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Sample records for time-of flight neutron

  1. Neutron Time-Of-Flight (n_TOF) experiment

    CERN Multimedia

    Brugger, M; Kaeppeler, F K; Jericha, E; Cortes rossell, G P; Riego perez, A; Baccomi, R; Laurent, B G; Griesmayer, E; Leeb, H; Dressler, M; Cano ott, D; Variale, V; Ventura, A; Carrillo de albornoz trillo, A; Andrzejewski, J J; Pavlik, A F; Kadi, Y; Zanni vlastou, R; Krticka, M; Kokkoris, M; Praena rodriguez, A J; Cortes giraldo, M A; Perkowski, J; Losito, R; Audouin, L; Weiss, C; Tagliente, G; Wallner, A; Woods, P J; Mengoni, A; Guerrero sanchez, C G; Tain enriquez, J L; Vlachoudis, V; Calviani, M; Junghans, A R; Reifarth, R; Mendoza cembranos, E; Quesada molina, J M; Babiano suarez, V; Schumann, M D; Tsinganis, A; Rauscher, T; Calvino tavares, F; Mingrone, F; Gonzalez romero, E M; Colonna, N; Negret, A L; Chiaveri, E; Milazzo, P M; De almeida carrapico, C A; Castelluccio, D M

    The neutron time-of-flight facility n_TOF at CERN, Switzerland, operational since 2001, delivers neutrons using the Proton Synchrotron (PS) 20 GeV/c proton beam impinging on a lead spallation target. The facility combines a very high instantaneous neutron flux, an excellent time of flight resolution due to the distance between the experimental area and the production target (185 meters), a low intrinsic background and a wide range of neutron energies, from thermal to GeV neutrons. These characteristics provide a unique possibility to perform neutron-induced capture and fission cross-section measurements for applications in nuclear astrophysics and in nuclear reactor technology.

  2. Detailed investigation of a time-of-flight neutron spectrometer

    International Nuclear Information System (INIS)

    Elevant, T.; Trostell, B.

    1981-02-01

    Properties of a neutron spectrometer and telescope, based on double neutron interaction in hydrogen based scintillators and neutron time-of-flight technique, have been investigated in detail. Theoretical scaling of the resolutions with the flight path length and scattering angle have been confirmed by experimental results. Important parameters in connection with calibration of the spectrometer are discussed and calculated relative resolutions of the ion temperature are shown when applied to a fusion deuterium plasma. (Auth.)

  3. Multichannel analyzer for the neutron time-of-flight spectrometer

    International Nuclear Information System (INIS)

    Vojter, A.P.; Slyisenko, V.Yi.; Doronyin, M.Yi.; Maznij, Yi.O.; Vasil'kevich, O.A.; Golyik, V.V.; Koval'ov, O.M.; Kopachov, V.Yi.; Savchuk, V.G.

    2010-01-01

    New multichannel time-of-flight spectrometer for the measurement of the energy and angular distributions of neutrons from the WWWR-M reactor is considered. This spectrometer has been developed for the replacement of the previous one to increase the number of channels and measurement precision, reduce the time of channel tuning and provide the automatic monitoring during the experiment.

  4. High resolution fast neutron spectrometry without time-of-flight

    International Nuclear Information System (INIS)

    Evans, A.E.; Brandenberger, J.D.

    1978-01-01

    Performance tests of a spectrometer tube of the type developed by Cuttler and Shalev show that the measurement of fast neutron spectra with this device can be made with an energy resolution previously obtainable only in large time-of-flight facilities. In preliminary tests, resolutions of 16.4 keV for thermal neutrons and 30.9 keV for 1-MeV neutrons were obtained. A broad-window pulse-shape discrimination (PSD) system is used to remove from pulse-height distributions most of the continua due to 3 He-recoil events, noise, and wall effect. Use of PSD improved the energy resolution to 12.9 keV for thermal neutrons and 29.2 keV for 1-MeV neutrons. The detector is a viable tool for neutron research at nominally equipped accelerator laboratories

  5. A neutron time-of-flight data acquisition system

    International Nuclear Information System (INIS)

    Morris, D.V.

    1983-10-01

    A neutron time-of-flight scaler system is described for use with the Harwell Linac. The equipment is sufficiently versatile to be used with several types of computers although normally used with DEC PDP 11/45 and PDP 11/34. Using a combination of different input and memory boards most types of experiments can be accommodated. (author)

  6. Time recording unit for a neutron time of flight spectrometer

    International Nuclear Information System (INIS)

    Puranik, Praful; Ajit Kiran, S.; Chandak, R.M.; Poudel, S.K.; Mukhopadhyay, R.

    2011-01-01

    Here the architecture and design of Time Recording Unit for a Neutron Time of Flight Spectrometer have been described. The Spectrometer would have an array of 50 Nos. of one meter long linear Position Sensitive Detector (PSD) placed vertically around the sample at a distance of 2000 mm. The sample receives periodic pulsed neutron beam coming through a Fermi chopper. The time and zone of detection of a scattered neutron in a PSD gives information of its flight time and path length, which will be used to calculate its energy. A neutron event zone (position) and time detection module for each PSD provides a 2 bit position/zone code and an event timing pulse. The path length assigned to a neutron detected in a zone (Z1, Z2 etc) in the PSD is the mean path length seen by the neutrons detected in that zone of the PSD. A Time recording unit described here receives event zone code and timing pulse for all the 50 detectors, tags a proper time window code to it, before streaming it to computer for calculation of the energy distribution of neutrons scattered from the sample

  7. Tests and calibration of NIF neutron time of flight detectors.

    Science.gov (United States)

    Ali, Z A; Glebov, V Yu; Cruz, M; Duffy, T; Stoeckl, C; Roberts, S; Sangster, T C; Tommasini, R; Throop, A; Moran, M; Dauffy, L; Horsefield, C

    2008-10-01

    The National Ignition Facility (NIF) neutron time of flight (NTOF) diagnostic will measure neutron yield and ion temperature in all NIF campaigns in DD, DT, and THD(*) implosions. The NIF NTOF diagnostic is designed to measure neutron yield from 1x10(9) to 2x10(19). The NTOF consists of several detectors of varying sensitivity located on the NIF at about 5 and 20 m from the target. Production, testing, and calibration of the NIF NTOF detectors have begun at the Laboratory for Laser Energetics (LLE). Operational tests of the NTOF detectors were performed on several facilities including the OMEGA laser at LLE and the Titan laser at Lawrence Livermore National Laboratory. Neutron calibrations were carried out on the OMEGA laser. Results of the NTOF detector tests and calibration will be presented.

  8. Characterizing Scintillator Response with Neutron Time-of-Flight

    Science.gov (United States)

    Palmisano, Kevin; Visca, Hannah; Caves, Louis; Wilkinson, Corey; McClow, Hannah; Padalino, Stephen; Forrest, Chad; Katz, Joe; Sangster, Craig; Regan, Sean

    2017-10-01

    Neutron scintillator diagnostics for ICF can be characterized using the neutron time-of-flight (nTOF) line on Geneseo's 1.7 MV Tandem Pelletron Accelerator. Neutron signals can be differentiated from gamma signals by employing a coincidence method called the associated particle technique (APT). In this measurement, a 2.1 MeV beam of deuterons incident on a deuterated polyethylene target produces neutrons via the d(d,n)3He reaction. A BC-412 plastic scintillator, placed at a scattering angle of 152º, detects 1.76 MeV neutrons in coincidence with the 2.56 MeV 3He ions at an associated angle of 10º. The APT is used to identify the 1.76 MeV neutron while the nTOF line determines its energy. By gating only mono-energetic neutrons, the instrument response function of the scintillator can be determined free from background scattered neutrons and gamma rays. Funded in part by a Grant from the DOE, through the Laboratory for Laser Energetics.

  9. Time coder for slow neutron time-of-flight spectrometer

    International Nuclear Information System (INIS)

    Grashilin, V.A.; Ofengenden, R.G.

    1988-01-01

    Time coder for slow neutron time-of-flight spectrometer is described. The time coder is of modular structure, is performed in the CAMAC standard and operates on line with DVK-2 computer. The main coder units include supporting generator, timers, time-to-digital converter, memory unit and crate controller. Method for measuring background symmetrically to the effect is proposed for a more correct background accounting. 4 refs.; 1 fig

  10. Time-of-flight neutron diffractometer for monocrystal study

    International Nuclear Information System (INIS)

    Anan'ev, B.N.; Balagurov, A.M.; Barabash, I.P.; Georgiu, Z.; Shibaev, V.D.

    1979-01-01

    The design of a neutron diffractometer is discussed. It is used for structural analysis of single crystals on the basis of time-of-flight measurements. The diffractometer is positioned along the axis of a beam of the IBR-30 pulse reactor, its average power is 29 kW. The mechanical part of the diffractometer consists of a massive foundation with a threeaxial goniometer, a rotatable platform with a collimator and a 3 He counter. The flowsheet of a control unit is given, which is used to position the rotatable platform of the diffractometer. The control unit includes a 14 digic binary counter for rotation angle recording, a parallel-to-series converter, a control signal shaper, two position shift registers, and a servo mechanism. The accuracy of diffraction maxima is evaluated. It is found that the ratio D(t)sup(1/2)/t (D(t) is a time dispersion of diffraction maxima, t is total time-of-flight time), which characterize the resolution of the diffractometer, is equal to 0.5% at the Bragg angle Q=45 deg and the neutron wavelength Λ=1 A

  11. A Time of Flight Fast Neutron Imaging System Design Study

    Science.gov (United States)

    Canion, Bonnie; Glenn, Andrew; Sheets, Steven; Wurtz, Ron; Nakae, Les; Hausladen, Paul; McConchie, Seth; Blackston, Matthew; Fabris, Lorenzo; Newby, Jason

    2017-09-01

    LLNL and ORNL are designing an active/passive fast neutron imaging system that is flexible to non-ideal detector positioning. It is often not possible to move an inspection object in fieldable imager applications such as safeguards, arms control treaty verification, and emergency response. Particularly, we are interested in scenarios which inspectors do not have access to all sides of an inspection object, due to interfering objects or walls. This paper will present the results of a simulation-based design parameter study, that will determine the optimum system design parameters for a fieldable system to perform time-of-flight based imaging analysis. The imaging analysis is based on the use of an associated particle imaging deuterium-tritium (API DT) neutron generator to get the time-of-flight of radiation induced within an inspection object. This design study will investigate the optimum design parameters for such a system (e.g. detector size, ideal placement, etc.), as well as the upper and lower feasible design parameters that the system can expect to provide results within a reasonable amount of time (e.g. minimum/maximum detector efficiency, detector standoff, etc.). Ideally the final prototype from this project will be capable of using full-access techniques, such as transmission imaging, when the measurement circumstances allow, but with the additional capability of producing results at reduced accessibility.

  12. Depth profiling of tritium by neutron time-of-flight

    International Nuclear Information System (INIS)

    Davis, J.C.; Anderson, J.D.; Lefevre, H.W.

    1976-01-01

    A method to measure the depth profile of tritium implanted or absorbed in materials was developed. The sample to be analyzed is bombarded with a pulsed proton beam and the energy of neutrons produced by the T(p,n) reaction is measured by the time-of-flight technique. From the neutron energy the depth in the target of the T atoms may be inferred. A sensitivity of 0.1 at. percent T or greater is possible. The technique is non-destructive and may be used with thick or radioactive host materials. Samples up to 20 μm in thickness may be profiled with resolution limited by straggling of the proton beam for depths greater than 1 μm. Deuterium depth profiling has been demonstrated using the D(d,n) reaction. The technique has been used to observe the behavior of an implantation spike of T produced by a 400 keV T + beam stopping at a depth of 3 μm in 11 μm thick layers of Ti and TiH. The presence of H in the Ti lattice is observed to inhibit the diffusion of T through the lattice. Effects of the total hydrogen concentration (H + T) being forced above stochiometry at the implantation site are suggested by the shapes of the implantation spikes

  13. Visualization of time-of-flight neutron diffraction data

    International Nuclear Information System (INIS)

    Mikkelson, D.J.; Price, D.L.; Worlton, T.G.

    1995-01-01

    The glass, liquids and amorphous materials diffractometer (GLAD) is a new instrument at the intense pulsed neutron source (IPNS) at Argonne National Laboratory. The GLAD currently has 218 linear position sensitive detectors arranged in five banks. Raw data collected from the instrument are typically split into 1000-1500 angular groups each of which contains approximately 2000 time channels. In order to obtain a meaningful overview of such a large amount of data, an interactive system to view the data has been designed. The system was implemented in C using the graphical kernel system (GKS) for portability.The system treats data from each bank of detectors as a three-dimensional data set with detector number, position along detector and time of flight as the three coordinate axes. The software then slices the data parallel to any of the coordinate planes and displays the slices as images. This approach has helped with the detailed analysis of detector electronics, verification of instrument calibration and resolution determination. In addition, it has helped to identify low-level background signals and provided insight into the overall operation of the instrument. ((orig.))

  14. Time-of-flight pulsed neutron diffraction of molten salts

    Energy Technology Data Exchange (ETDEWEB)

    Fukushima, Y; Misawa, M; Suzuki, K [Tohoku Univ., Sendai (Japan). Research Inst. for Iron, Steel and Other Metals

    1975-06-01

    In this work, the pulsed neutron diffraction of molten alkali metal nitrate and bismuth trihalide was measured by the time-of-flight method. An electron linear accelerator was used as the pulsed neutron source. All the measurements were carried out with the T-O-F neutron diffractometer installed on the 300 MeV electron lineac. Molten NaNO/sub 3/ and RbNO/sub 3/ were adopted as the samples for alkali metal nitrate. The measurement is in progress for KNO/sub 3/ and LiNO/sub 3/. As the first step of the study on bismuth-bismuth trihalide system, the temperature dependence of structure factors was observed for BiCl/sub 3/, BiBr/sub 3/ and BiI/sub 3/ in the liquid state. The structure factors Sm(Q) for molten NaNO/sub 3/ at 340/sup 0/C and RbNO/sub 3/ at 350/sup 0/C were obtained, and the form factor F/sub 1/(Q) for single NO/sub 3//sup -/ radical with equilateral triangle structure was calculated. In case of molten NaNO/sub 3/, the first peak of Sm(Q) is simply smooth and a small hump can be observed in the neighbourhood of the first minimum Q position. The first peak of Sm(Q) for molten RbNO/sub 3/ is divided into two peaks, whereas a hump at the first minimum becomes big, and shifts to the low Q side of the second peak. The size of the NO/sub 3//sup -/ radical in molten NaNO/sub 3/ is a little smaller than that in molten RbNO/sub 3/. The values of the bond length in the NO/sub 3//sup -/ radical are summarized for crystal state and liquid state. The temperature dependence of the structure factor S(Q) was observed for BiCl/sub 3/, BiBr/sub 3/ and BiI/sub 3/, and shown in a figure.

  15. TOF-SEMSANS—Time-of-flight spin-echo modulated small-angle neutron scattering

    NARCIS (Netherlands)

    Strobl, M.; Tremsin, A.S.; Hilger, A.; Wieder, F.; Kardjilov, N.; Manke, I.; Bouwman, W.G.; Plomp, J.

    2012-01-01

    We report on measurements of spatial beam modulation of a polarized neutron beam induced by triangular precession regions in time-of-flight mode and the application of this novel technique spin-echo modulated small-angle neutron scattering (SEMSANS) to small-angle neutron scattering in the very

  16. The Dynamic Method for Time-of-Flight Measurement of Thermal Neutron Spectra from Pulsed Sources

    International Nuclear Information System (INIS)

    Pepelyshev, Yu.N.; Tulaev, A.B.; Bobrakov, V.F.

    1994-01-01

    The time-of-flight method for a measurement of thermal neutron spectra in the pulsed neutron sources with high efficiency of neutron registration, more than 10 5 times higher in comparison with traditional one, is described. The main problems connected with the electric current technique for time-of-flight spectra measurement are examined. The methodical errors, problems of a special neutron detector design and other questions are discussed. Some experimental results, spectra from surfaces of the water and solid methane moderators, obtained in the pulsed reactor IBR-2 (Dubna, Russia) are presented. 4 refs., 5 figs

  17. Time-of-flight spectrometer for the measurement of gamma correlated neutron spectra

    International Nuclear Information System (INIS)

    Andriashin, A.V.; Devkin, B.V.; Lychagin, A.A.; Minko, J.V.; Mironov, A.N.; Nesterenko, V.S.; Sztaricskai, T.; Petoe, G.; Vasvary, L.

    1986-01-01

    A time-of-flight spectrometer for the measurement of gamma correlated neutron spectra from (n,xnγ) reactions is described. The operation and the main parameters are discussed. The resolution in the neutron channel is 2.2 ns/m at the 150 keV neutron energy threshold. A simultaneous measurement of the time-of-flight and amplitude distributions makes it possible to study gamma correlated neutron spectra as well as the prompt gamma spectra in coincidence with selected energy neutrons. In order to test the spectrometer, measurements of the neutron spectrum in coincidence with the 846 keV gamma line of 56 Fe were carried out at an incident neutron energy of 14.1 MeV. (Auth.)

  18. Time-of-flight spectrometer for the measurement of gamma correlated neutron spectra

    International Nuclear Information System (INIS)

    Andryashin, A.V.; Devlein, B.V.; Lychagin, A.A.; Minko, Y.V.; Mironov, A.N.; Nesterenko, V.S.

    1986-01-01

    A time-of-flight spectrometer for the measurement of gamma correlated neutron spectra form (n,xnγ) reactions is described. The operation and the main parameters are discussed. The resolution in the neutron channel is 2.2 ns/m at the 150 keV neutron energy threshold. A simultaneous measurement of the time-of-flight and amplitude distributions makes it possible to study gamma correlated neutron spectra as well as the prompt gamma spectra in coincidence with selected energy neutrons. In order to test the spectrometer, measurements of the neutron spectrum in coincidence with the 846 keV gamma line of 56 Fe were carried out at an incident neutron energy of 14.1 MeV. (author). 3 figs., 6 refs

  19. A neutron time of flight spectrometer appropriate for D-T plasma diagnostics

    International Nuclear Information System (INIS)

    Elevant, T.

    1984-02-01

    A neutron time-of-flight spectrometer with 2 m flight path for diagnostics of deuterium plasmas in JET is presently under construction. An upgrade of this spectrometer to make it appropriate for 14-MeV neutron spectroscopy is presented here. It is suggested to use backscattering in a deuterium based scintillator. The flight path length is 1-2 m and the efficiency is of the order of 2.10 -5 cm -5 . Results from test of principle are presented with estimates for neutron and gamma backgrounds

  20. Residual stress analysis by neutron time-of-flight at a reactor source

    International Nuclear Information System (INIS)

    Priesmeyer, H.G.; Schroder, J.

    1990-01-01

    Non-destructive neutron diffractometry for stress analysis will be a powerful experimental tool in material science research performed at the GKSS 5 MW reactor FRG-1. Arguments which show the advantages of the time-of-flight method are given and a suitable high-resolution neutron-efficient type of spectrometer is introduced. First results derived from this method are presented

  1. WINTOF - A program to produce neutron spectra from Zebra time-of-flight experiments

    International Nuclear Information System (INIS)

    Marshall, J.

    1969-06-01

    This report describes a computer program, written for the Winfrith KDF9 computer, which is used to calculate the neutron energy spectrum in the Zebra reactor from neutron time-of-flight measurements using the Zebra Linac. The data requirements for the program are specified and an illustration of the final spectrum is included. (author)

  2. FOCUS: neutron time-of-flight spectrometer at SINQ: recent progress

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, S.; Mesot, J.; Holitzner, L. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Hempelmann, R. [Saarbruecken Univ. (Germany)

    1997-09-01

    At the Swiss neutron spallation source SINQ a time-of-flight spectrometer for cold neutrons is under construction. The design foresees a Hybrid solution combining a Fermi chopper with a doubly focusing crystal monochromator. During 1996 important progress has been made concerning the main spectrometer components such as the spectrometer housing and the detector system. (author) 2 figs., 3 refs.

  3. Incident spectrum determination for time-of-flight neutron powder diffraction data analysis

    International Nuclear Information System (INIS)

    Hodges, J. P.

    1998-01-01

    Accurate characterization of the incident neutron spectrum is an important requirement for precise Rietveld analysis of time-of-flight powder neutron diffraction data. Without an accurate incident spectrum the calculated model for the measured relative intensities of individual Bragg reflections will possess systematic errors. We describe a method for obtaining an accurate numerical incident spectrum using data from a transmitted beam monitor

  4. Proceedings of the 1986 workshop on advanced time-of-flight neutron powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Lawson, A.C.; Smith, K. (comps.)

    1986-09-01

    This report contains abstracts of talks and summaries of discussions from a small workshop held to discuss the future of time-of-flight neutron powder diffraction and its implementation at the Los Alamos Neutron Scattering Center. 47 refs., 3 figs.

  5. Experiments at the time-of-flight neutron spectrometer GNEIS in Gatchina

    International Nuclear Information System (INIS)

    Shcherbakov, O.A.

    1990-01-01

    A brief description of the Gatchina neutron time-of-flight spectrometer GNEIS at the 1 GeV proton synchrocyclotron and its main characteristics are given. Some results of the nuclear fission experiments and neutron cross section measurements are presented not only to illustrate the facility performance but to outline the basic directions of the researches as well. 28 refs.; 10 figs

  6. Proceedings of the 1986 workshop on advanced time-of-flight neutron powder diffraction

    International Nuclear Information System (INIS)

    Lawson, A.C.; Smith, K.

    1986-09-01

    This report contains abstracts of talks and summaries of discussions from a small workshop held to discuss the future of time-of-flight neutron powder diffraction and its implementation at the Los Alamos Neutron Scattering Center. 47 refs., 3 figs

  7. Time-of-flight neutron spectra measurements in Zenith

    Energy Technology Data Exchange (ETDEWEB)

    Barclay, F R; Coates, M S; Diment, K M; Durrani, S A; Gayther, D B; Poole, M J; Reed, D L

    1962-01-15

    Neutron spectra in the second core loading of ZENITH have been measured using a neutron chopper. Spectra at two positions in the reactore core were obtained over a range of temperatures extending to 650 deg C.

  8. The dynamic method for time-of-flight measurement of thermal neutron spectra from pulsed sources

    International Nuclear Information System (INIS)

    Pepyolyshev, Yu.N.; Chuklyaev, S.V.; Tulaev, A.B.; Bobrakov, V.F.

    1995-01-01

    A time-of-flight method for measurement of thermal neutron spectra in pulsed neutron sources with an efficiency more than 10 5 times higher than the standard method is described. The main problems associated with the electric current technique for time-of-flight spectra measurement are examined. The methodical errors, problems of special neutron detector design and other questions are discussed. Some experimental results for spectra from the surfaces of water and solid methane moderators obtained at the IBR-2 pulsed reactor (Dubna, Russia) are presented. (orig.)

  9. Time-of-flight and vector polarization analysis for diffuse neutron scattering

    International Nuclear Information System (INIS)

    Schweika, W.

    2003-01-01

    The potential of pulsed neutron sources for diffuse scattering including time-of-flight (TOF) and polarization analysis is discussed in comparison to the capabilities of the present instrument diffuse neutron scattering at the research center Juelich. We present first results of a new method for full polarization analysis using precessing neutron polarization. A proposal is made for a new type of instrument at pulsed sources, which allows for vector polarization analysis in TOF instruments with multi-detectors

  10. Pseudo-random neutron time-of-flight spectroscopy using a Van de Graaff accelerator as neutron source

    International Nuclear Information System (INIS)

    Duquesne, Henry; Schmitt, Andre; Poussot, Rene; Pelicier, Henri.

    1976-05-01

    The classical experiments of neutron time-of-flight spectrometry on bulk multiplying media are using recurrent neutron bursts from a linear accelerator. The adaptation of the ion beam issued from the Cadarache Van de Graaff accelerator is described with the test experiments which were effected. Both methods are compared with respect to the accuracy obtained, the energy resolution and the time consumed [fr

  11. A Time of flight spectrometer for measurements of double differential neutron scattering cross sections

    International Nuclear Information System (INIS)

    Padron, I.; Dominguez, O.; Sarria, P. Sandin, C.

    1996-01-01

    The time -of-Flight neutron spectrometry technique by associated particle method was improved using a D-T neutron generator at Laboratory of Nuclear Analysis. This technique was implemented for double differential cross section measurements and supported by the IAEA Project CUB/01/005. An stilbene scintillation detector (dia=100 mm, length=50 mm) was used as principal neutron detector detector and was situated outside a hole in the concrete wall. This way the fligth path was extended and the scattered neutron cone accurate collimated throught the 2 m concrete wall. For the associated particle α detection a thin plastic NE-102 scint illator was used, as well as, two scintilation detectors and a long counter for the neutron flux monitoring. In this TOF neutron spectrometer (3.40 m flight path) a 1.7 nseg. temporal resolution was obtained

  12. Design study of a time-of-flight neutron spectrometer for JT-60U

    International Nuclear Information System (INIS)

    Elevant, T.; Hoek, M.; Nishitani, Takeo.

