of LSC counters. Measurements of the light distribution emitted by a scintillation vial were done by autoradiographs of cylindrical vials made of various materials and results were compared to those obtained by direct measurements of the light distribution made by scanning the vial with a photomultiplier tube. Calculations were also carried out to study the light transmission in the vial and the optimal design of the reflector for a system with one photomultiplier tube. (Author)

  13. Time resolution measurements with an improved discriminator and conical scintillators

    International Nuclear Information System (INIS)

    McGervey, J.D.; Vogel, J.; Sen, P.; Knox, C.

    1977-01-01

    A new constant fraction discriminator with improved stability and walk characteristics is described. The discriminator was used with RCA C31024 photomultiplier tubes to test scintillators of conical and cylindrical shapes. Conical scintillators of 2.54 cm base diameter, 1.0 cm top diameter, and 2.54 cm height gave a fwhm of 155 ps for 60 Co gamma rays; larger conical scintillators gave an improvement of 10-15% in fwhm over cylindrical scintillators of equal volume. (Auth.)

  14. Inorganic Scintillation Crystals for Neutron Detection

    International Nuclear Information System (INIS)

    Costa-Pereira, Maria-da-Conceicao; Filho, Tufic-Madi; Nahuel-Cardenas, Jose-Patricio

    2013-06-01

    Inorganic scintillators play an important role in the detection and spectroscopy of gamma and X-rays, as well as in neutrons and charged particles. For a variety of applications, new inorganic scintillation materials are being studied. New scintillation detector applications arise continuously and, consequently, the interest in the introduction of new fast scintillators becomes relevant. Scintillation crystals based on cesium iodide (CsI) have relatively low hygroscope, easy handling and low cost, features that favor their use as radiation detectors. In this work, lithium and bromine doped CsI crystals were grown using the vertical Bridgman technique. In this technique, the charge is maintained at high temperature for 10 h for the material melting and complete reaction. The temperature gradient 21 deg. C/cm and 1 mm/h descending velocity are chosen as technique parameters. After growth is finished, the furnace is cooled at a rate of 20 deg. C/h to room temperature. The concentration of the lithium doping element (Li) studied was 10 -3 M and the concentration of the bromine was 10 -2 M. Analyses were carried out to evaluate the scintillators developed concerning the neutron from the AmBe source, with energy range of 1 MeV to 12 MeV. Lithium can capture neutrons without gamma-ray emission, thus, reducing the back-ground. The neutron detection reaction is 6 Li(n, α) 3 H with a thermal neutron cross section of 940 barns. In this paper, it was investigated the feasibility of the CsI:Li and CsI:Br crystals as neutron detectors for monitoring, due to the fact that in our work environment there are two nuclear research reactors and calibration systems. (authors)

  15. Luminescence and scintillation properties of rare-earth-doped LuF.sub.3./sub. scintillation crystals

    Czech Academy of Sciences Publication Activity Database

    Pejchal, Jan; Fukuda, K.; Kurosawa, S.; Yokota, Y.; Yoshikawa, A.

    2015-01-01

    Roč. 41, Mar SI (2015), s. 58-62 ISSN 0925- 3467 Institutional support: RVO:68378271 Keywords : lutetium fluoride * scintillator * scintillator * VUV luminescence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.183, year: 2015

  16. Near-infrared scintillation of liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, T. [Fermilab; Escobar, C. O. [Campinas State U.; Lippincott, W. H. [Fermilab; Rubinov, P. [Fermilab

    2016-03-03

    Since the 1970s it has been known that noble gases scintillate in the near infrared (NIR) region of the spectrum (0.7 $\\mu$m < $\\lambda$; < 1.5$\\mu$m). More controversial has been the question of the NIR light yield for condensed noble gases. We first present the motivation for using the NIR scintillation in liquid argon detectors, then briefly review early as well as more recent efforts and finally show encouraging preliminary results of a test performed at Fermilab.

  17. Fluorescence quenching of plastic scintillators in oxygen

    Science.gov (United States)

    Horstmann, D.; Holm, U.

    1993-01-01

    The plastic scintillators SCSN-38, SCSN-81T, 3HF in polystyrene and a PMMA based Polivar scintillator show a loss in light yield when operated in air or oxygen. Both the fluorescence of the base material polystyrene or the PMMA admixture naphtalene as well as that of the dyes is reduced. The quenching ratio is proportional to the partial pressure of the surrounding oxygen. The maximum overall quenching amounts to 11.1% for SCSN-38 in one atmosphere of oxygen when excited with light of 262 nm.

  18. Fluorescence quenching of plastic scintillators in oxygen

    International Nuclear Information System (INIS)

    Horstmann, D.; Holm, U.

    1992-01-01

    The plastic scintillators SCSN-38, SCSN-81T, 3HF in polystyrene and a PMMA based Polivar scintillator show a loss in light yield when operated in air or oxygen. Both the fluorescence of the base material polystyrene or the PMMA admixture naphtalene as well as that of the dyes is reduced. The quenching ratio is proportional to the partial pressure of the surrounding oxygen. The maximum overall quenching amounts to 11.1 % for SCSN-38 in one atmosphere of oxygen when excited with light of 262 nm. (Author)

  19. Full-absorption scintillation spectrometer for neutrons

    International Nuclear Information System (INIS)

    Dzhelepov, V.P.; Filchenkov, V.V.; Konin, A.D.; Rudenko, A.I.; Solovieva, G.M.; Zinov, V.G.

    1988-01-01

    A full-absorption scintillation spectrometer for neutrons (volume of scintillator = 24 l) has been developed and employed in investigations of muon catalysed processes. Its application allows: (a) Considerably increasing the rate of accummulation of events; (b) efficiently using muon catalysis multiplicity for fuller and more reliable determination of its parameters; (c) significantly reducing uncertainty in the calculated and experimentally found values of neutron detection efficiency. The device combines good spectrometric properties for neutron energies E n = 1-6 MeV and reliable n-γ separation (the degree of separation for a Pu-Be source 3 starting from an electron energy of 50 keV). (orig.)

  20. Plastic scintillators modifications for a selective radiation detection

    Energy Technology Data Exchange (ETDEWEB)

    Hamel, Matthieu; Bertrand, Guillaume H.V.; Carrel, Frederick; Coulon, Romain; Dumazert, Jonathan; Montbarbon, Eva; Sguerra, Fabien [CEA, LIST, Laboratoire Capteurs and Architectures electroniques, 91191 Gif-sur-Yvette cedex (France)

    2015-07-01

    Recent developments of plastic scintillators are reviewed, from January 2000 to June 2015. All examples are distributed into the main application, i.e. how the plastic scintillator was modified to enhance the detection towards a given radiation particle. The main characteristics of these newly created scintillators and their detection properties are given. (authors)

  1. Upconverting nanoparticles for optimizing scintillator based detection systems

    Science.gov (United States)

    Kross, Brian; McKisson, John E; McKisson, John; Weisenberger, Andrew; Xi, Wenze; Zom, Carl

    2013-09-17

    An upconverting device for a scintillation detection system is provided. The detection system comprises a scintillator material, a sensor, a light transmission path between the scintillator material and the sensor, and a plurality of upconverting nanoparticles particles positioned in the light transmission path.

  2. Neutron detection by scintillation of noble-gas excimers

    Science.gov (United States)

    McComb, Jacob Collin

    Neutron detection is a technique essential to homeland security, nuclear reactor instrumentation, neutron diffraction science, oil-well logging, particle physics and radiation safety. The current shortage of helium-3, the neutron absorber used in most gas-filled proportional counters, has created a strong incentive to develop alternate methods of neutron detection. Excimer-based neutron detection (END) provides an alternative with many attractive properties. Like proportional counters, END relies on the conversion of a neutron into energetic charged particles, through an exothermic capture reaction with a neutron absorbing nucleus (10B, 6Li, 3He). As charged particles from these reactions lose energy in a surrounding gas, they cause electron excitation and ionization. Whereas most gas-filled detectors collect ionized charge to form a signal, END depends on the formation of diatomic noble-gas excimers (Ar*2, Kr*2,Xe* 2) . Upon decaying, excimers emit far-ultraviolet (FUV) photons, which may be collected by a photomultiplier tube or other photon detector. This phenomenon provides a means of neutron detection with a number of advantages over traditional methods. This thesis investigates excimer scintillation yield from the heavy noble gases following the boron-neutron capture reaction in 10B thin-film targets. Additionally, the thesis examines noble-gas excimer lifetimes with relationship to gas type and gas pressure. Experimental data were collected both at the National Institute of Standards and Technology (NIST) Center for Neutron Research, and on a newly developed neutron beamline at the Maryland University Training Reactor. The components of the experiment were calibrated at NIST and the University of Maryland, using FUV synchrotron radiation, neutron imaging, and foil activation techniques, among others. Computer modeling was employed to simulate charged-particle transport and excimer photon emission within the experimental apparatus. The observed excimer

  3. Scintillator developments for high energy physics and medical imaging

    CERN Document Server

    Lecoq, P

    2000-01-01

    Scintillating crystals have been for a long time developed as a basic component in particle detectors with a strong spin-off in the field of medical imaging. A typical example is BGO, which has become the main component of PET scanners since the large effort made by the L3 experiment at CERN to develop low cost production methods for this crystal. Systematic R&D on basic mechanism in inorganic scintillators, initiated by the Crystal Clear Collaboration at CERN 10 years ago, has contributed not to a small amount, to the development of new materials for high energy physics and for a new generation of medical imaging devices with increased resolution and sensitivity. The examples of the lead tungstate crystal for the CMS experiment at CERN (high energy physics) as well as of new materials under development for medical imaging will be described with an emphasis on the mutual benefit both fields can extract from a common R&D effort. (14 refs).

  4. Statistical evaluation of GLONASS amplitude scintillation over low latitudes in the Brazilian territory

    Science.gov (United States)

    de Oliveira Moraes, Alison; Muella, Marcio T. A. H.; de Paula, Eurico R.; de Oliveira, César B. A.; Terra, William P.; Perrella, Waldecir J.; Meibach-Rosa, Pâmela R. P.

    2018-04-01

    The ionospheric scintillation, generated by the ionospheric plasma irregularities, affects the radio signals that pass through it. Their effects are widely studied in the literature with two different approaches. The first one deals with the use of radio signals to study and understand the morphology of this phenomenon, while the second one seeks to understand and model how much this phenomenon interferes in the radio signals and consequently in the services to which these systems work. The interest of several areas, particularly to those that are life critical, has increased using the concept of satellite multi-constellation, which consists of receiving, processing and using data from different navigation and positioning systems. Although there is a vast literature analyzing the effects of ionospheric scintillation on satellite navigation systems, the number of studies using signals received from the Russian satellite positioning system (named GLONASS) is still very rare. This work presents for the first time in the Brazilian low-latitude sector a statistical analysis of ionospheric scintillation data for all levels of magnetic activities obtained by a set of scintillation monitors that receive signals from the GLONASS system. In this study, data collected from four stations were used in the analysis; Fortaleza, Presidente Prudente, São José dos Campos and Porto Alegre. The GLONASS L-band signals were analyzed for the period from December 21, 2012 to June 20, 2016, which includes the peak of the solar cycle 24 that occurred in 2014. The main characteristics of scintillation presented in this study include: (1) the statistical evaluation of seasonal and solar activity, showing the chances that an user on similar geophysical conditions may be susceptible to the effects of ionospheric scintillation; (2) a temporal analysis based on the local time distribution of scintillation at different seasons and intensity levels; and (3) the evaluation of number of

  5. 3D tomodosimetry using long scintillating fibers: A feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Goulet, Mathieu; Archambault, Louis; Beaulieu, Luc; Gingras, Luc [Département de Physique, de Génie Physique et d’Optique et Centre de Recherche sur le cancer, Université Laval, Québec, Québec G1V 0A6, Canada, and Département de Radio-Oncologie and CRCHU de Quebec, CHU de Québec, 11 Côte du Palais, Québec, Québec G1R 2J6 (Canada)

    2013-10-15

    Purpose: 3D dosimetry is recognized as an ideal for patient-specific quality assurance (QA) of highly conformal radiotherapy treatments. However, existing 3D dosimeters are not straightforward to implement in the clinic, as their read-out procedure is often tedious and their accuracy, precision, and/or sample size exhibit limitations. The purpose of this work is to develop a 3D dosimeter based on the concept of tomodosimetry inside concentric cylindrical planes using long scintillating fibers for the QA of modern radiotherapy techniques such as intensity-modulated radiation therapy (IMRT) or intensity-modulated arc therapy (IMAT).Methods: Using a model-based simulation, scintillating fibers were modeled on three concentric cylindrical planes of radii 2.5, 5.0, and 7.5 cm, inside a 10 cm radius water-equivalent cylinder phantom. The phantom was set to rotate around its central axis, made parallel to the linac gantry axis of rotation. Light acquisitions were simulated using the calculated dose from the treatment planning software and reconstructed in each cylindrical plane at a resolution of 1 mm{sup 2} using a total-variation minimization iterative reconstruction algorithm. The 3D dose was then interpolated from the reconstructed cylindrical plane doses at a resolution of 1 mm{sup 3}. Different scintillating fiber patterns were compared by varying the angle of each fiber in its cylindrical plane and introducing a light-tight cut in each fiber. The precision of the reconstructed cylindrical dose distribution was evaluated using a Poisson modeling of the acquired light signals and the accuracy of the interpolated 3D dose was evaluated using an IMRT clinical plan for a prostate case.Results: Straight scintillating fiber patterns with light-tight cuts were the most accurate in cylindrical dose reconstruction, showing less than 0.5 mm distance-to-agreement in dose gradients and a mean local dose difference of less than 0.2% in the high dose region for a 10 × 10 cm{sup 2

  6. The SNO+ Scintillator Purification Plant and Projected Sensitivity to Solar Neutrinos in the Pure Scintillator Phase

    Science.gov (United States)

    Pershing, Teal; SNO+ Collaboration

    2016-03-01

    The SNO+ detector is a neutrino and neutrinoless double-beta decay experiment utilizing the renovated SNO detector. In the second phase of operation, the SNO+ detector will contain 780 tons of organic liquid scintillator composed of 2 g/L 2,5-diphenyloxazole (PPO) in linear alkylbenzene (LAB). In this phase, SNO+ will strive to detect solar neutrinos in the sub-MeV range, including CNO production neutrinos and pp production neutrinos. To achieve the necessary detector sensitivity, a four-part scintillator purification plant has been constructed in SNOLAB for the removal of ionic and radioactive impurities. We present an overview of the SNO+ scintillator purification plant stages, including distillation, water extraction, gas stripping, and metal scavenger columns. We also give the projected SNO+ sensitivities to various solar-produced neutrinos based on the scintillator plant's projected purification efficiency.

  7. Scintillator device using a combined organic-inorganic scintillator as dose ratemeter

    International Nuclear Information System (INIS)

    Kolb, W.; Lauterbach, U.

    1974-01-01

    The dose ratemeter independent of energy in the energy region 17 keV to 3 MeV consists of an organic and an inorganic scintillator. The organic scintillation material of an anthracene monocrystal is surrounded by ZnS surface coating. The coating thickness of the inorganic scintillator ZnS is measured in such a manner for gamma and X-radiation below 100 keV that the light produced due to the incident radiation compensates for the decrease of light produced in the organic scintillator. The whole energy and dose rate region of interest for radiation protection can thus be measured with a detector volume of 135 cm 3 . (DG) [de

  8. General considerations for SSC scintillator calorimeters (For the scintillator general subgroup)

    International Nuclear Information System (INIS)

    Nodulman, L.

    1989-01-01

    The Scintillator Calorimetry group divided into three subgroups: a conventional uranium and plate design ala ZEUS, fiber design, and a group on general considerations. The considerations of the third group are reported here on geometrical and technical issues. 1 fig

  9. Temperature dependence of scintillation properties of bright oxide scintillators for well-logging

    Czech Academy of Sciences Publication Activity Database

    Yanagida, T.; Fujimoto, Y.; Kurosawa, S.; Kamada, K.; Takahashi, H.; Fukazawa, Y.; Nikl, Martin; Chani, V.

    2013-01-01

    Roč. 52, č. 7 (2013), "076401-1"-"076401-6" ISSN 0021-4922 Institutional support: RVO:68378271 Keywords : scintillator * high temperature * light yield Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.057, year: 2013

  10. New inorganic scintillation materials development for medical imaging

    CERN Document Server

    Lecoq, P

    2002-01-01

    As already advertised for several years, Lu-based compounds doped with trivalent Ce seem to be the most promising scintillators for a new generation of positron emission tomography scanners. Two crystals, namely LSO: Ce and LuAP : Ce, are under intensive study, but there is still an interest in searching for materials with a better combination of price/performance. In the study reported in this paper, we paid attention to the compounds containing rare earth and Ba, Hf. Another motivation was an increase of the effective charge of the host matrix and a decrease of the Lu fraction in compound. In this paper, we discuss spectroscopic properties of several new heavy compounds such as Lu/sub 2/Hf/sub 2/O/sub 7/, La /sub 2/Hf/sub 2/O/sub 7/ and Ba/sub 3/Lu/sub 4/O/sub 9/ doped with Ce. (22 refs).

  11. High-Z Nanoparticle/Polymer Nanocomposites for Gamma-Ray Scintillation Detectors

    Science.gov (United States)

    Liu, Chao

    An affordable and reliable solution for spectroscopic gamma-ray detection has long been sought after due to the needs from research, defense, and medical applications. Scintillators resolve gamma energy by proportionally converting a single high-energy photon into a number of photomultiplier-tube-detectable low-energy photons, which is considered a more affordable solution for general purposes compared to the delicate semiconductor detectors. An ideal scintillator should simultaneously exhibit the following characteristics: 1) high atomic number (Z) for high gamma stopping power and photoelectron production; 2) high light yield since the energy resolution is inversely proportional to the square root of light yield; 3) short emission decay lifetime; and 4) low cost and scalable production. However, commercial scintillators made from either inorganic single crystals or plastics fail to satisfy all requirements due to their intrinsic material properties and fabrication limitations. The concept of adding high-Z constituents into plastic scintillators to harness high Z, low cost, and fast emission in the resulting nanocomposite scintillators is not new in and of itself. Attempts have been made by adding organometallics, quantum dots, and scintillation nanocrystals into the plastic matrix. High-Z organometallics have long been used to improve the Z of plastic scintillators; however, their strong spin-orbit coupling effect entails careful triplet energy matching using expensive triplet emitters to avoid severe quenching of the light yield. On the other hand, reported quantum dot- and nanocrystal-polymer nanocomposites suffer from moderate Z and high optical loss due to aggregation and self-absorption at loadings higher than 10 wt%, limiting their potential for practical application. This dissertation strives to improve the performance of nanoparticle-based nanocomposite scintillators. One focus is to synthesize transparent nanocomposites with higher loadings of high

  12. Plastic scintillation dosimetry for radiation therapy: minimizing capture of Cerenkov radiation noise

    International Nuclear Information System (INIS)

    Beddar, A Sam; Suchowerska, Natalka; Law, Susan H

    2004-01-01

    Over the last decade, there has been an increased interest in scintillation dosimetry using small water-equivalent plastic scintillators, because of their favourable characteristics when compared with other more commonly used detector systems. Although plastic scintillators have been shown to have many desirable dosimetric properties, as yet there is no successful commercial detector system of this type available for routine clinical use in radiation oncology. The main factor preventing this new technology from realizing its full potential in commercial applications is the maximization of signal coupling efficiency and the minimization of noise capture. A principal constituent of noise is Cerenkov radiation. This study reports the calculated capture of Cerenkov radiation by an optical fibre in the special case where the radiation is generated by a relativistic particle on the fibre axis and the fibre axis is parallel to the Cerenkov cone. The fraction of radiation captured is calculated as a function of the fibre core refractive index and the refractive index difference between the core and the cladding of the fibre for relativistic particles. This is then used to deduce the relative intensity captured for a range of fibre core refractive indices and fibre core-cladding refractive index differences. It is shown that the core refractive index has little effect on the amount of radiation captured compared to the refractive index difference. The implications of this result for the design of radiation therapy plastic scintillation dosimeters are considered

  13. Neutron spectrometer using NE218 liquid scintillator

    International Nuclear Information System (INIS)

    Dance, J.B.; Francois, P.E.

    1976-01-01

    A neutron spectrometer has been constructed using NE218 liquid scintillator. Discrimination against electron-gamma events was obtained usng a charge-comparison pulse shape discrimination system. The resolution obtained was about 0.25 MeV F.W.H.M. at 2.0 MeV

  14. Progress in studying scintillator proportionality: Phenomenological model

    Energy Technology Data Exchange (ETDEWEB)

    Bizarri, Gregory; Cherepy, Nerine; Choong, Woon-Seng; Hull, Giulia; Moses, William; Payne, Sephen; Singh, Jai; Valentine, John; Vasilev, Andrey; Williams, Richard

    2009-04-30

    We present a model to describe the origin of non-proportional dependence of scintillator light yield on the energy of an ionizing particle. The non-proportionality is discussed in terms of energy relaxation channels and their linear and non-linear dependences on the deposited energy. In this approach, the scintillation response is described as a function of the deposited energy deposition and the kinetic rates of each relaxation channel. This mathematical framework allows both a qualitative interpretation and a quantitative fitting representation of scintillation non-proportionality response as function of kinetic rates. This method was successfully applied to thallium doped sodium iodide measured with SLYNCI, a new facility using the Compton coincidence technique. Finally, attention is given to the physical meaning of the dominant relaxation channels, and to the potential causes responsible for the scintillation non-proportionality. We find that thallium doped sodium iodide behaves as if non-proportionality is due to competition between radiative recombinations and non-radiative Auger processes.

  15. An improved model of equatorial scintillation

    Science.gov (United States)

    Secan, J. A.; Bussey, R. M.; Fremouw, E. J.; Basu, Sa.

    1995-05-01

    One of the main limitations of the modeling work that went into the equatorial section of the Wideband ionospheric scintillation model (WBMOD) was that the data set used in the modeling was limited to two stations near the dip equator (Ancon, Peru, and Kwajalein Island, in the North Pacific Ocean) at two fixed local times (nominally 1000 and 2200). Over the past year this section of the WBMOD model has been replaced by a model developed using data from three additional stations (Ascension Island, in the South Atlantic Ocean, Huancayo, Peru, and Manila, Phillipines; data collected under the auspices of the USAF Phillips Laboratory Geophysics Directorate) which provide a greater diversity in both latitude and longitude, as well as cover the entire day. The new model includes variations with latitude, local time, longitude, season, solar epoch, and geomagnetic activity levels. The way in which the irregularity strength parameter CkL is modeled has also been changed. The new model provides the variation of the full probability distribution function (PDF) of log (CkL) rather than simply the average of log (CkL). This permits the user to specify a threshold on scintillation level, and the model will calculate the percent of the time that scintillation will exceed that level in the user-specified scenario. It will also permit calculation of scintillation levels at a user-specified percentile. A final improvement to the WBMOD model is the implementation of a new theory for calculating S4 on a two-way channel.

  16. High resolution scintillation detector with semiconductor readout

    Science.gov (United States)

    Levin, Craig S.; Hoffman, Edward J.

    2000-01-01

    A novel high resolution scintillation detector array for use in radiation imaging such as high resolution Positron Emission Tomography (PET) which comprises one or more parallelepiped crystals with at least one long surface of each crystal being in intimate contact with a semiconductor photodetector such that photons generated within each crystal by gamma radiation passing therethrough is detected by the photodetector paired therewith.

  17. Neutron energy response measurement of scintillation detectors

    International Nuclear Information System (INIS)

    Yang Hongqiong; Peng Taiping; Yang Jianlun; Tang Zhengyuan; Yang Gaozhao; Li Linbo; Hu Mengchun; Wang Zhentong; Zhang Jianhua; Li Zhongbao; Wang Lizong

    2004-01-01

    Neutron sensitivities of detectors composed of plastic scintillator ST401, ST1422, ST1423 and phyotomultiplier tube in primary energy range of fission neutron are calibrated by direct current. The energy response curve of the detectors is obtained in this experiment. The experimental result has been compared with the theoretical calculation and they are in agreement within measuring uncertainty. (authors)

  18. Thallium bromide photodetectors for scintillation detection

    CERN Document Server

    Hitomi, K; Shoji, T; Hiratate, Y; Ishibashi, H; Ishii, M

    2000-01-01

    A wide bandgap compound semiconductor, TlBr, has been investigated as a blue sensitive photodetector material for scintillation detection. The TlBr photodetectors have been fabricated from the TlBr crystals grown by the TMZ method using materials purified by many pass zone refining. The performance of the photodetectors has been evaluated by measuring their leakage current, quantum efficiency, spatial uniformity, direct X-ray detection and scintillation detection characteristics. The photodetectors have shown high quantum efficiency for the blue wavelength region and high spatial uniformity for their optical response. In addition, good direct X-ray detection characteristics with an energy resolution of 4.5 keV FWHM for 22 keV X-rays from a sup 1 sup 0 sup 9 Cd radioactive source have been obtained. Detection of blue scintillation from GSO and LSO scintillators irradiated with a sup 2 sup 2 Na radioactive source has been done successfully by using the photodetectors at room temperature. A clear full-energy pea...

  19. Infrared scintillation in gases, liquids and crystals

    NARCIS (Netherlands)

    Belogurov, S.; Bressi, G; Carugno, G.; Conti, E; Iannuzzi, D; Meneguzzo, AT

    2000-01-01

    We report about experimental evidences of infrared scintillation in gaseous, liquid and crystal samples. We firstly studied noble gases at room temperature and near atmospheric pressure in the wavelength range between 0.7 and 1.81 mum. Ar gas emits infrared photons when irradiated by a proton beam.

  20. A multidetector scintillation camera with 254 channels

    DEFF Research Database (Denmark)

    Sveinsdottir, E; Larsen, B; Rommer, P

    1977-01-01

    A computer-based scintillation camera has been designed for both dynamic and static radionuclide studies. The detecting head has 254 independent sodium iodide crystals, each with a photomultiplier and amplifier. In dynamic measurements simultaneous events can be recorded, and 1 million total coun...

  1. Basic processes and scintillator and semiconductor detectors

    International Nuclear Information System (INIS)

    Bourgeois, C.

    1994-01-01

    In the following course, the interaction of heavy charged particles, electrons and Γ with matter is represented. Two types of detectors are studied, organic and inorganic scintillators and semiconductors. The signal formation is analysed. (author). 13 refs., 48 figs., 5 tabs

  2. Light pulse shapes from plastic scintillators

    International Nuclear Information System (INIS)

    Moszynski, M.; Bengtson, B.

    1977-01-01

    A detailed study of the light pulse shape from the binary NE 111 and the ternary Pilot U, Naton 136, KL 236, NE 102A, NE 104 and NE 110 plastic scintillators was performed by the single photon method using XP 1021 and C 31024 photomultipliers. The analysis of the shape of the light pulses determined experimentally for several samples of different dimensions gave the following conclusions. The original light pulse shape from the binary NE 111 scintillator, as measured with a 5 mm thick polished sample is described analytically by the convolution integral of a Gaussian and an exponential function. The Gaussian function may reflect a deexcitation of several higher levels of the solvent molecules excited by nuclear particles preceding an intermolecular energy transfer in the scintillator. It may introduce a rather important limitation of the speed of plastic scintillators as the standard deviation of the Gaussian function is equal to 0.2 ns. The light pulse shape from the ternary plastics is described by the convolution integral of a Gaussian and two exponential functions. The Gaussian function presents the rate of energy transfer from nuclear particles to the primary solute as in the binary plastics. The exponential functions describe the energy transfer from the primary solute to the wavelength shifter and the final emission of the light. (Auth.)

  3. A multidetector scintillation camera with 254 channels

    DEFF Research Database (Denmark)

    Sveinsdottir, E; Larsen, B; Rommer, P

    1977-01-01

    A computer-based scintillation camera has been designed for both dynamic and static radionuclide studies. The detecting head has 254 independent sodium iodide crystals, each with a photomultiplier and amplifier. In dynamic measurements simultaneous events can be recorded, and 1 million total counts...

  4. Scintillating fibre (SciFi) tracker

    CERN Multimedia

    Caraban Gonzalez, Noemi

    2017-01-01

    128 modules – containing 11 000 km of scintillating fibres – will make up the new SciFi tracker, which will replace the outer and inner trackers of the LHCb detector as part of the experiment’s major upgrade during Long Shutdown 2 (LS2)

  5. System and method of liquid scintillation counting

    International Nuclear Information System (INIS)

    Rapkin, E.

