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Sample records for charged photofragment coincidence

  1. Molecular ion photofragment spectroscopy

    International Nuclear Information System (INIS)

    A new molecular ion photofragment spectrometer is described which features a supersonic molecular beam ion source and a radio frequency octapole ion trap interaction region. This unique combination allows several techniques to be applied to the problem of detecting a photon absorption event of a molecular ion. In particular, it may be possible to obtain low resolution survey spectra of exotic molecular ions by using a direct vibrational predissociation process, or by using other more indirect detection methods. The use of the spectrometer is demonstrated by measuring the lifetime of the O2+(4π/sub u/) metastable state which is found to consist of two main components: the 4π/sub 5/2/ and 4π/sub -1/2/ spin components having a long lifetime (approx. 129 ms) and the 4π/sub 3/2/ and 4π/sub 1/2/ spin components having a short lifetime (approx. 6 ms)

  2. Light charged particles emitted in coincidence with deeply inelastic collisions in the 280 MeV 40Ar + 58Ni reaction

    International Nuclear Information System (INIS)

    A detailed study was made of the light charged particles (mainly protons and alpha particles) in coincidence with the main fragments from deep inelastic collisions in the reaction 280 MeV 40Ar + 58Ni. A survey of relevant data is followed by a discussion of the origin of the light charged particles as it can be deduced from the p, α-fragment coincidence experiment. The results of out-of-plane distributions of the α-particles are presented and they are discussed in terms of the extreme sticking limit

  3. Fast Beam Investigations of Two- and Three-Body Photodissociation by Time- and Position-Coincidence Imaging

    OpenAIRE

    Crider, Paul

    2010-01-01

    Fast beam photofragment translational spectroscopy has been used to elucidate the photodissociation dynamics of small radicals and closed-shell anions. Imaging of photofragments in time- and position-coincidence allows the determination of mass distributions, translational energy distributions [P(ET) distributions], and in the case of three-body fragmentation channels, ternary Dalitz plots depicting the momentum disposal among the fragments. These data yield information about the potential en...

  4. Light charged particles emitted in coincidence with deeply inelastic collisions in the 280MeV 40Ar+58Ni reaction

    International Nuclear Information System (INIS)

    A detailed study of the light charged particles (mainly protons and alpha particles) has been undertaken in coincidence with the main fragments from DIC in the reaction 280 MeV 40Ar + 58Ni. This study is divided in three sections. The first one is a quick survey of the preexisting data on the 40Ar + 58Ni that are relevant to this particular experiment. The second one deals mainly with the origin of the light charged particles as it can be deduced from the p, α-fragments coincidence experiment. Finally, the third section is devoted to the tangential friction aspects. The results of the out-of-plane distributions of the α-particles are presented and they are discussed in term of the extreme sticking limit

  5. MHD flow of a micro-polar fluid between two parallel plates rotating about two non-coincident axes under variable surface charges

    International Nuclear Information System (INIS)

    This paper presents the investigation of the flow of a micropolar fluid between two parallel plates rotating about two non-coincident axes when the upper surface is acted upon by an electric field and a magnetic field is applied perpendicular to the flow. Expressions for the velocity and microrotation have been obtained. The effects of the rotation of the plates in the presence of surface charges and magnetic field have been discussed in detail. (author). 5 refs., 11 figs

  6. Two-pulse laser control for selective photofragment orientation

    DEFF Research Database (Denmark)

    Machholm, Mette; Henriksen, Niels Engholm

    1999-01-01

    The nuclear wave packet dynamics in the potential well of a bound molecule can be controlled by an intense infrared (IR)-laser pulse. The phase of the nuclear wave packet motion is shown to depend on the phase of the laser field and the initial orientation of the molecule. We demonstrate, for...... diatomic heteronuclear molecules, that these spatial effects can be used to control the angular distribution of photofragments by selective dissociation of molecules with a given initial orientation from a sample of randomly oriented molecules. (C) 1999 American Institute of Physics. [S0021-9606(99)01131-9]....

  7. Photofragment Translational Spectroscopy of Propargyl Radicals at 248 nm

    Energy Technology Data Exchange (ETDEWEB)

    Goncher, S.J.; Moore, D.T.; Sveum, N.E.; Neumark, D.M.

    2007-12-21

    The photodissociation of propargyl radical, C{sub 3}H{sub 3}, and its perdeuterated isotopolog was investigated using photofragment translational spectroscopy. Propargyl radicals were produced by 193 nm photolysis of allene entrained in a molecular beam expansion, and then photodissociated at 248 nm. photofragment time-of-flight spectra were measured at a series of laboratory angles using electron impact ionization coupled to a mass spectrometer. Data for ion masses corresponding to C{sub 3}H{sub 2}{sup +}, C{sub 3}H{sup +}, C{sub 3}{sup +}, and the analogous deuterated species show that both H and H{sub 2} loss occur. The translational energy distributions for these processes have average values = 5.7 and 15.9 kcal/mol, respectively, and are consistent with dissociation on the ground state following internal conversion, with no exit barrier for H loss but a tight transition state for H{sub 2} loss. The translational energy distribution for H atom loss is similar to that in previous work on propargyl in which the H atom, rather than the heavy fragment, was detected. The branching ratio for H loss/H{sub 2} loss was determined to be 97.6/2.4 {+-} 1.2, in good agreement with RRKM results.

  8. Photofragment translational spectroscopy of three body dissociations and free radicals

    Energy Technology Data Exchange (ETDEWEB)

    North, S.W.

    1995-04-01

    This dissertation describes several three-body dissociations and the photodissociation of methyl radicals studied using photofragment translational spectroscopy. The first chapter provides an introduction to three body dissociation, examines current experimental methodology, and includes a discussion on the treatment of photofragment translational spectroscopy data arising from three-body fragmentation. The ultraviolet photodissociation of azomethane into two methyl radicals and nitrogen is discussed in chapter 2. Chapter 3 describes the photodissociation of acetone at 248 nm and 193 nm. At 248 nm the translational energy release from the initial C-C bond cleavage matches the exit barrier height and a comparison with results at 266 nm suggests that is invariant to the available energy. A fraction of the nascent CH{sub 3}CO radicals spontaneously dissociate following rotational averaging. The for the second C-C bond cleavage also matches the exit barrier height. At 193 nm the experimental data can be successfully fit assuming that the dynamics are analogous to those at 248 nm. A simplified model of energy partitioning which adequately describes the experimental results is discussed. Experiments on acetyl halides provide additional evidence to support the proposed acetone dissociation mechanism. A value of 17.0{+-}1.0 kcal/mole for the barrier height, CH{sub 3}CO decomposition has been determined. The photodissociation of methyl radical at 193 nm and 212.8 nm is discussed in the chapter 5. The formation of CH{sub 2} ({sup 1}A{sub l}) and H ({sup 2}S) was the only single photon dissociation pathway observed at both wavelengths.

  9. Importance of vacancy cascades in argon recoil-ion charge-state distributions accompanied by coincident projectile-electron capture and loss

    International Nuclear Information System (INIS)

    Argon recoil-ion charge-state distributions produced by beams of 0.7-MeV/u Cl/sup 5+,8+,10+/ have been measured by time-of-flight (TOF) techniques in coincidence with single- and double-charge-changed projectiles. In an essential improvement to the usual multinomial description of ionization in the independent-electron-ejection model, we find that inclusion of one (two) Auger vacancy cascades significantly alters the description of the recoil-ion spectra corresponding to single (double) capture. The single- and double-projectile-electron loss and capture spectra strongly resemble each other, suggesting that loss of one or two projectile electrons is closely associated with loss of one or two target L electrons, respectively. These conclusions are consistent with impact parameters inferred from determinations of mean recoil energy

  10. Momentum imaging of photofragments and photoelectrons using fast ion beams

    International Nuclear Information System (INIS)

    Momentum imaging of photofragments and photoelectrons using fast ion beams - Within the framework of this thesis a method for break-up channel specific detection of the photoelectrons from photon-induced dissociation processes of fast moving molecular ion has been established. For this purpose, a novel saddlepoint electron spectrometer was commissioned while investigating the photodetachment dynamics on a fast moving beam of oxygen anions. For a complete detection of all outgoing reaction products emerging from the photolysis of small water clusters (H2O)nH+(n≤3) in the wavelength range of 13.5-40 nm a new fragment analyzing system has been developed and in combination with the novel saddle-point spectrometer applied, to investigate the dissociative photoionization of the hydronium (H3O+) and the Zundel ion (H5O2+). In case of the hydronium ion, a binary H2O++H+ and two three-body channels OH++2H+, OH++H++H have been identified to be initiated by outer valence vacancies, where the binary channel is mainly triggered by the ionization of the 3a1 orbital and the three-body channels follow ionization from the 1e orbital. The photolysis of H5O2+ is found to proceed via five prominent pathways, where for a large number of processes the hydronium ion is split off as a stable structural unit. Also here, the investigation of the photoelectron spectra revealed the prominent dissociation pathways to be initiated by outer valence vacancies.

  11. An investigation of polarized atomic photofragments using the ion imaging technique

    Energy Technology Data Exchange (ETDEWEB)

    Bracker, A.S.

    1997-12-01

    This thesis describes measurement and analysis of the recoil angle dependence of atomic photofragment polarization (atomic v-J correlation). This property provides information on the electronic rearrangement which occurs during molecular photodissociation. Chapter 1 introduces concepts of photofragment vector correlations and reviews experimental and theoretical progress in this area. Chapter 2 described the photofragment ion imaging technique, which the author has used to study the atomic v-J correlation in chlorine and ozone dissociation. Chapter 3 outlines a method for isolating and describing the contribution to the image signal which is due exclusively to angular momentum alignment. Ion imaging results are presented and discussed in Chapter 4. Chapter 5 discusses a different set of experiments on the three-fragment dissociation of azomethane. 122 refs.

  12. Enhanced sensitivity in H photofragment detection by two-color reduced-Doppler ion imaging

    Energy Technology Data Exchange (ETDEWEB)

    Epshtein, Michael; Portnov, Alexander; Kupfer, Rotem; Rosenwaks, Salman; Bar, Ilana, E-mail: ibar@bgu.ac.il [Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

    2013-11-14

    Two-color reduced-Doppler (TCRD) and one-color velocity map imaging (VMI) were used for probing H atom photofragments resulting from the ∼243.1 nm photodissociation of pyrrole. The velocity components of the H photofragments were probed by employing two counterpropagating beams at close and fixed wavelengths of 243.15 and 243.12 nm in TCRD and a single beam at ∼243.1 nm, scanned across the Doppler profile in VMI. The TCRD imaging enabled probing of the entire velocity distribution in a single pulse, resulting in enhanced ionization efficiency, as well as improved sensitivity and signal-to-noise ratio. These advantages were utilized for studying the pyrrole photodissociation at ∼243.1 and 225 nm, where the latter wavelength provided only a slight increase in the H yield over the self-signal from the probe beams. The TCRD imaging enabled obtaining high quality H{sup +} images, even for the low H photofragment yields formed in the 225 nm photolysis process, and allowed determining the velocity distributions and anisotropy parameters and getting insight into pyrrole photodissociation.

  13. A new tandem mass spectrometer for photofragment spectroscopy of cold, gas-phase molecular ions

    International Nuclear Information System (INIS)

    We present here the design of a new tandem mass spectrometer that combines an electrospray ion source with a cryogenically cooled ion trap for spectroscopic studies of cold, gas-phase ions. The ability to generate large ions in the gas phase without fragmentation, cool them to ∼10 K in an ion trap, and perform photofragment spectroscopy opens up new possibilities for spectroscopic characterization of large biomolecular ions. The incorporation of an ion funnel, together with a number of small enhancements, significantly improves the sensitivity, signal stability, and ease of use compared with the previous instrument built in our laboratory.

  14. Double coincidence matrix

    International Nuclear Information System (INIS)

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

  15. Coincidence and modality

    OpenAIRE

    Kang, Li

    2011-01-01

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

  16. Unravelling the role of quantum interference in the weak-field laser phase modulation control of photofragment distributions

    DEFF Research Database (Denmark)

    García-Vela, Alberto; Henriksen, Niels Engholm

    2016-01-01

    The role played by quantum interference in the laser phase modulation coherent control of photofragment distributions in the weak-field regime is investigated in detail in this work. The specific application involves realistic wave packet calculations of the transient vibrational populations of t...

  17. Experimental study of the light charged particles emitted in coincidence with the main fragments from D.I.C. in the 40Ar (280 MeV) + 58Ni system

    International Nuclear Information System (INIS)

    The light charged particles emitted in coincidence with the main fragments from deep inelastic collisions in the 40Ar (280 MeV) + 58Ni have been studied. Both radial (in the reaction plane) and azimuthal angular distributions have been measured. For very asymmetric splitting, the radial angular distribution of the α particles shows two components one of which could be attributed to statistical evaporation by the heavy partner of the detected light fragment. The azimuthal distribution of that component clearly indicates a strong alignment of the spin of the emitting fragment with the orbital angular momentum and a preference for the 'sticking' limit. For symmetric splitting, some α particle energy spectra could not be explained in terms of statistical evaporation by either of the two main fragments. (orig.)

  18. Off-resonant vibrational excitation: Orientational dependence and spatial control of photofragments

    DEFF Research Database (Denmark)

    Machholm, Mette; Henriksen, Niels Engholm

    2000-01-01

    randomly oriented heteronuclear diatomic molecules can be obtained under simultaneous irradiation by a resonant and an off-resonant intense IR laser pulse: Molecules with one initial orientation will be vibrationally excited, while those with the opposite orientation will be at rest. The orientation......Off-resonant and resonant vibrational excitation with short intense infrared (IR) laser pulses creates localized oscillating wave packets, but differs by the efficiency of the excitation and surprisingly by the orientational dependence. Orientational selectivity of the vibrational excitation of......-dependent response to the IR fields is due to the anharmonicity of the potential. A subsequent ultraviolet laser pulse in resonance at the outer turning point of the vibrational motion can then dissociate the oscillating molecules, all with the same orientation, leading to spatial control of the photofragment...

  19. Imaging with coincidence detectors

    International Nuclear Information System (INIS)

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

  20. A β - γ coincidence

    International Nuclear Information System (INIS)

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

  1. Experiments using coincidence methods

    International Nuclear Information System (INIS)

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

  2. The parity-adapted basis set in the formulation of the photofragment angular momentum polarization problem: The role of the Coriolis interaction

    International Nuclear Information System (INIS)

    We present a theoretical framework for calculating the recoil-angle dependence of the photofragment angular momentum polarization taking into account both radial and Coriolis nonadiabatic interactions in the diatomic/linear photodissociating molecules. The parity-adapted representation of the total molecular wave function has been used throughout the paper. The obtained full quantum-mechanical expressions for the photofragment state multipoles have been simplified by using the semiclassical approximation in the high-J limit and then analyzed for the cases of direct photodissociation and slow predissociation in terms of the anisotropy parameters. In both cases, each anisotropy parameter can be presented as a linear combination of the generalized dynamical functions fK(q,q',q-tilde,q-tilde') of the rank K representing contribution from different dissociation mechanisms including possible radial and Coriolis nonadiabatic transitions, coherent effects, and the rotation of the recoil axis. In the absence of the Coriolis interactions, the obtained results are equivalent to the earlier published ones. The angle-recoil dependence of the photofragment state multipoles for an arbitrary photolysis reaction is derived. As shown, the polarization of the photofragments in the photolysis of a diatomic or a polyatomic molecule can be described in terms of the anisotropy parameters irrespective of the photodissociation mechanism

  3. Unravelling the role of quantum interference in the weak-field laser phase modulation control of photofragment distributions.

    Science.gov (United States)

    García-Vela, Alberto; Henriksen, Niels E

    2016-02-14

    The role played by quantum interference in the laser phase modulation coherent control of photofragment distributions in the weak-field regime is investigated in detail in this work. The specific application involves realistic wave packet calculations of the transient vibrational populations of the Br2(B,vf) fragment produced upon predissociation of the Ne-Br2(B) complex, which is excited to a superposition of overlapping resonance states using different fixed bandwidth pulses where the linear chirps are varied. The postpulse transient phase modulation effects observed on fragment populations for a long time window are explained in terms of the mechanism of interference between overlapping resonances. A detailed description of how the interference mechanism affects the magnitude and the time window of the phase control effects is also provided. In the light of the results, the conditions to maximize phase modulation control on fragment distributions are discussed. PMID:26799495

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

    OpenAIRE

    Johnson, Philip L F; Hellmann, Ines

    2011-01-01

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

  5. Light charged particle and neutron velocity spectra in coincidence with projectile fragments in the reaction sup 4 sup 0 Ar(44 A MeV)+ sup 2 sup 7 Al

    CERN Document Server

    Lanzanò, G; Geraci, M; Pagano, A; Aiello, S; Cunsolo, A; Fonte, R; Foti, A; Sperduto, M L; Volant, C; Charvet, J L; Dayras, R; Legrain, R

    2001-01-01

    We present a three source analysis of velocity spectra of light charged particles (LCP) and neutrons emitted in the reaction sup 4 sup 0 Ar+ sup 2 sup 7 Al at 44 A MeV. The light particle (LP) velocity spectra are studied as a function of the detection angle (1.5 deg. charge of the forward detected projectile-like fragment (PLF). The temperature parameter, the velocity and the intensity of each source are extracted as a function of the PLF charge. While the temperature parameters for PLF and target-like fragments (TLF) are very similar and show a dependence on the PLF charge, the temperature parameter for the intermediate source is approximately 15 MeV, independent of the PLF charge. Comparison with temperature values extracted from double isotopic ratios, shows an agreement only between the temperature values extracted from formula involving sup 3 He, sup 4 He, d, t ratios and the PLF proton temperature parameter. The characteristics of the PLF sources are derived. Present ...

  6. COINCIDENCE PROBLEMS FOR GENERALIZED CONTRACTIONS

    Directory of Open Access Journals (Sweden)

    Jesús Garcia Falset

    2014-03-01

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

  7. Video Histories, Memories, and Coincidences

    DEFF Research Database (Denmark)

    Kacunko, Slavko

    2012-01-01

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

  8. Photofragment imaging study of the CH2CCH2OH radical intermediate of the OH+allene reaction

    International Nuclear Information System (INIS)

    These velocity map imaging experiments characterize the photolytic generation of one of the two radical intermediates formed when OH reacts via an addition mechanism with allene. The CH2CCH2OH radical intermediate is generated photolytically from the photodissociation of 2-chloro-2-propen-1-ol at 193 nm. Detecting the Cl atoms using [2+1] resonance-enhanced multiphoton ionization evidences an isotropic angular distribution for the Cl+CH2CCH2OH photofragments, a spin-orbit branching ratio for Cl(2P1/2):Cl(2P3/2) of 0.28, and a bimodal recoil kinetic energy distribution. Conservation of momentum and energy allows us to determine from this data the internal energy distribution of the nascent CH2CCH2OH radical cofragment. To assess the possible subsequent decomposition pathways of this highly vibrationally excited radical intermediate, we include electronic structure calculations at the G3//B3LYP level of theory. They predict the isomerization and dissociation transition states en route from the initial CH2CCH2OH radical intermediate to the three most important product channels for the OH+allene reaction expected from this radical intermediate: formaldehyde+C2H3, H+acrolein, and ethene+CHO. We also calculate the intermediates and transition states en route from the other radical adduct, formed by addition of the OH to the center carbon of allene, to the ketene+CH3 product channel. We compare our results to a previous theoretical study of the O+allyl reaction conducted at the CBS-QB3 level of theory, as the two reactions include several common intermediates

  9. Combining attosecond XUV pulses with coincidence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-10-15

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

  10. Radioactivity determination by coincidence counting

    International Nuclear Information System (INIS)

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

  11. Dissociation dynamics of highly excited molecules produced by charge exchange: Two-body dynamics of CH5 and three-body dynamics of sym-triazine

    International Nuclear Information System (INIS)

    Translational spectroscopy and coincidence detection of the neutral photofragments have been used to observe the dissociation dynamics of highly excited neutrals produced by charge exchange between keV cation beams with Cs, and the results from two novel systems are presented. CH5 is formed slightly above the 3s Rydberg level and dissociates into two possible fragmentation channels, H loss and H2 loss. The kinetic energy release distributions of the two products are presented and the branching ratio between the two is found to be 11.4 ± 1.5 : 1 with the H loss being the dominant channel. Production of the highly symmetric azabenzene sym-triazine in its 3s Rydberg state has been shown to induce dissociation to 3 HCN(Σ+). Examination of momentum correlation in the dissociation products shows that this dissociation occurs by two distinct mechanisms. Evidence from Monte Carlo simulations suggest a sequential mechanism occurs creating products accompanied by a kinetic energy release of ∼1.5-5 eV. A symmetric concerted mechanism is also observed and is associated with products receiving a 2-4 eV kinetic energy release.

  12. Coincident photoelectron spectroscopy on superconductors

    International Nuclear Information System (INIS)

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

  13. Artifacts in digital coincidence timing.

    Science.gov (United States)

    Moses, W W; Peng, Q

    2014-11-01

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

  14. Artifacts in digital coincidence timing

    Science.gov (United States)

    Moses, W. W.; Peng, Q.

    2014-11-01

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

  15. Surface underground coincidences at the Soudan mine

    International Nuclear Information System (INIS)

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

  16. 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.

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

    Science.gov (United States)

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

    2016-05-01

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

  18. Light particle coincidences with gross structure in energy spectra from the 40Ca+40Ca collision

    International Nuclear Information System (INIS)

    Angular correlations between light charged particles and heavy ion fragments from the 40Ca + 40Ca collision have been investigated. The high excitation energy structure previously observed in inclusive experiments is strongly populated in coincidence with protons for calcium and potassium fragments, with alphas for argon fragments. Particles emitted in coincidence with the structure are strongly focused and have a velocity close to the velocity of the beam, whereas the yield of evaporation decay is very small

  19. Electron coincidence experiments in atomic physics

    International Nuclear Information System (INIS)

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

  20. Perturbative corrections to photon coincidence spectroscopy

    OpenAIRE

    Horvath, L.; Sanders, B. C.

    2000-01-01

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

  1. Simulation of triple coincidences in PET

    International Nuclear Information System (INIS)

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

  2. UV photodesorption of methanol in pure and CO-rich ices: desorption rates of the intact molecule and of the photofragments

    CERN Document Server

    Bertin, Mathieu; Doronin, Mikhail; Philippe, Laurent; Jeseck, Pascal; Litgerink, Niels; Linnartz, Harold; Michaut, Xavier; Fillion, Jean-Hugues

    2016-01-01

    Wavelength dependent photodesorption rates have been determined using synchrotron radiation, for condensed pure and mixed methanol ice in the 7 -- 14 eV range. The VUV photodesorption of intact methanol molecules from pure methanol ices is found to be of the order of 10$^{-5}$ molecules/photon, that is two orders of magnitude below what is generally used in astrochemical models. This rate gets even lower ($<$ 10$^{-6}$ molecules/photon) when the methanol is mixed with CO molecules in the ices. This is consistent with a picture in which photodissociation and recombination processes are at the origin of intact methanol desorption from pure CH$_3$OH ices. Such low rates are explained by the fact that the overall photodesorption process is dominated by the desorption of the photofragments CO, CH$_3$, OH, H$_2$CO and CH$_3$O/CH$_2$OH, whose photodesorption rates are given in this study. Our results suggest that the role of the photodesorption as a mechanism to explain the observed gas phase abundances of methan...

  3. Coincidence summing in gamma-ray spectroscopy

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

    van Oirschot, Pim; Lewis, Geraint F

    2014-01-01

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

  5. Coincidence lattices in the hyperbolic plane.

    Science.gov (United States)

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

    2011-01-01

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

  6. Sharp coincidences for absolutely summing multilinear operators

    OpenAIRE

    Pellegrino, Daniel

    2012-01-01

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

  7. Curious numerical coincidence to the Pioneer anomaly

    OpenAIRE

    Ivanescu, Liviu

    2009-01-01

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

  8. Mass spectrometric analysis with cluster projectiles and coincidence counting

    Energy Technology Data Exchange (ETDEWEB)

    Cox, B.D.

    1992-01-01

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

  9. Wardowski conditions to the coincidence problem

    Directory of Open Access Journals (Sweden)

    David eAriza-Ruiz

    2015-08-01

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

  10. Recent progress with digital coincidence counting

    International Nuclear Information System (INIS)

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

  11. Cosmic Coincidences: Investigations for Neutron Background Suppression

    OpenAIRE

    Heimbach, Craig R.

    2007-01-01

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

  12. 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.

  13. Kinematical coincidence method in transfer reactions

    CERN Document Server

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

    2012-01-01

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

  14. Coincidence measurements of FFTF breeder fuel subassemblies

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2016-01-01

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

  16. 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...

  17. Coincidence experiments in desorption mass spectrometry

    Science.gov (United States)

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

    2002-06-01

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

  18. Mass Scales and the Cosmological Coincidences

    Science.gov (United States)

    Landsberg, P. T.

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

  19. Mass scales and the cosmological coincidences

    International Nuclear Information System (INIS)

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

  20. A generalized model for coincidence counting

    International Nuclear Information System (INIS)

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

  1. New insight into dissociative photoionization of N2O at ∼20 eV using threshold photoelectron–photoion coincidence velocity imaging

    International Nuclear Information System (INIS)

    Highlights: • The unknown D2Π state was confessedly identified in threshold photoelectron spectrum of N2O at ∼20 eV. • Kinetic energy distributions of NO+ fragments dissociated from D2Π and C2Σ+ states were observed very similar. • Dissociation mechanisms of N2O+ in D2Π(v2+) and C2Σ+(0,0,0) states were proposed respectively. - Abstract: Dissociative photoionization (DPI) of N2O at ∼20 eV has been reinvestigated with threshold photoelectron–photoion coincidence (TPEPICO) velocity imaging. In threshold photoelectron spectrum, a shoulder peak at 20.045 eV is observed close to the ground vibrational level of C2Σ+ state at 20.100 eV. Through comparing the coincident mass spectra recorded at 20.045 and 20.100 eV, the assignment of the shoulder band is corrected to a vibrational excited D2Π ionic state from the previous conclusions of the vibrationless level of b4Π or hot band of C2Σ+ state. For the dominant photofragment of NO+ at 20.045 eV, TPEPICO time-sliced velocity image is measured to obtain the corresponding total kinetic energy and angular distributions. Interestingly, both the bimodal vibrational population and angular distribution of NO+ fragment from dissociation of N2O+(D2Π) are very similar to those of N2O+(C2Σ+) ions. With the aid of potential energy curves, the DPI mechanisms of N2O via D2Π ionic state at 20.045 eV along the NO+(X1Σ+) + N(2D) and NO+(X1Σ+) + N(2P) dissociation channels are clarified, in which the internal conversion from D2Π to B2Π state is the rate-determined step

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

    International Nuclear Information System (INIS)

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

  3. The model JSR-12 neutron coincidence analyzer

    International Nuclear Information System (INIS)

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

  4. Coincidences and the encounter problem: A formal account

    CERN Document Server

    Dessalles, Jean-Louis J -L

    2011-01-01

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

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

    OpenAIRE

    Larssons, JA; Gill, RD Richard

    2003-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2005-03-01

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

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

    International Nuclear Information System (INIS)

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

  9. Novel Beta-Gamma Coincidence Measurements Using Phoswich Detectors

    International Nuclear Information System (INIS)

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

  10. Coincidence Prompt Gamma-Ray Neutron Activation Analysis

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-11-10

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

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

    International Nuclear Information System (INIS)

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

  12. Recovery and normalization of triple coincidences in PET

    International Nuclear Information System (INIS)

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

  13. 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

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

    Science.gov (United States)

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

    2016-01-01

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

  15. 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.

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  18. Computed neutron coincidence counting applied to passive waste assay

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-11-01

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

  19. Standardization of 18F by digital coincidence counting

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  1. Computed neutron coincidence counting applied to passive waste assay

    International Nuclear Information System (INIS)

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

  2. Multiple-Coincidence Active Neutron Interrogation of Fissionable Materials

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

    Bhattacharya, Angshuman

    2009-01-01

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

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

    CERN Document Server

    Karasev, R N

    2009-01-01

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

  5. Coincidence rotations of the root lattice $A_4$

    CERN Document Server

    Baake, Michael; Heuer, Manuela; Zeiner, Peter

    2007-01-01

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

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

    International Nuclear Information System (INIS)

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

  8. Simultaneous, coincident 2-D ACAR and DBAR using segmented HPGe detectors incorporating sub-pixel interpolation

    Science.gov (United States)

    Williams, Christopher S.; Burggraf, Larry W.; Adamson, Paul E.; Petrosky, James C.; Oxley, Mark E.

