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Sample records for beta-gamma coincidence measurements

  1. Novel Beta-Gamma Coincidence Measurements Using Phoswich Detectors

    International Nuclear Information System (INIS)

    The PNNL has developed an Automated Radio-xenon Sampler/Analyzer (ARSA) for the CTBT to measure four radio-xenon isotopes using a beta-gamma coincidence counting detector. A novel method to measure beta-gamma coincidences using a phoswich detector with state-of-the-art pulse shape discrimination techniques has been investigated

  2. Influence from low energy x-rays and Auger electrons on 4. pi beta. -. gamma. coincidence measurements of electron-capture-decaying nuclides

    Energy Technology Data Exchange (ETDEWEB)

    Funck, E.; Larsen, A.N. (Physikalisch-Technische Bundesanstalt, Braunschweig (Germany, F.R.). Abt. Atomphysik; Commission of the European Communities, Geel (Belgium). Central Bureau for Nuclear Measurements)

    1983-03-01

    The influence of low energy x-rays and Auger electrons emitted by electron capture nuclides on 4..pi beta..-..gamma.. coincidence measurements is investigated. Under the assumption that these radiations are not detected, correction terms are developed for a number of nuclides that are in common use.

  3. Deconvolution of three-dimensional beta-gamma coincidence spectra from xenon sampling and measurement units

    International Nuclear Information System (INIS)

    Some environmental xenon sampling like the Automated Radioxenon Sampler-Analyzer (ARSA) and the Swedish Automated Noble Gas Unit (SAUNA), use β-γ coincidence detectors that are energy dispersive on both the γ and β axes. Applying conventional region-of-interest (ROI) analysis algorithms to such 3-D spectra is problematic due to spectral interferences in the low-resolution spectra. Deconvolving the 3-D sample spectra into the most probable combination of signals using non-negative least-squares results shows promise to robustly resolve the spectral interferences. Multiple isotope component analysis (MICA) algorithm developed for analysis of 3-D β-γ spectra from xenon sampling and measurement units is described. (author)

  4. Study of a 4{pi}{beta}-{gamma} coincidence system for absolute radionuclide activity measurement using plastic scintillators; Estudo de um sistema de coincidencias 4{pi}{beta}-{gamma} para a medida absoluta de atividade de radionuclideos empregando cintiladores plasticos

    Energy Technology Data Exchange (ETDEWEB)

    Piuvezam Filho, Helio

    2007-07-01

    The present work was intended to study a coincidence system 4{pi}(PS){beta}-{gamma} for absolute activity measurement using plastic scintillators in 4{pi} geometry. Along with experiments on the coincidence system, simulations were also performed applying the Monte Carlo Method, by means of codes PENELOPE and ESQUEMA. These simulations were performed in order to calculate the extrapolation curve of the coincidence system 4{pi}(PS){beta}-{gamma} and compare it to experimental data. A new geometry was proposed to the coincidence system adding up a second photomultiplier tube to the previous system for improving light collection from the plastic scintillator, as this system presented limitations in the minimum detected energy due to the presence of electronic noise and low gain. The results show that an improvement in the signal-to-noise ratio was obtained, as well as in the minimum detected energy. Moreover, there was an increase in the detection efficiency. With these modifications, it is now possible to calibrate radionuclides which emit low energy electrons or X-rays, increasing the number of radionuclides that can be standardized with this type of system.(author)

  5. Analysis method for beta-gamma coincidence spectra from radio-xenon isotopes

    International Nuclear Information System (INIS)

    Radio-xenon isotopes monitoring is one important method for the verification of CTBT, what includes the measurement methods of HPGe γ spectrometer and β-γ coincidence. The article describes the analytic flowchart and method of three-dimensional beta-gamma coincidence spectra from β-γ systems, and analyses in detail the principles and methods of the regions of interest of coincidence spectra and subtracting the interference, finally gives the formula of radioactivity of Xenon isotopes and minimum detectable concentrations. Studying on the principles of three-dimensional beta-gamma coincidence spectra, which can supply the foundation for designing the software of β-γ coincidence systems. (authors)

  6. Standardization of 56Co had been carried out using 4 pi beta-gamma coincidence methods

    International Nuclear Information System (INIS)

    Standardization of exp.56 Co had been carried out using 4 pi beta-gamma coincidence methods. The radionuclide use for calibration of nuclear instruments on range of energy over 1500 keV. The exp.56 Co had been produced by irradiation of proton by using a cyclotron with 15 MeV of energy and 300 mb of cross-section to natural iron target (99,5% of purity) at the Institute for Nuclear Study, University of Tokyo. Source preparation had been done by gravimetry method after the irradiated source was dissolved in 8N HCI solution. The disintegration rate had been measured using 4 pi beta-gamma coincidence apparatus, where the gamm gets sets on 511 and 847 keV gamma-rays. The result measurement is fairly good with the specific activity is 3078 n 15 Bq/mg

  7. Calibration of low-level beta-gamma coincidence detector systems for xenon isotope detection.

    Science.gov (United States)

    Khrustalev, K; Wieslander, J S E; Auer, M; Gheddou, A

    2016-03-01

    The beta-gamma coincidence detector systems used for the measurement of the CTBT-relevant xenon isotopes (Xe-131m, Xe-133m, Xe-133 and Xe-135) in the International Monitoring System network and in the On-Site Inspection are reviewed. These detectors typically consist of a well-type or bore-through NaI crystal into which a measurement cell, serving also as a sample container, is inserted. This work describes the current calibration procedure for energy, resolution and efficiency, implementation challenges, availability and uncertainties of the specific nuclear decay data and the path forward to full calibration validation using GEANT4. PMID:26702548

  8. An Optimized Design of Single-Channel Beta-Gamma Coincidence Phoswich Detector by Geant4 Monte Carlo Simulations

    Directory of Open Access Journals (Sweden)

    Weihua Zhang

    2011-01-01

    Full Text Available An optimized single-channel phoswich well detector design has been proposed and assessed in order to improve beta-gamma coincidence measurement sensitivity of xenon radioisotopes. This newly designed phoswich well detector consists of a plastic beta counting cell (BC404 embedded in a CsI(Tl crystal coupled to a photomultiplier tube. The BC404 is configured in a cylindrical pipe shape to minimise light collection deterioration. The CsI(Tl crystal consists of a rectangular part and a semicylindrical scintillation part as a light reflector to increase light gathering. Compared with a PhosWatch detector, the final optimized detector geometry showed 15% improvement in the energy resolution of a 131mXe 129.4 keV conversion electron peak. The predicted beta-gamma coincidence efficiencies of xenon radioisotopes have also been improved accordingly.

  9. An Optimized Design of Single-Channel Beta-Gamma Coincidence Phoswich Detector by Geant4 Monte Carlo Simulations

    OpenAIRE

    Marc Bean; Jing Yi; Kurt Ungar; Weihua Zhang; Pawel Mekarski

    2011-01-01

    An optimized single-channel phoswich well detector design has been proposed and assessed in order to improve beta-gamma coincidence measurement sensitivity of xenon radioisotopes. This newly designed phoswich well detector consists of a plastic beta counting cell (BC404) embedded in a CsI(Tl) crystal coupled to a photomultiplier tube. The BC404 is configured in a cylindrical pipe shape to minimise light collection deterioration. The CsI(Tl) crystal consists of a rectangular part and a semicyl...

  10. Beta-gamma coincidence counting efficiency and energy resolution optimization by Geant4 Monte Carlo simulations for a phoswich well detector.

    Science.gov (United States)

    Zhang, Weihua; Mekarski, Pawel; Ungar, Kurt

    2010-12-01

    A single-channel phoswich well detector has been assessed and analysed in order to improve beta-gamma coincidence measurement sensitivity of (131m)Xe and (133m)Xe. This newly designed phoswich well detector consists of a plastic cell (BC-404) embedded in a CsI(Tl) crystal coupled to a photomultiplier tube (PMT). It can be used to distinguish 30.0-keV X-ray signals of (131m)Xe and (133m)Xe using their unique coincidence signatures between the conversion electrons (CEs) and the 30.0-keV X-rays. The optimum coincidence efficiency signal depends on the energy resolutions of the two CE peaks, which could be affected by relative positions of the plastic cell to the CsI(Tl) because the embedded plastic cell would interrupt scintillation light path from the CsI(Tl) crystal to the PMT. In this study, several relative positions between the embedded plastic cell and the CsI(Tl) crystal have been evaluated using Monte Carlo modeling for its effects on coincidence detection efficiency and X-ray and CE energy resolutions. The results indicate that the energy resolution and beta-gamma coincidence counting efficiency of X-ray and CE depend significantly on the plastic cell locations inside the CsI(Tl). The degraded X-ray and CE peak energy resolutions due to light collection efficiency deterioration by the embedded cell can be minimised. The optimum of CE and X-ray energy resolution, beta-gamma coincidence efficiency as well as the ease of manufacturing could be achieved by varying the embedded plastic cell positions inside the CsI(Tl) and consequently setting the most efficient geometry. PMID:20598559

  11. Beta-gamma coincidence counting efficiency and energy resolution optimization by Geant4 Monte Carlo simulations for a phoswich well detector

    International Nuclear Information System (INIS)

    A single-channel phoswich well detector has been assessed and analysed in order to improve beta-gamma coincidence measurement sensitivity of 131mXe and 133mXe. This newly designed phoswich well detector consists of a plastic cell (BC-404) embedded in a CsI(Tl) crystal coupled to a photomultiplier tube (PMT). It can be used to distinguish 30.0-keV X-ray signals of 131mXe and 133mXe using their unique coincidence signatures between the conversion electrons (CEs) and the 30.0-keV X-rays. The optimum coincidence efficiency signal depends on the energy resolutions of the two CE peaks, which could be affected by relative positions of the plastic cell to the CsI(Tl) because the embedded plastic cell would interrupt scintillation light path from the CsI(Tl) crystal to the PMT. In this study, several relative positions between the embedded plastic cell and the CsI(Tl) crystal have been evaluated using Monte Carlo modeling for its effects on coincidence detection efficiency and X-ray and CE energy resolutions. The results indicate that the energy resolution and beta-gamma coincidence counting efficiency of X-ray and CE depend significantly on the plastic cell locations inside the CsI(Tl). The degraded X-ray and CE peak energy resolutions due to light collection efficiency deterioration by the embedded cell can be minimised. The optimum of CE and X-ray energy resolution, beta-gamma coincidence efficiency as well as the ease of manufacturing could be achieved by varying the embedded plastic cell positions inside the CsI(Tl) and consequently setting the most efficient geometry.

  12. A new approach to beta-gamma coincidence counting. Advance report on the Samar electronic system

    International Nuclear Information System (INIS)

    In 4π β-γ coincidence measurements, precision on the evaluation of coincidence counting losses is made difficult because of complex overlapping effects between theβ--and γ-side dead times due to pre cursive counted events. In this context the SAMAR electronic system is aimed to give a precise way of automatic counting and reduce the need for calculated corrections. This report describes its configuration and basic features. The SAMAR has been conceived in such a manner that both beta and gamma chains are sharing a common and non extending dead-time which is simultaneously applied to both channels. The shared dead time is made to be the only one inserted throughout the chains. Overlapping effects vanish and the three counting channels have identical transmission ratios. A new dead-time circuit based on fast linear gates as blocking elements has been developed. Application of the two-oscillator Muller's method evidences a fully non-extending character. Automatism is implemented by using a live timer corrective channel controlling the counting scalers. (Author) 21 refs

  13. Primary 4{pi}{beta}-{gamma} coincidence system for standardization of radionuclides by means of plastic scintillators; Sistema primario por coincidencias 4{pi}{beta}-{gamma} para a padronizacao de radionuclideos empregando cintiladores plasticos

    Energy Technology Data Exchange (ETDEWEB)

    Baccarelli, Aida Maria

    2003-07-01

    The present work describes a 4{pi}({alpha},{beta})-{gamma} coincidence system for absolute measurement of radionuclide activity using a plastic scintillator in 4{pi} geometry for charged particles detection and a Nal (Tl) crystal for gamma-ray detection. Several shapes and dimensions of the plastic scintillator have been tried in order to obtain the best system configuration. Radionuclides which decay by alpha emission, {beta}{sup -}, {beta}{sup +} and electron capture have been standardized. The results showed excellent agreement with other conventional primary system which makes use of a 4{pi} proportional counter for X-ray and charged particle detection. The system developed in the present work have some advantages when compared with the conventional systems, namely; it does not need metal coating on the films used as radioactive source holders. When compared to liquid scintillators, is showed the advantage of not needing to be kept in dark for more than 24 h to allow phosphorescence decay of ambient light. Therefore it can be set to count immediately after the sources are placed inside of it. (author)

  14. A new approach to beta-gamma coincidence counting. Advance report on the Samar electronic system; Informe preliminar del sistema Samar sistema automatico de medidas absolutas de Radionucleidos

    Energy Technology Data Exchange (ETDEWEB)

    Carlos, J. E. de; Granados, C. E.

    1972-07-01

    In 4{pi} {beta}-{gamma} coincidence measurements, precision on the evaluation of coincidence counting losses is made difficult because of complex overlapping effects between the{beta}--and {gamma}-side dead times due to pre cursive counted events. In this context the SAMAR electronic system is aimed to give a precise way of automatic counting and reduce the need for calculated corrections. This report describes its configuration and basic features. The SAMAR has been conceived in such a manner that both beta and gamma chains are sharing a common and non extending dead-time which is simultaneously applied to both channels. The shared dead time is made to be the only one inserted throughout the chains. Overlapping effects vanish and the three counting channels have identical transmission ratios. A new dead-time circuit based on fast linear gates as blocking elements has been developed. Application of the two-oscillator Muller's method evidences a fully non-extending character. Automatism is implemented by using a live timer corrective channel controlling the counting scalers. (Author) 21 refs.

  15. Study and construction of a {beta}-spectrometer of uniform axial magnetic field fitted with a {beta}-{gamma} coincidence selector. Study of the {beta} spectra of {sup 32}P, {sup 203}Hg, {sup 198}Au. Measurement of the conversion coefficients of {sup 203}Ti and of {sup 198}Hg; Etude et realisation d'un spectrometre-{beta} a champ magnetique axial uniforme, muni d'un selecteur de coincidence {beta}-{gamma}. Etude des spectres {beta} du {sup 32}p, {sup 203}Hg, {sup 198}Au. Mesure des coefficients de conversion du {sup 203}Ti et du {sup 198}Hg

    Energy Technology Data Exchange (ETDEWEB)

    Parsignault, D. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-06-01

    In the first part is given the principle of the beta spectrometer with uniform axial field using systematically the idea of caustics. The apparatus is described and its properties compared to those deduced from trajectory calculations. The {beta}-ray and {gamma}-ray detectors and the device for selecting coincidences with a 2 {tau} resolution of 5 nanoseconds are also presented. In the second part, the spectrometer is used for studying reference elements and the most accurate results are confirmed. The {beta} spectrum of {sup 60}Co has a statistical form with an accuracy of 1 per cent; the maximum energy E{sub 0} is 316.5 {+-} 1.5 keV. That of the 7/2 + {yields} 11/2 transition for {sup 137}Cs has a unique form, once forbidden. E{sub 0}= 522 {+-} 3 keV. Conversion coefficients {alpha}{sub k} = 96 {+-} 1 X 10{sup -3} {alpha}L + M + N = 20.9 {+-} 0.5 X 10{sup -3}. The two {beta} spectra of {sup 59}Fe, separated by coincidence with the gamma, have the statistical form E{sub 0} = 462 {+-} 2 keV (55.1 + 0,3 per cent) and E{sub 1} = 275 {+-} 4 keV (44.9 {+-} 0.3 per cent). It is then verified whether the l selection rule is apparent in the shape of the phosphorus 32 beta spectrum. It is found in fact that it is not of statistical shape and its shape coefficient is determined. For a theoretical interpretation it is necessary to have better approximations than those generally used and this interpretation will not be unique. This work has also made it possible to show that the source contains a small proportion of {sup 33}P. The study of the {sup 203}Hg {beta} spectrum followed by the 279 keV gamma spectrum is designed to determine the conversion coefficients. The interior spectrum of gold 198 is not of statistical shape either. The form coefficient is determined together with the conversion coefficients which are in slight disagreement with those calculated by Rose or Sliv. An interpretation of the spectrum is put forward which proposes an imperfect compensation for the

  16. Application of Monte Carlo method in study of the padronization for radionuclides with complex disintegration scheme in 4{pi}{beta}-{gamma} coincidence System; Aplicacao do metodo de Monte Carlo no estudo da padronizacao de radionuclideos com esquema de desintegracao complexos em sistema de coincidencias 4{pi}{beta}-{gamma}

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Mauro Noriaki

    2006-07-01

    The present work described a new methodology for modelling the behaviour of the activity in a 4{pi}{beta}-{gamma} coincidence system. The detection efficiency for electrons in the proportional counter and gamma radiation in the NaI(Tl) detector was calculated using the Monte Carlo program MCNP4C. Another Monte Carlo code was developed which follows the path in the disintegration scheme from the initial state of the precursor radionuclide, until the ground state of the daughter nucleus. Every step of the disintegration scheme is sorted by random numbers taking into account the probabilities of all {beta}{sup -} branches, electronic capture branches, transitions probabilities and internal conversion coefficients. Once the final state was reached beta, electronic capture events and gamma transitions are accounted for the three spectra: beta, gamma and coincidence variation in the beta efficiency was performed simulating energy cut off or use of absorbers (Collodion). The selected radionuclides for simulation were: {sup 134}Cs, {sup 72}Ga which disintegrate by {beta}{sup -} transition, {sup 133}Ba which disintegrates by electronic capture and {sup 35}S which is a beta pure emitter. For the latter, the Efficiency Tracing technique was simulated. The extrapolation curves obtained by Monte Carlo were filled by the Least Square Method with the experimental points and the results were compared to the Linear Extrapolation method. (author)

  17. Instruments used to measure or check {alpha}, {beta}, {gamma} activity and neutron emission in the course of processing ore or irradiated fuel; Appareils de mesure ou de controle {alpha}, {beta}, {gamma}, n, des circuits des usines de traitement du minerai ou du combustible irradie

    Energy Technology Data Exchange (ETDEWEB)

    Blanc, A.; Brunet, M.; Kermagoret, M.; Labeyrie, J.; Roux, G.; Vasseur, J.; Weil, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1959-07-01

    One of the methods checking ores in the course of treatment is the rapid quantitative determination of thorium. This measurement is carried out by means of a scintillation instrument which shows the {beta} and {alpha} coincidences of ThC and ThC'. The treatment of irradiated fuel is accompanied by a large number of radioactive checks relative to the performance of the fixation and elution operations of uranium in the ion exchangers, to the concentration of radioactivity of effluent sent from the plant into watercourses. The operations of fixation and elution of the uranium are checked automatically by an instrument which takes a sample of 5 cm{sup 3} of solution, evaporates it and measures its activity every 10 or 20 minutes. Plutonium concentrations are measured: - in the presence of strong {beta} {gamma} activities, by means of rotating cylinder detectors; - in the presence of weak {beta} {gamma} activities, by means of {alpha} detectors scanning a constant level liquid surface; - by means of fission chambers relatively insensitive to {gamma}. Fission product concentrations are measured by chambers, counters or scintillators, according to the amount of {gamma} activity present. Finally, the activity of effluent to be emptied into watercourses is checked by means of a scintillation instrument, which measures the {alpha} activity on the one hand, and on the other hand the {beta} {gamma} activity of residue from a 100 cm{sup 3} sample taken and evaporated in 20 minutes. (author) [French] Parmi les controles relatifs au minerai en cours de traitement, figure le dosage rapide de thorium. Cette mesure est realisee au moyen d'un appareillage a scintillation qui met en evidence la coincidence des emissions {beta} et {alpha} du ThC et du ThC'. Le traitement des combustibles irradies s'accompagne d'un grand nombre de controles radioactifs portant sur le fonctionnement des operations de fixation et d'elution de l'uranium dans les

  18. Measurement of Time-Dependent CP Asymmetries and Constraints on sin(2beta+gamma) with Partial Reconstruction of B0 -> D*-+ pi+- Decays

    CERN Document Server

    Aubert, Bernard; Boutigny, D; Couderc, F; Gaillard, J M; Hicheur, A; Karyotakis, Yu; Lees, J P; Robbe, P; Tisserand, V; Zghiche, A; Palano, A; Pompili, A; Chen, J C; Qi, N D; Rong, G; Wang, P; Zhu, Y S; Eigen, G; Ofte, I; Stugu, B; Abrams, G S; Borgland, A W; Breon, A B; Brown, D N; Button-Shafer, J; Cahn, R N; Charles, E; Day, C T; Gill, M S; Gritsan, A V; Groysman, Y; Jacobsen, R G; Kadel, R W; Kadyk, J; Kerth, L T; Kolomensky, Yu G; Kukartsev, G; Le Clerc, C; Levi, M E; Lynch, G; Mir, L M; Oddone, P J; Orimoto, T J; Pripstein, M; Roe, N A; Romosan, A; Ronan, Michael T; Shelkov, V G; Telnov, A V; Wenzel, W A; Ford, K; Harrison, T J; Hawkes, C M; Knowles, D J; Morgan, S E; Penny, R C; Watson, A T; Watson, N K; Goetzen, K; Held, T; Koch, H; Lewandowski, B; Pelizaeus, M; Peters, K; Schmücker, H; Steinke, M; Boyd, J T; Chevalier, N; Cottingham, W N; Kelly, M P; Latham, T E; MacKay, C; Wilson, F F; Abe, K; Çuhadar-Dönszelmann, T; Hearty, C; Mattison, T S; McKenna, J A; Thiessen, D; Kyberd, P; McKemey, A K; Teodorescu, L; Blinov, V E; Bukin, A D; Golubev, V B; Ivanchenko, V N; Kravchenko, E A; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Yushkov, A N; Best, D; Bruinsma, M; Chao, M; Kirkby, D; Lankford, A J; Mandelkern, M A; Mommsen, R K; Röthel, W; Stoker, D P; Buchanan, C; Hartfiel, B L; Gary, J W; Layter, J; Shen, B C; Wang, K; Del Re, D; Hadavand, H K; Hill, E J; MacFarlane, D B; Paar, H P; Rahatlou, S; Sharma, V; Berryhill, J W; Campagnari, C; Dahmes, B; Levy, S L; Long, O; Lu, A; Mazur, M A; Richman, J D; Verkerke, W; Beck, T W; Beringer, J; Eisner, A M; Heusch, C A; Lockman, W S; Schalk, T; Schmitz, R E; Schumm, B A; Seiden, A; Spradlin, P; Turri, M; Walkowiak, W; Williams, D C; Wilson, M G; Albert, J; Chen, E; Dubois-Felsmann, G P; Dvoretskii, A; Erwin, R J; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Ryd, A; Samuel, A; Yang, S; Jayatilleke, S M; Mancinelli, G; Meadows, B T; Sokoloff, M D; Abe, T; Blanc, F; Bloom, P; Chen, S; Clark, P J; Ford, W T; Nauenberg, U; Olivas, A; Rankin, P; Roy, J; Smith, J G; Van Hoek, W C; Zhang, L; Harton, J L; Hu, T; Soffer, A; Toki, W H; Wilson, R J; Zhang, J; Altenburg, D; Brandt, T; Brose, J; Colberg, T; Dickopp, M; Dubitzky, R S; Hauke, A; Lacker, H M; Maly, E; Müller-Pfefferkorn, R; Nogowski, R; Otto, S; Schubert, J; Schubert, Klaus R; Schwierz, R; Spaan, B; Wilden, L; Bernard, D; Bonneaud, G R; Brochard, F; Cohen-Tanugi, J; Grenier, P; Thiebaux, C; Vasileiadis, G; Verderi, M; Khan, A; Lavin, D; Muheim, F; Playfer, S; Swain, J E; Andreotti, M; Azzolini, V; Bettoni, D; Bozzi, C; Calabrese, R; Cibinetto, G; Luppi, E; Negrini, M; Piemontese, L; Sarti, A; Treadwell, E; Baldini-Ferroli, R; Calcaterra, A; De Sangro, R; Falciai, D; Finocchiaro, G; Patteri, P; Piccolo, M; Zallo, A; Buzzo, A; Capra, R; Contri, R; Crosetti, G; Lo Vetere, M; Macri, M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Bailey, S; Morii, M; Won, E; Bhimji, W; Bowerman, D A; Dauncey, P D; Egede, U; Eschrich, I; Gaillard, J R; Morton, G W; Nash, J A; Taylor, G P; Grenier, G J; Lee, S J; Mallik, U; Cochran, J; Crawley, H B; Lamsa, J; Meyer, W T; Prell, S; Rosenberg, E I; Yi, J; Davier, M; Grosdidier, G; Höcker, A; Laplace, S; Le, F; Diberder; Lepeltier, V; Lutz, A M; Petersen, T C; Plaszczynski, S; Schune, M H; Tantot, L; Wormser, G; Brigljevic, V; Cheng, C H; Lange, D J; Simani, M C; Wright, D M; Bevan, A J; Coleman, J P; Fry, J R; Gabathuler, Erwin; Gamet, R; Kay, M; Parry, R J; Payne, D J; Sloane, R J; Touramanis, C; Back, J J; Harrison, P F; Shorthouse, H W; Vidal, P B; Brown, C L; Cowan, G; Flack, R L; Flächer, H U; George, S; Green, M G; Kurup, A; Marker, C E; McMahon, T R; Ricciardi, S; Salvatore, F; Vaitsas, G; Winter, M A; Brown, D; Davis, C L; Allison, J; Barlow, N R; Barlow, R J; Hart, P A; Hodgkinson, M C; Jackson, F; Lafferty, G D; Lyon, A J; Weatherall, J H; Williams, J C; Farbin, A; Jawahery, A; Kovalskyi, D; Lae, C K; Lillard, V; Roberts, D A; Blaylock, G; Dallapiccola, C; Flood, K T; Hertzbach, S S; Kofler, R; Koptchev, V B; Moore, T B; Saremi, S; Stängle, H; Willocq, S; Cowan, R; Sciolla, G; Taylor, F; Yamamoto, R K; Mangeol, D J J; Patel, P M; Robertson, S H; Lazzaro, A; Palombo, F; Bauer, J M; Cremaldi, L M; Eschenburg, V; Godang, R; Kroeger, R; Reidy, J; Sanders, D A; Summers, D J; Zhao, H W; Brunet, S; Cote-Ahern, D; Taras, P; Nicholson, H; Cartaro, C; Cavallo, N; De Nardo, Gallieno; Fabozzi, F; Gatto, C; Lista, L; Paolucci, P; Piccolo, D; Sciacca, C; Baak, M A; Raven, G; LoSecco, J M; Gabriel, T A; Brau, B; Gan, K K; Honscheid, K; Hufnagel, D; Kagan, H; Kass, R; Pulliam, T; Wong, Q K; Brau, J E; Frey, R; Igonkina, O; Potter, C T; Sinev, N B; Strom, D; Torrence, E; Colecchia, F; Dorigo, A; Galeazzi, F; Margoni, M; Morandin, M; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Tiozzo, G; Voci, C; Benayoun, M; Briand, H; Chauveau, J; David, P; La Vaissière, C de; Del Buono, L; Hamon, O; John, M J J; Leruste, P; Ocariz, J; Pivk, M; Roos, L; Stark, J; T'Jampens, S; Therin, G; Manfredi, P F; Re, V; Behera, P K; Gladney, L; Guo, Q H; Panetta, J; Anulli, F; Biasini, M; Peruzzi, I M; Pioppi, M; Angelini, C; Batignani, G; Bettarini, S; Bondioli, M; Bucci, F; Calderini, G; Carpinelli, M; Del Gamba, V; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G; Martínez-Vidal, F; Morganti, M; Neri, N; Paoloni, E; Rama, M; Rizzo, G; Sandrelli, F; Walsh, J; Haire, M; Judd, D; Paick, K; Wagoner, D E; Danielson, N; Elmer, P; Lü, C; Miftakov, V; Olsen, J; Smith, A J S; Tanaka, H A; Varnes, E W; Bellini, F; Cavoto, G; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Mazzoni, M A; Morganti, S; Pierini, M; Piredda, G; Safai-Tehrani, F; Voena, C; Christ, S; Wagner, G; Waldi, R; Adye, T; De Groot, N; Franek, B J; Geddes, N I; Gopal, G P; Olaiya, E O; Xella, S M; Aleksan, Roy; Emery, S; Gaidot, A; Ganzhur, S F; Giraud, P F; Hamel de Monchenault, G; Monchenault; Kozanecki, Witold; Langer, M; Legendre, M; London, G W; Mayer, B; Schott, G; Vasseur, G; Yéche, C; Zito, M; Purohit, M V; Weidemann, A W; Yumiceva, F X; Aston, D; Bartoldus, R; Berger, N; Boyarski, A M; Buchmüller, O L; Convery, M R; Cristinziani, M; Dong, D; Dorfan, J; Dujmic, D; Dunwoodie, W M; Elsen, E E; Field, R C; Glanzman, T; Gowdy, S J; Graugès-Pous, E; Hadig, T; Halyo, V; Hrynóva, T; Innes, W R; Jessop, C P; Kelsey, M H; Kim, P; Kocian, M L; Langenegger, U; Leith, D W G S; Libby, J; Luitz, S; Lüth, V; Lynch, H L; Marsiske, H; Messner, R; Müller, D R; O'Grady, C P; Ozcan, V E; Perazzo, A; Perl, M; Petrak, S; Ratcliff, B N; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Simi, G; Snyder, A; Soha, A; Stelzer, J; Su, D; Sullivan, M K; Vavra, J; Wagner, S R; Weaver, M; Weinstein, A J R; Wisniewski, W J; Wright, D H; Young, C C; Burchat, Patricia R; Edwards, A J; Meyer, T I; Petersen, B A; Roat, C; Ahmed, M; Ahmed, S; Alam, M S; Ernst, J A; Saeed, M A; Saleem, M; Wappler, F R; Bugg, W; Krishnamurthy, M; Spanier, S M; Eckmann, R; Kim, H; Ritchie, J L; Schwitters, R F; Izen, J M; Kitayama, I; Lou, X C; Ye, S; Bianchi, F; Bóna, M; Gallo, F; Gamba, D; Borean, C; Bosisio, L; Della Ricca, G; Dittongo, S; Grancagnolo, S; Lanceri, L; Poropat, P; Vitale, L; Vuagnin, G; Panvini, R S; Banerjee, Sw; Brown, C M; Fortin, D; Jackson, P D; Kowalewski, R V; Roney, J M; Band, H R; Dasu, S; Datta, M; Eichenbaum, A M; Johnson, J R; Kutter, P E; Li, H; Liu, R; Di Lodovico, F; Mihályi, A; Mohapatra, A K; Pan, Y; Prepost, R; Sekula, S J; Von Wimmersperg-Töller, J H; Wu, J; Wu Sau Lan; Yu, Z; Neal, H

    2003-01-01

    We present a measurement of time-dependent CP-violating asymmetries in decays of neutral B mesons to the final states D*-+ pi+-, using approximately 82 million B B bar events recorded by the BABAR experiment at the PEP-II e+ e- storage ring. Events containing these decays are selected with a partial reconstruction technique, in which only the high-momentum pi+- from the B decay and the low-momentum pi-+ from the D*-+ decay are used. We measure the amplitude of the asymmetry to be -0.063 +- 0.024(stat.) +- 0.014(syst.) and compute bounds on |sin(2beta + gamma)|.

  19. Digital Pulse Shape Analysis with Phoswich Detectors to Simplify Coincidence Measurements of Radioactive Xenon

    Energy Technology Data Exchange (ETDEWEB)

    Hennig, Wolfgang; Tan, Hui; Warburton, William K.; McIntyre, Justin I.

    2005-08-31

    The Comprehensive Nuclear-Test-Ban Treaty establishes a network of monitoring stations to detect radioactive Xenon in the atmosphere from nuclear weapons testing. One such monitoring system is the Automated Radio-xenon Sampler/Analyzer (ARSA) developed at Pacific Northwest National Laboratory, which uses a complex arrangement of separate beta and gamma detectors to detect beta-gamma coincidences from the Xe isotopes of interest. The coincidence measurement is very sensitive, but the large number of detectors and photomultiplier tubes require careful calibration which makes the system hard to use. It has been suggested that beta-gamma coincidences could be detected with only a single photomultiplier tube and electronics channel by using a phoswich detector consisting of optically coupled beta and gamma detectors (Ely, 2003). In that work, rise time analysis of signals from a phoswich detector was explored as a method to determine if interactions occurred in either the beta or the gamma detector or in both simultaneously. However, this approach was not able to detect coincidences with the required sensitivity or to measure the beta and gamma energies with sufficient precision for Xenon monitoring. In this paper, we present a new algorithm to detect coincidences by pulse shape analysis of the signals from a BC-404/CsI(Tl) phoswich detector. Implemented on fast digital readout electronics, the algorithm achieves clear separation of beta only, gamma only and coincidence events, accurate measurement of both beta and gamma energies, and has an error rate for detecting coincidences of less than 0.1%. Monte Carlo simulations of radiation transport and light collection were performed to optimize design parameters for a replacement detector module for the ARSA system, obtaining an estimated coincidence detection efficiency of 82-92% and a background rejection rate better than 99%. The new phoswich/pulse shape analysis method is thus suitable to simplify the existing ARSA

  20. Digital Pulse Shape Analysis with Phoswich Detectors to Simplify Coincidence Measurements of Radioactive Xenon

    International Nuclear Information System (INIS)

    The Comprehensive Nuclear-Test-Ban Treaty establishes a network of monitoring stations to detect radioactive Xenon in the atmosphere from nuclear weapons testing. One such monitoring system is the Automated Radio-xenon Sampler/Analyzer (ARSA) developed at Pacific Northwest National Laboratory, which uses a complex arrangement of separate beta and gamma detectors to detect beta-gamma coincidences from the Xe isotopes of interest. The coincidence measurement is very sensitive, but the large number of detectors and photomultiplier tubes require careful calibration which makes the system hard to use. It has been suggested that beta-gamma coincidences could be detected with only a single photomultiplier tube and electronics channel by using a phoswich detector consisting of optically coupled beta and gamma detectors (Ely, 2003). In that work, rise time analysis of signals from a phoswich detector was explored as a method to determine if interactions occurred in either the beta or the gamma detector or in both simultaneously. However, this approach was not able to detect coincidences with the required sensitivity or to measure the beta and gamma energies with sufficient precision for Xenon monitoring. In this paper, we present a new algorithm to detect coincidences by pulse shape analysis of the signals from a BC-404/CsI(Tl) phoswich detector. Implemented on fast digital readout electronics, the algorithm achieves clear separation of beta only, gamma only and coincidence events, accurate measurement of both beta and gamma energies, and has an error rate for detecting coincidences of less than 0.1%. Monte Carlo simulations of radiation transport and light collection were performed to optimize design parameters for a replacement detector module for the ARSA system, obtaining an estimated coincidence detection efficiency of 82-92% and a background rejection rate better than 99%. The new phoswich/pulse shape analysis method is thus suitable to simplify the existing ARSA

  1. Coincidence measurements of FFTF breeder fuel subassemblies

    International Nuclear Information System (INIS)

    A prototype coincidence counter developed to assay fast breeder reactor fuel was used to measure four fast-flux test facility subassemblies at the Hanford Engineering Development Laboratory in Richland, Washington. Plutonium contents in the four subassemblies ranged between 7.4 and 9.7 kg with corresponding 240Pu-effective contents between 0.9 and 1.2 kg. Large count rates were observed from the measurements, and plots of the data showed significant multiplication in the fuel. The measured data were corrected for deadtime and multiplication effects using established formulas. These corrections require accurate knowledge of the plutonium isotopics and 241Am content in the fuel. Multiplication-corrected coincidence count rates agreed with the expected count rates based on spontaneous fission-neutron emission rates. These measurements indicate that breeder fuel subassemblies with 240Pu-effective contents up to 1.2 kg can be nondestructively assayed using the shift-register electronics with the prototype counters. Measurements using the standard Los Alamos National Laboratory shift-register coincidence electronics unit can produce an assay value accurate to +-1% in 1000 s. The uncertainty results from counting statistics and deadtime-correction errors. 3 references, 8 figures, 8 tables

  2. Beta/gamma test problems for ITS

    International Nuclear Information System (INIS)

    The Integrated Tiger Series of Coupled Electron/Photon Monte Carlo Transport Codes (ITS 3.0, PC Version) was used at Oak Ridge National Laboratory (ORNL) to compare with and extend the experimental findings of the beta/gamma response of selected health physics instruments. In order to assure that ITS gives correct results, several beta/gamma problems have been tested. ITS was used to simulate these problems numerically, and results for each were compared to the problem's experimental or analytical results. ITS successfully predicted the experimental or analytical results of all tested problems within the statistical uncertainty inherent in the Monte Carlo method

  3. Mass measurement of depleted uranium components with coincidence neutron count

    International Nuclear Information System (INIS)

    The technique of the mass measurement of depleted uranium components was studied with active and passive coincidence neutron count. A well neutron coincidence counter was used to measure the coincidence neutron counts of the depleted uranium components with various mass. Am-Be source was selected as the external neutron source for induced fission in the active measurement, and a shield was optimized to reduce the accidental coincidence counts. In the active measurement, the maximum relative deviation of the linear fit mass from the nominal mass of the depleted uranium components is 11.71%, compared to 4.05% in the passive measurement. It is proved that because of the weakening of the shape influence, the passive method is more accurate and reliable to measure the mass of depleted uranium components than the active method. (authors)

  4. Data acquisition and processing system for coincidence measurements

    International Nuclear Information System (INIS)

    An instrument has been designed for the absolute measurement of radioactivity with 4πβ(PC)-γ coincidence. The instrument can be used as a standard device for the radioactivity measurement in metology laboratories. Also it can be used in the nuclear sciece and engineering research for absolute measurement of nuclear decay rate. The control of the system dead time and coincidence resolving time is digitized. The precision can reach ±2 ns. For data acquisition and communication the normalizing GPIB interface system technique is adopted. The measuring error caused by the instrument itself can be better than ±0.02%

  5. Data acquisition and processing system for coincidence measurements

    International Nuclear Information System (INIS)

    An instrument has been designed for the absolute measurement of radioactivity with 4πβ(PC)-γ coincidence. The instrument can be used as a standard device for the radioactivity measurement in metrology laboratories. Also it can be used in the nuclear science and engineering research for absolute measurement of nuclear decay rate. The control of the system dead time and coincidence resolving time is digitized. The precision can reach ±2 ns. For data acquisition and communication the normalizing GPIB interface system technique is adopted. The measuring error caused by this instrument itself can be better than ±0.02%

  6. An alpha–gamma coincidence spectrometer based on the photon–electron rejecting alpha liquid scintillation (PERALS®) system

    International Nuclear Information System (INIS)

    An alpha–gamma coincidence spectrometer has been developed for the measurement of selected actinide isotopes in the presence of high beta/gamma fields. The system is based on a PERALS® liquid scintillation counter for beta/alpha discrimination and was successfully tested with both high purity germanium and bismuth germanate, gamma-ray detectors using conventional analog electronics

  7. Beta-gamma discriminator circuit

    International Nuclear Information System (INIS)

    The major difficulty encountered in the determination of beta-ray dose in field conditions is generally the presence of a relatively high gamma-ray component. Conventional dosimetry instruments use a shield on the detector to estimate the gamma-ray component in comparison with the beta-ray component. More accurate dosimetry information can be obtained from the measured beta spectrum itself. At Los Alamos, a detector and discriminator circuit suitable for use in a portable spectrometer have been developed. This instrument will discriminate between gammas and betas in a mixed field. The portable package includes a 256-channel MCA which can be programmed to give a variety of outputs, including a spectral display, and may be programmed to read dose directly

  8. Chemical application of positron annihilation through triple coincidence measurement

    International Nuclear Information System (INIS)

    This report summarises the work on the application of triple coincidence measurement of annihilation radiation for providing chemical state information; the observations have been corroborated by angular correlation and Doppler broadening measurements and supplemented by the magnetic quenching in the angular correlation and peak-to-valley ratio in the Ge(Li) singles spectrum for the 511 keV line. (author)

  9. Application of coincidence techniques to fusion product measurements

    International Nuclear Information System (INIS)

    Measurement of two products of a fusion reaction in coincidence is proposed. Possible detector arrays and sample count rates have been evaluated for reactions in the TFR and TEXT tokamaks and in the TFTR neutral beamlines. The count rates indicate that this method is feasible on existing devices

  10. A training and educational tool for neutron coincidence measurements

    International Nuclear Information System (INIS)

    Neutron coincidence counting techniques are widely used for nuclear safeguards inspection. They are based on the detection of time correlated neutrons created from spontaneous or induced fission of plutonium and some other actinides. IAEA inspectors are trained to know and to use this technique, but it is not easy to illustrate and explain the basics of the neutron coincidence counting. The traditional shift registers or multiplicity counters give only multiplicity distributions and the singles, doubles and triples count rates. Using the list mode method for the recording and evaluation of neutron coincidence data makes it easier to teach this technique. List mode acquisition is a relatively new way to collect data in neutron coincidence counting. It is based on the recording of the follow-up times of neutron pulses originating from a neutron detector into a file. The recorded pulse train can be evaluated with special software after the measurement. Hardware and software for list mode neutron coincidence acquisition have been developed in the Institute of Isotopes and is called a Pulse Train Reader. A system called Virtual Source for replaying pulse trains registered with the list mode device has also been developed. The list mode device and the pulse train 're-player' together build a good educational tool for teaching the basics of neutron coincidence counting. Some features of the follow-up time, multiplicity and Rossi-alpha distributions can be well demonstrated by replaying artificially generated or pre-recorded pulse trains. The choice of real sources is stored on DVD. There is no need to transport and maintain real sources for the training. Virtual sources also give the possibility of investigating rare sources that trainees would not have access to otherwise. (authors)

  11. Determination of the time resolution for neutron scintillation detectors by multi-coincidence measurement

    Institute of Scientific and Technical Information of China (English)

    LI Yong-Ming; RUAN Xi-Chao; ZHOU Bin; MA Zhong-Yuan

    2011-01-01

    Based on the multi-coincidence measurement, the time resolution of three liquid scintillation detectors (BC501A) were determined strictly by solving the coincidence equations, where the influence from electronics estimated by self coincidence measurement

  12. Simultaneous beta/gamma digital spectroscopy

    Science.gov (United States)

    Farsoni, Abdollah T.

    A state-of-the-art radiation detection system for simultaneous spectroscopy of beta-particles and gamma-rays has been developed. The system utilizes a triple-layer phoswich detector and a customized Digital Pulse Processor (DPP) built in our laboratory. The DPP board was designed to digitally capture the analog signal pulses and, following several digital preprocessing steps, transfer valid pulses to the host computer for further digital processing. A MATLAB algorithm was developed to digitally discriminate beta and gamma events and reconstruct separate beta and gamma-ray energy spectra with minimum crosstalk. The spectrometer proved to be an effective tool for recording separate beta and gamma-ray spectra from mixed radiation fields. The system as a beta-gamma spectrometer will have broad-ranging applications in nuclear non-proliferation, radioactive waste management, worker safety, systems reliability, dose assessment, and risk analysis.

  13. Coincidence Detection Radiation System Based on Time to Amplitude Conversion for Determination of Thermal Neutron Flux on RSG-GAS Research Reactor Irradiation Facilities

    International Nuclear Information System (INIS)

    Thermal neutron flux determination research in RS1 irradiation facilities RSG-GAS was done. This research has arranged beta-gamma coincidence equipment system and parameter of measurement according to Au-198 beta-gamma spectrum. Gold foils that have exposed to flux neutron for period of time, counted, and the activities of radiation analyzed to get neutron flux. The results show that thermal neutron flux in RS1 is 2.019 x 1012 n/cm2s. To examine the system performance, the measurement of Co-60 known activity radioactive source was done and discrepancy is 4.3 %. (author)

  14. Standardization of (18)F using the 4pi(beta+gamma) integral counting technique.

    Science.gov (United States)

    Yamada, T; Kawada, Y; Sato, Y; Yunoki, A; Hino, Y

    2008-01-01

    Alpha 4pi(beta+gamma) integral counting technique using a 4pibeta-4pigamma detector configuration was adopted for the standardization of (18)F. In this technique, the beta-detector is composed of two thin plastic scintillators sandwiching the source, coupled with a slender photomultiplier tube. The beta-detector part with the source was inserted into a large well-type NaI(Tl) scintillation detector for gamma-ray detection, making a 4pibeta-4pigamma coincidence counting system. In this work, positron particles were detected with high efficiency in the beta-channel and annihilation quanta were also detected with high efficiency in the 4pigamma channel. The very small inefficiency of the 4pi(beta+gamma) integral counter for the beta-plus branch has been confirmed by EGS5 Monte Carlo simulation. The result using this technique agreed within the uncertainties with the result obtained by the conventional 4pibeta-gamma coincidence counting with the efficiency extrapolation technique using the same detector configuration and a conventional 4pibeta-gamma coincidence counter. PMID:18378155

  15. The spallation in reverse kinematics: what for a coincidence measurement?

    International Nuclear Information System (INIS)

    The Spaladin installation has been designed to study spallation reactions in reverse kinematics. Furthermore, the heavy and light fragments are detected by coincidence which allows us to get an instantaneous picture of the reaction at a level of accuracy better than that obtained through inclusive measurement. The first part is dedicated to the theoretical description of the different mechanisms involved in the spallation reactions. In the second part we describe the Spaladin installation and report some results on the reaction: Fe56 + p at an energy of 1 GeV/nucleon. In the third part we expose the performance of the installation through its simulation with the Geant-IV model. We present a study about the sensitivity of the Spaladin installation to theoretical predictions. The fourth part is dedicated to the future experiments that will be performed with the Spaladin installation. (A.C.)

  16. Application of whole-body personal TL dosemeters in mixed field beta-gamma radiation

    International Nuclear Information System (INIS)

    Application of whole-body personal TL dosemeters based on a high-sensitivity LiF:Mg,Cu,P (MCP-N) in mixed field beta-gamma radiation has been characterised. The measurements were carried out with 90Sr/90Y, 85Kr and 137Cs point sources to calculate the energy response and linearity of the TLD response in a dose range of 0.1-30 mSv. From the result, calibration curves were obtained, enabling the readout of individual dose equivalent Hp(10) from gamma radiation and Hp(0.07) from beta radiation in mixed field beta-gamma. Limitation of the methodology and its application are presented and discussed. (authors)

  17. Microstructures of duplex (beta + gamma) silver-tin alloys.

    Science.gov (United States)

    Abbott, J R; Miller, D R; Netherway, D J

    1985-05-01

    The microstructures of (beta + gamma) silver-tin alloys are especially influenced by both homogenization temperature and subsequent heat treatment. When the alloy is cooled from homogenization temperatures above approximately 200 degrees C, lenticular regions of the ordered orthorhombic gamma phase precipitate from within the disordered h.c.p. beta phase on three structurally equivalent planes, (1210), (1120), and (2110), to form a Widmanstatten structure. When the duplex alloys were homogenized at temperatures below approximately 200 degrees C, where the beta/(beta + gamma) phase boundary is vertical, these structures were not observed. PMID:3858310

  18. Effect of two dead times in series on coincidence measurements

    Energy Technology Data Exchange (ETDEWEB)

    Funck, E.

    1987-01-01

    Dead times in series occur in any counting device where detector signals are electronically amplified, selected for pulse height by a discriminator (or pulse-height analyzer) and fed through a dead-time unit producing a dead time, which has very often been designed to establish definite dead time losses. The problem of two dead times in series has been treated by J.W. Muller. No attempt, however, seems to have been made up to now to investigate this problem for the electronics of a coincidence system. In the paper presented here two dead times in series are considered that are found either in one or in both channels of a coincidence system. Correction formulas with experimental evidence are given which allow the deviations from results, which were calculated by taking only one dead time per channel into account, to be estimated.

  19. Method of γ-peak removal in coincidence measurement system for verification of nuclear arms control

    International Nuclear Information System (INIS)

    The paper analyzes the influence of γ-rays on coincidence measurement system performance according to the principle of coincidence measurement in verification technology of nuclear arms control, and proposes the refusing window method to remove γ-peak. Experiments show that this method can significantly reduce the γ-peak, and the removal rate of γ-rays reaches 99%. Thus the refusing window method improves the precision of coincidence measurement system. (authors)

  20. First principle active neutron coincidence counting measurements of uranium oxide

    International Nuclear Information System (INIS)

    Uranium is present in most nuclear fuel cycle facilities ranging from uranium mines, enrichment plants, fuel fabrication facilities, nuclear reactors, and reprocessing plants. The isotopic, chemical, and geometric composition of uranium can vary significantly between these facilities, depending on the application and type of facility. Examples of this variation are: enrichments varying from depleted (∼0.2 wt% 235U) to high enriched (>20 wt% 235U); compositions consisting of U3O8, UO2, UF6, metallic, and ceramic forms; geometries ranging from plates, cans, and rods; and masses which can range from a 500 kg fuel assembly down to a few grams fuel pellet. Since 235U is a fissile material, it is routinely safeguarded in these facilities. Current techniques for quantifying the 235U mass in a sample include neutron coincidence counting. One of the main disadvantages of this technique is that it requires a known standard of representative geometry and composition for calibration, which opens up a pathway for potential erroneous declarations by the State and reduces the effectiveness of safeguards. In order to address this weakness, the authors have developed a neutron coincidence counting technique which uses the first principle point-model developed by Boehnel instead of the “known standard” method. This technique was primarily tested through simulations of 1000 g U3O8 samples using the Monte Carlo N-Particle eXtended (MCNPX) code. The results of these simulations showed good agreement between the simulated and exact 235U sample masses

  1. First principle active neutron coincidence counting measurements of uranium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Goddard, Braden, E-mail: goddard.braden@gmail.com [Nuclear Security Science and Policy Institute, Texas A and M University, College Station, Texas 77843 (United States); Charlton, William [Nuclear Security Science and Policy Institute, Texas A and M University, College Station, Texas 77843 (United States); Peerani, Paolo [European Commission, EC-JRC-ITU, Ispra (Italy)

    2014-03-01

    Uranium is present in most nuclear fuel cycle facilities ranging from uranium mines, enrichment plants, fuel fabrication facilities, nuclear reactors, and reprocessing plants. The isotopic, chemical, and geometric composition of uranium can vary significantly between these facilities, depending on the application and type of facility. Examples of this variation are: enrichments varying from depleted (∼0.2 wt% {sup 235}U) to high enriched (>20 wt% {sup 235}U); compositions consisting of U{sub 3}O{sub 8}, UO{sub 2}, UF{sub 6}, metallic, and ceramic forms; geometries ranging from plates, cans, and rods; and masses which can range from a 500 kg fuel assembly down to a few grams fuel pellet. Since {sup 235}U is a fissile material, it is routinely safeguarded in these facilities. Current techniques for quantifying the {sup 235}U mass in a sample include neutron coincidence counting. One of the main disadvantages of this technique is that it requires a known standard of representative geometry and composition for calibration, which opens up a pathway for potential erroneous declarations by the State and reduces the effectiveness of safeguards. In order to address this weakness, the authors have developed a neutron coincidence counting technique which uses the first principle point-model developed by Boehnel instead of the “known standard” method. This technique was primarily tested through simulations of 1000 g U{sub 3}O{sub 8} samples using the Monte Carlo N-Particle eXtended (MCNPX) code. The results of these simulations showed good agreement between the simulated and exact {sup 235}U sample masses.

  2. Study on coincidence measurement for 56Fe(n, χnγ) reaction cross section

    International Nuclear Information System (INIS)

    When measuring (n, χnγ) partial γ-ray cross section of heavy fissionable nuclei, the technique of coincidence measurement was applied to depress Compton platform and background of energy spectrum. Five energy points of 56Fe(n, χnγ) cross sections were measured directly by two Clover detectors on 600 kV Cockcroff-Walton accelerator in CIAE, and then the offline data analysis at 1238.3 keV was performed by using the coincidence technique. The result is approximately the same as direct measurement result and the availability of the technique of coincidence measurement is proved. (authors)

  3. Calibration of nuclides by gamma-gamma sum peak coincidence counting

    International Nuclear Information System (INIS)

    The feasibility of extending sum peak coincidence counting to the direct calibration of gamma-ray emitters having particular decay schemes was investigated, also checkings of the measurement accuracy, by comparing with more precise beta-gamma coincidence counting have been performed. New theoretical studies and experiments were developed, demonstrating the reliability of the procedure. Uncertainties of less than one percent were obtained when certain radioactive sources were measured. The application of the procedure to 60Co, 22Na, 47Ca and 148Pm was studied. Theoretical bases of sum peak coincidence counting were set in order to extend it as an alternative method for absolute activity determination. In this respect, theoretical studies were performed for positive and negative beta decay, and electron capture, either accompanied or unaccompanied by coincident gamma rays. They include decay schemes containing up to three daughter nuclide excited levels, for different geometrical configurations. Equations are proposed for a possible generalization of the procedure. (M.E.L.)

  4. Improving Quality Of Spectrum Measurement By Event - Event Coincidence Technique

    International Nuclear Information System (INIS)

    To improve the quality of measurement data for the research levels density and gamma strength function in intermediate energy region below the neutron binding energy (Bn), a new method was developed at the Dalat Nuclear Research Institute. This method improve the ratio of the count of peak per compton background more times. This results are evaluated, compared with other methods. (author)

  5. MISR BRF measurements for various surface types: Intercomparison with coincident airborne and ground measurements.

    Science.gov (United States)

    Abdou, W. A.; Helmlinger, M.; Jovanovic, V. M.; Martonchik, J. V.; Diner, D. J.; Gatebe, C. K.; King, M. D.

    2005-05-01

    The BRF retrieved by the multiangle Imaging spectroRadimeter (MISR) are compared with those coincidently measured from aircraft, by the Cloud Absorption Radiometer (CAR) and MISR airborne simulator (AirMISR), and on the ground, by the Portable Apparatus for Rabid Acquisition of Bidirectional Observations of Land and Atmosphere (PARABOLA III). The intercomparisons are made for five types of surfaces: bright desert, salt pans, dark grassland, forests and dismal swamps. The results show that MISR BRF values are within +/- 10% in agreement with the corresponding airborne and ground measurements, independent of the surface type. This study is part of an effort to validate MISR surface products.

  6. Beta-gamma contaminated solid waste incinerator facility

    International Nuclear Information System (INIS)

    This technical data summary outlines a reference process to provide a 2-stage, 400 lb/hour incinerator to reduce the storage volume of combustible process waste contaminated with low-level beta-gamma emitters in response to DOE Manual 0511. This waste, amounting to more than 200,000 ft3 per year, is presently buried in trenches in the burial ground. The anticipated storage volume reduction from incineration will be a factor of 20. The incinerator will also dispose of 150,000 gallons of degraded solvent from the chemical separations areas and 5000 gallons per year of miscellaneous nonradioactive solvents which are presently being drummed for storage

  7. Evaluation of a fast neutron coincidence counter for the measurements of uranium samples

    International Nuclear Information System (INIS)

    A fast neutron coincidence counter using BC454/BGO phoswich detectors has been evaluated for the purpose of rapid verification measurements of uranium items. This counter uses custom electronics to identify and count coincidence neutrons in the presence of background radiation. Measurements of uranium standards were performed to evaluate the counter. This counter is successful in measuring uranium items but has a low efficiency that results in minimal improvement over current technology. An optimized counter can be built with better performance capabilities, but it is recommended that newer technologies be used instead

  8. Effects of beta/gamma radiation on nuclear waste glasses

    Energy Technology Data Exchange (ETDEWEB)

    Weber, W.J. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-07-01

    A key challenge in the disposal of high-level nuclear waste (HLW) in glass waste forms is the development of models of long-term performance based on sound scientific understanding of relevant phenomena. Beta decay of fission products is one source of radiation that can impact the performance of HLW glasses through the interactions of the emitted {beta}-particles and g-rays with the atoms in the glass by ionization processes. Fused silica, alkali silicate glasses, alkali borosilicate glasses, and nuclear waste glasses are all susceptible to radiation effects from ionization. In simple glasses, defects (e.g., non-bridging oxygen and interstitial molecular oxygen) are observed experimentally. In more complex glasses, including nuclear waste glasses, similar defects are expected, and changes in microstructure, such as the formation of bubbles, have been reported. The current state of knowledge regarding the effects of {beta}/{gamma} radiation on the properties and microstructure of nuclear waste glasses are reviewed. (author)

  9. Self-absorption correction for β-γ coincidence measurement of xenon samples

    International Nuclear Information System (INIS)

    In xenon activity measurements,the self-absorption diversity among different samples should be well corrected. In this regard, MCNP simulation was performed with a β-γ coincidence detector model. The detection efficiencies were obtained for xenon samples in different volumes, and self-absorption coefficients were calculated using the efficiencies. (authors)

  10. Electron-electron coincidence measurements on the Ar 1s → 4p resonance

    International Nuclear Information System (INIS)

    The authors have measured the Ar L2,3MM Auger lines in coincidence with the KL2,3L2,3 Auger line and the KL1L2,3 Auger line, respectively, using monochromatized synchrotron radiation at beam line X24A at NSLS. The photon energy was tuned to the Ar 1s → 4p resonance. The KLL Auger electrons were detected with an angle-resolving CMA. The subsequent decay of the holes in the L-shell can give rise to the ejection of additional Auger electrons (LMM) which were detected by a Time-of-Flight spectrometer. The authors' set-up allows them to record all LMM Auger lines at once in coincidence with one KLL Auger line selected in energy and angle. The resulting coincidence spectra will be presented and discussed

  11. Decontamination Experiments on Intact Pig Skin Contaminated with Beta-Gamma- Emitting Nuclides

    Energy Technology Data Exchange (ETDEWEB)

    Edvardsson, K.A.; Hagsgaard, S. [AB Atomenergi, Nykoeping (Sweden); Swensson, A. [Dept. of Occupational Medicine, Karolinska Sjukhuset, Stockholm (Sweden)

    1966-11-15

    A number of decontamination experiments have been performed on intact pig skin. In most of the experiments NaI-131 in water solution has been utilized because this nuclide is widely used within the Studsvik research establishment, is easy to detect and relatively harmless, and is practical to use in these experiments. Among the {beta} {gamma}-nuclides studied 1-131 has furthermore proved to be the one most difficult to remove from the skin. The following conclusions and recommendations regarding the decontamination of skin are therefore valid primarily for iodine in the form of Nal, but are probably also applicable to many other {beta} {gamma}-nuclides. a) A prolonged interval between contamination and decontamination has a negative effect on the result of the decontamination. Therefore start decontamination as soon as possible after the contamination. b) Soap and water has proved to be the most suitable decontamination agent. A number of other agents have appeared to be harmful to the skin. Therefore, first of all use only soap and water in connection with gentle rubbing. c) No clear connection between the temperature of the water for washing and the result of the decontamination has been demonstrated. d) Skin not degreased before the contamination seems to be somewhat easier to decontaminate than degreased skin, particularly if the activity has been on the skin for a long time. Therefore do not remove the sebum of the skin when engaged on radioactive work involving contamination risks. e) Irrigation of the contaminated surface with a solution containing the corresponding inactive ions or ordinary water in large quantities may considerably decrease the skin contamination. f) In radioactive work of long duration involving high risks of contamination prophylactic measures in the form of a protective substance ('invisible glove'), type Kerodex, may make decontamination easier.

  12. Systematic measurements of doppler-coincidence spectra for positron annihilation in pure metals and semiconductors

    International Nuclear Information System (INIS)

    Doppler-broadening measurements of the electron-positron annihilation line in twenty six elements are presented. The adopted coincidence technique allows to reduce the background and point out the contribution of positron annihilation with core electrons. The changes of high momentum contribution is presented for selected examples and a semiempirical analysis of the dependence on electronic structure is performed. Measured data are in good agreement with recent theoretical calculations and can be used to identification of impurities surrounding open volume defects. (author)

  13. Measurement of uranium mass and enrichment by time correlation coincidence method

    International Nuclear Information System (INIS)

    Background: Nuclear materials especially highly enriched uranium materials attract more and more attentions, and increasing methods and technical means are used to detect its information of mass and enrichment. Purpose: In order to solve the key technique problem of measuring the mass and enrichment of highly enriched uranium materials in the heavy shielded containers, a novel trial method was proposed in the paper: Methods: Time correlation coincidence method was implemented by using 14-MeV neutrons and continuous spectrum neutrons obtained by moderating 14-MeV neutrons to interrogate uranium materials inside of lead container with different mass and enrichment. Results: Within the certain range of low enrichment, the relation of different uranium samples mass of same enrichment was linear, and so was the relation of different uranium samples enrichment of same mass. Conclusion: Time correlation coincidence method might be an effective solution to measure the mass and enrichment of uranium materials in the heavy shielded container in the future. (authors)

  14. Beta-gamma system, pure spinors and Hilbert series of arc spaces

    OpenAIRE

    Bhamidipati, Chandrasekhar; Ray, Koushik

    2014-01-01

    Algorithms are presented for calculating the partition function of constrained beta-gamma systems in terms of the generating functions of the individual fields of the theory, the latter obtained as the Hilbert series of the arc space of the algebraic variety defined by the constraint. Examples of a beta-gamma system on a complex surface with an $A_1$ singularity and pure spinors are worked out and compared with existing results.

  15. The assay of encapsulated beta-gamma emitting waste: feasibility study

    International Nuclear Information System (INIS)

    This report contains a discussion of the techniques and instrumentation available for the determination of Beta-Gamma emitting radionuclides in encapsulated radioactive waste. Where applicable, consideration has been given to the practical difficulties associated with the assay of certain waste forms. The levels of detection have been estimated but further work is required in this and other areas. A suggestion is made for incorporating the beta-gamma assay in the same facility as an alpha assay. (author)

  16. Low-level multicounter {beta}/{gamma} systems with external guards in surface and shallow underground laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Theodorsson, P. [Iceland Univ. (Iceland). Science Inst.

    1997-03-01

    When weak samples are measured it is important that they can be given ample counting time in order to obtain satisfactory accuracy and that the background count rate can be checked well. This calls for a high counting capacity, which multidetectors can bring us. I will discuss development possibilities of low-level {beta}/{gamma} multidetector systems with an external anticosmic shield that will in many cases be operated in underground laboratories. These simple and low-cost system can frequently help us in increasing the number of detectors. Three concepts are combined in these systems: (1) multidetectors, (2) an external anticosmic (or guard) detector arrangement and (3) overburden shielding. (orig.)

  17. Measurement of decay time constant of a plastic scintillator by a delayed coincidence method

    International Nuclear Information System (INIS)

    This report presents a novel method of measuring the decay time constant by a simple delayed coincidence circuit using Field Programmable Gate Arrays (FPGA) based electronics. The basic principle of single photon method involves measuring of average real photoelectron pulse of scintillation without distorting the signal by signal shaping effects of PMT. In general terms, this method for determining the timing dependence of the scintillation intensity consists of measuring the distribution of the difference in time obtained between 'Formation' of scintillation light pulse by detecting scintillations in one PMT and the 'Arrival' of individual single photoelectron at the cathode of another PMT

  18. Utilization of coincidence criteria in absolute length measurements by optical interferometry in vacuum and air

    International Nuclear Information System (INIS)

    Traceability of length measurements to the international system of units (SI) can be realized by using optical interferometry making use of well-known frequencies of monochromatic light sources mentioned in the Mise en Pratique for the realization of the metre. At some national metrology institutes, such as Physikalisch-Technische Bundesanstalt (PTB) in Germany, the absolute length of prismatic bodies (e.g. gauge blocks) is realized by so-called gauge-block interference comparators. At PTB, a number of such imaging phase-stepping interference comparators exist, including specialized vacuum interference comparators, each equipped with three highly stabilized laser light sources. The length of a material measure is expressed as a multiple of each wavelength. The large number of integer interference orders can be extracted by the method of exact fractions in which the coincidence of the lengths resulting from the different wavelengths is utilized as a criterion. The unambiguous extraction of the integer interference orders is an essential prerequisite for correct length measurements. This paper critically discusses coincidence criteria and their validity for three modes of absolute length measurements: 1) measurements under vacuum in which the wavelengths can be identified with the vacuum wavelengths, 2) measurements under air in which the air refractive index is obtained from environmental parameters using an empirical equation, and 3) measurements under air in which the air refractive index is obtained interferometrically by utilizing a vacuum cell placed along the measurement pathway. For case 3), which corresponds to PTB’s Kösters-Comparator for long gauge blocks, the unambiguous determination of integer interference orders related to the air refractive index could be improved by about a factor of ten when an ‘overall dispersion value,’ suggested in this paper, is used as coincidence criterion. (paper)

  19. Stimulation of phospholipase A2 activity in bovine rod outer segments by the beta gamma subunits of transducin and its inhibition by the alpha subunit.

    OpenAIRE

    Jelsema, C L; Axelrod, J

    1987-01-01

    In the rod outer segments (ROS) of bovine retina, light activation of phospholipase A2 has been shown to occur by a transducin-dependent mechanism. In this report, the transducin-mediated stimulation of phospholipase A2 is shown to require dissociation of the alpha beta gamma heterotrimer. Addition of transducin to dark-adapted transducin-poor ROS stimulated phospholipase A2 activity only with coincident exposure to white light or, in the dark, with addition of the hydrolysis-resistant GTP an...