    1977-01-01

    A method of liquid scintillation counting utilizing a combustion step to overcome quenching effects comprises novel features of automatic sequential introduction of samples into a combustion zone and automatic sequential collection and delivery of combustion products into a counting zone. 37 claims, 13 figures

  6. Large area scintillators for massive neutrino detectors

    CERN Document Server

    Bonesini, M

    2003-01-01

    A technique based on extruded scintillators for the active elements of large mass neutrino detectors is described in this paper. The robustness of the technique, pioneered by the Minos Collaboration, is demonstrated by the good results obtained on a six months timescale research and development done for the 1216 proposal at CERN.

  7. Fluorescent compounds for plastic scintillation applications

    Energy Technology Data Exchange (ETDEWEB)

    Pla-Dalmau, A.; Bross, A.D.

    1994-04-01

    Several 2-(2{prime}-hydroxyphenyl)benzothiazole, -benzoxazole, and -benzimidazole derivatives have been prepared. Transmittance, fluorescence, light yield, and decay time characteristics of these compounds have been studied in a polystyrene matrix and evaluated for use in plastic scintillation detectors. Radiation damage studies utilizing a {sup 60}C source have also been performed.

  8. Experimental evidence of infrared scintillation in crystals

    CERN Document Server

    Belogurov, S; Carugno, Giovanni; Conti, E; Iannuzzi, D; Meneguzzo, Anna Teresa

    2000-01-01

    We present experimental results on infrared emission induced by protons in some solid-state samples. Infrared scintillation occurs in many crystals, with different yield values and time-response behaviours. A rough measurement of the emission wavelength of CsI(Tl) is also reported.

  9. Systematic study of particle quenching in organic scintillators

    International Nuclear Information System (INIS)

    Santiago, L.M.; Bagán, H.; Tarancón, A.; Rauret, G.; Garcia, J.F.

    2013-01-01

    Among the different factors that affect measurements by organic scintillators, the majority of attention has been focused on those related to the scintillator (i.e., ionization, chemical, color and optical quenching), and less attention has been paid to the loss of energy before the particle (i.e., alpha or beta) arrives at the scintillator (i.e., particle quenching). This study evaluates the effect of particle quenching in different scintillation methods (i.e., using two plastic scintillation microspheres (PSm1 and PSm2), liquid scintillator and gel scintillator) by measuring solutions that contain increasing concentrations of NaCl, BaCl 2 and glycerin. The results show the importance of particle quenching in PSm measurements because detection efficiency decreases with increasing concentrations of the quenching component, although the spectrum position and external standard parameter remain constant. The results have shown evidence of particle quenching, although at a lower magnitude, in the liquid scintillation or gel scintillation measurements. Moreover, the use of two PSm with different diameters and salty compound that alters the equilibrium of the liquid and gel emulsions also exemplified the importance of the transmission of optical photons through different scintillation media (i.e., optical quenching). Improvement and deterioration of the optical conditions on the scintillation media is manifested as a movement of the spectrum to higher and lower energies, respectively. The results obtained with PSm were confirmed by Monte Carlo simulation.

  10. Systematic study of particle quenching in organic scintillators

    Science.gov (United States)

    Santiago, L. M.; Bagán, H.; Tarancón, A.; Rauret, G.; Garcia, J. F.

    2013-01-01

    Among the different factors that affect measurements by organic scintillators, the majority of attention has been focused on those related to the scintillator (i.e., ionization, chemical, color and optical quenching), and less attention has been paid to the loss of energy before the particle (i.e., alpha or beta) arrives at the scintillator (i.e., particle quenching). This study evaluates the effect of particle quenching in different scintillation methods (i.e., using two plastic scintillation microspheres (PSm1 and PSm2), liquid scintillator and gel scintillator) by measuring solutions that contain increasing concentrations of NaCl, BaCl2 and glycerin. The results show the importance of particle quenching in PSm measurements because detection efficiency decreases with increasing concentrations of the quenching component, although the spectrum position and external standard parameter remain constant. The results have shown evidence of particle quenching, although at a lower magnitude, in the liquid scintillation or gel scintillation measurements. Moreover, the use of two PSm with different diameters and salty compound that alters the equilibrium of the liquid and gel emulsions also exemplified the importance of the transmission of optical photons through different scintillation media (i.e., optical quenching). Improvement and deterioration of the optical conditions on the scintillation media is manifested as a movement of the spectrum to higher and lower energies, respectively. The results obtained with PSm were confirmed by Monte Carlo simulation.

  11. Non-Carbon Dyes For Platic Scintillators- Report

    Energy Technology Data Exchange (ETDEWEB)

    Teprovich, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Colon-Mercado, H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Gaillard, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Sexton, L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Washington, A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Ward, P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Velten, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-19

    Scintillation based detectors are desirable for many radiation detection applications (portal and border monitoring, safeguards verification, contamination detection and monitoring). The development of next generation scintillators will require improved detection sensitivity for weak gamma ray sources, and fast and thermal neutron quantification. Radiation detection of gamma and neutron sources can be accomplished with organic scintillators, however, the single crystals are difficult to grow for large area detectors and subject to cracking. Alternatives to single crystal organic scintillators are plastic scintillators (PS) which offer the ability to be shaped and scaled up to produce large sized detectors. PS is also more robust than the typical organic scintillator and are ideally suited for deployment in harsh real-world environments. PS contain a mixture of dyes to down-convert incident radiation into visible light that can be detected by a PMT. This project will evaluate the potential use of nano-carbon dyes in plastic scintillators.

  12. Neutron detection with plastic scintillators coupled to solid state photomultiplier detectors

    Science.gov (United States)

    Christian, James F.; Johnson, Erik B.; Fernandez, Daniel E.; Vogel, Samuel; Frank, Rebecca; Stoddard, Graham; Stapels, Christopher; Pereira, Jorge; Zegers, Remco

    2017-09-01

    The recent reduction of dark current in Silicon Solid-state photomultipliers (SiSSPMs) makes them an attractive alternative to conventional photomultiplier tubes (PMTs) for scintillation detection applications. Nuclear Physics experiments often require large detector volumes made using scintillation materials, which require sensitive photodetectors, such as a PMTs. PMTs add to the size, fragility, and high-voltage requirements as well as distance requirements for experiments using magnetic fields. This work compares RMD's latest detector modules, denoted as the "year 2 prototype", of plastic scintillators that discriminate gamma and high-energy particle events from neutron events using pulse shape discrimination (PSD) coupled to a SiSSPM to the following two detector modules: a similar "year 1 prototype" and a scintillator coupled to a PMT module. It characterizes the noise floor, relative signal-to-noise ratio (SNR), the timing performance, the PSD figure-of-merit (FOM) and the neutron detection efficiency of RMD's detectors. This work also evaluates the scaling of SiSSPM detector modules to accommodate the volumes needed for many Nuclear Physics experiments. The Si SSPM detector module provides a clear advantage in Nuclear Physics experiments that require the following attributes: discrimination of neutron and gamma-ray events, operation in or near strong magnetic fields, and segmentation of the detector.

  13. An ultrafast X-ray scintillating detector made of ZnO(Ga)

    Science.gov (United States)

    Zhang, Qingmin; Yan, Jun; Deng, Bangjie; Zhang, Jingwen; Lv, Jinge; Wen, Xin; Gao, Keqing

    2017-12-01

    Owing to its ultrafast scintillation, quite high light yield, strong radiation resistance, and non-deliquescence, ZnO(Ga) is a highly promising choice for an ultrafast X-ray detector. Because of its high deposition rate, good production repeatability and strong adhesive force, reactive magnetron sputtering was used to produce a ZnO(Ga) crystal on a quartz glass substrate, after the production conditions were optimized. The fluorescence lifetime of the sample was 173 ps. An ultrafast X-ray scintillating detector, equipped with a fast microchannel plate (MCP) photomultiplier tube (PMT), was developed and the X-ray tests show a signal full width at half maximum (FWHM) of only 385.5 ps. Moreover, derivation from the previous measurement shows the ZnO(Ga) has an ultrafast time response (FWHM = 355.1 ps) and a high light yield (14740 photons/MeV).

  14. Cerium doped lanthanum halides: fast scintillators for medical imaging; Halogenures de lanthane dopes cerium des scintillateurs rapides pour l'imagerie medicale

    Energy Technology Data Exchange (ETDEWEB)

    Selles, O

    2006-12-15

    This work is dedicated to two recently discovered scintillating crystals: cerium doped lanthanum halides (LaCl{sub 3}:Ce{sup 3+} and LaBr{sub 3}:Ce{sup 3+}).These scintillators exhibit interesting properties for gamma detection, more particularly in the field of medical imaging: a short decay time, a high light yield and an excellent energy resolution. The strong hygroscopicity of these materials requires adapting the usual experimental methods for determining physico-chemical properties. Once determined, these can be used for the development of the industrial manufacturing process of the crystals. A proper comprehension of the scintillation mechanism and of the effect of defects within the material lead to new possible ways for optimizing the scintillator performance. Therefore, different techniques are used (EPR, radioluminescence, laser excitation, thermally stimulated luminescence). Alongside Ce{sup 3+} ions, self-trapped excitons are involved in the scintillation mechanism. Their nature and their role are detailed. The knowledge of the different processes involved in the scintillation mechanism leads to the prediction of the effect of temperature and doping level on the performance of the scintillator. A mechanism is proposed to explain the thermally stimulated luminescence processes that cause slow components in the light emission and a loss of light yield. Eventually the study of afterglow reveals a charge transfer to deep traps involved in the high temperature thermally stimulated luminescence. (author)

  15. Nonproportionality of Scintillator Detectors: Theory and Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Payne, Stephen; Cherepy, Nerine; Hull, Giulia; Valentine, John; Moses, William; Choong, Woon-Seng

    2009-08-17

    On the basis of nonproportionality data obtained for several scintillators, we have developed a theory to describe the carrier dynamics to fit the light yield versus electron energy. The theory of Onsager was adapted to explain how the carriers form excitons or sequentially arrive at the activators to promote the ion to an excited state, and the theory of Birks was employed to allow for exciton-exciton annihilation. We then developed a second theory to deduce the degradation in resolution that results from nonproportionality by evoking Landau fluctuations, which are essentially variations in the deposited energy density that occur as the high energy electron travels along its trajectory. In general there is good agreement with the data, in terms of fitting the nonproportionality curves and reproducing the literature values of nonproportionality's contribution to the scintillator resolution. With the resurgence of interest in developing scintillator detectors that have good energy resolution, an improved understanding of nonproportionality has become a crucial matter since it presents the fundamental limit to the achievable resolution. In order to hasten an improved understanding of scintillator nonproportionality, we have constructed an instrument referred to as SLYNCI (Scintillator Light Yield Nonproportionality Compton Instrument). This is a second-generation instrument to the original device developed by Valentine and coworkers, wherein several new principles of operation have served to increase the data rate by an order of magnitude as discussed in detail in References. In the present article, the focus is on a theory to describe the measured electron response, which is the light yield as a function of the electron energy. To do this, we account for transport of carriers and excitons, in terms of how they transfer their energy to the activators with competition from nonradiative decay pathways. This work builds on the original work of Murray and coworkers

  16. Irradiance Scintillation Index for a Gaussian Beam Based on the Generalized Modified Atmospheric Spectrum with Aperture Averaged

    Directory of Open Access Journals (Sweden)

    Chao Gao

    2016-01-01

    Full Text Available This paper investigates the aperture-averaged irradiance scintillation index of a Gaussian beam propagating through a horizontal path in weak non-Kolmogorov turbulence. Mathematical expressions are obtained based on the generalized modified atmospheric spectrum, which includes the spectral power law value of non-Kolmogorov turbulence, the finite inner and outer scales of turbulence, and other optical parameters of the Gaussian beam. The numerical results are conducted to analyze the influences of optical parameters on the aperture-averaged irradiance scintillation index for different Gaussian beams. This paper also examines the effects of the irradiance scintillation on the performance of the point-to-point optical wireless communication system with intensity modulation/direct detection scheme.

  17. Determination of the energy dependence of the BC-408 plastic scintillation detector in medium energy x-ray beams

    Science.gov (United States)

    Yücel, H.; Çubukçu, Ş.; Uyar, E.; Engin, Y.

    2014-11-01

    The energy dependence of the response of BC-408 plastic scintillator (PS), an approximately water-equivalent material, has been investigated by employing standardized x-ray beams. IEC RQA and ISO N series x-ray beam qualities, in the range of 40-100 kVp, were calibrated using a PTW-type ionization chamber. The energy response of a thick BC-408 PS detector was measured using the multichannel pulse height analysis method. The response of BC-408 PS increased gradually with increasing energy in the energy range of 40-80 kVp and then showed a flat behavior at about 80 to 120 kVp. This might be due to the self-attenuation of scintillation light by the scintillator itself and may also be partly due to the ionization quenching, leading to a reduction in the intensity of the light output from the scintillator. The results indicated that the sensitivity drop in BC-408 PS material at lower photon energies may be overcome by adding some high-Z elements to its polyvinyltoluene (PVT) base. The material modification may compensate for the drop in the response at lower photon energies. Thus plastic scintillation dosimetry is potentially suitable for applications in diagnostic radiology.

  18. Scintillation properties of LiF–SrF2 and LiF–CaF2 eutectic

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Kawaguchi, Noriaki; Fujimoto, Yutaka; Fukuda, Kentaro; Watanabe, Kenichi; Yamazaki, Atsushi; Uritani, Akira

    2013-01-01

    Dopant free eutectic scintillators 6 LiF–SrF 2 and 6 LiF–CaF 2 were developed by the vertical Bridgeman method for the purpose of thermal neutron detection. The molar ratio of LiF and Ca/SrF 2 was 4:1 on its eutectic composition. The α-ray induced radioluminescence spectra of the scintillators showed intense emission peak at 300 nm due to the emission from the self-trapped exciton in Ca/SrF 2 layers. When the samples were irradiated with 252 Cf neutrons, 6 LiF–SrF 2 and 6 LiF–CaF 2 exhibited the light yields of 4700 and 9400 ph/n, respectively. Scintillation decay times of 6 LiF–SrF 2 and 6 LiF–CaF 2 were accepted for scintillation detectors, 90 and 250 ns, respectively. -- Highlights: • Nondoped LiF–CaF 2 and LiF–SrF 2 eutectic scinitillators are reported for the first time. • Two sample showed self-trapped exciton emission. • LiF–SrF 2 sample exhibited the light yield of 9400 ph/n and this value was comparable to conventional materials doped with rare earth ions. • Scintillation decay times of LiF–CaF 2 and LiF–SrF 2 were 250 and 90 ns, respectively

  19. Preparation of ferric acetylacetonate, bonzonate and caprate labelled with Fe-55 and tests of application to liquid scintillation measurements

    International Nuclear Information System (INIS)

    Los Arcos, J.M.; Rodriguez Barquero, L.; Grau Malonda, A.

    1990-01-01

    The methods of preparation of ferric acetylacetonate, benzoate and caprate labelled with 55 Fe are described. The quenching effect, the spectral baehaviour and the count rate stability are studied by liquid scintillation measurements in toluene, INSTAGEL and HISAFE II, for two different values of the sample concentration. The ferric acetylaceton-ate is stable for all the three scintillators but shows a strong quench, while the ferric benzoate and caprate are stable only for INSTAGEL and HISAFE II showing no significant quench at the concentrat-ions of interest in habitual measurements. (Author)

  20. Development of High-Resolution Scintillator Systems

    International Nuclear Information System (INIS)

    Larry A. Franks; Warnick J. Kernan

    2007-01-01

    Mercuric iodide (HgI2) is a well known material for the direct detection of gamma-rays; however, the largest volume achievable is limited by the thickness of the detector which needs to be a small fraction of the average trapping length for electrons. We report results of using HgI2 crystals to fabricate photocells used in the readout of scintillators. The optical spectral response and efficiency of these photocells were measured and will be reported. Nuclear response from an HgI2 photocell that was optically matched to a cerium-activated scintillator is presented and discussed. Further improvements can be expected by optimizing the transparent contact technology

  1. Development of High-Resolution Scintillator Systems

    Energy Technology Data Exchange (ETDEWEB)

    Larry A. Franks; Warnick J. Kernan

    2007-09-01

    Mercuric iodide (HgI2) is a well known material for the direct detection of gamma-rays; however, the largest volume achievable is limited by the thickness of the detector which needs to be a small fraction of the average trapping length for electrons. We report results of using HgI2 crystals to fabricate photocells used in the readout of scintillators. The optical spectral response and efficiency of these photocells were measured and will be reported. Nuclear response from an HgI2 photocell that was optically matched to a cerium-activated scintillator is presented and discussed. Further improvements can be expected by optimizing the transparent contact technology.

  2. Scintillation detectors of Alborz-I experiment

    International Nuclear Information System (INIS)

    Pezeshkian, Yousef; Bahmanabadi, Mahmud; Abbasian Motlagh, Mehdi; Rezaie, Masume

    2015-01-01

    A new air shower experiment of the Alborz Observatory, Alborz-I, located at the Sharif University of Technology, Iran, will be constructed in near future. An area of about 30×40 m 2 will be covered by 20 plastic scintillation detectors (each with an area of 50×50 cm 2 ). A series of experiments have been performed to optimize the height of light enclosures of the detectors for this array and the results have been compared to an extended code simulation of these detectors. Operational parameters of the detector obtained by this code are cross checked by the Geant4 simulation. There is a good agreement between the extended-code and Geant4 simulations. We also present further discussions on the detector characteristics, which can be applicable for all scintillation detectors with a similar configuration

  3. Central Tracking Detector Based on Scintillating Fibres

    CERN Multimedia

    2002-01-01

    Scintillating fibres form a reasonable compromise for central tracking detectors in terms of price, resolution, response time, occupancy and heat production. \\\\ \\\\ New fluorescents with large Stokes shifts have been produced, capable of working without wavelength shifters. Coherent multibundles have been developed to achieve high packing fractions. Small segments of tracker shell have been assembled and beam tests have confirmed expectations on spatial resolution. An opto-electronic delay line has been designed to delay the track patterns and enable coincidences with a first level trigger. Replacement of the conventional phosphor screen anode with a Si pixel chip is achieved. This tube is called ISPA-tube and has already been operated in beam tests with a scintillating fibres tracker. \\\\ \\\\ The aim of the proposal is to improve hit densities for small diameter fibres by increasing the fraction of trapped light, by reducing absorption and reflection losses, by reflecting light at the free fibre end, and by inc...

  4. Multifrequency techniques for studying interplanetary scintillations

    International Nuclear Information System (INIS)

    Woo, R.

    1975-01-01

    Rytov's approximation or the method of smooth perturbations is utilized to derive the temporal frequency spectra of the amplitude and phase fluctuations of multifrequency plane and spherical waves propagating in the interplanetary medium and solar corona. It is shown that multifrequency observations of interplanetary scintillations using either compact radio stars or spacecraft radio signals are desirable because the correlation of the multifrequency waves yields additional independent measurements of the solar wind and turbulence. Measurements of phase fluctuations are also desirable because, unlike amplitude fluctuations, they provide information on the full range of scale sizes for the electron density fluctuations. It is shown that a coherent dual-frequency radio system is particularly useful in making such measurements. In addition to providing a means for interpreting observations of multifrequency interplanetary scintillations, the analysis is also essential for estimating the effects of solar corona turbulence on the communications and navigation of a spacecraft whose line-of-sight path passes close to the Sun

  5. Background characterization in a liquid scintillation spectrometer

    International Nuclear Information System (INIS)

    Rodriguez Barquero, L.; Los Arcos, J.M.; Jimenez de Mingo, A.

    1995-01-01

    An alternate procedure for background count rate estimation in a liquid scintillation spectrometer is presented, which does not require to measure a blank with similar composition, volume and quench, to the problem sample. The procedure is based on a double linear parameterization which was obtained from a systematic study of the background observed with glass vials, in three different windows, 0 - 20 KeV, 0 - 800 KeV and 0 - 2 MeV, for volume between 2 and 20 mi of three commercial scintillators, Hisafe II, Ultima-Gold and Instagel, and quenching degree in the interval equivalent to 50% - 3% tritium efficiency. This procedure was tested with standard samples of 3H, and led to average discrepancies less than 10% for activity ≥0,6 Bq, against conventional methods for which the discrepancies are twice on average. (Author) 10 refs

  6. Background characterization in a liquid scintillation spectrometer

    International Nuclear Information System (INIS)

    Rodriguez Barquero, L.; Los arcos, J.M.; Jimenez de Mingo, A.

    1995-01-01

    An alternate procedure for background count rate estimation in a liquid scintillation spectrometer is presented, which does not require to measure a blank with similar composition, volume and quench, to the problem sample. The procedure is based on a double linear parameterization which was obtained from a systematic study of the background observed with glass vials, in three different windows, 0-20 KeV, 0-800 KeV and 0-2 MeV, for volume between 2 and 20 ml of three commercial scintillators, Hisafe II, Ultima-gold and Instagel, and quenching degree in the interval equivalent to 50%-3% tritium efficiency. This procedure was tested with standard samples of ''3 H, and led to average discrepancies less than 10% for activity => 0,6 Bq, against conventional methods for which the discrepancies are twice on average

  7. Calibration of the neutron scintillation counter threshold

    International Nuclear Information System (INIS)

    Noga, V.I.; Ranyuk, Yu.N.; Telegin, Yu.N.

    1978-01-01

    A method for calibrating the threshold of a neutron counter in the form of a 10x10x40 cm plastic scintillator is described. The method is based on the evaluation of the Compton boundary of γ-spectrum from the discrimination curve of counter loading. The results of calibration using 60 Co and 24 Na γ-sources are given. In order to eValuate the Compton edge rapidly, linear extrapolation of the linear part of the discrimination curve towards its intersection with the X axis is recommended. Special measurements have shown that the calibration results do not practically depend on the distance between the cathode of a photomultiplier and the place where collimated γ-radiation of the calibration source reaches the scintillator

  8. A study of scintillation beta microprobes

    Science.gov (United States)

    Woody, C. L.; Stoll, S. P.; Schlyer, D. J.; Gerasimov, M.; Vaska, P.; Shokouhi, S.; Volkow, N.; Fowler, J. S.; Dewey, S. L.

    2002-10-01

    Several types of scintillation microprobes have recently been developed to directly measure positron activity from radiotracers in live animals. These probes consist of either a small lutetium oxyorthosilicate (LSO) crystal or plastic scintillator coupled to an optical fiber that is read out with a photomultiplier tube operated in a single photon counting mode. In this paper, a comparison is made between the two types of probes in terms of their sensitivity to both positrons and gammas. It was found that LSO offers very high sensitivity to positrons due to its high density and light output, and allows the construction of very small probes for certain applications. The LSO probe can also provide effective discrimination between positrons and gammas, and provide better localization of positron decays, using pulse height discrimination. Results are also given on the use of the microprobe on live laboratory animals.

  9. Scintillating Optical Fiber Imagers for biology

    International Nuclear Information System (INIS)

    Mastrippolito, R.

    1990-01-01

    S.O.F.I (Scintillating Optical Fiber Imager) is a detector developed to replace the autoradiographic films used in molecular biology for the location of radiolabelled ( 32 P) DNA molecules in blotting experiments. It analyses samples on a 25 x 25 cm 2 square area still 25 times faster than autoradiographic films, with a 1.75 and 3 mm resolution for two orthogonal directions. This device performs numerised images with a dynamic upper than 100 which allows the direct quantitation of the analysed samples. First, this thesis describes the S.O.F.I. development (Scintillating Optical Fibers, coding of these fibers and specific electronic for the treatment of the Multi-Anode Photo-Multiplier signals) and experiments made in collaboration with molecular biology laboratories. In a second place, we prove the feasibility of an automatic DNA sequencer issued from S.O.F.I [fr

  10. Improved Neutron Scintillators Based on Nanomaterials

    International Nuclear Information System (INIS)

    Friesel, Dennis

    2008-01-01

    The development work conducted in this SBIR has so far not supported the premise that using nano-particles in LiFZnS:Ag foils improves their transparency to 420 (or other frequency) light. This conclusion is based solely on the light absorption properties of LiFZnS foils fabricated from nano- and from micro-particles. Furthermore, even for the case of the Gd 2 O 3 foils, the transmission of 420 nm light gained by using nano-particles all but disappears as the foil thickness is increased beyond about 0.2 mm, a practical scintillator thickness. This was not immediately apparent from the preliminary study since no foils thicker than about 0.04 mm were produced. Initially it was believed that the failure to see an improvement by using nano-particles for the LiFZnS foils was caused by the clumping of the particles in Toluene due to the polarity of the ZnS particles. However, we found, much to our surprise, that nano-particle ZnS alone in polystyrene, and in Epoxy, had worse light transmission properties than the micro-particle foils for equivalent thickness and density foils. The neutron detection measurements, while disappointing, are attributable to our inability to procure or fabricate Bulk Doped ZnS nanoparticles. The cause for the failure of nano-particles to improve the scintillation light, and hence improved neutron detection efficiency, is a fundamental one of light scattering within the scintillator. A consequence of PartTec's documentation of this is that several concepts for the fabrication of improved 6 LiFZnS scintillators were formulated that will be the subject of a future SBIR submission.

  11. Prompt angle measurements with large aperture scintillators

    International Nuclear Information System (INIS)

    Schneid, E.J.

    1976-01-01

    A technique is described for the measurement of particle trajectory angle through a pair of scintillator tiles. Signal processing provides an analog signal proportional to the tangent of the angle between the particle trajectory and the axis normal to the pair of tiles. This signal is readily available for use in fast decision logic if required: i.e., sorting energy loss signals from the tiles according to geometrical factors or restricting the events to be analyzed on the basis of incident direction

  12. Improved Neutron Scintillators Based on Nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Dennis Friesel, PhD

    2008-06-30

    The development work conducted in this SBIR has so far not supported the premise that using nano-particles in LiFZnS:Ag foils improves their transparency to 420 (or other frequency) light. This conclusion is based solely on the light absorption properties of LiFZnS foils fabricated from nano- and from micro-particles. Furthermore, even for the case of the Gd{sub 2}O{sub 3} foils, the transmission of 420 nm light gained by using nano-particles all but disappears as the foil thickness is increased beyond about 0.2 mm, a practical scintillator thickness. This was not immediately apparent from the preliminary study since no foils thicker than about 0.04 mm were produced. Initially it was believed that the failure to see an improvement by using nano-particles for the LiFZnS foils was caused by the clumping of the particles in Toluene due to the polarity of the ZnS particles. However, we found, much to our surprise, that nano-particle ZnS alone in polystyrene, and in Epoxy, had worse light transmission properties than the micro-particle foils for equivalent thickness and density foils. The neutron detection measurements, while disappointing, are attributable to our inability to procure or fabricate Bulk Doped ZnS nanoparticles. The cause for the failure of nano-particles to improve the scintillation light, and hence improved neutron detection efficiency, is a fundamental one of light scattering within the scintillator. A consequence of PartTec's documentation of this is that several concepts for the fabrication of improved {sup 6}LiFZnS scintillators were formulated that will be the subject of a future SBIR submission.

  13. Interaction probability value calculi for some scintillators

    International Nuclear Information System (INIS)

    Garcia-Torano Martinez, E.; Grau Malonda, A.

    1989-01-01

    Interaction probabilities for 17 gamma-ray energies between 1 and 1.000 KeV have been computed and tabulated. The tables may be applied to the case of cylindrical vials with radius 1,25 cm and volumes 5, 10 and 15 ml. Toluene, Toluene/Alcohol, Dioxane-Naftalen, PCS, INSTAGEL and HISAFE II scintillators are considered. Graphical results for 10 ml are also given. (Author) 11 refs

  14. Development of a reference liquid scintillation cocktail

    CSIR Research Space (South Africa)

    Van Wyn Gaardt, WM

    2006-02-01

    Full Text Available for Ionizing Radiation CCRI(II). The system will be maintained at the International Bureau of Weights and Measures (BIPM), France. The system requires a non-commercial reference liquid scintillation cocktail, the development of which is described here. A... Committee for Ionizing Radiation (CCRI(II)) of the International Committee of Weights and Measures (CIPM) enables laboratories to do this by organising comparisons of the activity measurements of a given radionuclide solution. Alternatively...