    1993-06-01

    A time-of-flight neutron spectrometer is proposed for measurements of neutron energy spectra from deuterium-deuterium reactions in JT-60U tokamak plasmas. The sensitivity of the instrument is 2 · 10 -2 cm 2 , energy resolution is 4.5 % (FWHM) and maximum useful count-rate is 6 kHz. Analysis of neutron energy spectra will provide information on central ion temperatures larger than ∼ 4 keV with an accuracy of ± 10 %, and neutron source fraction from reactions between thermal ions with an accuracy of ± 15 %. The minimum time required for data acquisition is 0.1 s. (author)

  13. DNS: Diffuse scattering neutron time-of-flight spectrometer

    Directory of Open Access Journals (Sweden)

    Yixi Su

    2015-08-01

    Full Text Available DNS is a versatile diffuse scattering instrument with polarisation analysis operated by the Jülich Centre for Neutron Science (JCNS, Forschungszentrum Jülich GmbH, outstation at the Heinz Maier-Leibnitz Zentrum (MLZ. Compact design, a large double-focusing PG monochromator and a highly efficient supermirror-based polarizer provide a polarized neutron flux of about 107 n cm-2 s-1. DNS is used for the studies of highly frustrated spin systems, strongly correlated electrons, emergent functional materials and soft condensed matter.

  14. A time-of-flight detector for thermal neutrons from radiotherapy Linacs

    Energy Technology Data Exchange (ETDEWEB)

    Conti, V. [Universita degli Studi di Milano and INFN di Milano (Italy)], E-mail: conti.Valentina@gmail.com; Bartesaghi, G. [Universita degli Studi di Milano and INFN di Milano (Italy); Bolognini, D.; Mascagna, V.; Perboni, C.; Prest, M.; Scazzi, S. [Universita dell' Insubria, Como and INFN di Milano (Italy); Mozzanica, A. [Universita degli Studi di Brescia and INFN sezione di Pavia (Italy); Cappelletti, P.; Frigerio, M.; Gelosa, S.; Monti, A.; Ostinelli, A. [Fisica Sanitaria, Ospedale S. Anna di Como (Italy); Giannini, G.; Vallazza, E. [INFN, sezione di Trieste and Universita degli Studi di Trieste (Italy)

    2007-10-21

    Boron Neutron Capture Therapy (BNCT) is a therapeutic technique exploiting the release of dose inside the tumour cell after a fission of a {sup 10}B nucleus following the capture of a thermal neutron. BNCT could be the treatment for extended tumors (liver, stomach, lung), radio-resistant ones (melanoma) or tumours surrounded by vital organs (brain). The application of BNCT requires a high thermal neutron flux (>5x10{sup 8}ncm{sup -2}s{sup -1}) with the correct energy spectrum (neutron energy <10keV), two requirements that for the moment are fulfilled only by nuclear reactors. The INFN PhoNeS (Photo Neutron Source) project is trying to produce such a neutron beam with standard radiotherapy Linacs, maximizing with a dedicated photo-neutron converter the neutrons produced by Giant Dipole Resonance by a high energy (>8MeV) photon beam. In this framework, we have developed a real-time detector to measure the thermal neutron time-of -flight to compute the flux and the energy spectrum. Given the pulsed nature of Linac beams, the detector is a single neutron counting system made of a scintillator detecting the photon emitted after the neutron capture by the hydrogen nuclei. The scintillator signal is sampled by a dedicated FPGA clock thus obtaining the exact arrival time of the neutron itself. The paper will present the detector and its electronics, the feasibility measurements with a Varian Clinac 1800/2100CD and comparison with a Monte Carlo simulation.

  15. Measurement of Neutron Energy Spectrum Emitted by Cf-252 Source Using Time-of-Flight Method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Cheol Ho; Son, Jaebum; Kim, Tae Hoon; Lee, Sangmin; Kim, Yong-Kyun [Hanyang University, Seoul (Korea, Republic of)

    2016-10-15

    The techniques proposed to detect the neutrons usually require the detection of a secondary recoiling nucleus in a scintillator (or other type of detector) to indicate the rare collision of a neutron with a nucleus. This is the same basic technique, in this case detection of a recoil proton that was used by Chadwick in the 1930 s to discover and identify the neutron and determine its mass. It is primary technique still used today for detection of fast neutron, which typically involves the use of a hydrogen based organic plastic or liquid scintillator coupled to a photo-multiplier tube. The light output from such scintillators is a function of the cross section and nuclear kinematics of the n + nucleus collision. With the exception of deuterated scintillators, the scintillator signal does not necessarily produce a distinct peak in the scintillator spectrum directly related to the incident neutron energy. Instead neutron time-of-flight (TOF) often must be utilized to determine the neutron energy, which requires generation of a prompt start signal from the nuclear source emitting the neutrons. This method takes advantage of the high number of prompt gamma rays. The Time-of-Flight method was used to measure neutron energy spectrum emitted by the Cf-252 neutron source. Plastic scintillator that has a superior discrimination ability of neutron and gamma-ray was used as a stop signal detector and liquid scintillator was used as a stat signal detector. In experiment, neutron and gamma-ray spectrum was firstly measured and discriminated using the TOF method. Secondly, neutron energy spectrum was obtained through spectrum analysis. Equation of neutron energy spectrum that was emitted by Cf-252 source using the Gaussian fitting was obtained.

  16. Neutron Spectroscopy for pulsed beams with frame overlap using a double time-of-flight technique

    Science.gov (United States)

    Harrig, K. P.; Goldblum, B. L.; Brown, J. A.; Bleuel, D. L.; Bernstein, L. A.; Bevins, J.; Harasty, M.; Laplace, T. A.; Matthews, E. F.

    2018-01-01

    A new double time-of-flight (dTOF) neutron spectroscopy technique has been developed for pulsed broad spectrum sources with a duty cycle that results in frame overlap, where fast neutrons from a given pulse overtake slower neutrons from previous pulses. Using a tunable beam at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory, neutrons were produced via thick-target breakup of 16 MeV deuterons on a beryllium target in the cyclotron vault. The breakup spectral shape was deduced from a dTOF measurement using an array of EJ-309 organic liquid scintillators. Simulation of the neutron detection efficiency of the scintillator array was performed using both GEANT4 and MCNP6. The efficiency-corrected spectral shape was normalized using a foil activation technique to obtain the energy-dependent flux of the neutron beam at zero degrees with respect to the incoming deuteron beam. The dTOF neutron spectrum was compared to spectra obtained using HEPROW and GRAVEL pulse height spectrum unfolding techniques. While the unfolding and dTOF results exhibit some discrepancies in shape, the integrated flux values agree within two standard deviations. This method obviates neutron time-of-flight spectroscopy challenges posed by pulsed beams with frame overlap and opens new opportunities for pulsed white neutron source facilities.

  17. Use of a large time-compensated scintillation detector in neutron time-of-flight measurements

    International Nuclear Information System (INIS)

    Goodman, C.D.

    1979-01-01

    A scintillator for neutron time-of-flight measurements is positioned at a desired angle with respect to the neutron beam, and as a function of the energy thereof, such that the sum of the transit times of the neutrons and photons in the scintillator are substantially independent of the points of scintillations within the scintillator. Extrapolated zero timing is employed rather than the usual constant fraction timing. As a result, a substantially larger scintillator can be employed that substantially increases the data rate and shortens the experiment time. 3 claims

  18. Fast neutron measurements at the nELBE time-of-flight facility

    Directory of Open Access Journals (Sweden)

    Junghansa A. R.

    2015-01-01

    Full Text Available The compact neutron-time-of-flight facility nELBE at the superconducting electron accelerator ELBE of Helmholtz-Zentrum Dresden-Rossendorf has been rebuilt. A new enlarged experimental hall with a flight path of up to 10 m is available for neutron time-of-flight experiments in the fast energy range from about 50 keV to 10 MeV. nELBE is intended to deliver nuclear data of fast neutron nuclear interactions e.g. for the transmutation of nuclear waste and improvement of neutron physical simulations of innovative nuclear systems. The experimental programme consists of transmission measurements of neutron total cross sections, elastic and inelastic scattering cross section measurements, and neutron induced fission cross sections. The inelastic scattering to the first few excited states in 56Fe was investigated by measuring the gamma production cross section with an HPGe detector. The neutron induced fission of 242Pu was studied using fast ionisation chambers with large homogeneous actinide deposits.

  19. Development and Applications of Time of Flight Neutron Depth Profiling

    International Nuclear Information System (INIS)

    Cady, Bingham; Unlu, Kenan

    2005-01-01

    The depth profiles of intentional or intrinsic constituents of a sample provide valuable information for the characterization of materials. For example, the subtle differences in spatial distribution and composition of many chemical species in the near surface region and across interfacial boundaries can significantly alter the electronic and optical properties of materials. A number of analytical techniques for depth profiling have been developed during the last two decades. neutron Depth Profiling (NDP) is one of the leading analytical techniques. The NDP is a nondestructive near surface technique that utilizes thermal/cold neutron beam to measure the concentration of specific light elements versus their depth in materials. The depth is obtained from the energy loss of protons, alphas or recoil atoms in substrate materials. Since the charged particle energy determination using surface barrier detector is used for NDP, the depth resolution is highly dependent on the detectors an d detection instruments. The depth resolutions of a few tens of nm are achieved with available NDP facilities in the world. However, the performance of NDP needs to be improved in order to obtain a few A depth resolutions

  20. Time-of-Flight Three Dimensional Neutron Diffraction in Transmission Mode for Mapping Crystal Grain Structures

    DEFF Research Database (Denmark)

    Cereser, Alberto; Strobl, Markus; Hall, Stephen A.

    2017-01-01

    constituting the material. This article presents a new non-destructive 3D technique to study centimeter-sized bulk samples with a spatial resolution of hundred micrometers: time-of-flight three-dimensional neutron diffraction (ToF 3DND). Compared to existing analogous X-ray diffraction techniques, ToF 3DND......-of-flight neutron beamline. The technique was developed and tested with data collected at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Complex (J-PARC) for an iron sample. We successfully reconstructed the shape of 108 grains and developed an indexing procedure...

  1. Computer-controlled neutron time-of-flight spectrometer. Part II

    International Nuclear Information System (INIS)

    Merriman, S.H.

    1979-12-01

    A time-of-flight spectrometer for neutron inelastic scattering research has been interfaced to a PDP-15/30 computer. The computer is used for experimental data acquisition and analysis and for apparatus control. This report was prepared to summarize the functions of the computer and to act as a users' guide to the software system

  2. Geometry Survey of the Time-of-Flight Neutron-Elastic Scattering (Antonella) Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Oshinowo, Babatunde O. [Fermilab; Izraelevitch, Federico [Buenos Aires U.

    2016-10-17

    The Antonella experiment is a measurement of the ionization efficiency of nuclear recoils in silicon at low energies [1]. It is a neutron elastic scattering experiment motivated by the search for dark matter particles. In this experiment, a proton beam hits a lithium target and neutrons are produced. The neutron shower passes through a collimator that produces a neutron beam. The beam illuminates a silicon detector. With a certain probability, a neutron interacts with a silicon nucleus of the detector producing elastic scattering. After the interaction, a fraction of the neutron energy is transferred to the silicon nucleus which acquires kinetic energy and recoils. This kinetic energy is then dissipated in the detector producing ionization and thermal energy. The ionization produced is measured with the silicon detector electronics. On the other hand, the neutron is scattered out of the beam. A neutron-detector array (made of scintillator bars) registers the neutron arrival time and the scattering angle to reconstruct the kinematics of the neutron-nucleus interaction with the time-of-flight technique [2]. In the reconstruction equations, the energy of the nuclear recoil is a function of the scattering angle with respect to the beam direction, the time-of-flight of the neutron and the geometric distances between components of the setup (neutron-production target, silicon detector, scintillator bars). This paper summarizes the survey of the different components of the experiment that made possible the off-line analysis of the collected data. Measurements were made with the API Radian Laser Tracker and I-360 Probe Wireless. The survey was completed at the University of Notre Dame, Indiana, USA in February 2015.

  3. Calibration of the time response functions of a quenched plastic scintillator for neutron time of flight

    CERN Document Server

    Chen, J B; Peng, H S; Tang, C H; Zhang, B H; Ding, Y K; Chen, M; Chen, H S; Li, C G; Wen, T S; Yu, R Z

    2002-01-01

    The time response functions of an ultrafast quenched plastic scintillation detector used to measure neutron time of flight spectra were calibrated by utilizing cosmic rays and implosion neutrons from DT-filled capsules at the Shenguang II laser facility. These sources could be regarded as delta function pulses due to their much narrower time widths than those of the time response functions of the detection system. The results showed that the detector responses to DT neutrons and to cosmic rays were 1.18 and 0.96 ns FWHM, respectively.

  4. Calibration of time of flight detectors using laser-driven neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Mirfayzi, S. R.; Kar, S., E-mail: s.kar@qub.ac.uk; Ahmed, H.; Green, A.; Alejo, A.; Jung, D. [Centre for Plasma Physics, School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN (United Kingdom); Krygier, A. G.; Freeman, R. R. [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States); Clarke, R. [Central Laser Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX (United Kingdom); Fuchs, J.; Vassura, L. [LULI, Ecole Polytechnique, CNRS, Route de Saclay, 91128 Palaiseau Cedex (France); Kleinschmidt, A.; Roth, M. [Institut für Kernphysik, Technische Universität Darmstadt, Schloßgartenstrasse 9, D-64289 Darmstadt,Germany (Germany); Morrison, J. T. [Propulsion Systems Directorate, Air Force Research Lab, Wright Patterson Air Force Base, Ohio 45433 (United States); Najmudin, Z.; Nakamura, H. [Blackett Laboratory, Department of Physics, Imperial College, London SW7 2AZ (United Kingdom); Norreys, P. [Central Laser Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX (United Kingdom); Department of Physics, University of Oxford, Oxford OX1 3PU (United Kingdom); Oliver, M. [Department of Physics, University of Oxford, Oxford OX1 3PU (United Kingdom); Zepf, M. [Centre for Plasma Physics, School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN (United Kingdom); Helmholtz Institut Jena, D-07743 Jena (Germany); Borghesi, M. [Centre for Plasma Physics, School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN (United Kingdom); Institute of Physics of the ASCR, ELI-Beamlines Project, Na Slovance 2, 18221 Prague (Czech Republic)

    2015-07-15

    Calibration of three scintillators (EJ232Q, BC422Q, and EJ410) in a time-of-flight arrangement using a laser drive-neutron source is presented. The three plastic scintillator detectors were calibrated with gamma insensitive bubble detector spectrometers, which were absolutely calibrated over a wide range of neutron energies ranging from sub-MeV to 20 MeV. A typical set of data obtained simultaneously by the detectors is shown, measuring the neutron spectrum emitted from a petawatt laser irradiated thin foil.

  5. Calibration of time of flight detectors using laser-driven neutron source

    Science.gov (United States)

    Mirfayzi, S. R.; Kar, S.; Ahmed, H.; Krygier, A. G.; Green, A.; Alejo, A.; Clarke, R.; Freeman, R. R.; Fuchs, J.; Jung, D.; Kleinschmidt, A.; Morrison, J. T.; Najmudin, Z.; Nakamura, H.; Norreys, P.; Oliver, M.; Roth, M.; Vassura, L.; Zepf, M.; Borghesi, M.

    2015-07-01

    Calibration of three scintillators (EJ232Q, BC422Q, and EJ410) in a time-of-flight arrangement using a laser drive-neutron source is presented. The three plastic scintillator detectors were calibrated with gamma insensitive bubble detector spectrometers, which were absolutely calibrated over a wide range of neutron energies ranging from sub-MeV to 20 MeV. A typical set of data obtained simultaneously by the detectors is shown, measuring the neutron spectrum emitted from a petawatt laser irradiated thin foil.

  6. Calibration of time of flight detectors using laser-driven neutron source

    International Nuclear Information System (INIS)

    Mirfayzi, S. R.; Kar, S.; Ahmed, H.; Green, A.; Alejo, A.; Jung, D.; Krygier, A. G.; Freeman, R. R.; Clarke, R.; Fuchs, J.; Vassura, L.; Kleinschmidt, A.; Roth, M.; Morrison, J. T.; Najmudin, Z.; Nakamura, H.; Norreys, P.; Oliver, M.; Zepf, M.; Borghesi, M.

    2015-01-01

    Calibration of three scintillators (EJ232Q, BC422Q, and EJ410) in a time-of-flight arrangement using a laser drive-neutron source is presented. The three plastic scintillator detectors were calibrated with gamma insensitive bubble detector spectrometers, which were absolutely calibrated over a wide range of neutron energies ranging from sub-MeV to 20 MeV. A typical set of data obtained simultaneously by the detectors is shown, measuring the neutron spectrum emitted from a petawatt laser irradiated thin foil

  7. Rietveld refinement with time-of-flight powder diffraction data from pulsed neutron sources

    International Nuclear Information System (INIS)

    David, W.I.F.; Jorgensen, J.D.

    1990-10-01

    The recent development of accelerator-based pulsed neutron sources has led to the widespread use of the time-of-flight technique for neutron powder diffraction. The properties of the pulsed source make possible unusually high resolution over a wide range of d spacings, high count rates, and the ability to collect complete data at fixed scattering angles. The peak shape and other instrument characteristics can be accurately modelled, which make Rietveld refinement possible for complex structures. In this paper we briefly review the development of the Rietveld method for time-of-flight diffraction data from pulsed neutron sources and discuss the latest developments in high resolution instrumentation and advanced Rietveld analysis methods. 50 refs., 12 figs., 14 tabs

  8. Time-of-flight discrimination between gamma-rays and neutrons by using artificial neural networks

    International Nuclear Information System (INIS)

    Akkoyun, S.

    2013-01-01

    Highlights: ► Time-of-flight (tof) is an obvious method for separation between gamma and neutron particles. ► tof distributions are obtained by neural networks. ► Neural network method is consistent with the experimental results. ► Neural networks can classify different events for discrimination. - Abstract: In gamma-ray spectroscopy, a number of neutrons are emitted from the nuclei together with the gamma-rays. These neutrons influence gamma-ray spectra. An obvious method for discrimination between neutrons and gamma-rays is based on the time-of-flight (tof) technique. In this work, the tof distributions of gamma-rays and neutrons were obtained both experimentally and by using artificial neural networks (ANNs). It was shown that, ANN can correctly classify gamma-ray and neutron events. Also, for highly nonlinear detector response for tof, we have constructed consistent empirical physical formulas (EPFs) by appropriate ANNs. These ANN–EPFs can be used to derive further physical functions which could be relevant to discrimination between gamma-rays and neutrons

  9. Time-of-flight diffraction at pulsed neutron sources: An introduction to the symposium

    International Nuclear Information System (INIS)

    Jorgensen, J.D.

    1994-01-01

    In the 25 years since the first low-power demonstration experiments, pulsed neutron sources have become as productive as reactor sources for many types of diffraction experiments. The pulsed neutron sources presently operating in the United States, England, and Japan offer state of the art instruments for powder and single crystal diffraction, small angle scattering, and such specialized techniques as grazing-incidence neutron reflection, as well as quasielastic and inelastic scattering. In this symposium, speakers review the latest advances in diffraction instrumentation for pulsed neutron sources and give examples of some of the important science presently being done. In this introduction to the symposium, I briefly define the basic principles of pulsed neutron sources, review their development, comment in general terms on the development of time-of-flight diffraction instrumentation for these sources, and project how this field will develop in the next ten years

  10. Invited article: polarization "down under": the polarized time-of-flight neutron reflectometer PLATYPUS.

    Science.gov (United States)

    Saerbeck, T; Klose, F; Le Brun, A P; Füzi, J; Brule, A; Nelson, A; Holt, S A; James, M

    2012-08-01

    This review presents the implementation and full characterization of the polarization equipment of the time-of-flight neutron reflectometer PLATYPUS at the Australian Nuclear Science and Technology Organisation (ANSTO). The functionality and efficiency of individual components are evaluated and found to maintain a high neutron beam polarization with a maximum of 99.3% through polarizing Fe/Si supermirrors. Neutron spin-flippers with efficiencies of 99.7% give full control over the incident and scattered neutron spin direction over the whole wavelength spectrum available in the instrument. The first scientific experiments illustrate data correction mechanisms for finite polarizations and reveal an extraordinarily high reproducibility for measuring magnetic thin film samples. The setup is now fully commissioned and available for users through the neutron beam proposal system of the Bragg Institute at ANSTO.

  11. ICF implosion hotspot ion temperature diagnostic techniques based on neutron time-of-flight method

    International Nuclear Information System (INIS)

    Tang Qi; Song Zifeng; Chen Jiabin; Zhan Xiayu

    2013-01-01

    Ion temperature of implosion hotspot is a very important parameter for inertial confinement fusion. It reflects the energy level of the hotspot, and it is very sensitive to implosion symmetry and implosion speed. ICF implosion hotspot ion temperature diagnostic techniques based on neutron time-of-flight method were described. A neutron TOF spectrometer was developed using a ultrafast plastic scintillator as the neutron detector. Time response of the spectrometer has 1.1 ns FWHM and 0.5 ns rising time. TOF spectrum resolving method based on deconvolution and low pass filter was illuminated. Implosion hotspot ion temperature in low neutron yield and low ion temperature condition at Shenguang-Ⅲ facility was acquired using the diagnostic techniques. (authors)

  12. Tests and Calibration of the NIF Neutron Time of Flight Detectors

    International Nuclear Information System (INIS)

    Ali, Z.A.; Glebov, V.Yu.; Cruz, M.; Duffy, T.; Stoeckl, C.; Roberts, S.; Sangster, T.C.; Tommasini, R.; Throop, A; Moran, M.; Dauffy, L.; Horsefield, C.

    2008-01-01

    The National Ignition Facility (NIF) Neutron Time of Flight (NTOF) diagnostic will measure neutron yield and ion temperature in all NIF campaigns in DD, DT, and THD (D = deuterium, T = tritium, H = hydrogen) implosions. The NIF NTOF diagnostic is designed to measure neutron yield from 10 9 to 2 x 10 19 . The NTOF consists of several detectors of varying sensitivity located on the NIF at about 5 m and 20 m from the target. Production, testing, and calibration of the NIF NTOF detectors have begun at the Laboratory for Laser Energetics (LLE). Operational tests of the NTOF detectors were performed on several facilities including the OMEGA laser at LLE and the Titan laser at Lawrence Livermore National Laboratory (LLNL). Neutron calibrations were carried out on the OMEGA laser. Results of the NTOF detectors tests and calibration will be presented

  13. The new JET 2.5-MeV neutron time-of-flight spectrometer

    International Nuclear Information System (INIS)

    Elevant, T.; Belle, P.v.; Grosshoeg, G.; Hoek, M.; Jarvis, O.N.; Olsson, M.; Sadler, G.

    1992-01-01

    A major upgrade of the JET 2.5-MeV neutron time-of-flight spectrometer has been completed. The improvement has permitted ion temperature measurements for Maxwellian deuterium plasmas with T i >4 keV to be obtained in 0.5-s intervals. By combining observations of neutron and x-ray energy spectra with studies of γ-ray emission from reactions between fast deuterons and impurities, the effects of ICRF heating on the deuterium energy distribution have been studied. The time evolution of neutron energy spectra from deuterium-beam heated deuterium plasmas is illustrated and a method for evaluating the ion temperature from such sequences is indicated. Furthermore, the spectrometer has shown stable performance during high neutron fluxes

  14. A real time scintillating fiber Time of Flight spectrometer for LINAC photoproduced neutrons

    Science.gov (United States)

    Maspero, M.; Berra, A.; Conti, V.; Giannini, G.; Ostinelli, A.; Prest, M.; Vallazza, E.

    2015-03-01

    The use of high-energy (> 8 MeV) LINear ACcelerators (LINACs) for medical cancer treatments causes the photoproduction of secondary neutrons, whose unwanted dose to the patient has to be calculated. The characterization of the neutron spectra is necessary to allow the dosimetric evaluation of the neutron beam contamination. The neutron spectrum in a hospital environment is usually measured with integrating detectors such as bubble dosimeters, Thermo Luminescent Dosimeters (TLDs) or Bonner Spheres, which integrate the information over a time interval and an energy one. This paper presents the development of a neutron spectrometer based on the Time of Flight (ToF) technique in order to perform a real time characterization of the neutron contamination. The detector measures the neutron spectrum exploiting the fact that the LINAC beams are pulsed and arranged in bunches with a rate of 100-300 Hz depending on the beam type and energy. The detector consists of boron loaded scintillating fibers readout by a MultiAnode PhotoMultiplier Tube (MAPMT). A detailed description of the detector and the acquisition system together with the results in terms of ToF spectra and number of neutrons with a Varian Clinac iX are presented.