  20. Inclusive and coincidence measurements of light particles and fragments from intermediate energy heavy ion collisions

    International Nuclear Information System (INIS)

    Intermediate energy heavy ion collisions have been studied. Presented data on light particles (Ζ=1.2) emitted in 12C +C, Al, Cu, Au reactions at 35A and 85A MeV incident projectile energy are generally well described within the participant-spectator picture. When coincident light particles are measured, an excess of particles detected with (Δφ = 180 degrees) is found. The strength of this excess increases with the mass of the coincident particles and decreases with the mass of the target. These observation seem to be consistent with particle emission from a participant region where momentum conservation within this region causes the observed behaviour. Azimuthal angular distributions of projectile-like fragments detected in coincidence with light particles are consistent with a transverse momentum balance between the fragment and a participant source. Low-energy (1A-6A MeV) medium-heavy (Ζ=3-12) fragment emitted in 94A MeV 16O+ Al collisions have been measured using ΔΕ-Ε telescopes consisting of silicon detectors implanted with boron. The momentum distributions of these fragments indicate the existence of two emission components. In addition to a component, which is isotropic in a system shifted by parallel- and transverse momenta ∼ 15A MeV/c, another component with larger momentum shifts is needed to describe the results. (author)

  1. Primary activity measurements with a 4πβ-4πγ coincidence counting system.

    Science.gov (United States)

    Nedjadi, Youcef; Bailat, Claude J; Bochud, François O

    2012-01-01

    The radioactive concentrations of (166m)Ho, (134)Cs and (133)Ba solutions have been standardised using a 4πβ-4πγ coincidence counting system we have recently set up. The detection in the beta channel is performed using various geometries of a UPS-89 plastic scintillator optically coupled to a selected low-noise 1in. diameter photomultiplier tube. The light-tight thin capsule that encloses this beta detector is housed within the well of a 5in.×5in. NaI(Tl) monocrystal detector. The beta detection efficiency can be varied either by optical filtering or electronic discrimination when the electrons loose all their energy in the plastic scintillator. This 4πβ-4πγ coincidence system improves on our 4πβ(PC)-γ system in that its sample preparation is less labour intensive, it yields larger beta- and gamma-counting efficiencies thus enabling the standardisation of low activity sources with good statistics in reasonable time, and it makes standardising short-lived radionuclides easier. The resulting radioactive concentrations of (166m)Ho, (134)Cs and (133)Ba are found to agree with those measured with other primary measurement methods thus validating our 4πβ-4πγ coincidence counting system. PMID:21840220

  2. Coincidence system for the absolute measurement of radionuclides activity using a liquid scintillator

    International Nuclear Information System (INIS)

    A system for the standartization of radioisotopes activity using liquid scintillator detector was developed. The system was set up at Nuclear Metrology Laboratory - L.M.N. (Nuclear Physics Division - IEA). The system performance was checked by absolute activity measurements for two radioisotopes, 60Co and 241Am. The activities were determined by the 4π(α, β-γ) coincidence method. An accuracy of the order of 99,8% was obtained. The results for 60Co were compared with those obtained by 4πβ-γ coincidence method using a proportional counter at L.M.N., while the results for 241Am were compared with those obtained through the linear extrapolation method using the same liquid scintillator. Compared to other systems, the advantages of this one are the simplicity and the short time spent in the sample preparation, and the negligible self-absorption. (Author)

  3. Analysis of time correlation measurements with the Active Well Coincidence Counter

    International Nuclear Information System (INIS)

    Active well coincidence counters are widely used for nondestructive assay applications in nuclear safeguards and nuclear waste characterization. The method is based on the detection of correlated neutrons from fission by He-3 detectors embedded in a polyethylene moderator. In the assay of uranium, an active measurement must be performed to induce fission in the material, and typically Am/Li neutron sources are used as the active source. Monte Carlo studies of the measurement setup are useful in the design, optimization, and analysis of the entire measurement system. The simulation must take into account many factors, for example the Am/Li neutron spectrum, the multiplicity of neutron emission in induced fission events, and the detection of thermalized neutrons by the He-3 counters. In this study, we address these issues and present a detailed analysis of the measurement system that includes parameters such as the length of fission chains generated in the fissile material by the source neutrons, the time of neutron detection in the He-3 counters, and the generation number of the detected neutrons. The simulations are performed with the MCNP-PoliMi code. The simulation results are compared with measurements performed on uranium oxide standards with an active well coincidence counter that is in use at the Y-12 National Security Complex. The geometry of the MCNP-PoliMi simulation for the active well coincidence counter is shown. In addition to the simulation of traditional multiplicity parameters given by the shift register (singles, doubles and triples), MCNP-PoliMi allows the user to simulate the entire distribution of time correlations between detectors and detector autocorrelations. We show that this approach, also known as time interval analysis and first proposed by Bruggeman and colleagues in 1996, has the potential to lead to a more robust and complete analysis compared to the measurement of multiplicity alone. The results of this study serve as a preliminary

  4. Efficiency corrections for the γ-γ coincidence counting rates measured by the multi-detector correlation system

    International Nuclear Information System (INIS)

    A new method of determination of the efficiency corrections for the γ-γ coincidence rates measured by the multi-detector system is described. The method uses the random coincidence counting rates and is based on two assumptions: a) the counting rates of both true and random coincidences for a given pair of γ-quanta are proportional to the efficiencies of the registration of γ-quanta in the detectors; b) there is no correlation between the gammas which coincide at random. Results of the test of the method applied to the multi-detector correlation system are presented. (orig.)

  5. Promoter opening (melting) and transcription initiation by RNA polymerase I requires neither nucleotide beta,gamma hydrolysis nor protein phosphorylation.

    OpenAIRE

    Lofquist, A K; Li, H; Imboden, M A; Paule, M. R.

    1993-01-01

    With some bacterial RNA polymerases and in eukaryotic RNA polymerase II, DNA melting during initiation requires the coupling of energy derived from beta,gamma hydrolysis of ATP. A detailed analysis of this possible requirement for eukaryotic RNA polymerase I reveals no such requirement. However, in some cases, beta,gamma non-hydrolyzable derivatives (beta,gamma imido or methylene) of nucleotide substrates have been found to significantly inhibit transcription initiation because of their ineff...

  6. The underwater coincidence counter for plutonium measurements in mixed-oxide fuel assemblies manual

    Energy Technology Data Exchange (ETDEWEB)

    G. W. Eccleston; H. O. Menlove; M. Abhold; M. Baker; J. Pecos

    1999-05-01

    This manual describes the Underwater Coincidence Counter (UWCC) that has been designed for the measurement of plutonium in mixed-oxide (MOX) fuel assemblies prior to irradiation. The UWCC uses high-efficiency {sup 3}He neutron detectors to measure the spontaneous-fission and induced-fission rates in the fuel assembly. Measurements can be made on MOX fuel assemblies in air or underwater. The neutron counting rate is analyzed for singles, doubles, and triples time correlations to determine the {sup 240}Pu effective mass per unit length of the fuel assembly. The system can verify the plutonium loading per unit length to a precision of less than 1% in a measurement time of 2 to 3 minutes. System design, components, performance tests, and operational characteristics are described in this manual.

  7. Multi-coincidence measurements in gas-phase amino acid alanine after valence level ionization

    International Nuclear Information System (INIS)

    Full text: The first chiral amino acids having distinct enantiomeric structures is the alanine. Therefore the study of such molecules is important for developing our understanding of this class of molecule. In this work, we report coincidence measurements between photoelectron and photoion, and total ion yield (TIY) measurements after valence level ionization of D,L-alanine in gas phase. The experiments were performed at the Brazilian Synchrotron Light Source (LNLS) at the Toroidal Grating Monochromator beamline (D0-5A TGM) in the 12-35 eV energy range. The end-station of the beamline is composed by a time-of-flight (TOF) spectrometer specially build for the photoelectron-photoion-photoion (PEPIPICO) measurements. The TIY have been compared with valence photoelectron spectra recorded with synchrotron radiation reported in the literature and have been discussed in a comparative form. The results will be presented during the conference

  8. High mass-resolution electron-ion-ion coincidence measurements on core-excited organic molecules

    CERN Document Server

    Tokushima, T; Senba, Y; Yoshida, H; Hiraya, A

    2001-01-01

    Total electron-ion-ion coincidence measurements on core excited organic molecules have been carried out with high mass resolution by using multimode (reflectron/linear) time-of-flight mass analyzer. From the ion correlation spectra of core excited CH sub 3 OH and CD sub 3 OH, the reaction pathway to form H sub 3 sup + (D sub 3 sup +) is identified as the elimination of three H (D) atoms from the methyl group, not as the inter-group (-CH sub 3 and -OH) interactions. In a PEPIPICO spectrum of acetylacetone (CH sub 3 COCH sub 2 COCH sub 3) measured by using a reflectron TOF, correlations between ions up to mass number 70 with one-mass resolution was recorded.

  9. Gram-scale Plutonium Samples Measured by Experimental Device of Four Detectors Well-type Fast Neutron Coincidence Measurement

    Institute of Scientific and Technical Information of China (English)

    LIU; Guo-rong; LIANG; Qing-lei; LI; Jing-huai; LI; An-li

    2013-01-01

    Experimental device of four detectors well-type fast neutron coincidence measurement(see Fig.1)consists of four?127 mm×50.8 mm BC501A liquid scintillation detectors,DC271A digitizer and other circuits.Application program simultaneously acquires the waveform of each pulse output from each detector,and identifies each pulse from neutron or?particle by offline model,and gets their arrival timing.

  10. Radioelements: their detection and measurement; Les radioelements: detection et mesure

    Energy Technology Data Exchange (ETDEWEB)

    Grinberg, B. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    A brief review of the properties of nuclear radiations is followed by a description of the basic techniques used for their detection: autoradiography, methods using the ionisation of gases (ionisation chambers, proportional counters, Geiger-Muller counters), scintillation techniques. The principles of the different methods of measurement are explained, whether they concern the activity or the energy absorbed (dosimetry). This is followed by a description of the basic techniques (4 {pi} counter, defined solid angle, {beta}-{gamma} coincidences). (author) [French] Apres un bref rappel des proprietes des rayonnements nucleaires, on decrit les techniques fondamentales employees pour leur detection: autoradiographie, procedes utilisant l'ionisation des gaz (chambres d'ionisation, compteurs proportionnels, compteurs de Geiger-Muller), technique des scintillations. On expose le principe des differentes methodes de mesure concernant soit l'activite, soit l'energie absorbee (dosimetrie). Les techniques fondamentales (compteur 4 {pi}, angle solide defini, coincidences {beta}-{gamma}) sont ensuite decrites. (auteur)

  11. Design of an electronic system with simultaneous registering of pulse amplitude and event time applied to the 4πβ-γ coincidence method

    International Nuclear Information System (INIS)

    The 4πβ-γ coincidence method for absolute radionuclide activity measurement has been considered for many years as a primary standard in Nuclear Metrology, because of dependence on few observable quantities and high accuracy. The Laboratorio de Metrologia Nuclear (LMN) - Nuclear Metrology Laboratory -, at Instituto de Pesquisas Energeticas e Nucleares (IPEN) - Nuclear and Energy Research Institute -, among its measurement techniques, uses the 4πβ-γ coincidence method. Recently a new technique known as 'software coincidence' has been used, with many advantages over the conventional coincidence methodology. In order to update the methodologies for radionuclide standardizations, the LMN developed a new system based on the software coincidence technique, described in the present work. This system uses the same nuclear set up for beta and gamma detection. The new software coincidence electronics uses a National Instruments (NI) acquisition card connected to a microcomputer and, through a connection panel, to the nuclear detection set up. The card configuration and controlling is accomplished by software using the LabVIEW, a NI proprietary product. This system records into disk files all the amplitudes and occurrence times for beta and gamma detected pulses. A suitable software was developed (the coincidence analysis program) to process the recorded data in order to obtain beta, gamma and coincidence counts and perform calculation of the radioactive source activity. The work also presents and discusses the results obtained with the first version of the coincidence analysis program, as well as perspectives for future works. (author)

  12. Using gamma-gamma coincidence measurements to validate Monte Carlo generated detector response functions

    International Nuclear Information System (INIS)

    Monte Carlo simulation of gamma-ray transport for the purpose of performing elemental analysis of bulk samples requires the tracking of gamma rays in the sample and also in the detector(s) used. Detector response functions (DRF's) are an efficient and accurate variance reduction technique that greatly decreases the simulation time by substituting the tracking of gamma rays inside the detector by predefined single energy gamma-ray spectra. These spectra correspond to the average response of the detector for incident gamma rays. DRF's are generated by Monte Carlo methods and are benchmarked with experimental data. In this work, prompt gamma-gamma coincidence measurements are presented as a way to validate DRF's for high-energy gamma rays

  13. Upgrading DRACULA setup to be used for light products - fission fragments coincidence measurements

    International Nuclear Information System (INIS)

    At low bombarding energy (E/A 238 U give rise to a number of fission processes, all leading to very similar fission products. Therefore, in order to understand the fission processes in this energy domain it is of interest to determine the amount of fission occurring after a peripheral interaction relative to that originating from compound nucleus formation. Although the detection of a projectile residue (PLF) in coincidence with the fission fragments is a very promising probe for the macroscopic features of the mechanism of induced fission, at incident energies in the vicinity of the Coulomb barrier (E/A 2 cross section area uses the phoswich technique by coupling a thin fast NE102A plastic scintillator to a 10 cm long BaF2 crystal of hexagonal section. The BaF2 crystal detectors have been successfully used in modular multielement detector ARGOS in the context of GANCT and HOTCT researches at LNS. The light response of the phoswich configuration as a function of the plastic thickness and of the energy and charge of the incident ion has been studied at Tandem energies. Both arrays will be placed in separate vacuum chambers attached to the remaining large angular opening windows of the reaction chamber. By rotating the whole device the fission fragment detection arrays will cover a range of 96 angle in the horizontal plane. The main advantage of this setup is that it allows to perform continuous measurements in energy and angle of the reaction products. The geometry of the whole device has been tested by Monte Carlo calculations using the code ELPHIC. The coincidence condition is completely fulfilled for the first two positions of the setup and partially for the third one. Measurements are intended to be performed at the SMP Tandem from LNS-Catania using light beams (16 O, 19 F, 20 Ne, 32 S) at ∼ 6 MeV/A on high fissility parameter targets. (authors)

  14. The spallation in reverse kinematics: what for a coincidence measurement?; La spallation en cinematique inverse: pourquoi faire une mesure en coincidence?

    Energy Technology Data Exchange (ETDEWEB)

    Ducret, J.E

    2006-07-15

    The Spaladin installation has been designed to study spallation reactions in reverse kinematics. Furthermore, the heavy and light fragments are detected by coincidence which allows us to get an instantaneous picture of the reaction at a level of accuracy better than that obtained through inclusive measurement. The first part is dedicated to the theoretical description of the different mechanisms involved in the spallation reactions. In the second part we describe the Spaladin installation and report some results on the reaction: Fe{sup 56} + p at an energy of 1 GeV/nucleon. In the third part we expose the performance of the installation through its simulation with the Geant-IV model. We present a study about the sensitivity of the Spaladin installation to theoretical predictions. The fourth part is dedicated to the future experiments that will be performed with the Spaladin installation. (A.C.)

  15. Weighted $\\beta\\gamma$-summability of fuzzy functions of order $\\theta$

    OpenAIRE

    Ojha, Sarita; Srivastava, P. D.

    2016-01-01

    The concept of weighted $\\beta\\gamma$ - summability of order $\\theta$ in case of fuzzy functions is introduced and classified into ordinary and absolute sense. Several inclusion relations among the sets are investigated. Also we have found some suitable conditions to get its relation with the generalized statistical convergence. Finally we have proved a generalized version of Tauberian theorem.

  16. 75 FR 4877 - In the Matter of Beta Gamma Nuclear Radiology; Confirmatory Order Modifying License (Effective...

    Science.gov (United States)

    2010-01-29

    ... rule (72 FR 49139, August 28, 2007). The E-Filing process requires participants to submit and serve all... Gamma Nuclear Radiology; Confirmatory Order Modifying License (Effective Immediately) I Beta Gamma Nuclear Radiology (BGNR) (Licensee) is the holder of medical License No. 52-25542-01, issued by the...

  17. Generalized Bessel transform of $(\\beta, \\gamma)$-generalized Bessel Lipschitz functions

    OpenAIRE

    DAHER, Radouan; El Hamma, Mohamed

    2015-01-01

    In this paper, we prove an analog of Younis’s theorem 5.2 in~[4] for the generalized Fourier-Bessel transform on the Half line for functions satisfying the $(\\beta, \\gamma)$-generalized Bessel Lipschitz condition in the space $\\mathrm{L}^{2}_{\\alpha,n}$.

  18. First satellite measurements of chemical changes in coincidence with sprite activity

    Science.gov (United States)

    Arnone, Enrico; São Sabbas, Fernanda; Kero, Antti; Soula, Serge; Carlotti, Massimo; Chanrion, Olivier; Dinelli, Bianca Maria; Papandrea, Enzo; Castelli, Elisa; Neubert, Torsten

    2010-05-01

    The last twenty years have seen the discovery of electric discharges in the Earth's atmosphere above thunderstorms, the so-called sprites and jets. It has been suggested that they impact the atmospheric chemistry and possibly affect the ozone layer through their repeated occurrence. Whereas theoretical studies and laboratory experiments suggest enhancement of such gasses as nitrogen oxides by up to hundreds of percent within sprites, a definitive detection of their chemical effects have to date been unsuccessful. In this paper, we report on the first measurements of atmospheric chemical perturbations recorded in coincidence with sprite activity. A striking event occurred on 25 August 2003 when the MIPAS spectrometer onboard the Envisat satellite recorded spectroscopic measurements soon after a sequence of 11 sprites observed above Corsica (France) by Eurosprite ground facilities (details of the convective system are discussed in a companion paper by São Sabbas et al.). The measurements show an enhancement of ambient nitrous oxide by 80% at 52 km altitude in the region above the parent thunderstorm. The recorded chemical changes imply sprites can exert significant modification of the atmospheric chemistry at a regional scale, confirming model and laboratory predictions of sprite-chemistry, and requiring a new estimate of their global impact. The results of the analysis and their implications are discussed.

  19. Measurement of U-235 Fission Neutron Spectra Using a Multiple Gamma Coincidence Technique

    Science.gov (United States)

    Ji, Chuncheng; Kegel, G. H. R.; Egan, J. J.; DeSimone, D. J.; Alimeti, A.; Roldan, C. F.; McKittrick, T. M.; Kim, D.-S.; Chen, X.; Tremblay, S. E.

    2005-05-01

    The Los Alamos Model of Madland and Nix predicts the shape of the fission neutron energy spectrum for incident primary neutrons of different energies. Verifications of the model normally are limited to measurements of the fission neutron spectra for energies higher than that of the primary neutrons because the low-energy spectrum is distorted by the admixture of elastically and inelastically scattered neutrons. This situation can be remedied by using a measuring technique that separates fission from scattering events. One solution consists of using a fissile sample so thin that fission fragments can be observed indicating the occurrence of a fission event. A different approach is considered in this paper. It has been established that a fission event is accompanied by the emission of between seven and eight gamma rays, while in a scattering interaction, between zero and two gammas are emitted, so that a gamma multiplicity detector should supply a datum to distinguish a fission event from a scattering event. We proceed as follows: A subnanosecond pulsed and bunched proton beam from the UML Van de Graaff generates nearly mono-energetic neutrons by irradiating a thin metallic lithium target. The neutrons irradiate a 235U sample. Emerging neutron energies are measured with a time-of-flight spectrometer. A set of four BaF2 detectors is located close to the 235U sample. These detectors together with their electronic components identify five different events for each neutron detected, i.e., whether four, three, two, one, or none of the BaF2 detectors received one (or more) gamma rays. We present work, preliminary to the final measurements, involving feasibility considerations based on gamma-ray coincidence measurements with four BaF2 detectors, and the design of a Fission-Scattering Discriminator under construction.

  20. A new method to reduce the statistical and systematic uncertainty of chance coincidence backgrounds measured with waveform digitizers

    Science.gov (United States)

    O`Donnell, J. M.

    2016-01-01

    A new method for measuring chance-coincidence backgrounds during the collection of coincidence data is presented. The method relies on acquiring data with near-zero dead time, which is now realistic due to the increasing deployment of flash electronic-digitizer (waveform digitizer) techniques. An experiment designed to use this new method is capable of acquiring more coincidence data, and a much reduced statistical fluctuation of the measured background. A statistical analysis is presented, and used to derive a figure of merit for the new method. Factors of four improvement over other analyzes are realistic. The technique is illustrated with preliminary data taken as part of a program to make new measurements of the prompt fission neutron spectra at Los Alamos Neutron Science Center. It is expected that the these measurements will occur in a regime where the maximum figure of merit will be exploited.

  1. Measurement of compensation factors for coincidence in detection of Co-60 in solid source

    International Nuclear Information System (INIS)

    For some isotopes with cascade gamma-ray emission, for instance, Co-60 with two gamma rays of 1173.2 keV and 1332.5 keV, coincidence in detection would occur, which would reduce the count rate in full-energy-peak. And for some multi-ray isotopes, count rate in some full-energy-peak may increase, while some others decreasing. Usually the effect of coincidence can be neglected if the standard source or sample is far enough away from the detector, say, 25 cm in some common situations. But in the paper, in order to obtain enough precision in a limited period of time, the low-activity environmental sample was placed about 1 cm away from the detector, which would cause a considerable effect of coincidence. To reduce this deviation induced by coincidence, it is necessary to do some compensation in the process of detection. (authors)

  2. Low level radioactivity measurements with phoswich detectors using coincident techniques and digital pulse processing analysis

    International Nuclear Information System (INIS)

    A new system has been developed for the detection of low radioactivity levels of fission products and actinides using coincidence techniques. The device combines a phoswich detector for α/β/γ-ray recognition with a fast digital card for electronic pulse analysis. The phoswich can be used in a coincident mode by identifying the composed signal produced by the simultaneous detection of α/β particles and X-rays/γ particles. The technique of coincidences with phoswich detectors was proposed recently to verify the Nuclear Test Ban Treaty (NTBT) which established the necessity of monitoring low levels of gaseous fission products produced by underground nuclear explosions. With the device proposed here it is possible to identify the coincidence events and determine the energy and type of coincident particles. The sensitivity of the system has been improved by employing liquid scintillators and a high resolution low energy germanium detector. In this case it is possible to identify simultaneously by α/γ coincidence transuranic nuclides present in environmental samples without necessity of performing radiochemical separation. The minimum detectable activity was estimated to be 0.01 Bq kg-1 for 0.1 kg of soil and 1000 min counting

  3. Development of a three-layer phoswich alpha-beta-gamma imaging detector

    Science.gov (United States)

    Yamamoto, Seiichi; Ishibashi, Hiroyuki

    2015-06-01

    For radiation monitoring at the sites of such nuclear power plant accidents as Fukushima Daiichi, radiation detectors are needed not only for gamma photons but also for alpha and beta particles because some nuclear fission products emit beta particles and gamma photons and some nuclear fuels contain plutonium that emits alpha particles. In some applications, imaging detectors are required to detect the distribution of plutonium particles that emit alpha particles and radiocesium in foods that emits beta particles and gamma photons. To solve these requirements, we developed an imaging detector that can measure the distribution of alpha and beta particles as well as gamma photons. The imaging detector consists of three-layer scintillators optically coupled to each other and to a position sensitive photomultiplier tube (PSPMT). The first layer, which is made of a thin plastic scintillator (decay time: ~5 ns), detects alpha particles. The second layer, which is made of a thin Gd2SiO5 (GSO) scintillator with 1.5 mol% Ce (decay time: 35 ns), detects beta particles. The third layer made of a thin GSO scintillator with 0.4 mol% Ce (decay time: 70 ns) detects gamma photons. Using pulse shape discrimination, the images of these layers can be separated. The position information is calculated by the Anger principle from 8×8 anode signals from the PSPMT. The images for the alpha and beta particles and the gamma photons are individually formed by the pulse shape discriminations for each layer. We detected alpha particle images in the first layer and beta particle images in the second layer. Gamma photon images were detected in the second and third layers. The spatial resolution for the alpha and beta particles was ~1.25 mm FWHM and less than 2 mm FWHM for the gamma photons. We conclude that our developed alpha-beta-gamma imaging detector is promising for imaging applications not only for the environmental monitoring of radionuclides but also for medical and molecular imaging.

  4. A high-resolution, multi-parameter, β-γ coincidence, μ-γ anticoincidence system for radioxenon measurement

    International Nuclear Information System (INIS)

    A high-resolution β-γ coincidence measurement system has been developed by combining a high-purity broad energy germanium and a silicon surface barrier detector. The system is intended for calibration of reference spikes and re-measurement of CTBT samples, by detection of coincident β-γ or conversion electron and X-ray radiation of the four radioxenon isotopes 131mXe, 133mXe, 133Xe and 135Xe. The use of a high-resolution, list-mode, multi-parameter data acquisition system allows off-line setup and optimization of the (anti)coincidence. A 166mHo β-γ source has been produced and validated for energy calibration and system check. The β-γ coincidence has been further enhanced by a cosmic muon veto based on six plastic scintillation detectors. The μ-γ anticoincidence has been implemented using a 50 ns resolution real-time clock for time spectroscopy. This method has been verified by running conventional TAC-ADC (combined time-amplitude and analog-digital converter) based time spectroscopy in parallel. The whole measurement system has been characterized, by measuring various radioxenon spikes and backgrounds with and without (anti)coincidence. Peak efficiencies and minimum detectable activities (MDA) for the main radioxenon isotopes have been determined. Application of μ-γ anticoincidence reduced the MDA by about a factor of two for all four radioxenon isotopes. Complementary adoption of β-γ coincidence further reduced the MDA for the metastable isotopes by more than an order of magnitude. The MDA for 135Xe reaches about 6 mBq after 1 day of measurement. For 131mXe, 133Xe and 133mXe a MDA of about 2 mBq is obtained after one week measurement.

  5. Coincidence measurements with the use of detectors measuring the energy of the radiances (proportional meters and scintillation counter); Mesures de coincidences avec utilisation de detecteurs mesurant l'energie des rayonnements (compteurs proportionnels et compteur a scintillations)

    Energy Technology Data Exchange (ETDEWEB)

    Sartory, M. [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

    1953-07-01

    In the setting of the realization of a set of installations permitting of the measures of coincidences between sorted radiances according to their energies, an installation understanding a proportional counter and a scintillation counter has been constructed and optimized. It has been used to do some measures of coincidences between X{sub K} photons and photons {gamma} issued at the time of the radioactive transformation of the selenium 75 (electronic capture). The efficiency of the proportional meter has been determined roughly. Besides, a proportional counter of solid angle neighboring of 4{pi} was able to achieve measures of coincidences while only doing one selection of amplitudes: indeed, the simultaneity of the detection of two radiances appear by an impulse whose amplitude is the sum of the amplitudes of the impulses resulting from each of the studied radiations. This method, applied to the coincidences between X-rays, permitted to bring the information on the diagram of decay of the arsenic 73. Besides, the coefficient of internal conversion of a consecutive transition to this decay has been valued. (author) [French] Dans le cadre de la realisation d'une serie de montages permettant des mesures de coincidences entre rayonnements tries d'apres leurs energies, un montage comprenant un compteur proportionnel et un compteur a scintillations a ete construit et mis au point. Il a ete utilise pour effectuer quelques mesures de coincidences entre photons X{sub K} et photons {gamma} emis lors de la transformation radioactive du selenium 75 (capture electronique). L'efficacite du compteur proportionnel a ete approximativement determinee. De plus, un compteur proportionnel d'angle solide voisin de 4{pi} a pu etre utilise pour realiser des mesures de coincidences en n'effectuant qu'une selection d'amplitudes: en effet, la simultaneite de la detection de deux rayonnements se manifeste par une impulsion dont l'amplitude est la

  6. Coincidence measurements in α/β/γ spectrometry with phoswich detectors using digital pulse shape discrimination analysis

    International Nuclear Information System (INIS)

    A novel system has been developed for the detection of low radioactivity levels using coincidence techniques. The device combines a phoswich detector for α/β/γ ray recognition with a fast digital card for electronic pulse analysis. The detector is able to discriminate different types of radiation in a mixed α/β/γ field and can be used in a coincidence mode by identifying the composite signal produced by the simultaneous detection of β particles in a plastic scintillator and γ rays in an NaI(Tl) scintillator. Use of a coincidence technique with phoswich detectors was proposed recently to verify the Nuclear Test Ban Treaty, which made it necessary to monitor the low levels of xenon radioisotopes produced by underground nuclear explosions. Previous studies have shown that combining CaF2(Eu) for β ray detection and NaI(Tl) for γ ray detection makes it difficult to identify the coincidence signals because of the similar fluorescence decay times of the two scintillators. With the device proposed here, it is possible to identify the coincidence events owing to the short fluorescence decay time of the plastic scintillator. The sensitivity of the detector may be improved by employing liquid scintillators, which allow low radioactivity levels from actinides to be measured when present in environmental samples. The device developed is simpler to use than conventional coincidence equipment because it uses a single detector and electronic circuit, and it offers fast and precise analysis of the coincidence signals by employing digital pulse shape analysis

  7. A Compton-suppression spectrometer for γ-γ coincidence measurements: Large solid angle and excellent suppression

    NARCIS (Netherlands)

    Aarts, H.J.M.; Poel, C.J. van der; Scherpenzeel, D.E.C.; Arciszewski, H.F.R.; Engelbertink, G.A.P.

    1980-01-01

    For γ-γ coincidence measurements a Compton-suppression spectrometer with a large solid angle of 120 msr and excellent suppression has been designed. The dimensions of the NaI anticoincidence shield have been optimized by means of Monte Carlo calculations. The NaI shield has a length of 35 cm and a d

  8. Coincidence measurements of the (π+,π0p) reaction in the /triangle/-resonance region

    International Nuclear Information System (INIS)

    This thesis describes an experimental study of the (π+, π0p) reaction at incident energy T/sub π/sup +// = 165 MeV. This work is part of the first experiment to detect neutral pions and protons in coincidence in kinematically complete measurements. The reaction was studied on 16O (using water targets) at several pion angles: θ/sub π/sup 0// = 70/degree/, 80/degree/, 110/degree/, and 130/degree/. At θ/sub π/sup 0// = 110/degree/ measurements were also made on 56Fe, 120Sn, and 208Pb. The neutral pions were detected with the LAMPF π0 spectrometer, while the protons were detected in a vertical array of plastic-scintillator ΔE-E telescopes, each spanning 8.5 msr. Energy spectra of the differential cross sections d4σ/dE/sub π/sup 0// dE/sub p/dΩ/sub π/sup 0//dΩ/sub p/ were obtained for each proton telescope and subsequently integrated over proton and pion energy and proton angle. The characteristics of these spectra are consistent with a quasi-free description of the (π+,π0p) reaction. The angular dependence of dσ/dΩ/sub π/sup 0//(θ/sub π/sup 0//) for 16O(π+,π0p) was found to be in accordance with that of the cross section for the corresponding free reaction at backward π0 angles. For the 16O(π+,π0p) reaction, events in which a p-shell nucleon had been removed were identified. The p-shell events were found to constitute only 40--50% of the total cross section for quasi-free one-nucleon removal. The (π+,π0p) cross section at θ/sub π/sup 0// = 110/degree/ proved to be almost the same for all target nuclei, possibly slightly decreasing as a function of A. 102 refs., 108 figs., 24 tabs

  9. Retrieval of ozone column content from airborne Sun photometer measurements during SOLVE II: comparison with coincident satellite and aircraft measurements

    Directory of Open Access Journals (Sweden)

    J. M. Livingston

    2005-01-01

    Full Text Available During the 2003 SAGE (Stratospheric Aerosol and Gas Experiment III Ozone Loss and Validation Experiment (SOLVE II, the fourteen-channel NASA Ames Airborne Tracking Sunphotometer (AATS-14 was mounted on the NASA DC-8 aircraft and measured spectra of total and aerosol optical depth (TOD and AOD during the sunlit portions of eight science flights. Values of ozone column content above the aircraft have been derived from the AATS-14 measurements by using a linear least squares method that exploits the differential ozone absorption in the seven AATS-14 channels located within the Chappuis band. We compare AATS-14 columnar ozone retrievals with temporally and spatially near-coincident measurements acquired by the SAGE III and the Polar Ozone and Aerosol Measurement (POAM III satellite sensors during four solar occultation events observed by each satellite. RMS differences are 19 DU (6% of the AATS value for AATS-SAGE and 10 DU (3% of the AATS value for AATS-POAM. In these checks of consistency between AATS-14 and SAGE III or POAM III ozone results, the AATS-14 analyses use airmass factors derived from the relative vertical profiles of ozone and aerosol extinction obtained by SAGE III or POAM III.

    We also compare AATS-14 ozone retrievals for measurements obtained during three DC-8 flights that included extended horizontal transects with total column ozone data acquired by the Total Ozone Mapping Spectrometer (TOMS and the Global Ozone Monitoring Experiment (GOME satellite sensors. To enable these comparisons, the amount of ozone in the column below the aircraft is estimated either by assuming a climatological model or by combining SAGE and/or POAM data with high resolution in-situ ozone measurements acquired by the NASA Langley Research Center chemiluminescent ozone sensor, FASTOZ, during the aircraft vertical profile at the start or end of each flight. Resultant total column ozone values agree with corresponding TOMS and GOME measurements to

  10. Measurement of Q{sub {beta}} values of neutron-rich Tc to Pd isotopes in the mass range A=110 to A=117; Messung von Q{sub {beta}}-Werten neutronenreicher Tc- bis Pd-Isotope im Massenbereich A=110 bis A=117

    Energy Technology Data Exchange (ETDEWEB)

    Kloeckl, Ingo

    2008-06-15

    The present work describes the measuring of Q{sub {beta}} values of {beta}-instable isotopes of Tc, Ru, Rh and Pd. The mass range A=110 to 117 comprises neutron-rich, short-living isotopes. Due to their small (fission) abundances, few data are known, especially regarding level schemes or gamma radiation. The proton-induced fission and a fast online mass separation was used to produce these nuclides in the IGISOL facility located in Jyvaeskylaein Finland. The {beta},{gamma},X coincidence apparatus used during the experiments allows measuring Q{sub {beta}} values as well as {gamma},X coincidences. The latter represent the basic input data for a calculation of Q{sub {beta}} values out of {beta},{gamma} coincidences. It is so possible to examine nuclides with incomplete level schemes; similarly, these level schemes can be extended using beta,gamma coincidence data. Twelve Q{sub {beta}} values of neutron-rich Tc to Pd isotopes could be determined, yielding nuclear masses, mass defects and neutron separation energies. Eight of them were determined for the first time; another one could be confirmed. For three more, the error of earlier values could be decreased by a factor of nearly ten. The resulting data are of interest for the review of nuclear mass models, they represent also input in astrophysical network calculations. (orig.)

  11. The effect of two dead times in series on coincidence measurements

    International Nuclear Information System (INIS)

    Dead times in series occur in any counting device where detector signals are electronically amplified, selected for pulse height by a discriminator (or pulse-height analyzer) and fed through a dead-time unit producing a dead time, which has very often been designed to establish definite dead time losses. The problem of two dead times in series has been treated by J.W. Muller. No attempt, however, seems to have been made up to now to investigate this problem for the electronics of a coincidence system. In the paper presented here two dead times in series are considered that are found either in one or in both channels of a coincidence system. Correction formulas with experimental evidence are given which allow the deviations from results, which were calculated by taking only one dead time per channel into account, to be estimated. (author)

  12. Portable alpha, beta, gamma, x and neutron radiation monitor

    International Nuclear Information System (INIS)

    Full text: Here below there is short information about new instrument developed in SPE ATOMTEX, which will be produced at the close of the year. The instrument consists of the main unit, including built-in detector Nal (Tl) of diameter 25x40 mm and photomultiplier tube, analog devices (amplifier, multichannel pulse-height analyzer of 256 channels, high-voltage power supply, LED stabilization scheme of measuring path) and digital devices (microprocessor for data processing, control and storage, liquid crystal display, interface). The main unit operates also as processing and indication device of connected external detection units: α, β-radiation contamination scintillator detection unit; x, γ-radiation detection unit with silicon detector to measure equivalent dose and equivalent dose rate and n-radiation detection unit with proportional 3He-counters. Because of scintillator detector Nal (Tl), the main unit, operating in counting mode, searches and detects effectively x- and gamma-radiation sources with the energy from 30 keV to 3 MeV. The point source of 137Cs of 50 kBq is detected at the distance of 10 cm for 2s. Ambient equivalent dose and equivalent dose rate are measured with this detector using the method of instrumental spectrum transformation into dose. In this case the energy range is from 40 keV to 3 meV. Energy relationship of readings do not exceed ± 15% with respect to the energy of 0,662 MeV. The range of ambient equivalent dose rate measurement is from 0,05 μSv/h to 0,05 mSv/h, with response time of 20 s at background change from 0,05 μSv/h to 0,1 μSv/h. The main unit operates also as selective express-radiometer, which could evaluate sample activity by single gamma-line. Measurement geometry is Marinelly's vessel of 0,5 l. The lower limit of measuring activity is 300 Bq/l without lead shield and 20 Bq/l with it with measurement time of 10 min. The unit weighs not more than 0,9 kg. External detection units connect to interface socket by turns

  13. Study of a 4πβ-γ coincidence system for absolute radionuclide activity measurement using plastic scintillators

    International Nuclear Information System (INIS)

    The present work was intended to study a coincidence system 4π(PS)β-γ for absolute activity measurement using plastic scintillators in 4π geometry. Along with experiments on the coincidence system, simulations were also performed applying the Monte Carlo Method, by means of codes PENELOPE and ESQUEMA. These simulations were performed in order to calculate the extrapolation curve of the coincidence system 4π(PS)β-γ and compare it to experimental data. A new geometry was proposed to the coincidence system adding up a second photomultiplier tube to the previous system for improving light collection from the plastic scintillator, as this system presented limitations in the minimum detected energy due to the presence of electronic noise and low gain. The results show that an improvement in the signal-to-noise ratio was obtained, as well as in the minimum detected energy. Moreover, there was an increase in the detection efficiency. With these modifications, it is now possible to calibrate radionuclides which emit low energy electrons or X-rays, increasing the number of radionuclides that can be standardized with this type of system.(author)

  14. Absolute measurements of the alpha-gamma emitters activities by a sum-coincidence method

    International Nuclear Information System (INIS)

    The absolute activity of U-235 contained in a UO2 sample, using a sum-coincidence circuit which selected only the alpha particles which were simultaneous with the well known 184 Kev gamma radiation from Th-231. The alpha particles were detected by ZnS(Ag) scintillator specially designed to show its maximun efficiency for U-235 alpha particles, whereas the gamma radiation was detected by NaI(Tl) scintillation detector. The values obtained for the half-life of U-235 was compared with data from various observers using different experimental techniques. (Author)

  15. Note: An improved 3D imaging system for electron-electron coincidence measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yun Fei; Lee, Suk Kyoung; Adhikari, Pradip; Herath, Thushani; Lingenfelter, Steven; Winney, Alexander H.; Li, Wen, E-mail: wli@chem.wayne.edu [Department of Chemistry, Wayne State University, Detroit, Michigan 48202 (United States)

    2015-09-15

    We demonstrate an improved imaging system that can achieve highly efficient 3D detection of two electrons in coincidence. The imaging system is based on a fast frame complementary metal-oxide semiconductor camera and a high-speed waveform digitizer. We have shown previously that this detection system is capable of 3D detection of ions and electrons with good temporal and spatial resolution. Here, we show that with a new timing analysis algorithm, this system can achieve an unprecedented dead-time (<0.7 ns) and dead-space (<1 mm) when detecting two electrons. A true zero dead-time detection is also demonstrated.

  16. Measurement of $\\gamma\\gamma$-coincidences and $^{152}Tb \\to ^{152}Gd$ Decay Scheme

    CERN Document Server

    Adam, J; Honusek, M; Kalinnikov, V G; Mrazek, J; Pronskikh, V S; Caloun, P; Lebedev, N A; Stegailov, V I; Tsoupko-Sitnikov, V M

    2001-01-01

    On the basis of \\gamma\\gamma-coincidences recorded with two HPGe-detectors, 242 transitions were placed into the ^{152}Tb\\to^{152}Gd decay scheme, 131 of them - for the first time. Also, 46 new levels were introduced for the first time (out of 111). For a number of low-lying levels the electron capture to positron decay ratio was found. For the most of levels, their spins and parities were determined, as well as log ft's for feeding them decays.

  17. Alpha and conversion electron spectroscopy of 238,239Pu and 241Am and alpha-conversion electron coincidence measurements

    Science.gov (United States)

    Dion, Michael P.; Miller, Brian W.; Warren, Glen A.

    2016-09-01

    A technique to determine the isotopic constituents of a mixed actinide sample has been proposed by a coincident alpha-conversion electron measurement. This presents a unique signature to allow the unfolding of isotopes that possess overlapping alpha particle energy and reduce backgrounds of an unseparated sample. The work presented here are results of conversion electron spectroscopy of 241Am, 238Pu and 239Pu using a dual-stage peltier-cooled 25 mm2 silicon drift detector and alpha spectroscopy with a passivated ion implanted planar silicon detector. The conversion electron spectra were evaluated from 20-55 keV based on fits to the dominant conversion electron emissions, which allowed the relative conversion electron emission intensities to be determined. These measurements provide crucial singles spectral information and calibration to aid in the coincident measurement approach. Furthermore, an alpha-conversion electron spectrometer was assembled using the silicon based detectors described and results of a coincident spectrum analysis is reported for 241Am.

  18. L{sub i} ({alpha}, {beta}, {gamma}, l) subshell X-ray production cross-sections and theirs emission ratio in Pb and Au for proton energy 1-2.5 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Ouziane, S [Faculte de Physique, Universite des Sciences et de Technologie Houari Boumediene, BP 32, El Alia, Bab Ezzouar 16111 Alger (Algeria); Amokrane, A [Faculte de Physique, Universite des Sciences et de Technologie Houari Boumediene, BP 32, El Alia, Bab Ezzouar 16111 Alger (Algeria); Toumert, I [Centre de Recherches Nucleaires d' Alger, 2 Bd Frantz Fanon, BP 399, Alger (Algeria)

    2006-05-15

    The L{sub i} ({alpha}, {beta}, {gamma}, l) subshell X-ray production cross-sections for Pb and Au were measured at incident proton energy between 1 to 2.5 MeV. The obtained data are compared to available data given in Sokhi and Crumpton and Orlic and al. compilations. The given data are also compared with the predictions of ECPSSR model. The comparison shows a good agreement.

  19. A tandem time–of–flight spectrometer for negative–ion/positive–ion coincidence measurements with soft x-ray excitation

    Energy Technology Data Exchange (ETDEWEB)

    Stråhlman, Christian, E-mail: Christian.Strahlman@maxlab.lu.se; Sankari, Rami; Nyholm, Ralf [MAX IV Laboratory, Lund University, P.O. Box 118, 22100 Lund (Sweden); Kivimäki, Antti [Consiglio Nazionale delle Ricerche—Istituto Officina dei Materiali, Laboratorio TASC, 34149 Trieste (Italy); Richter, Robert [Elettra–Sincrotrone Trieste, Area Science Park, 34149 Trieste (Italy); Coreno, Marcello [Consiglio Nazionale delle Ricerche—Istituto di Struttura della Materia, 34149 Trieste (Italy)

    2016-01-15

    We present a newly constructed spectrometer for negative–ion/positive–ion coincidence spectroscopy of gaseous samples. The instrument consists of two time–of–flight ion spectrometers and a magnetic momentum filter for deflection of electrons. The instrument can measure double and triple coincidences between mass–resolved negative and positive ions with high detection efficiency. First results include identification of several negative–ion/positive–ion coincidence channels following inner-shell photoexcitation of sulfur hexafluoride (SF{sub 6})

  20. A tandem time-of-flight spectrometer for negative-ion/positive-ion coincidence measurements with soft x-ray excitation

    Science.gov (United States)

    Strâhlman, Christian; Sankari, Rami; Kivimäki, Antti; Richter, Robert; Coreno, Marcello; Nyholm, Ralf

    2016-01-01

    We present a newly constructed spectrometer for negative-ion/positive-ion coincidence spectroscopy of gaseous samples. The instrument consists of two time-of-flight ion spectrometers and a magnetic momentum filter for deflection of electrons. The instrument can measure double and triple coincidences between mass-resolved negative and positive ions with high detection efficiency. First results include identification of several negative-ion/positive-ion coincidence channels following inner-shell photoexcitation of sulfur hexafluoride (SF6).

  1. Decay data measurements of 64Cu by 4πβ-γ coincidence technique and photon spectrometry

    International Nuclear Information System (INIS)

    The principal decay data for 64Cu were determined by 4πβ(PC)-γ coincidence techniques and photon spectrometry. The probability of electron capture was assessed from consistent results of three experiments; (1) measurements by the slope-to-intercept ratio method based on the 4πx-γ coincidence counting gated with the 1.34 MeV γ-rays, (2) K x-ray measurements with a calibrated low energy photon spectrometer (LEPS), and (3) 4πβ-ray emission rate measurements using sandwiched sources. Method (1) is practically independent of the decay parameters. The emission rate per decay of the positrons decay and of the 1.34 MeV γ-rays were measured with a calibrated Ge γ-ray spectrometer. From these measurements, the branching fraction of positron decay, negatron decay and electron capture and the γ-intensity per decay could be evaluated with uncertainties between 1.0 and 1.2% except for about a 4% uncertainty for the γ fraction. (author)

  2. Validation of ACE-FTS satellite data in the upper troposphere/lower stratosphere (UTLS using non-coincident measurements

    Directory of Open Access Journals (Sweden)

    P. Hoor

    2008-03-01

    Full Text Available CO, O3, and H2O data in the upper troposphere/lower stratosphere (UTLS measured by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS on Canada's SCISAT-1 satellite are validated using aircraft and ozonesonde measurements. In the UTLS, validation of chemical trace gas measurements is a challenging task due to small-scale variability in the tracer fields, strong gradients of the tracers across the tropopause, and scarcity of measurements suitable for validation purposes. Validation based on coincidences therefore suffers from geophysical noise. Two alternative methods for the validation of satellite data are introduced, which avoid the usual need for coincident measurements: tracer-tracer correlations, and vertical tracer profiles relative to tropopause height. Both are increasingly being used for model validation as they strongly suppress geophysical variability and thereby provide an "instantaneous climatology". This allows comparison of measurements between non-coincident data sets which yields information about the precision and a statistically meaningful error-assessment of the ACE-FTS satellite data in the UTLS. By defining a trade-off factor, we show that the measurement errors can be reduced by including more measurements obtained over a wider longitude range into the comparison, despite the increased geophysical variability. Applying the methods then yields the following upper bounds to the relative differences in the mean found between the ACE-FTS and SPURT aircraft measurements in the upper troposphere (UT and lower stratosphere (LS, respectively: for CO ±9% and ±12%, for H2O ±30% and ±18%, and for O3 ±25% and ±19%. The relative differences for O3 can be narrowed down by using a larger dataset obtained from ozonesondes, yielding a high bias in the ACE-FTS measurements of 18% in the UT and relative differences of ±8% for measurements in the LS

  3. Validation of ACE-FTS satellite data in the upper troposphere/lower stratosphere (UTLS) using non-coincident measurements

    Science.gov (United States)

    Hegglin, M. I.; Boone, C. D.; Manney, G. L.; Shepherd, T. G.; Walker, K. A.; Bernath, P. F.; Daffer, W. H.; Hoor, P.; Schiller, C.

    2008-03-01

    CO, O3, and H2O data in the upper troposphere/lower stratosphere (UTLS) measured by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) on Canada's SCISAT-1 satellite are validated using aircraft and ozonesonde measurements. In the UTLS, validation of chemical trace gas measurements is a challenging task due to small-scale variability in the tracer fields, strong gradients of the tracers across the tropopause, and scarcity of measurements suitable for validation purposes. Validation based on coincidences therefore suffers from geophysical noise. Two alternative methods for the validation of satellite data are introduced, which avoid the usual need for coincident measurements: tracer-tracer correlations, and vertical tracer profiles relative to tropopause height. Both are increasingly being used for model validation as they strongly suppress geophysical variability and thereby provide an "instantaneous climatology". This allows comparison of measurements between non-coincident data sets which yields information about the precision and a statistically meaningful error-assessment of the ACE-FTS satellite data in the UTLS. By defining a trade-off factor, we show that the measurement errors can be reduced by including more measurements obtained over a wider longitude range into the comparison, despite the increased geophysical variability. Applying the methods then yields the following upper bounds to the relative differences in the mean found between the ACE-FTS and SPURT aircraft measurements in the upper troposphere (UT) and lower stratosphere (LS), respectively: for CO ±9% and ±12%, for H2O ±30% and ±18%, and for O3 ±25% and ±19%. The relative differences for O3 can be narrowed down by using a larger dataset obtained from ozonesondes, yielding a high bias in the ACE-FTS measurements of 18% in the UT and relative differences of ±8% for measurements in the LS. When taking into account the smearing effect of the vertically limited

  4. A program to generate simulated radioxenon beta-gamma data for concentration verification and validation and training exercises

    International Nuclear Information System (INIS)

    PNNL developed a beta-gamma simulator (BGSim) that incorporated GEANT-modeled data sets from radioxenon decay chains, as well as functionality to use nuclear detector-acquired data sets to create new beta-gamma spectra with varying amounts of background, 133Xe, 131mXe, 133mXe, 135Xe, and 222Rn and its decay products. After BGSim was developed, additional uses began to be identified for the program output: training sets of two-dimensional spectra for data analysts at the IDC and other NDC, and spectra for exercises such as the Integrated Field Exercise 2014 held in Jordan at the Dead Sea. (author)

  5. Response-surface models for deterministic effects of localized irradiation of the skin by discrete {beta}/{gamma} -emitting sources

    Energy Technology Data Exchange (ETDEWEB)

    Scott, B.R.

    1995-12-01

    Individuals who work at nuclear reactor facilities can be at risk for deterministic effects in the skin from exposure to discrete {Beta}- and {gamma}-emitting ({Beta}{gamma}E) sources (e.g., {Beta}{gamma}E hot particles) on the skin or clothing. Deterministic effects are non-cancer effects that have a threshold and increase in severity as dose increases (e.g., ulcer in skin). Hot {Beta}{gamma}E particles are {sup 60}Co- or nuclear fuel-derived particles with diameters > 10 {mu}m and < 3 mm and contain at least 3.7 kBq (0.1 {mu}Ci) of radioactivity. For such {Beta}{gamma}E sources on the skin, it is the beta component of the dose that is most important. To develop exposure limitation systems that adequately control exposure of workers to discrete {Beta}{gamma}E sources, models are needed for systems that adequately control exposure of workers to discrete {Beta}{gamma}E sources, models are needed for evaluating the risk of deterministic effects of localized {Beta} irradiation of the skin. The purpose of this study was to develop dose-rate and irradiated-area dependent, response-surface models for evaluating risks of significant deterministic effects of localized irradiation of the skin by discrete {Beta}{gamma}E sources and to use modeling results to recommend approaches to limiting occupational exposure to such sources. The significance of the research results as follows: (1) response-surface models are now available for evaluating the risk of specific deterministic effects of localized irradiation of the skin; (2) modeling results have been used to recommend approaches to limiting occupational exposure of workers to {Beta} radiation from {Beta}{gamma}E sources on the skin or on clothing; and (3) the generic irradiated-volume, weighting-factor approach to limiting exposure can be applied to other organs including the eye, the ear, and organs of the respiratory or gastrointestinal tract and can be used for both deterministic and stochastic effects.

  6. Determination of the absolute activity by the coincidences 4πβ-γ method

    International Nuclear Information System (INIS)

    The 4π beta-gamma coincidence method for absolute determination of activities is extremely important in the production of high-precision radioactive sources. By means of this method it is possible to obtain absolute measurements of decay to within 0.1%. Thanks to the high efficiency of the 4π counter, most of the corrections required - background, random coincidences, dead time, decay scheme and detector efficiency - are small. The paper describes the experimental set-up showing the pulses in the two branches of the system, together with the conditions under which the 4πbeta flux detector functions. To determine whether the system was functioning satisfactorily, the activity of four cobalt-60 standards (supplied by the International Bureau of Weights and Measures based at Sevres in France) was determined and the differences obtained were less than 0.5% with respect to the certificates accompanying the sources. Alterations to the flux detector are suggested so that higher accuracy may be obtained. (author)

  7. Validation of ACE-FTS satellite data in the upper troposphere/lower stratosphere (UTLS using non-coincident measurements

    Directory of Open Access Journals (Sweden)

    M. I. Hegglin

    2007-09-01

    Full Text Available CO, O3, and H2O data in the upper troposphere/lower stratosphere (UTLS measured by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS on Canada's SCISAT-1 satellite are validated using aircraft measurements. In the UTLS, validation of chemical trace gas measurements is a challenging task due to small-scale variability in the tracer fields, strong gradients of the tracers across the tropopause, and scarcity of measurements suitable for validation purposes. Two alternative methods for the validation of the satellite data are introduced, which avoid the usual need for coincident measurements: tracer-tracer correlations, and vertical profiles relative to the tropopause height. Both largely reduce geophysical variability and thereby provide an "instantaneous climatology", allowing measurement comparison with non-coincident data which yields information about the precision, and a statistically meaningful error-assessment of the ACE-FTS satellite data. We found that the ACE-FTS CO and lower stratospheric O3 agree with the aircraft measurements within ±10% and ±5%, respectively. The ACE-FTS O3 in the UT exhibits a high bias of up to 40%. H2O indicates a low bias with relative differences of around 20% in the LS and 40% in the UT, respectively. When taking into account the smearing effect of the vertically limited spacing between measurements of the ACE-FTS instrument, the errors decrease by 5–15% around the tropopause. The ACE-FTS instrument hence offers unprecedented precision and vertical resolution in the UTLS, that will allow a new global perspective on UTLS tracer distributions.

  8. The Coincidence Tracker: Electronic Equipment for a Time-of-Flight Wind-Speed Measurement System

    DEFF Research Database (Denmark)

    Fog, Christian

    1982-01-01

    The electronic part of a laser-beam measuring system for wind velocity is described. Pulses of light scattered from aerosols are treated, first in a pair of adaptive filters, then in a tracker that calculates the wind velocity on-line while applying some knowledge about the velocity to be expected...... on the basis of preceding measurements. Practical measurements with the system are compared with traditional technique....

  9. Self-attenuation and coincidence-summing corrections calculated by Monte Carlo simulations for gamma-spectrometric measurements with well-type germanium detectors

    International Nuclear Information System (INIS)

    A Monte Carlo simulation package for the computation of the full-energy peak efficiency, self-attenuation correction factors and coincidence-summing corrections has been developed to assist in the calibration of well-type germanium detector measurements. Due to the almost 4π solid angle for this measurement geometry, particularly high coincidence-summing effects occur in the case of multi-photon emitting nuclides. Besides pair coincidences, the correction terms required to describe higher order coincidences have been included in the computation of the coincidence-summing effects. A general algorithm for self-attenuation calculations, working accurately as well in the case of high attenuating media, has been implemented. The computed results are in good agreement with the experimental data. (Author)

  10. The direct measurement using an imaging plate for coincidence of radiation centre and laser position in external radiation therapy

    International Nuclear Information System (INIS)

    A new method of quality assurance has been studied to measure coincidence of the radiation centre and a patient-setup laser position on a transverse plane to the beam at the isocentre. This measurement is achieved by using an imaging plate (IP). When radiation is applied to an IP, the energy is stored as trapped electrons. The number of electrons is decreased by local laser exposure. As a result, the radiation field produced by external beam irradiation is recorded as 'positive' information and the position of the patient-setup laser is recorded as 'negative' on an IP. The advantages of this method are the direct measurement, short time and high resolution. These are required for daily and monthly quality checks. We confirmed the advantage of this method by an experiment using a proton beam. (note)

  11. Time-Dependent Coincidence Method to Measure Plutonium Mass and Multiplication

    International Nuclear Information System (INIS)

    Future nuclear disarmament agreements between nations may require technical measures to ascertain each participating nation's adherence to the agreement. Almost certainly, measurement technologies and analytical methods will have to be developed by the participating nations jointly. In this way each participant has both confidence in the technology's efficacy and trust in its implementation. With the support of the National Nuclear Security Administration's Office of Nonproliferation Policy (NNSA NA-241), the Oak Ridge National Laboratory (ORNL) and the All-Russian Scientific Research Institute of Experimental Physics (VNIIEF) have taken first steps to jointly develop and implement a radiation measurement technique to inspect plutonium. In June and July 2000, personnel from ORNL and VNIIEF performed joint experiments on unclassified plutonium metal ((delta)-phase, 1.77%-(sup 240)Pu) spherical shells at VNIIEF facilities in Sarov, Russia[1,2]. The measurements were performed using the Nuclear Materials Identification System (NMIS). The subsequent analysis demonstrates how NMIS can be applied to passively measure the mass and multiplication of plutonium spherical shells

  12. Coincident measurements of prompt fission γ rays and fission fragments at DANCE

    Science.gov (United States)

    Walker, C. L.; Baramsai, B.; Jandel, M.; Rusev, G.; Couture, A.; Mosby, S.; Ullmann, J.; Kawano, T.; Stetcu, I.; Talou, P.

    2015-10-01

    Modern statistical approaches to modeling fission involve the calculation of not only average quantities but also fully correlated distributions of all fission products. Applications such as those involving the detection of special nuclear materials also rely on fully correlated data of fission products. Experimental measurements of correlated data are thus critical to the validation of theory and the development of important applications. The goal of this experiment was to measure properties of prompt fission gamma-ray emission as a function of fission fragments' total kinetic energy in the spontaneous fission of 252Cf. The measurement was carried out at the Detector for Advanced Neutron Capture Experiments (DANCE), a 4 π γ-ray calorimeter. A prototype design consisting of two silicon detectors was installed in the center of DANCE, allowing simultaneous measurement of fission fragments and γ rays. Effort has been taken to simulate fragment kinetic energy losses as well as γ-ray attenuation in DANCE using such tools as GEANT4 and SRIM. Theoretical predictions generated by the code CGMF were also incorporated as input for these simulations. Results from the experiment and simulations will be presented, along with plans for future measurements.

  13. The Coincidence Tracker: Electronic Equipment for a Time-of-Flight Wind-Speed Measurement System

    DEFF Research Database (Denmark)

    Fog, Christian

    1982-01-01

    The electronic part of a laser-beam measuring system for wind velocity is described. Pulses of light scattered from aerosols are treated, first in a pair of adaptive filters, then in a tracker that calculates the wind velocity on-line while applying some knowledge about the velocity to be expected...

  14. Absolute nuclear energy measurements using the γ-γ coincidence method

    International Nuclear Information System (INIS)

    I n this report a summary is first given of the principle of the γ-γ calibration method, stress being laid on the corrections required. After a description of the equipment used, the choice of the experimental conditions required for various isotopes is discussed (22Na, 46Sc, 60Co, 88Y) and the agreement between these results and those obtained by other absolute measurement methods is considered. (authors)

  15. Peculiarities of the clinical course of radiation sickness and organizational decisions for radiation accidents with beta-gamma sources

    International Nuclear Information System (INIS)

    The analysis of a number of recent large scale accidents involving beta-gamma sources in the last 40 years, such as those of the Marshall Islands (1954); Windscale, UK (1957); Chernobyl, USSR (1986) and Goiania, Brazil (1987) demonstrates the predominance and importance of health and social impacts. (author)

  16. Study of Rare B-Meson Decays Related to the CPObservable sin(2beta+gamma) at the BABAR Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Orimoto, Toyoko Jennifer

    2007-08-21

    This study reports the observation of the decays B{sup 0}{yields}D{sup (*)+}{sub S}{pi}{sup -} and B{sup 0}{yields}D{sup (*)-}K{sup +} in a sample of 230 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} storage ring, located at the Stanford Linear Accelerator Center. The branching fractions {beta}(B{sup 0} {yields} D{sup +}{sub S}{pi}{sup -}) = (1.3 {+-} 0.3 (stat) {+-} 0.2 (syst)) x 10{sup -5}, {beta}(B{sup 0} {yields} D{sup +}{sub S}K{sup +}) = (2.5 {+-} 0.4 (stat) {+-} 0.4 (syst)) x 10{sup -5}, {beta}(B{sup 0}{yields}D{sup (*)+}{sub S}{pi}{sup -}) = (2.8 {+-} 0.6 (stat) {+-} 0.5 (syst)) x 10{sup -5}, and {beta}(B{sup 0}{yields}D{sup (*)-}K{sup +}) = (2.0 {+-} 0.5 (stat) {+-} 0.4 (syst)) x 10{sup -5} are measured. The significance of the measurements to differ from zero are 5, 9, 6, and 5 standard deviations, respectively. This is a first observation of the decaysB{sup 0}{yields}D{sup (*)+}{sub S}{pi}{sup -} and B{sup 0}{yields}D{sup (*)-}K{sup +}. These results may potentially be useful in determining the CP asymmetry parameter sin(2{beta} + {gamma}) in the decays B{sup 0}{yields}D{sup (*)+}{sub S}{pi}{sup -}.

  17. Research, design and manufacture of a coincidence spectroscopy to measure energy-time spectra based on the DSP technique

    International Nuclear Information System (INIS)

    The coincidence technique and the coincidence spectroscopy has been developed and applied from the 1950s of last century. This technique is used mainly for studying the phenomenon of radioactive decay with time factor correlation. The popular coincidence spectroscopy are manufacture by analog technology which are many NIM or CAMAC electronic modules. This made not convenient for users. Today, the development of digital signal processing (DSP) technique and field-programmable gate array (FPGA) permits made compact spectroscopy with more power and convenient. This project applied DSP and FPGA to manufacture a compact coincidence spectroscopy. (author)

  18. Measurement of the background in Auger-photoemission coincidence spectra (APECS) associated with inelastic or multi-electron valence band photoemission processes

    OpenAIRE

    Satyal, S.; Joglekar, P. V.; Shastry, K.; Kalaskar, S.; Dong, Q.; Hulbert, S. L.; Bartynksi, R. A.; Weiss, A. H.

    2014-01-01

    Auger Photoelectron Coincidence Spectroscopy (APECS), in which the Auger spectra is measured in coincidence with the core level photoelectron, is capable of pulling difficult to observe low energy Auger peaks out of a large background due mostly to inelastically scattered valence band (VB) photoelectrons. However the APECS method alone cannot eliminate the background due to valence band photoemission processes in which the initial photon energy is shared by two or more electrons and one of th...

  19. Experiments using coincidence methods

    International Nuclear Information System (INIS)

    Experiments on γ spectroscopy using the simple coincidence techniques, including investigation of angular distribution of γ radiation from annihilation process in decay of Na22, γ - γ angular correlation technique in decay of Co60, decay scheme study of Bi207 and life time measurement of nuclear Pb207 excited state have been carried out. (author)

  20. Fragmentation of CF3Br induced by fluroine is core excitation: Energy resolved auger electron multiple-ion coincidence measurements

    International Nuclear Information System (INIS)

    Fragmentation processes in CF3Br near the F K edge were investigated using synchrotron radiation and Energy Resolved Auger Electron Multiple Ion Coincidence (ERAEMICO). Time-of flight mass spectra were collected in coincidence with either selected F 1s Auger or resonant-Auger electrons which were energy analyzed with a hemispherical detector. In addition, a more inclusive mass spectrum was taken near the F 1s ionization potential in coincidence with low energy electrons. Preliminary spectra the Br2+ ion intensity is negligible and the relative CF+ abundance is higher. These differences confirm the notion that the electronic state prior to bond breakage governs the resulting fragmentation pattern

  1. Data-model comparison search analysis of coincident PBO Balmer α, EURD Lyman β geocoronal measurements from March 2000

    Science.gov (United States)

    Bishop, J.; Mierkiewicz, E. J.; Roesler, F. L.; Gómez, J. F.; Morales, C.

    2004-05-01

    Recent Lyman series and Balmer series airglow measurements provide a fresh opportunity to investigate the density distribution and variability of atomic hydrogen in the upper atmosphere. Dedicated nightside Balmer α Fabry-Perot spectrometer measurements at the Pine Bluff Observatory (PBO), University of Wisconsin-Madison, have been acquired since late 1999 taking advantage of several technological advances. Extreme ultraviolet spectral radiance measurements by the Espectrógrafo Ultravioleta extremo para la Radiación Difusa (EURD) instrument on the Spanish MINISAT-1 satellite from October 1997 to December 2001 provide extensive sets of geocoronal Lyman β, Lyman γ and He 584 Å emission intensities. In this paper, coincident EURD Lyman β and PBO Balmer α radiance measurements from the early March 2000 new moon period are presented. In addition to serving as examples of the data sets now available, the data volume poses an analysis challenge not faced in prior geocoronal studies. A data-model comparison search procedure employing resonance radiation transport results for extensive sets of parametric density distribution models is being developed for use in analyses of multiple large data sets; this is described, and example results for the PBO and EURD March 2000 data sets are presented. The tightness of the constraints obtained for the solar line-center Lyman β irradiance and the atomic hydrogen column abundance is somewhat surprising, given the crudeness of the parameter binning in the search procedure and the fact that a small number of recognized corrections remain to be made to each data set.

  2. Management of defense beta-gamma contaminated solid low-level wastes

    International Nuclear Information System (INIS)

    In DOE defense operations, approx. 70,000 m3 of beta-gamma low-level radioactive waste are disposed of annually by shallow land burial operations at six primary sites. Waste generated at other DOE sites are transported on public roads to the primary sites for disposal. In the practice of low-level waste (LLW) disposal in the US, the site hydrology and geology are the primary barriers to radioactive migration. To date, little emphasis has been placed on waste form improvements or engineered site modifications to reduce migration potential. Compaction is the most common treatment step employed. The performance of ground disposal of radioactive waste in this country, in spite of many practices that we would consider unacceptable in today's light, has resulted in very little migration of radioactivity outside site boundaries. Most problems with previously used burial grounds have been from subsidence at the arid sites and subsidence and groundwater contact at the humid sites. The radionuclides that have shown the most significant migration are tritium, 90Sr, and 99Tc. The unit cost for disposal operations at a given DOE site is dependent on many variables, but the annual volume to be disposed is probably the major factor. The average cost for current DOE burial operation is approximately $170/m3. 23 figures

  3. Line C17: alpha and medium-level beta-gamma laboratory pilot facility

    International Nuclear Information System (INIS)

    The Process Development Laboratory (LDP) uses the ATALANTE C17 line for integral testing in order to develop and validate spent fuel reprocessing methods and for overall qualification of calculation codes. Line C 17 comprises shielded cells and glove boxes, equipped with centrifugal extractors and laboratory-scale mixer-settlers to test liquid-liquid extraction processes in an alpha and medium-level beta-gamma environment. The high reliability and precision of the process instrumentation and control system allow full control of operating parameters and comprehensive operating data recording, meeting the experimentation quality requirements necessary for qualifying calculation codes. Direct online spectrophotometric analysis at various points in the process provides real-time concentration data for vital elements, some of which are difficult to analyze offline because of their poor chemical stability. Online analyses, supplemented when necessary by gamma spectrometry, provide valuable process control input for reaching stabilized operating conditions. Fifteen radioactive test campaigns have been successfully completed since line C 17 was commissioned in June 1995. (authors)

  4. Coincident measurement of the reaction of 16O(πsup(+-),πsup(+-)'p) at 240 MeV

    International Nuclear Information System (INIS)

    In a coincidence measurement the reactions 0-16(π+,π+'p) and 0-16(π-,π4p) were studied at an incident energy of the pions of 240 MeV. The scattered pion and the outknocked proton were thereby detected over a large angular and energy range, and the shell state of the interacting proton in 0-16 before the reaction was determined. With this it is possible to identify the direct quasi-free reaction of the pion and to study its behaviour. The experimental arrangement necessary for this as well as the main topics of the data analysis are described, and the results are presented and discussed in the form of differential cross sections. The experiments were performed at the Swiss Institute for Nuclear Research and used the SUSI spectrometer for the detection of the pions and large-area scintillator telescopes for the spectroscopy of the outknocked protons. A comparized of the differential cross sections for π+ with theoretical calculations in the DWIA formalism shows for the quasi-free reaction contributions the same qualitative behaviour. For the ratio of π+ to π- induced reactions large differences to the free πp scattering result. They are qualitatively described by calculations in the Δ-hole formalism by means of an isospin dependent Δ-nucleus interaction and permit with this a first determination of the single isospin component of the interaction. (orig./HSI)

  5. Cyclic oxidation behavior of beta+gamma overlay coatings on gamma and gamma+gamma-prime alloys

    Science.gov (United States)

    Nesbitt, J. A.; Pilsner, B. H.; Carol, L. A.; Heckel, R. W.