  15. Nanophosphor composite scintillators comprising a polymer matrix

    Science.gov (United States)

    Muenchausen, Ross Edward; Mckigney, Edward Allen; Gilbertson, Robert David

    2010-11-16

    An improved nanophosphor composite comprises surface modified nanophosphor particles in a solid matrix. The nanophosphor particle surface is modified with an organic ligand, or by covalently bonding a polymeric or polymeric precursor material. The surface modified nanophosphor particle is essentially charge neutral, thereby preventing agglomeration of the nanophosphor particles during formation of the composite material. The improved nanophosphor composite may be used in any conventional scintillator application, including in a radiation detector.

  16. Scintillator materials-achievements, opportunities, and puzzles

    Czech Academy of Sciences Publication Activity Database

    Nikl, Martin; Mihóková, Eva; Pejchal, Jan; Vedda, A.; Fasoli, M.; Fontana, I.; Laguta, Valentyn; Babin, V.; Nejezchleb, K.; Yoshikawa, A.; Ogino, H.; Ren, G.

    2008-01-01

    Roč. 55, č. 3 (2008), s. 1035-1045 ISSN 0018-9499 R&D Projects: GA MŠk ME 903; GA MŠk ME 953; GA ČR GA202/05/2471; GA AV ČR 1QS100100506 Institutional research plan: CEZ:AV0Z10100521 Keywords : scintillator * Ce 3+ and Pr 3+ doped * traps * complex oxide Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.518, year: 2008

  17. Organic Scintillation Detectors for Spectroscopic Radiation Portal Monitors

    Science.gov (United States)

    Paff, Marc Gerrit

    Thousands of radiation portal monitors have been deployed worldwide to detect and deter the smuggling of nuclear and radiological materials that could be used in nefarious acts. Radiation portal monitors are often installed at bottlenecks where large amounts of people or goods must traverse. Examples of use include scanning cargo containers at shipping ports, vehicles at border crossings, and people at high profile functions and events. Traditional radiation portal monitors contain separate detectors for passively measuring neutron and gamma ray count rates. 3He tubes embedded in polyethylene and slabs of plastic scintillators are the most common detector materials used in radiation portal monitors. The radiation portal monitor alarm mechanism relies on measuring radiation count rates above user defined alarm thresholds. These alarm thresholds are set above natural background count rates. Minimizing false alarms caused by natural background and maximizing sensitivity to weakly emitting threat sources must be balanced when setting these alarm thresholds. Current radiation portal monitor designs suffer from frequent nuisance radiation alarms. These radiation nuisance alarms are most frequently caused by shipments of large quantities of naturally occurring radioactive material containing cargo, like kitty litter, as well as by humans who have recently undergone a nuclear medicine procedure, particularly 99mTc treatments. Current radiation portal monitors typically lack spectroscopic capabilities, so nuisance alarms must be screened out in time-intensive secondary inspections with handheld radiation detectors. Radiation portal monitors using organic liquid scintillation detectors were designed, built, and tested. A number of algorithms were developed to perform on-the-fly radionuclide identification of single and combination radiation sources moving past the portal monitor at speeds up to 2.2 m/s. The portal monitor designs were tested extensively with a variety of

  18. New scintillating crystals for PET scanners

    CERN Document Server

    Lecoq, P

    2002-01-01

    Systematic R&D on basic mechanism in inorganic scintillators, initiated by the Crystal Clear Collaboration at CERN 10 years ago, has contributed not to a small amount, to the development of new materials for a new generation of medical imaging devices with increased resolution and sensitivity. The first important requirement for a scintillator to be used in medical imaging devices is the stopping power for the given energy range of X and gamma rays to be considered, and more precisely the conversion efficiency. A high light yield is also mandatory to improve the energy resolution, which is essentially limited by the photostatistics and the electronic noise at these energies. A short scintillation decay time allows to reduce the dead time and therefore to increase the limiting counting rate. When all these requirements are fulfilled the sensitivity and image contrast are increased for a given patient dose, or the dose can be reduced. Examples of new materials under development by the Crystal Clear Collabor...

  19. Boron-Loaded Silicone Rubber Scintillators

    CERN Document Server

    Bell, Z W; Maya, L; Sloop, F V J

    2003-01-01

    Silicone rubber received attention as an alternative to polyvinyltoluene in applications in which the scintillator is exposed to high doses because of the increased resistance of the rubber to the formation of blue-absorbing color centers. Work by Bowen, et al., and Harmon, et al., demonstrated their properties under gamma/x-ray irradiation, and Bell, et al. have shown their response to thermal neutrons. This last work, however, provided an example of a silicone in which both the boron and the scintillator were contained in the rubber as solutes, a formulation which led to the precipitation of solids and sublimation of the boron component. In the present work we describe a scintillator in which the boron is chemically bonded to the siloxane and so avoids the problem of precipitation and loss of boron to sublimation. Material containing up to 18% boron, by weight, was prepared, mounted on photomultipliers, and exposed to both neutron and gamma fluxes. Pulse height spectra showing the neutron and photon respons...

  20. Liquid-scintillation alpha-detection techniques

    International Nuclear Information System (INIS)

    McKlveen, J.W.; McDowell, W.J.

    1983-01-01

    Accurate, quantitative determinations of alpha-emitting nuclides by conventional plate-counting methods are difficult because of sample self-absorption problems in counting and because of non-reproducible losses in conventional sample separation methods. Liquid scintillation alpha spectrometry offers an attractive with no sample self-absorption or geometry problems and with 100% counting efficiency. Sample preparation may include extraction of the alpha emitter of interest by a specific organic-phase-soluble compound directly into the liquid scintillation counting medium. Detection electronics use energy and pulse-shape discrimination to yield alpha spectra without beta and gamma background interference. Specific procedures have been developed for gross alpha, uranium, plutonium, thorium, and polonium assay. Possibilities for a large number of other applications exist. Accuracy and reproducibility are typically in the 1% range. Backgrounds on the order of 0.01 cpm are readily achievable. The paper will present an overview of liquid scintillation alpha counting techniques and some of the results achieved for specific applications

  1. Composition for use in scintillator systems

    International Nuclear Information System (INIS)

    Tarkkanen, V.

    1976-01-01

    Reference is made to compositions for liquid scintillation counting of aqueous radioactive samples. A composition is described that reduces chemiluminescence on the addition of an alkaline material. Many common sample materials, for example body fluids, are inherently alkaline, whilst samples such as animal tissues are often dissolved in alkaline media. Another problem is water miscibility, and the object is to provide a scintillation counting composition that, when mixed with an aqueous sample, produces a single phase low viscosity mixture over a wide range of water contents and temperatures. The composition described includes a major amount of an aromatic hydrocarbon solvent, a minor amount of an ethoxylated alkyl phenol surfactant, a scintillation solute, an amount of a substituted ethoxylated carboxylic acid sufficient to reduce chemiluminescence, and an amount of a tertiary amine salt or a quaternary ammonium salt of the substituted ethoxylated carboxylic acid sufficient to enhance the water miscibility. The hydrocarbon solvent and the surfactant may be pre-treated with a reactive solid metal hydride to remove peroxides, and then subsequently pre-treated with SO 2 . Examples of the use of the composition are given. (U.K)

  2. Boron-Loaded Silicone Rubber Scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Z.W.; Maya, L.; Brown, G.M.; Sloop, F.V.Jr

    2003-05-12

    Silicone rubber received attention as an alternative to polyvinyltoluene in applications in which the scintillator is exposed to high doses because of the increased resistance of the rubber to the formation of blue-absorbing color centers. Work by Bowen, et al., and Harmon, et al., demonstrated their properties under gamma/x-ray irradiation, and Bell, et al. have shown their response to thermal neutrons. This last work, however, provided an example of a silicone in which both the boron and the scintillator were contained in the rubber as solutes, a formulation which led to the precipitation of solids and sublimation of the boron component. In the present work we describe a scintillator in which the boron is chemically bonded to the siloxane and so avoids the problem of precipitation and loss of boron to sublimation. Material containing up to 18% boron, by weight, was prepared, mounted on photomultipliers, and exposed to both neutron and gamma fluxes. Pulse height spectra showing the neutron and photon response were obtained, and although the light output was found to be much poorer than from samples in which boron was dissolved, the higher boron concentrations enabled essentially 100% neutron absorption in only a few millimeters' thickness of rubber.

  3. Scintillation counter with MRS APD light readout

    International Nuclear Information System (INIS)

    Akindinov, A.; Bondarenko, G.; Golovin, V.; Grigoriev, E.; Grishuk, Yu.; Mal'kevich, D.; Martemiyanov, A.; Ryabinin, M.; Smirnitskiy, A.; Voloshin, K.

    2005-01-01

    START, a high-efficiency and low-noise scintillation detector for ionizing particles, was developed for the purpose of creating a high-granular system for triggering cosmic muons. Scintillation light in START is detected by MRS APDs (Avalanche Photo-Diodes with Metal-Resistance-Semiconductor Structure), operated in the Geiger mode, which have 1mm 2 sensitive areas. START is assembled from a 15x15x1cm 3 scintillating plastic plate, two MRS APDs and two pieces of wavelength-shifting optical fiber stacked in circular coils inside the plastic. The front-end electronic card is mounted directly on the detector. Tests with START have confirmed its operational consistency, over 99% efficiency of MIP registration and good homogeneity. START demonstrates a low intrinsic noise of about 10 -2 Hz. If these detectors are to be mass-produced, the cost of a mosaic array of STARTs is estimated at a moderate level of 2-3kUSD/m 2

  4. Temperature quenching in LAB based liquid scintillator

    Science.gov (United States)

    Sörensen, A.; Hans, S.; Junghans, A. R.; Krosigk, B. v.; Kögler, T.; Lozza, V.; Wagner, A.; Yeh, M.; Zuber, K.

    2018-01-01

    The effect of temperature changes on the light output of LAB based liquid scintillator is investigated in a range from -5 to 30°C with α -particles and electrons in a small scale setup. Two PMTs observe the scintillator liquid inside a cylindrically shaped aluminum cuvette that is heated or cooled and the temperature dependent PMT sensitivity is monitored and corrected. The α -emitting isotopes in dissolved radon gas and in natural Samarium (bound to a LAB solution) excite the liquid scintillator mixtures and changes in light output with temperature variation are observed by fitting light output spectra. Furthermore, also changes in light output by compton electrons, which are generated from external calibration γ -ray sources, is analysed with varying temperature. Assuming a linear behaviour, a combined negative temperature coefficient of {(-0.29 ± 0.01)}{ %/°}C is found. Considering hints for a particle type dependency, electrons show {(-0.17 ± 0.02)}{ %/°}C, whereas the temperature dependency seems stronger for α -particles, with {(-0.35 ± 0.03)}{ %/°}C. Due to a high sampling rate, a pulse shape analysis can be performed and shows an enhanced slow decay component at lower temperatures, pointing to reduced non-radiative triplet state de-excitations.

  5. Neutron scintillators using wavelength shifting fibers

    International Nuclear Information System (INIS)

    Hutchinson, D.P.; Miller, V.C.; Ramsey, J.A.

    1995-01-01

    A proposed design for an optically-based, one-dimension scintillation detector to replace the gas-filled position-sensitive proportional counter currently used for a wide-angle neutron detector (WAND) at the high-Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) is presented. The scintillator, consisting of a mixture of 6 LiF and ZnS(Ag) powders in an epoxy binder, is coupled to an array of wavelength shifting optical fibers which provide position resolution. The wide-angle neutron detector is designed to cover a 120 degree arc with a 75 cm radius of curvature. The final detector design provides for 600 optical fibers coupled to the scintillator screen with an angular resolution of 0.2 degrees. Each individual pixel of the detector will be capable of operating at count rates exceeding 1 MHz. Results are presented from the measurement of neutron conversion efficiencies for several screen compositions, gamma-ray sensitivity, and spatial resolution of a 16 element one-dimensional array prototype

  6. B-Loaded Plastic Scintillator on the Base of Polystyrene

    CERN Document Server

    Brudanin, V B; Nemchenok, I B; Smolnikov, A A

    2000-01-01

    A method to produce polystyrene-based plastic scintillators with boron concentration from 0.38 to 5.0% of boron have been developed. o-Carborane was used as B-containing additive. The results of investigations of the optical, spectral and scintillation characteristics are presented and discussed. It is shown that 5% B-loaded scintillator has a light output as much as 70% relative to the unloaded one. High efficiency for thermal neutron registration achieved for produced samples makes it possible to use such scintillators in complex neutron high sensitive spectrometers. Measured level of radioactive contamination in this scintillation materials is good enough for using the B-loaded scintillators in the proposed large scale neutrino experiments.

  7. Characteristics of plastic scintillators fabricated by a polymerization reaction

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Cheol Ho; Son, Jaebum; Kim, Tae Hoon; Kim, Yong Kyun [Dept. of Nuclear Engineering, Hanyang University, Seoul (Korea, Republic of)

    2017-04-15

    Three plastic scintillators of 4.5 cm diameter and 2.5-cm length were fabricated for comparison with commercial plastic scintillators using polymerization of the styrene monomer 2.5-diphenyloxazole (PPO) and 1,4-bis benzene (POPOP). Their maximum emission wavelengths were determined at 426.06 nm, 426.06 nm, and 425.00 nm with a standard error of 0.2% using a Varian spectrophotometer (Agilent, Santa Clara, CA, USA). Compton edge spectra were measured using three gamma ray sources [i.e., cesium 137 ({sup 137}Cs), sodium 22 ({sup 22}Na), and cobalt 60 ({sup 60}Co)]. Energy was calibrated by analyzing the Compton edge spectra. The fabricated scintillators possessed more than 99.7% energy linearity. Light output was comparable to that of the BC-408 scintillator (Saint-Gobain, Paris, France). The fabricated scintillators showed a light output of approximately 59–64% of that of the BC-408 scintillator.

  8. A New Neutron Calibration Technique with Fast Scintillators on DIII-D Tokamak

    Science.gov (United States)

    Zhu, Y. B.; Heidbrink, W. W.; Taylor, P. L.; Carrig, W.

    2015-11-01

    Absolute calibrations are necessary for conventional neutron measurements based on proportional counters and fission chambers, at regular intervals. For the DIII-D tokamak, the wide span of fusion rates, approximately between 1.e9 - 1.e17 neutrons per second, from pure Ohmic to high power auxiliary heating plasmas requires careful cross-calibrations of a variety of neutron detectors with stepwise and overlapped sensitivities, with an intense isotope neutron source, e.g. californium-252 and real plasmas. Scintillators have been successfully utilized for fast time resolved neutron detection for decades. A new calibration approach with the help of scintillators is shown to be straightforward, simpler and trustworthy while the conventional approach is complicated, time consuming and costly. Details on the calibration setup and results will be presented. Supported by US DOE SC-G903402 and DE-FC02-04ER54698.

  9. Growth and scintillation properties of Pr doped YAP with different Pr concentrations

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Kamada, Kei; Fujimoto, Yutaka; Sugiyama, Makoto; Furuya, Yuki; Yamaji, Akihiro; Yokota, Yuui; Yoshikawa, Akira

    2010-01-01

    Pr 3+ 0.2, 0.75, and 3 mol% doped YAP single crystalline scintillators were grown by using the micro-pulling down (μ-PD) method. Pr 3+ 0.05 mol% doped YAP was also prepared by using the Czochralski method. In transmittance spectra, 4f-5d absorption line appeared at 230 nm. The μ-PD grown crystals showed intense emission at 290 nm while the Czochralski grown one showed an emission peak at 245 nm in radio luminescence spectra under X-ray excitation. Among them, the Czochralski grown one exhibited the highest light yield under 137 Cs 662 keV excitation and the absolute light yield of this sample was estimated to be 20400±2000 ph/MeV. The decay time constants of these scintillators were around 10 ns due to Pr 3+ 5d-4f transition.

  10. Growth and scintillation properties of Pr doped YAP with different Pr concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Yanagida, Takayuki, E-mail: t_yanagi@tagen.tohoku.ac.j [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Kamada, Kei; Fujimoto, Yutaka; Sugiyama, Makoto; Furuya, Yuki [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yamaji, Akihiro [New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Yokota, Yuui [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yoshikawa, Akira [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

    2010-11-21

    Pr{sup 3+} 0.2, 0.75, and 3 mol% doped YAP single crystalline scintillators were grown by using the micro-pulling down ({mu}-PD) method. Pr{sup 3+} 0.05 mol% doped YAP was also prepared by using the Czochralski method. In transmittance spectra, 4f-5d absorption line appeared at 230 nm. The {mu}-PD grown crystals showed intense emission at 290 nm while the Czochralski grown one showed an emission peak at 245 nm in radio luminescence spectra under X-ray excitation. Among them, the Czochralski grown one exhibited the highest light yield under {sup 137}Cs 662 keV excitation and the absolute light yield of this sample was estimated to be 20400{+-}2000 ph/MeV. The decay time constants of these scintillators were around 10 ns due to Pr{sup 3+} 5d-4f transition.

  11. Scintillation of partially coherent Gaussian—Schell model beam propagation in slant atmospheric turbulence considering inner- and outer-scale effects

    International Nuclear Information System (INIS)

    Li Ya-Qing; Wu Zhen-Sen; Zhang Yuan-Yuan; Wang Ming-Jun

    2014-01-01

    Based on the modified Rytov theory and the international telecommunication union-radio (ITU-R) slant atmospheric structure constant model, the uniform scintillation index of partially coherent Gaussian—Schell model (GSM) beam propagation in the slant path is derived from weak- to strong-turbulence regions considering inner- and outer-scale effects. The effects of wavelength of beams and inner- and outer-scale of turbulence on scintillation are analyzed numerically. Comparison between the scintillation of GSM beams under the von Karman spectrum and that of beams under the modified Hill spectrum is made. The results obtained show that the scintillation index obtained under the von Karman spectrum is smaller than that under the modified Hill spectrum. This study can find theory bases for the experiments of the partially coherent GSM beam propagation through atmospheric turbulence. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  12. Preparation and characterization of highly lead-loaded red plastic scintillators under low energy x-rays

    Energy Technology Data Exchange (ETDEWEB)

    Hamel, Matthieu, E-mail: matthieu.hamel@cea.fr [CEA, LIST, Laboratoire Capteurs et Architectures Electroniques, F-91191 Gif-sur-Yvette Cedex (France); Turk, Gregory [LCPMR, UPMC, CNRS UMR 7614, 11 rue Pierre et Marie Curie, F-75231 PARIS Cedex 5 (France); Rousseau, Adrien; Darbon, Stephane; Reverdin, Charles [CEA, DAM, DIF, F-91297 Arpajon (France); Normand, Stephane [CEA, LIST, Laboratoire Capteurs et Architectures Electroniques, F-91191 Gif-sur-Yvette Cedex (France)

    2011-12-21

    To the aim of development of a spatially resolved x-ray imaging system intended for Inertial Confinement Fusion (ICF) experiments at the Laser Mega Joule (LMJ) facility, new plastic scintillators have been designed. The main characteristics are the following: fast decay time, red emission and good x-rays photoelectric absorption in the range 10-40 keV. These scintillators are synthesized by copolymerization of different monomers with an organometallic compound. In this matrix two fluorescent compounds are embedded, allowing to shift the energy from the UV to the near IR spectrum. Several parameters were studied: fluorophores concentration, nature of the secondary fluorophore and lead concentration. An outstanding effective atomic number of 53 has been reached, for a loading of lead corresponding to 29 wt%. Thus, small cylinders were prepared and their performances under x-ray beam studied and compared with those of inorganic Cerium-doped Yttrium Aluminum Garnet reference scintillator (Y{sub 3}Al{sub 5}O{sub 12}:Ce{sup 3+}). Eventually, such new scintillators or their next generation could replace expensive and brittle inorganic scintillators, inducing a strong industrial potential.

  13. A Scintillator Purification System for the Borexino Solar Neutrino Detector

    OpenAIRE

    Benziger, J.; Cadonati, L.; Calaprice, F.; Chen, M.; Corsi, A.; Dalnoki-Veress, F.; Fernholz, R.; Ford, R.; Galbiati, C.; Goretti, A.; Harding, E.; Ianni, Aldo; Ianni, Andrea; Kidner, S.; Leung, M.

    2007-01-01

    Purification of the 278 tons of liquid scintillator and 889 tons of buffer shielding for the Borexino solar neutrino detector was performed with a system that combined distillation, water extraction, gas stripping and filtration. The purification of the scintillator achieved unprecedented low backgrounds for the large scale liquid scintillation detector. This paper describes the principles of operation, design, construction and commissioning of the purification system, and reviews the require...

  14. Progress in Scintillating Polarized Targets for Spin Physics

    Science.gov (United States)

    van den Brandt, B.; Hautle, P.; Konter, J. A.; Bunyatova, E. I.

    2003-06-01

    At PSI polarized scintillating targets have been operated in several particle physics experiments over extended periods of time. They proved to be very robust and reliable. Proton polarizations of more than 80%, and deuteron polarizations of 25% in fully deuterated polystyrene based scintillator have been reached in a vertical dilution refrigerator with optical access. New choices of materials and preparation procedures show potential for an improvement of the scintillation and polarization properties.

  15. Paraffin scintillator for radioassay of solid support samples

    International Nuclear Information System (INIS)

    Fujii, Haruo; Takiue, Makoto

    1989-01-01

    A new paraffin scintillator used for solid support sample counting has been proposed, and its composition and various characteristics are described. The solid support sample treated with this scintillator can be easily handled because of rigid sample conditions. This technique provides great advantages such as the elimination of a large volume of scintillator and little radioactive waste material by using an economical polyethylene bag instead of the conventional counting vial. (author)

  16. Structural Origins of Scintillation: Metal Organic Frameworks as a Nanolaboratory

    Science.gov (United States)

    2016-06-01

    discrimination (PSD), for which the prompt component of the scintillation response is quenched for high specific energy loss (dE/dX) particles such as protons...for neutron discrimination (LDRD, $250k/year, FY10) - MOF-based scintillators (NA-22, ~600k / year, FY10-FY12) - Triplet-Harvesting doped plastic ...Structural Origins of Scintillation : Metal Organic Frameworks as a Nanolaboratory Distribution Statement A. Approved for public release

  17. Liquid emulsion scintillators which solidify for facile disposal

    International Nuclear Information System (INIS)

    O'Brien, R.E.; Krieger, J.K.

    1981-01-01

    A liquid organic scintillation cocktail is described which counts solutions of radiolabelled compounds containing up to ten % by volume of water with high efficiency and is readily polymerizable to a solid for easy disposal. The cocktail comprises a polymerizable organic solvent, a solubilizing agent, an intermediate solvent, and an organic scintillator. A method of disposing of liquid organic scintillation cocktail waste and a kit useful for practising the method are also described. (U.K.)

  18. Growth and scintillation properties of gadolinium and yttrium orthovanadate crystals

    International Nuclear Information System (INIS)

    Voloshina, O.V.; Baumer, V.N.; Bondar, V.G.; Kurtsev, D.A.; Gorbacheva, T.E.; Zenya, I.M.; Zhukov, A.V.; Sidletskiy, O.Ts.

    2012-01-01

    Aiming to explore the possibility of using the undoped rare-earth orthovanadates as scintillation materials, we developed the procedure for growth of gadolinium (GdVO 4 ) and yttrium (YVO 4 ) orthovanadate single crystals by Czochralski method, and determined the optimal conditions of their after-growth annealing. Optical, luminescent, and scintillation properties of YVO 4 and GdVO 4 were discussed versus known literature data. Scintillation characteristics of GdVO 4 were determined for the first time.

  19. Waveguide generated mitigation of speckle and scintillation on an actively illuminated target

    Science.gov (United States)

    Moore, Trevor D.; Raynor, Robert A.; Spencer, Mark F.; Schmidt, Jason D.

    2016-09-01

    Active illumination is often used when passive illumination cannot produce enough signal intensity to be a reliable imaging method. However, an increase in signal intensity is often achieved by using highly coherent laser sources, which produce undesirable effects such as speckle and scintillation. The deleterious effects of speckle and scintillation are often so immense that the imaging camera cannot receive intelligible data, thereby rendering the active illumination technique useless. By reducing the spatial coherence of the laser beam that is actively illuminating the object, it is possible to reduce the corruption of the received data caused by speckle and scintillation. The waveguide method discussed in this paper reduces spatial coherence through multiple total internal reflections, which create multiple virtual sources of diverse path lengths. The differing path lengths between the virtual sources and the target allow for the temporal coherence properties of the laser to be translated into spatial coherence properties. The resulting partial spatial coherence helps to mitigate the self-interference of the beam as it travels through the atmosphere and reflects off of optically rough targets. This mitigation method results in a cleaner, intelligible image that may be further processed for the intended use, unlike its unmitigated counterpart. Previous research has been done to independently reduce speckle or scintillation by way of spatial incoherence, but there has been no focus on modeling the waveguide, specifically the image plane the waveguide creates. Utilizing a ray-tracing method we can determine the coherence length of the source necessary to create incoherent spots in the image plane, as well as accurately modeling the image plane.

  20. Ionospheric scintillation observations over Kenyan region - Preliminary results

    Science.gov (United States)

    Olwendo, O. J.; Xiao, Yu; Ming, Ou

    2016-11-01

    Ionospheric scintillation refers to the rapid fluctuations in the amplitude and phase of a satellite signal as it passes through small-scale plasma density irregularities in the ionosphere. By analyzing ionospheric scintillation observation datasets from satellite signals such as GPS signals we can study the morphology of ionospheric bubbles. At low latitudes, the diurnal behavior of scintillation is driven by the formation of large-scale equatorial density depletions which form one to two hours after sunset via the Rayleigh-Taylor instability mechanism near the magnetic equator. In this work we present ionospheric scintillation activity over Kenya using data derived from a newly installed scintillation monitor developed by CRIRP at Pwani University (39.78°E, 3.24°S) during the period August to December, 2014. The results reveal the scintillation activity mainly occurs from post-sunset to post-midnight hours, and ceases around 04:00 LT. We also found that the ionospheric scintillation tends to appear at the southwest and northwest of the station. These locations coincide with the southern part of the Equatorial Ionization Anomaly crest over Kenya region. The occurrence of post-midnight L-band scintillation events which are not linked to pre-midnight scintillation observations raises fundamental question on the mechanism and source of electric fields driving the plasma depletion under conditions of very low background electron density.

  1. Large-scale liquid scintillation detectors for solar neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Benziger, Jay B.; Calaprice, Frank P. [Princeton University Princeton, Princeton, NJ (United States)

    2016-04-15

    Large-scale liquid scintillation detectors are capable of providing spectral yields of the low energy solar neutrinos. These detectors require > 100 tons of liquid scintillator with high optical and radiopurity. In this paper requirements for low-energy neutrino detection by liquid scintillation are specified and the procedures to achieve low backgrounds in large-scale liquid scintillation detectors for solar neutrinos are reviewed. The designs, operations and achievements of Borexino, KamLAND and SNO+ in measuring the low-energy solar neutrino fluxes are reviewed. (orig.)

  2. Lanthanide doped strontium-barium cesium halide scintillators

    Science.gov (United States)

    Bizarri, Gregory; Bourret-Courchesne, Edith; Derenzo, Stephen E.; Borade, Ramesh B.; Gundiah, Gautam; Yan, Zewu; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew

    2015-06-09

    The present invention provides for a composition comprising an inorganic scintillator comprising an optionally lanthanide-doped strontium-barium, optionally cesium, halide, useful for detecting nuclear material.

  3. Cesium hafnium chloride scintillator coupled with an avalanche photodiode photodetector

    Czech Academy of Sciences Publication Activity Database

    Kurosawa, S.; Kodama, S.; Yokota, Y.; Horiai, T.; Yamaji, A.; Shoji, Y.; Král, Robert; Pejchal, Jan; Ohashi, Y.; Kamada, K.; Nikl, Martin; Yoshikawa, A.

    2017-01-01

    Roč. 12, Feb (2017), s. 1-8, č. článku C02042. ISSN 1748-0221 Grant - others:AV ČR(CZ) JSPS-17-18 Program:Bilaterální spolupráce Institutional support: RVO:68378271 Keywords : gamma detectors * scintillators and scintillating fibres * scintillators * scintillation and light emission processes Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.220, year: 2016

  4. Liquid-helium scintillation detection with germanium photodiodes

    International Nuclear Information System (INIS)

    Luke, P.N.; Haller, E.E.; Steiner, H.M.