  15. Timing and position response of a block detector for fast neutron time-of-flight imaging

    Energy Technology Data Exchange (ETDEWEB)

    Laubach, M.A., E-mail: mlaubach@utk.edu [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Hayward, J.P., E-mail: jhayward@utk.edu [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, TN 37831 (United States); Zhang, X., E-mail: xzhang39@utk.edu [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Cates, J.W., E-mail: jcates7@vols.utk.edu [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States)

    2014-11-01

    Our research effort seeks to improve the spatial and timing performance of a block detector made of a pixilated plastic scintillator (EJ-200), first demonstrated as part of Oak Ridge National Laboratory's Advanced Portable Neutron Imaging System. Improvement of the position and time response is necessary to achieve better resolution and contrast in the images of shielded special nuclear material. Time-of-flight is used to differentiate between gamma and different sources of neutrons (e.g., transmission and fission neutrons). Factors limiting the timing and position performance of the neutron detector have been revealed through simulations and measurements. Simulations have suggested that the degradation in the ability to resolve pixels in the neutron detector is due to those interactions occurring near the light guide. The energy deposition within the neutron detector is shown to affect position performance and imaging efficiency. This examination details how energy cuts improve the position performance and degrade the imaging efficiency. Measurements have shown the neutron detector to have a timing resolution of σ=238 ps. The majority of this timing uncertainty is from the depth-of-interaction (DOI) of the neutron which is confirmed by simulations and analytical calculations.

  16. Time lens for high-resolution neutron time-of-flight spectrometers

    International Nuclear Information System (INIS)

    Baumann, K.; Gaehler, R.; Grigoriev, P.; Kats, E.I.

    2005-01-01

    We examine in analytic and numeric ways the imaging effects of temporal neutron lenses created by traveling magnetic fields. For fields of parabolic shape we derive the imaging equations, investigate the time magnification, the evolution of the phase-space element, the gain factor, and the effect of finite beam size. The main aberration effects are calculated numerically. The system is technologically feasible and should convert neutron time-of-flight instruments from pinhole to imaging configuration in time, thus enhancing intensity and/or time resolution. Further fields of application for high-resolution spectrometry may be opened

  17. A time-of-flight neutron reflectometer for surface and interfacial studies

    International Nuclear Information System (INIS)

    Penfold, J.; Ward, R.C.; Williams, W.G.

    1987-03-01

    A time-of-flight neutron reflectometer constructed for surface and interfacial studies, and installed at the ISIS pulsed neutron source, is described. One of its important design features is its inclined incident beam, since this allows both liquid and solid surface phenomena to be investigated. Measurements are presented to show the performance of the instrument, and new representative results, which include studies of liquid surfaces, Langmuir-Blodgett films, and thin film multilayers, are included as illustrations of the scientific potential of the method. (author)

  18. A silicon photomultiplier readout for time of flight neutron spectroscopy with {gamma}-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Pietropaolo, A.; Gorini, G. [Dipartimento di Fisica ' ' G. Occhialini' ' and CNISM, Universita Degli Studi di Milano-Bicocca, Piazza della Scienza 3, 20126 Milano (Italy); Festa, G.; Andreani, C.; De Pascale, M. P.; Reali, E. [Dipartimento di Fisica and Centro NAST, Universita degli Studi di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133, Roma (Italy); Grazzi, F. [Istituto dei Sistemi Complessi-Consiglio Nazionale delle Ricerche, Via Madonna del Piano n.10, I-50019 Sesto Fiorentino, Firenze (Italy); Schooneveld, E. M. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX (United Kingdom)

    2009-09-15

    The silicon photomultiplier (SiPM) is a recently developed photosensor used in particle physics, e.g., for detection of minimum ionizing particles and/or Cherenkov radiation. Its performance is comparable to that of photomultiplier tubes, but with advantages in terms of reduced volume and magnetic field insensitivity. In the present study, the performance of a gamma ray detector made of an yttrium aluminum perovskite scintillation crystal and a SiPM-based readout is assessed for use in time of flight neutron spectroscopy. Measurements performed at the ISIS pulsed neutron source demonstrate the feasibility of {gamma}-detection based on the new device.

  19. Measurement of detector neutron energy response using time-of-flight techniques

    International Nuclear Information System (INIS)

    Janee, H.S.

    1973-09-01

    The feasibility of using time-of-flight techniques at the EG and G/AEC linear accelerator for measuring the neutron response of relatively sensitive detectors over the energy range 0.5 to 14 MeV has been demonstrated. The measurement technique is described in detail as are the results of neutron spectrum measurements from beryllium and uranium photoneutron targets. The sensitivity of a fluor photomultiplier LASL detector with a 2- by 1-inch NE-111 scintillator was determined with the two targets, and agreement in the region of overlap was very good. (U.S.)

  20. Testing a new NIF neutron time-of-flight detector with a bibenzyl scintillator on OMEGA.

    Science.gov (United States)

    Glebov, V Yu; Forrest, C; Knauer, J P; Pruyne, A; Romanofsky, M; Sangster, T C; Shoup, M J; Stoeckl, C; Caggiano, J A; Carman, M L; Clancy, T J; Hatarik, R; McNaney, J; Zaitseva, N P

    2012-10-01

    A new neutron time-of-flight (nTOF) detector with a bibenzyl crystal as a scintillator has been designed and manufactured for the National Ignition Facility (NIF). This detector will replace a nTOF20-Spec detector with an oxygenated xylene scintillator currently operational on the NIF to improve the areal-density measurements. In addition to areal density, the bibenzyl detector will measure the D-D and D-T neutron yield and the ion temperature of indirect- and direct-drive-implosion experiments. The design of the bibenzyl detector and results of tests on the OMEGA Laser System are presented.

  1. The multiple disk chopper neutron time-of-flight spectrometer at NIST

    International Nuclear Information System (INIS)

    Altorfer, F.B.; Cook, J.C.; Copley, J.R.D.

    1995-01-01

    A highly versatile multiple disk chopper neutron time-of-flight spectrometer is being installed at the Cold Neutron Research Facility of the National institute of Standards and Technology. This new instrument will fill an important gap in the portfolio of neutron inelastic scattering spectrometers in North America. It will be used for a wide variety of experiments such as studies of magnetic and vibrational excitations, tunneling spectroscopy, and quasielastic neutron scattering investigations of local and translational diffusion. The instrument uses disk choppers to monochromate and pulse the incident beam, and the energy changes of scattered neutrons are determined from their times-of-flight to a large array of detectors. The disks and the guide have been designed to make the instrument readily adaptable to the specific performance requirements of experimenters. The authors present important aspects of the design, as well as estimated values of the flux at the sample and the energy resolution for elastic scattering. The instrument should be operational in 1996

  2. Parameters’ Covariance in Neutron Time of Flight Analysis – Explicit Formulae

    Energy Technology Data Exchange (ETDEWEB)

    Odyniec, M. [NSTec; Blair, J. [NSTec

    2014-12-01

    We present here a method that estimates the parameters’ variance in a parametric model for neutron time of flight (NToF). The analytical formulae for parameter variances, obtained independently of calculation of parameter values from measured data, express the variances in terms of the choice, settings, and placement of the detector and the oscilloscope. Consequently, the method can serve as a tool in planning a measurement setup.

  3. Neutron xyz - polarization analysis at a time-of-flight instrument

    Energy Technology Data Exchange (ETDEWEB)

    Ehlers, Georg [ORNL; Stewart, John Ross [ISIS Facility, Rutherford Appleton Laboratory; Andersen, Ken [ESS

    2015-01-01

    When implementing a dedicated polarization analysis setup at a neutron time-of-flight instrument with a large area detector, one faces enormous challenges. Nevertheless, significant progress has been made towards this goal over the last few years. This paper addresses systematic limitations of the traditional method that is used to make these measurements, and a possible strategy to overcome these limitations. This will be important, for diffraction as well as inelastic experiments, where the scattering occurs mostly out-of-plane.

  4. Analysis of the neutron time-of-flight spectra from inertial confinement fusion experiments

    Energy Technology Data Exchange (ETDEWEB)

    Hatarik, R., E-mail: hatarik1@llnl.gov; Sayre, D. B.; Caggiano, J. A.; Phillips, T.; Eckart, M. J.; Bond, E. J.; Cerjan, C.; Grim, G. P.; Hartouni, E. P.; Mcnaney, J. M.; Munro, D. H. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Knauer, J. P. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

    2015-11-14

    Neutron time-of-flight diagnostics have long been used to characterize the neutron spectrum produced by inertial confinement fusion experiments. The primary diagnostic goals are to extract the d + t → n + α (DT) and d + d → n + {sup 3}He (DD) neutron yields and peak widths, and the amount DT scattering relative to its unscattered yield, also known as the down-scatter ratio (DSR). These quantities are used to infer yield weighted plasma conditions, such as ion temperature (T{sub ion}) and cold fuel areal density. We report on novel methodologies used to determine neutron yield, apparent T{sub ion}, and DSR. These methods invoke a single temperature, static fluid model to describe the neutron peaks from DD and DT reactions and a spline description of the DT spectrum to determine the DSR. Both measurements are performed using a forward modeling technique that includes corrections for line-of-sight attenuation and impulse response of the detection system. These methods produce typical uncertainties for DT T{sub ion} of 250 eV, 7% for DSR, and 9% for the DT neutron yield. For the DD values, the uncertainties are 290 eV for T{sub ion} and 10% for the neutron yield.

  5. Neutron time-of-flight counters and spectrometers for diagnostics of burning fusion plasmas

    International Nuclear Information System (INIS)

    Elevant, T.; Olsson, M.

    1991-02-01

    Experiment with burning fusion plasmas in tokamaks will place particular requirements on neutron measurements from radiation resistance-, physics-, burn control- and reliability considerations. The possibility to meet these needs by measurements of neutron fluxes and energy spectra by means of time-of-flight techniques are described. Reference counters and spectrometers are proposed and characterized with respect to efficiency, count-rate capabilities, energy resolution and tolerable neutron and γ-radiation background levels. The instruments can be used in a neutron camera and are capable to operate in collimated neutron fluxes up to levels corresponding to full nuclear output power in the next generation of experiments. Energy resolutions of the spectrometers enables determination of ion temperatures from 3 (keV) through analysis of the Doppler broadening. Primarily, the instruments are aimed for studies of 14 (MeV) neutrons produced in (d,t)-plasmas but can, after minor modifications, be used for analysis of 2.45 (MeV) neutrons produced in (d,d)-plasma. (au) (33 refs.)

  6. HYSPEC : A CRYSTAL TIME OF FLIGHT HYBRID SPECTROMETER FOR THE SPALLATION NEUTRON SOURCE

    International Nuclear Information System (INIS)

    SHAPIRO, S.M.; ZALIZNYAK, I.A.

    2002-01-01

    This document lays out a proposal by the Instrument Development Team (IDT) composed of scientists from leading Universities and National Laboratories to design and build a conceptually new high-flux inelastic neutron spectrometer at the pulsed Spallation Neutron Source (SNS) at Oak Ridge. This instrument is intended to supply users of the SNS and scientific community, of which the IDT is an integral part, with a platform for ground-breaking investigations of the low-energy atomic-scale dynamical properties of crystalline solids. It is also planned that the proposed instrument will be equipped with a polarization analysis capability, therefore becoming the first polarized beam inelastic spectrometer in the SNS instrument suite, and the first successful polarized beam inelastic instrument at a pulsed spallation source worldwide. The proposed instrument is designed primarily for inelastic and elastic neutron spectroscopy of single crystals. In fact, the most informative neutron scattering studies of the dynamical properties of solids nearly always require single crystal samples, and they are almost invariably flux-limited. In addition, in measurements with polarization analysis the available flux is reduced through selection of the particular neutron polarization, which puts even more stringent limits on the feasibility of a particular experiment. To date, these investigations have mostly been carried out on crystal spectrometers at high-flux reactors, which usually employ focusing Bragg optics to concentrate the neutron beam on a typically small sample. Construction at Oak Ridge of the high-luminosity spallation neutron source, which will provide intense pulsed neutron beams with time-averaged fluxes equal to those at medium-flux reactors, opens entirely new opportunities for single crystal neutron spectroscopy. Drawing upon experience acquired during decades of studies with both crystal and time-of-flight (TOF) spectrometers, the IDT has developed a conceptual

  7. HYSPEC : A CRYSTAL TIME OF FLIGHT HYBRID SPECTROMETER FOR THE SPALLATION NEUTRON SOURCE.

    Energy Technology Data Exchange (ETDEWEB)

    SHAPIRO,S.M.; ZALIZNYAK,I.A.

    2002-12-30

    This document lays out a proposal by the Instrument Development Team (IDT) composed of scientists from leading Universities and National Laboratories to design and build a conceptually new high-flux inelastic neutron spectrometer at the pulsed Spallation Neutron Source (SNS) at Oak Ridge. This instrument is intended to supply users of the SNS and scientific community, of which the IDT is an integral part, with a platform for ground-breaking investigations of the low-energy atomic-scale dynamical properties of crystalline solids. It is also planned that the proposed instrument will be equipped with a polarization analysis capability, therefore becoming the first polarized beam inelastic spectrometer in the SNS instrument suite, and the first successful polarized beam inelastic instrument at a pulsed spallation source worldwide. The proposed instrument is designed primarily for inelastic and elastic neutron spectroscopy of single crystals. In fact, the most informative neutron scattering studies of the dynamical properties of solids nearly always require single crystal samples, and they are almost invariably flux-limited. In addition, in measurements with polarization analysis the available flux is reduced through selection of the particular neutron polarization, which puts even more stringent limits on the feasibility of a particular experiment. To date, these investigations have mostly been carried out on crystal spectrometers at high-flux reactors, which usually employ focusing Bragg optics to concentrate the neutron beam on a typically small sample. Construction at Oak Ridge of the high-luminosity spallation neutron source, which will provide intense pulsed neutron beams with time-averaged fluxes equal to those at medium-flux reactors, opens entirely new opportunities for single crystal neutron spectroscopy. Drawing upon experience acquired during decades of studies with both crystal and time-of-flight (TOF) spectrometers, the IDT has developed a conceptual

  8. Development of the STEFF detector for the neutron Time Of Flight facility (n_TOF), CERN

    CERN Document Server

    AUTHOR|(CDS)2092031

    Signicant work has been performed on the development of STEFF (SpecTrometer for Exotic Fission Fragments), a 2E2V (2-Energy 2-Velocity) spectrometer built by the University of Manchester Fission Group. The majority of this work was in the development of the time-of-flight systems, in particular the stop detector; with the main goals of improving the timing resolution and the detection eciency of the ssion fragments. Further development of the STEFF spectrometer was done to enable 2E2V measurements of the $^{235}$U(n,f) reaction with coincident measurements using a white neutron spectra of energies ranging from 10 meV to 200 MeV provided by the n_TOF (neutron Time Of Flight) facility, CERN. The STEFF spectrometer was successfully operated twice on the Experimental Area-2 high flux pulsed neutron beam line resulting in 2E2V measurements for ssion events with neutron energies ranging from 20 meV to 10 MeV. The first experiment received 1.36 X 10$^{18}$ POT (Protons On Target) with stable conditions and the seco...

  9. Fluence measurement at the neutron time of flight experiment at CERN

    CERN Document Server

    Weiss, Christina; Jericha, Erwin

    At the neutron time of flight facility n_TOF at CERN a new spallation target was installed in 2008. In 2008 and 2009 the commissioning of the new target took place. During the summer 2009 a fission chamber of the Physikalisch Technische Bundesanstalt (PTB) Braunschweig was used for the neutron fluence measurement. The evaluation of the data recorded with this detector is the primary topic of this thesis. Additionally a neutron transmission experiment with air has been performed at the TRIGA Mark II reactor of the Atomic Institute of the Austrian Universities (ATI). The experiment was implemented to clarify a question about the scattering cross section of molecular gas which could not be answered clearly via the literature. This problem came up during the evaluations for n_TOF.

  10. Time-of-flight neutron Bragg-edge transmission imaging of microstructures in bent steel plates

    Energy Technology Data Exchange (ETDEWEB)

    Su, Yuhua, E-mail: yuhua.su@j-parc.jp [J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195 (Japan); Oikawa, Kenichi; Harjo, Stefanus; Shinohara, Takenao; Kai, Tetsuya; Harada, Masahide; Hiroi, Kosuke [J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195 (Japan); Zhang, Shuoyuan; Parker, Joseph Don [Neutron R& D Division, CROSS-Tokai, 162-1 Shirakata, Tokai, Ibaraki 319-1106 (Japan); Sato, Hirotaka [Faculty of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Shiota, Yoshinori; Kiyanagi, Yoshiaki [Graduate School of Engineering, Nagoya University, Nagoya, Aichi 464-8603 (Japan); Tomota, Yo [Research Center for Strategic Materials, National Institute for Materials Science, Tsukuba 305-0047 (Japan)

    2016-10-15

    Neutron Bragg-edge transmission imaging makes it possible to quantitatively visualize the two-dimensional distribution of microstructure within a sample. In order to examine its application to engineering products, time-of-flight Bragg-edge transmission imaging experiments using a pulsed neutron source were performed for plastically bent plates composed of a ferritic steel and a duplex stainless steel. The non-homogeneous microstructure distributions, such as texture, crystalline size, phase volume fraction and residual elastic strain, were evaluated for the cross sections of the bent plates. The obtained results were compared with those by neutron diffraction and electron back scatter diffraction, showing that the Bragg-edge transmission imaging is powerful for engineering use.

  11. Time-of-flight small-angle scattering spectrometers on pulsed neutron sources

    International Nuclear Information System (INIS)

    Ostanevich, Yu.M.

    1987-01-01

    The operation principles, constructions, advantages and shortcomings of known time-of-flight small angle neutron scattering (TOF SANS) spectrometers built up with pulsed neutron sources are reviewed. The most important characteristics of TOF SANS apparatuses are rather a high luminosity and the possibility for the measurement in an extremely wide range of scattering vector at a single exposure. This is achieved by simultaneous employment of white beam, TOF technique for wave length-scan and the commonly known angle-scan. However, the electronic equipment, data-matching programs, and the measurement procedure, necessary for accurate normalization of experimental data and their transformation into absolute cross-section scale, they all become more complex, as compared with those for SANS apparatuses operating on steady-state neutron sources, where only angle-scan is used

  12. CVD Diamond Detectors for Current Mode Neutron Time-of-Flight Spectroscopy at OMEGA/NIF

    International Nuclear Information System (INIS)

    G. J. Schmid; V. Yu. Glebov; A. V. Friensehner; D. R. Hargrove; S. P. Hatchett; N. Izumi; R. A. Lerche; T. W. Phillips; T. C. Sangster; C. Silbernagel; C. Stoecki

    2001-01-01

    We have performed pulsed neutron and pulsed laser tests of a CVD diamond detector manufactured from DIAFILM, a commercial grade of CVD diamond. The laser tests were performed at the short pulse UV laser at Bechtel Nevada in Livermore, CA. The pulsed neutrons were provided by DT capsule implosions at the OMEGA laser fusion facility in Rochester, NY. From these tests, we have determined the impulse response to be 250 ps fwhm for an applied E-field of 500 V/mm. Additionally, we have determined the sensitivity to be 2.4 mA/W at 500 V/mm and 4.0 mA/W at 1000 V/mm. These values are approximately 2 to 5x times higher than those reported for natural Type IIa diamond at similar E-field and thickness (1mm). These characteristics allow us to conceive of a neutron time-of-flight current mode spectrometer based on CVD diamond. Such an instrument would sit inside the laser fusion target chamber close to target chamber center (TCC), and would record neutron spectra fast enough such that backscattered neutrons and x-rays from the target chamber wall would not be a concern. The acquired neutron spectra could then be used to extract DD fuel areal density from the downscattered secondary to secondary ratio

  13. Study on thermal neutron spectra in reactor moderators by time-of-flight method

    International Nuclear Information System (INIS)

    Akino, Fujiyoshi

    1982-12-01

    Prediction of thermal neutron spectra in a reactor core plays very important role in the neutronic design of the reactor for obtaining the accurate thermal group constants. It is well known that the neutron scattering properties of the moderator materials markedly influence the thermal neutron spectra. Therefore, 0 0 angular dependent thermal neutron spectra were measured by the time-of-flight method in the following moderator bulks 1) Graphite bulk poisoned with boron at the temperatures from 20 to 800 0 C, 2) Light water bulk poisoned with Cadmium and/or Indium, 3) Light water-natural uranium heterogeneous bulk. The measured results were compared with calculation utilizing Young-Koppel and Haywood scattering model for graphite and light water respectively. On the other hand, a variety of 20% enriched uranium loaded and graphite moderated cores consisting of the different lattice cell in a wide range of the carbon to uranium atomic ratio have been built at Semi-Homogeneous Critical Experimental Assembly (SHE) to perform the critical experiments related to Very High Temperature Reactor (VHTR). The experimental data were for the critical masses in 235 U, reactivity worths of experimental burnable poison rods, thorium rods, natural-uranium rods and experimental control rods and kinetic parameters. It is made clear from comparison between measurement and calculation that the accurate thermal group constants can be obtained by use of the Young-Koppel and Haywood neutron scattering models if heterogeneity of reactor core lattices is taken into account precisely. (author)

  14. Detection of renal cell carcinoma using neutron time of flight spectroscopy

    International Nuclear Information System (INIS)

    Viana, Rodrigo S.; Yoriyaz, Helio; Lakshmanan, Manu N.; Agasthya, Greeshma A.; Kapadia, Anuj J.

    2013-01-01

    The diagnosis of renal cell carcinoma (RCC) is challenging because the symptoms accompanying it are not unique to the disease, and can therefore be misdiagnosed as other diseases. Due to this characteristic, detection of renal cancer is incidental most of time, occurring via abdominal radiographic examinations unrelated to the disease. Presently, biopsy, which is invasive and an unpleasant procedure for the patient, is the most commonly used technique to diagnose RCC. In this study, we demonstrate the application of a novel noninvasive technique for detecting and imaging RCC in vivo. The elemental composition of biological tissues including kidneys has been investigated using a new technique called Neutron Stimulated Emission Computed Tomography (NSECT). This technique is based on detecting the energy signature emitted by the stable isotopes of elements in the body, which are stimulated to emit gamma radiation via inelastic neutron scattering. Methods for improving detection sensitivity and reducing dose, such as time-of-flight neutron spectroscopy have been explored. MCNP5 simulations were used to model the NSECT scanning of the human kidney where the energy and time of arrival of gamma photons were recorded in an ideal detector placed around the human torso. A 5 MeV collimated neutron beam was used to irradiate the kidney containing an RCC lesion. The resulting spectra were resolved in 100 picosecond and 1 keV time and energy bins, respectively. The preliminary results demonstrate the ability to localize the lesion through neutron time of flight spectroscopy and generate a tomographic image at a low dose to the patient. (author)

  15. Neutron Time-of-Flight Quantification of Water Desorption Isotherms of Montmorillonite

    DEFF Research Database (Denmark)

    Gates, Will P.; Bordallo, Heloisa N.; Aldridge, Laurence P.

    2012-01-01

    enabled us to differentiate at least two water motions during dehydration of Ca- and Na-SAz-1 (initially equilibrated at RH = 55%) by using a "controlled water loss" time-of-flight procedure. This work confirms that (a) interlayer and cationic water in dioctahedral smectites are characterized by slower...... motions than interparticle water, (b) interlayer cations influenced the dynamics of water loss, probably through its affect on clay fabric, and (c) interparticle water behaves more like bulk water. At 55% RH the Ca montmorillonite held more interparticle water, but on dehydration under controlled......The multiple energy states of water held by surfaces of a clay mineral can be effectively probed with time-of-flight and fixed elastic window neutron scattering. We used these techniques to quantitatively differentiate water types, including rotational and translational diffusions, in Ca- and Na...

  16. A PCI time digitizer for the new JET time-of-flight neutron spectrometer

    International Nuclear Information System (INIS)

    Sousa, J.; Batista, A.J.N.; Combo, A.; Pereira, R.; Cruz, N.; Carvalho, P.; Varandas, C.A.F.; Conroy, S.; Ericsson, G.; Kaellne, J.

    2004-01-01

    A PCI time digitizer module with eight independent time-to-digital converter (TDC) channels is being developed for the new time-of-flight spectrometer designed for optimized rate (TOFOR) which diagnoses deuterium plasmas of the EFDA-JET tokamak. The module shall measure with high accuracy the flight-times of 2.5 MeV neutrons in the 100 ns range as given by two groups of scintillation detectors operating at average event rates from the expected 500 kHz up to 5 MHz. The module stores up to 64 million hit-times with a resolution of 0.4 ns and incorporates a digital signal processor and a system-on-chip device which performs the data transfer, the device control/monitoring and may perform statistical, data reduction or control algorithms in real-time

  17. The IRK time-of-flight facility for measurements of double-differential neutron emission cross sections

    International Nuclear Information System (INIS)

    Pavlik, A.; Priller, A.; Steier, P.; Vonach, H.; Winkler, G.