    2010-04-01

    A three-dimensional Positron Annihilation Spectrometry System (3D PASS) for determination of 3D electron-positron (e--e+) momentum densities by measuring coincident annihilation photons was designed, constructed and characterized. 3D PASS collects a single data set including correlated photon energies and coincident photon positions which are typically collected separately by two-dimensional angular correlation of annihilation radiation (2D ACAR) and two-detector coincident Doppler broadening of annihilation radiation (CDBAR) spectrometry. 3D PASS is composed of two position-sensitive, high-purity germanium (HPGe) double-sided strip detectors (DSSD(s)) linked together by a 32-channel, 50 MHz digital electronics suite. The DSSDs data were analyzed to determine location of photon detection events using an interpolation method to achieve a spatial resolution less than the 5-mm width of the DSSDs' charge collection strips. The interpolation method relies on measuring a figure-of-merit proportional to the area of the transient charges observed on both strips directly adjacent to the charge collection strip detecting the full charge deposited by the annihilation photon. This sub-pixel resolution, corresponding to the error associated with event location within a sub-pixel was measured for both DSSDs using the approach outlined in Williams et al [1] and was on the order of ± 0.20 mm (± one-standard deviation). As a result of the sub-pixel resolution, the distance between the DSSDs and material sample was reduced by a factor of five compared to what is typically required in 2D ACAR systems was necessary to achieve 0.5-mrad angular resolution. This reduction in the system's footprint decreases attenuation of the annihilation photons in the air between the material sample and the DSSDs and increases the solid angle between the sample and the DSSDs, ultimately resulting in higher system detection efficiency. 3D PASS was characterized in the same manner comparable to state

  9. Simultaneous, coincident 2-D ACAR and DBAR using segmented HPGe detectors incorporating sub-pixel interpolation

    International Nuclear Information System (INIS)

    A three-dimensional Positron Annihilation Spectrometry System (3D PASS) for determination of 3D electron-positron (e--e+) momentum densities by measuring coincident annihilation photons was designed, constructed and characterized. 3D PASS collects a single data set including correlated photon energies and coincident photon positions which are typically collected separately by two-dimensional angular correlation of annihilation radiation (2D ACAR) and two-detector coincident Doppler broadening of annihilation radiation (CDBAR) spectrometry. 3D PASS is composed of two position-sensitive, high-purity germanium (HPGe) double-sided strip detectors (DSSD(s)) linked together by a 32-channel, 50 MHz digital electronics suite. The DSSDs data were analyzed to determine location of photon detection events using an interpolation method to achieve a spatial resolution less than the 5-mm width of the DSSDs' charge collection strips. The interpolation method relies on measuring a figure-of-merit proportional to the area of the transient charges observed on both strips directly adjacent to the charge collection strip detecting the full charge deposited by the annihilation photon. This sub-pixel resolution, corresponding to the error associated with event location within a sub-pixel was measured for both DSSDs using the approach outlined in Williams et al [1] and was on the order of ± 0.20 mm (± one-standard deviation). As a result of the sub-pixel resolution, the distance between the DSSDs and material sample was reduced by a factor of five compared to what is typically required in 2D ACAR systems was necessary to achieve 0.5-mrad angular resolution. This reduction in the system's footprint decreases attenuation of the annihilation photons in the air between the material sample and the DSSDs and increases the solid angle between the sample and the DSSDs, ultimately resulting in higher system detection efficiency. 3D PASS was characterized in the same manner comparable to state

  10. Simultaneous, coincident 2-D ACAR and DBAR using segmented HPGe detectors incorporating sub-pixel interpolation

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Christopher S; Burggraf, Larry W; Petrosky, James C; Oxley, Mark E [Air Force Institute of Technology, AFIT/ENP, 2950 Hobson Way, Wright-Patterson Air Force Base, OH 45433 (United States); Adamson, Paul E, E-mail: christopher.williams@afit.ed [High Power Microwave (HPM) Technologies Branch, HPM Division, Directed Energy Directorate, Air Force Research Laboratory, Kirtland AFB, NM 87117 (United States)

    2010-04-01

    A three-dimensional Positron Annihilation Spectrometry System (3D PASS) for determination of 3D electron-positron (e{sup -}-e{sup +}) momentum densities by measuring coincident annihilation photons was designed, constructed and characterized. 3D PASS collects a single data set including correlated photon energies and coincident photon positions which are typically collected separately by two-dimensional angular correlation of annihilation radiation (2D ACAR) and two-detector coincident Doppler broadening of annihilation radiation (CDBAR) spectrometry. 3D PASS is composed of two position-sensitive, high-purity germanium (HPGe) double-sided strip detectors (DSSD(s)) linked together by a 32-channel, 50 MHz digital electronics suite. The DSSDs data were analyzed to determine location of photon detection events using an interpolation method to achieve a spatial resolution less than the 5-mm width of the DSSDs' charge collection strips. The interpolation method relies on measuring a figure-of-merit proportional to the area of the transient charges observed on both strips directly adjacent to the charge collection strip detecting the full charge deposited by the annihilation photon. This sub-pixel resolution, corresponding to the error associated with event location within a sub-pixel was measured for both DSSDs using the approach outlined in Williams et al [1] and was on the order of {+-} 0.20 mm ({+-} one-standard deviation). As a result of the sub-pixel resolution, the distance between the DSSDs and material sample was reduced by a factor of five compared to what is typically required in 2D ACAR systems was necessary to achieve 0.5-mrad angular resolution. This reduction in the system's footprint decreases attenuation of the annihilation photons in the air between the material sample and the DSSDs and increases the solid angle between the sample and the DSSDs, ultimately resulting in higher system detection efficiency. 3D PASS was characterized in the same

  11. Geometric algorithm for efficient coincident detection of gravitational waves

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

    Capistrano, A J S

    2015-01-01

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

  13. The ZEPLIN-III Anti-Coincidence Veto Detector

    CERN Document Server

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

    2010-01-01

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

  14. Performance of Boron-10 based Neutron Coincidence Counters

    International Nuclear Information System (INIS)

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

  15. 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.

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

    Morozov, V A

    2002-01-01

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

  18. A training and educational tool for neutron coincidence measurements

    International Nuclear Information System (INIS)

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

  19. Automatic classification of gammas-gamma coincidence matrices

    International Nuclear Information System (INIS)

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

  20. Automatic classification of gamma-gamma coincidence matrices

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  2. Data acquisition and processing system for coincidence measurements

    International Nuclear Information System (INIS)

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

  3. Data acquisition and processing system for coincidence measurements

    International Nuclear Information System (INIS)

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

  5. Fractional charges

    International Nuclear Information System (INIS)

    20 years ago fractional charges were imagined to explain values of conductivity in some materials. Recent experiments have proved the existence of charges whose value is the third of the electron charge. This article presents the experimental facts that have led theorists to predict the existence of fractional charges from the motion of quasi-particles in a linear chain of poly-acetylene to the quantum Hall effect. According to the latest theories, fractional charges are neither bosons nor fermions but anyons, they are submitted to an exclusive principle that is less stringent than that for fermions. (A.C.)

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

    CERN Document Server

    Egan, Chas A

    2007-01-01

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

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

    OpenAIRE

    Ketov, Sergei V.

    1998-01-01

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

  8. Chemical application of positron annihilation through triple coincidence measurement

    International Nuclear Information System (INIS)

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

  9. Application of coincidence techniques to fusion product measurements

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  12. Proposed mechanisms for coincidence detection in the auditory brainstem

    Czech Academy of Sciences Publication Activity Database

    Maršálek, Petr; Lánský, Petr

    2005-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Gerald Jungck

    1993-03-01

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

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

    OpenAIRE

    Gerald Jungck

    1993-01-01

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

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

    International Nuclear Information System (INIS)

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

  16. Charged Condensation

    CERN Document Server

    Gabadadze, Gregory

    2008-01-01

    We consider Bose-Einstein condensation of massive electrically charged scalars in a uniform background of charged fermions. We focus on the case when the scalar condensate screens the background charge, while the net charge of the system resides on its boundary surface. A distinctive signature of this substance is that the photon acquires a Lorentz-violating mass in the bulk of the condensate. Due to this mass, the transverse and longitudinal gauge modes propagate with different group velocities. We give qualitative arguments that at high enough densities and low temperatures a charged system of electrons and helium-4 nuclei, if held together by laboratory devices or by force of gravity, can form such a substance. We briefly discuss possible manifestations of the charged condensate in compact astrophysical objects.

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

    CERN Document Server

    Poirier, J; Gress, J; Race, D

    2003-01-01

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

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

    CERN Document Server

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

    2016-01-01

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

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

    International Nuclear Information System (INIS)

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

  20. Data Acquisition System for Electron Energy Loss Coincident Spectrometers

    Institute of Scientific and Technical Information of China (English)

    Zhang Chi; Yu Xiaoqi; Yang Tao

    2005-01-01

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

  1. Coincidence Doppler Broadening of Positron Annihilation Radiation in Fe

    Science.gov (United States)

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

    2013-06-01

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Funck, E.

    1987-01-01

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

  4. Spectroscopy of β--delayed nγ-coincidences

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2012-10-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Al-Azmi, Darwish

    2008-08-01

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

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Fadhlan Kamaruzaman; Amir Akramin Shafie; Yasir M. Mustafah

    2015-01-01

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

  12. Photon–photon coincidence apparatus with position sensitive detectors

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Sheleg, Sergey V; Collins, Gregory B

    2011-12-01

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

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

    OpenAIRE

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

    2011-01-01

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

  16. Elimination of prompt components in delayed coincidence time distributions

    Energy Technology Data Exchange (ETDEWEB)

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

    1988-09-01

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

  17. Coincidence Theorems for Certain Classes of Hybrid Contractions

    Directory of Open Access Journals (Sweden)

    Singh SL

    2010-01-01

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

  18. The 8 Coincidences of Galaxy Photometry - Selection Effects

    Science.gov (United States)

    Disney, M. J.; Phillipps, S.

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

  19. Non-minimal quintessence: Dynamics and coincidence problem

    Indian Academy of Sciences (India)

    Fatimah Shojai; Ali Shojai

    2011-12-01

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

  20. The ZEPLIN-III Anti-Coincidence Veto Detector

    OpenAIRE

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

    2010-01-01

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

  1. Non-minimal Quintessence: Dynamics and coincidence problem

    OpenAIRE

    Shojai, Fatimah; Shojai, Ali

    2011-01-01

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

  2. Kinematics for chicane-beam electron coincidence experiments

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  4. Recent Advances in Digital Coincidence Counting for Radionuclide Metrology

    International Nuclear Information System (INIS)

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

  5. Detector system for the study of low energy heavy ion reactions using kinematic coincidence technique

    International Nuclear Information System (INIS)

    The characteristics and performance of a new detector system developed for the study of low energy heavy ion binary reactions using the kinematic coincidence technique are presented. The detector system has been developed to carry out experiments such as multi-nucleon transfer reactions using the General Purpose Scattering Chamber (GPSC) facility at IUAC [1,2]. The detector system consists of a pair of two-dimensional position sensitive multi wire proportional counter (MWPC) and a ΔE−E gas ionization chamber. Both MWPC have an active area of 5×5 cm2, and provide position signals in horizontal (X) and vertical (Y) plane, and timing signal for time of flight measurements. The main design feature of MWPC is the reduced wire pitch of 0.025 in. (0.635 mm) in all electrodes, giving uniform field and faster charge collection, and usage of 10μm diameter in anode frame which gives higher gains. The position resolution of the detectors was determined to be 0.45 mm FWHM and time resolution was estimated to be 400 ps FWHM. The detector could handle heavy ion count rates exceeding 100 kHz without any break down. The timing and position signals of the detectors are used for kinematic coincidence measurements and subsequent extraction of their mass and angular distributions. The ionization chamber has a conventional transverse field geometry with segmented anode providing multiple ΔE signals for nuclear charge (Z) identification. This article describes systematic study of these detectors in terms of efficiency, count rate handling capability, time, position and energy resolution

  6. The Theory of Electron-Scattering Coincidence Experiments.

    Science.gov (United States)

    Kleppinger, William Earl

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

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

    International Nuclear Information System (INIS)

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

  8. Charge independence and charge symmetry

    CERN Document Server

    Miller, G A; Miller, Gerald A; van Oers, Willem T H

    1994-01-01

    Charge independence and charge symmetry are approximate symmetries of nature, violated by the perturbing effects of the mass difference between up and down quarks and by electromagnetic interactions. The observations of the symmetry breaking effects in nuclear and particle physics and the implications of those effects are reviewed.

  9. Charge independence and charge symmetry

    International Nuclear Information System (INIS)

    Charge independence and charge symmetry are approximate symmetries of nature, violated by the perturbing effects of the mass difference between up and down quarks and by electromagnetic interactions. The observations of the symmetry breaking effects in nuclear and particle physics and the implications of those effects are reviewed. (author). 145 refs., 3 tabs., 11 figs

  10. Luminosity Coincident with Initial Breakdown Pulses in Lightning

    Science.gov (United States)

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

    2012-12-01

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    DiFilippo, Frank P

    2015-10-21

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

  13. 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.

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Holá, L’.

    1997-01-01

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

  16. High-level neutron coincidence counter maintenance manual

    International Nuclear Information System (INIS)

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

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

    Indian Academy of Sciences (India)

    R Palit; S Biswas

    2015-09-01

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

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

    OpenAIRE

    Morgan, Peter

    2008-01-01

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

  19. Charged Leptons

    CERN Document Server

    Albrecht, J; Babu, K; Bernstein, R H; Blum, T; Brown, D N; Casey, B C K; Cheng, C -h; Cirigliano, V; Cohen, A; Deshpande, A; Dukes, E C; Echenard, B; Gaponenko, A; Glenzinski, D; Gonzalez-Alonso, M; Grancagnolo, F; Grossman, Y; Harnik, R; Hitlin, D G; Kiburg, B; Knoepfe, K; Kumar, K; Lim, G; Lu, Z -T; McKeen, D; Miller, J P; Ramsey-Musolf, M; Ray, R; Roberts, B L; Rominsky, M; Semertzidis, Y; Stoeckinger, D; Talman, R; Van De Water, R; Winter, P

    2013-01-01

    This is the report of the Intensity Frontier Charged Lepton Working Group of the 2013 Community Summer Study "Snowmass on the Mississippi", summarizing the current status and future experimental opportunities in muon and tau lepton studies and their sensitivity to new physics. These include searches for charged lepton flavor violation, measurements of magnetic and electric dipole moments, and precision measurements of the decay spectrum and parity-violating asymmetries.

  20. Fast γ-ray coincidence timing using a BGO detector array in a nuclear reaction experiment

    International Nuclear Information System (INIS)

    The (7Li, 7Be) nuclear charge-exchange reaction has been investigated at E(7Li)=350 MeV. Coincidences were measured between the charged 7Be reaction products in the focal plane of a magnetic spectrometer and 430-keV Doppler-shifted γ-rays from the decay in flight of excited 7Be ejectiles. The latter were detected in a compact BGO detector array. Fast timing was used to optimize the separation between prompt and randoms events. The BGO output signals display the statistical distribution of the arrival times of individual photoelectrons from the photocathode in the photomultiplier tubes. A timing resolution of 6.5 ns relative to the accelerator RF was obtained. A simple model was successfully developed to simulate the BGO output signals with a statistical distribution of a predetermined number of photoelectrons modulated by the light output response of the scintillator and the single-photoelectron gain distribution and transit time through the photomultiplier tube. It is concluded that the timing resolution is primarily limited by the small number of photoelectrons. ((orig.))

  1. X-Rays Emitted in Coincidence with the Fission Of Cf252

    International Nuclear Information System (INIS)

    A possible technique for studying charge distribution in fission is the simultaneous measurement of the kinetic energies of both fragments and the energy of the K-X-rays emitted in coincidence with fission. The two kinetic energies define the masses of the fragments and the X-ray energy defines the atomic number of one fragment. For such a measurement to yield information on charge distribution, it is necessary that the number of vacancies in the K-shell vary slowly with the mass and charge of the fragments. If the vacancies are produced in the fission act itself, it seems likely that this condition is satisfied. X-rays so produced would be emitted within ∼ 10-15 s after fission, If, on the other hand, the vacancies are produced by internal conversion of gamma rays emitted after fission, it is quite possible that the yield of X-rays may vary markedly from one nucleus to the next. Such X-rays would be emitted with lifetimes characteristic of the converted gamma rays - probably at least as long as 10-12 s. We have measured the lifetime of the X-rays emitted in coincidence with fission with a time resolution of ∼ 1 ns. The spectrum of X-rays shows two peaks, one at the proper energy for light fission fragments, the other at the proper energy for heavy fragments. The number of K-X-rays per fission is approximately 0,6. The two peaks fall off in approximately the same manner with increasing time after fission. The apparent mean lifetime is about 1 ns, but the decay curve is complex and does not contain any obvious single component. There is no evidence of an appreciable number of K-X-rays emitted with lifetimes less than about 0.4 ns. Our conclusions from these results are that most, if not all, of the K-vacancies are due to internal conversion but that many different gamma-ray lifetimes appear in the decay curve. Experiments are in progress to measure simultaneously the kinetic energies of the two fragments and the K-X-ray energy. (author)

  2. 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.

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

    CERN Document Server

    Li, Ye

    2016-01-01

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

  4. Search for coincident air showers in the network observation

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  7. Performance of a coincidence based blood activity monitor

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Meng, Xiangying; Huguet, Gemma; Rinzel, John

    2012-08-01

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

  10. Coincidence counting emission tomographic probe: Method and apparatus

    International Nuclear Information System (INIS)

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

  11. Coincidence orientations of grains in rhombohedral and hexagonal materials

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  13. IXO-XMS LVSID Anti-Coincidence Detector

    Science.gov (United States)

    Porter, Scott F.; Kilbourne, Caroline

    2010-01-01

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

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

    International Nuclear Information System (INIS)

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

  15. Positron emission tomography with gamma camera in coincidence mode

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

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

    1999-01-01

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

  18. Sub-wavelength bubble in photon coincidence detection

    CERN Document Server

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

    2013-01-01

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

  19. Novel data evaluation algorithm for Coincident Doppler Broadening Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-06-01

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

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

    CERN Document Server

    Loredo, Thomas J

    2012-01-01

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

  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. 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.

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

    Institute of Scientific and Technical Information of China (English)

    MeiWenhua; YangYixian

    1995-01-01

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

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

    International Nuclear Information System (INIS)

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

  5. Forward-angle 3He(e,e'π+-) coincident electroproduction and the search for Δ's in the ground state of 3He

    International Nuclear Information System (INIS)

    Forward-angle coincident electroproduction cross sections of charged pions from 3He have been measured at the cw electron accelerator MAMI. The overall features of the data are reproduced in terms of a microscopic model, including pole terms, final state rescattering and produced and preformed Δ resonances. Separation of the cross section into its longitudinal and transverse parts was performed for the first time. (K.A.)

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

    International Nuclear Information System (INIS)

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

  7. Charge transport by holographic Fermi surfaces

    CERN Document Server

    Faulkner, Thomas; Liu, Hong; McGreevy, John; Vegh, David

    2013-01-01

    We compute the contribution to the conductivity from holographic Fermi surfaces obtained from probe fermions in an AdS charged black hole. This requires calculating a certain part of the one-loop correction to a vector propagator on the charged black hole geometry. We find that the current dissipation is as efficient as possible and the transport lifetime coincides with the single-particle lifetime. In particular, in the case where the spectral density is that of a marginal Fermi liquid, the resistivity is linear in temperature.

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

    International Nuclear Information System (INIS)

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

  9. Black diholes with unbalanced magnetic charges

    CERN Document Server

    Liang, Y C; Teo, Edward

    2001-01-01

    We present a technique that can be used to generate a static, axisymmetric solution of the Einstein-Maxwell-Dilaton equations from a stationary, axisymmetric solution of the vacuum Einstein equations. Starting from the Kerr solution, Davidson and Gedalin have previously made use of this technique to obtain a pair of oppositely charged, extremal dilatonic black holes, known as a black dihole. In this paper, we shall instead start from the Kerr-NUT solution. It will be shown that the new solution can also be interpreted as a dihole, but with the black holes carrying unbalanced magnetic charges. The effect of the NUT-parameter is to introduce a net magnetic charge into the system. Finally, we uplift our solution to ten dimensions to describe a system consisting of D6 and anti-D6-branes with unbalanced charges. The limit in which they coincide agrees with a solution recently derived by Brax et al..

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

    CERN Document Server

    Shaw, Douglas J

    2010-01-01

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

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

    Science.gov (United States)

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

    2013-06-01

    Electrical synapses have been shown to be important for enabling and detecting neuronal synchrony in both vertebrates and invertebrates. Hub-and-spoke circuits, in which a central hub neuron is electrically coupled to several input neurons, are an overrepresented motif in the C. elegans nervous system and may represent a conserved functional unit. The functional relevance of this configuration has been demonstrated for circuits mediating aggregation behavior and nose touch perception. Modeling approaches have been useful for understanding structurally and dynamically more complex electrical circuits. Therefore, we formulated a simple analytical model with minimal assumptions to obtain insight into the properties of the hub-and-spoke microcircuit motif. A key prediction of the model is that an active input neuron should facilitate activity throughout the network, whereas an inactive input should suppress network activity through shunting; this prediction was supported by cell ablation and in vivo neuroimaging experiments in the C. elegans nose touch circuit. Thus, the hub-and-spoke architecture may implement an analog coincidence detector enabling distinct responses to distributed and localized patterns of sensory input. PMID:23707432

  12. Coincidence ion imaging with a fast frame camera

    International Nuclear Information System (INIS)

    A new time- and position-sensitive particle detection system based on a fast frame CMOS (complementary metal-oxide semiconductors) camera is developed for coincidence ion imaging. The system is composed of four major components: a conventional microchannel plate/phosphor screen ion imager, a fast frame CMOS camera, a single anode photomultiplier tube (PMT), and a high-speed digitizer. The system collects the positional information of ions from a fast frame camera through real-time centroiding while the arrival times are obtained from the timing signal of a PMT processed by a high-speed digitizer. Multi-hit capability is achieved by correlating the intensity of ion spots on each camera frame with the peak heights on the corresponding time-of-flight spectrum of a PMT. Efficient computer algorithms are developed to process camera frames and digitizer traces in real-time at 1 kHz laser repetition rate. We demonstrate the capability of this system by detecting a momentum-matched co-fragments pair (methyl and iodine cations) produced from strong field dissociative double ionization of methyl iodide

  13. Super sub-wavelength patterns in photon coincidence detection

    Science.gov (United States)

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

    2014-02-01

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

  14. A 900-channel coincidence pulse-amplitude analyser

    International Nuclear Information System (INIS)

    An analyser designed for correlation studies of pulse-height distributions from two scintillation counters is described. The analyser consists of two separate transistorized units; a dual-channel analogue-to-digital encoder and a 900-channel, 216-per-channel capacity ferrite-core store. The display and control unit for the instrument is separate and can be situated away from the analyser. The analysis mode of operation for coincident pulses on the A and B inputs of the encoder can be selected to be 30 by 30, 100 by 9 or 300 channels by 3 distributions. In the last two modes the base lines and the widths of the pulse-amplitude ''windows'' on distribution A can be selected by the operator. With 100 channels for pulse-amplitude analysis, eight ''windows'' in distribution A define eight groups of 100 channels for the B distributions. In this case we have, in effect, one 100-channel analyser for distribution A and eight separate 100-channel analysers to which B can be routed. A description of the basic circuits of the encoder and the logic of the store and display units is given. (author)

  15. Dubin-Johnson syndrome coinciding with colon cancer and atherosclerosis

    Directory of Open Access Journals (Sweden)

    Eva Sticova

    2013-01-01

    Full Text Available Hyperbilirubinemia has been presumed to prevent the process of atherogenesis and cancerogenesis mainly by decreasing oxidative stress. Dubin-Johnson syndrome is a rare, autosomal recessive, inherited disorder characterized by biphasic, predominantly conjugated hyperbilirubinemia with no progression to end-stage liver disease. The molecular basis in Dubin-Johnson syndrome is absence or deficiency of human canalicular multispecific organic anion transporter MRP2/cMOAT caused by homozygous or compound heterozygous mutation(s in ABCC2 located on chromosome 10q24. Clinical onset of the syndrome is most often seen in the late teens or early adulthood. In this report, we describe a case of previously unrecognized Dubin-Johnson syndrome caused by two novel pathogenic mutations (c.2360_2366delCCCTGTC and c.3258+1G>A, coinciding with cholestatic liver disease in an 82-year-old male patient. The patient, suffering from advanced atherosclerosis with serious involvement of coronary arteries, developed colorectal cancer with nodal metastases. The subsequent findings do not support the protective role of Dubin-Johnson type hyperbilirubinemia.

  16. Potential Mars 2001 Sites Coincident with Magnetic Anomalies

    Science.gov (United States)

    Gilmore, M. S.

    1999-01-01

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

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

    Science.gov (United States)

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

    2016-06-21

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

  18. The Structure of the Cubic Coincident Site Lattice Rotation Group

    Energy Technology Data Exchange (ETDEWEB)

    Reed, B W; Minich, R W; Rudd, R E; Kumar, M

    2004-01-13

    This work is intended to be a mathematical underpinning for the field of grain boundary engineering and its relatives. The interrelationships within the set of rotations producing coincident site lattices in cubic crystals are examined in detail. Besides combining previously established but widely scattered results into a unified context, the present work details newly developed representations of the group structure in terms of strings of generators (based on quaternionic number theory, and including uniqueness proofs and rules for algebraic manipulation) as well as an easily visualized topological network model. Important results that were previously obscure or not universally understood (e.g. the {Sigma} combination rule governing triple junctions) are clarified in these frameworks. The methods also facilitate several general observations, including the very different natures of twin-limited structures in two and three dimensions, the inadequacy of the {Sigma} combination rule to determine valid quadruple nodes, and a curious link between allowable grain boundary assignments and the four-color map theorem. This kind of understanding is essential to the generation of realistic statistical models of grain boundary networks (particularly in twin-dominated systems) and is especially applicable to the field of grain boundary engineering.

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

    International Nuclear Information System (INIS)

    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 Ne2+ 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 Ne2+ (2p4, 3P) 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+ (3s23p43d) 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

  20. Investigation of strong laser field-induced fragmentation dynamics of hydrocarbon molecules using coincidence momentum imaging

    International Nuclear Information System (INIS)

    The thesis at hand deals with the strong laser field-induced fragmentation of hydrocarbon molecules. During the laser field's action the molecules may become multiply ionized. After the removal of electrons not only the charge density will be redistributed very quickly, also the molecule itself may undergo partly severe structural deformation and may fragment into several parts. Especially the dynamics of protons is of interest since the fragmentation of a molecule can be largely determined by its protons. This proton dynamics bridges the gap between the most fundamental level in molecular dynamics, which is the sub-femtosecond dynamics of the valence electrons, and the rather slow dynamics of the much heavier atoms of a molecule. The experiments were carried out by using the coincidence momentum imaging technique COLTRIMS which allows one to measure the momentum vectors of cations and electrons resulting from the interaction of the laser field with the molecule. From these momentum vectors the induced reaction, for example the fragmentation of the molecule, can be reconstructed. For the experiments laser pulses with intensities in the range of 1013 - 1016 W/cm2 and pulse durations of around 25 fs, delivered by a Ti:Sapphire based laser system, were used. 2-body and 3-boody fragmentation of 1,3-butadiene was investigated. Apart from different fragmentation channels along different fragmentation pathways, hydrogen/proton migration prior to chemical bond breaking was observed. Furthermore, the emission of highly energetic protons emitted from small hydrocarbon molecules was explored. (author)

  1. First coincidences in pre-clinical Compton camera prototype for medical imaging

    International Nuclear Information System (INIS)

    Compton collimated imaging may improve the detection of gamma rays emitted by radioisotopes used in single photon emission computed tomography (SPECT). We present a crude prototype consisting of a single 500 μm thick, 256 pad silicon detector with pad size of 1.4x1.4 mm2, combined with a 15x15x1 cm3 NaI scintillator crystal coupled to a set of 20 photo multipliers. Emphasis is placed on the performance of the silicon detector and the associated read-out electronics, which has so far proved to be the most challenging part of the set-up. Results were obtained using the VATAGP3, 128 channel low-noise self-triggering ASIC as the silicon detector's front-end. The noise distribution (σ) of the spectroscopic outputs gave an equivalent noise charge (ENC) with a mean value of =137 e with a spread of 10 e, corresponding to an energy resolution of 1.15 keV FWHM for the scattered electron energy. Threshold settings above 8.2 keV were required for stable operation of the trigger. Coincident Compton scatter events in both modules were observed for photons emitted by 57Co source with principal gamma ray energies of 122 and 136 keV

  2. Phantom attenuation research of 2 detectors SPECT with coincident

    International Nuclear Information System (INIS)

    Objective: The photons from the body would be attenuated in their intensity by the soft tissue before they reach the detectors. Some of them lost more intensity than others when coming from the deeper body. Attenuation of the photons would distort the image, affect the image quality, and may lead to misdiagnosis. In this research the X-ray and γ-ray were used as transmission resources for accurate assessment of attenuation in each part of the body. The transmission data was used to correct the emission data from the body. Iteration algorithm was used for the reconstruction of attenuation corrected tomography images. Evaluate the efficacy of attenuation correction in duel head hybrid SPECT/coincidence PET systems (SPECT/PET) and SPECT using both the Jaszczak and the myocardial phantoms. Methods: For PET phantom study, the Jaszczak phantom was filled with the aqueous solution of 18F-fluorodeoxyglucose (FDG) and was scanned with two hybrid SPECT/coincidence PET systems respectively (Vertex Plus, Netherlands Philips ADAC Company and Hawkeye, USA GE Company). The PET images were acquired and reconstructed. Results: The 'cold' lesion, which the diameter was less than 12 mm of uncorrected image, could not be identified. But it, after correction, diameter 9 mm, would be recognized clearly, less than 7 mm would not be distinguished. Noncorrected image could only identify 'hot' lesions which the diameter were 9, 12, 14, 18, 22 and 38 mm, while in the corrected image, not only it was much better, but also the 'hot' le-sion of 6 mm was distinguished. In Hawkeye, the same situation, the corrected image of was improved obviously; the disparity of counts between surrounding and deep center less, and the counts in deep center were compensated. There were only 3 round 'cold' lesions could be recognized, the diameter: 14, 18 and 20 mm; all of them which diameter were less than 12 mm could not be distinguished. One in the center was al-most as background, and could not be identified

  3. 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.