    1984-01-01

    Detailed experimental studies of the cyclic oxidation behavior of low-pressure plasma sprayed beta+gamma coasting on gamma-phase Ni-Cr-Al alloys have shown the correlation of weight change, oxide type, and Cr and Al concentration-distance profiles as a function of oxidation time. Of special interest was the transition to breakway oxidation due to the loss of the Al flux to the oxide and the failure of the coated alloy to form an Al2O3-rich oxide scale. The experimental results on beta+gamma/gamma coating systems were used as the basis of a numerical model (ternary, semi-infinite, finite-difference analysis) which accurately predicted changes in Cr and Al concentration-distance profiles. The model was used to study parameters critical to enhancing the life of coatings which fail by a combination of Al loss in forming the oxide scale and Al loss via interdiffusion with the substrate alloy. Comparisons of beta+gamma/gamma coating behavior are made to the oxidation of coated gamma+gamma-prime substrates, both ternary Ni-Cr-Al alloys and Mar-M 247-type alloys.

  6. The Generalized Centroid Difference method for lifetime measurements via γ-γ coincidences using large fast-timing arrays

    Directory of Open Access Journals (Sweden)

    Régis J.-M.

    2015-01-01

    Full Text Available A novel method for direct electronic “fast-timing” lifetime measurements of nuclear excited states via γ-γ coincidences using an array equipped with N very fast high-resolution LaBr3(Ce scintillator detectors is presented. The generalized centroid difference method provides two independent “start” and “stop” time spectra obtained without any correction by a superposition of the N(N – 1/2 calibrated γ-γ time difference spectra of the N detector fast-timing system. The two fast-timing array time spectra correspond to a forward and reverse gating of a specific γ-γ cascade and the centroid difference as the time shift between the centroids of the two time spectra provides a picosecond-sensitive mirror-symmetric observable of the set-up. The energydependent mean prompt response difference between the start and stop events is calibrated and used as a single correction for lifetime determination. These combined fast-timing array mean γ-γ zero-time responses can be determined for 40 keV < Eγ < 1.4 MeV with a precision better than 10 ps using a 152Eu γ-ray source. The new method is described with examples of (n,γ and (n,f,γ experiments performed at the intense cold-neutron beam facility PF1B of the Institut Laue-Langevin in Grenoble, France, using 16 LaBr3(Ce detectors within the EXILL&FATIMA campaign in 2013. The results are discussed with respect to possible systematic errors induced by background contributions.

  7. The influence from low energy x-rays and Auger electrons on 4πβ-γ coincidence measurements of electron-capture-decaying nuclides

    International Nuclear Information System (INIS)

    The influence of low energy x-rays and Auger electrons emitted by electron capture nuclides on 4πβ-γ coincidence measurements is investigated. Under the assumption that these radiations are not detected, correction terms are developed for a number of nuclides that are in common use. (author)

  8. Elaboration of Co-60 sources on gilding vyns, with beta efficiencies 80 % or better and its activity measure by the coincidences method

    International Nuclear Information System (INIS)

    The measuring technique of radioactive activity by the coincidences method 4 π β- γ it requires of the elaboration of radioactive sources on thin supports in order to flows the biggest percentage of beta particles, those of the order of the 80 % or but. In this work a procedure for the elaboration of this type of sources, with gilding Vyns is reported. (Author)

  9. Pure phase-locking of beta/gamma oscillation contributes to the N30 frontal component of somatosensory evoked potentials

    Directory of Open Access Journals (Sweden)

    Leroy Axelle

    2007-09-01

    Full Text Available Abstract Background Evoked potentials have been proposed to result from phase-locking of electroencephalographic (EEG activities within specific frequency bands. However, the respective contribution of phasic activity and phase resetting of ongoing EEG oscillation remains largely debated. We here applied the EEGlab procedure in order to quantify the contribution of electroencephalographic oscillation in the generation of the frontal N30 component of the somatosensory evoked potentials (SEP triggered by median nerve electrical stimulation at the wrist. Power spectrum and intertrial coherence analysis were performed on EEG recordings in relation to median nerve stimulation. Results The frontal N30 component was accompanied by a significant phase-locking of beta/gamma oscillation (25–35 Hz and to a lesser extent of 80 Hz oscillation. After the selection in each subject of the trials for which the power spectrum amplitude remained unchanged, we found pure phase-locking of beta/gamma oscillation (25–35 Hz peaking about 30 ms after the stimulation. Transition across trials from uniform to normal phase distribution revealed temporal phase reorganization of ongoing 30 Hz EEG oscillations in relation to stimulation. In a proportion of trials, this phase-locking was accompanied by a spectral power increase peaking in the 30 Hz frequency band. This corresponds to the complex situation of 'phase-locking with enhancement' in which the distinction between the contribution of phasic neural event versus EEG phase resetting is hazardous. Conclusion The identification of a pure phase-locking in a large proportion of the SEP trials reinforces the contribution of the oscillatory model for the physiological correlates of the frontal N30. This may imply that ongoing EEG rhythms, such as beta/gamma oscillation, are involved in somatosensory information processing.

  10. Observation of X-ray and Auger electron spectra in a 4π proportional counter for 4π(e, X)–γ coincidence measurements

    International Nuclear Information System (INIS)

    For the standardization of electron capture nuclides followed by γ-transitions, the 4π(e, X)–γ coincidence counting method is mainly adopted. To examine how the spectra of the (e, X) channel change with gas nature and pressure, pulse-height spectrum measurements of signals from a 4π pressurized proportional counter were carried out under various conditions for 54Mn and 88Y sources together with 4π(e, X)–γ coincidence counting. The spectra were measured for each half of the counter and for the combined 4π signal. The nature of counting gas (P-10 or methane) and its pressure was reflected in the X-ray peak intensity, and the Auger electron spectra were influenced significantly by the absorption in a thin VYNS film and the source conditions. In the measurements, we employed a pill-box type 4π counter in which the anodes were very thin gold-coated tungsten wires (30 μm ∅). In this system, spectra down to 0.2 keV were clearly seen. The gas pressure can be raised up to 0.6 MPa. Counting electronics used for 4π(e, X)–γ coincidence measurements were conventional modules and a list mode two-parameter data acquisition system. - Highlights: • Spectra of 54Mn and 88Y in a 4π proportional counter measured under various conditions. • Spectra due to X-rays and Auger electrons were clearly seen down to 0.2 keV. • Pulse spectra measured from each half of 4π counter (with P-10 gas or methane). • 4π(e, X)–γ coincidence measurements were also carried out

  11. INGAS: Iranian Noble Gas Analyzing System for radioxenon measurement

    Science.gov (United States)

    Doost-Mohammadi, V.; Afarideh, H.; Etaati, G. R.; Safari, M. J.; Rouhi, H.

    2016-03-01

    In this article, Iranian Noble Gas Analyzing System (INGAS) will be introduced. This system is based on beta-gamma coincidence technique and consists of a well-type NaI(Tl) as gamma or X radiation detector and a cylindrical plastic scintillator to detect beta or conversion electron. Standard NIM modules were utilized to detect coincidence events of detectors. Both the beta and gamma detectors were appropriately calibrated. The efficiency curve of gamma detector for volume geometry was obtained by comparing the results of gamma point sources measurements and simulations of GATE V7.0 Monte Carlo code. The performance of detection system was checked by injection of 222Rn and 131mXe gaseous source in the detection cell. The minimum detectable activity of the system for 133Xe is 1.240±0.024 mBq for 24 h measurement time.

  12. Absolute activity measurement of the electron-capture-based radionuclides 139Ce, 125I, 192Ir and 65Zn by liquid scintillation coincidence counting

    International Nuclear Information System (INIS)

    Four radionuclides with electron-capture-based decay schemes have been directly measured by a liquid scintillation coincidence extrapolation technique. 125I, 192Ir and 65Zn were measured as part of international key comparisons held under the auspices of the International Bureau of Weights and Measures (BIPM). The 139Ce measurements formed part of a regional comparison organized by the Asia Pacific Metrology Programme (APMP). Since 139Ce decays purely by electron-capture, the basic method is described for this radionuclide. Results and difficulties encountered are discussed and uncertainty budgets are presented

  13. Improvements in the Monte Carlo code for simulating 4πβ(PC)–γ coincidence system measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dias, M.S., E-mail: msdias@ipen.br [Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, Av. Prof. Lineu Prestes 2242, 05508-000 São Paulo, SP (Brazil); Takeda, M.N. [Universidade Santo Amaro, UNISA Rua Prof. Enéas da Siqueira Neto 340, 04829-300 São Paulo, SP (Brazil); Toledo, F.; Brancaccio, F.; Tongu, M.L.O.; Koskinas, M.F. [Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, Av. Prof. Lineu Prestes 2242, 05508-000 São Paulo, SP (Brazil)

    2013-01-11

    A Monte Carlo simulation code known as ESQUEMA has been developed by the Nuclear Metrology Laboratory (Laboratório de Metrologia Nuclear—LMN) in the Nuclear and Energy Research Institute (Instituto de Pesquisas Energéticas e Nucleares—IPEN) to be used as a benchmark for radionuclide standardization. The early version of this code simulated only β−γ and ec−γ emitters with reasonably high electron and X-ray energies. To extend the code to include other radionuclides and enable the code to be applied to software coincidence counting systems, several improvements have been made and are presented in this work. -- Highlights: ► Improvements to the Monte Carlo code ESQUEMA are described. ► The experimental extrapolation curve was compared to Monte Carlo simulation. ► Eu-152 was standardized by 4π(PC)β-γ coincidence system and compared to Monte Carlo simulation. ► 4π proportional counter gamma-ray efficiency was calculated by MCNPX and compared with experiment. ► X-ray and positron decay emitters were included in the simulation.

  14. Absolute measurements of the thermal neutron flux by the foil activation method using the 4πβ-γ coincidence technique

    International Nuclear Information System (INIS)

    An analysis of the correction factors required for the β-γ coincidence method is presented together with a listing of the various formulae involved in the determination of radioactive sources. The detection system including the activation detectores are described and the results are shown for the absolute measurements of thermal neutron flux carried out in the core of the Argonaut Reactor, at Instituto de Engenharia Nuclear (IEN), Brazil. (Author)

  15. Advanced Time-Delayed Coincidence Studies of $^{31,32}$Mg from the $\\beta$-decays of $^{31,32}$Na

    CERN Multimedia

    Marechal, F; Plociennik, W A

    2002-01-01

    It is proposed to study the lifetime of the 2$_{1}^{+}$ 885.4 keV state in $^{32}$Mg by means of Advanced Time-Delayed $\\beta \\gamma \\gamma$(t) method with the precision in the half-life value of about $\\pm$ 1.5 ps. This would be an independent verification of the B(E2; 0$_{1}^{+} \\rightarrow$ 2$_{1}^{+}$) values obtained so far in a few studies using Coulomb excitations at intermediate beam energies. The advantage of time-delayed coincidence measurements is that they are free of corrections used in the Coulex studies, which strongly affect the deduced B(E2) results. In addition, we propose to study the lifetimes or lifetime limits of other states in nuclei populated in the decays of $^{31}$Na and $^{32}$Na, specifically focusing on the intruder negative parity band in $^{31}$Mg. As a side benefit to this investigation we expect high-quality $\\gamma \\gamma$ coincidences to reveal new excited states in both $^{31}$Mg and $^{32}$Mg. Our results from a brief test-measurement yield a lifetime of T$_{1/2}$ = 10.5(...

  16. Measurement of disintegration rate and decay branching ratio for nuclide 192Ir with β-, EC mixing decays by using 4πβ-γ coincidence counting

    International Nuclear Information System (INIS)

    The absolute disintegration rates for nuclide 192Ir were measured with a 4πβ-γ (HPGe) coincidence apparatus by using parameter method and extrapolation method. The final uncertainties obtained were 0.4% and 0.5% respectively for a confidence level of 99.7%. The method with which both the disintegration rate and the decay branching ratio can be measured for nuclides with β- and EC mixing decays was proposed and described. The β- branching ratio in 192Ir decays was measured being 0.9572. The final uncertainties of disintegration rates and β- decay branching ratio with this method were 1.5% and 1.8% respectively

  17. The influence of partial volume effect on the measurement of lesion to background ratio in standard SPECT and coincidence circuit SPECT: a phantom study

    International Nuclear Information System (INIS)

    Objective: Partial volume effect is known to cause incorrect estimation of radiopharmaceutical uptake. The aim of this study was to evaluate the influence of partial volume effect on the measurement of lesion to background ratio (L/B) in standard SPECT and coincidence circuit SPECT. Methods: Using a simplified Jaszczak phantom containing 6 cylinders to simulate lesions with diameters of 2.8, 1.8, 1.3, 0.8, 0.8 and 0.8 cm, standard SPECT with 99TcmO4- and coincidence SPECT with 18F-fluorodeoxyglucose (FDG) studies were performed. The average background counts and three types of L/B values were measured, namely L/B1 for maximal counts ratio; L/B2 for the average counts ratio with the size of region of interest (ROI) equal to the lesion; and L/B3 for the average counts ratio of 6 pixels size in ROI. The L/B ratios were compared with the contrasts. SPSS 11.0 was used to calculate Paiied Student's t test, linear correlation and regression. Results: When the contrast was set to 2:1 in standard SPECT and 2:1 or 2.5:1 in coincidence SPECT, the lesions with 0.8 cm in diameter could not be detected. Except for the le- sion with 2.8 cm in diameter in coincidence SPECT, the L/B values were all significantly underestimated and there was strong positive correlation between the L/B values and the contrasts. The smaller the lesion size, the greater was the underestimation of the L/B values. The regression equations were Y2 a = 0. 086 + 0.689 Xcontrast, Y1.8=0.350 +0.436 Xcontrast, Y13=0.837+0.307 Xcontrast, Y0.8=0.564 +0.199 Xcontrast for standard SPECT series, and Y2.8=0.221 + 0.941 Xcontrast Y1.8=0.426+0.647 Xcontrast Y1.3=0.484 + 0.528 Xcontrast Y0.8=0.429+0.318 Xcontrast for coincidence SPECT series. The L/B values using the maxi- mum lesion radioactivity counts had the best results. Conclusions: Significant partial volume effects on L/B ratios were detected in SPECT and coincidence SPECT, particularly the former. Calibration by regression equation using the maximum L/B value

  18. Double coincidence matrix

    International Nuclear Information System (INIS)

    To increase the accuracy of discrimination of true coincidences against the background of accidental ones, circuit has been developed which operates on the principle of dynamic equalization of resolution times of two coincidence circuits. The flowsheet of a 4x6 double-coincidence matrix is given. The principal elements of the matrix are commutators and output signal shapers. The matrix uses 138-series microcircuits. The resolution time of coincidence circuits is 10 ns, the dead time is 25 ns. The results of testing the matrix during experiments under conditions of a high background of accidental coincidences (70-90%) have shown that the accuracy of discrimination of true coincidences with the help of the double-coincidence matrix approximates the accuracy of time-to-digital converters within the limits of the statistical accuracy

  19. Coincidence and modality

    OpenAIRE

    Kang, Li

    2011-01-01

    How should we understand de re modal features of objects, if there are such features? Any answer to the question is connected to how we should think about coincident objects, objects which occupy the same spatio-temporal region and share the same underlying matter. This thesis is mainly about the connections between de re modality and coincidence. My interest in the connections is twofold: First, how do theories of de re modality interact with theories about coincidence? Details of interactio...

  20. Standardization of electron-capture and complex beta-gamma radionuclides by the efficiency extrapolation method

    International Nuclear Information System (INIS)

    The efficiency extrapolation method was improved by establishing ''linearity conditions'' for the discrimination on the gamma channel of the coincidence equipment. These conditions were proved to eliminate the systematic error of the method. A control procedure for the fulfilment of linearity conditions and estimation of residual systematic error was given. For law-energy gamma transitions an ''equivalent scheme principle'' was established, which allow for a correct application of the method. Solutions of Cs-134, Co-57, Ba-133 and Zn-65 were standardized with an ''effective standard deviation'' of 0.3-0.7 per cent. For Zn-65 ''special linearity conditions'' were applied. (author)

  1. Absolute measurement of the desintegration rate of 137 Cs by 4Π (BS) e--X coincidence method

    International Nuclear Information System (INIS)

    The method developed by the Nuclear Metrology Laboratory for the absolute measurement of the desintegration rate of 137Cs by 4Π(BS)e--X is described. The conversion electron are measured by a pair of surface barrier detectors with 200mm2 of active area and 1000μm of depletion depth. The X-rays are measured by two 50.8mm diameter and 1.0mm thick NaI (Tl) scintillation counters. (author)

  2. Validation of ACE-FTS satellite data in the upper troposphere/lower stratosphere (UTLS) using non-coincident measurements

    OpenAIRE

    Hegglin, M. I.; Bernath, P. F.; C. D. Boone; W. H. Daffer; Hoor, P.; Manney, G. L.; Schiller, C.; Strong, K.; K. A. Walker

    2008-01-01

    CO, O3, and H2O data in the upper troposphere/lower stratosphere (UTLS) measured by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) on Canada's SCISAT-1 satellite are validated using aircraft and ozonesonde measurements. In the UTLS, validation of chemical trace gas measurements is a challenging task due to small-scale variability in the tracer fields, strong gradients of the tracers across the tropopause, and sc...

  3. Neutron Multiplicity And Active Well Neutron Coincidence Verification Measurements Performed For March 2009 Semi-Annual DOE Inventory

    International Nuclear Information System (INIS)

    The Analytical Development (AD) Section field nuclear measurement group performed six 'best available technique' verification measurements to satisfy a DOE requirement instituted for the March 2009 semi-annual inventory. The requirement of (1) yielded the need for SRNL Research Operations Department Material Control and Accountability (MC and A) group to measure the Pu content of five items and the highly enrich uranium (HEU) content of two. No 14Q-qualified measurement equipment was available to satisfy the requirement. The AD field nuclear group has routinely performed the required Confirmatory Measurements for the semi-annual inventories for fifteen years using sodium iodide and high purity germanium (HpGe) γ-ray pulse height analysis nondestructive assay (NDA) instruments. With appropriate γ-ray acquisition modeling, the HpGe spectrometers can be used to perform verification-type quantitative assay for Pu-isotopics and HEU content. The AD nuclear NDA group is widely experienced with this type of measurement and reports content for these species in requested process control, MC and A booking, and holdup measurements assays Site-wide. However none of the AD HpGe γ-ray spectrometers have been 14Q-qualified, and the requirement of reference 1 specifically excluded a γ-ray PHA measurement from those it would accept for the required verification measurements. The requirement of reference 1 was a new requirement for which the Savannah River National Laboratory (SRNL) Research Operations Department (ROD) MC and A group was unprepared. The criteria for exemption from verification were: (1) isotope content below 50 grams; (2) intrinsically tamper indicating or TID sealed items which contain a Category IV quantity of material; (3) assembled components; and (4) laboratory samples. Therefore all (SRNL) Material Balance Area (MBA) items with greater than 50 grams total Pu or greater than 50 grams HEU were subject to a verification measurement. The pass/fail criteria of

  4. Activity measurements and gamma emission intensities determination in the decay of Zn{sup 65}; Mesure de l'activite et des intensites des emissions gamma lors de la decroissance du Zn{sup 65}

    Energy Technology Data Exchange (ETDEWEB)

    Be, M.M.; Amiot, M.N.; Bobin, C.; Lepy, M.C.; Plagnard, J.; Lee, J.M.; Lee, K.B.; Park, T.S.; Luca, A.; Sahagia, M.; Razdolescu, A.M.; Grigorescu, L.; Sato, Y.; Hino, Y.; Kossert, K.; Klein, R.; Schneider, M.H.K.; Schrader, H.; Dryak, P.; Sochorova, J.; Kovar, P.; Auerbach, P.; Havelka, M.; Altzitzoglou, T.; Iwahara, A.; Da Silva, M.A.L.; Delgado, J.U.; Da Silva, C.J.; Johansson, L.; Collins, S.; Stroak, A

    2005-07-01

    Over the last twenty years, a number of laboratories have participated to the Systeme International de Reference (SIR BIPM) and it appeared that the mass activity of {sup 65}Zn determined by the gamma-ray spectrometry was less by about 2% than the one determined by using 4{pi}{beta}-{gamma} coincidence counting. An international exercise EUROMET, action 721, was organized with the objective of improving the knowledge of decay data in the {sup 65}Zn disintegration. Nine laboratories participated, sending results for the activity measurement and the 1115 keV gamma emission intensity. For the activity measurement, the participants used the 4{pi}{beta}-{gamma} coincidence method mainly, resulting values and uncertainty budgets are described. From the new gamma emission intensities measured in this exercise and, taking into account previous published values, the intensity of the 1115 keV gamma emission has been determined being equal to: 50.22 (11) %. This new value must lead to derive activity values higher than those previously obtained, reducing the difference, with other techniques of measurement, to 1 %. Moreover, the uncertainty on the emission intensity value has been divided by a factor of two. (authors)

  5. Observations of Bathymetry-Induced Ocean Roughness Modulation in In-situ Surface Slope Measurements and Coincident Airborne SAR Images

    NARCIS (Netherlands)

    Gommenginger, C.P.; Robinson, I.S.; Willoughby, J.; Greidanus, H.S.F.; Taylor, V.

    1999-01-01

    Empirical results from a field experiment in the southern North Sea have demonstrated the possibility to detect bathymetry-induced sea surface roughness modulation in the coastal zone using high frequency in-situ slope measurements provided by the Towed Laser Slopemeter. A strong correlation between

  6. Performance of a compact multi-crystal high-purity germanium detector array for measuring coincident gamma-ray emissions

    International Nuclear Information System (INIS)

    The Multi-sensor Airborne Radiation Survey (MARS) detector is a 14-crystal array of high-purity germanium (HPGe) detectors housed in a single cryostat. The array was used to measure the astrophysical S-factor for the 14N(p,γ)15O⁎ reaction for several transition energies at an effective center-of-mass energy of 163 keV. Owing to the granular nature of the MARS detector, the effect of gamma-ray summing was greatly reduced in comparison to past experiments which utilized large, single-crystal detectors. The new S-factor values agree within their uncertainties with the past measurements. Details of the analysis and detector performance are presented

  7. Performance of a compact multi-crystal high-purity germanium detector array for measuring coincident gamma-ray emissions

    Energy Technology Data Exchange (ETDEWEB)

    Howard, Chris; Daigle, Stephen; Buckner, Matt [University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Erikson, Luke E.; Runkle, Robert C. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Stave, Sean C., E-mail: Sean.Stave@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Champagne, Arthur E.; Cooper, Andrew; Downen, Lori [University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Glasgow, Brian D. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Kelly, Keegan; Sallaska, Anne [University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States)

    2015-05-21

    The Multi-sensor Airborne Radiation Survey (MARS) detector is a 14-crystal array of high-purity germanium (HPGe) detectors housed in a single cryostat. The array was used to measure the astrophysical S-factor for the {sup 14}N(p,γ){sup 15}O{sup ⁎} reaction for several transition energies at an effective center-of-mass energy of 163 keV. Owing to the granular nature of the MARS detector, the effect of gamma-ray summing was greatly reduced in comparison to past experiments which utilized large, single-crystal detectors. The new S-factor values agree within their uncertainties with the past measurements. Details of the analysis and detector performance are presented.

  8. Effect of double false pulses in calibrated neutron coincidence collar during measuring time-correlated neutrons from PuBe neutron sources

    International Nuclear Information System (INIS)

    Effect of double false pulses of preamplifiers in neutron coincidence collar was investigated to explain non-parallel shape of calibrated D/S–MPu curves of two commercial neutron coincidence collars, JCC-31 and JCC-13. Two curves, which were constructed from D/S ratio (doubles and singles count rate), and Pu content MPu, of the same set of secondary standard PuBe neutron sources, should be parallel. Non-parallelism rises doubt about usability of the method based on this curve for determination of Pu content in PuBe neutron sources. We have shown in three steps that the problem originates from double false pulses of preamplifiers in JCC-13. First we used a pulse train diagram for analyzing the non-parallel shape, second we used Rossi-Alpha distribution measured by pulse train recorder developed in our institute and finally, we investigated the effect of inserted noise pulses. This implies a new type of QA test option in traditional multiplicity shift registers for excluding presence of double false pulses

  9. Effect of double false pulses in calibrated neutron coincidence collar during measuring time-correlated neutrons from PuBe neutron sources

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Tam Cong, E-mail: tam.nguyen.cong@energia.mta.hu; Huszti, Jozsef; Nguyen, Quan Van

    2015-09-01

    Effect of double false pulses of preamplifiers in neutron coincidence collar was investigated to explain non-parallel shape of calibrated D/S–M{sub Pu} curves of two commercial neutron coincidence collars, JCC-31 and JCC-13. Two curves, which were constructed from D/S ratio (doubles and singles count rate), and Pu content M{sub Pu}, of the same set of secondary standard PuBe neutron sources, should be parallel. Non-parallelism rises doubt about usability of the method based on this curve for determination of Pu content in PuBe neutron sources. We have shown in three steps that the problem originates from double false pulses of preamplifiers in JCC-13. First we used a pulse train diagram for analyzing the non-parallel shape, second we used Rossi-Alpha distribution measured by pulse train recorder developed in our institute and finally, we investigated the effect of inserted noise pulses. This implies a new type of QA test option in traditional multiplicity shift registers for excluding presence of double false pulses.

  10. Imaging with coincidence detectors

    International Nuclear Information System (INIS)

    The development of a dual-detector, single photon emission computed tomography (SPECT) system that could be modified to perform coincidence imaging of positron-emitting radiotracers has resulted in a renaissance in the nuclear medicine community. In 1996, ADAC Laboratories introduced their Molecula Coincidence Detection (MCD) system at the Society of Nuclear Medicine Annual General Meeting in Denver. This ushered in a new era in nuclear medicine imaging. The ability of these coincidence systems to image 18FDG promises to make this type of imaging 'just another nuclear medicine procedure', possible within the next decade. This advancement is arguably the biggest news in nuclear medicine since the development of SPECT. In August 1997, Lion's Gate Hospital in North Vancouver acquired the MCD upgrade to their ADAC Vertex camera - the first and only to date in Canada. This article introduces coincidence imaging and describes the experiences of those pioneering the use of this new modality in Canada

  11. Surface underground coincidences at the Soudan mine

    International Nuclear Information System (INIS)

    A 37 m2 surface array which has been operating in coincidence with the Soudan 1 underground experiment is described. A comparison is made between measured and expected underground-surface coincident events. The surface array is used to ''tag'' the energy of the cosmic ray primary. Distributions of event rates and multiple muon rates as a function of energy are shown. Expected rates and plans for an enhanced array and for coincidences with Soudan 2 are also discussed. 1 ref., 6 figs

  12. Coincident measurements of PMSE and NLC above ALOMAR (69° N, 16° E by radar and lidar from 1999–2008

    Directory of Open Access Journals (Sweden)

    N. Kaifler

    2010-10-01

    Full Text Available Polar Mesosphere Summer Echoes (PMSE and Noctilucent Clouds (NLC have been routinely measured at the ALOMAR research facility in Northern Norway (69° N, 16° E by lidar and radar, respectively. 2900 h of lidar measurements by the ALOMAR Rayleigh/Mie/Raman lidar were combined with almost 18 000 h of radar measurements by the ALWIN VHF radar, all taken during the years 1999 to 2008, to study simultaneous and common-volume observations of both phenomena. PMSE and NLC are known from both theory and observations to be positively linked. We quantify the occurrences of PMSE and/or NLC and relations in altitude, especially with respect to the lower layer boundaries. The PMSE occurrence rate is with 75.3% considerably higher than the NLC occurrence rate of 19.5%. For overlapping PMSE and NLC observations, we confirm the coincidence of the lower boundaries and find a standard deviation of 1.26 km, hinting at very fast sublimation rates. However, 10.1% of all NLC measurements occur without accompanying PMSE. Comparison of occurrence rates with solar zenith angle reveals that NLC without PMSE mostly occur around midnight indicating that the ice particles were invisible to the radar due to the reduced electron density.

  13. Characterizing the detector response and testing the performance of a new well counter for neutron coincidence measurements of plutonium in residues

    International Nuclear Information System (INIS)

    A thermal neutron detector has been developed that integrates the neutron capture medium (6LiF) and scintillator (ZnS) into a thin screen, which is coupled to wavelength shifting fiber-optic ribbon. The 6LiF and ZnS powders are incorporated in a hydrogenous binder. The detector is constructed of alternating layers of the capture/scintillator screen and the fiber-optic ribbon. The scintillation light produced in the ZnS is absorbed and reemitted in the fibers and is transported to photomultiplier tubes (PMTs). The detector is sensitive to gamrna radiation, but the difference in the pulse decay times of gamma-ray and neutron events allows for discrimination using pulse shape analysis (PSA). To determine the feasibility of using PSA with this detector, a number of intrinsic characteristics of the detector have been measured; specifically, the number of photoelectrons produced at the photocathode of the PMT from the average neutron capture event in the screen and the temperature stability of the detector with respect to pulse shape. The number of photons that reach the PMTs was measured with two different PMTs. One was a typical PMT with single-photoelectron resolution, and the other was a Hybrid PMT comprised of a photocathode coupled to a PIN diode with few-photoelectron resolution. The number of photons that reach the PMTs is between 1600 and 2200, which is sufficient for PSA. The sensitivity of pulse shape to temperature has also been evaluated. Although the pulse decay time changes with varying temperature between -25 to +50 C, the normalized detector pulses have approximately the same amplitude around 400 ns. This results in a stable zero-crossing time of the 400-ns delay-line shaped pulse, and thus the PSA is independent of temperature. A four-sided prototype well counter has been built, It has a short neutron die-away time (τ 240Pu by neutron coincidence counting. Because of the high α,n-neutron yields in pyrochemical residues, greater sensitivity is required

  14. Coincident linkage of type 2 diabetes, metabolic syndrome, and measures of cardiovascular disease in a genome scan of the diabetes heart study.

    Science.gov (United States)

    Bowden, Donald W; Rudock, Megan; Ziegler, Julie; Lehtinen, Allison B; Xu, Jianzhao; Wagenknecht, Lynne E; Herrington, David; Rich, Stephen S; Freedman, Barry I; Carr, J Jeffrey; Langefeld, Carl D

    2006-07-01

    Cardiovascular disease (CVD) is a major contributor to morbidity and mortality in type 2 diabetes, but the relationship between CVD and type 2 diabetes is not well understood. The Diabetes Heart Study is a study of type 2 diabetes-enriched families extensively phenotyped for measures of CVD, type 2 diabetes, and metabolic syndrome. A total of 977 Caucasian subjects from 358 pedigrees (575 type 2 diabetic relative pairs) with at least two individuals with type 2 diabetes and, where possible, unaffected siblings were included in a genome scan. Qualitative traits evaluated in this analysis are with or without the presence of coronary calcified plaque (CCP) and with or without carotid calcified plaque (CarCP) measured by electrocardiogram-gated helical computed tomography. In addition, prevalent CVD was measured using two definitions: CVD1, based on self-reported history of clinical CVD (393 subjects), and CVD2, defined as CVD1 and/or CCP >400 (606 subjects). These discrete traits (type 2 diabetes, metabolic syndrome, CVD1, CVD2, CCP, and CarCP) frequently coincide in the same individuals with concordance ranging from 42.9 to 99%. Multipoint nonparametric linkage analysis revealed evidence for coincident mapping of each trait (type 2 diabetes, metabolic syndrome, CVD1, CVD2, CCP, and CarCP) to three different genomic regions: a broad region on chromosome 3 (70-160 cM; logarithm of odds [LOD] scores ranging between 1.15 and 2.71), chromosome 4q31 (peak LOD 146 cM; LOD scores ranging between 0.90 and 2.41), and on chromosome 14p (peak LOD 23 cM; LOD scores ranging between 1.43 and 2.31). Ordered subset analysis (OSA) suggests that the linked chromosome 3 region consists of at least two separate loci on 3p and 3q. In addition, OSA based on lipid measures and other traits identify family subsets with significantly stronger evidence of linkage (e.g., CVD2 on chromosome 3 at 87 cM subsetting on low HDL with an initial LOD of 2.19 is maximized to an LOD of 7.04 in a subset of

  15. A β - γ coincidence

    International Nuclear Information System (INIS)

    A β - γ coincidence method for absolute counting is given. The fundamental principles are revised and the experimental part is detailed. The results from 198 Au irradiated in the JEN 1 Swimming pool reactor are given. The maximal accuracy is 1 per cent. (Author) 11 refs

  16. Probing the decay characteristics of the Pygmy Dipole Resonance in the semi-magic nucleus 140Ce with γ-γ coincidence measurements

    International Nuclear Information System (INIS)

    This work presents the design and installation of a novel experimental setup - the γ3 setup - for measuring photon-induced nuclear dipole excitations in stable isotopes at the High Intensity γ-ray Source (HIγS) at the Duke University. The high energy resolution and high detection efficiency of the detector array, consisting of a combination of LaBr3:Ce and HPGe detectors, allows for the first time the efficient measurement of γ-γ-coincidences in combination with the method of nuclear resonance fluorescence. This technique provides access to the decay pattern of dipole excited states as an additional observable, which allows a deeper insight into the underlying structure of these excitations. The experimental setup has already been used successfully for two experimental campaigns in 2012 and 2013 in the investigation of 13 different target isotopes. Within the scope of this thesis the Pygmy Dipole Resonance (PDR) of 140Ce was studied in the excitation energy range from 5.2 MeV to 8.3 MeV based on data obtained with the γ3 setup. In particular the decay pattern of the states participating in the PDR was investigated. The experimental setup, the details of the analysis and the experimental results are presented in this thesis. A comparison of the results to theoretical quasi-particle phonon model (QPM) calculations allows for an interpretation of the observed decay behaviour.

  17. Precision measurement of sub-nanosecond lifetimes of excited nuclear states using fast-timing coincidences with LaBr3(Ce) detectors

    Science.gov (United States)

    Regan, P. H.

    2015-11-01

    Precision measurements of electromagnetic (EM) transition rates enable tests of models of internal nuclear structure. Measurements of transition rates can be used to infer the spin and parity differences between the initial and final discrete nuclear excited states via which the EM transition takes place. This short conference paper reports on developments of detection systems for the identification of discrete energy gamma-ray decays using arrays of halide-scintillation detectors acting in coincidence mode, which can be used to determine electromagnetic transition rates between excited nuclear states in the sub-nanosecond temporal regime. Ongoing development of a new multi-detector LaBr3(Ce) array for studies of exotic nuclei produced at the upcoming Facility for Anti-Proton and Ion Research (FAIR) as part of the NUSTAR-DESPEC project are presented, together with initial results from pre-NUSTAR implementations of this array for nuclear structure studies of neutron-rich fission fragment radionuclides at ILL-Grenoble, France and RIBF at RIKEN, Japan.

  18. Radiation protection in inhomogeneous beta-gamma fields and modelling of hand phantoms with MCNPX

    International Nuclear Information System (INIS)

    The usage of beta-radiation sources in various nuclear medicine therapies is increasing. Consequently, enhanced radiation protection measures are required, as medical staff more frequently handle high-activity sources required for therapy. Inhomogeneous radiation fields make it difficult to determine absorbed dose reliably. Routine monitoring with dosemeters does not guarantee any accurate determination of the local skin dose (LSD). In general, correction factors are used to correct for the measured dose and the maximum absorbed dose received. However, strong underestimations of the maximum exposure are possible depending on the individual handling the process and the reliability of dose measurements. Simulations can be used as a tool for a better understanding of the maximum possible exposure depending on the individual-related handling. While measurements reveal the overall dose during the entire irradiation time of the dosemeter, simulations help to analyse sequences of action. Hence, simulations allow for tracking the points of highest absorbed dose received during the handling process. In this respect, simulations were performed using the MCNPX software. In order to investigate the LSD, two hand phantoms were used, a model based on geometrical elements and a voxel hand. A typical situation of radio-synoviorthesis, i.e. handling a syringe filled with 90Y, was simulated. The results of the simulations show that the annual dose limit may be exceeded within minutes at the position of maximum absorbed dose received and that finger-ring dosemeters measure significantly different doses depending on their wearing position. It is of essential importance to wear the dosemeter properly and to use suitable correction factors with respect to the individual. Simulations are a suitable tool for ensuring reliable dose determination and may help to derive recommendations regarding radiation protection measures. (authors)

  19. One year of CNR-IMAA multi-wavelength Raman lidar measurements in coincidence with CALIPSO overpasses: Level 1 products comparison

    Directory of Open Access Journals (Sweden)

    L. Mona

    2009-09-01

    Full Text Available At CNR-IMAA, an aerosol lidar system has operated since May 2000 in the framework of EARLINET (European Aerosol Research Lidar Network, the first lidar network for tropospheric aerosol study on a continental scale. High quality multi-wavelength measurements make this system a reference point for the validation of data products provided by CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations, the first satellite-borne lidar specifically designed for aerosol and cloud study. Since 14 June 2006, dedicated measurements have been performed at CNR-IMAA in coincidence with CALIPSO overpasses. For the first time, results on 1-year comparisons between ground-based multi-wavelength Raman lidar measurements and corresponding CALIPSO lidar Level 1 profiles are presented. A methodology for the comparison is presented and discussed in detail. Night-time cases are considered to take advantage from Raman capability of the ground based lidar. Cases with the detection of cirrus clouds in CALIPSO data are separately analysed for taking into account multiple scattering effects. For cirrus cloud cases, few cases are available to draw any conclusions. For clear sky conditions, the comparison shows good performances of the CALIPSO on-board lidar: the mean relative difference between the ground-based and CALIPSO Level 1 measurements is always within its standard deviation at all altitudes, with a mean difference in the 3–8 km altitude range of (−2±12%. At altitude ranges corresponding to the typical PBL height observed at CNR-IMAA, a mean difference of (−24±20% is observed in CALIPSO data, probably due to the difference in the aerosol content at the location of PEARL and CALIPSO ground-track location. Finally, the mean differences are on average lower at all altitude ranges for the closest overpasses (at about 40 km respect to the 80-km overpasses.

  20. Measurement of the activity of the radiopharmaceuticals used in therapy

    Energy Technology Data Exchange (ETDEWEB)

    Sahagia, M.; Razdolescu, A.C.; Grigorescu, E.L.; Luca, A.; Ivan, C. [National Institute of R and D for Physics and Nuclear Engineering ' Horia Hulubei' IFIN-HH, POB MG-6, Bucharest (Romania)

    2006-07-01

    The paper presents the results obtained in the assurance of the whole traceability chain in the measurement of the activity for a particular group of radionuclides used as therapeutic pharmaceuticals: strong beta - weak gamma emitters, such as: 153 Sm, 177 Lu, 186 Re, 188 Re. The regulations regarding the uncertainty of the activity of therapy radiopharmaceuticals impose a maximum limit of 5%. All the above mentioned radionuclides belong to the group of triangular decay scheme and consequently they were standardized absolutely by the 4{pi}{beta}-{gamma} coincidence method. The solutions were then used for the calibration of the secondary standard, consisting from a 'Centronic I.G.12/20 A' ionization chamber. The calibration was transferred to the commercial radioisotope calibrators, as initial calibration figures. Some of these results are presented in the paper. (author)

  1. Use of multi-element TL dosimeters for beta and mixed beta/gamma personnel monitoring

    International Nuclear Information System (INIS)

    Applied experience as well as theoretical considerations make it clear that traditional two-element TL dosimeters are not adequate for use in personnel dosimetry involving beta radiation fields. The principal shortcoming of such dosimeters is that the TL element measuring the beta dose normally under responds, and the readings of such elements must be multiplied by a correction factor, called the beta factor, to obtain the dose. The beta factor, however, is not a constant but varies with variations in the beta spectrum incident on the dosimeter. Experimental tests carried out using a number of multi-element TL dosimeter designs have shown that the element readouts can be used in conjunction with a suitable algorithm to determine a suitable beta factor for use under a variety of irradiation conditions. The precision attainable in calculating the beta factor in this manner depends on a number of dosimeter design parameters and is often quite poor unless special care is exercised both in the design of the dosimeter and also in the operation of the readout system

  2. Decontamination Experiments on Intact Pig Skin Contaminated with Beta-Gamma- Emitting Nuclides

    International Nuclear Information System (INIS)

    A number of decontamination experiments have been performed on intact pig skin. In most of the experiments NaI-131 in water solution has been utilized because this nuclide is widely used within the Studsvik research establishment, is easy to detect and relatively harmless, and is practical to use in these experiments. Among the β γ-nuclides studied 1-131 has furthermore proved to be the one most difficult to remove from the skin. The following conclusions and recommendations regarding the decontamination of skin are therefore valid primarily for iodine in the form of Nal, but are probably also applicable to many other β γ-nuclides. a) A prolonged interval between contamination and decontamination has a negative effect on the result of the decontamination. Therefore start decontamination as soon as possible after the contamination. b) Soap and water has proved to be the most suitable decontamination agent. A number of other agents have appeared to be harmful to the skin. Therefore, first of all use only soap and water in connection with gentle rubbing. c) No clear connection between the temperature of the water for washing and the result of the decontamination has been demonstrated. d) Skin not degreased before the contamination seems to be somewhat easier to decontaminate than degreased skin, particularly if the activity has been on the skin for a long time. Therefore do not remove the sebum of the skin when engaged on radioactive work involving contamination risks. e) Irrigation of the contaminated surface with a solution containing the corresponding inactive ions or ordinary water in large quantities may considerably decrease the skin contamination. f) In radioactive work of long duration involving high risks of contamination prophylactic measures in the form of a protective substance ('invisible glove'), type Kerodex, may make decontamination easier

  3. Influence of nonstatistical variations on low-level measurements of 131I in milk

    International Nuclear Information System (INIS)

    The procedure described in the U. S. Atomic Energy Commission Regulatory Guide 4.3, which is intended to keep 131I levels in milk ''as low as practicable,'' does not properly account for all sources of analytical error that can occur in a low-level radiochemical procedure. Inaccurate chemical recovery factors due to large amounts of stable iodine in milk and incomplete evaluation of detector background fluctuations are the sources of largest error. Significant errors are also contributed in incorrect application of factors for protein-bound iodine and counting efficiency. Ambient levels of 131I contribute to difficulties in evaluating the local impact of any reactor. Use of a beta/gamma coincidence system for counting 131I, measurement of the stable iodine in milk samples and collection of control samples remote from any site are among the recommendations provided to ensure compliance with the Regulatory Guides

  4. Coincident photoelectron spectroscopy on superconductors

    International Nuclear Information System (INIS)

    Aim of the performed experiments of this thesis was to attempt to detect Cooper pairs as carriers of the superconducting current directly by means of the photoelectric effect. The method of the coincident photoelectron spectroscopy aims thereby at the detection of two coherently emitted electrons by the interaction with a photon. Because electrostatic analyzers typically cover only a very small spatial angle, which goes along with very low coincidence rates, in connection with this thesis a time-of-flight projection system has been developed, which maps nearly the whole spatial angle on a position-resolving detector. The pulsed light source in form of special synchrotron radiation necessary for the measurement has been adjusted so weak, that only single photons could arrive at the sample. Spectroscoped were beside test measurements on silver layers both a lead monocrystal as representative of the classical BCS superconductors and monocrystalline Bi2Sr2CaCu2O8 from the family of the high-temperature superconductors. With excitation energies up to 40 eV could be shown that sufficiently smooth and clean surfaces in the superconducting phase exhibit within the resolving power of about 0.5 eV no recognizable differences in comparison to the normally conducting phase. Beside these studies furthermore the simple photoemission at the different samples and especially in the case of the lead crystal is treated, because here no comparable results are known. Thereby the whole momentum space is discussed and the Fermi surface established as three-dimensional model, by means of which the measurement results are discussed. in the theoretical descriptions different models for the Cooper-pair production are presented, whereby to the momentum exchange with the crystal a special role is attributed, because this can only occur in direct excitations via discrete lattice vectors.

  5. Maximum information with minimum complexity from a coincidence assay system

    International Nuclear Information System (INIS)

    There are nuclear based assay situations where measurement of coincident radiation is possible and also appropriate because the coincidence requirement serves to decrease background and moreover may be particularly characteristic of the material being assayed. In these cases, besides the basic coincidence response, the coincidence system can be made to furnish additional useful information, to reduce the sensitivity of the measurement to detection efficiency, provide a continuous test of system performance, and in some instances, signal the presence of environmental noise or nuclear interferences. This paper discusses this coincidence system further. 3 refs., 1 fig

  6. A practical method for determining γ-ray full-energy peak efficiency considering coincidence-summing and self-absorption corrections for the measurement of environmental samples after the Fukushima reactor accident

    Science.gov (United States)

    Shizuma, Kiyoshi; Oba, Yurika; Takada, Momo

    2016-09-01

    A method for determining the γ-ray full-energy peak efficiency at positions close to three Ge detectors and at the well port of a well-type detector was developed for measuring environmental volume samples containing 137Cs, 134Cs and 40K. The efficiency was estimated by considering two correction factors: coincidence-summing and self-absorption corrections. The coincidence-summing correction for a cascade transition nuclide was estimated by an experimental method involving measuring a sample at the far and close positions of a detector. The derived coincidence-summing correction factors were compared with those of analytical and Monte Carlo simulation methods and good agreements were obtained. Differences in the matrix of the calibration source and the environmental sample resulted in an increase or decrease of the full-energy peak counts due to the self-absorption of γ-rays in the sample. The correction factor was derived as a function of the densities of several matrix materials. The present method was applied to the measurement of environmental samples and also low-level radioactivity measurements of water samples using the well-type detector.

  7. A thin 4πβ-counter operating by negative high voltage for the 4πβ-γ coincidence measurement

    International Nuclear Information System (INIS)

    A thin 4πβ-multiwire proportional counter was constructed to increase the γ-ray counting efficiency in the 4πβ-γ coincidence method. This counter with a counting volume of 70 x 60 x 11 mm and 5 wires in one half was made of an insulator and negative high voltage was supplied to the inner wall being possessed of conductivity. Then the anodes were operated at the earth potential and compact preamplifiers with no coupling condenser were fixed at the side of each half to miniaturize a shielding system for background. From the experimental results in various conditions, good characteristics were obtained in the case that signals were taken out from the center anode and the others were used only for cleaning up excess charges. (auth.)

  8. Calibration of the HB-line active well neutron coincidence counter for measure of LANL 3013 highly enriched uranium product splits

    International Nuclear Information System (INIS)

    In this paper, the setup, calibration, and testing of the F-Area Analytical Labs active well neutron coincidence counter (HV-221000-NDA-X-1-DKAWCC- 1) in SRNL are described for use in the Savannah River Site (SRS) transuranium metal production facility to enable assay of mixed uranium/plutonium metal product. The instrument was required within a three-month window for availability upon receipt of LANL uranium oxide samples into the SRS facility. Calibration of the instrument in the SRNL nuclear nondestructive assay facility in the range 10-400 g HEU is described. We also report qualification and installation of the instrument for assay of the initial suite of product samples. (author)

  9. Artifacts in digital coincidence timing.

    Science.gov (United States)

    Moses, W W; Peng, Q

    2014-11-01

    Digital methods are becoming increasingly popular for measuring time differences, and are the de facto standard in PET cameras. These methods usually include a master system clock and a (digital) arrival time estimate for each detector that is obtained by comparing the detector output signal to some reference portion of this clock (such as the rising edge). Time differences between detector signals are then obtained by subtracting the digitized estimates from a detector pair. A number of different methods can be used to generate the digitized arrival time of the detector output, such as sending a discriminator output into a time to digital converter (TDC) or digitizing the waveform and applying a more sophisticated algorithm to extract a timing estimator.All measurement methods are subject to error, and one generally wants to minimize these errors and so optimize the timing resolution. A common method for optimizing timing methods is to measure the coincidence timing resolution between two timing signals whose time difference should be constant (such as detecting gammas from positron annihilation) and selecting the method that minimizes the width of the distribution (i.e. the timing resolution). Unfortunately, a common form of error (a nonlinear transfer function) leads to artifacts that artificially narrow this resolution, which can lead to erroneous selection of the 'optimal' method. The purpose of this note is to demonstrate the origin of this artifact and suggest that caution should be used when optimizing time digitization systems solely on timing resolution minimization. PMID:25321885

  10. Artifacts in digital coincidence timing

    Science.gov (United States)

    Moses, W. W.; Peng, Q.

    2014-11-01

    Digital methods are becoming increasingly popular for measuring time differences, and are the de facto standard in PET cameras. These methods usually include a master system clock and a (digital) arrival time estimate for each detector that is obtained by comparing the detector output signal to some reference portion of this clock (such as the rising edge). Time differences between detector signals are then obtained by subtracting the digitized estimates from a detector pair. A number of different methods can be used to generate the digitized arrival time of the detector output, such as sending a discriminator output into a time to digital converter (TDC) or digitizing the waveform and applying a more sophisticated algorithm to extract a timing estimator. All measurement methods are subject to error, and one generally wants to minimize these errors and so optimize the timing resolution. A common method for optimizing timing methods is to measure the coincidence timing resolution between two timing signals whose time difference should be constant (such as detecting gammas from positron annihilation) and selecting the method that minimizes the width of the distribution (i.e. the timing resolution). Unfortunately, a common form of error (a nonlinear transfer function) leads to artifacts that artificially narrow this resolution, which can lead to erroneous selection of the ‘optimal’ method. The purpose of this note is to demonstrate the origin of this artifact and suggest that caution should be used when optimizing time digitization systems solely on timing resolution minimization.

  11. Special Analysis for the Disposal of the Lawrence Livermore National Laboratory Low Activity Beta/Gamma Sources Waste Stream at the Area 5 Radioactive Waste Management Site, Nevada National Security Site, Nye County, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Shott, Gregory J. [National Security Technologies, LLC

    2015-06-01

    This special analysis (SA) evaluates whether the Lawrence Livermore National Laboratory (LLNL) Low Activity Beta/Gamma Sources waste stream (BCLALADOEOSRP, Revision 0) is suitable for disposal by shallow land burial (SLB) at the Area 5 Radioactive Waste Management Site (RWMS) at the Nevada National Security Site (NNSS). The LLNL Low Activity Beta/Gamma Sources waste stream consists of sealed sources that are no longer needed. The LLNL Low Activity Beta/Gamma Sources waste stream required a special analysis because cobalt-60 (60Co), strontium-90 (90Sr), cesium-137 (137Cs), and radium-226 (226Ra) exceeded the NNSS Waste Acceptance Criteria (WAC) Action Levels (U.S. Department of Energy, National Nuclear Security Administration Nevada Field Office [NNSA/NFO] 2015). The results indicate that all performance objectives can be met with disposal of the LLNL Low Activity Beta/Gamma Sources in a SLB trench. The LLNL Low Activity Beta/Gamma Sources waste stream is suitable for disposal by SLB at the Area 5 RWMS. However, the activity concentration of 226Ra listed on the waste profile sheet significantly exceeds the action level. Approval of the waste profile sheet could potentially allow the disposal of high activity 226Ra sources. To ensure that the generator does not include large 226Ra sources in this waste stream without additional evaluation, a control is need on the maximum 226Ra inventory. A limit based on the generator’s estimate of the total 226Ra inventory is recommended. The waste stream is recommended for approval with the control that the total 226Ra inventory disposed shall not exceed 5.5E10 Bq (1.5 Ci).

  12. Mutation Rate Distribution Inferred from Coincident SNPs and Coincident Substitutions

    OpenAIRE

    Johnson, Philip L F; Hellmann, Ines

    2011-01-01

    Mutation rate variation has the potential to bias evolutionary inference, particularly when rates become much higher than the mean. We first confirm prior work that inferred the existence of cryptic, site-specific rate variation on the basis of coincident polymorphisms—sites that are segregating in both humans and chimpanzees. Then we extend this observation to a longer evolutionary timescale by identifying sites of coincident substitutions using four species. From these data, we develop anal...

  13. Kinematical coincidence method in transfer reactions

    Energy Technology Data Exchange (ETDEWEB)

    Acosta, L.; Amorini, F. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Auditore, L. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Berceanu, I. [Institute for Physics and Nuclear Engineering, Bucharest (Romania); Cardella, G., E-mail: cardella@ct.infn.it [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Chatterjiee, M.B. [Saha Institute for Nuclear Physics, Kolkata (India); De Filippo, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Francalanza, L.; Gianì, R. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); Grassi, L. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Rudjer Boskovic Institute, Zagreb (Croatia); Grzeszczuk, A. [Institut of Physics, University of Silesia, Katowice (Poland); La Guidara, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Lanzalone, G. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Facoltà di Ingegneria e Architettura, Università Kore, Enna (Italy); Lombardo, I. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Scienze Fisiche, Università Federico II and INFN Sezione di Napoli (Italy); Loria, D.; Minniti, T. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Pagano, E.V. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); and others

    2013-07-01

    A new method to extract high resolution angular distributions from kinematical coincidence measurements in binary reactions is presented. Kinematics is used to extract the center of mass angular distribution from the measured energy spectrum of light particles. Results obtained in the case of {sup 10}Be+p→{sup 9}Be+d reaction measured with the CHIMERA detector are shown. An angular resolution of few degrees in the center of mass is obtained. The range of applicability of the method is discussed.

  14. Kinematical coincidence method in transfer reactions

    CERN Document Server

    Acosta, L; Auditore, L; Berceanu, I; Cardella, G; Chatterjiee, M B; De Filippo, E; FrancalanzA, L; Gianì, R; Grassi, L; Grzeszczuk, A; La Guidara, E; Lanzalone, G; Lombardo, I; Loria, D; Minniti, T; Pagano, E V; Papa, M; Pirrone, S; Politi, G; Pop, A; Porto, F; Rizzo, F; Rosato, E; Russotto, P; Santoro, S; Trifirò, A; Trimarchi, M; Verde, G; Vigilante, M

    2012-01-01

    A new method to extract high resolution angular distributions from kinematical coincidence measurements in binary reactions is presented. Kinematic is used to extract the center of mass angular distribution from the measured energy spectrum of light particles. Results obtained in the case of 10Be+p-->9Be+d reaction measured with the CHIMERA detector are shown. An angular resolution of few degrees in the center of mass is obtained.

  15. COINCIDENCE PROBLEMS FOR GENERALIZED CONTRACTIONS

    Directory of Open Access Journals (Sweden)

    Jesús Garcia Falset

    2014-03-01

    Full Text Available In this paper, we establish some new existence, uniqueness and Ulam-Hyers stability theorems for coincidence problems for two single-valued mappings. The main results of this paper extend the results presented in {\\sc O. Mle\\c sni\\c te:} \\emph{Existence and Ulam-Hyers stability results for coincidence problems}, J. Nonlinear Sci.\\ Appl., \\textbf{6} (2013, 108--116. In the last section two examples of application of these results are also given.

  16. Absolute standardization of 106Ru by anti-coincidence method

    International Nuclear Information System (INIS)

    The system of absolute standardization activity of radionuclide by anti-coincidence counting and live-time techniques was implemented at LNMRI in 2008 to reduce the impacts of some influence factors in the determination of the activity with coincidence counting technique used for decades in the lab, for example, the measurement time. With the anti-coincidence system, the variety of radionuclides that can be calibrated by LNMRI was increased, in relation to the type of decay. The objective of this work is the standardization of 106Ru by the method of counting anti-coincidence and estimate its measurement uncertainties. (author)

  17. Bell's inequality and the coincidence-time loophole

    OpenAIRE

    Larssons, JA; Gill, RD Richard

    2003-01-01

    This paper analyzes effects of time-dependence in the Bell inequality. A generalized inequality is derived for the case when coincidence and non-coincidence [and hence whether or not a pair contributes to the actual data] is controlled by timing that depends on the detector settings. Needless to say, this inequality is violated by quantum mechanics and could be violated by experimental data provided that the loss of measurement pairs through failure of coincidence is small enough, but the qua...

  18. Comparison of CO2 retrievals from IASI-A, IASI-B and GOSAT in the thermal infrared for nearly coincident measurements over the Arctic ocean in summer

    Science.gov (United States)

    Camy-Peyret, Claude; Bureau, Jerome; Payan, Sebastien

    2015-04-01

    The capabilities to retrieve reliable information on the concentration of greenhouse gases in the lower atmosphere from thermal infrared (TIR) spectra collected by nadir sounders is still to be assessed. We have selected the two months period of July-August in the high latitude polar region where it is possible to observe almost coincident or superimposed footprints (IFOV) of the three infrared sounders considered in this study, namely IASI-A, IASI-B (on the MetOp platforms) and TANSO-FTS (on GOSAT). Retrievals of the column averaged mixing ratio of carbon dioxide XCO2 (and of the surface temperature) have been performed for three years i.e. 2010, 2013 and 2014 over Arctic waters. The summer period was chosen because ice free IFOVs (in the latitude band 68N to 82N) can be selected for which retrievals are less sensitive to surface inhomogeneity (as compared to IFOVs located over land). The emissivity of sea water is also better constrained. The inversion configuration (using the atmospheric window covering the so-called CO2 laser band in the interval 940-980 cm-1) will be described. The sensitivity of the retrieved XCO2 to the different layers of the lower atmosphere as a function of thermal contrast, temperature and humidity profiles will be presented. The precision/accuracy of the retrieved XCO2 will be discussed and compared between sounders. The CO2 trends is clearly captured over the years analysed in this work. The retrieved values will be compared to similar XCO2 products available from other sources (Leicester Univ., NIES, SRON/KIT). Some remaining spectroscopic issues in the vicinity of 948 cm-1 have been identified and circumvented. The retrieved sea surface temperature Tsurf used as a control variable is also providing an additional check of the performances of the retrievals and is compared to the Eumetsat IASI Tsurf product. These results are interesting starting points for preparing future missions like IASI-NG on MetOp-SG as well as GOSAT-2.

  19. Precise measurement of gamma-ray emission probabilities for 187W by using a two-dimensional 4πβ-γ coincidence system

    International Nuclear Information System (INIS)

    Gamma-ray emission probabilities for 187W have been determined with uncertainties less than 1% from measurement of absolute γ-ray intensities and disintegration rate. The measured emission probabilities are larger than those previously reported by about 20% and hence the β-ray branching ratio to the ground state has to be smaller than about 40%. The decay scheme of 187W calculated by using the present results is given as a final result. (author)

  20. Maximum information with minimum complexity from a coincidence assay system

    International Nuclear Information System (INIS)

    Nuclear assays based on coincidence measurements can yield more useful information than is usually derived from them. The additional information can be used to improve assay accuracy and reliability with only a modest increase in the complexity of the electronics. A particular three-channel coincidence system that has had practical application is analyzed as an example. (author)

  1. Absolute activity measurement and gamma-ray emission probability for decay of I-126; Medida absoluta da atividade e determinacao da taxa de emissao gama por decaimento do {sup 126} I

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, Katia Aparecida

    1997-07-01

    The accurate knowledge of the gamma-ray emission probability per decay of radionuclides is important in several applications. In the case of {sup 126} I, its importance lies mainly in fast neutron dosimetry as well as in the production of {sup 125} I where {sup 126} I appears as an impurity. In the present work the gamma-ray emission probabilities per decay for the 388 and 666-KeV transitions of {sup 126} I have been measured. This radionuclide was obtained by means of the {sup 127} I(n, 2n){sup 126} I reaction in a fast neutron flux at the IPEN 2 MW research reactor. The methodology for the primary standardization of {sup 126} I is described. For this purpose, two different coincidence systems were used due to the complex decay scheme of this radionuclide. The {beta}branch measurement was carried out in a 4 {pi}(PC){beta}-{gamma} coincidence system consisting of a proportional counter, coupled to a pair of 3'x3' Na I (Tl) crystal. The electron capture branch was measured in a X-{gamma} coincidence system using two NaI(Tl) crystals. The gamma-ray measurements were performed in a HPGe system, previously calibrated by means of standard sources supplied by the International Atomic Energy Agency. All the uncertainties evolved were treated rigorously, by means of covariance analysis. (author)

  2. Video Histories, Memories, and Coincidences

    DEFF Research Database (Denmark)

    Kacunko, Slavko

    2012-01-01

    Looping images allows us to notice things that we have never noticed before. Looping a small but exquisite selection of the video tapes of Marcel Odenbach, Dieter Kiessling and Matthias Neuenhofer may allow the discovering of Histories, Coincidences, and Infinitesimal Aesthetics inscribed into th...

  3. Electron-ion time-of-flight coincidence measurements of K-K electron-capture, cross sections for nitrogen, methane, ethylene, ethane, carbon dioxide, and argon (L-K) targets

    International Nuclear Information System (INIS)

    Protons with energies ranging from 0.4 to 2.0 MeV were used to measure K-shell vacancy production cross sections for N2, CH4, C2H4, C7H6, and CO2 gas targets under single collision conditions. An electron-ion time-of-light coincidence technique was used to determine the ratio of the K-K electron capture cross section to the K-vacancy production cross section. These ratios were then combined to extract the K-K electron capture cross sections. Measurements were also made for protons of the same energy range but with regard to L-shell vacancy production and L-K electron capture for Ar targets. In addition, K-K electron capture cross sections were measured for 1.0-2.0 MeV He+ ions on CH4. The agreement among the present measurements, previously published measurements, and the ECPSSR theory is excellent for protons incident on N2, Ar, and CH4. The present measurements do indicate that there is a molecular dependence for the carbon atom K-K electron capture cross sections

  4. Spectral shapes and a beta-gamma directional correlation in the beta decay of 172Tm (Jpi = 2-)

    DEFF Research Database (Denmark)

    Gregers Hansen, P.; Loft Nielsen, H.; Wilsky, K.; Agarwal, Y.K.; Baba, C. V. K.; Bhattaeherjee, S.K.

    1966-01-01

    defines parameters X and Y corresponding to the relative contributions of tensor ranks 0 and 1 respectively. The shape measurement provides the limit X2 + Y2 les 0.10, whereas the angular correlation measurement gives Y = 1.64X + (0.02 plusmn0.03). The reduced transition probabilities (f1t)-1 can......+(gamma)0+ cascade has been measured at six energies from 1010 to 1550 keV and these results too are consistent with the assumption that the 2- rarr 2+ beta transition is purely of tensor rank 2. The data for the 2- rarr 2+ transition are analysed on the basis of the modified Bij approximation, which...

  5. Radioactivity determination by coincidence counting

    International Nuclear Information System (INIS)

    The 4 π β-γ coincidence counting equipment used in the Lucas Heights radioisotope standards laboratory for international comparisons is described in detail. A radioactivity standard is a method rather than a material object; as such it can be specified clearly only by discussing fully the setting-up and operation of one particular set of equipment. This manual is written for persons who are setting up such equipment for the first time

  6. β-Arrestin interacts with the beta/gamma subunits of trimeric G-proteins and dishevelled in the Wnt/Ca(2+ pathway in xenopus gastrulation.

    Directory of Open Access Journals (Sweden)

    Katharina Seitz

    Full Text Available β-Catenin independent, non-canonical Wnt signaling pathways play a major role in the regulation of morphogenetic movements in vertebrates. The term non-canonical Wnt signaling comprises multiple, intracellularly divergent, Wnt-activated and β-Catenin independent signaling cascades including the Wnt/Planar Cell Polarity and the Wnt/Ca(2+ cascades. Wnt/Planar Cell Polarity and Wnt/Ca(2+ pathways share common effector proteins, including the Wnt ligand, Frizzled receptors and Dishevelled, with each other and with additional branches of Wnt signaling. Along with the aforementioned proteins, β-Arrestin has been identified as an essential effector protein in the Wnt/β-Catenin and the Wnt/Planar Cell Polarity pathway. Our results demonstrate that β-Arrestin is required in the Wnt/Ca(2+ signaling cascade upstream of Protein Kinase C (PKC and Ca(2+/Calmodulin-dependent Protein Kinase II (CamKII. We have further characterized the role of β-Arrestin in this branch of non-canonical Wnt signaling by knock-down and rescue experiments in Xenopus embryo explants and analyzed protein-protein interactions in 293T cells. Functional interaction of β-Arrestin, the β subunit of trimeric G-proteins and Dishevelled is required to induce PKC activation and membrane translocation. In Xenopus gastrulation, β-Arrestin function in Wnt/Ca(2+ signaling is essential for convergent extension movements. We further show that β-Arrestin physically interacts with the β subunit of trimeric G-proteins and Dishevelled, and that the interaction between β-Arrestin and Dishevelled is promoted by the beta/gamma subunits of trimeric G-proteins, indicating the formation of a multiprotein signaling complex.