    1982-05-01

    Special high-purity germanium photodiodes have been developed for the direct detection of vacuum ultraviolet scintillations in liquid helium. The photodiodes are immersed in the liquid helium, and scintillations are detected through one of the bare sides of the photodiodes. Test results with scintillation photons produced by 5.3-MeV α particles are presented. The use of these photodiodes as liquid-helium scintillation detectors may offer substantial improvements over the alternate detection method requiring the use of wavelength shifters and photomultiplier tubes

  5. Study on determination of 90Sr by liquid scintillation spectrometry

    International Nuclear Information System (INIS)

    Zhai Xiufang; Li Weiping; Tian Mei; Zou Ronghu

    2012-01-01

    Both of Liquid scintillation counting and Cerenkov counting can be used to determinate 90 Sr in samples by Liquid scintillation spectrometry. In this work, effects of scintillation vials wit-h different material, Liquid scintillation cocktails, sample volume, Strontium carrier, pH, quenching (chemical quenching and color quenching)are studied, and both counting methods are compared. For Liquid scintillation counting. The results show that the best appropriate volume ratio of sample and liquid scintillation cocktail is 8:12 for OPTIPHASE HISAFE-3 and OPTIPHASE HISAFE-2, stability of solution decreased when sample load exceeds the maximum load for both Liquid scintillation cocktails, and OPTIPHASE HISAFE-3 also show superior performance for high saline solution. The type of scintillation vial haven't clear influence on the MDA of 90 Sr. Chemical quenching and color quenching can decrease the counting efficiency. For Cerenkov counting, the lowest MDA is obtained when polyethylene plastic vial is used and sample volume is 20 ml. Color quenching decreases the counting efficiency, while there isn't chemical quenching for Cerenkov counting. The MDA of 90 Sr is 1.19 and 1.00 Bq/L for Liquid scintillation counting and Cerenkov counting with the optimal labeling condition. (authors)

  6. Plastic scintillator response to relativistic Ne, Ar, Fe IONS

    Science.gov (United States)

    Salamon, M. H.; Ahlen, S. P.

    1982-04-01

    The response to relativistic (0-600 MeV/amu) Ne, Ar, and Fe ions and to cosmic ray muons of four widely used commercial plastic scintillators, NE110, Pilot Y, Pilot F, and Pilot B, is discussed. Fitted expressions for scintillation efficiency for each scintillator and charge are given, and these are compared with the predictions of both the Voltz model and a modification of the Birks model. Resolution measurements demonstrate the relative roles of the halo and quenched core in heavy ion response, and point to a novel use for plastic scintillators.

  7. Radiation converter scintillator screen and its manufacturing process

    International Nuclear Information System (INIS)

    Delattre, D.; Rougeot, H.; Tassin, C.

    1984-01-01

    The present invention concerns scintillating screens receiving X or gamma radiation and converting it in luminous photons. The screen comprises a needle structure scintillating material. Its concave surface is quite smooth. The screen is obtained by evaporation on a frame having a perfectly smooth convex surface; the constituting material has a thermal dilatation coefficient different from the scintillating material one. After evaporation, the scintillating screen is set apart from the frame by simple heating. It is used for radiological image intensifier tubes and scintigraphy tubes [fr

  8. Study of spatial and temporal characteristics of L-band scintillations over the Indian low-latitude region and their possible effects on GPS navigation

    Directory of Open Access Journals (Sweden)

    P. V. S. Rama Rao

    2006-07-01

    Full Text Available The scintillation data (S4-index at the L-band frequency of 1.575GHz, recorded from a total of 18 GPS receivers installed at different locations in India under the GAGAN project, have provided us with a unique opportunity, for the first time in the Indian region, to make a simultaneous study of spatio-temporal and intensity characteristics of the trans-ionospheric scintillations during the 18-month, low sunspot activity (LSSA period from January 2004 to July 2005. During this period, the occurrence of scintillations is found to be maximum around the pre-midnight hours of equinox months, with very little activity during the post-midnight hours. No significant scintillation activity is observed during the summer and winter months of the period of observation. The intensity (S4 index of the scintillation activity is stronger around the equatorial ionization anomaly (EIA region in the geographic latitude range of 15° to 25° N in the Indian region. These scintillations are often accompanied by the TEC depletions with durations ranging from 5 to 25 min and magnitudes from 5 to 15 TEC units which affect the positional accuracy of the GPS by 1 to 3 m. Further, during the intense scintillation events (S4>0.45≈10 dB, the GPS receiver is found to lose its lock for a short duration of 1 to 4 min, increasing the error bounds effecting the integrity of the SBAS operation. During the present period of study, a total of 395 loss of lock events are observed in the Indian EIA region; this number is likely to increase during the high sunspot activity (HSSA period, creating more adverse conditions for the trans-ionospheric communications and the GPS-based navigation systems.

  9. Optical and structural characterization of the pure and doped BaY2F8 with rare earths for application in radiation detectors and scintillators

    International Nuclear Information System (INIS)

    Mello, Ana Carolina Santana de

    2008-01-01

    In this work Barium Yttrium Fluoride (BaY 2 F 8 -BaYF) doped with different concentrations of ions Tb 3+ , Er 3+ , Tm 3+ e Nd 3+ were characterized, aiming the application in radiation detection devices that use the scintillating properties. Two types of samples were produced in the CLA-IPEN-SP, polycrystalline samples, obtained via solid state reaction of BaF 2 and YF 3 under HF atmosphere, and single crystals, obtained via the zone melting method also in a HF atmosphere. The samples were characterized using the following experimental techniques: X-ray powder diffraction, Radioluminescence (RL), Optical Absorption and Dispersive X-ray Absorption Spectroscopy (DXAS). The X-ray diffraction pattern showed the presence of the phase BaY 2 F 8 and a small amount of the phase Ba 4 Y 3 F 17 in the polycrystalline pure and Tb 3+ doped samples. The other samples showed only the desired BaY 2 F 8 phase. The radioluminescence measurements of the doped BaYF, when irradiated with X-rays, showed emission peaks in energies that are characteristics of the 4f-4f transitions of rare earths. The RL of the samples with 2 mol por cent and 3 mold of Tb 3+ showed quite intense peaks with a maximum emission peak at 545 nm. The Tm 3+ doped BYF showed that the scintillation efficiency is not directly proportional to the doping level, and the highest RL emission were obtained for the polycrystalline samples doped with 1 mol por cent, showing a maximum peak intensity at 456 nm (the blue region of the visible spectrum). All samples showed a phosphorescent decay time of the order of seconds. Single crystals of BaYF doped with 2 mol por cent of Er 3+ , in addition to one of the highest phosphorescence time, presents a quite strong Rl in the green region of the spectra. The radiation damage was evaluated by the optical absorption techniques and the results showed that the formation of the absorption bands can be connected to colors centers generated by radiation in the matrix. Measurements of

  10. Scintillation response of Ce-doped or intrinsic scintillating crystals in the range up to 1 MeV

    Czech Academy of Sciences Publication Activity Database

    Mareš, Jiří A.; Beitlerová, Alena; Nikl, Martin; Solovieva, Natalia; D´Ambrosio, C.; Blažek, K.; Malý, P.; Nejezchleb, K.; De Notaristefani, F.

    2004-01-01

    Roč. 38, - (2004), s. 353-357 ISSN 1350-4487 R&D Projects: GA MŠk(CZ) ME 462 Grant - others:NATO SfP (XX) 973510 Institutional research plan: CEZ:AV0Z1010914 Keywords : scintillation * Ce-doped scintillators * photoelectron and light yields * intrinsic and extrinsic scintillators Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.664, year: 2004

  11. Performances of Free-Space Optical Communication System Over Strong Turbulence

    Directory of Open Access Journals (Sweden)

    Ucuk Darusalam

    2014-08-01

    Full Text Available We report an experimental of free-space optical communication (FSOC system that use tube propagation simulator (TPS as the turbulence medium. The FSOC system usewavelength of 1550 nm at the rate transmission of 1000 Mbps and amplified with EDFA at the output of +23 dBm. Index structure of 10-15–10-13 as the representation of atmosphere index turbulences are used for simulation of intensity distribution model or scintillation. The simulation use gammagamma and K model as well. The beam wave propagation models used in simulation are plane wave, spherical wave and Gaussian wave. Spherical wave achieves highest performance via gamma-gamma in strong turbulence. While Gaussian wave achieves highest performance also via K model. We also found, characteristical FSOC system performance is calculated more accurately with gamma-gamma method for strong turbulence than K model. The performances from gamma-gamma for strong turbulenceare at 22.55 dB, at 5.33×10-4, and at 9.41 ×10-6. 

  12. Growth and scintillation properties of BaMgF{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Yanagida, Takayuki, E-mail: t_yanagi@tagen.tohoku.ac.j [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Kawaguchi, Noriaki [Tokuyama Corporation, Shibuya 3-chome, Shibuya-ku, Tokyo 150-8383 (Japan); Fujimoto, Yutaka; Sugiyama, Makoto; Furuya, Yuki; Kamada, Kei; Yokota, Yuui [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yoshikawa, Akira [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Chani, Valery [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2010-09-21

    By using the micro-pulling down ({mu}-PD) method, the barium magnesium fluoride (BaMgF{sub 4}) single crystalline scintillator was produced. The crystal was cut and mirror polished to the physical dimensions of 1x2x10 mm{sup 3} for examination of scintillation properties. BaMgF{sub 4} demonstrated {approx}70% transmittance in wavelength range above 170 nm, and strong emission peaking around 205 nm was observed under X-ray excitation. The absolute light yield of BaMgF{sub 4} was 1300{+-}100 ph/MeV, and the decay time profile showed two components as 0.57{+-}0.01 (70%) and 2.2{+-}0.31 (30%) ns at room temperature.

  13. Scintillation characteristics of Tm3+ in Ca3(BO3)2 crystals

    International Nuclear Information System (INIS)

    Fujimoto, Yutaka; Yanagida, Takayuki; Yokota, Yuui; Kawaguchi, Noriaki; Fukuda, Kentaro; Totsuka, Daisuke; Watanabe, Kenichi; Yamazaki, Atsushi; Yoshikawa, Akira

    2011-01-01

    Basic optical properties and radiation responses of undoped, Tm 3+ 1.0% and 2.0% activated Ca 3 (BO 3 ) 2 (CBO) crystalline scintillator prepared by the micro-pulling down (μ-PD) method are reported. Tm 3+ : CBO crystals showed three weak absorption bands around 190, 260 and 350 nm, owing to the Tm 3+ 4f–4f transition. Strong blue luminescence peaks at 360 and 460 nm which are ascribed to the 1 D 2 – 3 H 6 and 1 D 2 – 3 F 4 transitions of Tm 3+ respectively were observed under 241 Am 5.5 MeV α-ray excitation. The scintillation light yield of 2.0% Tm 3+ -doped CBO crystal was evaluated to be about 250 ph/n from the 252 Cf excited pulse height spectrum.

  14. Monte Carlo investigations of the effect of beam divergence on thick, segmented crystalline scintillators for radiotherapy imaging

    Science.gov (United States)

    Wang, Yi; El-Mohri, Youcef; Antonuk, Larry E.; Zhao, Qihua

    2010-07-01

    The use of thick, segmented scintillators in electronic portal imagers offers the potential for significant improvement in x-ray detection efficiency compared to conventional phosphor screens. Such improvement substantially increases the detective quantum efficiency (DQE), leading to the possibility of achieving soft-tissue visualization at clinically practical (i.e. low) doses using megavoltage (MV) cone-beam computed tomography. While these DQE increases are greatest at zero spatial frequency, they are diminished at higher frequencies as a result of degradation of spatial resolution due to lateral spreading of secondary radiation within the scintillator—an effect that is more pronounced for thicker scintillators. The extent of this spreading is even more accentuated for radiation impinging the scintillator at oblique angles of incidence due to beam divergence. In this paper, Monte Carlo simulations of radiation transport, performed to investigate and quantify the effects of beam divergence on the imaging performance of MV imagers based on two promising scintillators (BGO and CsI:Tl), are reported. In these studies, 10-40 mm thick scintillators, incorporating low-density polymer, or high-density tungsten septal walls, were examined for incident angles corresponding to that encountered at locations up to ~15 cm from the central beam axis (for an imager located 130 cm from a radiotherapy x-ray source). The simulations demonstrate progressively more severe spatial resolution degradation (quantified in terms of the effect on the modulation transfer function) as a function of increasing angle of incidence (as well as of the scintillator thickness). Since the noise power behavior was found to be largely independent of the incident angle, the dependence of the DQE on the incident angle is therefore primarily determined by the spatial resolution. The observed DQE degradation suggests that 10 mm thick scintillators are not strongly affected by beam divergence for

  15. Influence of wind speed on free space optical communication performance for Gaussian beam propagation through non Kolmogorov strong turbulence

    International Nuclear Information System (INIS)

    Deng Peng; Yuan Xiuhua; Zeng Yanan; Zhao Ming; Luo Hanjun

    2011-01-01

    In free-space optical communication links, atmospheric turbulence causes fluctuations in both the intensity and the phase of the received signal, affecting link performance. Most theoretical treatments have been described by Kolmogorov's power spectral density model through weak turbulence with constant wind speed. However, several experiments showed that Kolmogorov theory is sometimes incomplete to describe atmospheric turbulence properly, especially through the strong turbulence with variable wind speed, which is known to contribute significantly to the turbulence in the atmosphere. We present an optical turbulence model that incorporates into variable wind speed instead of constant value, a non-Kolmogorov power spectrum that uses a generalized exponent instead of constant standard exponent value 11/3, and a generalized amplitude factor instead of constant value 0.033. The free space optical communication performance for a Gaussian beam wave of scintillation index, mean signal-to-noise ratio , and mean bit error rate , have been derived by extended Rytov theory in non-Kolmogorov strong turbulence. And then the influence of wind speed variations on free space optical communication performance has been analyzed under different atmospheric turbulence intensities. The results suggest that the effects of wind speed variation through non-Kolmogorov turbulence on communication performance are more severe in many situations and need to be taken into account in free space optical communication. It is anticipated that this work is helpful to the investigations of free space optical communication performance considering wind speed under severe weather condition in the strong atmospheric turbulence.

  16. Emergence of Uranium as a Distinct Metal Center for Building Intrinsic X-ray Scintillators.

    Science.gov (United States)

    Wang, Yaxing; Yin, Xuemiao; Liu, Wei; Xie, Jian; Chen, Junfeng; Silver, Mark A; Sheng, Daopeng; Chen, Lanhua; Diwu, Juan; Liu, Ning; Chai, Zhifang; Albrecht-Schmitt, Thomas E; Wang, Shuao

    2018-03-30

    The combination of high atomic number and high oxidation state in U VI materials gives rise to both high X-ray attenuation efficiency and intense green luminescence originating from ligand-to-metal charge transfer. These two features suggest that U VI materials might act as superior X-ray scintillators, but this postulate has remained substantially untested. Now the first observation of intense X-ray scintillation in a uranyl-organic framework (SCU-9) that is observable by the naked eye is reported. Combining the advantage in minimizing the non-radiative relaxation during the X-ray excitation process over those of inorganic salts of uranium, SCU-9 exhibits a very efficient X-ray to green light luminescence conversion. The luminescence intensity shows an essentially linear correlation with the received X-ray intensity, and is comparable with that of commercially available CsI:Tl. SCU-9 possesses an improved X-ray attenuation efficiency (E>20 keV) as well as enhanced radiation resistance and decreased hygroscopy compared to CsI:Tl. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. VHF Scintillation in an Artificially Heated Ionosphere

    Science.gov (United States)

    Suszcynsky, D. M.; Layne, J.; Light, M. E.; Pigue, M. J.; Rivera, L.

    2017-12-01

    As part of an ongoing project to characterize very-high-frequency (VHF) radio wave propagation through structured ionospheres, Los Alamos National Laboratory has been conducting a set of experiments to measure the scintillation effects of VHF transmissions under a variety of ionospheric conditions. Previous work (see 2015 Fall AGU poster by D. Suszcynsky et al.) measured the S4 index and ionospheric coherence bandwidth in the 32 - 44 MHz frequency range under naturally scintillated conditions in the equatorial region at Kwajalein Atoll during three separate campaigns centered on the 2014 and 2015 equinoxes. In this paper, we will present preliminary results from the February and September, 2017 High Altitude Auroral Research Project (HAARP) Experimental Campaigns where we are attempting to make these measurements under more controlled conditions using the HAARP ionospheric heater in a twisted-beam mode. Two types of measurements are made by transmitting VHF signals through the heated ionospheric volume to the Radio Frequency Propagation (RFProp) satellite experiment. The S4 scintillation index is determined by measuring the power fluctuations of a 135-MHz continuous wave signal and the ionospheric coherence bandwidth is simultaneously determined by measuring the delay spread of a frequency-modulated continuous wave (FMCW) signal in the 130 - 140 MHz frequency range. Additionally, a spatial Fourier transform of the CW time series is used to calculate the irregularity spectral density function. Finally, the temporal evolution of the time series is used to characterize spread-Doppler clutter effects arising from preferential ray paths to the satellite due to refraction off of isolated density irregularities. All results are compared to theory and scaled for comparison to the 32 - 44 MHz Kwajalein measurements.

  18. Experience with uranium-scintillator calorimetry

    International Nuclear Information System (INIS)

    Hasell, D.K.; Frisken, W.R.

    1990-01-01

    The ZEUS experiment on HERA will employ depleted uranium-scintillator calorimetry. Extensive studies have been made to optimize the calorimeter design. Test results and design aspects are discussed with a view to energy resolution, uniformity of response, mechanical assembly and calibration and monitoring. The energy resolution of four prototype calorimeter modules has been measured as 18%/v√E for electrons from 1 to 75 GeV and 35%/√E for pions from 1 to 100 GeV with an e/h ratio equal to one

  19. Scintillating ribbon x-ray detector

    International Nuclear Information System (INIS)

    Kinchen, B.E.; Rogers, A.

    1995-01-01

    A patent in the early 1970's by Aerojet Corporation in Sacramento, CA put forth the idea of using an array of scintillating fibers for x-ray detection and imaging. In about 1975, Pratt and Whitney Aircraft in East Hartford, CT designed and manufactured an imaging system based on the patent. The device was 1.75 in thick in the direction of the x-ray beam and about 4 in. by 4 in. square. The device was used with a 8 MeV x-ray source to image and measure internal clearances within operating aircraft, gas turbines engines. There are significant advantages of fiber optic detectors in x-ray detection. However, the advantages are often outweighed by the disadvantages. Two of the advantages of scintillating fiber optic x-ray detectors are: (1) high limiting spatial frequency -- between 20 and 25 lp/mm; and (2) excellent x-ray stopping power -- they can be made thick and retain spatial resolution. In traditional fiber optic detectors the x-rays are oriented parallel to the long axis of the fiber. For the scintillating ribbon x-ray sensor, the x-rays are oriented normal to the fiber long axis. This ribbon sensor technique has a number of advantages over the two current radiographic techniques digital x-radiography and x-ray film: The main advantage the ribbon has is size and shape. It can be as thin as 0.05 in., virtually any width or length, and flexible. Once positioned in a given location, 20 to 100 square inches of the object being inspected can be imaged with a single x-ray beam sweep. It is clear that conventional digital cameras do not lend themselves to placement between walls of aircraft structures or similar items requiring x-ray inspections. A prototype scintillating ribbon x-ray sensor has been fabricated and tested by Synergistic Detector Designs. Images were acquired on corrosion test panels of aluminum fabricated by Iowa State University

  20. AA, beam stopper with scintillator screen

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    An insertable steel-plate beam stopper was located after nearly a full turn downstream of the injection point. It was fitted with a scintillator screen, a thin plate of Cr-doped alumina, imprinted with a grid and reference points. The screen was illuminated through a window and observed with a highly sensitive TV camera plus image intensifier. This allowed observation of beam position and size of a proton test beam and of the beam from the target, which consisted not only of antiprotons but contained as well electrons, pions and muons of the same momentum.

  1. Collimator trans-axial tomographic scintillation camera

    International Nuclear Information System (INIS)

    Jaszczak, R.J.

    1977-01-01

    A collimator is provided for a scintillation camera system in which a detector precesses in an orbit about a patient. The collimator is designed to have high resolution and lower sensitivity with respect to radiation traveling in paths laying wholly within planes perpendicular to the cranial-caudal axis of the patient. The collimator has high sensitivity and lower resolution to radiation traveling in other planes. Variances in resolution and sensitivity are achieved by altering the length, spacing or thickness of the septa of the collimator

  2. Scintillating Fibre Calorimetry at the LHC

    CERN Multimedia

    2002-01-01

    Good electromagnetic and hadronic calorimetry will play a central role in an LHC detector. The lead/scintillating fibre calorimeter technique provides a fast signal response well matched to the LHC rate requirements. It can be made to give equal response for electrons and hadrons (compensation) with good electromagnetic and hadronic energy resolutions.\\\\ \\\\ The aim of this R&D proposal is to study in detail the aspects that are relevant for application of this type of calorimeter in an LHC environment, including its integration in a larger system of detectors, e.g.~projective geometry, radiation hardness, light detection, calibration and stability monitoring, electron/hadron separation.....

  3. Marine radioactivity measurements with liquid scintillation spectrometers

    International Nuclear Information System (INIS)

    Liong Wee Kwong, L.; Povinec, P.P.

    1999-01-01

    Liquid Scintillation Spectrometry (LSS) has now become the most widespread method for quantitative analytical measurement of low levels of β-emitting radionuclides like 3 H and 14 C. The high efficiency resulting from the latest development in LSS makes this technique not only appropriate but also enables direct measurement in environmental samples without excessive preparation. The introduction of several new cocktails based on solvents with a high flashpoint containing surfactants and having a high degree of aqueous sample compatibility has also contributed to the simplification of procedures

  4. Recent advances in gas scintillation proportional counters

    International Nuclear Information System (INIS)

    Palmer, H.E.

    1975-01-01

    Various geometrical configurations for gas scintillation proportional counters have been investigated in order to determine which is best for use in a large volume, high efficiency counter for measuring low energy gamma and x-rays. A xenon filled counter having a rod anode inside a cylindrical cathode appears to provide the best configuration for providing a uniform field and the best resolution over the total volume of the counter. The details of construction and operating characteristics of various shaped counters are described. (U.S.)

  5. Quality control of liquid scintillation counters

    International Nuclear Information System (INIS)

    Jaubert, F.; Tartes, I.; Cassette, P.

    2006-01-01

    Liquid scintillation counting (LSC) is widely used at LNHB for primary standardization of radionuclides (TDCR method), for secondary calibration and also for source stability studies or radioactive purity measurements. A total of five LSC counters are used for these purposes: two locally developed 3-photodetector counters for the implementation of the TDCR method, two Wallac 1414 counters and one Wallac 1220 Quantulus counter. The quality of the LSC measurements relies on the correct operation of these counters and their traceability to the frequency and time units

  6. Fundamental limits of scintillation detector timing precision

    International Nuclear Information System (INIS)

    Derenzo, Stephen E; Choong, Woon-Seng; Moses, William W

    2014-01-01

    In this paper we review the primary factors that affect the timing precision of a scintillation detector. Monte Carlo calculations were performed to explore the dependence of the timing precision on the number of photoelectrons, the scintillator decay and rise times, the depth of interaction uncertainty, the time dispersion of the optical photons (modeled as an exponential decay), the photodetector rise time and transit time jitter, the leading-edge trigger level, and electronic noise. The Monte Carlo code was used to estimate the practical limits on the timing precision for an energy deposition of 511 keV in 3 mm × 3 mm × 30 mm Lu 2 SiO 5 :Ce and LaBr 3 :Ce crystals. The calculated timing precisions are consistent with the best experimental literature values. We then calculated the timing precision for 820 cases that sampled scintillator rise times from 0 to 1.0 ns, photon dispersion times from 0 to 0.2 ns, photodetector time jitters from 0 to 0.5 ns fwhm, and A from 10 to 10 000 photoelectrons per ns decay time. Since the timing precision R was found to depend on A −1/2  more than any other factor, we tabulated the parameter B, where R = BA −1/2 . An empirical analytical formula was found that fit the tabulated values of B with an rms deviation of 2.2% of the value of B. The theoretical lower bound of the timing precision was calculated for the example of 0.5 ns rise time, 0.1 ns photon dispersion, and 0.2 ns fwhm photodetector time jitter. The lower bound was at most 15% lower than leading-edge timing discrimination for A from 10 to 10 000 photoelectrons ns −1 . A timing precision of 8 ps fwhm should be possible for an energy deposition of 511 keV using currently available photodetectors if a theoretically possible scintillator were developed that could produce 10 000 photoelectrons ns −1 . (paper)

  7. Scintillator's sensitivity calibration method in synchrotron radiation facility

    International Nuclear Information System (INIS)

    He Xiao'an; Du Huabing; Li Chaoguang; Yi Rongqing; Xiao Tiqiao

    2012-01-01

    Researches on scintillator's sensitivity method has been carried out recently in Shanghai synchrotron radiation facility. By some experimental researches in light source and detector's linearity, it built a new method for calibrating scintillator's sensitivity. Finally, calibration results were acquired by theory simulation of experimental data which were in accordance with radioactive source methods results, and the new method improved the data accuracy. (authors)

  8. Optimization of light collection from crystal scintillators for cryogenic experiments

    International Nuclear Information System (INIS)

    Mokina, V.M.; Danevich, F.A.; Kobychev, V.V.; Kraus, H.; Mikhailik, V.B.; Nagornaya, L.L.

    2012-01-01

    Cryogenic scintillation bolometers are a promising technique to search for dark matter and neutrinoless double decay. Improvement of light collection and energy resolution are important requirements in such experiments. Energy resolutions and relative pulse amplitudes of scintillation detectors using ZnWO 4 scintillation crystals of different shapes (cylinder 20x20 mm and hexagonal prism with diagonal 20 mm and height 20 mm), reflector materials and shapes, optical contact and surface properties (polished and diffused) were measured. The crystal scintillator of hexagonal shape shows the better energy resolution and pulse amplitude. The best energy resolution (FWHM = 9.3 % for 662 keV γ quanta of 137 Cs) was obtained with a hexagonal scintillator with all surfaces diffuse, in optical contact with a PMT and surrounded by a reflector (3M) of size 26x25 mm. In the geometry w ithout optical contact r epresenting the conditions of light collection for a cryogenic scintillating bolometer the best energy resolution and relative pulse amplitude was obtained for a hexagonal shape scintillator with diffuse side and polished face surfaces, surrounded by a reflector with a gap between the scintillator and the reflector

  9. Systematic studies of small scintillators for new sampling calorimeter

    Indian Academy of Sciences (India)

    mirror film, teflon, white paint, black tape, gold, aluminum and white paint+teflon. The pulse height dependence on position, length and thickness of the 3M reflective mirror film and teflon wrapped scintillators are measured. Results show that the 3M radiant mirror film-wrapped scintillator has the greatest light yield with an ...

  10. Systematic studies of small scintillators for new sampling calorimeter

    Indian Academy of Sciences (India)

    A new sampling calorimeter using very thin scintillators and the multi-pixel photon counter (MPPC) has been proposed to produce better position resolution for the international linear collider (ILC) experiment. As part of this R & D study, small plastic scintillators of different sizes, thickness and wrapping reflectors are ...

  11. Some history of liquid scintillator development at Los Alamos

    International Nuclear Information System (INIS)

    Ott, D.G.

    1979-01-01

    The early developments in liquid scintillation counting made at Los Alamos Scientific Laboratory are reviewed. Most of the work was under the direction of F.N. Hayes and included counter development and applications as well as synthesis and chemistry of liquid scintillators

  12. Microprocessor-based single particle calibration of scintillation counter

    Science.gov (United States)

    Mazumdar, G. K. D.; Pathak, K. M.

    1985-01-01

    A microprocessor-base set-up is fabricated and tested for the single particle calibration of the plastic scintillator. The single particle response of the scintillator is digitized by an A/D converter, and a 8085 A based microprocessor stores the pulse heights. The digitized information is printed. Facilities for CRT display and cassette storing and recalling are also made available.

  13. Influence of propagation technology on radiation stability of polystyren scintillators

    International Nuclear Information System (INIS)

    Senchishin, V.G.; Khlapova, N.P.; Borisenko, A.Yu.; Lebedev, V.N.

    1999-01-01

    In this work was studied the radiation hardness of polystyrene-based scintillators produced by injection molding technology and by polymerization in glass cast. The influence of crosslinking and low molecular filler on the radiation resistance was described. It was shown that the radiation resistance of scintillator depends on the viscosity properties of its polymer basis

  14. Scintillator quenching effects observed in the AMS-1 TOF data

    International Nuclear Information System (INIS)

    Esquivel, O.; Reyes, T.; Menchaca-Rocha, A.