  4. 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.

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

    International Nuclear Information System (INIS)

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

  6. Ion charge-resolved branching in decay of inner shell holes in Xe up to 1200 eV

    Science.gov (United States)

    Eland, J. H. D.; Slater, C.; Zagorodskikh, S.; Singh, R.; Andersson, J.; Hult-Roos, A.; Lauer, A.; Squibb, R. J.; Feifel, R.

    2015-10-01

    Using a new multi-electron multi-ion coincidence apparatus and soft x-ray synchrotron radiation we have determined branching ratios to final Xe n+ states with 2 4p-1, 4s-1, 3d-1 and 3p-1 Xe+ hole states. The coincident electron spectra give information on the Auger cascade pathways. We show that by judicious choice of coincident electrons, almost pure single charge states of the final ions can be selected.

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

    CERN Document Server

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

    2013-01-01

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

  8. Elemental PGNAA analysis using gamma-gamma coincidence counting with the library least-squares approach

    Science.gov (United States)

    Metwally, Walid A.; Gardner, Robin P.; Mayo, Charles W.

    2004-01-01

    An accurate method for determining elemental analysis using gamma-gamma coincidence counting is presented. To demonstrate the feasibility of this method for PGNAA, a system of three radioisotopes (Na-24, Co-60 and Cs-134) that emit coincident gamma rays was used. Two HPGe detectors were connected to a system that allowed both singles and coincidences to be collected simultaneously. A known mixture of the three radioisotopes was used and data was deliberately collected at relatively high counting rates to determine the effect of pulse pile-up distortion. The results obtained, with the library least-squares analysis, of both the normal and coincidence counting are presented and compared to the known amounts. The coincidence results are shown to give much better accuracy. It appears that in addition to the expected advantage of reduced background, the coincidence approach is considerably more resistant to pulse pile-up distortion.

  9. Calibration Analyses and Efficiency Studies for the Anti Coincidence Detector on the Fermi Gamma Ray Space Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Kachulis, Chris; /Yale U. /SLAC

    2011-06-22

    The Anti Coincidence Detector (ACD) on the Fermi Gamma Ray Space Telescope provides charged particle rejection for the Large Area Telescope (LAT). We use two calibrations used by the ACD to conduct three studies on the performance of the ACD. We examine the trending of the calibrations to search for damage and find a timescale over which the calibrations can be considered reliable. We also calculated the number of photoelectrons counted by a PMT on the ACD from a normal proton. Third, we calculated the veto efficiencies of the ACD for two different veto settings. The trends of the calibrations exhibited no signs of damage, and indicated timescales of reliability for the calibrations of one to two years. The number of photoelectrons calculated ranged from 5 to 25. Large errors in the effect of the energy spectrum of the charged particles caused these values to have very large errors of around 60 percent. Finally, the veto efficiencies were found to be very high at both veto values, both for charged particles and for the lower energy backsplash spectrum. The Anti Coincidence Detector (ACD) on the Fermi Gamma Ray Space Telescope is a detector system built around the silicon strip tracker on the Large Area Telescope (LAT). The purpose of the ACD is to provide charged particle rejection for the LAT. To do this, the ACD must be calibrated correctly in flight, and must be able to efficiently veto charged particle events while minimizing false vetoes due to 'backsplash' from photons in the calorimeter. There are eleven calibrations used by the ACD. In this paper, we discuss the use of two of these calibrations to preform three studies on the performance of the ACD. The first study examines trending of the calibrations to check for possible hardware degradation. The second study uses the calibrations to explore the efficiency of an on-board hardware veto. The third study uses the calibrations to calculate the number of photoelectrons seen by each PMT when a

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

    International Nuclear Information System (INIS)

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

  11. 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

  12. The coincidence of IgA nephropathy and Fabry disease

    Directory of Open Access Journals (Sweden)

    Maixnerová Dita

    2013-01-01

    Full Text Available Abstract Background IgA nephropathy (IgAN is the most common glomerulonephritis, which may also coexist with other diseases. We present two patients with an unusual coincidence of IgAN and Fabry disease (FD. Case presentation A 26 year-old man underwent a renal biopsy in February 2001. Histopathology showed very advanced IgAN and vascular changes as a result of hypertension. Because of his progressive renal insufficiency the patient began hemodialysis in August 2001. By means of the blood spot test screening method the diagnosis of FD was suspected. Low activity of alpha-galactosidase A in the patient’s plasma and leukocytes and DNA analysis confirmed the diagnosis of FD. Enzyme replacement therapy started in July 2004. Then the patient underwent kidney transplantation in November 2005. Currently, his actual serum creatinine level is 250 μmol/l. Other organ damages included hypertrophic cardiomyopathy, neuropathic pain and febrile crisis. After enzyme replacement therapy, myocardial hypertrophy has stabilized and other symptoms have disappeared. No further progression of the disease has been noted. The other patient, a 30 year-old woman, suffered from long-term hematuria with a good renal function. Recently, proteinuria (2.6 g/day appeared and a renal biopsy was performed. Histopathology showed IgAN with remarkably enlarged podocytes. A combination of IgAN and a high suspicion of FD was diagnosed. Electron microscopy revealed dense deposits in paramesangial areas typical for IgAN and podocytes with inclusive zebra bodies and myelin figures characteristic of FD. FD was confirmed by the decreased alpha-galactosidase A activity in plasma and leukocytes and by DNA and RNA analysis. Enzyme replacement therapy and family screening were initiated. Conclusions Our results emphasize the role of complexity in the process of diagnostic evaluation of kidney biopsy samples. Electron microscopy represents an integral part of histopathology, and genetic

  13. Ion-coincidence momentum imaging of three-body Coulomb explosion of formaldehyde in ultrashort intense laser fields

    International Nuclear Information System (INIS)

    Three-body Coulomb explosion of formaldehyde (H2CO) in intense 7- and 35-fs laser fields (1.3 × 1015 W/cm2) has been investigated by using ion-coincidence momentum imaging technique. Two types of explosion pathways from the triply charged state, H2CO3+ → (i) H+ + H+ + CO+ and (ii) H+ + CH+ + O+, have been identified. It is shown from the momentum correlation of the fragment ions of pathway (i), that the geometrical structure of the molecule is essentially frozen along the H-C-H bending coordinate for the 7-fs case. On the other hand, for a longer pulse duration (35 fs), structural deformation along the C-H stretching and H-C-H bending coordinates is identified, which is ascribed to the nuclear dynamics in the dication states populated within the laser pulse duration

  14. CHARGE Association

    Directory of Open Access Journals (Sweden)

    Semanti Chakraborty

    2012-01-01

    Full Text Available We present here a case of 17-year-old boy from Kolkata presenting with obesity, bilateral gynecomastia, mental retardation, and hypogonadotrophic hypogonadism. The patient weighed 70 kg and was of 153 cm height. Facial asymmetry (unilateral facial palsy, gynecomastia, decreased pubic and axillary hair, small penis, decreased right testicular volume, non-palpable left testis, and right-sided congenital inguinal hernia was present. The patient also had disc coloboma, convergent squint, microcornea, microphthalmia, pseudohypertelorism, low set ears, short neck, and choanalatresia. He had h/o VSD repaired with patch. Laboratory examination revealed haemoglobin 9.9 mg/dl, urea 24 mg/dl, creatinine 0.68 mg/dl. IGF1 77.80 ng/ml (decreased for age, GH <0.05 ng/ml, testosterone 0.25 ng/ml, FSH-0.95 ΅IU/ml, LH 0.60 ΅IU/ml. ACTH, 8:00 A.M cortisol, FT3, FT4, TSH, estradiol, DHEA-S, lipid profile, and LFT was within normal limits. Prolactin was elevated at 38.50 ng/ml. The patient′s karyotype was 46XY. Echocardiography revealed ventricularseptal defect closed with patch, grade 1 aortic regurgitation, and ejection fraction 67%. Ultrasound testis showed small right testis within scrotal sac and undescended left testis within left inguinal canal. CT scan paranasal sinuses revealed choanalatresia and deviation of nasal septum to the right. Sonomammography revealed bilateral proliferation of fibroglandular elements predominantly in subareoalar region of breasts. MRI of brain and pituitary region revealed markedly atrophic pituitary gland parenchyma with preserved infundibulum and hypothalamus and widened suprasellar cistern. The CHARGE association is an increasingly recognized non-random pattern of congenital anomalies comprising of coloboma, heart defect, choanal atresia, retarded growth and development, genital hypoplasia, ear abnormalities, and/or deafness. [1] These anomalies have a higher probability of occurring together. In this report, we have

  15. On coincidence problem and attractor solutions in ELKO dark energy model

    CERN Document Server

    Sadjadi, H Mohseni

    2011-01-01

    We study the critical points of a Universe dominated by ELKO spinor field dark energy and a barotropic matter in an almost general case. The coincidence problem and attractor solutions are discussed and it is shown the coincidence problem can not be alleviated in this model.

  16. Multiple-coincidence of flood waves on the main river and its tributaries

    Science.gov (United States)

    Prohaska, S.; Ilic, A.; Majkic, B.

    2008-11-01

    This paper addresses the definition of multiple coincidences of flood waves on the main river and its tributaries. Contrary to previous studies of partial coincidences of various flood parameters (Prohaska 1999) for the main river and one of its tributaries, this procedure allows for the definition of complex (multiple) coincidences of a single parameter for the main river and several of its tributaries. In particular, coincidence is defined for the major parameter which characterizes a flood (i.e., the flood wave volume). The paper gives a practical example of the analysis of simultaneous flood waves on the Danube and its main tributaries in Serbia: the Tisa and the Sava rivers. The procedure for potential use of the established coincidence functions in applied water management and forecasting is also described in the paper.

  17. Search milli-charged particles at SLAC

    Energy Technology Data Exchange (ETDEWEB)

    Langeveld, W.G.J. [Stanford Univ., CA (United States)

    1997-01-01

    Particles with electric charge q {triple_bond} Qe {le} 10{sup -3} e and masses in the range 1-1000 MeV/c{sup 2} are not excluded by present experiments or by astrophysical or cosmological arguments. A beam dump experiment uniquely suited to the detection of such {open_quotes}milli-charged{close_quotes} particles has been carried out at SLAC, utilizing the short-duration pulses of the SLC electron beam to establish a tight coincidence window for the signal. The detector, a large scintillation counter sensitive to very small energy depositions, provided much greater sensitivity than previous searches. Analysis of the data leads to the exclusion of a substantial portion of the charge-mass plane. In this report, a preliminary mass-dependent upper limit is presented for the charge of milli-charged particles, ranging from Q = 1.7 x 10{sup -5} at milli-charged particle mass 0.1 MeV/c{sup 2} to Q = 9.5 x 10{sup -4} at 100 MeV/c{sup 2}.

  18. Workplace Charging. Charging Up University Campuses

    Energy Technology Data Exchange (ETDEWEB)

    Giles, Carrie [ICF International, Fairfax, VA (United States); Ryder, Carrie [ICF International, Fairfax, VA (United States); Lommele, Stephen [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-03-01

    This case study features the experiences of university partners in the U.S. Department of Energy's (DOE) Workplace Charging Challenge with the installation and management of plug-in electric vehicle (PEV) charging stations.

  19. Relationship of the sensitivity of dual-head coincidence imaging and 18F activity

    International Nuclear Information System (INIS)

    Objective: To evaluate the effects of 18F activity on random coincidence rate and sensitivity in dual-head coincidence imaging. Methods: The chest model was filled with water solution added various 18F activity. The emission tomography imaging was acquired by DST-Xli dual-head SPECT and the imagings were processed with the same reconstruction procedure. Results: The more different between the true and random coincidence, the better imaging quality would be. the difference value varied from small to larger and then gradually went down in 6 consecutive imagings. At 86th min, the difference value reached maximum 8.9 MBq, the single counts rate was 3.65 x 105, the corresponding 18F activity was 17.8 MBq, and the random coincidence rate was 25%. At that time the most positive nodules were displayed with the best imaging quality. The counts rate, random coincidence rate and others had significant linear correlation. The correlation coefficient (R) between the activity X (MBq) and random coincidence rate Y(%) were 0.9974 (R2) and 0.9967 (R2) with P18F activity required; both higher or lower activity could not benefit for the imaging quality. When the random coincidence rate was 25%, the corresponding 18F activity could produced the best imaging sensitivity. (authors)

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

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

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

  2. 18F standardization by means of a 4πβ-γ software coincidence system

    International Nuclear Information System (INIS)

    The standardization of 18F, a positron emitter of short half-life, used in PET (Positron Emission Tomography) by means of a software 4πβ-γ coincidence system is described. The 4πβ-γ coincidence system consists of a gas-flow proportional counter (PC) in 4π geometry operated at 0.1 MPA coupled to a 50 x 50 mm NaI(Tl) crystal. The data collection was made by means of a Software Coincidence System (SCS) developed at the LMN (Nuclear Metrology Laboratory) of the IPEN-CNEN/SP. The extrapolation technique was applied to determine the activity of the solution. (author)

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  5. MULTIPLE IONIZATION PROCESS STUDIED WITH COINCIDENCE TECHNIQUE BETWEEN SLOW RECOIL ION AND PROJECTILE ION IN 42 MeV Arq+—Ar COLLISIONS

    Institute of Scientific and Technical Information of China (English)

    T.Tonuma; T.Matsuo; 等

    1990-01-01

    Slow Ar recoil ion Production cross sections by 42 MeV Ar1+(q=4-14) projectiles were measured using a projectile ion-recoilion coincidence technique in order to provide information on mechanisms of multiple ionization of target atome through pure ionization as well as of that accompaied simultaneously with multiple electron loss or capture of projectiles.The present results suggest that inner-shell electron processes caused through electron transfer into projectiles and also electron ionization by projectiles play a key role in the production of multiply charged recoil ions.

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

    International Nuclear Information System (INIS)

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

  7. Axioms for a local Reidemeister trace in fixed point and coincidence theory on differentiable manifolds

    OpenAIRE

    Staecker, P. Christopher

    2007-01-01

    We give axioms which characterize the local Reidemeister trace for orientable differentiable manifolds. The local Reidemeister trace in fixed point theory is already known, and we provide both uniqueness and existence results for the local Reidemeister trace in coincidence theory.

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-01

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

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

    OpenAIRE

    The LIGO Scientific Collaboration,; the Virgo Collaboration; Abbott, B.; Abbott, R.; Abbott, T.; Abernathy, M.; Acernese, F.; Ackley, K.; ADAMS, C.; Adams, T.; Addesso, P.; Adhikari, R.; Adya, V.; Affeldt, C.; Agathos, M.

    2016-01-01

    We present an archival search for transient gravitational wave bursts in coincidence with 27 single pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO, Virgo and GEO interferometer network. We also discuss a check for gravitational wave signals in coincidence with Parkes Fast Radio Bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short duration radio signals and transient gravitational...

  12. Experimental verification of mathematical efficiency modeling and true coincidence summing correction of the SAGe Well detector

    International Nuclear Information System (INIS)

    The characterization and ray-tracing algorithm in ISOCS/LabSOCS has been extended to calculate full energy peak and total efficiencies for the Small Anode Germanium Well detector. The extension allows for true coincidence summing correction using the standard algorithm in the Genie 2000 software. The accuracy of the full energy peak efficiency calculation and the coincidence summing correction has been experimentally validated to be the same as for non-well detectors. (author)

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

    International Nuclear Information System (INIS)

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

  14. On Approximate Coincidence Point Properties and Their Applications to Fixed Point Theory

    OpenAIRE

    Wei-Shih Du

    2012-01-01

    We first establish some existence results concerning approximate coincidence point properties and approximate fixed point properties for various types of nonlinear contractive maps in the setting of cone metric spaces and general metric spaces. From these results, we present some new coincidence point and fixed point theorems which generalize Berinde-Berinde's fixed point theorem, Mizoguchi-Takahashi's fixed point theorem, and some well-known results in the literature.

  15. Shift Register Clock Rate Effects on Coincidence Collection 50MHz versus 4MHz Comparison Tests

    Energy Technology Data Exchange (ETDEWEB)

    Newell, Matthew R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bourret, Steven C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Swinhoe, Martyn Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-03

    The following report identifies and quantifies the timing differences between the older slower Shift Register Coincidence/Multiplicity modules and today’s modern higher speed devices. Modern high speed Shift Register Coincidence/Multiplicity instruments employ high speed internal clocks that run at frequencies more than ten times the older units, typically 50MHz. These higher speed clocks allow for a finer time resolution when recording input pulses.

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

    Science.gov (United States)

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

    2012-09-01

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

  17. Improvement of software coincidence counting system for standardisation of EC-β+ radionuclides

    International Nuclear Information System (INIS)

    Since 2000 the software coincidence counting (SCC) system has been used for activity standardisation of about 15 radionuclides. Their activities were determined by the efficiency extrapolation method applied to 4π (PC)-γ coincidence. Some standardisations, mainly standardisations of EC-β+ radionuclides, required optimal setting of coincidence parameters, for which new procedures based on “the coincidence to total PC count ratios”, “a multiple gamma window combined from subwindows fractions” and “a source test for PC detection efficiency ” were introduced. The paper summarises the development of SCC system related to findings from detailed analyses of recorded data. These findings are not practically achievable by a conventional approach. - Highlights: ► Improvement of extrapolation method applied to 4π (PC)-γ coincidence. ► New procedures for optimal setting of coincidence parameters. ► Applicable in metrology of radionuclides with complicated decay scheme. ► Mainly for activity standardisation of EC-β+ radionuclides.

  18. An investigation of a coincidence detection system for an all-digital small animal PET scanner

    International Nuclear Information System (INIS)

    Objective: To investigate and design a coincidence detection system for an all-digital small animal PET scanner and evaluate its preliminary performance properties. Methods: This coincidence module adopted a coincidence identification mode based on singles data in list-mode.Using digital signal processing technology, energy calibration, crystal identification, timing alignment and coincidence events extraction were performed on singles data in list-mode. The obtained data could be used for image reconstruction. Results: The 13 × 13 crystal array was well recognized by the position histogram of one lutetium yttrium orthosilicate (LYSO) crystal block. In the coincidence timing histogram of the micro-Derenzo phantom, 1.36 ns full width at half maximum was obtained. The rods with a diameter of 1.2 mm were clearly displayed in the reconstructed image of the micro-Derenzo phantom. Conclusion: The coincidence module can provide satisfactory performance to meet the design needs of an all-digital small animal PET scanner. (authors)

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  1. Charged point particles with magnetic moment in general relativity

    International Nuclear Information System (INIS)

    Halbwachs Lagrangean formalism for the theory of charged point particles with spin (g = 2) is generalized and formulated in General Relativity for particles of arbitrary charge and magnetic moment. Equations are obtained, both corresponding to Frenkel's condition Ssub(μν)Xsup(ν) = 0 and to Nakano's condition Ssub(μν)Psup(ν) = 0. With the later condition the exact equations are highly coupled and non linear. When linearized in the electromagnetic and gravitational fields they coincide with de Groot-Suttorp equations for vanishing gravitational fields and with Dixon-Wald equations in the absence of electromagnetic field. The equations corresponding to Frenkel's condition, when linearized in Ssub(μν), coincide with Papapetrou's and Frenkel's equations in the corresponding limits

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-08-31

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

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

    International Nuclear Information System (INIS)

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

  5. 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

  6. 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

  7. Multistep Charge Method by Charge Arrays

    Science.gov (United States)

    Segami, Go; Kusawake, Hiroaki; Shimizu, Yasuhiro; Iwasa, Minoru; Kibe, Koichi

    2008-09-01

    We studied reduction of the size and weight of the Power Control Unit (PCU). In this study, we specifically examined the weight of the Battery Charge Regulator (BCR), which accounts for half of the PCU weight for a low earth orbit (LEO) satellite. We found a multistep charge method by charge arrays and adopted a similar method for GEO satellites, thereby enabling the BCR reduction. We found the possibility of reducing the size and weight of PCU through more detailed design than that for a conventional PCU.BCRC1R1batterySAPower Control UnitBCRC1R1batterySAPower UnitHowever, this method decreases the state of charge (SOC) of the battery. Battery tests, a battery simulator test, and numerical analysis were used to evaluate the SOC decrease. We also studied effects of this method on the battery lifetime. The multistep charge method by charge arrays enabled charging to the same level of SOC as the conventional constant current/ constant voltage (CC/CV) charge method for a LEO satellite.

  8. 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.

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

    International Nuclear Information System (INIS)

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

  10. 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.

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

    Science.gov (United States)

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

    2016-04-01

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

  12. High-level neutron-coincidence-counter (HLNCC) implementation: assay of the plutonium content of mixed-oxide fuel assemblies

    International Nuclear Information System (INIS)

    The portable High-Level Neutron Coincidence Counter is used to assay the 240Pu-effective loading of a reference mixed-oxide fuel assembly by neutron coincidence counting. We have investigated the effects on the coincidence count rate of the total fuel loading (UO2 + PuO2), the fissile loading, the fuel rod diameter, and the fuel rod pattern. The coincidence count rate per gram of 240Pu-effective per centimeter is primarily dependent on the total fuel loading of the assembly; the higher the loading, the higher the coincidence count rate. Detailed procedures for the assay of mixed-oxide fuel assemblies are developed

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

    International Nuclear Information System (INIS)

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

  14. CoINcIDE: A framework for discovery of patient subtypes across multiple datasets.

    Science.gov (United States)

    Planey, Catherine R; Gevaert, Olivier

    2016-01-01

    Patient disease subtypes have the potential to transform personalized medicine. However, many patient subtypes derived from unsupervised clustering analyses on high-dimensional datasets are not replicable across multiple datasets, limiting their clinical utility. We present CoINcIDE, a novel methodological framework for the discovery of patient subtypes across multiple datasets that requires no between-dataset transformations. We also present a high-quality database collection, curatedBreastData, with over 2,500 breast cancer gene expression samples. We use CoINcIDE to discover novel breast and ovarian cancer subtypes with prognostic significance and novel hypothesized ovarian therapeutic targets across multiple datasets. CoINcIDE and curatedBreastData are available as R packages. PMID:26961683

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-06-11

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

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

    Science.gov (United States)

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

    2004-06-01

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

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

    International Nuclear Information System (INIS)

    The U-235 quantity per lenght of fresh fuel assemblies of the Angra-I first recharge was determined by Neutron Coincidence Collar technique (N.C.C.). This technique is well-founded in fresh fuel assemblies activation by thermal neutrons from AmLi source to generate U-235 fission neutrons. These neutrons are detected by coincidence method in polyethylene structure where 18 He-3 detectors were placed. The coincidence counting results, in active mode (AmLi), showed 0,7% to standard deviation and equal to 1,49% to mass in 1000s of counting. The accuracies of different calibration methods were evaluated and compared. The results showed that the operator declared values are consistent. This evaluation was part of technical-exchange program between Safeguards Laboratory from C.N.E.N. and Los Alamos National Lab., United States. (author)

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

    In addition to the conventional singles mode of operation, the TOKIM system's two Anger-type gamma cameras may be used in the (stationary, 1800 opposition) coincidence mode, making it possible to achieve tomographic imaging with three-dimensional spatial resolution and high detection sensitivity, utilizing β+ emitting radioisotopes. This method, however, suffers from certain inherent limitations. Our efforts during this past year to improve upon the TOKIM imaging capability in the β+ mode have been directed towards the reduction of the limitations by the following means: the removal of out of focal plane image contributions through a computerized iterative correction procedure, coupled with coincidence aperture limitation to achieve uniform sensitivity across a reasonable portion of the detector pair diameter, and the application of Muehllehner's graded filter approach to the TOKIM to increase the ratio of usable coincidence events versus singles count rate

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

    CERN Document Server

    Balpardo, C; Rodrigues, D; Arenillas, P

    2010-01-01

    The nuclide 241Am decays by alpha emission to 237Np. Most of the decays (84.6 %) populate the excited level of 237Np with energy of 59.54 keV. Digital Coincidence Counting was applied to standardize a solution of 241Am by alpha-gamma coincidence counting with efficiency extrapolation. Electronic discrimination was implemented with a pressurized proportional counter and the results were compared with two other independent techniques: Liquid Scintillation Counting using the logical sum of double coincidences in a TDCR array and Defined Solid Angle Counting taking into account activity inhomogeneity in the active deposit. The results show consistency between the three methods within a limit of a 0.3%. An ampoule of this solution will be sent to the International Reference System (SIR) during 2009. Uncertainties were analysed and compared in detail for the three applied methods.