    1994-01-01

    In order to improve the present experimental data base of energy- and angle-differential neutron emission cross sections at 14 MeV incident-neutron energy, a new time-of-flight (TOF) facility was installed at the Institut fuer Radiumforschung und Kernphysik (IRK), Vienna. The set-up was particularly designed to more precisely measure the high-energy part of the secondary neutron spectra and consists of three main components: (1) a pulsed neutron generator of Cockcroft-Walton type producing primary neutrons via the T(d,n)-reaction, (2) a tube system which can be evacuated containing the neutron flight path, the sample, collimators and the sample positioning system, and (3) the neutron detectors with the data acquisition equipment. Removing the air along the neutron flight path results in a drastic suppression of background due to air-scattered neutrons in the spectrum of the secondary neutrons. For every secondary neutron detected in the main detector, the time-of-flight, the pulse-shape information and the recoil energy are recorded in list-mode via a CAMAC system connected to a PDP 11/34 on-line computer. Using a Micro VAX, the multiparameter data are sorted and reduced to double-differential cross sections

  18. MCRTOF, Multiple Scattering of Resonance Region Neutron in Time of Flight Experiments

    International Nuclear Information System (INIS)

    Ohkubo, Mako

    1984-01-01

    1 - Description of program or function: Multiple scattering of neutrons in the resonance energy region impinging on a disk with an arbitrary angle. 2 - Method of solution: The Monte Carlo method is employed to simulate the path of an incident neutron in a medium for which macroscopic cross sections are determined by resonance parameters. By tracing a large number of neutrons, probabilities for capture, transmission, front-face scattering, rear-face scattering and side-face scattering are determined and printed out as function of incident neutron energy. Optionally, the distribution of capture locations in the disk can be printed. The incident neutron energy is swept to fit a situation as encountered in time-of-flight experiments. 3 - Restrictions on the complexity of the problem: The cross section file is constructed from input resonance parameters with a single- level Breit-Wigner formula. The following restrictions and simplifications apply: - The maximum number of resonances is five. - Reactions other than capture and scattering are neglected. - The angular scattering distribution in the center-of-mass system is assumed to be uniform. - Chemical binding effects are neglected

  19. A neutron spectrometer based on the combination of time-of-flight and Larmor modulation

    International Nuclear Information System (INIS)

    Mulder, F.M.; Kreuger, R.; Grigoriev, S.V.; Kraan, W.H.; Rekveldt, M.Th.; Van Well, A.A.

    1999-01-01

    A study on the feasibility of neutron beam instrumentation that applies Larmor modulation for incoming, and time-of-flight for scattered wavelength determination (or vice versa) is currently under way at IRI. The instrument resulting from this combination can in principle measure quasi elastic and inelastic scattering with a flexible resolution and dynamic range. An important difference with current spectrometers is that there is no selection of neutron wavelengths for either the incoming beam (direct geometry) or scattered beam (inverted geometry). Therefore much of the available flux is used and there is no a priory selection of the energy transfer range and resolution. This instrument will be mainly applicable for quasi-elastic scattering and complex line shapes that are extended over a broad range in energy transfer. Line shapes can be measured directly in Fourier space, which is often advantageous. Due to signal to noise considerations, this instrument will be less suitable for the determination of weak, discrete energy transfer signals. A requirement for the Larmor modulator is that it can work with a white neutron beam. This can be realised for neutrons having a wavelength above ∼ 0.1 nm by use of 'adiabatic resonance π flippers'. This type of instrument may be applied at the future ESS pulsed neutron source in order to complement current spectrometers. (author)

  20. Neutron time-of-flight techniques for investigation of the extinction effect

    International Nuclear Information System (INIS)

    Niimura, N.; Tomiyoshi, S.; Takahashi, J.; Harada, J.

    1975-01-01

    An application of the time-of-flight neutron diffraction technique to an investigation of the nature of the extinction effect in a single-crystal specimen is given. It is shown that the wavelength dependence of the extinction can be easily obtained by changing the scattering angle. An estimation of the extinction factor for a CuCl single crystal is given as an example and a comparison of the results with recent extinction theory [Becker and Coppens. Acta Cryst.(1974). A30, 129-147; 148-153] is made. (Auth.)

  1. Software of structure experiMents in a neutron time-of-flight diffractometer

    International Nuclear Information System (INIS)

    Balagurov, A.M.; Dlouga, M.; Zlokazov, V.B.; Mironova, G.M.

    1978-01-01

    A set of programs is discussed to be used in diffraction experiment in a neutron time-of-flight diffractometer. The DIFRAT program, which processes spectra of poly and monocrystals, locates all spectrum maxima and assesses their width on the basis of given experimental data and elementary cell parameters. Accurate location of maxima, evaluation of their area and width is done by the IREAK program. The most important feature of this program is a capability to set an experimental model of maxima patterns. The EXPDAT program is developed to investigate structural characteristics of a sample. It calculates corrections for absorbtion and extinction

  2. Rotation stability of high speed neutron time-of-flight mechanical chopper

    International Nuclear Information System (INIS)

    Habib, N.; Adib, M.

    1998-01-01

    A modified rotation stabilization system has been designed to maintain the stability of a neutron time-of-flight (TOF) mechanical chopper rates from 460 rpm to 16000 rpm. The main principle of the system is based on comparing the chopper's rotation period with the preselected one from a quartz timer. The result of comparison is used to control the current driver of the chopper's motor. A 600 Hz three phase generator controlled by a magnetic amplifier was used as a current driver. The stability of the chopper's rotation rate at 16000 rpm was 0.02%. An improved method precise time scale calibration of the TOF spectrometer is applied

  3. A time-of-flight spectrometer for neutron diffraction under high pressure or at high temperature

    International Nuclear Information System (INIS)

    Roult, G.; Buevoz, J.L.

    1975-01-01

    For high pressure neutron diffraction studies (40 kilobars) the sample is placed in a very thick cell. In order to allow the neutron beam to go through the cell loosing as little intensity as possible, the inner part is kept solid while the external part has some windows facing the incident and reflected beam. The window dimensions are small (a few millimeters wide and a few centimeters long). There are two alternatives: to have the window either in a perpendicular plane or in a plane parallel to the axis. In the first case a fixed wavelength spectrometer can be used but the sample is small and the contribution of the cell to the diffraction pattern is relatively great. In the second case samples can be something like ten times greater and the cell contribution can be eliminated but a fixed wavelength spectrometer cannot be used. Thus the time-of-flight method is very convenient. The second alternative was chosen

  4. Measurement of residual strain in composites by means of time-of- flight neutron diffraction

    International Nuclear Information System (INIS)

    Kupperman, D.S.; Majumdar, S.; Richardson, J.; Saigal, A.

    1993-01-01

    Neutron diffraction time-of-flight measurements using the Intense Pulsed Neutron Source at Argonne National Laboratory have been employed to study strain in various metal- and ceramic-matrix composites. For example, measurements carried out to 900 C on a composite composed of a titanium alloy matrix and silicon carbide fibers have been used to validate theoretical assumptions in the prediction of fabrication-induced residual stress. Sapphire reinforced nickel aluminide composites have also been studied. Studies of a high-temperature ceramic superconducting composite consisting of yttrium barium copper oxide and silver with various volume fractions of silver have also been carried out. The results of these studies have provided information on the effect of Ag content on interface bonding. In addition, ceramic-matrix composites with randomly dispersed ceramic whiskers with varying fiber content have been investigated

  5. Deuterium-tritium neutron yield measurements with the 4.5 m neutron-time-of-flight detectors at NIF.

    Science.gov (United States)

    Moran, M J; Bond, E J; Clancy, T J; Eckart, M J; Khater, H Y; Glebov, V Yu

    2012-10-01

    The first several campaigns of laser fusion experiments at the National Ignition Facility (NIF) included a family of high-sensitivity scintillator∕photodetector neutron-time-of-flight (nTOF) detectors for measuring deuterium-deuterium (DD) and DT neutron yields. The detectors provided consistent neutron yield (Y(n)) measurements from below 10(9) (DD) to nearly 10(15) (DT). The detectors initially demonstrated detector-to-detector Y(n) precisions better than 5%, but lacked in situ absolute calibrations. Recent experiments at NIF now have provided in situ DT yield calibration data that establish the absolute sensitivity of the 4.5 m differential tissue harmonic imaging (DTHI) detector with an accuracy of ± 10% and precision of ± 1%. The 4.5 m nTOF calibration measurements also have helped to establish improved detector impulse response functions and data analysis methods, which have contributed to improving the accuracy of the Y(n) measurements. These advances have also helped to extend the usefulness of nTOF measurements of ion temperature and downscattered neutron ratio (neutron yield 10-12 MeV divided by yield 13-15 MeV) with other nTOF detectors.

  6. AMOR - the time-of-flight neutron reflectometer at SINQ/PSI

    Science.gov (United States)

    Gupta, Mukul; Gutberlet, T.; Stahn, J.; Keller, P.; Clemens, D.

    2004-07-01

    The apparatus for multioptional reflectometry (AMOR) at SINQ/PSI is a versatile reflectometer operational in the time-of-flight (TOF) mode (in a wavelength range of 0.15 nm <λ < 1.3 nm) as well as in the monochromatic (theta-2theta) mode with both polarized and unpolarized neutrons. AMOR is designed to perform reflectometry measurements in horizontal sample-plane geometry which allows studying both solid-liquid and liquid-liquid interfaces. A pulsed cold neutron beam from the end position of the neutron guide is produced by a dual-chopper system (side-by-side) having two windows at 180^{circ} and rotatable with a maximum frequency of 200 Hz. In the TOF mode, the chopper frequency, width of the gating window and the chopper-detector distance can be selected independently providing a wide range of q-resolution (Delta q/q=1-10&%slash;). Remanent FeCoV/Ti : N supermirrors are used as polarizer/analyzer with a polarization efficiency of sim97&%slash;. For the monochromatic wavelength mode, a Ni/Ti multilayer is used as a monochromator, giving sim50&%slash; reflectivity at a wavelength of 0.47 nm. In the present work, a detailed description of the instrument and setting-up of the polarization option is described. Results from some of the recent studies with polarized neutrons and measurements on liquid surfaces are presented.

  7. A fast large-area position-sensitive time-of-flight neutron detection system

    International Nuclear Information System (INIS)

    Crawford, R.K.; Haumann, J.R.

    1989-01-01

    A new position-sensitive time-of-flight neutron detection and histograming system has been developed for use at the Intense Pulsed Neutron Source. Spatial resolution of roughly 1 cm x 1 cm and time-of-flight resolution of ∼1 μsec are combined in a detection system which can ultimately be expanded to cover several square meters of active detector area. This system is based on the use of arrays of cylindrical one-dimensional position-sensitive proportional counters, and is capable of collecting the x-y-t data and sorting them into histograms at time-averaged data rates up to ∼300,000 events/sec over the full detector area and with instantaneous data rates up to more than fifty times that. Numerous hardware features have been incorporated to facilitate initial tuning of the position encoding, absolute calibration of the encoded positions, and automatic testing for drifts. 7 refs., 11 figs., 1 tabs

  8. A search for fine structure of the time-of-flight spectrum of the fission neutrons of 252Cf

    International Nuclear Information System (INIS)

    Scobie, J.; Scott, R.D.; Feather, N.; Vass, D.G.

    1977-01-01

    A standard time-of-flight arrangement, in which start pulses were supplied by fission fragments and stop pulses by neutrons, has been employed in an attempt to check recent claims of the existence of fine structures in the time-of-flight spectrum of the fission neutrons of 252 Cf. This structure, in the form of spikes with tails towards longer times, has been attributed to the emission of neutrons of short delay (with half-lives of a few to a hundred or so nanoseconds) in the fission process. It has not been possible to find any convincing evidence for the existence of such structure. (author)

  9. A digital data acquisition system for a time of flight neutron diffuse scattering instrument

    International Nuclear Information System (INIS)

    Venegas, Rafael; Bacza, Lorena; Navarro, Gustavo

    1998-01-01

    Full text. We describe the design of a digital data acquisition system built for acquiring and storing the information produced by a neutron diffuse scattering apparatus. This instrument is based on the analysis of pulsed subthermal neutron which are scattered by a solid or liquid sample, measured as function of the scattered neutron wavelength and momentum direction. The time of flight neutron intensities on 14 different angular detector positions and two fission chambers must be analyzed simultaneously for each neutron burst. A PC controlled data acquisition board system was built based on two parallel multiscannning units, each with its own add-one counting unit, and a common base time generator. The unit plugs onto the ISA bus through an interface card. Two separate counting units were designed, to avoid possible access competition between low counting rate counters at off-axis positions and the higher rate frontal 0 deg and beam monitoring counters. the first unit contains logic for 14 independent and simultaneous multi scaling inputs, with 128 time channels and dwell time per channel of 5, 10 or 20 microseconds. Sweep trigger is synchronized with an electric signal from a coil sensing the rotor. The second unit contains logic for four additional multi scalers using the same external synchronizing signal, similar in all others details to the previously described multi scalers. Basic control routines for the acquisitions were written in C and a program for spectrum display and user interface was written in C ++ for a Windows 3.1 OS. A block diagram of the system is presented

  10. The measurement programme at the neutron time-of-flight facility n_TOF at CERN

    Directory of Open Access Journals (Sweden)

    Gunsing F.

    2017-01-01

    Full Text Available Neutron-induced reaction cross sections are important for a wide variety of research fields ranging from the study of nuclear level densities, nucleosynthesis to applications of nuclear technology like design, and criticality and safety assessment of existing and future nuclear reactors, radiation dosimetry, medical applications, nuclear waste transmutation, accelerator-driven systems and fuel cycle investigations. Simulations and calculations of nuclear technology applications largely rely on evaluated nuclear data libraries. The evaluations in these libraries are based both on experimental data and theoretical models. CERN’s neutron time-of-flight facility n_TOF has produced a considerable amount of experimental data since it has become fully operational with the start of its scientific measurement programme in 2001. While for a long period a single measurement station (EAR1 located at 185 m from the neutron production target was available, the construction of a second beam line at 20 m (EAR2 in 2014 has substantially increased the measurement capabilities of the facility. An outline of the experimental nuclear data activities at n_TOF will be presented.

  11. Spherical neutron polarimetry applied to spin-echo and time-of-flight spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lelievre-Berna, E., E-mail: lelievre@ill.e [Institut Laue Langevin (ILL), 6 rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Bentley, P.; Bourgeat-Lami, E.; Thomas, M. [Institut Laue Langevin (ILL), 6 rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Pappas, C. [Helmholtz Centre Berlin for Materials and Energy (HCB), Glienickerstr. 100, 14109 Berlin (Germany); Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Kischnik, R.; Moskvin, E. [Helmholtz Centre Berlin for Materials and Energy (HCB), Glienickerstr. 100, 14109 Berlin (Germany)

    2009-09-01

    The changes in direction of the neutron spin that take place on scattering by a magnetic interaction vector are highly dependent on their relative directions. In some circumstances, without zero-field polarimeter, it is impossible to distinguish between a simple depolarisation and a rotation of the polarisation vector. Motivated by the investigation of chiral magnetic fluctuations, we have implemented the third-generation zero-field polarimeter Cryopad on the neutron spin-echo spectrometer SPAN at the Helmholtz Centre Berlin (HCB). We present the method and the limitations of this novel technique that is now available on IN15 at the ILL. The huge progress accomplished with {sup 3}He neutron spin filters/flippers are going to facilitate the exploitation of polarised beams at spallation sources. Zero-field polarimeters like Cryopad are used routinely at several steady-state sources but their design would be inefficient at a pulse source. We have investigated the possibility to implement a zero-field polarimeter on a time-of-flight spectrometer. We propose a design that would lead to a better efficiency and present the finite element calculations.

  12. Reconstruction of Time-Resolved Neutron Energy Spectra in Z-Pinch Experiments Using Time-of-flight Method

    International Nuclear Information System (INIS)

    Rezac, K.; Klir, D.; Kubes, P.; Kravarik, J.

    2009-01-01

    We present the reconstruction of neutron energy spectra from time-of-flight signals. This technique is useful in experiments with the time of neutron production in the range of about tens or hundreds of nanoseconds. The neutron signals were obtained by a common hard X-ray and neutron fast plastic scintillation detectors. The reconstruction is based on the Monte Carlo method which has been improved by simultaneous usage of neutron detectors placed on two opposite sides from the neutron source. Although the reconstruction from detectors placed on two opposite sides is more difficult and a little bit inaccurate (it followed from several presumptions during the inclusion of both sides of detection), there are some advantages. The most important advantage is smaller influence of scattered neutrons on the reconstruction. Finally, we describe the estimation of the error of this reconstruction.

  13. Development of an ion time-of-flight spectrometer for neutron depth profiling

    Science.gov (United States)

    Cetiner, Mustafa Sacit

    Ion time-of-flight spectrometry techniques are investigated for applicability to neutron depth profiling. Time-of-flight techniques are used extensively in a wide range of scientific and technological applications including energy and mass spectroscopy. Neutron depth profiling is a near-surface analysis technique that gives concentration distribution versus depth for certain technologically important light elements. The technique uses thermal or sub-thermal neutrons to initiate (n, p) or (n, alpha) reactions. Concentration versus depth distribution is obtained by the transformation of the energy spectrum into depth distribution by using stopping force tables of the projectiles in the substrate, and by converting the number of counts into concentration using a standard sample of known dose value. Conventionally, neutron depth profiling measurements are based on charged particle spectrometry, which employs semiconductor detectors such as a surface barrier detector (SBD) and the associated electronics. Measurements with semiconductor detectors are affected by a number of broadening mechanisms, which result from the interactions between the projectile ion and the detector material as well as fluctuations in the signal generation process. These are inherent features of the detection mechanism that involve the semiconductor detectors and cannot be avoided. Ion time-of-flight spectrometry offers highly precise measurement capabilities, particularly for slow particles. For high-energy low-mass particles, measurement resolution tends to degrade with all other parameters fixed. The threshold for more precise ion energy measurements with respect to conventional techniques, such as direct energy measurement by a surface barrier detector, is directly related to the design and operating parameters of the device. Time-of-flight spectrometry involves correlated detection of two signals by a coincidence unit. In ion time-of-flight spectroscopy, the ion generates the primary input

  14. Thermal diffuse scattering in time-of-flight neutron diffraction studied on SBN single crystals

    International Nuclear Information System (INIS)

    Prokert, F.; Savenko, B.N.; Balagurov, A.M.

    1994-01-01

    At time-of-flight (TOF) diffractometer D N-2, installed at the pulsed reactor IBR-2 in Dubna, Sr x Ba 1-x Nb 2 O 6 mixed single crystals (SBN-x) of different compositions (0.50 < x< 0.75) were investigated between 15 and 773 K. The diffraction patterns were found to be strongly influenced by the thermal diffuse scattering (TDS). The appearance of the TDS from the long wavelength acoustic models of vibration in single crystals is characterized by the ratio of the velocity of sound to the velocity of neutron. Due to the nature of the TOF Laue diffraction technique used on D N-2, the TDS around Bragg peaks has rather a complex profile. An understanding of the TDS close to Bragg peaks is essential in allowing the extraction of the diffuse scattering occurring at the diffuse ferroelectric phase transition in SBN crystals. 11 refs.; 9 figs.; 1 tab. (author)

  15. Precision Neutron Time-of-Flight Detectors Provide Insight into NIF Implosion Dynamics

    Science.gov (United States)

    Schlossberg, David; Eckart, M. J.; Grim, G. P.; Hartouni, E. P.; Hatarik, R.; Moore, A. S.; Waltz, C. S.

    2017-10-01

    During inertial confinement fusion, higher-order moments of neutron time-of-flight (nToF) spectra can provide essential information for optimizing implosions. The nToF diagnostic suite at the National Ignition Facility (NIF) was recently upgraded to include novel, quartz Cherenkov detectors. These detectors exploit the rapid Cherenkov radiation process, in contrast with conventional scintillator decay times, to provide high temporal-precision measurements that support higher-order moment analyses. Preliminary measurements have been made on the NIF during several implosions and initial results are presented here. Measured line-of-sight asymmetries, for example in ion temperatures, will be discussed. Finally, advanced detector optimization is shown to advance accessible physics, with possibilities for energy discrimination, gamma source identification, and further reduction in quartz response times. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

  16. Measurement and analysis of fast neutron spectra in reactor materials by time-of-flight method

    International Nuclear Information System (INIS)

    Hayashi, Shuhei; Kimura, Itsuro; Kobayashi, Shohei; Yamamoto, Shuji; Nishihara, Hiroshi.

    1982-01-01

    The LINAC-TOF experiments have been done to measure the neutron energy spectra in the assemblies of reactor materials. The sample materials to be measured were iron, stainless steel, aluminum, nickel, zirconium, thorium, lithium, and so on. The shapes of assemblies were piles (rectangular parallelopiped, sphere, and polyhedron) and slab. A photoneutron target was set at the center of the pile assemblies. Each assembly has an electron injection hole and a re-entrant hole. In case of a slab, a photo neutron target was placed at the outside of the slab. Neutrons were generated by using an electron linear accelerator (LINAC). The length of the flight path was 20 m. The neutron detectors were a Li-6 glass scintillator and a B-10 vaseline-NaI(Tl) scintillator. The spatial distributions of neutrons in the piles were measured by the foil activation method. The neutron transport calculation was performed, and the evaluation of group constants was made. (Kato, T.)

  17. The time-of-flight small-angle neutron diffractometer (SAD) at IPNS, Argonne National Laboratory

    International Nuclear Information System (INIS)

    Thiyagarajan, P.; Epperson, J.E.; Crawford, R.K.; Carpenter, J.M.; Klippert, T.E.; Wozniak, D.G.

    1997-01-01

    The design, development and performance of the time-of-flight (TOF) small-angle diffractometer (SAD) at the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory are described. Similar TOF-SANS instruments are in operation at the pulsed neutron sources at Los Alamos National Laboratory, USA, at Rutherford Appleton Laboratory, England, and at KEK, Japan. These instruments have an advantage by comparison with their steady-state counterparts in that a relatively wide range of momentum transfer (q) can be monitored in a single experiment without the need to alter the collimation or the sample-to-detector distance. This feature makes SANS experiments easy and very effective for studying systems such as those undergoing phase transitions under different conditions, samples that cannot be easily reproduced for repetitive experiments, and systems under high temperature, pressure or shear. Three standard samples are used to demonstrate that the quality of the SANS data from SAD is comparable with those from other established steady-state SANS facilities. Two examples are given to illustrate that the wide q region accessible in a single measurement at SAD is very effective for following the time-dependent phase transitions in paraffins and temperature- and pressure-dependent phase transitions in model biomembranes. (orig.)

  18. 8-channel system for neutron-nuclear investigations by time-of-flight method

    International Nuclear Information System (INIS)

    Shvetsov, V.N.; Enik, T.L.; Mitsyna, L.V.; Popov, A.B.; Salamatin, I.M.; Sedyshev, P.V.; Sirotin, A.P.; Astakhova, N.V.; Salamatin, K.M.

    2011-01-01

    In connection with commissioning of the IREN pulsed resonance neutron source, new electronics and appropriate software are developed for registration of time-of-flight spectra with small width of the channel (10 ns). The hardware-software system is intended for research of the IREN neutron beam characteristics, properties of new detectors, and also for performance of precision experiments under conditions of low intensity or registration of rare events. The time encoder is the key element of the system hardware. It is developed on the basis of the Cypress-technologies. The unit can measure time intervals for signals intensity up to 10 5 for each of eight inputs. Using a USB interface provides system mobility. The TOF System Software includes the control program, driver software layer, data sorting program and data processing utilities and other units, performed as executable applications. The interprocess communication between units is provided by network and/or by specially designed interface based on the mechanism of named files mapped into memory. This method provides fastest possible communication between processes. The developed methods of integrating the executable components into a system provide a distributed system, improve the reusing of the software and provide the ability to assemble the system by the user

  19. Ion-temperature measurement of indirectly driven implosions using a geometry-compensated neutron time-of-flight detector

    International Nuclear Information System (INIS)

    Murphy, T.J.; Lerche, R.A.; Bennett, C.; Howe, G.

    1995-01-01

    A geometry-compensated neutron time-of-flight detector has been constructed and used on Nova to measure ion temperatures from indirectly driven implosions with yields between 2.5 and 5x10 9 DD neutrons. The detector, which has an estimated respond time of 250 ps, was located 150 cm from the targets. Due to the long decay time of the scintillator, the time-of-flight signal must be unfolded from the measured detector signal. Several methods for determining the width of the neutron energy spectrum from the data have been developed and give similar results. Scattered x rays continue to be a problem for low yield shots, but should be brought under control with adequate shielding

  20. Ion temperature measurement of indirectly-driven implosions using a geometry-compensated neutron time-of-flight detector

    International Nuclear Information System (INIS)

    Murphy, T.J.; Lerche, R.A.; Bennett, C.; Howe, G.

    1994-05-01

    A geometry-compensated neutron time-of-flight detector has been constructed and used on Nova to measure ion temperatures from indirectly-driven implosions with yields between 2.5 and 5 x 10 9 DD neutrons. The detector, which has an estimated response time of 250 ps, was located 150 cm from the targets. Due to the long decay time of the scintillator, the time-of-flight signal must be unfolded from the measured detector signal. Several methods for determining the width of the neutron energy spectrum from the data have been developed and give similar results. Scattered x rays continue to be a problem for low yield shots, but should be brought under control with adequate shielding

  1. Modeling the neutron spin-flip process in a time-of-flight spin-resonance energy filter

    CERN Document Server

    Parizzi, A A; Klose, F

    2002-01-01

    A computer program for modeling the neutron spin-flip process in a novel time-of-flight (TOF) spin-resonance energy filter has been developed. The software allows studying the applicability of the device in various areas of spallation neutron scattering instrumentation, for example as a dynamic TOF monochromator. The program uses a quantum-mechanical approach to calculate the local spin-dependent spectra and is essential for optimizing the magnetic field profiles along the resonator axis. (orig.)