  7. Absolute activity measurement and gamma-ray emission probability for decay of I-126

    CERN Document Server

    Fonseca, K A

    1997-01-01

    The accurate knowledge of the gamma-ray emission probability per decay of radionuclides is important in several applications. In the case of sup 1 sup 2 sup 6 I, its importance lies mainly in fast neutron dosimetry as well as in the production of sup 1 sup 2 sup 5 I where sup 1 sup 2 sup 6 I appears as an impurity. In the present work the gamma-ray emission probabilities per decay for the 388 and 666-KeV transitions of sup 1 sup 2 sup 6 I have been measured. This radionuclide was obtained by means of the sup 1 sup 2 sup 7 I(n, 2n) sup 1 sup 2 sup 6 I reaction in a fast neutron flux at the IPEN 2 MW research reactor. The methodology for the primary standardization of sup 1 sup 2 sup 6 I is described. For this purpose, two different coincidence systems were used due to the complex decay scheme of this radionuclide. The beta branch measurement was carried out in a 4 pi(PC)beta-gamma coincidence system consisting of a proportional counter, coupled to a pair of 3'x3' Na I (Tl) crystal. The electron capture branch ...

  8. Standardization of 18F by digital coincidence counting

    International Nuclear Information System (INIS)

    The radioactivity of 18F has been measured by a digital coincidence counting (DCC) system. The main advantages of the digital coincidence counting technique are a shortening of the measurement time as compared with conventional coincidence counting and an ability to obtain activities with various experimental parameters through off-line analysis. The measurement results of radioactivity for 18F solution were compared with those of a conventional coincidence counting technique and a reference ion chamber method. - Highlights: ► Radioactivity of F-18 is measured by a DCC technique. ► DCC technique has an advantage for the radionuclide with short half-life. ► Activity results show a good agreement with those of other methods.

  9. Conditioning of alpha and beta-gamma ashes of incinerator, obtained by radioactive wastes incinerating and encapsulation in several matrices

    International Nuclear Information System (INIS)

    In this final report, the work carried out, and the results, obtained on the ash incinerator conditioning study, by means of encapsulation in several matrices, are presented. Three encapsulation matrices were checked: - a ternary cement, containing OPC, blast furnace slag and flying ash, - a two component epoxide system, - an epoxide-cement compound matrix. Three ash categories were employed: - real alpha ash, coming from plutonium bearing wastes, - ash, from inactive combustible waste, obtained by treatment in an incinerator prototype, - ash coming from inactive waste incineration plant. Using three different matrices, the encapsulated form properties were determined: at the laboratory scale, the encapsulating formulation was established, and physico mechanical data were obtained, - on active encapsulated forms, containing a calculated amount of 238 Pu, a radiolysis study was performed in order to measure the composition and volume of the radiolytic gas flow, - at the industrial scale, a pilot plant operating the polyvalent encapsulating process, was designed and put into service. Bench-scale experiments were done, on alpha ash embedded forms using the modified sulphur cement matrix as embedding agent. 4 refs., 30 figs., 27 tabs

  10. Measurement of the sp ectral prop erties of the coincident-frequency entangled biphoton state at optical communication wavelength%通信波长频率一致纠缠光源的频谱测量

    Institute of Scientific and Technical Information of China (English)

    王盟盟; 权润爱; 邰朝阳; 侯飞雁; 刘涛; 张首刚; 董瑞芳

    2014-01-01

    The frequency entangled biphoton source generated via spontaneous parametric down-conversion (SPDC) process has found important applications in the fields of quantum clock synchronization, quantum communication, quantum information processing, etc. As quantum technologies evolve, quantitative characterization of the frequency entanglement becomes necessary and has been implemented by measuring the spectral properties of the biphoton state. However, due to the high dark rate and low quantum efficiency of the InGaAs single-photon detectors, direct measurement of the spectral properties of the biphoton state at optical communication wavelength is hard to implement. In this paper, we report the measurement of the spectral properties of a biphoton state at optical communication wavelength which is generated from periodically poled potassium titanyl phosphate (PPKTP) pumped by an ultra-short pulsed optical source at 787 nm. Based on the coincidence measurement setup together with two infrared spectrometers, the spectra of the signal and idler photons are obtained with their center wavelengths being 1574.4 nm and 1574.9 nm, while their 3-dB bandwidths being 35.3 nm and 37.6 nm respectively. The joint spectrum of the photon pair is observed as well and shows a coincident-frequency entanglement and a joint spectrum bandwidth of 3 nm. According to the ratio of the single-photon spectral bandwidth to the joint spectral bandwidth of the photon pairs, the degree of frequency entanglement is quantified to be 12, denoting a relatively high quality of the entanglement.%本文利用光栅单色仪实现了对超短脉冲抽运周期极化磷酸氧钛钾晶体产生的通信波长频率一致纠缠光子源的频谱特性分析.测量到双光子的联合频谱呈正关联分布,为频率一致纠缠光源.信号光、闲置光中心波长分别为1574.4 nm和1574.9 nm,频谱宽度分别为35.3 nm和37.6 nm,双光子符合包络宽度约为3 nm.根据单光子频谱宽度与双光

  11. Detection limit for activation measurements in ultralow background sites

    Science.gov (United States)

    Trache, Livius; Chesneanu, D.; Margineanu, R.; Pantelica, A.; Ghita, D. G.; Burducea, I.; Straticiuc, M.; Tang, X. D.

    2014-09-01

    We used 12C +13C fusion at the beam energies E = 6, 7 and 8 MeV to determine the sensitivity and the limits of activation method measurements in ultralow background sites. A 13C beam of 0.5 μA from the 3 MV Tandem accelerator of the Horia Hulubei National Institute of Physics and Nuclear Engineering - IFIN HH impinged on thick graphite targets. After about 24 hrs of irradiation targets were measured in two different laboratories: one with a heavy shielded Ge detector in the institute (at the surface) and one located underground in the microBequerel laboratory, in the salt mine of Slanic-Prahova, Romania. The 1369- and 2754 keV peaks from 24Na deactivation were clearly observed in the γ-ray spectra obtained for acquisitions lasting a few hours, or a few days. Determination of the detection limit in evaluating the cross sections for the target irradiated at Ec . m = 3 MeV indicates the fact that it is possible to measure gamma spectrum in underground laboratory down to Ec . m = 2 . 6 MeV. Cleaning the spectra with beta-gamma coincidences and increasing beam intensity 20 times will take as further down. The measurements are motivated by the study of the 12 C +12 C reaction at astrophysical energies.

  12. Realisation of a {beta} spectrometer solenoidal and a double {beta} spectrometer at coincidence; Realisation d'un spectrometre {beta} solenoidal et d'un double spectrometre {beta} a coincidence

    Energy Technology Data Exchange (ETDEWEB)

    Moreau, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1955-06-15

    The two spectrometers have been achieved to tackle numerous problems of nuclear spectrometry. They possess different fields of application that complete themselves. The solenoidal spectrometer permits the determination of the energy limits of {beta} spectra and of their shape; it also permits the determination of the coefficients of internal conversion and reports {alpha}{sub K} / {alpha}{sub L} and it is especially efficient for the accurate energy levels of the {gamma} rays by photoelectric effect. The double coincidence spectrometer has been conceived to get a good efficiency in coincidence: indeed, the sum of the solid angles used for the {beta} and {gamma} emission is rather little lower to 4{pi} steradians. To get this efficiency, one should have sacrificed a little the resolution that is lower to the one obtained with the solenoidal spectrometer for a same brightness. Each of the elements of the double spectrometer can also be adapted to the study of angular correlations {beta}{gamma} and e{sup -}{gamma}. In this use, it is superior to the thin magnetic lens used up to here. The double spectrometer also permits the survey of the coincidences e{sup -}e{sup -}, e{sup -}{beta} of a equivalent way to a double lens; it can also be consider some adaptation for the survey of the angular correlations e{sup -}e{sup -}, e{sup -}{beta}. Finally, we applied the methods by simple spectrometry and by coincidence spectrometry, to the study of the radiances of the following radioelements: {sup 76}As (26 h), {sup 122}Sb (2,8 j), {sup 124}Sb (60 j), {sup 125}Sb (2,7 years). (M.B.) [French] Les deux spectrometres qui ont ete realises permettent d'aborder un grand nombre de problemes de spectrometrie nucleaire. Ils possedent des champs d'application tres differents qui se completent. Le spectrometre solenoidal permet la determination des energies limites des spectres {beta} et de leur forme; il permet aussi la determination des coefficients de conversion interne et

  13. Combining attosecond XUV pulses with coincidence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sabbar, M., E-mail: msabbar@phys.ethz.ch; Heuser, S.; Boge, R.; Lucchini, M.; Cirelli, C.; Keller, U. [Department of Physics, ETH Zurich, 8093 Zurich (Switzerland); Gallmann, L. [Department of Physics, ETH Zurich, 8093 Zurich (Switzerland); Institute of Applied Physics, University of Bern, 3012 Bern (Switzerland)

    2014-10-15

    Here we present a successful combination of an attosecond beamline with a COLTRIMS apparatus, which we refer to as AttoCOLTRIMS. The setup provides either single attosecond pulses or attosecond pulse trains for extreme ultraviolet-infrared pump-probe experiments. We achieve full attosecond stability by using an active interferometer stabilization. The capability of the setup is demonstrated by means of two measurements, which lie at the heart of the COLTRIMS detector: firstly, we resolve the rotating electric field vector of an elliptically polarized few-cycle infrared laser field by attosecond streaking exploiting the access to the 3D momentum space of the charged particles. Secondly, we show streaking measurements on different atomic species obtained simultaneously in a single measurement making use of the advantage of measuring ions and electrons in coincidence. Both of these studies demonstrate the potential of the AttoCOLTRIMS for attosecond science.

  14. A coincidence counting system for detection of low level activities

    International Nuclear Information System (INIS)

    A system based on coincidence counting for measuring the absolute activity of isotopes in which a gamma ray is emitted by the nucleus following the capture of the orbital electron with a known half-life is described. If the half-life of the excited state is small compared to the resolving time of the coincidence circuit, the absolute activity of the source can be determined. The system consists of two NaI(Th) crystals, a high voltage supply, 2 preamplifiers, 2 amplifiers, two single channel analyzers, one coincident unit, and three sealers

  15. Miniature proportional counter for compression measurements of laser-fusion targets

    International Nuclear Information System (INIS)

    Direct drive laser fusion targets consisting of DT gas encapsulated in glass microshells produce 14.1 MeV neutrons that can interact with silicon-28 nuclei in the glass to produce a 2.2 minute aluminum-28 activity. From the number of 28Al nuclei created and the neutron yield, the compressed glass areal density can be found. To determine the number of activated atoms created, we collect approximately one-half of the target debris on a thin metal foil which is transferred to our beta-gamma coincidence detector. This detector consists of a 25 cm x 25 cm NaI(Tl) crystal having a 5 cm x 15 cm well. We have recently built a miniature proportional counter that fits into this well and is used to detect beta particles. It is constructed of .025 cm thick copper and has nine separate chambers through which methane flows. The coincidence background is 0.14 cpm and the measured beta efficiency is 45%. We are now building a .0125 cm thick counter made of aluminum having a predicted efficiency of > 90%

  16. Multiple-Coincidence Active Neutron Interrogation of Fissionable Materials

    International Nuclear Information System (INIS)

    Using a beam of tagged 14.1 MeV neutrons to probe for the presence of fissionable materials, we have measured n-γ-γ coincidences from depleted uranium (DU). The multiple coincidence rate is substantially above that measured from lead, tungsten, and iron. The presence of coincidences involving delayed gammas in the DU time spectra provides a signature for fissionable materials that is distinct from non-fissionable ones. In addition, the information from the tagged neutron involved in the coincidence gives the position of the fissionable material in all three dimensions. The result is an imaging probe for fissionable materials that is more compact and that produces much less radiation than other solutions

  17. Spectra of radioactive nuclides radiation, measured with semiconductor detectors. 2

    International Nuclear Information System (INIS)

    The second part of the atlas 'Radiation spectra of radionuclides measured with semiconductor detectors' is presented including 259 spectra of 126 alpha, beta, gamma, and X ray emitters. Some spectra of the first part of the atlas are given at another scale and sometimes for other energy ranges. The total number of investigated radionuclides amounts to 261 of which 69 are new ones

  18. Computed neutron coincidence counting applied to passive waste assay

    Energy Technology Data Exchange (ETDEWEB)

    Bruggeman, M.; Baeten, P.; De Boeck, W.; Carchon, R. [Nuclear Research Centre, Mol (Belgium)

    1997-11-01

    Neutron coincidence counting applied for the passive assay of fissile material is generally realised with dedicated electronic circuits. This paper presents a software based neutron coincidence counting method with data acquisition via a commercial PC-based Time Interval Analyser (TIA). The TIA is used to measure and record all time intervals between successive pulses in the pulse train up to count-rates of 2 Mpulses/s. Software modules are then used to compute the coincidence count-rates and multiplicity related data. This computed neutron coincidence counting (CNCC) offers full access to all the time information contained in the pulse train. This paper will mainly concentrate on the application and advantages of CNCC for the non-destructive assay of waste. An advanced multiplicity selective Rossi-alpha method is presented and its implementation via CNCC demonstrated. 13 refs., 4 figs., 2 tabs.

  19. Computed neutron coincidence counting applied to passive waste assay

    International Nuclear Information System (INIS)

    Neutron coincidence counting applied for the passive assay of fissile material is generally realised with dedicated electronic circuits. This paper presents a software based neutron coincidence counting method with data acquisition via a commercial PC-based Time Interval Analyser (TIA). The TIA is used to measure and record all time intervals between successive pulses in the pulse train up to count-rates of 2 Mpulses/s. Software modules are then used to compute the coincidence count-rates and multiplicity related data. This computed neutron coincidence counting (CNCC) offers full access to all the time information contained in the pulse train. This paper will mainly concentrate on the application and advantages of CNCC for the non-destructive assay of waste. An advanced multiplicity selective Rossi-alpha method is presented and its implementation via CNCC demonstrated. 13 refs., 4 figs., 2 tabs

  20. RADIOXENON MEASUREMENTS WITH THE PHOSWATCH DETECTOR SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Hennig, Wolfgang; Warburton, William K.; Fallu-Labruyere, A.; Sabourov, K.; Cooper, Matthew W.; McIntyre, Justin I.; Gleyzer, A.; Bean, Marc; Korpach, E.; Ungar, R. Kurt; Zhang, W.; Mekarski, P.; Ward, Rebecca; Biegalski, S.; Haas, Derek A.

    2009-09-22

    Many of the radioxenon detector systems used in the International Monitoring System and in other applications employ beta/gamma coincidence detection to achieve high sensitivity. In these systems, the coincidence detection is implemented by requiring simultaneous signals from separate beta and gamma detectors. While very sensitive to small amounts of radioxenon, this approach requires careful calibration and gain matching of several detectors and photomultiplier tubes. An alternative approach is the use of a phoswich detector in which beta-gamma coincidences are detected by pulse shape analysis. The phoswich requires only a single photomultiplier tube and thus is easier to set up and calibrate, and can be assembled into a more compact and robust system. In the past, we have developed a COTS detector system, named PhosWatch, which consists of a CsI(Tl)/BC-404 phoswich detector, digital readout electronics, and on-board software to perform the pulse shape analysis. Several units of this system have been manufactured and are now evaluated at several radioxenon research laboratories. In this paper, we will report results from production tests and some of the evaluations, including a side-by-side comparison of a SAUNA detector and a PhosWatch system using atmospheric radioxenon samples. In addition, we will show initial results obtained with a higher speed version of the readout electronics, digitizing at 500 MHz and thus able to better resolve the fast pulses from the BC-404.

  1. Spectroscopy and lifetime measurements of states in $^{76}$Kr populated in $^{76}$Rb decay

    CERN Document Server

    Giannatiempo, A; Perego, A; Sona, P; Mach, H; Fogelberg, B; García-Borge, M J; Tengblad, O; Fraile-Prieto, L M; Aas, A J; Gulda, K; CERN. Geneva

    2005-01-01

    The properties of the excited states of $^{76}$Kr, populated in the decay of $^{76}$Rb produced at ISOLDE isotopic separator, have been investigated by using K-conversion electron, $\\gamma$-ray, and $\\gamma\\gamma$ coincidence measurements. The lifetimes of several levels have been measured by means of the Advanced Time-Delayed $\\beta\\gamma\\gamma (t)$ method. The identification of 19 new levels and 55 transitions and the information deduced on spin and/or parity of the observed states from K-conversion coefficients, log ft values and decay properties have led to an improved knowledge of the level scheme. In particular, six 1$^-$ states have been definitely identified and $J^{\\pi} =2^{-}$ has been assigned to the 2227 keV level, on which a band proposed to have negative-parity and even-spin had been previously observed. The strengths of the $E$0 and $E$2 transitions de-exciting the 0$^{+}_{2}$ and 0$^{+}_{3}$ states (the latter is here identified with the state at 1598 keV) have been measured. The experimental ...

  2. Exploitation of the FLK-60 slagging incinerator for different alpha waste streams and study of the feasibility of medium-level alpha-beta-gamma waste incineration in FLK-60

    International Nuclear Information System (INIS)

    The FLK-60 high temperature slagging incinerator and its peripherals were developed by SCK/CEN with the help of the Commission of the European Communities in the framework of contract no. EUR-017-76-7 WAS-B. This second contract, which covered the period between October 1980 and December 1982, aimed at gaining exploitation experience by running the FLK-60 installation with beta-gamma radioactive waste in semi-industrial conditions. At the end of those 27 months, the system was ready for exploitation in alpha-conditions with plutonium-containing materials. This report describes the various plant parameters during the 25 runs carried out in the framework of this contract and the results of characterization tests carried out on the final product and the secondary waste streams. In the meantime, typical operation balances are computed

  3. Kinetic method for the determination of nanogram amounts of cadmium(II) by its catalytic effect on the complex formation of manganese(II) with. cap alpha. ,. beta. ,. gamma. , $delta-tetra-(p-sulfonatophenyl)porphine

    Energy Technology Data Exchange (ETDEWEB)

    Tabata, M. (Saga Univ. (Japan). Faculty of Science and Engineering); Tanaka, M. (Nagoya Univ. (Japan). Faculty of Science)

    1982-01-01

    Cadmium(II) accelerates the complex formation reaction of manganese(II) with ..cap alpha.., ..beta.., ..gamma.., $delta-tetra(p-sulfonatophenyl)porphine (H/sub 2/TPPS/sub 4/). Cadmium(II) concentration as low as 1O/sup -7/ mol dm/sup -3/ can be determined from the decrease in absorbance at 413 nm ($lambdasub(max) H/sub 2/TPPS/sub 4/) at a fixed time after the start of the reaction of manganese(II) with H/sub 2/TPPS/sub 4/. After the separation of lead(II) by coprecipitation of manganese(IV) oxide, the method is highly selective and is free from interference of most substances usually encountered. Sandell's sensitivity calculated from the calibration curve at 30 min after the start of the reaction is 1.43 x 10/sup -/ /sup 1/ ng cm/sup -2/.

  4. Artifacts in Digital Coincidence Timing

    OpenAIRE

    Moses, W. W.; Peng, Q.

    2014-01-01

    Digital methods are becoming increasingly popular for measuring time differences, and are the de facto standard in PET cameras. These methods usually include a master system clock and a (digital) arrival time estimate for each detector that is obtained by comparing the detector output signal to some reference portion of this clock (such as the rising edge). Time differences between detector signals are then obtained by subtracting the digitized estimates from a detector pair. A number of diff...

  5. The ZEPLIN-III Anti-Coincidence Veto Detector

    CERN Document Server

    Akimov, D Yu; Barnes, E J; Belov, V A; Burenkov, A A; Chepel, V; Currie, A; Edwards, B; Francis, V; Ghag, C; Hollingsworth, A; Horn, M; Kalmus, G E; Kobyakin, A S; Kovalenko, A G; Lebedenko, V N; Lindote, A; Lopes, M I; Lüscher, R; Lyons, K; Majewski, P; Murphy, A St J; Neves, F; Paling, S M; da Cunha, J Pinto; Preece, R; Quenby, J J; Reichhart, L; Scovell, P R; Solovov, V N; Smith, N J T; Smith, P F; Stekhanov, V N; Sumner, T J; Taylor, R; Thorne, C; Walker, R J

    2010-01-01

    The design, optimisation and construction of an anti-coincidence veto detector to complement the ZEPLIN-III direct dark matter search instrument is described. One tonne of plastic scintillator is arranged into 52 bars individually read out by photomultipliers and coupled to a gadolinium-loaded passive polypropylene shield. Particular attention has been paid to radiological content. The overall aim has been to achieve a veto detector of low threshold and high efficiency without the creation of additional background in ZEPLIN-III, all at a reasonable cost. Extensive experimental measurements of the components have been made, including radioactivity levels and performance characteristics. These have been used to inform a complete end-to-end Monte Carlo simulation that has then been used to calculate the expected performance of the new instrument, both operating alone and as an anti-coincidence detector for ZEPLIN-III. The veto device will be capable of rejecting over 65% of coincident nuclear recoil events from ...

  6. Control of time stability of scintillation spectrometer of delayed coincidences

    International Nuclear Information System (INIS)

    Paper describes a system to control time stability of a two-detector plastic scintillation spectrometer of three-dimensional coincides. A two-reference control system incorporates a light guide base delay optical line, two light diodes and a two-channel generator of nanosecond pulses. A distinguishing feature of the design system is application of one delay line to form both advance and delay time signal as to the real coincidences in the studied radioactive source. The designed system of control enables to measure periods of half-decay of nuclei excited states within 40-100 ns range ensuring control of position of coincidence curve gravity centers within 4 ps limits

  7. Control of time stability of scintillation spectrometer of delayed coincidences

    CERN Document Server

    Morozov, V A

    2002-01-01

    Paper describes a system to control time stability of a two-detector plastic scintillation spectrometer of three-dimensional coincides. A two-reference control system incorporates a light guide base delay optical line, two light diodes and a two-channel generator of nanosecond pulses. A distinguishing feature of the design system is application of one delay line to form both advance and delay time signal as to the real coincidences in the studied radioactive source. The designed system of control enables to measure periods of half-decay of nuclei excited states within 40-100 ns range ensuring control of position of coincidence curve gravity centers within 4 ps limits

  8. Reduction of geometry and matrix effects by fast coincidence NDA

    International Nuclear Information System (INIS)

    Fast coincidence techniques based on detection of fissions are often used to passively or actively assay SNM. Several commercial instruments based on these techniques have been available since the early Seventies: ISAS, ISAF, and Random Driver. These techniques offer high sensitivities to SMM. They are applicable to small, as well as large size containers, e.g., 55 gallon drums. Like other NDA techniques, geometrical and matrix effects can have large contributions to the measurement error. However, algebraic combinations of coincidence multiplicities can be formed which are relatively independent of detection efficiency, yet proportional to the amount of nuclear material being assayed. Considering these combinations, in addition to the coincidence rates alone as fission signatures, has the demonstrable advantage that the assay results are comparatively independent of sample geometry or even matrix. Systematic measurements to assess the degree of reduction of matrix and geometrical effects and its limitation were recently completed. The measurement results show that coincidence ratios, and most specifically, twoto three-fold ratio, reduce matrix and geometrical effects. The effect of polyethylene and sand on the standard signal was reduced by a factor of two to three. Spatial effects were reduced by 50-80%. Non-linearity, i.e., variation in signal per gram U, for a soft neutron spectrum was reduced by 20-30%, with small loss of sensitivity

  9. Application of Monte Carlo method in study of the padronization for radionuclides with complex disintegration scheme in 4πβ-γ coincidence System

    International Nuclear Information System (INIS)

    The present work described a new methodology for modelling the behaviour of the activity in a 4πβ-γ coincidence system. The detection efficiency for electrons in the proportional counter and gamma radiation in the NaI(Tl) detector was calculated using the Monte Carlo program MCNP4C. Another Monte Carlo code was developed which follows the path in the disintegration scheme from the initial state of the precursor radionuclide, until the ground state of the daughter nucleus. Every step of the disintegration scheme is sorted by random numbers taking into account the probabilities of all β- branches, electronic capture branches, transitions probabilities and internal conversion coefficients. Once the final state was reached beta, electronic capture events and gamma transitions are accounted for the three spectra: beta, gamma and coincidence variation in the beta efficiency was performed simulating energy cut off or use of absorbers (Collodion). The selected radionuclides for simulation were: 134Cs, 72Ga which disintegrate by β- transition, 133Ba which disintegrates by electronic capture and 35S which is a beta pure emitter. For the latter, the Efficiency Tracing technique was simulated. The extrapolation curves obtained by Monte Carlo were filled by the Least Square Method with the experimental points and the results were compared to the Linear Extrapolation method. (author)

  10. Electron coincidence experiments in atomic physics

    International Nuclear Information System (INIS)

    The author reports on two types of coincidence experiments involving collisions of electrons with target gases. These are the (e,2e) and (e,eγ) experiments. Coincidence experiments can completely determine the kinematics of a reaction. Under certain conditions this means that if the reaction is understood, it can yield direct detailed information on target structure or conversely if the structure is knwon it can lead to extremely sensitive information on the reaction mechanism

  11. Perturbative corrections to photon coincidence spectroscopy

    OpenAIRE

    Horvath, L.; Sanders, B. C.

    2000-01-01

    Photon coincidence spectroscopy is a promising technique for probing the nonlinear regime of cavity quantum electrodynamics in the optical domain, however its accuracy is mitigated by two factors: higher-order photon correlations, which contribute to an enhanced pair count rate, and non-simultaneity of emitted photon pairs from the optical cavity. We show that the technique of photon coincidence spectroscopy is effective in the presence of these effects if the quantitative predictions are adj...

  12. The basis for design and manufacture of a dsp-based coincidence spectrometer

    CERN Document Server

    Hai, N X; Dien, N N; Lanh, D; Huong, T T T; Khang, P D

    2013-01-01

    The coincidence technique and the coincidence spectroscopy have been developed and applied for over 40 years. Most of popular coincidence measurement systems were based on analog electronics techniques such as time to amplitude conversion (TAC) or logic selecting coincidence unit. The above-mentioned systems are relatively cumbersome and complicated to use. With the strong growth of digital electronics techniques and computational science, the coincidence measurement systems will be constructed simpler but more efficient with the sake of application. This article presents the design principle and signal processing of a simple two-channel coincidence system by a technique of Digital Signal Processing (DSP) using Field Programmable Gate Arrays (FPGA) devices at Nuclear Research Institute (NRI), Dalat.

  13. Simulation of triple coincidences in PET

    International Nuclear Information System (INIS)

    Although current PET scanners are designed and optimized to detect double coincidence events, there is a significant amount of triple coincidences in any PET acquisition. Triple coincidences may arise from causes such as: inter-detector scatter (IDS), random triple interactions (RT), or the detection of prompt gamma rays in coincidence with annihilation photons when non-pure positron-emitting radionuclides are used (β+γ events). Depending on the data acquisition settings of the PET scanner, these triple events are discarded or processed as a set of double coincidences if the energy of the three detected events is within the scanner’s energy window. This latter option introduces noise in the data, as at most, only one of the possible lines-of-response defined by triple interactions corresponds to the line along which the decay occurred. Several novel works have pointed out the possibility of using triple events to increase the sensitivity of PET scanners or to expand PET imaging capabilities by allowing differentiation between radiotracers labeled with non-pure and pure positron-emitting radionuclides. In this work, we extended the Monte Carlo simulator PeneloPET to assess the proportion of triple coincidences in PET acquisitions and to evaluate their possible applications. We validated the results of the simulator against experimental data acquired with a modified version of a commercial preclinical PET/CT scanner, which was enabled to acquire and process triple-coincidence events. We used as figures of merit the energy spectra for double and triple coincidences and the triples-to-doubles ratio for different energy windows and radionuclides. After validation, the simulator was used to predict the relative quantity of triple-coincidence events in two clinical scanners assuming different acquisition settings. Good agreement between simulations and preclinical experiments was found, with differences below 10% for most of the observables considered. For clinical

  14. Using CHIMERA detector at LNS for gamma-particle coincidences

    Directory of Open Access Journals (Sweden)

    Cardella G.

    2016-01-01

    Full Text Available We have recently evaluated the quality of γ-ray angular distributions that can be extracted in particle-gamma coincidence measurements using the CHIMERA detector at LNS. γ-rays have been detected using the CsI(Tl detectors of the spherical part of the CHIMERA array. Very clean γ-rays angular distributions were extracted in reactions induced by different stable beams impinging on 12C thin targets. The results evidenced an effect of projectile spin flip on the γ-rays angular distributions. γ-particle coincidence measurements were also performed in reactions induced by neutron rich exotic beams produced through in-flight fragmentation at LNS. In recent experiments also the Farcos array was used to improve energy and angular resolution measurements of the detected charged particles. Results obtained with both stable and radioactive beams are reported.

  15. Spectroscopy of β--delayed nγ-coincidences

    International Nuclear Information System (INIS)

    As has originally been demonstrated by γ-ray measurements, beta-delayed neutron emission from precursors with large energy windows (Qsub(β)-Bsub(n)) can not only lead to the ground state but also to excited states of the final nucleus. In these cases the construction of β-strength functions (Ssub(β)-) requires unfolding of the neutron singles spectra. The optimum spectroscopic method therefore is the measurement of delayed neutrons in coincidence with γ-rays depopulating those excited final states. With a new set-up high-resolution n%GA-coincidence spectra were measured for 94-96Rb (β-nγ) decay. (orig./AH)

  16. Using CHIMERA detector at LNS for gamma-particle coincidences

    Science.gov (United States)

    Cardella, G.; Acosta, L.; Auditore, L.; Chatterjiee, M. B.; Castoldi, A.; De Filippo, E.; Dell'Aquila, D.; De Luca, S.; Gnoffo, B.; Guazzoni, C.; Francalanza, L.; Lanzalone, G.; Lombardo, I.; Martorana, N.; Norella, S.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Quattrocchi, L.; Rizzo, F.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Vigilante, M.

    2016-05-01

    We have recently evaluated the quality of γ-ray angular distributions that can be extracted in particle-gamma coincidence measurements using the CHIMERA detector at LNS. γ-rays have been detected using the CsI(Tl) detectors of the spherical part of the CHIMERA array. Very clean γ-rays angular distributions were extracted in reactions induced by different stable beams impinging on 12C thin targets. The results evidenced an effect of projectile spin flip on the γ-rays angular distributions. γ-particle coincidence measurements were also performed in reactions induced by neutron rich exotic beams produced through in-flight fragmentation at LNS. In recent experiments also the Farcos array was used to improve energy and angular resolution measurements of the detected charged particles. Results obtained with both stable and radioactive beams are reported.

  17. Performance of an active well coincidence counter for HEU samples

    International Nuclear Information System (INIS)

    Neutron coincidence counting is the reference NDA technique used in nuclear safeguards to measure the mass of nuclear material in samples. For high-enriched uranium (HEU) samples active neutron interrogation is generally performed and the most common device used by nuclear inspectors is the Active Well Coincidence Counter (AWCC). Within her master thesis at the Polytechnic of Milan, the first author performed an intensive study on the characteristics and performances of the AWCC in order to assess the 235U mass in HEU oxide samples at the PERLA laboratory of JRC. The work has been summarised in this paper that starts with the optimisation of the use of AWCC for nuclear safeguards, describing the calibration procedure, reporting results of a series of verification measurements, summarising the performances that can be obtained with this instruments during inspections at fuel production plants and concluding with the discussion of uncertainties related to these measurements.

  18. Coincidence summing in gamma-ray spectroscopy

    International Nuclear Information System (INIS)

    A new technique has been developed to calculate coincidence-summing corrections in γ-ray spectroscopy. In this technique the general coincidence-summing equations were derived in matrix notation, which allowed extracting either the first-order correction (combinations of only two coincident γ-rays) or a full correction (all possible combinations of emitted γ-rays). Subsequently, it is shown how the technique can be applied to the determination of the source disintegration rate, γ-ray emission rates or peak efficiencies in the presence of coincidence summing. In particular, the technique has been applied to the determination of peak efficiencies of a germanium detector. The peak efficiencies were iterated self-consistently using the coincidence-summing equations. The above calculation showed that, in general, the full correction is necessary for complicated decay schemes. In addition, a method has been developed to determine the peak-to-total ratio for a germanium detector in the presence of an interfering γ-ray. (orig.)

  19. Fast procedures for the analysis of γγ coincidences in multi-detector systems and measurement of the high-spin states of 146Gd and 128Ba

    International Nuclear Information System (INIS)

    The high-spin states of the double-magic nucleus 146Gd were studied by heavy-ion compound-nucleus reactions 102Ru(48Ca,4n) at a beam energy of 210 MeV and 110Pd(40Ar,4n) at a beam energy of 181 MeV. 47 new transitions and 35 new states up to an excitation energy of 16.3 MeV could be placed in the level scheme. Furthermore a new cascade was observed, which origins possibly from a breakup of the magic (N=82) neutron shell. The quasi-particle bands in the γ-soft transitional nucleus 128Ba were studied with the heavy-ion compound-nucleus reaction 96Zr(36S,4n) at a beam energy of 150 MeV. The Yrast band could be spectroscoped up to a spin of 34 ℎ. It shows to band crossings, which interpreted as crossings with the πh211/2) two-quasiparticle band and the πh 211/2νh211/2) four-quasiparticle band. A complete picture of the band structures in 128Ba is proposed and discussed. For the fast sorting of γγ-coincidences in many-parameter experiments a comprehensive program packet was developed. It allows the recalibration and presorting of data in a central first step and then followingly the fast sorting of many coincidence matrices under complex window conditions. For the support of systematical studies of the nuclear structure a new concept for a nuclear-spectroscopic data base was developed. It allows the fast data exchange via international computer networks and contains a time spectroscopic data of about 300 nuclei. A basic software was developed, which allows an easy access to the data. (orig./HSI)

  20. Another coincidence problem for $\\Lambda$CDM?

    CERN Document Server

    van Oirschot, Pim; Lewis, Geraint F

    2014-01-01

    Over the last nine years of cosmic microwave background observations, the Wilkinson Microwave Anisotropy Probe ($WMAP$) results were consistent with a $\\Lambda$CDM cosmological model in which the age of the Universe is one Hubble time, and the time-averaged value of the deceleration parameter is consistent with zero. This curious observation has been put forward as a new coincidence problem for the $\\Lambda$CDM concordance cosmology, which is in fact a `greater' coincidence than the near equality of the density parameters of matter and the cosmological constant. At the moment of writing these conference proceedings, the Planck Collaboration has released its first cosmological data, which revealed a small shift in the $\\Lambda$CDM cosmological parameters when compared to $WMAP$. We show that under the assumption of a spatially flat $\\Lambda$CDM cosmology, Planck's results remove this coincidence problem for $\\Lambda$CDM at greater than 99\\% confidence level.

  1. Coincidence lattices in the hyperbolic plane.

    Science.gov (United States)

    Rodríguez-Andrade, M A; Aragón-González, G; Aragón, J L; Gómez-Rodríguez, A

    2011-01-01

    The problem of coincidences of lattices in the space R(p,q), with p + q = 2, is analyzed using Clifford algebra. We show that, as in R(n), any coincidence isometry can be decomposed as a product of at most two reflections by vectors of the lattice. Bases and coincidence indices are constructed explicitly for several interesting lattices. Our procedure is metric-independent and, in particular, the hyperbolic plane is obtained when p = q = 1. Additionally, we provide a proof of the Cartan-Dieudonné theorem for R(p,q), with p + q = 2, that includes an algorithm to decompose an orthogonal transformation into a product of reflections. PMID:21173471

  2. Development of an analysis methodology applied to 4πβ-γ software coincidence data acquisition system

    International Nuclear Information System (INIS)

    The present work describes the new software methodology under development at the IPEN Nuclear Metrology Laboratory for radionuclide standardizations with 4πβ-γ coincidence technique. The software includes the Coincidence Graphic User Interface (GUI) and the Coincidence Analysis Program. The first results for a 60Co sample measurement are discussed and compared to the results obtained with two different conventional coincidence systems. (author)

  3. Electron--photon coincidence technique for electron impact on atoms

    International Nuclear Information System (INIS)

    A brief introduction is given to the general theory of the electron photon coincidence technique, and the specific application to 1P and 3P excitations in helium is described. The relation between the complex excitation amplitudes which characterize the collision process and the alignment and orientation of the excited atoms is emphasized. The data from the first electron photon angular correlation measurements are presented. These data yield values for the ratio of differential cross sections for exciting the degenerate sublevels and the relative phase of the corresponding amplitudes, or, equivalently, the alignment and orientation parameters. The results are obtained in dimensionless form and are free from absolute calibration or normalization difficulties. They are compared with various theoretical approximations. The application of the coincidence technique to a measurement of threshold polarization is described and results for 31P excitations are discussed

  4. Coincidence Doppler Broadening of Positron Annihilation Radiation in Fe

    Science.gov (United States)

    do Nascimento, E.; Vanin, V. R.; Maidana, N. L.; Helene, O.

    2013-06-01

    We measured the Doppler broadening annihilation radiation spectrum in Fe, using 22NaCl as a positron source, and two Ge detectors in coincidence arrangement. The two-dimensional coincidence energy spectrum was fitted using a model function that included positron annihilation with the conduction band and 3d electrons, 3s and 3p electrons, and in-flight positron annihilation. Detectors response functions included backscattering and a combination of Compton and pulse pileup, ballistic deficit and shaping effects. The core electrons annihilation intensity was measured as 16.4(3) %, with almost all the remainder assigned to the less bound electrons. The obtained results are in agreement with published theoretical values.

  5. High-level neutron coincidence counter (HLNCC): users' manual

    International Nuclear Information System (INIS)

    This manual describes the portable High-Level Neutron Coincidence Counter (HLNCC) developed at the Los Alamos Scientific Laboratory (LASL) for the assay of plutonium, particularly by inspectors of the International Atomic Energy Agency (IAEA). The counter is designed for the measurement of the effective 240Pu mass in plutonium samples which may have a high plutonium content. The following topics are discussed: principle of operation, description of the system, operating procedures, and applications

  6. Kinematics for chicane-beam electron coincidence experiments

    International Nuclear Information System (INIS)

    The kinematics for coincidence electrodisintegration experiments are investigated. 'Out-of-plane' measurements designed to completely determine the unpolarized cross section are analyzed by an alternate method that considers the situation where the primary electron beam is redirected through the plane formed by the target and the spectrometer. Specific cases, namely, pion production in a light nucleus, proton electroproduction in the giant resonance region and deuteron electrodisintegration in the quasielastic region are examined. (orig.)

  7. Sharp coincidences for absolutely summing multilinear operators

    OpenAIRE

    Pellegrino, Daniel

    2012-01-01

    In this note we prove the optimality of a family of known coincidence theorems for absolutely summing multilinear operators. We connect our results with the theory of multiple summing multilinear operators and prove the sharpness of similar results obtained via the complex interpolation method.

  8. Curious numerical coincidence to the Pioneer anomaly

    OpenAIRE

    Ivanescu, Liviu

    2009-01-01

    One noticed a pure numerical coincidence between the Pioneer spacecrafts deceleration anomaly and (gamma-1), with gamma the Lorentz factor. The match is not only for distances larger than 20 AU, but even for the observed slop between 10 and 20 AU.

  9. Determination of amount of Pu in samples by using neutron coincidences. Correction of induced fissions by coincidence multiplets detection

    International Nuclear Information System (INIS)

    When the isotopic composition of nuclear materials to control is know, it is possible to determine the amount of plutonium by measuring the rate of spontaneous fissions. The induced fissions alter significantly the measures. Therefore we must evaluate the multiplicative factor. For a not very multiplicative sample, the observed real neutron coincidences of multiplicity 0 to n agree with spontaneous emissions given by nuclear tables. This is not true in the opposite case (large amounts). Multiplicities are given by eighteen counting-scales associated with a shift-register coincidence system (SCRD) and compared with theoretical spontaneous emissions of the sample. A calculator leads all the equipment and gives automatically the real amount of Pu

  10. Recent Advances in Digital Coincidence Counting for Radionuclide Metrology

    International Nuclear Information System (INIS)

    The radioactivity measurement techniques developed within the EURAMET EMRP 'MetroFission' Joint Research Project, were aimed at performing on-site activity measurements at the primary standard level (4πβ-γ coincidence counting) for a wide range of radionuclides utilizing recent advances in high-speed digital sampling and digital signal processing. The state-of-the-art technology employed within this project provides up to 14-bit digitizer systems operating with sampling rates in the order of 108 to 109 samples-per-second, incorporating on-board FPGA devices, which greatly enhances the application of digital signal processing for the implementation of digital coincidence counting. These devices when coupled to suitable analysis software, demonstrate a significant improvement in the provision of primary standards of radioactivity. This manuscript provides a description of the systems employed, along with recommendations regarding optimization of the digital sampling of signals from photo-multiplier tubes and pre-amplifiers and compare the benefits of 'off-line' versus 'on-line' 4πβ-γ digital coincidence counting systems. (authors)

  11. Data Acquisition System for Electron Energy Loss Coincident Spectrometers

    Institute of Scientific and Technical Information of China (English)

    Zhang Chi; Yu Xiaoqi; Yang Tao

    2005-01-01

    A Data Acquisition System (DAQ) for electron energy loss coincident spectrometers (EELCS) has been developed. The system is composed of a Multiplex Time-Digital Converter (TDC) that measures the flying time of positive and negative ions and a one-dimension positionsensitive detector that records the energy loss of scattering electrons. The experimental data are buffered in a first-in-first-out(FIFO) memory module, then transferred from the FIFO memory to PC by the USB interface. The DAQ system can record the flying time of several ions in one collision, and allows of different data collection modes. The system has been demonstrated at the Electron Energy Loss Coincident Spectrometers at the Laboratory of Atomic and Molecular Physics, USTC. A detail description of the whole system is given and experimental results shown.

  12. Simplified methods for coincidence summing corrections in HPGe efficiency calibration

    International Nuclear Information System (INIS)

    Simple and practical coincidence summing corrections for n-type HPGe detectors are presented for the common calibration nuclides 57Co and 60Co using a defined “virtual peak” and accounting for the summing of gamma photons with x-rays having energies up to 40 keV (88Y and 139Ce). These corrections make it possible to easily and effectively establish peak and total efficiency curves suitable for subsequent summing corrections in routine gamma spectrometry analyses. Experimental verification of the methods shows excellent agreement for measurements of different reference solutions. - Highlights: ► Coincidence summing corrections are important in environmental gamma-ray spectrometry. ► Simple and practical corrections are presented for HPGe efficiency calibrations. ► Emphasis is placed on summing with low-energy photons in n-type detectors. ► The experimental validations of the methods show excellent agreement.

  13. Momentum spectrometer for electron-electron coincidence studies on superconductors.

    Science.gov (United States)

    Wallauer, Robert; Voss, Stefan; Foucar, Lutz; Bauer, Tobias; Schneider, Deborah; Titze, Jasmin; Ulrich, Birte; Kreidi, Katharina; Neumann, Nadine; Havermeier, Tilo; Schöffler, Markus; Jahnke, Till; Czasch, Achim; Schmidt, Lothar; Kanigel, Amit; Campuzano, Juan Carlos; Jeschke, Harald; Valenti, Roser; Müller, Andreas; Berner, Götz; Sing, Michael; Claessen, Ralph; Schmidt-Böcking, Horst; Dörner, Reinhard

    2012-10-01

    We present a new experimental setup to study electron-electron coincidences from superconducting surfaces. In our approach, electrons emitted from a surface are projected onto a time- and position-sensitive microchannel plate detector with delayline position readout. Electrons that are emitted within 2 π solid angle with respect to the surface are detected in coincidence. The detector used is a hexagonal delayline detector with enhanced multiple hit capabilities. It is read out with a Flash analog-to-digital converter. The three-dimensional momentum vector is obtained for each electron. The intrinsic dead time of the detector has been greatly reduced by implementing a new algorithm for pulse analysis. The sample holder has been matched to fit the spectrometer while being capable of cooling down the sample to 4.5 K during the measurement and heating it up to 420 K for the cleaning procedure. PMID:23126780

  14. Simplified slow anti-coincidence circuit for Compton suppression systems

    International Nuclear Information System (INIS)

    Slow coincidence circuits for the anti-coincidence measurements have been considered for use in Compton suppression technique. The simplified version of the slow circuit has been found to be fast enough, satisfactory and allows an easy system setup, particularly with the advantage of the automatic threshold setting of the low-level discrimination. A well-type NaI detector as the main detector surrounded by plastic guard detector has been arranged to investigate the performance of the Compton suppression spectrometer using the simplified slow circuit. The system has been tested to observe the improvement in the energy spectra for medium to high-energy gamma-ray photons from terrestrial and environmental samples

  15. Simplified slow anti-coincidence circuit for Compton suppression systems.

    Science.gov (United States)

    Al-Azmi, Darwish

    2008-08-01

    Slow coincidence circuits for the anti-coincidence measurements have been considered for use in Compton suppression technique. The simplified version of the slow circuit has been found to be fast enough, satisfactory and allows an easy system setup, particularly with the advantage of the automatic threshold setting of the low-level discrimination. A well-type NaI detector as the main detector surrounded by plastic guard detector has been arranged to investigate the performance of the Compton suppression spectrometer using the simplified slow circuit. The system has been tested to observe the improvement in the energy spectra for medium to high-energy gamma-ray photons from terrestrial and environmental samples. PMID:18222698

  16. Wardowski conditions to the coincidence problem

    Directory of Open Access Journals (Sweden)

    David eAriza-Ruiz

    2015-08-01

    Full Text Available In this article we □rst discuss the existence and uniqueness of a solution for the coincidence problem:Find $p in X$ such that Tp = Sp; where X is a nonempty set, Y is a complete metric space, and$T; S : X to Y$ are two mappings satisfying a Wardowski type condition of contractivity. Later on, wewill state the convergence of the Picard-Juncgk iteration process to the above coincidence problemas well as a rate of convergence for this iteration scheme. Finally, we shall apply our results to studythe existence and uniqueness of a solution as well as the convergence of the Picard-Juncgk iterationprocess towards the solution of a second order di□erential equation.

  17. Recent progress with digital coincidence counting

    International Nuclear Information System (INIS)

    Digital Coincidence Counting (DCC) is a new technique, based on the older method of analogue coincidence counting. It has been developed by ANSTO as a faster more reliable means of determining the activity of ionising radiation samples. The technique employs a dual channel analogue to digital converter acquisition system for collecting pulse information from a 4Π beta detector and a NaI(Tl) gamma detector. The digitised pulse information is stored on a high speed hard disk and timing information for both channels is also stored. The data may subsequently be recalled and analysed using software based algorithms. The system is operational and results are now being routinely collected and analysed. Some of the early work is presented for Co-60, Na-22 and Sm-153

  18. Cosmic Coincidences: Investigations for Neutron Background Suppression

    OpenAIRE

    Heimbach, Craig R.

    2007-01-01

    Two experimental investigations were made in order to reduce background counts in neutron detectors. Each investigation relied upon the fact that neutron background is largely due to cosmic ray interactions with the air and ground. The first attempt was to look at neutron arrival times. Neutron events close in time were taken to have been of a common origin due to cosmic rays. The second investigation was similar, but based on coincident neutron/muon events. The investigations showed only a s...

  19. Natural radioactivity measurements at the proposed nuclear power plant site

    International Nuclear Information System (INIS)

    Natural radioactivity measurement in the Philippines aims to establish baseline radioactivity levels in the environment of items essential to man. In this article, results of the environmental surveillance conducted in Bagac, Bataan from 1973 to 1974 are presented. Analyses were made on air parti-culates, sea and fresh water, grass, and soil samples for gross beta-gamma activities. Results obtained showed activity levels below the maximum permissible concentration recommended by the International Committee on Radiation Protection (ICRP)

  20. Development of radon isotopes discrimination device by software delayed coincidence method based on ARM

    International Nuclear Information System (INIS)

    The software delayed coincidence counting technology was researched based on embedded system. The device based on ARM processor was constructed to record time serials information of nuclear pulse. According to the different half-life of Po short-life daughters of radon isotopes, a method of software delayed coincidence counting was used to discriminate radon isotopes. Experiment results of 220Rn and 219Rn standard source measurement show that the software delayed coincidence counting method is practical for discrimination measurement of low level activity of radon isotopes. The software method is an alternative to hardware one, and it can offer better convenience and flexibility. (authors)

  1. Monte Carlo calculations of the neutron coincidence gate utilisation factor for passive neutron coincidence counting

    CERN Document Server

    Bourva, L C A

    1999-01-01

    The general purpose neutron-photon-electron Monte Carlo N-Particle code, MCNP sup T sup M , has been used to simulate the neutronic characteristics of the on-site laboratory passive neutron coincidence counter to be installed, under Euratom Safeguards Directorate supervision, at the Sellafield reprocessing plant in Cumbria, UK. This detector is part of a series of nondestructive assay instruments to be installed for the accurate determination of the plutonium content of nuclear materials. The present work focuses on one aspect of this task, namely, the accurate calculation of the coincidence gate utilisation factor. This parameter is an important term in the interpretative model used to analyse the passive neutron coincidence count data acquired using pulse train deconvolution electronics based on the shift register technique. It accounts for the limited proportion of neutrons detected within the time interval for which the electronics gate is open. The Monte Carlo code MCF, presented in this work, represents...

  2. The IAEA neutron coincidence counting (INCC) and the DEMING least-squares fitting programs

    International Nuclear Information System (INIS)

    Two computer programs are described: (1) the INCC (IAEA or International Neutron Coincidence Counting) program and (2) the DEMING curve-fitting program. The INCC program is an IAEA version of the Los Alamos NCC (Neutron Coincidence Counting) code. The DEMING program is an upgrade of earlier Windows reg-sign and DOS codes with the same name. The versions described are INCC 3.00 and DEMING 1.11. The INCC and DEMING codes provide inspectors with the software support needed to perform calibration and verification measurements with all of the neutron coincidence counting systems used in IAEA inspections for the nondestructive assay of plutonium and uranium

  3. Performance of a coincidence based blood activity monitor

    International Nuclear Information System (INIS)

    A new device has been constructed that measures the positron emitting radio-tracer concentration in arterial blood by extracting blood with a peristaltic pump, then measuring the activity concentration by detecting coincident pairs of 511 keV photons with a pair of heavy inorganic scintillators attached to photomultiplier tubes. The sensitivity of this device is experimentally determined to be 610 counts/second per μCi/ml, and has a paralyzing dead time of 1.2 μs, so is capable of measuring blood activity concentration as high as 1 mCi/ml. Its performance is compared to two other blood monitoring methods: discrete blood samples counted with a well counter and device that uses a plastic scintillator to directly detect positrons. The positron detection efficiency of this device for 18F is greater than the plastic scintillation counter, and also eliminates the radioisotope dependent correction factors necessary to convert count rate to absolute concentration. Coincident photon detection also has the potential of reducing the background compared to direct positron detection, thereby increasing the minimum detectable isotope concentration. 10 refs., 6 figs

  4. Aperiodic phase re-setting in scalp EEG of beta-gamma oscillations by state transitions at alpha-theta rates.

    Science.gov (United States)

    Freeman, Walter J; Burke, Brian C; Holmes, Mark D

    2003-08-01

    We evaluated the rapid changes in regional scalp EEG synchronization in normal subjects with spatial and temporal resolution exceeding prior art 10-fold with a high spatial density array and the Hilbert transform. A curvilinear array of 64 electrodes 3 mm apart extending 18.9 cm across the scalp was used to record EEG at 200/sec. Analytic amplitude (AA) and phase (AP) were calculated at each time step for the 64 traces in the analog pass band of 0.5-120 Hz. AP differences approximated the AP derivative (instantaneous frequency). The AP from unfiltered EEG revealed no reproducible patterns. Filtering was necessary in the beta and gamma ranges according to a technique that optimized the correlation of the AP differences with the activity band pass filtered in the alpha range. The sizes of temporal AP differences were usually within +/-0.5 radian from the average step corresponding to the center frequency of the pass band. Large AP differences were often synchronized over distances of 6 to 19 cm. An optimal pass band to detect and measure these recurring jumps in AP in the beta and gamma ranges was found by maximizing the alpha peak in the cospectrum of the correlation between unfiltered EEG and the band pass AP differences. Synchronized AP jumps recurred in clusters (CAP) at alpha and theta rates in resting subjects and with EMG. Cortex functions by serial changes in state. The Hilbert transform of EEG from high-density arrays can visualize these state transitions with high temporal and spatial resolution and should be useful in relating EEG to cognition. PMID:12874778

  5. The efficiency calibration for the β-γ coincidence system using 133Xe and 131mXe mixture

    International Nuclear Information System (INIS)

    Background: Being one of the sixteen radionuclide laboratories for CTBT, Beijing radionuclide laboratory studied the β-γ coincidence system to measure the activities of xenon isotopes (131mXe, 133mXe, 133Xe and 135Xe). The efficiency calibration is an important and difficult technique in the β-γ coincidence measurement. Purpose: The study is carried out to calibrate the efficiency for the β-γ coincidence system. Methods: The efficiency of the β(γ) particle can be calculate by the ratio of the coincidence counts/single γ(β) counts without knowing the sample activity. A 133Xe and 131mXe mixture, whose activity is not known, is used to calibrate the efficiency. Results: The efficiency for the β-γ coincidence system is got by this method. Conclusions: The method has been used to calibrate the efficiencies of β-γ coincidence system in our laboratory. (authors)

  6. Coincidence experiments in desorption mass spectrometry

    Science.gov (United States)

    Diehnelt, C. W.; English, R. D.; Van Stipdonk, M. J.; Schweikert, E. A.

    2002-06-01

    The detection of coincidental signals can enhance the amount of information available in desorption time-of-flight mass spectrometry (TOF-MS) by identifying physical, chemical and/or spatial correlations between secondary ions. Detection of coincidental emissions requires that the target surface be bombarded with individual primary ions (keV or MeV), each resolved in time and space. This paper will discuss the application of coincidence counting to TOF-MS to: extract the secondary ion mass spectrum and secondary ion yields from an organic target produced by a single primary ion type when multiple primary ions simultaneously impact the sample; examine the metastable dissociation pathways and decay fractions of organic secondary ions using an ion-neutral correlation method; and study the chemical microhomogeneity (on the sub-μm scale) of a surface composed of two chemically distinct species.

  7. Mass Scales and the Cosmological Coincidences

    Science.gov (United States)

    Landsberg, P. T.

    Theories involving the parameters h, c, G, H (in a usual notation) are considered. A huge ratio of 10120 of the mass of the universe (mu) to the smallest determinable mass m0 in the period since the big bang occurs in such theories. Five masses are here identified and interpreted between these two limits so that one has in all seven analytical expressions for masses. They form a geometrical progression m0, m0R, , m0R6 = mu with R 1020. It is shown that this formulation is easily adapted to explain existing cosmological coincidences and to generate new ones. Über die kosmische Bedingtheit einer Massenskala: Es werden kosmologische Theorien diskutiert, in denen neben der Planckschen Konstante h, der Lichtgeschwindigkeit c und der Gravitationskonstante G auch noch der Hubble-Parameter H eingeht. Für solche Kosmen wird eine Massen-Scala hergeleitet, die einer geometrischen Progression, mit dem Eddingtonschen Faktor 1020 entspricht.

  8. Mass scales and the cosmological coincidences

    International Nuclear Information System (INIS)

    Theories involving the parameters Planck's constant, light velocity, Newton's gravitational constant, and the Hubble parameter (in a usual notation) are considered. A huge ratio of 10120 of the mass of the universe (m/sub u/) to the smallest determinable mass m0 in the period since the big bang occurs in such theories. Five masses are here identified and interpreted between these two limits so that one has in all seven analytical expressions for masses. They form a geometrical progression m0, m0R,..., m0R6 = m/sub u/ with R approximately 1020. It is shown that this formulation is easily adapted to explain existing cosmological coincidences and to generate new ones. (author)

  9. A generalized model for coincidence counting

    International Nuclear Information System (INIS)

    The aim of this paper is to provide a description of the multiplicative processes associated with coincidence counting techniques, for example in the NDA of plutonium bearing materials. The model elucidates both the physical processes and the underlying mathematical formalism in a relatively simple but comprehensive way. In particular, it includes the effect of absorption by impurities or poisons, as well as that of neutron leakage on a parallel basis to the treatment of induced fission itself. The work thus parallels and generalizes the methods of Boehnel of Hage and Cifarelli, and more recently of Yanjushkin. This paper introduces the concept of a dual probability generating function to account for both the basic physical multiplication phenomena, as well as the detection phenomena. The underlying approach extends the idea of a simple probability generating function, due to De Moivre. The basic mathematical background may be found, for example, in Feller 1966

  10. Monte Carlo simulation of a digital coincidence system applied to 60Co standardization

    International Nuclear Information System (INIS)

    The Laboratorio de Metrologia Nuclear (LMN) at the Instituto de Pesquisas Energeticas e Nucleares (IPEN) is developing a Digital Coincidence System (DCS), including the design of the proper acquisition electronics and analysis software. A brief discussion about the measurement methodology and the electronics operation is presented. This work is focused on the results of the designed software (the Monte Carlo simulation of 60Co decay data and the Coincidence Data Analysis), which are in good agreement with the experimental data. (author)

  11. The coincidence-summing correction of the Compton-suppression spectrometer.

    Science.gov (United States)

    Fan, Yuan-qing; Wang, Jun; Wang, Shi-lian; Zhang, Xin-jun; Li, Qi

    2012-09-01

    The compton-suppression Spectrometer can suppress the Compton baseline and make weak full energy peaks prominent in low-level activity gamma spectra, so it is used to measure environmental radioactive samples. In order to quantify the activities of the radionuclides in the sample coincidence-summing corrections should be applied. In this article the expressions of coincidence-summing correction of Compton-Suppression Spectrometer were deduced and the validity of the expressions was verified. PMID:22405959

  12. Imaging photoelectron photoion coincidence spectroscopy with velocity focusing electron optics

    International Nuclear Information System (INIS)

    An imaging photoelectron photoion coincidence spectrometer at the vacuum ultraviolet (VUV) beamline of the Swiss Light Source is presented and a few initial measurements are reported. Monochromatic synchrotron VUV radiation ionizes the cooled or thermal gas-phase sample. Photoelectrons are velocity focused, with better than 1 meV resolution for threshold electrons, and also act as start signal for the ion time-of-flight analysis. The ions are accelerated in a relatively low, 40-80 V cm-1 field, which enables the direct measurement of rate constants in the 103-107 s-1 range. All electron and ion events are recorded in a triggerless multiple-start/multiple-stop setup, which makes it possible to carry out coincidence experiments at >100 kHz event frequencies. As examples, the threshold photoelectron spectrum of the argon dimer and the breakdown diagrams for hydrogen atom loss in room temperature methane and the chlorine atom loss in cold chlorobenzene are shown and discussed.

  13. A high-efficiency HPGe coincidence system for environmental analysis

    International Nuclear Information System (INIS)

    The Comprehensive Nuclear–Test–Ban Treaty (CTBT) is supported by a network of certified laboratories which must meet certain sensitivity requirements for CTBT relevant radionuclides. At the UK CTBT Radionuclide Laboratory (GBL15), a high-efficiency, dual–detector gamma spectroscopy system has been developed to improve the sensitivity of measurements for treaty compliance, greatly reducing the time required for each sample. Utilising list–mode acquisition, each sample can be counted once, and processed multiple times to further improve sensitivity. For the 8 key radionuclides considered, Minimum Detectable Activities (MDA's) were improved by up to 37% in standard mode (when compared to a typical CTBT detector system), with the acquisition time required to achieve the CTBT sensitivity requirements reduced from 6 days to only 3. When utilising the system in coincidence mode, the MDA for 60 Co in a high–activity source was improved by a factor of 34 when compared to a standard CTBT detector, and a factor of 17 when compared to the dual–detector system operating in standard mode. These MDA improvements will allow the accurate and timely quantification of radionuclides that decay via both singular and cascade γ emission, greatly enhancing the effectiveness of CTBT laboratories. - Highlights: • New high-sensitivity, high-resolution gamma spectroscopy system developed. • Data collected in list-mode with all events time stamped for offline coincidence analysis. • MDA's improved for a range of CTBT relevant radionuclides in singles mode. • MDA's substantially improved by detecting multiple gammas in coincidence

  14. Study and development of a spectrometer with Compton suppression and gamma coincidence counting

    International Nuclear Information System (INIS)

    This paper presents the characteristics of a spectrometer consisting of a Ge detector surrounded by a NaI(T1) detector that can operate in Compton-suppression and gamma-gamma coincidence modes. The criteria that led to this measurement configuration are discussed and the spectrometer performances are shown for 60Co and 137Cs gamma-ray sources. The results for the measurement of 189Ir (Compton suppression) and for the measurement of 101Rh (gamma-gamma coincidence) in the presence of other radioisotopes are given. 83Rb and 105Ag isotopes are also measured with this spectrometer

  15. Capability of analysis arsenic in geology sample by gamma-gamma coincidence method

    International Nuclear Information System (INIS)

    Gamma-gamma coincidence method has been successfully applied to the study of nuclear data and structure. Due to good abilities of background reduction, gamma-gamma coincidence method has been widely applied in neutron activation analysis. The experimental studies on geological and environmental samples have been conducted in several laboratories in the world. This report presents the results of Arsenic (As) analysis of geological sample by neutron activation analysis with coincidence method. The results show that the linearity between concentration in sample and count rate of peak in coincidence measurements and the influence of isotopes was eliminated and the background was reduced by application of this method in comparison with the conventional method that uses a detector. The results also found out that detection limits for analysis of As in geological samples were improved. (author)

  16. X-ray fluorescence/Auger-electron coincidence spectroscopy of vacancy cascades in atomic argon

    Energy Technology Data Exchange (ETDEWEB)

    Arp, U. [National Inst. of Standards and Technology, Gaithersburg, MD (United States). Electron and Optical Physics Div.; LeBrun, T.; Southworth, S.H.; Jung, M. [Argonne National Lab., IL (United States). Physics Div.; MacDonald, M.A. [E.P.S.R.C. Daresbury Lab., Warrington (United Kingdom)

    1996-12-01

    Argon L{sub 2.3}-M{sub 2.3}M{sub 2.3} Auger-electron spectra were measured in coincidence with K{alpha} fluorescent x-rays in studies of Ar K-shell vacancy decays at several photon energies above the K-threshold and on the 1s-4p resonance in atomic argon. The complex spectra recorded by conventional electron spectroscopy are greatly simplified when recorded in coincidence with fluorescent x-rays, allowing a more detailed analysis of the vacancy cascade process. The resulting coincidence spectra are compared with Hartree-Fock calculations which include shake-up transitions in the resonant case. Small energy shifts of the coincidence electron spectra are attributed to post-collision interaction with 1s photoelectrons.

  17. Novel data evaluation algorithm for Coincident Doppler Broadening Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pikart, Philip, E-mail: philip@pikart.de [Technische Universität München, Physics Department E21, Lichtenbergstr. 1, 85747 Garching (Germany); Hugenschmidt, Christoph [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Lichtenbergstr. 1, 85747 Garching (Germany)

    2014-06-01

    In Coincident Doppler Broadening Spectroscopy (CDBS) the sum energy of the annihilation photons is checked to be 1022 keV, to validate the measurement of an undisturbed two-gamma electron–positron decay event. The events are stored in a two-dimensional acquisition matrix. A new algorithm is presented, which optimizes the extraction of the one-dimensional CDBS spectrum from this matrix by enhanced background suppression by the use of variable size bins. - Highlights: • A more efficient data evaluation algorithm for CDBS is presented. • The SNR in parts of the CDB spectrum is improved by one order of magnitude. • Variable binning combines good resolution with lowest measurement error. • The mean detector resolution is extracted from the CDBS data.

  18. The model JSR-12 neutron coincidence analyzer

    International Nuclear Information System (INIS)

    This paper reports that one of the ways in which non-destructive assays for nuclear materials is made involved counting the neutron signatures which result from spontaneous or induced fissions in fissile materials. A major problem in determining the number of fission neutrons is trying to separate them from the background of neutrons arising from alpha particle interactions with lighter nuclei in the matrix materials of the samples being assayed. The JSR-12 neutron coincidence analyzer operates on the principle that fission neutrons occur in multiples of two or more, whereas background neutrons occur randomly as single events. By exploiting this time correlation difference, the JSR-12 can determine the fission neutron signal. This instrument represents a considerable upgrade from the industry standard JSR-11, by doubling the response speed and adding complete computer control of all functions, as well as employing non-volatile memory for data storage. Operation has been simplified for field use by using an LCD display to guide the operator in setting up assay parameters, and by time-date tagging all assays for later retrieval

  19. Uranium mass and neutron multiplication factor estimates from time-correlation coincidence counts

    International Nuclear Information System (INIS)

    Time-correlation coincidence counts of neutrons are an important means to measure attributes of nuclear material. The main deficiency in the analysis is that an attribute of an unknown component can only be assessed by comparing it with similar known components. There is a lack of a universal method of measurement suitable for the different attributes of the components. This paper presents a new method that uses universal relations to estimate the mass and neutron multiplication factor of any uranium component with known enrichment. Based on numerical simulations and analyses of 64 highly enriched uranium components with different thicknesses and average radii, the relations between mass, multiplication and coincidence spectral features have been obtained by linear regression analysis. To examine the validity of the method in estimating the mass of uranium components with different sizes, shapes, enrichment, and shielding, the features of time-correlation coincidence-count spectra for other objects with similar attributes are simulated. Most of the masses and multiplications for these objects could also be derived by the formulation. Experimental measurements of highly enriched uranium castings have also been used to verify the formulation. The results show that for a well-designed time-dependent coincidence-count measuring system of a uranium attribute, there are a set of relations dependent on the uranium enrichment by which the mass and multiplication of the measured uranium components of any shape and size can be estimated from the features of the source-detector coincidence-count spectrum

  20. Uranium mass and neutron multiplication factor estimates from time-correlation coincidence counts

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Wenxiong [China Academy of Engineering Physics, Center for Strategic Studies, Beijing 100088 (China); Li, Jiansheng [China Academy of Engineering Physics, Institute of Nuclear Physics and Chemistry, Mianyang 621900 (China); Zhu, Jianyu [China Academy of Engineering Physics, Center for Strategic Studies, Beijing 100088 (China)

    2015-10-11

    Time-correlation coincidence counts of neutrons are an important means to measure attributes of nuclear material. The main deficiency in the analysis is that an attribute of an unknown component can only be assessed by comparing it with similar known components. There is a lack of a universal method of measurement suitable for the different attributes of the components. This paper presents a new method that uses universal relations to estimate the mass and neutron multiplication factor of any uranium component with known enrichment. Based on numerical simulations and analyses of 64 highly enriched uranium components with different thicknesses and average radii, the relations between mass, multiplication and coincidence spectral features have been obtained by linear regression analysis. To examine the validity of the method in estimating the mass of uranium components with different sizes, shapes, enrichment, and shielding, the features of time-correlation coincidence-count spectra for other objects with similar attributes are simulated. Most of the masses and multiplications for these objects could also be derived by the formulation. Experimental measurements of highly enriched uranium castings have also been used to verify the formulation. The results show that for a well-designed time-dependent coincidence-count measuring system of a uranium attribute, there are a set of relations dependent on the uranium enrichment by which the mass and multiplication of the measured uranium components of any shape and size can be estimated from the features of the source-detector coincidence-count spectrum.