  1. Moisture corrections in neutron coincidence counting of PuO2

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-10-31

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

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

    CERN Document Server

    others,; Abbott, B P; Abbott, R; Abbott, T D; Abernathy, M R; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Adya, V B; Affeldt, C; Agathos, M; Agatsuma, K; Aggarwal, N; Aguiar, O D; Aiello, L; Ain, A; Ajith, P; Allen, B; Allocca, A; Altin, P A; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C C; Areeda, J S; Arnaud, N; Arun, K G; Ascenzi, S; Ashton, G; Ast, M; Aston, S M; Astone, P; Aufmuth, P; Aulbert, C; Babak, S; Bacon, P; Bader, M K M; Baker, P T; Baldaccini, F; Ballardin, G; Ballmer, S W; Barayoga, J C; Barclay, S E; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barta, D; Bartlett, J; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Baune, C; Bavigadda, V; Bazzan, M; Behnke, B; Bejger, M; Bell, A S; Bell, C J; Berger, B K; Bergman, J; Bergmann, G; Berry, C P L; Bersanetti, D; Bertolini, A; Betzwieser, J; Bhagwat, S; Bhandare, R; Bilenko, I A; Billingsley, G; Birch, J; Birney, R; Biscans, S; Bisht, A; Bitossi, M; Biwer, C; Bizouard, M A; Blackburn, J K; Blair, C D; Blair, D G; Blair, R M; Bloemen, S; Bock, O; Bodiya, T P; Boer, M; Bogaert, G; Bogan, C; Bohe, A; Bojtos, P; Bond, C; Bondu, F; Bonnand, R; Boom, B A; Bork, R; Boschi, V; Bose, S; Bouffanais, Y; Bozzi, A; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Brillet, A; Brinkmann, M; Brisson, V; Brockill, P; Brooks, A F; Brown, D A; Brown, D D; Brown, N M; Buchanan, C C; Buikema, A; Bulik, T; Bulten, H J; Buonanno, A; Buskulic, D; Buy, C; Byer, R L; Cadonati, L; Cagnoli, G; Cahillane, C; Bustillo, J Calderón; Callister, T; Calloni, E; Camp, J B; Cannon, K C; Cao, J; Capano, C D; Capocasa, E; Carbognani, F; Caride, S; Diaz, J Casanueva; Casentini, C; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Cella, G; Cepeda, C B; Baiardi, L Cerboni; Cerretani, G; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chamberlin, S J; Chan, M; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, H Y; Chen, Y; Cheng, C; Chincarini, A; Chiummo, A; Cho, H S; Cho, M; Chow, J H; Christensen, N; Chu, Q; Chua, S; Chung, S; Ciani, G; Clara, F; Clark, J A; Cleva, F; Coccia, E; Cohadon, P -F; Colla, A; Collette, C G; Cominsky, L; Constancio, M; Conte, A; Conti, L; Cook, D; Corbitt, T R; Cornish, N; Corsi, A; Cortese, S; Costa, C A; Coughlin, M W; Coughlin, S B; Coulon, J -P; Countryman, S T; Couvares, P; Coward, D M; Cowart, M J; Coyne, D C; Coyne, R; Craig, K; Creighton, J D E; Cripe, J; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Canton, T Dal; Danilishin, S L; D'Antonio, S; Danzmann, K; Darman, N S; Dattilo, V; Dave, I; Daveloza, H P; Davier, M; Davies, G S; Daw, E J; Day, R; DeBra, D; Debreczeni, G; Degallaix, J; De Laurentis, M; Deléglise, S; Del Pozzo, W; Denker, T; Dent, T; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Dhurandhar, S; Díaz, M C; Di Fiore, L; Di Giovanni, M; Di Girolamo, T; Di Lieto, A; Di Pace, S; Di Palma, I; Di Virgilio, A; Dojcinoski, G; Dolique, V; Donovan, F; Dooley, K L; Doravari, S; Douglas, R; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Ducrot, M; Dwyer, S E; Edo, T B; Edwards, M C; Effler, A; Eggenstein, H -B; Ehrens, P; Eichholz, J; Eikenberry, S S; Engels, W; Essick, R C; Etzel, T; Evans, M; Evans, T M; Everett, R; Factourovich, M; Fafone, V; Fair, H; Fairhurst, S; Fan, X; Fang, Q; Farinon, S; Farr, B; Farr, W M; Favata, M; Fays, M; Fehrmann, H; Fejer, M M; Ferrante, I; Ferreira, E C; Ferrini, F; Fidecaro, F; Fiori, I; Fiorucci, D; Fisher, R P; Flaminio, R; Fletcher, M; Fournier, J -D; Frasca, S; Frasconi, F; Frei, Z; Freise, A; Frey, R; Frey, V; Fricke, T T; Fritschel, P; Frolov, V V; Fulda, P; Fyffe, M; Gabbard, H A G; Gair, J R; Gammaitoni, L; Gaonkar, S G; Garufi, F; Gaur, G; Gehrels, N; Gemme, G; Genin, E; Gennai, A; George, J; Gergely, L; Germain, V; Ghosh, Archisman; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gill, K; Glaefke, A; Goetz, E; Goetz, R; Gondan, L; González, G; Castro, J M Gonzalez; Gopakumar, A; Gordon, N A; Gorodetsky, M L; Gossan, S E; Gosselin, M; Gouaty, R; Grado, A; Graef, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greco, G; Green, A C; Groot, P; Grote, H; Grunewald, S; Guidi, G M; Guo, X; Gupta, A; Gupta, M K; Gushwa, K E; Gustafson, E K; Gustafson, R; Hacker, J J; Hall, B R; Hall, E D; Hammond, G; Haney, M; Hanke, M M; Hanks, J; Hanna, C; Hannam, M D; Hanson, J; Hardwick, T; Harms, J; Harry, G M; Harry, I W; Hart, M J; Hartman, M T; Haster, C -J; Haughian, K; Heidmann, A; Heintze, M C; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Hennig, J; Heptonstall, A W; Heurs, M; Hild, S; Hoak, D; Hodge, K A; Hofman, D; Hollitt, S E; Holt, K; Holz, D E; Hopkins, P; Hosken, D J; Hough, J; Houston, E A; Howell, E J; Hu, Y M; Huang, S; Huerta, E A; Huet, D; Hughey, B; Husa, S; Huttner, S H; Huynh-Dinh, T; Idrisy, A; Indik, N; Ingram, D R; Inta, R; Isa, H N; Isac, J -M; Isi, M; Islas, G; Isogai, T; Iyer, B R; Izumi, K; Jacqmin, T; Jang, H; Jani, K; Jaranowski, P; Jawahar, S; Jiménez-Forteza, F; Johnson, W W; Jones, D I; Jones, R; Jonker, R J G; Ju, L; K, Haris; Kalaghatgi, C V; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Karki, S; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, S; Kaur, T; Kawabe, K; Kawazoe, F; Kéfélian, F; Kehl, M S; Keitel, D; Kelley, D B; Kells, W; Kennedy, R; Key, J S; Khalaidovski, A; Khalili, F Y; Khan, I; Khan, S; Khan, Z; Khazanov, E A; Kijbunchoo, N; Kim, Chunglee; Kim, J; Kim, K; Kim, Nam-Gyu; Kim, Namjun; Kim, Y -M; King, E J; King, P J; Kinzel, D L; Kissel, J S; Kleybolte, L; Klimenko, S; Koehlenbeck, S M; Kokeyama, K; Koley, S; Kondrashov, V; Kontos, A; Korobko, M; Korth, W Z; Kowalska, I; Kozak, D B; Kringel, V; Królak, A; Krueger, C; Kuehn, G; Kumar, P; Kuo, L; Kutynia, A; Lackey, B D; Landry, M; Lange, J; Lantz, B; Lasky, P D; Lazzarini, A; Lazzaro, C; Leaci, P; Leavey, S; Lebigot, E O; Lee, C H; Lee, H K; Lee, H M; Lee, K; Lenon, A; Leonardi, M; Leong, J R; Leroy, N; Letendre, N; Levin, Y; Levine, B M; Li, T G F; Libson, A; Littenberg, T B; Lockerbie, N A; Logue, J; Lombardi, A L; Lord, J E; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J D; Lück, H; Lundgren, A P; Luo, J; Lynch, R; Ma, Y; MacDonald, T; Machenschalk, B; MacInnis, M; Macleod, D M; Magaña-Sandoval, F; Magee, R M; Mageswaran, M; Majorana, E; Maksimovic, I; Malvezzi, V; Man, N; Mandic, V; Mangano, V; Mansell, G L; Manske, M; Mantovani, M; Marchesoni, F; Marion, F; Márka, S; Márka, Z; Markosyan, A S; Maros, E; Martelli, F; Martellini, L; Martin, I W; Martin, R M; Martynov, D V; Marx, J N; Mason, K; Masserot, A; Massinger, T J; Masso-Reid, M; Mastrogiovanni, S; Matichard, F; Matone, L; Mavalvala, N; Mazumder, N; Mazzolo, G; McCarthy, R; McClelland, D E; McCormick, S; McGuire, S C; McIntyre, G; McIver, J; McManus, D J; McWilliams, S T; Meacher, D; Meadors, G D; Meidam, J; Melatos, A; Mendell, G; Mendoza-Gandara, D; Mercer, R A; Merilh, E L; Merzougui, M; Meshkov, S; Messenger, C; Messick, C; Metzdorff, R; Meyers, P M; Mezzani, F; Miao, H; Michel, C; Middleton, H; Mikhailov, E E; Milano, L; Miller, A L; Miller, J; Millhouse, M; Minenkov, Y; Ming, J; Mirshekari, S; Mishra, C; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Moggi, A; Mohan, M; Mohapatra, S R P; Montani, M; Moore, B C; Moore, C J; Moraru, D; Moreno, G; Morriss, S R; Mossavi, K; Mours, B; Mow-Lowry, C M; Mueller, C L; Mueller, G; Muir, A W; Mukherjee, Arunava; Mukherjee, D; Mukherjee, S; Mukund, K N; Mullavey, A; Munch, J; Murphy, D J; Murray, P G; Mytidis, A; Nardecchia, I; Naticchioni, L; Nayak, R K; Necula, V; Nedkova, K; Nelemans, G; Neri, M; Neunzert, A; Newton, G; Nguyen, T T; Nielsen, A B; Nissanke, S; Nitz, A; Nocera, F; Nolting, D; Normandin, M E N; Nuttall, L K; Oberling, J; Ochsner, E; O'Dell, J; Oelker, E; Ogin, G H; Oh, J J; Oh, S H; Ohme, F; Oliver, M; Oppermann, P; Oram, Richard J; O'Reilly, B; O'Shaughnessy, R; Ott, C D; Ottaway, D J; Ottens, R S; Overmier, H; Owen, B J; Pai, A; Pai, S A; Palamos, J R; Palashov, O; Palomba, C; Pal-Singh, A; Pan, H; Pankow, C; Pannarale, F; Pant, B C; Paoletti, F; Paoli, A; Papa, M A; Paris, H R; Parker, W; Pascucci, D; Pasqualetti, A; Passaquieti, R; Passuello, D; Patricelli, B; Patrick, Z; Pearlstone, B L; Pedraza, M; Pedurand, R; Pekowsky, L; Pele, A; Penn, S; Pereira, R; Perreca, A; Phelps, M; Piccinni, O J; Pichot, M; Piergiovanni, F; Pierro, V; Pillant, G; Pinard, L; Pinto, I M; Pitkin, M; Pletsch, H J; Poggiani, R; Popolizio, P; Post, A; Powell, J; Prasad, J; Predoi, V; Premachandra, S S; Prestegard, T; Price, L R; Prijatelj, M; Principe, M; Privitera, S; Prodi, G A; Prokhorov, L; Puncken, O; Punturo, M; Puppo, P; Pürrer, M; Qi, H; Qin, J; Quetschke, V; Quintero, E A; Quitzow-James, R; Raab, F J; Rabeling, D S; Radkins, H; Raffai, P; Raja, S; Rakhmanov, M; Rapagnani, P; Raymond, V; Razzano, M; Re, V; Read, J; Reed, C M; Regimbau, T; Rei, L; Reid, S; Reitze, D H; Rew, H; Ricci, F; Riles, K; Robertson, N A; Robie, R; Robinet, F; Rocchi, A; Rolland, L; Rollins, J G; Roma, V J; Romano, J D; Romano, R; Romanov, G; Romie, J H; Rosińska, D; Rowan, S; Rüdiger, A; Ruggi, P; Ryan, K; Sachdev, S; Sadecki, T; Sadeghian, L; Salconi, L; Saleem, M; Salemi, F; Samajdar, A; Sammut, L; Sanchez, E J; Sandberg, V; Sandeen, B; Sanders, J R; Sassolas, B; Sathyaprakash, B S; Saulson, P R; Sauter, O E S; Savage, R L; Sawadsky, A; Schale, P; Schilling, R; Schmidt, J; Schmidt, P; Schnabel, R; Schofield, R M S; Schönbeck, A; Schreiber, E; Schuette, D; Schutz, B F; Scott, J; Scott, S M; Sellers, D; Sentenac, D; Sequino, V; Sergeev, A; Serna, G; Setyawati, Y; Sevigny, A; Shaddock, D A; Shahriar, M S; Shaltev, M; Shao, Z; Shapiro, B; Shawhan, P; Sheperd, A; Shoemaker, D H; Shoemaker, D M; Siellez, K; Siemens, X; Sieniawska, M; Sigg, D; Silva, A D; Simakov, D; Singer, A; Singer, L P; Singh, A; Singh, R; Singhal, A; Sintes, A M; Slagmolen, B J J; Smith, J R; Smith, N D; Smith, R J E; Son, E J; Sorazu, B; Sorrentino, F; Souradeep, T; Srivastava, A K; Staley, A; Steinke, M; Steinlechner, J; Steinlechner, S; Steinmeyer, D; Stephens, B C; Stiles, D; Stone, R; Strain, K A; Straniero, N; Stratta, G; Strauss, N A; Strigin, S; Sturani, R; Stuver, A L; Summerscales, T Z; Sun, L; Sutton, P J; Swinkels, B L; Szczepańczyk, M J; Tacca, M; Talukder, D; Tanner, D B; Tápai, M; Tarabrin, S P; Taracchini, A; Taylor, R; Theeg, T; Thirugnanasambandam, M P; Thomas, E G; Thomas, M; Thomas, P; Thorne, K A; Thrane, E; Tiwari, S; Tiwari, V; Tokmakov, K V; Tomlinson, C; Tonelli, M; Torres, C V; Torrie, C I; Töyrä, D; Travasso, F; Traylor, G; Trifirò, D; Tringali, M C; Trozzo, L; Tse, M; Turconi, M; Tuyenbayev, D; Ugolini, D; Unnikrishnan, C S; Urban, A L; Usman, S A; Vahlbruch, H; Vajente, G; Valdes, G; van Bakel, N; van Beuzekom, M; Brand, J F J van den; Broeck, C Van Den; Vander-Hyde, D C; van der Schaaf, L; van Heijningen, J V; van Veggel, A A; Vardaro, M; Vass, S; Vasúth, M; Vaulin, R; Vecchio, A; Vedovato, G; Veitch, J; Veitch, P J; Venkateswara, K; Verkindt, D; Vetrano, F; Viceré, A; Vinciguerra, S; Vine, D J; Vinet, J -Y; Vitale, S; Vo, T; Vocca, H; Vorvick, C; Voss, D V; Vousden, W D; Vyatchanin, S P; Wade, A R; Wade, L E; Wade, M; Walker, M; Wallace, L; Walsh, S; Wang, G; Wang, H; Wang, M; Wang, X; Wang, Y; Ward, R L; Warner, J; Was, M; Weaver, B; Wei, L -W; Weinert, M; Weinstein, A J; Weiss, R; Welborn, T; Wen, L; Wessels, P; Westphal, T; Wette, K; Whelan, J T; Whitcomb, S E; White, D J; Whiting, B F; Williams, R D; Williamson, A R; Willis, J L; Willke, B; Wimmer, M H; Winkler, W; Wipf, C C; Wittel, H; Woan, G; Worden, J; Wright, J L; Wu, G; Yablon, J; Yam, W; Yamamoto, H; Yancey, C C; Yap, M J; Yu, H; Yvert, M; zny, A Zadro; Zangrando, L; Zanolin, M; Zendri, J -P; Zevin, M; Zhang, F; Zhang, L; Zhang, M; Zhang, Y; Zhao, C; Zhou, M; Zhou, Z; Zhu, X J; Zucker, M E; Zuraw, S E; Zweizig, J; Archibald, A M; Banaszak, S; Berndsen, A; Boyles, J; Cardoso, R F; Chawla, P; Cherry, A; Dartez, L P; Day, D; Epstein, C R; Ford, A J; Flanigan, J; Garcia, A; Hessels, J W T; Hinojosa, J; Jenet, F A; Karako-Argaman, C; Kaspi, V M; Keane, E F; Kondratiev, V I; Kramer, M; Leake, S; Lorimer, D; Lunsford, G; Lynch, R S; Martinez, J G; Mata, A; McLaughlin, M A; McPhee, C A; Penucci, T; Ransom, S; Roberts, M S E; Rohr, M D W; Stairs, I H; Stovall, K; van Leeuwen, J; Walker, A N; Wells, B L

    2016-01-01

    We present an archival search for transient gravitational wave bursts in coincidence with 27 single pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO, Virgo and GEO interferometer network. We also discuss a check for gravitational wave signals in coincidence with Parkes Fast Radio Bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short duration radio signals andtransient gravitational wave emission include starquakes on neutron stars, binary coalescence of neutron stars, and cosmic string cusps. While no evidence for gravitational wave emission in coincidence with these radio transients was found, the current analysis serves as a prototype for similar future searches using more sensitive second generation interferometers.

  4. New method for automatic background subtraction in symmetrized γ - γ coincidence matrices

    International Nuclear Information System (INIS)

    The most widely used technique to establish the level schemes of the nuclei is the analysis of γ - γ coincidence data. Since, an important difficulty in this kind of analysis is to properly define the coincidence background in γ - γ coincidence matrices, without introducing more statistical uncertainties or losing of information, a new automatic method (in the present stage suitable for symmetric matrices) has been developed. It is based on the algorithm sketched below: - given Mij, a symmetrized γ - γ coincidence matrix, the number of counts in each cell is Mij = idj> + icj> + idj> + icj>, where icj> represent the number of coincidences between discrete component on row i and continuous component on column j; - by defining the continuous component on each row of the matrix Mij, one obtain the non-symmetric matrix Bij = icj> + icj>; - by using the property of symmetry for Mij, the peak-peak coincidences are idj> = Mij - Bij - Bji + icj>. We choose to isolate Bij on each row of the Mij matrix and then to construct the continuous component icj>. On this purpose we have developed an original, robust algorithm for background subtraction in one-dimensional γ-spectra which provides a good quality subtraction, independent of the statistics or peak density of the processed spectrum. A computer code based on our method was written and has been tested for many experimental situations using data obtained both with the GASP array and with two detectors at IFIN-HH TANDEM accelerator. Some spectra obtained with gates on different background subtracted matrices are presented. (authors)

  5. Distinct coincidence detectors govern the corticostriatal spike timing-dependent plasticity.

    Science.gov (United States)

    Fino, Elodie; Paille, Vincent; Cui, Yihui; Morera-Herreras, Teresa; Deniau, Jean-Michel; Venance, Laurent

    2010-08-15

    Corticostriatal projections constitute the main input to the basal ganglia, an ensemble of interconnected subcortical nuclei involved in procedural learning. Thus, long-term plasticity at corticostriatal synapses would provide a basic mechanism for the function of basal ganglia in learning and memory. We had previously reported the existence of a corticostriatal anti-Hebbian spike timing-dependent plasticity (STDP) at synapses onto striatal output neurons, the medium-sized spiny neurons. Here, we show that the blockade of GABAergic transmission reversed the time dependence of corticostriatal STDP. We explored the receptors and signalling mechanisms involved in the corticostriatal STDP. Although classical models for STDP propose NMDA receptors as the unique coincidence detector, the involvement of multiple coincidence detectors has also been demonstrated. Here, we show that corticostriatal STDP depends on distinct coincidence detectors. Specifically, long-term potentiation is dependent on NMDA receptor activation, while long-term depression requires distinct coincidence detectors: the phospholipase Cbeta (PLCbeta) and the inositol-trisphosphate receptor (IP3R)-gated calcium stores. Furthermore, we found that PLCbeta activation is controlled by group-I metabotropic glutamate receptors, type-1 muscarinic receptors and voltage-sensitive calcium channel activities. Activation of PLCbeta and IP3Rs leads to robust retrograde endocannabinoid signalling mediated by 2-arachidonoyl-glycerol and cannabinoid CB1 receptors. Interestingly, the same coincidence detectors govern the corticostriatal anti-Hebbian STDP and the Hebbian STDP reported at cortical synapses. Therefore, LTP and LTD induced by STDP at corticostriatal synapses are mediated by independent signalling mechanisms, each one being controlled by distinct coincidence detectors. PMID:20603333

  6. On Dust Charging Equation

    OpenAIRE

    Tsintsadze, Nodar L.; Tsintsadze, Levan N.

    2008-01-01

    A general derivation of the charging equation of a dust grain is presented, and indicated where and when it can be used. A problem of linear fluctuations of charges on the surface of the dust grain is discussed.

  7. Probability for chance coincidence of a gamma-ray burst with a galaxy on the sky

    OpenAIRE

    Campisi, Maria Angela; Li, Li-Xin

    2008-01-01

    The nearby long GRB 060614 was not accompanied by a supernova, challenging the collapsar model for long-duration GRBs and the traditional classification scheme for GRBs. However, Cobb et al. have argued that the association of GRB 060614 and its host galaxy could be chance coincidence. In this work we calculate the probability for a GRB to be randomly coincident with a galaxy on the sky, using a galaxy luminosity function obtained from current galaxy surveys. We find that, with a magnitude li...

  8. Coincidence techniques (time correlation) alpha-gamma particles associated experiments on PGFNAA

    International Nuclear Information System (INIS)

    PGFNAA (Prompt Gamma Fast Neutron Alpha Associated) techniques offers capabilities far beyond those of the conventional inspection system to detect hazardous materials such as explosives or drugs. This technique uses the time coincidence between alpha and gamma particles to reduce the background produced by fast neutron interactions not only with the objects but also with the surrounding material. This paper reports the experimental setup that have been conducted to capture coincident events between alpha and gamma particles. Although not perfect, but the reduction of the background almost 100 % had been obtained on the outside area of the spectrum energy interest for water and graphite samples. (author)

  9. LIGO Triggered Search for Coincidence with High Energy Photon Survey Missions

    Science.gov (United States)

    Camp, Jordan

    2009-01-01

    LIGO is about to begin a new, higher sensitivity science run, where gravitational detection is plausible. A possible candidate for detection is a compact binary merger, which would also be likely to emit a high energy electromagnetic signal. Coincident observation of the gw signal from a compact merger with an x-ray or gamma-ray signal would add considerable weight to the claim for gw detection. In this talk I will consider the possibility of using LIGO triggers with time and sky position to perform a coincident analysis of EM signals from the RXTE, SWIFT, and FERMI missions.

  10. Revolution of S-stars and oscillation of solar and terrestrial observables: nonrandom coincidence of periods

    CERN Document Server

    Rusov, V D; Eingorn, M V

    2015-01-01

    A striking coincidence of revolution periods of S-stars orbiting a supermassive black hole at the Galactic Center of the Milky Way and oscillation periods of such solar and terrestrial observables as the sunspot number, the geomagnetic field Y-component and the global temperature is established on basis of the corresponding experimental data. Rejecting randomness of this discovered coincidence, we put forward a hypothesis that modulation of dark matter flows in the Milky Way by the S-stars is responsible for such a frequency transfer from the Galactic Center to the Solar System.

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

    International Nuclear Information System (INIS)

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

  12. Design and construct an interface card for spectroscopy of amplitude of coincident pulses

    International Nuclear Information System (INIS)

    In 2005, the spectroscopy basing on the summation of amplitude of coincidence pulses had been setup completely on the third horizontal channel of neutron beam at Dalat Research Reactor (DRR). In 2006, it was planted to improve the specifications. It was increased from two channels to three channels for data acquisition. To solve this problem, the project which designs and constructs an interface card with three channels for control of data acquisition of spectroscopy of summation of amplitude of coincidence pulses (SACP) has been done. And some new techniques have been used in designing and manufacturing. (author)

  13. Design and construct an interface card for spectroscopy of amplitude of coincidence pulses

    International Nuclear Information System (INIS)

    In 2005, the spectroscopy basing on the summation of amplitude of coincidence pulses had been setup completely on the third horizontal channel of neutron beam at Dalat Research Reactor (DRR). In 2006, it was planted to improve the specifications. It was increased from two channels to three channels for data acquisition. To solve this problem, the project which designs and constructs an interface card with three channels for control of data acquisition of spectroscopy of summation of amplitude of coincidence pulses (SACP) has been done. And some new techniques have been used in designing and manufacturing. (author)

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

    International Nuclear Information System (INIS)

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

  15. n-Tupled Coincidence Point Theorems for Probabilistic ψ-Contractions in Menger Spaces

    Directory of Open Access Journals (Sweden)

    Penumarthy Parvateesam Murthy

    2016-01-01

    Full Text Available We introduced n-tupled coincidence point for a pair of maps T:Xn→X and A:X→X in Menger space. Utilizing the properties of the pseudometric and the triangular norm, we will establish n-tupled coincidence point theorems under weak compatibility as well as n-tupled fixed point theorems for hybrid probabilistic ψ-contractions with a gauge function. Our main results do not require the conditions of continuity and monotonicity of ψ. At the end of this paper, an example is given to support our main theorem.

  16. Induced Charge Capacitive Deionization

    OpenAIRE

    Rubin, S.; Suss, M. E.; Biesheuvel, P. M.; Bercovici, M.

    2016-01-01

    We demonstrate the phenomenon of induced-charge capacitive deionization (ICCDI) that occurs around a porous and conducting particle immersed in an electrolyte, under the action of an external electrostatic field. The external electric field induces an electric dipole in the porous particle, leading to capacitive charging of its volume by both cations and anions at opposite poles. This regime is characterized both by a large RC charging time and a small electrochemical charge relaxation time, ...

  17. Primitive Virtual Negative Charge

    OpenAIRE

    Kim, Kiyoung

    2008-01-01

    Physical fields, such as gravity and electromagnetic field, are interpreted as results from rearrangement of vacuum particles to get the equilibrium of net charge density and net mass density in 4-dimensional complex space. Then, both fields should interact to each other in that physical interaction is considered as a field-to-field interaction. Hence, Mass-Charge interaction is introduced with primitive-virtual negative charge defined for the mass. With the concept of Mass-Charge interaction...

  18. Ion-coincidence momentum imaging of three-body Coulomb explosion of formaldehyde in ultrashort intense laser fields

    Energy Technology Data Exchange (ETDEWEB)

    Fushitani, M.; Matsuda, A.; Hishikawa, A., E-mail: hishi@chem.nagoya-u.ac.jp [Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602 (Japan); Tseng, C.-M. [Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi 444-8585 (Japan)

    2015-12-31

    Three-body Coulomb explosion of formaldehyde (H{sub 2}CO) in intense 7- and 35-fs laser fields (1.3 × 10{sup 15} W/cm{sup 2}) has been investigated by using ion-coincidence momentum imaging technique. Two types of explosion pathways from the triply charged state, H{sub 2}CO{sup 3+} → (i) H{sup +} + H{sup +} + CO{sup +} and (ii) H{sup +} + CH{sup +} + O{sup +}, have been identified. It is shown from the momentum correlation of the fragment ions of pathway (i), that the geometrical structure of the molecule is essentially frozen along the H-C-H bending coordinate for the 7-fs case. On the other hand, for a longer pulse duration (35 fs), structural deformation along the C-H stretching and H-C-H bending coordinates is identified, which is ascribed to the nuclear dynamics in the dication states populated within the laser pulse duration.

  19. Charge exchange system

    Science.gov (United States)

    Anderson, Oscar A.

    1978-01-01

    An improved charge exchange system for substantially reducing pumping requirements of excess gas in a controlled thermonuclear reactor high energy neutral beam injector. The charge exchange system utilizes a jet-type blanket which acts simultaneously as the charge exchange medium and as a shield for reflecting excess gas.

  20. Space Charge Effects

    CERN Document Server

    Ferrario, M; Palumbo, L

    2014-01-01

    The space charge forces are those generated directly by the charge distribution, with the inclusion of the image charges and currents due to the interaction of the beam with a perfectly conducting smooth pipe. Space charge forces are responsible for several unwanted phenomena related to beam dynamics, such as energy loss, shift of the synchronous phase and frequency , shift of the betatron frequencies, and instabilities. We will discuss in this lecture the main feature of space charge effects in high-energy storage rings as well as in low-energy linacs and transport lines.

  1. Coincidence of the Universe Description Stemming from D-branes Theory and ENU Model

    OpenAIRE

    Sima, Jozef; Sukenik, Miroslav

    2001-01-01

    The contribution provides a comparison of consequences stemming from D-brane theories and Expansive Nondecelerative Universe model, and calls attention to coincidence of the results arising from the mentioned approaches to a description of the Universe. It follows from the comparison that the effects of quantum gravitation should appear at the energy near to 2 TeV.

  2. 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.

  3. 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

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

    International Nuclear Information System (INIS)

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

  5. Deduction of an improved formula for coincidence counting and its experimental verification

    International Nuclear Information System (INIS)

    An improved accurate coincidence correction formula has been deduced on the basis of Cox's theory considering the complex situations of differences in pulse shaping width as well as a relative delay existing between the two channels. The correctness has been examined by experiments. (author). 2 refs., 2 tabs

  6. Some New Coincidence Theorems in Product GFC-Spaces with Applications

    Directory of Open Access Journals (Sweden)

    Jianrong Zhao

    2014-01-01

    Full Text Available We first propose a new concept of GFC-subspace. Using this notion, we obtain a new continuous selection theorem. As a consequence, we establish some new collective fixed point theorems and coincidence theorems in product GFC-spaces. Finally, we give some applications of our theorems.

  7. Some New Coincidence Theorems in Product GFC-Spaces with Applications

    OpenAIRE

    Jianrong Zhao

    2014-01-01

    We first propose a new concept of GFC-subspace. Using this notion, we obtain a new continuous selection theorem. As a consequence, we establish some new collective fixed point theorems and coincidence theorems in product GFC-spaces. Finally, we give some applications of our theorems.

  8. Multiple scattering and accidental coincidences in the J-PET detector simulated using GATE package

    CERN Document Server

    Kowalski, P; Wiślicki, W; Raczyński, L; Bednarski, T; Białas, P; Bułka, J; Czerwiński, E; Gajos, A; Gruntowski, A; Kamińska, D; Kapłon, Ł; Kochanowski, A; Korcyl, G; Kowal, J; Kozik, T; Krzemień, W; Kubicz, E; Niedźwiecki, Sz; Pałka, M; Rudy, Z; Salabura, P; Sharma, N G; Silarski, M; Słomski, A; Smyrski, J; Strzelecki, A; Wieczorek, A; Wochlik, I; Zieliński, M; Zoń, N

    2015-01-01

    Novel Positron Emission Tomography system, based on plastic scintillators, is developed by the J-PET collaboration. In order to optimize geometrical configuration of built device, advanced computer simulations are performed. Detailed study is presented of background given by accidental coincidences and multiple scattering of gamma quanta.

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

    International Nuclear Information System (INIS)

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

  10. Light charged particle emission in heavy-ion reactions – What have we learnt?

    Indian Academy of Sciences (India)

    S Kailas

    2001-07-01

    Light charged particles emitted in heavy-ion induced reactions, their spectra and angular distributions measured over a range of energies, carry the signature of the underlying reaction mechanisms. Analysis of data of light charged particles, both inclusive and exclusive measured in coincidence with gamma rays, fission products, evaporation residues have yielded interesting results which bring out the influence of nuclear structure, nuclear mean field and dynamics on the emission of these particles.

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  13. Electrostatic interaction of two charged macroparticles in an equilibrium plasma

    Science.gov (United States)

    Filippov, A. V.; Pal', A. F.; Starostin, A. N.

    2015-11-01

    This article is a critical review of publications devoted to studying the electrostatic interaction of two charged macroparticles in an equilibrium plasma. It is shown from an analysis of the force of interaction based on the Maxwell stress tensor that two macroparticles with identical charges in the Poisson-Boltzmann model always repel each other both in isothermal and nonisothermal plasmas. At distances between macroparticles for which the Boltzmann exponents can be linearized, the interaction between macroparticles is completely described by the Debye-Hückel model. The correction to free energy due to the electrostatic interaction in the system of two macroparticles is determined by integrating the correction to the internal energy and by direct calculation of the correction for entropy. It is shown that the free energy coincides with the Yukawa potential. The coincidence of the interaction energy obtained by integrating the force of interaction with the free energy leads to the conclusion about the potential nature of the force of interaction between two macroparticles in an equilibrium plasma. The effect of the outer boundary on the electrostatic interaction force is analyzed; it is shown that the type of interaction depends on the choice of the boundary conditions at the outer boundary. It is also shown that the accumulation of space charge near the outer boundary can lead to the attraction of similarly charged particles at distances comparable with the radius of the outer boundary.