    2001-01-01

    An analytical expression for the light output response of plastic scintillators as a function of the energy and the z identity of the incident ion is proposed. The effect of the δ rays is considered in the calculation of the scintillation efficiency

  15. How to quench light attenuation in plastic scintillators

    CERN Document Server

    Gabriele, S A; Massam, Thomas; Zichichi, A

    1972-01-01

    The problem of light attenuation in plastic scintillators is well known and has existed since their invention. The authors show how the problem has been investigated and overcome via a study of the effect of the chemical concentration of the scintillator components on the light output pattern. (1 refs).

  16. Scintillator quenching effects observed in the AMS-1 TOF data

    Science.gov (United States)

    Esquivel, O.; Reyes, T.; Menchaca-Rocha, A.

    2001-05-01

    An analytical expression for the light output response of plastic scintillators as a function of the energy and the z identity of the incident ion is proposed. The effect of the δ rays is considered in the calculation of the scintillation efficiency. .

  17. Systematic studies of small scintillators for new sampling calorimeter

    Indian Academy of Sciences (India)

    The wrapped scintillator that gives the best light yield is determined by comparing the measured pulse height of each 10 × 40 × 2 mm strip scintillator covered with 3M reflective mirror film, teflon, white paint, black tape, gold, aluminum and white paint+teflon. The pulse height dependence on position, length and thickness of ...

  18. Effects of Temperature and X-rays on Plastic Scintillating Fiber and Infrared Optical Fiber.

    Science.gov (United States)

    Lee, Bongsoo; Shin, Sang Hun; Jang, Kyoung Won; Yoo, Wook Jae

    2015-05-11

    In this study, we have studied the effects of temperature and X-ray energy variations on the light output signals from two different fiber-optic sensors, a fiber-optic dosimeter (FOD) based on a BCF-12 as a plastic scintillating fiber (PSF) and a fiber-optic thermometer (FOT) using a silver halide optical fiber as an infrared optical fiber (IR fiber). During X-ray beam irradiation, the scintillating light and IR signals were measured simultaneously using a dosimeter probe of the FOD and a thermometer probe of the FOT. The probes were placed in a beaker with water on the center of a hotplate, under variation of the tube potential of a digital radiography system or the temperature of the water in the beaker. From the experimental results, in the case of the PSF, the scintillator light output at the given tube potential decreased as the temperature increased in the temperature range from 25 to 60 °C. We demonstrated that commonly used BCF-12 has a significant temperature dependence of -0.263 ± 0.028%/°C in the clinical temperature range. Next, in the case of the IR fiber, the intensity of the IR signal was almost uniform at each temperature regardless of the tube potential range from 50 to 150 kVp. Therefore, we also demonstrated that the X-ray beam with an energy range used in diagnostic radiology does not affect the IR signals transmitted via a silver halide optical fiber.

  19. Defect Engineering by Codoping in KCaI3 :Eu2 + Single-Crystalline Scintillators

    Science.gov (United States)

    Wu, Yuntao; Li, Qi; Jones, Steven; Dun, Chaochao; Hu, Sheng; Zhuravleva, Mariya; Lindsey, Adam C.; Stand, Luis; Loyd, Matthew; Koschan, Merry; Auxier, John; Hall, Howard L.; Melcher, Charles L.

    2017-09-01

    Eu2 + -doped alkali or alkali earth iodide scintillators with energy resolutions ≤3 % at 662 keV promise the excellent discrimination ability for radioactive isotopes required for homeland-security and nuclear-nonproliferation applications. To extend their applications to x-ray imaging, such as computed tomography scans, the intense afterglow which delays the response time of such materials is an obstacle that needs to be overcome. However, a clear understanding of the origin of the afterglow and feasible solutions is still lacking. In this work, we present a combined experimental and theoretical investigation of the physical insights of codoping-based defect engineering which can reduce the afterglow effectively in KCaI3:Eu2 + single-crystal scintillators. We illustrate that Sc3 + codoping greatly suppresses the afterglow, whereas Y3 + , Gd3 + , or La3 + codoping enhances the afterglow. Meanwhile, a light yield of 57 000 photons / MeV and an energy resolution of 3.4% at 662 keV can be maintained with the appropriate concentration of Sc3 + codoping, which makes the material promising for medical-imaging applications. Through our thermoluminescence techniques and density-functional-theory calculations, we are able to identify the defect structures and understand the mechanism by which codoping affects the scintillation performance of KCaI3:Eu2 + crystals. The proposed defect-engineering strategy is further validated by achieving afterglow suppression in Mg2 + codoped KCaI3:Eu2 + single crystals.

  20. The recent developments in the technology of scintillator detectors for gamma-ray spectroscopy

    International Nuclear Information System (INIS)

    Verdebout, J.

    1988-01-01

    The goal of this report is to review the recent developments in the use of high stopping power materials and solid state readout for scintillation gamma -ray spectroscopy as these techniques may give rise to a new generation of low powered portable instruments. The report is a bibliographical study based on papers published mainly these last five years. The main subject is preceded by a general introduction in which the principal characteristics of a scintillator gamma-ray spectrometer are discussed. The properties of some scintillator materials (NaI(T1), CsI(T1), CsI(Na), BGO, GSO(Ce) and CdWO 4 ) are then briefly presented. In this section, a special emphasis has been given to BGO as this material has recently received much attention and is now well documented. Finally, the results obtained by measuring the intensity of the light generated in the crystal with three types of solid-state photodetectors (Si photodiodes, HgI 2 photodetectors and avalanche Si photodiodes) are summarized

  1. Prompt directional detection of galactic supernova by combining large liquid scintillator neutrino detectors

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, V.; Chirac, T.; Lasserre, T., E-mail: vincent.fischer@cea.fr, E-mail: tchirac@gmail.fr, E-mail: thierry.lasserre@cea.fr [Commissariat a l' énergie atomique et aux énergies alternatives, Centre de Saclay, IRFU, 91191 Gif-sur-Yvette (France); and others

    2015-08-01

    Core-collapse supernovae produce an intense burst of electron antineutrinos in the few-tens-of-MeV range. Several Large Liquid Scintillator-based Detectors (LLSD) are currently operated worldwide, being very effective for low energy antineutrino detection through the Inverse Beta Decay (IBD) process. In this article, we develop a procedure for the prompt extraction of the supernova location by revisiting the details of IBD kinematics over the broad energy range of supernova neutrinos. Combining all current scintillator-based detector, we show that one can locate a canonical supernova at 10 kpc with an accuracy of 45 degrees (68% C.L.). After the addition of the next generation of scintillator-based detectors, the accuracy could reach 12 degrees (68% C.L.), therefore reaching the performances of the large water Čerenkov neutrino detectors. We also discuss a possible improvement of the SuperNova Early Warning System (SNEWS) inter-experiment network with the implementation of a directionality information in each experiment. Finally, we discuss the possibility to constrain the neutrino energy spectrum as well as the mass of the newly born neutron star with the LLSD data.

  2. Fabrication, optical and scintillation properties of transparent YAG:Ce ceramics

    Science.gov (United States)

    Osipov, V. V.; Ishchenko, A. V.; Shitov, V. A.; Maksimov, R. N.; Lukyashin, K. E.; Platonov, V. V.; Orlov, A. N.; Osipov, S. N.; Yagodin, V. V.; Viktorov, L. V.; Shulgin, B. V.

    2017-09-01

    Highly transparent YAG:Ce ceramics (transmission of 72-82% for 2-mm-thick samples in 550-900 nm wavelength range) were fabricated by solid-state reactive sintering using a mixture of Ce2xY2-2xO3 (x = 0.001, 0.01, 0.03, and 0.05) and Al2O3 nanopowders synthesized by laser ablation with an additional round of pre-calcining before compaction. The synthesized YAG:Ce ceramic materials showed intense luminescence with a maximum at 525-545 nm. The measured absolute light yields of the synthesized YAG:Ce ceramics were 18-21 photon/MeV for 1-5 at.% Ce and 5 photon/MeV for 0.1 at.% Ce. The energy resolutions of the fabricated thin ceramic samples (2 mm) under 662 keV gamma ray were measured to be 10-15%. The decay curves of scintillations consisted of two components with the decay times depending on the Ce3+ concentration. The sample doped with 5 at.% of Ce exhibited the main fast component with 26 ns decay time. The measured data was compared to that of YAG:Ce and well-known CsI:Tl single crystal scintillators. The influence of dopant concentration on the optical, luminescence and scintillation properties was discussed.

  3. Analysis of Ionospheric Scintillation Characteristics in Sub-Antarctica Region with GNSS Data at Macquarie Island.

    Science.gov (United States)

    Guo, Kai; Liu, Yang; Zhao, Yan; Wang, Jinling

    2017-01-12

    Ionospheric scintillation has a great impact on radio propagation and electronic system performance, thus is extensively studied currently. The influence of scintillation on Global Navigation Satellite System (GNSS) is particularly evident, making GNSS an effective medium to study characteristics of scintillation. Ionospheric scintillation varies greatly in relation with temporal and spatial distribution. In this paper, both temporal and spatial characteristics of scintillation are investigated based on Macquarie Island's GNSS scintillation data collected from 2011 to 2015. Experiments demonstrate that occurrence rates of amplitude scintillation have a close relationship with solar activity, while phase scintillation is more likely to be generated by geomagnetic activity. In addition, scintillation distribution behaviors related to elevation and azimuth angles are statistically analyzed for both amplitude and phase scintillation. The proposed work is valuable for a deeper understanding of theoretical mechanisms of ionospheric scintillation in this region, and provides a reference for GNSS applications in certain regions around sub-Antarctica.

  4. SU-F-J-50: Study On the Magnetic Field Effect On the Exradin W1 Plastic Scintillation Detector

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Z; Therriault-Proulx, F; Owens, C; Ibbott, G; Beddar, S [UT MD Anderson Cancer Center, Houston, TX (United States)

    2016-06-15

    Purpose: To study the response of the Exradin W1 plastic scintillator detector to a 6 MV photon field in the presence of a strong magnetic field (B). Methods: An Exradin W1 scintillator detector coupled to a SuperMax two-channel electrometer, both manufactured by Standard Imaging, Inc., was first calibrated in a Co-60 beam. The Cerenkov Light Ratio (CLR) was obtained following the procedure recommended by the manufacturer. Subtracting signal in channel 2 multiplied by CLR from the signal in channel 1 should lead to a Cerenkov-free signal. The W1 scintillator was placed in a plastic phantom inside a dipole electromagnet (GMW Associates) that could produce a strong B field, and irradiated using a 6 MV beam from an Elekta Versa HD LINAC. Signals from both channels of the W1 scintillator were acquired as a function of B (0 - 1.5 T). Results: The signals from both channels increased as a function of the B field strength. At 1.5 T, channel 1 increased by 11% compared to the baseline (B=0 T), while channel 2 increased by 22%. Applying the recommended Cerenkov correction led to a 2% difference between dose measurement with and without a magnetic field. The values between B=0.3 T and B=1.5 T remained constant. Conclusion: Signals from the Exradin W1 plastic scintillation detector increased as the B field increased. This increase mainly comes from a change in the amount of Cerenkov light coupled within the optical fiber. Removing the Cerenkov component following the procedure recommended by the manufacturer showed to be an effective way to measure dose accurately in strong magnetic fields. The cause for the residual 2% difference is currently under investigation. We acknowledge research support from Elekta AB.

  5. The Scintillating Grid Illusion is Enhanced by Binocular Viewing

    Directory of Open Access Journals (Sweden)

    Jenny C. A. Read

    2012-12-01

    Full Text Available The scintillating grid illusion is an intriguing stimulus consisting of a grey grid on a black background, with white discs at the grid intersections. Most viewers perceive illusory “scintillating” black discs within the physical white discs, especially at non-fixated locations. Here, we report for the first time that this scintillation percept is stronger when the stimulus is viewed binocularly than when it is presented to only one eye. Further experiments indicate that this is not simply because two monocular percepts combine linearly, but involves a specifically cyclopean contribution (Schrauf & Spillmann, 2000. However, the scintillation percept does not depend on the absolute disparity of the stimulus relative to the screen. In an intriguing twist, although the basic illusion shows more scintillation when viewed binocularly, when the illusion is weakened by shifting the discs away from the grid intersections, scintillation becomes stronger with monocular viewing.

  6. Development of a double scintillator fast neutron spectrometer

    International Nuclear Information System (INIS)

    Shirakata, Keisho; Iijima, Tsutomu; Cho, Mann.

    1976-03-01

    A double scintillator fast neutron spectrometer based on the time-of-flight measurement between two plastic scintillators has been developed for spectrum measurement in FCA cores and other fast systems. Neutrons extracted from a fast system are scattered by the 1st scintillator and the 2nd scintillator detects the scattered neutrons. By measuring the time-of-flight between the two scintillators, the neutron spectrum is determined. The method is essentially differential, and a complicated unfolding process is not required. The results of its application indicate excellence of the method over other methods in the energy range above several hundreds keV. Design and characteristics of the spectrometer, application, analysis of the measured data are described in detail. (auth.)

  7. Neutron-gamma discrimination of boron loaded plastic scintillator

    International Nuclear Information System (INIS)

    Wang Dong; He Bin; Zhang Quanhu; Wu Chuangxin; Luo Zhonghui

    2010-01-01

    Boron loaded plastic scintillator could detect both fast neutrons thanks to hydrogen and thermal neutrons thanks to 10B. Both reactions have large cross sections, and results in high detection efficiency of incident neutrons. However, similar with other organic scintillators, boron loaded plastic scintillator is sensitive to gamma rays and neutrons. So gamma rays must be rejected from neutrons using their different behavior in the scintillator. In the present research zero crossing method was used to test neutron-gamma discrimination of BC454 boron loaded plastic scintillator. There are three Gaussian peaks in the time spectrum, they are corresponding to gamma rays, fast neutrons and flow neutrons respectively. Conclusion could be made that BC454 could clear discriminate slow neutrons and gamma, but the discrimination performance turns poor as the neutrons' energy becomes larger. (authors)

  8. Scintillating fiber detector development for the SSC: Annual progress report

    International Nuclear Information System (INIS)

    Ruchti, R.C.

    1989-01-01

    During the past year, considerable effort has been applied to the development of scintillating fiber detectors in several areas: new scintillation liquids and studies of their fluorescence properties; new fluorescent dyes based on non-intramolecular proton transfer; new dyes based on intramolecular proton transfer; incorporation of these new dyes in plastic (polystyrene) and liquid scintillation solutions; development of small cross section glass capillaries for the containment of liquid scintillators; studies of waveguide characteristics; studies of image intensifier phosphor screen characteristics; initial steps to form a collaboration to study and develop appropriate new properties of the Solid State Photomultiplier; construction of a new laboratory at Notre Dame to enhance our capabilities for further measurements and studies; and organization of and execution of a Workshop on Scintillating Fiber Detector Development for the SSC, held at Fermilab, November 14--16, 1988

  9. Optimization of light collection from crystal scintillators for cryogenic experiments

    Energy Technology Data Exchange (ETDEWEB)

    Danevich, F.A., E-mail: danevich@kinr.kiev.ua [Institute for Nuclear Research, MSP 03680, Kyiv (Ukraine); Kobychev, R.V. [Institute for Nuclear Research, MSP 03680, Kyiv (Ukraine); National Technical University of Ukraine “Kyiv Polytechnic Institute”, 03056 Kyiv (Ukraine); Kobychev, V.V. [Institute for Nuclear Research, MSP 03680, Kyiv (Ukraine); Kyungpook National University, Daegu 702-701 (Korea, Republic of); Kraus, H. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Mikhailik, V.B. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Diamond Light Source, Harwell Science Campus, Didcot, OX11 0DE (United Kingdom); Mokina, V.M. [Institute for Nuclear Research, MSP 03680, Kyiv (Ukraine)

    2014-04-21

    High light collection efficiency is an important requirement in any application of scintillation detectors. The purpose of this study is to investigate the possibility for improving this parameter in cryogenic scintillation bolometers, which can be considered as promising detectors in experiments investigating neutrinoless double beta decay and dark matter. Energy resolutions and relative pulse amplitudes of scintillation detectors using ZnWO{sub 4} scintillation crystals of different shapes (cylinder ∅ 20×20 mm and hexagonal prism with diagonal 20 mm and height 20 mm), reflector materials and shapes, optical contact and surface properties (polished and diffused) were measured at room temperature. Propagation of optical photons in these experimental conditions was simulated using Geant4 and ZEMAX codes. The results of the simulations are found to be in good agreement with each other and with direct measurements of the crystals. This could be applied to optimize the geometry of scintillation detectors used in the cryogenic experiments.

  10. Regional Arctic observations of TEC gradients and scintillations

    DEFF Research Database (Denmark)

    Durgonics, Tibor; Høeg, Per; von Benzon, Hans-Henrik

    2015-01-01

    near-real time observations of the stateand variations of the high-latitude ionosphere. This data can be employed to obtain relevant geophysical variablesand statistics. In our study GPS-derived total electron content (TEC) measurements have been complemented with amplitudescintillation indices (S4......), and phase scintillation indices (σϕ) The investigation of relations of these geophysical variables can lead to possible new ways to study the underlying processes and to build tools for monitoring and predicting Arctic TEC and scintillation large-scale patterns. A number of specific ionosphere events...... will be presented and the underlying geophysical process will be identified and described. Especially results where large-scale gradients in the regional TEC are compared with the growth of scintillations.The statistics of the scintillations will be investigated, with emphasis on how well the scintillations follow...

  11. Quantum Hydrodynamical Formulation of Time-Dependent Density Functional Theory for Probing Strong-Field Multiphoton Processes: Application to the Study of High-Order Harmonic Generation of He and Ne in Intense Laser Fields

    Science.gov (United States)

    Roy, A. K.; Chu, Shih-I.

    2002-05-01

    We extend the quantum hydrodynamical (QFD) formulation of time-dependent density functional theory (TDDFT) to the study of multiphoton processes of many-electron atomic systems in intense laser fields (A. K. Roy and S. I. Chu, Phys. Rev. A (in press).). The QFD-TDDFT formulation results in a single generalized nonlinear Schrodinger equation (GNLSE) and includes the many-body effects through a local time-dependent exchange-correlation (xc) potential. The GNLSE is solved by the time- dependent generalized pseudospectral method (X. M. Tong and S.I. Chu, Chem. Phys. 217) (1997) 119. (X. Chu and S. I. Chu, Phys. Rev. A 63) (2001) 023411.. The procedure is applied to the study of multiphoton ionization (MPI) and high harmonic generation (HHG) of He and Ne in intense laser fields. Four different xc energy functionals are used in the study with an aim to explore the roles of exchange and correlation ovn MPI/HHG processes in details ^1.

  12. Decontamination and modification of liquid scintillators

    International Nuclear Information System (INIS)

    Sachan, S.R.; Soman, S.D.

    1980-01-01

    New techniques of decontaminating and recycling used radioactive liquid scintillators (LS) are discussed. Aromatic LS Tritel spiked with tritiated water was decontaminated with NaOH; single extraction gave a decontamination factor of about 90% and 3-4 extractions decontaminated the LS to background level. The counting efficiency of the decontaminated LS was about 88% of the fresh LS. A modification of hydrophobic toluene LS for use with aqueous samples is also described. The water holding capacity (WHC) of modified toluene/alcohol LS decreased while the counting efficiency increased with increasing concentration of toluene in LS; an optimum working range of around 50% toluene concentration was selected. The decontamination of used modified LS was achieved by a single washing with an excess amount of water. The counting efficiency of decontaminated LS was about 92% of the fresh LS. This recycling of used liquid scintillators after decontamination will not only save expenditure on LS but also help waste disposal problems as the radioactivity is contained in aqueous phase with reduced volume. (UK)

  13. Effects of hadron irradiation on scintillating fibers

    Energy Technology Data Exchange (ETDEWEB)

    Atac, M. (Univ. of California, Los Angeles, CA (United States) Fermi National Accelerator Lab., Batavia, IL (United States)); Buchanan, C.; Chrisman, D.; Cline, D.; Kolonko, J.; Kubic, J.; Park, J. (Univ. of California, Los Angeles, CA (United States)); Baumbaugh, A.; Binkley, M.; Bross, A.D.; Finley, D.; Elias, J.; Foster, G.W.; Kephart, R.; Kephart, R.; Kim, C.; Park, H.; Pla-Dalmau, A.; Rivetta, C.; Tkaczyk, S.; Wagner, R. (Fermi National Accelerator Lab., Batavia, IL (United States)); Chung, M.; Goldberg, H.; Jeskik, R.; Margulies, S.; Mendez, H.; Solomon, J.; Vaca, F. (Univ. of Illinois, Chicago, IL (United States)); Kelley, C. (Massachusetts College of Pharmacy and Allied Health Sciences, Boston, MA (United States)); Baumbaugh, B.; Bishop, J.; Biswas, N.; Cason, N.; Jacques, J.; Kehoe, R.; Kelly, M.; Kenney, V.; LoSecco, J.; Ruchti, R.; Shephard, W.; Warchol, J.; Wayne, M.; Marchant, J.; Mountain, R.J. (Univ. of Notre Dame, IN (United States)); Davis, D.; Vandergriff, D. (O

    1993-08-01

    Trackers based on scintillating-fiber technology are being considered by the Solenoidal Detector Collaboration at SSC and the D[phi] collaboration at Fermilab. An important issue is the effect of the radiation existing in the detector cores on fiber properties. Most studies of radiation damage in scintillators have irradiated small bulk samples rather than fibers, and have used X-rays, [sup 60]Co gammas, or electron beams, often at accelerated rates. The authors have irradiated some 600 fibers in the Fermilab Tevatron C[phi] area, thereby obtaining a hadronic irradiation at realistic rates. Four-meter-long samples of ten Bicron polystyrene-based fiber types, maintained in air, dry nitrogen, argon, and vacuum atmospheres within stainless-steel tubes, were irradiated for seven weeks at various distances from the accelerator beam pipes. Maximum doses, measured by thermoluminescence detectors, were about 80 Krad. Fiber properties, particularly light yield and attenuation length, have been measured over a one-year period. A description of the work together with the results is presented. At the doses achieved, corresponding to a few years of actual fiber-tracking detector operation, little degradation is observed. In addition, recovery after several days' exposure to air has been noted. Properties of unirradiated samples kept in darkness show no changes after one year.

  14. Collimator trans-axial tomographic scintillation camera

    International Nuclear Information System (INIS)

    Jaszczak, Ronald J.

    1979-01-01

    An improved collimator is provided for a scintillation camera system that employs a detector head for transaxial tomographic scanning. One object of this invention is to significantly reduce the time required to obtain statistically significant data in radioisotope scanning using a scintillation camera. Another is to increase the rate of acceptance of radioactive events to contribute to the positional information obtainable from a radiation source of known strength without sacrificing spatial resolution. A further object is to reduce the necessary scanning time without degrading the images obtained. The collimator described has apertures defined by septa of different radiation transparency. The septa are aligned to provide greater radiation shielding from gamma radiation travelling within planes perpendicular to the cranial-caudal axis and less radiation shielding from gamma radiation travelling within other planes. Septa may also define apertures such that the collimator provides high spatial resolution of gamma rays traveling within planes perpendicular to the cranial-caudal axis and directed at the detector and high radiation sensitivity to gamma radiation travelling other planes and indicated at the detector. (LL)

  15. Distributed imaging for liquid scintillation detectors

    Science.gov (United States)

    Dalmasson, J.; Gratta, G.; Jamil, A.; Kravitz, S.; Malek, M.; Wells, K.; Bentley, J.; Steven, S.; Su, J.

    2018-03-01

    We discuss a novel paradigm in the optical readout of scintillation radiation detectors. In one common configuration, such detectors are homogeneous and the scintillation light is collected and recorded by external photodetectors. It is usually assumed that imaging in such a photon-starved and large-emittance regime is not possible. Here we show that the appropriate optics, matched with highly segmented photodetector coverage and dedicated reconstruction software, can be used to produce images of the radiation-induced events. In particular, such a "distributed imaging" system can discriminate between events produced as a single cluster and those resulting from more delocalized energy depositions. This is crucial in discriminating many common backgrounds at MeV energies. With the use of simulation, we demonstrate the performance of a detector augmented with a practical, if preliminary, set of optics. Finally, we remark that this new technique lends itself to be adapted to different detector sizes and briefly discuss the implications for a number of common applications in science and technology.

  16. Buried plastic scintillator muon telescope (BATATA)

    International Nuclear Information System (INIS)

    Alfaro, R.; De Donato, C.; D'Olivo, J.C.; Guzman, A.; Medina-Tanco, G.; Moreno Barbosa, E.; Paic, G.; Patino Salazar, E.; Salazar Ibarguen, H.; Sanchez, F.A.; Supanitsky, A.D.; Valdes-Galicia, J.F.; Vargas Trevino, A.D.; Vergara Limon, S.; Villasenor, L.M.

    2010-01-01

    Muon telescopes have multiple applications in the area of cosmic ray research. We are currently building such a detector with the objective of comparing the ground penetration of muon vs. electron-gamma signals originated in cosmic ray showers. The detector is composed by a set of three parallel dual-layer scintillator planes, buried at fixed depths ranging from 120 to 600g/cm 2 . Each layer is 4m 2 and is composed by 49 rectangular strips of 4cmx2m, oriented at a 90 0 angle with respect to its companion layer, which gives an xy-coincidence pixel of 4x4cm 2 . The scintillators are MINOS extruded polystyrene strips, with an embedded Bicron BC92 wavelength shifting (WLS) fibers, of 1.5 mm in diameter. Light is collected by Hamamatsu H7546B multi-anode PMTs of 64 pixels. The front-end (FE) electronics works in counting mode and signals are transmitted to the surface DAQ stage using low-voltage differential signaling (LVDS). Any strip signal above threshold opens a GPS-tagged 2μs data collection window. Data, including signal and background, are acquired by a system of FPGA (Spartan 2E) boards and a single-board computer (TS7800).

  17. Data process of liquid scintillation counting

    International Nuclear Information System (INIS)

    Ishikawa, Hiroaki; Kuwajima, Susumu.

    1975-01-01

    The use of liquid scintillation counting system has been significantly spread because automatic sample changers and printers have recently come to be incorporated. However, the system will be systematized completely if automatic data processing and the sample preparation of radioactive materials to be measured are realized. Dry or wet oxidation method is applied to the sample preparation when radioactive materials are hard to dissolve into scintillator solution. Since these several years, the automatic sample combustion system, in which the dry oxidation is automated, has been rapidly spread and serves greatly to labor saving. Since the printers generally indicate only counted number, data processing system has been developed, and speeded up calculating process, which automatically corrects quenching of samples for obtaining the final radioactivity required. The data processing system is roughly divided into on-line and off-line systems according to whether computers are connected directly or indirectly, while its hardware is classified to input, calculating and output devices. Also, the calculation to determine sample activity by external standard method is explained. (Wakatsuki, Y.)

  18. Multifrequency techniques for studying interplanetary scintillations

    Science.gov (United States)

    Woo, R.

    1975-01-01

    Rytov's approximation, or the method of smooth perturbations, is utilized to derive the temporal frequency spectra of the amplitude and phase fluctuations of multifrequency plane and spherical waves propagating in the interplanetary medium and solar corona. It is shown that multifrequency observations of interplanetary scintillations using either compact radio stars of spacecraft radio signals are desirable because the correlation of the multifrequency waves yields additional independent measurements of the solar wind and turbulence. Measurements of phase fluctuations are also desirable because, unlike amplitude fluctuations, they provide information on the full range of scale sizes for the electron-density fluctuations. It is also shown that a coherent dual-frequency radio system is particularly useful in making such measurements. In addition to providing a means for interpreting observations of multifrequency interplanetary scintillations, the present analysis is essential for estimating the effects of solar corona turbulence on the communications and navigation of a spacecraft whose line-of-sight path passes close to the sun.

  19. Lanthanum halide scintillators: Properties and applications

    International Nuclear Information System (INIS)

    Iltis, Alain; Mayhugh, M.R.; Menge, P.; Rozsa, C.M.; Selles, O.; Solovyev, V.

    2006-01-01

    BrilLanCe[reg]-350 and BrilLanCe[reg]-380, Saint-Gobain Crystals' trade-names for LaCl 3 :Ce and LaBr 3 :Ce are being brought to market under exclusive license to Delft and Bern Universities. We are reporting the properties of crystals produced with commercially viable processes and find they match others' observations. These scintillators are bright (60,000 photons/MeV for LaBr 3 :Ce) and have very linear response, a combination that leads to very good energy resolution ( 3 :Ce). The materials also have fast scintillation decay times ( 3 :Ce). These excellent properties are retained at high temperature with only moderate light loss ( 138 and Ac 227 , the latter having been substantially reduced in recent processing. BrilLanCe[reg]-350 is now available in detectors up to 51 mm diameter while 38 mm diameter is available for BrilLanCe[reg]-380. Larger sizes are expected

  20. Influence of the least-squares phase on optical vortices in strongly scintillated beams

    CSIR Research Space (South Africa)

    Chen, M

    2009-06-01

    Full Text Available ]. In a random wave fleld, saddles, phase singularities and extrema can be cre- ated or converted from one to another with the topolog- ical index of the wave fleld being conserved [14, 19]. The total number of vortices can be variable due to the cre...

