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Sample records for alpha-conversion electron coincidence

  1. Alpha and conversion electron spectroscopy of {sup 238,239}Pu and {sup 241}Am and alpha-conversion electron coincidence measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dion, Michael P., E-mail: michael.dion@pnnl.gov; Miller, Brian W.; Warren, Glen A.

    2016-09-11

    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 {sup 241}Am, {sup 238}Pu and {sup 239}Pu using a dual-stage peltier-cooled 25 mm{sup 2} 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 {sup 241}Am.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-09-01

    A technique to determine the isotopics of a mixed actinide sample has been proposed by measuring the coincidence of the alpha particle during radioactive decay with the conversion electron (or Auger) emitted during the relaxation of the daughter isotope. This presents a unique signature to allow the deconvolution of isotopes that possess overlapping alpha particle energy. 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. A passivated ion implanted planar silicon detector provided measurements of alpha spectroscopy. 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 to aid in the coincident measurement approach.

  3. Electron-electron coincidence spectroscopies at surfaces

    International Nuclear Information System (INIS)

    Stefani, G.; Iacobucci, S.; Ruocco, A.; Gotter, R.

    2002-01-01

    In the past 20 years, a steadily increasing number of electron-electron coincidence experiments on atoms and molecules have contributed to a deeper understanding of electron-electron correlation effects. In more recent years this technique has been extended to the study of solid surfaces. This class of one photon IN two electrons OUT experiments will be discussed with an emphasis on grazing incidence geometry, that is expected to be particularly suited for studying surfaces. The crucial question of which is the dominant mechanism that leads to ejection of pairs of electron from the surface will be addressed. It will be shown that, depending on the kinematics chosen, the correlated behaviour of the pairs of electrons detected might be singled out from independent particle one

  4. Fast counting electronics for neutron coincidence counting

    International Nuclear Information System (INIS)

    Swansen, J.E.

    1987-01-01

    This patent describes a high speed circuit for accurate neutron coincidence counting comprising: neutron detecting means for providing an above-threshold signal upon neutron detection; amplifying means inputted by the neutron detecting means for providing a pulse output having a pulse width of about 0.5 microseconds upon the input of each above threshold signal; digital processing means inputted by the pulse output of the amplifying means for generating a pulse responsive to each input pulse from the amplifying means and having a pulse width of about 50 nanoseconds effective for processing an expected neutron event rate of about 1 Mpps: pulse stretching means inputted by the digital processing means for producing a pulse having a pulse width of several milliseconds for each pulse received form the digital processing means; visual indicating means inputted by the pulse stretching means for producing a visual output for each pulse received from the digital processing means; and derandomizing means effective to receive the 50 ns neutron event pulses from the digital processing means for storage at a rate up to the neutron event rate of 1 Mpps and having first counter means for storing the input neutron event pulses

  5. Electron coincidence spectroscopy of sodium and potassium

    International Nuclear Information System (INIS)

    Frost, L.; Weigold, E.

    1982-03-01

    The Na 3s and K 4s electron momentum distributions have been obtained using the noncoplanar symmetric (e,2e) reaction at total energies of 800 eV and 1200 eV. They show excellent agreement with the results of plane wave impulse approximation calculations using Roothaan-Hartree-Fock functions, after small corrections are made for the finite angular resolution of the apparatus. The potassium valence s momentum profile is a little narrower than that for sodium, implying a correspondingly slightly larger spatial distribution of the outer valence electrons. The ratio between the (n-1)p and ns cross-sections at their respective maxima in q-space were measured to be 0.009 +- 0.003 and 0.019 +- 0.003 for Na and K respectively. These cross-section ratios are in agreement with the PWIA calculations

  6. Electronic neutron sensor based on coincidence detection

    International Nuclear Information System (INIS)

    Barelaud, B.; Decossas, J.L.; Mokhtari, F.; Vareille, J.C.

    1996-01-01

    The last symposium on neutron dosimetry which took place in Paris in November 1995 have shown again that it doesn't exist any individual active neutron dosemeter. The state of art on electronic device, the needs of the nuclear power industry in individual neutron monitoring and the new trends of The last symposium on neutron dosimetry which took place in Paris in November 1995 have shown again that it doesn't exist any individual active neutron dosemeter. The state of art on electronic device, the needs of the nuclear power industry in individual neutron monitoring and the new trends of researches were presented. They confirm the relevance of our studies in progress in the C2M team of the University of Limoges. The aim of this work is to realize an individual electronic neutron dosemeter. The device in the progress of being development will operate either as a dosemeter or as ratemeter giving H p (10) and H p (10) either as a spectrometer permitting to characterize the primary neutron beam. (author)

  7. Photoion Auger-electron coincidence measurements near threshold

    International Nuclear Information System (INIS)

    Levin, J.C.; Biedermann, C.; Keller, N.; Liljeby, L.; Short, R.T.; Sellin, I.A.; Lindle, D.W.

    1990-01-01

    The vacancy cascade which fills an atomic inner-shell hole is a complex process which can proceed by a variety of paths, often resulting in a broad distribution of photoion charge states. We have measured simplified argon photoion charge distributions by requiring a coincidence with a K-LL or K-LM Auger electron, following K excitation with synchrotron radiation, as a function of photon energy, and report here in detail the argon charge distributions coincident with K-L 1 L 23 Auger electrons. The distributions exhibit a much more pronounced photon-energy dependence than do the more complicated non-coincident spectra. Resonant excitation of the K electron to np levels, shakeoff of these np electrons by subsequent decay processes, double-Auger decay, and recapture of the K photoelectron through postcollision interaction occur with significant probability. 17 refs

  8. A coincidence study between photo- and Auger electrons

    International Nuclear Information System (INIS)

    Ricz, S.; Koever, A.; Varga, D.; Molnar, J.; Aksela, S.; Jurvansuu, M.

    2000-01-01

    Complete text of publication follows. The investigation of double differential cross sections of photon induced Auger electrons provides very sensitive method for studying the rearrangement process, especially when the angular correlation between photo- and Auger electrons is also studied. Such type of measurements could reveal a new aspect in studying the electron-electron, hole-electron and photoelectron - Auger electron interactions. It enables one to separate the overlapping Auger lines belonging to different initial holes. The traditional coincidence measurement is very time consuming and causes serious calibration problems. In order to overcome these experimental difficulties a new electron-spectrometer (ESA-22) was developed in ATOMKI, Debrecen in cooperation with the Electron spectroscopy group of University of Oulu, Finland. The analyzer consists of a spherical and a cylindrical part. It is very similar to the ESA-21 analyzer. The main differences is that the focal ring can be set different diameters thus either a series of channel detectors can be used to detect the electrons at different angles or a position sensitive channel plate can be applied for simultaneous angular recording of electrons. Furthermore the outer sphere and cylinder are cut into two parts so the spectrometer is capable to analyze two independent angularly resolved electron spectra (in the 0 deg - 180 deg region) at different energy regions, simultaneously. A special electronic control and data handling electronics and software was worked out to control the analyzer. The first results were presented in. In the last year the ESA-22 electron-spectrometer was transported to the I411 beam line of MAX-II synchrotron in Lund, Sweden. The advanced properties of the spectrometer was investigated by measuring coincidences between the photoelectrons originated from the Ar L 3 subshell and the Ar Auger electrons in the 203-207 eV energy region. Fig. 1 shows the single and the coincidence spectra

  9. Data Acquisition System for Electron Energy Loss Coincident Spectrometers

    International Nuclear Information System (INIS)

    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 position-sensitive 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

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

    International Nuclear Information System (INIS)

    Bodi, Andras; Johnson, Melanie; Gerber, Thomas; Gengeliczki, Zsolt; Sztaray, Balint; Baer, Tomas

    2009-01-01

    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 10 3 -10 7 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.

  11. Development of an Apparatus for High-Resolution Auger Photoelectron Coincidence Spectroscopy (APECS) and Electron Ion Coincidence (EICO) Spectroscopy

    Science.gov (United States)

    Kakiuchi, Takuhiro; Hashimoto, Shogo; Fujita, Narihiko; Mase, Kazuhiko; Tanaka, Masatoshi; Okusawa, Makoto

    We have developed an electron electron ion coincidence (EEICO) apparatus for high-resolution Auger photoelectron coincidence spectroscopy (APECS) and electron ion coincidence (EICO) spectroscopy. It consists of a coaxially symmetric mirror electron energy analyzer (ASMA), a miniature double-pass cylindrical mirror electron energy analyzer (DP-CMA), a miniature time-of-flight ion mass spectrometer (TOF-MS), a magnetic shield, an xyz stage, a tilt-adjustment mechanism, and a conflat flange with an outer diameter of 203 mm. A sample surface was irradiated by synchrotron radiation, and emitted electrons were energy-analyzed and detected by the ASMA and the DP-CMA, while desorbed ions were mass-analyzed and detected by the TOF-MS. The performance of the new EEICO analyzer was evaluated by measuring Si 2p photoelectron spectra of clean Si(001)-2×1 and Si(111)-7×7, and by measuring Si-L23VV-Si-2p Auger photoelectron coincidence spectra (Si-L23VV-Si-2p APECS) of clean Si(001)-2×1.

  12. Secondary electron emission studied by secondary electron energy loss coincidence spectroscopy (SE2ELCS)

    International Nuclear Information System (INIS)

    Khalid, R.

    2013-01-01

    Emission of secondary electrons is of importance in many branches of fundamental and applied science. It is widely applied in the electron microscope for the investigation of the structure and electronic state of solid surfaces and particle detection in electron multiplier devices, and generally it is related to the energy dissipation of energetic particles moving inside a solid. The process of secondary electron emission is a complex physical phenomenon, difficult to measure experimentally and treat theoretically with satisfactory accuracy. The secondary electron spectrum measured with single electron spectroscopy does not provide detailed information of the energy loss processes responsible for the emission of secondary electrons. This information can be accessed when two correlated electron pairs are measured in coincidence and the pair consists of a backscattered electron after a given energy loss and a resulting emitted secondary electron. To investigate the mechanisms responsible for the emission of secondary electrons, a reflection (e,2e) coincidence spectrometer named Secondary Electron Electron Energy Loss Coincidence Spectrometer (SE2ELCS) has been developed in the framework of this thesis which allows one to uncover the relation between the features in the spectra which are due to energy losses and true secondary electron emission structures. The correlated electron pairs are measured with a hemispherical mirror analyzer (HMA) and a time of flight analyzer (TOF) by employing a continuous electron beam. An effort has been made to increase the coincidence count rate by increasing the effective solid angle of the TOF analyzer and optimizing the experimental parameters to get optimum energy resolution. Double differential coincidence spectra for a number of materials namely, nearly free electron metals (Al, Si), noble metals (Ag, Au, Cu, W) and highly oriented pyrolytic graphite (HOPG) have been measured using this coincidence spectrometer. The

  13. A new apparatus for electron-ion multiple coincidence momentum imaging spectroscopy

    International Nuclear Information System (INIS)

    Morishita, Y.; Kato, M.; Pruemper, G.; Liu, X.-J.; Lischke, T.; Ueda, K.; Tamenori, Y.; Oura, M.; Yamaoka, H.; Suzuki, I.H.; Saito, N.

    2006-01-01

    We have developed a new experimental apparatus for the electron-ion multiple coincidence momentum imaging spectroscopy in order to obtain the angular distributions of vibration-resolved photoelectrons from molecules fixed in space. The apparatus consists of a four-stage molecular supersonic jet and a spectrometer analyzing three-dimensional momenta of fragment ions and electrons in coincidence

  14. Electron emission relevant to inner-shell photoionization of condensed water studied by multi-electron coincidence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hikosaka, Y., E-mail: hikosaka@las.u-toyama.ac.jp [Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194 (Japan); Mashiko, R.; Konosu, Y.; Soejima, K. [Department of Environmental Science, Niigata University, Niigata 950-2181 (Japan); Shigemasa, E. [UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 (Japan); SOKENDAI, Okazaki 444-8585 (Japan)

    2016-11-15

    Highlights: • Multi-electron coincidence spectroscopy is applied to the study of electron emissions from condensed H2O molecules. • Coincidence Auger spectra are obtained for different photoelectron energies. • The energy distribution of the slow electrons ejected in the Auger decay is deduced from three-fold coincidences. - Abstract: Multi-electron coincidence spectroscopy using a magnetic-bottle electron spectrometer has been applied to the study of the Auger decay following O1s photoionization of condensed H{sub 2}O molecules. Coincidence Auger spectra are obtained for three different photoelectron energy ranges. In addition, the energy distribution of the slow electrons ejected in the Auger decay of the O1s core hole is deduced from three-fold coincidences.

  15. Analysis of 125Xe electron-photon coincidence decay

    International Nuclear Information System (INIS)

    Klingberg, F.J.; Biegalski, S.R.

    2016-01-01

    As part of the verification component of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), environmental gas samples originating from nuclear fission are analyzed for the presence of 131m Xe, 133m Xe, 133 Xe, and 135 Xe. In this work, the non-traditional radioxenon isotope 125 Xe was investigated. The isotope was produced as an isotopically pure sample via neutron activation of 124 Xe at the University of Texas at Austin Nuclear Engineering Teaching Lab's TRIGA MARK II Reactor. The sample was then measured using a HPGe detector as well as an ARSA-style b-c coincidence detector. Potential sources and sensitivities for production of 125 Xe are also considered for relevance to the CTBT verification mission. (author)

  16. Angular correlations of coincident electron-positron pairs in heavy ion collisions

    International Nuclear Information System (INIS)

    Graf, O.

    1988-10-01

    In the present thesis angular correlations of coincident electron-positron pairsnin heavy ion collisions are studied. It is meant as a contribution to the answer of fundamental questions in the quantum electrodynamics of strong fields. (orig./HSI) [de

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

    International Nuclear Information System (INIS)

    Arp, U.

    1996-01-01

    Argon L 2.3 -M 2.3 M 2.3 Auger-electron spectra were measured in coincidence with Kα 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

  18. Secondary electron/reflected particle coincidence studies during slow highly charged ion-surface interactions

    Energy Technology Data Exchange (ETDEWEB)

    McGrath, C.T.; Szilagyi, Z.; Shah, M.B.; McCullough, R.W. [Queen' s Univ., Belfast, Northern Ireland (United Kingdom); Woolsey, J.M. [Stirling Univ. (United Kingdom). DBMS; Trassl, R.; Salzborn, E. [Giessen Univ. (Germany). Inst. fuer Kernphysik

    2001-07-01

    We have measured the secondary electron emission statistics (ES) for 5 keV N{sup q+} (q = 1-4) ions incident at 10 on polycrystalline aluminium, in coincidence with specularly reflected N{sup 0}. In this arrangement the kinetic contribution to secondary electron emission is minimised. The experimental data shows that the coincident electron yield, {gamma}, increases linearly with incident ion charge state. The kinetic emission contribution has also been determined from this data. The ES due to 2 and 4 keV He{sup 2+} impact on polycrystalline aluminium in coincidence with specularly reflected He{sup +} and He{sup 0} have also been determined. The process He{sup 2+} {yields} He{sup 0} yields a larger {gamma} value than the process He{sup 2+} {yields} He{sup +}. (orig.)

  19. Multiple capture investigated by coincident electron spectroscopy in X7++Ar, at 70 keV

    International Nuclear Information System (INIS)

    Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A.

    1999-01-01

    The multiple electron capture in N 7+ + Ar and F 7+ (1s 2 ) + Ar systems is investigated at 70 keV with a new electron-recoil ion charge coincidence experiment. The whole electron energy range has been studied. Up to six electrons are found to be captured into autoionizing states. The recoil ion charge distribution associated with the emission of electrons is similar for both systems and found to be in good agreement with the prediction of Niehaus's model roughly adapted to take into account autoionizing cascades. New findings for the coincident double and triple captures are briefly discussed. A capture of an inner L-shell electron of Ar into the K-shell of the projectile is also observed in N 7+ + Ar collisions. (orig.)

  20. Coincident Auger electron and recoil ion momentum spectroscopy for low-energy ion-atom collisions

    International Nuclear Information System (INIS)

    Laurent, G.; Tarisien, M.; Flechard, X.; Jardin, P.; Guillaume, L.; Sobocinski, P.; Adoui, L.; Bordenave-Montesquieu, A.; Bordenave-Montesquieu, D.; Chesnel, J.-Y.; Fremont, F.; Hennecart, D.; Lienard, E.; Maunoury, L.; Moretto-Capelle, P.; Cassimi, A.

    2003-01-01

    The recoil ion momentum spectroscopy (RIMS) method combined with the detection of Auger electrons has been used successfully to analyse double electron capture following O 6+ + He collisions at low impact velocities. Although RIMS and Auger spectroscopies are known to be efficient tools to obtain details on the primary processes occurring during the collision, the conjunction of both techniques provides new insights on the electron capture process. In the present experiment, triple coincidence detection of the scattered projectile, the target recoil ion and the Auger electron allows for a precise identification of the doubly excited states O 4+ (1s 2 nln ' l ' ) populated after double electron-capture events

  1. Studies of the electron-impact double-ionisation process in magnesium using coincidence techniques

    International Nuclear Information System (INIS)

    Ford, M.J.

    1998-01-01

    This article will review recent measurements of the electron-impact double-ionisation of atomic magnesium. Results for the resonant Auger double-ionisation process with coincident detection of all three outgoing electrons, the (e, 3e) experiment, and for the direct double-ionisation process where only two outgoing electrons are detected, the (e, (3 -1)e) experiment, will be discussed. The results are analysed with reference to ionisation mechanisms and comparisons are made with calculated double-ionisation cross sections. Copyright (1998) CSIRO Australia

  2. Interaction of multicharged ions with molecules (CO2, C60) by coincident electron spectroscopy

    International Nuclear Information System (INIS)

    Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A.

    2001-01-01

    First results for the investigation of electron capture processes in collisions between multicharged ions and molecule targets using electron spectroscopy in coincidence with charged fragments, are presented. It is shown that a much more detailed investigation of the capture reaction can be achieved using molecular instead of heavy atomic targets provided that an analysis of the target dissociation is made. The collisional systems 18 O 8+ +Ar, CO 2 and C 60 have been studied at 80 keV. Non coincident electron spectra as well as first results of double or triple coincidence experiments are discussed. Kinetic energy distributions of the C n + fragments (n=1 to 8) produced in multiple capture processes from C 60 target are given. A detailed investigation of the double capture process with CO 2 molecule allows the measurement of kinetic energy release distributions (KERD) which characterize the dissociation of CO 2 2+ molecular ions; our results are found to be very similar to those measured in double photoionisation experiments. (orig.)

  3. Coincident Auger electron and recoil ion momentum spectroscopy for low-energy ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Laurent, G. E-mail: glaurent@ganil.fr; Tarisien, M.; Flechard, X.; Jardin, P.; Guillaume, L.; Sobocinski, P.; Adoui, L.; Bordenave-Montesquieu, A.; Bordenave-Montesquieu, D.; Chesnel, J.-Y.; Fremont, F.; Hennecart, D.; Lienard, E.; Maunoury, L.; Moretto-Capelle, P.; Cassimi, A

    2003-05-01

    The recoil ion momentum spectroscopy (RIMS) method combined with the detection of Auger electrons has been used successfully to analyse double electron capture following O{sup 6+} + He collisions at low impact velocities. Although RIMS and Auger spectroscopies are known to be efficient tools to obtain details on the primary processes occurring during the collision, the conjunction of both techniques provides new insights on the electron capture process. In the present experiment, triple coincidence detection of the scattered projectile, the target recoil ion and the Auger electron allows for a precise identification of the doubly excited states O{sup 4+} (1s{sup 2}nln{sup '}l{sup '}) populated after double electron-capture events.

  4. Coincidence Doppler broadening study on hydrocarbons with pi and sigma valence electrons: positronium correction

    International Nuclear Information System (INIS)

    Djourelov, N.; Suzuki, T.; Yu, R.S.; Ito, Y.

    2005-01-01

    The coincidence Doppler broadening (CDB) technique was applied to study the electron momentum distribution in anthracene, diphenyl, naphthalene, and polystyrene. A method for separation of the positron and positronium (Ps) components from the Doppler-broadened annihilation line (DBAL) was developed further to be applicable to hydrocarbons with different π and σ valence electron distributions. This method allows extraction of the electron momentum distribution (EMD) from DBAL for samples when Ps formation occurs. The annihilation on π valence electrons was detected as broadening of the EMD compared to that obtained for a polymer sample only with σ valence electrons. The broadening appeared as a significant change in the shape of the CDB ratio of the corresponding positronium-corrected curves: a slight enhancement above the unity line in the low-momentum region and a drop in the momentum region, 10-20x10 -3 m o c

  5. Silicon PIN diode based electron-gamma coincidence detector system for Noble Gases monitoring.

    Science.gov (United States)

    Khrustalev, K; Popov, V Yu; Popov, Yu S

    2017-08-01

    We present a new second generation SiPIN based electron-photon coincidence detector system developed by Lares Ltd. for use in the Noble Gas measurement systems of the International Monitoring System and the On-site Inspection verification regimes of the Comprehensive Nuclear-Test Ban Treaty (CTBT). The SiPIN provide superior energy resolution for electrons. Our work describes the improvements made in the second generation detector cells and the potential use of such detector systems for other applications such as In-Situ Kr-85 measurements for non-proliferation purposes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Evidence of sequential interatomic decay in argon trimers obtained by electron-triple-ion coincidence spectroscopy

    International Nuclear Information System (INIS)

    Liu, X-J; Saito, N; Fukuzawa, H; Morishita, Y; Stoychev, S; Kuleff, A; Suzuki, I H; Tamenori, Y; Richter, R; Pruemper, G; Ueda, K

    2007-01-01

    Sequential interatomic decay, where the first step is an Auger decay with interatomic character and the second step is a pure interatomic Coulombic decay (ICD), is identified in Ar trimers Ar 3 . The 2p hole state in Ar 3 decays via the L 2,3 M 1 M 2,3 Auger to the one-site two-hole states Ar ++ (3s -1 3p -1 )-Ar-Ar that couples to the two-site satellite states Ar + (3p -2 nl)-Ar + (3p -1 )-Ar. These states are subject to ICD to the states Ar + (3p -1 )-Ar + (3p -1 )-Ar + (3p -1 ), in which the nl electron fills the 3p hole in the same Ar site and one of the 3p electrons in the third Ar site is emitted as a slow ICD electron. This ICD process is identified unambiguously by electron-ion-ion-ion coincidence spectroscopy in which the kinetic energy of the slow ICD electron and the kinetic energy release among the three Ar + ions are measured in coincidence. (fast track communication)

  7. Resonant Auger electron-photoion coincidence study of the fragmentation dynamics of an acrylonitrile molecule

    Energy Technology Data Exchange (ETDEWEB)

    Kooser, K; Ha, D T; Granroth, S; Itaelae, E; Nommiste, E; Kukk, E [Department of Physics, University of Turku, FIN-20014 Turku (Finland); Partanen, L; Aksela, H, E-mail: kunkoo@utu.f [Department of Physics, University of Oulu, Box 3000, FIN-90014 Oulu (Finland)

    2010-12-14

    Monochromatic synchrotron radiation was used to promote K-shell electrons of nitrogen and carbon from the cyano group (C {identical_to} N) of gaseous acrylonitrile (C{sub 2}H{sub 3}-CN) to the unoccupied antibonding {pi}*{sub C} {sub {identical_to} N} orbital. Photofragmentation of acrylonitrile molecules following selective resonant core excitations of carbon and nitrogen core electrons to the {pi}*{sub C} {sub {identical_to} N} orbital was investigated using the electron-energy-resolved photoelecton-photoion coincidence technique. The fragment ion mass spectra were recorded in coincidence with the resonant Auger electrons, emitted in the decay process of the core-excited states. Singly and triply deuterated samples were used for fragment identification. The results showed the initial core-hole localization to be of minor importance in determining the dissociation pattern of the molecular cation. The participator and spectator Auger transitions produce entirely different fragmentation patterns and the latter indicates that complex nuclear rearrangements take place. It is suggested that the calculated kinetic energy releases are caused by the existence of metastable states, which appear with the opening of the spectator Auger channels.

  8. Photoelectron-Auger electron coincidence spectroscopy of free molecules: New experiments

    International Nuclear Information System (INIS)

    Ulrich, Volker; Barth, Silko; Lischke, Toralf; Joshi, Sanjeev; Arion, Tiberiu; Mucke, Melanie; Foerstel, Marko; Bradshaw, Alex M.; Hergenhahn, Uwe

    2011-01-01

    Photoelectron-Auger electron coincidence spectroscopy probes the dicationic states produced by Auger decay following the photoionization of core or inner valence levels in atoms, molecules or clusters. Moreover, the technique provides valuable insight into the dynamics of core hole decay. This paper serves the dual purpose of demonstrating the additional information obtained by this technique compared to Auger spectroscopy alone as well as of describing the new IPP/FHI apparatus at the BESSY II synchrotron radiation source. The distinguishing feature of the latter is the capability to record both the photoelectron and Auger electron with good energy and angle resolution, for which purpose a large hemispherical electrostatic analyser is combined with several linear time-of-flight spectrometers. New results are reported for the K-shell photoionization of oxygen (O 2 ) and the subsequent KVV Auger decay. Calculations in the literature for non-coincident O 2 Auger spectra are found to be in moderately good agreement with the new data.

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

    International Nuclear Information System (INIS)

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

    1972-01-01

    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

  10. A coincidence-type ion-electron converter detector for low-energy protons

    International Nuclear Information System (INIS)

    Benka, O.; Weinzierl, P.; Dobrozemsky, R.; Stratowa, C.

    1981-04-01

    A coincidence type ion-electron converter detector has been developed and used - together with an electrostatic energy-analyser - for precision measurements of the energy distribution of recoil protons from free-neutron decay. The most important aspect of the development was, besides keeping the background below 0,2 counts/sec in the presence of a certain radiation background, to achieve a high and energy-independent counting probability for protons with energies between 100 and 1000 eV. With an acceleration voltage of about 25 kV and Al-foils (20 to 35 ug/cmsup2) as converter, we obtained counting efficiences of 70 to 85 percent. The design and performance of the detector system, employing six foils with different sensitive areas, are described and discussed in detail. (author)

  11. 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.

  12. Imaging the electron transfer reaction of Ne2+ with Ar using position-sensitive coincidence spectroscopy

    International Nuclear Information System (INIS)

    Harper, Sarah M; Hu Wanping; Price, Stephen D

    2002-01-01

    A new experiment, employing position-sensitive detection coupled with time-of-flight mass spectrometry, has been used to investigate the single-electron transfer reaction between Ne 2+ and Ar by detecting the resulting pairs of singly charged ions in coincidence. The experimental technique allows the determination of the individual velocity vectors of the ionic products, in the centre-of-mass frame, for each reactive event detected. The experiments show that forward scattering dominates the reactivity, although a bimodal angular distribution is apparent. In addition, the spectra show that at laboratory frame collision energies from 4-14 eV the reactivity is dominated by Ne 2+ (2p 4 , 3 P) accepting an electron from an argon atom to form the ground state of Ne + together with an Ar + ion in an excited electronic level, predominantly arising from the Ar + (3s 2 3p 4 3d) configuration. The form of this reactivity, and the differences between the reactivity observed in these experiments and those performed at higher collision energies, are well reproduced by Landau-Zener theory

  13. Electron irradiation effect of polyurethane using coincidence doppler-broadening spectroscopy

    International Nuclear Information System (INIS)

    Yang, D.J.; Zhang, J.D.; Leung, J.K.C.; Beling, C.D.; Liu, L.B.

    2006-01-01

    Full text: To understand the electron irradiation effects on polymer, polyether-urethane (ETPU) samples of 2m m in thickness and 1 0 m m in diameter were irradiated by a 1.8M eV 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 15 x1 0 3m οc 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

  14. COINCIDENCES BETWEEN ELECTRONS AND TARGET IONS TO IDENTIFY CAPTURE CHANNELS IN COLLISIONS OF MULTIPLY CHARGED IONS ON GAS TARGETS

    NARCIS (Netherlands)

    POSTHUMUS, JH; MORGENSTERN, R

    1992-01-01

    We have investigated multielectron capture processes in collisions of Ar9+ on Ar by measuring the resulting Auger electrons in coincidence with charge-state-analyzed target ions. In this way it was possible to reconstruct partial electron energy spectra, each corresponding to a particular number of

  15. Multiple capture investigated by coincident electron spectroscopy in X{sup 7+}+Ar, at 70 keV

    Energy Technology Data Exchange (ETDEWEB)

    Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A. [Universite Paul Sabatier, Toulouse (France). Lab. Collisions-Agregats-Reactivite

    1999-11-01

    The multiple electron capture in N{sup 7+} + Ar and F{sup 7+}(1s{sup 2}) + Ar systems is investigated at 70 keV with a new electron-recoil ion charge coincidence experiment. The whole electron energy range has been studied. Up to six electrons are found to be captured into autoionizing states. The recoil ion charge distribution associated with the emission of electrons is similar for both systems and found to be in good agreement with the prediction of Niehaus`s model roughly adapted to take into account autoionizing cascades. New findings for the coincident double and triple captures are briefly discussed. A capture of an inner L-shell electron of Ar into the K-shell of the projectile is also observed in N{sup 7+} + Ar collisions. (orig.) 10 refs.

  16. An energy resolved electron-ion coincidence study near the S 2p thresholds of the SF6 molecule

    International Nuclear Information System (INIS)

    Kivimaeki, A; Ruiz, J Alvarez; Erman, P; Hatherly, P; Garcia, E Melero; Rachlew, E; Rius i Riu, J; Stankiewicz, M

    2003-01-01

    The fragmentation dynamics of the SF 6 molecule following the excitations of S 2p electrons into unoccupied molecular orbitals has been studied using the energy-resolved electron-ion coincidence technique. Fragmentation patterns were found to depend on the particular excitation and on the electronic state of the molecular ion. The spectator resonant Auger decay at the 2p → 6a 1g resonance induces changes in the ion distributions as compared to direct photoionization. Furthermore, coincidence spectra related to the same Auger structure display different ion abundances at the 2t 2g and 4e g shape resonances. Differences were also found in the Auger decay spectra. These findings give further support for the previously suggested many-electron character of the 4e g shape resonance

  17. Energy and angle resolved studies of double photo-ionisation of helium by electron time-of-flight coincidence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Viefhaus, J.; Avaldi, L.; Heiser, F.; Hentges, R.; Gessner, O.; Ruedel, A.; Wiedenhoeft, M.; Wieliczek, K.; Becker, U. [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany)

    1996-10-28

    Helium double photo-ionization is studied by a novel coincidence technique which employs time-of-flight spectrometers. Using this technique it is possible to collect simultaneously all the electron pairs, with different energy sharing, emitted by the absorption of a single energetic incident photon. The measurements, in a configuration where the two electrons emerge at 180{sup o} relative angle, provide the more complete information on the contribution of the ungerade amplitude to the triple differential cross section and allow the establishment of a relative scale for the full coincidence angular distribution measured by other experiments at the same photon energies, but only for a few selected energy-sharing conditions. (author).

  18. Interaction of multicharged ions with molecules (CO{sub 2}, C{sub 60}) by coincident electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A. [Universite Paul Sabatier, Toulouse (France). Lab. CAR-IRSAMC

    2001-07-01

    First results for the investigation of electron capture processes in collisions between multicharged ions and molecule targets using electron spectroscopy in coincidence with charged fragments, are presented. It is shown that a much more detailed investigation of the capture reaction can be achieved using molecular instead of heavy atomic targets provided that an analysis of the target dissociation is made. The collisional systems {sup 18}O{sup 8+}+Ar, CO{sub 2} and C{sub 60} have been studied at 80 keV. Non coincident electron spectra as well as first results of double or triple coincidence experiments are discussed. Kinetic energy distributions of the C{sub n}{sup +} fragments (n=1 to 8) produced in multiple capture processes from C{sub 60} target are given. A detailed investigation of the double capture process with CO{sub 2} molecule allows the measurement of kinetic energy release distributions (KERD) which characterize the dissociation of CO{sub 2}{sup 2+} molecular ions; our results are found to be very similar to those measured in double photoionisation experiments. (orig.)

  19. Wavelength dependent photoelectron circular dichroism of limonene studied by femtosecond multiphoton laser ionization and electron-ion coincidence imaging

    Science.gov (United States)

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

    2016-09-01

    Enantiomers of the monoterpene limonene have been investigated by (2 + 1) resonance enhanced multiphoton ionization and photoelectron circular dichroism employing tuneable, circularly polarized femtosecond laser pulses. Electron imaging detection provides 3D momentum measurement while electron-ion coincidence detection can be used to mass-tag individual electrons. Additional filtering, by accepting only parent ion tagged electrons, can be then used to provide discrimination against higher energy dissociative ionization mechanisms where more than three photons are absorbed to better delineate the two photon resonant, one photon ionization pathway. The promotion of different vibrational levels and, tentatively, different electronic ion core configurations in the intermediate Rydberg states can be achieved with different laser excitation wavelengths (420 nm, 412 nm, and 392 nm), in turn producing different state distributions in the resulting cations. Strong chiral asymmetries in the lab frame photoelectron angular distributions are quantified, and a comparison made with a single photon (synchrotron radiation) measurement at an equivalent photon energy.

  20. TARGET EXCITATION IN BARE ION XE/AR COLLISIONS STUDIED BY ELECTRON TARGET ION COINCIDENCES

    NARCIS (Netherlands)

    DENIJS, G; HOEKSTRA, R; MORGENSTERN, R

    We present electron spectra resulting from collisions of bare ions N-15(7+) and C-13(6+) on Ar and the charge state distribution of target ions resulting from C-13(6+)-Xe collisions. From both type of experiments we find evidence that electron capture accompanied by target excitation is an important

  1. The determination of electron momentum densities by inelastic scattering gamma-ray-electron coincidence measurements: The (γ,eγ)-experiment

    International Nuclear Information System (INIS)

    Rollason, A.J.; Bell, F.; Schneider, J.R.

    1989-09-01

    Measurements have been made of the recoiling electron in 320 keV gamma ray inelastic scattering collisions in thin aluminium targets. The angular correlation of these electrons detected in coincidence with the scattered photon is in agreement with the kinematic requirements of the Compton effect and is correctly predicted by Monte Carlo simulations based on the impulse approximation. Further simulations of ideal-geometry experiments indicate that information about the initial electron momenta is available from an examination of those electron-photon events originating in a surface layer of one electronic mean free path depth and that elastic scattering of the recoil electrons from greater depths produces a nearly flat background to this signal. The results clearly demonstrate the feasibility of the (γ,eγ) experiment for studying electron momentum densities with synchrotron radiation. (orig.) With 23 refs., 17 figs

  2. Coincidence set-up with a high duty-cycle, high energy electron accelerator

    International Nuclear Information System (INIS)

    Leconte, P.

    1981-01-01

    Important studies are now undertaken to develop continuous wave electron accelerators with energy ranging from 1 to 4 Gev. So very important effort must be now put on the development of the experimental set-up matching the performances expected from the electron beam. Major steps in the understanding of the nuclear systems will come from more and more exclusive experiments where well defined mechanisms will be selected

  3. Scattering of polarized electrons from polarized targets: Coincidence reactions and prescriptions for polarized half-off-shell single-nucleon cross sections

    International Nuclear Information System (INIS)

    Caballero, J.A.; Massachusetts Inst. of Tech., Cambridge, MA; Donnelly, T.W.; Massachusetts Inst. of Tech., Cambridge, MA; Poulis, G.I.; Massachusetts Inst. of Tech., Cambridge, MA

    1993-01-01

    Coincidence reactions of the type vector A( vector e, e'N)B involving the scattering of polarized electrons from polarized targets are discussed within the context of the plane-wave impulse approximation. Prescriptions are developed for polarized half-off single-nucleon cross sections; the different prescriptions are compared for typical quasi-free kinematics. Illustrative results are presented for coincidence polarized electron scattering from typical polarized nuclei. (orig.)

  4. Description and performance of an electron-ion coincidence TOF spectrometer used at the Brazilian synchrotron facility LNLS

    International Nuclear Information System (INIS)

    Burmeister, F.; Coutinho, L.H.; Marinho, R.R.T.; Homem, M.G.P.; Morais, M.A.A. de; Mocellin, A.; Bjoerneholm, O.; Sorensen, S.L.; Fonseca, P.T.; Lindgren, A.; Naves de Brito, A.

    2010-01-01

    This paper reports the characteristics and performance of a Time-of-Flight Mass Spectrometer (TOF-MS) for coincidence measurements between electrons and ions that has been developed jointly in Sweden and Brazil. The spectrometer, used for studies of inner-shell photoexcitation of molecules in the gas-phase, has been optimized by implementing ion and electron lenses to allow the use of relatively small diameter detectors. Simulations were performed to understand the lens performance and they show that ions (electrons) could be collected without angular discrimination with a maximum kinetic energy up to ten (two) times higher than without the lens actions. A rotary vacuum chamber allows the spectrometer axis to be positioned at different angles relative to the polarization vector of the excitation beam. An important characteristic of the apparatus is that the acquisition setup allows a multi-hit capability with 1 ns resolution. Hereby, Photoelectron-Photoion-Photoion Coincidence (PEPIPICO) measurements can be performed on molecules containing two or more atoms of equal mass. A method to obtain experimental detection efficiencies of a single ion and one of one, two or three electrons has been developed. A systematic study of the interaction region has been performed to determine the shape of the photon and gas beams. Measurements on molecular nitrogen demonstrate the spectrometer's ability to resolve fragments with the same charge to mass ratio arriving within only a few ns. Simulations and experimental results of fragmentation of two singly charged cation nitrogen atoms agree, confirming that the spectrometer performance is well understood.

  5. Description and performance of an electron-ion coincidence TOF spectrometer used at the Brazilian synchrotron facility LNLS

    Energy Technology Data Exchange (ETDEWEB)

    Burmeister, F. [Laboratorio Nacional de Luz Sincrotron, 13084-971, Campinas, SP (Brazil); Department of Physics, Uppsala University, Box 530, S-751 21 Uppsala (Sweden); Coutinho, L.H. [Laboratorio Nacional de Luz Sincrotron, 13084-971, Campinas, SP (Brazil); Instituto de Fisica, Universidade Estadual de Campinas, 13083-970 Campinas, SP (Brazil); Marinho, R.R.T. [Laboratorio Nacional de Luz Sincrotron, 13084-971, Campinas, SP (Brazil); Homem, M.G.P. [Departamento de Quimica, Universidade Federal de Sao Carlos, 13565-905 Sao Carlos, SP (Brazil); Morais, M.A.A. de; Mocellin, A. [Instituto de Fisica, Universidade de Brasilia, 70910-900 Brasilia, DF (Brazil); Bjoerneholm, O. [Department of Physics, Uppsala University, Box 530, S-751 21 Uppsala (Sweden); Sorensen, S.L. [SLF, Institute of Physics, University of Lund, Box 118, S-221 00 Lund (Sweden); Fonseca, P.T. [Laboratorio Nacional de Luz Sincrotron, 13084-971, Campinas, SP (Brazil); Lindgren, A. [SLF, Institute of Physics, University of Lund, Box 118, S-221 00 Lund (Sweden); Naves de Brito, A., E-mail: arnaldo.naves@gmail.co [Laboratorio Nacional de Luz Sincrotron, 13084-971, Campinas, SP (Brazil); Instituto de Fisica, Universidade de Brasilia, 70910-900 Brasilia, DF (Brazil)

    2010-06-15

    This paper reports the characteristics and performance of a Time-of-Flight Mass Spectrometer (TOF-MS) for coincidence measurements between electrons and ions that has been developed jointly in Sweden and Brazil. The spectrometer, used for studies of inner-shell photoexcitation of molecules in the gas-phase, has been optimized by implementing ion and electron lenses to allow the use of relatively small diameter detectors. Simulations were performed to understand the lens performance and they show that ions (electrons) could be collected without angular discrimination with a maximum kinetic energy up to ten (two) times higher than without the lens actions. A rotary vacuum chamber allows the spectrometer axis to be positioned at different angles relative to the polarization vector of the excitation beam. An important characteristic of the apparatus is that the acquisition setup allows a multi-hit capability with 1 ns resolution. Hereby, Photoelectron-Photoion-Photoion Coincidence (PEPIPICO) measurements can be performed on molecules containing two or more atoms of equal mass. A method to obtain experimental detection efficiencies of a single ion and one of one, two or three electrons has been developed. A systematic study of the interaction region has been performed to determine the shape of the photon and gas beams. Measurements on molecular nitrogen demonstrate the spectrometer's ability to resolve fragments with the same charge to mass ratio arriving within only a few ns. Simulations and experimental results of fragmentation of two singly charged cation nitrogen atoms agree, confirming that the spectrometer performance is well understood.

  6. 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...

  7. 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)

    Toledo, Fabio de

    2009-01-01

    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)

  8. Inexpensive read-out for coincident electron spectroscopy with a transmission electron microscope at nanometer scale using micro channel plates and multistrip anodes

    International Nuclear Information System (INIS)

    Hollander, R.W.; Bom, V.R.; Van Eijk, C.W.E.; Faber, J.S.; Hoevers, H.; Kruit, P.

    1994-01-01

    The elemental composition of a sample at nanometer scale is determined by measurement of the characteristic energy of Auger electrons, emitted in coincidence with incoming primary electrons from a microbeam in a scanning transmission electron microscope (STEM). Single electrons are detected with position sensitive detectors, consisting of MicroChannel Plates (MCP) and MultiStrip Anodes (MSA), one for the energy of the Auger electrons (Auger-detector) and one for the energy loss of primary electrons (EELS-detector). The MSAs are sensed with LeCroy 2735DC preamplifiers. The fast readout is based on LeCroy's PCOS III system. On the detection of a coincidence (Event) energy data of Auger and EELS are combined with timing data to an Event word. Event words are stored in list mode in a VME memory module. Blocks of Event words are scanned by transputers in VME and two-dimensional energy histograms are filled using the timing information to obtain a maximal true/accidental ratio. The resulting histograms are stored on disk of a PC-386, which also controls data taking. The system is designed to handle 10 5 Events per second, 90% of which are accidental. In the histograms the ''true'' to ''accidental'' ratio will be 5. The dead time is 15%. ((orig.))

  9. Electron-muon coincidences in proton-proton collisions at the CERN Intersecting Storage Rings

    CERN Document Server

    Clark, A G; Darriulat, Pierre; Eggert, K; Hungerbühler, V; Jenni, Peter; Lapuyade, C; Modis, T; Pérez, P; Renshall, H; Richter, Burton; Smadja, G; Strauss, J; Strolin, P; Tarnopolsky, G J; Teiger, J; Tur, C; Vialle, J P; Zaccone, Henri; Zallo, A; Zylberstejn, A

    1978-01-01

    In an experiment carried out at the CERN Intersecting Storage Rings with a highly selective electron spectrometer system and a magnetized iron filter to detect muons, the authors have observed 32+or-16 dilepton events of the type p+p to mu /sup +or-/+e/sup -or+/+... The integrated luminosity of the experiment was (2.0+or-0.1)*10/sup 37/ cm /sup -2/, and the over-all detection efficiency 0.14+or-0.07. Interpreting this signal as due to charmed meson-pair production, the authors estimate a model-dependent acceptance of 6.5*10/sup -5/ per event, and a cross-section sigma (p+p to D+D+...)=(18+or-9) mu b, with a scale uncertainty of 50% due to the detection efficiency. (9 refs).

  10. Single-photon double and triple ionization of acetaldehyde (ethanal) studied by multi-electron coincidence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zagorodskikh, S. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Gothenburg (Sweden); Zhaunerchyk, V. [Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Gothenburg (Sweden); Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Mucke, M. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Eland, J.H.D. [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom); Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Gothenburg (Sweden); Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Squibb, R.J. [Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Gothenburg (Sweden); Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Karlsson, L. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Linusson, P. [Department of Physics, Stockholm University, AlbaNova University Center, SE-106 91 Stockholm (Sweden); Feifel, R., E-mail: raimund.feifel@gu.se [Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Gothenburg (Sweden); Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden)

    2015-12-16

    Highlights: • The first ever valence double ionization spectrum of acetaldehyde is reported. • The first ever site-selectively extracted Auger spectra of acetaldehyde are reported. • The first ever Auger spectra of acetaldehyde involving shake-up states are reported. • The first ever triple ionization spectra of acetaldehyde are reported. • The first ever energy sharing of electron pairs emitted by acetaldehyde is presented. - Abstract: Single-photon multiple ionization processes of acetaldehyde (ethanal) have been experimentally investigated by utilizing a multi-particle coincidence technique based on the time-of-flight magnetic bottle principle, in combination with either a synchrotron radiation source or a pulsed helium discharge lamp. The processes investigated include double and triple ionization in the valence region as well as single and double Auger decay of core-ionized acetaldehyde. The latter are studied site-selectively for chemically different carbon core vacancies, scrutinizing early theoretical predictions specifically made for the case of acetaldehyde. Moreover, Auger processes in shake-up and core-valence ionized states are investigated. In the cases where the processes involve simultaneous emission of two electrons, the distributions of the energy sharing are presented, emphasizing either the knock-out or shake-off mechanism.

  11. Measurements of radionuclide activity by the (e-α, β, γ, Lx) coincidence method using electrons with energies of a few eV emitted from radionuclides

    International Nuclear Information System (INIS)

    Frolov, E.A.

    1994-01-01

    A study was made of the possibility of measuring radionuclide activities by the method of coincidence of electrons with energies of a few eV emitted from the valence shells of radioactive atoms with nuclear radiations. The low energy electrons were detected with a detector equipped with microchannel plates with trochoidal focusing of an original design. Photons were detected with NaI(TI) detectors. A 100 μm thick plastic scintillator was used to detect beta- and alpha-particles. The investigation shows that it is possible to use this method for accurate measurements of radionuclide activity. (orig.)

  12. Double photoionization of propylene oxide: A coincidence study of the ejection of a pair of valence-shell electrons

    Science.gov (United States)

    Falcinelli, Stefano; Vecchiocattivi, Franco; Alagia, Michele; Schio, Luca; Richter, Robert; Stranges, Stefano; Catone, Daniele; Arruda, Manuela S.; Mendes, Luiz A. V.; Palazzetti, Federico; Aquilanti, Vincenzo; Pirani, Fernando

    2018-03-01

    Propylene oxide, a favorite target of experimental and theoretical studies of circular dichroism, was recently discovered in interstellar space, further amplifying the attention to its role in the current debate on protobiological homochirality. In the present work, a photoelectron-photoion-photoion coincidence technique, using an ion-imaging detector and tunable synchrotron radiation in the 18.0-37.0 eV energy range, permits us (i) to observe six double ionization fragmentation channels, their relative yields being accounted for about two-thirds by the couple (C2H4+, CH2O+) and one-fifth by (C2H3+, CH3O+); (ii) to measure thresholds for their openings as a function of photon energy; and (iii) to unravel a pronounced bimodality for a kinetic-energy-released distribution, fingerprint of competitive non-adiabatic mechanisms.

  13. VUV photoionization of acetamide studied by electron/ion coincidence spectroscopy in the 8–24 eV photon energy range

    International Nuclear Information System (INIS)

    Schwell, Martin; Bénilan, Yves; Fray, Nicolas; Gazeau, Marie-Claire; Es-Sebbar, Et.; Garcia, Gustavo A.; Nahon, Laurent; Champion, Norbert; Leach, Sydney

    2012-01-01

    Highlights: ► We study the VUV photoionization of acetamide in the 8–24 eV photon energy range. ► Electron/ion coincidence measurements are performed using synchrotron radiation. ► The adiabatic ionization energy of acetamide is determined by TPEPICO measurements. ► VUV induced fragmentation pathways of acetamide are assigned and discussed. - Abstract: A VUV photoionization study of acetamide was carried out over the 8–24 eV photon energy range using synchrotron radiation and photoelectron/photoion coincidence (PEPICO) spectroscopy. Threshold photoelectron photoion coincidence (TPEPICO) measurements were also made. Photoion yield curves and branching ratios were measured for the parent ion and six fragment ions. The adiabatic ionization energy of acetamide was determined as I.E. (1 2 A′) = (9.71 ± 0.02) eV, in agreement with an earlier reported photoionization mass spectrometry (PIMS) value. The adiabatic energy of the first excited state of the ion, 1 2 A″, was determined to be ≈10.1 eV. Assignments of the fragment ions and the pathways of their formation by dissociative photoionization were made. The neutral species lost in the principal dissociative photoionization processes are CH 3 , NH 2 , NH 3 , CO, HCCO and NH 2 CO. Heats of formation are derived for all ions detected and are compared with literature values. Some astrophysical implications of these results are discussed.

  14. Surface-site-selective study of valence electronic states of a clean Si(111)-7x7 surface using Si L23VV Auger electron and Si 2p photoelectron coincidence measurements

    International Nuclear Information System (INIS)

    Kakiuchi, Takuhiro; Tahara, Masashi; Nagaoka, Shin-ichi; Hashimoto, Shogo; Fujita, Narihiko; Tanaka, Masatoshi; Mase, Kazuhiko

    2011-01-01

    Valence electronic states of a clean Si(111)-7x7 surface are investigated in a surface-site-selective way using high-resolution coincidence measurements of Si pVV Auger electrons and Si 2p photoelectrons. The Si L 23 VV Auger electron spectra measured in coincidence with energy-selected Si 2p photoelectrons show that the valence band at the highest density of states in the vicinity of the rest atoms is shifted by ∼0.95 eV toward the Fermi level (E F ) relative to that in the vicinity of the pedestal atoms (atoms directly bonded to the adatoms). The valence-band maximum in the vicinity of the rest atoms, on the other hand, is shown to be shifted by ∼0.53 eV toward E F relative to that in the vicinity of the pedestal atoms. The Si 2p photoelectron spectra of Si(111)-7x7 measured in coincidence with energy-selected Si L 23 VV Auger electrons identify the topmost surface components, and suggest that the dimers and the rest atoms are negatively charged while the pedestal atoms are positively charged. Furthermore, the Si 2p-Si L 23 VV photoelectron Auger coincidence spectroscopy directly verifies that the adatom Si 2p component (usually denoted by C 3 ) is correlated with the surface state just below E F (usually denoted by S 1 ), as has been observed in previous angle-resolved photoelectron spectroscopy studies.

  15. Reflection-time-of-flight spectrometer for two-electron (e,2e) coincidence spectroscopy on surfaces

    International Nuclear Information System (INIS)

    Kirschner, J.; Kerherve, G.; Winkler, C.

    2008-01-01

    In this article, a novel time-of-flight spectrometer for two-electron-emission (e,2e/γ,2e) correlation spectroscopy from surfaces at low electron energies is presented. The spectrometer consists of electron optics that collect emitted electrons over a solid angle of approximately 1 sr and focus them onto a multichannel plate using a reflection technique. The flight time of an electron with kinetic energy of E kin ≅25 eV is around 100 ns. The corresponding time- and energy resolution are typically ≅1 ns and ≅0.65 eV, respectively. The first (e,2e) data obtained with the present setup from a LiF film are presented

  16. Size effects in van der Waals clusters studied by spin and angle-resolved electron spectroscopy and multi-coincidence ion imaging

    International Nuclear Information System (INIS)

    Rolles, D; Pesic, Z D; Zhang, H; Bilodeau, R C; Bozek, J D; Berrah, N

    2007-01-01

    We have studied the valence and inner-shell photoionization of free rare-gas clusters by means of angle and spin resolved photoelectron spectroscopy and momentum resolving electron-multi-ion coincidence spectroscopy. The electron measurements probe the evolution of the photoelectron angular distribution and spin polarization parameters as a function of photon energy and cluster size, and reveal a strong cluster size dependence of the photoelectron angular distributions in certain photon energy regions. In contrast, the spin polarization parameter of the cluster photoelectrons is found to be very close to the atomic value for all covered photon energies and cluster sizes. The ion imaging measurements, which probe the fragmentation dynamics of multiply charged van der Waals clusters, also exhibit a pronounced cluster size dependence

  17. Effect of relaxation and decay of a charge transfer shakeup satellite on Auger-electron spectroscopy spectra and Auger-photoelectron coincidence spectroscopy spectra of adsorbates

    International Nuclear Information System (INIS)

    Ohno, Masahide

    2008-01-01

    An electron excited to an unoccupied part of adsorbate-substrate hybrid states in a chemisorbed molecule by a resonant core electron excitation or charge transfer (CT) shakeup may delocalize on time scale of core-hole decay so that the excited core-hole state relaxes partly or completely to a fully relaxed one. The Auger decay of the fully relaxed core-hole state via the relaxation of the excited one introduces an additional feature in the resonant Auger-electron spectroscopy (RAES) spectrum and the AES spectrum. However, the additional feature in the RAES spectrum is a normal AES spectrum by decay of the fully relaxed core-hole state, whereas the one in the AES spectrum is the AES spectrum by decay of the fully relaxed core-hole state broadened by the photoelectron spectroscopy (PES) CT shakeup satellite weighted by the branching ratio of the relaxation width. The discrepancies between the AES spectrum measured at high above the ionization threshold and the additional feature in the RAES spectrum consist of the symmetric-like part by the decay of the fully relaxed core-hole state via the relaxation of the CT shakeup state and the asymmetric part by the direct decay of the shakeup states. The asymmetric part increases with a decrease in the hybridization strength. This explains the variation with the hybridization strength in the discrepancies between the RAES spectra and the AES spectra of chemisorbed molecules such as CO/Ni, CO/Cu and CO/Ag. A comparison of the singles PES spectrum with the one measured in coincidence with the AES main line of a selected kinetic energy (KE) provides the delocalization rate of the excited electron in the CT shakeup state as a function of photoelectron KE. The coincidence measurement to obtain the partial singles PES spectrum is discussed

  18. Channel coincidence counter: version 1

    International Nuclear Information System (INIS)

    Krick, M.S.; Menlove, H.O.

    1980-06-01

    A thermal neutron coincidence counter has been designed for the assay of fast critical assembly fuel drawers and plutonium-bearing fuel rods. The principal feature of the detector is a 7-cm by 7-cm by 97-cm detector channel, which provides a uniform neutron detection efficiency of 16% along the central 40 cm of the channel. The electronics system is identical to that used for the High-Level Neutron Coincidence Counter

  19. 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.

  20. 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.

  1. Comparison of the target-thickness dependence of the convoy electron yield and the Rydberg electron yield measured in coincidence with exit charge states in fast ion-solid collisions

    International Nuclear Information System (INIS)

    Gaither, C.C. III; Breinig, M.; Freyou, J.; Underwood, T.A.