  2. Optimized design of the chopper disks and the neutron guide in a disk chopper neutron time-of-flight spectrometer

    International Nuclear Information System (INIS)

    Copley, J.R.D.

    1990-01-01

    We consider important aspects of the performance of a disk chopper neutron time-of-flight spectrometer. The intensity at the sample position, and the contributions of the choppers to the resolution of the instrument, are evaluated as a function of the widths of the slots in the chopper disks and the width of the neutron guide between the disks. We find that there is an optimum choice of the ratios of these widths and that this choice depends on a single parameter which, for elastic scattering, is a simple ratio of distances. When pairs of counter-rotating disks are employed, the widths of the slots can be modified by grossly changing the phase relationship between the members of a chopper pair. If the slot widths are changed, the width of the guide should also be altered in order to maintain the spectrometer in an optimized state. This change in the guide width may be effectively achieved using an arrangement of nested guides. Resolution and intensity calculations demonstrate the important gains which may be realized using this approach. (orig.)

  3. First records of thermal neutrons with the spectrometer for time of flight (TOF) in the RP-10 Nuclear Reactor

    International Nuclear Information System (INIS)

    Munive, M.; Baltuano, O; Soto, C; Ravello, Y

    2002-01-01

    To obtain the first spectrum of an emergent beam of neutrons of a nuclear reactor is the main parameter of the characterization in the use of this reactor; one of ways to get this spectrum is for the technique of time of flight, TOF, which registers the time that a neutron need to cover a certain distance, associating this time then to the kinetic energy of the neutron. The kinetic study of the beam of neutrons is carried out on neutron pulses that are generated by a revolving choke called Chopper; and the analysis in the time of the detected pulses is carried out for a system MCS. Using this technique it is achieved the record of the spectra in energy, or in wavelength , of the irradiation facilities No 2 and 4, and of the exit N o 5 of the thermal column of the Nuclear Reactor RP-10 of the Nuclear Center Oscar de la Guerra RACSO, Peru (au)

  4. Data recording programme for a time-of-flight neutron spectrometer

    International Nuclear Information System (INIS)

    Smit, J.G.

    1975-04-01

    A modular program was written for the acquisition of the measurement data of a rotating crystal neutron spectrometer in a PDP-11/20 computer (16 K core memory). The modules are subroutines called by the higher-order FORTRAN programs. This program, which is carried out under the version 08/02 disk operating system, collects the data of a maximum number of 7 detectors in the core memory via interrupts in the on line mode. The detectors are connected to a time-of-flight unit which assigns the time and the detector number to the signals (minimum width of time channel 0.5 μs). From the T.O.F. unit the signals are passed on to the computer via a CAMAC input register and the CA-11 a branch driver manufactured by DEC. All the measurement data can be graphically displayed on a Tektronix visual display unit (keyboard interrupt). Relevant data are stored on disk and passed on to the central computer (S 4004) for further processing at the end of the experiment. (orig./RF) [de

  5. Time-of-Flight Neutron Imaging on IMAT@ISIS: A New User Facility for Materials Science

    Directory of Open Access Journals (Sweden)

    Winfried Kockelmann

    2018-02-01

    Full Text Available The cold neutron imaging and diffraction instrument IMAT at the second target station of the pulsed neutron source ISIS is currently being commissioned and prepared for user operation. IMAT will enable white-beam neutron radiography and tomography. One of the benefits of operating on a pulsed source is to determine the neutron energy via a time of flight measurement, thus enabling energy-selective and energy-dispersive neutron imaging, for maximizing image contrasts between given materials and for mapping structure and microstructure properties. We survey the hardware and software components for data collection and image analysis on IMAT, and provide a step-by-step procedure for operating the instrument for energy-dispersive imaging using a two-phase metal test object as an example.

  6. Time-of-flight techniques applied to neutron spectra measurements in fast subcritical assemblies

    International Nuclear Information System (INIS)

    Rotival, Michel

    1975-04-01

    Time-of-flight measurements on Uranium-Graphite assemblies were performed using the BCMN linear accelerator. Methods to provide scalar spectra averaged over a core cell from these experimental results are described [fr

  7. The 2.5-MeV neutron time-of-flight spectrometer TOFOR for experiments at JET

    International Nuclear Information System (INIS)

    Gatu Johnson, M.; Giacomelli, L.; Hjalmarsson, A.

    2007-08-01

    A time-of-flight (TOF) spectrometer for measurement of the 2.5-MeV neutron emission from fusion plasmas has been developed and put into use at the JET tokamak. It has been optimized for operation at high rates (TOFOR) for the purpose of performing advanced neutron emission spectroscopy (NES) diagnosis of deuterium plasmas with a focus on the fuel ion motional states for different auxiliary heating scenarios. This requires operation over a large dynamic range including high rates of >100 kHz with a maximum value of 0.5 MHz for the TOFOR design. This paper describes the design principles and their technical realization. The performance is illustrated with recent neutron time-of-flight spectra recorded for plasmas subjected to different heating scenarios. A data acquisition rate of 39 kHz has been achieved at about a tenth of the expected neutron yield limit of JET, giving a projected maximum of 400 kHz at peak JET plasma yield. This means that the count rate capability for NES diagnosis of D plasmas has been improved more than an order of magnitude. Another important performance factor is the spectrometer bandwidth where data have been acquired and analyzed successfully with a response function for neutrons over the energy range 1 to >5 MeV. The implications of instrumental advancement represented by TOFOR are discussed

  8. The 2.5-MeV neutron time-of-flight spectrometer TOFOR for experiments at JET

    Energy Technology Data Exchange (ETDEWEB)

    Gatu Johnson, M.; Giacomelli, L.; Hjalmarsson, A. (and others)

    2007-08-15

    A time-of-flight (TOF) spectrometer for measurement of the 2.5-MeV neutron emission from fusion plasmas has been developed and put into use at the JET tokamak. It has been optimized for operation at high rates (TOFOR) for the purpose of performing advanced neutron emission spectroscopy (NES) diagnosis of deuterium plasmas with a focus on the fuel ion motional states for different auxiliary heating scenarios. This requires operation over a large dynamic range including high rates of >100 kHz with a maximum value of 0.5 MHz for the TOFOR design. This paper describes the design principles and their technical realization. The performance is illustrated with recent neutron time-of-flight spectra recorded for plasmas subjected to different heating scenarios. A data acquisition rate of 39 kHz has been achieved at about a tenth of the expected neutron yield limit of JET, giving a projected maximum of 400 kHz at peak JET plasma yield. This means that the count rate capability for NES diagnosis of D plasmas has been improved more than an order of magnitude. Another important performance factor is the spectrometer bandwidth where data have been acquired and analyzed successfully with a response function for neutrons over the energy range 1 to >5 MeV. The implications of instrumental advancement represented by TOFOR are discussed.

  9. Development and applications of the reverse neutron time-of-flight method with Fourier-type beam chopper

    International Nuclear Information System (INIS)

    Antson, O.

    1991-09-01

    The neutron powder diffraction method has been applied to the crystal structure analysis of high-temperature superconductors such as La 0 .8Sr 0 .2CuO 4 - y , YBa 2 Cu 3 O 7 - y and Bi 2 Sr 2 CaCu 2 O 8 + y optically active yttriumformate Y(HCOO) 3 , and β phase of deuterated acetonitrile, CD 3 CN. The structural information, containing symmetry, positional and thermal parameters, occupation factors and the order parameter, was obtained by measuring the coherent elastic scattering cross-section. The Rietveld profile refinement method was used for the extraction of structural parameters from experimental data. The diffraction spectra were obtained by measuring the time-of-flight distribution of neutrons with a Fourier-type beam chopper. The neutron diffraction spectrum is created by the on-line synthesis of the cross-correlation function between the beam modulation function and the detector intensity. Such an operational mode, called the reverse time-of-flight method, has many unique properties. The possibility of filtering out a low-frequency part of a diffraction spectrum, eg. incoherent background, by a properly selected band-pass filter has been studied. One of the practical applications of the reverse time-of-flight method, the Mini-Sfinks facility, is described with technical details, and its operational characteristics are compared with other high-resolution instruments

  10. A real-time neutron-gamma discriminator based on the support vector machine method for the time-of-flight neutron spectrometer

    Science.gov (United States)

    Wei, ZHANG; Tongyu, WU; Bowen, ZHENG; Shiping, LI; Yipo, ZHANG; Zejie, YIN

    2018-04-01

    A new neutron-gamma discriminator based on the support vector machine (SVM) method is proposed to improve the performance of the time-of-flight neutron spectrometer. The neutron detector is an EJ-299-33 plastic scintillator with pulse-shape discrimination (PSD) property. The SVM algorithm is implemented in field programmable gate array (FPGA) to carry out the real-time sifting of neutrons in neutron-gamma mixed radiation fields. This study compares the ability of the pulse gradient analysis method and the SVM method. The results show that this SVM discriminator can provide a better discrimination accuracy of 99.1%. The accuracy and performance of the SVM discriminator based on FPGA have been evaluated in the experiments. It can get a figure of merit of 1.30.

  11. Effects of gauge volume on pseudo-strain induced in strain measurement using time-of-flight neutron diffraction

    International Nuclear Information System (INIS)

    Suzuki, Hiroshi; Harjo, Stefanus; Abe, Jun; Xu, Pingguang; Aizawa, Kazuya; Akita, Koichi

    2013-01-01

    Spurious or pseudo-strains observed in time-of-flight (TOF) neutron diffraction due to neutron attenuation, surface-effects and a strain distribution within the gauge volume were investigated. Experiments were carried out on annealed and bent ferritic steel bars to test these effects. The most representative position in the gauge volume corresponds to the neutron-weighted center of gravity (ncog), which takes into account variations in intensity within the gauge volume due to neutron attenuation and/or absence of material in the gauge volume. The average strain in the gauge volume was observed to be weighted towards the ncog position but following an increase in the size of the gauge volume the weighted average strain was changed because of the change in the ncog position when a strain gradient appeared within the gauge volume. On the other hand, typical pseudo-strains, which are well known, did appear in through-surface strain measurements when the gauge volume was incompletely filled by the sample. Tensile pseudo-strains due to the surface-effect increased near the sample surface and exhibited a similar trend regardless of the size of the gauge volume, while the pseudo-strains increased faster for the smaller gauge volume. Furthermore, a pseudo-strain due to a change in the ncog position was observed even when the gauge volume was perfectly filled in the sample, and it increased with an increase in the size of the gauge volume. These pseudo-strains measured were much larger than those simulated by the conventional modeling, whereas they were simulated by taking into account an incident neutron beam divergence additionally in the model. Therefore, the incident divergence of the incident neutron beam must be carefully designed to avoid pseudo-strains in time-of-flight neutron diffractometry

  12. The Proton Beams for the New Time-of-Flight Neutron Facility at the CERN-PS

    CERN Document Server

    Cappi, R; Métral, G

    2000-01-01

    The experimental determination of neutron cross sections in fission and capture reactions as a function of the neutron energy is of primary importance in nuclear physics. Recent developments at CERN and elsewhere have shown that many fields of research and development, such as the design of Accelerator-Driven Systems (ADS) for nuclear waste incineration, nuclear astrophysics, fundamental nuclear physics, dosimetry for radiological protection and therapy, would benefit from a better knowledge of neutron cross sections. A neutron facility at the CERN-PS has been proposed with the aim of carrying out a systematic and high resolution study of neutron cross sections through Time-Of-Flight (n-TOF) measurement. The facility requires a high intensity proton beam (about 0.7x1013 particles/bunch) distributed in a short bunch (about 25 ns total length) to produce the neutrons by means of a spallation process in a lead target. To achieve these characteristics, a number of complex beam gymnastics have to be performed. All...

  13. Preliminary energy-filtering neutron imaging with time-of-flight method on PKUNIFTY: A compact accelerator based neutron imaging facility at Peking University

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hu; Zou, Yubin, E-mail: zouyubin@pku.edu.cn; Wen, Weiwei; Lu, Yuanrong; Guo, Zhiyu

    2016-07-01

    Peking University Neutron Imaging Facility (PKUNIFTY) works on an accelerator–based neutron source with a repetition period of 10 ms and pulse duration of 0.4 ms, which has a rather low Cd ratio. To improve the effective Cd ratio and thus improve the detection capability of the facility, energy-filtering neutron imaging was realized with the intensified CCD camera and time-of-flight (TOF) method. Time structure of the pulsed neutron source was firstly simulated with Geant4, and the simulation result was evaluated with experiment. Both simulation and experiment results indicated that fast neutrons and epithermal neutrons were concentrated in the first 0.8 ms of each pulse period; meanwhile in the period of 0.8–2.0 ms only thermal neutrons existed. Based on this result, neutron images with and without energy filtering were acquired respectively, and it showed that detection capability of PKUNIFTY was improved with setting the exposure interval as 0.8–2.0 ms, especially for materials with strong moderating capability.

  14. The 2.5-MeV neutron time-of-flight spectrometer TOFOR for experiments at JET

    International Nuclear Information System (INIS)

    Gatu Johnson, M.; Giacomelli, L.; Hjalmarsson, A.; Kaellne, J.; Weiszflog, M.; Andersson Sunden, E.; Conroy, S.; Ericsson, G.; Hellesen, C.; Ronchi, E.; Sjoestrand, H.; Gorini, G.; Tardocchi, M.; Combo, A.; Cruz, N.; Sousa, J.; Popovichev, S.

    2008-01-01

    A time-of-flight (TOF) spectrometer for measurement of the 2.5-MeV neutron emission from fusion plasmas has been developed and put into use at the JET tokamak. It has been optimized for operation at high rates (TOFOR) for the purpose of performing advanced neutron emission spectroscopy (NES) diagnosis of deuterium plasmas with a focus on the fuel ion motional states for different auxiliary heating scenarios. This requires operation over a large dynamic range, including high rates of >100 kHz with a maximum value of 0.5 MHz for the TOFOR design. This paper describes the design principles and their technical realization. The performance is illustrated with recent neutron TOF spectra recorded for plasmas subjected to different heating scenarios. A true event count rate of 39 kHz has been achieved at about a tenth of the expected neutron yield limit of JET, giving a projected maximum of 400 kHz at peak JET plasma yield. This means that the count rate capability for NES diagnosis of D plasmas has been improved more than an order of magnitude. Another important performance factor is the spectrometer bandwidth, where data have been acquired and analyzed successfully with a response function for neutrons over the energy range 1 to >5 MeV. The implications of instrumental advancement represented by TOFOR are discussed

  15. Time-of-flight small-angle neutron scattering data reduction and analysis at LANSCE with program SMR

    International Nuclear Information System (INIS)

    Hjelm, R.P. Jr.; Seeger, P.A.

    1988-01-01

    A user-friendly integrated system, SMR, for the display, reduction and analysis of data from time-of-flight small-angle neutron diffractometers is described. Its purpose is to provide facilities for data display and assessment, and to provide these facilities in near real time. This allows the results of each scattering measurement to be available almost immediately, and enables the user to use the results of a measurement as a basis for other measurements in the same time allocation of the instrument. 8 refs., 10 figs

  16. FOCUS: time-of-flight spectrometer for cold neutrons at SINQ

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, S; Mesot, J [Lab. for Neutron Scattering ETH Zurich, Zurich (Switzerland) and Paul Scherrer Institute, Villigen (Switzerland); Hempelmann, R [Saarbruecken Univ., Physical Chemistry, Saarbruecken (Germany)

    1996-11-01

    The physical layout of the Time-Of-Flight spectrometer at the new spallation source SINQ is presented. The concept shows up a hybrid-TOF combining a Fermi-chopper with a crystal monochromator. The demand of a versatile and flexible instrument for several applications is taken into account by the option of switching from time-focusing to monochromatic focusing mode such that the spectrometer can be optimised for both quasielastic and inelastic scattering applications. (author) 5 figs., 2 tabs., 16 refs.

  17. HYSPEC: A crystal time-of-flight hybrid spectrometer for the spallation neutron source with polarization capabilities

    International Nuclear Information System (INIS)

    Shapiro, S.M.; Zaliznyak, I.A.; Passell, L.; Ghosh, V.J.; Leonhardt, W.J.; Hagen, M.E.

    2006-01-01

    The hybrid spectrometer (HYSPEC) is a unique direct geometry inelastic scattering instrument under construction at the spallation neutron source (SNS). It combines the intensity enhancement features of focusing Bragg crystals with time-of-flight energy analysis. It will be located at beam-line 14B, which views a coupled liquid hydrogen moderator. A neutron beam from the moderator will travel along a curved guide, through a Fermi chopper and will then be focused onto a sample in an external building, 39 m from the source. In this configuration the intensity at the sample position is more than an order of magnitude larger than for other planned inelastic instrument. A movable detector bank 4.5 m from the sample will cover an angular range of 60 deg. in the horizontal plane and 15 deg. in the vertical direction. An important feature of HYSPEC is the ability to do neutron polarization analysis experiments. A Heusler crystal, which polarizes the neutron beam, can be used as the focusing crystal and a series of bender analyzers will analyze the polarization of the scattered beam

  18. Analysis methods of neutrons induced resonances in the transmission experiments by time-of-flight and automation of these methods on IBM 7094 II computer

    International Nuclear Information System (INIS)

    Corge, C.

    1967-01-01

    The neutron induced resonances analysis aims to determine the neutrons characteristics, leading to the excitation energies, de-excitation probabilities by gamma radiation emission, by neutron emission or by fission, their spin, their parity... This document describes the methods developed, or adapted, the calculation schemes and the algorithms implemented to realize such analysis on a computer, from data obtained during time-of-flight experiments on the linear accelerator of Saclay. (A.L.B.)

  19. Optimizing a neutron-beam focusing device for the direct geometry time-of-flight spectrometer TOFTOF at the FRM II reactor source

    DEFF Research Database (Denmark)

    Rasmussen, N. G.; Simeoni, G. G.; Lefmann, K.

    2016-01-01

    A dedicated beam-focusing device has been designed for the direct geometry thermal-cold neutron time-of-flight spectrometer TOFTOF at the neutron facility FRM II (Garching, Germany). The prototype, based on the compressed Archimedes' mirror concept, benefits from the adaptive-optics technology (a...... than 3.5 would have only marginal influence on the optimal behaviour, whereas comparable spectrometers could take advantage of longer focusing segments, with particular impact for the thermal region of the neutron spectrum....

  20. Time pulse profiles on a new data acquisition system for neutron time of flight diffractometer

    International Nuclear Information System (INIS)

    Venegas, R.; Baeza, L.; Navarro, G.

    1999-01-01

    A new differential acquisition system was built for a neutron diffuse scattering instrument. We analyze the time, space and velocity behavior of neutron pulse profiles, which can be obtained in a neutron diffuse scattering system of this nature, consisting of a black disc slit chopper and a circular detector bank, in order to design accurate scattering data analyzing methods. Computed direct pulse time spectra and measured spectra show satisfactory agreement. (author)

  1. Current-mode detector for neutron time-of-flight studies

    International Nuclear Information System (INIS)

    Bowman, J.D.; Szymanski, J.J.; Yuan, V.W.; Bowman, C.D.; Silverman, A.; Zhu, X.

    1990-01-01

    A system for the detection of high-intensity neutron bursts with instantaneous rates as high as 10 11 Hz is presented. This system uses a transient digitizer to sample the output voltage of a high-current photomultiplier tube as a function of time. The coutput voltage is proportional to the number of neutrons striking the detector. This detector is used at the Los Alamos Neutron Scattering Center to study fundamental symmetries. Design considerations, construction details and performance benchmarks are presented. (orig.)

  2. Implosion anisotropy of neutron kinetic energy distributions as measured with the neutron time-of-flight diagnostics at the National Ignition Facility

    Science.gov (United States)

    Hartouni, Edward; Eckart, Mark; Field, John; Grim, Gary; Hatarik, Robert; Moore, Alastair; Munro, David; Sayer, Daniel; Schlossberg, David

    2017-10-01

    Neutron kinetic energy distributions from fusion reactions are characterized predominantly by the excess energy, Q, of the fusion reaction and the variance of kinetic energy which is related to the thermal temperature of the plasma as shown by e.g. Brysk. High statistics, high quality neutron time-of-flight spectra obtained at the National Ignition Facility provide a means of measuring small changes to the neutron kinetic energy due to the spatial and temporal distribution of plasma temperature, density and velocity. The modifications to the neutron kinetic energy distribution as described by Munro include plasma velocity terms with spatial orientation, suggesting that the neutron kinetic energy distributions could be anisotropic when viewed by multiple lines-of-sight. These anisotropies provide a diagnostic of burn averaged plasma velocity distributions. We present the results of measurements made for a variety of DT implosions and discuss their possible physical interpretations. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC.

  3. A method for the determination of detector channel dead time for a neutron time-of-flight spectrometer

    International Nuclear Information System (INIS)

    Adib, M.; Salama, M.; Abd-Kawi, A.; Sadek, S.; Hamouda, I.

    1975-01-01

    A new method is developed to measure the dead time of a detector channel for a neutron time-of-flight spectrometer. The method is based on the simultaneous use of two identical BF 3 detectors but with two different efficiencies, due to their different enrichment in B 10 . The measurements were performed using the T.O.F. spectrometer installed at channel No. 6 of the ET-RR-1 reactor. The main contribution to the dead time was found to be due to the time analyser and the neutron detector used. The analyser dead time has been determined using a square wave pulse generator with frequency of 1 MC/S. For channel widths of 24.4 us, 48.8 ud and 97.6 us, the weighted dead times for statistical pulse distribution were found to be 3.25 us, 1.87 us respectively. The dead time of the detector contributes mostly to the counting losses and its value was found to be (33+-3) us

  4. Time-of-flight small-angle-neutron-scattering data reduction and analysis at LANSCE (Los Alamos Neutron Scattering Center) with program SMR

    International Nuclear Information System (INIS)

    Hjelm, R.P. Jr.; Seegar, P.A.

    1989-01-01

    A user-friendly, integrated system, SMR, for the display, reduction and analysis of data from time-of-flight small-angle neutron diffractometers is described. Its purpose is to provide facilities for data display and assessment and to provide these facilities in near real time. This allows the results of each scattering measurement to be available almost immediately, and enables the experimenter to use the results of a measurement as a basis for other measurements in the same instrument allocation. 8 refs., 11 figs

  5. Off-line correction for excessive constant-fraction-discriminator walk in neutron time-of-flight experiments

    International Nuclear Information System (INIS)

    Heilbronn, Lawrence; Iwata, Yoshiyuki; Iwase, H.

    2003-01-01

    A method for reducing excessive constant-fraction-discriminator walk that utilizes experimental data in the off-line analysis stage is introduced. Excessive walk is defined here as any walk that leads to an overall timing resolution that is much greater than the intrinsic timing resolution of the detection system. The method is able to reduce the contribution to the overall timing resolution from the walk that is equal to or less than the intrinsic timing resolution of the detectors. Although the method is explained in the context of a neutron time-of-flight experiment, it is applicable to any data set that satisfies two conditions. (1) A measure of the signal amplitude for each event must be recorded on an event-by-event basis; and (2) There must be a distinguishable class of events present where the timing information is known a priori

  6. Direct mass measurements in the light neutron-rich region using a combined energy and time-of-flight technique

    International Nuclear Information System (INIS)

    Pillai, C.; Swenson, L.W.; Vieira, D.J.; Butler, G.W.; Wouters, J.M.; Rokni, S.H.; Vaziri, K.; Remsberg, L.P.

    1985-01-01

    This experiment has demonstrated that direct mass measurements can be performed (albeit of low precision in this first attempt) using the M proportional to ET 2 method. This technique has the advantage that many particle-bound nuclei, produced in fragmentation reactions can be measured simultaneously, independent of their N or Z. The main disadvantage of this approach is that both energy and time-of-flight must be measured precisely on an absolute scale. Although some mass walk with N and Z was observed in this experiment, these uncertainties were largely removed by extrapolating the smooth dependence observed for known nuclei which lie closer to the valley of β-stability. Mass measurements for several neutron-rich light nuclei ranging from 17 C to 26 Ne have been performed. In all cases these measurements agree with the latest mass compilation of Wapstra and Audi. The masses of 20 N and 24 F have been determined for the first time

  7. HORACE: Software for the analysis of data from single crystal spectroscopy experiments at time-of-flight neutron instruments

    Energy Technology Data Exchange (ETDEWEB)

    Ewings, R.A.; Buts, A.; Le, M.D. [ISIS Facility, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX (United Kingdom); Duijn, J. van [Departamento de Mecánica, Universidad de Córdoba, 14071 Córdoba (Spain); Bustinduy, I. [ESS Bilbao, Poligono Ugaldeguren III, Pol. A, 7B - 48170 Zamudio, Bizkaia – País Vasco (Spain); Perring, T.G., E-mail: toby.perring@stfc.ac.uk [ISIS Facility, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX (United Kingdom); London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    2016-10-21

    The HORACE suite of programs has been developed to work with large multiple-measurement data sets collected from time-of-flight neutron spectrometers equipped with arrays of position-sensitive detectors. The software allows exploratory studies of the four dimensions of reciprocal space and excitation energy to be undertaken, enabling multi-dimensional subsets to be visualized, algebraically manipulated, and models for the scattering to simulated or fitted to the data. The software is designed to be an extensible framework, thus allowing user-customized operations to be performed on the data. Examples of the use of its features are given for measurements exploring the spin waves of the simple antiferromagnet RbMnF{sub 3} and ferromagnetic iron, and the phonons in URu{sub 2}Si{sub 2}.