  1. Rapid Weakening of Hurricane Joaquin in Strong Vertical Wind Shear and Cold SSTs: Numerical Simulations with Assimilation of High-Definition Sounding System Dropsondes During Tropical Cyclone Intensity Experiment

    Science.gov (United States)

    Pu, Z.; Zhang, S.

    2017-12-01

    Observations from High-Definition Sounding System (HDSS) Dropsondes, collected for Hurricane Joaquin (2005) during the Office of Naval Research Tropical Cyclone Intensity (TCI) Experiment in 2015, are assimilated into the Gridpoint Statistical Interpolation (GSI)-based hybrid data assimilation systems embedded in the NCEP Hurricane Weather Research and Forecasting (HWRF) system. A three-dimensional and a four-dimensional ensemble-variational hybrid (3DEnVAR and 4DEnVar) data assimilation configuration are used. It is found that the experiments with assimilation of the HDSS dropsonde observations capture well the intensity changes during the rapid weakening (RW) of Hurricane Joaquin. Compared with 3DEnVAR, 4DEnVar leads to better assimilation results and subsequent forecasts and thus offers a set of simulations to diagnose the processes associated with the RW of Hurricane Joaquin. A drastic increase in the vertical wind shear (VWS, with a magnitude of 12 m s-1) is found before the RW. This high VWS is persistent during the 0-12 h period of RW, inducing changes in the vortex structure of Hurricane Joaquin through dry air intrusion in the mid-level and the dilution of the upper-level warm core. The transport of low air from above into the boundary layer occurs at the same time, resulting in depressed values in the storm inflow layer and reduced eyewall values through the updraft. As a consequence, downdrafts flush the boundary layer with low air, leading to the weakening of inflow in the boundary layers. When Hurricane Joaquin moves over an area where the SSTs are below 28oC within the hurricane inner core during the 18-30 h period of RW, the cold SSTs significantly inhibit latent and sensible heat release within the hurricane inner core and its vicinity, thus resulting in the continuous weakening of Hurricane Joaquin.

  2. Design and test of a high resolution plastic scintillating fiber detector with intensified CCD readout

    International Nuclear Information System (INIS)

    Rebourgeard, P.

    1991-01-01

    We present the design of a particle detector involving a coherent array of 100 000 plastic scintillating microfibers, with an individual core diameter around 50 micrometers, and an intensified bidimensional CCD array. We investigate both theoretically and experimentally the use of polystyrene based scintillators in optical multimodal fibers. The isotropic excitation of modes and the characteristics of energy transfers between the polystyrene matrix and the added fluorescent dyes are of particular interest. An experimental approach is proposed and applied to the development of a new binary scintillator. In order to study the transmission of the signal from the interaction area to the output face, we specify the loss factors, the resolution and the signal to noise ratio within the fiber array. The low light level at the output face of the detector leads us to use image intensifiers in photon counting mode. This requires a detailed analysis of resolutions, gain, noise and detectivity concepts. We propose to describe these strongly correlated notions by the moment generation formalism. Thus, a previous modelisation of the photoelectronic devices allows us to evaluate the performance of the readout chain. A complete detector has been assembled and tested on a high energy hadron beam; the measurements are in good agreement with the modelisation [fr

  3. Microcolumnar and polycrystalline growth of LaBr3:Ce scintillator

    Science.gov (United States)

    Nagarkar, V. V.; Miller, S.; Sia, R.; Gaysinskiy, V.

    2011-05-01

    While a wide variety of new scintillators are now available, cerium-doped lanthanide halide scintillators have shown a strong potential toward fulfilling the needs of highly demanding applications such as radioisotope identification at room temperature, homeland security, quantitative molecular imaging for medical diagnostics, and disease staging and research. Despite their extraordinary advantages in terms of light yield and response uniformity over a wide energy range, issues related to reliable, large volume manufacturing of these high-light-yield materials in a rapid and economic manner has not been resolved or purposefully addressed. Here we report on synthesizing LaBr3:Ce scintillator using a thermal evaporation technique, which offers the potential to synthesize large quantities of small-to-large volume, high-quality material in a time-efficient and cost-effective manner. To date we have successfully applied this method to form both microcolumnar films and thick polycrystalline slabs of LaBr3:Ce, and have characterized their light yield, response linearity, decay time and afterglow.

  4. A simple satellite system to locate gamma-ray bursters using scintillating fiber technology

    International Nuclear Information System (INIS)

    Colavita, A.; Fratnik, F.

    1993-07-01

    We present a study on the feasibility of using a system of small, light, long-lived and simple satellites in order to locate gamma-ray bursters. Each small satellite possesses only electronics to discriminate gamma-rays out of the large background of cosmic rays and to time the arrival of the front of a gamma-ray burst. The arrival of a γ-ray strikes a plane made out of scintillating fibers. A layered structure of thin lead foils and scintillating fibers is used to obtain a low trigger threshold of approximately 20 MeV. To locate the burster applying triangulation methods, we use the time of arrival of the front of the gamma-ray burst and the position of the satellites at that very moment. We review an elementary version of the triangulation method to study the angular error in the determination of the burster position. We show that for almost all non-pathological distances among satellites we can determine the angular location of the source to better than one arc min. This precision allows us to find the visible counterpart of the burster, if it exists. These simple satellites can be made modular in order to customize their sizes or weights in order to use spare space available during major launches. We also propose a block diagram for the satellite architecture as well as a simple and strong detector using scintillating fiber technology. (author). 13 refs, 5 figs

  5. Effect of annealing temperature on the photoluminescence and scintillation properties of ZnO nanorods

    Science.gov (United States)

    Kurudirek, Sinem V.; Menkara, H.; Klein, Benjamin D. B.; Hertel, Nolan E.; Summers, Christopher J.

    2018-01-01

    The effect of the annealing to enhance the photoluminescence (PL) and scintillation properties, as determined by pulse height distribution of alpha particle irradiation, has been investigated for solution grown ZnO nanorods For this investigation the ZnO nanorod arrays were grown on glass for 22 h at 95 ∘C as a substrate using a solution based hydrothermal technique. The samples were first annealed for different times (30, 60, 90 and 120 min) at 300 ∘C and then at different temperatures (100 ∘C-600 ∘C) in order to determine the optimum annealing time and temperature, respectively. Before annealing, the ZnO nanorod arrays showed a broad yellow-orange visible and near-band gap UV emission peaks. After annealing in a forming gas atmosphere, the intensity of the sub-band gap PL was significantly reduced and the near-band gap PL emission intensity correspondingly increased (especially at temperatures higher than 100 ∘C). Based on the ratio of the peak intensity ratio before and after annealing, it was concluded that samples at 350 ∘C for 90 min resulted in the best near-band gap PL emission. Similarly, the analysis of the pulse height spectrum resulting from alpha particles revealed that ZnO nanorod arrays similarly annealed at 350 ∘C for 90 min exhibited the highest scintillation response.

  6. On the occurrence and strength of multi-frequency multi-GNSS Ionospheric Scintillations in Indian sector during declining phase of solar cycle 24

    Science.gov (United States)

    Srinivasu, V. K. D.; Dashora, N.; Prasad, D. S. V. V. D.; Niranjan, K.; Gopi Krishna, S.

    2018-04-01

    This study presents unique perspectives of occurrence and strength of low latitude ionospheric scintillations on multiple signals of Global Navigation Satellite System (GNSS) and its frequency dependence using continuous observation records of 780 nights. A robust comparative analysis is performed using scintillation index, S4 and its variation during pre-midnight and post-midnight duration from a GNSS receiver located at Waltair (17.7°N, 83.3°E), India, covering period from July 2014 to August 2016. The results, generally exhibit the impact of declining phase of solar cycle 24 on occurrence and strength of scintillations, which, however, is evidently different over different frequencies transmitted from different GNSS systems. A deeper quantitative analysis uniquely reveals that apart from the solar cycle and seasonal effects, the number of visible satellites of a selected GNSS markedly affect the occurrence and also the strength. Processing scheme of adopting 6 hourly time windows of pre-midnight and post-midnight brought a novel result that the strength and occurrence of strong scintillations decrease with declining solar activity during pre-midnight hours but remarkably increase for moderate and weak scintillations during post-midnight. The physical processes that dominate the post-midnight equatorial ionosphere are invoked to explain such variations that are special during declining solar activity. Finally, inter-GNSS signal analysis in terms of the effect of strong, moderate and weak scintillations is presented with due consideration of number of satellite passes affected and frequency dependence of mean S4. The quantitative results of this study emphasize for the first time effect of low latitude scintillation on GNSS signals in Indian zone under changing background solar and seasonal conditions.

  7. Enhanced scintillation of Ba3In(B3O6)3 based on nitrogen doping

    Science.gov (United States)

    Wang, Z. X.; Pei, H.; Tao, X. M.; Cai, G. M.; Mao, R. H.; Jin, Z. P.

    2018-02-01

    Scintillating materials, as a class of luminescent materials, are highly demanded for practical use in the high-energy detection. However, the applications are often hampered by their low light yield (LY) or long decay time for many traditional scintillators. In this work, upon nitrogen anion doping, scintillation performance in layered borate Ba3In(B3O6)3 (BIB) has been excellently enhanced with high XEL intensity of ~3 times as large as that of commercial Bi4Ge3O12 (BGO) and ultra-fast fluorescent decay time of ~1.25 ns. To shed light on origins of the intrinsic violet-blue emission, we measured the in-situ vacuum ultraviolet excited (VUV) emission spectra of N-BIB ceramic. Combined with experiments and first principles calculations, the band-gap reduction and donor-acceptor density increasing by nitrogen (N) doping is responsible for the enhancement of scintillation performance for N-doped Ba3In(B3O6)3. Moreover, nitrogen anion doping rather than conventional cation doping is found to be also applicable to other intrinsic luminescent materials for enhancing performance.

  8. Scintillation densimeter for liquids and an isotopic conveyor weighers with plastic scintillator

    International Nuclear Information System (INIS)

    Makhaj, B.; Antonyak, V.; Plyater, Z.

    1979-01-01

    The method is described of the weighted material's mass measuring according to the results of the conveyor momentary load measurement derived from the attenuation of radiation in the transmission geometry, conveyor belt velocity measurement and digital processing of the signals from the measurement of the bouth values. In the measuring gage there are located: the point type gamma source of cesium-137 with 4 mCi capacity, the scintillation detector with plastic cylindric scintillator of 5 cm in diameter and with the length approximately equal to the width of the conveyor belt and also the tachometer-generator. The conveyor weighers described is intended for use with conveyor having belt; from 60 to 180 cm wide. The results are given of industrial exploitation of the instrument [ru

  9. Field-Aligned GPS Scintillation: Multisensor Data Fusion

    Science.gov (United States)

    Mrak, Sebastijan; Semeter, Joshua; Hirsch, Michael; Starr, Gregory; Hampton, Don; Varney, Roger H.; Reimer, Ashton S.; Swoboda, John; Erickson, Philip J.; Lind, Frank; Coster, Anthea J.; Pankratius, Victor

    2018-01-01

    The Mahali Global Positioning System (GPS) array (9 receivers, 15-30 km baseline distance) in central Alaska has probed auroral structures in a field-aligned direction during a geomagnetic substorm on 7 October 2015. We present results from a collaborative study of GPS phase scintillation, optical emission brightness, and ionospheric density perturbations, by virtue of data fusion procedure from the Mahali GPS array, all-sky imager (ASI), and the Poker Flat Incoherent Scatter Radar (PFISR). First, we present observations in a traditional way using colocated GPS-ASI sensors, giving us a principal pattern of the phase scintillation with respect to auroral brightness, free of any mapping ambiguities. Next, we use an assumption that the plasma irregularities are located at an altitude of 120 km, we map the optical data to this altitude, and we extend the GPS-ASI study over the entire field of view of the GPS receiver array. We obtain a repeatable and persuasive pattern, revealing that GPS phase scintillation is clustered at the auroral edges. Moreover, investigation of the colinear ISR observations supports the altitude assumption of scintillation producing irregularities, and PFISR-derived electric field estimates suggest that the source for irregularities is gradient drift instability. The phase scintillation was observed on all GPS receivers, phase scintillation exceeded once cycle during several electrojet intensifications, and several events lasted for more than a minute. Finally, phase scintillation was observed during all surge events, independent of the particular auroral morphology.

  10. Study of the correlation of scintillation decay and emission wavelength

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Fujimoto, Yutaka; Yamaji, Akihiro; Kawaguchi, Noriaki; Kamada, Kei; Totsuka, Daisuke; Fukuda, Kentaro; Yamanoi, Kohei; Nishi, Ryosuke; Kurosawa, Shunsuke; Shimizu, Toshihiko; Sarukura, Nobuhiko

    2013-01-01

    In photoluminescence which directly excites the emission center of phosphor material is known to have a correlation between the emission wavelength and the decay time based on quantum mechanics. In scintillation phenomenon, host lattice of the material is first excited by ionizing radiation and then the excitation energy is transferred to emission centers. For the first time, we investigated the correlation between the scintillation decay and the emission wavelength by using pulse X-ray equipped streak camera system which could observe time and wavelength resolved scintillation phenomenon. Investigated materials were Ce 3+ , Pr 3+ and Nd 3+ doped oxides and fluorides which all showed 5d-4f transition based emission. As a result, we obtained the relation that τ (scintillation decay time) was proportional to the λ 2.15 (emission wavelength). -- Highlights: ► The correlation between emission wavelength and scintillation decay time is investigated. ► Photoluminescence decay times are also evaluated and compared with scintillation decay times. ► It is proved the relaxation process in emission center is dominant even in scintillation decay

  11. Surface preparation and coupling in plastic scintillator dosimetry

    International Nuclear Information System (INIS)

    Ayotte, Guylaine; Archambault, Louis; Gingras, Luc; Lacroix, Frederic; Beddar, A. Sam; Beaulieu, Luc

    2006-01-01

    One way to improve the performance of scintillation dosimeters is to increase the light-collection efficiency at the coupling interfaces of the detector system. We performed a detailed study of surface preparation of scintillating fibers and their coupling with clear optical fibers to minimize light loss and increase the amount of light collected. We analyzed fiber-surface polishing with aluminum oxide sheets, coating fibers with magnesium oxide, and the use of eight different coupling agents (air, three optical gels, an optical curing agent, ultraviolet light, cyanoacrylate glue, and acetone). We prepared 10 scintillating fiber and clear optical fiber light guide samples to test different coupling methods. To test the coupling, we first cut both the scintillating fiber and the clear optical fiber. Then, we cleaned and polished both ends of both fibers. Finally, we coupled the scintillating fiber with the clear optical fiber in either a polyethylene jacket or a V-grooved support depending on the coupling agent used. To produce more light, we used an ultraviolet lamp to stimulate scintillation. A typical series of similar couplings showed a standard deviation in light-collection efficiency of 10%. This can be explained by differences in the surface preparation quality and alignment of the scintillating fiber with the clear optical fiber. Absence of surface polishing reduced the light collection by approximately 40%, and application of magnesium oxide on the proximal end of the scintillating fiber increased the amount of light collected from the optical fiber by approximately 39%. Of the coupling agents, we obtained the best results using one of the optical gels. Because a large amount of the light produced inside a scintillator is usually lost, better light-collection efficiency will result in improved sensitivity

  12. Monte Carlo simulation of electron thermalization in scintillator materials: Implications for scintillator nonproportionality

    Science.gov (United States)

    Prange, Micah P.; Xie, YuLong; Campbell, Luke W.; Gao, Fei; Kerisit, Sebastien

    2017-12-01

    The lack of reliable quantitative estimates of the length and time scales associated with hot electron thermalization after a gamma-ray induced energy cascade obscures the interplay of various microscopic processes controlling scintillator performance and hampers the search for improved detector materials. We apply a detailed microscopic kinetic Monte Carlo model of the creation and subsequent thermalization of hot electrons produced by gamma irradiation of six important scintillating crystals to determine the spatial extent of the cloud of excitations produced by gamma rays and the time required for the cloud to thermalize with the host lattice. The main ingredients of the model are ensembles of microscopic track structures produced upon gamma excitation (including the energy distribution of the excited carriers), numerical estimates of electron-phonon scattering rates, and a calculated particle dispersion to relate the speed and energy of excited carriers. All these ingredients are based on first-principles density functional theory calculations of the electronic and phonon band structures of the materials. The details of the Monte Carlo model are presented along with the results for thermalization time and distance distributions. These results are discussed in light of previous work. It is found that among the studied materials, calculated thermalization distances are positively correlated with measured nonproportionality. In the important class of halide scintillators, the particle dispersion is found to be more influential than the largest phonon energy in determining the thermalization distance.

  13. Monte Carlo simulation of electron thermalization in scintillator materials: Implications for scintillator nonproportionality

    Energy Technology Data Exchange (ETDEWEB)

    Prange, Micah P. [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA; Xie, YuLong [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA; Campbell, Luke W. [National Security Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA; Gao, Fei [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA; Kerisit, Sebastien [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA

    2017-12-21

    The lack of reliable quantitative estimates of the length and time scales associated with hot electron thermalization after a gamma-ray induced energy cascade obscures the interplay of various microscopic processes controlling scintillator performance and hampers the search for improved detector materials. We apply a detailed microscopic kinetic Monte Carlo model of the creation and subsequent thermalization of hot electrons produced by gamma irradiation of six important scintillating crystals to determine the spatial extent of the cloud of excitations produced by gamma rays and the time required for the cloud to thermalize with the host lattice. The main ingredients of the model are ensembles of microscopic track structures produced upon gamma excitation (including the energy distribution of the excited carriers), numerical estimates of electron-phonon scattering rates, and a calculated particle dispersion to relate the speed and energy of excited carriers. All these ingredients are based on first-principles density functional theory calculations of the electronic and phonon band structures of the materials. Details of the Monte Carlo model are presented along with results for thermalization time and distance distributions. These results are discussed in light of previous work. It is found that among the studied materials, calculated thermalization distances are positively correlated with measured nonproportionality. In the important class of halide scintillators, the particle dispersion is found to be more influential than the largest phonon energy in determining the thermalization distance.

  14. Scintillation properties of N2 and CF4 and performances of a scintillating ionization chamber

    Science.gov (United States)

    Lehaut, G.; Salvador, S.; Fontbonne, J.-M.; Lecolley, F.-R.; Perronnel, J.; Vandamme, Ch.

    2015-10-01

    In this work, we studied the emission yields, decay times and coincidence resolving times (CRT) of two gases, nitrogen (N2) and tetrafluoromethane (CF4), used for particle detection in the context of fission products measurement. The set-up was made of an ionization chamber and two photomultiplier tubes (PMTs) placed front-to-front on each side of the active zone of the chamber. Using the photomultiplier tubes, the number of photoelectrons (phe) converted at the photocathodes from the scintillation processes in each gas was quantified and the scintillation time spectra were recorded. A scintillation emission yield of 24 phe MeV-1 with a decay time of τd = 2.5 ns in N2, and 225 phe MeV-1 with τd = 6.2 ns for CF4, has been measured. With our set-up, the coincidence resolving time (σ values) between the two PMTs have been measured using alpha particles at 1.4 ns and 0.34 ns for N2 and CF4, respectively.

  15. Scintillation trigger system of the liquid argon neutrino detector

    International Nuclear Information System (INIS)

    Belikov, S.V.; Gurzhiev, S.N.; Gutnikov, Yu.E.; Denisov, A.G.; Kochetkov, V.I.; Matveev, M.Yu.; Mel'nikov, E.A.; Usachev, A.P.

    1994-01-01

    This paper presents the organization of the Scintillation Trigger System (STS) for the Liquid Argon Neutrino Detector of the Tagged Neutrino Facility. STS is aimed at the effective registration of the needed neutrino interaction type and production of a fast trigger signal with high time resolution. The fast analysis system of analog signal from the trigger scintillation planes for rejection of the trigger signals from background processes is described. Real scintillation trigger planes characteristics obtained on the basis of the presented data acquisition system are shown. 10 refs., 12 figs., 3 tabs

  16. Neutron detector using lithiated glass-scintillating particle composite

    Science.gov (United States)

    Wallace, Steven [Knoxville, TN; Stephan, Andrew C [Knoxville, TX; Dai, Sheng [Knoxville, TN; Im, Hee-Jung [Knoxville, TN

    2009-09-01

    A neutron detector composed of a matrix of scintillating particles imbedded in a lithiated glass is disclosed. The neutron detector detects the neutrons by absorbing the neutron in the lithium-6 isotope which has been enriched from the natural isotopic ratio to a commercial ninety five percent. The utility of the detector is optimized by suitably selecting scintillating particle sizes in the range of the alpha and the triton. Nominal particle sizes are in the range of five to twenty five microns depending upon the specific scintillating particle selected.

  17. Ionization and scintillation of nuclear recoils in gaseous xenon

    Energy Technology Data Exchange (ETDEWEB)

    Renner, J., E-mail: jrenner@lbl.gov [Lawrence Berkeley National Laboratory (LBNL), 1 Cyclotron Road, Berkeley, CA 94720 (United States); Department of Physics, University of California, Berkeley, CA 94720 (United States); Gehman, V.M.; Goldschmidt, A.; Matis, H.S.; Miller, T.; Nakajima, Y.; Nygren, D.; Oliveira, C.A.B.; Shuman, D. [Lawrence Berkeley National Laboratory (LBNL), 1 Cyclotron Road, Berkeley, CA 94720 (United States); Álvarez, V. [Instituto de Física Corpuscular (IFIC), CSIC & Universitat de València, Calle Catedrático José Beltrán, 2, 46980 Paterna, Valencia (Spain); Borges, F.I.G. [Departamento de Fisica, Universidade de Coimbra, Rua Larga, 3004-516 Coimbra (Portugal); Cárcel, S. [Instituto de Física Corpuscular (IFIC), CSIC & Universitat de València, Calle Catedrático José Beltrán, 2, 46980 Paterna, Valencia (Spain); Castel, J.; Cebrián, S. [Laboratorio de Física Nuclear y Astropartículas, Universidad de Zaragoza, Calle Pedro Cerbuna 12, 50009 Zaragoza (Spain); Cervera, A. [Instituto de Física Corpuscular (IFIC), CSIC & Universitat de València, Calle Catedrático José Beltrán, 2, 46980 Paterna, Valencia (Spain); Conde, C.A.N. [Departamento de Fisica, Universidade de Coimbra, Rua Larga, 3004-516 Coimbra (Portugal); and others

    2015-09-01

    Ionization and scintillation produced by nuclear recoils in gaseous xenon at approximately 14 bar have been simultaneously observed in an electroluminescent time projection chamber. Neutrons from radioisotope α-Be neutron sources were used to induce xenon nuclear recoils, and the observed recoil spectra were compared to a detailed Monte Carlo employing estimated ionization and scintillation yields for nuclear recoils. The ability to discriminate between electronic and nuclear recoils using the ratio of ionization to primary scintillation is demonstrated. These results encourage further investigation on the use of xenon in the gas phase as a detector medium in dark matter direct detection experiments.

  18. Design and Prototyping of a High Granularity Scintillator Calorimeter

    International Nuclear Information System (INIS)

    Zutshi, Vishnu

    2016-01-01

    A novel approach for constructing fine-granularity scintillator calorimeters, based on the concept of an Integrated Readout Layer (IRL) was developed. The IRL consists of a printed circuit board inside the detector which supports the directly-coupled scintillator tiles, connects to the surface-mount SiPMs and carries the necessary front-end electronics and signal/bias traces. Prototype IRLs using this concept were designed, prototyped and successfully exposed to test beams. Concepts and implementations of an IRL carried out with funds associated with this contract promise to result in the next generation of scintillator calorimeters.

  19. CsI(Tl) infrared scintillation light yield and spectrum

    CERN Document Server

    Belogurov, S; Carugno, Giovanni; Conti, E; Iannuzzi, D; Meneguzzo, Anna Teresa

    2000-01-01

    Infrared emission from CsI(Tl) excited by approx 70 keV electrons was detected with an InGaAs PIN photodiode. Some parameters of infrared scintillation were studied. The emission spectrum is located between 1.55 and 1.70 mu m with a maximum at 1.60 mu m. The light yield of infrared scintillation is (4.9+-0.3)x10 sup 3 photons/MeV. Infrared scintillation caused by 3 MeV alpha-particles is detected as well.

  20. Design and Prototyping of a High Granularity Scintillator Calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Zutshi, Vishnu [Northern Illinois Univ., DeKalb, IL (United States). Dept. of Physics

    2016-03-27

    A novel approach for constructing fine-granularity scintillator calorimeters, based on the concept of an Integrated Readout Layer (IRL) was developed. The IRL consists of a printed circuit board inside the detector which supports the directly-coupled scintillator tiles, connects to the surface-mount SiPMs and carries the necessary front-end electronics and signal/bias traces. Prototype IRLs using this concept were designed, prototyped and successfully exposed to test beams. Concepts and implementations of an IRL carried out with funds associated with this contract promise to result in the next generation of scintillator calorimeters.

  1. Method for measuring multiple scattering corrections between liquid scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Verbeke, J.M., E-mail: verbeke2@llnl.gov; Glenn, A.M., E-mail: glenn22@llnl.gov; Keefer, G.J., E-mail: keefer1@llnl.gov; Wurtz, R.E., E-mail: wurtz1@llnl.gov

    2016-07-21

    A time-of-flight method is proposed to experimentally quantify the fractions of neutrons scattering between scintillators. An array of scintillators is characterized in terms of crosstalk with this method by measuring a californium source, for different neutron energy thresholds. The spectral information recorded by the scintillators can be used to estimate the fractions of neutrons multiple scattering. With the help of a correction to Feynman's point model theory to account for multiple scattering, these fractions can in turn improve the mass reconstruction of fissile materials under investigation.

  2. Modelling of an IR scintillation counter

    CERN Document Server

    Fraga, M M F; Policarpo, Armando

    2000-01-01

    A systematic study of the excitation and de-excitation mechanisms in ternary gas mixtures Ar+CO sub 2 +N sub 2 is presented regarding the possibility of developing a proportional scintillation counter based on the detection of the infrared molecular emissions associated with the lowest vibrational states of molecules. The use of visible or near-infrared photons (lambda<1 mu m) for applications like imaging and quality control of microstructure detectors has been reported. In view of these applications we analyse the processes leading to near-infrared emissions in pure argon and give an estimation of the number of photons emitted per electron, at several pressures, as a function of the charge gain.

  3. Collimated trans-axial tomographic scintillation camera

    International Nuclear Information System (INIS)

    1980-01-01

    The principal problem in trans-axial tomographic radioisotope scanning is the length of time required to obtain meaningful data. Patient movement and radioisotope migration during the scanning period can cause distortion of the image. The object of this invention is to reduce the scanning time without degrading the images obtained. A system is described in which a scintillation camera detector is moved to an orbit about the cranial-caudal axis relative to the patient. A collimator is used in which lead septa are arranged so as to admit gamma rays travelling perpendicular to this axis with high spatial resolution and those travelling in the direction of the axis with low spatial resolution, thus increasing the rate of acceptance of radioactive events to contribute to the positional information obtainable without sacrificing spatial resolution. (author)

  4. A readout system for plastic scintillating fibers

    Science.gov (United States)

    Akbari, H.; Bao, J.; Chien, C.-Y.; Fenker, H.; Fitzgerald, R.; Fisher, P.; Glaubman, M.; Grimes, A.; Hofer, H.; Horvath, I.; Kaplan, D.; Lanius, K.; Leedom, I.; Macdermott, M.; Mnich, J.; Newman, D.; Orndorff, J.; Pevsner, A.; Reucroft, S.; Rose, J.; Spangler, J.; Spartiotis, C.; Tonisch, F.; Viertel, G.; Waldmeier, S.; Zehnder, L.