    1988-01-01

    We have simultaneously measured the yield of convoy electrons and the yield of electrons in high Rydberg states of the projectile (n /approx gt/ 70), produced by 2MeV/u C projectiles passing through C foils, whose thicknesses range from 4--10 ug/cm 2 , for incident charge states q/sub i/ = 4--6 and exit charge states q/sub e/ = 4--6. We have found that these yields exhibit similar trends as a function of foil thickness, but that, nevertheless, the ratio of the number of convoy electrons detected in coincidence with ions of exit charge state q/sub e/ to the number of electrons detected in high Rydberg states of ions with the same exit charge state is a function of foil thickness. This may be due to a broadening of the convoy electron energy spectrum with increasing foil thickness. 6 refs., 3 figs

  2. SU-F-T-486: A Simple Approach to Performing Light Versus Radiation Field Coincidence Quality Assurance Using An Electronic Portal Imaging Device (EPID)

    Energy Technology Data Exchange (ETDEWEB)

    Herchko, S; Ding, G [Vanderbilt University, Nashville, TN (United States)

    2016-06-15

    Purpose: To develop an accurate, straightforward, and user-independent method for performing light versus radiation field coincidence quality assurance utilizing EPID images, a simple phantom made of readily-accessible materials, and a free software program. Methods: A simple phantom consisting of a blocking tray, graph paper, and high-density wire was constructed. The phantom was used to accurately set the size of a desired light field and imaged on the electronic portal imaging device (EPID). A macro written for use in ImageJ, a free image processing software, was then use to determine the radiation field size utilizing the high density wires on the phantom for a pixel to distance calibration. The macro also performs an analysis on the measured radiation field utilizing the tolerances recommended in the AAPM Task Group #142. To verify the accuracy of this method, radiochromic film was used to qualitatively demonstrate agreement between the film and EPID results, and an additional ImageJ macro was used to quantitatively compare the radiation field sizes measured both with the EPID and film images. Results: The results of this technique were benchmarked against film measurements, which have been the gold standard for testing light versus radiation field coincidence. The agreement between this method and film measurements were within 0.5 mm. Conclusion: Due to the operator dependency associated with tracing light fields and measuring radiation fields by hand when using film, this method allows for a more accurate comparison between the light and radiation fields with minimal operator dependency. Removing the need for radiographic or radiochromic film also eliminates a reoccurring cost and increases procedural efficiency.

  3. SU-F-T-486: A Simple Approach to Performing Light Versus Radiation Field Coincidence Quality Assurance Using An Electronic Portal Imaging Device (EPID)

    International Nuclear Information System (INIS)

    Herchko, S; Ding, G

    2016-01-01

    Purpose: To develop an accurate, straightforward, and user-independent method for performing light versus radiation field coincidence quality assurance utilizing EPID images, a simple phantom made of readily-accessible materials, and a free software program. Methods: A simple phantom consisting of a blocking tray, graph paper, and high-density wire was constructed. The phantom was used to accurately set the size of a desired light field and imaged on the electronic portal imaging device (EPID). A macro written for use in ImageJ, a free image processing software, was then use to determine the radiation field size utilizing the high density wires on the phantom for a pixel to distance calibration. The macro also performs an analysis on the measured radiation field utilizing the tolerances recommended in the AAPM Task Group #142. To verify the accuracy of this method, radiochromic film was used to qualitatively demonstrate agreement between the film and EPID results, and an additional ImageJ macro was used to quantitatively compare the radiation field sizes measured both with the EPID and film images. Results: The results of this technique were benchmarked against film measurements, which have been the gold standard for testing light versus radiation field coincidence. The agreement between this method and film measurements were within 0.5 mm. Conclusion: Due to the operator dependency associated with tracing light fields and measuring radiation fields by hand when using film, this method allows for a more accurate comparison between the light and radiation fields with minimal operator dependency. Removing the need for radiographic or radiochromic film also eliminates a reoccurring cost and increases procedural efficiency.

  4. Detector for imaging and dosimetry of laser-driven epithermal neutrons by alpha conversion

    Science.gov (United States)

    Mirfayzi, S. R.; Alejo, A.; Ahmed, H.; Wilson, L. A.; Ansell, S.; Armstrong, C.; Butler, N. M. H.; Clarke, R. J.; Higginson, A.; Notley, M.; Raspino, D.; Rusby, D. R.; Borghesi, M.; Rhodes, N. J.; McKenna, P.; Neely, D.; Brenner, C. M.; Kar, S.

    2016-10-01

    An epithermal neutron imager based on detecting alpha particles created via boron neutron capture mechanism is discussed. The diagnostic mainly consists of a mm thick Boron Nitride (BN) sheet (as an alpha converter) in contact with a non-borated cellulose nitride film (LR115 type-II) detector. While the BN absorbs the neutrons in the thermal and epithermal ranges, the fast neutrons register insignificantly on the detector due to their low neutron capture and recoil cross-sections. The use of solid-state nuclear track detectors (SSNTD), unlike image plates, micro-channel plates and scintillators, provide safeguard from the x-rays, gamma-rays and electrons. The diagnostic was tested on a proof-of-principle basis, in front of a laser driven source of moderated neutrons, which suggests the potential of using this diagnostic (BN+SSNTD) for dosimetry and imaging applications.

  5. Coincident detection of electrons ejected at large angles and target recoil ions produced in multiply ionizing collisions for the 1-MeV/u Oq++Ar collision system

    International Nuclear Information System (INIS)

    Gaither III, C.C.; Breinig, M.; Berryman, J.W.; Hasson, B.F.; Richards, J.D.; Price, K.

    1993-01-01

    The angular distributions of energetic electrons ejected at angles between 45 degree and 135 degree with respect to the incident-beam direction have been measured in coincidence with the charge states of the target recoil ions produced in multiply ionizing collisions for the 1-MeV/u O q+ (q=4,7)+Ar collision systems. These measurements have been made for ∼179-, ∼345-, and ∼505-eV electrons. Additionally, the energy distributions of electrons ejected into specific angular regions have been measured. Ar LMM satellite Auger electrons appear as a peak in the energy spectrum of electrons ejected at all large angles. The center of this peak is found at an electron energy of ∼179 eV. Electrons with ∼179 eV energy, ejected at large angles, are preferentially produced in coincidence with recoil ions of charge state 4+. Electrons with ∼345 eV energy and ∼505 eV energy ejected at large angles are preferentially produced in coincidence with recoil ions of charge state 3+. The angular distributions for these electrons are strongly peaked in the forward direction; essentially no electrons are observed at angles larger than 90 degree. These results are consistent with the dominant production mechanism for energetic electrons ejected at large angles being a binary-encounter process. Differential cross sections have been calculated from these angular distributions. They are on the order of 10 -21 cm 2 /(eV sr)

  6. Surface-site-selective study of valence electronic structures of clean Si(100)-2x1 using Si-L23VV Auger electron-Si-2p photoelectron coincidence spectroscopy

    International Nuclear Information System (INIS)

    Kakiuchi, Takuhiro; Nagaoka, Shinichi; Hashimoto, Shogo; Fujita, Narihiko; Tanaka, Masatoshi; Mase, Kazuhiko

    2010-01-01

    Valence electronic structures of a clean Si(100)-2x1 surface are investigated in a surface-site-selective way using Si-L 23 VV Auger electron-Si-2p photoelectron coincidence spectroscopy. The Si-L 23 VV Auger electron spectra measured in coincidence with Si-2p photoelectrons emitted from the Si up-atoms or Si 2nd-layer of Si(100)-2x1 suggest that the position where the highest density of valence electronic states located in the vicinity of the Si up-atoms is shifted by 0.8 eV towards lower binding energy relative to that in the vicinity of the Si 2nd-layer. Furthermore, the valence band maximum in the vicinity of the Si up-atoms is indicated to be shifted by 0.1 eV towards lower binding energy relative to that in the vicinity of the Si 2nd-layer. These results are direct evidence of the transfer of negative charge from the Si 2nd-layer to the Si up-atoms. (author)

  7. Optical simulations for the S3 project - Super separator spectrometer - gamma-electron coincidence spectroscopy of a transfermium nucleus: the 251Md101

    International Nuclear Information System (INIS)

    Dechery, Fabien

    2012-01-01

    In analogy with the atomic closed shells giving rise to the stability and high ionisation energies of noble gases, nuclear physics also has its magic numbers of protons and neutrons which enhance nuclear structure stability. Knowledge of the structure of doubly-magic nuclei, both proton and neutron numbers, is crucial to parameterize theoretical models. The discovery of the next and ultimate magic numbers will provide a strong constraint on the many predictions. These two numbers are like the centre coordinates of an area of enhanced stability of the nuclear chart, well known as 'island of stability'. These superheavy nuclei only exist due to pure quantum shell effects. My thesis work deals with two distinct, but complementary, aspects of fundamental physics with the common goal of studying these extreme mass nuclei structure. The first part corresponds to the development of a next generation instrument for nuclear physics to allow synthesis and spectroscopy studies of superheavy nuclei: the Super Separator Spectrometer S 3 . This project will be installed at SPIRAL2 (GANIL) and has been approved by the French Research National Agency (ANR) within the EQUIPEX framework. It has been designed to take advantage of the high intensity heavy ion beam from the LINAC, giving access to a wide range of physical programs. The second part corresponds to the preparation, realisation and analysis of an experiment on 251-Mendelevium in which the very first prompt gamma-electron coincidence spectroscopy was performed for a transfermium nuclei. (author) [fr

  8. Electric giant resonances in sup 4 sup 0 Ca and sup 4 sup 8 Ca probed with electron and proton scattering coincidence experiments

    CERN Document Server

    Strauch, S

    1999-01-01

    Excitation and particle decay of electric giant resonances in sup 4 sup 0 Ca and sup 4 sup 8 Ca are studied with electron and proton beams. Recent results of a sup 4 sup 8 Ca(e,e'n) measurement performed at the S-DALINAC in Darmstadt with kinematics that selectively populate electric monopole, dipole and quadrupole excitations are presented. The extracted B(E1) strength distribution is in good agreement with photo nuclear data and the predictions of microscopic calculations. The summed B(E2+E0) strength distribution, however disagrees with the result of these calculations. The neutron emission of the giant dipole resonance in sup 4 sup 8 Ca shows a large fraction of direct decay to sup 4 sup 7 Ca hole states. In addition, isoscalar giant monopole resonance strength in sup 4 sup 0 Ca was extracted from (e,e'alpha sub 0) and (e,e'alpha sub 1) angular correlations. A study of the quadrupole strength in the alpha sub 0 decay channel of sup 4 sup 0 Ca with a (p,p'alpha) coincidence measurement reiterates the unsol...

  9. Many-body effect in the resonant Ti L23-M23V Auger-electron spectroscopy spectra and Auger-photoelectron coincidence spectroscopy spectra of Ti oxides

    International Nuclear Information System (INIS)

    Ohno, Masahide

    2007-01-01

    Recently Danger et al. [J. Danger, H. Magnan, D. Chandesris, P. Le Fevre, S. Bourgeois, J. Jupille, A. Verdini, R. Gotter, A. Morgante, Phys. Rev. B 64 (2001) 045110] and Le Fevre et al. [P. Le Fevre, J. Danger, H. Magnan, D. Chandesris, J. Jupille, S. Bourgeois, M.-A. Arrio, R. Gotter, A. Verdini, A. Morgante, Phys. Rev. B 69 (2004) 155421] showed the absence of resonant Raman scattering feature in the Ti L 23 -M 23 V resonant Auger-electron spectroscopy (RAES) spectra of Ti oxides measured across the Ti 2p edges. They attributed the absence to the covalent character of the Ti-O bond which allows an effective delocalization of 3d electrons. It is shown by a many-body theory that when the time scale of relaxation of the resonantly excited core-hole state to the fully relaxed core-hole state is much shorter than that of core-hole decay, any sizeable Raman scattering is absent in the RAES spectra measured across the Ti 2p edges. The relaxation width depends on the hybridization strength and the charge transfer (CT) energy between the two states. The L 2 -L 3 V Coster-Kronig (CK) decay widths of TiO 2 and TiO 2-x are determined from the L 23 -M 23 V Auger-photoelectron coincidence spectroscopy (APECS) spectra reported in the aforementioned papers. They are about 0.18 and 0.35 eV, respectively. The CK-decay width in the reduced Ti oxide increases compared to that of TiO 2 in rutile because of filling of the 3d states just below the Fermi level in the former

  10. Integrated coincidence circuits

    International Nuclear Information System (INIS)

    Borejko, V.F.; Grebenyuk, V.M.; Zinov, V.G.

    1976-01-01

    The description is given of two coincidence units employing integral circuits in the VISHNYA standard. The units are distinguished for the coincidence selection element which is essentially a combination of a tunnel diode and microcircuits. The output fast response of the units is at least 90 MHz in the mode of the output signal unshaped in duration and 50 MHz minimum in the mode of the output signal shaping. The resolution time of the units is dependent upon the duration of input signals

  11. Coincidence studies with antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    McGovern, M; Walters, H R J [Department of Applied Mathematics and Theoretical Physics, Queen' s University, Belfast BT7 1NN (United Kingdom); Assafrao, D; Mohallem, J R [Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, P.O Box 702, 30123-970 Belo Horizonte, MG (Brazil); Whelan, Colm T, E-mail: mmcgovern06@qub.ac.u [Department of Physics, Old Dominion University, Norfolk, VA 23529-0116 (United States)

    2010-02-01

    We present a short overview of a new method for calculating fully differential cross sections that is able to describe any aspect of coincidence measurements involving heavy projectiles. The method is based upon impact parameter close coupling with pseudostates. Examples from antiproton impact ionization are shown.

  12. Experiments using coincidence methods

    International Nuclear Information System (INIS)

    Anwar Dhani.

    1978-01-01

    Experiments on γ spectroscopy using the simple coincidence techniques, including investigation of angular distribution of γ radiation from annihilation process in decay of Na 22 , γ - γ angular correlation technique in decay of Co 60 , decay scheme study of Bi 207 and life time measurement of nuclear Pb 207 excited state have been carried out. (author)

  13. A β - γ coincidence

    International Nuclear Information System (INIS)

    Agullo, F.

    1960-01-01

    A β - γ coincidence method for absolute counting is given. The fundamental principles are revised and the experimental part is detailed. The results from 1 98 Au irradiated in the JEN 1 Swimming pool reactor are given. The maximal accuracy is 1 per cent. (Author) 11 refs

  14. VUV photoionization of acetamide studied by electron/ion coincidence spectroscopy in the 8-24 eV photon energy range

    KAUST Repository

    Schwell, Martin; Bé nilan, Yves; Fray, Nicolas; Gazeau, Marie Claire; Es-sebbar, Et-touhami; Garcí a, Gustavo A.; Nahon, Laurent; Champion, Norbert; Leach, Sydney Sydney

    2012-01-01

    A VUV photoionization study of acetamide was carried out over the 8-24 eV photon energy range using synchrotron radiation and photoelectron/photoion coincidence (PEPICO) spectroscopy. Threshold photoelectron photoion coincidence (TPEPICO) measurements were also made. Photoion yield curves and branching ratios were measured for the parent ion and six fragment ions. The adiabatic ionization energy of acetamide was determined as I.E. (1 2A′) = (9.71 ± 0.02) eV, in agreement with an earlier reported photoionization mass spectrometry (PIMS) value. The adiabatic energy of the first excited state of the ion, 1 2A″, was determined to be ≈10.1 eV. Assignments of the fragment ions and the pathways of their formation by dissociative photoionization were made. The neutral species lost in the principal dissociative photoionization processes are CH 3, NH 2, NH 3, CO, HCCO and NH 2CO. Heats of formation are derived for all ions detected and are compared with literature values. Some astrophysical implications of these results are discussed. © 2011 Elsevier B.V. All rights reserved.

  15. Digital coincidence counting

    International Nuclear Information System (INIS)

    Buckman, S.M.; Ius, D.

    1996-01-01

    This paper reports on the development of a digital coincidence-counting system which comprises a custom-built data acquisition card and associated PC software. The system has been designed to digitise the pulse-trains from two radiation detectors at a rate of 20 MSamples/s with 12-bit resolution. Through hardware compression of the data, the system can continuously record both individual pulse-shapes and the time intervals between pulses. Software-based circuits are used to process the stored pulse trains. These circuits are constructed simply by linking together icons representing various components such as coincidence mixers, time delays, single-channel analysers, deadtimes and scalers. This system enables a pair of pulse trains to be processed repeatedly using any number of different methods. Some preliminary results are presented in order to demonstrate the versatility and efficiency of this new method. (orig.)

  16. Digital coincidence counting

    Science.gov (United States)

    Buckman, S. M.; Ius, D.

    1996-02-01

    This paper reports on the development of a digital coincidence-counting system which comprises a custom-built data acquisition card and associated PC software. The system has been designed to digitise the pulse-trains from two radiation detectors at a rate of 20 MSamples/s with 12-bit resolution. Through hardware compression of the data, the system can continuously record both individual pulse-shapes and the time intervals between pulses. Software-based circuits are used to process the stored pulse trains. These circuits are constructed simply by linking together icons representing various components such as coincidence mixers, time delays, single-channel analysers, deadtimes and scalers. This system enables a pair of pulse trains to be processed repeatedly using any number of different methods. Some preliminary results are presented in order to demonstrate the versatility and efficiency of this new method.

  17. A magnetic-lens - mini-orange coincidence spectrometer

    International Nuclear Information System (INIS)

    Bargholtz, C.; Holmberg, L.; Ruus, N.; Tegner, P.E.; Weiss, G.

    1997-04-01

    A coincidence spectrometer consisting of a Gerholm type magnetic lens and a permanent magnet mini-orange spectrometer is described. Electron-electron or electron-positron coincidences may be registered in various angular settings. The spectrometer has been developed mainly to search for anomalous contributions to Bhabha scattering or positrons and is at present used for such studies. 6 refs

  18. Prospects in coincidence experiments

    International Nuclear Information System (INIS)

    Laget, J.M.

    1984-01-01

    The sensitivity of virtual photons to the local variations of the charge and magnetization densities is exploited to study the short-range part of the nucleon-nucleon interaction inside the nucleus. The possibility of varying energy, squared mass and longitudinal polarization of the photons independently enables us to disentangle the mechanisms related to the internal structure of the nucleon (e.g. quark interchange) and the contribution due to meson exchange. Coincidence experiments of the type (e,e'N) and (e,e'NN) are performed to suppress the meson contribution to the longitudinal part of the quasi-elastic peak. Four typical examples of coincidence experiments induced by virtual photons are discussed: experiments (1) on the spectroscopic structure of the quasi-elastic peak and the problem of deep lying hole states; (2) on the structure of the continuum; (3) on the low energy side of the quasi-elastic peak; and finally a three-arm coincidence experiment. (Auth.)

  19. Coincident ion acceleration and electron extraction for space propulsion using the self-bias formed on a set of RF biased grids bounding a plasma source

    International Nuclear Information System (INIS)

    Rafalskyi, D; Aanesland, A

    2014-01-01

    We propose an alternative method to accelerate ions in classical gridded ion thrusters and ion sources such that co-extracted electrons from the source may provide beam space charge neutralization. In this way there is no need for an additional electron neutralizer. The method consists of applying RF voltage to a two-grid acceleration system via a blocking capacitor. Due to the unequal effective area of the two grids in contact with the plasma, a dc self-bias is formed, rectifying the applied RF voltage. As a result, ions are continuously accelerated within the grid system while electrons are emitted in brief instants within the RF period when the RF space charge sheath collapses. This paper presents the first experimental results and a proof-of-principle. Experiments are carried out using the Neptune thruster prototype which is a gridded Inductively Coupled Plasma (ICP) source operated at 4 MHz, attached to a larger beam propagation chamber. The RF power supply is used both for the ICP discharge (plasma generation) and powering the acceleration grids via a capacitor for ion acceleration and electron extraction without any dc power supplies. The ion and electron energies, particle flux and densities are measured using retarding field energy analyzers (RFEA), Langmuir probes and a large beam target. The system operates in Argon and N 2 . The dc self-bias is found to be generated within the gridded extraction system in all the range of operating conditions. Broad quasi-neutral ion-electron beams are measured in the downstream chamber with energies up to 400 eV. The beams from the RF acceleration method are compared with classical dc acceleration with an additional external electron neutralizer. It is found that the two acceleration techniques provide similar performance, but the ion energy distribution function from RF acceleration is broader, while the floating potential of the beam is lower than for the dc accelerated beam. (paper)

  20. Initiation of electron transport chain activity in the embryonic heart coincides with the activation of mitochondrial complex 1 and the formation of supercomplexes.

    Science.gov (United States)

    Beutner, Gisela; Eliseev, Roman A; Porter, George A

    2014-01-01

    Mitochondria provide energy in form of ATP in eukaryotic cells. However, it is not known when, during embryonic cardiac development, mitochondria become able to fulfill this function. To assess this, we measured mitochondrial oxygen consumption and the activity of the complexes (Cx) 1 and 2 of the electron transport chain (ETC) and used immunoprecipitation to follow the generation of mitochondrial supercomplexes. We show that in the heart of mouse embryos at embryonic day (E) 9.5, mitochondrial ETC activity and oxidative phosphorylation (OXPHOS) are not coupled, even though the complexes are present. We show that Cx-1 of the ETC is able to accept electrons from the Krebs cycle, but enzyme assays that specifically measure electron flow to ubiquinone or Cx-3 show no activity at this early embryonic stage. At E11.5, mitochondria appear functionally more mature; ETC activity and OXPHOS are coupled and respond to ETC inhibitors. In addition, the assembly of highly efficient respiratory supercomplexes containing Cx-1, -3, and -4, ubiquinone, and cytochrome c begins at E11.5, the exact time when Cx-1 becomes functional activated. At E13.5, ETC activity and OXPHOS of embryonic heart mitochondria are indistinguishable from adult mitochondria. In summary, our data suggest that between E9.5 and E11.5 dramatic changes occur in the mitochondria of the embryonic heart, which result in an increase in OXPHOS due to the activation of complex 1 and the formation of supercomplexes.

  1. Triple-coincidence with automatic chance coincidence correction

    International Nuclear Information System (INIS)

    Chase, R.L.

    1975-05-01

    The chance coincidences in a triple-coincidence circuit are of two types--partially correlated and entirely uncorrelated. Their relative importance depends on source strength and source and detector geometry so that the total chance correction cannot, in general, be calculated. The system described makes use of several delays and straightforward integrated circuit logic to provide independent evaluation of the two components of the chance coincidence rate. (auth)

  2. Coincident photoelectron spectroscopy on superconductors

    International Nuclear Information System (INIS)

    Voss, Stefan

    2011-01-01

    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 2 Sr 2 CaCu 2 O 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.

  3. 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...

  4. Coincidence counting corrections for dead time losses and accidental coincidences

    International Nuclear Information System (INIS)

    Wyllie, H.A.

    1987-04-01

    An equation is derived for the calculation of the radioactivity of a source from the results of coincidence counting taking into account the dead-time losses and accidental coincidences. The derivation is an extension of the method of J. Bryant [Int. J. Appl. Radiat. Isot., 14:143, 1963]. The improvement on Bryant's formula has been verified by experiment

  5. A portable neutron coincidence counter

    Energy Technology Data Exchange (ETDEWEB)

    Peurrung, A.J.; Bowyer, S.M.; Craig, R.A.; Dudder, G.B.; Knopf, M.A.; Panisko, M.E.; Reeder, P.L.; Stromswold, D.C.; Sunberg, D.S.

    1996-11-01

    Pacific Northwest National Laboratory has designed and constructed a prototype portable neutron coincidence counter intended for use in a variety of applications, such as the verification and inspection of weapons components, safety measurements for novel and challenging situations, portable portal deployment to prevent the transportation of fissile materials, uranium enrichment measurements in hard-to-reach locations, waste assays for objects that cannot be measured by existing measurement systems, and decontamination and decommissioning. The counting system weighs less than 40 kg and is composed of parts each weighing no more than 5 kg. In addition, the counter`s design is sufficiently flexible to allow rapid, reliable assembly around containers of nearly arbitrary size and shape. The counter is able to discern the presence of 1 kg of weapons-grade plutonium within an ALR-8 (30-gal drum) in roughly 100 seconds and 10 g in roughly 1000 seconds. The counter`s electronics are also designed for maximum adaptability, allowing operation under a wide variety of circumstances, including exposure to gamma-ray fields of 1 R/h. This report provides a detailed review of the design and construction process. Finally, preliminary experimental measurements that confirm the performance capabilities of this counter are discussed. 6 refs., 18 figs., 3 tabs.

  6. Multiverse understanding of cosmological coincidences

    International Nuclear Information System (INIS)

    Bousso, Raphael; Hall, Lawrence J.; Nomura, Yasunori

    2009-01-01

    There is a deep cosmological mystery: although dependent on very different underlying physics, the time scales of structure formation, of galaxy cooling (both radiatively and against the CMB), and of vacuum domination do not differ by many orders of magnitude, but are all comparable to the present age of the universe. By scanning four landscape parameters simultaneously, we show that this quadruple coincidence is resolved. We assume only that the statistical distribution of parameter values in the multiverse grows towards certain catastrophic boundaries we identify, across which there are drastic regime changes. We find order-of-magnitude predictions for the cosmological constant, the primordial density contrast, the temperature at matter-radiation equality, the typical galaxy mass, and the age of the universe, in terms of the fine structure constant and the electron, proton and Planck masses. Our approach permits a systematic evaluation of measure proposals; with the causal patch measure, we find no runaway of the primordial density contrast and the cosmological constant to large values.

  7. Coincidence measurements of FFTF breeder fuel subassemblies

    International Nuclear Information System (INIS)

    Eccleston, G.W.; Foley, J.E.; Krick, M.; Menlove, H.O.; Goris, P.; Ramalho, A.

    1984-04-01

    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 240 Pu-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 241 Am 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 240 Pu-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

  8. 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...

  9. Coincidence logic modules for criticality alarming

    International Nuclear Information System (INIS)

    Schaief, C.C. III.

    1977-04-01

    A coincidence Logic Module and a companion contact closure Relay Module utilizing the NIM Standard have been developed for criticality alarming. The units provide an ALARM whenever two or more out of N detectors become activated. In addition, an ALERT is generated whenever one or more detectors is activated or when certain electronic component failures occur. The number of detector inputs (N) can be expanded in groups of six by adding modules. Serial and parallel redundancy were used to reduce the probability of system failure

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

    International Nuclear Information System (INIS)

    Bourva, L.C.A.; Croft, S.

    1999-01-01

    The general purpose neutron-photon-electron Monte Carlo N-Particle code, MCNP TM , 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 a new evaluation technique for the estimation of gate utilisation factors. It uses the die-away profile of a neutron coincidence chamber generated either by MCNP TM , or by other means, to simulate the neutron detection arrival time pattern originating from independent spontaneous fission events. A shift register simulation algorithm, embedded in the MCF code, then calculates the coincidence counts scored within the electronics gate. The gate utilisation factor is then deduced by dividing the coincidence counts obtained with that obtained in the same Monte Carlo run, but for an ideal detection system with a coincidence gate utilisation factor equal to unity. The MCF code has been benchmarked against analytical results calculated for both single and double exponential die-away profiles. These results are presented along with the development of the closed form algebraic expressions for the two cases. Results of this validity check showed very good agreement. On this

  11. 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.

  12. Computed neutron coincidence counting applied to passive waste assay

    International Nuclear Information System (INIS)

    Bruggeman, M.; Baeten, P.; De Boeck, W.; Carchon, R.

    1997-01-01

    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

  13. Multiple channel programmable coincidence counter

    Science.gov (United States)

    Arnone, Gaetano J.

    1990-01-01

    A programmable digital coincidence counter having multiple channels and featuring minimal dead time. Neutron detectors supply electrical pulses to a synchronizing circuit which in turn inputs derandomized pulses to an adding circuit. A random access memory circuit connected as a programmable length shift register receives and shifts the sum of the pulses, and outputs to a serializer. A counter is input by the adding circuit and downcounted by the seralizer, one pulse at a time. The decoded contents of the counter after each decrement is output to scalers.

  14. Numerical coincidences and 'tuning' in cosmology

    OpenAIRE

    Rees, Martin J.

    2004-01-01

    Fred Hoyle famously drew attention to the significance of apparent coincidences in the energy levels of the carbon and oxygen nucleus. This paper addresses the possible implications of other coincidences in cosmology.

  15. IMPECC, new 4 π β γ coincidence system

    International Nuclear Information System (INIS)

    Bouchard, J.; Chauvenet, B.; Vatin, R.

    1988-05-01

    The new 4 π β γ coincidence system IMPECC which uses an extensible dead time circuit common to both channels is described. Correction formulae which take into account the particularities of the electronics are also presented. The use of two ADC's and the symmetry in the two channels gives us a very powerful instrument when measuring complex decay scheme radionuclides [fr

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

    International Nuclear Information System (INIS)

    Menlove, H.O.

    1983-01-01

    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

  17. 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.

  18. Photoion spectroscopy of atoms using coincidence techniques

    International Nuclear Information System (INIS)

    Hayaishi, Tatsuji

    1990-01-01

    Interaction of atoms or molecules with photons causes many effects which are often obscured because of many decay paths from the event. To pick up an effect in the mixed-up ones, it is necessary to observe the decay path arising the effect alone. There is a coincidence technique in one of experimental means for the purpose of observing the decay path. In this article, two coincidence measurements are presented; a photoelectron-photoion coincidence technique and a threshold photoelectron-photoion coincidence technique. Furthermore, experimental facts of rare gases atoms obtained by the techniques are reviewed. (author)

  19. Quantifying radionuclide signatures from a γ–γ coincidence system

    International Nuclear Information System (INIS)

    Britton, Richard; Jackson, Mark J.; Davies, Ashley V.

    2015-01-01

    A method for quantifying gamma coincidence signatures has been developed, and tested in conjunction with a high-efficiency multi-detector system to quickly identify trace amounts of radioactive material. The γ–γ system utilises fully digital electronics and list-mode acquisition to time–stamp each event, allowing coincidence matrices to be easily produced alongside typical ‘singles’ spectra. To quantify the coincidence signatures a software package has been developed to calculate efficiency and cascade summing corrected branching ratios. This utilises ENSDF records as an input, and can be fully automated, allowing the user to quickly and easily create/update a coincidence library that contains all possible γ and conversion electron cascades, associated cascade emission probabilities, and true-coincidence summing corrected γ cascade detection probabilities. It is also fully searchable by energy, nuclide, coincidence pair, γ multiplicity, cascade probability and half-life of the cascade. The probabilities calculated were tested using measurements performed on the γ–γ system, and found to provide accurate results for the nuclides investigated. Given the flexibility of the method, (it only relies on evaluated nuclear data, and accurate efficiency characterisations), the software can now be utilised for a variety of systems, quickly and easily calculating coincidence signature probabilities. - Highlights: • Monte-Carlo based software developed to easily create/update a coincidence signal library for environmental radionuclides. • Coincidence library utilised to accurately quantify gamma coincidence signatures. • All coincidence signature probabilities are corrected for cascade summing, conversion electron emission and pair production. • Key CTBTO relevant radionuclides have been tested to verify the calculated correction factors. • Accurately quantifying coincidence signals during routine analysis will allow dramatically improved detection

  20. Sensitivity to coincidences and paranormal belief.

    Science.gov (United States)

    Hadlaczky, Gergö; Westerlund, Joakim

    2011-12-01

    Often it is difficult to find a natural explanation as to why a surprising coincidence occurs. In attempting to find one, people may be inclined to accept paranormal explanations. The objective of this study was to investigate whether people with a lower threshold for being surprised by coincidences have a greater propensity to become believers compared to those with a higher threshold. Participants were exposed to artificial coincidences, which were formally defined as less or more probable, and were asked to provide remarkability ratings. Paranormal belief was measured by the Australian Sheep-Goat Scale. An analysis of the remarkability ratings revealed a significant interaction effect between Sheep-Goat score and type of coincidence, suggesting that people with lower thresholds of surprise, when experiencing coincidences, harbor higher paranormal belief than those with a higher threshold. The theoretical aspects of these findings were discussed.

  1. Statistical data filtration in neutron coincidence counting

    International Nuclear Information System (INIS)

    Beddingfield, D.H.; Menlove, H.O.

    1992-11-01

    We assessed the effectiveness of statistical data filtration to minimize the contribution of matrix materials in 200-ell drums to the nondestructive assay of plutonium. Those matrices were examined: polyethylene, concrete, aluminum, iron, cadmium, and lead. Statistical filtration of neutron coincidence data improved the low-end sensitivity of coincidence counters. Spurious data arising from electrical noise, matrix spallation, and geometric effects were smoothed in a predictable fashion by the statistical filter. The filter effectively lowers the minimum detectable mass limit that can be achieved for plutonium assay using passive neutron coincidence counting

  2. Coincident effect characteristic in a thermoacoustic regenerator

    International Nuclear Information System (INIS)

    Liu Yicai; Xin Tianlong; Huang Qian; Shi Xiangnan; Chen Siming; Chen Lixin

    2011-01-01

    Many previous studies on characteristics of thermoacoustic regenerator are based on fluid micro-groups and their compression-expansion cycle. In this paper, coincident frequency is introduced to evaluate its acoustic characteristics by combining structural acoustic with structural vibration theories. The relationship among structure wave radiation and regenerator position, slab thickness, and properties of material are analyzed by numerical calculation. The results show that in the low-frequency thermoacoustic system, the coincident effect generated by higher frequency wave weakens the fundamental sound wave. While in the high-frequency thermoacoustic system, where the oscillating fundamental frequency is higher than the coincident frequency, the sound field strength is enhanced by stronger structure wave radiation because of the coincident effect.

  3. A versatile fast coincidence system with memory

    International Nuclear Information System (INIS)

    Pouthas, J.

    1976-01-01

    A versatile fast coincidence system has been studied for experiments using several detectors. In this system, all the coincidence events are produced with an associated code, and thus, different kinds of events can be processed with the same experimental set-up. Also, the classification of the logical pulses gives the possibility of using a large number of ways (30 in this system). The setting of the system is very simple: there are only two time windows to adjust. (Auth.)

  4. Instrument limitation of accuracy of absolute measurement by method of 4π beta-gamma coincidence

    International Nuclear Information System (INIS)

    Plkh, J.

    1979-01-01

    Accuracy is discussed of determination of coincidence channels dead-time in 4π β-γ installation and determination of coincidence resolution time as well as conditions for determination and accuracy of these parameters. Conditions are considered under which these parameters have not been determined and there is wrong performance of the installation. Special attention was paid to the electronic circuit of the γ-channel. It has been shown that as a result of wrong performance of electronic circuit a new type of wrong coincidence appeared [ru

  5. Simulation of triple coincidences in PET

    International Nuclear Information System (INIS)

    Cal-González, J; Herranz, E; Vicente, E; Udias, J M; Lage, E; Dave, S R; Parot, V; Herraiz, J L; Moore, S C; Park, M-A

    2015-01-01

    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 (R T ), 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

  6. Neutron coincidence counting with digital signal processing

    International Nuclear Information System (INIS)

    Bagi, Janos; Dechamp, Luc; Dransart, Pascal; Dzbikowicz, Zdzislaw; Dufour, Jean-Luc; Holzleitner, Ludwig; Huszti, Joseph; Looman, Marc; Marin Ferrer, Montserrat; Lambert, Thierry; Peerani, Paolo; Rackham, Jamie; Swinhoe, Martyn; Tobin, Steve; Weber, Anne-Laure; Wilson, Mark

    2009-01-01

    Neutron coincidence counting is a widely adopted nondestructive assay (NDA) technique used in nuclear safeguards to measure the mass of nuclear material in samples. Nowadays, most neutron-counting systems are based on the original-shift-register technology, like the (ordinary or multiplicity) Shift-Register Analyser. The analogue signal from the He-3 tubes is processed by an amplifier/single channel analyser (SCA) producing a train of TTL pulses that are fed into an electronic unit that performs the time- correlation analysis. Following the suggestion of the main inspection authorities (IAEA, Euratom and the French Ministry of Industry), several research laboratories have started to study and develop prototypes of neutron-counting systems with PC-based processing. Collaboration in this field among JRC, IRSN and LANL has been established within the framework of the ESARDA-NDA working group. Joint testing campaigns have been performed in the JRC PERLA laboratory, using different equipment provided by the three partners. One area of development is the use of high-speed PCs and pulse acquisition electronics that provide a time stamp (LIST-Mode Acquisition) for every digital pulse. The time stamp data can be processed directly during acquisition or saved on a hard disk. The latter method has the advantage that measurement data can be analysed with different values for parameters like predelay and gate width, without repeating the acquisition. Other useful diagnostic information, such as die-away time and dead time, can also be extracted from this stored data. A second area is the development of 'virtual instruments.' These devices, in which the pulse-processing system can be embedded in the neutron counter itself and sends counting data to a PC, can give increased data-acquisition speeds. Either or both of these developments could give rise to the next generation of instrumentation for improved practical neutron-correlation measurements. The paper will describe the

  7. Coincidence method for determination of radionuclides activities

    International Nuclear Information System (INIS)

    Andrukhovich, S.K.; Berestov, A.V.; Rudak, E.A.

    2004-01-01

    The radon and radium activity measurements using six-crystal gamma-gamma coincidence, 4 -spectrometer PRIPJAT and radioactivity measurements in different samples of meat and vegetation by 32-crystal spectrometer ARGUS, are described. Radiation detector with 4 -geometry provides higher efficiency, and therefore shorter counting time than a detector without such geometry. However, its application is limited by the fact that obtained spectrum contains summing peaks of all γ-quanta registered in coincidence. Multiparameter information on coincident photon emission can be obtained only by a detection system where the 4 -geometry is made by many detectors, such are both the PRIPJAT and the ARGUS - γ-coincidence spectrometer of the Crystal Ball type in the Institute of Physics, Minsk [1,2]. There are other characteristics, as background conditions, energy and time resolution, makes it ve suitable for investigation of rare decays and interactions, cascade transitions, k intensity radiations etc. We are developing a method of 2 26R a and 2 26 Rn measurement by a multidetector 4 -spectrometer. The method is based on coincidence counting of γ-rays from two step cascade transitions that follow - decay of 2 14 Bi. Its application to the PRIPL spectrometer, which has 6 Nal(Tl) detectors, is presented here, as well as the method of the determination of radionuclide activities based on the registration of the cascades intensity of γ-rays of different multiplicity using ARGUS

  8. Quintessence, Cosmic Coincidence, and the Cosmological Constant

    International Nuclear Information System (INIS)

    Zlatev, I.; Wang, L.; Steinhardt, P.J.; Steinhardt, P.J.

    1999-01-01

    Recent observations suggest that a large fraction of the energy density of the Universe has negative pressure. One explanation is vacuum energy density; another is quintessence in the form of a scalar field slowly evolving down a potential. In either case, a key problem is to explain why the energy density nearly coincides with the matter density today. The densities decrease at different rates as the Universe expands, so coincidence today appears to require that their ratio be set to a specific, infinitesimal value in the early Universe. In this paper, we introduce the notion of a open-quotes tracker field,close quotes a form of quintessence, and show how it may explain the coincidence, adding new motivation for the quintessence scenario. copyright 1999 The American Physical Society

  9. Slow coincidences for CAMAC multiparameter analysis

    International Nuclear Information System (INIS)

    Akimov, Yu.K.; Kalinin, A.I.; Tissol'd, E.; Fromm, V.D.; Ekstein, P.

    1978-01-01

    A coincidence circuit with controlled parameters is described. The circuit has six coincidence inputs and one input for anticoincidences. A pulse duration in channels is changed from 0.25 to 5 μs and delay time, within 8 μs. The circuit is developed for multiparameter spectrometric analysis with the use of amplitude-digital and time-digital convertors. Its introduction permits one to diminish considerably the ''dead'' time of apparatus and to select rapidly and reliably strictly correlated digital information from convertors

  10. Coincidence-counting corrections for accidental coincidences, set dead time and intrinsic dead time

    International Nuclear Information System (INIS)

    Wyllie, H.A.

    1998-01-01

    An equation is derived for calculating the radioactivity of a source from the results of coincidence counting, taking into account dead-time losses and accidental coincidences. The corrections allow for the extension of the set dead time in the p channel by the intrinsic dead time. Experimental verification shows improvement over a previous equation. (author)

  11. X-ray line coincidence photopumping in a solar flare

    Science.gov (United States)

    Keenan, F. P.; Poppenhaeger, K.; Mathioudakis, M.; Rose, S. J.; Flowerdew, J.; Hynes, D.; Christian, D. J.; Nilsen, J.; Johnson, W. R.

    2018-03-01

    Line coincidence photopumping is a process where the electrons of an atomic or molecular species are radiatively excited through the absorption of line emission from another species at a coincident wavelength. There are many instances of line coincidence photopumping in astrophysical sources at optical and ultraviolet wavelengths, with the most famous example being Bowen fluorescence (pumping of O III 303.80 Å by He II), but none to our knowledge in X-rays. However, here we report on a scheme where a He-like line of Ne IX at 11.000 Å is photopumped by He-like Na X at 11.003 Å, which predicts significant intensity enhancement in the Ne IX 82.76 Å transition under physical conditions found in solar flare plasmas. A comparison of our theoretical models with published X-ray observations of a solar flare obtained during a rocket flight provides evidence for line enhancement, with the measured degree of enhancement being consistent with that expected from theory, a truly surprising result. Observations of this enhancement during flares on stars other than the Sun would provide a powerful new diagnostic tool for determining the sizes of flare loops in these distant, spatially unresolved, astronomical sources.

  12. Determining chance coincidence, survival factor and decay factor in 220Rn delayed coincidence measurement

    International Nuclear Information System (INIS)

    Huang Derong; Yan Yongjun; Zhou Jianliang; Qiu Shoukang

    2013-01-01

    The method and calculation formulas to determine the chance coincidence in the 220 Rn coincidence measurement are introduced in this paper. The poisson distribution is introduced to correct the chance coincidence. The relative deviation of the true coincidence between the method and the Giffin's is within 5% after the correction of the cohance coincidence. The measurement of 220 Rn is done by comparative measurement with RAD7. The results shows that 220 Rn can be measured by the method with a relative deviation of 14%. Mean while, for the 220 Rn flow regime is difficult to meet the condition of calculation formulas, a solution to solve the survival factor and decay factor is proposed and the error come from the useage of theoretical calculation formula is avoided. (authors)

  13. Tachyon driven solution to Cosmic Coincidence Problrm

    OpenAIRE

    Srivastaca, S. K.

    2004-01-01

    Here, non-minimally coupled tachyon to gravity is considered as a source of "dark energy". It is demonstrated that with expansion of the universe, tachyon dark energy decays to "dark matter" providing a solution to "cosmic coincidence problem".Moreover, it is found that universe undergoes accelerated expansion simultaneously.

  14. High-level neutron coincidence counter maintenance manual

    International Nuclear Information System (INIS)

    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

  15. Standardization of 18F by coincidence and LSC methods

    International Nuclear Information System (INIS)

    Roteta, Miguel; Garcia-Torano, Eduardo; Rodriguez Barquero, Leonor

    2006-01-01

    The nuclide 18 F disintegrates to 18 O by β + emission (96.86%) and electron capture (3.14%) with a half-life of 1.8288 h. It is widely used in nuclear medicine for positron emission tomography (PET). A radioactive solution of this nuclide has been standardized by two techniques: coincidence measurements with a pressurized proportional counter and liquid scintillation counting using the CIEMAT/NIST method. One ampoule containing a solution calibrated in activity was sent for measurement at the International Reference System maintained by the BIPM. Results are in excellent agreement with SIR values

  16. 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.

  17. Using Compton scattering for random coincidence rejection

    International Nuclear Information System (INIS)

    Kolstein, M.; Chmeissani, M.

    2016-01-01

    The Voxel Imaging PET (VIP) project presents a new approach for the design of nuclear medicine imaging devices by using highly segmented pixel CdTe sensors. CdTe detectors can achieve an energy resolution of ≈ 1% FWHM at 511 keV and can be easily segmented into submillimeter sized voxels for optimal spatial resolution. These features help in rejecting a large part of the scattered events from the PET coincidence sample in order to obtain high quality images. Another contribution to the background are random events, i.e., hits caused by two independent gammas without a common origin. Given that 60% of 511 keV photons undergo Compton scattering in CdTe (i.e. 84% of all coincidence events have at least one Compton scattering gamma), we present a simulation study on the possibility to use the Compton scattering information of at least one of the coincident gammas within the detector to reject random coincidences. The idea uses the fact that if a gamma undergoes Compton scattering in the detector, it will cause two hits in the pixel detectors. The first hit corresponds to the Compton scattering process. The second hit shall correspond to the photoelectric absorption of the remaining energy of the gamma. With the energy deposition of the first hit, one can calculate the Compton scattering angle. By measuring the hit location of the coincident gamma, we can construct the geometric angle, under the assumption that both gammas come from the same origin. Using the difference between the Compton scattering angle and the geometric angle, random events can be rejected.

  18. Neutron coincidence counter for MOX fuel pins in storage trays: users' manual

    International Nuclear Information System (INIS)

    Cowder, L.; Menlove, H.

    1982-08-01

    The neutron coincidence counter for measurement of mixed-oxide fuel pins in storage trays is described. The special detector head has been designed so that the detectors, high-voltage junction boxes, and electronics are interchangeable with those of the high-level neutron coincidence counter system. This manual describes the system components and the operation and maintenance of the counter. The counter was developed at Los Alamos National Laboratory for in-plant inspection applications by the International Atomic Energy Agency

  19. Application of coincidence Doppler-broadening spectroscopy to different carbon phases

    International Nuclear Information System (INIS)

    Ito, Y.; Djourelov, N.; Suzuki, T.; Kondo, K.; Ito, Y.; Shantarovich, V.; Onoe, J.

    2004-01-01

    Coincidence Doppler-broadening spectroscopy was applied to C60 and C70 fullerenes and other carbon phases, such as nanotubes and graphites. Remarkable differences were observed in the Doppler-broadening of the positron annihilation γ-rays in these materials, which reflect the different densities distribution of the momentum for electrons annihilated with positrons. This would be caused by the different composition of the π and σ electrons in annihilation with positrons. This result shows the sensitivity of the coincidence Doppler-broadening method to determine the density distribution of electrons sampled by positrons. (orig.)

  20. Method and apparstus for determining random coincidence count rate in a scintillation counter utilizing the coincidence technique

    International Nuclear Information System (INIS)

    Horrocks, D.L.

    1980-01-01

    A method and apparatus for the reliable determination of a random coincidence count attributable to chance coincidences of single-photon events which are each detected in only a single detector of a scintillation counter utilizing two detectors in a coincidence counting technique are described. A firstdelay device is employed to delay output pulses from one detector, and then the delayed signal is compared with the undelayed signal from the other detector in a coincidence circuit, to obtain an approximate random coincidence count. The output of the coincidence circuit is applied to an anti-coincidence circuit, where it is corrected by elimination of pulses coincident with, and attributable to, conventionally detected real coincidences, and by elimination of pulses coincident with, and attributable to, real coincidences that have been delayed by a second delay device having the same time parameter as the first. 8 claims

  1. Development of coincidence processing module for PEM

    International Nuclear Information System (INIS)

    Feng Baotong; Shuai Lei; Li Ke

    2011-01-01

    For the breast cancer diagnosis and therapy, a prototype of positron emission mammography (PEM) was developed in Institute of High Energy Physics, Chinese Academy of Sciences. In this paper, the design of coincidence processing module (CPM) for this PEM was presented. Both the hardware architecture and the software logic were introduced. In this design, the CPM used the Rocket IO fast interface in FPGA and fiber technology to acquire the preprocessed data from the continuous sampling module (CSM) and then selected the valid event with the coincidence timing window method, which was performed in the FPGA on the daughter board. The CPM transmits the processed data to host computer via gigabit Ethernet. The whole system was controlled by CAN bus. The primary tests indicate that the performance of this design is good. (authors)

  2. Recent progress with digital coincidence counting

    International Nuclear Information System (INIS)

    Butcher, K.S.A.; Watt, G.C.; Alexiev, D.

    1999-01-01

    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

  3. New way on designing majorant coincidence circuits

    International Nuclear Information System (INIS)

    Gajdamaka, R.I.; Kalinnikov, V.A.; Nikityuk, N.M.; Shirikov, V.P.

    1982-01-01

    A new way of designing fast devices of combinatorial selection by the number of particles passing through a multichannel charged particle detector is decribed. The algorithm of their operation is based on modern algebraic coding theory. By application of analytical computational methods Boolean expressions can be obtianed for designing basic circuits for a large number of inputs. An example of computation of 15 inputs majorant coincidence circuit is considered

  4. 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.

  5. Coincident-inclusive electrofission angular correlations

    International Nuclear Information System (INIS)

    Arruda Neto, J.D.T.

    1983-08-01

    A method for the joint analysis of coincident and inclusive electrofission data, in order to minimize effects of the model dependence of data interpretation, is developed. Explicit calculations of the (e,e'f) angular correlations are presented. The potentialities of the method to the study of sub- and near-barrier properties of the fission process, and to the study of the giant resonances fission mode, are discussed. (Author) [pt

  6. Timing coincidence studies with fast photomultipliers

    International Nuclear Information System (INIS)

    Raoof, M.A.; Raoof, S.A.

    1981-01-01

    The time response of RCA C70045D photomultipliers was studied using a subnanosecond light flasher. The tubes, which have an output rise time of approximately 0.5 ns, were used in coincidence to study the variations in the fwhm of the time spectrum over a certain dynamic range of pulse amplitudes for both leading edge and constant fraction discrimination. A comparison has also been made for the measured time resolutions with some of the other fast photomultipliers. (orig.)

  7. Fast coincidence counting with active inspection systems

    Science.gov (United States)

    Mullens, J. A.; Neal, J. S.; Hausladen, P. A.; Pozzi, S. A.; Mihalczo, J. T.

    2005-12-01

    This paper describes 2nd and 3rd order time coincidence distributions measurements with a GHz processor that synchronously samples 5 or 10 channels of data from radiation detectors near fissile material. On-line, time coincidence distributions are measured between detectors or between detectors and an external stimulating source. Detector-to-detector correlations are useful for passive measurements also. The processor also measures the number of times n pulses occur in a selectable time window and compares this multiplet distribution to a Poisson distribution as a method of determining the occurrence of fission. The detectors respond to radiation emitted in the fission process induced internally by inherent sources or by external sources such as LINACS, DT generators either pulsed or steady state with alpha detectors, etc. Data can be acquired from prompt emission during the source pulse, prompt emissions immediately after the source pulse, or delayed emissions between source pulses. These types of time coincidence measurements (occurring on the time scale of the fission chain multiplication processes for nuclear weapons grade U and Pu) are useful for determining the presence of these fissile materials and quantifying the amount, and are useful for counter terrorism and nuclear material control and accountability. This paper presents the results for a variety of measurements.

  8. Fast coincidence counting with active inspection systems

    International Nuclear Information System (INIS)

    Mullens, J.A.; Neal, J.S.; Hausladen, P.A.; Pozzi, S.A.; Mihalczo, J.T.

    2005-01-01

    This paper describes 2nd and 3rd order time coincidence distributions measurements with a GHz processor that synchronously samples 5 or 10 channels of data from radiation detectors near fissile material. On-line, time coincidence distributions are measured between detectors or between detectors and an external stimulating source. Detector-to-detector correlations are useful for passive measurements also. The processor also measures the number of times n pulses occur in a selectable time window and compares this multiplet distribution to a Poisson distribution as a method of determining the occurrence of fission. The detectors respond to radiation emitted in the fission process induced internally by inherent sources or by external sources such as LINACS, DT generators either pulsed or steady state with alpha detectors, etc. Data can be acquired from prompt emission during the source pulse, prompt emissions immediately after the source pulse, or delayed emissions between source pulses. These types of time coincidence measurements (occurring on the time scale of the fission chain multiplication processes for nuclear weapons grade U and Pu) are useful for determining the presence of these fissile materials and quantifying the amount, and are useful for counter terrorism and nuclear material control and accountability. This paper presents the results for a variety of measurements

  9. Coincidence corrections for a multi-detector gamma spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Britton, R., E-mail: r.britton@surrey.ac.uk [University of Surrey, Guildford GU2 7XH (United Kingdom); AWE, Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom); Burnett, J.L.; Davies, A.V. [AWE, Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom); Regan, P.H. [University of Surrey, Guildford GU2 7XH (United Kingdom)

    2015-01-01

    List-mode data acquisition has been utilised in conjunction with a high-efficiency γ–γ coincidence system, allowing both the energetic and temporal information to be retained for each recorded event. Collected data is re-processed multiple times to extract any coincidence information from the γ-spectroscopy system, correct for the time-walk of low-energy events, and remove accidental coincidences from the projected coincidence spectra. The time-walk correction has resulted in a reduction in the width of the coincidence delay gate of 18.4±0.4%, and thus an equivalent removal of ‘background’ coincidences. The correction factors applied to ∼5.6% of events up to ∼500 keV for a combined {sup 137}Cs and {sup 60}Co source, and are crucial for accurate coincidence measurements of low-energy events that may otherwise be missed by a standard delay gate. By extracting both the delay gate and a representative ‘background’ region for the coincidences, a coincidence background subtracted spectrum is projected from the coincidence matrix, which effectively removes ∼100% of the accidental coincidences (up to 16.6±0.7% of the total coincidence events seen during this work). This accidental-coincidence removal is crucial for accurate characterisation of the events seen in coincidence systems, as without this correction false coincidence signatures may be incorrectly interpreted.

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

    International Nuclear Information System (INIS)

    Guevara, E.A.

    1986-01-01

    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 60 Co, 22 Na, 47 Ca and 148 Pm 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.) [es

  11. Coincident Detection Significance in Multimessenger Astronomy

    Science.gov (United States)

    Ashton, G.; Burns, E.; Dal Canton, T.; Dent, T.; Eggenstein, H.-B.; Nielsen, A. B.; Prix, R.; Was, M.; Zhu, S. J.

    2018-06-01

    We derive a Bayesian criterion for assessing whether signals observed in two separate data sets originate from a common source. The Bayes factor for a common versus unrelated origin of signals includes an overlap integral of the posterior distributions over the common-source parameters. Focusing on multimessenger gravitational-wave astronomy, we apply the method to the spatial and temporal association of independent gravitational-wave and electromagnetic (or neutrino) observations. As an example, we consider the coincidence between the recently discovered gravitational-wave signal GW170817 from a binary neutron star merger and the gamma-ray burst GRB 170817A: we find that the common-source model is enormously favored over a model describing them as unrelated signals.

  12. A generalized model for coincidence counting

    International Nuclear Information System (INIS)

    Lu, Ming-Shih; Teichmann, T.

    1992-01-01

    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

  13. More accurate thermal neutron coincidence counting technique

    International Nuclear Information System (INIS)

    Baron, N.