  8. HORACE: Software for the analysis of data from single crystal spectroscopy experiments at time-of-flight neutron instruments

    International Nuclear Information System (INIS)

    Ewings, R.A.; Buts, A.; Le, M.D.; Duijn, J. van; Bustinduy, I.; Perring, T.G.

    2016-01-01

    The HORACE suite of programs has been developed to work with large multiple-measurement data sets collected from time-of-flight neutron spectrometers equipped with arrays of position-sensitive detectors. The software allows exploratory studies of the four dimensions of reciprocal space and excitation energy to be undertaken, enabling multi-dimensional subsets to be visualized, algebraically manipulated, and models for the scattering to simulated or fitted to the data. The software is designed to be an extensible framework, thus allowing user-customized operations to be performed on the data. Examples of the use of its features are given for measurements exploring the spin waves of the simple antiferromagnet RbMnF_3 and ferromagnetic iron, and the phonons in URu_2Si_2.

  9. Off-line correction for excessive constant-fraction-discriminator walk in neutron time-of-flight experiments

    International Nuclear Information System (INIS)

    Heilbronn, L.; Iwata, Y.; Iwase, H.

    2004-01-01

    A method for reducing excessive constant-fraction-discriminator walk that utilizes experimental data in the off-line analysis stage is introduced. Excessive walk is defined here as any walk that leads to an overall timing resolution that is much greater than the intrinsic timing resolution of the detection system. The method is able to reduce the contribution to the overall timing resolution from the walk to a value that is equal to or less than the intrinsic timing resolution of the detectors. Although the method is explained in the context of a neutron time-of-flight experiment, it is applicable to any data set that satisfies two conditions: (1) a measure of the signal amplitude for each event must be recorded on an event-by-event basis; and (2) there must be a distinguishable class of events present where the timing information is known a priori

  10. Neutron time-of-flight ion temperature diagnostic for inertial confinement fusion experiments

    International Nuclear Information System (INIS)

    Chrien, R.E.; Simmons, D.F.; Holmberg, D.L.

    1992-01-01

    We are constructing a T i diagnostic for low neutron yield (5 x 10 7 to above 10 9 ) d-d and d-t targets in the Nova facility at Livermore. The diagnostic measures the neutron energy spread with 960 scintillator-photomultiplier detectors located 28 m from the target and operates in the single-hit mode. Each detector can measure a single neutron arrival with time resolution of 1 ns or better. The arrival time distribution is constructed from the results of typically 200--500 detector measurements. The ion temperature is determined from the spread in neutron energy ΔE n ∝ T i 1/2 , which is related to the arrival time spread by Δt/t = 1(1/2 ΔE n /E n ). Each neutron arrival is detected by using a photomultiplier tube to observe the recoil proton from elastic scattering in a fast plastic scintillator. The timing electronics for each channel consist of a novel constant fraction-like discriminator and a multiple hit time-to-digital converter (TDC). The overall system design, together with single channel performance data, is presented

  11. PLATYPUS - A Time-of-Flight Neutron Reflectometer at the OPAL Facility

    International Nuclear Information System (INIS)

    James, Michael; Brule, Alain

    2005-01-01

    Full text: Neutron reflectometry is used to probe the structure of surfaces, thin-films or buried interfaces as well as processes occurring at surfaces and interfaces. Applications cover adsorbed surfactant layers, self-assembled monolayers, biological membranes, electrochemical and catalytic interfaces, polymer coatings and photosensitive films. The PLATYPUS neutron reflectometer has been recognised as one of the highest priority instruments to be constructed at the new 20MW OPAL research reactor at Lucas Heights. The instrument will be capable of collecting data from solid, liquid and magnetic samples using a broad wavelength band of polarised or non-polarised neutrons. Details of the design and construction of the PLATYPUS reflectometer will be given. (authors)

  12. Data acquisition and control system for the IPNS time-of-flight neutron scattering instruments

    International Nuclear Information System (INIS)

    Daly, R.T.; Haumann, J.R.; Kraimer, M.R.; Lenkszus, F.R.; Lidinsky, W.P.; Morgan, C.B.; Rutledge, L.L.; Rynes, P.E.; Tippie, J.W.

    1979-01-01

    The Argonne Intense Pulsed Neutron System (IPNS-I) presently under construction at Argonne National Laboratory will include a number of neutron scattering instruments. This study investigates the data acquisition requirements of these instruments and proposes three alternative multiprocessor systems which will satisfy these requirements. All proposals are star configurations with a super-mini as the central node or HOST. The first proposal is based on front-ends composed of two or more 16-bit microcomputers, the second proposal is based on front ends consisting of a combination of a mini and microcomputers, and the third is based on a minicomputer with an intelligent CAMAC controller

  13. Experimental verification of a method to create a variable energy neutron beam from a monoenergetic, isotropic source using neutron elastic scatter and time of flight

    Energy Technology Data Exchange (ETDEWEB)

    Whetstone, Zachary D., E-mail: zacwhets@umich.edu; Flaska, Marek, E-mail: mflaska@umich.edu; Kearfott, Kimberlee J., E-mail: kearfott@umich.edu

    2016-08-11

    An experiment was performed to determine the neutron energy of near-monoergetic deuterium–deuterium (D–D) neutrons that elastically scatter in a hydrogenous target. The experiment used two liquid scintillators to perform time of flight (TOF) measurements to determine neutron energy, with the start detector also serving as the scatter target. The stop detector was placed 1.0 m away and at scatter angles of π/6, π/4, and π/3 rad, and 1.5 m at a scatter angle of π/4 rad. When discrete 1 ns increments were implemented, the TOF peaks had estimated errors between −21.2 and 3.6% relative to their expected locations. Full widths at half-maximum (FWHM) ranged between 9.6 and 20.9 ns, or approximately 0.56–0.66 MeV. Monte Carlo simulations were also conducted that approximated the experimental setup and had both D–D and deuterium–tritium (DT) neutrons. The simulated results had errors between −17.2 and 0.0% relative to their expected TOF peaks when 1 ns increments were applied. The largest D–D and D–T FWHMs were 26.7 and 13.7 ns, or approximately 0.85 and 4.98 MeV, respectively. These values, however, can be reduced through manipulation of the dimensions of the system components. The results encourage further study of the neutron elastic scatter TOF system with particular interest in application to active neutron interrogation to search for conventional explosives.

  14. Neutron capture cross section measurement of $^{151}Sm$ at the CERN neutron Time of Flight Facility (nTOF)

    CERN Document Server

    Abbondanno, U; Alvarez-Velarde, F; Alvarez-Pol, H; Andriamonje, Samuel A; Andrzejewski, J; Badurek, G; Baumann, P; Becvar, F; Benlliure, J; Berthoumieux, E; Calviño, F; Cano-Ott, D; Capote, R; Cennini, P; Chepel, V; Chiaveri, Enrico; Colonna, N; Cortés, G; Cortina-Gil, D; Couture, A; Cox, J; Dababneh, S; Dahlfors, M; David, S; Dolfini, R; Domingo-Pardo, C; Durán, I; Embid-Segura, M; Ferrant, L; Ferrari, A; Ferreira-Marques, R; Frais-Kölbl, H; Furman, W; Gonçalves, I; Gallino, R; Gonzalez-Romero, E; Goverdovski, A; Gramegna, F; Griesmayer, E; Gunsing, F; Haas, B; Haight, R; Heil, M; Herrera-Martínez, A; Isaev, S; Jericha, E; Kappeler, F; Kadi, Y; Karadimos, D; Kerveno, M; Ketlerov, V; Köhler, P; Konovalov, V; Krticka, M; Lamboudis, C; Leeb, H; Lindote, A; Lopes, I; Lozano, M; Lukic, S; Marganiec, J; Marrone, S; Martinez-Val, J; Mastinu, P; Mengoni, A; Milazzo, P M; Molina-Coballes, A; Moreau, C; Mosconi, M; Neves, F; Oberhummer, Heinz; O'Brien, S; Pancin, J; Papaevangelou, T; Paradela, C; Pavlik, A; Pavlopoulos, P; Perlado, J M; Perrot, L; Pignatari, M; Plag, R; Plompen, A; Plukis, A; Poch, A; Policarpo, Armando; Pretel, C; Quesada, J; Raman, S; Rapp, W; Rauscher, T; Reifarth, R; Rosetti, M; Rubbia, Carlo; Rudolf, G; Rullhusen, P; Salgado, J; Soares, J C; Stéphan, C; Tagliente, G; Taín, J L; Tassan-Got, L; Tavora, L; Terlizzi, R; Vannini, G; Vaz, P; Ventura, A; Villamarín, D; Vincente, M C; Vlachoudis, V; Voss, F; Wendler, H; Wiescher, M; Wissha, K

    2004-01-01

    The measurement of **1**5**1Sm(n, gamma)**1**5**2Sm (samarium) cross section showed improved performance of the new spallation neutron facility. It covered a wide energy range with good resolution, high neutron flux, low backgrounds and a favourable duty factor. The samarium cross section was found to be of great importance for characterizing neutron capture nucleosynthesis in asymptotic giant stars. The combination of these features provided a promising basis for a broad experimental program directed towards application in astrophysics and advanced nuclear technologies. (Edited abstract)

  15. Neutron time-of-flight signals from expanding or contracting spherical sources

    International Nuclear Information System (INIS)

    Murphy, T.J.; Chrien, R.E.; Klare, K.A.

    1996-01-01

    The width of the energy distribution of fusion-produced neutrons is often used as an indication of the temperature of the reacting ions. The Doppler broadening of the neutron energy is due to the center-of-mass velocity of reacting ion pairs and is characterized by the ion temperature for a Maxwellian distribution of ions with zero collective velocity. If there is bulk fluid motion or turbulence characterized by a velocity on the order of the ion thermal speed, a significant additional broadening may introduced. Suggestions of this phenomenon have been observed for two classes of laser targets. The first is a ''gas bag'' target, in which a deuterated hydrocarbon gas is contained in a thin spherical membrane and illuminated uniformly. The second target is an ICF capsule with a deuterated plastic inner layer. In both cases, measured neutron energy distributions were wider than expected from theoretical ion temperatures alone would predict, and if interpreted as indicative of the ion temperature, are inconsistent with the neutron yields observed

  16. AMOR – the time-of-flight neutron reflectometer at SINQ/PSI

    Indian Academy of Sciences (India)

    range of 0.15 nm <λ< 1.3 nm) as well as in the monochromatic (θ–2θ) mode with both polarized and unpolarized neutrons. AMOR is designed to perform reflectometry measure- ments in horizontal sample-plane ... destructive microscopic probes for the investigation of stratified structures and hidden interfaces. Due to the ...

  17. Multi-Grid detector for neutron spectroscopy: results obtained on time-of-flight spectrometer CNCS

    Science.gov (United States)

    Anastasopoulos, M.; Bebb, R.; Berry, K.; Birch, J.; Bryś, T.; Buffet, J.-C.; Clergeau, J.-F.; Deen, P. P.; Ehlers, G.; van Esch, P.; Everett, S. M.; Guerard, B.; Hall-Wilton, R.; Herwig, K.; Hultman, L.; Höglund, C.; Iruretagoiena, I.; Issa, F.; Jensen, J.; Khaplanov, A.; Kirstein, O.; Lopez Higuera, I.; Piscitelli, F.; Robinson, L.; Schmidt, S.; Stefanescu, I.

    2017-04-01

    The Multi-Grid detector technology has evolved from the proof-of-principle and characterisation stages. Here we report on the performance of the Multi-Grid detector, the MG.CNCS prototype, which has been installed and tested at the Cold Neutron Chopper Spectrometer, CNCS at SNS. This has allowed a side-by-side comparison to the performance of 3He detectors on an operational instrument. The demonstrator has an active area of 0.2 m2. It is specifically tailored to the specifications of CNCS. The detector was installed in June 2016 and has operated since then, collecting neutron scattering data in parallel to the He-3 detectors of CNCS. In this paper, we present a comprehensive analysis of this data, in particular on instrument energy resolution, rate capability, background and relative efficiency. Stability, gamma-ray and fast neutron sensitivity have also been investigated. The effect of scattering in the detector components has been measured and provides input to comparison for Monte Carlo simulations. All data is presented in comparison to that measured by the 3He detectors simultaneously, showing that all features recorded by one detector are also recorded by the other. The energy resolution matches closely. We find that the Multi-Grid is able to match the data collected by 3He, and see an indication of a considerable advantage in the count rate capability. Based on these results, we are confident that the Multi-Grid detector will be capable of producing high quality scientific data on chopper spectrometers utilising the unprecedented neutron flux of the ESS.

  18. Time-of-flight 3D Neutron Diffraction for Multigrain Crystallography

    DEFF Research Database (Denmark)

    Cereser, Alberto

    of the individual grains within the sample. The experiments were conducted at the single crystal diffractometer SENJU at the Japanese neutron source J-PARC. The choice of this instrument was motivated by its large coverage of the reciprocal space. The instrument had to undergo modifications to enable ToF 3DND...... for indexing SENJU data, which then serves as prior information to restrict the extinction spots that belong to the same grain. The ToF 3DND methods are verified through the study of two different samples: an Iron rod and a shape memory alloy (SMA) CoNiGa bi-crystal. Part of this verification involves...

  19. Combined proton-recoil and neutron time-of-flight spectrometer for 14 MeV neutrons

    International Nuclear Information System (INIS)

    Grosshoeg, G.; Aronsson, D.; Arvidsson, E.; Beimer, K.-H.; Pekkari, L.-O.; Rydz, R.; Sjoestrand, N.G.

    1983-05-01

    The main effort put into this work is the foundation of a reliable physical basis for a 12-16 MeV neutron-spectrometer at JET. The essential problem is the amount of scatterer that can be incorporated without losing resolution. We have found two possible methods, the use of a pure hydrogen scatterer and the use of a polyethylene foil scatterer. The pure hydrogen solution gives a very complicated spectrometer with large detectors. The polyethylene solution is limited by the thickness and the width of the foil. We judge the solution with the polyethylene foil to be the most promising one for a reliable spectrometer. However, a large foil area is needed. This gives a spectrometer design with an annular foil, an annular neutron detection system, and a central proton-detector. An efficiency of 10 - 6 counts/s per n/cm 2 ,s at the foil can be obtained with a resolution in the order of 100 keV for 14 MeV neutrons. Following the General Requirements given in the contract of this work, we concluded that an instrument with the desired properties can be made. The instruments is able to give useful information about the plasma from plasma temperatures of about 5 keV. (Authors)

  20. Time-of-flight data acquisition unit (DAU) for neutron scattering experiments. Specification of the requirements and design concept. Version 3.1

    International Nuclear Information System (INIS)

    Herdam, G.; Klessmann, H.; Wawer, W.; Adebayo, J.; David, G.; Szatmari, F.

    1989-12-01

    This specification describes the requirements for the Data Acquisition Unit (DAU) and defines the design concept for the functional units involved. The Data Acquisition Unit will be used in the following neutron scattering experiments: Time-of-Flight Spectrometer NEAT, Time-of-Flight Spectrometer SPAN. In addition, the data of the SPAN spectrometer in Spin Echo experiments will be accumulated. The Data Acquisition Unit can be characterised by the following requirements: Time-of-flight measurement with high time resolution (125 ns), sorting the time-of-flight in up to 4096 time channels (channel width ≥ 1 μs), selection of different time channel widths for peak and background, on-line time-of-flight correction for neutron flight paths of different lengths, sorting the detector position information in up to 4096 position channels, accumulation of two-dimensional spectra in a 32 Mbyte RAM memory (4 K time channels*4 K position channels*16 bits). Because of the stringent timing requirements the functional units of the DAU are hardware controlled via tables. The DAU is part of a process control system which has access to the functional units via the VMEbus in order to initialise, to load tables and control information, and to read status information and spectra. (orig.) With 18 figs

  1. Dynamics in γ-Fe2O3 nanoparticles studied by time-of-flight polarized neutron scattering

    DEFF Research Database (Denmark)

    Kuhn, L.T.; Lefmann, K.; Klausen, S.N.

    2004-01-01

    The inelastic neutron-scattering signal from magnetic nanoparticles contains information on magnetic dynamics like superparamagnetic relaxation and collective magnetic excitations. Often another, very broad quasi-elastic component is observed in addition. We have studied this quasi-elastic neutron...... signal from 4 nm ferrimagnetic maghemite (gamma-Fe(2)O(3)) particles, and by means of time-of-flight polarised neutron scattering we have identified the source of (most of) this signal to be water adsorbed at the surface of the nanoparticles. A minor part of the signal has its origin in dynamics...

  2. Correlation in the statistical analysis of a reverse Fourier neutron time-of-flight experiment. Pt. 2

    International Nuclear Information System (INIS)

    Tilli, K.J.

    1982-01-01

    The significance of the correlation in the statistical analysis of reverse Fourier neutron time-of-flight observations has been evaluated by applying different methods of estimation to diffraction patterns containing peaks with Gaussian line shapes. Effects of the correlation between adjacent channels of a spectrum arise both from the incorrect weighting of the experiment's independent variables and from the misinterpretation of the number of independent observations in the data. The incorrect weighting bears the greatest effects on the width parameter of a Gaussian profile, and it leads to an increase in the relative weights of the broadest peaks of the diffraction pattern. If the correlation is ignored in the analysis, the estimates obtained for the parameters of a model will not be exactly the same as those evaluated from the minimum variance estimation, in which the correlation is taken into account. However, the differences will not be statistically significant. Nevertheless, the standard deviations will then be underestimated typically by a factor of two, which will have serious consequences on every aspect of the statistical inference. (orig.)

  3. A Time of flight spectrometer for measurements of double differential neutron scattering cross sections; Montaje de un espectrometro por tiempo de vuelo para la medicion de secciones doble diferenciales de dispersion de neutrones

    Energy Technology Data Exchange (ETDEWEB)

    Padron, I; Dominguez, O; Sarria, P. Sandin, C. [Centro de Estudios Aplicados al Desarrollo Nuclear (CEADEN), La Habana (Cuba)

    1996-05-01

    The time -of-Flight neutron spectrometry technique by associated particle method was improved using a D-T neutron generator at Laboratory of Nuclear Analysis. This technique was implemented for double differential cross section measurements and supported by the IAEA Project CUB/01/005. An stilbene scintillation detector (dia=100 mm, length=50 mm) was used as principal neutron detector detector and was situated outside a hole in the concrete wall. This way the fligth path was extended and the scattered neutron cone accurate collimated throught the 2 m concrete wall. For the associated particle {alpha} detection a thin plastic NE-102 scint illator was used, as well as, two scintilation detectors and a long counter for the neutron flux monitoring. In this TOF neutron spectrometer (3.40 m flight path) a 1.7 nseg. temporal resolution was obtained.

  4. Development of a 'chronotron' for time of flight fast neutron spectrometer; Realisation d'un chronotron pour spectrometre a neutrons rapides par temps de vol

    Energy Technology Data Exchange (ETDEWEB)

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

    1958-10-15

    A chronotron using storage circuits of a 100 channels amplitude analyser has been developed in order to measure the time of flight of fast neutrons. A time dilatation is obtained by a distribution of 20 6BN6 tubes. The width at half maximum of prompt coincidences curve is 1,6.10{sup -9} s for {beta}-{gamma} coincidences from An{sup 198} and 2.10{sup -9} s for n-{alpha} coincidences from (d, t) reaction. (author) [French] En vue de realiser un spectrometre a neutrons rapides par temps de vol, un chronotron utilisant les circuits d'enregistrement d'un selecteur d'amplitude de 100 canaux a ete construit. Une dilatation du temps est obtenue a l'aide d'une distribution de 20 lampes 6BN6. La largeur a mi-hauteur de la courbe de resolution est 1,6.10{sup -9} s pour les coincidences {beta}-{gamma} de Au{sup 198} et 2.10{sup -9} s pour les coincidences n-{alpha} de la reaction (d, t). (auteur)

  5. Solutions for implementing time-of-flight techniques in low-angle neutron scattering, as realized on the Low-Q Diffractometer at Los Alamos

    International Nuclear Information System (INIS)

    Hjelm, R.P. Jr.; Seeger, P.A.

    1992-01-01

    The implementation of small-angle (Low-momentum transfer) neutron scattering at pulsed spallation sources, using time of flight methods, has meant the introduction of some new ideas in instrument design, data acquisition, data reduction and computer management of the experiment and the data. Here we recount some of the salient aspects of solutions for implementing time of fight small-angle neutron scattering instruments at pulsed sources, as realized on the Low-Q Diffractometer, LQD, at Los Alamos. We consider, fortlier, some of the problems that are yet to be solved, and take a short excursion into the future of SANS instrumentation at pulsed sources

  6. Development of a geometry-compensated neutron time-of-flight detector for ICF applications with approximately 200 ps time response

    International Nuclear Information System (INIS)

    Murphy, T.J.; Lerche, R.A.

    1992-01-01

    Current-mode neutron time-of-flight detectors are used on Nova for neutron yield, ion temperature, and neutron emission time measurements. Currently used detectors are limited by the time response of the microchannel plate photomultiplier tubes used with the scintillators, scintillator decay time, scintillator thickness, and oscilloscope response time. A change in the geometry of the scintillator allows one to take advantage of the increased time resolution made possible by more advanced transient recorders and microchannel plate photomultiplier tubes. A prototype detector has been designed to incorporate these changes, and could potentially yield time resolution of less than 150 ps. Experimental results are presented demonstrating an ion temperature measurement of a direct-drive DT implosion on Nova

  7. Prompt fission neutron spectra from fission induced by 1 to 8 MeV neutrons on 235U and 239Pu using the double time-of-flight technique

    International Nuclear Information System (INIS)

    Noda, S.; Haight, R. C.; Nelson, R. O.; Devlin, M.; O'Donnell, J. M.; Chatillon, A.; Granier, T.; Belier, G.; Taieb, J.; Kawano, T.; Talou, P.

    2011-01-01

    Prompt fission neutron spectra from 235 U and 239 Pu were measured for incident neutron energies from 1 to 200 MeV at the Weapons Neutron Research facility (WNR) of the Los Alamos Neutron Science Center, and the experimental data were analyzed with the Los Alamos model for the incident neutron energies of 1-8 MeV. A CEA multiple-foil fission chamber containing deposits of 100 mg 235 U and 90 mg 239 Pu detected fission events. Outgoing neutrons were detected by the Fast Neutron-Induced γ-Ray Observer array of 20 liquid organic scintillators. A double time-of-flight technique was used to deduce the neutron incident energies from the spallation target and the outgoing energies from the fission chamber. These data were used for testing the Los Alamos model, and the total kinetic energy parameters were optimized to obtain a best fit to the data. The prompt fission neutron spectra were also compared with the Evaluated Nuclear Data File (ENDF/B-VII.0). We calculate average energies from both experimental and calculated fission neutron spectra.

  8. Optimizing a neutron-beam focusing device for the direct geometry time-of-flight spectrometer TOFTOF at the FRM II reactor source

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, N.G. [Nanoscience Center, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø (Denmark); Simeoni, G.G., E-mail: ggsimeoni@outlook.com [Heinz Maier-Leibnitz Zentrum (MLZ) and Physics Department, Technical University of Munich, D-85748 Garching (Germany); Lefmann, K. [Nanoscience Center, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø (Denmark)

    2016-04-21

    A dedicated beam-focusing device has been designed for the direct geometry thermal-cold neutron time-of-flight spectrometer TOFTOF at the neutron facility FRM II (Garching, Germany). The prototype, based on the compressed Archimedes' mirror concept, benefits from the adaptive-optics technology (adjustable supermirror curvature) and the compact size (only 0.5 m long). We have simulated the neutron transport across the entire guide system. We present a detailed computer characterization of the existing device, along with the study of the factors mostly influencing the future improvement. We have optimized the simulated prototype as a function of the neutron wavelength, accounting also for all relevant features of a real instrument like the non-reflecting side edges. The results confirm the “chromatic” displacement of the focal point (flux density maximum) at fixed supermirror curvature, and the ability of a variable curvature to keep the focal point at the sample position. Our simulations are in excellent agreement with theoretical predictions and the experimentally measured beam profile. With respect to the possibility of a further upgrade, we find that supermirror coatings with m-values higher than 3.5 would have only marginal influence on the optimal behaviour, whereas comparable spectrometers could take advantage of longer focusing segments, with particular impact for the thermal region of the neutron spectrum.