    1991-05-01

    A readout system for plastic scintillating fibers has been developed using a multi-anode microchannel photomultiplier tube operated in a 5 kG magnetic field and the CMOS MX4 microplexer chip. The microchannel photomultiplier tube with an anode array of 10×10 is coupled to an array of fibers using a precise alignment procedure. Each readout unit is capable of sampling signals from 100 fibers simultaneously and multiplexing the analog signals serially with rates of up to 5 MHz. The analog signals are subsequently digitized and subtracted from the pedestals previously stored using a specially designed analog to digital VME module. Such a readout system has many applications in high energy physics, solid state physics, and other fields where a large number of fibers must be read out in short times and at relatively high rates.

  5. Elevator mechanism and method for scintillation detectors

    International Nuclear Information System (INIS)

    Frank, E.

    1975-01-01

    An elevator mechanism and method for raising and lowering radioactive samples through a shielded vertical counting chamber in a benchtop scintillation detector is described. The elevator mechanism adds little or nothing to the height of the detector by using an elongated flexible member such as a metal tape secured to the bottom of the elevator platform and extending downwardly through the counting chamber and its bottom shielding, where the tape is bent laterally for connection to a drive means. In the particular embodiment illustrated, the tape is bent laterally below the bottom shielding for the counting chamber, and then upwardly along or through one side of the shielding to a reel at the top of the shielding. The tape is wound onto the reel, and the reel is driven by a reversible motor which winds and unwinds the tape on the reel to raise and lower the elevator platform

  6. Liquid xenon/krypton scintillation calorimeter

    International Nuclear Information System (INIS)

    Akimov, D.Yu.; Bolozdynya, A.I.; Brastilov, A.D.

    1994-01-01

    A scintillating LXe/LKr electromagnetic calorimeter has been built at the ITEP and tested at the BATES (MIT) accelerator. The detector consists of PMT matrix and 45 light collecting cells made of aluminized 50 microns Mylar partially covered with p-terphenyl as a wavelength-shifter. Each pyramidal cell has (2.1 x 2.1) x 40 x (4.15 x 4.15) cm dimensions and is viewed by FEU-85 glass-window photomultiplier. The detector has been exposed at 106-348 MeV electron beam. The energy resolution σ E /E ≅ 5% √ E at 100 - 350 MeV range in LXe, the coordinate resolution τ x ≅ 0.7 cm, the time resolution for single cell ≅ 0.6 ns have been obtained. Possible ways to improve energy resolution are discussed. 8 refs., 15 figs

  7. Quench determination in liquid scintillation counting systems

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    A method and apparatus for measuring the degree of quench in a liquid scintillation sample by irradiating the sample with a standard source, such as a cesium-137 gamma source, to produce a Compton scattered electron distribution exhibiting a Compton edge configuration as the leading edge are described. For increasing the quench levels in the sample, the Compton edge shifts to lower pulse height values and the extent of this shift is indicative of the degree of quench. To measure the degree of quench, a unique point on the Compton edge, namely the point at which the second derivative of the edge is zero (i.e. the inflection point), is measured for the quenched sample and the pulse height value corresponding to the inflection point is determined. The pulse height value is compared with the pulse height value determined for a calibration standard in a similar manner, the difference in pulse height values indicating the degree of quench

  8. A three-state model for describing the temperature variation of the scintillation properties of Cs2HfCl6

    Science.gov (United States)

    Koshimizu, Masanori; Saeki, Keiichiro; Fujimoto, Yutaka; Okada, Go; Yanagida, Takayuki; Yamashita, Shinichi; Asai, Keisuke

    2018-03-01

    The temperature dependence of the scintillation intensity of Cs2HfCl6 was measured and found to increase monotonically from 10 to 300 K, whereas no significant dependence on temperature was observed for the scintillation decay. A simple three-state model in which two excited levels are slightly different in their energies and have similar radiative rates was able to describe the experimental trends. The model is consistent with the experimental observation of two kinds of V k centers and with theoretical predictions of two types of self-trapped excitons reported in the literature.

  9. Spectroscopic neutron detection using composite scintillators

    Science.gov (United States)

    Jovanovic, I.; Foster, A.; Kukharev, V.; Mayer, M.; Meddeb, A.; Nattress, J.; Ounaies, Z.; Trivelpiece, C.

    2016-09-01

    Shielded special nuclear material (SNM), especially highly enriched uranium, is exceptionally difficult to detect without the use of active interrogation (AI). We are investigating the potential use of low-dose active interrogation to realize simultaneous high-contrast imaging and photofission of SNM using energetic gamma-rays produced by low-energy nuclear reactions, such as 11B(d,nγ)12C and 12C(p,p‧)12C. Neutrons produced via fission are one reliable signature of the presence of SNM and are usually identified by their unique timing characteristics, such as the delayed neutron die-away. Fast neutron spectroscopy may provide additional useful discriminating characteristics for SNM detection. Spectroscopic measurements can be conducted by recoil-based or thermalization and capture-gated detectors; the latter may offer unique advantages since they facilitate low-statistics and event-by-event neutron energy measurements without spectrum unfolding. We describe the results of the development and characterization of a new type of capture-gated spectroscopic neutron detector based on a composite of scintillating polyvinyltoluene and lithium-doped scintillating glass in the form of millimeter-thick rods. The detector achieves >108 neutron-gamma discrimination resulting from its geometric properties and material selection. The design facilitates simultaneous pulse shape and pulse height discrimination, despite the fact that no materials intrinsically capable of pulse shape discrimination have been used to construct the detector. Accurate single-event measurements of neutron energy may be possible even when the energy is relatively low, such as with delayed fission neutrons. Simulation and preliminary measurements using the new composite detector are described, including those conducted using radioisotope sources and the low-dose active interrogation system based on low-energy nuclear reactions.

  10. Comparative study of Tm-doped and Tm-Sc co-doped Lu3Al5O12 scintillator

    International Nuclear Information System (INIS)

    Sugiyama, Makoto; Yanagida, Takayuki; Fujimoto, Yutaka

    2014-01-01

    The crystals of Tm doped and Tm-Sc co-doped Lu 3 Al 5 O 12 (LuAG) grown by the floating zone (FZ) method were examined for their optical and scintillation properties. In transmittance spectra, strong absorption lines due to Tm 3+ 4f–4f transitions were observed. X-ray excited radioluminescence spectra were measured and broad and sharp emission peaks were detected. The former one was attributed to Sc 3+ and the latter one was due to Tm 3+ 4f–4f transitions. Scintillation yield enhancement due to Sc co-doping was observed by means of 137 Cs pulse height spectra. Scintillation decay times were several tens of μs under pulse X-ray excitation. - Highlights: • LuAG:Tm and LuAG:Tm, Sc single crystals have been grown by the FZ method. • Tm 3+ 4f–4f absorption has been observed in transmittance spectra. • Scintillation yield of Tm-doped LuAG has been enhanced by Sc co-doping

  11. Synthesis of crystalline Ce-activated garnet phosphor powders and technique to characterize their scintillation light yield

    Science.gov (United States)

    Gordienko, E.; Fedorov, A.; Radiuk, E.; Mechinsky, V.; Dosovitskiy, G.; Vashchenkova, E.; Kuznetsova, D.; Retivov, V.; Dosovitskiy, A.; Korjik, M.; Sandu, R.

    2018-04-01

    This work reports on a process of preparation of garnet phosphor powders and a technique for light yield evaluation of strongly light scattering samples. Powders of scintillation compounds could be used as individual materials or as samples for express tests of scintillation properties. However, estimation of their light yield (LY) is complicated by strong light scattering of this kind of materials. Ce3+-activated yttrium-aluminum and gallium-gadolinium-aluminum garnet phosphor powders, Y3Al5O12 (YAG:Ce) and Gd3Ga3Al2O12 (GGAG:Ce), were obtained using a modified coprecipitation technique. Ga tends to residue in mother liquor in ammonia media, but the modification allows to avoid the loss of components. We propose an approach for sample preparation and LY measurement setup with alpha particles excitation, allowing to decrease light scattering influence and to estimate a light yield of powder samples. This approach is used to evaluate the obtained powders.

  12. Testing strong interaction theories

    International Nuclear Information System (INIS)

    Ellis, J.

    1979-01-01

    The author discusses possible tests of the current theories of the strong interaction, in particular, quantum chromodynamics. High energy e + e - interactions should provide an excellent means of studying the strong force. (W.D.L.)

  13. Production of the Large-area Plastic Scintillator for Beta-ray Detection using Epoxy Resin

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Jong Soo; Choi, Yong Seok; Hong, Sang Bum; Seo, Bum Kyung; Moon, Jei Kwon; Choi, Jong Won [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    In this study, we prepared a plastic scintillator whose manufacturing process is simple and can be freely shaped. A thin plate of the plastic scintillator was manufactured using epoxy resin as a polymer. The plastic scintillator was made by mixing epoxy resin and organic scintillators under various conditions. The optimal mixture ratio to prepare the plastic scintillator was derived from the above results. Using the derived results, we made the large-area plastic scintillator which can quickly measure the contamination site and evaluated characteristics of the large-area plastic scintillator in the laboratory. A thin plate of a plastic scintillator with a simple preparation process can be freely shaped using epoxy resin and organic scintillators such as PPO and POPOP. PPO emits scintillation of light in the ultraviolet range, and POPOP is a wave shifter for moving the wavelength responsible for the PMT. The mixture ratio of PPO and POPOP was determined using their emission spectra. The optimal weight percentage of PPO and POPOP in an organic scintillator was determined to be 0.2 wt%:0.01 wt%. Based on the above results, the large-area plastic scintillator of the window size of a typical pancake-type αβ surface contamination counter was prepared. We want to evaluate the characteristics of the large-area plastic scintillator. However, there were the difficulties in evaluating characteristics of the large-area plastic scintillator. The cross-sectional area of the large-area plastic scintillator is significantly different to PMT.

  14. Thallium magnesium chloride: A high light yield, large effective atomic number, intrinsically activated crystalline scintillator for X-ray and gamma-ray detection

    Science.gov (United States)

    Fujimoto, Yutaka; Koshimizu, Masanori; Yanagida, Takayuki; Okada, Go; Saeki, Keiichiro; Asai, Keisuke

    2016-09-01

    We report the luminescence and the scintillation properties of a newly developed thallium magnesium chloride (TlMgCl3) crystal. The crystal sample can be easily fabricated from the melt using the Bridgman method. The photoluminescence band appeared near the wavelength of 405 nm under excitation at 230 nm. An X-ray-induced scintillation spectrum showed an intense emission band near the wavelength of 405 nm. The decay time constant was estimated to be approximately 60 ns (∼25%) and 350 ns (∼75%) using a bi-exponential fitting. The scintillation light yield reached 46,000 photons/MeV with an energy resolution of 5% at 662 keV.

  15. 3D reconstruction of scintillation light emission from proton pencil beams using limited viewing angles—a simulation study

    International Nuclear Information System (INIS)

    Hui, CheukKai; Robertson, Daniel; Beddar, Sam

    2014-01-01

    An accurate and high-resolution quality assurance (QA) method for proton radiotherapy beams is necessary to ensure correct dose delivery to the target. Detectors based on a large volume of liquid scintillator have shown great promise in providing fast and high-resolution measurements of proton treatment fields. However, previous work with these detectors has been limited to two-dimensional measurements, and the quantitative measurement of dose distributions was lacking. The purpose of the current study is to assess the feasibility of reconstructing three-dimensional (3D) scintillation light distributions of spot scanning proton beams using a scintillation system. The proposed system consists of a tank of liquid scintillator imaged by charge-coupled device cameras at three orthogonal viewing angles. Because of the limited number of viewing angles, we developed a profile-based technique to obtain an initial estimate that can improve the quality of the 3D reconstruction. We found that our proposed scintillator system and profile-based technique can reconstruct a single energy proton beam in 3D with a gamma passing rate (3%/3 mm local) of 100.0%. For a single energy layer of an intensity modulated proton therapy prostate treatment plan, the proposed method can reconstruct the 3D light distribution with a gamma pass rate (3%/3 mm local) of 99.7%. In addition, we also found that the proposed method is effective in detecting errors in the treatment plan, indicating that it can be a very useful tool for 3D proton beam QA. (paper)

  16. Scintillation properties of LiF–SrF{sub 2} and LiF–CaF{sub 2} eutectic

    Energy Technology Data Exchange (ETDEWEB)

    Yanagida, Takayuki, E-mail: yanagida@lsse.kyutech.ac.jp [Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu 808-0196 (Japan); Kawaguchi, Noriaki [Tokuyama Corporation, 1-1 Mikage-cho, Shunan-shi, Yamaguchi 745-8648 (Japan); Fujimoto, Yutaka [Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu 808-0196 (Japan); Fukuda, Kentaro [Tokuyama Corporation, 1-1 Mikage-cho, Shunan-shi, Yamaguchi 745-8648 (Japan); Watanabe, Kenichi; Yamazaki, Atsushi; Uritani, Akira [Quantum Science and Energy Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2013-12-15

    Dopant free eutectic scintillators {sup 6}LiF–SrF{sub 2} and {sup 6}LiF–CaF{sub 2} were developed by the vertical Bridgeman method for the purpose of thermal neutron detection. The molar ratio of LiF and Ca/SrF{sub 2} was 4:1 on its eutectic composition. The α-ray induced radioluminescence spectra of the scintillators showed intense emission peak at 300 nm due to the emission from the self-trapped exciton in Ca/SrF{sub 2} layers. When the samples were irradiated with {sup 252}Cf neutrons, {sup 6}LiF–SrF{sub 2} and {sup 6}LiF–CaF{sub 2} exhibited the light yields of 4700 and 9400 ph/n, respectively. Scintillation decay times of {sup 6}LiF–SrF{sub 2} and {sup 6}LiF–CaF{sub 2} were accepted for scintillation detectors, 90 and 250 ns, respectively. -- Highlights: • Nondoped LiF–CaF{sub 2} and LiF–SrF{sub 2} eutectic scinitillators are reported for the first time. • Two sample showed self-trapped exciton emission. • LiF–SrF{sub 2} sample exhibited the light yield of 9400 ph/n and this value was comparable to conventional materials doped with rare earth ions. • Scintillation decay times of LiF–CaF{sub 2} and LiF–SrF{sub 2} were 250 and 90 ns, respectively.

  17. Recent developments in plastic scintillators with pulse shape discrimination

    Science.gov (United States)

    Zaitseva, N. P.; Glenn, A. M.; Mabe, A. N.; Carman, M. L.; Hurlbut, C. R.; Inman, J. W.; Payne, S. A.

    2018-05-01

    The paper reports results of studies conducted to improve scintillation performance of plastic scintillators capable of neutron/gamma pulse-shape discrimination (PSD). Compositional modifications made with the polymer matrix improved physical stability, allowing for increased loads of the primary dye that, in combination with selected secondary dyes, provided enhanced PSD especially important for the lower energy ranges. Additional measurements were made with a newly-introduced PSD plastic EJ-276, that replaces the first commercially produced EJ-299. Comparative studies conducted with the new materials and EJ-309 liquids at large scale (up to 10 cm) show that current plastics may provide scintillation and PSD performance sufficient for the replacement of liquid scintillators. Comparison to stilbene single crystals compliments the information about the status of the solid-state materials recently developed for fast neutron detection applications.

  18. Proton damage measurements of rare earth oxide scintillators

    International Nuclear Information System (INIS)

    Hollerman, W.A.; Fisher, J.H.; Shelby, G.A.; Holland, L.R.; Jenkins, G.M.

    1990-01-01

    This paper reports on the development of a measurement technique to determine the degradation in light output under exposure to 3 MeV protons. The rare earth oxide scintillators included Gd 2 O 2 S doped with Pr, Tb, and Eu; Y 2 O 2 S doped with Tb and Eu; Y 3 Al 5 O 12 (YAG) doped with Ce; and ZnS doped with Ag. Four scintillator samples were painted on a rotable water cooled turret used to measure the proton beam current with thermocouples for temperature monitoring. The data acquisition and storage system consists of an ACRO module interfaced to a Macintosh SE/30 computer running LabVIEW software. Results indicate that the YAG doped with Ce scintillator coating withstood a proton dose an order of magnitude larger than that tolerated by the other phosphor compounds. This fact has significant implications for the use of this material for experimental scintillator applications

  19. Photonic Crystals: Enhancing the Light Output of Scintillation Based Detectors

    CERN Document Server

    Knapitsch, Arno Richard

    A scintillator is a material which emits light when excited by ionizing radiation. Such materials are used in a diverse range of applications; From high energy particle physics experiments, X-ray security, to nuclear cameras or positron emission tomography. Future high-energy physics (HEP) experiments as well as next generation medical imaging applications are more and more pushing towards better scintillation characteristics. One of the problems in heavy scintillating materials is related to their high index of refraction. As a consequence, most of the scintillation light produced in the bulk material is trapped inside the crystal due to total internal reflection. The same problem also occurs with light emitting diodes (LEDs) and has for a long time been considered as a limiting factor for their overall efficiency. Recent developments in the area of nanophotonics were showing now that those limitations can be overcome by introducing a photonic crystal (PhC) slab at the outcoupling surface of the substrate. P...

  20. Inorganic scintillators for detector systems physical principles and crystal engineering

    CERN Document Server

    Lecoq, Paul; Korzhik, Mikhail

    2017-01-01

    This second edition features new chapters highlighting advances in our understanding of the behavior and properties of scintillators, and the discovery of new families of materials with light yield and excellent energy resolution very close to the theoretical limit. The book focuses on the discovery of next-generation scintillation materials and on a deeper understanding of fundamental processes. Such novel materials with high light yield as well as significant advances in crystal engineering offer exciting new perspectives. Most promising is the application of scintillators for precise time tagging of events, at the level of 100 ps or higher, heralding a new era in medical applications and particle physics. Since the discovery of the Higgs Boson with a clear signature in the lead tungstate scintillating blocks of the CMS Electromagnetic Calorimeter detector, the current trend in particle physics is toward very high luminosity colliders, in which timing performance will ultimately be essential to mitigating...

  1. Energy response and reaction losses in plastic scintillators

    International Nuclear Information System (INIS)

    Papandreou, Z.; Lolos, G.J.; Huber, G.M.; Cormier, J.C.; Naqvi, S.I.H.; Mathie, E.L.; Jones, G.; Trelle, R.P.; Alanoglu, X.; Orfanakos, S.

    1987-12-01

    The energy dependence of the scintillation response (light output) of plastic scintillator BC400 has been investigated for protons in the energy region of 60 to 220 MeV. In this region the scintillation exhibits a linear response, as well as a noticeable difference in the light output between stopping and passing-through (transmission) protons. A comparison between our results and theoretical calculations is presented. Losses due to edge effects have been separated from losses due to the bona-fide reaction of protons in the scintillator with the aid of Multi-Wire Proportional Chamber (MWPC) trajectory information. The number of events associated with reaction losses was found to range from 10% to 25% of the total number of events, depending on the incident proton kinetic energy. (Author) (12 refs., tab., 2 figs.)

  2. A sensitivity analysis approach to optical parameters of scintillation detectors

    International Nuclear Information System (INIS)

    Ghal-Eh, N.; Koohi-Fayegh, R.

    2008-01-01

    In this study, an extended version of the Monte Carlo light transport code, PHOTRACK, has been used for a sensitivity analysis to estimate the importance of different wavelength-dependent parameters in the modelling of light collection process in scintillators

  3. Mechanical deformation effect on CsI(Tl) scintillators efficiency

    International Nuclear Information System (INIS)

    Gayshan, V.; Boyarintsev, A.; Gektin, A.; Zosim, D.

    2003-01-01

    Due to the technological limitations in scintillation crystal growth and machining afterwards, crystals always contain certain internal defects and nonuniform distribution of intrinsic stresses. This work is directed to study the effect of CsI(Tl) mechanical deformation on their scintillation efficiency. It is shown that light output changes depend on the type of deformation (shock, steady deformation) and crystallographic orientation of specimen. The value of the phenomenon reaches up to 20% of the CsI(Tl) light output. Stress relaxation is the reason for the scintillator light output recovery. For CsI(Tl) scintillator mechanical deformation effects on light output will significantly decrease in the first 7-10 days after application of the stress and might completely disappear within 30-40 days

  4. High-density scintillating glasses for a proton imaging detector

    Science.gov (United States)

    Tillman, I. J.; Dettmann, M. A.; Herrig, V.; Thune, Z. L.; Zieser, A. J.; Michalek, S. F.; Been, M. O.; Martinez-Szewczyk, M. M.; Koster, H. J.; Wilkinson, C. J.; Kielty, M. W.; Jacobsohn, L. G.; Akgun, U.

    2017-06-01

    High-density scintillating glasses are proposed for a novel proton-imaging device that can improve the accuracy of the hadron therapy. High-density scintillating glasses are needed to build a cost effective, compact calorimeter that can be attached to a gantry. This report summarizes the study on Europium, Terbium, and Cerium-doped scintillating glasses that were developed containing heavy elements such as Lanthanum, Gadolinium, and Tungsten. The density of the samples reach up to 5.9 g/cm3, and their 300-600 nm emission overlaps perfectly with the peak cathode sensitivity of the commercial photo detectors. The developed glasses do not require any special quenching and can be poured easily, which makes them a good candidate for production in various geometries. Here, the glass making conditions, preliminary tests on optical and physical properties of these scintillating, high-density, oxide glasses developed for a novel medical imaging application are reported.

  5. Scintillation Particle Detectors Based on Plastic Optical Fibres and Microfluidics

    CERN Document Server

    Mapelli, Alessandro; Renaud, Philippe

    2011-01-01

    This thesis presents the design, development, and experimental validation of two types of scintillation particle detectors with high spatial resolution. The first one is based on the well established scintillating fibre technology. It will complement the ATLAS (A Toroidal Large ApparatuS) detector at the CERN Large Hadron Collider (LHC). The second detector consists in a microfabricated device used to demonstrate the principle of operation of a novel type of scintillation detector based on microfluidics. The first part of the thesis presents the work performed on a scintillating fibre tracking system for the ATLAS experiment. It will measure the trajectory of protons elastically scattered at very small angles to determine the absolute luminosity of the CERN LHC collider at the ATLAS interaction point. The luminosity of an accelerator characterizes its performance. It is a process-independent parameter that is completely determined by the properties of the colliding beams and it relates the cross section of a ...

  6. Inorganic Scintillators for Detector Systems Physical Principles and Crystal Engineering

    CERN Document Server

    AUTHOR|(CDS)2068219; Gektin, Alexander; Korzhik, Mikhail; Pédrini, Christian

    2006-01-01

    The development of new scintillators as components of modern detector systems is increasingly defined by the end user's needs. This book provides an introduction to this emerging topic at the interface of physics and materials sciences, with emphasis on bulk inorganic scintillators. After surveying the end user's needs in a vast range of applications, ranging from astrophysics to industrial R & D, the authors move on to review scintillating mechanisms and the properties of the most important materials used. A chapter on crystal engineering and examples of recent developments in the field of high-energy physics and medical imaging introduce the reader to the practical aspects. This book will benefit researchers and scientists working in academic and industrial R & D related to the development of scintillators.

  7. Multilayer Scintillation Detector for Nuclear Physics Monitoring of Space Weather

    Science.gov (United States)

    Batischev, A. G.; Aleksandrin, S. Yu.; Gurov, Yu. B.; Koldashov, S. V.; Lapushkin, S. V.; Mayorov, A. G.

    The physical characteristics of the multilayer scintillation spectrometer (MSS) for identification and energy measurement of cosmic electrons, positrons and nuclei are considered in this paper. This spectrometer is made on the basis of several plastic scintillator plates with various thick viewed by photomultipliers. Two upper layers are strips of orthogonal scintillators. The nuclei energy measurement range is 3 - 100 MeV/nucleon. Spectrometer is planning for space weather monitoring and investigation of solar-magnetospheric and geophysics effects on satellite. MSS time resolution is about 1 microsecond and it can measure the time profiles of fast processes in the Earth's magnetosphere. Spectrometer experimental characteristics were estimated by means of computer simulation. The ionization loss fluctuations, ion charge exchange during pass through detector and, especially, scintillation quenching effect (Bircs effect) were taken into account in calculations.

  8. Set of counts by scintillations for atmospheric samplings

    International Nuclear Information System (INIS)

    Appriou, D.; Doury, A.

    1962-01-01

    The author reports the development of a scintillation-based counting assembly with the following characteristics: a photo-multiplier with a wide photo-cathode, a thin plastic scintillator for the counting of beta + alpha (and possibility of mounting an alpha scintillator), a relatively small own motion with respect to activities to be counted, a weakly varying efficiency. The authors discuss the counting objective, present equipment tests (counter, proportional amplifier and pre-amplifier, input drawer). They describe the apparatus operation, discuss the selection of scintillators, report the study of the own movement (electron-based background noise, total background noise, background noise reduction), discuss counts (influence of the external source, sensitivity to alpha radiations, counting homogeneity, minimum detectable activity) and efficiencies

  9. Use of pliable bags in liquid scintillation counting

    International Nuclear Information System (INIS)

    Simonnet, G.; Jacquet, M.A.; Sharif, A.; Engler, R.

    1981-01-01

    Pliable plastic bags have been used to replace glass or plastic vials for liquid scintillation counting. The two major advantages of this method are the lower cost of the plastic bags and the fact that, per sample, the radioactive waste is significantly reduced. The following parameters have been checked: the impermeability of the bags to various scintillator mixtures and the fact that neither the irregular shape of the bags nor their position in the counting chamber had any effect on the results of the counting. The latter was also constant with time, at least over a period of 10 days. The technique has been used to count the radioactivity of 3 H-DNA precipitates prepared from bacteria and lymphocytes and deposited on filters impregnated with only 200 μl scintillator. It is a method that can be applied to the counting of any samples deposited on filters and insoluble in scintillator. (author)

  10. Search of new scintillation materials for nuclear medicine application

    CERN Document Server

    Korzhik, M V

    2000-01-01

    Oxide crystals have a great potential to develop new advanced scintillation materials which are dense, fast, and bright. This combination of parameters, when combined to affordable price, gives a prospect for materials to be applied in nuclear medicine devices. Some of them have been developed for the last two decades along the line of rear-earth (RE) garnet (RE/sub 3/Al/sub 5/O/sub 12/) oxiorthosilicate (RE/sub 2/SiO/sub 5/) and perovskite (REAlO/sub 3/) crystals doped with Ce ions. Among recently developed oxide materials the lead tungstate scintillator (PWO) becomes the most used scintillation material in high energy physics experiments due to its application in CMS and ALICE experiments at LHC. In this paper we discuss scintillation properties of some new heavy compounds doped with Ce as well as light yield improvement of PWO crystals to apply them in low energy physics and nuclear medicine. (18 refs).

  11. Final LDRD report : advanced plastic scintillators for neutron detection.

    Energy Technology Data Exchange (ETDEWEB)

    Vance, Andrew L.; Mascarenhas, Nicholas; O' Bryan, Greg; Mrowka, Stanley

    2010-09-01

    This report summarizes the results of a one-year, feasibility-scale LDRD project that was conducted with the goal of developing new plastic scintillators capable of pulse shape discrimination (PSD) for neutron detection. Copolymers composed of matrix materials such as poly(methyl methacrylate) (PMMA) and blocks containing trans-stilbene (tSB) as the scintillator component were prepared and tested for gamma/neutron response. Block copolymer synthesis utilizing tSBMA proved unsuccessful so random copolymers containing up to 30% tSB were prepared. These copolymers were found to function as scintillators upon exposure to gamma radiation; however, they did not exhibit PSD when exposed to a neutron source. This project, while falling short of its ultimate goal, demonstrated the possible utility of single-component, undoped plastics as scintillators for applications that do not require PSD.

  12. Liquid scintillation cocktails comparison for tritium contamination measurements

    International Nuclear Information System (INIS)

    Bazzarri, S.; Belloni, P.

    1996-01-01

    Liquid scintillation counting is one of the most used techniques for the measurements of tritium contamination. Until few years ago a problem related to this kind of measurement was the potential toxicity of the liquid cocktails used to produce the required scintillation. Some new products that guarantee an almost negligible impact on the environment and that are no longer toxic for the operators are now available. Some of this new scintillation cocktail are suitable to be used for tritium measurement. Due to the great benefit from the health point of view of these new materials a test of their scintillation performance has been done at the ENEA centers to select the product having the best characteristics for tritium measurement. (author)

  13. Comparison of the methods for determination of scintillation light yield

    CERN Document Server

    Sysoeva, E; Zelenskaya, O

    2002-01-01

    One of the most important characteristics of scintillators is the light yield. It depends not only on the properties of scintillators, but also on the conditions of measurements. Even for widely used crystals, such as alkali halide scintillators NaI(Tl) and CsI(Tl), light yield data, obtained by various authors, are different. Therefore, it is very important to choose the convenient method of the light yield measurements. In the present work, methods for the determination of the physical light yield, based on measurements of pulse amplitude, single-electron pulses and intrinsic photomultiplier resolution are discussed. These methods have been used for the measurements of light yield of alkali halide crystals and oxide scintillators. Repeatability and reproducibility of results were determined. All these methods are rather complicated in use, not for measurements, but for further data processing. Besides that, they demand a precise determination of photoreceiver's parameters, as well as determination of light ...