    1978-01-01

    Using passive thermal neutron coincidence counting techniques, the accuracy of nondestructive assays of fertile material can be improved significantly using a two-ring detector. It was shown how the use of a function of the coincidence count rate ring-ratio can provide a detector response rate that is independent of variations in neutron detection efficiency caused by varying sample moderation. Furthermore, the correction for multiplication caused by SF- and (α,n)-neutrons is shown to be separable into the product of a function of the effective mass of 240 Pu (plutonium correction) and a function of the (α,n) reaction probability (matrix correction). The matrix correction is described by a function of the singles count rate ring-ratio. This correction factor is empirically observed to be identical for any combination of PuO 2 powder and matrix materials SiO 2 and MgO because of the similar relation of the (α,n)-Q value and (α,n)-reaction cross section among these matrix nuclei. However the matrix correction expression is expected to be different for matrix materials such as Na, Al, and/or Li. Nevertheless, it should be recognized that for comparison measurements among samples of similar matrix content, it is expected that some function of the singles count rate ring-ratio can be defined to account for variations in the matrix correction due to differences in the intimacy of mixture among the samples. Furthermore the magnitude of this singles count rate ring-ratio serves to identify the contaminant generating the (α,n)-neutrons. Such information is useful in process control

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

    Science.gov (United States)

    de la Fuente, R; de Celis, B; del Canto, V; Lumbreras, J M; de Celis Alonso, B; Martín-Martín, A; Gutierrez-Villanueva, J L

    2008-10-01

    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 alpha/beta/gamma-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 alpha/beta particles and X-rays/gamma 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 alpha/gamma 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.

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

    International Nuclear Information System (INIS)

    Fuente, R. de la; Celis, B. de; Canto, V. del; Lumbreras, J.M.; Celis, Alonso B. de; Martin-Martin, A.; Gutierrez-Villanueva, J.L.

    2008-01-01

    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

  16. Minicomputer system for radiochemical analysis by coincidence spectrometry

    International Nuclear Information System (INIS)

    Brauer, F.P.; Fager, J.E.

    1979-01-01

    Minicomputer-based coincidence analysis methods have been developed for use in performing radiochemical analysis by high-resolution x- and gamma-ray coincidence spectrometry. This paper describes the data-acquisition and analysis methods develolped for qualitative and quantitative analyses of coincidence spectrometric data. Data-acquisition capabilities include both direct multiparameter pulse-height analysis and buffered list-mode acquisition

  17. Soudan 2 muons in coincidence with BATSE bursts

    International Nuclear Information System (INIS)

    DeMuth, D.M.; Marshak, M.L.; Wagner, G.L.

    1994-01-01

    We explore the possibilities of statistically significant temporal and spatial coincidences between underground muons at Soudan 2 and Gamma Ray Bursts at the GRO-BATSE detector. Our search uses data from the April 91 to March 92 BATSE burst catalog to seek correlations within a 100 second window of coincidence. Sixteen of 180 BATSE triggers have temporally and spatially coincident muons in the Soudan 2 detector. We estimate the chance probability of each coincidence assuming the null hypothesis on the basis of a study of the multiplicities of spatially coincident muons observed over a two day period centered on the time of burst

  18. K-chameleon and the coincidence problem

    International Nuclear Information System (INIS)

    Wei Hao; Cai Ronggen

    2005-01-01

    In this paper we present a hybrid model of k-essence and chameleon, named as k-chameleon. In this model, due to the chameleon mechanism, the directly strong coupling between the k-chameleon field and matters (cold dark matters and baryons) is allowed. In the radiation-dominated epoch, the interaction between the k-chameleon field and background matters can be neglected; the behavior of the k-chameleon therefore is the same as that of the ordinary k-essence. After the onset of matter domination, the strong coupling between the k-chameleon and matters dramatically changes the result of the ordinary k-essence. We find that during the matter-dominated epoch, only two kinds of attractors may exist: one is the familiar K attractor and the other is a completely new, dubbed C attractor. Once the Universe is attracted into the C attractor, the fraction energy densities of the k-chameleon Ω φ and dust matter Ω m are fixed and comparable, and the Universe will undergo a power-law accelerated expansion. One can adjust the model so that the K attractor does not appear. Thus, the k-chameleon model provides a natural solution to the cosmological coincidence problem

  19. Coincidence orientations of grains in hexagonal materials

    International Nuclear Information System (INIS)

    Grimmer, H.; Warrington, D.H.

    1986-06-01

    The connection between the rotation matrix in hexagonal lattice coordinates and an angle-axis quadruple is given. The multiplication law of quadruples is derived. It corresponds to multiplying two matrices and gives the effect of two successive rotations. The relation is given between two quadruples that describe the same relative orientation of two lattices due to their hexagonal symmetry; a unique standard description of the relative orientation is proposed. The restrictions satisfied by rotations generating coincidence site lattices (CSLs) are derived for any value of the axial ratio rho = c/a. It is shown that the law for cubic lattices, where the multiplicity SIGMA of the CSL was equal to the least common denominator of the elements of the rotation matrix, does not always hold for hexagonal lattices. A generalisation of this law to lattices of arbitrary symmetry is given and another, quicker method to determine SIGMA for hexagonal lattices is derived. Finally, convenient algorithms are described for determining bases of the CSL and the DSC lattice. (author)

  20. Complex action support from coincidences of couplings

    International Nuclear Information System (INIS)

    Nielsen, H.B.

    2011-01-01

    Our model (Refs. 1–7) with a complex action in a functional integral formulation with path integrals extending over all times, both past and future, is reviewed. Several numerical relations between coupling constants are presented as supporting evidence. The new evidence is that several more hitherto unexplained coincidences are explained by our model: (1) The "scale problem" is solved because the Higgs field expectation value is predicted to be very small compared to say some fundamental scale, that might be the Planck scale. (2) The Higgs VEV need not be just zero, but rather is predicted to be so that the running top-quark Yukawa coupling just is about to be unity at this scale; in this way the (weak) scale easily becomes "exponentially small." Instead of the top-Yukawa we should rather say the highest flavor Yukawa coupling here. These predictions are only achieved by allowing the principle of minimization of the imaginary part of the action SI(history) to a certain extent adjust some coupling constants in addition to the initial conditions. If supersymmetric partners are not found at LHC it would strengthen the need for a "solution" to the hierarchy problem in our direction of an explanation via a fine-tuning scheme inside the Standard Model, from say minimizing "the imaginary part of the action" in our complex action model. (author)

  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. Calculations of coincident ionization plus excitation

    International Nuclear Information System (INIS)

    Becker, R.L.

    1986-01-01

    For Li- and Be-like ions, K x-ray yields, together with detection that the ionic charge has increased, give the cross section for ionization plus excitation (IE), a process which can exhibit electron-electron correlations. Measurements of IE for 14 Si 11+ + He stimulated our coupled-channels calculations in the independent-Fermi-particle model (IFPM), which includes Pauli correlations. We discuss how the IFPM expressions, generalized here to include an open shell, differ from those for distinguishable electrons. The sensitivity of σ/sub IE/ to correlations is shown. Recent additional measurements and future ones giving excitation functions for resolved configurations and complementary Auger data will provide even more sensitive tests of collisional correlation theory. 15 refs., 3 figs., 1 tab

  3. Standardization of 241Am by digital coincidence counting, liquid scintillation counting and defined solid angle counting

    International Nuclear Information System (INIS)

    Balpardo, C.; Capoulat, M.E.; Rodrigues, D.; Arenillas, P.

    2010-01-01

    The nuclide 241 Am decays by alpha emission to 237 Np. Most of the decays (84.6%) populate the excited level of 237 Np with energy of 59.54 keV. Digital coincidence counting was applied to standardize a solution of 241 Am 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.

  4. Photoelectron photoion coincidence imaging of ultrafast control in multichannel molecular dynamics.

    Science.gov (United States)

    Lehmann, C Stefan; Ram, N Bhargava; Irimia, Daniel; Janssen, Maurice H M

    2011-01-01

    The control of multichannel ionic fragmentation dynamics in CF3I is studied by femtosecond pulse shaping and velocity map photoelectron photoion coincidence imaging. When CF3I is photoexcited with femtosecond laser pulses around 540 nm there are two major ions observed in the time-of-flight mass spectrum, the parent CF3I+ ion and the CF3+ fragment ion. In this first study we focussed on the influence of LCD-shaped laser pulses on the molecular dynamics. The three-dimensional recoil distribution of electrons and ions were imaged in coincidence using a single time-of-flight delay line detector. By fast switching of the voltages on the various velocity map ion lenses after detection of the electron, both the electron and the coincident ion are measured with the same imaging detector. These results demonstrate that a significant simplification of a photoelectron-photoion coincidence imaging apparatus is in principle possible using switched lens voltages. It is observed that shaped laser fields like chirped pulses, double pulses, and multiple pulses can enhance the CF3+CF3I+ ratio by up to 100%. The total energetics of the dynamics is revealed by analysis of the coincident photoelectron spectra and the kinetic energy of the CF3+ and I fragments. Both the parent CF3I+ and the CF3+ fragment result from a five-photon excitation process. The fragments are formed with very low kinetic energy. The photoelectron spectra and CF3+/CF3I+ ratio vary with the center wavelength of the shaped laser pulses. An optimal enhancement of the CF3+/CF3I+ ratio by about 60% is observed for the double pulse excitation when the pulses are spaced 60 fs apart. We propose that the control mechanism is determined by dynamics on neutral excited states and we discuss the results in relation to the location of electronically excited (Rydberg) states of CF3I.

  5. Minority n out of m coincidence circuits for time-differential experiments with multi-detector arrays

    International Nuclear Information System (INIS)

    Braunsfurth, J.; Geske, K.

    1976-01-01

    Two n out of m minority coincidence circuits (n<=8, 15<=m<=31), employed for time-differential experiments are presented. Specifications like obtainable prompt coincidence resolution time, expandability to higher detector numbers m, implementation variants and their consequences, and some application modes are discussed. Hardware expenses on electronics for m-detector arrays usually rise nearly proportional to m factorial. In the coincidence system proposed here, the rise in hardware expenses can be reduced to slightly more than proportional to m, without sacrifice in experimental quality and flexibility. (Auth.)

  6. Gamma-X-ray coincidence Moessbauer spectroscopic study of the aftereffects in sulfate hydrates

    International Nuclear Information System (INIS)

    Kobayashi, T.; Makita, T.; Fukumura, K.

    1990-01-01

    The anomalous charge states formed after the electron capture decay of 57 Co in FeSO 4 .H 2 O and FeSO 4 .7H 2 O are investigated using the conventional Moessbauer emission spectroscopy and a gamma-X ray coincidence method. This method is based on the idea that a Moessbauer spectrum observed with the coincidence technique only when K-X rays are emitted is reflected by isolated events with a reduced influence of the Auger-electron self-irradiation. The formation of the anomalous electronic and structural configuration is attributed to the self-radiolysis of the H 2 O and SO 4 2- ligands in the nearest and the second nearest coordination shells around the decaying atom. (orig.)

  7. Principle of coincidence method and application in activity measurement

    International Nuclear Information System (INIS)

    Li Mou; Dai Yihua; Ni Jianzhong

    2008-01-01

    The basic principle of coincidence method was discussed. The basic principle was generalized by analysing the actual example, and the condition in theory of coincidence method was brought forward. The cause of variation of efficiency curve and the effect of dead-time in activity measurement were explained using the above principle and condition. This principle of coincidence method provides the foundation in theory for activity measurement. (authors)

  8. Operations manual for the megachannel gamma-ray coincidence system

    International Nuclear Information System (INIS)

    Ruhter, W.

    1977-01-01

    To aid in the study of nuclear structures, a megachannel pulse-height coincidence analysis system on a PDP-8 computer was constructed. The system digitizes the energies of coincident gamma-rays and stores the resultant information on a moving-head disk. The system uses a minicomputer to sort and store gamma-gamma coincident information on line. The megachannel system and how to use it are described

  9. Coincidence Imaging and interference with coherent Gaussian beams

    Institute of Scientific and Technical Information of China (English)

    CAI Yang-jian; ZHU Shi-yao

    2006-01-01

    we present a theoretical study of coincidence imaging and interference with coherent Gaussian beams The equations for the coincidence image formation and interference fringes are derived,from which it is clear that the imaging is due to the corresponding focusing in the two paths .The quality and visibility of the images and fringes can be high simultaneously.The nature of the coincidence imaging and interference between quantum entangled photon pairs and coherent Gaussian beams are different .The coincidence image with coherent Gaussian beams is due to intensity-intensity correspondence,a classical nature,while that with entangled photon pairs is due to the amplitude correlation a quantum nature.

  10. 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

  11. An Inexpensive Coincidence Circuit for the Pasco Geiger Sensors

    CERN Document Server

    Fichera, F; Librizzi, F; Riggi, F

    2005-01-01

    A simple coincidence circuit was devised to carry out educational coincidence experiments involving the use of Geiger counters. The system was tested by commercially available Geiger sensors from PASCO, and is intended to be used in collaboration with high school students and teachers

  12. Identification of peaks in multidimensional coincidence {gamma}-ray spectra

    Energy Technology Data Exchange (ETDEWEB)

    Morhac, Miroslav E-mail: fyzimiro@savba.sk; Kliman, Jan; Matousek, Vladislav; Veselsky, Martin; Turzo, Ivan

    2000-03-21

    In the paper a new algorithm to find peaks in two, three and multidimensional spectra, measured in large multidetector {gamma}-ray arrays, is derived. Given the dimension m, the algorithm is selective to m-fold coincidence peaks. It is insensitive to intersections of lower-fold coincidences, hereinafter called ridges.

  13. Identification of peaks in multidimensional coincidence γ-ray spectra

    International Nuclear Information System (INIS)

    Morhac, Miroslav; Kliman, Jan; Matousek, Vladislav; Veselsky, Martin; Turzo, Ivan

    2000-01-01

    In the paper a new algorithm to find peaks in two, three and multidimensional spectra, measured in large multidetector γ-ray arrays, is derived. Given the dimension m, the algorithm is selective to m-fold coincidence peaks. It is insensitive to intersections of lower-fold coincidences, hereinafter called ridges

  14. 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

  15. Recovery and normalization of triple coincidences in PET.

    Science.gov (United States)

    Lage, Eduardo; Parot, Vicente; Moore, Stephen C; Sitek, Arkadiusz; Udías, Jose M; Dave, Shivang R; Park, Mi-Ae; Vaquero, Juan J; Herraiz, Joaquin L

    2015-03-01

    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. 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. The addition of triple-coincidence events with the authors' method increased peak

  16. High rate 4π β-γ coincidence counting system

    International Nuclear Information System (INIS)

    Johnson, L.O.; Gehrke, R.J.

    1978-01-01

    A high count rate 4π β-γ coincidence counting system for the determination of absolute disintegration rates of short half-life radionuclides is described. With this system the dead time per pulse is minimized by not stretching any pulses beyond the width necessary to satisfy overlap coincidence requirements. The equations used to correct for the β, γ, and coincidence channel dead times and for accidental coincidences are presented but not rigorously developed. Experimental results are presented for a decaying source of 56 Mn initially at 2 x 10 6 d/s and a set of 60 Co sources of accurately known source strengths varying from 10 3 to 2 x 10 6 d/s. A check of the accidental coincidence equation for the case of two independent sources with varying source strengths is presented

  17. Standardisation of 64Cu using a software coincidence counting system

    International Nuclear Information System (INIS)

    Havelka, Miroslav; Sochorová, Jana

    2014-01-01

    The activity of the radionuclide 64 Cu was determined by the efficiency extrapolation method applied to 4π(PC)−γ coincidence counting. The standardisation was performed by software coincidence counting—a digital method for primary activity measurement that simplifies the setting of optimal coincidence parameters. The γ-ray-energy window, characterised by identical gamma detection efficiency related to the sum of EC and to the sum of beta decay branches, was found. This setting ensured a linear and zero slope extrapolation curve. - Highlights: • Standardisation realised by extrapolation method applied to 4π(PC)−γ coincidence. • Digital method for optimal setting of coincidence parameters was used. • Result with total standard uncertainty of 0.74% was obtained

  18. Low level GAMMA0 spectrometry by beta-gamma coincidence

    International Nuclear Information System (INIS)

    Grigorescu, E.L.; Luca, A.; Razdolescu, A.C.; Ivan, C.

    1999-01-01

    Low level gamma spectrometry has a wide application, especially in environmental monitoring. Two variants, based on a beta-gamma coincidence technique, were studied. The equipment was composed of a beta detector and a Ge(Li) gamma detector (6% - relative efficiency), with the associated electronics. The gamma rays are recorded by the multichannel analyzer (4096 channels) only if the associated beta particles, which precede the gamma transitions, are registered in coincidence. Two types of beta detectors were used: plastic and liquid scintillators. In both cases, an external lead shield of 5 cm thick was used. The integral gamma background (50-1700 KeV) was reduced about 85 and 50 times, respectively. The corresponding MDA (Minimum Detectable Activity) values decreased about 1.5 and (3-7) times, respectively. The 2π sr plastic beta detector was placed on top the Ge(Li). The sample was inserted between the two detectors. The measurement time was 10 4 s. A 4π sr detector, built of the same material, was also studied, but it proved to be less advantageous because the background was reduced only 16 times; for a MDA reduction similar with that of the 2π sr variant, a longer measurement was needed (3.10 4 s). The other type of beta detector used, was a liquid scintillator. The dissolving of the samples in scintillator ensures a 4π sr measurement geometry. The vials with scintillator (10 ml volume) were placed on top the Ge(Li) and visualised by the photocathode of a phototube. This setup was surrounded by an enclosure which prevent the light penetration. The measurement time was 10 4 s. The only difficulty encountered in this low level measurement method is the accurate determination of the beta efficiency. A limitation is the possibility to measure only small mass samples. These variants are more simple and cheaper than others, previously studied. The advantage of the method is obvious when, instead of low MDA values, shorter measurement times are preferred. The

  19. The origin of narrowing of the Si 2p coincidence photoelectron spectroscopy main line of Si(1 0 0) surface

    International Nuclear Information System (INIS)

    Ohno, Masahide

    2011-01-01

    Highlights: → The Si 2p coincidence photoelectron spectroscopy (PES) main line of Si(1 0 0) is calculated. → The PES main line shows an asymmetric line shape change compared to the singles one. → The narrowing of the coincidence Si 2p PES main line is well reproduced. → The inherent mechanism of APECS is explained by a many-body theory. - Abstract: The Si 2p photoelectron spectroscopy (PES) main line of Si(1 0 0) surface measured in coincidence with the singles (noncoincidence) Si L 2,3 -VV Auger-electron spectroscopy (AES) elastic peak is calculated. The agreement with the experiment is good. The present work is the first many-body calculation of the experimental coincidence PES spectrum of solid surface. The narrowing of the coincidence Si 2p PES main line compared to the singles one is due to the mechanism inherent in the coincidence PES. The inherent mechanism is explained by a many-body theory by which photoemission and Auger-electron emission are treated on the same footing.

  20. Many-body calculation of the coincidence L3 photoelectron spectroscopy main line of Ni metal

    International Nuclear Information System (INIS)

    Ohno, Masahide

    2008-01-01

    The partial singles L 3 photoelectron spectroscopy (PES) main line of Ni metal correlated with Auger electrons emitted by the localized L 3 -VV Auger decay is calculated by a many-body theory. The partial singles L 3 PES main line of Ni metal almost coincides in both line shape and peak kinetic energy (KE) with the singles one. The former main line peak shows a KE shift of only 0.01 eV toward the lower KE and a very small asymmetric line shape change compared to the singles one. The asymmetric line shape change and the peak KE shift of the partial singles L 3 main line are very small. However, they are due to the variation with photoelectron KE in the branching ratio of the partial Auger decay width in the partial singles L 3 PES main line by the photoelectron KE dependent imaginary part of the shakeup self-energy. The L 3 PES main line of Ni metal measured in coincidence with the L 3 -VV ( 1 G) Auger electron spectroscopy (AES) main line peak is the partial singles one modulated by a spectral function R a of a fixed energy Auger electron analyzer so that it should show only a symmetric line narrowing by R a compared to the singles one. The L 3 PES main line peak of Ni metal measured in coincidence with the delocalized band-like L 3 -VV AES peak or not completely split-off (or not completely localized) L 3 -VV ( 3 F) AES peak, will show an asymmetric line narrowing and a KE shift compared to the singles one. Thus, the L 3 PES main line of Ni metal in coincidence with various parts of the L 3 -VV AES spectrum depends on which part of the L 3 -VV AES spectrum a fixed energy Auger electron analyzer is set. The experimental verification is in need

  1. Software correction of scatter coincidence in positron CT

    International Nuclear Information System (INIS)

    Endo, M.; Iinuma, T.A.

    1984-01-01

    This paper describes a software correction of scatter coincidence in positron CT which is based on an estimation of scatter projections from true projections by an integral transform. Kernels for the integral transform are projected distributions of scatter coincidences for a line source at different positions in a water phantom and are calculated by Klein-Nishina's formula. True projections of any composite object can be determined from measured projections by iterative applications of the integral transform. The correction method was tested in computer simulations and phantom experiments with Positologica. The results showed that effects of scatter coincidence are not negligible in the quantitation of images, but the correction reduces them significantly. (orig.)

  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. Some target assay uncertainties for passive neutron coincidence counting

    International Nuclear Information System (INIS)

    Ensslin, N.; Langner, D.G.; Menlove, H.O.; Miller, M.C.; Russo, P.A.

    1990-01-01

    This paper provides some target assay uncertainties for passive neutron coincidence counting of plutonium metal, oxide, mixed oxide, and scrap and waste. The target values are based in part on past user experience and in part on the estimated results from new coincidence counting techniques that are under development. The paper summarizes assay error sources and the new coincidence techniques, and recommends the technique that is likely to yield the lowest assay uncertainty for a given material type. These target assay uncertainties are intended to be useful for NDA instrument selection and assay variance propagation studies for both new and existing facilities. 14 refs., 3 tabs

  4. Low-resource synchronous coincidence processor for positron emission tomography

    International Nuclear Information System (INIS)

    Sportelli, Giancarlo; Belcari, Nicola; Guerra, Pedro; Santos, Andres

    2011-01-01

    We developed a new FPGA-based method for coincidence detection in positron emission tomography. The method requires low device resources and no specific peripherals in order to resolve coincident digital pulses within a time window of a few nanoseconds. This method has been validated with a low-end Xilinx Spartan-3E and provided coincidence resolutions lower than 6 ns. This resolution depends directly on the signal propagation properties of the target device and the maximum available clock frequency, therefore it is expected to improve considerably on higher-end FPGAs.

  5. 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.

  6. Permutational symmetries for coincidence rates in multimode multiphotonic interferometry

    Science.gov (United States)

    Khalid, Abdullah; Spivak, Dylan; Sanders, Barry C.; de Guise, Hubert

    2018-06-01

    We obtain coincidence rates for passive optical interferometry by exploiting the permutational symmetries of partially distinguishable input photons, and our approach elucidates qualitative features of multiphoton coincidence landscapes. We treat the interferometer input as a product state of any number of photons in each input mode with photons distinguished by their arrival time. Detectors at the output of the interferometer count photons from each output mode over a long integration time. We generalize and prove the claim of Tillmann et al. [Phys. Rev. X 5, 041015 (2015), 10.1103/PhysRevX.5.041015] that coincidence rates can be elegantly expressed in terms of immanants. Immanants are functions of matrices that exhibit permutational symmetries and the immanants appearing in our coincidence-rate expressions share permutational symmetries with the input state. Our results are obtained by employing representation theory of the symmetric group to analyze systems of an arbitrary number of photons in arbitrarily sized interferometers.

  7. Electronics

    Science.gov (United States)

    2001-01-01

    International Acer Incorporated, Hsin Chu, Taiwan Aerospace Industrial Development Corporation, Taichung, Taiwan American Institute of Taiwan, Taipei, Taiwan...Singapore and Malaysia .5 - 4 - The largest market for semiconductor products is the high technology consumer electronics industry that consumes up...Singapore, and Malaysia . A new semiconductor facility costs around $3 billion to build and takes about two years to become operational

  8. Measurement of plutonium oxalate in thermal neutron coincidence counters

    International Nuclear Information System (INIS)

    Marshall, R.S.; Erkkila, B.H.

    1979-01-01

    A coincidence neutron counting method has been developed for assaying batches of plutonium oxalate. Using counting data from two concentric rings of 3 He detectors, corrections are made for the effects that water has on the coincidence neutron count rate. Batches of plutonium oxalate varying from 750 to 1000 g of plutonium and from 34 to 54% water are assayed with an average accuracy of +-3%

  9. Calculation of the n-th coincidences frequency

    International Nuclear Information System (INIS)

    Mercier, C.

    1959-01-01

    Events can occur randomly with a given frequency. Each event lasts a Θ-time. During this Θ-time other events can occur. A coincidence beginning of order n at a t-time is when an event occurs while n other events already occurred between t-Θ and t. In this work the frequency of coincidence beginnings with an order greater than or equal to n is established

  10. Energy and resolution calibration of detectors for noble gas β-γ coincidence system

    International Nuclear Information System (INIS)

    Jia Huaimao; Wang Shilian; Li Qi; Wang Jun; Zhao Yungang; Zhang Xinjun; Fan Yuanqing

    2010-01-01

    The β-γ coincidence technique is a kind of important method to detect radioactive xenon isotopes for the Comprehensive Nuclear-Test-Ban Treaty(CTBT). The energy and resolution calibration of detectors is the first key technique. This paper describes in detail the energy and resolution calibration methods of NaI (Tl) and plastic scintillator detectors for the noble gas β-γ coincidence system SAUNA II-Lab. NaI (Tl) detector's energy and resolution for γ-ray were calibrated with γ radioactive point sources. Plastic scintillator detector's energy and resolution for β-ray were calibrated by Compton scattering electrons of 137 Cs 661.66 keV γ-ray. And the results of β-ray energy resolution calibrated by Compton scattering electrons of 137 Cs were compared with the results of conversion electron of 131 Xe m . In conclusion,it is an easy and feasible method of calibrating plastic scintillator detector's energy by Compton scattering electrons of 137 Cs,but detector's resolution calibrated by Compton scattering electrons is higher than factual result. (authors)

  11. Observation of relaxation on time scale of core hole decay by coincidence photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Ohno, Masahide

    2007-01-01

    It is shown by a many-body theory that when the relaxation time of a metastable core hole state(s) to the most stable one is comparable to or shorter than core hole decay time of the former state(s), a comparison between the singles (noncoincidence) photoelectron spectroscopy (PES) spectrum and the coincidence one provides a direct evidence of the relaxation. In principle the variation with photoelectron kinetic energy of relaxation (or charge transfer (CT)) time can be determined. By singles measurement the correlation of a photoelectron generated by creation of the metastable states not only with an Auger electron generated by annihilation of the same core hole state but also with an Auger electron generated by annihilation of the stable state via relaxation of the metastable state, is completely lost, unless only the metastable state is observed by PES, whereas the correlation often manifests directly in the coincidence spectra. Thus, compared to the coincidence spectroscopy the singles one is often much less capable of elucidating the competition between relaxation and core hole decay of a metastable state. Such examples are discussed

  12. A deadtime reduction circuit for thermal neutron coincidence counters with Amptek preamplifiers

    International Nuclear Information System (INIS)

    Bourret, S.C.; Krick, M.S.

    1994-01-01

    We have developed a deadtime reduction circuit for thermal neutron coincidence counters using Amptek preamplifier/amplifier/discriminator circuits. The principle is to remove the overlap between the output pulses from the Amptek circuits by adding a derandomizer between the Amptek circuits and the shift-register coincidence electronics. We implemented the derandomizer as an Actel programmable logic array; the derandomizer board is small and can be mounted in the high-voltage junction box with the Amptek circuits, if desired. Up to 32 Amptek circuits can be used with one derandomizer. The derandomizer has seven outputs: four groups of eight inputs, two groups of 16 inputs, and one group of 32 inputs. We selected these groupings to facilitate detector ring-ratio measurements. The circuit was tested with the five-ring research multiplicity counter, which has five output signals-one for each ring. The counter's deadtime was reduced from 70 to 30 ns

  13. Standardization of Ga-68 by coincidence measurements, liquid scintillation counting and 4πγ counting.

    Science.gov (United States)

    Roteta, Miguel; Peyres, Virginia; Rodríguez Barquero, Leonor; García-Toraño, Eduardo; Arenillas, Pablo; Balpardo, Christian; Rodrígues, Darío; Llovera, Roberto

    2012-09-01

    The radionuclide (68)Ga is one of the few positron emitters that can be prepared in-house without the use of a cyclotron. It disintegrates to the ground state of (68)Zn partially by positron emission (89.1%) with a maximum energy of 1899.1 keV, and partially by electron capture (10.9%). This nuclide has been standardized in the frame of a cooperation project between the Radionuclide Metrology laboratories from CIEMAT (Spain) and CNEA (Argentina). Measurements involved several techniques: 4πβ-γ coincidences, integral gamma counting and Liquid Scintillation Counting using the triple to double coincidence ratio and the CIEMAT/NIST methods. Given the short half-life of the radionuclide assayed, a direct comparison between results from both laboratories was excluded and a comparison of experimental efficiencies of similar NaI detectors was used instead. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

    International Nuclear Information System (INIS)

    Celis, B. de; Fuente, R. de la; Williart, A.; Celis Alonso, B. de

    2007-01-01

    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 CaF 2 (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

  15. Importance of interpolation and coincidence errors in data fusion

    Science.gov (United States)

    Ceccherini, Simone; Carli, Bruno; Tirelli, Cecilia; Zoppetti, Nicola; Del Bianco, Samuele; Cortesi, Ugo; Kujanpää, Jukka; Dragani, Rossana

    2018-02-01

    The complete data fusion (CDF) method is applied to ozone profiles obtained from simulated measurements in the ultraviolet and in the thermal infrared in the framework of the Sentinel 4 mission of the Copernicus programme. We observe that the quality of the fused products is degraded when the fusing profiles are either retrieved on different vertical grids or referred to different true profiles. To address this shortcoming, a generalization of the complete data fusion method, which takes into account interpolation and coincidence errors, is presented. This upgrade overcomes the encountered problems and provides products of good quality when the fusing profiles are both retrieved on different vertical grids and referred to different true profiles. The impact of the interpolation and coincidence errors on number of degrees of freedom and errors of the fused profile is also analysed. The approach developed here to account for the interpolation and coincidence errors can also be followed to include other error components, such as forward model errors.

  16. A training and educational tool for neutron coincidence measurements

    International Nuclear Information System (INIS)

    Huszti, J.; Bagi, J.; Langner, D.

    2009-01-01

    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)

  17. Data acquisition and processing system for coincidence measurements

    International Nuclear Information System (INIS)

    Li Xu

    1990-07-01

    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%

  18. On the structure of the set of coincidence points

    Energy Technology Data Exchange (ETDEWEB)

    Arutyunov, A V [Peoples Friendship University of Russia, Moscow (Russian Federation); Gel' man, B D [Voronezh State University (Russian Federation)

    2015-03-31

    We consider the set of coincidence points for two maps between metric spaces. Cardinality, metric and topological properties of the coincidence set are studied. We obtain conditions which guarantee that this set (a) consists of at least two points; (b) consists of at least n points; (c) contains a countable subset; (d) is uncountable. The results are applied to study the structure of the double point set and the fixed point set for multivalued contractions. Bibliography: 12 titles.

  19. On neutron activation analysis with γγ coincidence spectrometry

    International Nuclear Information System (INIS)

    Zeisler, Rolf; Danyal Turkoglu; Ibere Souza Ribeiro Junior; Shetty, M.G.

    2017-01-01

    A new γγ coincidence system has been set up at NIST. It is operated with a digital data finder supported by new software developed at NIST. The system is used to explore possible enhancements in instrumental neutron activation analysis (INAA) and study applicability to neutron capture prompt gamma activation analysis (PGAA). The performance of the system is tested with certified reference materials for efficiency calibration and quantitative performance. Comparisons of INAA results based on conventional gamma-ray spectrometry data with INAA results based on coincidence data obtained from the same samples show improvements in the counting uncertainties and demonstrates the quantitative accuracy of the new system. (author)

  20. Automatic classification of gammas-gamma coincidence matrices

    International Nuclear Information System (INIS)

    Los Arcos Merino, J. M.; Gonzalez, J. A.

    1978-01-01

    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)

    Los Arcos Merino, J.M.; Gonzalez Gonzalez, J.A.

    1978-01-01

    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. Comparative study of chance coincidence correction in measuring 223Ra and 224Ra by delay coincidence method

    International Nuclear Information System (INIS)

    Yan Yongjun; Huang Derong; Zhou Jianliang; Qiu Shoukang

    2013-01-01

    The delay coincidence measurement of 220 Rn and 219 Rn has been proved to be a valid indirect method for measuring 224 Ra and 223 Ra extracted from natural water, which can provide valuable information on estuarine/ocean mixing, submarine groundwater discharge, and water/soil interactions. In practical operation chance coincidence correction must be considered, mostly Moore's correction method, but Moore's and Giffin's methods were incomplete in some ways. In this paper the modification (method 1) and a new chance coincidence correction formula (method 2) were provided. Experiments results are presented to demonstrate the conclusions. The results show that precision is improved while counting rate is less than 70 min- 1 . (authors)

  3. Modeling of LMM-MVV Auger-Auger Coincidence Spectra From Solids

    Science.gov (United States)

    Sundaramoorthy, R.; Weiss, A. H.; Hulbert, S. L.; Bartynski, R. A.

    2006-03-01

    Atoms that are highly excited due to the presence of a hole in an inner shell often relax via an Auger transition. This auto-ionizing process results in a final state with two or more holes from an Auger cascade. We present results of the direct measurements of the second and third Auger decays in this sequence. We have measured the Mn MVV Auger spectra from a single-crystal sample of MnO in time coincidence with Auger electrons emitted from prior Mn LMM Auger decays and find these to be much wider than the MVV spectrum measured in time coincidence with M core photoelectron emission. We present a model which attributes the increased energy width of the MVV transitions that follow LMM decays to the rearrangement of ``not so innocent'' bystander hole(s) in the valence band. The energetics of the Auger cascade process are modeled mathematically in terms of correlation integral(s) and convolution integral(s) over the valence band density of states. Comparisons with recent Auger-Auger coincidence studies of Ag and Pd will be made. Acknowledgements: Welch Foundation, NSF DMR98-12628, NSF DMR98-01681, and DOE DE-AC02-98CH10886.

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

    International Nuclear Information System (INIS)

    Smith, B.G.R.; Outram, J.D.; Storey, M.

    1991-01-01

    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 of 240 Pu 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 240 Pu 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

  5. Standardization of Ga-68 by coincidence measurements, liquid scintillation counting and 4πγ counting

    International Nuclear Information System (INIS)

    Roteta, Miguel; Peyres, Virginia; Rodríguez Barquero, Leonor; García-Toraño, Eduardo; Arenillas, Pablo; Balpardo, Christian; Rodrígues, Darío; Llovera, Roberto

    2012-01-01

    The radionuclide 68 Ga is one of the few positron emitters that can be prepared in-house without the use of a cyclotron. It disintegrates to the ground state of 68 Zn partially by positron emission (89.1%) with a maximum energy of 1899.1 keV, and partially by electron capture (10.9%). This nuclide has been standardized in the frame of a cooperation project between the Radionuclide Metrology laboratories from CIEMAT (Spain) and CNEA (Argentina). Measurements involved several techniques: 4πβ−γ coincidences, integral gamma counting and Liquid Scintillation Counting using the triple to double coincidence ratio and the CIEMAT/NIST methods. Given the short half-life of the radionuclide assayed, a direct comparison between results from both laboratories was excluded and a comparison of experimental efficiencies of similar NaI detectors was used instead. - Highlights: ► We standardized the positron emitter Ga-68 in a bilateral cooperation. ► We used several techniques, as coincidence, integral gamma and liquid scintillation. ► An efficiency comparison replaced a direct comparison of reference materials.

  6. Standardisation of {sup 18}F by a coincidence method using full solid angle detectors

    Energy Technology Data Exchange (ETDEWEB)

    Nedjadi, Youcef, E-mail: youcef.nedjadi@chuv.c [Institut de Radiophysique Appliquee, Grand Pre 1, 1007 Lausanne (Switzerland); Bailat, Claude; Caffari, Yvan; Bochud, Francois [Institut de Radiophysique Appliquee, Grand Pre 1, 1007 Lausanne (Switzerland)

    2010-07-15

    A solution of {sup 18}F was standardised with a 4{pi}{beta}-4{pi}{gamma} coincidence counting system in which the beta detector is a one-inch diameter cylindrical UPS89 plastic scintillator, positioned at the bottom of a well-type 5''x5'' NaI(Tl) gamma-ray detector. Almost full detection efficiency-which was varied downwards electronically-was achieved in the beta-channel. Aliquots of this {sup 18}F solution were also measured using 4{pi}{gamma} NaI(Tl) integral counting and Monte Carlo calculated efficiencies as well as the CIEMAT-NIST method. Secondary measurements of the same solution were also performed with an IG11 ionisation chamber whose equivalent activity is traceable to the Systeme International de Reference through the contribution IRA-METAS made to it in 2001; IRA's degree of equivalence was found to be close to the key comparison reference value (KCRV). The {sup 18}F activity predicted by this coincidence system agrees closely with the ionisation chamber measurement and is compatible within one standard deviation of the other primary measurements. This work demonstrates that our new coincidence system can standardise short-lived radionuclides used in nuclear medicine.

  7. Disintegration rate of Tc -99m and In -111 radioactive solutions in coincidence systems

    International Nuclear Information System (INIS)

    Brito, Andreia Barreto de

    2011-01-01

    The 111 In and 99 mTc standardization in a 4πβ-γ coincidence system is described. The 111 In was produced by the reaction of 111 Cd (p, n) 111 In in the cyclotron. The 111 In decays with a half life of 2.8 days by electron capture process, populating the excited levels of 111 Cd, emitting two main gamma rays with energies of 171 keV and 245 keV. The 99m Tc decay with a half life of 6.007 h for isomeric transition, from the radioactive decay of 99 Mo. 111 In standardization was carried out in a 4πβ-γ system, consisted of a gas flow proportional counter with 4π geometry coupled to a pair of NaI(Tl) scintillation counter with conventional electronics. The gamma window was set comprising the (171 keV + 245 keV) total absorption energy peaks. The choice of the window was based on the analysis of the extrapolation curves prediction, obtained by Monte Carlo simulation. The 99 mTc standardization has been accomplished by the 4πβ-γ coincidence method using a thin window proportional counter in a 4π geometry coupled to a single NaI(Tl) scintillation counter. The beta efficiency was varied by electronic discrimination using a software coincidence counting system (SCS). Two windows were selected for the gamma channel: one at 140 keV gamma ray and the other at 20 keV X ray total absorption peaks. The result of the experimental activity of 111 In two solutions agree with the results obtained by Monte Carlo simulation. The experimental activities of 99m Tc for the two gamma windows are in agreement within the experimental uncertainty, indicating that the adopted methodology is adequate. (author)

  8. Optical Co-Incidence Gate | Srinivasulu | African Journal of Science ...

    African Journals Online (AJOL)

    The paper explains Optical co-incidence gate, realized using Unijunction transistors (UJT), Light emitting diodes (LED) and Photo-resistors (LDR), which works on 1.8Vdc instead of 3Vdc. The power dissipation of the designed gate is only 3 mW. This optical gate finds application in the field of Mechatronics, Instrumentation ...

  9. Positron two-photon annihilation coincidence technique: difference mode

    Energy Technology Data Exchange (ETDEWEB)

    Karol, P J; Klobuchar, R L [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA). Dept. of Chemistry

    1978-05-01

    A difference (or comparative) mode in the measurement of two-photon coincidences from positron or positronium annihilation has been developed. The method can be used to advantage, particularly in gases, in determining annihilation parameters such as quenching cross sections for low concentration strongly quenching chemical species in a reference medium which is relatively non-quenching.

  10. Analysis of (HI, xnγ) coincidence spectra

    International Nuclear Information System (INIS)

    Pattabiraman, N.S.; Ghugre, S.S.; Chintalapudi, S.N.

    2000-01-01

    The increase in the sensitivity and the detection limits of the modern third generation gamma detector arrays, has made it necessary to properly understand and estimate the observed background in such experiments. The present paper extends the two algorithms to improve the genuine photo-peak-photo-peak coincident events of interest

  11. A {beta} - {gamma} coincidence; Metodo de coincidencias {beta} - {gamma}

    Energy Technology Data Exchange (ETDEWEB)

    Agullo, F

    1960-07-01

    A {beta} - {gamma} coincidence method for absolute counting is given. The fundamental principles are revised and the experimental part is detailed. The results from {sup 1}98 Au irradiated in the JEN 1 Swimming pool reactor are given. The maximal accuracy is 1 per cent. (Author) 11 refs.

  12. Chemical application of positron annihilation through triple coincidence measurement

    International Nuclear Information System (INIS)

    Yegnasubramanian, S.; Gangadharan, S.

    1982-01-01

    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)

  13. Standardization of {sup 241}Am by digital coincidence counting, liquid scintillation counting and defined solid angle counting

    Energy Technology Data Exchange (ETDEWEB)

    Balpardo, C., E-mail: balpardo@cae.cnea.gov.a [Laboratorio de Metrologia de Radioisotopos, CNEA, Buenos Aires (Argentina); Capoulat, M.E.; Rodrigues, D.; Arenillas, P. [Laboratorio de Metrologia de Radioisotopos, CNEA, Buenos Aires (Argentina)

    2010-07-15

    The nuclide {sup 241}Am decays by alpha emission to {sup 237}Np. Most of the decays (84.6%) populate the excited level of {sup 237}Np with energy of 59.54 keV. Digital coincidence counting was applied to standardize a solution of {sup 241}Am 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.

  14. Xe isotope detection and discrimination using beta spectroscopy with coincident gamma spectroscopy

    Science.gov (United States)

    Reeder, P. L.; Bowyer, T. W.

    1998-02-01

    Beta spectroscopic techniques show promise of significant improvements for a beta-gamma coincidence counter that is part of a system for analyzing Xe automatically separated from air. The previously developed counting system for 131mXe, 133mXe, 133gXe, and 135gXe can be enhanced to give additional discrimination between these Xe isotopes by using the plastic scintillation sample cell as a beta spectrometer to resolve the conversion electron peaks. The automated system will be a key factor in monitoring the Comprehensive Test Ban Treaty.

  15. 3D Silicon Coincidence Avalanche Detector (3D-SiCAD) for charged particle detection

    Science.gov (United States)

    Vignetti, M. M.; Calmon, F.; Pittet, P.; Pares, G.; Cellier, R.; Quiquerez, L.; Chaves de Albuquerque, T.; Bechetoille, E.; Testa, E.; Lopez, J.-P.; Dauvergne, D.; Savoy-Navarro, A.

    2018-02-01

    Single-Photon Avalanche Diodes (SPADs) are p-n junctions operated in Geiger Mode by applying a reverse bias above the breakdown voltage. SPADs have the advantage of featuring single photon sensitivity with timing resolution in the picoseconds range. Nevertheless, their relatively high Dark Count Rate (DCR) is a major issue for charged particle detection, especially when it is much higher than the incoming particle rate. To tackle this issue, we have developed a 3D Silicon Coincidence Avalanche Detector (3D-SiCAD). This novel device implements two vertically aligned SPADs featuring on-chip electronics for the detection of coincident avalanche events occurring on both SPADs. Such a coincidence detection mode allows an efficient discrimination of events related to an incoming charged particle (producing a quasi-simultaneous activation of both SPADs) from dark counts occurring independently on each SPAD. A 3D-SiCAD detector prototype has been fabricated in CMOS technology adopting a 3D flip-chip integration technique, and the main results of its characterization are reported in this work. The particle detection efficiency and noise rejection capability for this novel device have been evaluated by means of a β- strontium-90 radioactive source. Moreover the impact of the main operating parameters (i.e. the hold-off time, the coincidence window duration, the SPAD excess bias voltage) over the particle detection efficiency has been studied. Measurements have been performed with different β- particles rates and show that a 3D-SiCAD device outperforms single SPAD detectors: the former is indeed capable to detect particle rates much lower than the individual DCR observed in a single SPAD-based detectors (i.e. 2 to 3 orders of magnitudes lower).

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

    International Nuclear Information System (INIS)

    Piuvezam Filho, Helio

    2007-01-01

    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)

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

    International Nuclear Information System (INIS)

    Al-Azmi, Darwish

    2008-01-01

    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

  18. Device for multi-dimensional γ-γ-coincidence study

    International Nuclear Information System (INIS)

    Gruzinova, T.M.; Erokhina, K.I.; Kutuzov, V.I.; Lemberg, I.Kh.; Petrov, S.A.; Revenko, V.S.; Senin, A.T.; Chugunov, I.N.; Shishlinov, V.M.

    1977-01-01

    A device for studying multi-dimensional γ-γ coincidences is described which operates on-line with the BESM-4 computer. The device comprises Ge(Li) detectors, analog-to-digital converters, shaper discriminators and fast amplifiers. To control the device operation as a whole and to elaborate necessary commands, an information distributor has been developed. The following specific features of the device operation are noted: the device may operate both in the regime of recording spectra of direct γ radiation in the block memory of multi-channel analyzer, and in the regime of data transfer to the computer memory; the device performs registration of coincidences; it transfers information to the computer which has a channel of direct access to the memory. The procedure of data processing is considered, the data being recorded on a magnetic tape. Partial spectra obtained are in a good agreement with data obtained elsewhere

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

    International Nuclear Information System (INIS)

    Ferrari, Francesca; Peerani, Paolo

    2010-01-01

    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 235 U 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.

  20. 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.

  1. Alpha-Photon Coincidence Spectroscopy Along Element 115 Decay Chains

    Energy Technology Data Exchange (ETDEWEB)

    Rudolph, D. [Lund Univ., Lund (Sweden); Forsberg, U. [Lund Univ., Lund (Sweden); Golubev, P. [Lund Univ., Lund (Sweden); Sarmiento, L. G. [Lund Univ., Lund (Sweden); Yakushev, A. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Andersson, L. -L. [Helmholtz Institute Mainz, Mainz (Germany); Di Nitto, A. [Johannes Gutenberg-Univ. Mainz, Mainz (Germany); Dullmann, Ch. E. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Helmholtz Institute Mainz, Mainz (Germany); Johannes Gutenberg-Univ. Mainz, Mainz (Germany); Gates, J. M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gregorich, K. E. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gross, C. J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Herzberg, R. -D. [Univ. of Liverpool, Liverpool (United Kingdom); Hessberger, F. P. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Helmholtz Institute Mainz, Mainz (Germany); Khuyagbaatar, J. [Helmholtz Institute Mainz, Mainz (Germany); Kratz, J. V. [Johannes Gutenberg-Univ. Mainz, Mainz (Germany); Rykaczewski, K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Schadel, M. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Japan Atomic Energy Agency, Tokai (Japan); Aberg, S. [Lund Univ., Lund (Sweden); Ackermann, D. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Block, M. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Brand, H. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Carlsson, B. G. [Lund Univ., Lund (Sweden); Cox, D. [Univ. of Liverpool, Liverpool (United Kingdom); Derkx, X. [Helmholtz Institute Mainz, Mainz (Germany); Johannes Gutenberg-Univ. Mainz, Mainz (Germany); Eberhardt, K. [Helmholtz Institute Mainz, Mainz (Germany); Johannes Gutenberg-Univ. Mainz, Mainz (Germany); Even, J. [Helmholtz Institute Mainz, Mainz (Germany); Fahlander, C. [Lund Univ., Lund (Sweden); Gerl, J. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Jager, E. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Kindler, B. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Krier, J. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Kojouharov, I. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Kurz, N. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Lommel, B. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Mistry, A. [Univ. of Liverpool, Liverpool (United Kingdom); Mokry, C. [Helmholtz Institute Mainz, Mainz (Germany); Johannes Gutenberg-Univ. Mainz, Mainz (Germany); Nitsche, H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Omtvedt, J. P. [Univ. of Oslo, Oslo (Norway); Papadakis, P. [Univ. of Liverpool, Liverpool (United Kingdom); Ragnarsson, I. [Lund Univ., Lund (Sweden); Runke, J. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Schaffner, H. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Schausten, B. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Thorle-Pospiech, P. [Helmholtz Institute Mainz, Mainz (Germany); Johannes Gutenberg-Univ. Mainz, Mainz (Germany); Torres, T. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Traut, T. [Johannes Gutenberg-Univ. Mainz, Mainz (Germany); Trautmann, N. [Johannes Gutenberg-Univ. Mainz, Mainz (Germany); Turler, A. [Paul Scherrer Institute and Univ. of Bern, Villigen (Switzerland); Ward, A. [Univ. of Liverpool, Liverpool (United Kingdom); Ward, D. E. [Lund Univ., Lund (Sweden); Wiehl, N. [Helmholtz Institute Mainz, Mainz (Germany); Johannes Gutenberg-Univ. Mainz, Mainz (Germany)

    2014-01-01

    Produced in the reaction 48Ca+ 243Am, thirty correlated α-decay chains were observed in an experiment conducted at the GSI Helmholzzentrum für Schwerionenforschung, Darmstadt, Germany. The decay chains are basically consistent with previous findings and are considered to originate from isotopes of element 115 with mass numbers 287, 288, and 289. A set-up aiming specifically for high-resolution charged particle and photon coincidence spectroscopy was placed behind the gas-filled separator TASCA. For the first time, γ rays as well as X-ray candidates were observed in prompt coincidence with the α-decay chains of element 115.

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

    International Nuclear Information System (INIS)

    Krick, M.S.; Menlove, H.O.

    1979-06-01

    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 240 Pu 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

  3. Coincidence of asthma and bronchospasm during anesthesia in tympanomastoidectomy.

    OpenAIRE

    Nima Hosseinzadeh; Shahram Samadi; Amin Amali; Mihan Jafari Javid

    2014-01-01

    High prevalence of asthma and bronchospasm was observed during induction of anesthesia in patients with chronic suppurative otitis mMedia (CSOM) who underwent tympanomastoidectomy. Although several studies have proposed association of allergic diseases with CSOM but no consensus about it has been established. Current study was designed to determine the coincidence of asthma in CSOM patients. In a cross-sectional study, authors investigated medical records of 106 CSOM patients underwent tympan...

  4. Energy and depth resolution in elastic recoil coincidence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Szilagyi, E., E-mail: szilagyi@rmki.kfki.h [KFKI Research Institute for Particle and Nuclear Physics, P.O. Box 49, H-1525 Budapest (Hungary)

    2010-06-15

    Elastic recoil coincidence spectrometry was implemented into the analytical ion beam simulation program DEPTH. In the calculations, effective detector geometry and multiple scattering effects are considered. Mott's cross section for the identical, spin zero particles is included. Spectra based on the individual detector signal and summing the energy of the recoiled and scattered particles originating from the same scattering events can also be calculated. To calculate this latter case, the dependency of the energy spread contributions had to be reconsidered.

  5. Energy and depth resolution in elastic recoil coincidence spectrometry

    International Nuclear Information System (INIS)

    Szilagyi, E.

    2010-01-01

    Elastic recoil coincidence spectrometry was implemented into the analytical ion beam simulation program DEPTH. In the calculations, effective detector geometry and multiple scattering effects are considered. Mott's cross section for the identical, spin zero particles is included. Spectra based on the individual detector signal and summing the energy of the recoiled and scattered particles originating from the same scattering events can also be calculated. To calculate this latter case, the dependency of the energy spread contributions had to be reconsidered.

  6. Monte Carlo simulation of {beta}-{gamma} coincidence system using plastic scintillators in 4{pi} geometry

    Energy Technology Data Exchange (ETDEWEB)

    Dias, M.S. [Instituto de Pesquisas Energeticas e Nucleares: IPEN-CNEN/SP, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo, SP (Brazil)], E-mail: msdias@ipen.br; Piuvezam-Filho, H. [Instituto de Pesquisas Energeticas e Nucleares: IPEN-CNEN/SP, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo, SP (Brazil); Baccarelli, A.M. [Departamento de Fisica-PUC/SP-Rua Marques de Paranagua 111, 01303-050 Sao Paulo, SP (Brazil); Takeda, M.N. [Universidade Santo Amaro, UNISA-Rua Prof. Eneas da Siqueira Neto 340, 04829-300 Sao Paulo, SP (Brazil); Koskinas, M.F. [Instituto de Pesquisas Energeticas e Nucleares: IPEN-CNEN/SP, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo, SP (Brazil)

    2007-09-21

    A modified version of a Monte Carlo code called Esquema, developed at the Nuclear Metrology Laboratory in IPEN, Sao Paulo, Brazil, has been applied for simulating a 4{pi}{beta}(PS)-{gamma} coincidence system designed for primary radionuclide standardisation. This system consists of a plastic scintillator in 4{pi} geometry, for alpha or electron detection, coupled to a NaI(Tl) counter for gamma-ray detection. The response curves for monoenergetic electrons and photons have been calculated previously by Penelope code and applied as input data to code Esquema. The latter code simulates all the disintegration processes, from the precursor nucleus to the ground state of the daughter radionuclide. As a result, the curve between the observed disintegration rate as a function of the beta efficiency parameter can be simulated. A least-squares fit between the experimental activity values and the Monte Carlo calculation provided the actual radioactive source activity, without need of conventional extrapolation procedures. Application of this methodology to {sup 60}Co and {sup 133}Ba radioactive sources is presented and showed results in good agreement with a conventional proportional counter 4{pi}{beta}(PC)-{gamma} coincidence system.

  7. Monte Carlo simulation of β-γ coincidence system using plastic scintillators in 4π geometry

    International Nuclear Information System (INIS)

    Dias, M.S.; Piuvezam-Filho, H.; Baccarelli, A.M.; Takeda, M.N.; Koskinas, M.F.

    2007-01-01

    A modified version of a Monte Carlo code called Esquema, developed at the Nuclear Metrology Laboratory in IPEN, Sao Paulo, Brazil, has been applied for simulating a 4πβ(PS)-γ coincidence system designed for primary radionuclide standardisation. This system consists of a plastic scintillator in 4π geometry, for alpha or electron detection, coupled to a NaI(Tl) counter for gamma-ray detection. The response curves for monoenergetic electrons and photons have been calculated previously by Penelope code and applied as input data to code Esquema. The latter code simulates all the disintegration processes, from the precursor nucleus to the ground state of the daughter radionuclide. As a result, the curve between the observed disintegration rate as a function of the beta efficiency parameter can be simulated. A least-squares fit between the experimental activity values and the Monte Carlo calculation provided the actual radioactive source activity, without need of conventional extrapolation procedures. Application of this methodology to 60 Co and 133 Ba radioactive sources is presented and showed results in good agreement with a conventional proportional counter 4πβ(PC)-γ coincidence system

  8. Coincidence summing corrections for positron emitters in germanium gamma spectrometry

    International Nuclear Information System (INIS)

    Richardson, A.E.; Sallee, W.W.; New Mexico State Univ., Las Cruces

    1990-01-01

    For positron emitters, 511 keV annihilation quanta are in coincidence with other gamma rays in the decay scheme. If the positrons are not localized at the point of decay, annihilation quanta will be produced at a site some distance from the point of emission. The magnitude of the summing coincidence effect will depend upon the position of annihilation. A method for determining the magnitude of the summing effect for a single gamma of energy E in coincidence with the annihilation gammas from non-localized positrons has been developed which makes use of the counting data for the full energy peaks for both the gamma ray (E) and the 511 keV annihilation gammas. With this data and efficiency calibration data one can determine the average total efficiency for the annihilation positions from which 511 keV gammas originate, and thereby obtain the summing correction factor, SCF, for gamma ray (E). Application of the method to a 22 Na NIST standard gave excellent agreement of observed emission rates for the 1275 keV gamma with the NIST value for wide ranging degrees of positron localization having summing correction factors ranging from 1.021 to 1.505. The method was also applied successfully to 58 Co in neutron-irradiated nickel foils. The method shows promise as a check on the accuracy of the efficiency calibration for a particular detector geometry at the 511 keV energy and energies for other gammas associated with positron emission. (orig.)