  1. Coincident photoelectron spectroscopy on superconductors; Koinzidente Photoelektronenspektroskopie an Supraleitern

    Energy Technology Data Exchange (ETDEWEB)

    Voss, Stefan

    2011-07-01

    Aim of the performed experiments of this thesis was to attempt to detect Cooper pairs as carriers of the superconducting current directly by means of the photoelectric effect. The method of the coincident photoelectron spectroscopy aims thereby at the detection of two coherently emitted electrons by the interaction with a photon. Because electrostatic analyzers typically cover only a very small spatial angle, which goes along with very low coincidence rates, in connection with this thesis a time-of-flight projection system has been developed, which maps nearly the whole spatial angle on a position-resolving detector. The pulsed light source in form of special synchrotron radiation necessary for the measurement has been adjusted so weak, that only single photons could arrive at the sample. Spectroscoped were beside test measurements on silver layers both a lead monocrystal as representative of the classical BCS superconductors and monocrystalline Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} from the family of the high-temperature superconductors. With excitation energies up to 40 eV could be shown that sufficiently smooth and clean surfaces in the superconducting phase exhibit within the resolving power of about 0.5 eV no recognizable differences in comparison to the normally conducting phase. Beside these studies furthermore the simple photoemission at the different samples and especially in the case of the lead crystal is treated, because here no comparable results are known. Thereby the whole momentum space is discussed and the Fermi surface established as three-dimensional model, by means of which the measurement results are discussed. in the theoretical descriptions different models for the Cooper-pair production are presented, whereby to the momentum exchange with the crystal a special role is attributed, because this can only occur in direct excitations via discrete lattice vectors.

  2. Derivation of decay heat benchmarks for U235 and Pu239 by a least squares fit to measured data

    International Nuclear Information System (INIS)

    A least squares technique used by previous authors has been applied to an extended set of available decay heat measurements for both U235 and Pu239 to yield simultaneous fits to the corresponding beta, gamma and total decay heat. The analysis takes account of both systematic and statistical uncertainties, including correlations, via calculations which use covariance matrices constructed for the measured data. The results of the analysis are given in the form of beta, gamma and total decay heat estimates following fission pulses and a range of irradiation times in both U235 and Pu239. These decay heat estimates are considered to form a consistent set of benchmarks for use in the assessment of summation calculations. (author)

  3. A neutron detector for (p,np) coincidence studies

    CERN Document Server

    Carman, D S; Chant, N S; Eads, A; Gu, T; Huber, G M; Huffman, J; Klyachko, A; Markham, B C; Roos, P G; Schwandt, P; Solberg, K

    1999-01-01

    A neutron detector with moderate energy resolution (approx 3 MeV) has been built for neutrons in the energy range 75-175 MeV. The detector was designed for coincidence scattering experiments. The design eliminates the need for long neutron flight paths necessary for comparable energy resolution time-of-flight measurements with a comparable efficiency-solid angle product (0.02 msr). The detector consists of thin plastic scintillators in which the neutron undergoes n-p elastic scattering. The second-scattered protons are tracked by drift chambers and detected in a sodium iodide array. The design motivations and features are presented along with results from detailed in-beam experimental tests.

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

    International Nuclear Information System (INIS)

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

  5. Coincidences and the encounter problem: A formal account

    CERN Document Server

    Dessalles, Jean-Louis J -L

    2011-01-01

    Individuals have an intuitive perception of what makes a good coincidence. Though the sensitivity to coincidences has often been presented as resulting from an erroneous assessment of probability, it appears to be a genuine competence, based on non-trivial computations. The model presented here suggests that coincidences occur when subjects perceive complexity drops. Co-occurring events are, together, simpler than if considered separately. This model leads to a possible redefinition of subjective probability.

  6. Clifford algebra approach to the coincidence problem for planar lattices.

    Science.gov (United States)

    Rodríguez, M A; Aragón, J L; Verde-Star, L

    2005-03-01

    The problem of coincidences of planar lattices is analyzed using Clifford algebra. It is shown that an arbitrary coincidence isometry can be decomposed as a product of coincidence reflections and this allows planar coincidence lattices to be characterized algebraically. The cases of square, rectangular and rhombic lattices are worked out in detail. One of the aims of this work is to show the potential usefulness of Clifford algebra in crystallography. The power of Clifford algebra for expressing geometric ideas is exploited here and the procedure presented can be generalized to higher dimensions. PMID:15724067

  7. Environmental radiation measurement in CTBT verification system

    International Nuclear Information System (INIS)

    This paper introduces the technical requirements of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) Radionuclide Stations, the CTBT-related activities carried out by the Japan Atomic Energy Research Institute (JAERI), and the ripple effects of such acquired radionuclide data on general researches. The International Monitoring System (IMS), which is one of the CTBT verification regime. Consists of 80 radionuclide air monitoring stations (of those, 40 stations monitor noble gas as well) and 16 certified laboratories that support these stations throughout the world. For radionuclide air monitoring under the CTBT, the stations collect particulates in the atmosphere on a filter and determine by gamma-ray spectrometry the presence or absence of any radionuclides (e.g. 140Ba, 131I, 99Mo, 132Te, 103Ru, 141Ce, 147Nd, 95Zr, etc.) that offer clear evidence of possible nuclear explosion. Minimum technical requirements are stringently set for the radionuclide air monitoring stations: 500 m3/h air flow rate, 24-hour acquisition time, 10 to 30 Bq/m3 of detection sensitivity for 140Ba, and less than 7 consecutive days, or total of 15 days, a year of shutdown at the stations. For noble gas monitoring, on the other hand, the stations separate Xe from gas elements in the atmosphere and, after purifying and concentrating it, measure 4 nuclides, 131mXe, 133Xe, 133mXe, and 135Xe, by gamma-ray spectrometry or beta-gamma coincidence method. Minimum technical requirements are also set for the noble gas measurement: 0.4 m3/h air flow rate, a full capacity of 10 m3, and 1 Bq/m3 of detection sensitivity for 133Xe, etc. On the request of the Ministry of Education, Culture, Sports and Technology, the JAERI is currently undertaking the establishment of the CTBT radionuclide monitoring stations at both Takasaki (both particle and noble gas) and Okinawa (particle), the certified laboratory at JAERI Tokai, and the National Data Center (NDC 2) at JAERI Tokai, which handles radionuclide data, as

  8. Results of the measurement survey of elevation and environmental media in surface impoundments 3513 (B) and 3524 (A) at Oak Ridge National Laboratory, Oak Ridge, TN

    Energy Technology Data Exchange (ETDEWEB)

    Murray, M.E.; Rose, D.A.; Brown, K.S.; Coe, R.H.C. III; Lawrence, J.D.; Winton, W.

    1998-07-01

    A measurement survey of the elevation and environmental media in impoundments 3513 (B) and 3524 (A) at the Oak Ridge National Laboratory (ORNL) was conducted during April 1998. The investigation was performed by the Measurement Applications and Development Group of the Life Sciences Division of ORNL at the request of Bechtel Jacobs Company. Measurement activities were conducted at selected locations in order to determine the depth and appearance of the sediment and describe the clay underlying the impoundments prior to remediation. The survey was a follow-up to a previous elevation survey. The survey included the following: collection of sediment/clay cores from selected locations in each impoundment; measurement and documentation of the elevation at the water surface, at the top of sediment, at the top of clay, and at the bottom of each core; visual inspection of each core by a soil scientist to confirm the presence of clay and not material such as fly ash and soda lime compacted over the last 50 years; measurement and documentation of the background beta-gamma radiation level at the time and location of collection of each core, the highest beta-gamma level along the sediment portion of each core, and the highest beta-gamma level along the clay portion of each core; measurement and documentation of the length of the clay and of the sediment portion of each core; photographic documentation of each core; and replacement of each core in the impoundment.

  9. Coincidence Prompt Gamma-Ray Neutron Activation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    R.P. gandner; C.W. Mayo; W.A. Metwally; W. Zhang; W. Guo; A. Shehata

    2002-11-10

    The normal prompt gamma-ray neutron activation analysis for either bulk or small beam samples inherently has a small signal-to-noise (S/N) ratio due primarily to the neutron source being present while the sample signal is being obtained. Coincidence counting offers the possibility of greatly reducing or eliminating the noise generated by the neutron source. The present report presents our results to date on implementing the coincidence counting PGNAA approach. We conclude that coincidence PGNAA yields: (1) a larger signal-to-noise (S/N) ratio, (2) more information (and therefore better accuracy) from essentially the same experiment when sophisticated coincidence electronics are used that can yield singles and coincidences simultaneously, and (3) a reduced (one or two orders of magnitude) signal from essentially the same experiment. In future work we will concentrate on: (1) modifying the existing CEARPGS Monte Carlo code to incorporate coincidence counting, (2) obtaining coincidence schemes for 18 or 20 of the common elements in coal and cement, and (3) optimizing the design of a PGNAA coincidence system for the bulk analysis of coal.

  10. Recovery and normalization of triple coincidences in PET

    International Nuclear Information System (INIS)

    Purpose: Triple coincidences in positron emission tomography (PET) are events in which three γ-rays are detected simultaneously. These events, though potentially useful for enhancing the sensitivity of PET scanners, are discarded or processed without special consideration in current systems, because there is not a clear criterion for assigning them to a unique line-of-response (LOR). Methods proposed for recovering such events usually rely on the use of highly specialized detection systems, hampering general adoption, and/or are based on Compton-scatter kinematics and, consequently, are limited in accuracy by the energy resolution of standard PET detectors. In this work, the authors propose a simple and general solution for recovering triple coincidences, which does not require specialized detectors or additional energy resolution requirements. Methods: To recover triple coincidences, the authors’ method distributes such events among their possible LORs using the relative proportions of double coincidences in these LORs. The authors show analytically that this assignment scheme represents the maximum-likelihood solution for the triple-coincidence distribution problem. The PET component of a preclinical PET/CT scanner was adapted to enable the acquisition and processing of triple coincidences. Since the efficiencies for detecting double and triple events were found to be different throughout the scanner field-of-view, a normalization procedure specific for triple coincidences was also developed. The effect of including triple coincidences using their method was compared against the cases of equally weighting the triples among their possible LORs and discarding all the triple events. The authors used as figures of merit for this comparison sensitivity, noise-equivalent count (NEC) rates and image quality calculated as described in the NEMA NU-4 protocol for the assessment of preclinical PET scanners. Results: The addition of triple-coincidence events with the

  11. Recovery and normalization of triple coincidences in PET

    Energy Technology Data Exchange (ETDEWEB)

    Lage, Eduardo, E-mail: elage@mit.edu; Parot, Vicente; Dave, Shivang R.; Herraiz, Joaquin L. [Madrid-MIT M+Visión Consortium, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Moore, Stephen C.; Sitek, Arkadiusz; Park, Mi-Ae [Division of Nuclear Medicine, Department of Radiology, Harvard Medical School and Brigham and Women’s Hospital, Boston, Massachusetts 02115 (United States); Udías, Jose M. [Grupo de Física Nuclear, Departamento de Física Atómica Molecular y Nuclear, Universidad Complutense de Madrid, CEI Moncloa, Madrid 28040 (Spain); Vaquero, Juan J. [Departamento de Ingeniería Biomédica e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Leganés 28911 (Spain)

    2015-03-15

    Purpose: Triple coincidences in positron emission tomography (PET) are events in which three γ-rays are detected simultaneously. These events, though potentially useful for enhancing the sensitivity of PET scanners, are discarded or processed without special consideration in current systems, because there is not a clear criterion for assigning them to a unique line-of-response (LOR). Methods proposed for recovering such events usually rely on the use of highly specialized detection systems, hampering general adoption, and/or are based on Compton-scatter kinematics and, consequently, are limited in accuracy by the energy resolution of standard PET detectors. In this work, the authors propose a simple and general solution for recovering triple coincidences, which does not require specialized detectors or additional energy resolution requirements. Methods: To recover triple coincidences, the authors’ method distributes such events among their possible LORs using the relative proportions of double coincidences in these LORs. The authors show analytically that this assignment scheme represents the maximum-likelihood solution for the triple-coincidence distribution problem. The PET component of a preclinical PET/CT scanner was adapted to enable the acquisition and processing of triple coincidences. Since the efficiencies for detecting double and triple events were found to be different throughout the scanner field-of-view, a normalization procedure specific for triple coincidences was also developed. The effect of including triple coincidences using their method was compared against the cases of equally weighting the triples among their possible LORs and discarding all the triple events. The authors used as figures of merit for this comparison sensitivity, noise-equivalent count (NEC) rates and image quality calculated as described in the NEMA NU-4 protocol for the assessment of preclinical PET scanners. Results: The addition of triple-coincidence events with the

  12. Roles for Coincidence Detection in Coding Amplitude-Modulated Sounds

    Science.gov (United States)

    Ashida, Go; Kretzberg, Jutta; Tollin, Daniel J.

    2016-01-01

    Many sensory neurons encode temporal information by detecting coincident arrivals of synaptic inputs. In the mammalian auditory brainstem, binaural neurons of the medial superior olive (MSO) are known to act as coincidence detectors, whereas in the lateral superior olive (LSO) roles of coincidence detection have remained unclear. LSO neurons receive excitatory and inhibitory inputs driven by ipsilateral and contralateral acoustic stimuli, respectively, and vary their output spike rates according to interaural level differences. In addition, LSO neurons are also sensitive to binaural phase differences of low-frequency tones and envelopes of amplitude-modulated (AM) sounds. Previous physiological recordings in vivo found considerable variations in monaural AM-tuning across neurons. To investigate the underlying mechanisms of the observed temporal tuning properties of LSO and their sources of variability, we used a simple coincidence counting model and examined how specific parameters of coincidence detection affect monaural and binaural AM coding. Spike rates and phase-locking of evoked excitatory and spontaneous inhibitory inputs had only minor effects on LSO output to monaural AM inputs. In contrast, the coincidence threshold of the model neuron affected both the overall spike rates and the half-peak positions of the AM-tuning curve, whereas the width of the coincidence window merely influenced the output spike rates. The duration of the refractory period affected only the low-frequency portion of the monaural AM-tuning curve. Unlike monaural AM coding, temporal factors, such as the coincidence window and the effective duration of inhibition, played a major role in determining the trough positions of simulated binaural phase-response curves. In addition, empirically-observed level-dependence of binaural phase-coding was reproduced in the framework of our minimalistic coincidence counting model. These modeling results suggest that coincidence detection of excitatory

  13. Three-particle coincidence of the long range pseudorapidity correlation in high energy nucleus-nucleus collision

    OpenAIRE

    Abelev, B. I.; Braidot, E.; Mischke, A.; Peitzmann, T.(Institute for Subatomic Physics of Utrecht University, Utrecht, Netherlands); van Leeuwen, M.(Institute for Subatomic Physics of Utrecht University, Utrecht, Netherlands)

    2010-01-01

    We report the first three-particle coincidence measurement in pseudorapidity (Δη) between a high transverse momentum (p⊥) trigger particle and two lower p⊥ associated particles within azimuth |Δϕ|

  14. Sustaining IAEA Neutron Coincidence Counting: Past, Present and Future

    International Nuclear Information System (INIS)

    Los Alamos National Laboratory's IAEA Neutron Coincidence Counting (INCC) code is the standard tool for neutron coincidence counting measurements. INCC software and its' predecessors were originally implemented in the 1970s. The measurement and analysis techniques perfected in the code arise from many years of laboratory and field experience by nuclear engineers and physicists. Covering the full arc of INCC's lifecycle, we discuss the engineering approaches used for conception, original development, worldwide deployment of the stand-alone Windows application, more than a decade of sustained maintenance support, and our recent work to carry INCC successfully into future applications. We delve into the recent re-architecture of the INCC code base, an effort to create a maintainable and extensible architecture designed to preserve the existing INCC code base while adding support for new analyzes and instruments (e.g., List Mode PTR-32 and the List Mode Multiplicity Module). INCC now consists of separate modules implementing attended instrumentation control, data file processing, statistical and Pu mass calculation and analyzes, list mode counting and analyzes, reporting functions, and a database support library. Separating functional capabilities in this architecture enables better testing, isolates development risk and enables the use of INCC features in other software systems. We discuss our approach to handling divergent data and protocol support as a result of this re-architecture. INCC has complex testing requirements; we show how the testing effort was reduced by breaking the software into separate modules. This new architecture enables integration of INCC analysis into the IAEA's new Integrated Review and Analysis Programme (iRAP) data review system. iRAP is based on the respected Euratom Comprehensive Review Inspector Software Package (CRISP) software framework, and is expected to be the future data review system for IAEA and Euratom

  15. The effect of deadtime and electronic transients on the predelay bias in neutron coincidence counting

    Science.gov (United States)

    Croft, Stephen; Favalli, Andrea; Swinhoe, Martyn T.; Goddard, Braden; Stewart, Scott

    2016-04-01

    In neutron coincidence counting using the shift register autocorrelation technique, a predelay is inserted before the opening of the (R+A)-gate. Operationally the purpose of the predelay is to ensure that the (R+A)- and A-gates have matched effectiveness, otherwise a bias will result when the difference between the gates is used to calculate the accidentals corrected net reals coincidence rate. The necessity for the predelay was established experimentally in the early practical development and deployment of the coincidence counting method. The choice of predelay for a given detection system is usually made experimentally, but even today long standing traditional values (e.g., 4.5 μs) are often used. This, at least in part, reflects the fact that a deep understanding of why a finite predelay setting is needed and how to control the underlying influences has not been fully worked out. In this paper we attempt to gain some insight into the problem. One aspect we consider is the slowing down, thermalization, and diffusion of neutrons in the detector moderator. The other is the influence of deadtime and electronic transients. These may be classified as non-ideal detector behaviors because they are not included in the conventional model used to interpret measurement data. From improved understanding of the effect of deadtime and electronic transients on the predelay bias in neutron coincidence counting, the performance of both future and current coincidence counters may be improved.

  16. Optical optimization for anti-coincidence detectors of a Hard X-ray Modulation Telescope

    Science.gov (United States)

    Li, Yun-Long; Zhang, Chen; Zhang, Zhao; Fu, Min-Xue; Chen, Yi-Bao; Zhao, Dong-Hua; Deng, Jing-Kang; Shang, Ren-Cheng

    2016-01-01

    The anti-coincidence detectors of Hard X-ray Modulation Telescope (HXMT) are designed to suppress the X-ray background induced by incident charged cosmic-ray particles. The main components of anti-coincidence detectors are thin flat plastic scintillators. In this work we apply the TracePro program to study the light transfer features in the scintillators, and we propose several optimized reflector configurations to significantly improve the light transfer efficiency. The simulation results are verified by measurements of the detector prototypes. We chose a particular optimized reflector configuration.

  17. Determination of relative γ-ray intensities of 106Pd by γ-γ coincidence technique

    International Nuclear Information System (INIS)

    The relative γ-ray intensities of 106Pd have been measured from the γ-γ coincidence spectra obtained by the prompt γ-ray spectroscopic technique. Samples of natural Pd and enriched 105Pd were irradiated with the B-4 thermal neutron guide facilities at Kyoto University Research Reactor Institute (KURRI). Capture prompt γ-rays were detected in both singles and coincidence modes by using two high purity Ge detectors. Based on the γ-γ coincidence data, more than 40 cascading γ-transitions were assigned as these in 106Pd and the partial level-scheme was constructed. Two levels were newly identified. The relative γ-ray intensities of cascading γ-transitions were determined and compared with the compilation data of Brookhaven National Laboratory (BNL). (author)

  18. Two-dimensional diagonal summing of coincidence spectra for bulk PGNAA applications

    Energy Technology Data Exchange (ETDEWEB)

    Metwally, W.A.; Gardner, R.P. E-mail: gardner@ncsu.edu; Mayo, C.W

    2004-06-11

    In the past 10 years, new electronic devices have been developed that allow fast coincidence measurements to be performed that are capable of simultaneously recording the individual spectra as well as the coincidence spectra of multiple detectors. Utilizing these devices with computer software allows multiparameter data acquisition which adds much more flexibility in data analysis. One of the capabilities that is enabled is that of obtaining two-dimensional spectra. In this work, the use of this equipment and the two-dimensional spectra obtained with it are used to allow two-dimensional diagonal summing. The main advantages of this approach are improved peak resolution and very low background (Compton continuum). Possible uses of the two-dimensional diagonal summing are identifying coincidence schemes, performing elemental analysis, and identifying trace elements in bulk samples. The spectra obtained are very promising for these applications.

  19. Two-dimensional diagonal summing of coincidence spectra for bulk PGNAA applications

    Science.gov (United States)

    Metwally, W. A.; Gardner, R. P.; Mayo, C. W.

    2004-06-01

    In the past 10 years, new electronic devices have been developed that allow fast coincidence measurements to be performed that are capable of simultaneously recording the individual spectra as well as the coincidence spectra of multiple detectors. Utilizing these devices with computer software allows multiparameter data acquisition which adds much more flexibility in data analysis. One of the capabilities that is enabled is that of obtaining two-dimensional spectra. In this work, the use of this equipment and the two-dimensional spectra obtained with it are used to allow two-dimensional diagonal summing. The main advantages of this approach are improved peak resolution and very low background (Compton continuum). Possible uses of the two-dimensional diagonal summing are identifying coincidence schemes, performing elemental analysis, and identifying trace elements in bulk samples. The spectra obtained are very promising for these applications.

  20. Moisture corrections in neutron coincidence counting of PuO2

    International Nuclear Information System (INIS)

    Passive neutron coincidence counting is capable of 1% assay accuracy for pure, well-characterized PuO2 samples that contain plutonium masses from a few tens of grams to several kilograms. Moisture in the sample can significantly bias the assay high by changing the (α,n) neutron production, the sample multiplication, and the detection efficiency. Monte Carlo calculations and an analytical model of coincidence counting have been used to quantify the individual and cumulative effects of moisture biases for two PuO2 sample sizes and a range of moisture levels from 0 to 9 wt %. Results of the calculations suggest a simple correction procedure for moisture bias that is effective from 0 to 3 wt % H2O. The procedure requires that the moisture level in the sample be known before the coincidence measurement

  1. Simulations of Lithium-Based Neutron Coincidence Counter for Gd-Loaded Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Cowles, Christian C.; Kouzes, Richard T.; Siciliano, Edward R.

    2014-10-31

    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Lithium-Based Alternative Neutron Detection Technology Coincidence Counting for Gd-loaded Fuels at Pacific Northwest National Laboratory for the development of a lithium-based neutron coincidence counter for nondestructively assaying Gd loaded nuclear fuel. This report provides results from MCNP simulations of a lithium-based coincidence counter for the possible measurement of Gd-loaded nuclear fuel. A comparison of lithium-based simulations and UNCL-II simulations with and without Gd loaded fuel is provided. A lithium-based model, referred to as PLNS3A-R1, showed strong promise for assaying Gd loaded fuel.

  2. Introduction to Neutron Coincidence Counter Design Based on Boron-10

    Energy Technology Data Exchange (ETDEWEB)

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R.

    2012-01-22

    The Department of Energy Office of Nonproliferation Policy (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is ultimately to design, build and demonstrate a boron-lined proportional tube based alternative system in the configuration of a coincidence counter. This report, providing background information for this project, is the deliverable under Task 1 of the project.

  3. Coincidence of Schur Multipliers of the Drury-Arveson Space

    CERN Document Server

    Bhattacharya, Angshuman

    2009-01-01

    In a purely multi-variable setting (i.e., the issues discussed in this note are not interesting in the single variable operator theory setting), we show that the coincidence of two operator valued Schur class multipliers of a certain kind on the Drury-Arveson space is characterized by the fact that the associated colligations (or a variant, obtained canonically) are `unitarily coincident' in a sense to be made precise in the last section of this article.

  4. Configuration-like spaces and coincidences of maps on orbits

    CERN Document Server

    Karasev, R N

    2009-01-01

    In this paper the spaces of $q$-tuples of points in a Euclidean space, without $k$-wise coincidences are studied (configuration-like spaces). A transitive group action by permuting these points is considered, and some new upper bounds on the genus (in the sense of Krasnosel'skii-Schwarz and Clapp-Puppe) for this action are given. Some theorems of Cohen-Lusk type for coincidence points of continuous maps to Euclidean spaces are deduced.

  5. Coincidence rotations of the root lattice $A_4$

    CERN Document Server

    Baake, Michael; Heuer, Manuela; Zeiner, Peter

    2007-01-01

    The coincidence site lattices of the root lattice $A_4$ are considered, and the statistics of the corresponding coincidence rotations according to their indices is expressed in terms of a Dirichlet series generating function. This is possible via an embedding of $A_4$ into the icosian ring with its rich arithmetic structure, which recently (arXiv:math.MG/0702448) led to the classification of the similar sublattices of $A_4$.

  6. Super sub-wavelength patterns in photon coincidence detection

    Science.gov (United States)

    Liu, Ruifeng; Zhang, Pei; Zhou, Yu; Gao, Hong; Li, Fuli

    2014-02-01

    High-precision measurements implemented with light are desired in all fields of science. However, light acts as a wave, and the Rayleigh criterion in classical optics yields a diffraction limit that prevents obtaining a resolution smaller than the wavelength. Sub-wavelength interference has potential application in lithography because it beats the classical Rayleigh resolution limit. Here, we carefully study second-order correlation theory to establish the physics behind sub-wavelength interference in photon coincidence detection. A Young's double slit experiment with pseudo-thermal light is performed to test the second-order correlation pattern. The results show that when two point detectors are scanned in different ways, super sub-wavelength interference patterns can be obtained. We then provide a theoretical explanation for this surprising result, and demonstrate that this explanation is also suitable for the results found for entangled light. Furthermore, we discuss the limitations of these types of super sub-wavelength interference patterns in quantum lithography.

  7. Potential Mars 2001 Sites Coincident with Magnetic Anomalies

    Science.gov (United States)

    Gilmore, M. S.

    1999-01-01

    Of the areas that meet the engineering criteria for MSP 01, only two are coincident with magnetic anomalies measured by the MAG/ER instrument on MGS. Area A is centered on about 10 deg S, 202 deg W and extends from about 7.5 deg S to 15 S. This area is associated with three bands of magnetic anomalies, two with positive values surrounding an area with negative values. Area B corresponds with a circular high positive magnetic anomaly and is centered at 13.5 deg S, 166 deg W. In addition to magnetic anomalies, the proposed sites have other attributes that make then attractive from of standpoint of meeting the objectives of the Mars Program. The landing site candidates meet the engineering requirements outlined on the Mars '01 landing site page htip://mars.jpl.nasa.gov/2001/landingsite. These are (source of data in parentheses): latitude between 3 deg N and 12 deg S, rock abundance between 5-10% (IRTM), fine-component thermal inertia > 4 cgs units (IRTM), topography < 2.5 km (MOLA). There are three exceptions: 1) Area B contains sites that lie up to about 15 deg S, 2) some sites are considered that have rock abundance values of 3-13%. 3) High resolution Viking coverage may not be available. These exceptions will be noted.

  8. Analytical model of coincidence resolving time in TOF-PET.

    Science.gov (United States)

    Wieczorek, H; Thon, A; Dey, T; Khanin, V; Rodnyi, P

    2016-06-21

    The coincidence resolving time (CRT) of scintillation detectors is the parameter determining noise reduction in time-of-flight PET. We derive an analytical CRT model based on the statistical distribution of photons for two different prototype scintillators. For the first one, characterized by single exponential decay, CRT is proportional to the decay time and inversely proportional to the number of photons, with a square root dependence on the trigger level. For the second scintillator prototype, characterized by exponential rise and decay, CRT is proportional to the square root of the product of rise time and decay time divided by the doubled number of photons, and it is nearly independent of the trigger level. This theory is verified by measurements of scintillation time constants, light yield and CRT on scintillator sticks. Trapping effects are taken into account by defining an effective decay time. We show that in terms of signal-to-noise ratio, CRT is as important as patient dose, imaging time or PET system sensitivity. The noise reduction effect of better timing resolution is verified and visualized by Monte Carlo simulation of a NEMA image quality phantom. PMID:27245232

  9. A comparison of cloud motion winds from ATS 6 images with coinciding SMS 1 winds

    Science.gov (United States)

    Kuhlow, W. W.; Chatters, G. C.

    1978-01-01

    A methodology is developed for accurate measurement of cloud motion winds from the geosynchronous ATS 6 image data. Attitude changes between consecutive images (as a function of scan-line number) are accounted for in wind computations through measurement of the earth-edge displacements between the successive infrared images. Also, an image matching procedure is used to remove obvious and distracting image distortions. The availability of SMS imagery coinciding with ATS 6 imagery makes SMS an excellent reference against which the quality of ATS 6 winds can be tested. The resulting winds inferred from cloud displacement measurements taken from a sequence of the corrected images are found to agree better than 2 m/sec rms with winds measured from coincident SMS 1 imagery.

  10. The Anthropic Principle and numerical coincidences involving the cosmological, gravitational and fine structure constants

    CERN Document Server

    Eaves, Laurence

    2014-01-01

    Christian Beck has proposed a set of Shannon-Khinchin axioms to derive a formula for the cosmological constant, {\\Lambda}. We discuss this result in relation to numerical coincidences involving the measured values of {\\Lambda} and the gravitational and fine structure constants, G and {\\alpha}. The empirical formulae that inter-relate the three constants suggest that the measured values of G and {\\Lambda} are consistent with the apparent anthropic fine-tuning of {\\alpha}.

  11. The optimum choice of gate width for neutron coincidence counting

    Energy Technology Data Exchange (ETDEWEB)

    Croft, S., E-mail: crofts@ornl.gov [Safeguards and Security Technology (SST), Global Nuclear Security Technology Divisions, PO Box 2008, Building 5700, MS-6166, Oak Ridge, TN 37831-6166 (United States); Henzlova, D.; Favalli, A.; Hauck, D.K.; Santi, P.A. [Safeguards Science and Technology Group (NEN-1), Nuclear Engineering and Nonproliferation Division, MS-E540, Los Alamos, NM 87545 (United States)

    2014-11-11

    In the measurement field of international nuclear safeguards, passive neutron coincidence counting is used to quantify the spontaneous fission rate of certain special nuclear materials. The shift register autocorrelation analysis method is the most commonly used approach. However, the Feynman-Y technique, which is more commonly applied in reactor noise analysis, provides an alternative means to extract the correlation information from a pulse train. In this work we consider how to select the optimum gate width for each of these two time-correlation analysis techniques. The optimum is considered to be that which gives the lowest fractional precision on the net doublets rate. Our theoretical approach is approximate but is instructional in terms of revealing the key functional dependence. We show that in both cases the same performance figure of merit applies so that common design criteria apply to the neutron detector head. Our prediction is that near optimal results, suitable for most practical applications, can be obtained from both techniques using a common gate width setting. The estimated precision is also comparable in the two cases. The theoretical expressions are tested experimentally using {sup 252}Cf spontaneous fission sources measured in two thermal well counters representative of the type in common use by international inspectorates. Fast accidental sampling was the favored method of acquiring the Feynman-Y data. Our experimental study confirmed the basic functional dependences predicted although experimental results when available are preferred. With an appropriate gate setting Feynman-Y analysis provides an alternative to shift register analysis for safeguards applications which is opening up new avenues of data collection and data reduction to explore.

  12. The optimum choice of gate width for neutron coincidence counting

    International Nuclear Information System (INIS)

    In the measurement field of international nuclear safeguards, passive neutron coincidence counting is used to quantify the spontaneous fission rate of certain special nuclear materials. The shift register autocorrelation analysis method is the most commonly used approach. However, the Feynman-Y technique, which is more commonly applied in reactor noise analysis, provides an alternative means to extract the correlation information from a pulse train. In this work we consider how to select the optimum gate width for each of these two time-correlation analysis techniques. The optimum is considered to be that which gives the lowest fractional precision on the net doublets rate. Our theoretical approach is approximate but is instructional in terms of revealing the key functional dependence. We show that in both cases the same performance figure of merit applies so that common design criteria apply to the neutron detector head. Our prediction is that near optimal results, suitable for most practical applications, can be obtained from both techniques using a common gate width setting. The estimated precision is also comparable in the two cases. The theoretical expressions are tested experimentally using 252Cf spontaneous fission sources measured in two thermal well counters representative of the type in common use by international inspectorates. Fast accidental sampling was the favored method of acquiring the Feynman-Y data. Our experimental study confirmed the basic functional dependences predicted although experimental results when available are preferred. With an appropriate gate setting Feynman-Y analysis provides an alternative to shift register analysis for safeguards applications which is opening up new avenues of data collection and data reduction to explore

  13. Determination of trace elements in scallop and fish otolith by instrumental neutron activation analysis using anti-coincidence and coincidence counting methods

    International Nuclear Information System (INIS)

    Trace element concentrations in scallop reference material and fish otolith certified reference materials prepared at the National Institute for Environmental Studies (NIES) of Japan were determined by instrumental neutron activation analysis (INAA). Nine aliquots of scallop sample (ca. 252∼507 mg) and five aliquots of fish otolith sample (ca. 502 ∼ 988 mg) and comparative standards were irradiated for a short time (10 s) at a thermal neutron flux of 1.5 x 1012 n cm-2s-1 (pneumatic transfer) and for a long time (6 h) at a thermal neutron flux of 3.7 x 1012n cm-2s-1 (central thimble) in the Rikkyo University Research Reactor (100 kW). The irradiated samples were measured by conventional γ-ray spectrometry using a coaxial Ge detector, and by anti-coincidence and coincidence γ-ray spectrometry with a coaxial Ge detector and a well-type NaI (Tl) detector to determine as many trace elements as possible with high sensitivity. The concentrations of 34 elements of the NIES No.15 scallop reference material and 16 elements of the NIES No.22 fish otolith CRM were determined. Using the coincidence counting method to determine Se, Ba and Hf, the lower limit of the determination was improved by 2 times compared with the conventional counting method. (author)

  14. Calculation of coincidence summing corrections for a specific small soil sample geometry

    Energy Technology Data Exchange (ETDEWEB)

    Helmer, R.G.; Gehrke, R.J.

    1996-10-01

    Previously, a system was developed at the INEL for measuring the {gamma}-ray emitting nuclides in small soil samples for the purpose of environmental monitoring. These samples were counted close to a {approx}20% Ge detector and, therefore, it was necessary to take into account the coincidence summing that occurs for some nuclides. In order to improve the technical basis for the coincidence summing corrections, the authors have carried out a study of the variation in the coincidence summing probability with position within the sample volume. A Monte Carlo electron and photon transport code (CYLTRAN) was used to compute peak and total efficiencies for various photon energies from 30 to 2,000 keV at 30 points throughout the sample volume. The geometry for these calculations included the various components of the detector and source along with the shielding. The associated coincidence summing corrections were computed at these 30 positions in the sample volume and then averaged for the whole source. The influence of the soil and the detector shielding on the efficiencies was investigated.

  15. Geometric algorithm for efficient coincident detection of gravitational waves

    International Nuclear Information System (INIS)

    Data from a network of gravitational-wave detectors can be analyzed in coincidence to increase detection confidence and reduce nonstationarity of the background. We propose and explore a geometric algorithm to combine the data from a network of detectors. The algorithm makes optimal use of the variances and covariances that exist among the different parameters of a signal in a coincident detection of events. The new algorithm essentially associates with each trigger ellipsoidal regions in parameter space defined by the covariance matrix. Triggers from different detectors are deemed to be in coincidence if their ellipsoids have a nonzero overlap. Compared to an algorithm that uses uncorrelated windows separately for each of the signal parameters, the new algorithm greatly reduces the background rate thereby increasing detection efficiency at a given false alarm rate.

  16. Implications on the cosmic coincidence by a dynamical extrinsic curvature

    CERN Document Server

    Capistrano, A J S

    2015-01-01

    In this work, we apply the smooth deformation concept in order to obtain a modification of Friedmann equations. It is shown that the cosmic coincidence can be at least alleviated using the dynamical properties of the extrinsic curvature. We investigate the transition from nucleosynthesis to the coincidence era obtaining a very small variation of the ratio $r=\\frac{\\rho_{m}}{\\rho_{ext}}$, that compares the matter energy density to extrinsic energy density, compatible with the known behavior of the deceleration parameter. We also show that the calculated "equivalence" redshift matches the transition redshift from a deceleration to accelerated phase and the coincidence ceases to be. The dynamics on $r$ is also studied based on Hubble parameter observations as the latest Baryons Acoustic Oscillations/Cosmic Microwave Background Radiation (BAO/CMBR) + SNIa.

  17. Performance of Boron-10 based Neutron Coincidence Counters

    International Nuclear Information System (INIS)

    Helium-3 gas-filled detectors have been used in neutron coincidence counting for non-destructive assay for over 30 years. With the current shortage of 3He gas, GE's Reuter-Stokes business developed a 10B lined proportional counter and a 10B hybrid coincidence counter, in which a small amount of 3He is added to a 10B detector to enhance the neutron sensitivity. GE's Reuter-Stokes business modelled, designed, built and tested prototype coincidence counters using the 10B lined detectors and the 10B hybrid detectors. We will present these systems and their applications for non-destructive assay. (author)

  18. CDL, a Precise, Low-Cost Coincidence Detector Latch

    Directory of Open Access Journals (Sweden)

    Ralf Joost

    2015-12-01

    Full Text Available The electronic detection of the coincidence of two events is still a key ingredient for high-performance applications, such as Positron Emission Tomography and Quantum Optics. Such applications are demanding, since the precision of their calculations and thus their conclusions directly depend on the duration of the interval in which two events are considered coincidental. This paper proposes a new circuitry, called coincidence detector latch (CDL, which is derived from standard RS latches. The CDL has the following advantages: low complexity, fully synthesizable, and high scalability. Even in its simple implementation, it achieves a coincidence window width as short as 115 ps, which is more than 10 times better than that reported by recent research.

  19. Coincident Observations of Surface Ozone and NMVOCs over Abu Dhabi

    Science.gov (United States)

    Abbasi, Naveed; Majeed, Tariq; Iqbal, Mazhar; Tarasick, David; Davies, Jonathan; Riemer, Daniel; Apel, Eric

    2016-07-01

    The vertical profiles of ozone are measured coincidently with non-methane volatile organic compounds (NMVOCs) at the meteorological site located at the Abu Dhabi international airport (latitude 24.45N; longitude 54.22E) during the years 2012 - 2014. Some of the profiles show elevated surface ozone >95 ppbv during the winter months (December, January and February). The ground-level NMVOCs obtained from the gas chromatography-flame ionization detection/mass spectrometry system also show elevated values of acetylene, ethane, propane, butane, pentane, benzene, and toluene. NMVOCs and ozone abundances in other seasons are much lower than the values in winter season. NMVOCs are emitted from an extensive number of sources in urban environments including fuel production, distribution, and consumption, and serve as precursor of ozone. Transport sources contribute a substantial portion of the NMVOC burden to the urban atmosphere in developed regions. Abu Dhabi is located at the edge of the Arabian Gulf and is highly affected by emissions from petrochemical industries in the neighboring Gulf region. The preliminary results indicate that wintertime enhancement in ozone is associated with large values of NMVOCs at Abu Dhabi. The domestic production of surface ozone is estimated from the combination of oxygen recombination and NMVOCs and compared with the data. It is estimated that about 40-50% of ozone in Abu Dhabi is transported from the neighbouring petrochemical industries. We will present ozone sounding and NMVOCs data and our model estimates of surface ozone, including a discussion on the high levels of the tropospheric ozone responsible for contaminating the air quality in the UAE. This work is supported by National Research Foundation, UAE.

  20. Automatic classification of gammas-gamma coincidence matrices

    International Nuclear Information System (INIS)

    The information obtained during a coincidence experiment, recorded on magnetic tape by a MULTI-8 minicomputer, is transferred to a new tape in 36 bit words, using the program LEC0M8. The classification in two dimensional matrix form is carried out off-line, on a magnetic disk file, by the program CLAFI. On finishing classification one obtains a copy of the coincidence matrix on the second magnetic tape. Both programs are written to be processed in that order with the UNIVAC 1106 computer of J.E.N. (Author) 4 refs

  1. Automatic classification of gamma-gamma coincidence matrices

    International Nuclear Information System (INIS)

    The information obtained during a coincidence experiment, recorded on magnetic tape by a Multi-8 minicomputer, is transferred to a new tape in 36 bit words, using the program Lecom8. The classification in two dimensional matrix form is carried out off-line, on a magnetic disk file, by the program Clafi. On finishing classification one obtains a copy of the coincidence matrix on the second magnetic tape. Both programs are written to be processed in that order with the Univac 1106 computer of J.E.N. (author)

  2. Standardization of portable assay instrumentation: the neutron-coincidence tree

    International Nuclear Information System (INIS)

    Standardization of portable neutron assay instrumentation has been achieved by using the neutron coincidence technique as a common basis for a wide range of instruments and applications. The electronics originally developed for the High-Level Neutron Coincidence Counter has been adapted to both passive- and active-assay instrumentation for field verification of bulk plutonium, inventory samples, pellets, powders, nitrates, high-enriched uranium, and materials-testing-reactor, light-water-reactor, and mixed-oxide fuel assemblies. The family of detectors developed at Los Alamos National Laboratory and their performance under in-field conditions are described. 16 figures, 3 tables

  3. Unattended mode monitoring of passive neutron coincidence detector systems using a commercial data logger

    International Nuclear Information System (INIS)

    A commercial Data Logger for unattended passive neutron coincidence data acquisition is described. This consists of an inexpensive commercial Data Logging equipment attached to a neutron coincidence electronics and a software package for data review. The Data Logger permits both the flexible configuration of a passive neutron coincidence measurement system for unattended mode monitoring and the storage of the measured Totals and Reals count rates. An additional feature of the Data Logger is a custom software package providing for the complete analysis of the stored data and yielding an assay of each item passing through the measurement cavity. The analysis includes an input for different isotopic compositions, the calculation of the multiplication corrected Reals rates, the inclusion of a calibration functions, and the determination of240Pu masses. The software package for data review displays the Totals and Reals count rates logged by the Data Logger as a function of time. In addition the custom software provides input files to the data review package to display the multiplication corrected Reals count rates and the measured 240Pu masses as a function of time. Information on the Data Logger is presented along with the monitoring mode specifications. The analysis functions implemented are described as is the data review software. Results are presented for a specific application

  4. Control of the mass of a plutonium sample by neutron coincidences with correction of induced fissions

    International Nuclear Information System (INIS)

    When the isotopic composition of nuclear materials to control is known, it is possible to determine the amount of plutonium by measuring the rate of spontaneous fissions. The induced fissions alter significantly the measures. Therefore we must evaluate the multiplicative factor. For a not very multiplicative sample, the observed neutron coincidences of multiplicity 0 to n agree with spontaneous emissions given by nuclear tables. This is not true in the opposite case (large amounts). Multiplicities are given by eighteen counting-scales associated with a shift-register coincidence system (SCRD) and compared with theoretical spontaneous emissions of the sample. A calculator leads all equipment and compares theoretical and experimental results about the controlled amount of Pu

  5. Chiral asymmetry in the multiphoton ionization of methyloxirane using femtosecond electron-ion coincidence imaging.

    Science.gov (United States)

    Rafiee Fanood, Mohammad M; Powis, Ivan; Janssen, Maurice H M

    2014-12-11

    Multiphoton photoelectron circular dichroism (MP-PECD) has been observed as an asymmetry in the angular distribution of photoelectrons emitted in the ionization of pure enantiomers of the small chiral molecule methyloxirane using a femtosecond laser operated at 420 nm. Energetically, this requires the uptake of four photons. By switching the laser between left- and right-circular polarization, and observing the differences in the full three-dimensional electron momentum distribution recorded in an electron-ion coincidence technique, the chiral (odd) terms in the angular distribution expression can be isolated. Electron events can additionally be filtered by coincident ion mass, providing mass-tagged electron distributions and quantitative measures of the MP-PECD asymmetry that help characterize the different ionization channels. For the production of ground state parent cation, the magnitude of the mean chiral asymmetry is measured to be 4.7%, with a peak magnitude exceeding 10% PMID:25402546

  6. Design of a liquid scintillator-based prototype neutron coincidence counter for Nuclear Safeguards

    International Nuclear Information System (INIS)

    A liquid scintillator-based neutron coincidence counting system designed to address a number of safeguards applications is under development by the IAEA in collaboration with the Joint Research Centre-ITU and Hybrid Instruments LTD. Liquid scintillators are a promising technology due to their good fast-neutron detection capabilities. The characteristic fast response of scintillators is particularly beneficial for coincidence counting applications, for which a performance level higher than that associated with moderated thermal detectors might be expected. Fast neutron detection requires no thermalization process and therefore, does not incur the resulting neutron detection delays. These features reduce the length of the coincidence gate by three orders of magnitude, reducing practically to negligible values the accidental coincidence rate which dominates the uncertainty in thermal neutron detectors. Recent progress in fast electronic digitizers offers the possibility to perform on-line, real-time pulse shape discrimination (PSD) between gamma and neutron radiation detection, making this technology suitable for nuclear safeguards and security applications. This paper will describe the experiments and Monte Carlo modelling activities engaged to design a prototype liquid scintillator-based neutron coincidence collar for fresh fuel assembly verification. The characterization of the system response required accurate calibration measurements in order to determine the operational parameters of the liquid scintillator cell, including gain, pulse shape discrimination and energy thresholds. Extensive Monte Carlo simulations which are essential for the understanding and characterization of the system’s response were also carried out using the MCNPX-PoliMi Monte Carlo code to simulate the radiation transport within the system and to optimize the detector design. The evolution from the different detector configurations we investigated to the characteristic features of the

  7. Detector description and performance for the first coincidence observations between LIGO and GEO

    OpenAIRE

    Abbott, B.; Abbott, F.; Adhikari, R.; Ageev, A.; Allen, B.; R. Amin; Anderson, S; Anderson, W.; Araya, M; Armandula, H.; Asiri, F.; Aufmuth, P.; Aulbert, C.; Babak, S; Balasubramanian, R.

    2004-01-01

    For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis p...

  8. Two-photon coincident-frequency-entanglement via extended phase matching

    OpenAIRE

    Kuzucu, Onur; Fiorentino, Marco; Albota, Marius A.; Wong, Franco N. C.; Kaertner, Franz X.

    2004-01-01

    We demonstrate a new class of frequency-entangled states generated via spontaneous parametric down-conversion under extended phase matching conditions. Biphoton entanglement with coincident signal and idler frequencies is observed over a broad bandwidth in periodically poled KTiOPO$_4$. We demonstrate high visibility in Hong-Ou-Mandel interferometric measurements under pulsed pumping without spectral filtering, which indicates excellent frequency indistinguishability between the down-converte...

  9. Dark-Energy Dynamics Required to Solve the Cosmic Coincidence

    CERN Document Server

    Egan, Chas A

    2007-01-01

    Dynamic dark energy (DDE) models are often designed to solve the cosmic coincidence (why, just now, is the dark energy density $\\rho_{de}$, the same order of magnitude as the matter density $\\rho_m$?) by guaranteeing $\\rho_{de} \\sim \\rho_m$ for significant fractions of the age of the universe. This typically entails ad-hoc tracking or oscillatory behaviour in the model. However, such behaviour is neither sufficient nor necessary to solve the coincidence problem. What must be shown is that a significant fraction of observers see $\\rho_{de} \\sim \\rho_m$. Precisely when, and for how long, must a DDE model have $\\rho_{de} \\sim \\rho_{m}$ in order to solve the coincidence? We explore the coincidence problem in dynamic dark energy models using the temporal distribution of terrestrial-planet-bound observers. We find that any dark energy model fitting current observational constraints on $\\rho_{de}$ and the equation of state parameters $w_0$ and $w_a$, does have $\\rho_{de} \\sim \\rho_m$ for a large fraction of observer...

  10. AdS/CFT correspondence and coincident D-6-branes

    OpenAIRE

    Ketov, Sergei V.

    1998-01-01

    A relation between confinement and Maldacena conjecture is briefly discussed. The gauge symmetry enhancement for two coincident D-6-branes is analyzed from the viewpoint of the hypermultiplet low-energy effective action given by the N=2 supersymmetric non-linear sigma-model with the Eguchi-Hanson (ALE) target space.

  11. Linear optical controlled-NOT gate in the coincidence basis

    International Nuclear Information System (INIS)

    We describe the operation and tolerances of a nondeterministic, coincidence basis, quantum controlled-NOT gate for photonic qubits. It is constructed solely from linear optical elements and requires only a two-photon source for its demonstration. Its success probability is 1/9

  12. Proposed mechanisms for coincidence detection in the auditory brainstem

    Czech Academy of Sciences Publication Activity Database

    Maršálek, Petr; Lánský, Petr

    2005-01-01

    Roč. 92, č. 6 (2005), s. 445-451. ISSN 0340-1200 R&D Projects: GA AV ČR 1ET400110401 Institutional research plan: CEZ:AV0Z50110509 Keywords : neuronal modeling * coincidence detection * hearing Subject RIV: ED - Physiology Impact factor: 1.398, year: 2005

  13. Coincidence and fixed points for compatible and relatively nonexpansive maps

    Directory of Open Access Journals (Sweden)

    Gerald Jungck

    1993-03-01

    Full Text Available The concept of relatively nonexpansive maps is introduced. Fixed point and coincidence results for families of four self maps of metric spaces are obtained. Non-continuous compatible and relatively nonexpansive maps on star-shaped compact subsets of normed linear spaces are highlighted, and two theorems of Dotson are generalized.

  14. Coincidence and fixed points for compatible and relatively nonexpansive maps

    OpenAIRE

    Gerald Jungck

    1993-01-01

    The concept of relatively nonexpansive maps is introduced. Fixed point and coincidence results for families of four self maps of metric spaces are obtained. Non-continuous compatible and relatively nonexpansive maps on star-shaped compact subsets of normed linear spaces are highlighted, and two theorems of Dotson are generalized.

  15. AdS/CFT correspondence and coincident D-6-branes

    International Nuclear Information System (INIS)

    A relation between confinement and Maldacena conjecture is briefly discussed. The gauge symmetry enhancement for two coincident D-6-branes is analyzed from the viewpoint of the hypermultiplet low-energy effective action given by the N=2 supersymmetric non-linear sigma-model with the Eguchi-Hanson (ALE) target space. (orig.)

  16. Development of a TES-Based Anti-Coincidence Detector for Future X-ray Observatories

    Science.gov (United States)

    Bailey, Catherine

    2011-01-01

    Microcalorimeters onboard future x-ray observatories require an anti-coincidence detector to remove environmental backgrounds. In order to most effectively integrate this anticoincidence detector with the main microcalorimeter array, both instruments should use similar read-out technology. The detectors used in the Cryogenic Dark Matter Search (CDMS) use a phonon measurement technique that is well suited for an anti-coincidence detector with a microcalorimeter array using SQUID readout. This technique works by using a transition-edge sensor (TES) connected to superconducting collection fins to measure the athermal phonon signal produced when an event occurs in the substrate crystal. Energy from the event propagates through the crystal to the superconducting collection fins, creating quasiparticles, which are then trapped as they enter the TES where they produce a signal. We are currently developing a prototype anti-coincidence detector for future x-ray missions and have recently fabricated test devices with Mo/Au TESs and Al collection fins. We will present results from the first tests of these devices which indicate a proof of concept that quasiparticle trapping is occurring in these materials.

  17. Development of a TES-Based Anti-Coincidence Detector for Future X-Ray Observations

    Science.gov (United States)

    Bailey, Catherine N.; Adams, J. S.; Bandler, S. R.; Eckart, M. E.; Ewin, A. J.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.; Sadleir, J. E.; Smith, S. J.; Sultana, M.

    2012-01-01

    Microcalorimeters onboard future x-ray observatories require an anticoincidence detector to remove environmental backgrounds. In order to most effectively integrate this anti-coincidence detector with the main microcalorimeter array, both instruments should use similar read-out technology. The detectors used in the Cryogenic Dark Matter Search (CDMS) use a phonon measurement technique that is well suited for an anti-coincidence detector with a microcalorimeter array using SQUID readout. This technique works by using a transition-edge sensor (TES) connected to superconducting collection fins to measure the athermal phonon signal produced when an event occurs in the substrate crystal. Energy from the event propagates through the crystal to the superconducting collection fins, creating quasiparticles, which are then trapped as they enter the TES where they produce a signal. We are currently developing a prototype anti-coincidence detector for future x-ray missions and have recently fabricated test devices with Mo/Au TESs and Al collection fins. We present results from the first tests of these devices which indicate a proof of concept that quasiparticle trapping is occurring in these materials.

  18. Planned search for LIGO-GBM coincidence in the first advanced LIGO data run

    CERN Document Server

    Camp, Jordan; Briggs, Michael; Christensen, Nelson; Connaughton, Valerie; Singer, Leo; Shawhan, Peter; Veitch, John

    2015-01-01

    In the fall of 2015 the first scientific observing run (O1) of the advanced LIGO detectors will be conducted. Based on the recent commissioning progress at the LIGO Hanford and Livingston sites, the gravitational wave detector range for a neutron star binary inspiral is expected to be of order 60 Mpc. We describe here our planning for an O1 search for coincidence between a LIGO gravitational wave detection and a gamma-ray signal from the Fermi Gamma-ray Burst Monitor. Such a coincidence would constitute measurement of an electromagnetic counterpart to a gravitational wave signal, with significant corresponding scientific benefits, including revealing the central engine powering the gamma-ray burst, enhanced confidence in the event as a genuine astrophysical detection, and a determination of the relative speed of the photon and graviton.

  19. A Bayesian coincidence test for noise rejection in a gravitational-wave burst search

    Energy Technology Data Exchange (ETDEWEB)

    Cannon, Kipp C [LIGO Laboratory 18-34, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125 (United States)], E-mail: kcannon@ligo.caltech.edu

    2008-05-21

    In searches for gravitational-wave bursts, a standard technique used to reject noise is to discard burst event candidates that are not seen in coincidence in multiple detectors. A coincidence test in which Bayesian inference is used to measure how noise-like a tuple of events appears is presented here. This technique is shown to yield higher detection efficiencies for a given false alarm rate than do techniques based on per-parameter thresholds when applied to a toy model covering a broad class of event candidate populations. Also presented is the real-world example of a use of the technique for noise rejection in a time-frequency burst search conducted on simulated gravitational-wave detector data. Besides achieving a higher detection efficiency, the technique is significantly less challenging to implement well than is a per-parameter threshold method.

  20. Application of Triple Coincidence for the Detection of Small Amounts of Special Nuclear Materials

    Energy Technology Data Exchange (ETDEWEB)

    DIOSZEGI, I.; Salwen, C.; and Forman, L.

    2011-06-12

    We constructed a device that measures two {gamma}-rays and one neutron from spontaneous fission and any resulting multiplication chains. It extends the associated particle technique based upon correlated counting of the multiplicity of gamma-rays and neutrons released in spontaneous- or neutron-induced fission. There are two advantages in incorporating a third detector in the design over the standard two-detector version. First, we found that random uncorrelated events dominate the background of coincident counting with a gamma-ray- and neutron-detector. These might be suppressed by requiring an additional coincidence. Second, the time history of gamma-ray emission between the two gamma-ray detectors is related to multiplication in the target media. Multiplication in highly enriched uranium is much greater than in depleted uranium.

  1. A two-dimensional extrapolation for the standardization of 201Tl by the 4πβ-τ coincidence method

    International Nuclear Information System (INIS)

    201TL has been standardized by 4πβ-τ coincidence measurements using one- and two-dimensional extrapolation. An analysis of the various contributions to the count rate of the β channel is made and it is shown that due to low-energy conversion electrons two-dimensional extrapolation is preferable. Several measurements have been performed under various conditions with a coincidence system consisting of a Ge detector or a NaI crystal for the detection of τ rays and a pressurized proportional counter for the detection of the x rays and Auger electrons from electron capture. (author)

  2. Two-dimensional extrapolation for the standardization of /sup 201/Tl by the 4. pi beta. -tau coincidence method

    Energy Technology Data Exchange (ETDEWEB)

    Funck, E.

    1987-01-01

    /sup 201/TL has been standardized by 4..pi beta..-tau coincidence measurements using one- and two-dimensional extrapolation. An analysis of the various contributions to the count rate of the ..beta.. channel is made and it is shown that due to low-energy conversion electrons two-dimensional extrapolation is preferable. Several measurements have been performed under various conditions with a coincidence system consisting of a Ge detector or a NaI crystal for the detection of tau rays and a pressurized proportional counter for the detection of the x rays and Auger electrons from electron capture.

  3. Safeguards Technology Factsheet 3He-free Neutron Coincidence Counter

    International Nuclear Information System (INIS)

    A full scale thermal neutron coincidence counter (High Level Neutron Counter - Boron: HLNB) based on 3He alternative detection technology was designed and built at LANL and field tested at Plutonium Conversion Development Facility (PCDF) of Japan Atomic Energy Agency (JAEA) during FY15. HLNB is based on boron-lined proportional plates that replace the traditional 3He proportional tubes and was designed as a direct alternative to 3He-based High Level Neutron Coincidence Counter (HLNC-II). During the JAEA field trial the HLNB demonstrated comparable performance to HLNC-II, which represents a key development in the area of 3He alternative technologies and provides a complete demonstration of the technology for nuclear safeguards applications including high mass MOX samples.

  4. Coincidence Detection Using Spiking Neurons with Application to Face Recognition

    OpenAIRE

    Fadhlan Kamaruzaman; Amir Akramin Shafie; Yasir M. Mustafah

    2015-01-01

    We elucidate the practical implementation of Spiking Neural Network (SNN) as local ensembles of classifiers. Synaptic time constant τs is used as learning parameter in representing the variations learned from a set of training data at classifier level. This classifier uses coincidence detection (CD) strategy trained in supervised manner using a novel supervised learning method called τs Prediction which adjusts the precise timing of output spikes towards the desired spike timing through itera...

  5. Photon–photon coincidence apparatus with position sensitive detectors

    International Nuclear Information System (INIS)

    An apparatus for the coincident detection of two photons in the visible and VUV spectral range is presented equipped with two position- and time resolving detectors. The equipment enables angular resolution for the detected photons and thus allows an angular correlation between the two detected photons without changing the target cell geometry. Two different configurations of this apparatus are presented and compared in terms of solid angle coverage, imaging properties and suitability for their use in gas phase experiments at synchrotron radiation facilities

  6. The elimination of prompt components in delayed coincidence time distributions

    International Nuclear Information System (INIS)

    In the centroid-shift analysis of a delayed coincidence time distribution, an unknown prompt component may considerably influence the result. A new procedure is proposed to quantitatively identify and eliminate the prompt component in a complex time distribution provided the shape of the experimental apparatus response function is known. The procedure uses some features of the realistic complex distribution. Practical applications to experimental data obtained in different reactions with germanium detectors are demonstrated. (orig.)

  7. A coincidence of addiction to "Kratom" and severe primary hypothyroidism.

    Science.gov (United States)

    Sheleg, Sergey V; Collins, Gregory B

    2011-12-01

    Here we present a case of a coincidence of addiction to "Kratom" (botanically known as Mitragyna speciosa Korth) and developed severe primary hypothyroidism. We are discussing a possibility that high dose of indole alkaloid mitragynine (the major alkaloid identified from "Kratom") might reduce the normal response of the thyroid gland to thyroid-stimulating hormone resulting in primary hypothyroidism. Further experimental investigations of mitragynine as a possible suppressor of thyroid gland function would be a matter of interest. PMID:21817918

  8. ECOLOGIC CRISIS AND ECONOMIC CRISIS. IS IT A COINCIDENCE?

    OpenAIRE

    Ştefania-Diana Ioniţă-Burda; Cristian Giuseppe Zaharie; Oana-Elena Mitran-Costache

    2011-01-01

    We constantly speak about the crisis, a phenomenon which characterizes both the individual and the society. The individual is always in a crisis of time,inspiration etc. In turn, society undergoes periods of ecologic, economic, financial,social, political crisis. From among crisis forms, two of them are particularly worth noticing: the ecologic crisis and the economic crisis. Could their coexistence be a mere coincidence or maybe …?

  9. Elimination of prompt components in delayed coincidence time distributions

    Energy Technology Data Exchange (ETDEWEB)

    Petkov, P.; Andrejtscheff, W.; Kostov, L.K.; Kostova, L.G.

    1988-09-01

    In the centroid-shift analysis of a delayed coincidence time distribution, an unknown prompt component may considerably influence the result. A new procedure is proposed to quantitatively identify and eliminate the prompt component in a complex time distribution provided the shape of the experimental apparatus response function is known. The procedure uses some features of the realistic complex distribution. Practical applications to experimental data obtained in different reactions with germanium detectors are demonstrated.

  10. Coincidence Theorems for Certain Classes of Hybrid Contractions

    Directory of Open Access Journals (Sweden)

    Singh SL

    2010-01-01

    Full Text Available Coincidence and fixed point theorems for a new class of hybrid contractions consisting of a pair of single-valued and multivalued maps on an arbitrary nonempty set with values in a metric space are proved. In addition, the existence of a common solution for certain class of functional equations arising in dynamic programming, under much weaker conditions are discussed. The results obtained here in generalize many well known results.

  11. The 8 Coincidences of Galaxy Photometry - Selection Effects

    Science.gov (United States)

    Disney, M. J.; Phillipps, S.

    When the photometric properties of significant numbers of galaxies are compared, eight remarkable coincidences turn up. No convincing explanation for these have appeared so far. However, it may be that they can all be explained through a single powerful selection effect which brings into prominence only galaxies of certain favourable surface brightnesses. If that is the case, then our current understanding of galaxy populations is a delusion, and there must be many more galaxies about than we presently assume.

  12. Non-minimal quintessence: Dynamics and coincidence problem

    Indian Academy of Sciences (India)

    Fatimah Shojai; Ali Shojai

    2011-12-01

    Brans–Dicke scalar–tensor theory provides a conformal coupling of the scalar field with gravity in Einstein’s frame. This model is equivalent to an interacting quintessence in which dark matter is coupled to dark energy. This provides a natural mechanism to alleviate the coincidence problem. We investigate the dynamics of this model and show that it leads to comparable dark energy and dark matter densities today.

  13. The ZEPLIN-III Anti-Coincidence Veto Detector

    OpenAIRE

    Akimov, D. Yu.; Araujo, H. M.; Barnes, E. J.; Belov, V. A.; Burenkov, A. A.; Chepel, V.; Currie, A.; B. Edwards; Francis, V.; Ghag, C.; Hollingsworth, A; M Horn; Kalmus, G. E.; Kobyakin, A. S.; Kovalenko, A. G.

    2010-01-01

    The design, optimisation and construction of an anti-coincidence veto detector to complement the ZEPLIN-III direct dark matter search instrument is described. One tonne of plastic scintillator is arranged into 52 bars individually read out by photomultipliers and coupled to a gadolinium-loaded passive polypropylene shield. Particular attention has been paid to radiological content. The overall aim has been to achieve a veto detector of low threshold and high efficiency without the creation of...

  14. Non-minimal Quintessence: Dynamics and coincidence problem

    OpenAIRE

    Shojai, Fatimah; Shojai, Ali

    2011-01-01

    Brans--Dicke scalar--tensor theory provides a conformally coupling of the scalar field with gravity in Einstein's frame. This model is equivalent to an interacting quintessence in which dark matter is coupled to dark energy. This provides a natural mechanism to alleviate the coincidence problem. We investigate the dynamics of this model and show that it leads to comparable dark energy and dark matter densities today.

  15. The coincidence of dementia and intracranial tumours. Avoidable misdiagnosis

    International Nuclear Information System (INIS)

    The case of a 66-year-old female suffering from a large olfactory groove meningioma with first diagnosis of 'Alzheimer's disease' exemplifies problems that occur in the differential diagnosis of dementia. Special regard is given to the coincidence of dementia and intracranial tumours. The case described above shows that early neuroimaging is advisable to exclude idiopathic from remediable dementias in order to offer the possibility of intervention. (orig.)