  14. Electrostatic interaction of two charged macroparticles in an equilibrium plasma

    International Nuclear Information System (INIS)

    This article is a critical review of publications devoted to studying the electrostatic interaction of two charged macroparticles in an equilibrium plasma. It is shown from an analysis of the force of interaction based on the Maxwell stress tensor that two macroparticles with identical charges in the Poisson–Boltzmann model always repel each other both in isothermal and nonisothermal plasmas. At distances between macroparticles for which the Boltzmann exponents can be linearized, the interaction between macroparticles is completely described by the Debye–Hückel model. The correction to free energy due to the electrostatic interaction in the system of two macroparticles is determined by integrating the correction to the internal energy and by direct calculation of the correction for entropy. It is shown that the free energy coincides with the Yukawa potential. The coincidence of the interaction energy obtained by integrating the force of interaction with the free energy leads to the conclusion about the potential nature of the force of interaction between two macroparticles in an equilibrium plasma. The effect of the outer boundary on the electrostatic interaction force is analyzed; it is shown that the type of interaction depends on the choice of the boundary conditions at the outer boundary. It is also shown that the accumulation of space charge near the outer boundary can lead to the attraction of similarly charged particles at distances comparable with the radius of the outer boundary

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  17. Modelling airport congestion charges

    OpenAIRE

    Janić, Milan

    2012-01-01

    This article deals with modelling congestion charges at an airport. In this context, congestion charging represents internalizing the cost of marginal delays that a flight imposes on other flights due to congestion. The modelling includes estimating congestion and flight delays, the cost of these delays and the efficiency of particular flights following the introduction ofa congestion charge. The models are applied to an airport / New York LaGuardia / to illustrate their ability to handle mor...

  18. 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.)

  19. More Than Charged Base Loss — Revisiting the Fragmentation of Highly Charged Oligonucleotides

    Science.gov (United States)

    Nyakas, Adrien; Eberle, Rahel P.; Stucki, Silvan R.; Schürch, Stefan

    2014-07-01

    Tandem mass spectrometry is a well-established analytical tool for rapid and reliable characterization of oligonucleotides (ONs) and their gas-phase dissociation channels. The fragmentation mechanisms of native and modified nucleic acids upon different mass spectrometric activation techniques have been studied extensively, resulting in a comprehensive catalogue of backbone fragments. In this study, the fragmentation behavior of highly charged oligodeoxynucleotides (ODNs) comprising up to 15 nucleobases was investigated. It was found that ODNs exhibiting a charge level (ratio of the actual to the total possible charge) of 100% follow significantly altered dissociation pathways compared with low or medium charge levels if a terminal pyrimidine base (3' or 5') is present. The corresponding product ion spectra gave evidence for the extensive loss of a cyanate anion (NCO-), which frequently coincided with the abstraction of water from the 3'- and 5'-end in the presence of a 3'- and 5'-terminal pyrimidine nucleobase, respectively. Subsequent fragmentation of the M-NCO- ion by MS3 revealed a so far unreported consecutive excision of a metaphosphate (PO3 -)-ion for the investigated sequences. Introduction of a phosphorothioate group allowed pinpointing of PO3 - loss to the ultimate phosphate group. Several dissociation mechanisms for the release of NCO- and a metaphosphate ion were proposed and the validity of each mechanism was evaluated by the analysis of backbone- or sugar-modified ONs.

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

    International Nuclear Information System (INIS)

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

  1. Forward-Angle 3He(e,e'π±) Coincident Electroproduction and the Search for Δ's in the Ground State of 3He

    International Nuclear Information System (INIS)

    Forward-angle coincident electroproduction cross sections of charged pions from 3He have been measured at electron energies E0=855, 675, 600, and 555 MeV. The overall features of the data for energy transfers of ω=370 to 430 MeV with pions detected along the momentum transfer axis are reproduced in terms of a microscopic model, including pole terms, final state rescattering and produced and preformed Δ resonances. Separation of the cross section into its longitudinal and transverse parts was performed at Q2=0.045(GeV/c)2. The longitudinal part of the cross section in the π+ channel does not contradict with the assumption of a preformed Δ++. copyright 1996 The American Physical Society

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

    International Nuclear Information System (INIS)

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

  3. Things, stuffs, and coincidence. A non-ontological point of view

    Directory of Open Access Journals (Sweden)

    Nikos Psarros

    2001-03-01

    Full Text Available In this article the problem of the so-called 'coinciding objects', i.e. the question whether a substantially homogeneous thing is something ontologically different from the corresponding 'piece of stuff' it is made of or not, is examined from a pragmatical and language-analytical point of view. Instead of recurring to ontological assertions, I propose to regard 'stuffs' or 'substances' as a mode of speaking about things that fulfil the condition of being homogeneous in respect to a certain kind of properties that are called substantial properties. The coincidence problem is resolved by demonstrating that terms for substantially homogeneous things and the corresponding 'pieces of stuff' are predicative expressions in an Aristotelian genus-species relationship.

  4. LINEAR BUNDLES WITHIN THE FRAMEWORK OF COINCIDENCE OF CIRCLE AND ELLIPSE

    Directory of Open Access Journals (Sweden)

    Polezhaev Yuriy Olegovich

    2012-10-01

    Full Text Available Compositions represented by geometrical graphic models of circular and elliptical shapes enjoy wide application in architectural and interior design. The research of variations of coincidences of circles and ellipses is a relevant subject of exploration. In the paper, the authors analyze some of the multiplicity of coincidences, and an example of their practical implementation (a church dome model. The section of an object is "amalgamated" into the architectural concept of the structure, the relief and theological ideas. Geometric interlinks, compositions and figurations of interconnected diameters, circular and elliptical arcs, their tangency, incidences and interspaces have always been of interest to researchers; they have triggered the search for harmonious and rational solutions in civil engineering and architecture. Advancements in theoretical geometrography and its software applications facilitate new solutions.

  5. Coincident site lattice-matched growth of semiconductors on substrates using compliant buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Norman, Andrew

    2016-08-23

    A method of producing semiconductor materials and devices that incorporate the semiconductor materials are provided. In particular, a method is provided of producing a semiconductor material, such as a III-V semiconductor, on a silicon substrate using a compliant buffer layer, and devices such as photovoltaic cells that incorporate the semiconductor materials. The compliant buffer material and semiconductor materials may be deposited using coincident site lattice-matching epitaxy, resulting in a close degree of lattice matching between the substrate material and deposited material for a wide variety of material compositions. The coincident site lattice matching epitaxial process, as well as the use of a ductile buffer material, reduce the internal stresses and associated crystal defects within the deposited semiconductor materials fabricated using the disclosed method. As a result, the semiconductor devices provided herein possess enhanced performance characteristics due to a relatively low density of crystal defects.

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

    Science.gov (United States)

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

    1978-01-01

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

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

    CERN Document Server

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

    2015-01-01

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

  8. A coincidence detection algorithm for improving detection rates in coulomb explosion imaging

    International Nuclear Information System (INIS)

    A scheme for determining true coincidence events in Coulomb Explosion Imaging experiments is reported and compared with a simple design used in recently published work. The new scheme is able to identify any possible coincidence without the use of a priori knowledge of the fragmentation mechanism. Using experimental data from the triatomic molecule OCS, the advanced algorithm is shown to improve acquisition yield by a factor of between 2 and 6 depending on the amount of a priori knowledge included in the simple design search. Monte Carlo simulations for both systems suggest that detection yield can be improved by increasing the number of molecules in the laser focus from the standard ≤1 up to 3.5 and employing the advanced algorithm. Count rates for larger molecules would be preferentially improved with the rate for 6 atom molecules improved by a factor of up to five.

  9. A feasibility study of a coincidence counting approach for PGNAA applications

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, R.P. E-mail: gardner@ncsu.edu; Mayo, C.W.; El-Sayyed, E.S.; Metwally, W.A.; Zheng, Y.; Poezart, M

    2000-11-15

    Prompt gamma-ray neutron activation analysis (PGNAA) has an inherently low signal-to-noise (S/N) ratio primarily because of the large background (noise) associated with it. Most elements emit a significant fraction of their prompt gamma rays in coincidence with one or more other prompt gamma rays. This paper reports on initial efforts to use coincidence counting in PGNAA to significantly reduce the several sources of background and thereby increase the S/N ratio. An added benefit is the elimination of the often dominant hydrogen prompt gamma-ray spectrum which emits only a single prompt gamma ray with an energy of 2.223 MeV. Preliminary results are given for both in situ bulk analysis applications with a {sup 252}Cf neutron source and for nuclear reactor thermal neutron beam applications for small laboratory samples.

  10. A feasibility study of a coincidence counting approach for PGNAA applications

    Science.gov (United States)

    Gardner; Mayo; El-Sayyed; Metwally; Zheng; Poezart

    2000-10-01

    Prompt gamma-ray nutron activation analysis (PGNAA) has an inherently low signal-to-noise (S/N) ratio primarily because of the large background (noise) associated with it. Most elements emit a significant fraction of their prompt gamma rays in coincidence with one or more other prompt gamma rays. This paper reports on initial efforts to use coincidence counting in PGNAA to significantly reduce the several sources of background and thereby increase the S/N ratio. An added benefit is the elimination of the often dominant hydrogen prompt gamma-ray spectrum which emits only a single prompt gamma ray with an energy of 2.223 MeV. Preliminary results are given for both in situ bulk analysis applications with a 252Cf neutron source and for nuclear reactor thermal neutron beam applications for small laboratory samples. PMID:11003486

  11. A feasibility study of a coincidence counting approach for PGNAA applications

    International Nuclear Information System (INIS)

    Prompt gamma-ray neutron activation analysis (PGNAA) has an inherently low signal-to-noise (S/N) ratio primarily because of the large background (noise) associated with it. Most elements emit a significant fraction of their prompt gamma rays in coincidence with one or more other prompt gamma rays. This paper reports on initial efforts to use coincidence counting in PGNAA to significantly reduce the several sources of background and thereby increase the S/N ratio. An added benefit is the elimination of the often dominant hydrogen prompt gamma-ray spectrum which emits only a single prompt gamma ray with an energy of 2.223 MeV. Preliminary results are given for both in situ bulk analysis applications with a 252Cf neutron source and for nuclear reactor thermal neutron beam applications for small laboratory samples

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

    International Nuclear Information System (INIS)

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

  13. Detection of coincident radiations in a single transducer by pulse shape analysis

    Science.gov (United States)

    Warburton, William K.

    2008-03-11

    Pulse shape analysis determines if two radiations are in coincidence. A transducer is provided that, when it absorbs the first radiation produces an output pulse that is characterized by a shorter time constant and whose area is nominally proportional to the energy of the absorbed first radiation and, when it absorbs the second radiation produces an output pulse that is characterized by a longer time constant and whose area is nominally proportional to the energy of the absorbed second radiation. When radiation is absorbed, the output pulse is detected and two integrals are formed, the first over a time period representative of the first time constant and the second over a time period representative of the second time constant. The values of the two integrals are examined to determine whether the first radiation, the second radiation, or both were absorbed in the transducer, the latter condition defining a coincident event.

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-05-21

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

  16. Search for large-scale coincidences in network observation of cosmic ray air showers

    International Nuclear Information System (INIS)

    The Large Area Air Shower (LAAS) group has been performing a network observation of extensive air showers (EAS) since 1996 in Japan. Eight compact EAS arrays (ten in the near future) are operating simultaneously and independently at distant stations (up to ∼ 1000 km), constituting a gigantic detector system as a whole. Using five stations' datasets, large-scale coincidences of EAS have been searched for with the aim of detecting signals from extremely short bursts in the universe. By comparing arrival times and arrival directions of all registered EAS, three coincident and parallel EAS pairs were extracted out of a sea of background cosmic rays. One of them was observed almost from the direction of the Crab Nebula, a previously reported ultra-high-energy γ-ray source. The first application reported here allows the analysis techniques to be tested and demonstrates the potential of observations with the full operation of the network detector system

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

    International Nuclear Information System (INIS)

    Coincident site lattice-matched wurtzite (0001) In0.31Ga0.69N, emitting in the important green wavelength region, is demonstrated by molecular beam epitaxy on a cubic (111) MgAl2O4 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.

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

    International Nuclear Information System (INIS)

    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 24Na, 46Sc, 60Co, 66Ga, 75Se, 88Y, Nb94, 111In, 123mTe, 133Ba, 134Cs, 152Eu, 154Eu and 207Bi. Reaction 11B (p,γ) 12C* 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. SPADnet: Embedded coincidence in a smart sensor network for PET applications

    International Nuclear Information System (INIS)

    In this paper we illustrate the core technologies at the basis of the European SPADnet project ( (www.spadnet.eu)), and present the corresponding first results. SPADnet is aimed at a new generation of MRI-compatible, scalable large area image sensors, based on CMOS technology, that are networked to perform gamma-ray detection and coincidence to be used primarily in (Time-of-Flight) Positron Emission Tomography (PET). The project innovates in several areas of PET systems, from optical coupling to single-photon sensor architectures, from intelligent ring networks to reconstruction algorithms. In addition, SPADnet introduced the first computational model enabling study of the full chain from gamma photons to network coincidence detection through scintillation events, optical coupling, etc

  20. Valence photodissociation of trifluoroethyl iodide investigated by photoelectron photoion coincidence spectroscopy

    International Nuclear Information System (INIS)

    Highlights: •Experimental and theoretical Investigation of trifluoroethyl iodide molecule. •Photoelectron photoion coincidence spectra in the 10–22 eV range. •VUV photoionization and dissociation dynamics. -- Abstract: Dissociative photoionization of trifluoroethyl iodide (C2H2F3I) molecule has been investigated by electron-ion coincidence technique (PEPICO) and VUV synchrotron radiation. Mass spectra have been recorded for this molecule in the photon energy range of 10–22 eV. The molecular ion as well as cationic fragments have been detected and analyzed as a function of photon energy and the main dissociation pathways are proposed. We also performed ab initio calculations for the neutral molecule, its cation and the ion fragments in order to determine electronic and structural parameters

  1. Digital coincidence acquisition applied to portable β liquid scintillation counting device

    International Nuclear Information System (INIS)

    A digital coincidence acquisition system applied to a portable liquid scintillation counting device is developed. The system which simplifies the device design consists of a digitizer card of Agilent U1066A DC438, a discriminator and a host computer. The anode analog pulses from two photomultiplier tubes are captured by the system, which adopts the sequence acquisition storage mode. By choosing proper threshold for each channel, coincidence time window of ±30 ns, and comparing the pulse amplitudes from two channels, the portable scintillation counting device can be used to detect β particles. For the unquenched standard 3H sample, the results show that the detection efficiency is (58.5±0.1)% and the background is (86.7±0.7) cpm. Meanwhile, 3H β spectrum is obtained. (authors)

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2014-12-11

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-06-12

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Henzlova, Daniela [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Menlove, Howard Olsen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-04-21

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

  7. A processing circuit for overlapped pulse signals for a thermal neutron coincidence counter

    International Nuclear Information System (INIS)

    We have developed a processing circuit for overlapped pulse signals. The overlapped pulse signals are generated when the pulse signals of a He-3 detector, by using a neutron coincidence counter, are connected to shift register coincidence electronics by an OR gate device. The developed circuit detects the overlapped pulse signals from among four input signals and produces new 50 ns pulse wide signals. We considered a case where two pulse signals are simultaneously overlapped among four signals. This circuit was tested with an ACP safeguards neutron counter (ASNC) for an advanced spent fuel conditioning process (ACP) and a 252Cf neutron source at high rates. The loss rate of the output signal was reduced by 1.27% for singles and 4.75% for doubles when compared with the OR gate device. Also the variation for the triples was much bigger.

  8. Low-level gamma spectrometry using beta coincidence and Compton suppression.

    Science.gov (United States)

    Grigorescu, E L; De Felice, P; Razdolescu, Anamaria-Cristina; Luca, A

    2004-01-01

    A low-level gamma-ray spectrometry system was developed using a Ge(Li) detector with 6% relative efficiency coupled to a 2pi beta plastic detector for coincidence selection and a massive NaI(Tl) detector for Compton suppression. The integral background count rate for (50-1500)keV was 0.5 s(-1)kg(-1) (Ge), using only beta coincidences. With Compton suppression, a value of 0.25 s(-1)kg(-1) (Ge) was obtained. Spectra with and without Compton suppression were studied for 60Co, 137Cs and 152Eu point sources. Considerations are made concerning the Compton suppression advantages in different situations. PMID:15177343

  9. Realisation of a β spectrometer solenoidal and a double β spectrometer at coincidence

    International Nuclear Information System (INIS)

    The two spectrometers have been achieved to tackle numerous problems of nuclear spectrometry. They possess different fields of application that complete themselves. The solenoidal spectrometer permits the determination of the energy limits of β spectra and of their shape; it also permits the determination of the coefficients of internal conversion and reports αK / αL and it is especially efficient for the accurate energy levels of the γ rays by photoelectric effect. The double coincidence spectrometer has been conceived to get a good efficiency in coincidence: indeed, the sum of the solid angles used for the β and γ emission is rather little lower to 4π steradians. To get this efficiency, one should have sacrificed a little the resolution that is lower to the one obtained with the solenoidal spectrometer for a same brightness. Each of the elements of the double spectrometer can also be adapted to the study of angular correlations βγ and e-γ. In this use, it is superior to the thin magnetic lens used up to here. The double spectrometer also permits the survey of the coincidences e-e-, e-β of a equivalent way to a double lens; it can also be consider some adaptation for the survey of the angular correlations e-e-, e-β. Finally, we applied the methods by simple spectrometry and by coincidence spectrometry, to the study of the radiances of the following radioelements: 76As (26 h), 122Sb (2,8 j), 124Sb (60 j), 125Sb (2,7 years). (M.B.)

  10. Interaction between Dark Matter and Dark Energy and the Cosmological Coincidence Problem

    OpenAIRE

    Kourosh Nozari; Noushin Behrouz; Narges Rashidi

    2014-01-01

    We consider a quintessence model of dark energy inspired by scalar-tensor theories of gravity where the scalar field is nonminimally coupled to gravity and dark matter. By considering exponential potential as self-interaction potential, the stability and existence of the critical points are discussed in details. With nonminimally coupled dark sector with gravity, we obtain scaling solutions to address the coincidence problem by considering complex velocity for dark matter. The statefinder dia...

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

    International Nuclear Information System (INIS)

    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)

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

    OpenAIRE

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

    2004-01-01

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

  13. Peak Doubling in SPDC Coincidence Spectra with a Short-Pulse Pump

    OpenAIRE

    Fedorov, Mikhail V.; Mikhailova, Julia M.; Volkov, Peter A.

    2011-01-01

    We describe a double-peak structure of the coincidence spectrum of biphoton states in the process of spontaneous parametric down-conversion with a pump having the form of short pulses. The effect is shown to arise owing to the obligatory symmetry of bihoton wave functions, as wave functions describing states of two bozons obeying the Bose-Einstein statistics. Parameters of the peaks are found and conditions necessary for experimental observation of the effect are determined.

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

    OpenAIRE

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

    2004-01-01

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

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Study of Neutron Induced Reactions on 7Be Using Large Angle Coincidence Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Vacík, Jiří; Hnatowicz, Vladimír; Koster, U.

    Vol. 66. San Antonio : Elsevier, 2015, s. 520-523. ISSN 1875-3892. [23rd International Conference on the Application of Accelerators in Research and Industry (CAARI). San Antonio (US), 25.05.2014-30.05.2014] R&D Projects: GA MŠk(CZ) LM2011019; GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:61389005 Keywords : radioactive nuclei * Berylium * thermal neutrons * coincidence spectroscopy Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders

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

    CERN Document Server

    Eaves, Laurence

    2014-01-01

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

  19. A method to estimate the significance of coincident gravitational-wave observations from compact binary coalescence

    OpenAIRE

    Cannon, K; Hanna, C.; Keppel, D.

    2013-01-01

    Coalescing compact binary systems consisting of neutron stars and/or black holes should be detectable with upcoming advanced gravitational-wave detectors such as LIGO, Virgo, GEO and {KAGRA}. Gravitational-wave experiments to date have been riddled with non-Gaussian, non-stationary noise that makes it challenging to ascertain the significance of an event. A popular method to estimate significance is to time shift the events collected between detectors in order to establish a false coincidence...

  20. Gut microflora of abalone Haliotis discus hannai in culture changes coincident with a change in diet

    OpenAIRE

    Tanaka, Reiji; Sugimura, Itsuro; SAWABE, Tomoo; Yoshimizu, Mamoru; Ezura, Yoshio

    2003-01-01

    Development of gut microflora in abalone Haliotis discus hannai cultured at two abalone farms in Japan was similar: (i) gut microflora of juvenile abalones fed on microalgae matched microflora cultured from seawater; and (ii) gut microflora changed coincident with the abalone switching food sources from microalgae to algal pellets. After abalone reached 4 months of age, the gut microflora was replaced by algal polysaccharide-degrading bacteria, which were almost entirely characterized as facu...

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

    International Nuclear Information System (INIS)

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

  2. Severe mammal declines coincide with proliferation of invasive Burmese pythons in Everglades National Park

    OpenAIRE

    Dorcas, Michael E.; Willson, John D.; Reed, Robert N.; Snow, Ray W.; Rochford, Michael R.; Miller, Melissa A.; Meshaka, Walter E.; Andreadis, Paul T.; Mazzotti, Frank J.; Christina M. Romagosa; Hart, Kristen M.

    2012-01-01

    Invasive species represent a significant threat to global biodiversity and a substantial economic burden. Burmese pythons, giant constricting snakes native to Asia, now are found throughout much of southern Florida, including all of Everglades National Park (ENP). Pythons have increased dramatically in both abundance and geographic range since 2000 and consume a wide variety of mammals and birds. Here we report severe apparent declines in mammal populations that coincide temporally and spatia...

  3. Assay of plutonium oxide in different unknown MOX samples by neutron well coincidence counting

    International Nuclear Information System (INIS)

    During fabrication process of Plutonium based Mixed Oxide (MOX) fuel a few number of equipment/machines are involved to entail the desirable quality product as MOX pellets. It is inherently observed that an ample quantity UO2, PuO2 MOX powder remains deposited or entrapped in high load press used for making pellets. Since plutonium is an important fissile component in MOX, it is to be reutilized for fabrication of pellets. These MOX are collected during refurbishing or maintenance of the equipments from the floor of glove boxes. The estimation of PuO2 in these floor scraps are initiated using Neutron Well Coincidence Counting (NWCC). NWCC is a Non-Destructive technique for determination of amount of PuO2 in MOX sample. The technique monitors neutrons emitting from spontaneous fission of 238Pu, 240Pu and 242Pu are counted by proportional counter filled with 3He gas. To separate fission neutron emitted by even-even Isotope of Pu from background (α,n) neutrons, coincidence logic has been used in this technique. To correlate amount of PuO2 with coincidence count rate, the specific activity of 238Pu, 240Pu, 242Pu and their weight percent are prerequisite. NWCC was used for the determination of PuO2 in MOX floor scrap. The NWCC system was calibrated with series of known Pure PuO2 working standards. Each standard was counted for 100 sec. for five times and the average values were recorded. A calibration was drawn between average coincidence counts and wt of the standard PuO2 samples. This calibration plot was used to determine amount of PuO2 in MOX floor scrap. Precision and accuracy of the system was found to be 3.0 percent for 3.0 g PuO2

  4. Correlated charge-changing ion-atom collisions

    International Nuclear Information System (INIS)

    This report summarizes the progress and accomplishments in accelerator atomic physics research supported by DOE grant DE-FG02-87ER13778 from March 16, 1991 through March 15, 1992. This work involves the experimental investigation of fundamental atomic processes in collisions of charged projectiles with neutral targets or electrons, with particular emphasis on two-electron interactions and electron correlation effects. Processes involving combinations of excitation, ionization, and charge transfer are investigated utilizing coincidence techniques in which projectiles charge-changing events are associated with x-ray emission, target recoil ions, or electron emission. New results have been obtained for studies involving (1) resonant recombination of atomic ions, (2) double ionization of helium, and (3) continuum electron emission. Experiments were conducted using accelerators at the Lawrence Berkeley Laboratory, Argonne National Laboratory, Michigan State University, Western Michigan University, and the Institute of Nuclear Research, Debrecen, Hungary. Brief summaries of work completed and work in progress are given in this report

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

    International Nuclear Information System (INIS)

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

  6. 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.

  7. Three-head positron coincidence detection (γ PET) by PRISM-IRIX gamma camera system

    International Nuclear Information System (INIS)

    The Shimadzu PRISM-IRIX is a three-headed variable-angle gamma camera system that also ensures the highest performances in single photon emission computed tomography (SPECT). It provides not only single photon imaging, but also positron coincidence imaging, by using two of the three heads. We have successfully improved the hardware and software of this system, so that the system fully utilizes all of the three heads in order to perform more reliable positron coincidence imaging. Also, we utilized the method of computer simulation to find out the head configuration that ensures the highest performances. Our investigations have shown that the triangular head configuration ensures the highest performances and stability of results in examinations of small organs where the rotation angle is set to 15 cm and that the C-mode head configuration gives the highest stability in examinations of larger organs where the rotation angle is set to 30 cm. We have further improved the electronic circuitry of the head to establish a system called AZTec (adaptive zone technology system). This system ensures even higher coincidence efficiency and higher performances in general. (author)

  8. 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.

  9. A model of spike-timing dependent plasticity: one or two coincidence detectors?

    Science.gov (United States)

    Karmarkar, Uma R; Buonomano, Dean V

    2002-07-01

    In spike-timing dependent plasticity (STDP), synapses exhibit LTD or LTP depending on the order of activity in the presynaptic and postsynaptic cells. LTP occurs when a single presynaptic spike precedes a postsynaptic one (a positive interspike interval, or ISI), while the reverse order of activity (a negative ISI) produces LTD. A fundamental question is whether the "standard model" of plasticity in which moderate increases in Ca(2+) influx through the N-methyl-D-aspartate (NMDA) channels induce LTD and large increases induce LTP, can account for the order and interval sensitivity of STDP. To examine this issue we developed a model that captures postsynaptic Ca(2+) influx dynamics and the associativity of the NMDA receptors. While this model can generate both LTD and LTP, it predicts that LTD will be observed at both negative and positive ISIs. This is because longer and longer positive ISIs induce monotonically decreasing levels of Ca(2+), which eventually fall into the same range that produced LTD at negative ISIs. A second model that incorporated a second coincidence detector in addition to the NMDA receptor generated LTP at positive intervals and LTD only at negative ones. Our findings suggest that a single coincidence detector model based on the standard model of plasticity cannot account for order-specific STDP, and we predict that STDP requires two coincidence detectors. PMID:12091572

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

    Science.gov (United States)

    Alnour, I. A.; Wagiran, H.; Ibrahim, N.; Hamzah, S.; Siong, W. B.; Elias, M. S.

    2016-01-01

    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 57Co, 60Co, 133Ba and 137Cs 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.

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

    Science.gov (United States)

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

    2012-01-01

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

  12. A new double imaging velocity focusing coincidence experiment: i2PEPICO

    International Nuclear Information System (INIS)

    The vacuum ultraviolet (VUV) beamline of the Swiss Light Source has been upgraded after two years of operation. A new, turntable-type monochromator was constructed at the Paul Scherrer Institut, which allows for fast yaw-alignment as well as quick grating change and exchange. In addition to the original imaging photoelectron photoion coincidence endstation (iPEPICO), a second, complementary double imaging setup (i2PEPICO) has been built. Volatile samples can be introduced at room temperature or in a molecular beam, a pyrolysis source allows for radical production, and non-volatile solids can be evaporated in a heated cell. Monochromatic VUV radiation ionizes the sample and both photoelectrons and photoions are velocity map imaged onto two fast position sensitive detectors and detected in delayed coincidence. High intensity synchrotron radiation leads to ionization rates above 105 s−1. New data acquisition and processing approaches are discussed for recording coincidence processes at high rates. The setup is capable of resolving pulsed molecular beam profiles and the synchrotron time structure temporally. The latter is shown by photoelectron autocorrelation, which displays both the 1.04 MHz ring clock frequency as well as resolving the micro-pulses with a separation of 2 ns. Kinetic energy release analysis on the dissociative photoionization of CF4 indicates a dissociation mechanism change in the Franck–Condon allowed energy range of the first ion state.

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

    Science.gov (United States)

    Bailey, Catherine

    2011-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2012-01-01

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

  18. Detecting gravitational waves from inspiraling binaries with a network of detectors coherent versus coincident strategies

    CERN Document Server

    Mukhopadhyay, H; Kanda, H T N; Sago, N; Tagoshi, H; Dhurandhar, Sanjeev; Kanda, Hirotaka Takahashi & Nobuyuki; Mukhopadhyay, Himan; Sago, Norichica; Tagoshi, Hideyuki

    2006-01-01

    We compare two strategies of multi-detector 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 as 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 th...

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

    International Nuclear Information System (INIS)

    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 57Co, 60Co, 133Ba and 137Cs 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

  20. Higher charge periodic monopoles

    OpenAIRE

    Maldonado, Rafael

    2013-01-01

    We consider singly periodic solutions to the SU(2) Bogomolny equations and use the Nahm transform to generate a class of monopoles of charge k>2, thereby extending known results for lower charge chains. Some simple scattering processes are presented and a comparison made with geodesic motion of monopoles in $\\mathbb{R}^3$.