  9. Importance of interpolation and coincidence errors in data fusion

    Directory of Open Access Journals (Sweden)

    S. Ceccherini

    2018-02-01

    Full Text Available The complete data fusion (CDF method is applied to ozone profiles obtained from simulated measurements in the ultraviolet and in the thermal infrared in the framework of the Sentinel 4 mission of the Copernicus programme. We observe that the quality of the fused products is degraded when the fusing profiles are either retrieved on different vertical grids or referred to different true profiles. To address this shortcoming, a generalization of the complete data fusion method, which takes into account interpolation and coincidence errors, is presented. This upgrade overcomes the encountered problems and provides products of good quality when the fusing profiles are both retrieved on different vertical grids and referred to different true profiles. The impact of the interpolation and coincidence errors on number of degrees of freedom and errors of the fused profile is also analysed. The approach developed here to account for the interpolation and coincidence errors can also be followed to include other error components, such as forward model errors.

  10. High sensitivity neutron activation analysis using coincidence counting method

    International Nuclear Information System (INIS)

    Suzuki, Shogo; Okada, Yukiko; Hirai, Shoji

    1999-01-01

    Four kinds of standard samples such as river sediment (NIES CRM No.16), Typical Japanese Diet, otoliths and river water were irradiated by TRIGA-II (100 kW, 3.7x10 12 n cm -2 s -1 ) for 6 h. After irradiation and cooling, they were analyzed by the coincidence counting method and a conventional γ-ray spectrometry. Se, Ba and Hf were determined by 75 Se 265 keV, 131 Ba 496 keV and 181 Hf 482 keV. On the river sediment sample, Ba and Hf showed the same values by two methods, but Se value contained Ta by the conventional method, although the coincidence counting method could analyze Se. On Typical Japanese Diet and otoliths, Se could be determined by two methods and Ba and Hf determined by the coincidence counting method but not determined by the conventional method. Se value in the river water agreed with the authorization value. (S.Y.)

  11. Recent Advances in Digital Coincidence Counting for Radionuclide Metrology

    International Nuclear Information System (INIS)

    Keightley, John; Bobin, Christophe; Bouchard, Jacques; Capogni, Marco; Loreti, Stefano; Roteta, Miguel

    2013-06-01

    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 10 8 to 10 9 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)

  12. Post training REMs coincident auditory stimulation enhances memory in humans.

    Science.gov (United States)

    Smith, C; Weeden, K

    1990-06-01

    Sleep activity was monitored in 20 freshman college students for two consecutive nights. Subjects were assigned to 4 equal groups and all were asked to learn a complex logic task before bed on the second night. Two groups of subjects learned the task with a constant clicking noise in the background (cued groups), while two groups simply learned the task (non cued). During the night, one cued and one non cued group were presented with auditory clicks during REM sleep such as to coincide with all REMs of at least 100 microvolts. The second cued group was given auditory clicks during REM sleep, but only during the REMs "quiet" times. The second non-cued control group was never given any nighttime auditory stimulations. The cued REMs coincident group showed a significant 23% improvement in task performance when tested one week later. The non cued REMs coincident group showed only an 8.8% improvement which was not significant. The cued REMs quiet and non-stimulated control groups showed no change in task performance when retested. The results were interpreted as support for the idea that the cued auditory stimulation induced a "recall" of the learned material during the REM sleep state in order for further memory processing to take place.

  13. Simulation approach to coincidence summing in {gamma}-ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Dziri, S., E-mail: samir.dziri@iphc.cnrs.fr [Groupe RaMsEs, Institut Pluridisciplinaire Hubert Curien (IPHC), University of Strasbourg, CNRS, IN2P3, UMR 7178, 23 rue de Loess, BP 28, 67037 Strasbourg Cedex 2 (France); Nourreddine, A.; Sellam, A.; Pape, A.; Baussan, E. [Groupe RaMsEs, Institut Pluridisciplinaire Hubert Curien (IPHC), University of Strasbourg, CNRS, IN2P3, UMR 7178, 23 rue de Loess, BP 28, 67037 Strasbourg Cedex 2 (France)

    2012-07-15

    Some of the radionuclides used for efficiency calibration of a HPGe spectrometer are subject to coincidence-summing (CS) and account must be taken of the phenomenon to obtain quantitative results when counting samples to determine their activity. We have used MCNPX simulations, which do not take CS into account, to obtain {gamma}-ray peak intensities that were compared to those observed experimentally. The loss or gain of a measured peak intensity relative to the simulated peak is attributed to CS. CS correction factors are compared with those of ETNA and GESPECOR. Application to a test sample prepared with known radionuclides gave values close to the published activities. - Highlights: Black-Right-Pointing-Pointer Coincidence summing occurs when the solid angle is increased. Black-Right-Pointing-Pointer The loss of counts gives rise to an approximative efficiency curves, this means a wrong quantitative data. Black-Right-Pointing-Pointer To overcome this problem we need mono-energetic source, otherwise, the MCNPX simulation allows by comparison with the experiment data to get the coincidence summing correction factors. Black-Right-Pointing-Pointer By multiplying these factors by the approximative efficiency, we obtain the accurate efficiency.

  14. Improvements of low-level radioxenon detection sensitivity by a state-of-the art coincidence setup.

    Science.gov (United States)

    Cagniant, A; Le Petit, G; Gross, P; Douysset, G; Richard-Bressand, H; Fontaine, J-P

    2014-05-01

    The ability to quantify isotopic ratios of 135, 133 m, 133 and 131 m radioxenon is essential for the verification of the Comprehensive Nuclear-Test Ban Treaty (CTBT). In order to improve detection limits, CEA has developed a new on-site setup using photon/electron coincidence (Le Petit et al., 2013. J. Radioanal. Nucl. Chem., DOI : 10.1007/s 10697-013-2525-8.). Alternatively, the electron detection cell equipped with large silicon chips (PIPS) can be used with HPGe detector for laboratory analysis purpose. This setup allows the measurement of β/γ coincidences for the detection of (133)Xe and (135)Xe; and K-shell Conversion Electrons (K-CE)/X-ray coincidences for the detection of (131m)Xe, (133m)Xe and (133)Xe as well. Good energy resolution of 11 keV at 130 keV and low energy threshold of 29 keV for the electron detection were obtained. This provides direct discrimination between K-CE from (133)Xe, (133m)Xe and (131m)Xe. Estimation of Minimum Detectable Activity (MDA) for (131m)Xe is in the order of 1mBq over a 4 day measurement. An analysis of an environmental radioxenon sample using this method is shown. © 2013 The Authors. Published by Elsevier Ltd All rights reserved.

  15. 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 somme des amplitudes des impulsions

  16. Coincident brane nucleation and the neutralization of Λ

    International Nuclear Information System (INIS)

    Garriga, Jaume; Megevand, Ariel

    2004-01-01

    Nucleation of branes by a four-form field has recently been considered in string motivated scenarios for the neutralization of the cosmological constant. An interesting question in this context is whether the nucleation of stacks of coincident branes is possible, and if so, at what rate does it proceed. Feng et al. have suggested that, at high ambient de Sitter temperature, the rate may be strongly enhanced, due to large degeneracy factors associated with the number of light species living on the worldsheet. This might facilitate the quick relaxation from a large effective cosmological constant down to the observed value. Here, we analyze this possibility in some detail. In four dimensions, and after the moduli are stabilized, branes interact via repulsive long range forces. Because of that, the Coleman-de Luccia (CdL) instanton for coincident brane nucleation may not exist, unless there is some short range interaction that keeps the branes together. If the CdL instanton exists, we find that the degeneracy factor depends only mildly on the ambient de Sitter temperature, and does not switch off even in the case of tunneling from flat space. This would result in catastrophic decay of the present vacuum. If, on the contrary, the CdL instanton does not exist, coincident brane nucleation may still proceed through a 'static' instanton, representing pair creation of critical bubbles--a process somewhat analogous to thermal activation in flat space. In that case, the branes may stick together due to thermal symmetry restoration, and the pair creation rate depends exponentially on the ambient de Sitter temperature, switching off sharply as the temperature approaches zero. Such a static instanton may be well suited for the 'saltatory' relaxation scenario proposed by Feng et al

  17. Bell's inequalities and the four-coincidence experiment

    International Nuclear Information System (INIS)

    Garuccio, A.; Rapisarda, V.A.

    1981-01-01

    The four-coincidence experiment, in which two correlated particles interact, each, with a dichotomic-detection apparatus, is formally described. Some care is devoted to analyze what is due to the structure of the experiment, and what can really be measured. Some of the questions which the experiment can answer are posed in a general probabilistic hidden-variable frame and, for the QM point of view, in the specific case of the 0-1-0 calcium atomic cascade. Besides, a new method to treat discriminating inequalities is shown which allows, in our opinion, a deeper insight into the theoretical assumptions together with a better experimental reliability. (author)

  18. Reconstructed Image Spatial Resolution of Multiple Coincidences Compton Imager

    Science.gov (United States)

    Andreyev, Andriy; Sitek, Arkadiusz; Celler, Anna

    2010-02-01

    We study the multiple coincidences Compton imager (MCCI) which is based on a simultaneous acquisition of several photons emitted in cascade from a single nuclear decay. Theoretically, this technique should provide a major improvement in localization of a single radioactive source as compared to a standard Compton camera. In this work, we investigated the performance and limitations of MCCI using Monte Carlo computer simulations. Spatial resolutions of the reconstructed point source have been studied as a function of the MCCI parameters, including geometrical dimensions and detector characteristics such as materials, energy and spatial resolutions.

  19. Coincident systemic lupus erythematosus and psoriasis vulgaris: a case report.

    Science.gov (United States)

    Wang, Y; Da, G; Yu, Y; Han, J; Li, H

    2015-12-01

    Psoriasis vulgaris is an autoimmune chronic inflammatory skin disease, but its association with other typical autoimmune disease such as systemic lupus erythematosus has only occasionally been reported. We presented a 25-year-old female who developed systemic lupus erythematosus associated with psoriasis vulgaris. Her conditions were in good control after she got administration of prednisolone (5 mg/day) and Tripterygium Wilfordii Hook (20 mg/day). It is necessary to integrate past history and physical examination to diagnose coincident SLE and psoriasis, and combined treatment with prednisolone and Tripterygium Wilfordii Hook proves effective.

  20. Coincidence corrected efficiency calibration of Compton-suppressed HPGe detectors

    Energy Technology Data Exchange (ETDEWEB)

    Aucott, Timothy [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Brand, Alexander [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); DiPrete, David [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-04-20

    The authors present a reliable method to calibrate the full-energy efficiency and the coincidence correction factors using a commonly-available mixed source gamma standard. This is accomplished by measuring the peak areas from both summing and non-summing decay schemes and simultaneously fitting both the full-energy efficiency, as well as the total efficiency, as functions of energy. By using known decay schemes, these functions can then be used to provide correction factors for other nuclides not included in the calibration standard.

  1. Preliminary results of a neutron-gamma coincidence experiment

    International Nuclear Information System (INIS)

    Piercey, R.B.; Dunnam, F.E.; Muga, M.L.; Rester, A.C.; Ramayya, A.V.; Hamilton, J.H.; Eberth, J.; Zganjar, E.F.

    1984-01-01

    The recently completed neutron multiplicity detector dubbed PANDA (Pentagonal Annular Neutron Detector Array) is fully described later in this report. The new detector was recently used for the first time on-line at the Holifield Heavy Ion Research Facility to measure neutron-gamma coincidence in the 24 Mg( 58 Ni,xαypzn) reaction. The detector configuration for the experiment is shown. The PANDA was situated in the forward direction, coaxial to the beam line with five gamma-ray detectors placed at +/- 90 0 , +/- 135 0 , and 0 0 . 2 figures

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

    International Nuclear Information System (INIS)

    Urban, S.; Urbanova, S.

    1988-01-01

    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

  3. 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.

  4. Cochlear spike synchronization and neuron coincidence detection model

    Science.gov (United States)

    Bader, Rolf

    2018-02-01

    Coincidence detection of a spike pattern fed from the cochlea into a single neuron is investigated using a physical Finite-Difference model of the cochlea and a physiologically motivated neuron model. Previous studies have shown experimental evidence of increased spike synchronization in the nucleus cochlearis and the trapezoid body [Joris et al., J. Neurophysiol. 71(3), 1022-1036 and 1037-1051 (1994)] and models show tone partial phase synchronization at the transition from mechanical waves on the basilar membrane into spike patterns [Ch. F. Babbs, J. Biophys. 2011, 435135]. Still the traveling speed of waves on the basilar membrane cause a frequency-dependent time delay of simultaneously incoming sound wavefronts up to 10 ms. The present model shows nearly perfect synchronization of multiple spike inputs as neuron outputs with interspike intervals (ISI) at the periodicity of the incoming sound for frequencies from about 30 to 300 Hz for two different amounts of afferent nerve fiber neuron inputs. Coincidence detection serves here as a fusion of multiple inputs into one single event enhancing pitch periodicity detection for low frequencies, impulse detection, or increased sound or speech intelligibility due to dereverberation.

  5. Performance of a coincidence based blood activity monitor

    International Nuclear Information System (INIS)

    Moses, W.W.

    1989-12-01

    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 18 F 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

  6. Coincidence-anticipation timing requirements are different in racket sports.

    Science.gov (United States)

    Akpinar, Selçuk; Devrilmez, Erhan; Kirazci, Sadettin

    2012-10-01

    The aim of this study was to compare the coincidence-anticipation timing accuracy of athletes of different racket sports with various stimulus velocity requirements. Ninety players (15 girls, 15 boys for each sport) from tennis (M age = 12.4 yr., SD = 1.4), badminton (M age = 12.5 yr., SD = 1.4), and table tennis (M age = 12.4 yr., SD = 1.2) participated in this study. Three different stimulus velocities, low, moderate, and high, were used to simulate the velocity requirements of these racket sports. Tennis players had higher accuracy when they performed under the low stimulus velocity compared to badminton and table tennis players. Badminton players performed better under the moderate speed comparing to tennis and table tennis players. Table tennis players had better performance than tennis and badminton players under the high stimulus velocity. Therefore, visual and motor systems of players from different racket sports may adapt to a stimulus velocity in coincidence-anticipation timing, which is specific to each type of racket sports.

  7. Monte Carlo simulation of activity measurements by means of 4πβ-γ coincidence system

    International Nuclear Information System (INIS)

    Takeda, Mauro N.; Dias, Mauro S.; Koskinas, Marina F.

    2004-01-01

    The methodology for simulating all detection processes in a 4πβ-γ coincidence system by means of the Monte Carlo technique is described. The goal is to predict the behavior of the observed activity as a function of the 4πβ detector efficiency. In this approach, the information contained in the decay scheme is used for determining the contribution of all radiations emitted by the selected radionuclide, to the measured spectra by each detector. This simulation yields the shape of the coincidence spectrum, allowing the choice of suitable gamma-ray windows for which the activity can be obtained with maximum accuracy. The simulation can predict a detailed description of the extrapolation curve, mainly in the region where the 4πβ detector efficiency approaches 100%, which is experimentally unreachable due to self absorption of low energy electrons in the radioactive source substrate. The theoretical work is being developed with MCNP Monte Carlo code, applied to a gas-flow proportional counter of 4π geometry, coupled to a pair of NaI(Tl) crystals. The calculated efficiencies are compared to experimental results. The extrapolation curve can be obtained by means of another Monte Carlo algorithm, being developed in the present work, to take into account fundamental characteristics of a complex decay scheme, including different types of radiation and transitions. The present paper shows preliminary calculated values obtained by the simulation and compared to predicted analytical values for a simple decay scheme. (author)

  8. True coincidence-summing corrections for the coincident γ-rays measured with coplanar grid CdZnTe detectors

    International Nuclear Information System (INIS)

    Yuecel, H.; Solmaz, A.N.; Koese, E.; Bor, D.

    2010-01-01

    In this study, true coincidence-summing (TCS) correction factors have been measured for the sources 22 Na, 60 Co, 133 Ba and 152 Eu by use of three large volume coplanar grid CdZnTe (acronym: CZT) detectors. In case of a close-in detection geometry, two different TCS calculation algorithms were used to compute the required TCS correction factors. Both of the algorithms are based on the measured total-to-peak (TTP) ratio and full-energy peak (FEP) efficiency values that were obtained using almost 'single' energy and coincidence-free nuclides. The results for TCS correction factors obtained by two different algorithms were agreeable to each other. The obtained TCS factors were ranged from about 7% to 30.5% in a 2250 mm 3 CZT detector when a close counting geometry was used. For other two detectors with a volume of 1000 and 1687.5 mm 3 , the resulted TCS correction factors were relatively smaller and varied between about 0.1% and 20% at the close counting geometry condition. Therefore, the results indicate that there is a need for the estimation of TCS corrections in CZT detectors, especially when their crystal volumes are greater than 1 cm 3 and these detectors are used in the case of a close-in detection geometry.

  9. Digital data recording system for the 4 πβ-γ coincidence apparatus

    International Nuclear Information System (INIS)

    Shaha, V.V.; Srivastava, P.K.

    1975-01-01

    The data recording system for the 4πβ-γ coincidence apparatus consists of three scalers, a timer, a day-clock, a print control unit and a Hewlett-Packard printer. The print control unit serves as an interface unit as well as generates necessary electronic commands for starting, scanning, recycling and actuating the printer. It also generates the run number and identification number. It has made the data recording and recycling completely automatic. The report describes the data recording system which has been in continuous use since March 1973. Brief description of the scalers, the timer, the day-clock and the printer is given. The print control unit is described and the working of the data handling, scanning and cycle counting sections is explained. (author)

  10. A high-efficiency neutron coincidence counter for small samples

    International Nuclear Information System (INIS)

    Miller, M.C.; Menlove, H.O.; Russo, P.A.

    1991-01-01

    The inventory sample coincidence counter (INVS) has been modified to enhance its performance. The new design is suitable for use with a glove box sample-well (in-line application) as well as for use in the standard at-line mode. The counter has been redesigned to count more efficiently and be less sensitive to variations in sample position. These factors lead to a higher degree of precision and accuracy in a given counting period and allow for the practical use of the INVS counter with gamma-ray isotopics to obtain a plutonium assay independent of operator declarations and time-consuming chemicals analysis. A calculation study was performed using the Los Alamos transport code MCNP to optimize the design parameters. 5 refs., 7 figs., 8 tabs

  11. Positron emission tomography with gamma camera in coincidence mode

    International Nuclear Information System (INIS)

    Hertel, A.; Hoer, G.

    1999-01-01

    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.) [de

  12. Airborne LIDAR borsight error calibration based on surface coincide

    International Nuclear Information System (INIS)

    Yuan, Fangyan; Li, Guoqing; Zuo, Zhengli; Li, Dong; Qi, Zengying; Qiu, Wen; Tan, Junxiang

    2014-01-01

    Light Detection and Ranging (LIDAR) is a system which can directly collect three-dimensional coordinate information of ground point and laser reflection strength information. With the wide application of LIDAR system, users hope to get more accurate results. Boresight error has an important effect on data accuracy and thus, it is thought that eliminating the error is very important. In recent years, many methods have been proposed to eliminate the error. Generally, they can be categorized into tie point method and surface matching method. In this paper, we propose another method called try value method based on surface coincide that is used in actual production by many companies. The method is simple and operable. Further, the efficacy of the method was demonstrated by analyzing the data from Zhangye city

  13. On the spatial coincidence of hydroxyl and methanol masers

    Science.gov (United States)

    Hartquist, T. W.; Menten, K. M.; Lepp, S.; Dalgarno, A.

    1995-01-01

    We argue that purely gas-phase chemical models for the production of OH in hydroxyl masers around ultracompact H II regions such as W3(OH) cannot account for the CH_3OH in the methanol masers that are found to coincide with the hydroxyl masers in these sources. We suggest that the CH_3OH in the masers is injected into the gas phase by evaporation of the grain mantles, the grains being heated by the passage of weak shocks. Gas evaporation also injects H_2O into the gas. Photodissociation of H_2O, CH_3OH and OH occur at similar rates, and substantial abundances of CH_3OH and OH coexist.

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

    International Nuclear Information System (INIS)

    Ducret, J.E.

    2006-07-01

    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 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. Optimized coincidence Doppler broadening spectroscopy using deconvolution algorithms

    International Nuclear Information System (INIS)

    Ho, K.F.; Ching, H.M.; Cheng, K.W.; Beling, C.D.; Fung, S.; Ng, K.P.

    2004-01-01

    In the last few years a number of excellent deconvolution algorithms have been developed for use in ''de-blurring'' 2D images. Here we report briefly on one such algorithm we have studied which uses the non-negativity constraint to optimize the regularization and which is applied to the 2D image like data produced in Coincidence Doppler Broadening Spectroscopy (CDBS). The system instrumental resolution functions are obtained using the 514 keV line from 85 Sr. The technique when applied to a series of well annealed polycrystalline metals gives two photon momentum data on a quality comparable to that obtainable using 1D Angular Correlation of Annihilation Radiation (ACAR). (orig.)

  16. Passive Time Coincidence Measurements with HEU and DU Metal Castings

    International Nuclear Information System (INIS)

    McConchie, Seth M.; Hausladen, Paul; Mihalczo, John T.; Wright, Michael C.; Archer, Daniel E.

    2008-01-01

    A Department of Energy sponsored Oak Ridge National Laboratory/Y-12 National Security Complex program of passive time coincidence measurements has been initiated at Y-12 to evaluate the ability to determine the presence of high enriched uranium (HEU) and distinguish it from depleted uranium (DU). This program uses the Nuclear Materials Identification System (NMIS) without an active interrogation source. Previous passive NMIS measurements with Pu metal and Pu oxide have been successful in determining the Pu mass, assuming a known 240Pu content. The spontaneous fission of uranium metal is considerably lower than Pu and measurements of this type have been performed at Lawrence Livermore National Laboratory. This work presents results of measurements of HEU and DU metal castings using moderated 3He detectors.

  17. Testable solution of the cosmological constant and coincidence problems

    International Nuclear Information System (INIS)

    Shaw, Douglas J.; Barrow, John D.

    2011-01-01

    We present a new solution to the cosmological constant (CC) and coincidence problems in which the observed value of the CC, Λ, is linked to other observable properties of the Universe. This is achieved by promoting the CC from a parameter that must be specified, to a field that can take many possible values. The observed value of Λ≅(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 Ω k0 =-0.0056(ζ b /0.5), where ζ b ∼1/2 is a QCD parameter. Requiring that a classical history exist, our model determines the probability of observing a given Λ. 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 observed coincidence between t Λ =Λ -1/2 and the age of the Universe, t U , is a typical occurrence in our model. In contrast to multiverse explanations of the CC problems, our solution is independent of the choice of a prior weighting of different Λ values and does not rely on anthropic selection effects. Our model includes no unnatural small parameters and does not require the introduction of new dynamical scalar fields or modifications to general relativity, and it can be tested by astronomical observations in the near future.

  18. 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.

  19. A superconducting electron spectrometer

    International Nuclear Information System (INIS)

    Guttormsen, M.; Huebel, H.; Grumbkow, A. von

    1983-03-01

    The set-up and tests of an electron spectrometer for in-beam conversion electron measurements are described. A superconducting solenoid is used to transport the electrons from the target to cooled Si(Li) detectors. The solenoid is designed to produce either a homogeneous axially symmetric field of up to 2 Tesla or a variety of field profiles by powering the inner and outer set of coils of the solenoid separately. The electron trajectories resulting for various field profiles are discussed. In-beam electron spectra taken in coincidence with electrons, gammas and alpha-particles are shown. (Auth.)

  20. 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.

  1. 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.

  2. Development of a coincidence system for radio-nuclide standardization using surface barrier detectors

    International Nuclear Information System (INIS)

    Koskinas, M.F.

    1988-01-01

    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 241 Am, 137 Cs and 109 Cd solutions. The activity has been obtained using the extrapolation method applied to the 4Πα-γ and 2Πe c -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 241 Am, 0.7% for 137 Cs and 0.6% for 109 Cd. The ratio between the probabilities of (electron capture + internal conversion) and internal conversion for the K-shell of 109 Cd has been determined. The result is: 2.8883 ± 0.016. (author) [pt

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

    Science.gov (United States)

    de Celis, B.; de la Fuente, R.; Williart, A.; de Celis Alonso, B.

    2007-09-01

    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 CaF 2(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.

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

    International Nuclear Information System (INIS)

    Yang Wenjing; Yin Jingpeng; Huang Xiongliang; Cheng Zhiwei; Shen Maoquan; Zhang Yang

    2012-01-01

    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)

  5. Design and development of VHDL based IP core for coincidence analyzer for FPGA based TDCR system

    International Nuclear Information System (INIS)

    Agarwal, Shivam; Gupta, Ashutosh; Chaudhury, Probal; Sharma, M.K.; Kulkarni, M.S.

    2018-01-01

    The coincidence counting technique is used in activity measurement methods to determine the activity of radionuclide e.g. 4πβ-γ method and Triple to Double Coincidence Ratio (TDCR) method etc. The 4πβ-γ method requires two inputs Coincidence Analyzer (CA) whereas; TDCR method requires three inputs CA. A VHDL (Very High Speed Integrated Circuit Hardware Description Language) based IP (Intellectual Property) core for coincidence analyzer has been designed and implemented in FPGA (Field Programmable Gate Array) for TDCR system. The developed IP not only facilitates the coincidence counting of three channels simultaneously but also provides an extendable dead time feature

  6. A merged-beam setup at SOLEIL dedicated to photoelectron–photoion coincidence studies on ionic species

    Energy Technology Data Exchange (ETDEWEB)

    Bizau, J.M., E-mail: jean-marc.bizau@u-psud.fr [Institut des Sciences Moléculaires d’Orsay (ISMO), CNRS, Univ. Paris Paris-Sud, Université Paris-Saclay, F-91405 Orsay (France); Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex (France); Cubaynes, D. [Institut des Sciences Moléculaires d’Orsay (ISMO), CNRS, Univ. Paris Paris-Sud, Université Paris-Saclay, F-91405 Orsay (France); Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex (France); Guilbaud, S.; El Eassan, N.; Al Shorman, M.M.; Bouisset, E.; Guigand, J.; Moustier, O.; Marié, A.; Nadal, E. [Institut des Sciences Moléculaires d’Orsay (ISMO), CNRS, Univ. Paris Paris-Sud, Université Paris-Saclay, F-91405 Orsay (France); Robert, E.; Nicolas, C. [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex (France); Miron, C. [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex (France); Extreme Light Infrastructure—Nuclear Physics, “Horia Hulubei” National Institute for Physics and Nuclear Engineering, 30 Reactorului Street, RO-077125 Măgurele, Jud. Ilfov (Romania)

    2016-07-15

    Highlights: • Description of a merged-beam setup at SOLEIL synchrotron radiation facility. • Unique setup of this kind allowing photoelectron spectroscopy on ionic species. • Use of electron-ion coincidence to reduce the background. • Examples on the photoionization of Xe{sup 5+} multiply-charged ion. - Abstract: We describe the merged-beam setup permanently installed on a dedicated optical branch of the PLEIADES beamline at SOLEIL, the French synchrotron radiation facility in St-Aubin, delivering photons in the 10–1000 eV photon energy range. The setup is designed both for photoion and photoelectron spectroscopy experiments on atomic and molecular ions. Ion spectrometry is dedicated to the determination of absolute single and multiple photoionization cross sections. Electron spectroscopy brings additional information on the non-radiative decay of inner-vacancies produced in the photoionization processes and allows for the determination of partial cross sections. Efficient reduction of the background in the electron spectra is achieved by the use of the electron-ion coincidence technique. Examples of photoion and photoelectron spectra are given for the Xe{sup 5+} ion.

  7. Active method of neutron time correlation coincidence measurement to authenticate mass and enrichment of uranium metal

    International Nuclear Information System (INIS)

    Zhang Songbai; Wu Jun; Zhu Jianyu; Tian Dongfeng; Xie Dong

    2011-01-01

    The active methodology of time correlation coincidence measurement of neutron is an effective verification means to authenticate uranium metal. A collimated 252 Cf neutron source was used to investigate mass and enrichment of uranium metal through the neutron transport simulation for different enrichments and different masses of uranium metal, then time correlation coincidence counts of them were obtained. By analyzing the characteristic of time correlation coincidence counts, the monotone relationships were founded between FWTH of time correlation coincidence and multiplication factor, between the total coincidence counts in FWTH for time correlation coincidence and mass of 235 U multiplied by multiplication factor, and between the ratio of neutron source penetration and mass of uranium metal. Thus the methodology to authenticate mass and enrichment of uranium metal was established with time correlation coincidence by active neutron investigation. (authors)

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

    International Nuclear Information System (INIS)

    Longo, J.; Schaffer, K.M.; Nordquist, H.

    2015-01-01

    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

  9. Coincidence of asthma and bronchospasm during anesthesia in tympanomastoidectomy.

    Science.gov (United States)

    Hosseinzadeh, Nima; Samadi, Shahram; Amali, Amin; Jafari Javid, Mihan

    2014-01-01

    High prevalence of asthma and bronchospasm was observed during induction of anesthesia in patients with chronic suppurative otitis mMedia (CSOM) who underwent tympanomastoidectomy. Although several studies have proposed association of allergic diseases with CSOM but no consensus about it has been established. Current study was designed to determine the coincidence of asthma in CSOM patients. In a cross-sectional study, authors investigated medical records of 106 CSOM patients underwent tympanomastoidectomy, aged 15 to 65 years, and 95 controls, which were matched by age and sex. Participants were admitted to Valiasr Hospital, Tehran, Iran, from April of 2011 to March of 2013. Required information, such as demographic characteristics and history of allergic rhinitis (AR) and asthma were obtained from patients' medical records. The prevalence of AR in the CSOM group was higher than controls' group (19.8% and 15.8%, respectively) (P>0.05). Asthma prevalence was significantly higher in patients with CSOM (P=0.03) (OR=7.67, 95% CI:  0.9-62.5). No significant association was found between history of AR and chronic ear infections. However, asthma was significantly more common in CSOM patients. Current study indicates that asthma and risk of bronchospasm need particular attention in patients with CSOM underwent tympanomastoidectomy before and during anesthesia.

  10. Coincidence of asthma and bronchospasm during anesthesia in tympanomastoidectomy.

    Directory of Open Access Journals (Sweden)

    Nima Hosseinzadeh

    2014-12-01

    Full Text Available High prevalence of asthma and bronchospasm was observed during induction of anesthesia in patients with chronic suppurative otitis mMedia (CSOM who underwent tympanomastoidectomy. Although several studies have proposed association of allergic diseases with CSOM but no consensus about it has been established. Current study was designed to determine the coincidence of asthma in CSOM patients. In a cross-sectional study, authors investigated medical records of 106 CSOM patients underwent tympanomastoidectomy, aged 15 to 65 years, and 95 controls, which were matched by age and sex. Participants were admitted to Valiasr Hospital, Tehran, Iran, from April of 2011 to March of 2013. Required information, such as demographic characteristics and history of allergic rhinitis (AR and asthma were obtained from patients' medical records. The prevalence of AR in the CSOM group was higher than controls' group (19.8% and 15.8%, respectively (P>0.05. Asthma prevalence was significantly higher in patients with CSOM (P=0.03 (OR=7.67, 95% CI:  0.9-62.5. No significant association was found between history of AR and chronic ear infections. However, asthma was significantly more common in CSOM patients. Current study indicates that asthma and risk of bronchospasm need particular attention in patients with CSOM underwent tympanomastoidectomy before and during anesthesia.

  11. Line identification studies using traditional techniques and wavelength coincidence statistics

    International Nuclear Information System (INIS)

    Cowley, C.R.; Adelman, S.J.

    1990-01-01

    Traditional line identification techniques result in the assignment of individual lines to an atomic or ionic species. These methods may be supplemented by wavelength coincidence statistics (WCS). The strength and weakness of these methods are discussed using spectra of a number of normal and peculiar B and A stars that have been studied independently by both methods. The present results support the overall findings of some earlier studies. WCS would be most useful in a first survey, before traditional methods have been applied. WCS can quickly make a global search for all species and in this way may enable identifications of an unexpected spectrum that could easily be omitted entirely from a traditional study. This is illustrated by O I. WCS is a subject to well known weakness of any statistical technique, for example, a predictable number of spurious results are to be expected. The danger of small number statistics are illustrated. WCS is at its best relative to traditional methods in finding a line-rich atomic species that is only weakly present in a complicated stellar spectrum

  12. Intrinsic coincident full-Stokes polarimeter using stacked organic photovoltaics.

    Science.gov (United States)

    Yang, Ruonan; Sen, Pratik; O'Connor, B T; Kudenov, M W

    2017-02-20

    An intrinsic coincident full-Stokes polarimeter is demonstrated by using strain-aligned polymer-based organic photovoltaics (OPVs) that can preferentially absorb certain polarized states of incident light. The photovoltaic-based polarimeter is capable of measuring four Stokes parameters by cascading four semitransparent OPVs in series along the same optical axis. This in-line polarimeter concept potentially ensures high temporal and spatial resolution with higher radiometric efficiency as compared to the existing polarimeter architecture. Two wave plates were incorporated into the system to modulate the S3 Stokes parameter so as to reduce the condition number of the measurement matrix and maximize the measured signal-to-noise ratio. Radiometric calibration was carried out to determine the measurement matrix. The polarimeter presented in this paper demonstrated an average RMS error of 0.84% for reconstructed Stokes vectors after normalized to S0. A theoretical analysis of the minimum condition number of the four-cell OPV design showed that for individually optimized OPV cells, a condition number of 2.4 is possible.

  13. Design for measurement system of Doppler broadening profiles with the coincidence technique using a NaI detector in colinear geometry with the Ge detector

    International Nuclear Information System (INIS)

    Mori, Kazuteru; Uedono, Akira; Tanigawa, Shoichiro; Nakai, Katsuhiko

    1998-01-01

    The measurement system for Doppler broadening profiles with the coincidence technique using a NaI detector in colinear geometry with a Ge detector was developed. The principle of measurement system with the coincidence technique between the NaI detector and the Ge detector was described. Application of the system for the detection of vacancy-type defects introduced by electron irradiation in Czochralski-(Cz) grown Si was shown. Detail in the difference between the Doppler broadening profiles for Cz-Si and Si grown by the floating-zone method was also obtained. (author)

  14. Design for measurement system of Doppler broadening profiles with the coincidence technique using a NaI detector in colinear geometry with the Ge detector

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Kazuteru; Uedono, Akira; Tanigawa, Shoichiro [Tsukuba Univ., Ibaraki (Japan). Inst. of Materials Science; Nakai, Katsuhiko

    1998-08-01

    The measurement system for Doppler broadening profiles with the coincidence technique using a NaI detector in colinear geometry with a Ge detector was developed. The principle of measurement system with the coincidence technique between the NaI detector and the Ge detector was described. Application of the system for the detection of vacancy-type defects introduced by electron irradiation in Czochralski-(Cz) grown Si was shown. Detail in the difference between the Doppler broadening profiles for Cz-Si and Si grown by the floating-zone method was also obtained. (author)

  15. Suitability study of using a coincidence monitor for room air radioactivity monitoring in a PET center

    International Nuclear Information System (INIS)

    Roellig, D.; Reichelt, C.; Iwatschenko-Borho, M.

    2001-01-01

    The application of radioactive nuclides in medicine may cause as well radioactive exposure of personnel (Medical Technical Assistants). In the present case the exposure of personnel in the area of medical positron-emission tomography (PET) within the Research Center of Rossendorf due to exhalation of the injected activity by the patient shall be investigated. For this purpose it is necessary to measure the activity concentration of the room air. Conventional methods such as collecting samples on special filters are not suitable due to the short half-life time of the used nuclides. Standard type continuous monitors are hardly suitable as well, because the injected activity of the patient and various radioactive sources required for the calibration of the PET-Camera produce an increased gamma background. In order to eliminate these disturbing influences a monitor has been constructed which uses CCM (cobalt coincidence method) developed by the company Thermo Eberline ESM. This method is specially suitable because upon each radioactive decay of PET nuclides positrons are emitted which in turn annihilate via the simultaneous emission of two 511 keV gamma quanta under an angle of 180 . The air to be measured is sucked through a cavity with two scintillation detectors on opposite sides. The coincident pulses produced by annihilating positrons inside the cavity are counted by a suitable electronic. Gamma quanta from outside the cavity can produce a pulse only in one detector and are rejected. Therefore no heavy lead shielding is required. Besides the mechanical construction of the monitor optimization and calibration for different PET-nuclides had to be performed. Special attention was paid to the sampling system. The air intake had to be close to the breathing zone of the MTA. The hose to the monitor had to be as short as possible. The target of the work was to design a model for an industrial monitor. (orig.) [de

  16. A beta ray spectrometer based on a two-, or three-element silicon detector coincidence telescope

    International Nuclear Information System (INIS)

    Horowitz, Y.S.; Weizman, Y.; Hirning, C.R.

    1995-01-01

    The operation of a beta ray energy spectrometer based on a two-or three-element silicon detector telescope is described. The front detector (A) is a thin, totally depleted, silicon surface barrier detector either 40 μm, 72 μm or 98 μm thick. The back detector (C) is a Li compensated silicon detector, 5000 μm thick. An additional thin detector can be inserted between these two detectors when additional photon rejection capability is required in intense photon fields. The capability of the spectrometer to reject photons is based on the fact that incident photons will have a small probability of simultaneously losing detectable energy in two detectors and an even smaller probability of losing detectable energy in all three detectors. Electrons, however, above a low energy threshold, will always record simultaneous, events in all three detectors. The spectrometer is capable of measuring electron energies from a lower energy coincidence threshold of 70 keV with 60% efficiency increasing to 100% efficiency in the energy region between 150 keV and 2.5 MeV. (Author)

  17. 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.

  18. 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.

  19. Fast digital 4πβ-4πγ coincidence counting with offline analysis at IRA.

    Science.gov (United States)

    Teresa Durán, M; Nedjadi, Youcef; Juget, Frédéric; Bochud, François; Bailat, Claude

    2018-04-01

    IRA recently launched a project to digitize all the data acquisition systems it uses for primary radionuclide standardizations. It is well-known that the digital approach presents numerous advantages over the traditional analog electronics such as information losslessness, scalability, online and/or offline data processing, and it is also a solution to the growing difficulties to repair or renew ageing modules. As a first step in this wider program, our institute set-up a 4πβ-4πγ digital coincidence counting system, with FPGA (Field Programmable Gate Array)-based commercial boards from National Instruments (NI), to perform data acquisition and offline data analysis. Choosing all components and software from the same supplier provides a full compact and consistent electronic system. To demonstrate and validate the capacity of this system to standardize the activity of radioisotopes, we compare its predictions for the activity concentration of 133 Ba, 166m Ho and 18 F solutions with the results from a coincidence counting system with analog electronics, as well as with the results from other primary methods and a secondary measurement performed with an IG11 ionization chamber (CIR, chambre d'ionization de référence) with an equivalent activity traceable to the Système International de Référence. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Coincidence and covariance data acquisition in photoelectron and -ion spectroscopy. II. Analysis and applications

    Science.gov (United States)

    Mikosch, Jochen; Patchkovskii, Serguei

    2013-10-01

    We use an analytical theory of noisy Poisson processes, developed in the preceding companion publication, to compare coincidence and covariance measurement approaches in photoelectron and -ion spectroscopy. For non-unit detection efficiencies, coincidence data acquisition (DAQ) suffers from false coincidences. The rate of false coincidences grows quadratically with the rate of elementary ionization events. To minimize false coincidences for rare event outcomes, very low event rates may hence be required. Coincidence measurements exhibit high tolerance to noise introduced by unstable experimental conditions. Covariance DAQ on the other hand is free of systematic errors as long as stable experimental conditions are maintained. In the presence of noise, all channels in a covariance measurement become correlated. Under favourable conditions, covariance DAQ may allow orders of magnitude reduction in measurement times. Finally, we use experimental data for strong-field ionization of 1,3-butadiene to illustrate how fluctuations in experimental conditions can contaminate a covariance measurement, and how such contamination can be detected.

  1. LETTER TO THE EDITOR: Observation of photo-double ionization of carbon monoxide below the adiabatic double-ionization potential by threshold-photoelectron - photoelectron coincidence spectroscopy

    Science.gov (United States)

    Thompson, David B.; Dawber, Grant; Gulley, Nicola; MacDonald, Michael A.; King, George C.

    1997-03-01

    The production of 0953-4075/30/5/004/img8 and 0953-4075/30/5/004/img9 ion pairs in carbon monoxide at photon energies below the adiabatic double-ionization threshold of 41.25 eV has been probed in a threshold-photoelectron - photoelectron coincidence (TPEPECO) experiment using tunable VUV radiation and a sensitive electron spectrometer. The TPEPECO spectra provide evidence of 0953-4075/30/5/004/img10 production that does not involve creation and dissociation of a molecular dication, but instead results from complete dissociation of a molecular cation followed by autoionization of the atomic oxygen fragment. Furthermore, an electron - electron coincidence signal has been detected at photon energies as low as 36.5 eV, well below the previously measured onset for 0953-4075/30/5/004/img10 production.

  2. Description and performance characteristics for the neutron Coincidence Collar for the verification of reactor fuel assemblies

    International Nuclear Information System (INIS)

    Menlove, H.O.

    1981-08-01

    An active neutron interrogation method has been developed for the measurement of 235 U content in fresh fuel assemblies. The neutron Coincidence Collar uses neutron interrogation with an AmLi neutron source and coincidence counting the induced fission reaction neutrons from the 235 U. This manual describes the system components, operation, and performance characteristics. Applications of the Coincidence Collar to PWR and BWR types of reactor fuel assemblies are described

  3. It takes two—coincidence coding within the dual olfactory pathway of the honeybee

    OpenAIRE

    Brill, Martin F.; Meyer, Anneke; Rössler, Wolfgang

    2015-01-01

    To rapidly process biologically relevant stimuli, sensory systems have developed a broad variety of coding mechanisms like parallel processing and coincidence detection. Parallel processing (e.g., in the visual system), increases both computational capacity and processing speed by simultaneously coding different aspects of the same stimulus. Coincidence detection is an efficient way to integrate information from different sources. Coincidence has been shown to promote associative learning and...

  4. Differential coincidence circuit in the 10-10 second region (1960)

    International Nuclear Information System (INIS)

    Van Zurk, R.; Grenoble-1 Univ., 38; Commissariat a l'Energie Atomique, Saclay

    1960-01-01

    A coincidence circuit of low resolution time using the differential coincidence Bay principle is described. It uses three 6BN6 tubes ordered to chronotron structure. Results with Radiotechnique 56 AVP photomultipliers and for 60 Co γ-γ coincidences are 4,6.10 -10 s (full width at half maximum) if the efficiency is ε = 40 per cent and also 7,2.10 -10 s if ε = 85 per cent. (author) [fr

  5. 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

  6. Design and test of 4πβ-γ coincidence measurement device based on DSP technology

    International Nuclear Information System (INIS)

    Zeng Herong; Feng Qijie; Leng Jun; Qian Dazhi; Bai Lixin; Zhang Yiyun

    2012-01-01

    The paper illustrates the hardware and software of the 4πβ-γ coincidence measurement device based on DSP technology in detail. In such device, the single-channel analyzer, gate generator, coincidence circuit and scalar in the traditional coincidence measurement device are replaced by the digital coincidence acquirer which is researched and manufactured by ourselves. Doing so, the measurement efficiency will be respectively improved, and the hardware cost will be lowered. The comparison experiment shows that the design of such device is a success. (authors)

  7. Studies on the true coincidence correction in measuring filter samples by gamma spectrometry

    CERN Document Server

    Lian Qi; Chang Yong Fu; Xia Bing

    2002-01-01

    The true coincidence correction in measuring filter samples has been studied by high efficiency HPGe gamma detectors. The true coincidence correction for a specific three excited levels de-excitation case has been analyzed, and the typical analytical expressions of true coincidence correction factors have been given. According to the measured relative efficiency on the detector surface with 8 'single' energy gamma emitters and efficiency of filter samples, the peak and total efficiency surfaces are fitted. The true coincidence correction factors of sup 6 sup 0 Co and sup 1 sup 5 sup 2 Eu calculated by the efficiency surfaces agree well with experimental results

  8. The development and application of a coincidence measurement apparatus with micro-computer system

    International Nuclear Information System (INIS)

    Du Hongshan; Zhou Youpu; Gao Junlin; Qin Deming; Cao Yunzheng; Zhao Shiping

    1987-01-01

    A coincidence measurement apparatus with micro-computer system is developed. Automatic data acquisition and processing are achieved. Results of its application for radioactive measurement are satisfactory

  9. New technique for determination of long-lived radioisotopes, Iodine-129, using multiparameter coincidence spectrometry

    International Nuclear Information System (INIS)

    Hatsukawa, Yuichi; Oshima, Masumi; Toh, Yosuke; Shinohara, Nobuo; Kushita, Kosuke; Ueno, Takashi

    2003-01-01

    Multiparameter coincidence γ-ray spectrometry based on g-g coincidence is widely used in the field of nuclear structure studies, and has produced many successful results. In this study, feasibility of the method for neutron activation analysis of long lived iodine isotope, 129 I, was investigated. (author)

  10. It Takes Two – Coincidence coding within the dual olfactory pathway of the honeybee

    Directory of Open Access Journals (Sweden)

    Martin F. Brill

    2015-07-01

    Full Text Available To rapidly process biologically relevant stimuli, sensory systems have developed a broad variety of coding mechanisms like parallel processing and coincidence detection. Parallel processing (e.g. in the visual system, increases both computational capacity and processing speed by simultaneously coding different aspects of the same stimulus. Coincidence detection is an efficient way to integrateinformation from different sources. Coincidence has been shown to promote associative learning and memory or stimulus feature detection (e.g. in auditory delay lines. Within the dual olfactory pathway of the honeybee both of these mechanisms might be implemented by uniglomerular projection neurons (PNs that transfer information from the primary olfactory centers, the antennal lobe (AL, to a multimodal integration center, the mushroom body (MB. PNs from anatomically distinct tracts respond to the same stimulus space, but have different physiological properties, characteristics that are prerequisites for parallel processing of different stimulus aspects. However, the PN pathways also display mirror-imaged like anatomical trajectories that resemble neuronal coincidence detectors as known from auditory delay lines. To investigate temporal processing of olfactory information, we recorded PN odor responses simultaneously from both tracts and measured coincident activity of PNs within and between tracts. Our results show that coincidence levels are different within each of the two tracts. Coincidence also occurs between tracts, but to a minor extent compared to coincidence within tracts. Taken together our findings support the relevance of spike timing in coding of olfactory information (temporal code.

  11. It takes two-coincidence coding within the dual olfactory pathway of the honeybee.

    Science.gov (United States)

    Brill, Martin F; Meyer, Anneke; Rössler, Wolfgang

    2015-01-01

    To rapidly process biologically relevant stimuli, sensory systems have developed a broad variety of coding mechanisms like parallel processing and coincidence detection. Parallel processing (e.g., in the visual system), increases both computational capacity and processing speed by simultaneously coding different aspects of the same stimulus. Coincidence detection is an efficient way to integrate information from different sources. Coincidence has been shown to promote associative learning and memory or stimulus feature detection (e.g., in auditory delay lines). Within the dual olfactory pathway of the honeybee both of these mechanisms might be implemented by uniglomerular projection neurons (PNs) that transfer information from the primary olfactory centers, the antennal lobe (AL), to a multimodal integration center, the mushroom body (MB). PNs from anatomically distinct tracts respond to the same stimulus space, but have different physiological properties, characteristics that are prerequisites for parallel processing of different stimulus aspects. However, the PN pathways also display mirror-imaged like anatomical trajectories that resemble neuronal coincidence detectors as known from auditory delay lines. To investigate temporal processing of olfactory information, we recorded PN odor responses simultaneously from both tracts and measured coincident activity of PNs within and between tracts. Our results show that coincidence levels are different within each of the two tracts. Coincidence also occurs between tracts, but to a minor extent compared to coincidence within tracts. Taken together our findings support the relevance of spike timing in coding of olfactory information (temporal code).

  12. Coincidence imaging of polyatomic molecules via laser-induced Coulomb explosion

    International Nuclear Information System (INIS)

    Gagnon, J; Corkum, P B; Bhardwaj, V R; Lee, Kevin F; Rayner, D M

    2008-01-01

    We extend laser-induced Coulomb explosion imaging to retrieve the structure of the five-atom dichloromethane (CH 2 Cl 2 ) molecule by developing coincidence imaging and geometry optimization techniques. By detecting all five atoms in coincidence, we show that, from the measured velocity vectors, the geometry of the molecules can be reconstructed.

  13. Coincidence and noncoincidence counting (81Rb and 43K): a comparative study

    International Nuclear Information System (INIS)

    Ikeda, S.; Duken, H.; Tillmanns, H.; Bing, R.J.

    1975-01-01

    The accuracy of imaging and resolution obtained with 81 Rb and 43 K using coincidence and noncoincidence counting was compared. Phantoms and isolated infarcted dog hearts were used. The results clearly show the superiority of coincidence counting with a resolution of 0.5 cm. Noncoincidence counting failed to reveal even sizable defects in the radioactive source. (U.S.)

  14. Dissociative photoionization of the NO molecule studied by photoelectron-photon coincidence technique

    International Nuclear Information System (INIS)

    Kivimaeki, A.; Alvarez-Ruiz, J.; Coreno, M.; Simone, M. de; Moise, A.; Partanen, L.; Richter, R.; Stankiewicz, M.

    2010-01-01

    Low-energy photoelectron-vacuum ultraviolet (VUV) photon coincidences have been measured using synchrotron radiation excitation in the inner-valence region of the nitric oxide molecule. The capabilities of the coincidence set-up were demonstrated by detecting the 2s -1 → 2p -1 radiative transitions in coincidence with the 2s photoelectron emission in Ne. In NO, the observed coincidence events are attributed to dissociative photoionization with excitation, whereby photoelectron emission is followed by fragmentation of excited NO + ions into O + + N* or N + + O* and VUV emission from an excited neutral fragment. The highest coincidence rate occurs with the opening of ionization channels which are due to correlation satellites of the 3σ photoionization. The decay time of VUV photon emission was also measured, implying that specific excited states of N atoms contribute significantly to observed VUV emission.

  15. Differential coincidence circuit in the 10{sup -10} second region (1960); Circuit de coincidence differentiel dans le domaine de 10{sup -10} seconde (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Van Zurk, R [Commissariat a l' Energie Atomique, Lab. de Physique Nucleaire, Grenoble (France).Centre d' Etudes Nucleaires; [Grenoble-1 Univ., 38 (France); [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1960-07-01

    A coincidence circuit of low resolution time using the differential coincidence Bay principle is described. It uses three 6BN6 tubes ordered to chronotron structure. Results with Radiotechnique 56 AVP photomultipliers and for {sup 60}Co {gamma}-{gamma} coincidences are 4,6.10{sup -10} s (full width at half maximum) if the efficiency is {epsilon} = 40 per cent and also 7,2.10{sup -10} s if {epsilon} = 85 per cent. (author) [French] Un circuit de coincidence differentiel du type de Bay, utilise en selecteur en temps a canal mobile, a ete construit pour la mesure des periodes {gamma} et des periodes d'annihilation du positon dans differents materiaux. Il comporte trois tubes 6BN6 disposes en structure chronotron. On a utilise les nouveaux photomultiplicateurs 56 AVP avec scintillateur plastique. Avec les coincidences {gamma}-{gamma} du {sup 60}Co, on obtient 2T 4,6.10{sup -10} s avec une efficacite de 40 pour cent et 2T = 7,2.10{sup -10} s avec une efficacite de 85 pour cent. (auteur)

  16. Standardization of 201Tl and 55Fe radionuclides in a 4 (PC)-NaI(Tl) coincidence system

    International Nuclear Information System (INIS)

    Pires, Carlos Augusto

    2008-01-01

    In the present work the procedure for the standardization of radionuclides using the 4π(PC)-NaI(Tl) coincidence system was developed. The radionuclides selected were 201 Tl, used in nuclear medicine, and 55 Fe primary standard source, used for x-ray spectrometers calibration. The 4π(PC)-NaI(Tl) is composed of a 4 proportional counter operated at 0.1MPa coupled to two NaI(Tl) crystals. The 201 Tl decays by electron capture process followed by a prompt gamma-ray. The disintegration rate was determined by extrapolation technique using two methods: electronic discrimination and external absorbers. The radioactive sources were prepared in a 20 μg cm -2 thick Collodion film. The conventional electronic system was used. The observed events were registered by the TAC method. The 55 Fe decays by electron capture process to the ground state of 55 Mn, emitting x rays with around 6 keV. The standardization was obtained by the tracing method. This technique was applied using two radionuclides, which decay by electron capture process followed by a prompt gamma-ray, namely 51 Cr and 54 Mn, as tracers. Measurements with 1 and 2 aluminum foils, each 150 g cm-2 thick were carried out. The activity was obtained by extrapolation for zero thickness Al foil. The uncertainties were treated by means of matrix covariance methodology and takes into account all correlations involved. (author)

  17. Evaluation of accidental coincidences for time-differential Moessbauer-spectroscopy

    International Nuclear Information System (INIS)

    Alflen, M.; Meyer, W.

    1995-01-01

    The accidental coincidences of a measuring system based on time-to-amplitude conversion are considered in some detail for the case of low starting and high stopping rates. Two types of accidental coincidences are distinguished, those carrying time information and those without time information. Neglecting any deadtime effects of the detectors, analytical expressions for the calculation of the time distribution of the random coincidences are evaluated. The analytical expressions have been confirmed by Monte Carlo simulations. The procedure is applied to time-differential Moessbauer spectroscopy in order to extract the time spectra of true coincidences. The measured spectrum in a time channel turns out to be a superposition of the true spectrum (true coincidences), a time integral spectrum (random coincidences), and a weighted superposition of true spectra of other time channels (random but time carrying information). A measurement with a single line 57 Co/Rh-source and single line K[Fe(CN) 6 ].3H 2 O-absorber with stopping rates of 1 MBq shows agreement between the theoretical time-filtered spectra and the corrected measured spectra of true coincidences. ((orig.))