  16. A digital Compton suppression spectroscopy without gamma-ray coincidence-summing loss using list-mode multispectral data acquisition

    International Nuclear Information System (INIS)

    The study demonstrates the advantages of an innovative list-mode multispectral data acquisition system that allows simultaneous creation of several different single, summed, coincident and anticoincident spectra with a single measurement. One of the consequences of list-mode data file offline processing is a reconstructed spectrum with Compton continuum suppression and without any full-energy peak efficiency deduction owing to true coincidence summing. The spectrometer is designed to read out analogue signal from preamplifier of gamma-ray detectors and to digitalize it using DGF/Pixie-4 software and card package (XIA LLC). This is realized by converting an Ortec Compton suppression data acquisition system into an all-digital spectrometer. Instead of using its timing electronic chain to determine the coincidence event, the analog signals from primary and guard detectors were connected directly into the Pixie-4 card for pulse height and time coincident measurement by individually logging and time stamping each electronic pulse. The data acquired in list-mode included coincidence and anticoincidence events consisting of records of energy and timestamp from primary and guard detectors. Every event was stored in a text file for offline processing and spectral reconstruction. A sophisticated computer simulation was also created with the goals of obtaining a better understanding of the experimental results and calculating efficiency. (author)

  17. The Theory of Electron-Scattering Coincidence Experiments.

    Science.gov (United States)

    Kleppinger, William Earl

    A general theoretical formalism for coincidence electron scattering from a nuclear target has been developed within the one-photon exchange approximation. The unpolarized cross section is expressed in terms of four combinations of the nuclear transition matrix elements. The helicity analysis of Jacob and Wick is used to decompose the transition matrix elements into amplitudes of definite angular momentum. For massive particles, a transformation can be made to LS coupling states for the coincident particle and final nucleus. Tables of angular correlation coefficients relating the transition amplitudes to the required combinations of current matrix elements are given for the case where the target has spin zero. They constitute one of our most useful new results. These results depend only on the existence of a local nuclear current operator and general invariance principles. In the limit of heavy, localized initial and final nuclei, and assuming that the reaction proceeds through an intermediate resonance, connection can be made to the singles inelastic cross section. The aforementioned coefficients can also be used in this limit. The relationship to previous work is also indicated. The general formalism is next applied to the one -Z-boson exchange graph in the Weinberg-Salam model. This allows for a study of parity-violating effects from the interference of the neutral weak and electromagnetic currents. The general coincidence cross section with polarized incident electrons is derived. The helicity analysis is then used to express the eight combinations of transition matrix elements which appear in terms of inelastic multipole matrix elements. Finally, we present some examples to illustrate the formalism. We find that the angular distribution of the coincident particle is. characterized by the angular momentum of the intermediate. resonance. Lastly, we reanalyze the data of Calarco et al. for. coincidence electron scattering from a carbon -twelve target,. retaining

  18. Frequencies of mutagen-induced coincident mitotic recombination at unlinked loci in Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, Kathryn M. [Department of Biology, College of the Holy Cross, One College Street, Worcester, MA 01610-2395 (United States); Hoffmann, George R. [Department of Biology, College of the Holy Cross, One College Street, Worcester, MA 01610-2395 (United States)]. E-mail: ghoffmann@holycross.edu

    2007-03-01

    Frequencies of coincident genetic events were measured in strain D7 of Saccharomyces cerevisiae. This diploid strain permits the detection of mitotic gene conversion involving the trp5-12 and trp5-27 alleles, mitotic crossing-over and gene conversion leading to the expression of the ade2-40 and ade2-119 alleles as red and pink colonies, and reversion of the ilv1-92 allele. The three genes are on different chromosomes, and one might expect that coincident (simultaneous) genetic alterations at two loci would occur at frequencies predicted by those of the single alterations acting as independent events. Contrary to this expectation, we observed that ade2 recombinants induced by bleomycin, {beta}-propiolactone, and ultraviolet radiation occur more frequently among trp5 convertants than among total colonies. This excess among trp5 recombinants indicates that double recombinants are more common than expected for independent events. No similar enrichment was found among Ilv{sup +} revertants. The possibility of an artifact in which haploid yeasts that mimic mitotic recombinants are generated by a low frequency of cryptic meiosis has been excluded. Several hypotheses that can explain the elevated incidence of coincident mitotic recombination have been evaluated, but the cause remains uncertain. Most evidence suggests that the excess is ascribable to a subset of the population being in a recombination-prone state.

  19. Development of neutron coincidence counting simulation code based on open-source simulation code

    International Nuclear Information System (INIS)

    Nuclear Material Control Center has used the open-source simulation code called MCNP (A General Monte Carlo N-Particle Transport Code) version 4B, which is developed by Los Alamos National Laboratory, to develop NDA detectors based on coincidence neutron counting and to have an initial estimation for their performance. However, the MCNP does not have the function to simulate coincidence neutrons because the code can not generate several number of neutron particles associated with a fission event, and also it can not simulate neutrons emitted with Poisson distribution like behavior in nature. For these reasons, new functions were added to the code to result in output of detection point, detection time, incident direction, and neutron energy detected. And also a calculation program was developed to estimate coincidence counts from these outputs. Simulation results with the developed code were compared with actual results to adjust bias. In the paper, new functions added to the code and comparison of calculation data with actual measurement data are presented. (author)

  20. Frequencies of mutagen-induced coincident mitotic recombination at unlinked loci in Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Frequencies of coincident genetic events were measured in strain D7 of Saccharomyces cerevisiae. This diploid strain permits the detection of mitotic gene conversion involving the trp5-12 and trp5-27 alleles, mitotic crossing-over and gene conversion leading to the expression of the ade2-40 and ade2-119 alleles as red and pink colonies, and reversion of the ilv1-92 allele. The three genes are on different chromosomes, and one might expect that coincident (simultaneous) genetic alterations at two loci would occur at frequencies predicted by those of the single alterations acting as independent events. Contrary to this expectation, we observed that ade2 recombinants induced by bleomycin, β-propiolactone, and ultraviolet radiation occur more frequently among trp5 convertants than among total colonies. This excess among trp5 recombinants indicates that double recombinants are more common than expected for independent events. No similar enrichment was found among Ilv+ revertants. The possibility of an artifact in which haploid yeasts that mimic mitotic recombinants are generated by a low frequency of cryptic meiosis has been excluded. Several hypotheses that can explain the elevated incidence of coincident mitotic recombination have been evaluated, but the cause remains uncertain. Most evidence suggests that the excess is ascribable to a subset of the population being in a recombination-prone state

  1. Verification of light & radiation field coincidence quality assurance for radiation therapy by using a-Se based DR system

    Science.gov (United States)

    Kim, Jin-Young; Park, Eun-Tae; Choi, Yun-Seon; Cho, Heung-Lae; Ahn, Ki-Jung; Park, Sung-Kwang; Kim, Ji-Na; Suh, Tae-Suk; Kim, Jin-Seon; Hong, Ju-Yeon; Park, Jeong-Eun; Kim, Kyo-Tae; Oh, Kyung-Min; Kim, Hyunjung; Jo, Sun-Mi; Oh, Won-Yong; Jin, Seong-Jin; Cho, Woong

    2015-04-01

    Currently, the American Association of Physicists in Medicine (AAPM) recommends measuring the surface field size once a week by using an analog film in order to verify light and radiation field coincidence in the Quality Assurance (QA) of radiotherapy. However, the use of the film does not allow for a quantitative method of evaluation, and measuring the light field with radiation field detectors in a 2D array is difficult. Therefore, we used an amorphous-Se (a-Se) digital radiation detection system to measure the light and radiation fields simultaneously for a quantitative QA system, and the feasibility of using such a system was confirmed by ensuring the coincidence of the light and the radiation field measurements. The characteristics of the analog film and the a-Se digital radiation detection system were compared by delivering to each doses of 100, 10 monitor units(MU) of radiation at a rate of 400 MU/min to a radiation field 100 × 100 mm2 in size from a 100 cm source-surface distance (SSD). A 0.5 mm to 0.6 mm difference was measured in the X-axis, and a 0.3 mm difference was measured in the Y-axis. The difference in the measurements of the coincidence of light and the radiation field was less than 0.3 mm, which is relatively insignificant. These results indicate that the use of an a-Se digital radiation detection system is adequate for quality assurance of radiotherapy using light and radiation field coincidence. In addition, the experiment is considered to have provided valuable results in that the a-Se based digital radiation detection system enables simple and accurate QA for clinical radiation therapy by assessing the coincidence in the alignment of the light and the radiation fields.

  2. Imaging photoelectron circular dichroism of chiral molecules by femtosecond multiphoton coincidence detection

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, C. Stefan; Ram, N. Bhargava; Janssen, Maurice H. M., E-mail: m.h.m.janssen@vu.nl [LaserLaB Amsterdam, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands); Powis, Ivan [School of Chemistry, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2013-12-21

    Here, we provide a detailed account of novel experiments employing electron-ion coincidence imaging to discriminate chiral molecules. The full three-dimensional angular scattering distribution of electrons is measured after photoexcitation with either left or right circular polarized light. The experiment is performed using a simplified photoelectron-photoion coincidence imaging setup employing only a single particle imaging detector. Results are reported applying this technique to enantiomers of the chiral molecule camphor after three-photon ionization by circularly polarized femtosecond laser pulses at 400 nm and 380 nm. The electron-ion coincidence imaging provides the photoelectron spectrum of mass-selected ions that are observed in the time-of-flight mass spectra. The coincident photoelectron spectra of the parent camphor ion and the various fragment ions are the same, so it can be concluded that fragmentation of camphor happens after ionization. We discuss the forward-backward asymmetry in the photoelectron angular distribution which is expressed in Legendre polynomials with moments up to order six. Furthermore, we present a method, similar to one-photon electron circular dichroism, to quantify the strength of the chiral electron asymmetry in a single parameter. The circular dichroism in the photoelectron angular distribution of camphor is measured to be 8% at 400 nm. The electron circular dichroism using femtosecond multiphoton excitation is of opposite sign and about 60% larger than the electron dichroism observed before in near-threshold one-photon ionization with synchrotron excitation. We interpret our multiphoton ionization as being resonant at the two-photon level with the 3s and 3p Rydberg states of camphor. Theoretical calculations are presented that model the photoelectron angular distribution from a prealigned camphor molecule using density functional theory and continuum multiple scattering X alpha photoelectron scattering calculations

  3. Study of incomplete fusion reaction of 16O-ion beam with 124Sn using particle-gamma coincidence technique

    International Nuclear Information System (INIS)

    In order to study the incomplete fusion dynamics, particle-gamma coincidence experiment for the system 16O + 124Sn at 100 MeV beam energy have been performed. To the best of the knowledge these measurements have been reported first time for this projectile-target system

  4. Luminosity Coincident with Initial Breakdown Pulses in Lightning

    Science.gov (United States)

    Stolzenburg, M.; Marshall, T.; Karunarathne, S.; Karunarathna, N.; Vickers, L.; Warner, T. A.; Orville, R. E.; Betz, H.

    2012-12-01

    Time correlated high-speed video and electromagnetic data for 15 cloud-to-ground and intracloud lightning flashes reveal bursts of light, bright enough to be seen through intervening cloud, during the initial breakdown (IB) stage and within the first 3 ms after flash initiation. Each sudden increase in luminosity is coincident with a CG-type (12 cases) or IC-type (3 cases) IB pulse in fast electric field change records. Some of these IB pulses have a coincident VLF/LF (LINET) or a VHF (LDAR2) radiation source. The luminosity bursts of 14 CG flashes occur 11-340 ms before the first return stroke, at altitudes of 4-8 km, and at 4-41 km range from the camera. In seven cases, streamer-type linear segments visibly advance away from the first light burst for 55-200 μs, then the entire length dims, then the luminosity sequence repeats along the same path. These visible initial streamers lengthen intermittently to about 300-1500 m. Their estimated 2-D speeds are 4 to 18 x 10^5 m/s over the first few hundred microseconds and decrease by about 50% over the first 2 ms. In other cases, only a bright spot or a broad area of diffuse light, presumably scattered by intervening cloud, is visible. The bright area grows larger over 20-60 μs before the luminosity fades in about 100 μs, then this sequence may repeat several times. In several of the flashes a 1-2 ms period of little or no luminosity and small E-change is observed following the IB stage prior to stepped leader development. In this presentation we will show examples of the IB luminosity and coincident electromagnetic data.

  5. Mass spectrometric analysis with cluster projectiles and coincidence counting

    Energy Technology Data Exchange (ETDEWEB)

    Cox, B.D.

    1992-01-01

    Methods for maximizing the amount of secondary ion information, per primary projectile, are described. The method is based on time-of-flight mass spectrometry and event-by-event coincidence counting. The information obtained from coincidence counting time-of-flight mass spectrometry includes: (a) surface composition, (b) relative concentrations, and (c) degree of intermolecular mixing. The technique was applied to the study of an important new class of polymers: polymer blends. Secondary ion mass spectrometry, when applied to the analysis of synthetic polymers, induces backbone fragmentation which is characteristic of the homopolymer. The characteristic fingerprint peaks from polystyrene and poly(vinyl methyl ether) were used to identify the presence of these two polymers in a polymer blend. The percent coincidence between the characteristic secondary ions from each component of the blend were used to determine both the relative concentration and the degree of molecular mixing. Results indicate molecular segregation of the two polymers on the film surface. The largest degree of segregation was determined for the phase separated blends. The performance of this technique depends on the desorption efficiency of the primary projectiles. In practice one seeks primary ions which are surface sensitive, have controllable parameters such as size, velocity, and charge state, and generate high secondary ion yields. Focus was placed on the use of keV organic cluster projectiles to meet these criteria. Of interest to this study were C[sub 18] (chrysene), C[sub 24] (coronene), and C[sub 60] (buckminster-fulleren). Results indicate enhanced secondary ion yields for C[sub 60]. For example, when CsI is bombarded with 30 keV C[sub 60], the yields for I[sup [minus

  6. Enhanced PET resolution by combining pinhole collimation and coincidence detection.

    Science.gov (United States)

    DiFilippo, Frank P

    2015-10-21

    Spatial resolution of clinical PET scanners is limited by detector design and photon non-colinearity. Although dedicated small animal PET scanners using specialized high-resolution detectors have been developed, enhancing the spatial resolution of clinical PET scanners is of interest as a more available alternative. Multi-pinhole 511 keV SPECT is capable of high spatial resolution but requires heavily shielded collimators to avoid significant background counts. A practical approach with clinical PET detectors is to combine multi-pinhole collimation with coincidence detection. In this new hybrid modality, there are three locations associated with each event, namely those of the two detected photons and the pinhole aperture. These three locations over-determine the line of response and provide redundant information that is superior to coincidence detection or pinhole collimation alone. Multi-pinhole collimation provides high resolution and avoids non-colinearity error but is subject to collimator penetration and artifacts from overlapping projections. However the coincidence information, though at lower resolution, is valuable for determining whether the photon passed near a pinhole within the cone acceptance angle and for identifying through which pinhole the photon passed. This information allows most photons penetrating through the collimator to be rejected and avoids overlapping projections. With much improved event rejection, a collimator with minimal shielding may be used, and a lightweight add-on collimator for high resolution imaging is feasible for use with a clinical PET scanner. Monte Carlo simulations were performed of a (18)F hot rods phantom and a 54-pinhole unfocused whole-body mouse collimator with a clinical PET scanner. Based on coincidence information and pinhole geometry, events were accepted or rejected, and pinhole-specific crystal-map projections were generated. Tomographic images then were reconstructed using a conventional pinhole SPECT

  7. High-level neutron coincidence counter maintenance manual

    Energy Technology Data Exchange (ETDEWEB)

    Swansen, J.; Collinsworth, P.

    1983-05-01

    High-level neutron coincidence counter operational (field) calibration and usage is well known. This manual makes explicit basic (shop) check-out, calibration, and testing of new units and is a guide for repair of failed in-service units. Operational criteria for the major electronic functions are detailed, as are adjustments and calibration procedures, and recurrent mechanical/electromechanical problems are addressed. Some system tests are included for quality assurance. Data on nonstandard large-scale integrated (circuit) components and a schematic set are also included.

  8. Electron coincidence spectroscopy - an introduction to momentum space chemistry

    International Nuclear Information System (INIS)

    The application of electron coincidence spectroscopy or (e,2e) to obtaining detailed information on the dynamic structure of atoms and molecules is discussed. The technique obtains separation energy spectra and spherically averaged electron momentum distributions for each molecular orbital in the valence region. A brief discussion of molecular orbital density functions in momentum space is given. The results using Hartree-Fock wave functions for atomic orbitals and LCAO-MO-SCF wave functions for molecular orbitals are compared with (e,2e) data. The sensitivity of the data to electron correlations in either the initial or final ion many body states is discussed and examples given

  9. Coincidence of Vietoris and Wijsman Topologies: A New Proof

    OpenAIRE

    Holá, L’.

    1997-01-01

    Let (X, d) be a metric space and CL(X) the family of all nonempty closed subsets of X. We provide a new proof of the fact that the coincidence of the Vietoris and Wijsman topologies induced by the metric d forces X to be a compact space. In the literature only a more involved and indirect proof using the proximal topology is known. Here we do not need this intermediate step. Moreover we prove that (X, d) is boundedly compact if and only if the bounded Vietoris and Wijsman to...

  10. High-level neutron coincidence counter maintenance manual

    International Nuclear Information System (INIS)

    High-level neutron coincidence counter operational (field) calibration and usage is well known. This manual makes explicit basic (shop) check-out, calibration, and testing of new units and is a guide for repair of failed in-service units. Operational criteria for the major electronic functions are detailed, as are adjustments and calibration procedures, and recurrent mechanical/electromechanical problems are addressed. Some system tests are included for quality assurance. Data on nonstandard large-scale integrated (circuit) components and a schematic set are also included

  11. Spectroscopy of fission fragments using prompt-delayed coincidence technique

    Indian Academy of Sciences (India)

    R Palit; S Biswas

    2015-09-01

    The time-stamp structure of the digital data acquisition system of the Indian National Gamma Array (INGA) has been utilized to carry out prompt-delayed coincidence technique for the spectroscopic study of fission fragments. This technique was found to be useful to determine the states above the long-lived isomer (with half-life up to ∼5 s), present in the fission fragments. The angular correlation of -rays, emitted by the fission fragments, has also been used in the present INGA geometry to determine the spins of the de-exciting states.

  12. Violation of Bell inequalities through the coincidence-time loophole

    OpenAIRE

    Morgan, Peter

    2008-01-01

    The coincidence-time loophole was identified by Larsson & Gill (Europhys. Lett. 67, 707 (2004)); a concrete model that exploits this loophole has recently been described by De Raedt et al. (Found. Phys., to appear). It is emphasized here that De Raedt et al.'s model is experimentally testable. De Raedt et al.'s model also introduces contextuality in a novel and classically more natural way than the use of contextual particle properties, by introducing a probabilistic model of a limited set of...

  13. Detector Description and Performance for the First Coincidence Observations between LIGO and GEO

    CERN Document Server

    Abbott, B; Adhikari, R; Allen, B; Amin, R; Anderson, S B; Anderson, W G; Araya, M; Armandula, H; Asiri, F; Aufmuth, P; Aulbert, C; Babak, S V; Balasubramanian, R; Ballmer, S; Barish, B C; Barker, D; Barker-Patton, C; Barnes, M; Barr, B; Barton, M A; Bayer, K; Beausoleil, R; Belczynski, K; Bennett, R; Berukoff, S J; Betzwieser, J; Bhawal, B; Billingsley, G; Black, E; Blackburn, K; Bland-Weaver, B; Bochner, B; Bogue, L; Bork, R G; Bose, S; Brady, P R; Brau, J E; Brown, D A; Brozek, S; Bullington, A; Buonanno, A; Burgess, R; Busby, D; Butler, W E; Byer, R L; Cadonati, L; Cagnoli, G; Camp, J B; Cantley, C A; Cardenas, L; Carter, K; Casey, M M; Castiglione, J; Chandler, A; Chapsky, J; Charlton, P; Chatterji, S; Chen, Y; Chickarmane, V; Chin, D; Christensen, N; Churches, D; Colacino, C N; Coldwell, R; Coles, M; Cook, D; Corbitt, T; Coyne, D; Creighton, J D E; Creighton, T D; Crooks, D R M; Csatorday, P; Cusack, B J; Cutler, C; D'Ambrosio, E; Danzmann, K; Davies, R; Daw, E; De Bra, D; Delker, T; DeSalvo, R; Dhurandhar, S V; Ding, H; Drever, R W P; Dupuis, R J; Ebeling, C; Edlund, J; Ehrens, P; Elliffe, E J; Etzel, T; Evans, M; Evans, T; Fallnich, C; Farnham, D; Fejer, M M; Fine, M; Finn, L S; Flanagan, E; Freise, A; Frey, R; Fritschel, P; Frolov, V; Fyffe, M; Ganezer, K S; Giaime, J A; Gillespie, A; Goda, K; González, G; Gossler, S; Grandclément, P; Grant, A; Gray, C; Gretarsson, A M; Grimmett, D; Grote, H; Grünewald, S; Günther, M; Gustafson, E; Gustafson, R; Hamilton, W O; Hammond, M; Hanson, J; Hardham, C; Harry, G; Hartunian, A; Heefner, J; Hefetz, Y; Heinzel, G; Heng, I S; Hennessy, M; Hepler, N; Heptonstall, A; Heurs, M; Hewitson, M; Hindman, N; Hoang, P; Hough, J; Hrynevych, M; Hua, W; Ingley, R; Ito, M; Itoh, Y; Ivanov, A; Jennrich, O; Johnson, W W; Johnston, W; Jones, L; Jungwirth, D; Kalogera, V; Katsavounidis, E; Kawabe, K; Kawamura, S; Kells, W; Kern, J; Khan, A; Killbourn, S; Killow, C J; Kim, C; King, C; King, P; Klimenko, S; Kloevekorn, P; Koranda, S; Kotter, K; Kovalik, Yu; Kozak, D; Krishnan, B; Landry, M; Langdale, J; Lantz, B; Lawrence, R; Lazzarini, A; Lei, M; Leonhardt, V; Leonor, I; Libbrecht, K; Lindquist, P; Liu, S; Logan, J; Lormand, M; Lubinski, M; Lück, H B; Lyons, T T; Machenschalk, B; MacInnis, M; Mageswaran, M; Mailand, K; Majid, W A; Malec, M; Mann, F; Marin, A; Marka, S; Maros, E; Mason, J; Mason, K; Matherny, O; Matone, L; Mavalvala, N; McCarthy, R; McClelland, D E; McHugh, M; McNamara, P; Mendell, G; Meshkov, S; Messenger, C; Mitselmakher, G; Mittleman, R; Miyakawa, O; Miyoki, S; Mohanty, S; Moreno, G; Mossavi, K; Mours, B; Müller, G; Mukherjee, S; Myers, J; Nagano, S; Nash, T; Naundorf, H; Nayak, R; Newton, G; Nocera, F; Nutzman, P; Olson, T; O'Reilly, B; Ottaway, D J; Ottewill, A; Ouimette, D A; Overmier, H; Owen, B J; Papa, M A; Parameswariah, C; Parameshwaraiah, V; Pedraza, M; Penn, S; Pitkin, M; Plissi, M; Pratt, M; Quetschke, V; Raab, F; Radkins, H; Rahkola, R; Rakhmanov, M; Rao, S R; Redding, D; Regehr, M W; Regimbau, T; Reilly, K T; Reithmaier, K; Reitze, D H; Richman, S; Riesen, R; Riles, K; Rizzi, A; Robertson, D I; Robertson, N A; Robison, L; Roddy, S; Rollins, J; Romano, J D; Romie, J; Rong, H; Rose, D; Rotthoff, E; Rowan, S; Rüdiger, A; Russell, P; Ryan, K; Salzman, I; Sanders, G H; Sannibale, V; Sathyaprakash, B; Saulson, P R; Savage, R; Sazonov, A; Schilling, R; Schlaufman, K; Schmidt, V; Schofield, R; Schrempel, M; Schutz, B F; Schwinberg, P; Scott, S M; Searle, A C; Sears, B; Seel, S; Sengupta, A S; Shapiro, C A; Shawhan, P S; Shoemaker, D H; Shu, Q Z; Sibley, A; Siemens, X; Sievers, L; Sigg, D; Sintes, A M; Skeldon, K D; Smith, J R; Smith, M; Smith, M R; Sneddon, P; Spero, R; Stapfer, G; Strain, K A; Strom, D; Stuver, A; Summerscales, T; Sumner, M C; Sutton, P J; Sylvestre, J; Takamori, A; Tanner, D B; Tariq, H; Taylor, I; Taylor, R; Thorne, K S; Tibbits, M; Tilav, S; Tinto, M; Torres, C; Torrie, C; Traeger, S; Traylor, G; Tyler, W; Ugolini, D W; Vallisneri, M; Van Putten, M H P M; Vass, S; Vecchio, A; Vorvick, C; Wallace, L; Walther, H; Ward, H; Ware, B; Watts, K; Webber, D; Weidner, A; Weiland, U; Weinstein, A; Weiss, R; Welling, H; Wen, L; Wen, S; Whelan, J T; Whitcomb, S E; Whiting, B F; Willems, P A; Williams, P R; Williams, R; Willke, B; Wilson, A; Winjum, B J; Winkler, W; Wise, S; Wiseman, A G; Woan, G; Wooley, R; Worden, J; Yakushin, I; Yamamoto, H; Yoshida, S; Zawischa, I; Zhang, L; Zotov, N P; Zucker, M; Zweizig, J

    2004-01-01

    For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis papers based on the first data.

  14. A compact Ge-BGO coincidence array for ultra-sensitive in-beam gamma spectroscopy

    International Nuclear Information System (INIS)

    Ultra-weak resonances in nuclear reactions impose a challenge on experimentalists. The present work describes the setup used in the first direct measurement of extremely weak low energy resonances of the 18O(α, γ)22Ne reaction. A Clover HPGe detector in coincidence with specified energy windows in BGO counters covering a large solid angle, and combined with large plastic veto counters led to a significantly improved sensitivity, thus allowing for the clear identification of specific γ-transitions. Different modes of operation have been tested for optimizing the final experimental setup

  15. Fluorescent atom coincidence spectroscopy of extremely neutron-deficient barium isotopes

    International Nuclear Information System (INIS)

    Fluorescent atom coincidence spectroscopy (FACS) has been used to measure the nuclear mean square radii and moments of the extremely neutron-deficient isotopes 120-124Ba. At N=65 an abrupt change in nuclear mean square charge radii is observed which can be understood in terms of the occupation of the spin-orbit partner g7/2 5/2[413] neutron and g9/2 9/2[404] proton orbitals and the consequent enhancement of the n-p interaction. (orig.)

  16. A note on the local cosmological constant and the dark energy coincidence problem

    International Nuclear Information System (INIS)

    It has been suggested that the dark energy coincidence problem could be interpreted as a possible link between the cosmological constant and a massive graviton. We show that by using this link and models for the graviton mass, a dark energy density can be obtained that is indeed very close to measurements by WMAP. As a consequence of the models, the cosmological constant was found to depend on the density of matter. A brief outline of the cosmological consequences such as the effect on the black hole solution is given. (comments, replies and notes)

  17. Coincidence Detection Using Spiking Neurons with Application to Face Recognition

    Directory of Open Access Journals (Sweden)

    Fadhlan Kamaruzaman

    2015-01-01

    Full Text Available We elucidate the practical implementation of Spiking Neural Network (SNN as local ensembles of classifiers. Synaptic time constant τs is used as learning parameter in representing the variations learned from a set of training data at classifier level. This classifier uses coincidence detection (CD strategy trained in supervised manner using a novel supervised learning method called τs Prediction which adjusts the precise timing of output spikes towards the desired spike timing through iterative adaptation of τs. This paper also discusses the approximation of spike timing in Spike Response Model (SRM for the purpose of coincidence detection. This process significantly speeds up the whole process of learning and classification. Performance evaluations with face datasets such as AR, FERET, JAFFE, and CK+ datasets show that the proposed method delivers better face classification performance than the network trained with Supervised Synaptic-Time Dependent Plasticity (STDP. We also found that the proposed method delivers better classification accuracy than k nearest neighbor, ensembles of kNN, and Support Vector Machines. Evaluation on several types of spike codings also reveals that latency coding delivers the best result for face classification as well as for classification of other multivariate datasets.

  18. Radio transient following FRB 150418: afterglow or coincident AGN flare?

    CERN Document Server

    Li, Ye

    2016-01-01

    Recently, Keane et al. reported the discovery of a fading radio transient following FRB 150418, and interpreted it as the afterglow of the FRB. Williams \\& Berger, on the other hand, suggested that the radio transient is analogous to a group of variable radio sources, so that it could be a coincident AGN flare in the observational beam of the FRB. A new observation with VLA showed a re-brightening, which is consistent with the AGN picture. Here, using the radio survey data of Ofek et al., we statistically examine the chance coincidence probability to produce an event like the FRB 150418 transient. We find that the probabilities to produce a variable radio transient with at least the same variability amplitude and signal-to-noise ratio as the FRB 150415 transient, without and with the VLA point, are $P_1 \\sim 6 \\times 10^{-4}$ and $P_1 \\sim 2 \\times 10^{-3}$, respectively. In addition, the chance probability to have a fading transient detected following a random time (FRB time) is less than $P_2 \\sim 10^{-...

  19. Search for coincident air showers in the network observation

    International Nuclear Information System (INIS)

    Here we report results of the coincident event analysis, using air shower data taken at six stations of the Large Area Air Shower (LAAS) group in Japan. In this analysis we search for pairs of coincident air showers between stations, which are hypothetically induced by bursts of ultra-high-energy γ-ray sources or by secondary particles from interactions of extremely-high-energy cosmic rays with interstellar matter. From four years data (2.3 x 106 air showers) we find a pair of air showers with a very small time difference of 195 microseconds and an angular distance of 5.3 degrees, which is within the angular accuracy of our arrays, between two stations separated by 152 km. The chance probability of this event is 0.16. The Crab Nebula, a well-known ultra-high-energy γ-ray source, is within the angular accuracy from the arrival direction of this event. We expect that this event was induced by the ultra-high-energy γ-rays emitted in a burst of the Crab Nebula

  20. Coincidence of lung cancer and silicosis in Czechoslovak uranium miners

    International Nuclear Information System (INIS)

    27 patients with established coincidence of lung cancer and silicosis from a group of 1607 cases of lung cancer from radioactive compounds, and 166 cases of pneumoconiosis were reported by the Occupational Diseases Ward of the works Institute of National Health in Uranium Industry in the 1962 to 1986 years. Lung cancer was found in 16% of reported silicosis patients, in 81% it was simple silicosis, in 50% of cases in was an epidermoid type of cancer. In two cases the malignant process originated in the silicotic node, in one case from a tuberculoma. Lung cancer occurred most frequently in the right lower lung region. The mean age of the silicosis group was 48.6 years and 56.0 years for the lung cancer group. No difference was thus seen from the mean age of patients with lung cancer from radioactive compounds diagnosed in the years 1976 to 1980 but it was significantly lower that the reported average age of patients with coincidence of lung cancer and pneumoconiosis in the population not exposed to ionizing radiation. (author). 2 figs., 1 tab., 18 refs

  1. FDG-PET using coincidence gamma cameras - an update

    International Nuclear Information System (INIS)

    PET imaging with F-18 labeled tracers - mainly FDG - is on the verge to be applied in a broad clinical setting with a multitude of indications in oncology, neurology and cardiology. Main obstacles for a more widespread distribution of PET technology are the high costs of cyclotron products (350-500 Euro for FDG in satellite distribution) and of dedicated PET tomographs (1.5 Mio Euro). As a consequence, dual head gamma cameras were equipped for coincidence detection and tested as 'small PET'. Meanwhile a few studies have been published allowing a new evaluation of coincidence gamma cameras for FDG imaging. Decisive criteria should be the better diagnostic performance in comparison with CT and MRI. Applying restrictive indications these systems might be useful for staging head and neck tumors, and for evaluation of solitary pulmonary nodules larger than 1 cm. In the future, the option for camera PET most likely will be the control of ongoing therapy of known lesions (chemo- or radiotherapy). (orig.)

  2. TYPE III EXCITABILITY, SLOPE SENSITIVITY AND COINCIDENCE DETECTION.

    Science.gov (United States)

    Meng, Xiangying; Huguet, Gemma; Rinzel, John

    2012-08-01

    Some neurons in the nervous system do not show repetitive firing for steady currents. For time-varying inputs, they fire once if the input rise is fast enough. This property of phasic firing is known as Type III excitability. Type III excitability has been observed in neurons in the auditory brainstem (MSO), which show strong phase-locking and accurate coincidence detection. In this paper, we consider a Hodgkin-Huxley type model (RM03) that is widely-used for phasic MSO neurons and we compare it with a modification of it, showing tonic behavior. We provide insight into the temporal processing of these neuron models by means of developing and analyzing two reduced models that reproduce qualitatively the properties of the exemplar ones. The geometric and mathematical analysis of the reduced models allows us to detect and quantify relevant features for the temporal computation such as nearness to threshold and a temporal integration window. Our results underscore the importance of Type III excitability for precise coincidence detection. PMID:23667306

  3. Coincidence counting emission tomographic probe: Method and apparatus

    International Nuclear Information System (INIS)

    An nuclear medicine apparatus is described for analyzing particular characteristics of a body organ into which radiopharmaceuticals have been introduced, the radiopharmaceuticals causing a plurality of internally generated radioactive emissions from the organ, the apparatus comprising: pairs of adjacent radiation detector means. Each pair of detector means is capable of detecting at least two different internally generated radioactive emissions, of respectively different energy levels, from the organ and generating separate electrical signals. Each of the separate signals generates in response to a different detected emission; and electronic means coupled to the detector means, the electronic means responsive to coincident reception of the two separate electric signals, representative of the different detected emissions; means for processing and analyzing the levels of the coincident reception, coupled to the output of the electronic means. The processing and analyzing means is positioned at least every 45 degrees around. The organ monitors throughout along an arc of at least 180 degrees. The maximum and minimum intensity of angular radiation can then be determined

  4. Coincidence orientations of grains in rhombohedral and hexagonal materials

    International Nuclear Information System (INIS)

    In experimental investigations and computer simulations of the structure and properties of grain boundaries, the results are usually discussed with reference to the special case of coincidence boundaries, where the two neighbouring grains have a three-dimensional lattice of symmetry translations in common. For historical reasons this lattice is called the coincidence site lattice or CSL. A systematic determination of CSL's for the case of grains with a lattice of rhombohedral Bravais type is presented. It is shown that a number of investigations of the structure of grain boundaries in alumina (α-Al2O3) have to be reinterpreted in the light of the present results. It is shown that the multiplicities of the CSL's generated by a given rotation in a hexagonal and in a rhombohedral lattice with the same value of c/a differ by at most a factor 3. Regularities in the numbers of different rotations generating CSL's with given multiplicity have been observed for rhombohedral and hexagonal lattices for certain rational values of c2/a2. This may be of interest also to mathematicians in those cases where the number of representations of integers by the corresponding positive integral quaternary quadratic forms are not yet known. (author) 16 tabs., 9 figs., 66 refs

  5. Study and construction of a β-spectrometer of uniform axial magnetic field fitted with a β-γ coincidence selector. Study of the β spectra of 32P, 203Hg, 198Au. Measurement of the conversion coefficients of 203Ti and of 198Hg

    International Nuclear Information System (INIS)

    In the first part is given the principle of the beta spectrometer with uniform axial field using systematically the idea of caustics. The apparatus is described and its properties compared to those deduced from trajectory calculations. The β-ray and γ-ray detectors and the device for selecting coincidences with a 2 τ resolution of 5 nanoseconds are also presented. In the second part, the spectrometer is used for studying reference elements and the most accurate results are confirmed. The β spectrum of 60Co has a statistical form with an accuracy of 1 per cent; the maximum energy E0 is 316.5 ± 1.5 keV. That of the 7/2 + → 11/2 transition for 137Cs has a unique form, once forbidden. E0= 522 ± 3 keV. Conversion coefficients αk = 96 ± 1 X 10-3 αL + M + N = 20.9 ± 0.5 X 10-3. The two β spectra of 59Fe, separated by coincidence with the gamma, have the statistical form E0 = 462 ± 2 keV (55.1 + 0,3 per cent) and E1 = 275 ± 4 keV (44.9 ± 0.3 per cent). It is then verified whether the l selection rule is apparent in the shape of the phosphorus 32 beta spectrum. It is found in fact that it is not of statistical shape and its shape coefficient is determined. For a theoretical interpretation it is necessary to have better approximations than those generally used and this interpretation will not be unique. This work has also made it possible to show that the source contains a small proportion of 33P. The study of the 203Hg β spectrum followed by the 279 keV gamma spectrum is designed to determine the conversion coefficients. The interior spectrum of gold 198 is not of statistical shape either. The form coefficient is determined together with the conversion coefficients which are in slight disagreement with those calculated by Rose or Sliv. An interpretation of the spectrum is put forward which proposes an imperfect compensation for the various elements of the matrix. (author)

  6. Determination of the 242Pu Branching Ratio via Alpha-Gamma Coincidence

    Energy Technology Data Exchange (ETDEWEB)

    Wang, T F

    2012-05-24

    When the burn-up is high, the {sup 242}Pu isotopic content becomes more important. The traditional correlation method will fail. The {sup 242}Pu isotopic content in the sample plays an essential role if the neutron coincidence method is used to quantify the total amount of plutonium. In one of the earlier measurements we had a chance to measure an isotopic pure (> 99.95 %) {sup 242}Pu thick sample and realized that the difference in the branching ratio (BR) value among current nuclear data3) for the two important gamma-rays at 103.5-keV and 158.8-keV. In this study, the thick sample was counted on a 15% ORTEC safeguards type HPGe to further improve BR determination of the 159-keV gamma-ray. Furthermore, we have made a thin {sup 242}Pu sample from the thick sample and performed alpha-gamma coincidence measurements. Our preliminary gamma-ray BR results are 4.37(6) E-4, 2.79(8) E-5, and 2.25(8) E-6 for 44.9-keV, 103.5-keV, and 158.9-keV, respectively.

  7. Determination of the 242Pu Branching Ratio via Alpha-Gamma Coincidence

    International Nuclear Information System (INIS)

    When the burn-up is high, the 242Pu isotopic content becomes more important. The traditional correlation method will fail. The 242Pu isotopic content in the sample plays an essential role if the neutron coincidence method is used to quantify the total amount of plutonium. In one of the earlier measurements we had a chance to measure an isotopic pure (> 99.95 %) 242Pu thick sample and realized that the difference in the branching ratio (BR) value among current nuclear data3) for the two important gamma-rays at 103.5-keV and 158.8-keV. In this study, the thick sample was counted on a 15% ORTEC safeguards type HPGe to further improve BR determination of the 159-keV gamma-ray. Furthermore, we have made a thin 242Pu sample from the thick sample and performed alpha-gamma coincidence measurements. Our preliminary gamma-ray BR results are 4.37(6) E-4, 2.79(8) E-5, and 2.25(8) E-6 for 44.9-keV, 103.5-keV, and 158.9-keV, respectively.

  8. Hydrogen analysis for granite using proton-proton elastic recoil coincidence spectrometry.

    Science.gov (United States)

    Komatsubara, T; Sasa, K; Ohshima, H; Kimura, H; Tajima, Y; Takahashi, T; Ishii, S; Yamato, Y; Kurosawa, M

    2008-07-01

    In an effort to develop DS02, a new radiation dosimetry system for the atomic bomb survivors of Hiroshima and Nagasaki, measurements of neutron-induced activities have provided valuable information to reconstruct the radiation situation at the time of the bombings. In Hiroshima, the depth profile of (152)Eu activity measured in a granite pillar of the Motoyasu Bridge (128 m from the hypocenter) was compared with that calculated using the DS02 methodology. For calculation of the (152)Eu production due to the thermal-neutron activation reaction, (151)Eu(n,gamma)(152)Eu, information on the hydrogen content in granite is important because the transport and slowing-down process of neutrons penetrating into the pillar is strongly affected by collisions with the protons of hydrogen. In this study, proton-proton elastic recoil coincidence spectrometry has been used to deduce the proton density in the Motoyasu pillar granite. Slices of granite samples were irradiated by a 20 MeV proton beam, and the energies of scattered and recoil protons were measured with a coincidence method. The water concentration in the pillar granite was evaluated to be 0.30 +/- 0.07%wt. This result is consistent with earlier data on adsorptive water (II) and bound water obtained by the Karl Fisher method. PMID:18509666

  9. A simultaneous beta and coincidence-gamma imaging system for plant leaves

    Science.gov (United States)

    Ranjbar, Homayoon; Wen, Jie; Mathews, Aswin J.; Komarov, Sergey; Wang, Qiang; Li, Ke; O’Sullivan, Joseph A.; Tai, Yuan-Chuan

    2016-05-01

    Positron emitting isotopes, such as 11C, 13N, and 18F, can be used to label molecules. The tracers, such as 11CO2, are delivered to plants to study their biological processes, particularly metabolism and photosynthesis, which may contribute to the development of plants that have a higher yield of crops and biomass. Measurements and resulting images from PET scanners are not quantitative in young plant structures or in plant leaves due to poor positron annihilation in thin objects. To address this problem we have designed, assembled, modeled, and tested a nuclear imaging system (simultaneous beta–gamma imager). The imager can simultaneously detect positrons ({β+} ) and coincidence-gamma rays (γ). The imaging system employs two planar detectors; one is a regular gamma detector which has a LYSO crystal array, and the other is a phoswich detector which has an additional BC-404 plastic scintillator for beta detection. A forward model for positrons is proposed along with a joint image reconstruction formulation to utilize the beta and coincidence-gamma measurements for estimating radioactivity distribution in plant leaves. The joint reconstruction algorithm first reconstructs beta and gamma images independently to estimate the thickness component of the beta forward model and afterward jointly estimates the radioactivity distribution in the object. We have validated the physics model and reconstruction framework through a phantom imaging study and imaging a tomato leaf that has absorbed 11CO2. The results demonstrate that the simultaneously acquired beta and coincidence-gamma data, combined with our proposed joint reconstruction algorithm, improved the quantitative accuracy of estimating radioactivity distribution in thin objects such as leaves. We used the structural similarity (SSIM) index for comparing the leaf images from the simultaneous beta–gamma imager with the ground truth image. The jointly reconstructed images yield SSIM indices of 0.69 and 0.63, whereas

  10. IXO-XMS LVSID Anti-Coincidence Detector

    Science.gov (United States)

    Porter, Scott F.; Kilbourne, Caroline

    2010-01-01

    This document describes a high-TRL backup implementation of the anti-coincidence detector for the IXO/XMS instrument. The backup detector, hereafter referred to as the low-voltage silicon ionization detector (LVSID), has been successfully flown on Astro-E2 (Suzaku)/XRS and is currently being implemented, without significant changes, on the Astro-H/SXS instrument. The LVSID anti-coincidence detector on Astro-E2/XRS operated successfully for almost 2 years, and was not affected by the loss of liquid helium in that instrument. The LVSID continues to operate after almost 5 years on-orbit (LEO, 550 km) but with slightly increased noise following the expected depletion of solid Neon after 22 months. The noise of the device is increased after the loss of sNe due to thermally induced bias and readout noise. No radiation damage, or off-nominal affects have been observed with the LVSID on-orbit during the Astro-E2/XRS program. A detector die from the same fabrication run will be used on the Astro-H/SXS mission. The LVSID technology and cryogenic JFET readout system is thus TRL 9. The technology is described in detail in section 2. The IXO/XMS "backup-up" anti-coincidence detector is a small array of LVSID detectors that are almost identical to those employed for Astro -E2/XRS as described in this document. The readout system is identical and, infact would use the same design as the Astro -E2/XRS JFET amplifier module (19 channels) essentially without changes except for its mechanical mount. The changes required for the IXO/XMS LVSID array are limited to the mounting of the LVSID detectors, and the mechanical mounting of the JFET amplifier sub-assembly. There is no technical development needed for the IXO/XMS implementation and the technology is ready for detailed design-work leading to PDR. The TRL level is thus at least 6, and possibly higher. Characteristics of an IXO/XMS LVSID anti-co detector are given in Table 1 and described in detail in section 3.

  11. Positron emission tomography with gamma camera in coincidence mode

    International Nuclear Information System (INIS)

    Positron emission tomography using F-18 FDG has been estbalished in clinical diagnostics with first indications especially in oncology. To install a conventional PET tomography (dedicated PET) is financially costly and restricted to PET examinations only. Increasing demand for PET diagnostics on one hand and restricted financial resources in the health system on the other hand led industry to develop SPECT cameras to be operated in coincidence mode (camera PET) in order to offer nuclear medicine physicians cost-effective devices for PET diagnostic. At the same time camera PET is inferior to conventional PET regarding sensitivity and detection-efficiency for 511 keV photons. Does camera-PET offer a reliable alternative to conventional PET? The first larger comparative studies are now available, so a first apraisal about the technical clinical performance of camera-PET can be done. (orig.)

  12. Sub-wavelength bubble in photon coincidence detection

    CERN Document Server

    Liu, Ruifeng; Zhou, Yu; Gao, Hong; Li, Fuli

    2013-01-01

    Sub-wavelength interference has a potential application in lithography to beat the classical Rayleigh limit of resolution. We carefully study the second-order correlation theory and find there is a bubble of sub-wavelength interference in photon coincidence detection. A Young's double-slit experiment with thermal light is carried out to test the second-order correlation pattern. The result shows that when different scanning ways of two point detectors are chosen, we can get arbitrary-wavelength interference patterns. We then give a theoretical explanation to this surprising result, and find this explanation is also suitable for the result by using entangled light. Furthermore, the question of whether this kind of arbitrary-wavelength interference patterns can be used in quantum lithography is also analyzed.

  13. Commentary on Bayesian coincidence assessment (cross-matching)

    CERN Document Server

    Loredo, Thomas J

    2012-01-01

    This paper is an invited commentary on Tamas Budavari's presentation, "On statistical cross-identification in astronomy," for the Statistical Challenges in Modern Astronomy V conference held at Pennsylvania State University in June 2011. I begin with a brief review of previous work on probabilistic (Bayesian) assessment of directional and spatio-temporal coincidences in astronomy (e.g., cross-matching or cross-identification of objects across multiple catalogs). Then I discuss an open issue in the recent innovative work of Budavari and his colleagues on large-scale probabilistic cross-identification: how to assign prior probabilities that play an important role in the analysis. With a simple toy problem, I show how Bayesian multilevel modeling (hierarchical Bayes) provides a principled framework that justifies and generalizes pragmatic rules of thumb that have been successfully used by Budavari's team to assign priors.

  14. Excitation and decay at Stark-mixed n = 2 states of hydrogen observed in an electron-photon coincidence experiment

    International Nuclear Information System (INIS)

    Measurements have been made of the Lyman-α intensity from Stark-mixed n = 2 states of hydrogen, using the electron-photon coincidence technique at an incident electron energy of 350 eV. The data are related to a combination of excitation amplitudes, including a term which depends on the relative phase of S and P amplitudes. Field-free measurements of lambda and R have also been made at this energy. Comparison is made with several theoretical results. (author)

  15. Modification of the Cox-Isham formula for 4πβ-γ-coincidence counting by the Gandy -effect and its automatic correction by electronic circuits

    International Nuclear Information System (INIS)

    The correction formula of Cox and Isham for accidental coincidences and dead time losses in a 4πβ-γ-coincidence system is modified for the relative delay between β- and γ-channels ( Grand effect ). This extended formula is used to study the problems connected with an automatic measurement and compensation of the relative delay. Basic delay matching circuits for this purpose are proposed. (orig.)

  16. Algorithms for Identification of Nearly-Coincident Events in Calorimetric Sensors

    CERN Document Server

    Alpert, B; Bennett, D; Faverzani, M; Fowler, J; Giachero, A; Hays-Wehle, J; Maino, M; Nucciotti, A; Puiu, A; Swetz, D; Ullom, J

    2015-01-01

    For experiments with high arrival rates, reliable identification of nearly-coincident events can be crucial. For calorimetric measurements to directly measure the neutrino mass such as HOLMES, unidentified pulse pile-ups are expected to be a leading source of experimental error. Although Wiener filtering can be used to recognize pile-up, it suffers errors due to pulse-shape variation from detector nonlinearity, readout dependence on sub-sample arrival times, and stability issues from the ill-posed deconvolution problem of recovering Dirac delta-functions from smooth data. Due to these factors, we have developed a processing method that exploits singular value decomposition to (1) separate single-pulse records from piled-up records in training data and (2) construct a model of single-pulse records that accounts for varying pulse shape with amplitude, arrival time, and baseline level, suitable for detecting nearly-coincident events. We show that the resulting processing advances can reduce the required performa...

  17. Search for Sub-TeV Gamma Rays Coincident with BATSE Gamma Ray Bursts

    CERN Document Server

    Poirier, J; Gress, J; Race, D

    2003-01-01

    Project GRAND is a 100m x 100m air shower array of proportional wire chambers (PWCs). There are 64 stations each with eight 1.29 m^2 PWC planes arranged in four orthogonal pairs placed vertically above one another to geometrically measure the angles of charged secondaries. A steel plate above the bottom pair of PWCs differentiates muons (which pass undeflected through the steel) from non-penetrating particles. FLUKA Monte Carlo studies show that a TeV gamma ray striking the atmosphere at normal incidence produces 0.23 muons which reach ground level where their angles and identities are measured. Thus, paradoxically, secondary muons are used as a signature for gamma ray primaries. The data are examined for possible angular and time coincidences with eight gamma ray bursts (GRBs) detected by BATSE. Seven of the GRBs were selected because of their good acceptance by GRAND and high BATSE Fluence. The eighth GRB was added due to its possible coincident detection by Milagrito. For each of the eight candidate GRBs, ...

  18. Development of a geometric uncertainty model describing the accuracy of position-sensitive, coincidence neutron detection

    International Nuclear Information System (INIS)

    A diameter of uncertainty (Du) was derived from a geometric uncertainty model describing the error that would be introduced into position-sensitive, coincidence neutron detection measurements by charged-particle transport phenomena and experimental setup. The transport of α and Li ions, produced by the 10B(n,α) 7Li reaction, through free-standing boro-phosphosilicate glass (BPSG) films was modeled using the Monte Carlo code SRIM, and the results of these simulations were used as input to determine Du for position-sensitive, coincidence techniques. The results of these calculations showed that Du is dependent on encoder separation, the angle of charged particle emission, and film thickness. For certain emission scenarios, the magnitude of Du is larger than the physical size of the neutron converting media that were being modeled. Spheres of uncertainty were developed that describe the difference in flight path times among the bounding-case emission scenarios that were considered in this work. It was shown the overlapping spheres represent emission angles and particle flight path lengths that would be difficult to resolve in terms of particle time-of-flight measurements. However, based on the timing resolution of current nuclear instrumentation, emission events that yield large Du can be discriminated by logical arguments during spectral deconvolution.

  19. Theoretical Bounds and Practical Constructions for Families of One—Coincidence Sequences in FHMA

    Institute of Scientific and Technical Information of China (English)

    MeiWenhua; YangYixian

    1995-01-01

    Theoretical bounds are given for the number of one-coincidence sequences in syn-chronous FHMA systems,and for the number and period of one-coincidence sequences in asyn-chronous FHMA systems.Several practical constructions for families of one-coincidencesequences are surveyed,and a new model for families of one-coincidence sequences is presented.

  20. Dead time effects of time jitter and metastable gamma-transitions in coincidence systems

    International Nuclear Information System (INIS)

    Time jitter, or more generally, the time distribution of coincidences in coincidence systems, is investigated for its dead time effect on the coincidence rate. The discussion is extended to metastable γ-transitions and an experimental proof is given for the correction terms developed. (orig.)

  1. A statistical method for selection of sequences of coincident weather parameters for design cooling load calculations

    International Nuclear Information System (INIS)

    Current design weather data recommended by ASHRAE and CIBSE may result in overestimated peak cooling loads. This is because solar radiation, and outdoor dry-bulb and wet-bulb temperatures selected for design conditions do not occur coincidently. Hence, the data cannot reflect the joint statistical distribution of these three weather parameters. Moreover, the peak cooling load largely depends on the characteristics of both weather and buildings. A statistical method has been developed for the rational selection of sequences of coincident design weather parameters in order to properly determine peak cooling loads. Overall periodic transfer factors responding to different periodic weather heat sources are first derived based on the radiant time series (RTS) method. This allows us to utilize the available thermal and optical properties of a building without the need for tedious regenerating these data. The periodic transfer factors are then equivalently transformed to z-transfer coefficients. The model has been applied to hourly weather records of 25 years in Hong Kong to generate the hourly cooling loads of buildings with any thermal lag. Sequences of coincident design solar irradiance, dry-bulb and wet-bulb temperatures have been rationally determined through statistical analysis of the computed cooling loads. Results indicate that horizontal solar irradiance computed with the method recommended by ASHRAE is always higher, 4-20%, than the measured value in different months. The peak cooling load resulted from the traditional design weather data is always much higher, 12-50%, than the results from the new design weather data. An unreasonably oversized air-conditioning system would cause high initial cost and unnecessary significant use in embodied energy. It would also deteriorate the part-load energy efficiency and the system management effectiveness

  2. Coincidence spectroscopy of high-lying Rydberg states produced in strong laser fields

    CERN Document Server

    Larimian, Seyedreza; Lemell, Christoph; Yoshida, Shuhei; Nagele, Stefan; Maurer, Raffael; Baltuška, Andrius; Burgdörfer, Joachim; Kitzler, Markus; Xie, Xinhua

    2016-01-01

    We report on the measurement of electron emission after the interaction of strong laser pulses with atoms and molecules. These electrons originate from high-lying Rydberg states with quantum numbers up to $n \\lesssim 120$ formed by frustrated field ionization. Simulations show that both tunneling ionization by a weak dc field and photoionization by the black-body radiation contribute to delayed electron emission on the nano- to microsecond scale. We measured ionization rates from these Rydberg states by coincidence spectroscopy. Further, the dependence of the Rydberg-state production on the ellipticity of the driving laser field proves that such high-lying Rydberg states are populated through electron recapture. The present experiment provides detailed quantitative information on Rydberg production by frustrated field ionization.

  3. Coincidence detection of spatially correlated photon pairs with a monolithic time-resolving detector array

    CERN Document Server

    Unternährer, Manuel; Gasparini, Leonardo; Stoppa, David; Stefanov, André

    2016-01-01

    We demonstrate coincidence measurements of spatially entangled photons by means of a novel type of multi-pixel based detection array. The adopted sensor is a fully digital 8$\\times$16 silicon photomultiplier array allowing not only photon counting but also per-pixel time stamping of the arrived photons with a resolution of 65 ps. Together with a frame rate of 500 kfps, this property exceeds the capabilities of conventional charge-coupled device cameras which have become of growing interest for the detection of transversely correlated photon pairs. The sensor is used to measure a second-order correlation function for various non-collinear configurations of entangled photons generated by spontaneous parametric down-conversion. The experimental results are compared to theory.

  4. SCORPION: a system for coincidences between recoil and projectile ions at NSC, New Delhi

    International Nuclear Information System (INIS)

    An on-line facility to measure coincidences between the recoil ions and the scattered projectiles (SCORPION) has been designed, fabricated and commissioned at Nuclear Science Centre (NSC), New Delhi. The facility consists of a four jaw slit assembly, a time of flight (TOF) spectrometer, a parallel plate electrostatic charge analyser and a one dimensional position sensitive parallel plate avalanche counter (PPAC). Details of the design and working principles of various components and the test results obtained for the Siq+ -Ar collision system are presented to highlight the performance of the system. A multiple loss of up to four electrons has been observed for 60 MeV Si4+ ions colliding with argon atoms in a single collision condition. Spectra of recoil ions detected in coincidence with a particular charge state of the scattered projectile show a bell shaped distribution as a function of the recoil charge state (r) for the electron loss events. However, the yield of recoil ions drops as r increases for the direct ionization channel. Also for electron loss, the peak of the recoil ion distribution is seen to shift to a higher recoil charge state as the number of lost electrons from the projectile increases. (author)

  5. Ionospheric disturbances observed coincident with the 2006 and 2009 North Korean underground nuclear tests

    Science.gov (United States)

    Yang, Yu-Ming; Garrison, James L.; Lee, See-Chen

    2012-01-01

    Acoustic-Gravity Waves (AGWs) in the neutral atmosphere can induce disturbances in the ionosphere that are subsequently observable in trans-ionospheric Global Navigation Satellite System (GNSS) measurements. Disruptive events on the Earth's surface, such as earthquakes, tsunamis and large explosions are one source of these disturbances. In this study, we apply wavelet analysis to enhance a cross-correlation technique for detecting the presence of ionospheric disturbances in dual frequency GNSS time series collected from the GEONET (Japan) during the North Korean Underground Nuclear Tests (UGTs) conducted on 9 October 2006 and 25 May 2009. Through use of the wavelet coherence analysis, we are able to find significant wave trains in the Integrated Electron Content (IEC) data collected from the network. Low frequency disturbances, with periods between 3 and 12 min and horizontal propagation speeds between 75 and 453 m/s were found coincident with both the 2006 and 2009 events. High frequency disturbances, with periods between 2 and 5 min and horizontal speeds between 297 and 1322 m/s were found only after the 2009 event. The disturbances extracted from these signals showed propagation speeds, directions, and times of arrival coincident with the reported geographic location and times of the UGTs.

  6. Analysis of the effect of true coincidence summing on efficiency calibration for an HP GE detector

    Energy Technology Data Exchange (ETDEWEB)

    Rodenas, J.; Gallardo, S.; Ballester, S.; Primault, V. [Valencia Univ. Politecnica, Dept. de Ingenieria Quimica y Nuclear (Spain); Ortiz, J. [Valencia Univ. Politecnica, Lab. de Radiactividad Ambiental (Spain)

    2006-07-01

    The H.P. (High Purity) Germanium detector is commonly used for gamma spectrometry in environmental radioactivity laboratories. The efficiency of the detector must be calibrated for each geometry considered. This calibration is performed using a standard solution containing gamma emitter sources. The usual goal is the obtaining of an efficiency curve to be used in the determination of the activity of samples with the same geometry. It is evident the importance of the detector calibration. However, the procedure presents some problems as it depends on the source geometry (shape, volume, distance to detector, etc.) and shall be repeated when these factors change. That means an increasing use of standard solutions and consequently an increasing generation of radioactive wastes. Simulation of the calibration procedure with a validated computer program is clearly an important auxiliary tool for environmental radioactivity laboratories. This simulation is useful for both optimising calibration procedures and reducing the amount of radioactivity wastes produced. The M.C.N.P. code, based on the Monte Carlo method, has been used in this work for the simulation of detector calibration. A model has been developed for the detector as well as for the source contained in a Petri box. The source is a standard solution that contains the following radionuclides: {sup 241}Am, {sup 109}Cd, {sup 57}Co, {sup 139}Ce, {sup 203}Hg, {sup 113}Sn, {sup 85}Sr, {sup 137}Cs, {sup 88}Y and {sup 60}Co; covering a wide energy range (50 to 2000 keV). However, there are two radionuclides in the solution ({sup 60}Co and {sup 88}Y) that emit gamma rays in true coincidence. The effect of the true coincidence summing produces a distortion of the calibration curve at higher energies. To decrease this effect some measurements have been performed at increasing distances between the source and the detector. As the true coincidence effect is observed in experimental measurements but not in the Monte Carlo

  7. A Testable Solution of the Cosmological Constant and Coincidence Problems

    CERN Document Server

    Shaw, Douglas J

    2010-01-01

    We present a new solution to the cosmological constant (CC) and coincidence problems in which the observed value of the CC, Lambda, is linked to other observable properties of the universe. This is achieved by promoting the CC from a parameter which must to specified, to a field which can take many possible values. The observed value of Lambda = 1/(9.3 Gyrs)^2 (~ 10^(-120) in Planck units) is determined by a new constraint equation which follows from the application of a causally restricted variation principle. When applied to our visible universe, the model makes a testable prediction for the dimensionless spatial curvature of Omega_K0 = -0.0056 (s_b/0.5); where s_b ~ 1/2 is a QCD parameter. Requiring that a classical history exist, our model determines the probability of observing a given Lambda. The observed CC value, which we successfully predict, is typical within our model even before the effects of anthropic selection are included. When anthropic selection effects are accounted for, we find that the ob...

  8. A gap junction circuit enhances processing of coincident mechanosensory inputs.

    Science.gov (United States)

    Rabinowitch, Ithai; Chatzigeorgiou, Marios; Schafer, William R

    2013-06-01

    Electrical synapses have been shown to be important for enabling and detecting neuronal synchrony in both vertebrates and invertebrates. Hub-and-spoke circuits, in which a central hub neuron is electrically coupled to several input neurons, are an overrepresented motif in the C. elegans nervous system and may represent a conserved functional unit. The functional relevance of this configuration has been demonstrated for circuits mediating aggregation behavior and nose touch perception. Modeling approaches have been useful for understanding structurally and dynamically more complex electrical circuits. Therefore, we formulated a simple analytical model with minimal assumptions to obtain insight into the properties of the hub-and-spoke microcircuit motif. A key prediction of the model is that an active input neuron should facilitate activity throughout the network, whereas an inactive input should suppress network activity through shunting; this prediction was supported by cell ablation and in vivo neuroimaging experiments in the C. elegans nose touch circuit. Thus, the hub-and-spoke architecture may implement an analog coincidence detector enabling distinct responses to distributed and localized patterns of sensory input. PMID:23707432

  9. Coincidence ion imaging with a fast frame camera

    International Nuclear Information System (INIS)

    A new time- and position-sensitive particle detection system based on a fast frame CMOS (complementary metal-oxide semiconductors) camera is developed for coincidence ion imaging. The system is composed of four major components: a conventional microchannel plate/phosphor screen ion imager, a fast frame CMOS camera, a single anode photomultiplier tube (PMT), and a high-speed digitizer. The system collects the positional information of ions from a fast frame camera through real-time centroiding while the arrival times are obtained from the timing signal of a PMT processed by a high-speed digitizer. Multi-hit capability is achieved by correlating the intensity of ion spots on each camera frame with the peak heights on the corresponding time-of-flight spectrum of a PMT. Efficient computer algorithms are developed to process camera frames and digitizer traces in real-time at 1 kHz laser repetition rate. We demonstrate the capability of this system by detecting a momentum-matched co-fragments pair (methyl and iodine cations) produced from strong field dissociative double ionization of methyl iodide

  10. A 900-channel coincidence pulse-amplitude analyser

    International Nuclear Information System (INIS)

    An analyser designed for correlation studies of pulse-height distributions from two scintillation counters is described. The analyser consists of two separate transistorized units; a dual-channel analogue-to-digital encoder and a 900-channel, 216-per-channel capacity ferrite-core store. The display and control unit for the instrument is separate and can be situated away from the analyser. The analysis mode of operation for coincident pulses on the A and B inputs of the encoder can be selected to be 30 by 30, 100 by 9 or 300 channels by 3 distributions. In the last two modes the base lines and the widths of the pulse-amplitude ''windows'' on distribution A can be selected by the operator. With 100 channels for pulse-amplitude analysis, eight ''windows'' in distribution A define eight groups of 100 channels for the B distributions. In this case we have, in effect, one 100-channel analyser for distribution A and eight separate 100-channel analysers to which B can be routed. A description of the basic circuits of the encoder and the logic of the store and display units is given. (author)

  11. Dubin-Johnson syndrome coinciding with colon cancer and atherosclerosis

    Directory of Open Access Journals (Sweden)

    Eva Sticova

    2013-01-01

    Full Text Available Hyperbilirubinemia has been presumed to prevent the process of atherogenesis and cancerogenesis mainly by decreasing oxidative stress. Dubin-Johnson syndrome is a rare, autosomal recessive, inherited disorder characterized by biphasic, predominantly conjugated hyperbilirubinemia with no progression to end-stage liver disease. The molecular basis in Dubin-Johnson syndrome is absence or deficiency of human canalicular multispecific organic anion transporter MRP2/cMOAT caused by homozygous or compound heterozygous mutation(s in ABCC2 located on chromosome 10q24. Clinical onset of the syndrome is most often seen in the late teens or early adulthood. In this report, we describe a case of previously unrecognized Dubin-Johnson syndrome caused by two novel pathogenic mutations (c.2360_2366delCCCTGTC and c.3258+1G>A, coinciding with cholestatic liver disease in an 82-year-old male patient. The patient, suffering from advanced atherosclerosis with serious involvement of coronary arteries, developed colorectal cancer with nodal metastases. The subsequent findings do not support the protective role of Dubin-Johnson type hyperbilirubinemia.

  12. The Structure of the Cubic Coincident Site Lattice Rotation Group

    Energy Technology Data Exchange (ETDEWEB)

    Reed, B W; Minich, R W; Rudd, R E; Kumar, M

    2004-01-13

    This work is intended to be a mathematical underpinning for the field of grain boundary engineering and its relatives. The interrelationships within the set of rotations producing coincident site lattices in cubic crystals are examined in detail. Besides combining previously established but widely scattered results into a unified context, the present work details newly developed representations of the group structure in terms of strings of generators (based on quaternionic number theory, and including uniqueness proofs and rules for algebraic manipulation) as well as an easily visualized topological network model. Important results that were previously obscure or not universally understood (e.g. the {Sigma} combination rule governing triple junctions) are clarified in these frameworks. The methods also facilitate several general observations, including the very different natures of twin-limited structures in two and three dimensions, the inadequacy of the {Sigma} combination rule to determine valid quadruple nodes, and a curious link between allowable grain boundary assignments and the four-color map theorem. This kind of understanding is essential to the generation of realistic statistical models of grain boundary networks (particularly in twin-dominated systems) and is especially applicable to the field of grain boundary engineering.

  13. Using triple gamma coincidences with a pixelated semiconductor Compton-PET scanner: a simulation study

    Science.gov (United States)

    Kolstein, M.; Chmeissani, M.

    2016-01-01

    The Voxel Imaging PET (VIP) Pathfinder project presents a novel design using pixelated semiconductor detectors for nuclear medicine applications to achieve the intrinsic image quality limits set by physics. The conceptual design can be extended to a Compton gamma camera. The use of a pixelated CdTe detector with voxel sizes of 1 × 1 × 2 mm3 guarantees optimal energy and spatial resolution. However, the limited time resolution of semiconductor detectors makes it impossible to use Time Of Flight (TOF) with VIP PET. TOF is used in order to improve the signal to noise ratio (SNR) by using only the most probable portion of the Line-Of-Response (LOR) instead of its entire length. To overcome the limitation of CdTe time resolution, we present in this article a simulation study using β+-γ emitting isotopes with a Compton-PET scanner. When the β+ annihilates with an electron it produces two gammas which produce a LOR in the PET scanner, while the additional gamma, when scattered in the scatter detector, provides a Compton cone that intersects with the aforementioned LOR. The intersection indicates, within a few mm of uncertainty along the LOR, the origin of the beta-gamma decay. Hence, one can limit the part of the LOR used by the image reconstruction algorithm.