  14. Large liquid-scintillator trackers for neutrino experiments

    CERN Document Server

    Benussi, L; D'Ambrosio, N; Déclais, Y; Dupraz, J P; Fabre, Jean-Paul; Fanti, V; Forton, E; Frekers, D; Frenkel, A; Girerd, C; Golovkin, S V; Grégoire, G; Harrison, K; Jonkmans, G; Jonsson, P; Katsanevas, S; Kreslo, I; Marteau, J; Martellotti, G; Martínez, S; Medvedkov, A M; Moret, G; Niwa, K; Novikov, V; Van Beek, G; Penso, G; Vasilchenko, V G; Vuilleumier, J L; Wilquet, G; Zucchelli, P; Kreslo, I E

    2002-01-01

    Results are given on tests of large particle trackers for the detection of neutrino interactions in long-baseline experiments. Module prototypes have been assembled using TiO$_2$-doped polycarbonate panels. These were subdivided into cells of $\\sim 1$~cm$^2$ cross section and 6~m length, filled with liquid scintillator. A wavelength-shifting fibre inserted in each cell captured a part of the scintillation light emitted when a cell was traversed by an ionizing particle. Two different fibre-readout systems have been tested: an optoelectronic chain comprising an image intensifier and an Electron Bombarded CCD (EBCCD); and a hybrid photodiode~(HPD). New, low-cost liquid scintillators have been investigated for applications in large underground detectors. Testbeam studies have been performed using a commercially available liquid scintillator. The number of detected photoelectrons for minimum-ionizing particles crossing a module at different distances from the fibre readout end was 6 to 12 with the EBCCD chain and ...

  15. Detection of {sup 8}B solar neutrinos in liquid scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Ianni, A [Laboratori Nazionali del Gran Sasso and INFN, I-67010 Assergi (Italy); Montanino, D [Dipartimento di Fisica, Universita' di Lecce and INFN, I-73100 Lecce (Italy); Villante, F L [Dipartimento di Fisica, Universita di Ferrara and INFN, I-44100 Ferrara (Italy)

    2006-05-15

    We show that liquid organic scintillator detectors (e. g., KamLAND and Borexino) can measure the {sup 8}B solar neutrino flux by means of the {nu}{sub e} charged current interaction with the {sup 13}C nuclei naturally contained in the scintillators. The neutrino events can be identified by exploiting the time and space coincidence with the subsequent decay of the produced {sup 13}N nuclei.

  16. Development of water radiocontamination monitor using a plastic scintillator detector

    International Nuclear Information System (INIS)

    Mesquita, C.H. de; Madi Filho, T.; Hamada, M.M.

    1990-01-01

    An alpha, beta and gamma radiation water monitor was developed using a plastic scintillator detector with a sensitivity level of 15 bplastic scintillator detector with a sensitivity level of 15 Bq.L -1 and a counting efficiency of 25% for 131 I. It was proposed to be used in the radiation monitoring program of the research reactor swimming-pool of Sao Paulo. A simplified design and some properties of this monitor are presented. (author) [pt

  17. Scintillator for radiation detection and process for producing the same

    International Nuclear Information System (INIS)

    Ishii, M.; Akiyama, S.; Ishibashi, H.

    1985-01-01

    A scintillator for radiation detection obtained by coating a light reflective material in a thickness of 50 to 150 μm by a screen printing method on the surface of a solid scintillator material substrate is excellent in uniformity, dimensional accuracy with high light output. When the light reflective material layer is covered with a synthetic resin film, adhesive strength of the light reflective material layer to the substrate is increased remarkably

  18. Multiple event 2D image intensifier scintillation detector

    International Nuclear Information System (INIS)

    Thieberger, P.; Wegner, H.E.; Lee, R.C.

    1981-01-01

    An image intensifier scintillation detector has been developed for the simultaneous detection of multiple light or heavy ions down to very low energies. The relative X-Y positions of each ion are read out by digitization of a television image of the light amplified scintillations. The maximum data rate is limited by the present television scan speed to 15 multiple events per second and to about one event second by the microcomputer presently used to store and process the data. (orig.)

  19. Performance studies of scintillating ceramic samples exposed to ionizing radiation

    CERN Document Server

    Dissertori, G; Nessi-Tedaldi, F; Wallny, R

    2014-01-01

    Scintillating ceramics are a promising, new development for various applications in science and industry. Their application in calorimetry for particle physics experiments is expected to involve an exposure to high levels of ionizing radiation. In this paper, changes in performance have been measured for scintillating ceramic samples of different composition after exposure to penetrating ionizing radiation up to a dose of 38 kGy. 2012 IEEE Nuclear Science Symposium Conference Record

  20. Simulation study of liquid scintillator based 4π neutron detector

    International Nuclear Information System (INIS)

    Banerjee, K.; Kundu, S.; Bhattacharya, C.; Dey, A.; Bhattacharya, S.

    2004-01-01

    Neutron multiplicity detectors play an important role in deciphering the complexities of intermediate energy nucleus-nucleus reactions. Several neutron multiplicity detectors are in operation. As part of the super conducting cyclotron utilization project, it has been planned to make one liquid scintillator based neutron multiplicity detector at VECC, Kolkata. Here reported are initial results of the simulation study of the characteristics of a large liquid scintillator based neutron multiplicity detector

  1. Liquid scintillators and composites in fast neutron detection

    Science.gov (United States)

    Iwanowska, J.; Swiderski, L.; Moszynski, M.

    2012-04-01

    Helium-3 world crisis requires a development of new methods of neutron detection to replace commonly used 3He proportional counters. One of the option is application of liquid scintillators widely used in detection of fast neutrons, mostly in physics experiments, especially in applications where large volumes are required. Moreover, recently studied 10B loaded liquid scintillators cover detection of neutrons down to thermal energy. The several years' studies of liquid scintillators in our laboratory, brought us a knowledge about their efficiency to neutron detection, gamma sensitivity, etc. We have also tested composite scintillators, which are an alternative to organic single crystals, used in the 70's last century. In the report, we will present the results of the study of several liquid scintillators, also 10B loaded, as well as high flashpoint ones. We also show the neutron detection properties of some samples of composite scintillators. Composites are based on small grains of p-terphenyl or stilbene, introduced into a polymer matrix, which acts as a diffuser. The composite is encapsulated in a housing made of organic glass. P-terphenyl and stilbene are organic scintillators, which were commonly used in the seventies last century. They are characterized by good neutron/gamma discrimination properties. The present studies covers neutron/gamma discrimination by the zero-crossing method, a comparison of detection efficiency of liquid scintillators to 3He detectors and methods to reduce their gamma-ray sensitivity. In conclusion, a detection system, based on several small liquid cells of 2'' × 2'', is preferred, with pulse shape discrimination circuit equipped with the pile-up rejection circuit (PUR), as well as lead and tin shielding.

  2. Research to Operations of Ionospheric Scintillation Detection and Forecasting

    Science.gov (United States)

    Jones, J.; Scro, K.; Payne, D.; Ruhge, R.; Erickson, B.; Andorka, S.; Ludwig, C.; Karmann, J.; Ebelhar, D.

    Ionospheric Scintillation refers to random fluctuations in phase and amplitude of electromagnetic waves caused by a rapidly varying refractive index due to turbulent features in the ionosphere. Scintillation of transionospheric UHF and L-Band radio frequency signals is particularly troublesome since this phenomenon can lead to degradation of signal strength and integrity that can negatively impact satellite communications and navigation, radar, or radio signals from other systems that traverse or interact with the ionosphere. Although ionospheric scintillation occurs in both the equatorial and polar regions of the Earth, the focus of this modeling effort is on equatorial scintillation. The ionospheric scintillation model is data-driven in a sense that scintillation observations are used to perform detection and characterization of scintillation structures. These structures are then propagated to future times using drift and decay models to represent the natural evolution of ionospheric scintillation. The impact on radio signals is also determined by the model and represented in graphical format to the user. A frequency scaling algorithm allows for impact analysis on frequencies other than the observation frequencies. The project began with lab-grade software and through a tailored Agile development process, deployed operational-grade code to a DoD operational center. The Agile development process promotes adaptive promote adaptive planning, evolutionary development, early delivery, continuous improvement, regular collaboration with the customer, and encourage rapid and flexible response to customer-driven changes. The Agile philosophy values individuals and interactions over processes and tools, working software over comprehensive documentation, customer collaboration over contract negotiation, and responding to change over following a rigid plan. The end result was an operational capability that met customer expectations. Details of the model and the process of

  3. PMP, a novel solute for liquid and plastic scintillation counting

    International Nuclear Information System (INIS)

    Gusten, Hans

    1983-01-01

    The excellent fluorescence properties of PMP ( 11-phenyl-3-mesityl-2-pyrazoline) such as long wavelength emission of over 400 nm, and high fluorescence quantum yield with a short decay time together with a solubility of more than one Mol/L in toluene make this compound a promising solute for scintillation counting. The Stokes' shift of PMP of over 10,000 cm -1 is twice as large as that of the commonly used PPO. Due to this unusually large Stokes' shift PMP can be used as a primary solute without requiring a secondary solute as wavelength shifter. A comparison of the scintillation properties of PMP and PPO in toluene reveals that the counting efficiency for 14 C is better for PMP while the 3 H efficiency is equally good. Due to the large Stokes' shift, PMP is about 50 percent less sensitive to color quenching than PPO. Compared to the solute combinations PPO/secondary solutes, the scintillation counting efficiency of PMP for 14 C in toluene or xylene is the same, while the absolute 3 H efficiency of PPO/secondary solutes in cocktails with emulsifiers is about 10 percent higher. The PMP scintillation efficiency for 14 C as well as 3 H in chemical quenching by urine is more or less the same as for PPO/dimethyl-POPOP. PMP is more sensitive to quenching by halogenated solvents. In the dioxane-based scintillation, this sensitivity to chemical quenching by CHCl 3 vanishes and the counting efficiencies for 14 C and 3 H are as good as for PPO/dimethyl-POPOP or PPO/bis-MSB. Due to the large Stokes' shift, the self-absorption of the scintillation light by PMP is lower than in conventional scintillators. This offers good possibilities in very large-volume applications of liquid as well as plastic scintillators

  4. High effective atomic number polymer scintillators for gamma ray spectroscopy

    Science.gov (United States)

    Cherepy, Nerine Jane; Sanner, Robert Dean; Payne, Stephen Anthony; Rupert, Benjamin Lee; Sturm, Benjamin Walter

    2014-04-15

    A scintillator material according to one embodiment includes a bismuth-loaded aromatic polymer having an energy resolution at 662 keV of less than about 10%. A scintillator material according to another embodiment includes a bismuth-loaded aromatic polymer having a fluor incorporated therewith and an energy resolution at 662 keV of less than about 10%. Additional systems and methods are also presented.

  5. High resolution scintillation hodoscope using a position sensitive photomultiplier

    International Nuclear Information System (INIS)

    Ditta, J.; Sillou, D.; Michalowicz, A.; Azaiez, H.; Kuroda, K.

    1983-09-01

    Using a position sensitive photomultiplier we have realized and tested a prototype of high resolution scintillation hodoscope. A space resolution of approximately 1 mm (FWHM) has been obtained by a single block of NE102A scintillator, 10 mm thick, with 10 GeV/c π - particles. An off-line analysis based on the moment method has confirmed the fact that suitable cuts in the second-order moments provides a powerful criterion for improving the image quality

  6. Progress in PbWO4 scintillating crystal

    International Nuclear Information System (INIS)

    Fyodorov, A.; Korzhik, M.; Missevitch, O.; Pavlenko, V.; Kachanov, V.; Singovsky, A.; Annenkov, A.N.; Ligun, V.A.; Peigneux, J.P.; Vialle, J.P.

    1994-12-01

    Lead tungstate PbWO 4 (PWO) has recently been shown to be a promising scintillating material for precise electromagnetic calorimetry. Modifications of PWO technology were made to improve the uniformity of the crystal properties. A model of the scintillation mechanism for PWO was developed and served to guide the improvement. The complex spectroscopic analysis of the crystal after improvement is presented, as well as the new crystal properties achieved. (K.A.). 14 refs., 14 figs., 4 tabs

  7. A directional fast neutron detector using scintillating fibers and an intensified CCD camera system

    International Nuclear Information System (INIS)

    Holslin, Daniel; Armstrong, A.W.; Hagan, William; Shreve, David; Smith, Scott

    1994-01-01

    We have been developing and testing a scintillating fiber detector (SFD) for use as a fast neutron sensor which can discriminate against neutrons entering at angles non-parallel to the fiber axis (''directionality''). The detector/convertor component is a fiber bundle constructed of plastic scintillating fibers each measuring 10 cm long and either 0.3 mm or 0.5 mm in diameter. Extensive Monte Carlo simulations were made to optimize the bundle response to a range of fast neutron energies and to intense fluxes of high energy gamma-rays. The bundle is coupled to a set of gamma-ray insenitive electro-optic intensifiers whose output is viewed by a CCD camera directly coupled to the intensifiers. Two types of CCD cameras were utilized: 1) a standard, interline RS-170 camera with electronic shuttering and 2) a high-speed (up to 850 frame/s) field-transfer camera. Measurements of the neutron detection efficiency and directionality were made using 14 MeV neutrons, and the response to gamma-rays was performed using intense fluxes from radioisotopic sources (up to 20 R/h). Recently, the detector was constructed and tested using a large 10 cm by 10 cm square fiber bundle coupled to a 10 cm diameter GEN I intensifier tube. We present a description of the various detector systems and report the results of experimental tests. ((orig.))

  8. Scintillation analysis of multiple-input single-output underwater optical links.

    Science.gov (United States)

    Gökçe, Muhsİn Caner; Baykal, Yahya

    2016-08-01

    Multiple-input single-output (MISO) techniques are employed in underwater wireless optical communication (UWOC) links to mitigate the degrading effects of oceanic turbulence. In this paper, we consider a MISO UWOC system which consists of a laser beam array as transmitter and a point detector as receiver. Our aim is to find the scintillation index at the detector in order to quantify the system performance. For this purpose, the average intensity and the average of the square of the intensity are derived in underwater turbulence by using the extended Huygens-Fresnel principle. The scintillation index and the average bit-error-rate (⟨BER⟩) formulas presented in this paper depend on the oceanic turbulence parameters, such as the rate of dissipation of the mean-squared temperature, rate of dissipation of kinetic energy per unit mass of fluid, Kolmogorov microscale, and the ratio of temperature to salinity contributions to the refractive index spectrum, the link length, and the wavelength. Recently, we have derived an equivalent structure constant of atmospheric turbulence and expressed it in terms of the oceanic turbulence parameters [Appl. Opt.55, 1228 (2016)APOPAI0003-693510.1364/AO.55.001228]. In the formulation in this paper, this equivalent structure constant is utilized, which enables us to employ the existing similar formulation valid in atmospheric turbulence.

  9. PALS investigations of free volumes thermal expansion of J-PET plastic scintillator synthesized in polystyrene matrix

    Directory of Open Access Journals (Sweden)

    Wieczorek Anna

    2015-12-01

    Full Text Available The polystyrene doped with 2,5-diphenyloxazole as a primary fluor and 2-(4-styrylphenylbenzoxazole as a wavelength shifter prepared as a plastic scintillator was investigated using positronium probe in wide range of temperatures from 123 to 423 K. Three structural transitions at 260, 283, and 370 K were found in the material. In the o-Ps intensity dependence on temperature, the significant hysteresis is observed. Heated to 370 K, the material exhibits the o-Ps intensity variations in time.

  10. Effects of atmospheric scintillation in Ka-band satellite communications

    Science.gov (United States)

    Borgsmiller, Scott A.

    This research is motivated by the need to characterize the effects of atmospheric scintillation on Ka-band satellite communications. The builders of satellite communications systems are planning to utilize Ka-band in more than a dozen systems that have been proposed for launch in the next decade. The NASA ACTS (Advanced Communication Technology Satellite) program has provided a means to investigate the problems associated with Ka-band satellite transmissions. Experimental measurements have been conducted using a very small aperture terminal (VSAT) to evaluate the effects of scintillation on narrowband and wideband signals. The theoretical background of scintillation theory is presented, noting especially the additional performance degradation predicted for wideband Ka-band systems using VSATs. Experimental measurements of the amplitude and phase variations in received narrowband carrier signals were performed, using beacon signals transmitted by ACTS and carrier signals which are relayed through the satellite. Measured amplitude and phase spectra have been compared with theoretical models to establish the presence of scintillation. Measurements have also been performed on wideband spread spectrum signals which are relayed through ACTS to determine the bit-error rate degradation of the digital signal resulting from scintillation effects. The theory and measurements presented for the geostationary ACTS have then been applied to a low-earth orbiting satellite system, by extrapolating the effects of the moving propagation path on scintillation.

  11. Red Emitting Phenyl-Polysiloxane Based Scintillators for Neutron Detection

    International Nuclear Information System (INIS)

    Dalla Palma, Matteo; Quaranta, Alberto; Marchi, Tommaso; Gramegna, Fabiana; Cinausero, Marco; Carturan, Sara; Collazuol, Gianmaria

    2013-06-01

    In this work, the performances of new red emitting phenyl- substituted polysiloxane based scintillators are described. Three dyes were dispersed in a phenyl-polysiloxane matrix in order to shift the scintillation wavelength towards the red part of the visible spectrum. PPO, Lumogen Violet (BASF) and Lumogen Red (BASF) were mixed to the starting resins with different wt. % and the analysis of the different samples was performed by means of fluorescence measurements. The scintillation yield to alpha particles at the different dye ratios was monitored by detecting either the full spectrum or the red part of the emitted light. Finally, thin red scintillators with selected compositions were coupled to Avalanche Photodiode sensors, which are usually characterized by higher efficiency in the red part of the spectrum. An increased light output of about 17% has been obtained comparing the red scintillators to standard blue emitting systems. Preliminary results on the detection of fast neutrons with the APD-red scintillator system are also presented. (authors)

  12. Fast neutron detection with 6Li-loaded liquid scintillator

    Science.gov (United States)

    Fisher, B. M.; Abdurashitov, J. N.; Coakley, K. J.; Gavrin, V. N.; Gilliam, D. M.; Nico, J. S.; Shikhin, A. A.; Thompson, A. K.; Vecchia, D. F.; Yants, V. E.

    2011-08-01

    We report on the development of a fast neutron detector using a liquid scintillator doped with enriched 6Li. The lithium was introduced in the form of an aqueous LiCl micro-emulsion with a di-isopropylnaphthalene-based liquid scintillator. A 6Li concentration of 0.15% by weight was obtained. A 125 mL glass cell was filled with the scintillator and irradiated with fission-source neutrons. Fast neutrons may produce recoil protons in the scintillator, and those neutrons that thermalize within the detector volume can be captured on the 6Li. The energy of the neutron may be determined by the light output from recoiling protons, and the capture of the delayed thermal neutron reduces background events. In this paper, we discuss the development of this 6Li-loaded liquid scintillator, demonstrate the operation of it in a detector, and compare its efficiency and capture lifetime with Monte Carlo simulations. Data from a boron-loaded plastic scintillator were acquired for comparison. We also present a pulse-shape discrimination method for differentiating between electronic and nuclear recoil events based on the Matusita distance between a normalized observed waveform and nuclear and electronic recoil template waveforms. The details of the measurements are discussed along with specifics of the data analysis and its comparison with the Monte Carlo simulation.

  13. Experiment to demonstrate separation of Cherenkov and scintillation signals

    Science.gov (United States)

    Caravaca, J.; Descamps, F. B.; Land, B. J.; Wallig, J.; Yeh, M.; Orebi Gann, G. D.

    2017-05-01

    The ability to separately identify the Cherenkov and scintillation light components produced in scintillating mediums holds the potential for a major breakthrough in neutrino detection technology, allowing development of a large, low-threshold, directional detector with a broad physics program. The CHESS (CHErenkov/Scintillation Separation) experiment employs an innovative detector design with an array of small, fast photomultiplier tubes and state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov ring in a scintillating medium based on photon hit time and detected photoelectron density. This paper describes the physical properties and calibration of CHESS along with first results. The ability to reconstruct Cherenkov rings is demonstrated in a water target, and a time precision of 338 ±12 ps FWHM is achieved. Monte Carlo-based predictions for the ring imaging sensitivity with a liquid scintillator target predict an efficiency for identifying Cherenkov hits of 94 ±1 % and 81 ±1 % in pure linear alkyl benzene (LAB) and LAB loaded with 2 g/L of a fluor, PPO, respectively, with a scintillation contamination of 12 ±1 % and 26 ±1 % .

  14. Strong field laser physics

    CERN Document Server

    2008-01-01

    Since the invention of the laser in the 1960s, people have strived to reach higher intensities and shorter pulse durations. High intensities and ultrashort pulse durations are intimately related. Recent developments have shown that high intensity lasers also open the way to realize pulses with the shortest durations to date, giving birth to the field of attosecond science (1 asec = 10-18s). This book is about high-intensity lasers and their applications. The goal is to give an up to date introduction to the technology behind these laser systems and to the broad range of intense laser applications. These applications include AMO (atomic molecular and optical) physics, x-ray science, attosecond science, plasma physics and particle acceleration, condensed matter science and laser micromachining, and finally even high-energy physics.

  15. Growth and scintillation properties of Eu doped BaCl.sub.2./sub./LiF eutectic scintillator

    Czech Academy of Sciences Publication Activity Database

    Kamada, K.; Hishinuma, K.; Kurosawa, S.; Yamaji, A.; Shoji, Y.; Pejchal, Jan; Yokota, Y.; Ohashi, Y.; Yoshikawa, A.

    2015-01-01

    Roč. 50, Dec (2015), 76-80 ISSN 0925- 3467 Institutional support: RVO:68378271 Keywords : scintillator * eutectic * micro-pulling down Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.183, year: 2015

  16. GNSS-based Observations and Simulations of Spectral Scintillation Indices in the Arctic Ionosphere

    DEFF Research Database (Denmark)

    Durgonics, Tibor; Hoeg, Per; von Benzon, Hans-Henrik

    , and development of data-driven methodologies to accurately localize ionospheric irregularities and simulate GNSS scintillation signals are highly desired. Ionospheric scintillations have traditionally been quantified by amplitude (S4) and phase scintillations (σφ). Our study focuses on the Arctic, where...... scintillations, especially phase scintillations, are prominent. We will present observations acquired from a network of Greenlandic GNSS stations, including 2D amplitude and phase scintillation index maps for representative calm and storm periods. In addition to the traditional indices described above, we....... The observations will then be compared to properties of simulated GNSS signals computed by the Fast Scintillation Mode (FSM). The FSM was developed to simulate ionospheric scintillations under different geophysical conditions, and is used to simulate GNSS signals with known scintillation characteristics...

  17. Alpha/beta pulse shape discrimination in plastic scintillation using commercial scintillation detectors

    International Nuclear Information System (INIS)

    Bagan, H.; Tarancon, A.; Rauret, G.; Garcia, J.F.

    2010-01-01

    Activity determination in different types of samples is a current need in many different fields. Simultaneously analysing alpha and beta emitters is now a routine option when using liquid scintillation (LS) and pulse shape discrimination. However, LS has an important drawback, the generation of mixed waste. Recently, several studies have shown the capability of plastic scintillation (PS) as an alternative to LS, but no research has been carried out to determine its capability for alpha/beta discrimination. The objective of this study was to evaluate the capability of PS to discriminate alpha/beta emitters on the basis of pulse shape analysis (PSA). The results obtained show that PS pulses had lower energy than LS pulses. As a consequence, a lower detection efficiency, a shift to lower energies and a better discrimination of beta and a worst discrimination of alpha disintegrations was observed for PS. Colour quenching also produced a decrease in the energy of the particles, as well as the effects described above. It is clear that in PS, the discrimination capability was correlated with the energy of the particles detected. Taking into account the discrimination capabilities of PS, a protocol for the measurement and the calculation of alpha and beta activities in mixtures using PS and commercial scintillation detectors has been proposed. The new protocol was applied to the quantification of spiked river water samples containing a pair of radionuclides ( 3 H- 241 Am or 90 Sr/ 90 Y- 241 Am) in different activity proportions. The relative errors in all determinations were lower than 7%. These results demonstrate the capability of PS to discriminate alpha/beta emitters on the basis of pulse shape and to quantify mixtures without generating mixed waste.

  18. Optical properties and structure of Pr3+-doped Al(PO3)3-LiF glasses as scattered neutron scintillator for nuclear fusion diagnostics

    International Nuclear Information System (INIS)

    Murata, T; Fujino, S; Yoshida, H; Arikawa, Y; Nakazato, T; Shimizu, T; Sarukura, N; Nakai, M; Norimatsu, T; Azechi, H; Kamada, K; Usuki, Y; Suyama, T; Yoshikawa, A; Sato, N; Kan, H

    2011-01-01

    Scattered neutron diagnostics is an indispensable tool for both inertial confinement and magnetic confinement fusion research. For this purpose, a fast-response neutron scintillator with a high cross section for scattered neutrons is strongly required. Recently, based on our material design strategy, we have successfully developed the fast response time Pr 3+ -doped 20Al(PO 3 ) 3 -80LiF glass scintillator for scattered neutron originated from inertial confinement fusion. The matrix glass 20Al(PO 3 ) 3 -80LiF shows good glass forming ability, chemical durability and transparency in the deep ultraviolet region. The purpose of this work is to investigate the glass structure of 20Al(PO 3 ) 3 -80LiF glasses using Raman spectroscopy and to discuss the relationship between physical and scintillation properties and glass structure.

  19. X-ray detection capability of a Cs2ZnCl4 single-crystal scintillator

    International Nuclear Information System (INIS)

    Yahaba, Natsuna; Koshimizu, Masanori; Sun, Yan; Asai, Keisuke; Yanagida, Takayuki; Fujimoto, Yutaka; Haruki, Rie; Nishikido, Fumihiko; Kishimoto, Shunji

    2014-01-01

    The X-ray detection capability of a scintillation detector equipped with a Cs 2 ZnCl 4 single crystal was evaluated. The scintillation decay kinetics can be expressed as the sum of two exponential decay components. The fast decay component had a decay time constant of 1.8 ns, and its relative intensity was 95%. The total light output was 630 photons/MeV, and a subnanosecond timing resolution of 0.66 ns was obtained. The detection efficiency of 67.4 keV X-rays was 80% for a detector equipped with a 2.2-mm-thick Cs 2 ZnCl 4 crystal. Thus, excellent timing resolution and high detection efficiency were achieved simultaneously. (author)

  20. Investigation on neutron/gamma discrimination phenomena in plastic scintillators

    International Nuclear Information System (INIS)

    Blanc, Pauline

    2014-01-01

    This PhD topic was born from misunderstandings and incomplete knowledge of the mechanism and relative effectiveness of neutron and gamma-ray (n/γ) discrimination between plastic scintillators compared to liquid scintillators. The shape of the light pulse these materials generate following interaction with an ionizing particle (predominantly recoil protons in the case of neutrons and electrons in the case of gamma-rays) is different in time in a way that depends on the detected particle (nature and energy). It is this fact that enables separation (PSD). The behavior in liquid scintillators has been extensively studied experimentally for practical applications. Only recently has it been shown that a weak separation can also be achieved using specially prepared plastics. The study of this system presents an open field and the understanding of both liquids and plastics with respect to their PSD properties is far from complete. This work is dedicated to exploring the fundamental photophysical phenomena at play in the generation of luminescence emission, following the interaction of ionizing radiation with organic scintillators. For this purpose, firstly a detailed literature review of the state-of-the-art has been conducted extending from 1960 to the present day. Secondly a complete characterization of the main scintillating materials has been conducted to define their fluorescence properties and the characteristics of their scintillation under irradiation. Thirdly a proton beam has been used to simulate recoil protons to quantify under controlled laboratory conditions their specific energy deposition in a plastic scintillator with PSD properties. The fourth part of this thesis is devoted to the study of PSD efficiency of scintillators as a function of their molecular structure. This investigation has led to a plastic scintillator prepared in our laboratory with good PSD properties and a patent submission. Finally, photophysical experiments were performed using a