  18. Tight bounds for the Pearle-Braunstein-Caves chained inequality without the fair-coincidence assumption

    Science.gov (United States)

    Jogenfors, Jonathan; Larsson, Jan-Åke

    2017-08-01

    In any Bell test, loopholes can cause issues in the interpretation of the results, since an apparent violation of the inequality may not correspond to a violation of local realism. An important example is the coincidence-time loophole that arises when detector settings might influence the time when detection will occur. This effect can be observed in many experiments where measurement outcomes are to be compared between remote stations because the interpretation of an ostensible Bell violation strongly depends on the method used to decide coincidence. The coincidence-time loophole has previously been studied for the Clauser-Horne-Shimony-Holt and Clauser-Horne inequalities, but recent experiments have shown the need for a generalization. Here, we study the generalized "chained" inequality by Pearle, Braunstein, and Caves (PBC) with N ≥2 settings per observer. This inequality has applications in, for instance, quantum key distribution where it has been used to reestablish security. In this paper we give the minimum coincidence probability for the PBC inequality for all N ≥2 and show that this bound is tight for a violation free of the fair-coincidence assumption. Thus, if an experiment has a coincidence probability exceeding the critical value derived here, the coincidence-time loophole is eliminated.

  19. Testing the Cosmic Coincidence Problem and the Nature of Dark Energy

    International Nuclear Information System (INIS)

    Dalal, Neal; Abazajian, Kevork; Jenkins, Elizabeth; Manohar, Aneesh V.

    2001-01-01

    Dark energy models which alter the relative scaling behavior of dark energy and matter could provide a natural solution to the cosmic coincidence problem -- why the densities of dark energy and dark matter are comparable today. A generalized class of dark energy models is introduced which allows noncanonical scaling of the ratio of dark matter and dark energy with the Robertson-Walker scale factor a(t) . We show that determining whether there is a coincidence problem, and the extent of cosmic coincidence, can be addressed by several forthcoming experiments

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

    International Nuclear Information System (INIS)

    Krick, M.S.; Harker, W.C.; Rinard, P.M.; Wenz, T.R.; Lewis, W.; Pham, P.; Ridder, P. de

    1998-01-01

    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

  1. Comparison of satellite reflectance algorithms for estimating chlorophyll-a in a temperate reservoir using coincident hyperspectral aircraft imagery and dense coincident surface observations

    Science.gov (United States)

    We analyzed 10 established and 4 new satellite reflectance algorithms for estimating chlorophyll-a (Chl-a) in a temperate reservoir in southwest Ohio using coincident hyperspectral aircraft imagery and dense water truth collected within one hour of image acquisition to develop si...

  2. Reproduction of the coincidence effect in gamma ray spectrometry by using Monte Carlo method

    International Nuclear Information System (INIS)

    Park, S. H.; Kim, J. K.; Lee, S. H.

    2001-01-01

    Scintillation detector such as NaI(TI), or semiconductor detector, such as HPGe, are used for Measurement/Assessment of the radiation type and radiation activity. The measured energy spectrum are used for measuring the radiation type and activity. Corrections for true coincidence due to emit more than 2 photons at the same time and random coincidence due to measuring system when increasing of the radiation intensity. For accurate assessment, measurement with adequate measure system is performed, and corrections for coincidence are performed in the hardware aspect and software aspect. In general, there are limitations or difficulties in measurement of radiation assessment, computational simulation is instead used. In simulation, it has much advantages than measurement in technically, timely, and financially, it is widely used instead of measurement. In this study, the method to reproduce of the coincidence effect was proposed by using monte carlo method

  3. High proportion of smaller ranged hummingbird species coincides with ecological specialization across the Americas

    DEFF Research Database (Denmark)

    Sonne, Jesper; Martín González, Ana M.; Maruyama, Pietro K.

    2016-01-01

    Ecological communities that experience stable climate conditions have been speculated to preserve more specialized interspecific associations and have higher proportions of smaller ranged species (SRS). Thus, areas with disproportionally large numbers of SRS are expected to coincide geographicall...

  4. On the extension of (e,2e) theory to coincidence studies of ion-atom collisions

    International Nuclear Information System (INIS)

    Godunov, A.L.; Kampp, Marco; Sulik, B.; Walters, H.R.J.; Whelan, Colm T.

    2007-01-01

    The extension of (e,2e) theory to the coincidence studies of ion-atom collisions is considered. The simultaneous ionization of projectile and target is discussed and results are presented for transfer ionization

  5. A data acquisition system for coincidence imaging using a conventional dual head gamma camera

    Science.gov (United States)

    Lewellen, T. K.; Miyaoka, R. S.; Jansen, F.; Kaplan, M. S.

    1997-06-01

    A low cost data acquisition system (DAS) was developed to acquire coincidence data from an unmodified General Electric Maxxus dual head scintillation camera. A high impedance pick-off circuit provides position and energy signals to the DAS without interfering with normal camera operation. The signals are pulse-clipped to reduce pileup effects. Coincidence is determined with fast timing signals derived from constant fraction discriminators. A charge-integrating FERA 16 channel ADC feeds position and energy data to two CAMAC FERA memories operated as ping-pong buffers. A Macintosh PowerPC running Labview controls the system and reads the CAMAC memories. A CAMAC 12-channel scaler records singles and coincidence rate data. The system dead-time is approximately 10% at a coincidence rate of 4.0 kHz.

  6. A data acquisition system for coincidence imaging using a conventional dual head gamma camera

    International Nuclear Information System (INIS)

    Lewellen, T.K.; Miyaoka, R.S.; Kaplan, M.S.

    1996-01-01

    A low cost data acquisition system (DAS) was developed to acquire coincidence data from an unmodified General Electric Maxxus dual head scintillation camera. A high impedance pick-off circuit provides position and energy signals to the DAS without interfering with normal camera operation. The signals are pulse-clipped to reduce pileup effects. Coincidence is determined with fast timing signals derived from constant fraction discriminators. A charge-integrating FERA 16 channel ADC feeds position and energy data to two CAMAC FERA memories operated as ping-pong buffers. A Macintosh PowerPC running Labview controls the system and reads the CAMAC memories. A CAMAC 12-channel scaler records singles and coincidence rate data. The system dead-time is approximately 10% at a coincidence rate of 4.0 kHz

  7. A method for measuring the energy spectrum of coincidence events in positron emission tomography.

    Science.gov (United States)

    Goertzen, Andrew L; Stout, David B; Thompson, Christopher J

    2010-01-21

    Positron emission tomography (PET) system energy response is typically characterized in singles detection mode, yet there are situations in which the energy spectrum of coincidence events might be different than the spectrum measured in singles mode. Examples include imaging with isotopes that emit a prompt gamma in coincidence with a positron emission, imaging with low activity in a LSO/LYSO-based cameras, in which the intrinsic activity is significant, and in high scatter situations where the two 511 keV photons have different scattering probabilities (i.e. off-center line source). The ability to accurately measure the energy spectrum of coincidence events could be used for validating simulation models, optimizing energy discriminator levels and examining scatter models and corrections. For many PET systems operating in coincidence mode, the only method available for estimating the energy spectrum is to step the lower and upper level discriminators (LLD and ULD). Simple measurement techniques such as using a narrow sliding energy window or stepping only the LLD will not yield a spectrum of coincidence events that is accurate for cases where there are different energy components contributing to the spectrum. In this work we propose a new method of measuring the energy spectrum of coincidence events in PET based on a linear combination of two sets of coincident count measurements: one made by stepping the LLD and one made by stepping the ULD. The method was tested using both Monte Carlo simulations of a Siemens microPET R4 camera and measured data acquired on a Siemens Inveon PET camera. The results show that our energy spectrum calculation method accurately measures the coincident energy spectra for cases including the beta/gamma spectrum of the (176)Lu intrinsic activity present in the LSO scintillator crystals, a (68)Ge source and an (124)I source (in which there are prompt gamma-rays emitted together with the positron).

  8. Coincidence and covariance data acquisition in photoelectron and -ion spectroscopy. I. Formal theory

    Science.gov (United States)

    Mikosch, Jochen; Patchkovskii, Serguei

    2013-10-01

    We derive a formal theory of noisy Poisson processes with multiple outcomes. We obtain simple, compact expressions for the probability distribution function of arbitrarily complex composite events and its moments. We illustrate the utility of the theory by analyzing properties of coincidence and covariance photoelectron-photoion detection involving single-ionization events. The results and techniques introduced in this work are directly applicable to more general coincidence and covariance experiments, including multiple ionization and multiple-ion fragmentation pathways.

  9. Multidimensional coincidence point results for generalized $(\\psi ,\\theta ,\\varphi$-contraction on ordered metric spaces

    Directory of Open Access Journals (Sweden)

    Bhavana Deshpande

    2017-11-01

    Full Text Available The main objective of this research article is to establish some coincidence point theorem for $g$-non-decreasing mappings under generalized $(\\psi ,\\theta ,\\varphi $-contraction on a partially ordered metric space. Furthermore, we show how multidimensional results can be seen as a simple consequences of our unidimensional coincidence point theorem. Our results modify, improve, sharpen, enrich and generalize various known results.

  10. Memory Effects Study of Measuring Radioactive Xenon Isotopes With β-γ Coincidence Method

    International Nuclear Information System (INIS)

    Jia Huaimao; Wang Shilian; Wang Jun; Li Qi; Zhao Yungang; Fan Yuanqing; Zhang Xinjun

    2010-01-01

    The β-γ coincidence technique is a kind of the key important method to detect radioactive xenon isotopes for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). This paper describes noble gases memory effects of β-γ coincidence detector. Xenon memory effects were measured and its influence on detector's minimum detectable activity (MDA) was evaluated. The methods of reducing xenon memory effects were studied. In conclusion, aluminium coated plastic scintillator and YAP scintillator can remarkably decrease xenon memory effects. (authors)

  11. Analysis of femtosecond pump-probe photoelectron-photoion coincidence measurements applying Bayesian probability theory

    Science.gov (United States)

    Rumetshofer, M.; Heim, P.; Thaler, B.; Ernst, W. E.; Koch, M.; von der Linden, W.

    2018-06-01

    Ultrafast dynamical processes in photoexcited molecules can be observed with pump-probe measurements, in which information about the dynamics is obtained from the transient signal associated with the excited state. Background signals provoked by pump and/or probe pulses alone often obscure these excited-state signals. Simple subtraction of pump-only and/or probe-only measurements from the pump-probe measurement, as commonly applied, results in a degradation of the signal-to-noise ratio and, in the case of coincidence detection, the danger of overrated background subtraction. Coincidence measurements additionally suffer from false coincidences, requiring long data-acquisition times to keep erroneous signals at an acceptable level. Here we present a probabilistic approach based on Bayesian probability theory that overcomes these problems. For a pump-probe experiment with photoelectron-photoion coincidence detection, we reconstruct the interesting excited-state spectrum from pump-probe and pump-only measurements. This approach allows us to treat background and false coincidences consistently and on the same footing. We demonstrate that the Bayesian formalism has the following advantages over simple signal subtraction: (i) the signal-to-noise ratio is significantly increased, (ii) the pump-only contribution is not overestimated, (iii) false coincidences are excluded, (iv) prior knowledge, such as positivity, is consistently incorporated, (v) confidence intervals are provided for the reconstructed spectrum, and (vi) it is applicable to any experimental situation and noise statistics. Most importantly, by accounting for false coincidences, the Bayesian approach allows us to run experiments at higher ionization rates, resulting in a significant reduction of data acquisition times. The probabilistic approach is thoroughly scrutinized by challenging mock data. The application to pump-probe coincidence measurements on acetone molecules enables quantitative interpretations

  12. Subtraction of random coincidences in γ-ray spectroscopy: A new approach

    International Nuclear Information System (INIS)

    Pattabiraman, N.S.; Ghugre, S.S.; Basu, S.K.; Garg, U.; Ray, S.; Sinha, A.K.; Zhu, S.

    2006-01-01

    A new analytical method for estimation and subsequent subtraction of random coincidences has been developed. It utilizes the knowledge of the counts in the main diagonal of a background-subtracted symmetric data set for the estimation of the events originating from random coincidences. This procedure has been successfully applied to several data sets. It could be a valuable tool for low-fold data sets, especially for low-cross-section events

  13. Gamma--gamma directional correlations and coincidence studies in /sup 154/Gd

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, J B; Gupta, S L; Hamilton, J H; Ramayya, A V [Vanderbilt Univ., Nashville, Tenn. (USA). Dept. of Physics; Delhi Univ. (India). Ramjas Coll.)

    1977-06-01

    The intensities, placements and E2/M1 mixing ratios of transitions in the decay of /sup 154/Eu have been carefully studied to provide accurate data for microscopic calculations. Coincidence relationships in thhe decay of /sup 154/Eu have been studied extensively with a multiparameter ..gamma..-..gamma.. coincidence system with two large volume Ge(Li) detectors. Spectra in coincidence with twenty energy gates were analyzed. Twenty-nine new coincidence relationships were established and confirmed most, but not all, of several levels previously assigned by energy fits only. From an analysis of coincidence spectra and singles spectra with a 18% efficiency Ge(Li) detector new information on the gamma-ray intensities were obtained. Precise values of the E2/M1 mixing ratios of transitions from the gamma- and beta-vibrational bands to the g.s. band have been determined from ..gamma..-..gamma.. directional correlation measurements with a NaI(Tl)-Ge(Li) detector coincidence system. Mixing ratios were obtained for a number of other transitions including those from KPI = 0/sup -/ and 2+ bands from direct and skipped cascade correlations.

  14. Gamma-gamma directional correlations and coincidence studies in 154Gd

    International Nuclear Information System (INIS)

    Gupta, J.B.; Gupta, S.L.; Hamilton, J.H.; Ramayya, A.V.; Delhi Univ.

    1977-01-01

    The intensities, placements and E2/M1 mixing ratios of transitions in the decay of 154 Eu have been carefully studied to provide accurate data for microscopic calculations. Coincidence relationships in thhe decay of 154 Eu have been studied extensively with a multiparameter γ-γ coincidence system with two large volume Ge(Li) detectors. Spectra in coincidence with twenty energy gates were analyzed. Twenty-nine new coincidence relationships were established and confirmed most, but not all, of several levels previously assigned by energy fits only. From an analysis of coincidence spectra and singles spectra with a 18% efficiency Ge(Li) detector new information on the gamma-ray intensities were obtained. Precise values of the E2/M1 mixing ratios of transitions from the gamma- and beta-vibrational bands to the g.s. band have been determined from γ-γ directional correlation measurements with a NaI(Tl)-Ge(Li) detector coincidence system. Mixing ratios were obtained for a number of other transitions including those from KPI = 0 - and 2+ bands from direct and skipped cascade correlations. (orig.) [de

  15. Systemic Autoimmune, Rheumatic Diseases and Coinciding Psoriasis: Data from a Large Single-Centre Registry and Review of the Literature

    Directory of Open Access Journals (Sweden)

    Anna Bazsó

    2015-01-01

    Full Text Available Psoriasis is a systemic immune-inflammatory disease characterized by chronic or recurrent skin symptoms, psoriatic arthritis, enthesopathy, and uveitis. Psoriasis has recently been published to appear with various autoimmune disorders, but the coexistence has been systematically reviewed by only few studies until now. In the present study, charts and electronic database of 4344 patients with various systemic autoimmune disorders, under regular medical control at our department, were reviewed retrospectively searching for association with psoriasis. Hereby, we demonstrate 25 psoriatic patients coinciding with various systemic autoimmune diseases. The coexistence of psoriasis and autoimmune diseases resulted in the worsening of the clinical outcome of the autoimmune diseases as indicated by higher frequency and dosages of glucocorticoid use, need for biologicals, and other comorbidities. These results suggest common environmental and genetic background as well as therapeutic possibilities in the future.

  16. Proton-gamma coincidence experiment on medium mass nuclei at 400MeV and study of reaction mechanisms

    International Nuclear Information System (INIS)

    Baldit, Alain.

    1981-01-01

    Previous γ ray production experiments produced by proton on nuclei show important cross sections for residual nuclei corresponding to a four nucleon (2p + 2n) removal. With our (p - γ) coincidence experiment the forward emitted proton reflects the primary interaction and the γ spectra characterizes the final state of the reaction. Protons are detected with a magnetic spectrometer and γ rays are selected with a Ge(Li) diode. Angular and momentum analysis of scattered protons demonstrate a primary quasi free process on nucleons. No indication of knock out reactions on clusters has been seen. The residual nuclei are mainly produced by evaporation processes. A theoretical calculation involving intranuclear cascades and evaporation processes has been performed. The nucleus model is based upon a Fermi gas and nuclear density agrees with diffusion electron experiments. Residual nuclei far from target are well described with a such model. Residual nuclei near the target are sensitive to the nuclear structure [fr

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

    International Nuclear Information System (INIS)

    Brancaccio, Franco; Dias, Mauro da Silva; Toledo, Fabio de

    2009-01-01

    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 60 Co sample measurement are discussed and compared to the results obtained with two different conventional coincidence systems. (author)

  18. Perfect/complete scattering experiments. Probing quantum mechanics on atomic and molecular collisions and coincidences

    International Nuclear Information System (INIS)

    Lohmann, Bernd; Grum-Grzhimailo, Alexei N.; Kleinpoppen, Hans

    2013-01-01

    Derives parameters for electrons, photons, atoms, ions, molecules calculated from theory. Delivers the quantum mechanical knowledge of atomic and molecular physics. Presents state-of-the-art experiments in atomic and molecular physics and related theoretical approaches. The main goal of this book is to elucidate what kind of experiment must be performed in order to determine the full set of independent parameters which can be extracted and calculated from theory, where electrons, photons, atoms, ions, molecules, or molecular ions may serve as the interacting constituents of matter. The feasibility of such perfect' and-or 'complete' experiments, providing the complete quantum mechanical knowledge of the process, is associated with the enormous potential of modern research techniques, both, in experiment and theory. It is even difficult to overestimate the role of theory in setting of the complete experiment, starting with the fact that an experiment can be complete only within a certain theoretical framework, and ending with the direct prescription of what, and in what conditions should be measured to make the experiment 'complete'. The language of the related theory is the language of quantum mechanical amplitudes and their relative phases. This book captures the spirit of research in the direction of the complete experiment in atomic and molecular physics, considering some of the basic quantum processes: scattering, Auger decay and photo-ionization. It includes a description of the experimental methods used to realize, step by step, the complete experiment up to the level of the amplitudes and phases. The corresponding arsenal includes, beyond determining the total cross section, the observation of angle and spin resolved quantities, photon polarization and correlation parameters, measurements applying coincidence techniques, preparing initially polarized targets, and even more sophisticated methods. The 'complete' experiment is, until today, hardly to perform

  19. Perfect/complete scattering experiments. Probing quantum mechanics on atomic and molecular collisions and coincidences

    Energy Technology Data Exchange (ETDEWEB)

    Lohmann, Bernd [Muenster Univ. (Germany). Inst. fuer Theoretische Physik 1; Grum-Grzhimailo, Alexei N. [Moscow State Univ. (Russian Federation). Skobeltsyn Inst. of Nuclear Physics; Kleinpoppen, Hans

    2013-07-01

    Derives parameters for electrons, photons, atoms, ions, molecules calculated from theory. Delivers the quantum mechanical knowledge of atomic and molecular physics. Presents state-of-the-art experiments in atomic and molecular physics and related theoretical approaches. The main goal of this book is to elucidate what kind of experiment must be performed in order to determine the full set of independent parameters which can be extracted and calculated from theory, where electrons, photons, atoms, ions, molecules, or molecular ions may serve as the interacting constituents of matter. The feasibility of such perfect' and-or 'complete' experiments, providing the complete quantum mechanical knowledge of the process, is associated with the enormous potential of modern research techniques, both, in experiment and theory. It is even difficult to overestimate the role of theory in setting of the complete experiment, starting with the fact that an experiment can be complete only within a certain theoretical framework, and ending with the direct prescription of what, and in what conditions should be measured to make the experiment 'complete'. The language of the related theory is the language of quantum mechanical amplitudes and their relative phases. This book captures the spirit of research in the direction of the complete experiment in atomic and molecular physics, considering some of the basic quantum processes: scattering, Auger decay and photo-ionization. It includes a description of the experimental methods used to realize, step by step, the complete experiment up to the level of the amplitudes and phases. The corresponding arsenal includes, beyond determining the total cross section, the observation of angle and spin resolved quantities, photon polarization and correlation parameters, measurements applying coincidence techniques, preparing initially polarized targets, and even more sophisticated methods. The 'complete' experiment is

  20. 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)

    Suzuki, Shogo; Okada, Yukiko; Hirai, Shoji

    2005-01-01

    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 10 12 n cm -2 s -1 (pneumatic transfer) and for a long time (6 h) at a thermal neutron flux of 3.7 x 10 12 n cm -2 s -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)

  1. 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

  2. Passive neutron coincidence counting with plastic scintillators for the characterization of radioactive waste drums

    Energy Technology Data Exchange (ETDEWEB)

    Deyglun, C.; Simony, B.; Perot, B.; Carasco, C. [CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 Saint-Paul-lez-Durance (France); Saurel, N.; Colas, S. [CEA, DAM, Valduc, F-21120 Is-sur-Tille (France); Collot, J. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Grenoble Alpes, CNRS/IN2P3, Grenoble (France)

    2015-07-01

    The quantification of radioactive material is essential in the fields of safeguards, criticality control of nuclear processes, dismantling of nuclear facilities and components, or radioactive waste characterization. The Nuclear Measurement Laboratory (LMN) of CEA is involved in the development of time-correlated neutron detection techniques using plastic scintillators. Usually, 3He proportional counters are used for passive neutron coincidence counting owing to their high thermal neutron capture efficiency and gamma insensitivity. However, the global {sup 3}He shortage in the past few years has made these detectors extremely expensive. In addition, contrary to {sup 3}He counters for which a few tens of microseconds are needed to thermalize fast neutrons, in view to maximize the {sup 3}He(n,p){sup 3}H capture cross section, plastic scintillators are based on elastic scattering and therefore the light signal is formed within a few nanoseconds, correlated pulses being detected within a few dozen- or hundred nanoseconds. This time span reflects fission particles time of flight, which allows reducing accordingly the duration of the coincidence gate and thus the rate of random coincidences, which may totally blind fission coincidences when using {sup 3}He counters in case of a high (α,n) reaction rate. However, plastic scintillators are very sensitive to gamma rays, requiring the use of a thick metallic shield to reduce the corresponding background. Cross talk between detectors is also a major issue, which consists on the detection of one particle by several detectors due to elastic or inelastic scattering, leading to true but undesired coincidences. Data analysis algorithms are tested to minimize cross-talk in simultaneously activated detectors. The distinction between useful fission coincidences and the correlated background due to cross-talk, (α,n) and induced (n,2n) or (n,n'γ) reactions, is achieved by measuring 3-fold coincidences. The performances of a

  3. 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.

  4. 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.

  5. Study on the eγ coincidences in the 169Lu decay

    International Nuclear Information System (INIS)

    Batsev, S.; Bonch-Osmolovskaya, N.A.; Budzyak, A.; Kuznetsov, V.V.; Usmanov, R.R.

    1979-01-01

    The 169 Lu→ 169 Yb decay scheme was analyzed on the basis of measurements of eγ coincidence. The 169 Lu sources were obtained by irradiating a tantalum target by 660 MeV protons. The eγ-coincidence spectra were measured by an ironless β-spectrometer with a toroidal magnetic field and a detector. The γ-ray and eγ-coincidence spectra were processed by a computer. The results of processing the 169 Lu coincidence spectra are tabulated. No excited states of 169 Yb not confirmed by γγ and eγ coincidences (except for the head level of the 3/2 + (651) 720 keV band) remain in the 169 Lu decay scheme proposed. Weak transitions with the total intensity of no more than 3.3% per a 169 Lu decay have remained unarranged, they should discharge weakly excited levels of 169 Yb. Probabilities of the 169 Yb level population per a 169 Lu decay and the corresponding values of probabilities of transitions in them are presented. As a whole, the 169 Lu decay scheme involves 60 levels, 31 states of them are new

  6. Determination of 131mXe and 133mXe in the presence of 133gXe via combined beta-spectroscopy and delayed coincidence

    International Nuclear Information System (INIS)

    Reeder, P.L.; Bowyer, T.W.; McIntyre, J.I.; Pitts, W.K.

    2001-01-01

    The International Monitoring System for the Comprehensive Nuclear-Test-Ban Treaty will include measurements of Xe fission products. Pacific Northwest National Laboratory has developed an automated system for separating Xe from air which detects Xe fission products using a beta-gamma counting system for 131m Xe, 133m Xe, 133g Xe, and 135g Xe. Betas and conversion electrons are detected in a plastic scintillation cell containing the Xe sample. Gamma and X-rays are detected in a NaI(Tl) scintillation detector which surrounds the plastic scintillator sample cell. Two-dimensional pulse-height spectra of gamma-energy versus beta-energy are obtained. The plastic scintillator spectrum in coincidence with the 31-keV X-rays from 131m Xe. 133m Xe, and 133g Xe is a complex mixture of conversion electrons and betas. A new technique to simultaneously measure the delayed coincidence (T 1/2 = 6.27 ns) between beta-particles from 133g Xe and conversion electrons depopulating the 81-keV state in 133 Cs is being developed. This technique allows separation of the 133g Xe beta spectrum from the conversion electrons due to 131m Xe and 133m Xe and uniquely quantifies all three nuclides. (author)

  7. Determination of 131m Xe and 133m Xe in the presence of 133gXe via combined beta-spectroscopy and delayed coincidence

    International Nuclear Information System (INIS)

    Reeder, Paul L.; Bowyer, Ted W.; McIntyre, Justin I.; Pitts, W K.

    2001-01-01

    The International Monitoring System for the Comprehensive Nuclear-Test-Ban Treaty will include measurements of Xe fission products. Pacific Northwest National Laboratory has developed an automated system for separating Xe from air which detects Xe fission products using a beta-gamma counting system for 131mXe, 133mXe, 133Xe, and 135Xe. Betas and conversion electrons are detected in a plastic scintillation cell containing the Xe sample. Gamma and X-rays are detected in a NaI(Tl) scintillation detector which surrounds the plastic scintillator sample cell. Two-dimensional pulse height spectra of gamma energy versus beta energy are obtained. The plastic scintillator spectrum in coincidence with the 31-keV X-rays from 131mXe. 133mXe, and 133Xe is a complex mixture of conversion electrons and betas. A new technique to simultaneously measure the delayed coincidence (t1/2 = 6.27 ns) between beta particles from 133Xe and conversion electrons depopulating the 81-keV state in 133Cs is being developed. This technique will allow separation of the 133Xe spectrum from the conversion electrons due to 131mXe and 133mXe and will uniquely quantify all three nuclides

  8. 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)

    Takeda, Mauro Noriaki

    2006-01-01

    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: 134 Cs, 72 Ga which disintegrate by β - transition, 133 Ba which disintegrates by electronic capture and 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)

  9. A theoretical basis for the analysis of multiversion software subject to coincident errors

    Science.gov (United States)

    Eckhardt, D. E., Jr.; Lee, L. D.

    1985-01-01

    Fundamental to the development of redundant software techniques (known as fault-tolerant software) is an understanding of the impact of multiple joint occurrences of errors, referred to here as coincident errors. A theoretical basis for the study of redundant software is developed which: (1) provides a probabilistic framework for empirically evaluating the effectiveness of a general multiversion strategy when component versions are subject to coincident errors, and (2) permits an analytical study of the effects of these errors. An intensity function, called the intensity of coincident errors, has a central role in this analysis. This function describes the propensity of programmers to introduce design faults in such a way that software components fail together when executing in the application environment. A condition under which a multiversion system is a better strategy than relying on a single version is given.

  10. Moisture corrections in neutron coincidence counting of PuO2

    International Nuclear Information System (INIS)

    Stewart, J.E.; Menlove, H.O.

    1987-01-01

    Passive neutron coincidence counting is capable of 1% assay accuracy for pure, well-characterized PuO 2 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 PuO 2 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 % H 2 O. The procedure requires that the moisture level in the sample be known before the coincidence measurement

  11. Application of GESPECOR software for the calculation of coincidence summing effects in special cases

    International Nuclear Information System (INIS)

    Arnold, Dirk; Sima, Octavian

    2004-01-01

    In this work, coincidence summing correction factors have been measured for 133 Ba, 152 Eu and 88 Y point sources with a 50% relative efficiency p-type detector and a 25% relative efficiency n-type detector in two close-to-detector measurement geometries. The experimental data for 133 Ba and 152 Eu and the results obtained with the GESPECOR software reveal a complex structure of the conventional dead layer of the p-type detector. The high value of the coincidence summing correction factor for the 511 keV peak of 88 Y, in agreement with the values computed by GESPECOR, in this case cautions against the application of the semiempirical method for evaluating coincidence summing effects

  12. Instrumentation and data handling. I. Positron coincidence imaging with the TOKIM system

    International Nuclear Information System (INIS)

    Anon.

    1976-01-01

    In addition to the conventional singles mode of operation, the TOKIM system's two Anger-type gamma cameras may be used in the (stationary, 180 0 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

  13. System for ν-ν-coincidence spectra processing with data compression

    International Nuclear Information System (INIS)

    Byalko, A.A.; Volkov, N.G.; Tsupko-Sitnikov, V.M.; Churakov, A.K.

    1982-01-01

    Calculational algorithm and program for analyzing gamma-gamma coincidence spectra based on using the method of expansion in singular values for data compression (the SVD method) are described. Results of the testing of the program during the processing of coincidence spectrum for the low-energy region of transitions corresponding to decay 164 Lu → 164 Yb are given. The program is written in the FORTRAN language and is realized by the ES-1040 computer. The counting time constitutes about 20 min. It is concluded that the use of the SVD method permits to correct the data at the expense of distortion filtration caused with statistical deviations and random interferences, at that not distorting the initial data. The data compressed correspond more to theoretical suggestions of forms of semiconductor detector lines and two-dimensional line in the coincidence spectrum

  14. A flexible VME-based multiparametric apparatus for coincidence spectroscopy and investigation of parameters of detectors

    International Nuclear Information System (INIS)

    Jakubek, J.

    2000-01-01

    The methodology of Coincidence Instrumental Activation Analysis (CIAA) based on a three-parameter gamma-gamma coincidence spectrometer with two high-purity Ge detectors is presented. A flexible coincidence system was built on standard NIM spectrometric modules connected to a VME or CAMAC data acquisition system. The detailed setup of the system optimized for the maximum energy resolution, maximum data throughput (dead time correction, pile-up rejection) and maximum flexibility is described. The use of different data acquisition platforms is discussed (VME bus with several different controllers, CAMAC bus). The software developed for reading and basic processing of measured data is also described. The possibilities of off-line data evaluation are discussed. The system was tested with respect to its compliance with the criteria of the CIAA method. Some results of measurement by this method are also presented. The flexibility of the system is demonstrated on its ability to measure the time characteristics of different detectors. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Cowles, Christian C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Siciliano, Edward R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-10-01

    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.

  16. Determination of U-235 quantity in fresh fuel elements by neutron coincidence collar technique

    International Nuclear Information System (INIS)

    Almeida, M.C.M. de; Almeida, S.G. de; Marzo, M.A.S.; Moita, L.P.M.

    1990-01-01

    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)

  17. Automatic analysis algorithm for radionuclide pulse-height data from beta-gamma coincidence systems

    International Nuclear Information System (INIS)

    Foltz Biegalski, K.M.

    2001-01-01

    There are two acceptable noble gas monitoring measurement modes for Comprehensive Nuclear-Test-Ban-Treaty (CTBT) verification purposes defined in CTBT/PC/II/WG.B/1. These include beta-gamma coincidence and high-resolution gamma-spectrometry. There are at present no commercial, off-the-shelf (COTS) applications for the analysis of β-γ coincidence data. Development of such software is in progress at the Prototype International Data Centre (PIDC) for eventual deployment at the International Data Centre (IDC). Flowcharts detailing the automatic analysis algorithm for β-γ coincidence data to be coded at the PIDC is included. The program is being written in C with Oracle databasing capabilities. (author)

  18. Convergent input from brainstem coincidence detectors onto delay-sensitive neurons in the inferior colliculus.

    Science.gov (United States)

    McAlpine, D; Jiang, D; Shackleton, T M; Palmer, A R

    1998-08-01

    Responses of low-frequency neurons in the inferior colliculus (IC) of anesthetized guinea pigs were studied with binaural beats to assess their mean best interaural phase (BP) to a range of stimulating frequencies. Phase plots (stimulating frequency vs BP) were produced, from which measures of characteristic delay (CD) and characteristic phase (CP) for each neuron were obtained. The CD provides an estimate of the difference in travel time from each ear to coincidence-detector neurons in the brainstem. The CP indicates the mechanism underpinning the coincidence detector responses. A linear phase plot indicates a single, constant delay between the coincidence-detector inputs from the two ears. In more than half (54 of 90) of the neurons, the phase plot was not linear. We hypothesized that neurons with nonlinear phase plots received convergent input from brainstem coincidence detectors with different CDs. Presentation of a second tone with a fixed, unfavorable delay suppressed the response of one input, linearizing the phase plot and revealing other inputs to be relatively simple coincidence detectors. For some neurons with highly complex phase plots, the suppressor tone altered BP values, but did not resolve the nature of the inputs. For neurons with linear phase plots, the suppressor tone either completely abolished their responses or reduced their discharge rate with no change in BP. By selectively suppressing inputs with a second tone, we are able to reveal the nature of underlying binaural inputs to IC neurons, confirming the hypothesis that the complex phase plots of many IC neurons are a result of convergence from simple brainstem coincidence detectors.

  19. Analysis of radionuclide mixtures by {alpha}-{gamma} and {beta}-{gamma} coincidences using a simple device; Analyse de melanges de radionucleides par un dispositif simple de coincidences {alpha}-{gamma} et {beta}-{gamma}

    Energy Technology Data Exchange (ETDEWEB)

    Pottier, R; Berger, R [Commissariat a l' Energie Atomique, Centre d' Etudes Nucleaires de Fontenay-aux-Roses, 92 (France)

    1966-06-01

    A procedure is described for the qualitative and quantitative spectrographic analysis of radioactive sources containing two alpha-gamma emitters having the same alpha energy or two beta-gamma emitters having the same gamma energy. The main apparatus is a multichannel pulse-height analyzer including a coincidence circuit. The principle of the method, the synoptic scheme, the electronic device, the type of sources, and the precautions to be taken or the corrections to take into account are reported. The results obtained in solving the three following problems are discussed as examples of applications of the method: analysis of {sup 241}Am in alpha-gamma sources containing {sup 238}Pu; analysis of {sup 237}Np in beta-gamma sources containing {sup 239}Pu; and analysis of {sup 106}Ru-{sup 106}Rh in beta-gamma sources containing {sup 95}Zr-{sup 95}Nb. (authors) [French] Dans ce. rapport, on presente une methode d'analyse spectrographique qualitative et quantitative de sources radioactives contenant deux emetteurs alpha-gamma de meme energie alpha et deux emetteurs beta-gamma de meme energie gamma. L'organe principal est un analyseur d'amplitude a 400 canaux comprenant un circuit de coincidence. On decrit le principe de la methode, le schema synoptique, l'appareillage, le type des sources, les precautions a prendre ou les corrections a faire. On discute les resultats obtenus dans la solution des trois problemes suivants traites a titre d'application de la methode: 1. analyse d'americium 241 en presence de plutonium 238; 2. analyse de neptunium 237 en presence de plutonium 239; 3. analyse de ruthenium 106-rhodium 106 en presence de zirconium 95-niobium 95. (auteurs)

  20. A 15 channel 2- and 3-fold coincidence counting system for radioactivity standardization

    International Nuclear Information System (INIS)

    Simpson, B.R.S.; Meyer, B.R.; Raave, D.A.

    1986-01-01

    The 4π β-γ liquid scintillation coincidence counting system which is used at the National Accelerator Centre for standardizing radioisotopes, has been extended to allow for up to fifteen data points to be measured simultaneously by introducing a 15-fold coincidence unit and a 32-channel scaler into the system. A new control / data acquisition computer program has been written and its operation explained in detail. The advantages of the new system are discussed, and the activity of a 139 Ce source as measured by the new system and the old 3-fold system is compared

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

    International Nuclear Information System (INIS)

    Masse, D.

    1990-10-01

    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 60 Co and 137 Cs gamma-ray sources. The results for the measurement of 189 Ir (Compton suppression) and for the measurement of 101 Rh (gamma-gamma coincidence) in the presence of other radioisotopes are given. 83 Rb and 105 Ag isotopes are also measured with this spectrometer [fr

  2. Boron-Coated Straw Collar for Uranium Neutron Coincidence Collar Replacement

    International Nuclear Information System (INIS)

    Hu, Jianwei; Croft, Stephen; McElroy, Robert Dennis

    2017-01-01

    The objective of this project was to design and optimize, in simulation space, an active neutron coincidence counter (or collar) using boron-coated straws (BCSs) as a non- 3 He replacement to the Uranium Neutron Coincidence Collar (UNCL). UNCL has been used by the International Atomic Energy Agency (IAEA) and European Atomic Energy Community (Euratom) since the 1980s to verify the 235 U content in fresh light water reactor fuel assemblies for safeguards purposes. This report documents the design and optimization of the BCS collar.

  3. Boron-Coated Straw Collar for Uranium Neutron Coincidence Collar Replacement

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jianwei [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Croft, Stephen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McElroy, Robert Dennis [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-01-01

    The objective of this project was to design and optimize, in simulation space, an active neutron coincidence counter (or collar) using boron-coated straws (BCSs) as a non-3He replacement to the Uranium Neutron Coincidence Collar (UNCL). UNCL has been used by the International Atomic Energy Agency (IAEA) and European Atomic Energy Community (Euratom) since the 1980s to verify the 235U content in fresh light water reactor fuel assemblies for safeguards purposes. This report documents the design and optimization of the BCS collar.

  4. Determination of plutonium in nuclear fuels using the neutron coincidence method

    International Nuclear Information System (INIS)

    Boehnel, K.

    1978-03-01

    In assays for plutonium the neutron coincidence technique is often used. This method which is based on measuring spontaneous fission rates is examined both experimentally and theoretically. A novel coincidence unit is described which works in effect without deadtime and which therefore has advantages over the currently used design. For waste samples a principle for measurement is described which avoids space dependence effects by rotating the probe in an asymmetric detector. Formulae are developed for the statistical error and various effects of deadtimes are discussed. Further it is shown that neutron multiplication in the sample is an important source of errors, especially when the (α, n)-background is neglected. (author)

  5. Unexpected decline in tuberculosis cases coincident with economic recession -- United States, 2009

    Directory of Open Access Journals (Sweden)

    Winston Carla A

    2011-11-01

    Full Text Available Abstract Background Since 1953, through the cooperation of state and local health departments, the U.S. Centers for Disease Control and Prevention (CDC has collected information on incident cases of tuberculosis (TB disease in the United States. In 2009, TB case rates declined -11.4%, compared to an average annual -3.8% decline since 2000. The unexpectedly large decline raised concerns that TB cases may have gone unreported. To address the unexpected decline, we examined trends from multiple sources on TB treatment initiation, medication sales, and laboratory and genotyping data on culture-positive TB. Methods We analyzed 142,174 incident TB cases reported to the U. S. National Tuberculosis Surveillance System (NTSS during January 1, 2000-December 31, 2009; TB control program data from 59 public health reporting areas; self-reported data from 50 CDC-funded public health laboratories; monthly electronic prescription claims for new TB therapy prescriptions; and complete genotyping results available for NTSS cases. Accounting for prior trends using regression and time-series analyses, we calculated the deviation between observed and expected TB cases in 2009 according to patient and clinical characteristics, and assessed at what point in time the deviation occurred. Results The overall deviation in TB cases in 2009 was -7.9%, with -994 fewer cases reported than expected (P Conclusions Our assessments show that the decline in reported TB was not an artifact of changes in surveillance methods; rather, similar declines were found through multiple data sources. While the steady decline of TB cases before 2009 suggests ongoing improvement in TB control, we were not able to identify any substantial change in TB control activities or TB transmission that would account for the abrupt decline in 2009. It is possible that other multiple causes coincident with economic recession in the United States, including decreased immigration and delayed access to

  6. Coincidence measurements of slow recoil ions with projectile ions in 42-MeV Arq+-Ar collisions

    International Nuclear Information System (INIS)

    Tonuma, T.; Kumagai, H.; Matsuo, T.; Tawara, H.

    1989-01-01

    Slow Ar recoil-ion production cross sections by projectiles of 1.05-MeV/amu Ar q+ (q=4,6,8,10,12,14) were measured using a projectile-ion--recoil-ion coincidence technique. The present results indicate that the average recoil ion charges left-angle i right-angle increase with increasing the incident projectile charge q and the number of the lost and captured electrons from and/or into projectiles, whereas the projectile charge-changing cross sections for loss ionization decrease steeply with increasing q for low-charge-state projectiles, and those for transfer ionization increase rapidly with increasing q for high-charge-state projectiles. For Ar projectiles with q=10, which corresponds to the equilibrium charge state of Ar projectiles at the present collision energy, the average recoil-ion charges are nearly the same in both loss and transfer ionization, and a pure ionization process plays a much more important role in producing highly charged recoil ions, in contrast to projectile electron loss or transfer processes, which play a role in other projectile charge states

  7. THE LIMITED EFFECT OF COINCIDENT ORIENTATION ON THE CHOICE OF INTRINSIC AXIS (.).

    Science.gov (United States)

    Li, Jing; Su, Wei

    2015-06-01

    The allocentric system computes and represents general object-to-object spatial relationships to provide a spatial frame of reference other than the egocentric system. The intrinsic frame-of-reference system theory, which suggests people learn the locations of objects based upon an intrinsic axis, is important in research about the allocentric system. The purpose of the current study was to determine whether the effect of coincident orientation on the choice of intrinsic axis was limited. Two groups of participants (24 men, 24 women; M age = 24 yr., SD = 2) encoded different spatial layouts in which the objects shared the coincident orientation of 315° and 225° separately at learning perspective (0°). The response pattern of partial-scene-recognition task following learning reflected different strategies for choosing the intrinsic axis under different conditions. Under the 315° object-orientation condition, the objects' coincident orientation was as important as the symmetric axis in the choice of the intrinsic axis. However, participants were more likely to choose the symmetric axis as the intrinsic axis under the 225° object-orientation condition. The results suggest the effect of coincident orientation on the choice of intrinsic axis is limited.

  8. Calibration and adjustment of the EGRET coincidence/time-of-flight system

    International Nuclear Information System (INIS)

    Hunter, S.D.

    1991-01-01

    The coincidence/time-of-flight system of the energetic gamma ray experiment telescope (EGRET) on NASA's Gamma Ray Observatory (GRO) consists of two layers of sixteen scintillator tiles. These tiles are paired into 96 coincidence telescopes. Valid coincidence and time-of-flight values (indicating downward moving particles) from one of these telescopes are two of the requirements for an EGRET event trigger. To maximize up-down discrimination, variations in the mean timing value of the telescopes must be minimized. The timing values of the 96 telescopes are not independent, hence they cannot be individually adjusted to calibrate the system. An iterative approach was devised to determine adjustments to the length of the photomultiplier signal cables. These adjustments were made directly in units of time using a time domain reflectometry technique, by timing the reflection of a fast pulse from the unterminated end of eable, and observing the charge in signal propagation time as the length of the cable was shortened. Two constant fraction discriminators, a time-to-amplitude converter and a pulse height analyzer were used for these measurements. Using this direct time measuring approach, the timing values for the 96 EGRET coincidence/time-of-flight telescopes were adjusted with an FWHM variation of less than 450 ps (± 1 TOF timing channel). (orig.)

  9. Evaluation of in-plant neutron coincidence counters for the measurement of molten salt extraction residues

    International Nuclear Information System (INIS)

    Langner, D.G.; Russo, P.A.; Wachter, J.R.

    1993-01-01

    Americium is extracted from plutonium by a molten salt extraction (MSE) process. The residual americium-laden salts are a significant waste stream in this pyrochemical purification process. Rapid assay of MSE residues is desirable to minimize the exposure of personnel to these often high-level emissions. However, the quantitative assay of plutonium in MSE residues is difficult. Variable, unknown (a,n) rates and variable emitted-neutron energy spectra preclude the use of standard neutron coincidence counting techniques with old-generation neutron coincidence counters. Gamma-ray assay methods have not been successful with some residues because of random lumps of plutonium metal. In this paper, we present measurements of MSE residues with two state-of-the-art neutron coincidence counters at the Los Alamos Plutonium Processing Facility: an in-line counter built for the assay of bulk waste material and the pyrochemical multiplicity counter that underwent test and evaluation at that facility. Both of these counters were designed to minimize the effects on measurements of variations in the sample geometry and variable energy spectra of emitted neutrons. These results are compared to measurements made with an HLNCII and with a 20-yr-old in-line well counter. The latter two counters are not optimized in ft sense. We conclude that the newer counters provide significantly improved assay results. The pyrochemical multiplicity counter operated in the conventional coincidence mode provided the best assays overall

  10. Performance Evaluation of the Neutron Coincidence Counter for the Advanced Spent Fuel Conditioning Process

    International Nuclear Information System (INIS)

    Lee, S.Y.; Li, T.K.; Menlove, Howard O.; Kim, H.D.; Ko, W.I.; Park, S.W.

    2005-01-01

    The Advanced Spent Fuel Conditioning Process (ACP) is a pyrochemical dry reprocessing technique to convert oxide-type spent nuclear fuel into a metallic form. The Korea Atomic Energy Research Institute (KAERI) has been developing this technology for the purpose of spent fuel management and is planning to perform a lab-scale demonstration in 2006. With this technology, a significant reduction of the volume and heat load of spent fuel is expected, which could decrease the burden of safety and economics. In this study, MCNPX code calculations were carried out to estimate the performance of a neutron coincidence counter designed for measruement of the process materials in the pilot-scale ACP facility. To verify the design requirement, the singles and doubles counting rates of the detectors were simulated with the latest coincidence capability of the MCNPX code. Then, the precision of the coincidence measurements were evaluated on various process materials from the ACP. It was verified that the performance of the neutron coincidence counter could meet the design criteria for all samples in the ACP, and the material accounting system for the pilot-scale ACP facility could meet the IAEA safeguards goals.

  11. Constructing coincident indices of economic activity for the Latin American economy

    Directory of Open Access Journals (Sweden)

    João Victor Issler

    2013-03-01

    Full Text Available This paper has three main contributions. The first is to propose an individual coincident indicator for the following Latin American countries: Argentina, Brazil, Chile, Colombia and Mexico. In order to obtain similar series to those traditionally used in business-cycle research in constructing coincident indices (output, sales, income and employment we were forced to back-cast several individual country series which were not available in a long time-series span. The second contribution is to establish a chronology of recessions for these countries, covering the period from 1980 to 2012 on a monthly basis. Based on this chronology, the countries are compared in several respects. The final contribution is to propose an aggregate coincident indicator for the Latin American economy, which weights individual-country composite indices. Finally, this indicator is compared with the coincident indicator (The Conference Board - TCB of the U.S. economy. We find that the U.S. indicator Granger-causes the Latin American indicator in statistical tests

  12. Increased coincidence detection for quantum versus pseudo-generated random numbers

    NARCIS (Netherlands)

    Boshoff, Lieze; Jolij, Jacob

    2015-01-01

    People often see meaning in stimuli that are typically considered meaningless. According to Von Lucadou’s idea of Generalized Quantum Teory (GQT), such perceived coincidences, or examples of synchronicity, may be the result of entanglement between a conscious observer and the physical world. Here we

  13. Use of sum-peak and coincidence counting methods for activity standardization of {sup 22}Na

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, E.M. de, E-mail: estela@ird.gov.br [Laboratorio Nacional de Metrologia das Radiacoes Ionizantes (LNMRI/IRD/CNEN), Av. Salvador Allende, s/n, Recreio, CEP 22780-160 Rio de Janeiro (Brazil); Iwahara, A.; Poledna, R. [Laboratorio Nacional de Metrologia das Radiacoes Ionizantes (LNMRI/IRD/CNEN), Av. Salvador Allende, s/n, Recreio, CEP 22780-160 Rio de Janeiro (Brazil); Silva, M.A.L. da [Coordenacao Geral de Instalacoes Nucleares/Comissao Nacional de Energia Nuclear, R. Gal. Severiano, 90 - Botafogo, CEP 22290-901 Rio de Janeiro (Brazil); Tauhata, L. [Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ), Av. Erasmo Braga, 118-6 Degree-Sign andar, CEP 20020-000 Centro, Rio de Janeiro (Brazil); Delgado, J.U. [Laboratorio Nacional de Metrologia das Radiacoes Ionizantes (LNMRI/IRD/CNEN), Av. Salvador Allende, s/n, Recreio, CEP 22780-160 Rio de Janeiro (Brazil); Lopes, R.T. [Laboratorio de Instrumentacao Nuclear (LIN/PEN/COPPE/UFRJ), Caixa Postal 68509, CEP 21945-970 Rio de Janeiro (Brazil)

    2012-09-21

    A solution containing the positron emitter {sup 22}Na has been absolutely standardized using the 4{pi}{beta}-{gamma} coincidence counting method and the sum-peak spectrometry counting method. In the 4{pi}{beta}-{gamma} coincidence method two ways for the activity concentration measurements were used: gating on the 1275 keV photopeak and on the 1786 keV sum-peak where the knowledge of the {beta}{sup +}-branching ratio is required. In the sum-peak method the measurements were carried out using three experimental arrangements: the first composed by a well type 5 in. Multiplication-Sign 5 in. NaI(Tl) scintillation crystal, the second by a 3 in. Multiplication-Sign 3 in. NaI(Tl) scintillation crystal placed on the top of the first, resulting in a 4{pi} counting geometry and the third arrangement is a high purity coaxial germanium detector. The results that are obtained by these two methods are compatible within the standard uncertainty values with a coverage factor of k=2 ({approx}95% of the confidence level). This means that the sum-peak counting with its more simple experimental setup than the complex coincidence 4{pi}{beta}-{gamma} counting system gives consistent results for the activity standardization of {sup 22}Na with smaller uncertainties. Besides, the time period involved to attain the result of the standardization was quite shorter than the coincidence measurements used in this work.

  14. Study of Thermal Equilibrium in Heavy Ion Collisions via the Ma Coincidence Method - Test of Applicability

    International Nuclear Information System (INIS)

    Kirejczyk, M.

    2002-01-01

    The coincidence method of judging whether a system reached thermal equilibrium is shortly presented. It is used on the model data to test, whether it is applicable in the low-relativistic energy range. Also, the cuts corresponding to real detectors are introduced and their influence is briefly discussed. (author)

  15. Pre-coincidence brain activity predicts the perceptual outcome of streaming/bouncing motion display.

    Science.gov (United States)

    Zhao, Song; Wang, Yajie; Jia, Lina; Feng, Chengzhi; Liao, Yu; Feng, Wenfeng

    2017-08-18

    When two identical visual discs move toward each other on a two-dimensional visual display, they can be perceived as either "streaming through" or "bouncing off" each other after their coincidence. Previous studies have observed a strong bias toward the streaming percept. Additionally, the incidence of the bouncing percept in this ambiguous display could be increased by various factors, such as a brief sound at the moment of coincidence and a momentary pause of the two discs. The streaming/bouncing bistable motion phenomenon has been studied intensively since its discovery. However, little is known regarding the neural basis underling the perceptual ambiguity in the classic version of the streaming/bouncing motion display. The present study investigated the neural basis of the perception disambiguating underling the processing of the streaming/bouncing bistable motion display using event-related potential (ERP) recordings. Surprisingly, the amplitude of frontal central P2 (220-260 ms) that was elicited by the moving discs ~200 ms before the coincidence of the two discs was observed to be predictive of subsequent streaming or bouncing percept. A larger P2 amplitude was observed for streaming percept than the bouncing percept. These findings suggest that the streaming/bouncing bistable perception may have been disambiguated unconsciously ~200 ms before the coincidence of the two discs.

  16. Pulse shaping for fast coincidence with NaI(Tl) detectors

    International Nuclear Information System (INIS)

    Bose, S.; Sinha, B.K.; Bhattacharya, R.

    1983-01-01

    The effect of multiple limiting of the anode pulses of the photomultiplier tubes on the resolving time of an NaI(Tl)-NaI(Tl) fast coincidence set up is investigated with the help of a simple transistored limiter circuit. The performance of the set up for different energy ranges selected in the side channels is also investigated. (orig.)

  17. Metformin and lactic acidosis : cause or coincidence? A review of case reports

    NARCIS (Netherlands)

    Stades, AME; Heikens, JT; Erkelens, DW; Holleman, F; Hoekstra, JBL

    Objective. Metformin has been associated with the serious side-effect lactic acidosis. However, it remains unclear whether the use of metformin was a cause or a coincidence in lactic acidosis. Design. A literature search of the Index Medicus (1959-66) and of the databases Embase, Medline, Medline

  18. Metformin and lactic acidosis: cause or coincidence? A review of case reports

    NARCIS (Netherlands)

    Stades, A. M. E.; Heikens, J. T.; Erkelens, D. W.; Holleman, F.; Hoekstra, J. B. L.

    2004-01-01

    Objective. Metformin has been associated with the serious side-effect lactic acidosis. However, it remains unclear whether the use of metformin was a cause or a coincidence in lactic acidosis. Design. A literature search of the Index Medicus (1959-66) and of the databases Embase, Medline, Medline

  19. Field test and calibration of neutron coincidence counters for high-mass plutonium samples

    International Nuclear Information System (INIS)

    Menlove, H.O.; Dickinson, R.J.; Douglas, I.

    1987-02-01

    Five different neutron coincidence systems were evaluated and calibrated for high-mass PuO 2 samples. The samples were from 2 to 7.2 kg of PuO 2 in mass, with a large range of burnup. This report compares the equipment and the results, with an evaluation of deadtime and multiplication corrections

  20. Interacting dark sector and the coincidence problem within the scope of LRS Bianchi type I model

    Science.gov (United States)

    Muharlyamov, Ruslan K.; Pankratyeva, Tatiana N.

    2018-05-01

    It is shown that a suitable interaction between dark energy and dark matter in locally rotationally symmetric (LRS) Bianchi-I space-time can solve the coincidence problem and not contradict the accelerated expansion of present Universe. The interaction parameters are estimated from observational data.

  1. The memory coincidence system (CALI). Principle and use for the multidetector experiments in nuclear physics

    International Nuclear Information System (INIS)

    Pouthas, J.