  14. Simulation study of neutrons time-correlated coincidence count for uranium components based on 252Cf source-driven noise analysis method

    International Nuclear Information System (INIS)

    Background: For the intensity of high-enriched uranium's neutrons from fission is weak, the active detection method is commonly adopted. Purpose: The quality attribute of uranium components is analysed. Methods: According to the theory of neutron source-driven noise analysis method and mass measurement problem of uranium material or uranium component, Monte Carlo simulation is used to study the mass measurement of metal uranium sphere components with the same geometry and enrichment and the different masses. The time-correlation coincidence count distributions to different uranium components are obtained. Results: The source-driven time correlation coincidence measurements can provide quantities, time-dependent coincidence distributions between two detectors, which can be related to the mass of uranium components. Conclusions: By studying on the sample (radius: 4.67 cm, mass: 8 kg), it realized mass measurement to metal uranium sphere components with different masses. (authors)

  15. Activity determination of a 201Tl solution by 4πβ-γ and sum-peak coincidence methods

    International Nuclear Information System (INIS)

    201Tl is used in nuclear medicine in cardiac imaging for evaluating the injury level in cardiac muscle at rest and exercise. In this work the activity concentration of a 201Tl radioactive solution has been absolutely determined using the 4πβ-γ coincidence and sum-peak coincidence methods. The presence of 202Tl radioactive impurity that imposes some difficult in the activity measurements was taken into account in the measurements. In the sum-peak method a planar germanium detector was used. The half-lives were evaluated by the reference source method and the results obtained were (3.033 ± 0.004) d and (12.320 ± 0.163) d, respectively, for 201Tl and 202Tl. (author)

  16. Coincidence study of the 27Al(16O, 12Cα)27Al reaction at 65 MeV

    International Nuclear Information System (INIS)

    Both in-plane and out-of plane angular correlations of coincident C and α particles have been measured for 65-MeV 16O bombardment of an 27Al target. Exploitation of the time-of-flight method enabled measurement of very-low-energy alpha particles at back angles. Results from the present experiment show that evaporation from an intermediate nucleus 31P* accounts for the majority of the C-α coincidence events observed. A small number of alpha particles from the break-up of 16O* were detected at angles around that of the carbon detector. Fewer than 10% of the alpha particles detected are of pre-equilibrium origin. this finding is in sharp contrast to earlier results. 11 figures

  17. Simultaneous, coincident 2-D ACAR and DBAR using segmented HPGe detectors incorporating sub-pixel interpolation

    Science.gov (United States)

    Williams, Christopher S.; Burggraf, Larry W.; Adamson, Paul E.; Petrosky, James C.; Oxley, Mark E.

    2010-04-01

    A three-dimensional Positron Annihilation Spectrometry System (3D PASS) for determination of 3D electron-positron (e--e+) momentum densities by measuring coincident annihilation photons was designed, constructed and characterized. 3D PASS collects a single data set including correlated photon energies and coincident photon positions which are typically collected separately by two-dimensional angular correlation of annihilation radiation (2D ACAR) and two-detector coincident Doppler broadening of annihilation radiation (CDBAR) spectrometry. 3D PASS is composed of two position-sensitive, high-purity germanium (HPGe) double-sided strip detectors (DSSD(s)) linked together by a 32-channel, 50 MHz digital electronics suite. The DSSDs data were analyzed to determine location of photon detection events using an interpolation method to achieve a spatial resolution less than the 5-mm width of the DSSDs' charge collection strips. The interpolation method relies on measuring a figure-of-merit proportional to the area of the transient charges observed on both strips directly adjacent to the charge collection strip detecting the full charge deposited by the annihilation photon. This sub-pixel resolution, corresponding to the error associated with event location within a sub-pixel was measured for both DSSDs using the approach outlined in Williams et al [1] and was on the order of ± 0.20 mm (± one-standard deviation). As a result of the sub-pixel resolution, the distance between the DSSDs and material sample was reduced by a factor of five compared to what is typically required in 2D ACAR systems was necessary to achieve 0.5-mrad angular resolution. This reduction in the system's footprint decreases attenuation of the annihilation photons in the air between the material sample and the DSSDs and increases the solid angle between the sample and the DSSDs, ultimately resulting in higher system detection efficiency. 3D PASS was characterized in the same manner comparable to state

  18. Simultaneous, coincident 2-D ACAR and DBAR using segmented HPGe detectors incorporating sub-pixel interpolation

    International Nuclear Information System (INIS)

    A three-dimensional Positron Annihilation Spectrometry System (3D PASS) for determination of 3D electron-positron (e--e+) momentum densities by measuring coincident annihilation photons was designed, constructed and characterized. 3D PASS collects a single data set including correlated photon energies and coincident photon positions which are typically collected separately by two-dimensional angular correlation of annihilation radiation (2D ACAR) and two-detector coincident Doppler broadening of annihilation radiation (CDBAR) spectrometry. 3D PASS is composed of two position-sensitive, high-purity germanium (HPGe) double-sided strip detectors (DSSD(s)) linked together by a 32-channel, 50 MHz digital electronics suite. The DSSDs data were analyzed to determine location of photon detection events using an interpolation method to achieve a spatial resolution less than the 5-mm width of the DSSDs' charge collection strips. The interpolation method relies on measuring a figure-of-merit proportional to the area of the transient charges observed on both strips directly adjacent to the charge collection strip detecting the full charge deposited by the annihilation photon. This sub-pixel resolution, corresponding to the error associated with event location within a sub-pixel was measured for both DSSDs using the approach outlined in Williams et al [1] and was on the order of ± 0.20 mm (± one-standard deviation). As a result of the sub-pixel resolution, the distance between the DSSDs and material sample was reduced by a factor of five compared to what is typically required in 2D ACAR systems was necessary to achieve 0.5-mrad angular resolution. This reduction in the system's footprint decreases attenuation of the annihilation photons in the air between the material sample and the DSSDs and increases the solid angle between the sample and the DSSDs, ultimately resulting in higher system detection efficiency. 3D PASS was characterized in the same manner comparable to state

  19. Simultaneous, coincident 2-D ACAR and DBAR using segmented HPGe detectors incorporating sub-pixel interpolation

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Christopher S; Burggraf, Larry W; Petrosky, James C; Oxley, Mark E [Air Force Institute of Technology, AFIT/ENP, 2950 Hobson Way, Wright-Patterson Air Force Base, OH 45433 (United States); Adamson, Paul E, E-mail: christopher.williams@afit.ed [High Power Microwave (HPM) Technologies Branch, HPM Division, Directed Energy Directorate, Air Force Research Laboratory, Kirtland AFB, NM 87117 (United States)

    2010-04-01

    A three-dimensional Positron Annihilation Spectrometry System (3D PASS) for determination of 3D electron-positron (e{sup -}-e{sup +}) momentum densities by measuring coincident annihilation photons was designed, constructed and characterized. 3D PASS collects a single data set including correlated photon energies and coincident photon positions which are typically collected separately by two-dimensional angular correlation of annihilation radiation (2D ACAR) and two-detector coincident Doppler broadening of annihilation radiation (CDBAR) spectrometry. 3D PASS is composed of two position-sensitive, high-purity germanium (HPGe) double-sided strip detectors (DSSD(s)) linked together by a 32-channel, 50 MHz digital electronics suite. The DSSDs data were analyzed to determine location of photon detection events using an interpolation method to achieve a spatial resolution less than the 5-mm width of the DSSDs' charge collection strips. The interpolation method relies on measuring a figure-of-merit proportional to the area of the transient charges observed on both strips directly adjacent to the charge collection strip detecting the full charge deposited by the annihilation photon. This sub-pixel resolution, corresponding to the error associated with event location within a sub-pixel was measured for both DSSDs using the approach outlined in Williams et al [1] and was on the order of {+-} 0.20 mm ({+-} one-standard deviation). As a result of the sub-pixel resolution, the distance between the DSSDs and material sample was reduced by a factor of five compared to what is typically required in 2D ACAR systems was necessary to achieve 0.5-mrad angular resolution. This reduction in the system's footprint decreases attenuation of the annihilation photons in the air between the material sample and the DSSDs and increases the solid angle between the sample and the DSSDs, ultimately resulting in higher system detection efficiency. 3D PASS was characterized in the same

  20. Effects of beta/gamma radiation on nuclear waste glasses

    International Nuclear Information System (INIS)

    A key challenge in the disposal of high-level nuclear waste (HLW) in glass waste forms is the development of models of long-term performance based on sound scientific understanding of relevant phenomena. Beta decay of fission products is one source of radiation that can impact the performance of HLW glasses through the interactions of the emitted β-particles and g-rays with the atoms in the glass by ionization processes. Fused silica, alkali silicate glasses, alkali borosilicate glasses, and nuclear waste glasses are all susceptible to radiation effects from ionization. In simple glasses, defects (e.g., non-bridging oxygen and interstitial molecular oxygen) are observed experimentally. In more complex glasses, including nuclear waste glasses, similar defects are expected, and changes in microstructure, such as the formation of bubbles, have been reported. The current state of knowledge regarding the effects of β/γ radiation on the properties and microstructure of nuclear waste glasses are reviewed. (author)

  1. Realistic PET Monte Carlo Simulation With Pixelated Block Detectors, Light Sharing, Random Coincidences and Dead-Time Modeling

    OpenAIRE

    Guérin, Bastein; Fakhri, Georges El

    2008-01-01

    We have developed and validated a realistic simulation of random coincidences, pixelated block detectors, light sharing among crystal elements and dead-time in 2D and 3D positron emission tomography (PET) imaging based on the SimSET Monte Carlo simulation software. Our simulation was validated by comparison to a Monte Carlo transport code widely used for PET modeling, GATE, and to measurements made on a PET scanner.

  2. Absolute Radiometric Calibration of Narrow-Swath Imaging Sensors with Reference to Non-Coincident Wide-Swath Sensors

    Science.gov (United States)

    McCorkel, Joel; Thome, Kurtis; Lockwood, Ronald

    2012-01-01

    An inter-calibration method is developed to provide absolute radiometric calibration of narrow-swath imaging sensors with reference to non-coincident wide-swath sensors. The method predicts at-sensor radiance using non-coincident imagery from the reference sensor and knowledge of spectral reflectance of the test site. The imagery of the reference sensor is restricted to acquisitions that provide similar view and solar illumination geometry to reduce uncertainties due to directional reflectance effects. Spectral reflectance of the test site is found with a simple iterative radiative transfer method using radiance values of a well-understood wide-swath sensor and spectral shape information based on historical ground-based measurements. At-sensor radiance is calculated for the narrow-swath sensor using this spectral reflectance and atmospheric parameters that are also based on historical in situ measurements. Results of the inter-calibration method show agreement on the 2 5 percent level in most spectral regions with the vicarious calibration technique relying on coincident ground-based measurements referred to as the reflectance-based approach. While the variability of the inter-calibration method based on non-coincident image pairs is significantly larger, results are consistent with techniques relying on in situ measurements. The method is also insensitive to spectral differences between the sensors by transferring to surface spectral reflectance prior to prediction of at-sensor radiance. The utility of this inter-calibration method is made clear by its flexibility to utilize image pairings with acquisition dates differing in excess of 30 days allowing frequent absolute calibration comparisons between wide- and narrow-swath sensors.

  3. Phantom attenuation research of 2 detectors SPECT with coincident

    International Nuclear Information System (INIS)

    Objective: The photons from the body would be attenuated in their intensity by the soft tissue before they reach the detectors. Some of them lost more intensity than others when coming from the deeper body. Attenuation of the photons would distort the image, affect the image quality, and may lead to misdiagnosis. In this research the X-ray and γ-ray were used as transmission resources for accurate assessment of attenuation in each part of the body. The transmission data was used to correct the emission data from the body. Iteration algorithm was used for the reconstruction of attenuation corrected tomography images. Evaluate the efficacy of attenuation correction in duel head hybrid SPECT/coincidence PET systems (SPECT/PET) and SPECT using both the Jaszczak and the myocardial phantoms. Methods: For PET phantom study, the Jaszczak phantom was filled with the aqueous solution of 18F-fluorodeoxyglucose (FDG) and was scanned with two hybrid SPECT/coincidence PET systems respectively (Vertex Plus, Netherlands Philips ADAC Company and Hawkeye, USA GE Company). The PET images were acquired and reconstructed. Results: The 'cold' lesion, which the diameter was less than 12 mm of uncorrected image, could not be identified. But it, after correction, diameter 9 mm, would be recognized clearly, less than 7 mm would not be distinguished. Noncorrected image could only identify 'hot' lesions which the diameter were 9, 12, 14, 18, 22 and 38 mm, while in the corrected image, not only it was much better, but also the 'hot' le-sion of 6 mm was distinguished. In Hawkeye, the same situation, the corrected image of was improved obviously; the disparity of counts between surrounding and deep center less, and the counts in deep center were compensated. There were only 3 round 'cold' lesions could be recognized, the diameter: 14, 18 and 20 mm; all of them which diameter were less than 12 mm could not be distinguished. One in the center was al-most as background, and could not be identified

  4. Representation of the activity unit for sup 56 Co. Darstellung der Aktivitaetseinheit fuer sup 56 Co

    Energy Technology Data Exchange (ETDEWEB)

    Funck, E.; Schoetzig, U.

    1991-02-01

    Three measuring processes were used: The 4 {pi}{beta}-{gamma} coincidence method using a counter proportional to pressure and a 4 {pi}{gamma} borehole Na I (T1) scintillation counter, integral pulse counting with a large-volume 4 {pi} {gamma} - NAI(T1) scintillation counter and measurement via a selected {gamma} line with calibrated germanium detectors. The results of the three processes of measurement, and the relative standard deviation is 0.2%. (orig.).

  5. Time-and-frequency gated photon coincidence counting; a novel multidimensional spectroscopy tool

    CERN Document Server

    Dorfman, Konstantin E

    2016-01-01

    Coherent multidimensional optical spectroscopy techniques are broadly applied across the electromagnetic spectrum ranging from NMR to the UV. These reveal properties of matter through correlation plots of signal fields generated in response to sequences of short pulses with variable delays. Here we discuss a new class of multidimensional techniques obtained by time-and-frequency resolved photon coincidence counting measurements of N photons which constitutes a 2N dimensional spectrum. A compact description of these signals is developed based on time ordered superoperators rather than the normally ordered ordinary operators used in Glauber's photon counting formalism. The independent control of the time and frequency gate parameters reveals details of matter dynamics not available otherwise. Application to an anharmonic oscillator model with fluctuating energy and anharmonicity demonstrates the power of these signals.

  6. Coincident occurrences of tropical individual cirrus clouds and deep convective systems derived from TRMM observations

    Science.gov (United States)

    Lin, Bing; Xu, Kuan-Man; Minnis, Patrick; Wielicki, Bruce A.; Hu, Yongxiang; Chambers, Lin; Fan, Tai-Fang; Sun, Wenbo

    2007-07-01

    Satellite measurements of cloud properties and atmospheric radiation were used to investigate the effect of spatial and temporal scales on the coincident occurrences of tropical individual cirrus clouds (ICCs) and deep convective systems (DCSs). There is little or even negative correlation between instantaneous occurrences of ICC and DCS in small areas. When spatial and temporal domains are increased, ICCs become more dependent on DCSs due to the origination of many ICCs from DCSs and moisture supply from the DCS in the upper troposphere for the ICCs to grow, resulting in significant positive correlation between the two types of clouds. The estimated radiative feedback due to the change in tropical high cloud area coverage with sea surface temperature appears small and about -0.14 Wm-2K-1, which would not cancel out the estimated anthropogenic forcing of doubled atmospheric CO2.

  7. Calibration and experimental comparison of the active well coincidence counter and PHONID-II

    International Nuclear Information System (INIS)

    A team from EURATOM-Luxembourg, JRC-Ispra, Los Alamos, and International Atomic Energy Agency (IAEA) has performed measurements to directly compare the Active Well Coincidence Counter (AWCC) with the PHONID-II for the assay of highly enriched uranium (HEU). The comparison included an evaluation of counting rates, sensitivity, accuracy, linearity, stability, and matrix effects. Samples used in the evaluation included highly enriched uranium metal, U3O8 U-Al alloy plates, UF4, and (uranium/thorium) coated particles covering the mass range from a few grams up to about 5 kg of 235U. These materials are typical of the HEU samples under inspector verification. This report gives the results of the intercomparison as well as calibration information for the above material categories

  8. True coincidence summing corrections for an extended energy range HPGe detector

    Energy Technology Data Exchange (ETDEWEB)

    Venegas-Argumedo, Y. [Centro de Investigación en Materiales Avanzados (CIMAV), Miguel de Cervantes 120, Chihuahua, Chih 31109 (Mexico); M.S. Student at CIMAV (Mexico); Montero-Cabrera, M. E., E-mail: elena.montero@cimav.edu.mx [Centro de Investigación en Materiales Avanzados (CIMAV), Miguel de Cervantes 120, Chihuahua, Chih 31109 (Mexico)

    2015-07-23

    True coincidence summing (TCS) effect for natural radioactive families of U-238 and Th-232 represents a problem when an environmental sample with a close source-detector geometry measurement is performed. By using a certified multi-nuclide standard source to calibrate an energy extended range (XtRa) HPGe detector, it is possible to obtain an intensity spectrum slightly affected by the TCS effect with energies from 46 to 1836 keV. In this work, the equations and some other considerations required to calculate the TCS correction factor for isotopes of natural radioactive chains are described. It is projected a validation of the calibration, performed with the IAEA-CU-2006-03 samples (soil and water)

  9. Detection of the Cerenkov effect of β particles in a liquid by rapid photomultipliers in coincidence

    International Nuclear Information System (INIS)

    An electronic assembly in the nanosecond region was studied for the detection of weak light pulses due to the Cerenkov effect, which an ordinary photomultiplier represents by pulses of a level comparable to that of the thermal noise at ambient temperature. The elimination of these extraneous counts was effected by rapid coincidence between two photomultipliers viewing the same source of light. This arrangement, eliminating the cooling normally used in this type of detection, permits a significant reduction of the volume and weight of the apparatus used with the Cerenkov detector proper. The apparatus described has been applied to the detection of β-emitters in solution; it has permitted the measurement of Sr-Y activity in water, in concentrations at the MCP level. (author)

  10. Design and performance of the Savannah River Site Billet Active Well Coincidence Counter

    International Nuclear Information System (INIS)

    The Savannah River Site (SRS) has acquired, installed, and tested a custom-built Billet Active Well (neutron) Coincidence Counter (BAWCC). The BAWCC is used to make accountability measurements of the 235U content of U-Al coextrusion billets in the SRS fuel fabrication facility. The instrument design incorporates a unique center-source configuration, with two moderated americium-lithium (AmLi) neutron sources located in a central spindle that inserts through the center hole of the U-Al billets. This configuration, a result of earlier experimental studies at SRS, yields improved response and precision for billet assay when compared to the standard AWCC source arrangement. Initial tests of the BAWCC at SRS have yielded one-sigma uncertainties of 0.8--1.0% for a fifteen-minute assay. This paper will describe the design, testing program and performance characteristics of the BAWCC

  11. PLUMEX II: A second set of coincident radar and rocket observations of equatorial spread-F

    International Nuclear Information System (INIS)

    PLUMEX II, the second rocket in a two-rocket operation that successfully executed coincident rocket and radar measurements of backscatter plumes and plasma depletions, was launched into the mid-phase of well-developed equatorial spread-F. In contrast with the first operation, the PLUMEX II results show large scale F-region irregularities only on the bottomside gradient with smaller scale irregularities (i.e., small scale structure imbedded in larger scale features) less intense than corresponding observations in PLUMEX I. The latter result could support current interpretations of east-west plume asymmetry which suggests that during initial upwelling the western wall of a plume (the PLUMEX I case) is more unstable than its eastern counterpart (the PLUMEX II case). In addition, ion mass spectrometer results are found to provide further support for an ion transport model which ''captures'' bottomside ions in an upwelling bubble and transports them to high altitudes

  12. Time-and-frequency-gated photon coincidence counting; a novel multidimensional spectroscopy tool

    Science.gov (United States)

    Dorfman, Konstantin E.; Mukamel, Shaul

    2016-08-01

    Coherent multidimensional optical spectroscopy is broadly applied across the electromagnetic spectrum ranging from NMR to UV. These techniques reveal the properties of matter through the correlation plots of signal fields generated in response to sequences of short pulses with variable delays. Here we discuss a new class of multidimensional techniques obtained by the time-and-frequency-resolved photon coincidence counting measurements of N photons, which constitute a 2N dimensional spectrum. A compact description of these signals is developed based on time-ordered superoperators rather than the normally ordered ordinary operators used in Glauber's photon counting formalism. The independent control of the time and frequency gate parameters reveals fine details of matter dynamics not available otherwise. These signal are illustrated for application to an anharmonic oscillator model with fluctuating energy and anharmonicity.

  13. A Dead Time Correction for Overlapped Pulse Signals for a Thermal Neutron Coincidence Counter System

    International Nuclear Information System (INIS)

    A typical well-type thermal neutron counter uses many He-3 proportional counter neutron detectors to enhance its measurement efficiency. Such, He-3 detectors are grouped with several other groups to make one output signal. Then the group signals are connected to shift register coincidence electronics using an OR gate device. But a loss of pulse signals occurs in an OR gate device because a simultaneous pulse signal is recognized as one pulse signal. This paper describes the development of a new circuit that processes overlapped pulse signals and the effect of the dead time with an OR gate device of an ACP Safeguards Neutron Counter (ASNC) for an Advanced Spent Fuel Conditioning Process (ACP)

  14. True coincidence summing corrections for an extended energy range HPGe detector

    International Nuclear Information System (INIS)

    True coincidence summing (TCS) effect for natural radioactive families of U-238 and Th-232 represents a problem when an environmental sample with a close source-detector geometry measurement is performed. By using a certified multi-nuclide standard source to calibrate an energy extended range (XtRa) HPGe detector, it is possible to obtain an intensity spectrum slightly affected by the TCS effect with energies from 46 to 1836 keV. In this work, the equations and some other considerations required to calculate the TCS correction factor for isotopes of natural radioactive chains are described. It is projected a validation of the calibration, performed with the IAEA-CU-2006-03 samples (soil and water)

  15. Elemental PGNAA analysis using gamma-gamma coincidence counting with the library least-squares approach

    Science.gov (United States)

    Metwally, Walid A.; Gardner, Robin P.; Mayo, Charles W.

    2004-01-01

    An accurate method for determining elemental analysis using gamma-gamma coincidence counting is presented. To demonstrate the feasibility of this method for PGNAA, a system of three radioisotopes (Na-24, Co-60 and Cs-134) that emit coincident gamma rays was used. Two HPGe detectors were connected to a system that allowed both singles and coincidences to be collected simultaneously. A known mixture of the three radioisotopes was used and data was deliberately collected at relatively high counting rates to determine the effect of pulse pile-up distortion. The results obtained, with the library least-squares analysis, of both the normal and coincidence counting are presented and compared to the known amounts. The coincidence results are shown to give much better accuracy. It appears that in addition to the expected advantage of reduced background, the coincidence approach is considerably more resistant to pulse pile-up distortion.

  16. Detector system for the study of low energy heavy ion reactions using kinematic coincidence technique

    International Nuclear Information System (INIS)

    The characteristics and performance of a new detector system developed for the study of low energy heavy ion binary reactions using the kinematic coincidence technique are presented. The detector system has been developed to carry out experiments such as multi-nucleon transfer reactions using the General Purpose Scattering Chamber (GPSC) facility at IUAC [1,2]. The detector system consists of a pair of two-dimensional position sensitive multi wire proportional counter (MWPC) and a ΔE−E gas ionization chamber. Both MWPC have an active area of 5×5 cm2, and provide position signals in horizontal (X) and vertical (Y) plane, and timing signal for time of flight measurements. The main design feature of MWPC is the reduced wire pitch of 0.025 in. (0.635 mm) in all electrodes, giving uniform field and faster charge collection, and usage of 10μm diameter in anode frame which gives higher gains. The position resolution of the detectors was determined to be 0.45 mm FWHM and time resolution was estimated to be 400 ps FWHM. The detector could handle heavy ion count rates exceeding 100 kHz without any break down. The timing and position signals of the detectors are used for kinematic coincidence measurements and subsequent extraction of their mass and angular distributions. The ionization chamber has a conventional transverse field geometry with segmented anode providing multiple ΔE signals for nuclear charge (Z) identification. This article describes systematic study of these detectors in terms of efficiency, count rate handling capability, time, position and energy resolution

  17. Obesidade e asma: associação ou coincidência? Obesity and asthma: association or coincidence?

    Directory of Open Access Journals (Sweden)

    Daniella Fernandes Camilo

    2010-02-01

    Full Text Available OBJETIVO: A asma e a obesidade estão entre as maiores causas de morbidade na infância e adolescência. A obesidade precoce aumenta as chances de doenças crônicas degenerativas no adulto. Embora a concomitância de ambas as situações clínicas vem sendo demonstrada em vários estudos, os mecanismos intrínsecos dessa associação ainda são pouco conhecidos. Portanto, o objetivo deste artigo foi revisar os principais trabalhos sobre a associação de obesidade e asma e verificar se existe relação de causa e efeito entre ambas. FONTES DOS DADOS: Revisão sistemática baseada em bases de dados indexadas MEDLINE (PubMed e SciELO. Foram revisados artigos originais (transversal, caso-controle e prospectivo e meta-análises publicados no período de janeiro de 1998 a janeiro de 2008. Foram pesquisados estudos divulgados em língua inglesa, espanhola e portuguesa. SÍNTESE DOS DADOS: Embora existam muitos estudos sobre as crescentes prevalências da asma e da obesidade, poucos estabelecem relações de causa e efeito entre ambas. Os mecanismos fisiopatológicos e os fatores envolvidos nesse processo ainda são pouco conhecidos. CONCLUSÃO: O rigor metodológico em estudos futuros deverá buscar respostas para melhor entender se existe associação entre asma e obesidade, ou se a relação entre ambas as doenças é coincidência.OBJECTIVE: Asthma and obesity are among the major causes of morbidity in childhood and adolescence. Early obesity increases the chances of chronic degenerative diseases in adults. Although the concomitance or both clinical situations are being demonstrated in various studies, the intrinsic mechanisms of this association are still very little known. Therefore, the objective of this article was to review the main studies on the association of obesity and asthma and check if there is a cause-effect relation between them. SOURCES: Systematic review based on indexed data bases MEDLINE (PubMed and SciELO. Original articles

  18. The coincidence of IgA nephropathy and Fabry disease

    Directory of Open Access Journals (Sweden)

    Maixnerová Dita

    2013-01-01

    Full Text Available Abstract Background IgA nephropathy (IgAN is the most common glomerulonephritis, which may also coexist with other diseases. We present two patients with an unusual coincidence of IgAN and Fabry disease (FD. Case presentation A 26 year-old man underwent a renal biopsy in February 2001. Histopathology showed very advanced IgAN and vascular changes as a result of hypertension. Because of his progressive renal insufficiency the patient began hemodialysis in August 2001. By means of the blood spot test screening method the diagnosis of FD was suspected. Low activity of alpha-galactosidase A in the patient’s plasma and leukocytes and DNA analysis confirmed the diagnosis of FD. Enzyme replacement therapy started in July 2004. Then the patient underwent kidney transplantation in November 2005. Currently, his actual serum creatinine level is 250 μmol/l. Other organ damages included hypertrophic cardiomyopathy, neuropathic pain and febrile crisis. After enzyme replacement therapy, myocardial hypertrophy has stabilized and other symptoms have disappeared. No further progression of the disease has been noted. The other patient, a 30 year-old woman, suffered from long-term hematuria with a good renal function. Recently, proteinuria (2.6 g/day appeared and a renal biopsy was performed. Histopathology showed IgAN with remarkably enlarged podocytes. A combination of IgAN and a high suspicion of FD was diagnosed. Electron microscopy revealed dense deposits in paramesangial areas typical for IgAN and podocytes with inclusive zebra bodies and myelin figures characteristic of FD. FD was confirmed by the decreased alpha-galactosidase A activity in plasma and leukocytes and by DNA and RNA analysis. Enzyme replacement therapy and family screening were initiated. Conclusions Our results emphasize the role of complexity in the process of diagnostic evaluation of kidney biopsy samples. Electron microscopy represents an integral part of histopathology, and genetic

  19. Design and performance of A 3He-free coincidence counter based on parallel plate boron-lined proportional technology

    Science.gov (United States)

    Henzlova, D.; Menlove, H. O.; Marlow, J. B.

    2015-07-01

    Thermal neutron counters utilized and developed for deployment as non-destructive assay (NDA) instruments in the field of nuclear safeguards traditionally rely on 3He-based proportional counting systems. 3He-based proportional counters have provided core NDA detection capabilities for several decades and have proven to be extremely reliable with range of features highly desirable for nuclear facility deployment. Facing the current depletion of 3He gas supply and the continuing uncertainty of options for future resupply, a search for detection technologies that could provide feasible short-term alternative to 3He gas was initiated worldwide. As part of this effort, Los Alamos National Laboratory (LANL) designed and built a 3He-free full scale thermal neutron coincidence counter based on boron-lined proportional technology. The boron-lined technology was selected in a comprehensive inter-comparison exercise based on its favorable performance against safeguards specific parameters. This paper provides an overview of the design and initial performance evaluation of the prototype High Level Neutron counter-Boron (HLNB). The initial results suggest that current HLNB design is capable to provide ~80% performance of a selected reference 3He-based coincidence counter (High Level Neutron Coincidence Counter, HLNCC). Similar samples are expected to be measurable in both systems, however, slightly longer measurement times may be anticipated for large samples in HLNB. The initial evaluation helped to identify potential for further performance improvements via additional tailoring of boron-layer thickness.

  20. Using anisotropies in prompt fission neutron coincidences to assess the neutron multiplication of highly multiplying subcritical plutonium assemblies

    Science.gov (United States)

    Mueller, J. M.; Mattingly, J.

    2016-07-01

    There is a significant and well-known anisotropy between the prompt neutrons emitted from a single fission event; these neutrons are most likely to be observed at angles near 0° or 180° relative to each other. However, the propagation of this anisotropy through different generations of a fission chain reaction has not been previously studied. We have measured this anisotropy in neutron-neutron coincidences from a subcritical highly-multiplying assembly of plutonium metal. The assembly was a 4.5 kg α-phase plutonium metal sphere composed of 94% 239Pu and 6% 240Pu by mass. Data were collected using two EJ-309 liquid scintillators and two EJ-299 plastic scintillators. The angular distribution of neutron-neutron coincidences was measured at 90° and 180° and found to be largely isotropic. Simulations were performed using MCNPX-PoliMi of similar plutonium metal spheres of varying sizes and a correlation between the neutron multiplication of the assembly and the anisotropy of neutron-neutron coincidences was observed. In principle, this correlation could be used to assess the neutron multiplication of an unknown assembly.

  1. Design and performance of A 3He-free coincidence counter based on parallel plate boron-lined proportional technology

    International Nuclear Information System (INIS)

    Thermal neutron counters utilized and developed for deployment as non-destructive assay (NDA) instruments in the field of nuclear safeguards traditionally rely on 3He-based proportional counting systems. 3He-based proportional counters have provided core NDA detection capabilities for several decades and have proven to be extremely reliable with range of features highly desirable for nuclear facility deployment. Facing the current depletion of 3He gas supply and the continuing uncertainty of options for future resupply, a search for detection technologies that could provide feasible short-term alternative to 3He gas was initiated worldwide. As part of this effort, Los Alamos National Laboratory (LANL) designed and built a 3He-free full scale thermal neutron coincidence counter based on boron-lined proportional technology. The boron-lined technology was selected in a comprehensive inter-comparison exercise based on its favorable performance against safeguards specific parameters. This paper provides an overview of the design and initial performance evaluation of the prototype High Level Neutron counter—Boron (HLNB). The initial results suggest that current HLNB design is capable to provide ~80% performance of a selected reference 3He-based coincidence counter (High Level Neutron Coincidence Counter, HLNCC). Similar samples are expected to be measurable in both systems, however, slightly longer measurement times may be anticipated for large samples in HLNB. The initial evaluation helped to identify potential for further performance improvements via additional tailoring of boron-layer thickness

  2. Synchrotron-based double imaging photoelectron/photoion coincidence spectroscopy of radicals produced in a flow tube: OH and OD

    International Nuclear Information System (INIS)

    In this study, we present a microwave discharge flow tube coupled with a double imaging electron/ion coincidence device and vacuum ultraviolet (VUV) synchrotron radiation. The system has been applied to the study of the photoelectron spectroscopy of the well-known radicals OH and OD. The coincidence imaging scheme provides a high selectivity and yields the spectra of the pure radicals, removing the ever-present contributions from excess reactants, background, or secondary products, and therefore obviating the need for a prior knowledge of all possible byproducts. The photoelectron spectra encompassing the X3Σ- ground state of the OH+ and OD+ cations have been extracted and the vibrational constants compared satisfactorily to existing literature values. Future advantages of this approach include measurement of high resolution VUV spectroscopy of radicals, their absolute photoionization cross section, and species/isomer identification in chemical reactions as a function of time

  3. Synchrotron-based double imaging photoelectron/photoion coincidence spectroscopy of radicals produced in a flow tube: OH and OD

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Gustavo A.; Tang, Xiaofeng; Gil, Jean-François; Nahon, Laurent [Synchrotron SOLEIL, L’Orme des Merisiers, St. Aubin, BP 48, 91192 Gif sur Yvette (France); Ward, Michael; Batut, Sebastien; Fittschen, Christa [PC2A, Université de Lille 1, UMR CNRS-USTL 8522, Cité Scientifique Bât. C11, F-59655 Villeneuve d’Ascq (France); Taatjes, Craig A.; Osborn, David L. [Combustion Research Facility, Mail Stop 9055, Sandia National Laboratories, Livermore, California 94551-0969 (United States); Loison, Jean-Christophe [ISM, Université Bordeaux 1, CNRS, 351 cours de la Libération, 33405 Talence Cedex (France)

    2015-04-28

    We present a microwave discharge flow tube coupled with a double imaging electron/ion coincidence device and vacuum ultraviolet (VUV) synchrotron radiation. The system has been applied to the study of the photoelectron spectroscopy of the well-known radicals OH and OD. The coincidence imaging scheme provides a high selectivity and yields the spectra of the pure radicals, removing the ever-present contributions from excess reactants, background, or secondary products, and therefore obviating the need for a prior knowledge of all possible byproducts. The photoelectron spectra encompassing the X{sup 3}Σ{sup −} ground state of the OH{sup +} and OD{sup +} cations have been extracted and the vibrational constants compared satisfactorily to existing literature values. Future advantages of this approach include measurement of high resolution VUV spectroscopy of radicals, their absolute photoionization cross section, and species/isomer identification in chemical reactions as a function of time.

  4. The influence of radiation and light on Ps formation in PMMA and PE studied by coincidence Doppler-broadening spectroscopy

    CERN Document Server

    Suzuki, T; Shantarovich, V; Kondo, K; Hamada, E; Matso, M; Ma Li; Ito, Y

    2003-01-01

    Using two Ge detectors, the high-resolution Doppler-broadening energy spectra of positron annihilation gamma rays has been obtained by measuring the coincidences of the two photons. Light bleaching and oxygen effects on positron annihilation were investigated in this way. A large enhancement of the high-momentum part of the coincidence Doppler spectra was observed in poly(methylmethacrylate) (PMMA), which contains oxygen atoms in the polymer structure. Bleaching experiments in PMMA and in copolymer ethylene-methylmethacrylate EMMA (LDPE+MMA 3 mol%) have demonstrated that the enhancement effect may be due to the trapping of positrons by the polar -C sup + 6-O sup - groups, followed by positron annihilation with the electrons belonging to oxygen.

  5. A search for double-electron capture in 74Se using coincidence/anticoincidence gamma-ray spectrometry

    CERN Document Server

    Jeskovsky, M; Kovacik, A; Povinec, P P; Puppe, P; Stanicek, J; Sykora, I; Simkovic, F; Thies, J H

    2015-01-01

    Evaluation of single, coincidence and anticoincidence gamma-ray spectrometry methods has been carried out with the aim to search for double-electron capture in 74Se. This process is unique, because there is probability for transition to the 2+ excited state in 74Ge (1204 keV), and de-excitation through two gamma-quanta cascade with energies of 595.9 keV and 608.4 keV. Long-term measurements with anticosmic shielded HPGe spectrometer and the coincidence HPGe-NaI(Tl) spectrometer did not show any evidence for the double-electron capture in 74Se. The best limit for the half-life of the double electron capture in 74Se (both for the neutrinoless and two neutrino processes) was estimated to be >1.5x10E19 years.

  6. The influence of radiation and light on Ps formation in PMMA and PE studied by coincidence Doppler-broadening spectroscopy

    International Nuclear Information System (INIS)

    Using two Ge detectors, the high-resolution Doppler-broadening energy spectra of positron annihilation gamma rays has been obtained by measuring the coincidences of the two photons. Light bleaching and oxygen effects on positron annihilation were investigated in this way. A large enhancement of the high-momentum part of the coincidence Doppler spectra was observed in poly(methylmethacrylate) (PMMA), which contains oxygen atoms in the polymer structure. Bleaching experiments in PMMA and in copolymer ethylene-methylmethacrylate EMMA (LDPE+MMA 3 mol%) have demonstrated that the enhancement effect may be due to the trapping of positrons by the polar -C+6-O- groups, followed by positron annihilation with the electrons belonging to oxygen

  7. Standardization and decay data of /sup 169/Yb

    Energy Technology Data Exchange (ETDEWEB)

    Funck, E.; Schoetzig, U.; Walz, K.F. (Physikalisch-Technische Bundesanstalt, Braunschweig (Germany, F.R.))

    1983-08-01

    The gamma- and x-ray-emission probabilities per decay of /sup 169/Yb were determined from the ratio of the emission rates and the activity. The emission rates were measured with calibrated semiconductor spectrometers and the activity with 4..pi beta..-..gamma.. coincidence counting systems and 4..pi gamma..-NaI (Tl) high-efficiency-counting device. Measurements of the half life were carried out with a 4..pi gamma.. ionization chamber.

  8. The use of computed radiography plates to determine light and radiation field coincidence

    International Nuclear Information System (INIS)

    Purpose: Photo-stimulable phosphor computed radiography (CR) has characteristics that allow the output to be manipulated by both radiation and optical light. The authors have developed a method that uses these characteristics to carry out radiation field and light field coincidence quality assurance on linear accelerators.Methods: CR detectors from Kodak were used outside their cassettes to measure both radiation and light field edges from a Varian linear accelerator. The CR detector was first exposed to a radiation field and then to a slightly smaller light field. The light impinged on the detector's latent image, removing to an extent the portion exposed to the light field. The detector was then digitally scanned. A MATLAB-based algorithm was developed to automatically analyze the images and determine the edges of the light and radiation fields, the vector between the field centers, and the crosshair center. Radiographic film was also used as a control to confirm the radiation field size.Results: Analysis showed a high degree of repeatability with the proposed method. Results between the proposed method and radiographic film showed excellent agreement of the radiation field. The effect of varying monitor units and light exposure time was tested and found to be very small. Radiation and light field sizes were determined with an uncertainty of less than 1 mm, and light and crosshair centers were determined within 0.1 mm.Conclusions: A new method was developed to digitally determine the radiation and light field size using CR photo-stimulable phosphor plates. The method is quick and reproducible, allowing for the streamlined and robust assessment of light and radiation field coincidence, with no observer interpretation needed

  9. On coincidence problem and attractor solutions in ELKO dark energy model

    CERN Document Server

    Sadjadi, H Mohseni

    2011-01-01

    We study the critical points of a Universe dominated by ELKO spinor field dark energy and a barotropic matter in an almost general case. The coincidence problem and attractor solutions are discussed and it is shown the coincidence problem can not be alleviated in this model.

  10. Calibration of Muon Detector for Coincidence Cathodoluminescence Experiments

    OpenAIRE

    Zia, Kenneth; Dennison, JR

    2015-01-01

    A muon scintillation detector has been calibrated by measuring the magnitude and angular dependence of high energy cosmic background radiation events. Optimizing dark current as a function of voltage across the photomultiplier tube (PMT) detector was essential for accurate counting of current pulses as narrow as the counts in the PMT. Measurements of the crosssection zenith angle were also optimized by sweeping the detector across the horizon and from t...

  11. X-Rays Emitted in Coincidence with the Fission Of Cf252

    International Nuclear Information System (INIS)

    A possible technique for studying charge distribution in fission is the simultaneous measurement of the kinetic energies of both fragments and the energy of the K-X-rays emitted in coincidence with fission. The two kinetic energies define the masses of the fragments and the X-ray energy defines the atomic number of one fragment. For such a measurement to yield information on charge distribution, it is necessary that the number of vacancies in the K-shell vary slowly with the mass and charge of the fragments. If the vacancies are produced in the fission act itself, it seems likely that this condition is satisfied. X-rays so produced would be emitted within ∼ 10-15 s after fission, If, on the other hand, the vacancies are produced by internal conversion of gamma rays emitted after fission, it is quite possible that the yield of X-rays may vary markedly from one nucleus to the next. Such X-rays would be emitted with lifetimes characteristic of the converted gamma rays - probably at least as long as 10-12 s. We have measured the lifetime of the X-rays emitted in coincidence with fission with a time resolution of ∼ 1 ns. The spectrum of X-rays shows two peaks, one at the proper energy for light fission fragments, the other at the proper energy for heavy fragments. The number of K-X-rays per fission is approximately 0,6. The two peaks fall off in approximately the same manner with increasing time after fission. The apparent mean lifetime is about 1 ns, but the decay curve is complex and does not contain any obvious single component. There is no evidence of an appreciable number of K-X-rays emitted with lifetimes less than about 0.4 ns. Our conclusions from these results are that most, if not all, of the K-vacancies are due to internal conversion but that many different gamma-ray lifetimes appear in the decay curve. Experiments are in progress to measure simultaneously the kinetic energies of the two fragments and the K-X-ray energy. (author)

  12. Multiple-coincidence of flood waves on the main river and its tributaries

    Science.gov (United States)

    Prohaska, S.; Ilic, A.; Majkic, B.

    2008-11-01

    This paper addresses the definition of multiple coincidences of flood waves on the main river and its tributaries. Contrary to previous studies of partial coincidences of various flood parameters (Prohaska 1999) for the main river and one of its tributaries, this procedure allows for the definition of complex (multiple) coincidences of a single parameter for the main river and several of its tributaries. In particular, coincidence is defined for the major parameter which characterizes a flood (i.e., the flood wave volume). The paper gives a practical example of the analysis of simultaneous flood waves on the Danube and its main tributaries in Serbia: the Tisa and the Sava rivers. The procedure for potential use of the established coincidence functions in applied water management and forecasting is also described in the paper.

  13. A threshold photoelectron-photoion coincidence spectrometer with double velocity imaging using synchrotron radiation

    International Nuclear Information System (INIS)

    A novel threshold photoelectron-photoion coincidence (TPEPICO) imaging spectrometer at the U14-A beamline of the Hefei National Synchrotron Radiation Laboratory is presented. A set of open electron and ion lenses are utilized to map velocity imaging of photoelectrons and photoions simultaneously, in which a repelling electric field using an extra lens is applied to magnify images of photoelectrons instead of traditional accelerating electric field in order to suppress the contribution of energetic electrons in the threshold photoelectron spectroscopy (TPES) and the mass-selected TPEPICO spectroscopy. The typical energy resolution of TPES is measured to be 9 meV (full width at half maximum), as shown on the 2P1/2 ionization of argon. The measured mass resolving power for the present TPEPICO imaging spectrometer is above 900 of M/ΔM. Subsequently as a benchmark, oxygen molecule is photoionized by monochromatic synchrotron radiation at 20.298 eV and dissociates to an oxygen atomic ion and a neutral oxygen atom, and the translation energy distribution of oxygen atomic ion is measured by the time-sliced imaging based on mass-selected TPEPICO experiment. The kinetic energy resolution of the present ion velocity imaging is better than 3% of ΔE/E.

  14. A Rapid Coordinate Transformation Method Applied in Industrial Robot Calibration Based on Characteristic Line Coincidence

    Directory of Open Access Journals (Sweden)

    Bailing Liu

    2016-02-01

    Full Text Available Coordinate transformation plays an indispensable role in industrial measurements, including photogrammetry, geodesy, laser 3-D measurement and robotics. The widely applied methods of coordinate transformation are generally based on solving the equations of point clouds. Despite the high accuracy, this might result in no solution due to the use of ill conditioned matrices. In this paper, a novel coordinate transformation method is proposed, not based on the equation solution but based on the geometric transformation. We construct characteristic lines to represent the coordinate systems. According to the space geometry relation, the characteristic line scan is made to coincide by a series of rotations and translations. The transformation matrix can be obtained using matrix transformation theory. Experiments are designed to compare the proposed method with other methods. The results show that the proposed method has the same high accuracy, but the operation is more convenient and flexible. A multi-sensor combined measurement system is also presented to improve the position accuracy of a robot with the calibration of the robot kinematic parameters. Experimental verification shows that the position accuracy of robot manipulator is improved by 45.8% with the proposed method and robot calibration.

  15. A Rapid Coordinate Transformation Method Applied in Industrial Robot Calibration Based on Characteristic Line Coincidence.

    Science.gov (United States)

    Liu, Bailing; Zhang, Fumin; Qu, Xinghua; Shi, Xiaojia

    2016-01-01

    Coordinate transformation plays an indispensable role in industrial measurements, including photogrammetry, geodesy, laser 3-D measurement and robotics. The widely applied methods of coordinate transformation are generally based on solving the equations of point clouds. Despite the high accuracy, this might result in no solution due to the use of ill conditioned matrices. In this paper, a novel coordinate transformation method is proposed, not based on the equation solution but based on the geometric transformation. We construct characteristic lines to represent the coordinate systems. According to the space geometry relation, the characteristic line scan is made to coincide by a series of rotations and translations. The transformation matrix can be obtained using matrix transformation theory. Experiments are designed to compare the proposed method with other methods. The results show that the proposed method has the same high accuracy, but the operation is more convenient and flexible. A multi-sensor combined measurement system is also presented to improve the position accuracy of a robot with the calibration of the robot kinematic parameters. Experimental verification shows that the position accuracy of robot manipulator is improved by 45.8% with the proposed method and robot calibration. PMID:26901203

  16. Unbiased estimators of coincidence and correlation in non-analogous Monte Carlo particle transport

    International Nuclear Information System (INIS)

    Highlights: • The history splitting method was developed for non-Boltzmann Monte Carlo estimators. • The method allows variance reduction for pulse-height and higher moment estimators. • It works in highly multiplicative problems but Russian roulette has to be replaced. • Estimation of higher moments allows the simulation of neutron noise measurements. • Biased sampling of fission helps the effective simulation of neutron noise methods. - Abstract: The conventional non-analogous Monte Carlo methods are optimized to preserve the mean value of the distributions. Therefore, they are not suited to non-Boltzmann problems such as the estimation of coincidences or correlations. This paper presents a general method called history splitting for the non-analogous estimation of such quantities. The basic principle of the method is that a non-analogous particle history can be interpreted as a collection of analogous histories with different weights according to the probability of their realization. Calculations with a simple Monte Carlo program for a pulse-height-type estimator prove that the method is feasible and provides unbiased estimation. Different variance reduction techniques have been tried with the method and Russian roulette turned out to be ineffective in high multiplicity systems. An alternative history control method is applied instead. Simulation results of an auto-correlation (Rossi-α) measurement show that even the reconstruction of the higher moments is possible with the history splitting method, which makes the simulation of neutron noise measurements feasible

  17. Coincident helminth infection modulates systemic inflammation and immune activation in active pulmonary tuberculosis.

    Directory of Open Access Journals (Sweden)

    Parakkal Jovvian George

    Full Text Available Helminth infections are known to modulate innate and adaptive immune responses in active and latent tuberculosis (TB. However, the role of helminth infections in modulating responses associated with inflammation and immune activation (reflecting disease activity and/or severity in TB is not known.We measured markers of inflammation and immune activation in active pulmonary TB individuals (ATB with co-incidental Strongyloides stercoralis (Ss infection. These included systemic levels of acute phase proteins, matrix metalloproteinases and their endogenous inhibitors and immune activation markers. As a control, we measured the systemic levels of the same molecules in TB-uninfected individuals (NTB with or without Ss infection.Our data confirm that ATB is associated with elevated levels of the various measured molecules when compared to those seen in NTB. Our data also reveal that co-incident Ss infection in ATB individuals is associated with significantly decreased circulating levels of acute phase proteins, matrix metalloproteinases, tissue inhibitors of matrix metalloproteinases as well as the systemic immune activation markers, sCD14 and sCD163. These changes are specific to ATB since they are absent in NTB individuals with Ss infection.Our data therefore reveal a profound effect of Ss infection on the markers associated with TB disease activity and severity and indicate that co-incidental helminth infections might dampen the severity of TB disease.

  18. Variance estimation in neutron coincidence counting using the bootstrap method

    International Nuclear Information System (INIS)

    In the study, we demonstrate the implementation of the “bootstrap” method for a reliable estimation of the statistical error in Neutron Multiplicity Counting (NMC) on plutonium samples. The “bootstrap” method estimates the variance of a measurement through a re-sampling process, in which a large number of pseudo-samples are generated, from which the so-called bootstrap distribution is generated. The outline of the present study is to give a full description of the bootstrapping procedure, and to validate, through experimental results, the reliability of the estimated variance. Results indicate both a very good agreement between the measured variance and the variance obtained through the bootstrap method, and a robustness of the method with respect to the duration of the measurement and the bootstrap parameters

  19. Variance estimation in neutron coincidence counting using the bootstrap method

    Energy Technology Data Exchange (ETDEWEB)

    Dubi, C., E-mail: chendb331@gmail.com [Physics Department, Nuclear Research Center of the Negev, P.O.B. 9001 Beer Sheva (Israel); Ocherashvilli, A.; Ettegui, H. [Physics Department, Nuclear Research Center of the Negev, P.O.B. 9001 Beer Sheva (Israel); Pedersen, B. [Nuclear Security Unit, Institute for Transuranium Elements, Via E. Fermi, 2749 JRC, Ispra (Italy)

    2015-09-11

    In the study, we demonstrate the implementation of the “bootstrap” method for a reliable estimation of the statistical error in Neutron Multiplicity Counting (NMC) on plutonium samples. The “bootstrap” method estimates the variance of a measurement through a re-sampling process, in which a large number of pseudo-samples are generated, from which the so-called bootstrap distribution is generated. The outline of the present study is to give a full description of the bootstrapping procedure, and to validate, through experimental results, the reliability of the estimated variance. Results indicate both a very good agreement between the measured variance and the variance obtained through the bootstrap method, and a robustness of the method with respect to the duration of the measurement and the bootstrap parameters.

  20. Coincident optima for two-facility Weber problems

    DEFF Research Database (Denmark)

    Juel, Henrik

    1983-01-01

    The location problem with two new facilities in continuous space is considered, with distance measured by arbitrary norms. Necessary and sufficient conditions for a proposed solution to be optimal are given for several cases. These cases include situations where the cost function is nondifferenti......The location problem with two new facilities in continuous space is considered, with distance measured by arbitrary norms. Necessary and sufficient conditions for a proposed solution to be optimal are given for several cases. These cases include situations where the cost function is...

  1. Monte Carlo simulation of GM probe and NaI detector efficiency for surface activity measurements

    International Nuclear Information System (INIS)

    This paper deals with the direct measurement of total (fixed plus removable) surface activity in the presence of interfering radiation fields. Two methods based on Monte Carlo simulations are used: one for a Geiger–Muller (GM) ionisation probe and the other for sodium iodide (NaI) detector with lead collimators; equations for the most general case and the geometry models for Monte Carlo simulation of both (GM and NaI) detectors are employed. Finally, an example of application is discussed. - Highlights: • Two methods for direct measurements of beta/gamma surface activity are proposed. • Monte Carlo simulated efficiency of detectors was validated and tested. • The calculated and measured efficiencies of detection systems were very similar. • The comparison between two different methods shows good agreement. • Methods can be used for rapid and accurate direct measurements of surface activity

  2. The standardization of 57Co by liquid scintillation coincidence counting

    International Nuclear Information System (INIS)

    The theoretical and experimental aspects relating to the standardization of the nuclide 57Co are described. An ampoule containing a standardized 57Co solution was sent to the Bureau International des Poids et Mesures for comparative measurement. The registration table and a plot based thereon are preseted

  3. Contested spatial coincidence of conservation and mining efforts in Madagascar

    OpenAIRE

    Anjara Andriamanalina; Scott G. Cardiff

    2007-01-01

    Mining appears to represent an important threat to conservation efforts in Madagascar. Expanding mining activities on the island have the potential to provide revenue for development and conservation efforts, but also pose a potential threat to conservation efforts on the island due to the spatial distribution and extent of mining concessions and the environmental impacts that mines often cause. By measuring the extent of overlap of permitted mining concessions with protected areas, potential...

  4. Study of inclusion counting by the coincidence method

    International Nuclear Information System (INIS)

    The assessment of microscopic inclusions in steels by the counting methods on polished sample is studied. This paper makes use of the method of size measurement and point counting to high grade carbon and alloy and stainless steels. Those fine steels are scarcely concerned by the classical Jernkontorets method, which often leads to uncertain results. This work was carried out to test the canning of the fuel elements of the reactor EL 4. (author)

  5. Intrinsic coincident linear polarimetry using stacked organic photovoltaics.

    Science.gov (United States)

    Roy, S Gupta; Awartani, O M; Sen, P; O'Connor, B T; Kudenov, M W

    2016-06-27

    Polarimetry has widespread applications within atmospheric sensing, telecommunications, biomedical imaging, and target detection. Several existing methods of imaging polarimetry trade off the sensor's spatial resolution for polarimetric resolution, and often have some form of spatial registration error. To mitigate these issues, we have developed a system using oriented polymer-based organic photovoltaics (OPVs) that can preferentially absorb linearly polarized light. Additionally, the OPV cells can be made semitransparent, enabling multiple detectors to be cascaded along the same optical axis. Since each device performs a partial polarization measurement of the same incident beam, high temporal resolution is maintained with the potential for inherent spatial registration. In this paper, a Mueller matrix model of the stacked OPV design is provided. Based on this model, a calibration technique is developed and presented. This calibration technique and model are validated with experimental data, taken with a cascaded three cell OPV Stokes polarimeter, capable of measuring incident linear polarization states. Our results indicate polarization measurement error of 1.2% RMS and an average absolute radiometric accuracy of 2.2% for the demonstrated polarimeter. PMID:27410627

  6. Relationship of the sensitivity of dual-head coincidence imaging and 18F activity

    International Nuclear Information System (INIS)

    Objective: To evaluate the effects of 18F activity on random coincidence rate and sensitivity in dual-head coincidence imaging. Methods: The chest model was filled with water solution added various 18F activity. The emission tomography imaging was acquired by DST-Xli dual-head SPECT and the imagings were processed with the same reconstruction procedure. Results: The more different between the true and random coincidence, the better imaging quality would be. the difference value varied from small to larger and then gradually went down in 6 consecutive imagings. At 86th min, the difference value reached maximum 8.9 MBq, the single counts rate was 3.65 x 105, the corresponding 18F activity was 17.8 MBq, and the random coincidence rate was 25%. At that time the most positive nodules were displayed with the best imaging quality. The counts rate, random coincidence rate and others had significant linear correlation. The correlation coefficient (R) between the activity X (MBq) and random coincidence rate Y(%) were 0.9974 (R2) and 0.9967 (R2) with P18F activity required; both higher or lower activity could not benefit for the imaging quality. When the random coincidence rate was 25%, the corresponding 18F activity could produced the best imaging sensitivity. (authors)

  7. Spectroscopy of {sup 189,187}Pb from gamma-FMA coincidences

    Energy Technology Data Exchange (ETDEWEB)

    Janssens, R.V.F.; Davids, C.N.; Blumenthal, D. [and others

    1995-08-01

    The very neutron-deficient Pb isotopes are of much current interest because they exhibit shape coexistence between a spherical groundstate and a deformed prolate excited configuration located very low in excitation energy. Last year the nucleus {sup 186}Pb was studied at the FMA in an FMA-{gamma}-{gamma} coincidence experiment. The purpose of the present measurement was to delineate, for the first time, the groundstate and near groundstate excitations in the odd Pb isotopes {sup 189,187}Pb in order to identify the orbitals which have an important role in driving the nuclear shape. The experiment was performed only very recently at the FMA with 10 Compton-suppressed Ge detectors from the Argonne Notre Dame BGO Gamma-Ray facility. {sup 187}Pb was studied with the {sup 155}Gd({sup 36}Ar,4n) reaction at 179 MeV, while {sup 189}Pb was reached with the {sup 158}Gd({sup 36}Ar,5n) reaction at the same beam energy. The analysis just began. It can already be stated that transitions in both Pb isotopes were identified and that it should be possible to establish level schemes. The presence of possible isomeric states in {sup 189}Pb will be checked in a follow-up experiment planned in Canberra. A similar measurement on {sup 187}Pb appears very difficult because of the very small cross section involved.

  8. The Efficiency Of Coincidence Spectroscopy With Two Semi-Conductor Detectors At 0.5 - 8 MeV Energy Region

    International Nuclear Information System (INIS)

    The efficiency function of detector is provided by manufacturer only when user request to manufacture. Even in this case, these functions still need to be tested by experiments. The efficiency of spectrometer is a function which depend energy, measurement geometry and sample geometry. Further more in the coincidence spectrometer, the efficiency depend both of detector efficiencies and distribute cascade energy. So, determined efficiency function of coincidence spectrometer is very complex. This report presents the results of determining the relative efficiency of coincidence spectrometer at Dalat Nuclear Research Institute. The experimental was determined by 35Cl(nth,γ)36Cl reaction and interpolated for 0.5 - 8 MeV energy region. (author)

  9. 18F standardization by means of a 4πβ-γ software coincidence system

    International Nuclear Information System (INIS)

    The standardization of 18F, a positron emitter of short half-life, used in PET (Positron Emission Tomography) by means of a software 4πβ-γ coincidence system is described. The 4πβ-γ coincidence system consists of a gas-flow proportional counter (PC) in 4π geometry operated at 0.1 MPA coupled to a 50 x 50 mm NaI(Tl) crystal. The data collection was made by means of a Software Coincidence System (SCS) developed at the LMN (Nuclear Metrology Laboratory) of the IPEN-CNEN/SP. The extrapolation technique was applied to determine the activity of the solution. (author)

  10. Radioxenon detector calibration spike production and delivery systems

    Energy Technology Data Exchange (ETDEWEB)

    Foxe, Michael P.; Cameron, Ian M.; Cooper, Matthew W.; Haas, Derek A.; Hayes, James C.; Kriss, Aaron A.; Lidey, Lance S.; Mendez, Jennifer M.; Prinke, Amanda M.; Riedmann, Robin A.

    2016-03-01

    Abstract Beta-Gamma coincidence radioxenon detectors must be calibrated for each of the four-radioxenon isotopes (135Xe, 133Xe, 133mXe, and 131mXe). Without a proper calibration, there is potential for the misidentification of the amount of each isotope detected. It is important to accurately determine the amount of each radioxenon isotope, as the ratios can be used to distinguish between an anthropogenic source and a nuclear explosion. We have developed a xenon calibration system (XeCalS) that produces calibration spikes of known activity and pressure for field calibration of detectors. The activity concentrations of these calibration spikes are measured using a beta-gamma coincidence detector and a high purity germanium (HPGe) detector. We will present the results from the development and commissioning of XeCalS, along with the future plans for a portable spike implementation system.

  11. Construction and simulation of the KAOS spectrometer for coincidence measurements in the associated kaon production

    International Nuclear Information System (INIS)

    With the extension of the Mainz microtron MAMI at the Institut fuer Kernphysik with a third stage it is now possible to produce particles with open strangeness. For their detection the spectrometer facility of the A1 collaboration has been expanded with the KAOS-spectrometer which has been inherited from GSI in Darmstadt. We are studying the p(e,e'K+)Λ/Sigma0 reaction where the outgoing electron and kaon have to be detected. If we use a different target than hydrogen there is the possibility of a hypernuceus being formed. Spectroscopy of these gives the opportunity to study the hyperon potential within the atomic nucleus and the hyperon-nucleon interaction. Due to the good quality of the electron beam mass resolutions of a few hundred keV/c2 can be achieved. The detectors and the optical properties of the spectrometer have been simulated with GEANT4. Hit pattern in the detectors have been generated to aid the programming of the FPGA-based trigger. A first mapping of the detector coordinates to the target coordinates has been generated. For the experiments with hypernuclei KAOS has to be placed at 0 forward angle and the primary electron beam has to go via a magnetic chicane through the dipole. The simulation shows only a slight increase of the radiation for this case, especially around the beam-dump. Thus it is possible to operate KAOS as double sided spectrometer at MAMI. Within the scope of this thesis the readout and control electronics for all detectors had to be integrated into the existing A1 data acquisition and into the control system. During two beamtimes in autumn 2008 kaons where detected in the angular range between 20 and 40 and the momentum range between 400 MeV/c and 600 MeV/c. A time resolution of 1ns FWHM could be achieved which allows particle identification. The angular and momentum resolution was sufficient to identify Λ and Σ0 hyperons in the missing mass spectrum. (orig.)

  12. Single track coincidence measurements of fluorescent and plastic nuclear track detectors in therapeutic carbon beams

    Czech Academy of Sciences Publication Activity Database

    Osinga, J. M.; Ambrožová, Iva; Pachnerová Brabcová, Kateřina; Akselrod, M. S.; Jäkel, O.; Davídková, Marie; Greilich, S.

    2014-01-01

    Roč. 9, APR (2014), P04013. ISSN 1748-0221 R&D Projects: GA MŠk LG14004 Institutional support: RVO:61389005 Keywords : instrumentation for heavy-ion therapy * particle tracking detectors * solid-state detectors * heavy-ion detectors * hybrid detectors Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.399, year: 2014

  13. Angle-resolved photon-coincidence measurements in a multiple-scattering medium

    DEFF Research Database (Denmark)

    Smolka, Stephan; Muskens, Otto L.; Lagendijk, Ad; Lodahl, Peter

    2011-01-01

    agreement with the continuous mode quantum theory of multiple scattering of light. The presented experimental technique is essential in order to study quantum phenomena in multiple-scattering random media, such as quantum interference and quantum entanglement of photons....

  14. Signature of pre-equilibrium-emission: yield-ratio measurement in particle-γ coincidence

    International Nuclear Information System (INIS)

    In the present work, forward peaked angular distribution characteristics of pre-equilibrium-particles have been used to probe the pre-equilibrium process. In such a case, the probability of light nuclear particles emitted in forward cone may be relatively large as compared to that emitted in backward cone

  15. STUDY OF THE CONTINUUM IN HEAVY-ION INELASTIC SPECTRA BY LIGHT PARTICLE COINCIDENCE MEASUREMENTS

    NARCIS (Netherlands)

    SCARPACI, JA; BLUMENFELD, Y; CHOMAZ, P; FRASCARIA, N; GARRON, JP; ROYNETTE, JC; SUOMIJARVI, T; ALAMANOS, N; GILLIBERT, A; VANDERWOUDE, A

    1991-01-01

    The continuum in heavy ion inelastic spectra contains, in addition to the excitation of target nucleus states, contributions from pick-up break-up and knock out reactions. In the case of the Ca-40 + Ca-40 collision at 50 MeV/N these contributions are separated and their relative importance assessed

  16. A coincidence method for the simultaneous measurement of the photoionization of several masses

    International Nuclear Information System (INIS)

    This study was made in the working team Ding (Hahn-Meitner Institute Berlin) in the framework of photoionization experiments on Van-der-Waals clusters. The experiments were performed at the Berlin electron storage ring (BESSY). In a molecular-beam source clusters are produced and ionized by monochromatic light. The mass of the ions arising hereby is determined with a time-of-flight mass spectrometer. Within this thesis a method and an electronic device was developed, by which it is made possible to gather simultaneously the wave-length dependence of several masses. (orig.) With 27 refs

  17. Detection of lead via lead-207m using cyclic activation and a modified sum-coincidence system

    International Nuclear Information System (INIS)

    Samples containing lead were irradiated in a reactor, counted on a detector, and the process repeated for an optimum number of cycles in order to determine the concentration of the element present. The 0.8s isomer of /sup 207m/Pb was detected using two 7.5 cm x 7.5 cm NaI (Tl) crystals operating in a modified sum-coincidence system. The efficiency and resolution of the system were measured using a standard source. The sensitivity and detection limits for lead in various matrices of environmental interest were obtained. The sensitivity in an interference free matrix was found to be 5 μg

  18. Results of low level waste analysis of plutonium with a passive neutron coincidence counter

    International Nuclear Information System (INIS)

    Measurements have been made at the Los Alamos National Laboratory (LANL) in the US and the Power Reactor Nuclear Fuel Development Corporation/Plutonium Fuel Production Facility (PNC/PFPF) in Japan with the Passive Neutron Waste Assay System (JCC-21) employing the Add-a-Source technique to quantify the plutonium content in 208 liter drums. The JCC-21 was jointly developed by Canberra Nuclear and LANL. High counting efficiency is obtained by using multiple 3He detectors in a 4π geometry, and a carefully-designed high-density polyethylene moderator provides relative insensitivity to the effects of scattering reactions in the matrix. Additional high-density polyethylene also provides shielding to reduce the low-energy ambient neutron background and improves the detection limit. The Add-a-Source technique developed by LANL provides a significant improvement in accounting for matrix effects by actually measuring the matrix absorption of neutrons from a small 252Cf source and correcting the detected flux for the matrix absorption. Matrix effects and corrections using the Add-a-Source technique were evaluated during installation. A detectability limit of 0.73 mg 240Pueff was measured for coincidence count at PNC/PFPF, making the JCC-21 one of the most sensitive and accurate NDA systems for analysis of plutonium-bearing waste. A detectability limit of 0.4 mg 240Pueff was measured for total counts at LANL, demonstrating a lower detection limit for waste where the (α,n) component is known. Enhancements to the counter design are being investigated to improve the sensitivity by reducing the background and increasing the counting efficiency. New counting techniques are also being investigated to improve the accuracy of the assay. The results of these enhancements and new techniques are presented

  19. Axioms for a local Reidemeister trace in fixed point and coincidence theory on differentiable manifolds

    OpenAIRE

    Staecker, P. Christopher

    2007-01-01

    We give axioms which characterize the local Reidemeister trace for orientable differentiable manifolds. The local Reidemeister trace in fixed point theory is already known, and we provide both uniqueness and existence results for the local Reidemeister trace in coincidence theory.

  20. Contested spatial coincidence of conservation and mining efforts in Madagascar

    Directory of Open Access Journals (Sweden)

    Anjara Andriamanalina

    2007-12-01

    Full Text Available Mining appears to represent an important threat to conservation efforts in Madagascar. Expanding mining activities on the island have the potential to provide revenue for development and conservation efforts, but also pose a potential threat to conservation efforts on the island due to the spatial distribution and extent of mining concessions and the environmental impacts that mines often cause. By measuring the extent of overlap of permitted mining concessions with protected areas, potential protected areas, and mining - exclusion zones on the island, we assessed potential effects of mining on terrestrial conservation and evaluated the success of the governing institutions in limiting that impact. Permitted mining areas in 2006 overlapped with protected areas, potential protected areas, and mining - exclusion zones on the island. Mining concession areas overlapped with 33 % of surface area planned for protection in 2005, 21 % of surface area planned for protection in 2006, and 12 % of the surface area from which mining was to be legally excluded. Total permitted area and area of overlap with conservation areas increased between 2005 and 2006 despite efforts in 2004 to limit such overlap. Changes in the mining permitting and regulation could improve prospects for limiting the impact of mining on biodiversity conservation on the island.