  9. Numerical analysis of resonances induced by s wave neutrons in transmission time-of-flight experiments with a computer IBM 7094 II

    International Nuclear Information System (INIS)

    Corge, Ch.

    1969-01-01

    Numerical analysis of transmission resonances induced by s wave neutrons in time-of-flight experiments can be achieved in a fairly automatic way on an IBM 7094/II computer. The involved computations are carried out following a four step scheme: 1 - experimental raw data are processed to obtain the resonant transmissions, 2 - values of experimental quantities for each resonance are derived from the above transmissions, 3 - resonance parameters are determined using a least square method to solve the over determined system obtained by equalling theoretical functions to the correspondent experimental values. Four analysis methods are gathered in the same code, 4 - graphical control of the results is performed. (author) [fr

  10. Study of the delayed neutron emission through the time-of-flight method. Application to 49K, 50K and 51K

    International Nuclear Information System (INIS)

    Rachidi, J.

    1983-04-01

    This work is dedicated to the study of the emission of delayed neutrons observed in the decay of 49 K, 50 K and 51 K. Spectroscopic data are non-existent for these 3 isotopes, so we have had to design a specific detection system based on a large-surface scintillation counter. A series of n-γ coincidence measurement has allowed us to determine the energy levels of the non-bound states of 49 Ca, 50 Ca and 51 Ca and to establish the nature of the beta transitions (K → Ca). We have measured the energy of the delayed neutrons through the time-of-flight method. Our results are consistent with the model of the p-n states based on the Bansac-French's works. This model shows that the non-bound states of the calcium isotopes discovered in the experiment are represented by simple configurations of the (sd) -1 (fp) n type. (A.C.)

  11. Deuterated-xylene (xylene-d{sub 10}; EJ301D): A new, improved deuterated liquid scintillator for neutron energy measurements without time-of-flight

    Energy Technology Data Exchange (ETDEWEB)

    Becchetti, F.D.; Raymond, R.S.; Torres-Isea, R.O. [Department of Physics, University of Michigan, Ann Arbor, MI 48109 (United States); Di Fulvio, A.; Clarke, S.D.; Pozzi, S.A. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Febbraro, M. [Oak Ridge National Laboratory, Oak Ridge, TN 37830 (United States)

    2016-06-01

    In conjunction with Eljen Technology, Inc. (Sweetwater,TX) we have designed, constructed, and evaluated a 3 in. ×3 in. deuterated-xylene organic liquid scintillator (C{sub 8}D{sub 10}; EJ301D) as a fast neutron detector. Similar to deuterated benzene (C{sub 6}D{sub 6}; NE230, BC537, and EJ315) this scintillator can provide good pulse-shape discrimination between neutrons and gamma rays, has good timing characteristics, and can provide a light spectrum with peaks corresponding to discrete neutron energy groups up to ca. 20 MeV. Unlike benzene-based detectors, deuterated xylene is less volatile, less toxic, is not known to be carcinogenic, has a higher flashpoint, and hence is much safer for many applications. In addition EJ301D can provide slightly more light output and better PSD than deuterated-benzene scintillators. We show that, as with deuterated-benzene scintillators, the light-response spectra can be unfolded to provide useable neutron energy spectra without need for time-of-flight (ToF). An array of these detectors arranged at many angles close to a reaction target can be much more effective (×10 to ×100 or more) than an array of long-path ToF detectors which must utilize a narrowly-bunched and pulse-selected beam. As we demonstrate using a small Van de Graaff accelerator, measurements can thus be performed when a bunched and pulse-selected beam (as needed for time-of-flight) is not available.

  12. Time-of-flight spectrometer for slow neutrons in use at the reactor in Saclay. Its application for the study of the inelastic diffusion of cold neutrons; L'appareillage de spectrometrie a temps-de-vol pour neutrons lents en service a la pile de Saclay. Son application a l'etude de la diffusion inelastique des neutrons froids

    Energy Technology Data Exchange (ETDEWEB)

    Jacsot, B; Netter, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Galula, M [Centre National de la Recherche Scientifique (CNRS), 91 - Gif-sur-Yvette (France)

    1955-07-01

    The time-of-flight spectrometers is constituted of a mechanic swivel obturator which absorbs neutrons until energies above 1 KeV, a mechanic filter which allow to retain only high wave length components and a delayed pulses selector with 100 channels. Its main application field is the thermic region where it allowed to measure the inelastic scattering of neutrons using various materials as H{sub 2}O, D{sub 2}O, Be, BeO, etc... (M.P.)

  13. In-beam test of the Boron-10 Multi-Grid neutron detector at the IN6 time-of-flight spectrometer at the ILL

    Energy Technology Data Exchange (ETDEWEB)

    Birch, J; Hultman, L; Höglund, C [Linköping University, Thin Film Physics Division, IFM, SE-581 83 Linköping (Sweden); Buffet, J-C; Clergeau, J-F; Correa, J; Van Esch, P; Ferraton, M; Guerard, B; Halbwachs, J; Khaplanov, A; Koza, M; Piscitelli, F; Zbiri, M [Institute Laue Langevin, Rue Jules Horowitz, FR-38000 Grenoble (France); Hall-Wilton, R [European Spallation Source ESS AB, P.O Box 176, SE-221 00 Lund (Sweden)

    2014-07-24

    A neutron detector concept based on solid layers of boron carbide enriched in {sup 10}B has been in development for the last few years as an alternative for {sup 3}He by collaboration between the ILL, ESS and Linköping University. This Multi-Grid detector uses layers of aluminum substrates coated with {sup 10}B{sub 4}C on both sides that are traversed by the incoming neutrons. Detection is achieved using a gas counter readout principle. By segmenting the substrate and using multiple anode wires, the detector is made inherently position sensitive. This development is aimed primarily at neutron scattering instruments with large detector areas, such as time-of-flight chopper spectrometers. The most recent prototype has been built to be interchangeable with the {sup 3}He detectors of IN6 at ILL. The {sup 10}B detector has an active area of 32 x 48cm{sup 2}. It was installed at the IN6 instrument and operated for several weeks, collecting data in parallel with the regularly scheduled experiments, thus providing the first side-by-side comparison with the conventional {sup 3}He detectors. Results include an efficiency comparison, assessment of the in-detector scattering contribution, sensitivity to gamma-rays and the signal-to-noise ratio in time-of-flight spectra. The good expected performance has been confirmed with the exception of an unexpected background count rate. This has been identified as natural alpha activity in aluminum. New convertor substrates are under study to eliminate this source of background.

  14. Optimisation of a collimator array for a multi-detector time-of-flight spectrometer for fast neutrons

    International Nuclear Information System (INIS)

    Schlegel-Bickmann, D.

    1979-01-01

    A Monte Carlo program has been developed which calculates the neutron background due to the interaction between incident neutrons and the collimator fan near the detector in dependence of geometry and material parameters. The position of the neutron source with regard to the collimators may be chosen at random. The program is also suitable for other three-dimensional transport problems of fast neutrons in the energy range between 0.5 and 20 MeV. The modular structure makes it easy to adapt it to highly specific problems. (orig.) 891 HP 892 MB [de

  15. Obtaining the neutron time-of-flight instrument response function for a single D-T neutron utilizing n-alpha coincidence from the d(t, α) n nuclear reaction

    Science.gov (United States)

    Styron, Jedediah; Ruiz, Carlos; Hahn, Kelly; Cooper, Gary; Chandler, Gordon; Jones, Brent; McWatters, Bruce; Smith, Jenny; Vaughan, Jeremy

    2017-10-01

    A measured neutron time-of-flight (nTOF) signal is a convolution of the neutron reaction history and the instrument response function (IRF). For this work, the IRF was obtained by measuring single, D-T neutron events by utilizing n-alpha coincidence. The d(t, α) n nuclear reaction was produced at Sandia National Laboratories' Ion Beam Laboratory using a 300-keV Cockroft-Walton generator to accelerate a 2- μA beam, of 175-keV D + ions, into a stationary, 2.6- μm, ErT2 target. Comparison of these results to those obtained using cosmic-rays and photons will be discussed. Sandia National Laboratories.

  16. A method for in situ absolute DD yield calibration of neutron time-of-flight detectors on OMEGA using CR-39-based proton detectors

    Energy Technology Data Exchange (ETDEWEB)

    Waugh, C. J., E-mail: cjwaugh@mit.edu; Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.; Petrasso, R. D. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States); Rosenberg, M. J.; Glebov, V. Yu.; Sangster, T. C.; Stoeckl, C. [Laboratory for Laser Energetics, Rochester, New York 14623 (United States)

    2015-05-15

    Neutron time of flight (nTOF) detectors are used routinely to measure the absolute DD neutron yield at OMEGA. To check the DD yield calibration of these detectors, originally calibrated using indium activation systems, which in turn were cross-calibrated to NOVA nTOF detectors in the early 1990s, a direct in situ calibration method using CR-39 range filter proton detectors has been successfully developed. By measuring DD neutron and proton yields from a series of exploding pusher implosions at OMEGA, a yield calibration coefficient of 1.09 ± 0.02 (relative to the previous coefficient) was determined for the 3m nTOF detector. In addition, comparison of these and other shots indicates that significant reduction in charged particle flux anisotropies is achieved when bang time occurs significantly (on the order of 500 ps) after the trailing edge of the laser pulse. This is an important observation as the main source of the yield calibration error is due to particle anisotropies caused by field effects. The results indicate that the CR-39-nTOF in situ calibration method can serve as a valuable technique for calibrating and reducing the uncertainty in the DD absolute yield calibration of nTOF detector systems on OMEGA, the National Ignition Facility, and laser megajoule.

  17. A method for in situ absolute DD yield calibration of neutron time-of-flight detectors on OMEGA using CR-39-based proton detectors.

    Science.gov (United States)

    Waugh, C J; Rosenberg, M J; Zylstra, A B; Frenje, J A; Séguin, F H; Petrasso, R D; Glebov, V Yu; Sangster, T C; Stoeckl, C

    2015-05-01

    Neutron time of flight (nTOF) detectors are used routinely to measure the absolute DD neutron yield at OMEGA. To check the DD yield calibration of these detectors, originally calibrated using indium activation systems, which in turn were cross-calibrated to NOVA nTOF detectors in the early 1990s, a direct in situ calibration method using CR-39 range filter proton detectors has been successfully developed. By measuring DD neutron and proton yields from a series of exploding pusher implosions at OMEGA, a yield calibration coefficient of 1.09 ± 0.02 (relative to the previous coefficient) was determined for the 3m nTOF detector. In addition, comparison of these and other shots indicates that significant reduction in charged particle flux anisotropies is achieved when bang time occurs significantly (on the order of 500 ps) after the trailing edge of the laser pulse. This is an important observation as the main source of the yield calibration error is due to particle anisotropies caused by field effects. The results indicate that the CR-39-nTOF in situ calibration method can serve as a valuable technique for calibrating and reducing the uncertainty in the DD absolute yield calibration of nTOF detector systems on OMEGA, the National Ignition Facility, and laser megajoule.

  18. A method for in situ absolute DD yield calibration of neutron time-of-flight detectors on OMEGA using CR-39-based proton detectors

    International Nuclear Information System (INIS)

    Waugh, C. J.; Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.; Petrasso, R. D.; Rosenberg, M. J.; Glebov, V. Yu.; Sangster, T. C.; Stoeckl, C.

    2015-01-01

    Neutron time of flight (nTOF) detectors are used routinely to measure the absolute DD neutron yield at OMEGA. To check the DD yield calibration of these detectors, originally calibrated using indium activation systems, which in turn were cross-calibrated to NOVA nTOF detectors in the early 1990s, a direct in situ calibration method using CR-39 range filter proton detectors has been successfully developed. By measuring DD neutron and proton yields from a series of exploding pusher implosions at OMEGA, a yield calibration coefficient of 1.09 ± 0.02 (relative to the previous coefficient) was determined for the 3m nTOF detector. In addition, comparison of these and other shots indicates that significant reduction in charged particle flux anisotropies is achieved when bang time occurs significantly (on the order of 500 ps) after the trailing edge of the laser pulse. This is an important observation as the main source of the yield calibration error is due to particle anisotropies caused by field effects. The results indicate that the CR-39-nTOF in situ calibration method can serve as a valuable technique for calibrating and reducing the uncertainty in the DD absolute yield calibration of nTOF detector systems on OMEGA, the National Ignition Facility, and laser megajoule

  19. Neutron energy distribution function reconstructed from time-of-flight signals in deuterium gas-puff Z-pinch

    Czech Academy of Sciences Publication Activity Database

    Klír, D.; Kravárik, J.; Kubeš, J.; Rezac, K.; Ananev, S.S.; Bakshaev, Y. L.; Blinov, P. I.; Chernenko, A. S.; Kazakov, E.D.; Korolev, V. D.; Ustroev, G. I.; Juha, Libor; Krása, Josef; Velyhan, Andriy

    2009-01-01

    Roč. 37, č. 3 (2009), s. 425-432 ISSN 0093-3813 R&D Projects: GA MŠk(CZ) LC528; GA MŠk LA08024 Grant - others:IAEA(XE) RC 14817 Institutional research plan: CEZ:AV0Z10100523 Keywords : deuterium * fusion reaction * gas puff * Monte Carlo reconstruction * neutron energy spectra * neutron s * Z-pinch Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.043, year: 2009

  20. New Insights into the Molecular Dynamics of P3HT:PCBM Bulk Heterojunction: A Time-of-Flight Quasi-Elastic Neutron Scattering Study.

    Science.gov (United States)

    Guilbert, Anne A Y; Zbiri, Mohamed; Jenart, Maud V C; Nielsen, Christian B; Nelson, Jenny

    2016-06-16

    The molecular dynamics of organic semiconductor blend layers are likely to affect the optoelectronic properties and the performance of devices such as solar cells. We study the dynamics (5-50 ps) of the poly(3-hexylthiophene) (P3HT): phenyl-C61-butyric acid methyl ester (PCBM) blend by time-of-flight quasi-elastic neutron scattering, at temperatures in the range 250-360 K, thus spanning the glass transition temperature region of the polymer and the operation temperature of an OPV device. The behavior of the QENS signal provides evidence for the vitrification of P3HT upon blending, especially above the glass transition temperature, and the plasticization of PCBM by P3HT, both dynamics occurring on the picosecond time scale.

  1. Monte Carlo Simulation of the Time-Of-Flight Technique for the Measurement of Neutron Cross-section in the Pohang Neutron Facility

    Energy Technology Data Exchange (ETDEWEB)

    An, So Hyun; Lee, Young Ouk; Lee, Cheol Woo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Young Seok [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2007-10-15

    It is essential that neutron cross sections are measured precisely for many areas of research and technique. In Korea, these experiments have been performed in the Pohang Neutron Facility (PNF) with the pulsed neutron facility based on the 100 MeV electron linear accelerator. In PNF, the neutron energy spectra have been measured for different water levels inside the moderator and compared with the results of the MCNPX calculation. The optimum size of the water moderator has been determined on the base of these results. In this study, Monte Carlo simulations for the TOF technique were performed and neutron spectra of neutrons were calculated to predict the measurements.

  2. The data acquisition system of the neutron time-of-flight facility nTOF at CERN

    CERN Document Server

    Abbondanno, U; Alvarez, F; Alvarez, H; Andriamonje, Samuel A; Andrzejewski, J; Badurek, G; Baumann, P; Becvar, F; Benlliure, J; Berthomieux, E; Betev, B; Calviño, F; Cano-Ott, D; Capote, R; Cennini, P; Chepel, V Yu; Chiaveri, Enrico; Colonna, N; Cortés, G; Cortina-Gil, D; Couture, A; Cox, J; Dababneh, S; David, S; Dolfini, R; Domingo-Pardo, C; Durán, I; Embid-Segura, M; Ferrant, L; Ferrari, A; Ferreira-Marques, R; Frais-Kölbl, H; Furman, W; Gonçalves, I; González-Romero, E M; Goverdovski, A A; Gramegna, F; Griesmayer, E; Gunsing, F; Haas, B; Haight, R; Heil, M; Herrera-Martínez, A; Isaev, S; Jericha, E; Kadi, Y; Käppeler, F K; Kerveno, M; Ketlerov, V; Köhler, P E; Konovalov, V; Krticka, M; Leeb, H; Lindote, A; Lopes, M I; Lozano, M; Lukic, S; Marganiec, J; Marrone, S; Martínez-Val, J M; Mastinu, P; Mengoni, A; Milazzo, P M; Molina-Coballes, A; Moreau, C; Mosconi, M; Neves, F; Oberhummer, Heinz; O'Brien, S; Pancin, J; Papaevangelou, T; Paradela, C; Pavlik, A; Pavlopoulos, P; Perlado, J M; Perrot, L; Peskov, Vladimir; Plag, R; Plompen, A; Plukis, A; Poch, A; Policarpo, Armando; Pretel, C; Quesada, J M; Rapp, W; Rauscher, T; Reifarth, R; Rosetti, M; Rubbia, Carlo; Rudolf, G; Rullhusen, P; Salgado, V; Schäfer, E; Soares, J C; Stephanq, C; Tagliente, G; Taín, J L; Tassan-Got, L; Tavora, L M N; Terlizzi, R; Vannini, G; Vaz, P; Ventura, A; Villamarín-Fernández, D; Vincente-Vincente, M; Vlachoudis, V; Voss, F; Wendler, H; Wiescher, M; Wisshak, K

    2005-01-01

    The n_TOF facility at CERN has been designed for the measurement of neutron capture, fission and (n, multiplied by n) cross-sections with high accuracy. This requires a flexible and - due to the high instantaneous neutron flux - almost dead time free data acquisition system. A scalable and versatile data solution has been designed based on 8-bit flash-ADCs with sampling rates up to 2 GHz and 8 Mbyte memory buffer. The software is written in C and C++ and is running on PCs equipped with RedHat Linux.

  3. Effect of high current electron beam in a 30 MeV radio frequency linac for neutron-time-of-flight applications

    Energy Technology Data Exchange (ETDEWEB)

    Nayak, B., E-mail: biswaranjan.nayak1@gmail.com; Acharya, S.; Rajawat, R. K. [Accelerator and Pulsed Power Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); DasGupta, K. [Accelerator and Pulsed Power Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Beam Technology Development Group, BARC, Mumbai 400085 (India)

    2016-01-15

    A high power pulsed radio frequency electron linac is designed by BARC, India to accelerate 30 MeV, 10 A, 10 ns beam for neutron-time-of-flight applications. It will be used as a neutron generator and will produce ∼10{sup 12}–10{sup 13} n/s. It is essential to reduce the beam instability caused by space charge effect and the beam cavity interaction. In this paper, the wakefield losses in the accelerating section due to bunch of RMS (Root mean square) length 2 mm (at the gun exit) is analysed. Loss and kick factors are numerically calculated using CST wakefield solver. Both the longitudinal and transverse wake potentials are incorporated in beam dynamics code ELEGANT to find the transverse emittance growth of the beam propagating through the linac. Beam loading effect is examined by means of numerical computation carried out in ASTRA code. Beam break up start current has been estimated at the end of the linac which arises due to deflecting modes excited by the high current beam. At the end, transverse beam dynamics of such high current beam has been analysed.

  4. Magnetic properties of nano-scale hematite, α-Fe{sub 2}O{sub 3}, studied by time-of-flight inelastic neutron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Adrian H. [The European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP220, 38043 Grenoble Cedex 9 (France); Jacobsen, Henrik, E-mail: hjacobse@fys.ku.dk; Holm, Sonja L.; Lefmann, Kim [Nanoscience Centre, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen (Denmark); Stewart, J. Ross [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 OQX (United Kingdom); Jiao, Feng [Department of Chemical Engineering, University of Delaware, Center for Catalytic Science and Technology, 150 Academy Street, Newark, Delaware 19716-3110 (United States); Jensen, Niels P. [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Mutka, Hannu; Seydel, Tilo [The Institute Laue-Langevin, 6 rue Jules Horowitz, BP156, 38042 Grenoble Cedex 9 (France); Harrison, Andrew [The Institute Laue-Langevin, 6 rue Jules Horowitz, BP156, 38042 Grenoble Cedex 9 (France); EaStCHEM, School of Chemistry and Centre for Science at Extreme Conditions, The King' s Buildings, The University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ (United Kingdom)

    2014-01-28

    Samples of nanoscale hematite, α-Fe{sub 2}O{sub 3}, with different surface geometries and properties have been studied with inelastic time-of-flight neutron scattering. The 15 nm diameter nanoparticles previously shown to have two collective magnetic excitation modes in separate triple-axis neutron scattering studies have been studied in further detail using the advantage of a large detector area, high resolution, and large energy transfer range of the IN5 TOF spectrometer. A mesoporous hematite sample has also been studied, showing similarities to that of the nanoparticle sample and bulk α-Fe{sub 2}O{sub 3}. Analysis of these modes provides temperature dependence of the magnetic anisotropy coefficient along the c-axis, κ{sub 1}. This is shown to remain negative throughout the temperature range studied in both samples, providing an explanation for the previously observed suppression of the Morin transition in the mesoporous material. The values of this anisotropy coefficient are found to lie between those of bulk and nano-particulate samples, showing the hybrid nature of the mesoporous 3-dimensional structure.

  5. Crystal structure relation between tetragonal and orthorhombic CsAlD{sub 4}: DFT and time-of-flight neutron powder diffraction studies

    Energy Technology Data Exchange (ETDEWEB)

    Bernert, Thomas; Krech, Daniel; Felderhoff, Michael; Weidenthaler, Claudia [Department of Heterogeneous Catalysis, Max-Planck-Institut fuer Kohlenforschung, Muelheim/Ruhr (Germany); Kockelmann, Winfried [Rutherford Appleton Laboratory, Harwell Oxford, Didcot (United Kingdom); Frankcombe, Terry J. [Research School of Chemistry, The Australian National University, Canberra, ACT (Australia); School of Physical, Environmental and Mathematic Sciences, The University of New South Wales, Canberra, ACT (Australia)

    2015-11-15

    The crystal structures of orthorhombic and tetragonal CsAlD{sub 4} were refined from time-of-flight neutron powder diffraction data starting from atomic positions predicted from DFT calculations. The earlier proposed crystal structure of orthorhombic CsAlH{sub 4} is confirmed. For tetragonal CsAlH{sub 4}, DFT calculations predicted a crystal structure in I4{sub 1}/amd as potential minimum structure, while from neutron diffraction studies of CsAlD{sub 4} best refinement is obtained for a disordered structure in the space group I4{sub 1}/a, with a = 5.67231(9) Aa, c = 14.2823(5) Aa. While the caesium atoms are located on the Wyckoff position 4b and aluminium at Wyckoff position 4a, there are two distinct deuterium positions at the Wyckoff position 16f with occupancies of 50 % each. From this structure, the previously reported phase transition between the orthorhombic and tetragonal polymorphs could be explained. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. ALICE Time Of Flight Detector

    CERN Multimedia

    Alici, A

    2013-01-01

    Charged particles in the intermediate momentum range are identified in ALICE by the Time Of Flight (TOF) detector. The time measurement with the TOF, in conjunction with the momentum and track length measured by the tracking detector, is used to calculate the particle mass.

  7. Calibration of scintillation-light filters for neutron time-of-flight spectrometers at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Sayre, D. B., E-mail: sayre4@llnl.gov; Barbosa, F.; Caggiano, J. A.; Eckart, M. J.; Grim, G. P.; Hartouni, E. P.; Hatarik, R. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); DiPuccio, V. N.; Weber, F. A. [National Security Technologies, Livermore, California 94551 (United States)

    2016-11-15

    Sixty-four neutral density filters constructed of metal plates with 88 apertures of varying diameter have been radiographed with a soft x-ray source and CCD camera at National Security Technologies, Livermore. An analysis of the radiographs fits the radial dependence of the apertures’ image intensities to sigmoid functions, which can describe the rapidly decreasing intensity towards the apertures’ edges. The fitted image intensities determine the relative attenuation value of each filter. Absolute attenuation values of several imaged filters, measured in situ during calibration experiments, normalize the relative quantities which are now used in analyses of neutron spectrometer data at the National Ignition Facility.

  8. Time-of-flight neutron diffraction investigation of temperature factors in the Zn blende semiconductor InP

    International Nuclear Information System (INIS)

    Ferrari, C.; Bocchi, C.; Fornari, R.; Moze, O.; Wilson, C.C.

    1992-01-01

    A structural investigation of the Zn blende structure semiconductor InP has been carried out using the single crystal diffractometer SXD at the pulsed neutron facility ISIS. The ability to measure structure factors accurately at large Q values even with highly absorbing materials such as InP is demonstrated. Measurements were performed on a single crystal of InP at 293, 100 and 50 K with the crystallographic axis mounted perpendicular to the scattering plane. This enabled collection of (hhl) reflections up to a maximum with Miller indices (10, 10, 8). (orig.)