    1984-01-01

    In an experimental set up, the main function of the ''CALI system'' is to achieve ''coincidence'' between logic channels. This system also provides a fast selection of the events and their identification by a digital word, and the connection to the data acquisition system [fr

  2. Detecting gravitational waves from inspiraling binaries with a network of detectors: Coherent versus coincident strategies

    International Nuclear Information System (INIS)

    Mukhopadhyay, Himan; Dhurandhar, Sanjeev; Sago, Norichika; Tagoshi, Hideyuki; Takahashi, Hirotaka; Kanda, Nobuyuki

    2006-01-01

    We compare two strategies of multidetector detection of compact binary inspiral signals, namely, the coincidence and the coherent. For simplicity we consider here two identical detectors having the same power spectral density of noise, that of initial LIGO, located in the same place and having the same orientation. We consider the cases of independent noise as well as that of correlated noise. The coincident strategy involves separately making two candidate event lists, one for each detector, and from these choosing those pairs of events from the two lists which lie within a suitable parameter window, which then are called coincidence detections. The coherent strategy on the other hand involves combining the data phase coherently, so as to obtain a single network statistic which is then compared with a single threshold. Here we attempt to shed light on the question as to which strategy is better. We compare the performances of the two methods by plotting the receiver operating characteristics (ROC) for the two strategies. Several of the results are obtained analytically in order to gain insight. Further we perform numerical simulations in order to determine certain parameters in the analytic formulae and thus obtain the final complete results. We consider here several cases from the relatively simple to the astrophysically more relevant in order to establish our results. The bottom line is that the coherent strategy although more computationally expensive in general than the coincidence strategy, is superior to the coincidence strategy--considerably less false dismissal probability for the same false alarm probability in the viable false alarm regime

  3. 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.)

  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. Calculation of “LS-curves” for coincidence summing corrections in gamma ray spectrometry

    Science.gov (United States)

    Vidmar, Tim; Korun, Matjaž

    2006-01-01

    When coincidence summing correction factors for extended samples are calculated in gamma-ray spectrometry from full-energy-peak and total efficiencies, their variation over the sample volume needs to be considered. In other words, the correction factors cannot be computed as if the sample were a point source. A method developed by Blaauw and Gelsema takes the variation of the efficiencies over the sample volume into account. It introduces the so-called LS-curve in the calibration procedure and only requires the preparation of a single standard for each sample geometry. We propose to replace the standard preparation by calculation and we show that the LS-curves resulting from our method yield coincidence summing correction factors that are consistent with the LS values obtained from experimental data.

  6. Complete characterization of breakup of 9Be by α-α coincidence measurements

    International Nuclear Information System (INIS)

    Rafiei, R.; Luong, D.H.; Hinde, D.J.; Dasgupta, M.; Du Rietz, R.

    2011-01-01

    The breakup mechanisms for 9 Be have been studied through coincident detection of the breakup α particles at sub-barrier energies, where the probability of capture of a charged breakup fragment by the target nucleus is negligible. Combining the reconstructed reaction Q-value and the relative energy of the two coincident breakup α particles a complete picture of breakup dynamics has been obtained. The measurements reveal breakup processes which are fast enough (~ 10 -22 s) to affect fusion, called prompt breakup. It is shown that prompt breakup is triggered predominantly by the transfer of a neutron -a two-step process. The prompt breakup probabilities are shown to have an exponential dependence on the surface-to-surface separation of the interacting nuclei, but are independent of the target nuclei, ranging from 144 Sm to 209 Bi. These results provide significant input towards a complete quantal model aiming to describe the breakup of weakly bound stable and halo nuclei. (author)

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

    International Nuclear Information System (INIS)

    Wardiyanto, Gatot; Pujadi

    2000-01-01

    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

  8. X-ray spectral line coincidences between fluorine VIII (and IX) and transition metal lines

    International Nuclear Information System (INIS)

    Charatis, G.; Rockett, P.D.; Burkhalter, P.G.

    1983-01-01

    X-ray spectroscopy was performed in the 12 to 15 A region, recording L-shell lines from selected laser-irradiated transition metals. Line coincidences and near coincidences were identified between Fe, Cr, Mn, and Ni L-spectra, and F VIII and F IX K-shell lines. Wavelengths were determined to accuracies of 1 to 3 mA and will be utilized in selecting potential pumping candidates in future x-ray lasing schemes. High-resolution x-ray spectra were collected under controlled illumination and target conditions using 1.05 μm and 0.527 μm laser excitation with the KMS CHROMA laser

  9. Use of γ-γ coincidence spectrometry in the geochemical study of diamictites from South Africa

    International Nuclear Information System (INIS)

    Huber, H.; Koeberl, Ch.; McDonald, I.; Reimold, W.U.

    2000-01-01

    γ-γ coincidence spectrometry was used to investigate the possible presence of a meteoritical component in 27 samples of South African diamictites. Recently, several studies have suggested that some tillites/diamictites may represent impact breccias, but a petrographical study by our group found no evidence for the presence of impact-characteristic shocked minerals. The siderophile elements, such as Cr, Co, Ni, and, especially, the platinum group elements, have high abundances in meteorites, but low abundances in terrestrial crustal rocks. The Ir content of the diamictites was measured with the new iridium coincidence spectrometer (ICS) at the University of Vienna, with detection limits of around 0.02 ppb. No enrichments in the contents of Ir and other siderophile elements compared to average crustal concentrations were found; thus, no unequivocal evidence for an impact origin of these diamictites of the South African Dwyka Group can be documented. (author)

  10. Coincident site lattice-matched InGaN on (111) spinel substrates

    International Nuclear Information System (INIS)

    Norman, A. G.; Dippo, P. C.; Moutinho, H. R.; Simon, J.; Ptak, A. J.

    2012-01-01

    Coincident site lattice-matched wurtzite (0001) In 0.31 Ga 0.69 N, emitting in the important green wavelength region, is demonstrated by molecular beam epitaxy on a cubic (111) MgAl 2 O 4 spinel substrate. The coincident site lattice matching condition involves a 30 deg. rotation between the lattice of the InGaN epitaxial layer and the lattice of the spinel. This work describes an alternative approach towards realizing more compositionally homogenous InGaN films with low dislocation density emitting in the ''green gap'' of low efficiency currently observed for semiconductor light emitting diodes (LEDs). This approach could lead to higher efficiency green LEDs presently of great interest for solid-state lighting applications.

  11. Coincident site lattice-matched InGaN on (111) spinel substrates

    Energy Technology Data Exchange (ETDEWEB)

    Norman, A. G.; Dippo, P. C.; Moutinho, H. R.; Simon, J.; Ptak, A. J. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)

    2012-04-09

    Coincident site lattice-matched wurtzite (0001) In{sub 0.31}Ga{sub 0.69}N, emitting in the important green wavelength region, is demonstrated by molecular beam epitaxy on a cubic (111) MgAl{sub 2}O{sub 4} spinel substrate. The coincident site lattice matching condition involves a 30 deg. rotation between the lattice of the InGaN epitaxial layer and the lattice of the spinel. This work describes an alternative approach towards realizing more compositionally homogenous InGaN films with low dislocation density emitting in the ''green gap'' of low efficiency currently observed for semiconductor light emitting diodes (LEDs). This approach could lead to higher efficiency green LEDs presently of great interest for solid-state lighting applications.

  12. Ion-ion coincidence imaging at high event rate using an in-vacuum pixel detector

    Science.gov (United States)

    Long, Jingming; Furch, Federico J.; Durá, Judith; Tremsin, Anton S.; Vallerga, John; Schulz, Claus Peter; Rouzée, Arnaud; Vrakking, Marc J. J.

    2017-07-01

    A new ion-ion coincidence imaging spectrometer based on a pixelated complementary metal-oxide-semiconductor detector has been developed for the investigation of molecular ionization and fragmentation processes in strong laser fields. Used as a part of a velocity map imaging spectrometer, the detection system is comprised of a set of microchannel plates and a Timepix detector. A fast time-to-digital converter (TDC) is used to enhance the ion time-of-flight resolution by correlating timestamps registered separately by the Timepix detector and the TDC. In addition, sub-pixel spatial resolution (principle experiment on strong field dissociative double ionization of carbon dioxide molecules (CO2), using a 400 kHz repetition rate laser system. The experimental results demonstrate that the spectrometer can detect multiple ions in coincidence, making it a valuable tool for studying the fragmentation dynamics of molecules in strong laser fields.

  13. Performance evaluation of BGO block detectors used in positron emission tomography and a coincidence system

    International Nuclear Information System (INIS)

    Kim, J. H.; Choi, Y.; Lim, K. C.; Lee, M. Y.; Woo, S. K.; Lee, K. H.; Kim, S. E.; Choi, Y. S.; Kim, B. T.

    1999-01-01

    We investigated the basic performances of the BGO block detectors, which is used in the GE Advance positron emission tomography. The block detector is composed of 36 small BGO crystals coupled to two 2-channel photomultiplier tubes. In this study, we measured the crystal map and the intrinsic energy resolution of the detector. The coincidence signals between the detectors were also obtained using F-18. The intrinsic energy resolution of the block detector was 69% FWHM at 140 keV and 33% FWHM at 511 keV. High quality crystal map and the coincidence signals between the detectors were successfully obtained. The timing resolution of the detectors are being measured. The results of this study demonstrate the feasibility of developing high performance positron emission tomography

  14. Coincidence in the two-photon spectra of Li and Li2 at 735 nm

    International Nuclear Information System (INIS)

    DeGraffenreid, W; Sansonetti, Craig J

    2005-01-01

    A coincidence between the 2 2 S 1/2 -3 2 S 1/2 two-photon transition in the atomic spectrum of 6 Li and the X 1 Σ + g → E 1 Σ + g two-photon ro-vibrational series of 7 Li 2 was observed near 735 nm in a heat pipe oven using a tunable laser and thermionic diode detection scheme. The molecular transition obscures one component of the 6 Li atomic transition. Selective detection of the atomic transition was obtained by adding an intensity-modulated laser that drives atoms from the 3S to 16P state. The coincident molecular transition and four nearby molecular lines were identified using previously determined Dunham coefficients

  15. Studies of weak capture-gamma-ray resonances via coincidence techniques

    CERN Document Server

    Rowland, C; Champagne, A E; Dummer, A K; Fitzgerald, R; Harley, E C T; Mosher, J; Runkle, R

    2002-01-01

    A method for measuring weak capture-gamma-ray resonances via gamma gamma-coincidence counting techniques is described. The coincidence apparatus consisted of a large-volume germanium detector and an annular NaI(Tl) crystal. The setup was tested by measuring the weak E sub R =227 keV resonance in sup 2 sup 6 Mg(p,gamma) sup 2 sup 7 Al. Absolute germanium and NaI(Tl) counting efficiencies for a range of gamma-ray energies and for different detector-target geometries are presented. Studies of the gamma-ray background in our spectra are described. Compared to previous work, our method improves the detection sensitivity for weak capture-gamma-ray resonances by a factor of approx 100. The usefulness of the present technique for investigations of interest to nuclear astrophysics is discussed.

  16. Nuclear lifetime measurements with the DSA coincidence method in inverse reactions

    International Nuclear Information System (INIS)

    Hermans, J.A.J.

    1977-01-01

    This thesis describes lifetime measurements with the DSA coincidence method in inverse reactions. Bombardment of 2 H and 3 H targets with heavy ions of energies up to 50 MeV produces nuclei recoiling at initial velocities of v(0) approximately equal to 0.05 c. Heavy-ion beams of 11 B, 12 C, 14 N, 16 O, 18 O, 19 F, 27 A1, 28 Si, 30 Si, 31 P, 32 S, 35 Cl and 37 Cl are at present available from the Utrecht 6 MV EN tandem accelerator. The recoil nuclei are slowed down in Mg, Al, Cu, Ag or Au and the γ-ray Doppler pattern is observed with a large Ge(Li) detector in coincidence with protons

  17. Research of coincidence method for calculation model of the specific detector

    Energy Technology Data Exchange (ETDEWEB)

    Guangchun, Hu; Suping, Liu; Jian, Gong [China Academy of Engineering Physics, Mianyang (China). Inst. of Nuclear Physics and Chemistry

    2003-07-01

    The physical size of specific detector is known normally, but production business is classified for some sizes that is concerned with the property of detector, such as the well diameter, well depth of detector and dead region. The surface source of even distribution and the sampling method of source particle isotropy sport have been established with the method of Monte Carlo, and gamma ray respond spectral with the {sup 152}Eu surface source been calculated. The experiment have been performed under the same conditions. Calculation and experiment results are compared with relative efficiency coincidence method and spectral similar degree coincidence method. According to comparison as a result, detector model is revised repeatedly to determine the calculation model of detector and to calculate efficiency of detector and spectra. (authors)

  18. Selection and evaluation of gamma decay standards for detector calibration using coincidence method

    International Nuclear Information System (INIS)

    Hlavac, S.

    2000-01-01

    Coincidence method for calibration of gamma detectors using suitable calibration standards with two cascading gamma rays is analyzed. From the list of recommended gamma ray standards currently under reevaluation by the CRP, 14 radionuclides were selected as the potential source candidates for the coincidence method. The following sources were selected 24 Na, 46 Sc, 60 Co, 66 Ga, 75 Se, 88 Y, Nb 94 , 111 In, 123m Te, 133 Ba, 134 Cs, 152 Eu, 154 Eu and 207 Bi. Reaction 11 B (p,γ) 12 C* was also selected as a source of high energy gamma rays. Experimental data on angular correlation coefficients for selected sources were collected from the literature and evaluated according to the recommended procedure. Theoretical angular correlation coefficients were calculated and compared to the evaluated data. (author)

  19. Electronics and electronic systems

    CERN Document Server

    Olsen, George H

    1987-01-01

    Electronics and Electronic Systems explores the significant developments in the field of electronics and electronic devices. This book is organized into three parts encompassing 11 chapters that discuss the fundamental circuit theory and the principles of analog and digital electronics. This book deals first with the passive components of electronic systems, such as resistors, capacitors, and inductors. These topics are followed by a discussion on the analysis of electronic circuits, which involves three ways, namely, the actual circuit, graphical techniques, and rule of thumb. The remaining p

  20. n-Tupled Coincidence Point Theorems in Partially Ordered Metric Spaces for Compatible Mappings

    Directory of Open Access Journals (Sweden)

    Sumitra Dalal

    2014-01-01

    Full Text Available The intent of this paper is to introduce the notion of compatible mappings for n-tupled coincidence points due to (Imdad et al. (2013. Related examples are also given to support our main results. Our results are the generalizations of the results of (Gnana Bhaskar and Lakshmikantham (2006, Lakshmikantham and Ćirić (2009, Choudhury and Kundu (2010, and Choudhary et al. (2013.

  1. Coincidence study of alpha particle fragmentation at E/sub alpha/ = 140 MeV

    International Nuclear Information System (INIS)

    Koontz, R.W.

    1980-01-01

    Results of an experimental study of the interaction of 140 MeV alpha particles with 90 Zr nuclei resulting in fragmentation of the alpha particle are reported. The experimental observations of the study are analyzed and are found to show that alpha particle breakup reactions leading to at least 4-body final states, composed of two charged alpha particle fragments, contribute significantly to the singles yield of charged fragments observed at a fixed forward angle. The conclusions are based on coincidence measurements where one charged fragment is detected at a small forward angle which remains fixed, while the second charged fragment is detected at a series of coplanar secondary angles. The largest coincidence charged particle yield for the multiparticle final state events results from 90 Zr(α,pp)X reactions, where both of the measured protons have energy distributions similar to the proton singles energy distributions. The second largest observed coincidence yield involving two charged fragments arises from 90 Zr(α,pd)X reactions, where the p and d fragments, as in the 90 Zr(α,pp)X reactions also have energy distribution similar to the singles energy distributions. Analysis of additional measurements, where alpha particle fragments at the fixed angle are detected in coincidence with evaporation and nonequilibrium particles at many coplanar angles, show that the alpha particle fragmentation reactions are also generally associated with large energy transfer to the target nucleus. A multiple scattering model of the fragmentation reaction is employed, in conjunction with the experimental observations, to estimate the cross sections for alpha particle fragmentation into multi-particle final states resulting in n, 2n, p, pp, d, dn, dp, t and 3 He fragments. The estimated total cross section for all fragmentation reactions is 755 mb or approximately 38% of the total reaction cross section for 140 MeV alpha particle interactions with 90 Zr

  2. Field tests and evaluations of the IAEA Active-Well Coincidence Counter

    International Nuclear Information System (INIS)

    Krick, M.S.; Rinard, P.M.

    1982-12-01

    This report summarizes and evaluates field tests of the Active Well Coincidence Counter (AWCC) at Winfrith and Dounreay, United Kingdom. The applicability of the AWCC for assaying the uranium content of a wide variety of materials was demonstrated and calibration curves were generated. The AWCC was used in three modes (fast, thermal, and passive) while assaying powders, pellets, cartridges, plates, assorted residues, and materials-testing-reactor fuel assemblies

  3. USING A PHENOMENOLOGICAL MODEL TO TEST THE COINCIDENCE PROBLEM OF DARK ENERGY

    International Nuclear Information System (INIS)

    Chen Yun; Zhu Zonghong; Alcaniz, J. S.; Gong Yungui

    2010-01-01

    By assuming a phenomenological form for the ratio of the dark energy and matter densities ρ X ∝ ρ m a ξ , we discuss the cosmic coincidence problem in light of current observational data. Here, ξ is a key parameter to denote the severity of the coincidence problem. In this scenario, ξ = 3 and ξ = 0 correspond to ΛCDM and the self-similar solution without the coincidence problem, respectively. Hence, any solution with a scaling parameter 0 X = 0, where ω X is the equation of state of the dark energy component, whereas the inequality ξ + 3ω X ≠ 0 represents non-standard cosmology. We place observational constraints on the parameters (Ω X,0 , ω X , ξ) of this model, where Ω X,0 is the present value of density parameter of dark energy Ω X , by using the Constitution Set (397 supernovae of type Ia data, hereafter SNeIa), the cosmic microwave background shift parameter from the five-year Wilkinson Microwave Anisotropy Probe and the Sloan Digital Sky Survey baryon acoustic peak. Combining the three samples, we get Ω X,0 = 0.72 ± 0.02, ω X = -0.98 ± 0.07, and ξ = 3.06 ± 0.35 at 68.3% confidence level. The result shows that the ΛCDM model still remains a good fit to the recent observational data, and the coincidence problem indeed exists and is quite severe, in the framework of this simple phenomenological model. We further constrain the model with the transition redshift (deceleration/acceleration). It shows that if the transition from deceleration to acceleration happens at the redshift z > 0.73, within the framework of this model, we can conclude that the interaction between dark energy and dark matter is necessary.

  4. A Monte Carlo Model for Neutron Coincidence Counting with Fast Organic Liquid Scintillation Detectors

    International Nuclear Information System (INIS)

    Gamage, Kelum A.A.; Joyce, Malcolm J.; Cave, Frank D.

    2013-06-01

    Neutron coincidence counting is an established, nondestructive method for the qualitative and quantitative analysis of nuclear materials. Several even-numbered nuclei of the actinide isotopes, and especially even-numbered plutonium isotopes, undergo spontaneous fission, resulting in the emission of neutrons which are correlated in time. The characteristics of this i.e. the multiplicity can be used to identify each isotope in question. Similarly, the corresponding characteristics of isotopes that are susceptible to stimulated fission are somewhat isotope-related, and also dependent on the energy of the incident neutron that stimulates the fission event, and this can hence be used to identify and quantify isotopes also. Most of the neutron coincidence counters currently used are based on 3 He gas tubes. In the 3 He-filled gas proportional-counter, the (n, p) reaction is largely responsible for the detection of slow neutrons and hence neutrons have to be slowed down to thermal energies. As a result, moderator and shielding materials are essential components of many systems designed to assess quantities of fissile materials. The use of a moderator, however, extends the die-away time of the detector necessitating a larger coincidence window and, further, 3 He is now in short supply and expensive. In this paper, a simulation based on the Monte Carlo method is described which has been performed using MCNPX 2.6.0, to model the geometry of a sector-shaped liquid scintillation detector in response to coincident neutron events. The detection of neutrons from a mixed-oxide (MOX) fuel pellet using an organic liquid scintillator has been simulated for different thicknesses of scintillators. In this new neutron detector, a layer of lead has been used to reduce the gamma-ray fluence reaching the scintillator. The effect of lead for neutron detection has also been estimated by considering different thicknesses of lead layers. (authors)

  5. 'TrueCoinc' software utility for calculation of the true coincidence correction

    International Nuclear Information System (INIS)

    Sudar, S.

    2002-01-01

    The true coincidence correction plays an important role in the overall accuracy of the γ ray spectrometry especially in the case of present-day high volume detectors. The calculation of true coincidence corrections needs detailed nuclear structure information. Recently these data are available in computerized form from the Nuclear Data Centers through the Internet or on a CD-ROM of the Table of Isotopes. The aim has been to develop software for this calculation, using available databases for the levels data. The user has to supply only the parameters of the detector to be used. The new computer program runs under the Windows 95/98 operating system. In the framework of the project a new formula was prepared for calculating the summing out correction and calculation of the intensity of alias lines (sum peaks). The file converter for reading the ENDSF-2 type files was completed. Reading and converting the original ENDSF was added to the program. A computer accessible database of the X rays energies and intensities was created. The X ray emissions were taken in account in the 'summing out' calculation. Calculation of the true coincidence 'summing in' correction was done. The output was arranged to show independently two types of corrections and to calculate the final correction as multiplication of the two. A minimal intensity threshold can be set to show the final list only for the strongest lines. The calculation takes into account all the transitions, independently of the threshold. The program calculates the intensity of X rays (K, L lines). The true coincidence corrections for X rays were calculated. The intensities of the alias γ lines were calculated. (author)

  6. Coincidence arrangements of local observables and uniqueness of the vacuum in QFT

    International Nuclear Information System (INIS)

    Dybalski, Wojciech

    2009-01-01

    A new phase space criterion, encoding the physically motivated behavior of coincidence arrangements of local observables, is proposed in this work. This condition entails, in particular, uniqueness and purity of the energetically accessible vacuum states. It is shown that the qualitative part of this new criterion is equivalent to a compactness condition proposed in the literature. Its novel quantitative part is verified in massive free field theory.

  7. Mass measurement of 80Y by β-γ coincidence spectroscopy

    International Nuclear Information System (INIS)

    Barton, C.J.; Caprio, M.A.; Beausang, C.W.; Casten, R.F.; Cooper, J.R.; Kruecken, R.; Novak, J.R.; Pietralla, N.; Brenner, D.S.; Zamfir, N.V.; Aprahamian, A.; Wiescher, M.C.; Shawcross, M.; Teymurazyan, A.; Berant, Z.; Wolf, A.; Gill, R.L.

    2003-01-01

    The Q EC value of 80 Y has been measured by β-γ coincidence spectroscopy to be ≥8929(83) keV. Combining this result with the adopted mass excess of the daughter 80 Sr gives a mass excess for 80 Y of ≥-61 376(83) keV. Results are compared with other measurements, with Audi-Wapstra systematics, and with predictions of mass formulas. Implications of this measurement are considered for the rp process

  8. Sizeable acquired subglottic cyst in a baby with Williams-Beuren syndrome: association or coincidence?

    Science.gov (United States)

    Christoforidis, Athanasios; Tsakalides, Christos; Chatziavramidis, Angelos; Karagianni, Paraskevi; Dimitriadou, Meropi; Konstantinidis, Iordanis

    2013-10-15

    We describe a case of an acquired subglottic cyst presented with persistent stridor and voice hoarsening in a baby diagnosed with Williams-Beuren syndrome that was born premature and required intubation during neonatal period. We also comment on whether this is a coincidence or there can be an association between impaired elastogenesis, a feature of patients with the syndrome and the formation of a subglottic cyst. © 2013 Elsevier B.V. All rights reserved.

  9. Orientation, alignment and polarisation in electron-helium collisions

    International Nuclear Information System (INIS)

    Beijers, J.P.M.

    1987-01-01

    In this thesis electron-photon coincidence experiments to study the excitation of helium by electron impact are updated. This is achieved by cross firing a well collimated and mono-energetic electron beam with a thermal helium beam and measuring the angular and/or polarisation distribution of the decay photons in coincidence with the inelastically scattered electrons. In this way target parameters are determined for the 2 1 P, 3 1 P, 3 1 D and 3 3 P states of helium. (Auth.)

  10. Monte Carlo simulation of β γ coincidence system using plastic scintillators in 4π geometry

    Science.gov (United States)

    Dias, M. S.; Piuvezam-Filho, H.; Baccarelli, A. M.; Takeda, M. N.; Koskinas, M. F.

    2007-09-01

    A modified version of a Monte Carlo code called Esquema, developed at the Nuclear Metrology Laboratory in IPEN, São Paulo, Brazil, has been applied for simulating a 4 πβ(PS)-γ coincidence system designed for primary radionuclide standardisation. This system consists of a plastic scintillator in 4 π geometry, for alpha or electron detection, coupled to a NaI(Tl) counter for gamma-ray detection. The response curves for monoenergetic electrons and photons have been calculated previously by Penelope code and applied as input data to code Esquema. The latter code simulates all the disintegration processes, from the precursor nucleus to the ground state of the daughter radionuclide. As a result, the curve between the observed disintegration rate as a function of the beta efficiency parameter can be simulated. A least-squares fit between the experimental activity values and the Monte Carlo calculation provided the actual radioactive source activity, without need of conventional extrapolation procedures. Application of this methodology to 60Co and 133Ba radioactive sources is presented and showed results in good agreement with a conventional proportional counter 4 πβ(PC)-γ coincidence system.

  11. Development of Coincidence Method for Determination Thermal Neutron Flux on RSG-GAS

    International Nuclear Information System (INIS)

    Bakhri, Syaiful; Hamzah, Amir

    2004-01-01

    The research to develop detection radiation system using coincidence method has been done to determine thermal neutron flux in RS1 and RS2 irradiation facilities RSG-GAS. At this research has arranged beta-gamma coincidence equipment system and parameter of measurement according to Au-198 beta-gamma spectrum. Gold foils that have irradiated for period of time, counted, and the activities of radiation is analyzed to get neutron flux. Result of research indicate that systems measurement of absolute activity with gamma beta coincidence method functioning well and can be applied at activity measurement of gold foil for irradiation facility characterization. The results show that thermal neutron flux in RS1 and RS2, respectively is 2.007E+12 n/cm 2 s and 2.147E+12 n/cm 2 s. To examine the system performance, the result was compared to measure activity using high resolution of Hp Ge detector and achieved discrepancy is about 1.26% and 6.70%. (author)

  12. Pile-up correction for coincidence counting using a CAEN 1724 digitizer

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro Junior, Iberê S.; Zahn, Guilherme S.; Genezini, Frederico A., E-mail: gzahn@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2017-07-01

    In conventional gamma-ray spectrometry, the probability of pile-up effects is considered to be proportional to the dead-time, and is usually neglected for low dead-times (below 4-5%). In gamma-gamma coincidence spectrometry, though, while the dead time takes into account only events that are actually digitized, the pile-up effects are proportional to the actual gamma-ray detection rate in each detector, not only to the ones that trigger the coincidence gate. Thus, the pile-up corrections may not be so easy to assess as in single spectrometry systems. In this work, a system composed of two HPGe detectors coupled to a CAEN v1724 digitizer is studied. A 3kBq {sup 60}Co source was analyzed, both alone and in the presence of other radioactive sources ({sup 137}Cs, {sup 133}Ba and {sup 152}Eu), and the resulting coincidence peak areas were compared to assess the effectiveness of two distinct corrections: a simple normalization by the live time of acquisition and the normalization by the count rate obtained using a pulse generator. The results obtained stress the need to use the pulse generator in this specific setup in order to get accurate results. (author)

  13. 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.

  14. Diversification of C(4) grasses (Poaceae) does not coincide with their ecological dominance.

    Science.gov (United States)

    Bouchenak-Khelladi, Yanis; Slingsby, Jasper A; Verboom, G Anthony; Bond, William J

    2014-02-01

    The radiation of a lineage and its rise to ecological dominance are distinct phenomena and driven by different processes. For example, paleoecological data has been used to show that the Cretaceous angiosperm radiation did not coincide with their rise to dominance. Using a phylogenetic approach, we here explored the evolution of C4 grasses and evaluated whether the diversification of this group and its rise to ecological dominance in the late Miocene were decoupled. We assembled a matrix including 675 grass species of the PACMAD clade and 2784 characters (ITS and ndhF) to run a molecular dating analysis using three fossils as reference calibrations. We coded species as C3 vs. C4 and reconstructed ancestral states under maximum likelihood. We used the program BiSSE to test whether rates of diversification are correlated with photosynthetic pathway and whether the radiation of C4 lineages preceded or coincided with their rise to ecological dominance from ∼10 Ma. C4 grass lineages first originated around 35 Ma at the time of the Eocene-Oligocene transition. Accelerated diversification of C4 lineages did not coincide with their rise to ecological dominance. C4-dominated grasslands have expanded only since the Late Miocene and Pliocene. The initial diversification of their biotic elements can be tracked back as far as the Eocene-Oligocene transition. We suggest that shifts in taxonomic diversification and ecological dominance were stimulated by different factors, as in the case of the early angiosperms in the Cretaceous.

  15. New approach to calculate the true-coincidence effect of HpGe detector

    Energy Technology Data Exchange (ETDEWEB)

    Alnour, I. A., E-mail: aaibrahim3@live.utm.my, E-mail: ibrahim.elnour@yahoo.com [Department of Physics, Faculty of Pure and Applied Science, International University of Africa, 12223 Khartoum (Sudan); Wagiran, H. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai,Johor (Malaysia); Ibrahim, N. [Faculty of Defence Science and Technology, National Defence University of Malaysia, Kem Sungai Besi, 57000 Kuala Lumpur (Malaysia); Hamzah, S.; Elias, M. S. [Malaysia Nuclear Agency (MNA), Bangi, 43000 Kajang, Selangor D.E. (Malaysia); Siong, W. B. [Chemistry Department, Faculty of Resource Science & Technology, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak (Malaysia)

    2016-01-22

    The corrections for true-coincidence effects in HpGe detector are important, especially at low source-to-detector distances. This work established an approach to calculate the true-coincidence effects experimentally for HpGe detectors of type Canberra GC3018 and Ortec GEM25-76-XLB-C, which are in operation at neutron activation analysis lab in Malaysian Nuclear Agency (NM). The correction for true-coincidence effects was performed close to detector at distances 2 and 5 cm using {sup 57}Co, {sup 60}Co, {sup 133}Ba and {sup 137}Cs as standard point sources. The correction factors were ranged between 0.93-1.10 at 2 cm and 0.97-1.00 at 5 cm for Canberra HpGe detector; whereas for Ortec HpGe detector ranged between 0.92-1.13 and 0.95-100 at 2 and 5 cm respectively. The change in efficiency calibration curve of the detector at 2 and 5 cm after correction was found to be less than 1%. Moreover, the polynomial parameters functions were simulated through a computer program, MATLAB in order to find an accurate fit to the experimental data points.

  16. Digital spectrometer for coincidence measurement of Doppler broadening of positron annihilation radiation

    International Nuclear Information System (INIS)

    Cizek, J.; Vlcek, M.; Prochazka, I.

    2010-01-01

    High-resolution digital coincidence Doppler broadening spectrometer equipped with two high-purity Ge detectors and two-channel 12-bit fast digitizer was developed and tested in this work. Two configurations were compared: (i) semi-digital setup which uses active analogue shaping of detector pulses prior to digitization to improve signal-to-noise ratio, and (ii) pure-digital setup which samples detector pulses directly. Software procedure developed for analysis of sampled waveforms, i.e. precise determination of energy of detected photon and rejection of distorted pulses, is described. Performance of digital coincidence spectrometer was compared with traditional analogue setup connected to the same detectors. It was found that digital spectrometer enables to achieve better energy resolution than in traditional analogue setup. Moreover, in digital configuration one has better control over shape of the signal. This allows efficient elimination of undesired distorted or damaged waveforms and to obtain spectrum of better clarity. The superior parameters of new digital coincidence Doppler broadening spectrometer are demonstrated by benchmark measurements of well defined Fe and Al specimens and also by the detection of rare annihilation in flight events.

  17. Hydrogen scrambling in ethane induced by intense laser fields: statistical analysis of coincidence events.

    Science.gov (United States)

    Kanya, Reika; Kudou, Tatsuya; Schirmel, Nora; Miura, Shun; Weitzel, Karl-Michael; Hoshina, Kennosuke; Yamanouchi, Kaoru

    2012-05-28

    Two-body Coulomb explosion processes of ethane (CH(3)CH(3)) and its isotopomers (CD(3)CD(3) and CH(3)CD(3)) induced by an intense laser field (800 nm, 1.0 × 10(14) W/cm(2)) with three different pulse durations (40 fs, 80 fs, and 120 fs) are investigated by a coincidence momentum imaging method. On the basis of statistical treatment of the coincidence data, the contributions from false coincidence events are estimated and the relative yields of the decomposition pathways are determined with sufficiently small uncertainties. The branching ratios of the two body decomposition pathways of CH(3)CD(3) from which triatomic hydrogen molecular ions (H(3)(+), H(2)D(+), HD(2)(+), D(3)(+)) are ejected show that protons and deuterons within CH(3)CD(3) are scrambled almost statistically prior to the ejection of a triatomic hydrogen molecular ion. The branching ratios were estimated by statistical Rice-Ramsperger-Kassel-Marcus calculations by assuming a transition state with a hindered-rotation of a diatomic hydrogen moiety. The hydrogen scrambling dynamics followed by the two body decomposition processes are discussed also by using the anisotropies in the ejection directions of the fragment ions and the kinetic energy distribution of the two body decomposition pathways.

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

    International Nuclear Information System (INIS)

    Freeman, Kathryn M.; Hoffmann, George R.

    2007-01-01

    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, 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

  19. Search for transient gravitational waves in coincidence with short-duration radio transients during 2007-2013

    NARCIS (Netherlands)

    Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Phythian-Adams, A.T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.T.; 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, R.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, M.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, A.L.S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, J.G.; Bogan, C.; Bohe, A.; Bojtos, P.; Bond, T.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, A.D.; Brown, 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.; Calderon Bustillo, J.; Callister, T. A.; 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.; Cavaglia, 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, D. 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, Qian; Chua, S. E.; Chung, E.S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P. -F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M., Jr.; Conte, A.; Conti, L.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, A.C.; 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, A.L.; Cuoco, E.; Dal Canton, T.; 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.; Deleglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.A.; Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Diaz, M. C.; Di Fiore, L.; Giovanni, M.G.; 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, T. M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.M.; 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.P.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; Gonzalez, Idelmis G.; Castro, J. M. Gonzalez; Gopakumar, A.; Gordon, N. A.; Gorodetsky, M. L.; Gossan, S. E.; Lee-Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.M.; 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.; Buffoni-Hall, R.; Hall, E. D.; Hammond, G.L.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, P.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, D.H.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jimenez-Forteza, F.; Johnson, W.; Jones, I.D.; Jones, R.; Jonker, R. J. G.; Ju, L.; Haris, K.; Kalaghatgi, C. V.; Kalogera, V.; Kandhasamy, S.; Kang, G.H.; Kanner, J. B.; Karki, S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kawazoe, F.; Kefelian, F.; Kehl, M. S.; Keitel, D.; Kelley, D. B.; Kells, W.; Kennedy, R.E.; 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.; Krolak, 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, K.H.; Lee, M.H.; 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.; Lueck, H.; Lundgren, A. P.; Luo, J.; Lynch, R.; Ma, Y.; MacDonald, T.T.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magana-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.; Marka, S.; Marka, 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, J.C.; Moraru, D.; Gutierrez Moreno, M.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, S.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.; Gutierrez-Neri, M.; Neunzert, A.; Newton-Howes, 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.; Oh, S. H.; Ohme, F.; Oliver, M. B.; 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.S; 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.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. G.; Puncken, O.; Punturo, M.; Puppo, P.; Purrer, 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.; Rosinska, D.; Rowan, S.; Ruediger, A.; Ruggi, P.; Ryan, K.A.; Sachdev, P.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.B.; Schofield, R. M. S.; Schoenbeck, A.; Schreiber, K.E.C.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, M.S.; Sellers, D.; Sentenac, D.; Sequino, V.; Sergeev, A.; Serna, G.; Setyawati, Y.; Sevigny, A.; Shaddock, D. A.; Shahriar, M. S.; Shaltev, M.; Shao, Z.M.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, António Dias da; Simakov, D.; Singer, A; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, R. J. E.; 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, C.D.; Stone, J.R.; Strain, K. A.; Straniero, N.; Stratta, G.; Strauss, N. A.; Strigin, S. E.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sutton, P. J.; Swinkels, B. L.; Szczepanczyk, M. J.; Tacca, M.D.; Talukder, D.; Tanner, D. B.; Tapai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, W.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.; Toyra, D.; Travasso, F.; Traylor, G.; Trifiro, 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, Martin; van den Brand, J. F. J.; Van Den Broeck, C.F.F.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Vass, S.; Vasuth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P.J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Vicere, 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, MT; 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.M.; Wessels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Williams, D.R.; 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.; Zadrozny, A.; 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-Lewis, F.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

  20. Electron Scattering From Atoms, Molecules, Nuclei, and Bulk Matter

    CERN Document Server

    Whelan, Colm T

    2005-01-01

    Topics that are covered include electron scattering in the scanning TEM; basic theory of inelastic electron imaging; study of confined atoms by electron excitation; helium bubbles created in extreme pressure with application to nuclear safety; lithium ion implantation; electron and positron scattering from clusters; electron scattering from physi- and chemi-absorbed molecules on surfaces; coincidence studies; electron scattering from biological molecules; electron spectroscopy as a tool for environmental science; electron scattering in the presence of intense fields; electron scattering from astrophysical molecules; electon interatctions an detection of x-ray radiation.

  1. A comprehensive & systematic study of coincidence time resolution and light yield using scintillators of different size, wrapping and doping

    CERN Document Server

    Auffray, E.; Geraci, F.; Ghezzi, A.; Gundacker, S.; Hillemanns, H.; Jarron, P.; Meyer, T.; Paganoni, M.; Pauwels, K.; Pizzichemi, M.; Lecoq, P.

    2011-01-01

    Over the last years interest in using time-of-flight-based Positron Emission Tomography (TOF-PET) systems has significantly increased. High time resolution in such PET systems is a powerful tool to improve signal to noise ratio and therefore to allow smaller exposure rates for patients as well as faster image reconstruction. Improvement in coincidence time resolution (CTR) in PET systems to the level of 200ps FWHM requires the optimization of all parameters in the photon detection chain influencing the time resolution: crystal, photodetector and readout electronics. After reviewing the factors influencing the time resolution of scintillators, we will present in this paper the light yield and CTR obtained for different scintillator types (LSO:Ce, LYSO:Ce, LGSO:Ce, LSO:Ce:0.4Ca, LuAG:Ce, LuAG:Pr) with different cross-sections, lengths and reflectors. Whereas light yield measurements were made with a classical PMT, all CTR tests were performed with Hamamatsu-MPPCs or SiPMs S10931-050P. The CTR measurements were ...

  2. Primary 4πβ-γ coincidence system for standardization of radionuclides by means of plastic scintillators

    International Nuclear Information System (INIS)

    Baccarelli, Aida Maria

    2003-01-01

    The present work describes a 4π(α,β)-γ coincidence system for absolute measurement of radionuclide activity using a plastic scintillator in 4π 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, β - , β + and electron capture have been standardized. The results showed excellent agreement with other conventional primary system which makes use of a 4π 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)

  3. Effect of inter-crystal scatter on estimation methods for random coincidences and subsequent correction

    International Nuclear Information System (INIS)

    Torres-Espallardo, I; Spanoudaki, V; Ziegler, S I; Rafecas, M; McElroy, D P

    2008-01-01

    Random coincidences can contribute substantially to the background in positron emission tomography (PET). Several estimation methods are being used for correcting them. The goal of this study was to investigate the validity of techniques for random coincidence estimation, with various low-energy thresholds (LETs). Simulated singles list-mode data of the MADPET-II small animal PET scanner were used as input. The simulations have been performed using the GATE simulation toolkit. Several sources with different geometries have been employed. We evaluated the number of random events using three methods: delayed window (DW), singles rate (SR) and time histogram fitting (TH). Since the GATE simulations allow random and true coincidences to be distinguished, a comparison between the number of random coincidences estimated using the standard methods and the number obtained using GATE was performed. An overestimation in the number of random events was observed using the DW and SR methods. This overestimation decreases for LETs higher than 255 keV. It is additionally reduced when the single events which have undergone a Compton interaction in crystals before being detected are removed from the data. These two observations lead us to infer that the overestimation is due to inter-crystal scatter. The effect of this mismatch in the reconstructed images is important for quantification because it leads to an underestimation of activity. This was shown using a hot-cold-background source with 3.7 MBq total activity in the background region and a 1.59 MBq total activity in the hot region. For both 200 keV and 400 keV LET, an overestimation of random coincidences for the DW and SR methods was observed, resulting in approximately 1.5% or more (at 200 keV LET: 1.7% for DW and 7% for SR) and less than 1% (at 400 keV LET: both methods) underestimation of activity within the background region. In almost all cases, images obtained by compensating for random events in the reconstruction

  4. Correlation of the Auger electrons direction of movement with the internal electron conversion direction of movement

    International Nuclear Information System (INIS)

    Mitrokhovich, N.F.; Kupryashkin, V.T.; Sidorenko, L.P.

    2013-01-01

    On installation of coincidences of γ-quanta with electrons and with law energy electrons about zero area the spatial correlation of the direction emitting Auger-electrons and electron of internal conversion was investigated at the 152 Eu decay. Auger-electrons were registered on e 0 -electrons of the secondary electron emission (γ e IC e 0 -coincidences). It was established, that Auger-electrons of M-series, as well as electrons 'shake-off' at β-decay and internal conversion, are strongly correlated at the direction of movement with the direction of movement of basic particle (β -particle, conversion electron), moving together mainly in the forward hemisphere. The intensity of correlated M-Auger radiation in range energy 1000 - 1700 eV is equal to intensity of correlated radiation 'shake-off' electron from internal conversion in this range. The assumption, that the presence of spatial correlating Auger-electron and conversion electron caused by cur-rent components of electron-electron interaction of particles in the final state is made

  5. Clinical value of 18F-FDG coincidence imaging for diagnosis of nasopharyngeal carcinoma

    International Nuclear Information System (INIS)

    Ning Yanli; Lou Cen; Huang Zhongke; Shi Guohua; Chen Dongfang; Mu Da

    2012-01-01

    Objective: To investigate the value of 18 F-FDG coincidence imaging for diagnosis of nasopharyngeal carcinoma. Methods: A total of 45 patients with nasopharyngeal carcinoma (33 males and 12 females, average age (55.56 ± 13.50) years), who underwent 18 F-FDG coincidence imaging before treatment, were studied retrospectively. The images of 18 F-FDG coincidence imaging (GE Millennium VG SPECT) and MRI were analyzed. The radioactivity ratio of the accumulated regions to cerebellum (T/NT)was calculated by ROI technique. The volume of nasopharyngeal carcinoma was recorded by MRI. The positive rates of 18 F-FDG coincidence imaging and EB virus-related antibody measurements were compared by paired χ 2 test. The correlation between T/NT ratios and tumor volumes were tested by Pearson correlation, and then ROC curves were established. The T/NT ratios and tumor volumes of different groups (different first symptoms, clinical stages, T stages, pathological classification and outcomes, with or without lymph node enlargement) were compared by t-test and rank sum test. Results: The positive rate of 18 F-FDG coincidence imaging was 97.78% (44/45), and the positive rate of EB virus-related antibody measurement was 95.56% (43/45, χ 2 =1.33, P>0.05). The T/NT ratio (2.439 ±1.119) and tumor volume ((7.311 ± 8.280) cm 3 ) of primary lesions had a positive correlation (r=0.463, P<0.05). The cut-off values of T/NT ratio and the tumor volume were 2.396 and 7.348 cm 3 , respectively, by ROC curves. T/NT ratios in groups with or without first symptom of epistaxis (2.847 ± 1.254 vs 2.082 ± 0.863, t=-2.409) and groups with or without facial numbness (2.855 ± 1.261 vs 2.134 ± 0.913, t=-2.225) were both significantly different (both P<0.05). T/NT ratios of differentiated and undifferentiated cancer were 2.266 ± 0.997 and 2.971 ± 1.351, respectively (t=-2.018, P<0.05). There was a significant difference of tumor volumes between groups with or without facial numbness (t=-2.684, P<0

  6. Estimating accidental coincidences for pixelated PET detectors and singles list-mode acquisition

    International Nuclear Information System (INIS)

    Rafecas, M.; Torres, I.; Spanoudaki, V.; McElroy, D.P.; Ziegler, S.I.

    2007-01-01

    We have studied the validity of random estimation techniques for various low energy thresholds (LETs) and single list-mode data sets in small animal PET. While a LET below 255 keV helps to increase the sensitivity, it also results in an increase of random coincidences and inter-crystal scatter (ICS). The study is carried out for MADPET-II, a dual-layer positron emission tomography (PET) scanner prototype consisting of LSO crystals read out individually by APDs. The data are acquired in singles list-mode format, and coincidences are computed post-acquisition. To estimate randoms, we have used the delayed coincidence window method (DW), and the singles rate model (SR). Various phantoms were simulated using GATE. For LETs under 255 keV, the number of random events R, estimated using the SR and the DW methods, is larger than the number of randoms which was directly computed from GATE simulations, and R(SR)>R(DW)>R(GATE). The higher the LET, the smaller the overestimation. For LETs >255 keV, R(DW)/R(GATE) ∼1. If scattered singles were excluded from the file, this discrepancy between R(DW or SR) and R(GATE) significantly diminished. This fact points out to ICS as the effect responsible for the mismatch, since for LETs lower than 255 keV, all singles related to an ICS event can be detected independently, thus altering the singles rate. Therefore, if low LETs are used, random estimation techniques should account for ICS

  7. Study on the Spatial Resolution of Single and Multiple Coincidences Compton Camera

    Science.gov (United States)

    Andreyev, Andriy; Sitek, Arkadiusz; Celler, Anna

    2012-10-01

    In this paper we study the image resolution that can be obtained from the Multiple Coincidences Compton Camera (MCCC). The principle of MCCC is based on a simultaneous acquisition of several gamma-rays emitted in cascade from a single nucleus. Contrary to a standard Compton camera, MCCC can theoretically provide the exact location of a radioactive source (based only on the identification of the intersection point of three cones created by a single decay), without complicated tomographic reconstruction. However, practical implementation of the MCCC approach encounters several problems, such as low detection sensitivities result in very low probability of coincident triple gamma-ray detection, which is necessary for the source localization. It is also important to evaluate how the detection uncertainties (finite energy and spatial resolution) influence identification of the intersection of three cones, thus the resulting image quality. In this study we investigate how the spatial resolution of the reconstructed images using the triple-cone reconstruction (TCR) approach compares to images reconstructed from the same data using standard iterative method based on single-cone. Results show, that FWHM for the point source reconstructed with TCR was 20-30% higher than the one obtained from the standard iterative reconstruction based on expectation maximization (EM) algorithm and conventional single-cone Compton imaging. Finite energy and spatial resolutions of the MCCC detectors lead to errors in conical surfaces definitions (“thick” conical surfaces) which only amplify in image reconstruction when intersection of three cones is being sought. Our investigations show that, in spite of being conceptually appealing, the identification of triple cone intersection constitutes yet another restriction of the multiple coincidence approach which limits the image resolution that can be obtained with MCCC and TCR algorithm.

  8. Chronic auditory hallucinations in schizophrenic patients: MR analysis of the coincidence between functional and morphologic abnormalities.

    Science.gov (United States)

    Martí-Bonmatí, Luis; Lull, Juan José; García-Martí, Gracián; Aguilar, Eduardo J; Moratal-Pérez, David; Poyatos, Cecilio; Robles, Montserrat; Sanjuán, Julio

    2007-08-01

    To prospectively evaluate if functional magnetic resonance (MR) imaging abnormalities associated with auditory emotional stimuli coexist with focal brain reductions in schizophrenic patients with chronic auditory hallucinations. Institutional review board approval was obtained and all participants gave written informed consent. Twenty-one right-handed male patients with schizophrenia and persistent hallucinations (started to hear hallucinations at a mean age of 23 years +/- 10, with 15 years +/- 8 of mean illness duration) and 10 healthy paired participants (same ethnic group [white], age, and education level [secondary school]) were studied. Functional echo-planar T2*-weighted (after both emotional and neutral auditory stimulation) and morphometric three-dimensional gradient-recalled echo T1-weighted MR images were analyzed using Statistical Parametric Mapping (SPM2) software. Brain activation images were extracted by subtracting those with emotional from nonemotional words. Anatomic differences were explored by optimized voxel-based morphometry. The functional and morphometric MR images were overlaid to depict voxels statistically reported by both techniques. A coincidence map was generated by multiplying the emotional subtracted functional MR and volume decrement morphometric maps. Statistical analysis used the general linear model, Student t tests, random effects analyses, and analysis of covariance with a correction for multiple comparisons following the false discovery rate method. Large coinciding brain clusters (P < .005) were found in the left and right middle temporal and superior temporal gyri. Smaller coinciding clusters were found in the left posterior and right anterior cingular gyri, left inferior frontal gyrus, and middle occipital gyrus. The middle and superior temporal and the cingular gyri are closely related to the abnormal neural network involved in the auditory emotional dysfunction seen in schizophrenic patients.

  9. Poster – 02: Positron Emission Tomography (PET) Imaging Reconstruction using higher order Scattered Photon Coincidences

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hongwei; Pistorius, Stephen [Department of Physics and Astronomy, University of Manitoba, CancerCare, Manitoba (Canada)

    2016-08-15

    PET images are affected by the presence of scattered photons. Incorrect scatter-correction may cause artifacts, particularly in 3D PET systems. Current scatter reconstruction methods do not distinguish between single and higher order scattered photons. A dual-scattered reconstruction method (GDS-MLEM) that is independent of the number of Compton scattering interactions and less sensitive to the need for high energy resolution detectors, is proposed. To avoid overcorrecting for scattered coincidences, the attenuation coefficient was calculated by integrating the differential Klein-Nishina cross-section over a restricted energy range, accounting only for scattered photons that were not detected. The optimum image can be selected by choosing an energy threshold which is the upper energy limit for the calculation of the cross-section and the lower limit for scattered photons in the reconstruction. Data was simulated using the GATE platform. 500,000 multiple scattered photon coincidences with perfect energy resolution were reconstructed using various methods. The GDS-MLEM algorithm had the highest confidence (98%) in locating the annihilation position and was capable of reconstructing the two largest hot regions. 100,000 photon coincidences, with a scatter fraction of 40%, were used to test the energy resolution dependence of different algorithms. With a 350–650 keV energy window and the restricted attenuation correction model, the GDS-MLEM algorithm was able to improve contrast recovery and reduce the noise by 7.56%–13.24% and 12.4%–24.03%, respectively. This approach is less sensitive to the energy resolution and shows promise if detector energy resolutions of 12% can be achieved.

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

    International Nuclear Information System (INIS)

    Schödel, R

    2015-01-01

    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)

  11. Coinciding exercise with peak serum caffeine does not improve cycling performance.

    Science.gov (United States)

    Skinner, Tina L; Jenkins, David G; Taaffe, Dennis R; Leveritt, Michael D; Coombes, Jeff S

    2013-01-01

    To investigate whether coinciding peak serum caffeine concentration with the onset of exercise enhances subsequent endurance performance. Randomised, double-blind, crossover. In this randomised, placebo-controlled, double-blind crossover study, 14 male trained cyclists and triathletes (age 31±5year, body mass 75.4±5.7 kg, VO₂max 69.5±6.1 mL kg⁻¹ min⁻¹ and peak power output 417±35W, mean±SD) consumed 6 mg kg(-1) caffeine or a placebo either 1h (C(1h)) prior to completing a 40 km time trial or when the start of exercise coincided with individual peak serum caffeine concentrations (C(peak)). C(peak) was determined from a separate 'caffeine profiling' session that involved monitoring caffeine concentrations in the blood every 30 min over a 4h period. Following caffeine ingestion, peak serum caffeine occurred 120 min in 12 participants and 150 min in 2 participants. Time to complete the 40 km time trial was significantly faster (2.0%; p=0.002) in C(1h) compared to placebo. No statistically significant improvement in performance was noted in the C(peak) trial versus placebo (1.1%; p=0.240). Whilst no differences in metabolic markers were found between C(peak) and placebo conditions, plasma concentrations of glucose (p=0.005), norepinephrine and epinephrine (p≤0.002) were higher in the C(1h) trial 6 min post-exercise versus placebo. In contrast to coinciding peak serum caffeine concentration with exercise onset, caffeine consumed 60 min prior to exercise resulted in significant improvements in 40 km time trial performance. The ergogenic effect of caffeine was not found to be related to peak caffeine concentration in the blood at the onset of endurance exercise. Copyright © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  12. An application of the coincidence Doppler spectroscopy for substances of chemical interest: phthalocyanine and acetylacetonate complexes

    International Nuclear Information System (INIS)

    Ito, Y.; Suzuki, T.

    2000-01-01

    Coincidence Doppler spectroscopy, which is particularly powerful when one is concerned with high momentum components of positron annihilation gamma-rays, has been applied to two different kinds of organo-metallic ligands: metal phthalocyanines and metal acetylacetonates. The energy (momentum) profiles of the annihilation gamma-rays were the same for metal phthalocyanines indicating that positron and/or positronium are not interacting with the metal ions. However, the profiles for the metal acetylacetonates evidently showed a dependence on the kind of metal ions. Discussion is made on the features of positron interaction which are different for phthalocyanines and acetylacetonates.

  13. Manual asymmetry in older adults on a complex coincidence-anticipation task.

    Science.gov (United States)

    Rodrigues, Paula Cristina Dos Santos; Silva, João Miguel Carvalho da; Barreiros, João Manuel Pardal; Vasconcelos, Maria Olga Fernandes

    2018-04-20

    Age-related asymmetrical functional decline was tested in a sample of 57 right-handed volunteers between 65 and 85 years of age. Participants performed a complex coincidence-anticipation (CA) task with both preferred and non-preferred hands. Results demonstrated that the proficiency of a complex CA task was similar for the 2 age groups, but different for the 2 hands. The non-preferred hand was more proficient for temporal accuracy but not for response timing, which was similar for both hands. Moreover, the lack of interaction between age and hand both in response timing and response accuracy reveal symmetric performance across ages.

  14. Calibration and performance testing of the IAEA Aquila Active Well Coincidence Counter (Unit 1)

    International Nuclear Information System (INIS)

    Menlove, H.O..; Siebelist, R.; Wenz, T.R.