  1. Charged weak currents

    International Nuclear Information System (INIS)

    In this review of charged weak currents we shall concentrate on inclusive high energy neutrino physics. The plan of this review is the following: general structure of charged current; new results on total cross-section; Callan-Gross relation; antiquark distribution; scaling violations and tests of QCD. At the end we will give a very short summary on multilepton physics

  2. Induced Charge Capacitive Deionization

    CERN Document Server

    Rubin, S; Biesheuvel, P M; Bercovici, M

    2016-01-01

    We demonstrate the phenomenon of induced-charge capacitive deionization (ICCDI) that occurs around a porous and conducting particle immersed in an electrolyte, under the action of an external electrostatic field. The external electric field induces an electric dipole in the porous particle, leading to capacitive charging of its volume by both cations and anions at opposite poles. This regime is characterized both by a large RC charging time and a small electrochemical charge relaxation time, which leads to rapid and significant deionization of ionic species from a volume which is on the scale of the particle. We show by theory and experiment that the transient response around a cylindrical particle results in spatially non-uniform charging and non-steady growth of depletion regions which emerge around the particle's poles. Potentially, ICCDI can be useful in applications where fast concentration changes of ionic species are required over large volumes.

  3. 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

  4. Electrodynamics of hyperbolically accelerated charges V. The field of a charge in the Rindler space and the Milne space

    Science.gov (United States)

    Eriksen, E.; Grøn, Ø.

    2004-09-01

    We describe the electromagnetic field of a uniformly accelerated charge in its co-moving Rindler frame. It is shown that the electrical field lines coincide with the trajectories of photons. The self force of a charged particle at rest in Rindler space, and the increase of its weight due to its charge, is calculated. The general case of an accelerated charge in Rindler space is also considered. It is shown that the electrical field inside a uniformly charged spherical shell can be used as a measure of it 4-acceleration. A result that has earlier been deduced in a different way by Fugmann and Kretzschmar is confirmed, namely that the intensity of radiation from a point charge instantaneously at rest in an accelerated frame is proportional to the square of the relative acceleration of the charge and the observer. In particular it is shown that a freely falling charge in Rindler space radiates in accordance with Larmor's formula. In this case the radiation energy is taken from the Schott energy. The energy of the electromagnetic field is analysed from the point of view of the Hirayama-separation, which generalizes the Teitelboim-separation to non-inertial frames, of the field in a bound part and an unbound part. A detailed account, with reference to the Rindler frame, of the field energy and particle energy is given for the case of a charge entering and leaving a region with hyperbolic motion. We also consider the electromagnetic field of a uniformly accelerated charge with reference to the Milne frame, which covers a different part of spacetime than the Rindler frame. The radiating part of the electromagnetic field is found in the Milne sector of spacetime.

  5. Electrodynamics of hyperbolically accelerated charges V. The field of a charge in the Rindler space and the Milne space

    International Nuclear Information System (INIS)

    We describe the electromagnetic field of a uniformly accelerated charge in its co-moving Rindler frame. It is shown that the electrical field lines coincide with the trajectories of photons. The self force of a charged particle at rest in Rindler space, and the increase of its weight due to its charge, is calculated. The general case of an accelerated charge in Rindler space is also considered. It is shown that the electrical field inside a uniformly charged spherical shell can be used as a measure of it 4-acceleration. A result that has earlier been deduced in a different way by Fugmann and Kretzschmar is confirmed, namely that the intensity of radiation from a point charge instantaneously at rest in an accelerated frame is proportional to the square of the relative acceleration of the charge and the observer. In particular it is shown that a freely falling charge in Rindler space radiates in accordance with Larmor's formula. In this case the radiation energy is taken from the Schott energy. The energy of the electromagnetic field is analysed from the point of view of the Hirayama-separation, which generalizes the Teitelboim-separation to non-inertial frames, of the field in a bound part and an unbound part. A detailed account, with reference to the Rindler frame, of the field energy and particle energy is given for the case of a charge entering and leaving a region with hyperbolic motion. We also consider the electromagnetic field of a uniformly accelerated charge with reference to the Milne frame, which covers a different part of spacetime than the Rindler frame. The radiating part of the electromagnetic field is found in the Milne sector of spacetime

  6. Improved sliced velocity map imaging apparatus optimized for H photofragments.

    Science.gov (United States)

    Ryazanov, Mikhail; Reisler, Hanna

    2013-04-14

    Time-sliced velocity map imaging (SVMI), a high-resolution method for measuring kinetic energy distributions of products in scattering and photodissociation reactions, is challenging to implement for atomic hydrogen products. We describe an ion optics design aimed at achieving SVMI of H fragments in a broad range of kinetic energies (KE), from a fraction of an electronvolt to a few electronvolts. In order to enable consistently thin slicing for any imaged KE range, an additional electrostatic lens is introduced in the drift region for radial magnification control without affecting temporal stretching of the ion cloud. Time slices of ∼5 ns out of a cloud stretched to ⩾50 ns are used. An accelerator region with variable dimensions (using multiple electrodes) is employed for better optimization of radial and temporal space focusing characteristics at each magnification level. The implemented system was successfully tested by recording images of H fragments from the photodissociation of HBr, H2S, and the CH2OH radical, with kinetic energies ranging from 3 eV. It demonstrated KE resolution ≲1%-2%, similar to that obtained in traditional velocity map imaging followed by reconstruction, and to KE resolution achieved previously in SVMI of heavier products. We expect it to perform just as well up to at least 6 eV of kinetic energy. The tests showed that numerical simulations of the electric fields and ion trajectories in the system, used for optimization of the design and operating parameters, provide an accurate and reliable description of all aspects of system performance. This offers the advantage of selecting the best operating conditions in each measurement without the need for additional calibration experiments. PMID:24981528

  7. Improved sliced velocity map imaging apparatus optimized for H photofragments

    International Nuclear Information System (INIS)

    Time-sliced velocity map imaging (SVMI), a high-resolution method for measuring kinetic energy distributions of products in scattering and photodissociation reactions, is challenging to implement for atomic hydrogen products. We describe an ion optics design aimed at achieving SVMI of H fragments in a broad range of kinetic energies (KE), from a fraction of an electronvolt to a few electronvolts. In order to enable consistently thin slicing for any imaged KE range, an additional electrostatic lens is introduced in the drift region for radial magnification control without affecting temporal stretching of the ion cloud. Time slices of ∼5 ns out of a cloud stretched to ⩾50 ns are used. An accelerator region with variable dimensions (using multiple electrodes) is employed for better optimization of radial and temporal space focusing characteristics at each magnification level. The implemented system was successfully tested by recording images of H fragments from the photodissociation of HBr, H2S, and the CH2OH radical, with kinetic energies ranging from 3 eV. It demonstrated KE resolution ≲1%–2%, similar to that obtained in traditional velocity map imaging followed by reconstruction, and to KE resolution achieved previously in SVMI of heavier products. We expect it to perform just as well up to at least 6 eV of kinetic energy. The tests showed that numerical simulations of the electric fields and ion trajectories in the system, used for optimization of the design and operating parameters, provide an accurate and reliable description of all aspects of system performance. This offers the advantage of selecting the best operating conditions in each measurement without the need for additional calibration experiments.

  8. Electron transfer processes in collisions of highly charged energetic (0. 1 to 1. 0 MeV/nucleon) ions with helium atoms

    Energy Technology Data Exchange (ETDEWEB)

    Datz, S.; Hippler, R.; Andersen, L.H.; Dittner, P.F.; Knudsen, H.; Krause, H.F.; Miller, P.D.; Pepmiller, P.L.; Rosseel, T.; Stolterfoht, N.

    1987-01-01

    We have investigated charge transfer in collisions of energetic (0.1 - 1 MeV/nucleon) highly charged ions with helium atoms with the principal aim clarifying the nature of two-electron processes. The sensitivity of partial charge-changing cross sections (i.e., single- and double-charge transfer, transfer ionization (TI), and single and double ionization) to core configuration and scaling rules for one- and two-electron processes were investigated with iodine ions (q = 5+ ..-->.. 26+) and uranium ions (q = 17+ ..-->.. 44+) using an ion-charge state, recoil-ion coincidence method. Using zero-degree electron spectroscopy in coincidence with charge transfer, we found that at the higher energies, as in the case of 0.1 MeV/nucleon ions previously reported, TI involves the transfer of two electrons to a higher correlated state followed by loss of one electron to the continuum. In addition, we observe very high Rydberg electrons in coincidence with TI, implying a possible up-down correlation in the pair transfer. In addition, we made measurements of VUV photons emitted at the collision in coincidence with He/sup +/ and He/sup 2 +/ recoils. The results show that TI leads to capture into lower n states than single-charge transfer. 15 refs., 10 figs.

  9. Price Based Electric Vehicle Charging

    DEFF Research Database (Denmark)

    Mahat, Pukar; Handl, Martin; Kanstrup, Kenneth;

    2012-01-01

    paper investigates the impact on a Danish distribution system when the EV charging aims to reduce the charging cost by charging at the cheapest hours. Results show that the charging based on the price signal only will have adverse effect on the grid. The paper also proposes an alternate EV charging...

  10. Decay of electric charge on corona charged polyethylene

    International Nuclear Information System (INIS)

    This paper describes a study on the surface potential decay of corona charged low density polyethylene (LDPE) films. A conventional corona charging process is used to deposit charge on the surface of film and surface potential is measured by a compact JCI 140 static monitor. The results from corona charged multilayer sample reveal that the bulk process dominates charge decay. In addition, the pulsed-electro-acoustic (PEA) technique has been employed to monitor charge profiles in corona charged LDPE films. By using the PEA technique, we are able to monitor charge migration through the bulk. Charge profiles in corona charged multilayer sample are consistent with surface potential results. Of further significance, the charge profiles clearly demonstrate that double injection has taken place in corona charged LDPE films

  11. Effect of the charge localization in the C+-H+ fragmentation pathway of the ethyne dication

    International Nuclear Information System (INIS)

    The C+-H+ channel in the fragmentation of the ethyne dication following inner-shell ionization has been studied by Auger electron-ion-ion coincidence spectroscopy. The ion-ion coincidence map shows a peculiar feature which corresponds to the emission of both the H+ and C+ ions in the same direction. The analysis of the data, complemented by ab initio calculations, suggests an interpretation in terms of a two-step, asynchronous concerted reaction, in which the charge of the ethynyl intermediate ion localizes on the terminal carbon atom.

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2016-05-01

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

  14. Marrow Adipose Tissue Expansion Coincides with Insulin Resistance in MAGP1-Deficient Mice.

    Science.gov (United States)

    Walji, Tezin A; Turecamo, Sarah E; Sanchez, Alejandro Coca; Anthony, Bryan A; Abou-Ezzi, Grazia; Scheller, Erica L; Link, Daniel C; Mecham, Robert P; Craft, Clarissa S

    2016-01-01

    Marrow adipose tissue (MAT) is an endocrine organ with the potential to influence skeletal remodeling and hematopoiesis. Pathologic MAT expansion has been studied in the context of severe metabolic challenge, including caloric restriction, high fat diet feeding, and leptin deficiency. However, the rapid change in peripheral fat and glucose metabolism associated with these models impedes our ability to examine which metabolic parameters precede or coincide with MAT expansion. Microfibril-associated glycoprotein-1 (MAGP1) is a matricellular protein that influences cellular processes by tethering signaling molecules to extracellular matrix structures. MAGP1-deficient (Mfap2 (-/-)) mice display a progressive excess adiposity phenotype, which precedes insulin resistance and occurs without changes in caloric intake or ambulation. Mfap2 (-/-) mice were, therefore, used as a model to associate parameters of metabolic disease, bone remodeling, and hematopoiesis with MAT expansion. Marrow adiposity was normal in Mfap2 (-/-) mice until 6 months of age; however, by 10 months, marrow fat volume had increased fivefold relative to wild-type control at the same age. Increased gonadal fat pad mass and hyperglycemia were detectable in Mfap2 (-/-) mice by 2 months, but peaked by 6 months. The development of insulin resistance coincided with MAT expansion. Longitudinal characterization of bone mass demonstrated a disconnection in MAT volume and bone volume. Specifically, Mfap2 (-/-) mice had reduced trabecular bone volume by 2 months, but this phenotype did not progress with age or MAT expansion. Interestingly, MAT expansion in the 10-month-old Mfap2 (-/-) mice was associated with modest alterations in basal hematopoiesis, including a shift from granulopoiesis to B lymphopoiesis. Together, these findings indicate MAT expansion is coincident with insulin resistance, but not excess peripheral adiposity or hyperglycemia in Mfap2 (-/-) mice; and substantial MAT accumulation does

  15. Determination of multielements by neutron activation analysis using a coincidence counting method

    International Nuclear Information System (INIS)

    When γ-rays are counted using γ-ray spectrometry for neutron activation analysis (NAA), the Compton continuum from high-energy γ-rays often interferes with the detection of nuclides with lower energy γ-rays. A coincidence counting of γ-rays in the cascade series with a coaxial Ge detector and a well-type NaI(Tl) detector can reduce this problem. The coincidence counting method was applied to the determination of Se, Hf, Ba, Cs, Co, Sb and Sc in 3 kinds of certified reference materials (NIES CRM No.16 river sediment, NIES/NIRS typical Japanese diet CRM and NIES/WAMRL fish otolith CRM) and 10 kind of iron remains excavated at the ruins of Kaman-Kalehoyuk in Turkey. These samples and comparative standards were irradiated for 6 h at a thermal neutron flux of 3.7 x 1012 n cm-2s-1 in the Rikkyo University Research Reactor (TRIGA Mark-II, 100 kW). The irradiated samples were counted by multiparameter MCA (LN-9000, Laboratory Equipment Corporation). A coaxial Ge detector (relative efficiency of 21% and FWHM of 1.8 keV at 1332 keV) was used for the conventional counting method. For the coincidence counting method, the coaxial Ge detector along with a well-type NaI(Tl) detector (6 in.φ x 6 in., well 3 in.φ x 4 in.) was used. Using this method to determine Se, Hf, Ba, Cs, Co, Sb and Sc, the lower limit of the determination was improved by 2-4 times compared with the conventional counting method using the coaxial Ge detector. The determined values were in good agreement with the certified values. (author)

  16. Pathological α-synuclein distribution in subjects with coincident Alzheimer's and Lewy body pathology.

    Science.gov (United States)

    Toledo, Jon B; Gopal, Pallavi; Raible, Kevin; Irwin, David J; Brettschneider, Johannes; Sedor, Samantha; Waits, Kayla; Boluda, Susana; Grossman, Murray; Van Deerlin, Vivianna M; Lee, Edward B; Arnold, Steven E; Duda, John E; Hurtig, Howard; Lee, Virginia M-Y; Adler, Charles H; Beach, Thomas G; Trojanowski, John Q

    2016-03-01

    We investigated the distribution patterns of Lewy body-related pathology (LRP) and the effect of coincident Alzheimer disease (AD) pathology using a data-driven clustering approach that identified groups with different LRP pathology distributions without any diagnostic or researcher's input in two cohorts including: Parkinson disease patients without (PD, n = 141) and with AD (PD-AD, n = 80), dementia with Lewy bodies subjects without AD (DLB, n = 13) and demented subjects with AD and LRP pathology (Dem-AD-LB, n = 308). The Dem-AD-LB group presented two LRP patterns, olfactory-amygdala and limbic LRP with negligible brainstem pathology, that were absent in the PD groups, which are not currently included in the DLB staging system and lacked extracranial LRP as opposed to the PD group. The Dem-AD-LB individuals showed relative preservation of substantia nigra cells and dopamine active transporter in putamen. PD cases with AD pathology showed increased LRP. The cluster with occipital LRP was associated with non-AD type dementia clinical diagnosis in the Dem-AD-LB group and a faster progression to dementia in the PD groups. We found that (1) LRP pathology in Dem-AD-LB shows a distribution that differs from PD, without significant brainstem or extracranial LRP in initial phases; (2) coincident AD pathology is associated with increased LRP in PD indicating an interaction; (3) LRP and coincident AD pathology independently predict progression to dementia in PD, and (4) evaluation of LRP needs to acknowledge different LRP spreading patterns and evaluate substantia nigra integrity in the neuropathological assessment and consider the implications of neuropathological heterogeneity for clinical and biomarker characterization. PMID:26721587

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

    International Nuclear Information System (INIS)

    The 111In and 99mTc standardization in a 4πβ-γ coincidence system is described. The 111In was produced by the reaction of 111Cd (p, n) 111In in the cyclotron. The 111In decays with a half life of 2.8 days by electron capture process, populating the excited levels of 111Cd, emitting two main gamma rays with energies of 171 keV and 245 keV. The 99mTc decay with a half life of 6.007 h for isomeric transition, from the radioactive decay of 99Mo. 111In 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 99mTc 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 111In two solutions agree with the results obtained by Monte Carlo simulation. The experimental activities of 99mTc for the two gamma windows are in agreement within the experimental uncertainty, indicating that the adopted methodology is adequate. (author)

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

    International Nuclear Information System (INIS)

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

  19. Coincidence detection of convergent perforant path and mossy fibre inputs by CA3 interneurons.

    Science.gov (United States)

    Calixto, Eduardo; Galván, Emilio J; Card, J Patrick; Barrionuevo, Germán

    2008-06-01

    We performed whole-cell recordings from CA3 s. radiatum (R) and s. lacunosum-moleculare (L-M) interneurons in hippocampal slices to examine the temporal aspects of summation of converging perforant path (PP) and mossy fibre (MF) inputs. PP EPSPs were evoked from the s. lacunosum-moleculare in area CA1. MF EPSPs were evoked from the medial extent of the suprapyramidal blade of the dentate gyrus. Summation was strongly supralinear when examining PP EPSP with MF EPSP in a heterosynaptic pair at the 10 ms ISI, and linear to sublinear at longer ISIs. This pattern of nonlinearities suggests that R and L-M interneurons act as coincidence detectors for input from PP and MF. Summation at all ISIs was linear in voltage clamp mode demonstrating that nonlinearities were generated by postsynaptic voltage-dependent conductances. Supralinearity was not detected when the first EPSP in the pair was replaced by a simulated EPSP injected into the soma, suggesting that the conductances underlying the EPSP boosting were located in distal dendrites. Supralinearity was selectively eliminated with either Ni2+ (30 microm), mibefradil (10 microm) or nimodipine (15 microm), but was unaffected by QX-314. This pharmacological profile indicates that supralinearity is due to recruitment of dendritic T-type Ca2+channels by the first subthreshold EPSP in the pair. Results with the hyperpolarization-activated (Ih) channel blocker ZD 7288 (50 microm) revealed that Ih restricted the time course of supralinearity for coincidently summed EPSPs, and promoted linear to sublinear summation for asynchronous EPSPs. We conclude that coincidence detection results from the counterbalanced activation of T-type Ca2+ channels and inactivation of Ih. PMID:18388134

  20. Electric charge quantization

    International Nuclear Information System (INIS)

    Experimentally it has been known for a long time that the electric charges of the observed particles appear to be quantized. An approach to understanding electric charge quantization that can be used for gauge theories with explicit U(1) factors - such as the standard model and its variants - is pedagogically reviewed and discussed in this article. This approach used the allowed invariances of the Lagrangian and their associated anomaly cancellation equations. It is demonstrated that charge may be de-quantized in the three-generation standard model with massless neutrinos, because differences in family-lepton-numbers are anomaly-free. The relevant experimental limits are also reviewed. This approach to charge quantization suggests that the minimal standard model should be extended so that family-lepton-number differences are explicitly broken. Some candidate extensions such as the minimal standard model augmented by Majorana right-handed neutrinos are also briefly discussed. 30 refs

  1. Primitive Virtual Negative Charge

    CERN Document Server

    Kim, Kiyoung

    2008-01-01

    Physical fields, such as gravity and electromagnetic field, are interpreted as results from rearrangement of vacuum particles to get the equilibrium of net charge density and net mass density in 4-dimensional complex space. Then, both fields should interact to each other in that physical interaction is considered as a field-to-field interaction. Hence, Mass-Charge interaction is introduced with primitive-virtual negative charge defined for the mass. With the concept of Mass-Charge interaction electric equilibrium of the earth is discussed, especially about the electric field and magnetic field of the earth. For unsettled phenomena related with the earth's gravity, such as antigravity phenomenon, gravity anomalies during the solar eclipses, the connection between geomagnetic storms and earthquakes, etc., possible explanations are discussed.

  2. Space-Charge Effect

    CERN Document Server

    Chauvin, N

    2013-01-01

    First, this chapter introduces the expressions for the electric and magnetic space-charge internal fields and forces induced by high-intensity beams. Then, the root-mean-square equation with space charge is derived and discussed. In the third section, the one-dimensional Child-Langmuir law, which gives the maximum current density that can be extracted from an ion source, is exposed. Space-charge compensation can occur in the low-energy beam transport lines (located after the ion source). This phenomenon, which counteracts the spacecharge defocusing effect, is explained and its main parameters are presented. The fifth section presents an overview of the principal methods to perform beam dynamics numerical simulations. An example of a particles-in-cells code, SolMaxP, which takes into account space-charge compensation, is given. Finally, beam dynamics simulation results obtained with this code in the case of the IFMIF injector are presented.

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

    International Nuclear Information System (INIS)

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

  4. Application of neutron well coincidence counting for plutonium determination in mixed oxide fuel fabrication plant

    International Nuclear Information System (INIS)

    Mixed oxide (MOX) fuel is an alternative to conventional enriched uranium oxide fuel in thermal reactors. Indian interest in plutonium recycle in thermal reactors is primarily due to the need to develop alternative indigenous fuel for two boiling water reactors (BWR) at Tarapur, which are designed to use imported light enriched uranium fuel. A few MOX assemblies have been fabricated and loaded into the reactors. Neutron well coincidence counting (NWCC) system has been successfully employed to check the enrichments of PuO2 in MOX blends. NWCC has also been successfully applied in developing dry recycling process of clean rejected oxide (CRO) and dirty rejected oxide (DRO). (author)

  5. Evaluation Of The Coincidence Of Male Pattern Baldness And Pityrosporum Group Of Fungus In Iran

    OpenAIRE

    Javanbakht Arash; Famili Sorour; Amirmajdi Monireh Mokhtari

    2002-01-01

    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...

  6. 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

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

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

    2004-01-01

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

  9. Flow structure from a horizontal cylinder coincident with a free surface in shallow water flow

    OpenAIRE

    Kahraman Ali; Özgören Muammer; Şahin Beşir

    2012-01-01

    Vortex formation from a horizontal cylinder coincident with a free surface of a shallow water flow having a depth of 25.4 [mm] was experimentally investigated using the PIV technique. Instantaneous and time-averaged flow patterns in the wake region of the cylinder were examined for three different cylinder diameter values under the fully developed turbulent boundary layer condition. Reynolds numbers were in the range of 1124£ Re£ 3374 and Froude numbers were in the range of 0.41 £ Fr £ ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-15

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2016-03-01

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

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

    CERN Document Server

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

    2001-01-01

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

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

    International Nuclear Information System (INIS)

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

  16. Experimental comparison of the active well coincidence counter with the random driver

    International Nuclear Information System (INIS)

    A direct comparison has been made between the IAEA Active Well Coincidence Counter (AWCC) and the LASL Random Driver at CMB-8. The comparison included an experimental evaluation of precision, counting rate, accuracy, penetrability, stability, and the effect of sample inhomogeneity. Samples used in the evaluation included highly enriched U3O8, U3O8 mixed with graphite, highly enriched uranium metal discs, and depleted uranium metal. These materials are typical of the samples of interest to the IAEA inspectors. It is concluded that the two instruments had very similar performance characteristics with the Random Driver giving better penetrability and the AWCC giving better stability

  17. Analysis of 18F-FDG maximum standardized uptake value in gastric cancer with coincidence imaging

    International Nuclear Information System (INIS)

    Objective: To investigate the value of 18F-FDG SUVmax in gastric cancer diagnosis with coincidence imaging. Methods: The coincidence imaging was performed in 92 patients with gastric diseases (60 males, 32 females,age 65 (32-85) years; 78 malignant cases, 14 benign cases). The malignant cases included 3 remnant gastric cancers and 75 primary gastric cancers (staging: 4 of Tis, 13 of T1, 9 of T2, 33 of T3, 11 of T4 and 5 without surgery). The well-, moderately-and poorly-differentiated adenocarcinomas were 22, 15 and 28, respectively. Images were analyzed retrospectively with visual method and 18F-FDG SUVmax, and the diagnostic results were compared with the histopathological findings. The ROC curve was used to analyze the SUVmax. The Pearson's correlation analysis was performed to evaluate the relationship between SUVmax and tumor size. The Wilcoxon rank sum test was applied to determine the difference of SUVmax between early and advanced gastric cancers. The Kruskal-Wallis test was used to analyze the difference of SUVmax in various types of differentiated adenocarcinoma. Results: No matter visual method or SUVmax was used, the sensitivity, specificity and accuracy of coincidence imaging in diagnosis of gastric cancer were 64.1% (50/78), 64.3% (9/14) and 64.1% (59/92), respectively. The AUC of SUVmax was 0.695 and the cut-off value was 0.700. SUVmax Was positively correlated with tumor size significantly (r=0.489, P<0.001). There was statistically significant difference between SUVmax of Tis-1 and that of T2-4 (0.676± 1.288 vs 3.851 ±3.764; Z=-3.754, P<0.001). However, there was no statistically significant difference among SUVmax of various grades of differentiated adenocarcinoma(2.805±4.008, 3.447±2.365, 3.413± 3.737; χ2=2.459, P> 0.05). Conclusions: SUVmax provides more information than visual method in assessing gastric cancer with 18F-FDG coincidence imaging. Appropriate cut-off value of SUV is necessary for improvement of the diagnostic efficiency

  18. Interaction between Dark Matter and Dark Energy and the Cosmological Coincidence Problem

    Directory of Open Access Journals (Sweden)

    Kourosh Nozari

    2014-01-01

    Full Text Available We consider a quintessence model of dark energy inspired by scalar-tensor theories of gravity where the scalar field is nonminimally coupled to gravity and dark matter. By considering exponential potential as self-interaction potential, the stability and existence of the critical points are discussed in details. With nonminimally coupled dark sector with gravity, we obtain scaling solutions to address the coincidence problem by considering complex velocity for dark matter. The statefinder diagnostic shows that the equation of state reaches ΛCDM model in the future.

  19. An application of the coincidence Doppler spectroscopy for substances of chemical interest: phthalocyanine and acetylacetonate complexes

    CERN Document Server

    Ito, Y

    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.

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

    Science.gov (United States)

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

    2005-05-01

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

  1. The Concept of the Cultural Region and the Importance of Coincidence between Administrative and Cultural Regions

    OpenAIRE

    PETER JORDAN

    2005-01-01

    After browsing the principal terms of geographical regions like structural and functional regions, the paper highlights the term “cultural region” as a manifestation of a certain culture in the landscape on the one hand and as a factor of shaping cultural identity on the other. The very point and message of the paper is to emphasize that it was an advantage, if administrative regions, i.e. a subtype of functional regions, would coincide with cultural regions, i.e. a subtype of structural regi...

  2. 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.

  3. On the potential of active coincidence counting using a spontaneous fission source to induce fission

    International Nuclear Information System (INIS)

    Using the one-group point-model equations as a guide, we compare the active neutron Doubles rate from a multiplying item interrogated with a spontaneous fission neutron source with that of a random neutron source of equal emission rate. We find that, especially for highly multiplying items, 252Cf is likely to provide a viable alternative to the commonly used Am/Li interrogation source. We conclude that detailed design studies and experiments are warranted to develop this concept into practical assay tools. Keywords: coincidence counting; active interrogation; 252Cf active driver; point-model; collar detector

  4. Coincidence of remission of postpartum Graves' disease and use of omega-3 fatty acid supplements

    Directory of Open Access Journals (Sweden)

    Breese McCoy Sarah J

    2011-11-01

    Full Text Available Abstract I developed Graves' Disease four months postpartum. After one year on propylthiouracil, I learned that omega-3 fatty acids may reduce inflammation associated with certain autoimmune disorders, although no investigations for thyroiditis have been reported. Within eight weeks of beginning flaxseed oil supplements, TSH levels normalized, but fell somewhat when flaxseed was decreased and PTU discontinued. During another pregnancy, plasma TSH normalized, but was again suppressed by four weeks postpartum, then undetectable by four months. This time, flaxseed supplementation alone coincided with TSH normalization. Omega-3 fatty acids should be investigated as a potential treatment for autoimmune thyroid disease.

  5. Charge-sensitive amplifier

    OpenAIRE

    Startsev V. I.; Yampolsky Ju. S.

    2008-01-01

    The authors consider design and circuit design techniques of reduction of the influence of the pyroelectric effect on operation of the charge sensitive amplifiers. The presented experimental results confirm the validity of the measures taken to reduce the impact of pyroelectric currents. Pyroelectric currents are caused by the influence of the temperature gradient on the piezoelectric sensor and on the output voltage of charge sensitive amplifiers.