  1. Search for transient gravitational waves in coincidence with short duration radio transients during 2007-2013

    OpenAIRE

    The LIGO Scientific Collaboration,; the Virgo Collaboration; Abbott, B.; Abbott, R.; Abbott, T.; Abernathy, M.; Acernese, F.; Ackley, K.; ADAMS, C.; Adams, T.; Addesso, P.; Adhikari, R.; Adya, V.; Affeldt, C.; Agathos, M.

    2016-01-01

    We present an archival search for transient gravitational wave bursts in coincidence with 27 single pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO, Virgo and GEO interferometer network. We also discuss a check for gravitational wave signals in coincidence with Parkes Fast Radio Bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short duration radio signals and transient gravitational...

  2. Experimental verification of mathematical efficiency modeling and true coincidence summing correction of the SAGe Well detector

    International Nuclear Information System (INIS)

    The characterization and ray-tracing algorithm in ISOCS/LabSOCS has been extended to calculate full energy peak and total efficiencies for the Small Anode Germanium Well detector. The extension allows for true coincidence summing correction using the standard algorithm in the Genie 2000 software. The accuracy of the full energy peak efficiency calculation and the coincidence summing correction has been experimentally validated to be the same as for non-well detectors. (author)

  3. On Approximate Coincidence Point Properties and Their Applications to Fixed Point Theory

    OpenAIRE

    Wei-Shih Du

    2012-01-01

    We first establish some existence results concerning approximate coincidence point properties and approximate fixed point properties for various types of nonlinear contractive maps in the setting of cone metric spaces and general metric spaces. From these results, we present some new coincidence point and fixed point theorems which generalize Berinde-Berinde's fixed point theorem, Mizoguchi-Takahashi's fixed point theorem, and some well-known results in the literature.

  4. Shift Register Clock Rate Effects on Coincidence Collection 50MHz versus 4MHz Comparison Tests

    Energy Technology Data Exchange (ETDEWEB)

    Newell, Matthew R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bourret, Steven C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Swinhoe, Martyn Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-03

    The following report identifies and quantifies the timing differences between the older slower Shift Register Coincidence/Multiplicity modules and today’s modern higher speed devices. Modern high speed Shift Register Coincidence/Multiplicity instruments employ high speed internal clocks that run at frequencies more than ten times the older units, typically 50MHz. These higher speed clocks allow for a finer time resolution when recording input pulses.

  5. Light particle coincidences with gross structure in energy spectra from the 40Ca+40Ca collision

    International Nuclear Information System (INIS)

    Angular correlations between light charged particles and heavy ion fragments from the 40Ca + 40Ca collision have been investigated. The high excitation energy structure previously observed in inclusive experiments is strongly populated in coincidence with protons for calcium and potassium fragments, with alphas for argon fragments. Particles emitted in coincidence with the structure are strongly focused and have a velocity close to the velocity of the beam, whereas the yield of evaporation decay is very small

  6. Sensitive neutron detection method using delayed coincidence transitions in existing iodine-containing detectors

    CERN Document Server

    Yakushev, E; Drokhlyansky, A; Filosofov, D; Kalaninova, Z; Timkin, V; Ponomarev, D

    2016-01-01

    This letter explains a new, highly sensitive method for the detection of neutrons, which uses the T$_{1/2}=845$ ns delay in the decay of $^{128}$I at the 137.8 keV energy level, resulting from the capture of thermal neutrons by iodine nuclei in NaI and CsI scintillation detectors. The use of delayed coincidence techniques with a several $\\mu {\\rm s}$ time frame for delayed events allows for the highly effective discrimination of neutron events from any existing background signals. A comparison of ambient neutron measurements between those identified through the suggested method from a cylindrical, \\o$\\, 63 \\, {\\rm mm}\\times 63\\, {\\rm mm}$ NaI(Tl) scintillator and those from a low-background proportional $^3$He counter experimentally demonstrates the efficacy of this neutron detection method. For an isotropic, $4\\pi$, thermal neutron flux of 1 ${\\rm n}\\, {\\rm cm}^{-2}\\, {\\rm s}^{-1}$, the absolute sensitivity of the NaI detector was found to be $6.5 \\pm 1\\, {\\rm counts}\\, {\\rm s}^{-1}$ with a background of $0....

  7. Development of a coincidence system for radio-nuclide standardization using surface barrier detectors

    International Nuclear Information System (INIS)

    A system for the standardization of alpha-gamma or electron-X radionuclide emitters has been developed in the present work. The system consists of one or two surface barrier detectors for alpha or electron detection which are coupled to thin-window NaI (T1) crystals suitable for low energy X or gamma ray detection. The performance of the system has been verified by means of the standardization of 241Am, 137Cs and 109Cd solutions. The activity has been obtained using the extrapolation method applied to the 4Πα-γ and 2Πec-X coincidence technique. The surface barrier detection efficiency was varied by placing absorbers over the radioactive sources or by changing the source to detector distance. The results were compared to those obtained using conventional absolute systems based on gas-flow and pressurized 4Π proportional counters, or using radioactive solutions standardized in international comparisons spondored by the Bureau International des Poids et Mesures. The expect and measured activities agree within the experimental uncertainties which were: 0.2 % for 241Am, 0.7% for 137Cs and 0.6% for 109Cd. The ratio between the probabilities of (electron capture + internal conversion) and internal conversion for the K-shell of 109Cd has been determined. The result is: 2.8883 ± 0.016. (author)

  8. Fast γ-ray coincidence timing using a BGO detector array in a nuclear reaction experiment

    International Nuclear Information System (INIS)

    The (7Li, 7Be) nuclear charge-exchange reaction has been investigated at E(7Li)=350 MeV. Coincidences were measured between the charged 7Be reaction products in the focal plane of a magnetic spectrometer and 430-keV Doppler-shifted γ-rays from the decay in flight of excited 7Be ejectiles. The latter were detected in a compact BGO detector array. Fast timing was used to optimize the separation between prompt and randoms events. The BGO output signals display the statistical distribution of the arrival times of individual photoelectrons from the photocathode in the photomultiplier tubes. A timing resolution of 6.5 ns relative to the accelerator RF was obtained. A simple model was successfully developed to simulate the BGO output signals with a statistical distribution of a predetermined number of photoelectrons modulated by the light output response of the scintillator and the single-photoelectron gain distribution and transit time through the photomultiplier tube. It is concluded that the timing resolution is primarily limited by the small number of photoelectrons. ((orig.))

  9. The RD27 muon trigger co-incidence array demonstrator ASIC

    International Nuclear Information System (INIS)

    One aim of the RD27 project is to perform design and R and D work leading to a first level muon trigger for an experiment at the Large Hadron Collider (LHC) at CERN. This paper describes the design, implementation and testing of an ASIC for a trigger demonstrator system. The trigger system is implemented using a set of seven chambers. The low momentum trigger requires hits in three out of the four inner chambers. The high momentum trigger requires a low momentum trigger and hits in two of three outer chambers. This scheme allows for chamber inefficiencies for real muons and reduces the trigger rate from neutron and photon-induced background in the detectors. The core of the ASIC is an eight by twenty-four input double co-incidence array allowing two momentum cuts to be applied. The ASIC has multiple inputs per axis and includes the multiplicity logic. The design of the ASIC is flexible enough to demonstrate fully combinatorial operation, fully pipelined operation, or any combination of the two. The ASIC has been fabricated using a 34K gate, 0.5microm CMOS gate array from Fujitsu. Testing confirms it can be pipelined at above 100MHz or fully combinatorial with a measured maximum propagation delay of 7.4ns, varying by up to 2ns depending on input pattern

  10. Investigation of strong laser field-induced fragmentation dynamics of hydrocarbon molecules using coincidence momentum imaging

    International Nuclear Information System (INIS)

    The thesis at hand deals with the strong laser field-induced fragmentation of hydrocarbon molecules. During the laser field's action the molecules may become multiply ionized. After the removal of electrons not only the charge density will be redistributed very quickly, also the molecule itself may undergo partly severe structural deformation and may fragment into several parts. Especially the dynamics of protons is of interest since the fragmentation of a molecule can be largely determined by its protons. This proton dynamics bridges the gap between the most fundamental level in molecular dynamics, which is the sub-femtosecond dynamics of the valence electrons, and the rather slow dynamics of the much heavier atoms of a molecule. The experiments were carried out by using the coincidence momentum imaging technique COLTRIMS which allows one to measure the momentum vectors of cations and electrons resulting from the interaction of the laser field with the molecule. From these momentum vectors the induced reaction, for example the fragmentation of the molecule, can be reconstructed. For the experiments laser pulses with intensities in the range of 1013 - 1016 W/cm2 and pulse durations of around 25 fs, delivered by a Ti:Sapphire based laser system, were used. 2-body and 3-boody fragmentation of 1,3-butadiene was investigated. Apart from different fragmentation channels along different fragmentation pathways, hydrogen/proton migration prior to chemical bond breaking was observed. Furthermore, the emission of highly energetic protons emitted from small hydrocarbon molecules was explored. (author)

  11. Modeling time-coincident ultrafast electron transfer and solvation processes at molecule-semiconductor interfaces

    International Nuclear Information System (INIS)

    Kinetic models based on Fermi's Golden Rule are commonly employed to understand photoinduced electron transfer dynamics at molecule-semiconductor interfaces. Implicit in such second-order perturbative descriptions is the assumption that nuclear relaxation of the photoexcited electron donor is fast compared to electron injection into the semiconductor. This approximation breaks down in systems where electron transfer transitions occur on 100-fs time scale. Here, we present a fourth-order perturbative model that captures the interplay between time-coincident electron transfer and nuclear relaxation processes initiated by light absorption. The model consists of a fairly small number of parameters, which can be derived from standard spectroscopic measurements (e.g., linear absorbance, fluorescence) and/or first-principles electronic structure calculations. Insights provided by the model are illustrated for a two-level donor molecule coupled to both (i) a single acceptor level and (ii) a density of states (DOS) calculated for TiO2 using a first-principles electronic structure theory. These numerical calculations show that second-order kinetic theories fail to capture basic physical effects when the DOS exhibits narrow maxima near the energy of the molecular excited state. Overall, we conclude that the present fourth-order rate formula constitutes a rigorous and intuitive framework for understanding photoinduced electron transfer dynamics that occur on the 100-fs time scale

  12. A Web-based Google-Earth Coincident Imaging Tool for Satellite Calibration and Validation

    Science.gov (United States)

    Killough, B. D.; Chander, G.; Gowda, S.

    2009-12-01

    The Group on Earth Observations (GEO) is coordinating international efforts to build a Global Earth Observation System of Systems (GEOSS) to meet the needs of its nine “Societal Benefit Areas”, of which the most demanding, in terms of accuracy, is climate. To accomplish this vision, satellite on-orbit and ground-based data calibration and validation (Cal/Val) of Earth observation measurements are critical to our scientific understanding of the Earth system. Existing tools supporting space mission Cal/Val are often developed for specific campaigns or events with little desire for broad application. This paper describes a web-based Google-Earth based tool for the calculation of coincident satellite observations with the intention to support a diverse international group of satellite missions to improve data continuity, interoperability and data fusion. The Committee on Earth Observing Satellites (CEOS), which includes 28 space agencies and 20 other national and international organizations, are currently operating and planning over 240 Earth observation satellites in the next 15 years. The technology described here will better enable the use of multiple sensors to promote increased coordination toward a GEOSS. The CEOS Systems Engineering Office (SEO) and the Working Group on Calibration and Validation (WGCV) support the development of the CEOS Visualization Environment (COVE) tool to enhance international coordination of data exchange, mission planning and Cal/Val events. The objective is to develop a simple and intuitive application tool that leverages the capabilities of Google-Earth web to display satellite sensor coverage areas and for the identification of coincident scene locations along with dynamic menus for flexibility and content display. Key features and capabilities include user-defined evaluation periods (start and end dates) and regions of interest (rectangular areas) and multi-user collaboration. Users can select two or more CEOS missions from a

  13. Improvement of software coincidence counting system for standardisation of EC-β+ radionuclides

    International Nuclear Information System (INIS)

    Since 2000 the software coincidence counting (SCC) system has been used for activity standardisation of about 15 radionuclides. Their activities were determined by the efficiency extrapolation method applied to 4π (PC)-γ coincidence. Some standardisations, mainly standardisations of EC-β+ radionuclides, required optimal setting of coincidence parameters, for which new procedures based on “the coincidence to total PC count ratios”, “a multiple gamma window combined from subwindows fractions” and “a source test for PC detection efficiency ” were introduced. The paper summarises the development of SCC system related to findings from detailed analyses of recorded data. These findings are not practically achievable by a conventional approach. - Highlights: ► Improvement of extrapolation method applied to 4π (PC)-γ coincidence. ► New procedures for optimal setting of coincidence parameters. ► Applicable in metrology of radionuclides with complicated decay scheme. ► Mainly for activity standardisation of EC-β+ radionuclides.

  14. An investigation of a coincidence detection system for an all-digital small animal PET scanner

    International Nuclear Information System (INIS)

    Objective: To investigate and design a coincidence detection system for an all-digital small animal PET scanner and evaluate its preliminary performance properties. Methods: This coincidence module adopted a coincidence identification mode based on singles data in list-mode.Using digital signal processing technology, energy calibration, crystal identification, timing alignment and coincidence events extraction were performed on singles data in list-mode. The obtained data could be used for image reconstruction. Results: The 13 × 13 crystal array was well recognized by the position histogram of one lutetium yttrium orthosilicate (LYSO) crystal block. In the coincidence timing histogram of the micro-Derenzo phantom, 1.36 ns full width at half maximum was obtained. The rods with a diameter of 1.2 mm were clearly displayed in the reconstructed image of the micro-Derenzo phantom. Conclusion: The coincidence module can provide satisfactory performance to meet the design needs of an all-digital small animal PET scanner. (authors)

  15. Limb–nadir matching using non-coincident NO2 observations: Proof of concept and the OMI-minus-OSIRIS prototype product

    OpenAIRE

    Adams, Cristen; Normand, Elise N; Mclinden, Chris A.; Bourassa, Adam E.; Lloyd, Nicholas D.; Degenstein, Douglas A.; Krotkov, Nickolay A.; Belmonte Rivas, Maria; Boersma, K. Folkert; Eskes, Henk

    2016-01-01

    A variant of the limb-nadir matching technique for deriving tropospheric NO2 columns is presented in which the stratospheric component of the NO2 slant column density (SCD) measured by the Ozone Monitoring Instrument (OMI) is removed using non-coincident profiles from the Optical Spectrograph and InfraRed Imaging System (OSIRIS). In order to correct their mismatch in local time and the diurnal variation of stratospheric NO2, OSIRIS profiles, which were measured just after sunrise, were mapped...

  16. Summing coincidence errors using 152Eu lungs to calibrate a lung-counting system: are they significant?

    Science.gov (United States)

    Kramer, Gary H; Lynch, Timothy; Lopez, Maria Antonia; Hauck, Barry M

    2004-02-01

    The use of a lung phantom containing 152Eu/241 Am activity can provide a sufficient number of energy lines to generate an efficiency calibration for the in vivo measurements of radioactive materials in the lungs. However, due to the number of energy lines associated with 152Eu, coincidence summing occurs and can present a problem when using such a phantom for calibrating lung-counting systems. A Summing Peak Effect Study was conducted at three laboratories to determine the effect of using an efficiency calibration based on a 152Eu/241 Am lung phantom. The measurement data at all three laboratories showed the presence of sum peaks. While one of the laboratories found only small biases (< 5%) when using the 152Eu/241 Am calibration, the other facilities noted up to 30% positive bias in the 140 keV to 190 keV energy range that prevents the use of the 152Eu/241 Am lung phantom for routine calibrations. Although manufactured by different vendors, the three facilities use similar types of germanium detectors (38 cm2 by 25 mm thick or 38 cm2 by 30 mm thick) for counting. These results underscore the need to evaluate the coincidence summing effect, which appear system dependent, when using a nuclide such as 152Eu for the calibration of low-energy lung counting systems and highlight the problem of using a general calibration curve in place of specific nuclide calibration factors. PMID:14744066

  17. Electron irradiation effect of polyurethane using coincidence doppler-broadening spectroscopy

    International Nuclear Information System (INIS)

    Full text: To understand the electron irradiation effects on polymer, polyether-urethane (ETPU) samples of 2mm in thickness and 10mm in diameter were irradiated by a 1.8MeV electron beam with beam current of 3 ma at room temperature. The irradiated doses are 5 kGy, 10 kGy, 15 kGy, 30 kGy, 100 kGy and 150 kGy. ETPU was manufactured by mixing PTMG-100, TDI-100 and MOCA. The momentum density distributions (MMDs) of electrons taking part in the annihilation processes of positron-electron pairs in ETPU have been measured by coincidence Doppler-broadening spectroscopy (CDBS). By presenting the ratio of the counts in every channel of the measured CDB spectrum to the corresponding counts from a reference spectrum (pristine ETPU), we observed that the change in MMDs is not significant for doses lower than 10 kGy. However, high momentum part of MMDs exhibit an obvious decrease for dose exceeding 15 kGy and then slowly down to steady with doses until 150 kGy. This valley occurs at around 15x103mοc and is well known as oxygen-specific, indicative of a less positron trapping by oxygen atoms in some samples of higher dose radiation. It is postulated that the radiation will break the crosslinkings, allowing the trace water and oxygen molecules to be released from the sample surface. Excess NCO groups in ETPU would crosslink with urethane and urea groups to produce allophanate and biuret groups. After receiving a certain amount of electron irradiation, crosslinked allophanate and biuret groups would produce degradation. Thus, residual water and oxygen trapped in ETPU by the crosslinking would diffuse out. However, the irradiation doses up to 150 kGy in this experiment are still not large enough to induce strong degradation of urethane and urea groups

  18. Gravity Wave Energetics Determined From Coincident Space-Based and Ground-Based Observations of Airglow Emissions

    Science.gov (United States)

    2000-01-01

    Significant progress was made toward the goals of this proposal in a number of areas during the covered period. Section 5.1 contains a copy of the originally proposed schedule. The tasks listed below have been accomplished: (1) Construction of space-based observing geometry gravity wave model. This model has been described in detail in the paper accompanying this report (Section 5.2). It can simulate the observing geometry of both ground-based, and orbital instruments allowing comparisons to be made between them. (2) Comparisons of relative emission intensity, temperatures, and Krassovsky's ratio for space- and ground-based observing geometries. These quantities are used in gravity wave literature to describe the effects of the waves on the airglow. (3) Rejection of Bates [1992], and Copeland [1994] chemistries for gravity wave modeling purposes. Excessive 02(A(sup 13)(Delta)) production led to overproduction of O2(b(sup 1)(Sigma)), the state responsible for the emission of O2. Atmospheric band. Attempts were made to correct for this behavior, but could not adequately compensate for this. (4) Rejection of MSX dataset due to lack of coincident data, and resolution necessary to characterize the waves. A careful search to identify coincident data revealed only four instances, with only one of those providing usable data. Two high latitude overpasses and were contaminated by auroral emissions. Of the remaining two mid-latitude coincidences, one overflight was obscured by cloud, leaving only one ten minute segment of usable data. Aside from the statistical difficulties involved in comparing measurements taken in this short period, the instrument lacks the necessary resolution to determine the vertical wavelength of the gravity wave. This means that the wave cannot be uniquely characterized from space with this dataset. Since no observed wave can be uniquely identified, model comparisons are not possible.

  19. Recovering the triple coincidence of non-pure positron emitters in preclinical PET

    Science.gov (United States)

    Lin, Hsin-Hon; Chuang, Keh-Shih; Chen, Szu-Yu; Jan, Meei-Ling

    2016-03-01

    Non-pure positron emitters, with their long half-lives, allow for the tracing of slow biochemical processes which cannot be adequately examined by the commonly used short-lived positron emitters. Most of these isotopes emit high-energy cascade gamma rays in addition to positron decay that can be detected and create a triple coincidence with annihilation photons. Triple coincidence is discarded in most scanners, however, the majority of the triple coincidence contains true photon pairs that can be recovered. In this study, we propose a strategy for recovering triple coincidence events to raise the sensitivity of PET imaging for non-pure positron emitters. To identify the true line of response (LOR) from a triple coincidence, a framework utilizing geometrical, energy and temporal information is proposed. The geometrical criterion is based on the assumption that the LOR with the largest radial offset among the three sub pairs of triple coincidences is least likely to be a true LOR. Then, a confidence time window is used to test the valid LOR among those within triple coincidence. Finally, a likelihood ratio discriminant rule based on the energy probability density distribution of cascade and annihilation gammas is established to identify the true LOR. An Inveon preclinical PET scanner was modeled with GATE (GEANT4 application for tomographic emission) Monte Carlo software. We evaluated the performance of the proposed method in terms of identification fraction, noise equivalent count rates (NECR), and image quality on various phantoms. With the inclusion of triple coincidence events using the proposed method, the NECR was found to increase from 11% to 26% and 19% to 29% for I-124 and Br-76, respectively, when 7.4-185 MBq of activity was used. Compared to the reconstructed images using double coincidence, this technique increased the SNR by 5.1-7.3% for I-124 and 9.3-10.3% for Br-76 within the activity range of 9.25-74 MBq, without compromising the spatial resolution or

  20. Recovering the triple coincidence of non-pure positron emitters in preclinical PET.

    Science.gov (United States)

    Lin, Hsin-Hon; Chuang, Keh-Shih; Chen, Szu-Yu; Jan, Meei-Ling

    2016-03-01

    Non-pure positron emitters, with their long half-lives, allow for the tracing of slow biochemical processes which cannot be adequately examined by the commonly used short-lived positron emitters. Most of these isotopes emit high-energy cascade gamma rays in addition to positron decay that can be detected and create a triple coincidence with annihilation photons. Triple coincidence is discarded in most scanners, however, the majority of the triple coincidence contains true photon pairs that can be recovered. In this study, we propose a strategy for recovering triple coincidence events to raise the sensitivity of PET imaging for non-pure positron emitters. To identify the true line of response (LOR) from a triple coincidence, a framework utilizing geometrical, energy and temporal information is proposed. The geometrical criterion is based on the assumption that the LOR with the largest radial offset among the three sub pairs of triple coincidences is least likely to be a true LOR. Then, a confidence time window is used to test the valid LOR among those within triple coincidence. Finally, a likelihood ratio discriminant rule based on the energy probability density distribution of cascade and annihilation gammas is established to identify the true LOR. An Inveon preclinical PET scanner was modeled with GATE (GEANT4 application for tomographic emission) Monte Carlo software. We evaluated the performance of the proposed method in terms of identification fraction, noise equivalent count rates (NECR), and image quality on various phantoms. With the inclusion of triple coincidence events using the proposed method, the NECR was found to increase from 11% to 26% and 19% to 29% for I-124 and Br-76, respectively, when 7.4-185 MBq of activity was used. Compared to the reconstructed images using double coincidence, this technique increased the SNR by 5.1-7.3% for I-124 and 9.3-10.3% for Br-76 within the activity range of 9.25-74 MBq, without compromising the spatial resolution or

  1. Determination of true coincidence correction factors using Monte-Carlo simulation techniques

    Directory of Open Access Journals (Sweden)

    Chionis Dionysios A.

    2014-01-01

    Full Text Available Aim of this work is the numerical calculation of the true coincidence correction factors by means of Monte-Carlo simulation techniques. For this purpose, the Monte Carlo computer code PENELOPE was used and the main program PENMAIN was properly modified in order to include the effect of the true coincidence phenomenon. The modified main program that takes into consideration the true coincidence phenomenon was used for the full energy peak efficiency determination of an XtRa Ge detector with relative efficiency 104% and the results obtained for the 1173 keV and 1332 keV photons of 60Co were found consistent with respective experimental ones. The true coincidence correction factors were calculated as the ratio of the full energy peak efficiencies was determined from the original main program PENMAIN and the modified main program PENMAIN. The developed technique was applied for 57Co, 88Y, and 134Cs and for two source-to-detector geometries. The results obtained were compared with true coincidence correction factors calculated from the "TrueCoinc" program and the relative bias was found to be less than 2%, 4%, and 8% for 57Co, 88Y, and 134Cs, respectively.

  2. High-level neutron-coincidence-counter (HLNCC) implementation: assay of the plutonium content of mixed-oxide fuel assemblies

    International Nuclear Information System (INIS)

    The portable High-Level Neutron Coincidence Counter is used to assay the 240Pu-effective loading of a reference mixed-oxide fuel assembly by neutron coincidence counting. We have investigated the effects on the coincidence count rate of the total fuel loading (UO2 + PuO2), the fissile loading, the fuel rod diameter, and the fuel rod pattern. The coincidence count rate per gram of 240Pu-effective per centimeter is primarily dependent on the total fuel loading of the assembly; the higher the loading, the higher the coincidence count rate. Detailed procedures for the assay of mixed-oxide fuel assemblies are developed

  3. Determination iodine in biological materials using instrumental neutron activation and anti-coincidence gamma-ray spectrometry

    International Nuclear Information System (INIS)

    Iodine is an element of interest in nutritional research. Its lower limit of safe and adequate daily dietary intake for adults varies between 150 and 200 micrograms per day. In the present study, an epithermal instrumental neutron activation analysis (EINAA) method in conjunction with anti-coincidence counting has been developed for the determination of ppb levels of iodine in individual food items. Typically 200-300 mg of a sample are irradiated for 10 or 20 minutes at the Dalhousie University SLOWPOKE-2 reactor in an epithermal flux of 1x1011 n cm-2 s-1, followed by 1 min decay and then counting for 30 min. The 443-keV gamma-ray of 128I is used for measuring iodine content by anti-coincidence counting. The anti-coincidence spectrometer consists of a 25% HPGe detector surrounded by a 10''x10'' NaI(TI) annulus and a 3''x3'' NaI(TI) plug. This system has a peak-to-Compton ratio of about 650 to 1 for the 661.6-keV photopeak of 137Cs. The Compton background resulting from the scattering of many gamma-rays of energies higher than 443 keV can be reduced by a factor of about 4 using anti-coincidence counting compared to conventional counting. The detection limit for iodine can be improved by a factor of 2 to 5 depending on the sample matrix, dead time, position of the annulus and counting geometry among several other factors.The lowest detection limit of 5 ppb can be achieved for low-salt foods. This limit is comparable to that obtained by a preconcentration NAA (PNAA) method. However, a detection limit of 20 ppb is more realistic for samples containing high amounts of Na, Cl and Al. The results obtained for many reference materials are in good agreement with the certified values and those reported by the PNAA method. Details of the methods and results will be reported

  4. Determination iodine in biological materials using instrumental neutron activation and anti-coincidence gamma-ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, W.H.; Chatt, A. [Dalhousie University, Halifax, Nova Scotia (Canada). Radiochemistry Research Laboratory

    1997-10-01

    Iodine is an element of interest in nutritional research. Its lower limit of safe and adequate daily dietary intake for adults varies between 150 and 200 micrograms per day. In the present study, an epithermal instrumental neutron activation analysis (EINAA) method in conjunction with anti-coincidence counting has been developed for the determination of ppb levels of iodine in individual food items. Typically 200-300 mg of a sample are irradiated for 10 or 20 minutes at the Dalhousie University SLOWPOKE-2 reactor in an epithermal flux of 1x10{sup 11} n cm{sup -2} s{sup -1}, followed by 1 min decay and then counting for 30 min. The 443-keV gamma-ray of {sup 128}I is used for measuring iodine content by anti-coincidence counting. The anti-coincidence spectrometer consists of a 25% HPGe detector surrounded by a 10``x10`` NaI(TI) annulus and a 3``x3`` NaI(TI) plug. This system has a peak-to-Compton ratio of about 650 to 1 for the 661.6-keV photopeak of {sup 137}Cs. The Compton background resulting from the scattering of many gamma-rays of energies higher than 443 keV can be reduced by a factor of about 4 using anti-coincidence counting compared to conventional counting. The detection limit for iodine can be improved by a factor of 2 to 5 depending on the sample matrix, dead time, position of the annulus and counting geometry among several other factors.The lowest detection limit of 5 ppb can be achieved for low-salt foods. This limit is comparable to that obtained by a preconcentration NAA (PNAA) method. However, a detection limit of 20 ppb is more realistic for samples containing high amounts of Na, Cl and Al. The results obtained for many reference materials are in good agreement with the certified values and those reported by the PNAA method. Details of the methods and results will be reported 6 refs., 2 tabs.

  5. Efficiency calibration and coincidence summing correction for large arrays of NaI(Tl) detectors in soccer-ball and castle geometries

    Energy Technology Data Exchange (ETDEWEB)

    Anil Kumar, G., E-mail: anilg@tifr.res.i [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India); Mazumdar, I.; Gothe, D.A. [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India)

    2009-11-21

    Efficiency calibration and coincidence summing correction have been performed for two large arrays of NaI(Tl) detectors in two different configurations. They are, a compact array of 32 conical detectors of pentagonal and hexagonal shapes in soccer-ball geometry and an array of 14 straight hexagonal NaI(Tl) detectors in castle geometry. Both of these arrays provide a large solid angle of detection, leading to considerable coincidence summing of gamma rays. The present work aims to understand the effect of coincidence summing of gamma rays while determining the energy dependence of efficiencies of these two arrays. We have carried out extensive GEANT4 simulations with radio-nuclides that decay with a two-step cascade, considering both arrays in their realistic geometries. The absolute efficiencies have been simulated for gamma energies from 700 to 2800 keV using four different double-photon emitters, namely, {sup 60}Co, {sup 46}Sc, {sup 94}Nb and {sup 24}Na. The efficiencies so obtained have been corrected for coincidence summing using the method proposed by Vidmar et al. . The simulations have also been carried out for the same energies assuming mono-energetic point sources, for comparison. Experimental measurements have also been carried out using calibrated point sources of {sup 137}Cs and {sup 60}Co. The simulated and the experimental results are found to be in good agreement. This demonstrates the reliability of the correction method for efficiency calibration of two large arrays in very different configurations.

  6. Monte Carlo calculation of the efficiency calibration curve and coincidence-summing corrections in low-level gamma-ray spectrometry using well-type HPGe detectors

    International Nuclear Information System (INIS)

    Well-type high-purity germanium (HPGe) detectors are well suited to the analysis of small amounts of environmental samples, as they can combine both low background and high detection efficiency. A low-background well-type detector is installed in the Modane underground Laboratory. In the well geometry, coincidence-summing effects are high and make the construction of the full energy peak efficiency curve a difficult task with an usual calibration standard, especially in the high energy range. Using the GEANT code and taking into account a detailed description of the detector and the source, efficiency curves have been modelled for several filling heights of the vial. With a special routine taking into account the decay schemes of the radionuclides, corrections for coincidence-summing effects that occur when measuring samples containing 238U, 232Th or 134Cs have been computed. The results are found to be in good agreement with the experimental data. It is shown that triple coincidences effect on counting losses accounts for 7-15% of pair coincidences effect in the case of 604 and 796 keV lines of 134Cs

  7. Remote preparation of complex spatial states of single photons and verification by two-photon coincidence experiment.

    Science.gov (United States)

    Kang, Yoonshik; Cho, Kiyoung; Noh, Jaewoo; Vitullo, Dashiell L P; Leary, Cody; Raymer, M G

    2010-01-18

    We propose and provide experimental evidence in support of a theory for the remote preparation of a complex spatial state of a single photon. An entangled two-photon source was obtained by spontaneous parametric down-conversion, and a double slit was placed in the path of the signal photon as a scattering object. The signal photon was detected after proper spatial filtering so that the idler photon was prepared in the corresponding single-photon state. By using a two-photon coincidence measurement, we obtained the Radon transform, at several longitudinal distances, of the single-photon Wigner distribution function modified by the double slit. The experimental results are consistent with the idler photon being in a pure state. An inverse Radon transformation can, in principle, be applied to the measured data to reconstruct the modified single-photon Wigner function, which is a complete representation of the amplitude and phase structure of the scattering object. PMID:20173945

  8. CoINcIDE: A framework for discovery of patient subtypes across multiple datasets.

    Science.gov (United States)

    Planey, Catherine R; Gevaert, Olivier

    2016-01-01

    Patient disease subtypes have the potential to transform personalized medicine. However, many patient subtypes derived from unsupervised clustering analyses on high-dimensional datasets are not replicable across multiple datasets, limiting their clinical utility. We present CoINcIDE, a novel methodological framework for the discovery of patient subtypes across multiple datasets that requires no between-dataset transformations. We also present a high-quality database collection, curatedBreastData, with over 2,500 breast cancer gene expression samples. We use CoINcIDE to discover novel breast and ovarian cancer subtypes with prognostic significance and novel hypothesized ovarian therapeutic targets across multiple datasets. CoINcIDE and curatedBreastData are available as R packages. PMID:26961683

  9. Determination of U-235 quantity in fresh fuel elements by neutron coincidence collar technique

    International Nuclear Information System (INIS)

    The U-235 quantity per lenght of fresh fuel assemblies of the Angra-I first recharge was determined by Neutron Coincidence Collar technique (N.C.C.). This technique is well-founded in fresh fuel assemblies activation by thermal neutrons from AmLi source to generate U-235 fission neutrons. These neutrons are detected by coincidence method in polyethylene structure where 18 He-3 detectors were placed. The coincidence counting results, in active mode (AmLi), showed 0,7% to standard deviation and equal to 1,49% to mass in 1000s of counting. The accuracies of different calibration methods were evaluated and compared. The results showed that the operator declared values are consistent. This evaluation was part of technical-exchange program between Safeguards Laboratory from C.N.E.N. and Los Alamos National Lab., United States. (author)

  10. Instrumentation and data handling. I. Positron coincidence imaging with the TOKIM system

    International Nuclear Information System (INIS)

    In addition to the conventional singles mode of operation, the TOKIM system's two Anger-type gamma cameras may be used in the (stationary, 1800 opposition) coincidence mode, making it possible to achieve tomographic imaging with three-dimensional spatial resolution and high detection sensitivity, utilizing β+ emitting radioisotopes. This method, however, suffers from certain inherent limitations. Our efforts during this past year to improve upon the TOKIM imaging capability in the β+ mode have been directed towards the reduction of the limitations by the following means: the removal of out of focal plane image contributions through a computerized iterative correction procedure, coupled with coincidence aperture limitation to achieve uniform sensitivity across a reasonable portion of the detector pair diameter, and the application of Muehllehner's graded filter approach to the TOKIM to increase the ratio of usable coincidence events versus singles count rate

  11. Standardization of 241Am by digital coincidence counting, liquid scintillation counting and defined solid angle counting

    CERN Document Server

    Balpardo, C; Rodrigues, D; Arenillas, P

    2010-01-01

    The nuclide 241Am decays by alpha emission to 237Np. Most of the decays (84.6 %) populate the excited level of 237Np with energy of 59.54 keV. Digital Coincidence Counting was applied to standardize a solution of 241Am by alpha-gamma coincidence counting with efficiency extrapolation. Electronic discrimination was implemented with a pressurized proportional counter and the results were compared with two other independent techniques: Liquid Scintillation Counting using the logical sum of double coincidences in a TDCR array and Defined Solid Angle Counting taking into account activity inhomogeneity in the active deposit. The results show consistency between the three methods within a limit of a 0.3%. An ampoule of this solution will be sent to the International Reference System (SIR) during 2009. Uncertainties were analysed and compared in detail for the three applied methods.

  12. Search for transient gravitational waves in coincidence with short duration radio transients during 2007-2013

    CERN Document Server

    others,; Abbott, B P; Abbott, R; Abbott, T D; Abernathy, M R; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Adya, V B; Affeldt, C; Agathos, M; Agatsuma, K; Aggarwal, N; Aguiar, O D; Aiello, L; Ain, A; Ajith, P; Allen, B; Allocca, A; Altin, P A; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C C; Areeda, J S; Arnaud, N; Arun, K G; Ascenzi, S; Ashton, G; Ast, M; Aston, S M; Astone, P; Aufmuth, P; Aulbert, C; Babak, S; Bacon, P; Bader, M K M; Baker, P T; Baldaccini, F; Ballardin, G; Ballmer, S W; Barayoga, J C; Barclay, S E; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barta, D; Bartlett, J; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Baune, C; Bavigadda, V; Bazzan, M; Behnke, B; Bejger, M; Bell, A S; Bell, C J; Berger, B K; Bergman, J; Bergmann, G; Berry, C P L; Bersanetti, D; Bertolini, A; Betzwieser, J; Bhagwat, S; Bhandare, R; Bilenko, I A; Billingsley, G; Birch, J; Birney, R; Biscans, S; Bisht, A; Bitossi, M; Biwer, C; Bizouard, M A; Blackburn, J K; Blair, C D; Blair, D G; Blair, R M; Bloemen, S; Bock, O; Bodiya, T P; Boer, M; Bogaert, G; Bogan, C; Bohe, A; Bojtos, P; Bond, C; Bondu, F; Bonnand, R; Boom, B A; Bork, R; Boschi, V; Bose, S; Bouffanais, Y; Bozzi, A; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Brillet, A; Brinkmann, M; Brisson, V; Brockill, P; Brooks, A F; Brown, D A; Brown, D D; Brown, N M; Buchanan, C C; Buikema, A; Bulik, T; Bulten, H J; Buonanno, A; Buskulic, D; Buy, C; Byer, R L; Cadonati, L; Cagnoli, G; Cahillane, C; Bustillo, J Calderón; Callister, T; Calloni, E; Camp, J B; Cannon, K C; Cao, J; Capano, C D; Capocasa, E; Carbognani, F; Caride, S; Diaz, J Casanueva; Casentini, C; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Cella, G; Cepeda, C B; Baiardi, L Cerboni; Cerretani, G; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chamberlin, S J; Chan, M; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, H Y; Chen, Y; Cheng, C; Chincarini, A; Chiummo, A; Cho, H S; Cho, M; Chow, J H; Christensen, N; Chu, Q; Chua, S; Chung, S; Ciani, G; Clara, F; Clark, J A; Cleva, F; Coccia, E; Cohadon, P -F; Colla, A; Collette, C G; Cominsky, L; Constancio, M; Conte, A; Conti, L; Cook, D; Corbitt, T R; Cornish, N; Corsi, A; Cortese, S; Costa, C A; Coughlin, M W; Coughlin, S B; Coulon, J -P; Countryman, S T; Couvares, P; Coward, D M; Cowart, M J; Coyne, D C; Coyne, R; Craig, K; Creighton, J D E; Cripe, J; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Canton, T Dal; Danilishin, S L; D'Antonio, S; Danzmann, K; Darman, N S; Dattilo, V; Dave, I; Daveloza, H P; Davier, M; Davies, G S; Daw, E J; Day, R; DeBra, D; Debreczeni, G; Degallaix, J; De Laurentis, M; Deléglise, S; Del Pozzo, W; Denker, T; Dent, T; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Dhurandhar, S; Díaz, M C; Di Fiore, L; Di Giovanni, M; Di Girolamo, T; Di Lieto, A; Di Pace, S; Di Palma, I; Di Virgilio, A; Dojcinoski, G; Dolique, V; Donovan, F; Dooley, K L; Doravari, S; Douglas, R; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Ducrot, M; Dwyer, S E; Edo, T B; Edwards, M C; Effler, A; Eggenstein, H -B; Ehrens, P; Eichholz, J; Eikenberry, S S; Engels, W; Essick, R C; Etzel, T; Evans, M; Evans, T M; Everett, R; Factourovich, M; Fafone, V; Fair, H; Fairhurst, S; Fan, X; Fang, Q; Farinon, S; Farr, B; Farr, W M; Favata, M; Fays, M; Fehrmann, H; Fejer, M M; Ferrante, I; Ferreira, E C; Ferrini, F; Fidecaro, F; Fiori, I; Fiorucci, D; Fisher, R P; Flaminio, R; Fletcher, M; Fournier, J -D; Frasca, S; Frasconi, F; Frei, Z; Freise, A; Frey, R; Frey, V; Fricke, T T; Fritschel, P; Frolov, V V; Fulda, P; Fyffe, M; Gabbard, H A G; Gair, J R; Gammaitoni, L; Gaonkar, S G; Garufi, F; Gaur, G; Gehrels, N; Gemme, G; Genin, E; Gennai, A; George, J; Gergely, L; Germain, V; Ghosh, Archisman; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gill, K; Glaefke, A; Goetz, E; Goetz, R; Gondan, L; González, G; Castro, J M Gonzalez; Gopakumar, A; Gordon, N A; Gorodetsky, M L; Gossan, S E; Gosselin, M; Gouaty, R; Grado, A; Graef, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greco, G; Green, A C; Groot, P; Grote, H; Grunewald, S; Guidi, G M; Guo, X; Gupta, A; Gupta, M K; Gushwa, K E; Gustafson, E K; Gustafson, R; Hacker, J J; Hall, B R; Hall, E D; Hammond, G; Haney, M; Hanke, M M; Hanks, J; Hanna, C; Hannam, M D; Hanson, J; Hardwick, T; Harms, J; Harry, G M; Harry, I W; Hart, M J; Hartman, M T; Haster, C -J; Haughian, K; Heidmann, A; Heintze, M C; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Hennig, J; Heptonstall, A W; Heurs, M; Hild, S; Hoak, D; Hodge, K A; Hofman, D; Hollitt, S E; Holt, K; Holz, D E; Hopkins, P; Hosken, D J; Hough, J; Houston, E A; Howell, E J; Hu, Y M; Huang, S; Huerta, E A; Huet, D; Hughey, B; Husa, S; Huttner, S H; Huynh-Dinh, T; Idrisy, A; Indik, N; Ingram, D R; Inta, R; Isa, H N; Isac, J -M; Isi, M; Islas, G; Isogai, T; Iyer, B R; Izumi, K; Jacqmin, T; Jang, H; Jani, K; Jaranowski, P; Jawahar, S; Jiménez-Forteza, F; Johnson, W W; Jones, D I; Jones, R; Jonker, R J G; Ju, L; K, Haris; Kalaghatgi, C V; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Karki, S; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, S; Kaur, T; Kawabe, K; Kawazoe, F; Kéfélian, F; Kehl, M S; Keitel, D; Kelley, D B; Kells, W; Kennedy, R; Key, J S; Khalaidovski, A; Khalili, F Y; Khan, I; Khan, S; Khan, Z; Khazanov, E A; Kijbunchoo, N; Kim, Chunglee; Kim, J; Kim, K; Kim, Nam-Gyu; Kim, Namjun; Kim, Y -M; King, E J; King, P J; Kinzel, D L; Kissel, J S; Kleybolte, L; Klimenko, S; Koehlenbeck, S M; Kokeyama, K; Koley, S; Kondrashov, V; Kontos, A; Korobko, M; Korth, W Z; Kowalska, I; Kozak, D B; Kringel, V; Królak, A; Krueger, C; Kuehn, G; Kumar, P; Kuo, L; Kutynia, A; Lackey, B D; Landry, M; Lange, J; Lantz, B; Lasky, P D; Lazzarini, A; Lazzaro, C; Leaci, P; Leavey, S; Lebigot, E O; Lee, C H; Lee, H K; Lee, H M; Lee, K; Lenon, A; Leonardi, M; Leong, J R; Leroy, N; Letendre, N; Levin, Y; Levine, B M; Li, T G F; Libson, A; Littenberg, T B; Lockerbie, N A; Logue, J; Lombardi, A L; Lord, J E; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J D; Lück, H; Lundgren, A P; Luo, J; Lynch, R; Ma, Y; MacDonald, T; Machenschalk, B; MacInnis, M; Macleod, D M; Magaña-Sandoval, F; Magee, R M; Mageswaran, M; Majorana, E; Maksimovic, I; Malvezzi, V; Man, N; Mandic, V; Mangano, V; Mansell, G L; Manske, M; Mantovani, M; Marchesoni, F; Marion, F; Márka, S; Márka, Z; Markosyan, A S; Maros, E; Martelli, F; Martellini, L; Martin, I W; Martin, R M; Martynov, D V; Marx, J N; Mason, K; Masserot, A; Massinger, T J; Masso-Reid, M; Mastrogiovanni, S; Matichard, F; Matone, L; Mavalvala, N; Mazumder, N; Mazzolo, G; McCarthy, R; McClelland, D E; McCormick, S; McGuire, S C; McIntyre, G; McIver, J; McManus, D J; McWilliams, S T; Meacher, D; Meadors, G D; Meidam, J; Melatos, A; Mendell, G; Mendoza-Gandara, D; Mercer, R A; Merilh, E L; Merzougui, M; Meshkov, S; Messenger, C; Messick, C; Metzdorff, R; Meyers, P M; Mezzani, F; Miao, H; Michel, C; Middleton, H; Mikhailov, E E; Milano, L; Miller, A L; Miller, J; Millhouse, M; Minenkov, Y; Ming, J; Mirshekari, S; Mishra, C; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Moggi, A; Mohan, M; Mohapatra, S R P; Montani, M; Moore, B C; Moore, C J; Moraru, D; Moreno, G; Morriss, S R; Mossavi, K; Mours, B; Mow-Lowry, C M; Mueller, C L; Mueller, G; Muir, A W; Mukherjee, Arunava; Mukherjee, D; Mukherjee, S; Mukund, K N; Mullavey, A; Munch, J; Murphy, D J; Murray, P G; Mytidis, A; Nardecchia, I; Naticchioni, L; Nayak, R K; Necula, V; Nedkova, K; Nelemans, G; Neri, M; Neunzert, A; Newton, G; Nguyen, T T; Nielsen, A B; Nissanke, S; Nitz, A; Nocera, F; Nolting, D; Normandin, M E N; Nuttall, L K; Oberling, J; Ochsner, E; O'Dell, J; Oelker, E; Ogin, G H; Oh, J J; Oh, S H; Ohme, F; Oliver, M; Oppermann, P; Oram, Richard J; O'Reilly, B; O'Shaughnessy, R; Ott, C D; Ottaway, D J; Ottens, R S; Overmier, H; Owen, B J; Pai, A; Pai, S A; Palamos, J R; Palashov, O; Palomba, C; Pal-Singh, A; Pan, H; Pankow, C; Pannarale, F; Pant, B C; Paoletti, F; Paoli, A; Papa, M A; Paris, H R; Parker, W; Pascucci, D; Pasqualetti, A; Passaquieti, R; Passuello, D; Patricelli, B; Patrick, Z; Pearlstone, B L; Pedraza, M; Pedurand, R; Pekowsky, L; Pele, A; Penn, S; Pereira, R; Perreca, A; Phelps, M; Piccinni, O J; Pichot, M; Piergiovanni, F; Pierro, V; Pillant, G; Pinard, L; Pinto, I M; Pitkin, M; Pletsch, H J; Poggiani, R; Popolizio, P; Post, A; Powell, J; Prasad, J; Predoi, V; Premachandra, S S; Prestegard, T; Price, L R; Prijatelj, M; Principe, M; Privitera, S; Prodi, G A; Prokhorov, L; Puncken, O; Punturo, M; Puppo, P; Pürrer, M; Qi, H; Qin, J; Quetschke, V; Quintero, E A; Quitzow-James, R; Raab, F J; Rabeling, D S; Radkins, H; Raffai, P; Raja, S; Rakhmanov, M; Rapagnani, P; Raymond, V; Razzano, M; Re, V; Read, J; Reed, C M; Regimbau, T; Rei, L; Reid, S; Reitze, D H; Rew, H; Ricci, F; Riles, K; Robertson, N A; Robie, R; Robinet, F; Rocchi, A; Rolland, L; Rollins, J G; Roma, V J; Romano, J D; Romano, R; Romanov, G; Romie, J H; Rosińska, D; Rowan, S; Rüdiger, A; Ruggi, P; Ryan, K; Sachdev, S; Sadecki, T; Sadeghian, L; Salconi, L; Saleem, M; Salemi, F; Samajdar, A; Sammut, L; Sanchez, E J; Sandberg, V; Sandeen, B; Sanders, J R; Sassolas, B; Sathyaprakash, B S; Saulson, P R; Sauter, O E S; Savage, R L; Sawadsky, A; Schale, P; Schilling, R; Schmidt, J; Schmidt, P; Schnabel, R; Schofield, R M S; Schönbeck, A; Schreiber, E; Schuette, D; Schutz, B F; Scott, J; Scott, S M; Sellers, D; Sentenac, D; Sequino, V; Sergeev, A; Serna, G; Setyawati, Y; Sevigny, A; Shaddock, D A; Shahriar, M S; Shaltev, M; Shao, Z; Shapiro, B; Shawhan, P; Sheperd, A; Shoemaker, D H; Shoemaker, D M; Siellez, K; Siemens, X; Sieniawska, M; Sigg, D; Silva, A D; Simakov, D; Singer, A; Singer, L P; Singh, A; Singh, R; Singhal, A; Sintes, A M; Slagmolen, B J J; Smith, J R; Smith, N D; Smith, R J E; Son, E J; Sorazu, B; Sorrentino, F; Souradeep, T; Srivastava, A K; Staley, A; Steinke, M; Steinlechner, J; Steinlechner, S; Steinmeyer, D; Stephens, B C; Stiles, D; Stone, R; Strain, K A; Straniero, N; Stratta, G; Strauss, N A; Strigin, S; Sturani, R; Stuver, A L; Summerscales, T Z; Sun, L; Sutton, P J; Swinkels, B L; Szczepańczyk, M J; Tacca, M; Talukder, D; Tanner, D B; Tápai, M; Tarabrin, S P; Taracchini, A; Taylor, R; Theeg, T; Thirugnanasambandam, M P; Thomas, E G; Thomas, M; Thomas, P; Thorne, K A; Thrane, E; Tiwari, S; Tiwari, V; Tokmakov, K V; Tomlinson, C; Tonelli, M; Torres, C V; Torrie, C I; Töyrä, D; Travasso, F; Traylor, G; Trifirò, D; Tringali, M C; Trozzo, L; Tse, M; Turconi, M; Tuyenbayev, D; Ugolini, D; Unnikrishnan, C S; Urban, A L; Usman, S A; Vahlbruch, H; Vajente, G; Valdes, G; van Bakel, N; van Beuzekom, M; Brand, J F J van den; Broeck, C Van Den; Vander-Hyde, D C; van der Schaaf, L; van Heijningen, J V; van Veggel, A A; Vardaro, M; Vass, S; Vasúth, M; Vaulin, R; Vecchio, A; Vedovato, G; Veitch, J; Veitch, P J; Venkateswara, K; Verkindt, D; Vetrano, F; Viceré, A; Vinciguerra, S; Vine, D J; Vinet, J -Y; Vitale, S; Vo, T; Vocca, H; Vorvick, C; Voss, D V; Vousden, W D; Vyatchanin, S P; Wade, A R; Wade, L E; Wade, M; Walker, M; Wallace, L; Walsh, S; Wang, G; Wang, H; Wang, M; Wang, X; Wang, Y; Ward, R L; Warner, J; Was, M; Weaver, B; Wei, L -W; Weinert, M; Weinstein, A J; Weiss, R; Welborn, T; Wen, L; Wessels, P; Westphal, T; Wette, K; Whelan, J T; Whitcomb, S E; White, D J; Whiting, B F; Williams, R D; Williamson, A R; Willis, J L; Willke, B; Wimmer, M H; Winkler, W; Wipf, C C; Wittel, H; Woan, G; Worden, J; Wright, J L; Wu, G; Yablon, J; Yam, W; Yamamoto, H; Yancey, C C; Yap, M J; Yu, H; Yvert, M; zny, A Zadro; Zangrando, L; Zanolin, M; Zendri, J -P; Zevin, M; Zhang, F; Zhang, L; Zhang, M; Zhang, Y; Zhao, C; Zhou, M; Zhou, Z; Zhu, X J; Zucker, M E; Zuraw, S E; Zweizig, J; Archibald, A M; Banaszak, S; Berndsen, A; Boyles, J; Cardoso, R F; Chawla, P; Cherry, A; Dartez, L P; Day, D; Epstein, C R; Ford, A J; Flanigan, J; Garcia, A; Hessels, J W T; Hinojosa, J; Jenet, F A; Karako-Argaman, C; Kaspi, V M; Keane, E F; Kondratiev, V I; Kramer, M; Leake, S; Lorimer, D; Lunsford, G; Lynch, R S; Martinez, J G; Mata, A; McLaughlin, M A; McPhee, C A; Penucci, T; Ransom, S; Roberts, M S E; Rohr, M D W; Stairs, I H; Stovall, K; van Leeuwen, J; Walker, A N; Wells, B L

    2016-01-01

    We present an archival search for transient gravitational wave bursts in coincidence with 27 single pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO, Virgo and GEO interferometer network. We also discuss a check for gravitational wave signals in coincidence with Parkes Fast Radio Bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short duration radio signals andtransient gravitational wave emission include starquakes on neutron stars, binary coalescence of neutron stars, and cosmic string cusps. While no evidence for gravitational wave emission in coincidence with these radio transients was found, the current analysis serves as a prototype for similar future searches using more sensitive second generation interferometers.

  13. Non-proportionality study of CaMoO4 and GAGG:Ce scintillation crystals using Compton coincidence technique.

    Science.gov (United States)

    Kaewkhao, J; Limkitjaroenporn, P; Chaiphaksa, W; Kim, H J

    2016-09-01

    In this study, the CCT technique and nuclear instrument module (NIM) setup for the measurements of coincidence electron energy spectra of calcium molybdate (CaMoO4) and cerium doped gadolinium aluminium gallium garnet (Gd3Al2Ga3O12:Ce or GAGG:Ce) scintillation crystals were carried out. The (137)Cs irradiated gamma rays with an energy (Eγ) of 662keV was used as a radioactive source. The coincidence electron energy spectra were recorded at seven scattering angles of 30°-120°. It was found that seven corresponding electron energies were in the range of 100.5-435.4keV. The results show that, for all electron energies, the electron energy peaks of CaMoO4 crystal yielded higher number of counts than those of GAGG:Ce crystal. The electron energy resolution, the light yield and non-proportionality were also determined. It was found that the energy resolutions are inverse proportional to the square root of electron energy for both crystals. Furthermore, the results show that the light yield of GAGG:Ce crystal is much higher than that of CaMoO4 crystal. It was also found that both CaMoO4 and GAGG:Ce crystals demonstrated good proportional property in the electron energy range of 260-435.4keV. PMID:27423926

  14. Study of rare neutron induced processes and coincidence analyses to identify and reduce background contributions in the COBRA experiment

    International Nuclear Information System (INIS)

    The aim of the COBRA experiment is the observation of neutrinoless double-beta decay, primarily of the isotope 116Cd. The applied semiconductor detectors of cadmium zinc telluride that are 90% to be enriched enable both the detection and the source of this decay. The half-lives of decays of this kind are expected in the range of more than 1026 years. Therefore, the reduction of contributions to the background is of decisive importance. The main subjects of this work are, on the one hand, the time synchronization of the data, which provides the basis for coincidence analysis. This analysis method has access not only to identification of contributions to the background, but also to observe decays involving positron annihilation and decays into excited states. In this study, the intrinsic detector contamination of some decay products of 238U and 232Th was measured and sensitivities to the half-lives of the decays like 120Te and 128Te in each case to the first excited state of daughter products are given. On the other hand, qualitative studies on the importance of neutrons in the COBRA experiment were conducted. These have shown that fast neutrons, thus with energies greater than 10 keV, only result in an insignificant contribution to the background for the detection of neutrinoless double-beta decay of the 116Cd. Previous studies have also shown that the thermal neutron flux can be in situ determined by coincidence analysis.

  15. THE ELECTRONIC STRUCTURE OF AG/CU(100) SURFACE ALLOYS STUDIES BY AUGER-PHOTOELECTRON COINCIDENCE SPECTROSCOPY.

    Energy Technology Data Exchange (ETDEWEB)

    ARENA,D.A.; BARTYNSKI,R.A.; HULBERT,S.L.

    2001-10-08

    We have measured the Ag and Pd M{sub 5}VV Auger spectrum in coincidence with Ag and Pd 4d{sub 5/2} photoelectrons for the Ag/Cu(100) and Pd/Cu(100) systems, respectively, as a function of admetal coverage. These systems form surface alloys (i.e. random substitutional alloys in the first atomic layer) for impurity concentrations in the 0.1 monolayer range. For these systems, the centroid of the impurity 4d levels is expected to shift away from the Fermi level by {approx}1 eV [Ruban et al., Journal of Molecular Catalysis. A 115 (1997) 421], an effect that should be easily seen in coincidence core-valence-valence Auger spectra. We find that the impurity Auger spectra of both systems shift in a manner that is consistent with d-band moving away from EF. However, the shift for Pd is considerably smaller than expected, and a shift almost absent for Ag. The disagreement between theory and experiment is most likely caused by the neglect of lattice relaxations in the calculations.

  16. True coincidence summing correction and mathematical efficiency modeling of a well detector

    International Nuclear Information System (INIS)

    True coincidence summing (TCS) occurs when two or more photons are emitted from the same decay of a radioactive nuclide and are detected within the resolving time of the gamma ray detector. TCS changes the net peak areas of the affected full energy peaks in the spectrum and the nuclide activity is rendered inaccurate if no correction is performed. TCS is independent of the count rate, but it is strongly dependent on the peak and total efficiency, as well as the characteristics of a given nuclear decay. The TCS effects are very prominent for well detectors because of the high efficiencies, and make accounting for TCS a necessity. For CANBERRA's recently released Small Anode Germanium (SAGe) well detector, an extension to CANBERRA's mathematical efficiency calibration method (In Situ Object Calibration Software or ISOCS, and Laboratory SOurceless Calibration Software or LabSOCS) has been developed that allows for calculation of peak and total efficiencies for SAGe well detectors. The extension also makes it possible to calculate TCS corrections for well detectors using the standard algorithm provided with CANBERRAS's Spectroscopy software Genie 2000. The peak and total efficiencies from ISOCS/LabSOCS have been compared to MCNP with agreements within 3% for peak efficiencies and 10% for total efficiencies for energies above 30 keV. A sample containing Ra-226 daughters has been measured within the well and analyzed with and without TCS correction and applying the correction factor shows significant improvement of the activity determination for the energy range 46–2447 keV. The implementation of ISOCS/LabSOCS for well detectors offers a powerful tool for efficiency calibration for these detectors. The automated algorithm to correct for TCS effects in well detectors makes nuclide specific calibration unnecessary and offers flexibility in carrying out gamma spectral analysis

  17. True coincidence summing correction and mathematical efficiency modeling of a well detector

    Energy Technology Data Exchange (ETDEWEB)

    Jäderström, H., E-mail: henrik.jaderstrom@canberra.com [CANBERRA Industries Inc., 800 Research Parkway, Meriden, CT 06450 (United States); Mueller, W.F. [CANBERRA Industries Inc., 800 Research Parkway, Meriden, CT 06450 (United States); Atrashkevich, V. [Stroitely St 4-4-52, Moscow (Russian Federation); Adekola, A.S. [CANBERRA Industries Inc., 800 Research Parkway, Meriden, CT 06450 (United States)

    2015-06-01

    True coincidence summing (TCS) occurs when two or more photons are emitted from the same decay of a radioactive nuclide and are detected within the resolving time of the gamma ray detector. TCS changes the net peak areas of the affected full energy peaks in the spectrum and the nuclide activity is rendered inaccurate if no correction is performed. TCS is independent of the count rate, but it is strongly dependent on the peak and total efficiency, as well as the characteristics of a given nuclear decay. The TCS effects are very prominent for well detectors because of the high efficiencies, and make accounting for TCS a necessity. For CANBERRA's recently released Small Anode Germanium (SAGe) well detector, an extension to CANBERRA's mathematical efficiency calibration method (In Situ Object Calibration Software or ISOCS, and Laboratory SOurceless Calibration Software or LabSOCS) has been developed that allows for calculation of peak and total efficiencies for SAGe well detectors. The extension also makes it possible to calculate TCS corrections for well detectors using the standard algorithm provided with CANBERRAS's Spectroscopy software Genie 2000. The peak and total efficiencies from ISOCS/LabSOCS have been compared to MCNP with agreements within 3% for peak efficiencies and 10% for total efficiencies for energies above 30 keV. A sample containing Ra-226 daughters has been measured within the well and analyzed with and without TCS correction and applying the correction factor shows significant improvement of the activity determination for the energy range 46–2447 keV. The implementation of ISOCS/LabSOCS for well detectors offers a powerful tool for efficiency calibration for these detectors. The automated algorithm to correct for TCS effects in well detectors makes nuclide specific calibration unnecessary and offers flexibility in carrying out gamma spectral analysis.

  18. Coincidence of a high-fluence blazar outburst with a PeV-energy neutrino event

    Science.gov (United States)

    Kadler, M.; Krauß, F.; Mannheim, K.; Ojha, R.; Müller, C.; Schulz, R.; Anton, G.; Baumgartner, W.; Beuchert, T.; Buson, S.; Carpenter, B.; Eberl, T.; Edwards, P. G.; Eisenacher Glawion, D.; Elsässer, D.; Gehrels, N.; Gräfe, C.; Gulyaev, S.; Hase, H.; Horiuchi, S.; James, C. W.; Kappes, A.; Kappes, A.; Katz, U.; Kreikenbohm, A.; Kreter, M.; Kreykenbohm, I.; Langejahn, M.; Leiter, K.; Litzinger, E.; Longo, F.; Lovell, J. E. J.; McEnery, J.; Natusch, T.; Phillips, C.; Plötz, C.; Quick, J.; Ros, E.; Stecker, F. W.; Steinbring, T.; Stevens, J.; Thompson, D. J.; Trüstedt, J.; Tzioumis, A. K.; Weston, S.; Wilms, J.; Zensus, J. A.

    2016-08-01

    The astrophysical sources of the extraterrestrial, very high-energy neutrinos detected by the IceCube collaboration remain to be identified. Gamma-ray (γ-ray) blazars have been predicted to yield a cumulative neutrino signal exceeding the atmospheric background above energies of 100 TeV, assuming that both the neutrinos and the γ-ray photons are produced by accelerated protons in relativistic jets. As the background spectrum falls steeply with increasing energy, the individual events with the clearest signature of being of extraterrestrial origin are those at petaelectronvolt energies. Inside the large positional-uncertainty fields of the first two petaelectronvolt neutrinos detected by IceCube, the integrated emission of the blazar population has a sufficiently high electromagnetic flux to explain the detected IceCube events, but fluences of individual objects are too low to make an unambiguous source association. Here, we report that a major outburst of the blazar PKS B1424-418 occurred in temporal and positional coincidence with a third petaelectronvolt-energy neutrino event (HESE-35) detected by IceCube. On the basis of an analysis of the full sample of γ-ray blazars in the HESE-35 field, we show that the long-term average γ-ray emission of blazars as a class is in agreement with both the measured all-sky flux of petaelectronvolt neutrinos and the spectral slope of the IceCube signal. The outburst of PKS B1424-418 provides an energy output high enough to explain the observed petaelectronvolt event, suggestive of a direct physical association.

  19. New method for automatic background subtraction in symmetrized γ - γ coincidence matrices

    International Nuclear Information System (INIS)

    The most widely used technique to establish the level schemes of the nuclei is the analysis of γ - γ coincidence data. Since, an important difficulty in this kind of analysis is to properly define the coincidence background in γ - γ coincidence matrices, without introducing more statistical uncertainties or losing of information, a new automatic method (in the present stage suitable for symmetric matrices) has been developed. It is based on the algorithm sketched below: - given Mij, a symmetrized γ - γ coincidence matrix, the number of counts in each cell is Mij = idj> + icj> + idj> + icj>, where icj> represent the number of coincidences between discrete component on row i and continuous component on column j; - by defining the continuous component on each row of the matrix Mij, one obtain the non-symmetric matrix Bij = icj> + icj>; - by using the property of symmetry for Mij, the peak-peak coincidences are idj> = Mij - Bij - Bji + icj>. We choose to isolate Bij on each row of the Mij matrix and then to construct the continuous component icj>. On this purpose we have developed an original, robust algorithm for background subtraction in one-dimensional γ-spectra which provides a good quality subtraction, independent of the statistics or peak density of the processed spectrum. A computer code based on our method was written and has been tested for many experimental situations using data obtained both with the GASP array and with two detectors at IFIN-HH TANDEM accelerator. Some spectra obtained with gates on different background subtracted matrices are presented. (authors)

  20. Distinct coincidence detectors govern the corticostriatal spike timing-dependent plasticity.

    Science.gov (United States)

    Fino, Elodie; Paille, Vincent; Cui, Yihui; Morera-Herreras, Teresa; Deniau, Jean-Michel; Venance, Laurent

    2010-08-15

    Corticostriatal projections constitute the main input to the basal ganglia, an ensemble of interconnected subcortical nuclei involved in procedural learning. Thus, long-term plasticity at corticostriatal synapses would provide a basic mechanism for the function of basal ganglia in learning and memory. We had previously reported the existence of a corticostriatal anti-Hebbian spike timing-dependent plasticity (STDP) at synapses onto striatal output neurons, the medium-sized spiny neurons. Here, we show that the blockade of GABAergic transmission reversed the time dependence of corticostriatal STDP. We explored the receptors and signalling mechanisms involved in the corticostriatal STDP. Although classical models for STDP propose NMDA receptors as the unique coincidence detector, the involvement of multiple coincidence detectors has also been demonstrated. Here, we show that corticostriatal STDP depends on distinct coincidence detectors. Specifically, long-term potentiation is dependent on NMDA receptor activation, while long-term depression requires distinct coincidence detectors: the phospholipase Cbeta (PLCbeta) and the inositol-trisphosphate receptor (IP3R)-gated calcium stores. Furthermore, we found that PLCbeta activation is controlled by group-I metabotropic glutamate receptors, type-1 muscarinic receptors and voltage-sensitive calcium channel activities. Activation of PLCbeta and IP3Rs leads to robust retrograde endocannabinoid signalling mediated by 2-arachidonoyl-glycerol and cannabinoid CB1 receptors. Interestingly, the same coincidence detectors govern the corticostriatal anti-Hebbian STDP and the Hebbian STDP reported at cortical synapses. Therefore, LTP and LTD induced by STDP at corticostriatal synapses are mediated by independent signalling mechanisms, each one being controlled by distinct coincidence detectors. PMID:20603333