    1996-01-01

    An Active Well Coincidence Counter (AWCC) and a portable shift register (PSR-B) produced by Aquila Technologies Group, Inc., have been tested and cross-calibrated with existing AWCCs used by the International Atomic Energy Agency (IAEA). This report summarizes the results of these tests and the cross-calibration of the detector. In addition, updated tables summarizing the cross-calibration of existing AWCCs and AmLi sources are also included. Using the Aquila PSR-B with existing IAEA software requires secondary software also supplied by Aquila to set up the PSR-B with the appropriate measurement parameters

  15. The high-level neutron coincidence counter (HLNCC) family of detectors

    International Nuclear Information System (INIS)

    Ramalho, A.; Dahn, E.; Selleck, E.; Kupryashkin, V.; Dubreuil, A.

    1983-01-01

    A description of a group of detectors based on The High-Level Neutron Coincidence Counter (HLNCC) concept is presented. Experience in their utilization is summarized and the procedures followed in calibration and data treatment are described. Advantages of the use of this variety of detectors in simplifying the NDA verifications, reducing the interference with facility operators, and increasing the effectiveness of the inspectors' work are stressed. Likewise, remaining problems such as the need for a vigorous programme directed at achieving the best independent calibrations are emphasized. (author)

  16. 65Zn and 133Ba standardizing by photon-photon coincidence counting

    Science.gov (United States)

    Loureiro, Jamir S.; da Cruz, Paulo A. L.; Iwahara, Akira; Delgado, José U.; Lopes, Ricardo T.

    2018-03-01

    The LNMRI/Brazil has deployed a system using X-gamma coincidence technique for the standardizing radionuclide, which present simple and complex decay scheme with X-rays of energy below 100 keV. The work was carried on radionuclide metrology laboratory using a sodium iodide detector, for gamma photons, in combination with a high purity germanium detector for X-rays. Samples of 65Zn and 133Ba were standardized and the results for both radionuclides showed good precision and accuracy when compared with reference values. The standardization differences were 0.72 % for 65Zn and 0.48 % for 133Ba samples.

  17. Uranium cross-calibration measurements using an active well coincidence counter

    International Nuclear Information System (INIS)

    Nikolaev, V.; Prochine, I.; Smirnov, V.; Ensslin, N.; Carillo, L.

    1998-01-01

    This paper reports on the cross-calibration of an Active Well Coincidence Counter for use in the Materials Protection, Control, and Accountability Graduate Program at the Moscow State Engineering Physics Institute (MEPhI). The cross-calibration procedure and its application to nuclear material types available at MEPhI for instructional purposes is described. Cross-calibration results at Los Alamos and initial applications at MEPhI are summarized. Based on the results so far, the authors conclude that the cross-calibration approach seems useful, with good prospects for potential applications at other Russian and US Dept. of Energy facilities

  18. Hypohidrotic ectodermal dysplasia and immunodeficiency with coincident NEMO and EDA Mutations

    Directory of Open Access Journals (Sweden)

    Michael D. Keller

    2011-11-01

    Full Text Available Ectodermal dysplasias (ED are uncommon genetic disorders resulting in abnormalities in ectodermally-derived structures. Though many ED-associated genes have been described, the NF-κB Essential Modulator (NEMO encoded by the IKBKG gene is unique in that mutations also result in severe humoral and cellular immunologic defects. We describe three unrelated kindreds with defects in both EDA and IKBKG resulting from an X-chromosome crossover. This demonstrates the importance of thorough immunologic consideration of patients with ED even when an EDA etiology is confirmed, and raises the possibility of a specific phenotype arising from coincident mutations in EDA and IKBKB.

  19. Hall effects on unsteady MHD flow between two rotating disks with non-coincident parallel axes

    Energy Technology Data Exchange (ETDEWEB)

    Barik, R.N., E-mail: barik.rabinarayan@rediffmail.com [Department of Mathematics, Trident Academy of Technology, Bhubaneswar (India); Dash, G.C., E-mail: gcdash@indiatimes.com [Department of Mathematics, S.O.A. University, Bhubaneswar (India); Rath, P.K., E-mail: pkrath_1967@yahoo.in [Department of Mathematics, B.R.M. International Institute of Technology, Bhubaneswar (India)

    2013-01-15

    Hall effects on the unsteady MHD rotating flow of a viscous incompressible electrically conducting fluid between two rotating disks with non-coincident parallel axes have been studied. There exists an axisymmetric solution to this problem. The governing equations are solved by applying Laplace transform method. It is found that the torque experienced by the disks decreases with an increase in either the Hall parameter, m or the rotation parameter, S{sup 2}. Further, the axis of rotation has no effect on the fluid flow. (author)

  20. Hall effects on unsteady MHD flow between two rotating disks with non-coincident parallel axes

    International Nuclear Information System (INIS)

    Barik, R.N.; Dash, G.C.; Rath, P.K.

    2013-01-01

    Hall effects on the unsteady MHD rotating flow of a viscous incompressible electrically conducting fluid between two rotating disks with non-coincident parallel axes have been studied. There exists an axisymmetric solution to this problem. The governing equations are solved by applying Laplace transform method. It is found that the torque experienced by the disks decreases with an increase in either the Hall parameter, m or the rotation parameter, S 2 . Further, the axis of rotation has no effect on the fluid flow. (author)

  1. Constructing coincident indices of economic activity for the Latin American economy

    Directory of Open Access Journals (Sweden)

    João Victor Issler

    2013-03-01

    Full Text Available This paper has three main contributions. The first is to propose an individual coincident indicator for the following Latin American countries: Argentina, Brazil, Chile, Colombia and Mexico. In order to obtain similar series to those traditionally used in business-cycle research in constructing coincident indices (output, sales, income and employment we were forced to back-cast several individual country series which were not available in a long time-series span. The second contribution is to establish a chronology of recessions for these countries, covering the period from 1980 to 2012 on a monthly basis. Based on this chronology, the countries are compared in several respects. The final contribution is to propose an aggregate coincident indicator for the Latin American economy, which weights individual-country composite indices. Finally, this indicator is compared with the coincident indicator (The Conference Board - TCB of the U.S. economy. We find that the U.S. indicator Granger-causes the Latin American indicator in statistical testsEsse artigo tem 3 contribuições à literatura de ciclos de negócios. A primeira é a de construir indicadores coincidentes de atividade econômica para Argentina, Brasil, Chile, Colômbia e México, usando pesos idênticos para as séries de Emprego, Produção, Renda, e Vendas. Para tal, tivemos que fazer o back-cast de algumas séries chave para poder construir esses indicadores. A segunda é a de estabelecer uma cronologia de recessões para esses países no período 1980-2012 em bases mensais. Com base na última, fazemos comparações em várias dimensões. Finalmente, nossa última contribuição é propor um índice coincidente agregado para a América Latina, que é comparado ao índice agregado dos EUA. Esta comparação indica que o índice coincidente dos EUA Granger-causa o da América Latina, mas a recíproca não é verdadeira

  2. Efficiency-optimized low-cost TDPAC spectrometer using a versatile routing/coincidence unit

    International Nuclear Information System (INIS)

    Renteria, M.; Bibiloni, A. G.; Darriba, G. N.; Errico, L. A.; Munoz, E. L.; Richard, D.; Runco, J.

    2008-01-01

    A highly efficient, reliable, and low-cost γ-γ TDPAC spectrometer, PACAr, optimized for 181 Hf-implanted low-activity samples, is presented. A versatile EPROM-based routing/coincidence unit was developed and implemented to be use with the memory-card-based multichannel analyzer hosted in a personal computer. The excellent energy resolution and very good overall resolution and efficiency of PACAr are analyzed and compare with advanced and already tested fast-fast and slow-fast PAC spectrometers.

  3. 65Zn and 133Ba standardizing by photon-photon coincidence counting

    International Nuclear Information System (INIS)

    Loureiro, Jamir S.; Cruz, Paulo A.L. da; Iwahara, Akira; Delgado, José U.; Lopes, Ricardo T.

    2017-01-01

    The LNMRI/Brazil has deployed a system using X-gamma coincidence technique for the standardizing radionuclide, which present simple and complex decay scheme with X-rays of energy below 100 keV. The work was carried on radionuclide metrology laboratory using a sodium iodide detector, for gamma photons, in combination with a high purity germanium detector for X-rays. Samples of 65 Zn and 133 Ba were standardized and the results for both radionuclides showed good precision and accuracy when compared with reference values. The standardization differences were 0.72 % for 65 Zn and 0.48 % for 133 Ba samples. (author)

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

    International Nuclear Information System (INIS)

    Tajmar, M

    2006-01-01

    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)

  5. Mid-infrared coincidence measurements on twin photons at room temperature

    DEFF Research Database (Denmark)

    Mancinelli, M.; Trenti, A.; Piccione, S.

    2017-01-01

    Quantum measurements using single-photon detectors are opening interesting new perspectives in diverse fields such as remote sensing, quantum cryptography and quantum computing. A particularly demanding class of applications relies on the simultaneous detection of correlated single photons...... pave the way to quantum measurements in the MIR by the demonstration of a room temperature coincidence measurement with non-degenerate twin photons at about 3.1 mu m. The experiment is based on the spectral translation of MIR radiation into the visible region, by means of efficient up-converter modules...

  6. Phantom dark energy with varying-mass dark matter particles: Acceleration and cosmic coincidence problem

    International Nuclear Information System (INIS)

    Leon, Genly; Saridakis, Emmanuel N.

    2010-01-01

    We investigate several varying-mass dark matter particle models in the framework of phantom cosmology. We examine whether there exist late-time cosmological solutions, corresponding to an accelerating universe and possessing dark energy and dark matter densities of the same order. Imposing exponential or power-law potentials and exponential or power-law mass dependence, we conclude that the coincidence problem cannot be solved or even alleviated. Thus, if dark energy is attributed to the phantom paradigm, varying-mass dark matter models cannot fulfill the basic requirement that led to their construction.

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

    International Nuclear Information System (INIS)

    Wells, S.A.; Evans, D.E.; Griffith, J.A.R.; Eastham, D.A.; Groves, J.; Smith, J.R.H.; Tolfree, D.W.L.; Warner, D.D.; Billowes, J.; Grant, I.S.; Walker, P.M.

    1988-01-01

    Fluorescent atom coincidence spectroscopy (FACS) has been used to measure the nuclear mean square radii and moments of the extremely neutron-deficient isotopes 120-124 Ba. 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 g 7/2 5/2[413] neutron and g 9/2 9/2[404] proton orbitals and the consequent enhancement of the n-p interaction. (orig.)

  8. {sup 65}Zn and {sup 133}Ba standardizing by photon-photon coincidence counting

    Energy Technology Data Exchange (ETDEWEB)

    Loureiro, Jamir S.; Cruz, Paulo A.L. da; Iwahara, Akira; Delgado, José U., E-mail: palcruz@ird.gov.br [Instituto de Radioproteção e Dosimetria (LNMRI/IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. Nacional de Metrologia das Radiações Ionizantes; Lopes, Ricardo T. [Coordenacao de Pos-Graduacao e Pesquisa de Engenharia (PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear

    2017-07-01

    The LNMRI/Brazil has deployed a system using X-gamma coincidence technique for the standardizing radionuclide, which present simple and complex decay scheme with X-rays of energy below 100 keV. The work was carried on radionuclide metrology laboratory using a sodium iodide detector, for gamma photons, in combination with a high purity germanium detector for X-rays. Samples of {sup 65}Zn and {sup 133}Ba were standardized and the results for both radionuclides showed good precision and accuracy when compared with reference values. The standardization differences were 0.72 % for {sup 65}Zn and 0.48 % for {sup 133}Ba samples. (author)

  9. Development of a coincidence circuit with nanosecond resolving time for NaI(Tl) scintillator pulses

    International Nuclear Information System (INIS)

    Ripon, R.; Coussot, G.

    1969-01-01

    The principle and the details of a slow-fast type coincidence circuit for pulses delivered by Nal(Tl) scintillators are presented. Thanks to a voluntary limitation of the analysis band (150 keV to 1 MeV) an excellent stability is obtained with respect to thermal drifts. The resolving time which has been adopted, 4 ns with 100 per cent efficiency, is quite sufficient for the projected experiment but does not represent the optimum performance of which the circuit is capable [fr

  10. Deconvolution of 2D coincident Doppler broadening spectroscopy using the Richardson-Lucy algorithm

    International Nuclear Information System (INIS)

    Zhang, J.D.; Zhou, T.J.; Cheung, C.K.; Beling, C.D.; Fung, S.; Ng, M.K.

    2006-01-01

    Coincident Doppler Broadening Spectroscopy (CDBS) measurements are popular in positron solid-state studies of materials. By utilizing the instrumental resolution function obtained from a gamma line close in energy to the 511 keV annihilation line, it is possible to significantly enhance the quality of the CDBS spectra using deconvolution algorithms. In this paper, we compare two algorithms, namely the Non-Negativity Least Squares (NNLS) regularized method and the Richardson-Lucy (RL) algorithm. The latter, which is based on the method of maximum likelihood, is found to give superior results to the regularized least-squares algorithm and with significantly less computer processing time

  11. Interesting coincidence of atypical TSH-secreting pituitary adenoma and chronic lymphocytic leukemia.

    Science.gov (United States)

    Bolanowski, Marek; Zieliński, Grzegorz; Jawiarczyk-Przybyłowska, Aleksandra; Maksymowicz, Maria; Potoczek, Stanisław; Syrycka, Joanna; Podgórski, Jan K

    2014-01-01

    Thyrotropin-secreting adenomas (TSH-oma) are very rare pituitary tumours. They are macroadenomas usually presenting with signs and symptoms of hyperthyroidism, and mass effects. They can co-secrete other hormones such as growth hormone or prolactin. Different malignancies, including haematological ones, are reported in patients with pituitary diseases. Chronic lymphocytic leukemia (CLL) occurs mostly in older patients, more often in males. CLL is associated with increased risk of second malignancies such as other blood neoplasms, skin and solid tumours. We present a successful neurosurgical outcome in a patient with an interesting coincidence of atypical TSH-oma and asymptomatic CLL.

  12. Study of the continuum in heavy ion inelastic spectra by light particle coincidence measurements

    International Nuclear Information System (INIS)

    Scarpaci, J.A.; Blumenfeld, Y.; Chomaz, P.; Frascaria, N.; Garron, J.P.; Roynette, J.C.; Suomijarvi, T.; Van der Woude, A.; Alamanos, N.; Fernandez, B.; Gillibert, A.; Van der Woude, A.; Lepine, A.

    1990-01-01

    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 40 Ca + 40 Ca collision at 50 MeV/N these contributions are separated and their relative importance assessed by the measurement of light charged particles in coincidence with the inelastically scattered fragments. The pick-up break-up contribution is found to make up less than half of the cross section at high excitation energies, conversely, the knock out process is important

  13. Method for improving the gamma-transition cascade spectra amplitude resolution during coincidence code computerized processing

    International Nuclear Information System (INIS)

    Sukhovoj, A.M.; Khitrov, V.A.

    1984-01-01

    A method of unfolding the differential γ-cascade spectra during radiation capture of slow neutrons based on the computeri-- zed processing of the results of measurements performed, by means of a spectrometer with two Ge(Li) detectors is suggested. The efficiency of the method is illustrated using as an example the spectrum of 35 Cl(n, γ) reaction corresponding to the 8580 keV peak. It is shown that the above approach permits to improve the resolution by 1.2-2.6 times without decrease in registration efficiency within the framework of the method of coincidence pulse amplitude summation

  14. Efficiency-optimized low-cost TDPAC spectrometer using a versatile routing/coincidence unit

    Energy Technology Data Exchange (ETDEWEB)

    Renteria, M., E-mail: renteria@fisica.unlp.edu.ar; Bibiloni, A. G.; Darriba, G. N.; Errico, L. A.; Munoz, E. L.; Richard, D.; Runco, J. [Universidad Nacional de La Plata, Departamento de Fisica, Facultad de Ciencias Exactas (Argentina)

    2008-01-15

    A highly efficient, reliable, and low-cost {gamma}-{gamma} TDPAC spectrometer, PACAr, optimized for {sup 181}Hf-implanted low-activity samples, is presented. A versatile EPROM-based routing/coincidence unit was developed and implemented to be use with the memory-card-based multichannel analyzer hosted in a personal computer. The excellent energy resolution and very good overall resolution and efficiency of PACAr are analyzed and compare with advanced and already tested fast-fast and slow-fast PAC spectrometers.

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

    International Nuclear Information System (INIS)

    Tobias, C.C.B.

    1982-01-01

    The absolute activity of U-235 contained in a UO 2 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) [pt

  16. Coincidence of calcified carotid atheromatous plaque, osteoporosis, and periodontal bone loss in dental panoramic radiographs

    Energy Technology Data Exchange (ETDEWEB)

    Ramesh, Aruna; Ganguly, Rumpa [Dept. of Diagnosis and Health Promotion, Division of Oral and Maxillofacial Radiology, Tufts University School of Dental Medicine, Boston (United States); Soroushian, Sheila [Dept. of Orthodontics, Howard University College of Dentistry, Washington, DC(United States)

    2013-12-15

    This study was performed to assess the correlation of calcified carotid atheromatous plaque (CCAP), the mandibular cortical index, and periodontal bone loss in panoramic radiographs. One hundred eighty-five panoramic radiographs with CCAP and 234 without this finding were evaluated by 3 observers for the presence of osseous changes related to osteoporosis and periodontal bone loss. Chi-squared and Mann-Whitney U tests were used to compare the two groups for an association of CCAP with the mandibular cortical index and periodontal bone loss, respectively. There was a statistically significant coincidence of CCAP and osseous changes related to osteopenia/osteoporosis, with a p-value <0.001. There was no statistically significant coincidence of CCAP and periodontal bone loss. When comparing the 2 groups, 'With CCAP' and 'Without CCAP', there was a statistically significant association with the mean body mass index (BMI), number of remaining teeth, positive history of diabetes mellitus, and vascular accidents. There was no statistically significant association with gender or a history of smoking. This study identified a possible concurrence of CCAP and mandibular cortical changes secondary to osteopenia/osteoporosis in panoramic radiographs. This could demonstrate the important role of dental professionals in screening for these systemic conditions, leading to timely and appropriate referrals resulting in early interventions and thus improving overall health.

  17. PET with a coincidence gamma camera: results in selected oncological questions

    International Nuclear Information System (INIS)

    Lauer, I.; Haase, A; Adam, S.; Prueter, I.; Richter, E.; Baehre, M.

    2001-01-01

    Since early 1997, about 1660 investigations with coincidence gamma camera PET (CGC-PET) have been performed in our department, mostly undertaken for oncological questions. Based on these data, several retrospective and prospective studies were performed. In the following, the results in CUP (cancer of unknown primary) syndrome, melanoma and malignant lymphoma are presented. Methods: CGC-PET was performed after application of 250-350 MBq [ 18 F]FDG using a coincidence double head gamma camera with 19 mm Nal cristal. CUP-Syndrome: After completing conventional diagnostic procedures, 32 patients have been examined in a prospective study, including 25 patients with recently detected CUP and 7 patients undergoing restaging after therapy. Localization of the primary tumor was successful in 12 (38%) cases. Melanoma: We evaluated 50 studies in 41 patients suffering from melanoma, retrospectively. CGC-PET showed a sensitivity of 76%, and a specificity of 94%. In comparison to conventional diagnostic methods, CGC-PET delineated important additional information in 16%. CGC-PET was superior to morphological diagnostic tools in the differentiation between residual scar tissue and active tumor following immunochemotherapy. Malignant lymphoma: 29 CGC-PET in 29 patients were performed for staging of malignant lymphoma, sensitivity was 86% versus 88% for CT. Overall CGC-PET showed additional information to conventional diagnostic methods, but revealed problems in detecting small infiltrations of organs. In restaging malignant melanoma (26 patients, 33 studies), specificity of CGC-PET was superior to conventional diagnostics (92% versus 35%). (orig.) [de

  18. F-18 FDG PET with coincidence detection, dual-head gamma camera, initial experience in oncology

    Energy Technology Data Exchange (ETDEWEB)

    Chu, J.M.G.; Pocock, N.; Quach, T.; Camden, B.M.C. [Liverpool Health Services, Liverpool, NSW (Australia). Department of Nuclear Medicine and Clinical Ultrasound

    1998-06-01

    Full text: The development of Co-incidence Detection (CD) in gamma camera technology has allowed the use of positron radiopharmaceuticals in clinical practice without dedicated PET facilities. We report our initial experience of this technology in Oncological applications. All patients were administered 200 MBq of F- 18 FDG intravenously in a fasting state, with serum glucose below 8.9 mmol/L., and hydration well maintained. Tomography was performed using an ADAC Solus Molecular Co-incidence Detection (MCD) dual-head gamma camera, 60 minutes after administration and immediately after voiding. Tomography of the torso required up to three collections depending on the length of the patient, with each collection requiring 32 steps of 40 second duration, and a 50% overlap. Tomography of the brain required a single collection with 32 steps of 80 seconds. Patients were scanned in the supine position. An iterative reconstruction algorithm was employed without attenuation correction. All patients had histologically confirmed malignancy. Scan findings were correlated with results of all conventional diagnostic imaging procedures that were pertinent to the evaluation and management of each individual patient`s disease. Correlation with tumour type and treatment status was also undertaken. F-18 FDG uptake as demonstrated by CD-PET was increased in tumour bearing sites. The degree of increased uptake varied with tumour type and with treatment status. Our initial experience with CD-PET has been very encouraging, and has led us to undertake prospective short and long term studies to define its role in oncology

  19. Aspects of the cosmological ''coincidence problem''

    Energy Technology Data Exchange (ETDEWEB)

    Velten, H.E.S.; Marttens, R.F. vom; Zimdahl, W. [Universidade Federal do Espirito Santo (UFES), Departamento de Fisica, Vitoria, Espirito Santo (Brazil)

    2014-11-15

    The observational fact that the present values of the densities of dark energy and dark matter are of the same order of magnitude, ρ{sub de0}/ρ{sub dm0} ∝ O(1), seems to indicate that we are currently living in a very special period of the cosmic history. Within the standard model, a density ratio of the order of one just at the present epoch can be seen as coincidental since it requires very special initial conditions in the early Universe. The corresponding ''why now'' question constitutes the cosmological ''coincidence problem''. According to the standard model the equality ρ{sub de} = ρ{sub dm} took place ''recently'' at a redshift z ∼ 0.55. The meaning of ''recently'' is, however, parameter dependent. In terms of the cosmic time the situation looks different. We discuss several aspects of the ''coincidence problem'', also in its relation to the cosmological constant problem, to issues of structure formation and to cosmic age considerations. (orig.)

  20. Coincidence of calcified carotid atheromatous plaque, osteoporosis, and periodontal bone loss in dental panoramic radiographs

    International Nuclear Information System (INIS)

    Ramesh, Aruna; Ganguly, Rumpa; Soroushian, Sheila

    2013-01-01

    This study was performed to assess the correlation of calcified carotid atheromatous plaque (CCAP), the mandibular cortical index, and periodontal bone loss in panoramic radiographs. One hundred eighty-five panoramic radiographs with CCAP and 234 without this finding were evaluated by 3 observers for the presence of osseous changes related to osteoporosis and periodontal bone loss. Chi-squared and Mann-Whitney U tests were used to compare the two groups for an association of CCAP with the mandibular cortical index and periodontal bone loss, respectively. There was a statistically significant coincidence of CCAP and osseous changes related to osteopenia/osteoporosis, with a p-value <0.001. There was no statistically significant coincidence of CCAP and periodontal bone loss. When comparing the 2 groups, 'With CCAP' and 'Without CCAP', there was a statistically significant association with the mean body mass index (BMI), number of remaining teeth, positive history of diabetes mellitus, and vascular accidents. There was no statistically significant association with gender or a history of smoking. This study identified a possible concurrence of CCAP and mandibular cortical changes secondary to osteopenia/osteoporosis in panoramic radiographs. This could demonstrate the important role of dental professionals in screening for these systemic conditions, leading to timely and appropriate referrals resulting in early interventions and thus improving overall health.

  1. Fast procedures for coincidence-summing correction in γ-ray spectrometry

    International Nuclear Information System (INIS)

    De Felice, Pierino; Angelini, Paola; Fazio, Aldo; Biagini, Roberto

    2000-01-01

    Simplified and fast procedures for coincidence-summing correction in γ-ray spectrometry were investigated. These procedures are based on the usual theoretical expressions of the correction factors, but differ in the determination of the total efficiency curve based on the following approximations: (a) replacement, below the knee efficiency value, of the total efficiency by the full-energy peak efficiency; and (b) use of linear interpolations (in log-log plot) between only two experimental points above the knee efficiency value; or (c) assumption of a peak-to-total efficiency ratio independent on the counting geometry; or (d) assumption of a constant relation between the peak-to-total efficiency ratios and the photoelectric-to-total cross section ratios. The above approximations were separately assumed for determination of the coincidence-summing correction factors for nuclides with complex decay scheme ( 133 Ba, 134 Cs, 152 Eu) and for 60 Co and 88 Y measured on a 15% relative efficiency p-type coaxial HPGe detector, for three source-detector geometries: point source placed on top of and at 10 cm from the detector window, and 1 l Marinelli beaker filled with aqueous solution. The results were compared with those based on more accurate experimental determinations of the total efficiency curve from measurements of standard sources of eight different single-γ-ray emitters. The usefulness of each simplified procedure is evaluated with respect to its accuracy and to the reduction of the number of standard sources and measurement time

  2. Design of a coincidence processing board for a dual-head PET scanner for breast imaging

    International Nuclear Information System (INIS)

    Martinez, J.D.; Toledo, J.; Esteve, R.; Sebastia, A.; Mora, F.J.; Benlloch, J.M.; Fernandez, M.M.; Gimenez, M.; Gimenez, E.N.; Lerche, Ch.W.; Pavon, N.; Sanchez, F.

    2005-01-01

    This paper describes the design of a coincidence processing board for a dual-head Positron Emission Tomography (PET) scanner for breast imaging. The proposed block-oriented data acquisition system relies on a high-speed DSP processor for fully digital trigger and on-line event processing that surpasses the performance of traditional analog coincidence detection systems. A mixed-signal board has been designed and manufactured. The analog section comprises 12 coaxial inputs (six per head) which are digitized by means of two 8-channel 12-bit 40-MHz ADCs in order to acquire the scintillation pulse, the charge division signals and the depth of interaction within the scintillator. At the digital section, a state-of-the-art FPGA is used as deserializer and also implements the DMA interface to the DSP processor by storing each digitized channel into a fast embedded FIFO memory. The system incorporates a high-speed USB 2.0 interface to the host computer

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

    Energy Technology Data Exchange (ETDEWEB)

    Trivelpiece, Cory L., E-mail: cory@psu.ed [Department of Mechanical and Nuclear Engineering, The Pennsylvania, State University, University Park, PA 16802 (United States); Brenizer, J.S. [Department of Mechanical and Nuclear Engineering, The Pennsylvania, State University, University Park, PA 16802 (United States)

    2011-01-01

    A diameter of uncertainty (D{sub u}) 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 {alpha} and Li ions, produced by the {sup 10}B(n,{alpha}) {sup 7}Li 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 D{sub u} for position-sensitive, coincidence techniques. The results of these calculations showed that D{sub u} is dependent on encoder separation, the angle of charged particle emission, and film thickness. For certain emission scenarios, the magnitude of D{sub u} 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 D{sub u} can be discriminated by logical arguments during spectral deconvolution.

  4. Investigating the γ decay of 65Ni from particle-γ coincidence data

    Science.gov (United States)

    Campo, L. Crespo; Larsen, A. C.; Garrote, F. L. Bello; Eriksen, T. K.; Giacoppo, F.; Görgen, A.; Guttormsen, M.; Klintefjord, M.; Renstrøm, T.; Sahin, E.; Siem, S.; Tornyi, T. G.; Tveten, G. M.

    2017-07-01

    The γ decay of 65Ni has been studied from particle-γ coincidence data on the 64Ni(d ,p γ )65Ni reaction. γ -ray spectra at excitation energies below Ex≈2 MeV have been studied and compared with previous measurements. Coincidences corresponding to Ex≈4.4 -6.1 MeV have been used to constrain the shape of the nuclear level density and γ -strength function of 65Ni by means of the Oslo method. The experimental γ -strength function presents an enhancement at γ energies below Eγ≈3 MeV . In addition, a resonance-like structure centered at Eγ≈4.6 MeV is seen together with accumulated strength at Eγ≈2.6 -3.6 MeV . The obtained results contribute to the systematic study of γ decay in the Ni isotopes, which is of great interest for the understanding of both single-particle and collective nuclear structure phenomena.

  5. The manifestation of 18F-FDG imaging of coincidence SPECT in benign pulmonary diseases

    International Nuclear Information System (INIS)

    Miao Jisheng; Liu Jinjun; Wu Jiyong; Pan Huizhong; Wang Huoqiang; Shen Yi; Shi Degang

    2001-01-01

    Objective: To study the uptake of the 18 F-FDG in the benign pulmonary diseases with dual head SPECT coincidence detection system. Methods: Scanning were performed with dual head SPECT coincidence detection system for patients with pulmonary diseases,the uptake and the imaging characteristic of the diseases were analysed. Results: 1) In 28 tuberculosis (TB) patients, 19 cases with a negative imaging (68%, 19/28), whereas 9 cases with a positive result (32%, 9/28). The T/N value of the TB is 1.7 +- 1.2, but the T/N of the lung cancer is 4.1 +- 2.4, significantly different from them. In the skin PPD test, 9 cases with positive scans showed a 16.2 (12 - 22) mm diameter red spot, but 7 cases of negative scans with a 8.6 (0 - 15) mm diameter, both also have a significant difference. 2) Out of the 8 patients suffered from sarcoidosis, among them 5 active stage with positive scans, whereas another 3 remission cases with negative results. 3) In 18 inflammation cases, positive imagings were showed in 6 patients with cryptococcosis, mycoplasma pneumonia, mycosis, organized pneumonia, lung abscess and bacteria pneumonia. Conclusions: In some benign pulmonary diseases, 18 F-FDG imaging can be positive also. Analysing the characteristic of the imaging could rise specificity in lung cancer and also give some new clues to treatment of these benign pulmonary diseases

  6. Dendritic calcium channels and their activation by synaptic signals in auditory coincidence detector neurons.

    Science.gov (United States)

    Blackmer, Trillium; Kuo, Sidney P; Bender, Kevin J; Apostolides, Pierre F; Trussell, Laurence O

    2009-08-01

    The avian nucleus laminaris (NL) encodes the azimuthal location of low-frequency sound sources by detecting the coincidence of binaural signals. Accurate coincidence detection requires precise developmental regulation of the lengths of the fine, bitufted dendrites that characterize neurons in NL. Such regulation has been suggested to be driven by local, synaptically mediated, dendritic signals such as Ca(2+). We examined Ca(2+) signaling through patch clamp and ion imaging experiments in slices containing nucleus laminaris from embryonic chicks. Voltage-clamp recordings of neurons located in the NL showed the presence of large Ca(2+) currents of two types, a low voltage-activated, fast inactivating Ni(2+) sensitive channel resembling mammalian T-type channels, and a high voltage-activated, slowly inactivating Cd(2+) sensitive channel. Two-photon Ca(2+) imaging showed that both channel types were concentrated on dendrites, even at their distal tips. Single action potentials triggered synaptically or by somatic current injection immediately elevated Ca(2+) throughout the entire cell. Ca(2+) signals triggered by subthreshold synaptic activity were highly localized. Thus when electrical activity is suprathreshold, Ca(2+) channels ensure that Ca(2+) rises in all dendrites, even those that are synaptically inactive.

  7. Development of Simultaneous Beta-and-Coincidence-Gamma Imager for Plant Imaging Research

    Energy Technology Data Exchange (ETDEWEB)

    Tai, Yuan-Chuan [Washington Univ., St. Louis, MO (United States). School of Medicine

    2016-09-30

    The goal of this project is to develop a novel imaging system that can simultaneously acquire beta and coincidence gamma images of positron sources in thin objects such as leaves of plants. This hybrid imager can be used to measure carbon assimilation in plants quantitatively and in real-time after C-11 labeled carbon-dioxide is administered. A better understanding of carbon assimilation, particularly under the increasingly elevated atmospheric CO2 level, is extremely critical for plant scientists who study food crop and biofuel production. Phase 1 of this project is focused on the technology development with 3 specific aims: (1) develop a hybrid detector that can detect beta and gamma rays simultaneously; (2) develop an imaging system that can differentiate these two types of radiation and acquire beta and coincidence gamma images in real-time; (3) develop techniques to quantify radiotracer distribution using beta and gamma images. Phase 2 of this project is to apply technologies developed in phase 1 to study plants using positron-emitting radionuclide such as 11C to study carbon assimilation in biofuel plants.

  8. Coincidences in analysis: Sigmund Freud and the strange case of Dr Forsyth and Herr von Vorsicht.

    Science.gov (United States)

    Pierri, Maria

    2010-08-01

    Freud's interest in thought transference opens the possibility for psychoanalytic research on the primary preverbal language and the maternal function, which the emphasis on verbal and paternal communication had hidden in the background of the setting. The author advances a new interpretation of coincidences in analysis and of the psychopathology of everyday life of the setting. Starting from a strange coincidence, new hypotheses are submitted following additional readings of the unpublished manuscript of the 'Forsyth case', recovered by the author, in regard to a significant moment of transformation, both in Freud and in psychoanalysis, at the end of the war. This phase corresponds first to a change of language, from German to English, as well as to the foundation of the International Journal of Psychoanalysis by Ernest Jones. In particular, the roots of the metapsychological turn of the 1920s are explored, together with the opening of private and productive thoughts in the area of 'telepathy' that joined Freud, Ferenczi, and Anna Freud in a true 'dialogue of unconsciouses'. The free association between A Child Is Being Beaten, Beyond the Pleasure Principle, and the clinical experience with 'Herr B.' is outlined in order to understand Freud's heroic self-analysis at the time when he was treating his daughter Anna and grieving the death of his beloved Sophie. Copyright © 2010 Institute of Psychoanalysis.

  9. Comparison of the Savannah River Site billet active well coincidence counter and two Californium Shufflers

    International Nuclear Information System (INIS)

    Sadowski, E.T.; Griffin, J.C.; Rinard, P.M.

    1991-01-01

    A Scrap Californium Shuffler at the Savannah River Site (SRS) was calibrated to assay the U-Al cores of billets (an intermediate step in the SRS reactor fuel fabrication cycle.) The precision of the Scrap Shuffler over several years has been approximately 0.50%. A typical total uncertainty for the assay of a core on the Scrap Shuffler is approximately 0.33% for a twelve minute assay. The precision over several months and a typical total uncertainty for the Billet Active Well (neutron) Coincidence Counter (BAWCC) are approximately 1.0% and 1.9%, respectively, for a fifteen minute assay. A new Billet Californium Shuffler specifically designed for assaying SRS billets has yielded precision (over one month) and total uncertainty results of 0.40% and 0.69%, respectively, for an eight minute assay. The introduction of a measurement point into the fuel fabrication cycle to replace estimates based upon material weight will greatly enhance material and process control in the Reactor Materials area of SRS. The use of all three instruments provides a comparison of the relative merits of Active Well (neutron) Coincidence Counters (AWCCs) and shufflers for assay of homogeneous and geometrically simple material containing 235 U. The measurement precisions, systematic and random uncertainties, as well as the procurement and operation of each instrument will be compared. 3 refs., 5 figs., 1 tab

  10. Exploring short-GRB afterglow parameter space for observations in coincidence with gravitational waves

    Science.gov (United States)

    Saleem, M.; Resmi, L.; Misra, Kuntal; Pai, Archana; Arun, K. G.

    2018-03-01

    Short duration Gamma Ray Bursts (SGRB) and their afterglows are among the most promising electromagnetic (EM) counterparts of Neutron Star (NS) mergers. The afterglow emission is broad-band, visible across the entire electromagnetic window from γ-ray to radio frequencies. The flux evolution in these frequencies is sensitive to the multidimensional afterglow physical parameter space. Observations of gravitational wave (GW) from BNS mergers in spatial and temporal coincidence with SGRB and associated afterglows can provide valuable constraints on afterglow physics. We run simulations of GW-detected BNS events and assuming that all of them are associated with a GRB jet which also produces an afterglow, investigate how detections or non-detections in X-ray, optical and radio frequencies can be influenced by the parameter space. We narrow down the regions of afterglow parameter space for a uniform top-hat jet model, which would result in different detection scenarios. We list inferences which can be drawn on the physics of GRB afterglows from multimessenger astronomy with coincident GW-EM observations.

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

    International Nuclear Information System (INIS)

    Urcelay Silva, A.J.

    1975-01-01

    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)

  12. Correlation-Based Amplitude Estimation of Coincident Partials in Monaural Musical Signals

    Directory of Open Access Journals (Sweden)

    Jayme Garcia Arnal Barbedo

    2010-01-01

    Full Text Available This paper presents a method for estimating the amplitude of coincident partials generated by harmonic musical sources (instruments and vocals. It was developed as an alternative to the commonly used interpolation approach, which has several limitations in terms of performance and applicability. The strategy is based on the following observations: (a the parameters of partials vary with time; (b such a variation tends to be correlated when the partials belong to the same source; (c the presence of an interfering coincident partial reduces the correlation; and (d such a reduction is proportional to the relative amplitude of the interfering partial. Besides the improved accuracy, the proposed technique has other advantages over its predecessors: it works properly even if the sources have the same fundamental frequency, it is able to estimate the first partial (fundamental, which is not possible using the conventional interpolation method, it can estimate the amplitude of a given partial even if its neighbors suffer intense interference from other sources, it works properly under noisy conditions, and it is immune to intraframe permutation errors. Experimental results show that the strategy clearly outperforms the interpolation approach.

  13. Hypernuclear weak decay experiments at KEK: n-n and n-p coincidence measurement

    International Nuclear Information System (INIS)

    Outa, H.; Ajimura, S.; Aoki, K.; Banu, A.; Bhang, H.C.; Fukuda, T.; Hashimoto, O.; Hwang, J.I.; Kameoka, S.; Kang, B.H.; Kim, E.H.; Kim, J.H.; Kim, M.J.; Maruta, T.; Miura, Y.; Miyake, Y.; Nagae, T.; Nakamura, M.; Nakamura, S.N.; Noumi, H.; Okada, S.; Okayasu, Y.; Park, H.; Saha, P.K.; Sato, Y.; Sekimoto, M.; Takahashi, T.; Tamura, H.; Tanida, K.; Toyoda, A.; Tsukada, K.; Watanabe, T.; Yim, H.J.

    2005-01-01

    We performed a coincidence measurement of two nucleons emitted from the nonmesonic weak decay (NMWD) of 5 Λ He and 12 Λ C formed via the (π+,K+) reaction. In both of n+p and n+n pair coincidence spectra, we observed a clean back-to-back correlation coming from the two-body decay of Λp->np and Λn->nn, respectively. We obtained the ratio of the nucleon pair numbers, Nnn/Nnp ( 5 Λ He)=0.45-bar +/--bar 0.11-bar (stat)-bar +/--bar 0.03-bar (syst) in the kinematic region of cosθNN-0.8. Since each decay mode was exclusively detected, the measured ratio should be close to the ratio of Γ(Λp->nn)/Γ(Λn->np). The Γn/Γp ratio was measured also for the NMWD of 12 Λ C. It is also close to 0.5. Those ratios are consistent with recent theoretical calculations based on the heavy meson/direct quark exchange picture

  14. Quark seesaw mechanism, dark U (1 ) symmetry, and the baryon-dark matter coincidence

    Science.gov (United States)

    Gu, Pei-Hong; Mohapatra, Rabindra N.

    2017-09-01

    We attempt to understand the baryon-dark matter coincidence problem within the quark seesaw extension of the standard model where parity invariance is used to solve the strong C P problem. The S U (2 )L×S U (2 )R×U (1 )B -L gauge symmetry of this model is extended by a dark U (1 )X group plus inclusion of a heavy neutral vector-like fermion χL ,R charged under the dark group which plays the role of dark matter. All fermions are Dirac type in this model. Decay of heavy scalars charged under U (1 )X leads to simultaneous asymmetry generation of the dark matter and baryons after sphaleron effects are included. The U (1 )X group not only helps to stabilize the dark matter but also helps in the elimination of the symmetric part of the dark matter via χ -χ ¯ annihilation. For dark matter mass near the proton mass, it explains why the baryon and dark matter abundances are of similar magnitude (the baryon-dark matter coincidence problem). This model is testable in low threshold (sub-keV) direct dark matter search experiments.

  15. Performance of coincidence-based PSD on LiF/ZnS Detectors for Multiplicity Counting

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Sean M.; Stave, Sean C.; Lintereur, Azaree; Siciliano, Edward R.; Cowles, Christian C.; Kouzes, Richard T.; Behling, Richard S.

    2016-10-06

    Abstract: Mass accountancy measurement is a nuclear nonproliferation application which utilizes coincidence and multiplicity counters to verify special nuclear material declarations. With a well-designed and efficient detector system, several relevant parameters of the material can be verified simultaneously. 6LiF/ZnS scintillating sheets may be used for this purpose due to a combination of high efficiency and short die-away times in systems designed with this material, but involve choices of detector geometry and exact material composition (e.g., the addition of Ni-quenching in the material) that must be optimized for the application. Multiplicity counting for verification of declared nuclear fuel mass involves neutron detection in conditions where several neutrons arrive in a short time window, with confounding gamma rays. This paper considers coincidence-based Pulse-Shape Discrimination (PSD) techniques developed to work under conditions of high pileup, and the performance of these algorithms with different detection materials. Simulated and real data from modern LiF/ZnS scintillator systems are evaluated with these techniques and the relationship between the performance under pileup and material characteristics (e.g., neutron peak width and total light collection efficiency) are determined, to allow for an optimal choice of detector and material.

  16. Multiple electron capture in close ion-atom collisions

    International Nuclear Information System (INIS)

    Schlachter, A.S.

    1987-10-01

    Multiple electron capture is reported for Ca 17+ in Ar. Close collisions are defined by the observation of a coincident Ca K or Ar K x-ray. A large number of electrons is transferred to the projectile in a single close collision when the Ca ion projectile is of the order of the Ar L-shell electron velocity. The cross section for electron capture is reported

  17. The synthesis method for design of electron flow sources

    Science.gov (United States)

    Alexahin, Yu I.; Molodozhenzev, A. Yu

    1997-01-01

    The synthesis method to design a relativistic magnetically - focused beam source is described in this paper. It allows to find a shape of electrodes necessary to produce laminar space charge flows. Electron guns with shielded cathodes designed with this method were analyzed using the EGUN code. The obtained results have shown the coincidence of the synthesis and analysis calculations [1]. This method of electron gun calculation may be applied for immersed electron flows - of interest for the EBIS electron gun design.

  18. The effect of Coster-Kronig transition on the Auger-photoelectron coincidence spectroscopy spectra of early 3d-transition metals

    International Nuclear Information System (INIS)

    Ohno, Masahide

    2004-01-01

    The singles L23-M45M45 Auger-electron spectroscopy (AES) spectrum of early 3d-transition metal can be fitted by a weighted sum of the density of the single-hole states and that of the two-hole states, broadened by the initial L23-hole lifetime width, respectively (in the present paper we denote the atomic shells Lx, My, and Nz by LX, MY and NZ, respectively). With increasing occupancy of the 3d band the probability of creating the two-hole states by the L23-M45M45 Auger transition and the L2-L3M45 Coster-Kronig (CK) transition increases. However, the M45 hole created by the CK transition is delocalized and becomes decoupled (screened out) from the L3-hole decay so that the L3M45 two-hole state 'decays' to the single L3-hole state before the L3-hole decays. Thus the singles AES spectrum by the L2-L3-M45(M45) CK-transition preceded Auger transition and the singles one by the L3-M45(M45) Auger-transition overlap. We can study the M45-hole dynamics by Auger-photoelectron coincidence spectroscopy because the coincidence spectral lineshape depends on the dynamics of the M45 hole created by the CK transition

  19. Detector characterization and first coincidence tests of a Compton telescope based on LaBr3 crystals and SiPMs

    International Nuclear Information System (INIS)

    Llosá, G.; Barrio, J.; Cabello, J.; Crespo, A.; Lacasta, C.; Rafecas, M.; Callier, S.; La Taille, C. de; Raux, L.

    2012-01-01

    A Compton telescope for dose monitoring in hadron therapy consisting of several layers of continuous LaBr 3 crystals coupled to silicon photomultiplier (SiPM) arrays is under development within the ENVISION project. In order to test the possibility of employing such detectors for the telescope, a detector head consisting of a continuous 16 mm×18 mm×5 mm LaBr 3 crystal coupled to a SiPM array has been assembled and characterized, employing the SPIROC1 ASIC as readout electronics. The best energy resolution obtained at 511 keV is 6.5% FWHM and the timing resolution is 3.1 ns FWHM. A position determination method for continuous crystals is being tested, with promising results. In addition, the detector has been operated in time coincidence with a second detector layer, to determine the coincidence capabilities of the system. The first tests are satisfactory, and encourage the development of larger detectors that will compose the telescope prototype.

  20. Interacting dark energy models as an approach for solving Cosmic Coincidence Problem

    Science.gov (United States)

    Shojaei, Hamed

    Understanding the dark side of the Universe is one of the main tasks of physicists. As there is no thorough understanding of nature of the dark energy, this area is full of new ideas and there may be several discoveries, theoretical or experimental, in the near future. We know that dark energy, though not detected directly, exists and it is not just an exotic idea. The presence of dark energy is required by the observation of the acceleration of the universe. There are several questions regarding dark energy. What is the nature of dark energy? How does it interact with matter, baryonic or dark? Why is the density of dark energy so tiny, i.e. why rhoΛ ≈ 10--120 M4Pl ? And finally why does its density have the same order of magnitude as the density of matter does at the present time? The last question is one form of what is known as the "Cosmic Coincidence Problem" and in this work, I have been investigating one way to resolve this issue. Observations of Type Ia supernovae indicate that we are in an accelerating universe. A matter-dominated universe cannot be accelerating. A good fit is obtained if we assume that energy density parameters are O Λ = 0.7 and Om = 0.3. Here O Λ is related to dark energy, or cosmological constant in ΛCDM model. At the same time data from Wilkinson Microwave Anisotropy Probe (WMAP) satellite and supernova surveys have placed a constraint on w, the equation of state for dark energy, which is actually the ratio of pressure and energy density. Any good theory needs to explain this coincidence problem and yields a value for w between -1.1 and -0.9. I have employed an interesting approach to solve this problem by assuming that there exists an interaction between dark energy and matter in the context of holographic dark energy. This interaction converts dark energy to matter or vice versa without violating the local conservation of energy in the universe. Holographic dark energy by itself indicates that the value of dark energy is related

  1. Measuring 226Ra and 232Th activity in soil and vegetation samples using a method of double γ-coincidences

    International Nuclear Information System (INIS)

    Antovic, N.M.; Antovic, I.

    2010-01-01

    A coincidence method for measuring radium and thorium activity has been developed using the PRIPYAT-2M gamma-ray coincidence spectrometer, with six NaI(Tl) detectors and registration geometry close to 4π. It was tested by measuring soil samples from the Northern region of Montenegro, as well as vegetation samples from the same region. The results showed a good agreement with ones obtained by the HPGe spectrometer. (author)

  2. Standardization of iodine-129 by the TDCR liquid scintillation method and 4π β-γ coincidence counting

    Science.gov (United States)

    Cassette, P.; Bouchard, J.; Chauvenet, B.

    1994-01-01

    Iodine-129 is a long-lived fission product, with physical and chemical properties that make it a good candidate for evaluating the environmental impact of the nuclear energy fuel cycle. To avoid solid source preparation problems, liquid scintillation has been used to standardize this nuclide for a EUROMET intercomparison. Two methods were used to measure the iodine-129 activity: triple-to-double-coincidence ratio liquid scintillation counting and 4π β-γ coincidence counting; the results are in good agreement.

  3. Financial market implications of monetary policy coincidences: Evidence from the UK and Euro Area government-bond markets

    OpenAIRE

    Arestis, Philip; Phelps, P

    2017-01-01

    Relatively little is known about the financial market impact of international monetary surprises arising on the same trading day. This paper estimates a suite of multi-security factor models, which captures international monetary surprise effects on UK and Euro Area government-bond markets over the period 1999–2014. In doing so, we shed light on the relative importance of coinciding, non-coinciding monetary surprises and non-monetary surprises across the yield curve. We find some support for ...

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

    International Nuclear Information System (INIS)

    Hillenbrand, Pierre-Michel

    2013-07-01

    Within the scope of this thesis the fundamental process of electron-nucleus bremsstrahlung was studied in inverse kinematics at the Experimental Storage Ring ESR at GSI. For the system U 88+ + N 2 at 90 MeV/u it was shown, that by using inverse kinematics coincidence measurements between the scattered electron and the emitted photon can be performed for the case, in which the incoming electron transfers almost all of its kinetic energy onto the emitted photon. The sensitivity to the fundamental process could be achieved by measuring triple differential cross sections as a function of the emission angle of the photon and the scattered electron as well as the energy of the scattered electron. The optics of the magnetic electron spectrometer used were thoroughly revised and optimized to the experimental requirements. Analyzing different coincidences in this collision system, it was possible to determine the contributions to the electron distribution arising from radiative electron capture to the projectile continuum, nonradiative electron capture to the projectile continuum, and electron loss to the projectile continuum. The experimental results of each of these processes were compared to theoretical calculations. The electron spectra for the radiative and the nonradiative electron capture to continuum clearly reproduce the opposite asymmetry predicted by theory. Furthermore electron spectra for collisions of U 28+ with different gases were measured.

  5. Metrology and statistical analysis for the precise standardisation of cobalt-60 by 4πβ-γ coincidence counting

    International Nuclear Information System (INIS)

    Buckman, S.M.

    1995-03-01

    The major part of the thesis is devoted to the theoretical development of a comprehensive PC-based statistical package for the analysis of data from coincidence-counting experiments. This analysis is applied to primary standardizations of Co performed in Australia and Japan. The Australian standardisation, the accuracy of which is confirmed through international comparison, is used to re-calibrate the ionisation chamber. Both Australian and Japanese coincidence-counting systems are interfaced to personal computers to enable replicated sets of measurements to be made under computer control. Further research to confirm the validity of the statistical model includes an experimental investigation into the non-Poisson behaviour of radiation detectors due to the effect of deadtime. Experimental investigation is conducted to determine which areas are most likely to limit the ultimate accuracy achievable with coincidence counting. The thesis concludes by discussing the possibilities of digital coincidence counting and outlines the design of a prototype system presently under development. The accuracy of the Australian standardisation is confirmed by international comparison. From this result a more accurate Co calibration is obtained for the Australian working standard. Based on the work of this thesis, uncertainties in coincidence counting experiments can be better handled with resulting improvements in measurement reliability. The concept and benefits of digital coincidence counting are discussed and a proposed design is given for such a system. All of the data and software associated with this thesis is provided on computer discs. 237 refs., figs., tabs

  6. Polarisation-based coincidence event discrimination: an in silico study towards a feasible scheme for Compton-PET

    Science.gov (United States)

    Toghyani, M.; Gillam, J. E.; McNamara, A. L.; Kuncic, Z.

    2016-08-01

    Current positron emission tomography (PET) systems use temporally localised coincidence events discriminated by energy and time-of-flight information. The two annihilation photons are in an entangled polarisation state and, in principle, additional information from the polarisation correlation of photon pairs could be used to improve the accuracy of coincidence classification. In a previous study, we demonstrated that in principle, the polarisation correlation information could be transferred to an angular correlation in the distribution of scattered photon pairs in a planar Compton camera system. In the present study, we model a source-phantom-detector system using Geant4 and we develop a coincidence classification scheme that exploits the angular correlation of scattered annihilation quanta to improve the accuracy of coincidence detection. We find a 22% image quality improvement in terms of the peak signal-to-noise ratio when scattered coincidence events are discriminated solely by their angular correlation, thus demonstrating the feasibility of this novel classification scheme. By integrating scatter events (both single-single and single-only) with unscattered coincidence events discriminated using conventional methods, our results suggest that Compton-PET may be a promising candidate for optimal emission tomographic imaging.

  7. NaI(Tl) electron energy resolution

    CERN Document Server

    Mengesha, W

    2002-01-01

    NaI(Tl) electron energy resolution eta sub e was measured using the Modified Compton Coincidence Technique (MCCT). The MCCT allowed detection of nearly monoenergetic internal electrons resulting from the scattering of incident 662 keV gamma rays within a primary NaI(Tl) detector. Scattered gamma rays were detected using a secondary HPGe detector in a coincidence mode. Measurements were carried out for electron energies ranging from 16 to 438 keV, by varying the scattering angle. Measured HPGe coincidence spectra were deconvolved to determine the scattered energy spectra from the NaI(Tl) detector. Subsequently, the NaI(Tl) electron energy spectra were determined by subtracting the energy of scattered spectra from the incident source energy (662 keV). Using chi-squared minimization, iterative deconvolution of the internal electron energy spectra from the measured NaI(Tl) spectra was then used to determine eta sub e at the electron energy of interest. eta sub e values determined using this technique represent va...

  8. Feynman variance-to-mean in the context of passive neutron coincidence counting

    Energy Technology Data Exchange (ETDEWEB)

    Croft, S., E-mail: scroft@lanl.gov [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545 (United States); Favalli, A.; Hauck, D.K.; Henzlova, D.; Santi, P.A. [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545 (United States)

    2012-09-11

    Passive Neutron Coincidence Counting (PNCC) based on shift register autocorrelation time analysis of the detected neutron pulse train is an important Nondestructive Assay (NDA) method. It is used extensively in the quantification of plutonium and other spontaneously fissile materials for purposes of nuclear materials accountancy. In addition to the totals count rate, which is also referred to as the singles, gross or trigger rate, a quantity known as the reals coincidence rate, also called the pairs or doubles, is obtained from the difference between the measured neutron multiplicities in two measurement gates triggered by the incoming events on the pulse train. The reals rate is a measure of the number of time correlated pairs present on the pulse train and this can be related to the fission rates (and hence material mass) since fissions emit neutrons in bursts which are also detected in characteristic clusters. A closely related measurement objective is the determination of the reactivity of systems as they approach criticality. In this field an alternative autocorrelation signature is popular, the so called Feynman variance-to-mean technique which makes use of the multiplicity histogram formed the periodic, or clock-triggered opening of a coincidence gate. Workers in these two application areas share common challenges and improvement opportunities but are often separated by tradition, problem focus and technical language. The purpose of this paper is to recognize the close link between the Feynman variance-to-mean metric and traditional PNCC using shift register logic applied to correlated pulse trains. We, show using relationships for the late-gate (or accidentals) histogram recorded using a multiplicity shift register, how the Feynman Y-statistic, defined as the excess variance-to-mean ratio, can be expressed in terms of the singles and doubles rates familiar to the safeguards and waste assay communities. These two specialisms now have a direct bridge between

  9. Coincidence and coherent data analysis methods for gravitational wave bursts in a network of interferometric detectors

    International Nuclear Information System (INIS)

    Arnaud, Nicolas; Barsuglia, Matteo; Bizouard, Marie-Anne; Brisson, Violette; Cavalier, Fabien; Davier, Michel; Hello, Patrice; Kreckelbergh, Stephane; Porter, Edward K.