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

    International Nuclear Information System (INIS)

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

  7. Value of coincidence gamma camera PET in tumors of the thorax and abdomen and assessment of myocardial viability

    International Nuclear Information System (INIS)

    In this paper we report our experience of the usefulness of FDG scanning using a gamma camera equipped with coincidence detection for staging lung cancer and in the follow-up of patients with colorectal cancer. We also tested the diagnostic accuracy of cardiac FDG imaging. Our results demonstrate that, although a coincidence camera is technically inferior to a dedicated PET scanner, it may provide clinically useful results in situations were a lesion of sufficient size and FDG-uptake is to be expected. In patients with chronic ischemic cardiomyopathy coincidence PET can be introduced into clinical practice for the assessment of myocardial viability. (orig.)

  8. The use of coincidence counting mass spectrometry to study the emission and metastable dissociation of cluster ions

    Science.gov (United States)

    Van Stipdonk, M. J.; Schweikert, E. A.

    1996-05-01

    Coincidence counting and time-of-flight mass spectrometry were used to study the coincidental emission of ions from single fission fragment, impacts from an inorganic solid. Removal of interfering peaks is possible by observing those ions in coincidence with a mass peak unambiguously representative of the sample of interest. The use of coincidence also allows a direct study of the correlation of ions and neutrals formed due to the metastable dissociation of ions while in the drift region of the spectrometer. Such studies allow insight into the structure of cluster ions, which can aid in relating the cluster ion composition and structure back to that of the original solid.

  9. MOSFET Electric-Charge Sensor

    Science.gov (United States)

    Robinson, Paul A., Jr.

    1988-01-01

    Charged-particle probe compact and consumes little power. Proposed modification enables metal oxide/semiconductor field-effect transistor (MOSFET) to act as detector of static electric charges or energetic charged particles. Thickened gate insulation acts as control structure. During measurements metal gate allowed to "float" to potential of charge accumulated in insulation. Stack of modified MOSFET'S constitutes detector of energetic charged particles. Each gate "floats" to potential induced by charged-particle beam penetrating its layer.

  10. Gaseous charge transfer reactions of multiply charged ions

    International Nuclear Information System (INIS)

    Doubly charged ions produced in electron impact ionization have received relatively little study due to their low abundance and masking from singly charged ions which are detected at the same mass-to-charge ratio by a mass spectrometer. This interference problem was avoided by exploiting a technique in which doubly charged molecular and fragment ions are monitored using a collisional charge-exchange process where only fast singly charged product ions are allowed to reach the detector. Primary research efforts were to determine structures and energetics of multiply charged ions formed in high energy electron impact ionization processes and their reactivities in ion-molecule charge exchange interactions. Doubly charged ion mass distributions for various chemical classes (including acetylenes, alkenes, terpenes and organophosphorus compounds) were recorded and appearance energies of prominent doubly charged ions were measured. Computer molecular orbital calculations (at the MINDO/3 level) of ionic structures, energies and charge distributions were utilized to augment the analysis of experimental results

  11. Energy loss of charged particles colliding with an oscillator

    Science.gov (United States)

    Makarov, D. N.

    2015-04-01

    Energy loss of fast charged particles colliding with an oscillator is considered in the dipole approximation. In this approximation, the problem is solved exactly and the energy loss of the oscillator from the initial state | m> = |0> is found in the form of the sum of single integrals. It is shown that passing to the limit, the Bethe theory for an atom with small perturbations can be obtained, and in the case of strong fields, the correction to the Bethe theory, analogous to the Bloch correction, can be calculated; in addition, a classical limit coinciding with the Bohr formula is possible.

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

    CERN Document Server

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

    2015-01-01

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

  14. Fragment ion-photon coincidence investigation of carbon tetrafluoride by controlled electron impact

    International Nuclear Information System (INIS)

    Fragment ion-photon coincidence (FIPCO) spectra by 120 eV electron impact on carbon tetrafluoride (CF4) have been observed, in which optical emission in the 200-600 nm region has been detected. Only the CF3+ fragment has been found in the FIPCO spectra, demonstrating that the dissociative double-ionization process producing a pair of CF3+ and F+ is negligible in the correlation with the optical emission. This finding was already known from photon-impact experiments, but such a process was expected to play an important role in the ultraviolet-visible emission by electron impact on CF4. The translational energy distribution of CF3+ has also been estimated on the basis of the high-resolution FIPCO spectra and their Monte Carlo simulation. The magnitude of the mean translational energy of CF3+ has been explained together with earlier results obtained through threshold photoelectron-photoion coincidence experiments by considering the Franck-Condon region in the transition among the neutral ground state of CF4 and its ionic A, C and D states. (author)

  15. 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.

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

    Science.gov (United States)

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

    2012-01-01

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

  17. The coincidence matrix ASIC of the level-1 muon barrel trigger of the ATLAS experiment

    CERN Document Server

    Bocci, V; Salamon, A; Vari, R; Veneziano, Stefano

    2003-01-01

    The ATLAS barrel level-1 muon trigger processes hit information from the resistive plate chamber detector, identifying candidate muon tracks and assigning them to a programmable p/sub T/ range and to a unique bunch crossing number. The trigger system uses up to seven detector layers and seeks hit patterns compatible with muon tracks in the bending and nonbending projection. The basic principle of the algorithm is to demand a coincidence of hits in the different chamber layers within a path. The width of the road is related to the p/sub T / threshold to be applied. The system is split into an on-detector and an off-detector part. The on-detector electronics reduces the information from about 350 k channels to about 400 32-bit data words sent via optical fiber to the so-called sector logic (SL). The off- detector SL electronics collects muon candidates and associates them to detector regions-of-interest of Delta eta * Delta Phi of 0.1*0.1. The core of the on-detector electronics is the coincidence matrix ASIC (...

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang, T F

    2012-05-24

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

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

    International Nuclear Information System (INIS)

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

  20. Coincidence of calcified carotid atheromatous plaque, osteoporosis, and periodontal bone loss in dental panoramic radiographs

    International Nuclear Information System (INIS)

    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. Rejection of randomly coinciding events in ZnMoO4 scintillating bolometers

    International Nuclear Information System (INIS)

    Random coincidence of events (particularly from two neutrino double beta decay) could be one of the main sources of background in the search for neutrinoless double beta decay with cryogenic bolometers due to their poor time resolution. Pulse-shape discrimination by using front edge analysis, mean-time and χ2 methods were applied to discriminate randomly coinciding events in ZnMoO4 cryogenic scintillating bolometers. These events can be effectively rejected at the level of 99 % by the analysis of the heat signals with rise-time of about 14 ms and signal-to-noise ratio of 900, and at the level of 92 % by the analysis of the light signals with rise-time of about 3 ms and signal-to-noise ratio of 30, under the requirement to detect 95 % of single events. These rejection efficiencies are compatible with extremely low background levels in the region of interest of neutrinoless double beta decay of 100Mo for enriched ZnMoO4 detectors, of the order of 10-4 counts/(y keV kg). Pulse-shape parameters have been chosen on the basis of the performance of a real massive ZnMoO4 scintillating bolometer. Importance of the signal-to-noise ratio, correct finding of the signal start and choice of an appropriate sampling frequency are discussed. (orig.)

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

    International Nuclear Information System (INIS)

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

  3. Clinical value of 18F-FDG coincidence imaging for patients with fever of unknown origin

    International Nuclear Information System (INIS)

    Objective: The aim of this study was to assess the clinical value of 18F-fluorodeoxyglucose (FDG) coincidence imaging in the diagnosis of fever of unknown origin (FUO). Methods: Fifty-eight patients with FUO (temperature>38.3 degree C, fever more than 3 weeks) underwent SPECT imaging with 18F-FDG. Region of interest (ROI) was drawn over the lesions (L) and contralateral or adjacent normal tissue (B). The radioactivity ratio L/B was calculated for both benign and malignant pathologies and compared by t test. Results In 48 patients(83%), at least one site of abnormal 18F-FDG accumulation on SPECT was found, which led to the final diagnosis of malignant disease in 20 patients, and infectious or other benign disease in 23 patients. Five patients remained unknown.Four in 10 (17%) cases with negative 18F-FDG SPECT were later proven as infectious disease (2 with urinary tract infection, 2 with lymphadenitis); 3 were found to have connective tissue and collagen disease (1 with rheumatism, 1 with adult onset still's disease. 1 with systemic lupus erythematosus); while the last 3 remained unknown. The L/B ratio of benign foci was 1.93 ± 0.39, and that of malignant foci was 3.58 ± 1.01 (statistically significant difference with t=6.955. P18F-FDG coincidence imaging is valuable in the diagnosis for FUO. (authors)

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

    Science.gov (United States)

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

    2008-07-01

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

  5. Loss of CDKN2A Promoter Methylation Coincides With the Epigenetic Transdifferentiation of Uterine Myosarcomatous Cells.

    Science.gov (United States)

    Roncati, Luca; Barbolini, Giuseppe; Sartori, Giuliana; Siopis, Elena; Pusiol, Teresa; Maiorana, Antonio

    2016-07-01

    Leiomyosarcoma is the most common type of uterine sarcoma and usually displays typical morphology. Heterologous leiomyosarcoma is the rarest variant, in which the tumor contains liposarcomatous, osteosarcomatous, or rhabdomyosarcomatous components. We have investigated the largest series of uterine leiomyosarcoma with a rhabdomyosarcomatous component and we have disclosed a molecular finding, which coincides to the process of transdifferentiation from smooth muscle into striated muscle phenotype. The surgical specimens of 5 rare cases of uterine leiomyosarcoma with a rhabdomyosarcomatous component were formalin fixed and paraffin embedded. In addition to hematoxylin/eosin stains, phosphotungstic acid hematoxylin staining, immunohistochemistry, and methylation-specific polymerase chain reaction the CDKN2A promoter region were performed. Leiomyosarcomatous cells were found to be strongly immunoreactive for both desmin and α-smooth muscle actin. Rhabdomyosarcomatous cells were immunoreactive for sarcomeric actin, desmin, vimentin, CD10, and p16. The methylation-specific polymerase chain reaction revealed the presence of a methylated allele and an unmethylated allele in the microdissected samples, coming from leiomyosarcomatous cells. On the contrary, 2 unmethylated alleles, molecular expression of a loss of heterozygosity, were detected in all the microdissected samples in the rhabdomyosarcomatous cells. The loss of heterozygosity methylation in the promoter region of the CDKN2A gene, occurred only in the rhabdomyosarcomatous cells with increases in both p16 and p14 expression. This event may result in an inhibition of cdk4/cdk6 activity, stabilizes the tumor suppressor protein p53, and coincides with the transdifferentiation from smooth muscle into striated muscle. PMID:27276112

  6. Fast Neutron Dose Evaluation Using CR39 by Coincidence Counting Process

    Science.gov (United States)

    Vilela, Eudice; Brandão, J. O. C.; Santos, J. A. L.; de Freitas, F. F.

    2008-08-01

    The solid state nuclear tracks detection (SSNTD) technique is widely used in the area of radiation dosimetry. Different materials can be used applying this technique as glass and the most used in the dosimetry field that are the polycarbonates, CR39 and Makrofol-DE. Both are very rich in hydrogenous, that enables the SSNTD to detect fast neutrons through recoils of protons in the own detector material, without need of converters. The low reproducibility of its backgroundhas often been the major drawback in the assessment of low fluences of fast neutrons with SSNTDs. This problem can be effectively solved by counting coincidence of tracks in two detectors foils irradiated in close contact. After processing and counting only tracks produced by the same recoil nuclei on the surfaces of both detectors are considered as a track. This procedure enables the reduction of the background counts in the response of the detectors. In this work a preliminary study on the application of the coincidence technique for neutron dosimetry is presented. The CR39 material was investigated aiming to achieve the personal dose equivalent for fast neutrons. Using this method of analysis a significant reduction on the lower detectable dose was observed resulting even one order of magnitude smaller value. Reading, however, needs to be automated due to the large areas necessary to achieve a satisfactory number of tracks for statistical significance of results.

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

    International Nuclear Information System (INIS)

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

  8. Cerebellar Dysfunction and Ataxia in Patients with Epilepsy: Coincidence, Consequence, or Cause?

    Science.gov (United States)

    Filip, Pavel; Bareš, Martin; Brázdil, Milan

    2016-01-01

    Basic epilepsy teachings assert that seizures arise from the cerebral cortex, glossing over infratentorial structures such as the cerebellum that are believed to modulate rather than generate seizures. Nonetheless, ataxia and other clinical findings in epileptic patients are slowly but inevitably drawing attention to this neural node. Tracing the evolution of this line of inquiry from the observed coincidence of cerebellar atrophy and cerebellar dysfunction (most apparently manifested as ataxia) in epilepsy to their close association, this review considers converging clinical, physiological, histological, and neuroimaging evidence that support incorporating the cerebellum into epilepsy pathology. We examine reports of still controversial cerebellar epilepsy, studies of cerebellar stimulation alleviating paroxysmal epileptic activity, studies and case reports of cerebellar lesions directly associated with seizures, and conditions in which ataxia is accompanied by epileptic seizures. Finally, the review substantiates the role of this complex brain structure in epilepsy whether by coincidence, as a consequence of deleterious cortical epileptic activity or antiepileptic drugs, or the very cause of the disease. PMID:27375960

  9. Rejection of randomly coinciding events in ZnMoO{sub 4} scintillating bolometers

    Energy Technology Data Exchange (ETDEWEB)

    Chernyak, D.M. [Institute for Nuclear Research, Kyiv (Ukraine); Centre de Sciences Nucleaires et de Sciences de la Matiere, Orsay (France); Danevich, F.A.; Tretyak, V.I. [Institute for Nuclear Research, Kyiv (Ukraine); Giuliani, A.; Mancuso, M. [Centre de Sciences Nucleaires et de Sciences de la Matiere, Orsay (France); Dipartimento di Scienza e Alta Tecnologia dell' Universita dell' Insubria, Como (Italy); Nones, C. [Service de Physique des Particules, CEA-Saclay, Gif sur Yvette (France); Olivieri, E.; Tenconi, M. [Centre de Sciences Nucleaires et de Sciences de la Matiere, Orsay (France)

    2014-06-15

    Random coincidence of events (particularly from two neutrino double beta decay) could be one of the main sources of background in the search for neutrinoless double beta decay with cryogenic bolometers due to their poor time resolution. Pulse-shape discrimination by using front edge analysis, mean-time and χ{sup 2} methods were applied to discriminate randomly coinciding events in ZnMoO{sub 4} cryogenic scintillating bolometers. These events can be effectively rejected at the level of 99 % by the analysis of the heat signals with rise-time of about 14 ms and signal-to-noise ratio of 900, and at the level of 92 % by the analysis of the light signals with rise-time of about 3 ms and signal-to-noise ratio of 30, under the requirement to detect 95 % of single events. These rejection efficiencies are compatible with extremely low background levels in the region of interest of neutrinoless double beta decay of {sup 100}Mo for enriched ZnMoO{sub 4} detectors, of the order of 10{sup -4} counts/(y keV kg). Pulse-shape parameters have been chosen on the basis of the performance of a real massive ZnMoO{sub 4} scintillating bolometer. Importance of the signal-to-noise ratio, correct finding of the signal start and choice of an appropriate sampling frequency are discussed. (orig.)

  10. Beyond contact-based transmission networks: the role of spatial coincidence.

    Science.gov (United States)

    Richardson, Thomas O; Gorochowski, Thomas E

    2015-10-01

    Animal societies rely on interactions between group members to effectively communicate and coordinate their actions. To date, the transmission properties of interaction networks formed by direct physical contacts have been extensively studied for many animal societies and in all cases found to inhibit spreading. Such direct interactions do not, however, represent the only viable pathways. When spreading agents can persist in the environment, indirect transmission via 'same-place, different-time' spatial coincidences becomes possible. Previous studies have neglected these indirect pathways and their role in transmission. Here, we use rock ant colonies, a model social species whose flat nest geometry, coupled with individually tagged workers, allowed us to build temporally and spatially explicit interaction networks in which edges represent either direct physical contacts or indirect spatial coincidences. We show how the addition of indirect pathways allows the network to enhance or inhibit the spreading of different types of agent. This dual-functionality arises from an interplay between the interaction-strength distribution generated by the ants' movement and environmental decay characteristics of the spreading agent. These findings offer a general mechanism for understanding how interaction patterns might be tuned in animal societies to control the simultaneous transmission of harmful and beneficial agents. PMID:26400200

  11. 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

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

    OpenAIRE

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

    2010-01-01

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

  13. Highly Charged Ion Sources

    International Nuclear Information System (INIS)

    In this work a study is made for the factors affecting the production and extraction of highly charged ion beams. Discussion is made for the production of highly charged ions from: the conventional vacuum are ion sources (Pinning PIG and Duoplasmatron DP) and the recent trends type which are (Electron Beam Ion Sources EBIS, Electron Cyclotron Resonance Ion Sources ECRIS and Laser Ion source LIS). The highly charged ions with charge state +7 , O+8 ,Ne+10 , Ar+18 have been extracted from the ECRIS while fully stripped Xe+54 has been extracted from EBIS. Improving the capabilities of the conventional RF ion source to produce multiply charged ions is achieved through the use of electron injection into the plasma or with the use of RF driven ion source. The later is based on coupling the RF power to the discharge through an internal antenna in vacuum are ion source. The argon ion species extracted from these upgraded RF ion sources could reach Ar+5

  14. Coincidence and coherent data analysis methods for gravitational wave bursts in a network of interferometric detectors

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-07-01

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

  16. Effects of Calcium Spikes in the Layer 5 Pyramidal Neuron on Coincidence Detection and Activity Propagation

    Science.gov (United States)

    Chua, Yansong; Morrison, Abigail

    2016-01-01

    The role of dendritic spiking mechanisms in neural processing is so far poorly understood. To investigate the role of calcium spikes in the functional properties of the single neuron and recurrent networks, we investigated a three compartment neuron model of the layer 5 pyramidal neuron with calcium dynamics in the distal compartment. By performing single neuron simulations with noisy synaptic input and occasional large coincident input at either just the distal compartment or at both somatic and distal compartments, we show that the presence of calcium spikes confers a substantial advantage for coincidence detection in the former case and a lesser advantage in the latter. We further show that the experimentally observed critical frequency phenomenon, in which action potentials triggered by stimuli near the soma above a certain frequency trigger a calcium spike at distal dendrites, leading to further somatic depolarization, is not exhibited by a neuron receiving realistically noisy synaptic input, and so is unlikely to be a necessary component of coincidence detection. We next investigate the effect of calcium spikes in propagation of spiking activities in a feed-forward network (FFN) embedded in a balanced recurrent network. The excitatory neurons in the network are again connected to either just the distal, or both somatic and distal compartments. With purely distal connectivity, activity propagation is stable and distinguishable for a large range of recurrent synaptic strengths if the feed-forward connections are sufficiently strong, but propagation does not occur in the absence of calcium spikes. When connections are made to both the somatic and the distal compartments, activity propagation is achieved for neurons with active calcium dynamics at a much smaller number of neurons per pool, compared to a network of passive neurons, but quickly becomes unstable as the strength of recurrent synapses increases. Activity propagation at higher scaling factors can be

  17. Space charge dominated beams

    International Nuclear Information System (INIS)

    After an introductory section on the relationship between emittance and beam Coulomb energy we discuss the properties of space charge dominated beams in progressive steps: from uniformly charged bunched beams to non-uniformly charged beams to correlation effects between particles (simulation beams or 'crystalline' beams). A practical application can be found in the beam dynamics of a high-current injector. The concept of correlation energy is of practical interest in computer simulation of high-brilliance beams, where one deals with an artificially enhanced two-particle Coulomb energy, if many real particles are combined into one simulation super-particle. This can be a source of non-physical emittance growth. (orig./HSI)

  18. Sources for charged particles

    International Nuclear Information System (INIS)

    This document is a basic course on charged particle sources for post-graduate students and thematic schools on large facilities and accelerator physics. A simple but precise description of the creation and the emission of charged particles is presented. This course relies on every year upgraded reference documents. Following relevant topics are considered: electronic emission processes, technological and practical considerations on electron guns, positron sources, production of neutral atoms, ionization, plasma and discharge, different types of positive and negative ion sources, polarized particle sources, materials for the construction of ion sources, low energy beam production and transport. (N.T.)

  19. Charged conformal Killing spinors

    International Nuclear Information System (INIS)

    We study the twistor equation on pseudo-Riemannian Spinc-manifolds whose solutions we call charged conformal Killing spinors (CCKSs). We derive several integrability conditions for the existence of CCKS and study their relations to spinor bilinears. A construction principle for Lorentzian manifolds admitting CCKS with nontrivial charge starting from CR-geometry is presented. We obtain a partial classification result in the Lorentzian case under the additional assumption that the associated Dirac current is normal conformal and complete the classification of manifolds admitting CCKS in all dimensions and signatures ≤5 which has recently been initiated in the study of supersymmetric field theories on curved space

  20. Time-and-frequency gated photon coincidence counting; a novel multidimensional spectroscopy tool

    CERN Document Server

    Dorfman, Konstantin E

    2016-01-01

    Coherent multidimensional optical spectroscopy techniques are broadly applied across the electromagnetic spectrum ranging from NMR to the UV. These reveal properties of matter through correlation plots of signal fields generated in response to sequences of short pulses with variable delays. Here we discuss a new class of multidimensional techniques obtained by time-and-frequency resolved photon coincidence counting measurements of N photons which constitutes a 2N dimensional spectrum. A compact description of these signals is developed based on time ordered superoperators rather than the normally ordered ordinary operators used in Glauber's photon counting formalism. The independent control of the time and frequency gate parameters reveals details of matter dynamics not available otherwise. Application to an anharmonic oscillator model with fluctuating energy and anharmonicity demonstrates the power of these signals.

  1. Coincidence Doppler broadening study of Eurofer 97 irradiated in spallation environment

    Science.gov (United States)

    Sabelová, V.; Kršjak, V.; Kuriplach, J.; Dai, Y.; Slugeň, V.

    2015-03-01

    The behavior of transmutation helium during isochronal annealing of irradiated Eurofer 97 was investigated using coincidence Doppler broadening spectroscopy (CDBS). The investigated ferritic martensitic steel was irradiated in 2000 and 2001 in the frame of the STIP-II project at the Swiss neutron spallation source (SINQ) (irradiation with neutrons and protons) at the Paul Scherrer Institute (PSI). During isochronal annealing experiment, coarsening of vacancy clusters and/or growth of helium bubbles was observed at T ⩾ 500 °C. This process causes an increase of low-momentum annihilation events and related increase of the S parameter during thermal treatment of material. On the other hand, the maximum concentration of helium in small vacancy clusters (Vn) was observed after annealing at 400 °C, where an excellent correlation with the calculated CDBS profiles of Vn + Hem clusters was found.

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

    CERN Document Server

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

    2016-01-01

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

  3. True coincidence summing correction determination for 214Bi principal gamma lines in NORM samples

    International Nuclear Information System (INIS)

    The gamma lines 609.3 and 1,120.3 keV are two of the most intensive γ emissions of 214Bi, 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 214Bi 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)

  4. Coincident occurrences of tropical individual cirrus clouds and deep convective systems derived from TRMM observations

    Science.gov (United States)

    Lin, Bing; Xu, Kuan-Man; Minnis, Patrick; Wielicki, Bruce A.; Hu, Yongxiang; Chambers, Lin; Fan, Tai-Fang; Sun, Wenbo

    2007-07-01

    Satellite measurements of cloud properties and atmospheric radiation were used to investigate the effect of spatial and temporal scales on the coincident occurrences of tropical individual cirrus clouds (ICCs) and deep convective systems (DCSs). There is little or even negative correlation between instantaneous occurrences of ICC and DCS in small areas. When spatial and temporal domains are increased, ICCs become more dependent on DCSs due to the origination of many ICCs from DCSs and moisture supply from the DCS in the upper troposphere for the ICCs to grow, resulting in significant positive correlation between the two types of clouds. The estimated radiative feedback due to the change in tropical high cloud area coverage with sea surface temperature appears small and about -0.14 Wm-2K-1, which would not cancel out the estimated anthropogenic forcing of doubled atmospheric CO2.

  5. 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.

  6. Calibration and experimental comparison of the active well coincidence counter and PHONID-II

    International Nuclear Information System (INIS)

    A team from EURATOM-Luxembourg, JRC-Ispra, Los Alamos, and International Atomic Energy Agency (IAEA) has performed measurements to directly compare the Active Well Coincidence Counter (AWCC) with the PHONID-II for the assay of highly enriched uranium (HEU). The comparison included an evaluation of counting rates, sensitivity, accuracy, linearity, stability, and matrix effects. Samples used in the evaluation included highly enriched uranium metal, U3O8 U-Al alloy plates, UF4, and (uranium/thorium) coated particles covering the mass range from a few grams up to about 5 kg of 235U. These materials are typical of the HEU samples under inspector verification. This report gives the results of the intercomparison as well as calibration information for the above material categories

  7. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-05-01

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

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

    International Nuclear Information System (INIS)

    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. Detection of the Cerenkov effect of β particles in a liquid by rapid photomultipliers in coincidence

    International Nuclear Information System (INIS)

    An electronic assembly in the nanosecond region was studied for the detection of weak light pulses due to the Cerenkov effect, which an ordinary photomultiplier represents by pulses of a level comparable to that of the thermal noise at ambient temperature. The elimination of these extraneous counts was effected by rapid coincidence between two photomultipliers viewing the same source of light. This arrangement, eliminating the cooling normally used in this type of detection, permits a significant reduction of the volume and weight of the apparatus used with the Cerenkov detector proper. The apparatus described has been applied to the detection of β-emitters in solution; it has permitted the measurement of Sr-Y activity in water, in concentrations at the MCP level. (author)

  11. Design and performance of the Savannah River Site Billet Active Well Coincidence Counter

    International Nuclear Information System (INIS)

    The Savannah River Site (SRS) has acquired, installed, and tested a custom-built Billet Active Well (neutron) Coincidence Counter (BAWCC). The BAWCC is used to make accountability measurements of the 235U content of U-Al coextrusion billets in the SRS fuel fabrication facility. The instrument design incorporates a unique center-source configuration, with two moderated americium-lithium (AmLi) neutron sources located in a central spindle that inserts through the center hole of the U-Al billets. This configuration, a result of earlier experimental studies at SRS, yields improved response and precision for billet assay when compared to the standard AWCC source arrangement. Initial tests of the BAWCC at SRS have yielded one-sigma uncertainties of 0.8--1.0% for a fifteen-minute assay. This paper will describe the design, testing program and performance characteristics of the BAWCC

  12. Natural GeV Dark Matter and the Baryon-Dark Matter Coincidence Puzzle

    CERN Document Server

    Allahverdi, Rouzbeh

    2013-01-01

    We present a simple extension of the standard model that gives rise to baryogenesis a has a dark matter candidate of O(GeV) mass. A minimal set of new fields required for baryogenesis includes two O(TeV) colored scalars and a singlet fermion. The fermion also becomes a viable dark matter candidate when its is nearly degenerate in mass with the proton. Dark matter and baryon asymmetry are produced form the decay of heavy scalars, which can lead to a natural explanation of the baryon-dark matter coincidence problem. The dark matter candidate escapes direct and indirect detection, but can be probed at the LHC. The supersymmetric extension of this model is straightforward and leads to a multi-component dark matter scenario, which improves the direct and indirect detection prospects.

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

    International Nuclear Information System (INIS)

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

  14. A recurrent network in the lateral amygdala: a mechanism for coincidence detection

    Directory of Open Access Journals (Sweden)

    2008-11-01

    Full Text Available Synaptic changes at sensory inputs to the dorsal nucleus of the lateral amygdala (LAd play a key role in the acquisition and storage of associative fear memory. However, neither the temporal nor spatial architecture of the LAd network response to sensory signals is understood. We developed a method for the elucidation of network behavior. Using this approach, temporally patterned polysynaptic recurrent network responses were found in LAd (intra-LA, both in vitro and in vivo, in response to activation of thalamic sensory afferents. Potentiation of thalamic afferents resulted in a depression of intra-LA synaptic activity, indicating a homeostatic response to changes in synaptic strength within the LAd network. Additionally; the latencies of thalamic afferent triggered recurrent network activity within the LAd overlap with known later occurring cortical afferent latencies. Thus, this recurrent network may facilitate temporal coincidence of sensory afferents within LAd during associative learning.

  15. Two-parameter gamma-gamma coincidence analysis with the ''useful'' data selection on both parameters

    International Nuclear Information System (INIS)

    The description is given of the method of registration of two-dimensional coincidence spectra with a decreased required memory volume but without losses of essential information. It is attained by transition from the field of two-dimensional matrix determined by the number of channels N within the spectrum of each parameter to the field of the two-dimensional matrix determined by the number of sectors M chosen by the experimenter of these spectra. The method is based on the use of two discriminator systems that make it possible to divide the spectra of all parameters into sectors. The memory volume gain is N2/M2. Two main storage modes are described: with registration of all information and with registration of selective information. The results of experiments are available

  16. PLUMEX II: A second set of coincident radar and rocket observations of equatorial spread-F

    International Nuclear Information System (INIS)

    PLUMEX II, the second rocket in a two-rocket operation that successfully executed coincident rocket and radar measurements of backscatter plumes and plasma depletions, was launched into the mid-phase of well-developed equatorial spread-F. In contrast with the first operation, the PLUMEX II results show large scale F-region irregularities only on the bottomside gradient with smaller scale irregularities (i.e., small scale structure imbedded in larger scale features) less intense than corresponding observations in PLUMEX I. The latter result could support current interpretations of east-west plume asymmetry which suggests that during initial upwelling the western wall of a plume (the PLUMEX I case) is more unstable than its eastern counterpart (the PLUMEX II case). In addition, ion mass spectrometer results are found to provide further support for an ion transport model which ''captures'' bottomside ions in an upwelling bubble and transports them to high altitudes

  17. 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.