    2003-01-01

    Network data analysis methods are the only way to properly separate real gravitational wave (GW) transient events from detector noise. They can be divided into two generic classes: the coincidence method and the coherent analysis. The former uses lists of selected events provided by each interferometer belonging to the network and tries to correlate them in time to identify a physical signal. Instead of this binary treatment of detector outputs (signal present or absent), the latter method involves first the merging of the interferometer data and looks for a common pattern, consistent with an assumed GW waveform and a given source location in the sky. The thresholds are only applied later, to validate or not the hypothesis made. As coherent algorithms use more complete information than coincidence methods, they are expected to provide better detection performances, but at a higher computational cost. An efficient filter must yield a good compromise between a low false alarm rate (hence triggering on data at a manageable rate) and a high detection efficiency. Therefore, the comparison of the two approaches is achieved using so-called receiving operating characteristics (ROC), giving the relationship between the false alarm rate and the detection efficiency for a given method. This paper investigates this question via Monte Carlo simulations, using the network model developed in a previous article. Its main conclusions are the following. First, a three-interferometer network such as Virgo-LIGO is found to be too small to reach good detection efficiencies at low false alarm rates: larger configurations are suitable to reach a confidence level high enough to validate as true GW a detected event. In addition, an efficient network must contain interferometers with comparable sensitivities: studying the three-interferometer LIGO network shows that the 2-km interferometer with half sensitivity leads to a strong reduction of performances as compared to a network of three

  10. Improving the singles rate method for modeling accidental coincidences in high-resolution PET

    International Nuclear Information System (INIS)

    Oliver, Josep F; Rafecas, Magdalena

    2010-01-01

    Random coincidences ('randoms') are one of the main sources of image degradation in PET imaging. In order to correct for this effect, an accurate method to estimate the contribution of random events is necessary. This aspect becomes especially relevant for high-resolution PET scanners where the highest image quality is sought and accurate quantitative analysis is undertaken. One common approach to estimate randoms is the so-called singles rate method (SR) widely used because of its good statistical properties. SR is based on the measurement of the singles rate in each detector element. However, recent studies suggest that SR systematically overestimates the correct random rate. This overestimation can be particularly marked for low energy thresholds, below 250 keV used in some applications and could entail a significant image degradation. In this work, we investigate the performance of SR as a function of the activity, geometry of the source and energy acceptance window used. We also investigate the performance of an alternative method, which we call 'singles trues' (ST) that improves SR by properly modeling the presence of true coincidences in the sample. Nevertheless, in any real data acquisition the knowledge of which singles are members of a true coincidence is lost. Therefore, we propose an iterative method, STi, that provides an estimation based on ST but which only requires the knowledge of measurable quantities: prompts and singles. Due to inter-crystal scatter, for wide energy windows ST only partially corrects SR overestimations. While SR deviations are in the range 86-300% (depending on the source geometry), the ST deviations are systematically smaller and contained in the range 4-60%. STi fails to reproduce the ST results, although for not too high activities the deviation with respect to ST is only a few percent. For conventional energy windows, i.e. those without inter-crystal scatter, the ST method corrects the SR overestimations, and deviations from

  11. Elimination of two atomic electrons by a single high energy photon

    International Nuclear Information System (INIS)

    Amusia, M.Y.; Ioffe, A.F.

    1993-01-01

    This report discusses the following topics: mechanism of two-electron photoionization; multiple photoionization near inner shell thresholds; double ionization accompanying compton-effect; and the investigation of secondary photon emission in coincidence with double charged ion production

  12. True coincidence summing correction determination for 214Bi principal gamma lines in NORM samples

    International Nuclear Information System (INIS)

    Haddad, Kh.

    2014-01-01

    The gamma lines 609.3 and 1,120.3 keV are two of the most intensive γ emissions of 214 Bi, but they have serious true coincidence summing (TCS) effects due to the complex decay schemes with multi-cascading transitions. TCS effects cause inaccurate count rate and hence erroneous results. A simple and easy experimental method for determination of TCS correction of 214 Bi gamma lines was developed in this work using naturally occurring radioactive material samples. Height efficiency and self attenuation corrections were determined as well. The developed method has been formulated theoretically and validated experimentally. The corrections problems were solved simply with neither additional standard source nor simulation skills. (author)

  13. Design and performance of the Savannah River Site Billet Active Well Coincidence Counter

    International Nuclear Information System (INIS)

    Griffin, J.C.; Sadowski, E.T.

    1991-01-01

    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 235 U 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

  14. Aspects of kinematical coincidence measurements of excitation energy division in damped reactions

    International Nuclear Information System (INIS)

    Toke, J.; Schroeder, W.U.; Huizenga, J.R.; Rochester Univ., NY

    1990-01-01

    It is shown that the finite resolution inherent in the kinematical coincidence method leads to systematic errors in the deduced (primary) physical quantities if the latter are calculated based on mass and linear momentum conservation equations alone. As an example, application of this method for measuring excitation energy of the fragments from damped reactions is reviewed. In such a case, finite resolution effects generate significant instrumental, or 'background' correlations between the physical quantities reconstructed in a straightforward fashion, hence, if not accounted for, they may lead to the qualitative misinterpretation of the data. Experimental measures are discussed which appear necessary in order to ensure proper accuracy of the finite resolution corrections. An alternative method of data analysis is presented which is much less susceptible to the finite resolution effects discussed. (orig.)

  15. Modular routing interface for simoultaneous list mode and histogramming mode storage of coincident data

    International Nuclear Information System (INIS)

    D'Achard van Eschut, J.F.M.; Nationaal Inst. voor Kernfysica en Hoge-Energiefysica

    1985-01-01

    A routing interface has been developed and built for successive storage of the digital output of four 13-bit ADCs, within 6 μs, into selected parts of two 16K CAMAC histogramming modules and, if an event trigger is applied, simultaneously into four 64-words deep (16-bit) first-in first-out (FIFO) CAMAC modules. In this way it is possible to accumulate on-line single spectra and, at the same time, write coincident data in list mode to magnetic tape under control of a computer. Additional routing interfaces can be used in parallel so that extensive data-collecting systems can be set up to store multi-parameter events. (orig.)

  16. Frequent floods in the European Alps coincide with cooler periods of the past 2500 years.

    Science.gov (United States)

    Glur, Lukas; Wirth, Stefanie B; Büntgen, Ulf; Gilli, Adrian; Haug, Gerald H; Schär, Christoph; Beer, Jürg; Anselmetti, Flavio S

    2013-09-26

    Severe floods triggered by intense precipitation are among the most destructive natural hazards in Alpine environments, frequently causing large financial and societal damage. Potential enhanced flood occurrence due to global climate change would thus increase threat to settlements, infrastructure, and human lives in the affected regions. Yet, projections of intense precipitation exhibit major uncertainties and robust reconstructions of Alpine floods are limited to the instrumental and historical period. Here we present a 2500-year long flood reconstruction for the European Alps, based on dated sedimentary flood deposits from ten lakes in Switzerland. We show that periods with high flood frequency coincide with cool summer temperatures. This wet-cold synchronism suggests enhanced flood occurrence to be triggered by latitudinal shifts of Atlantic and Mediterranean storm tracks. This paleoclimatic perspective reveals natural analogues for varying climate conditions, and thus can contribute to a better understanding and improved projections of weather extremes under climate change.

  17. Do climate extreme events foster violent civil conflicts? A coincidence analysis

    Science.gov (United States)

    Schleussner, Carl-Friedrich; Donges, Jonathan F.; Donner, Reik V.

    2014-05-01

    Civil conflicts promoted by adverse environmental conditions represent one of the most important potential feedbacks in the global socio-environmental nexus. While the role of climate extremes as a triggering factor is often discussed, no consensus is yet reached about the cause-and-effect relation in the observed data record. Here we present results of a rigorous statistical coincidence analysis based on the Munich Re Inc. extreme events database and the Uppsala conflict data program. We report evidence for statistically significant synchronicity between climate extremes with high economic impact and violent conflicts for various regions, although no coherent global signal emerges from our analysis. Our results indicate the importance of regional vulnerability and might aid to identify hot-spot regions for potential climate-triggered violent social conflicts.

  18. Catalyzing Transdisciplinarity: A Systems Ethnography of Cancer-Obesity Comorbidity and Risk Coincidence.

    Science.gov (United States)

    Graham, S Scott; Harley, Amy; Kessler, Molly M; Roberts, Laura; DeVasto, Dannielle; Card, Daniel J; Neuner, Joan M; Kim, Sang-Yeon

    2017-05-01

    Effectively addressing wicked health problems, that is, those arising from complex multifactorial biological and socio-economic causes, requires transdisciplinary action. However, a significant body of research points toward substantial difficulties in cultivating transdisciplinary collaboration. Accordingly, this article presents the results of a study that adapts Systems Ethnography and Qualitative Modeling (SEQM) in response to wicked health problems. SEQM protocols were designed to catalyze transdisciplinary responses to national defense concerns. We adapted these protocols to address cancer-obesity comorbidity and risk coincidence. In so doing, we conducted participant-observations and interviews with a diverse range of health care providers, community health educators, and health advocacy professionals who target either cancer or obesity. We then convened a transdisciplinary conference designed to catalyze a coordinated response. The findings offer productive insights into effective ways of catalyzing transdisciplinarity in addressing wicked health problems action and demonstrate the promise of SEQM for continued use in health care contexts.

  19. PLUMEX II: A second set of coincident radar and rocket observations of equatorial spread-F

    International Nuclear Information System (INIS)

    Szuszczewicz, E.P.; Tsunoda, R.T.; Narcisi, R.; Holmes, J.C.

    1981-01-01

    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

  20. 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)

  1. Characterizations of double pulsing in neutron multiplicity and coincidence counting systems

    Energy Technology Data Exchange (ETDEWEB)

    Koehler, Katrina E., E-mail: kkoehler@lanl.gov [Los Alamos National Laboratory, P. O. Box 1663, Los Alamos, NM 87545 (United States); Henzl, Vladimir [Los Alamos National Laboratory, P. O. Box 1663, Los Alamos, NM 87545 (United States); Croft, Stephen S. [Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37831 (United States); Henzlova, Daniela; Santi, Peter A. [Los Alamos National Laboratory, P. O. Box 1663, Los Alamos, NM 87545 (United States)

    2016-10-01

    Passive neutron coincidence/multiplicity counters are subject to non-ideal behavior, such as double pulsing and dead time. It has been shown in the past that double-pulsing exhibits a distinct signature in a Rossi-alpha distribution, which is not readily noticed using traditional Multiplicity Shift Register analysis. However, it has been assumed that the use of a pre-delay in shift register analysis removes any effects of double pulsing. In this work, we use high-fidelity simulations accompanied by experimental measurements to study the effects of double pulsing on multiplicity rates. By exploiting the information from the double pulsing signature peak observable in the Rossi-alpha distribution, the double pulsing fraction can be determined. Algebraic correction factors for the multiplicity rates in terms of the double pulsing fraction have been developed. We discuss the role of these corrections across a range of scenarios.

  2. Field test and evaluation of the passive neutron coincidence collar for prototype fast reactor fuel subassemblies

    International Nuclear Information System (INIS)

    Menlove, H.O.; Keddar, A.

    1982-08-01

    The passive neutron Coincidence Collar, which was developed for the verification of plutonium content in fast reactor fuel subassemblies, has been field tested using Prototype Fast Reactor fuel. For passive applications, the system measures the 240 Pu-effective mass from the spontaneous fission rate, and in addition, a self-interrogation technique is used to determine the fissile content in the subassembly. Both the passive and active modes were evaluated at the Windscale Works in the United Kingdom. The results of the tests gave a standard deviation 0.75% for the passive count and 3 to 7% for the active measurement for a 1000-s counting time. The unit will be used in the future for the verification of plutonium in fresh fuel assemblies

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

    International Nuclear Information System (INIS)

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

    1999-01-01

    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 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 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

  4. γ-Particle coincidence technique for the study of nuclear reactions

    Science.gov (United States)

    Zagatto, V. A. B.; Oliveira, J. R. B.; Allegro, P. R. P.; Chamon, L. C.; Cybulska, E. W.; Medina, N. H.; Ribas, R. V.; Seale, W. A.; Silva, C. P.; Gasques, L. R.; Zahn, G. S.; Genezini, F. A.; Shorto, J. M. B.; Lubian, J.; Linares, R.; Toufen, D. L.; Silveira, M. A. G.; Rossi, E. S.; Nobre, G. P.

    2014-06-01

    The Saci-Perere γ ray spectrometer (located at the Pelletron AcceleratorLaboratory - IFUSP) was employed to implement the γ-particle coincidence technique for the study of nuclear reaction mechanisms. For this, the 18O+110Pd reaction has been studied in the beam energy range of 45-54 MeV. Several corrections to the data due to various effects (energy and angle integrations, beam spot size, γ detector finite size and the vacuum de-alignment) are small and well controlled. The aim of this work was to establish a proper method to analyze the data and identify the reaction mechanisms involved. To achieve this goal the inelastic scattering to the first excited state of 110Pd has been extracted and compared to coupled channel calculations using the São Paulo Potential (PSP), being reasonably well described by it.

  5. γ-Particle coincidence technique for the study of nuclear reactions

    Energy Technology Data Exchange (ETDEWEB)

    Zagatto, V.A.B., E-mail: vinicius.zagatto@gmail.com [Instituto de Física da Universidade de São Paulo (Brazil); Oliveira, J.R.B.; Allegro, P.R.P.; Chamon, L.C.; Cybulska, E.W.; Medina, N.H.; Ribas, R.V.; Seale, W.A.; Silva, C.P.; Gasques, L.R. [Instituto de Física da Universidade de São Paulo (Brazil); Zahn, G.S.; Genezini, F.A.; Shorto, J.M.B. [Instituto de Pesquisas Energéticas e Nucleares (Brazil); Lubian, J.; Linares, R. [Instituto de Física da Universidade Federal Fluminense (Brazil); Toufen, D.L. [Instituto Federal de Educação, Ciência e Tecnologia (Brazil); Silveira, M.A.G. [Centro Universitário da FEI (Brazil); Rossi, E.S. [Centro Universitário FIEO – UNIFIEO (Brazil); Nobre, G.P. [Lawrence Livermore National Laboratory (United States)

    2014-06-01

    The Saci-Perere γ ray spectrometer (located at the Pelletron AcceleratorLaboratory – IFUSP) was employed to implement the γ-particle coincidence technique for the study of nuclear reaction mechanisms. For this, the {sup 18}O+{sup 110}Pd reaction has been studied in the beam energy range of 45–54 MeV. Several corrections to the data due to various effects (energy and angle integrations, beam spot size, γ detector finite size and the vacuum de-alignment) are small and well controlled. The aim of this work was to establish a proper method to analyze the data and identify the reaction mechanisms involved. To achieve this goal the inelastic scattering to the first excited state of {sup 110}Pd has been extracted and compared to coupled channel calculations using the São Paulo Potential (PSP), being reasonably well described by it.

  6. The Anti-Coincidence Detector for the GLAST Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Moiseev, A.A.; Hartman, R.C.; Ormes, J.F.; Thompson, D.J.; Amato, M.J.; Johnson, T.E.; Segal, K.N.; Sheppard, D.A.

    2007-03-23

    This paper describes the design, fabrication and testing of the Anti-Coincidence Detector (ACD) for the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT). The ACD is LAT's first-level defense against the charged cosmic ray background that outnumbers the gamma rays by 3-5 orders of magnitude. The ACD covers the top and 4 sides of the LAT tracking detector, requiring a total active area of {approx}8.3 square meters. The ACD detector utilizes plastic scintillator tiles with wave-length shifting fiber readout. In order to suppress self-veto by shower particles at high gamma-ray energies, the ACD is segmented into 89 tiles of different sizes. The overall ACD efficiency for detection of singly charged relativistic particles entering the tracking detector from the top or sides of the LAT exceeds the required 0.9997.

  7. PET with coincidence gamma cameras - clinical benefit from the radiooncologists' point of view

    International Nuclear Information System (INIS)

    Richter, E.; Feyerabend, T.; Stallmann, C.; Lauer, I.; Baehre, M.

    2001-01-01

    Positron emission tomography with FDG (FDG-PET) is a new technique, which displays the cellular metabolic activity. Since tumors exhibit an increased metabolic activity when compared to normal tissue, this imaging modality has a particularly high importance. FDG-PET is not only useful for localizing and staging of malignant tumors, but also to evaluate therapy response. In this context, PET is superior to morphologically orientated modalities, because therapeutically induced changes in glucose metabolism precede morphologic alterations. Numerous studies indicate, that PET will play an important role in radiooncology concerning therapy planning and monitoring the effects of therapy during and after treatment. Further clinical studies are necessary to evaluate the information provided by FDG-PET more precisely. Coincidence gamma cameras with adequate imaging characteristics will gain enhanced importance to meet these increasing demands. (orig.) [de

  8. Positron emission measurement with coincidence counting technic using large plastic scintillators

    International Nuclear Information System (INIS)

    Espinasse, P.; Minchella, P.

    1990-01-01

    For measuring positron emission of a large organ such as the brain for example, a device has been built with two cylindric plastic scintillators allowing the detection in coincidence of the 511 keV gamma rays without any spectrometry. The main results are for the sensitivity at the center of the field with 22 Na source in water: 240 ips/MBq; background = 12 ips, and for the countloss due to the deadtime >5% with 42 MBq. Sensitivity is almost uniform on the main axis between the probes. It falls to about 50% on the edges of a central diameter of 20 cm. The performances could certainly be improved by using modern rapid photomultipliers [fr

  9. Anisotropy in electron-atom collisions

    International Nuclear Information System (INIS)

    Linden van den Heuvel, H.B. van.

    1982-01-01

    Most of the work described in this thesis deals with studies using coincidence experiments, particularly for investigating the electron impact excitation of the 2 1 P and 3 1 D states in helium. A peculiarity is that in the 3 1 D studies the directly emitted 3 1 D → 2 1 P photons are not observed but the 2 1 P → 1 1 S photons resulting from the 3 1 D → 2 1 P → 1 1 S cascade instead. Another interesting point is the choice of the quantisation axis. The author demonstrates that it is of great advantage to take the quantisation axis perpendicular to the scattering plane rather than in the direction of the incident beam, as was done (on historical grounds) in previously reported electron-photon coincidence experiments. Contrary to the incident beam direction the axis perpendicular to the scattering plane really represents an axis of symmetry in the coincidence experiment. In Chapter II the so-called 'parity unfavoured' excitation of the (2p 2 ) 3 P state of helium by electrons is studied. In chapter III the anisotropy parameters for the electron impact excitation of the 2 1 P state of helium in the energy range from 26.6 to 40 eV and in the angular range from 30 0 to 110 0 are determined. Chapter IV contains a description of a scattered electron cascaded-photon coincidence experiment on the electron impact excitation of helium's 3 1 D state. The measurement of complex scattering amplitudes for electron impact excitation of the 3 1 D and 3 1 P states of helium is discussed in Chapter V. (Auth./C.F.)

  10. Evaluation Of The Coincidence Of Male Pattern Baldness And Pityrosporum Group Of Fungus In Iran

    Directory of Open Access Journals (Sweden)

    Javanbakht Arash

    2002-01-01

    Full Text Available The aetilogy of male pattern baldness (MPB is not clearly found yet. The present study has been designed to determine if three is a significant statistical coincidence between MPB and pityrosporm group of fungal infection. This cross-sectional study covers 50 men with the diagnosis of MPB who visited the dermatology clinic of Qaem hospital of Mashhad Medical University as the case group and 43 men with no evidence of MPB as the control group. A questionnaire was filled out for each person of the two groups and mycological sampling was done from three parts of the case group scalp (bald, balding, intact areas and two parts of the control group scalp (vertex and parietal. All the data were analysed using the software SPSS 10.00 and Chi-square, Pearson Chi-square and Friedman tests. Results showed that there was no difference between different degrees of infection in the intact area (p>0.05. Among the three parts of the case group scalp, bald area had the highest degree of infection (p<0.001. The degree of infection in the bald area of the case group scalp was higher than that of the vertex area of the control group scalp (p<0.001, while there was no difference between the degrees of infection in the intact area of the case group scalp and the parietal area of the control group scalp (p>0.05. This study supports some previous studies that claimed that there might be coincidence between MPB and pityrosporum fungal infection.

  11. Alpha particle spectra in coincidence with normal and superdeformed states in {sup 150}Tb

    Energy Technology Data Exchange (ETDEWEB)

    Viesti, G.; Lunardon, M.; Bazzacco, D. [dell`Universita, Padova (Italy)]|[INFN, Padova (Italy)] [and others

    1996-12-31

    The study of correlations between particle evaporation from highly excited compound nuclei at large angular momenta and the states in the final evaporation residues (ER) is a field of investigation which has been opened, in the last years, with the advent of the new large {gamma}-ray arrays. It is now possible to correlate the evaporation spectra to various bands with shapes ranging from spherical to superdeformed (SD) in the same final nucleus. It is generally accepted that the particle evaporation from the compound nucleus is chaotic and that only in the near-yrast {gamma} cascade, where the feeding of different classes of states takes place, the ordered motion is restored. The sensitivity of the particle spectra on the feeding of specific states in the residual nuclei can be taken as an indication that additional degrees of freedom might be important in the evaporation process or that particular regions of the phase space open to the decay populate preferentially some selected structures in the final cold nucleus. This latter point is important for the understanding of the feeding mechanism of SD states. Several experiments performed so far did not find a clear dependence of the shapes of the particle spectra on the excited states having different deformations in the ER. For example, the proton spectra in coincidence with transitions in the SD bands of {sup 133}Nd and {sup 152}Dy nuclei were found to be similar to those in coincidence with transitions in the normal deformed (ND) bands. Alpha particles have been proposed since long as a sensitive probe of the deformation of the emitting nucleus. Results are presented here of an experiment in which the authors have measured the energy spectra of alpha particles associated with different classes of states (ND and SD) in the {sup 150}Tb nucleus populated in the reaction {sup 37}Cl({sup 120}Sn, {alpha}3n{gamma}){sup 150}Tb.

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

    International Nuclear Information System (INIS)

    Simion, V.; Petrovici, M.; Pop, A.; Berceanu, I.; Duma, M.; Moisa, D.; Pagano, A.; Geraci, E.

    1999-01-01

    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 BaF 2 crystal of hexagonal section. The BaF 2 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)

  13. Revised Correlation between Odin/OSIRIS PMC Properties and Coincident TIMED/SABER Mesospheric Temperatures

    Science.gov (United States)

    Feofilov, A. G.; Petelina, S. V.; Kutepov, A. A.; Pesnell, W. D.; Goldberg, R. A.; Llewellyn, E. J.; Russell, J. M.

    2006-01-01

    The Optical Spectrograph and Infrared Imaging System (OSIRIS) instrument on board the Odin satellite detects Polar Mesospheric Clouds (PMCs) through the enhancement in the limb-scattered solar radiance. The Sounding of the Atmosphere using the Broadband Emission Radiometry (SABER) instrument on board the TIMED satellite is a limb scanning infrared radiometer that measures temperature and vertical profiles and energetic parameters for minor constituents in the mesosphere and lower thermosphere. The combination of OSIRIS and SABER data has been previously used to statistically derive thermal conditions for PMC existence [Petelina et al., 2005]. a, A.A. Kutepov, W.D. Pesnell, In this work, we employ the simultaneous common volume measurements of PMCs by OSIRIS and temperature profiles measured by SABER for the Northern Hemisphere summers of 2002-2005 and corrected in the polar region by accounting for the vibrational-vibrational energy exchange among the CO2 isotopes [Kutepov et al., 2006]. For each of 20 coincidences identified within plus or minus 1 degree latitude, plus or minus 2 degrees longitude and less than 1 hour time the frost point temperatures were calculated using the corresponding SABER temperature profile and water vapor densities of 1,3, and 10 ppmv. We found that the PMC presence and brightness correlated only with the temperature threshold that corresponds to the frost point. The absolute value of the temperature below the frost point, however, didn't play a significant role in the intensity of PMC signal for the majority of selected coincidences. The presence of several bright clouds at temperatures above the frost point is obviously related to the limitation of the limb geometry when some near- or far-field PMCs located at higher (and warmer) altitudes appear to be at lower altitudes.

  14. Correction for variable moderation and multiplication effects associated with thermal neutron coincidence counting

    International Nuclear Information System (INIS)

    Baron, N.

    1978-01-01

    A correction is described for multiplication and moderation when doing passive thermal neutron coincidence counting nondestructive assay measurements on powder samples of PuO 2 mixed arbitrarily with MgO, SiO 2 , and moderating material. The multiplication correction expression is shown to be approximately separable into the product of two independent terms; F/sub Pu/ which depends on the mass of 240 Pu, and F/sub αn/ which depends on properties of the matrix material. Necessary assumptions for separability are (1) isotopic abundances are constant, and (2) fission cross sections are independent of incident neutron energy: both of which are reasonable for the 8% 240 Pu powder samples considered here. Furthermore since all prompt fission neutrons are expected to have nearly the same energy distributions, variations among different samples can be due only to the moderating properties of the samples. Relative energy distributions are provided by a thermal neutron well counter having two concentric rings of 3 He proportional counters placed symmetrically about the well. Measured outer-to-inner ring ratios raised to an empirically determined power for coincidences, (N/sup I//N/sup O/)/sup Z/, and singles, (T/sup O//T/sup I/)/sup delta/, provide corrections for moderation and F/sub αn/ respectively, and F/sub Pu/ is approximated by M 240 /sup X//M 240 . The exponents are calibration constants determined by a least squares fitting procedure using standards' data. System calibration is greatly simplified using the separability principle. Once appropriate models are established for F/sub Pu/ and F/sub αn/, only a few standards are necessary to determine the calibration constants associated with these terms. Since F/sub Pu/ is expressed as a function of M 240 , correction for multiplication in a subsequent assay demands only a measurement of F/sub αn/

  15. Development of portable Liquid Scintillation counters for on-site primary measurement of radionuclides using the Triple-to-Double Coincidence Ratio method

    International Nuclear Information System (INIS)

    Cassette, P.; Capogni, M.; De Felice, P.; Johansson, L.; Sephton, J.; Kossert, K.; Naehle, O.

    2013-06-01

    The Triple-to-Double Coincidence Ratio (TDCR) method in Liquid Scintillation counting (LSC) is a primary radionuclide standardization method widely used in National Metrology laboratories and was primarily developed for the activity measurement of beta emitters. It is based on liquid scintillation: the light is detected by three photomultipliers (PM) and the detection efficiency is evaluated by using a model which uses the ratio of triple-to-double coincidences between the PM tubes. Up to now, most of current TDCR systems were locally-made metrology instruments neither aimed at nor suitable for in-situ measurements. In the framework of the European Metrofission project, a work package was dedicated to the realisation of miniature self-calibrated primary TDCR systems, which are state-of-the-art, for use on-site. The challenge was to develop a versatile portable, table-top designed instrument, from this metrology device. This implied improvements for the miniaturisation of the detection chamber, for the miniaturisation of electronic modules by exploring the possibilities of digital treatment, and for the validation of models and extension of them to nuclides with special beta spectrum shapes, to nuclides with complex decay schemes including many gamma-rays and to nuclides with higher atomic number decaying by electron capture. Four prototypes of counters were built by the Metrofission partners ENEA (Italy), LNHB (France), NPL (UK) and PTB (Germany) using various technical approaches. The paper describes these prototypes and provides some details on the choice of the technical options concerning the design of the optical chamber, of the photodetectors and of the acquisition system. (authors)

  16. Value of coincidence gamma camera PET for diagnosing head and neck tumors: functional imaging and image coregistration

    International Nuclear Information System (INIS)

    Dresel, S.; Brinkbaeumer, K.; Schmid, R.; Hahn, K.

    2001-01-01

    54 patients suffering from head and neck tumors (30 m, 24 f, age: 32-67 years) were examined using dedicated PET and coincidence gamma camera PET after injection of 185-350 MBq [ 18 F]FDG. Examinations were carried out on the dedicated PET first (Siemens ECAT Exact HR+) followed by a scan on the coincidence gamma camera PET (Picker Prism 2000 XP-PCD, Marconi Axis g-PET 2 AZ). Dedicated PET was acquired in 3D mode, coincidence gamma camera PET was performed in list mode using an axial filter. Reconstruction of data was performed iteratively on both, dedicated PET and coincidence gamma camera PET. All patients received a CT scan in multislice technique (Siemens Somatom Plus 4, Marconi MX 8000). Image coregistration was performed on an Odyssey workstation (Marconi). All findings have been verified by the gold standard histology or in case of negative histology by follow-up. Results: Using dedicated PET the primary or recurrent lesion was correctly diagnosed in 47/48 patients, using coincidence gamma camera PET in 46/48 patients and using CT in 25/48 patients. Metastatic disease in cervical lymph nodes was diagnosed in 17/18 patients with dedicated PET, in 16/18 patients with coincidence gamma camera PET and in 15/18 with CT. False-positive results with regard to lymph node metastasis were seen with one patient for dedicated PET and hybrid PET, respectively, and with 18 patients for CT. In a total of 11 patients unknown metastatic lesions were seen with dedicated PET and with coincidence gamma camera PET elsewhere in the body (lung: n = 7, bone: n = 3, liver: n = 1). Additional malignant disease other than the head and neck tumor was found in 4 patients. (orig.) [de

  17. Coincidence: Fortran code for calculation of (e, e'x) differential cross-sections, nuclear structure functions and polarization asymmetry in self-consistent random phase approximation with Skyrme interaction

    Energy Technology Data Exchange (ETDEWEB)

    Cavinato, M.; Marangoni, M.; Saruis, A.M.

    1990-10-01

    This report describes the COINCIDENCE code written for the IBM 3090/300E computer in Fortran 77 language. The output data of this code are the (e, e'x) threefold differential cross-sections, the nuclear structure functions, the polarization asymmetry and the angular correlation coefficients. In the real photon limit, the output data are the angular distributions for plane polarized incident photons. The code reads from tape the transition matrix elements previously calculated, by in continuum self-consistent RPA (random phase approximation) theory with Skyrme interactions. This code has been used to perform a numerical analysis of coincidence (e, e'x) reactions with polarized electrons on the /sup 16/O nucleous.

  18. Software for the on-off-line A-A-T coincidence experiment with use of semiconductor detector of nuclear radiation

    International Nuclear Information System (INIS)

    Samatov, Zh.K.; Fominyh, V.I.; Gromov, K.Ya; Samatov, Zh.K.; Safarov, A.N.

    2006-01-01

    Full text: In γ-spectra measurements with 200 cm 3 HPGe-detector with energy resolution (FWHM) of 3.5 keV for α-rays 1.33 MeV 60 Co, 60 cm 3 Ge(Li)-detector with energy resolution of 1.9 keV for γ -rays 1.33 MeV 60 Co, 2 cm 3 HPGe-detector with energy resolution of 1.0 keV for α-rays 122 keV 57 Co and planar 250 mm 3 HPGe-detector with energy resolution of 0.5 keV for γ -rays 53 keV 133 Ba. For accumulation and analysis of the experimental information the analog electronics produced companies ORTEC, CANBERRA, Dzhelepov Laboratory of Nuclear Problem of JINR, units of the digital electronics of standard KAMAK, personal computers were used. The accumulation of information on the coincidence spectra was provided by record of each event (E 1 , E 2 , t)-coincidence (in list mode) and single spectra E 1 and E 2 that gave the broad possibilities for analysis result after completion experiment by means of the multiple sorting of information on spectra of the coincidences with installation the energy and time windows. In the report, a description of programs of the management and control of the on-off-line experiment designed at the begin 90-s being performed in Dubna by the YASNAPP-2 program [1-3] on the experimental complex for study nuclei far from the drip-line β-stability is given. The publication of the description of controlling programs is retard from publication of descriptions of the measuring equipment and result of the physical studies [4-6] due to in particular with creation in Institute of Nuclear Physics in Tashkent of the experimental complex γ-γ -coincidences, which can be used to accumulate the unpublished material by authors. The programs are formed in the Turbo-Pascal language with reference to the KAMAK-standard digital equipment and spectrometric equipment in standard NIM. It is properly to classify beforehand the programs in amount of 50 items: Program of the accumulation coincidence spectra of the type A-A-T with using the digital windows and

  19. Auger decay of 1σg and 1σu hole states of the N2 molecule: Disentangling decay routes from coincidence measurements

    International Nuclear Information System (INIS)

    Semenov, S. K.; Schoeffler, M. S.; Titze, J.; Petridis, N.; Jahnke, T.; Cole, K.; Schmidt, L. Ph. H.; Czasch, A.; Jagutzki, O.; Schmidt-Boecking, H.; Doerner, R.; Akoury, D.; Williams, J. B.; Landers, A. L.; Osipov, T.; Lee, S.; Prior, M. H.; Belkacem, A.; Weber, Th.; Cherepkov, N. A.

    2010-01-01

    Results of the most sophisticated measurements in coincidence with the angular-resolved K-shell photoelectrons and Auger electrons and with two atomic ions produced by dissociation of N 2 molecule are analyzed. Detection of photoelectrons at certain angles makes it possible to separate the Auger decay processes of the 1σ g and 1σ u core-hole states. The Auger electron angular distributions for each of these hole states are measured as a function of the kinetic-energy release of two atomic ions and are compared with the corresponding theoretical angular distributions. From that comparison one can disentangle the contributions of different repulsive doubly charged molecular ion states to the Auger decay. Different kinetic-energy-release values are directly related to the different internuclear distances. In this way one can trace experimentally the behavior of the potential energy curves of dicationic final states inside the Frank-Condon region. Presentation of the Auger-electron angular distributions as a function of kinetic-energy release of two atomic ions opens a new dimension in the study of Auger decay.

  20. Method and program for decay scheme reconstruction based on formal logical analysis of gamma-gamma coincidence matrix

    International Nuclear Information System (INIS)

    Adam, J.; Tsupko-Sitnikov, V.M.

    1996-01-01

    A new, rigorously substantiated approach to construction of decay schemes on the basis of γ-γ coincidence data is described. Complete decay modes (concrete cascades of transitions from excited to the ground-state of a nucleus excited in a decay or a reaction) and continuity regions in complete modes (regions of successive transitions) are isolated by logical operations with rows (columns) of a symmetrical coincidence matrix where rows (columns) correspond to energies of coinciding transitions and matrix elements are unities and zeros, depending on the presence or absence of the given coincidence. To reject false complete modes and continuity regions arising from incompleteness of the coincidence data and errors in them, energy selection is introduced for complete modes and continuity regions, which demands that total energy of their constituent transitions should be equal to total energy of some other complete modes and continuity regions and to the energies of singles. With the continuity regions found, it is possible to order transitions in the selected complete modes and to algorithmize matching of complete modes into a decay scheme. 10 refs., 3 figs

  1. Electronic technology

    International Nuclear Information System (INIS)

    Kim, Jin Su

    2010-07-01

    This book is composed of five chapters, which introduces electronic technology about understanding of electronic, electronic component, radio, electronic application, communication technology, semiconductor on its basic, free electron and hole, intrinsic semiconductor and semiconductor element, Diode such as PN junction diode, characteristic of junction diode, rectifier circuit and smoothing circuit, transistor on structure of transistor, characteristic of transistor and common emitter circuit, electronic application about electronic equipment, communication technology and education, robot technology and high electronic technology.

  2. 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

  3. The value of attenuation correction in dual-head coincidence imaging

    International Nuclear Information System (INIS)

    Shi Yiping; Huang Gang; Liu Jianjun

    2004-01-01

    Objective: To elucidate the value of attenuation correction (AC) in dual-head coincidence imaging by comparison of phantom and patients images with and without AC. Methods: We used a 20-cm-diameter cylindrical phantom, which contains four spheres of inside diameters of 1.4-2.9 cm for phantom study (1.4 cm, n=2; 2.0 cm, n=l; 2.9 cm, n=1). The axial length of the phantom was 30 cm. The wall thickness of the spheres was 1 mm. Both the phantom and spheres were filled with a solution that contained 18F-FDG. Three acquisitions were performed with the concentrations adjusted to provide a ratio of sphere-to-background activity of 3:1, 5:1 and 10:1. There were 38 patients (30 men and 8 women, age range 31 to 78 years) with suspected lung cancer included in clinical study. All patients were performed pneumonectomies and verified by histopathology. The histological tumor types were adenocarcinoma (n=11), squamous carcinoma (n=8), adenosquamous carcinoma (n=4), large cell carcinoma (n=2), neuroendocrine carcinoma (n=l), metastatic carcinoma (n=4), bronchiolo-alveolar carcinoma (n=1) and benign mass (n=7). The patients were fasted for at least 6 hours before the start of the study. Sixty minutes after intravenous administration of 111-185MBq (3-5mCi) 18F-FDG, emission scanning was performed using a dual-head gamma camera with a 128x128x16 matrix, with energy windows of 511 keV, 180 degree rotation, 32 steps and an acquisition time of 40 s per step. Subsequently, transmission scanning was performed with energy windows of 662 keV, 360 degree rotation, 96 steps and an acquisition time of 2s per step. The coincidence gamma camera imaging data were reconstructed by MCD iterative Methods with a Wiener filter (noise factor 0.75, pixel size 3.95 mm 3 ). Visual analysis and semiquantitative analysis were performed in AC and NAC images. For visual interpretation, a positive lesion was defined as any activity above local background. The count ratio of tumor to surrounded normal tissue (T

  4. The Electron

    Energy Technology Data Exchange (ETDEWEB)

    Thomson, George

    1972-01-01

    Electrons are elementary particles of atoms that revolve around and outside the nucleus and have a negative charge. This booklet discusses how electrons relate to electricity, some applications of electrons, electrons as waves, electrons in atoms and solids, the electron microscope, among other things.

  5. Fragment ion and electron emission from C sub 6 sub 0 by fast heavy ion impact

    CERN Document Server

    Mizuno, T; Itoh, A; Tsuchida, H; Nakai, Y

    2003-01-01

    Correlation between electron emission and fragmentation of C sub 6 sub 0 was studied using 847keV Si sup + ions. Mass distribution of fragment ions, number distribution of secondary electrons, and final charge distribution of outgoing projectiles were successfully measured by means of a triple coincidence time-of-flight method. Strong correlation was observed for electron emission and fragmentation.

  6. Electron spectroscopy studies of argon K-shell excitation and vacancy cascades

    International Nuclear Information System (INIS)

    Southworth, S.H.; MacDonald, M.A.; LeBrun, T.; Azuma, Y.; Cooper, J.W.

    1995-01-01

    Electron spectroscopy combined with tunable synchrotron radiation has been used for studies of Ar K-shell excitation and vacancy decay processes. In addition, electrons and fluorescent X-rays have been recorded in coincidence to select subsets of the ejected electron spectra. Examples are presented for Ar 1s photoelectrons and KLL and LMM Auger spectra

  7. Cocaine Promotes Coincidence Detection and Lowers Induction Threshold during Hebbian Associative Synaptic Potentiation in Prefrontal Cortex.

    Science.gov (United States)

    Ruan, Hongyu; Yao, Wei-Dong

    2017-01-25

    Addictive drugs usurp neural plasticity mechanisms that normally serve reward-related learning and memory, primarily by evoking changes in glutamatergic synaptic strength in the mesocorticolimbic dopamine circuitry. Here, we show that repeated cocaine exposure in vivo does not alter synaptic strength in the mouse prefrontal cortex during an early period of withdrawal, but instead modifies a Hebbian quantitative synaptic learning rule by broadening the temporal window and lowers the induction threshold for spike-timing-dependent LTP (t-LTP). After repeated, but not single, daily cocaine injections, t-LTP in layer V pyramidal neurons is induced at +30 ms, a normally ineffective timing interval for t-LTP induction in saline-exposed mice. This cocaine-induced, extended-timing t-LTP lasts for ∼1 week after terminating cocaine and is accompanied by an increased susceptibility to potentiation by fewer pre-post spike pairs, indicating a reduced t-LTP induction threshold. Basal synaptic strength and the maximal attainable t-LTP magnitude remain unchanged after cocaine exposure. We further show that the cocaine facilitation of t-LTP induction is caused by sensitized D1-cAMP/protein kinase A dopamine signaling in pyramidal neurons, which then pathologically recruits voltage-gated l-type Ca 2+ channels that synergize with GluN2A-containing NMDA receptors to drive t-LTP at extended timing. Our results illustrate a mechanism by which cocaine, acting on a key neuromodulation pathway, modifies the coincidence detection window during Hebbian plasticity to facilitate associative synaptic potentiation in prefrontal excitatory circuits. By modifying rules that govern activity-dependent synaptic plasticity, addictive drugs can derail the experience-driven neural circuit remodeling process important for executive control of reward and addiction. It is believed that addictive drugs often render an addict's brain reward system hypersensitive, leaving the individual more susceptible to

  8. The measurement of cross sections of inelastic and transfer reactions with gamma-particle coincidence

    Energy Technology Data Exchange (ETDEWEB)

    Zagatto, V.A.B.; Oliveira, J.R.B.; Pereira, D.; Allegro, P.R.P.; Chamon, L.C.; Cybulska, E.W.; Medina, N.H.; Ribas, R.V.; Rossi Junior, E.S.; Seale, W.A.; Silva, C.P.; Gasques, L. [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica; Toufen, D.L. [Instituto Federal de Educacao, Ciencia e Tecnologia, Guarulhos, SP (Brazil); Silveira, M.A.G. [Centro Universitario da FEI, Sao Bernardo do Campo, SP (Brazil); Zahn, G.S.; Genezini, F.A.; Shorto, J.M.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Lubian, J.; Linares, R. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Fisica; Nobre, G.P. [Lawrence Livermore National Laboratory, Livermore (United States)

    2012-07-01

    Full text: A new method was developed in Pelletron laboratory to measure gamma-particle coincidences and the chosen experiment to test this method was the {sup 18}O +{sup 110} Pd in the 46-60 MeV range. The following work aims to obtain experimental cross sections of inelastic excitation 0{sup +} {yields} 2{sup +} of {sup 110}Pd and transfer to excited states reactions (both measured by gamma-particle coincidences). The measurements were made at the Pelletron accelerator laboratory of the University of Sao Paulo with the Saci-Perere spectrometer [1], which consists of 4 GeHP Compton suppressed gamma detectors and a 4{pi} charged particle ancillary system with 11{Delta}E-E plastic phoswich scintillators (further details about the experimental procedure may be found in [2]). Calculations were performed with a new model based on the Sao Paulo Potential, specifically developed for the inclusion of dissipative processes like deep-inelastic collisions (DIC) [3,4] considering the Coulomb plus nuclear potential (with the aid of FRESCO code [5]). The experimental cross sections were obtained such as described in [6] including particle-gamma angular correlations, finite size of gamma and particle detectors as the vacuum de-alignment effects [7] (caused by hyperfine interaction) for the {sup 110}Pd inelastic reaction and for the {sup 110}Pd 2n transfer reaction. Also the effects of the beam spot size and energy loss in the target were included in these calculations. For these purposes a new code has been developed to assist in the data analysis. The gamma-particle angular correlations are calculated using the scattering amplitudes given by FRESCO. The theoretical predictions still consider 2 different types of normalization factors in its the real part: 1:0, and 0:6 as proposed in [3] for the weakly bound projectile cases. The analyses indicate that the 0:6 factor describes better the experimental data possible due to the large density of states in the transitional region. [1

  9. The ancient Egyptian civilization: maximum and minimum in coincidence with solar activity

    Science.gov (United States)

    Shaltout, M.

    It is proved from the last 22 years observations of the total solar irradiance (TSI) from space by artificial satellites, that TSI shows negative correlation with the solar activity (sunspots, flares, and 10.7cm Radio emissions) from day to day, but shows positive correlations with the same activity from year to year (on the base of the annual average for each of them). Also, the solar constant, which estimated fromth ground stations for beam solar radiations observations during the 20 century indicate coincidence with the phases of the 11- year cycles. It is known from sunspot observations (250 years) , and from C14 analysis, that there are another long-term cycles for the solar activity larger than 11-year cycle. The variability of the total solar irradiance affecting on the climate, and the Nile flooding, where there is a periodicities in the Nile flooding similar to that of solar activity, from the analysis of about 1300 years of the Nile level observations atth Cairo. The secular variations of the Nile levels, regularly measured from the 7 toth 15 century A.D., clearly correlate with the solar variations, which suggests evidence for solar influence on the climatic changes in the East African tropics The civilization of the ancient Egyptian was highly correlated with the Nile flooding , where the river Nile was and still yet, the source of the life in the Valley and Delta inside high dry desert area. The study depends on long -time historical data for Carbon 14 (more than five thousands years), and chronical scanning for all the elements of the ancient Egyptian civilization starting from the firs t dynasty to the twenty six dynasty. The result shows coincidence between the ancient Egyptian civilization and solar activity. For example, the period of pyramids building, which is one of the Brilliant periods, is corresponding to maximum solar activity, where the periods of occupation of Egypt by Foreign Peoples corresponding to minimum solar activity. The decline

  10. Hard electronics; Hard electronics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    Hard material technologies were surveyed to establish the hard electronic technology which offers superior characteristics under hard operational or environmental conditions as compared with conventional Si devices. The following technologies were separately surveyed: (1) The device and integration technologies of wide gap hard semiconductors such as SiC, diamond and nitride, (2) The technology of hard semiconductor devices for vacuum micro- electronics technology, and (3) The technology of hard new material devices for oxides. The formation technology of oxide thin films made remarkable progress after discovery of oxide superconductor materials, resulting in development of an atomic layer growth method and mist deposition method. This leading research is expected to solve such issues difficult to be easily realized by current Si technology as high-power, high-frequency and low-loss devices in power electronics, high temperature-proof and radiation-proof devices in ultimate electronics, and high-speed and dense- integrated devices in information electronics. 432 refs., 136 figs., 15 tabs.

  11. Corrections for the effects of accidental coincidences, Compton scatter, and object size in positron emission mammography (PEM) imaging

    Energy Technology Data Exchange (ETDEWEB)

    Raymond Raylman; Stanislaw Majewski; Randolph Wojcik; Andrew Weisenberger; Brian Kross; Vladimir Popov

    2001-06-01

    Positron emission mammography (PEM) has begun to show promise as an effective method for the detection of breast lesions. Due to its utilization of tumor-avid radiopharmaceuticals labeled with positron-emitting radionuclides, this technique may be especially useful in imaging of women with radiodense or fibrocystic breasts. While the use of these radiotracers affords PEM unique capabilities, it also introduces some limitations. Specifically, acceptance of accidental and Compton-scattered coincidence events can decrease lesion detectability. The authors studied the effect of accidental coincidence events on PEM images produced by the presence of 18F-Fluorodeoxyglucose in the organs of a subject using an anthropomorphic phantom. A delayed-coincidence technique was tested as a method for correcting PEM images for the occurrence of accidental events. Also, a Compton scatter correction algorithm designed specifically for PEM was developed and tested using a compressed breast phantom.

  12. A First Search for Coincident Gravitational Waves and High Energy Neutrinos Using LIGO, Virgo and ANTARES Data from 2007

    Science.gov (United States)

    Adrian-Martinez, S.; Samarai, Al; Albert, A.; Andre, M.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardid, M; Astraatmadja, T.; Aubert, J.-J.; hide

    2013-01-01

    We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.

  13. A gamma-gamma coincidence/anticoincidence spectrometer for low-level cosmogenic (22)Na/(7)Be activity ratio measurement.

    Science.gov (United States)

    Zhang, Weihua; Ungar, Kurt; Stukel, Matthew; Mekarski, Pawel

    2014-04-01

    In this study, a digital gamma-gamma coincidence/anticoincidence spectrometer was developed and examined for low-level cosmogenic (22)Na and (7)Be in air-filter sample monitoring. The spectrometer consists of two bismuth germanate scintillators (BGO) and an XIA LLC Digital Gamma Finder (DGF)/Pixie-4 software and card package. The spectrometer design allows a more selective measurement of (22)Na with a significant background reduction by gamma-gamma coincidence events processing. Hence, the system provides a more sensitive way to quantify trace amounts of (22)Na than normal high resolution gamma spectrometry providing a critical limit of 3 mBq within a 20 h count. The use of a list-mode data acquisition technique enabled simultaneous determination of (22)Na and (7)Be activity concentrations using a single measurement by coincidence and anticoincidence mode respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Search for Transient Gravitational Waves in Coincidence with Short-Duration Radio Transients During 2007-2013

    Science.gov (United States)

    Abbott, B. P.; Hughey, Brennan; Zanolin, Michele; Szczepanczyk, Marek; Gill, Kiranjyot; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; hide

    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 (Laser Interferometer Gravitational Wave Observatory), Virgo (Variability of Solar Irradiance and Gravity Oscillations) and GEO (German-UK Interferometric Detector) 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-wave emission include star quakes 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.

  15. Corrections for the effects of accidental coincidences, Compton scatter, and object size in positron emission mammography (PEM) imaging

    International Nuclear Information System (INIS)

    Raymond Raylman; Stanislaw Majewski; Randolph Wojcik; Andrew Weisenberger; Brian Kross; Vladimir Popov

    2001-01-01

    Positron emission mammography (PEM) has begun to show promise as an effective method for the detection of breast lesions. Due to its utilization of tumor-avid radiopharmaceuticals labeled with positron-emitting radionuclides, this technique may be especially useful in imaging of women with radiodense or fibrocystic breasts. While the use of these radiotracers affords PEM unique capabilities, it also introduces some limitations. Specifically, acceptance of accidental and Compton-scattered coincidence events can decrease lesion detectability. The authors studied the effect of accidental coincidence events on PEM images produced by the presence of 18F-Fluorodeoxyglucose in the organs of a subject using an anthropomorphic phantom. A delayed-coincidence technique was tested as a method for correcting PEM images for the occurrence of accidental events. Also, a Compton scatter correction algorithm designed specifically for PEM was developed and tested using a compressed breast phantom

  16. A new 4π(LS)-γ coincidence counter at NCBJ RC POLATOM with TDCR detector in the beta channel.

    Science.gov (United States)

    Ziemek, T; Jęczmieniowski, A; Cacko, D; Broda, R; Lech, E

    2016-03-01

    A new 4π(LS)-γ coincidence system (TDCRG) was built at the NCBJ RC POLATOM. The counter consists of a TDCR detector in the beta channel and scintillation detector with NaI(Tl) crystal in the gamma channel. The system is equipped with a digital board with FPGA, which records and analyses coincidences in the TDCR detector and coincidences between the beta and gamma channels. The characteristics of the system and a scheme of the FPGA implementation with behavioral simulation are given. The TDCRG counter was validated by activity measurements on (14)C and (60)Co solutions standardized in RC POLATOM using previously validated methods. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Integrative Genomic Analysis of Coincident Cancer Foci Implicates CTNNB1 and PTEN Alterations in Ductal Prostate Cancer.

    Science.gov (United States)

    Gillard, Marc; Lack, Justin; Pontier, Andrea; Gandla, Divya; Hatcher, David; Sowalsky, Adam G; Rodriguez-Nieves, Jose; Vander Griend, Donald; Paner, Gladell; VanderWeele, David

    2017-12-08

    Ductal adenocarcinoma of the prostate is an aggressive subtype, with high rates of biochemical recurrence and overall poor prognosis. It is frequently found coincident with conventional acinar adenocarcinoma. The genomic features driving evolution to its ductal histology and the biology associated with its poor prognosis remain unknown. To characterize genomic features distinguishing ductal adenocarcinoma from coincident acinar adenocarcinoma foci from the same patient. Ten patients with coincident acinar and ductal prostate cancer underwent prostatectomy. Laser microdissection was used to separately isolate acinar and ductal foci. DNA and RNA were extracted, and used for integrative genomic and transcriptomic analyses. Single nucleotide mutations, small indels, copy number estimates, and expression profiles were identified. Phylogenetic relationships between coincident foci were determined, and characteristics distinguishing ductal from acinar foci were identified. Exome sequencing, copy number estimates, and fusion genes demonstrated coincident ductal and acinar adenocarcinoma diverged from a common progenitor, yet they harbored distinct alterations unique to each focus. AR expression and activity were similar in both histologies. Nine of 10 cases had mutually exclusive CTNNB1 hotspot mutations or phosphatase and tensin homolog (PTEN) alterations in the ductal component, and these were absent in the acinar foci. These alterations were associated with changes in expression in WNT- and PI3K-pathway genes. Coincident ductal and acinar histologies typically are clonally related and thus arise from the same cell of origin. Ductal foci are enriched for cases with either a CTNNB1 hotspot mutation or a PTEN alteration, and are associated with WNT- or PI3K-pathway activation. These alterations are mutually exclusive and may represent distinct subtypes. The aggressive subtype ductal adenocarcinoma is closely related to conventional acinar prostate cancer. Ductal foci

  18. Future directions in electron momentum spectroscopy of matter

    International Nuclear Information System (INIS)

    Weigold, E.

    1998-01-01

    The development of coincidence spectrometers with multivariable detection techniques, higher energy kinematics, monochromated and spin-polarised electron sources, will usher in a new generation of electron momentum spectroscopy revealing new electronic phenomena in atoms, molecules and solids. This will be enhanced by developments in target preparation, such as spin polarised, oriented and aligned atoms and molecules, radicals, surfaces and strongly correlated systems in condensed matter. Copyright (1998) CSIRO Australia

  19. Sub aqueous electronics of neutrino detector; Podvodnaya ehlektronika nejtrinnogo detektora

    Energy Technology Data Exchange (ETDEWEB)

    Borisovets, B A; Donskikh, L A; Klabukov, A M [and others

    1996-12-31

    Paper describes the systems of measuring electronics of NT-200 neutrino detector designed to carry out investigations in the field of neutrino astrophysics. Correlation measuring electronics unit are presented by two two-level discriminators and coincidence circuit is studied. 6-channel unit of electronic chain covering time-code number recording is designed for data communication into the computer. detector calibration mode is described. 3 refs.

  20. Light particles emitted in coincidence with evaporation residues in 79Br(930 MeV) + 27Al collisions

    International Nuclear Information System (INIS)

    Chavez Lomeli, E.; Dacal, A.; Ortiz, M.E.; Gomez del Campo, J.; Kim, H.; Korolija, M.; Shapira, D.

    1993-01-01

    Exclusive measurements of light particles, deuterons, tritons and alphas, in coincidence with Evaporation Residues (ER), were performed at the Holified Heavy Ion Research Facility of the Oak Ridge National Laboratory using the large detector array HILI (Heavy Ion Light Ion). Heavy fragments produced in the reaction (Z 35), were stopped in the Ionisation Chamber, where their energy, atomic number (Z) and position were measured. Coincident light particles, were detected in the 192 element hodoscope placed behind the chamber, where its charge (Z) and energy were measured. Also the time of flight relative to the radio frequency of the cyclotron, allowed identification of protons deuterons and tritons