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

    International Nuclear Information System (INIS)

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

  19. 3D Coincidence Imaging Disentangles Intense Field Double Detachment of SF6(–).

    Science.gov (United States)

    Kandhasamy, Durai Murugan; Albeck, Yishai; Jagtap, Krishna; Strasser, Daniel

    2015-07-23

    The efficient intense field double detachment of molecular anions observed in SF6(–) is studied by 3D coincidence imaging of the dissociation products. The dissociation anisotropy and kinetic energy release distributions are determined for the energetically lowest double detachment channel by virtue of disentangling the SF5(+) + F fragmentation products. The observed nearly isotropic dissociation with respect to the linear laser polarization and surprisingly high kinetic energy release events suggest that the dissociation occurs on a highly excited state. Rydberg (SF6(+))* states composed of a highly repulsive dication core and a Rydberg electron are proposed to explain the observed kinetic energy release, accounting also for the efficient production of all possible cationic fragments at equivalent laser intensities. PMID:26098224

  20. Vibrio harveyi quorum sensing: a coincidence detector for two autoinducers controls gene expression

    Science.gov (United States)

    Mok, Kenny C.; Wingreen, Ned S.; Bassler, Bonnie L.

    2003-01-01

    In a process called quorum sensing, bacteria communicate with one another by exchanging chemical signals called autoinducers. In the bioluminescent marine bacterium Vibrio harveyi, two different auto inducers (AI-1 and AI-2) regulate light emission. Detection of and response to the V.harveyi autoinducers are accomplished through two two-component sensory relay systems: AI-1 is detected by the sensor LuxN and AI-2 by LuxPQ. Here we further define the V.harveyi quorum-sensing regulon by identifying 10 new quorum-sensing-controlled target genes. Our examination of signal processing and integration in the V.harveyi quorum-sensing circuit suggests that AI-1 and AI-2 act synergistically, and that the V.harveyi quorum-sensing circuit may function exclusively as a ‘coincidence detector’ that discriminates between conditions in which both autoinducers are present and all other conditions. PMID:12574123

  1. Molecular photoionisation using synchrotron radiation. Photoelectron photoion coincidence and circular dichroism

    CERN Document Server

    Garcia-Macias, G A

    2002-01-01

    The first ionisation potential of the CF sub 3 radical has been determined in this work from the appearance potential of the CF sub 3 sup + fragment, formed in the photofragmentation of CF sub 3 Br. In obtaining this value special care has been taken in removing the contributions from second order light and internal energy of the fragmenting parent ion. The resulting ionisation potential was found to be in very good agreement with a number of recent theoretical calculations. The valence photoelectron spectra of three monoterpenes such as limonene, carvone and camphor have been recorded along with their mass spectra taken in coincidence with energy selected photoelectrons, providing information about state selected parent ion fragmentation channels. A new photoelectron spectrometer based on the Alien box design has been studied by ray-tracing simulations. It will include a two dimensional position sensitive detector system consisting in two micro channel plates in a chevron stack and a delay-line anode to enco...

  2. Coincidence Doppler broadening study of Eurofer 97 irradiated in spallation environment

    International Nuclear Information System (INIS)

    The behavior of transmutation helium during isochronal annealing of irradiated Eurofer 97 was investigated using coincidence Doppler broadening spectroscopy (CDBS). The investigated ferritic martensitic steel was irradiated in 2000 and 2001 in the frame of the STIP-II project at the Swiss neutron spallation source (SINQ) (irradiation with neutrons and protons) at the Paul Scherrer Institute (PSI). During isochronal annealing experiment, coarsening of vacancy clusters and/or growth of helium bubbles was observed at T ⩾ 500 °C. This process causes an increase of low-momentum annihilation events and related increase of the S parameter during thermal treatment of material. On the other hand, the maximum concentration of helium in small vacancy clusters (Vn) was observed after annealing at 400 °C, where an excellent correlation with the calculated CDBS profiles of Vn + Hem clusters was found

  3. Time-and-frequency-gated photon coincidence counting; a novel multidimensional spectroscopy tool

    Science.gov (United States)

    Dorfman, Konstantin E.; Mukamel, Shaul

    2016-08-01

    Coherent multidimensional optical spectroscopy is broadly applied across the electromagnetic spectrum ranging from NMR to UV. These techniques reveal the properties of matter through the correlation plots of signal fields generated in response to sequences of short pulses with variable delays. Here we discuss a new class of multidimensional techniques obtained by the time-and-frequency-resolved photon coincidence counting measurements of N photons, which constitute a 2N dimensional spectrum. A compact description of these signals is developed based on time-ordered superoperators rather than the normally ordered ordinary operators used in Glauber's photon counting formalism. The independent control of the time and frequency gate parameters reveals fine details of matter dynamics not available otherwise. These signal are illustrated for application to an anharmonic oscillator model with fluctuating energy and anharmonicity.

  4. CMB observations from the CBI and VSA: A comparison of coincident maps and parameter estimation methods

    CERN Document Server

    Rajguru, N; Battye, R A; Bond, J R; Cleary, K; Contaldi, C R; Davies, R D; Davis, R J; Dickinson, C; Genova-Santos, R; Grainge, K; Hafez, Y A; Hobson, M P; Jones, M E; Kneissl, R; Lancaster, K; Lasenby, A; Mason, B S; Pearson, T J; Pooley, G G; Readhead, A C S; Rebolo, R; Rocha, G; Rubiño-Martín, J A; Saunders, R D E; Savage, R S; Scaife, A; Scott, P F; Sievers, J L; Slosar, A; Taylor, A C; Titterington, D; Waldram, E M; Watson, R A; Wilkinson, A

    2005-01-01

    We present coincident observations of the Cosmic Microwave Background (CMB) from the Very Small Array (VSA) and Cosmic Background Imager (CBI) telescopes. The consistency of the full datasets is tested in the map plane and the Fourier plane, prior to the usual compression of CMB data into flat bandpowers. Of the three mosaics observed by each group, two are found to be in excellent agreement. In the third mosaic, there is a 2 sigma discrepancy between the correlation of the data and the level expected from Monte Carlo simulations. This is shown to be consistent with increased phase calibration errors on VSA data during summer observations. We also consider the parameter estimation method of each group. The key difference is the use of the variance window function in place of the bandpower window function, an approximation used by the VSA group. A re-evaluation of the VSA parameter estimates, using bandpower windows, shows that the two methods yield consistent results.

  5. Design and Performance of the Astro-E/XRS Microcalorimeter Array and Anti-Coincidence Detector

    Science.gov (United States)

    Stahle, C. K.; Audley, M. D.; Boyce, K. R.; Brekosky, R. P.; Fujimoto, R.; Gendreau, K. C.; Gygax, J. D.; Ishisaki, Y.; Kelley, R. L.; McClanahan, R. A.

    1999-01-01

    The XRS instrument has an array of 32 micro-calorimeters at the focal plane. These calorimeters consist of ion-implanted silicon thermistors and HgTe thermalizing x-ray absorbers. These devices have demonstrated a resolution of 9 eV at 3 keV and 11 eV at 6 keV. We will discuss the basic physical parameters of this array, including the array layout, thermal conductance of the link to the heat sink, operating temperature, thermistor size, absorber choice, and means of attaching the absorber to the thermistor bearing element. We will present representative performance data, though a more detailed presentation of the results of the instrument calibration is presented elsewhere in these proceedings. A silicon ionization detector is located behind the calorimeter array and serves to reject events due to cosmic rays. We will briefly describe this anti-coincidence detector and its performance in conjunction with the array.

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

    International Nuclear Information System (INIS)

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

  7. A Dead Time Correction for Overlapped Pulse Signals for a Thermal Neutron Coincidence Counter System

    International Nuclear Information System (INIS)

    A typical well-type thermal neutron counter uses many He-3 proportional counter neutron detectors to enhance its measurement efficiency. Such, He-3 detectors are grouped with several other groups to make one output signal. Then the group signals are connected to shift register coincidence electronics using an OR gate device. But a loss of pulse signals occurs in an OR gate device because a simultaneous pulse signal is recognized as one pulse signal. This paper describes the development of a new circuit that processes overlapped pulse signals and the effect of the dead time with an OR gate device of an ACP Safeguards Neutron Counter (ASNC) for an Advanced Spent Fuel Conditioning Process (ACP)

  8. True coincidence summing corrections for an extended energy range HPGe detector

    International Nuclear Information System (INIS)

    True coincidence summing (TCS) effect for natural radioactive families of U-238 and Th-232 represents a problem when an environmental sample with a close source-detector geometry measurement is performed. By using a certified multi-nuclide standard source to calibrate an energy extended range (XtRa) HPGe detector, it is possible to obtain an intensity spectrum slightly affected by the TCS effect with energies from 46 to 1836 keV. In this work, the equations and some other considerations required to calculate the TCS correction factor for isotopes of natural radioactive chains are described. It is projected a validation of the calibration, performed with the IAEA-CU-2006-03 samples (soil and water)

  9. Estimation of residual plutonium oxide in empty containers using neutron well coincidence counting

    International Nuclear Information System (INIS)

    Neutron well coincidence counting (NWCC) technique is a relatively fast and non-destructive technique for plutonium analysis. This technique has been used for the analysis of residual plutonium oxide in empty containers. Estimation of plutonium oxide left in the empty container is very difficult by using other techniques such as potentiometry, coulometry etc. as all these techniques need tedious and time taking sample preparation processes involving separation, dissolution, accurate weighing etc. NWCC was found to be very useful technique is this analysis as no sample preparation was needed and sample can be counted directly in double sealed packet. Over 180 empty containers have been analyzed by this technique with 5% accuracy and precision. (author)

  10. Hypohidrotic ectodermal dysplasia and immunodeficiency with coincident NEMO and EDA mutations.

    Science.gov (United States)

    Keller, Michael D; Petersen, Maureen; Ong, Peck; Church, Joseph; Risma, Kimberly; Burham, Jon; Jain, Ashish; Stiehm, E Richard; Hanson, Eric P; Uzel, Gulbu; Deardorff, Matthew A; Orange, Jordan S

    2011-01-01

    Ectodermal dysplasias (ED) are uncommon genetic disorders resulting in abnormalities in ectodermally derived structures. Many ED-associated genes have been described, of which ectodysplasin-A (EDA) is one of the more common. The NF-κB essential modulator (NEMO encoded by the IKBKG gene) is unique in that mutations result in severe humoral and cellular immunologic defects in addition to ED. We describe three unrelated kindreds with defects in both EDA and IKBKG resulting from 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 IKBKG. PMID:22566850

  11. Coincidence, historical repetition, and self-knowledge: Jung, Vico, and Joyce.

    Science.gov (United States)

    Verene, Donald Phillip

    2002-07-01

    Jung develops synchronicity as an a causal principle of connection by recounting various examples of meaningful coincidence from experience and by analysing various systems of divination, notably the I Ching. Philosophical theory of causality has given no significant attention to synchronicity; the events of synchronicity are regarded as chance. The Neapolitan philosopher Giambattista Vico (1668-1744) developed a doctrine of historical experience and of self-knowledge that grounds the phenomenon of synchronicity in a metaphysics. James Joyce employed Vico's conception of language and historical cycles as the basis of Joyce's final literary work, Finnegans Wake. Vico's metaphysical sense of synchronicity and Joyce's literary formulation offer a grounding of this principle in non-divinatory sources in modern Western thought, something which Jung's discussion does not provide. These philosophical and literary perspectives complement Jung's to offer an expanded context in which to recognize synchronicity and to make sense of it. PMID:12174547

  12. Charge configurations in viral proteins.

    OpenAIRE

    Karlin, S; Brendel, V

    1988-01-01

    The spatial distribution of the charged residues of a protein is of interest with respect to potential electrostatic interactions. We have examined the proteins of a large number of representative eukaryotic and prokaryotic viruses for the occurrence of significant clusters, runs, and periodic patterns of charge. Clusters and runs of positive charge are prominent in many capsid and core proteins, whereas surface (glyco)proteins frequently contain a negative charge cluster. Significant charge ...

  13. The use of computed radiography plates to determine light and radiation field coincidence

    International Nuclear Information System (INIS)

    Purpose: Photo-stimulable phosphor computed radiography (CR) has characteristics that allow the output to be manipulated by both radiation and optical light. The authors have developed a method that uses these characteristics to carry out radiation field and light field coincidence quality assurance on linear accelerators.Methods: CR detectors from Kodak were used outside their cassettes to measure both radiation and light field edges from a Varian linear accelerator. The CR detector was first exposed to a radiation field and then to a slightly smaller light field. The light impinged on the detector's latent image, removing to an extent the portion exposed to the light field. The detector was then digitally scanned. A MATLAB-based algorithm was developed to automatically analyze the images and determine the edges of the light and radiation fields, the vector between the field centers, and the crosshair center. Radiographic film was also used as a control to confirm the radiation field size.Results: Analysis showed a high degree of repeatability with the proposed method. Results between the proposed method and radiographic film showed excellent agreement of the radiation field. The effect of varying monitor units and light exposure time was tested and found to be very small. Radiation and light field sizes were determined with an uncertainty of less than 1 mm, and light and crosshair centers were determined within 0.1 mm.Conclusions: A new method was developed to digitally determine the radiation and light field size using CR photo-stimulable phosphor plates. The method is quick and reproducible, allowing for the streamlined and robust assessment of light and radiation field coincidence, with no observer interpretation needed

  14. 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.

  15. Charged particle beams

    CERN Document Server

    Humphries, Stanley

    2013-01-01

    Detailed enough for a text and sufficiently comprehensive for a reference, this volume addresses topics vital to understanding high-power accelerators and high-brightness-charged particle beams. Subjects include stochastic cooling, high-brightness injectors, and the free electron laser. Humphries provides students with the critical skills necessary for the problem-solving insights unique to collective physics problems. 1990 edition.

  16. Charged Particle Optics Theory

    Czech Academy of Sciences Publication Activity Database

    Hawkes, P. W.; Lencová, Bohumila

    -, č. 6 (2006), s. 6-8 Grant ostatní: EC 5RP(XE) G5RD-CT-2000-00344 Institutional research plan: CEZ:AV0Z20650511 Keywords : optics of charged particles * design of ion lithography system * spot profile * the finite element method Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering www.phantomsnet.net

  17. Stability of charged membranes

    OpenAIRE

    Bensimon, D; David, F.; Leibler, S.; Pumir, A.

    1990-01-01

    The electrostatic contribution to the bending elastic modulus of charged phospholipid bilayers in an ionic solution is computed. It is found to be the same for conducting and non-conducting membranes and is always stabilizing. This stability for free membranes is shown to be a simple consequence of the vanishing of the physical surface tension.

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

    International Nuclear Information System (INIS)

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

  19. Spontaneous Emission of Charged Bosons from Supercritical Point Charges

    CERN Document Server

    Kim, Sang Pyo

    2013-01-01

    We study the spontaneous emission of charged bosons from supercritical Coulomb potentials and charged black holes. We find the exact emission rate from the Bogoliubov transformation by applying the tunneling boundary condition on the Jost functions at the asymptotic boundaries. The emission rate for charged bosons in the supercritical Coulomb potential increases as the charge $Z\\alpha > 1/2$ of the superatom and the energy of the bosons increase but is suppressed for large angular momenta. We discuss physical implications of the emission of charged bosons from superatoms and charged black holes.

  20. Decay of electric charge on corona charged polyethylene

    International Nuclear Information System (INIS)

    In this paper, the surface potential decay of corona-charged low density polyethylene (LDPE) films has been investigated. It has been found that for the same sample thickness the faster decay occurs in the sample with a higher charging voltage. For the same charging voltage, the surface potential in the thinner sample shows rapid decay. Our new evidence from both the surface potential measurement on multilayer samples and space charge measurement suggests the surface potential decay is a bulk limited process. More importantly, space charge measurement indicates double injection has taken place during corona charging process.

  1. Optimization of BEV Charging Strategy

    Science.gov (United States)

    Ji, Wei

    This paper presents different approaches to optimize fast charging and workplace charging strategy of battery electric vehicle (BEV) drivers. For the fast charging analysis, a rule-based model was built to simulate BEV charging behavior. Monte Carlo analysis was performed to explore to the potential range of congestion at fast charging stations which could be more than four hours at the most crowded stations. Genetic algorithm was performed to explore the theoretical minimum waiting time at fast charging stations, and it can decrease the waiting time at the most crowded stations to be shorter than one hour. A deterministic approach was proposed as a feasible suggestion that people should consider to take fast charging when the state of charge is approaching 40 miles. This suggestion is hoped to help to minimize potential congestion at fast charging stations. For the workplace charging analysis, scenario analysis was performed to simulate temporal distribution of charging demand under different workplace charging strategies. It was found that if BEV drivers charge as much as possible and as late as possible at workplace, it could increase the utility of solar-generated electricity while relieve grid stress of extra intensive electricity demand at night caused by charging electric vehicles at home.

  2. P-V criticality of charged AdS black holes

    OpenAIRE

    Kubiznak, David; Robert B. Mann

    2012-01-01

    Treating the cosmological constant as a thermodynamic pressure and its conjugate quantity as a thermodynamic volume, we reconsider the critical behaviour of charged AdS black holes. We complete the analogy of this system with the liquid-gas system and study its critical point, which occurs at the point of divergence of specific heat at constant pressure. We calculate the critical exponents and show that they coincide with those of the Van der Waals system.

  3. Transfer ionization cross-sections measured in collisions of highly charged argon ions with neon target

    Institute of Scientific and Technical Information of China (English)

    MA; Xinwen(马新文); LIU; Huiping; (刘惠萍); CHEN; Ximeng; (陈熙萌); YANG; Zhihu; (杨治虎); SHEN; Ziyong; (申自勇); WANG; Youde; (王友德); YU; Deyang; (于得洋); CAI; Xiaohong; (蔡晓红); LIU; Zhaoyuan; (刘兆远)

    2003-01-01

    Multiple electron transfer processes are studied for Arq+ + Ne (q = 8, 9, 11, 12) collisions by using multi-parameter coincidence techniques. Various electron transfer processes are identified experimentally and the related cross-sections are measured. The dependence of transfer ionization cross-sections on the recoil charge states is compared with the results from the modified molecular classical overbarrier model. It is found that the modified model described the experimental results reasonably.

  4. K-Vacancy Production in the Collision of Highly Charged Relativistic Ions With Heavy Atoms

    OpenAIRE

    Khabibullaev, P. K.

    2000-01-01

    A general expression for the cross section of the inelastic collision of relativistic highly charged ion with heavy (relativistic) atoms is obtained using the generalized eikonal approximation. In the ultrarelativistic limit, the obtained formula coincides with a known exact one. As an application of the obtained result, probability and cross section of the K-vacany production in the U92+ - U91+ collision are calculated.

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

    International Nuclear Information System (INIS)

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

  6. Charge Breeding of Radioactive Ions

    OpenAIRE

    Wenander, F. J. C.

    2014-01-01

    Charge breeding is a technique to increase the charge state of ions, in many cases radioactive ions. The singly charged radioactive ions, produced in an isotope separator on-line facility, and extracted with a low kinetic energy of some tens of keV, are injected into a charge breeder, where the charge state is increased to Q. The transformed ions are either directed towards a dedicated experiment requiring highly charged ions, or post-accelerated to higher beam energies. In this paper the phy...

  7. Determination of nuclear charge resolution of a thin film detector using a 252Cf fission fragment source

    International Nuclear Information System (INIS)

    Little quantitative information is available regarding the ability of a thin film detector (TFD) to determine the nuclear charge of a low energy heavy mass ion. To compare the nuclear charge resolving power Z/ΔZ of the TFD to other heavy ion detectors, an experiment was performed where the TFD luminescence response to 252Cf fission fragments was recorded in coincidence with the gamma de-excitation of the fragments. With this technique, the TFD nuclear charge resolving power Z/ΔZ was determined to be 25.2 for the light mass fragment group. (orig.)

  8. Determination of nuclear charge resolution of a thin film detector using a [sup 252]Cf fission fragment source

    Energy Technology Data Exchange (ETDEWEB)

    Milosevich, Z.; Muga, M.L. (Florida Univ., Gainesville, FL (United States). Dept. of Chemistry); Coldwell, R.L. (Florida Univ., Gainesville, FL (United States). Dept. of Physics)

    1992-09-15

    Little quantitative information is available regarding the ability of a thin film detector (TFD) to determine the nuclear charge of a low energy heavy mass ion. To compare the nuclear charge resolving power Z/[Delta]Z of the TFD to other heavy ion detectors, an experiment was performed where the TFD luminescence response to [sup 252]Cf fission fragments was recorded in coincidence with the gamma de-excitation of the fragments. With this technique, the TFD nuclear charge resolving power Z/[Delta]Z was determined to be 25.2 for the light mass fragment group. (orig.).

  9. 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

  10. 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

  11. Photoionization of endohedral fullerenes using soft x-ray coincidence spectroscopy

    Science.gov (United States)

    Obaid, Razib; Xiong, Hui; Ablikim, Utuq; Augustin, Sven; Schnorr, Kirsten; Battistoni, Andrea; Wolf, Thomas; Carroll, Ann Marie; Bilodeau, Rene; Osipov, Timur; Rolles, Daniel; Berrah, Nora

    2016-05-01

    Endohedral fullerenes are a model system to understand the reorganization dynamics of highly charged molecular systems with delocalized electronic clouds in the multiphoton excitation regime. Previous experiments at the Linac Coherent Light Source (LCLS) using free-electron laser (FEL) and ultrafast IR laser pulses studied this feature in Ho3N@C80. The question remains whether these dynamics can be studied in the site-specific single photo-ionization regime. Ho3N@C80 is particularly interesting since the inner molecule, Ho3N, is unstable in its natural form. The presence of the encapsulating cage, with the charge exchange characteristics of Holmium, stabilizes the whole molecule. In this study, we will present the charge fragmentation dynamics of this species in the single photoionization process of inner shell electrons (4d) of Holmium using the Advanced Light Source (ALS) at LBNL. Photoion-photoion correlation data, alongside with qualitative electron data will be presented. Funded by the DoE-BES, Grant No. DE-SC0012376.

  12. Intelligent battery charging system

    Science.gov (United States)

    Everett, Hobert R., Jr.

    1991-09-01

    The present invention is a battery charging system that provides automatic voltage selection, short circuit protection, and delayed output to prevent arcing or pitting. A second embodiment of the invention provides a homing beacon which transmits a signal so that a battery powered mobile robot may home in on and contact the invention to charge its battery. The invention includes electric terminals isolated from one another. One terminal is grounded and the other has a voltage applied to it through a resistor connected to the output of a DC power supply. A voltage scaler is connected between the resistor and the hot terminal. An On/Off controller and a voltage mode selector sense the voltage provided at the output of the voltage scaler.

  13. High Voltage Charge Pump

    KAUST Repository

    Emira, Ahmed A.

    2014-10-09

    Various embodiments of a high voltage charge pump are described. One embodiment is a charge pump circuit that comprises a plurality of switching stages each including a clock input, a clock input inverse, a clock output, and a clock output inverse. The circuit further comprises a plurality of pumping capacitors, wherein one or more pumping capacitors are coupled to a corresponding switching stage. The circuit also comprises a maximum selection circuit coupled to a last switching stage among the plurality of switching stages, the maximum selection circuit configured to filter noise on the output clock and the output clock inverse of the last switching stage, the maximum selection circuit further configured to generate a DC output voltage based on the output clock and the output clock inverse of the last switching stage.

  14. Hidden Charged Dark Matter

    CERN Document Server

    Feng, Jonathan L; Tu, Huitzu; Yu, Hai-Bo

    2009-01-01

    We examine the possibility that dark matter is hidden, that is, neutral under all standard model gauge interactions, but charged under an exact U(1) gauge symmetry of the hidden sector. Such candidates are predicted in simple WIMPless models, supersymmetric models in which hidden dark matter has the desired thermal relic density for a wide range of masses. Hidden charged dark matter has many potentially disastrous implications for astrophysics: (1) bound state formation and Sommerfeld-enhanced annihilation after chemical freeze out may destroy its relic density, (2) similar effects greatly enhance dark matter annihilation in protohalos at redshifts of z ~ 30, (3) Compton scattering off hidden photons delays kinetic decoupling, suppressing small scale structure, and (4) Rutherford scattering makes such dark matter self-interacting and collisional, potentially violating constraints from the Bullet Cluster and the observed morphology of galactic halos. We show that all of these constraints are satisfied and are ...

  15. Controlling charge on levitating drops.

    Science.gov (United States)

    Hilger, Ryan T; Westphall, Michael S; Smith, Lloyd M

    2007-08-01

    Levitation technologies are used in containerless processing of materials, as microscale manipulators and reactors, and in the study of single drops and particles. Presented here is a method for controlling the amount and polarity of charge on a levitating drop. The method uses single-axis acoustic levitation to trap and levitate a single, initially neutral drop with a diameter between 400 microm and 2 mm. This drop is then charged in a controllable manner using discrete packets of charge in the form of charged drops produced by a piezoelectric drop-on-demand dispenser equipped with a charging electrode. The magnitude of the charge on the dispensed drops can be adjusted by varying the voltage applied to the charging electrode. The polarity of the charge on the added drops can be changed allowing removal of charge from the trapped drop (by neutralization) and polarity reversal. The maximum amount of added charge is limited by repulsion of like charges between the drops in the trap. This charging scheme can aid in micromanipulation and the study of charged drops and particles using levitation. PMID:17580951

  16. Charge states of ions, and mechanisms of charge ordering transitions

    International Nuclear Information System (INIS)

    To gain insight into the mechanism of charge ordering transitions, which conventionally are pictured as a disproportionation of an ion M as 2Mn+→M(n+1)+ + M(n−1)+, we (1) review and reconsider the charge state (or oxidation number) picture itself, (2) introduce new results for the putative charge ordering compound AgNiO2 and the dual charge state insulator AgO, and (3) analyze the cationic occupations of the actual (not formal) charge, and work to reconcile the conundrums that arise. We establish that several of the clearest cases of charge ordering transitions involve no disproportion (no charge transfer between the cations, and hence no charge ordering), and that the experimental data used to support charge ordering can be accounted for within density functional-based calculations that contain no charge transfer between cations. We propose that the charge state picture retains meaning and importance, at least in many cases, if one focuses on Wannier functions rather than atomic orbitals. The challenge of modeling charge ordering transitions with model Hamiltonians isdiscussed. (paper)

  17. Mesoscopic charge quantization

    OpenAIRE

    Aleiner, I.L.; Glazman, L. I.

    1997-01-01

    We study the Coulomb blockade in a chaotic quantum dot connected to a lead by a single channel at nearly perfect transmission. We take into account quantum fluctuations of the dot charge and a finite level spacing for electron states within the dot. Mesoscopic fluctuations of thermodynamic and transport properties in the Coulomb blockade regime exist at any transmission coefficient. In contrast to the previous theories, we show that by virtue of these mesoscopic fluctuations, the Coulomb bloc...

  18. Charged current review

    International Nuclear Information System (INIS)

    Experimental measurements of the τ lifetime and leptonic branching ratios are combined to give updated world averages for these quantities. The results are then used to test the universality of the electroweak charged current couplings to the three lepton species and are found to be consistent with Standard Model predictions at the level of 0.2%, permitting limits to be derived on non-Standard Model physics such as the mass of the τ neutrino

  19. General 2 charge geometries

    CERN Document Server

    Taylor, M

    2006-01-01

    Two charge BPS horizon free supergravity geometries are important in proposals for understanding black hole microstates. In this paper we construct a new class of geometries in the NS1-P system, corresponding to solitonic strings carrying fermionic as well as bosonic condensates. Such geometries are required to account for the full microscopic entropy of the NS1-P system. We then briefly discuss the properties of the corresponding geometries in the dual D1-D5 system.

  20. Interaction of low-energy highly charged ions with matter

    International Nuclear Information System (INIS)

    The thesis presented herein deals with experimental studies of the interaction between highly charged ions and neutral matter at low collision energies. The energy range investigated is of great interest for the understanding of both charge exchange reactions between ions comprising the solar wind and various astrophysical gases, as well as the creation of near-surface nanostructures. Over the course of this thesis an experimental setup was constructed, capable of reducing the kinetic energy of incoming ions by two orders of magnitude and finally focussing the decelerated ion beam onto a solid or gaseous target. A coincidence method was employed for the simultaneous detection of photons emitted during the charge exchange process together with the corresponding projectile ions. In this manner, it was possible to separate reaction channels, whose superposition presumably propagated large uncertainties and systematic errors in previous measurements. This work has unveiled unexpectedly strong contributions of slow radiative decay channels and clear evidence of previously only postulated decay processes in charge exchange-induced X-ray spectra. (orig.)