  9. Applications of the associated-particle neutron-time-of-flight interrogation technique - From sheep to unexploded ordnance

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, S. [Environmental Sciences Department, Brookhaven National Laboratory, Upton, NY 11973 and Nuclear Forensics R and D, Sandia National Laboratories, Albuquerque, NM 87185-0968 (United States)

    2013-04-19

    The associated-particle technique (APT) will be presented for some diverse applications that include on the one hand, analyzing the body composition of live sheep and on the other, identifying the fillers of unexploded ordnance (UXO). What began with proof-of-concept studies using a large laboratory based 14 MeV neutron generator of the 'associated-particle' type, soon became possible for the first time to measure total body protein, fat and water simultaneously in live sheep using a compact field deployable associated-particle sealed-tube neutron generator (APSTNG). This non-invasive technique offered the animal physiologist a tool to monitor the growth of an animal in response to new genetic, nutritional and pharmacologic methods for livestock improvement. While measurement of carbon (C), nitrogen (N) and oxygen (O) determined protein, fat and water because of the fixed stoichiometric proportions of these elements in these body components, the unique C/N and C/O ratios of high explosives revealed their identity in UXO. The algorithm that was developed and implemented to extract C, N and O counts from an APT generated gamma-ray spectrum will be presented together with the UXO investigations that involved preliminary proofof-concept studies and modeling with Monte Carlo produced synthetic spectra of 57-155 mm projectiles.

  10. Prototyping and tests for an MRPC-based time-of-flight detector for 1 GeV neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Yakorev, D. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); Aumann, T. [GSI Helmholtz zentrum fuer Schwerionenforschung, Darmstadt (Germany); Technische Universitaet Darmstadt (Germany); Bemmerer, D., E-mail: d.bemmerer@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); Boretzky, K. [GSI Helmholtz zentrum fuer Schwerionenforschung, Darmstadt (Germany); Caesar, C. [GSI Helmholtz zentrum fuer Schwerionenforschung, Darmstadt (Germany); Technische Universitaet Darmstadt (Germany); Ciobanu, M. [GSI Helmholtz zentrum fuer Schwerionenforschung, Darmstadt (Germany); Cowan, T.; Elekes, Z. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); Elvers, M. [Universitaet zu Koeln (Germany); Gonzalez Diaz, D. [GSI Helmholtz zentrum fuer Schwerionenforschung, Darmstadt (Germany); Technische Universitaet Darmstadt (Germany); Tsinghua University, Beijing (China); Hannaske, R. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); Hehner, J.; Heil, M. [GSI Helmholtz zentrum fuer Schwerionenforschung, Darmstadt (Germany); Kempe, M. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); Maroussov, V. [Universitaet zu Koeln (Germany); Nusair, O. [GSI Helmholtz zentrum fuer Schwerionenforschung, Darmstadt (Germany); Al Balqa' Applied University, Salt (Jordan); Simon, H. [GSI Helmholtz zentrum fuer Schwerionenforschung, Darmstadt (Germany); Sobiella, M.; Stach, D.; Wagner, A. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); and others

    2011-10-21

    The NeuLAND detector at the R{sup 3}B experiment at the future FAIR facility in Darmstadt aims to detect fast neutrons (0.2-1.0 GeV) with high time and spatial resolutions ({sigma}{sub t}<100ps,{sigma}{sub x,y,z}<1cm). This task can be performed either with a scintillator or based on the multigap resistive plate chamber (MRPC) technology. Here, prototyping and test for an MRPC-based solution are discussed. In order to reach 90% detection efficiency, the final detector must consist of 50 consecutive MRPC stacks. Each stack contains a 4 mm thick anode made of iron converter material, with an additional 4 mm of converter material between two stacks. The secondary charged particles stemming from hadronic interactions of the high energetic neutrons in the converter will be detected in the MRPCs. As part of the ongoing development effort, a number of prototypes for this detector have been developed and built. They have been tested in experiments with a single-electron beam with picosecond resolution at the superconducting linac ELBE (Dresden, Germany). The results of the tests are presented here, and an outlook is given.

  11. Time-of-flight spectrometers

    International Nuclear Information System (INIS)

    Carrico, J.P.

    1976-01-01

    The flight time of an ion in an inhomogeneous, oscillatory electric field (IOFE) is an m/e-dependent property of this field and is independent of the initial position and velocity. The d.c. component of the equation of motion for an ion in the IOFE describes a harmonic oscillation of constant period. When ions oscillate for many periods with one species overtaking another the motion may no longer be truly periodic although the resulting period or 'quasi-period' still remains independent of the initial conditions. This period or 'quasi-period' is used in the time-of-flight mass spectrometer described. The principle of operation is also described and both analytical and experimental results are reported. (B.D.)

  12. ALICE Time of Flight Module

    CERN Multimedia

    The Time-Of-Flight system of ALICE consists of 90 such modules, each containing 15 or 19 Multigap Resistive Plate Chamber (MRPC) strips. This detector is used for identification of charged particles. It measures with high precision (50 ps) the time of flight of charged particles and therefore their velocity. The curvature of the particle trajectory inside the magnetic field gives the momentum, thus the particle mass is calculated and the particle is identified The MRPC is a stack of resistive glass plates, separated from each other by nylon fishing line. The mass production of the chambers (~1600, covering a surface of 150 m2) was done at INFN Bologna, while the first prototypes were bult at CERN.

  13. A novel time-to-pulse height converter for fast-neutron time-of-flight techniques

    International Nuclear Information System (INIS)

    Christiansen, J.

    1962-01-01

    An electronic time-to-pulse height converter is described which uses a multiplicative method instead of the usual one of adding overlapping pulses. This is achieved by a coincidence of a linear sawtooth and a sharply clipped needle-pulse. The sawtooth is fed to the grid of a beam-deflecting tube (E80T) and the needle-pulse is applied to the deflecting plates and opens the tube only during a time-interval of about 5.10 -9 s. The plate gets a charge proportional to the time-difference between the start of the sawtooth and the needle pulse. The plate-pulse is stretched and amplified and its height represents a measurement of the time-difference. With this method we got a time resolution of 2τ = 7 x 10 -12 s with artificial pulses, 2τ = 3 x 10 -10 s with Co 60 γ-coincidences by using NE 102 plastic crystals and 2τ = 1.4 x 10 -9 s with 511-keV γ-coincidences using NaI(Te) crystals. The method was also used with pulsed beam techniques. In this case we got from the pulsing RF an 8-Mc, sharply-peaked pulse-sequence, which was fed to the E80T plates. We had a time-resolution of 2τ = 1.1 x 10 -9 s with 4-MeV neutrons using plastic crystals 0.7 in long. Normally the region of linear response was 30 ns but it was possible to go up to 120 ns. (author) [fr

  14. Analysis methods of neutrons induced resonances in the transmission experiments by time-of-flight and automation of these methods on IBM 7094 II computer; Methode d'analyse des resonances induites par les neutrons dans les experiences de transmission par temps-de-vol et automatisation de ces methodes sur ordinateur IBM-7094 II

    Energy Technology Data Exchange (ETDEWEB)

    Corge, C

    1967-07-01

    The neutron induced resonances analysis aims to determine the neutrons characteristics, leading to the excitation energies, de-excitation probabilities by gamma radiation emission, by neutron emission or by fission, their spin, their parity... This document describes the methods developed, or adapted, the calculation schemes and the algorithms implemented to realize such analysis on a computer, from data obtained during time-of-flight experiments on the linear accelerator of Saclay. (A.L.B.)

  15. Analysis methods of neutrons induced resonances in the transmission experiments by time-of-flight and automation of these methods on IBM 7094 II computer; Methode d'analyse des resonances induites par les neutrons dans les experiences de transmission par temps-de-vol et automatisation de ces methodes sur ordinateur IBM-7094 II

    Energy Technology Data Exchange (ETDEWEB)

    Corge, C

    1967-07-01

    The neutron induced resonances analysis aims to determine the neutrons characteristics, leading to the excitation energies, de-excitation probabilities by gamma radiation emission, by neutron emission or by fission, their spin, their parity... This document describes the methods developed, or adapted, the calculation schemes and the algorithms implemented to realize such analysis on a computer, from data obtained during time-of-flight experiments on the linear accelerator of Saclay. (A.L.B.)

  16. Time and Energy Characterization of a Neutron Time of Flight Detector Using a Novel Coincidence Method for Constraining Neutron Yield, Ion Temperature and Liner Density Measurements from MagLIF Experiments

    Science.gov (United States)

    Styron, Jedediah D.

    The focus of this work is the characterization of a typical neutron time-of-flight (NTOF) detector that is fielded on inertial confinement fusion (ICF) experiments conducted at the Z-experimental facility with emphasis on the Magnetized Liner Fusion (MagLIF) concept. An NTOF detector consisting of EJ-228 scintillator and two independent photomultiplier tubes (PMTs), a Hamamatsu-mod 5 and Photek-PMT240, has been characterized in terms of the absolute time and energy response. The characterization was done by measuring single, neutron-induced events in the scintillator by measuring the alpha particle and neutron produced from the D-T reaction in kinematic coincidence. The results of these experiments provided the time dependent instrument response function and the detector sensitivity as a function of applied voltage covering the entire dynamic range of the detector. Historically, impulse response functions have been measured using various photon sources as surrogates for a neutron source. Thus, this measurement using a single hit neutron source results in the most accurate measured response function, which will improve the accuracy of impulse response corrections to the NTOF signals. While this detector has not yet been fielded on any MagLIF experiments, the development of a predictive capability was desired for transferring the measured detector response from the calibration geometry to the more complex Z geometry. As a proof-of-principle, a detailed model of the Z-machine was developed in MCNP6 to correct for geometry issues when transferring the calibration results from a light lab setting to the Z-environment. Representative values for the instrument response function and the sensitivity for the current detectors fielded on MagLIF experiments were convolved with the modeled results. These results were compared with data collected on three previous MagLIF experiments. The comparison shows the model results can be used to constrain three parameters that are

  17. Simulations and measurements of the performance of a channeled neutron guide for a time-of-flight spectrometer at the NIST Center for Neutron Research

    International Nuclear Information System (INIS)

    Cook, Jeremy C.; Copley, John R.D.

    2004-01-01

    We describe the identification and analysis of the principal sources of intensity loss within the five-channeled neutron guide tube that was originally installed in the chopper section of the Disk Chopper Spectrometer at the National Institute of Standards and Technology Center for Neutron Research. (The purpose of the five channels was to optimize intensity and resolution in three different modes of operation known as ''resolution modes.'') By combining measurements, Monte Carlo simulations, and analytical calculations, we have developed a model that successfully explains performance losses in the original guide. We have used this model to quantify expected returns in performance using a replacement guide in which the principal contributions to the intensity loss are reduced to the minimum achievable with current technology. We have also estimated the intensity gains that would be achieved if one of the limited number of options were adopted for modifying the original guide in a manner likely to produce such gains. We describe factors that affect the performance of the original guide and compare the measured and predicted performance of the modified guide against predictions for the optimal replacement guide. The simulations indicate that the modified guide (which has three channels rather than the original five) produces greater intensity gains over a large incident wavelength band for the low and medium resolution modes, whereas a high quality replacement guide greatly improves performance in the high resolution mode of operation. Because the low and medium resolution modes are most heavily demanded, we opted to modify the guide rather than replace it. We describe the nature of this modification and present intensity measurements that meet or exceed predictions in all resolution modes with no detectable change in the energy resolution nor increase in the instrumental background

  18. Contrast variation by dynamic nuclear polarization and time-of-flight small-angle neutron scattering. I. Application to industrial multi-component nanocomposites1

    Science.gov (United States)

    Noda, Yohei; Koizumi, Satoshi; Masui, Tomomi; Mashita, Ryo; Kishimoto, Hiroyuki; Yamaguchi, Daisuke; Kumada, Takayuki; Takata, Shin-ichi; Ohishi, Kazuki; Suzuki, Jun-ichi

    2016-01-01

    Dynamic nuclear polarization (DNP) at low temperature (1.2 K) and high magnetic field (3.3 T) was applied to a contrast variation study in small-angle neutron scattering (SANS) focusing on industrial rubber materials. By varying the scattering contrast by DNP, time-of-flight SANS profiles were obtained at the pulsed neutron source of the Japan Proton Accelerator Research Complex (J-PARC). The concentration of a small organic molecule, (2,2,6,6-tetramethylpiperidine-1-yl)oxy (TEMPO), was carefully controlled by a doping method using vapour sorption into the rubber specimens. With the assistance of microwave irradiation (94 GHz), almost full polarization of the paramagnetic electronic spin of TEMPO was transferred to the spin state of hydrogen (protons) in the rubber materials to obtain a high proton spin polarization (P H). The following samples were prepared: (i) a binary mixture of styrene–butadiene random copolymer (SBR) with silica particles (SBR/SP); and (ii) a ternary mixture of SBR with silica and carbon black particles (SBR/SP/CP). For the binary mixture (SBR/SP), the intensity of SANS significantly increased or decreased while keeping its q dependence for P H = −35% or P H = 40%, respectively. The q behaviour of SANS for the SBR/SP mixture can be reproduced using the form factor of a spherical particle. The intensity at low q (∼0.01 Å−1) varied as a quadratic function of P H and indicated a minimum value at P H = 30%, which can be explained by the scattering contrast between SP and SBR. The scattering intensity at high q (∼0.3 Å−1) decreased with increasing P H, which is attributed to the incoherent scattering from hydrogen. For the ternary mixture (SBR/SP/CP), the q behaviour of SANS was varied by changing P H. At P H = −35%, the scattering maxima originating from the form factor of SP prevailed, whereas at P H = 29% and P H = 38%, the scattering maxima disappeared. After decomposition of the total SANS according to inverse matrix

  19. Construction of a time-of-flight neutron spectrometer for reaction angles 000 and study of the reaction 65Cu(p,xn) 65Zn for Esub(p)=26.7 MeV

    International Nuclear Information System (INIS)

    Holler, Y.

    1984-01-01

    At the Hamburg Isochronous Cyclotron a novel time-of-flight neutron spectrometer was designed, constructed, and tested by means of a for the planned application typical nuclear reaction. The apparature was optimized for the measurement of continuous, structure-deficient neutron spectra in a wide angular range at a reproducible, as low as possible scattering neutron background. Such a facility is fitted to the strengths of the Hamburg cyclotron and allows to study questions on the precompound emission and on the inelastic projectile ( 3 He) breakup. The final test was performed with the reaction 65 Cu(p,xn) 65 Zn at Esub(p)=26.7 MeV for which already comparable data over a smaller angular range were present. In the analysis of the measurement results performed regarding the precompound effects the hybrid-exciton model calculations let recognize essential deviations at high neutron energies in the range of the extreme reaction angles. (orig./HSI) [de

  20. Magnetic excitations studied with time-of-flight spectroscopy

    International Nuclear Information System (INIS)

    Rainford, B.

    1996-01-01

    An introduction to time-of-flight neutron spectroscopy is presented in the context of the study of magnetic materials. Examples are taken from the class of rare earth and actinide magnetic materials known as 'strongly correlated electron' systems. (author) 11 figs., 24 refs

  1. Magnetic excitations studied with time-of-flight spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rainford, B [Southampton Univ. (United Kingdom). Dept. of Physics

    1996-11-01

    An introduction to time-of-flight neutron spectroscopy is presented in the context of the study of magnetic materials. Examples are taken from the class of rare earth and actinide magnetic materials known as `strongly correlated electron` systems. (author) 11 figs., 24 refs.

  2. A control and data processing system for neutron time-of-flight experiments at the Harwell linear accelerator based on a PDP-11/45 mini-computer

    International Nuclear Information System (INIS)

    Chapman, W.S.; Boyce, D.A.; Brisland, J.B.; Langman, A.E.; Morris, D.V.; Schomberg, M.G.; Webb, D.A.

    1977-05-01

    The subject is treated in sections, entitled: introduction (experimental method, need for the PDP-11/45 based system); features required in the control and data processing system; description of the selected system configuration (PDP 11/45 mini-computer and RSX-11 D operating system, the single parameter experimental stations (the CAMAC units, the time-of-flight scaler)); description of the applications software; system performance. (U.K.)

  3. Minimizing the background radiation in the new neutron time-of-flight facility at CERN FLUKA Monte Carlo simulations for the optimization of the n_TOF second experimental line

    CERN Document Server

    Bergström, Ida; Elfgren, Erik

    2013-06-11

    At the particle physics laboratory CERN in Geneva, Switzerland, the Neutron Time-of-Flight facility has recently started the construction of a second experimental line. The new neutron beam line will unavoidably induce radiation in both the experimental area and in nearby accessible areas. Computer simulations for the minimization of the background were carried out using the FLUKA Monte Carlo simulation package. The background radiation in the new experimental area needs to be kept to a minimum during measurements. This was studied with focus on the contributions from backscattering in the beam dump. The beam dump was originally designed for shielding the outside area using a block of iron covered in concrete. However, the backscattering was never studied in detail. In this thesis, the fluences (i.e. the flux integrated over time) of neutrons and photons were studied in the experimental area while the beam dump design was modified. An optimized design was obtained by stopping the fast neutrons in a high Z mat...

  4. Sample-interpolation timing: an optimized technique for the digital measurement of time of flight for γ rays and neutrons at relatively low sampling rates

    International Nuclear Information System (INIS)

    Aspinall, M D; Joyce, M J; Mackin, R O; Jarrah, Z; Boston, A J; Nolan, P J; Peyton, A J; Hawkes, N P

    2009-01-01

    A unique, digital time pick-off method, known as sample-interpolation timing (SIT) is described. This method demonstrates the possibility of improved timing resolution for the digital measurement of time of flight compared with digital replica-analogue time pick-off methods for signals sampled at relatively low rates. Three analogue timing methods have been replicated in the digital domain (leading-edge, crossover and constant-fraction timing) for pulse data sampled at 8 GSa s −1 . Events arising from the 7 Li(p, n) 7 Be reaction have been detected with an EJ-301 organic liquid scintillator and recorded with a fast digital sampling oscilloscope. Sample-interpolation timing was developed solely for the digital domain and thus performs more efficiently on digital signals compared with analogue time pick-off methods replicated digitally, especially for fast signals that are sampled at rates that current affordable and portable devices can achieve. Sample interpolation can be applied to any analogue timing method replicated digitally and thus also has the potential to exploit the generic capabilities of analogue techniques with the benefits of operating in the digital domain. A threshold in sampling rate with respect to the signal pulse width is observed beyond which further improvements in timing resolution are not attained. This advance is relevant to many applications in which time-of-flight measurement is essential

  5. The high-resolution time-of-flight spectrometer TOFTOF

    Energy Technology Data Exchange (ETDEWEB)

    Unruh, Tobias [Technische Universitaet Muenchen, Forschungsneutronenquelle Heinz Maier-Leibnitz FRM II and Physik Department E13, Lichtenbergstr. 1, 85747 Garching (Germany)], E-mail: Tobias.Unruh@frm2.tum.de; Neuhaus, Juergen; Petry, Winfried [Technische Universitaet Muenchen, Forschungsneutronenquelle Heinz Maier-Leibnitz FRM II and Physik Department E13, Lichtenbergstr. 1, 85747 Garching (Germany)

    2007-10-11

    The TOFTOF spectrometer is a multi-disc chopper time-of-flight spectrometer for cold neutrons at the research neutron source Heinz Maier-Leibnitz (FRM II). After five reactor cycles of routine operation the characteristics of the instrument are reported in this article. The spectrometer features an excellent signal to background ratio due to its remote position in the neutron guide hall, an elaborated shielding concept and an s-shaped curved primary neutron guide which acts i.a. as a neutron velocity filter. The spectrometer is fed with neutrons from the undermoderated cold neutron source of the FRM II leading to a total neutron flux of {approx}10{sup 10}n/cm{sup 2}/s in the continuous white beam at the sample position distributed over a continuous and particularly broad wavelength spectrum. A high energy resolution is achieved by the use of high speed chopper discs made of carbon-fiber-reinforced plastic. In the combination of intensity, resolution and signal to background ratio the spectrometer offers new scientific prospects in the fields of inelastic and quasielastic neutron scattering.

  6. The high-resolution time-of-flight spectrometer TOFTOF

    Science.gov (United States)

    Unruh, Tobias; Neuhaus, Jürgen; Petry, Winfried

    2007-10-01

    The TOFTOF spectrometer is a multi-disc chopper time-of-flight spectrometer for cold neutrons at the research neutron source Heinz Maier-Leibnitz (FRM II). After five reactor cycles of routine operation the characteristics of the instrument are reported in this article. The spectrometer features an excellent signal to background ratio due to its remote position in the neutron guide hall, an elaborated shielding concept and an s-shaped curved primary neutron guide which acts i.a. as a neutron velocity filter. The spectrometer is fed with neutrons from the undermoderated cold neutron source of the FRM II leading to a total neutron flux of ˜1010n/cm2/s in the continuous white beam at the sample position distributed over a continuous and particularly broad wavelength spectrum. A high energy resolution is achieved by the use of high speed chopper discs made of carbon-fiber-reinforced plastic. In the combination of intensity, resolution and signal to background ratio the spectrometer offers new scientific prospects in the fields of inelastic and quasielastic neutron scattering.

  7. Doppler time-of-flight imaging

    KAUST Repository

    Heidrich, Wolfgang; Heide, Felix; Wetzstein, Gordon; Hullin, Matthias

    2017-01-01

    Systems and methods for imaging object velocity are provided. In an embodiment, at least one Time-of-Flight camera is used to capture a signal representative of an object in motion over an exposure time. Illumination and modulation frequency

  8. Principles of time-of-flight tomography

    International Nuclear Information System (INIS)

    Campagnolo, R.; Garderet, P.; Lecomte, J.L.; Bouvier, A.; Darier, P.; Soussaline, F.

    1983-03-01

    After a short introduction to the physics of time-of-flight positron tomography, the various aspects of this technique are presented. The characteristics including data acquisition and image reconstruction system of a positron tomograph (TTV01) which uses time-of-flight information, are described. The preliminary results obtained with TTV01, such as resolution and sensitivity, as well as phantom images, are presented [fr

  9. The development of a time of flight diffractometer, FIONA

    International Nuclear Information System (INIS)

    Goodyear, A.G.; Miller, R.J.R.

    1975-11-01

    A neutron diffractometer, FIONA, has been built at AWRE in order to study structure and equation of state data of materials at high pressures and elevated temperatures. It is required that the sample should be subjected to pressures up to 60 kbar and temperatures up to 800 0 K. There is a further requirement that the diffractometer should have a multi-detector system to make the maximum use of the neutrons available from the 5 MW HERALD reactor. Both these requirements can be met by using a time of flight diffractometer. The instrument is described. (author)

  10. Development of a new time-amplitude converter with tunnel diodes for improving fast neutron spectrometry by time of flight; Realisation d'un nouveau convertisseur temps-amplitude a diodes ''tunnel'' ameliorant la spectrometrie des neutrons rapides par temps de vol

    Energy Technology Data Exchange (ETDEWEB)

    Van Zurk, R [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1963-11-15

    New time-amplitude converter with Esaki diodes, the events being preselected before analysis, allows for realizing a fast neutron spectrometer by time-of-flight with an 1.5 * 10{sup -9} s overall time resolution for {sup 12}C (n,n') at 14 MeV. (author) [French] Realisation d'un convertisseur temps-amplitude a diodes 'tunnel', avec preselection des impulsions; l'application pour un spectrometre de neutrons rapides a temps-de-vol permet d'obtenir une resolution totale en temps de 1,5 nanoseconde dans la diffusion {sup 12}C (n,n') a 14 MeV. (auteur)

  11. High-dynamic-range neutron time-of-flight detector used to infer the D(t,n){sup 4}He and D(d,n){sup 3}He reaction yield and ion temperature on OMEGA

    Energy Technology Data Exchange (ETDEWEB)

    Forrest, C. J., E-mail: cforrest@lle.rochester.edu; Glebov, V. Yu.; Goncharov, V. N.; Knauer, J. P.; Radha, P. B.; Regan, S. P.; Romanofsky, M. H.; Sangster, T. C.; Shoup, M. J.; Stoeckl, C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299 (United States)

    2016-11-15

    Upgraded microchannel-plate–based photomultiplier tubes (MCP-PMT’s) with increased stability to signal-shape linearity have been implemented on the 13.4-m neutron time-of-flight (nTOF) detector at the Omega Laser Facility. This diagnostic uses oxygenated xylene doped with diphenyloxazole C{sub 15}H{sub 11}NO + p-bis-(o-methylstyryl)-benzene (PPO + bis-MSB) wavelength shifting dyes and is coupled through four viewing ports to fast-gating MCP-PMT’s, each with a different gain to allow one to measure the light output over a dynamic range of 1 × 10{sup 6}. With these enhancements, the 13.4-m nTOF can measure the D(t,n){sup 4}He and D(d,n){sup 3}He reaction yields and average ion temperatures in a single line of sight. Once calibrated for absolute neutron sensitivity, the nTOF detectors can be used to measure the neutron yield from 1 × 10{sup 9} to 1 × 10{sup 14} and the ion temperature with an accuracy approaching 5% for both the D(t,n){sup 4}He and D(d,n){sup 3}He reactions.

  12. The use of a position sensitive detector or of a multidetector for the measurement of pole figures by neutron time-of-flight technique

    International Nuclear Information System (INIS)

    Walther, K.

    1990-01-01

    The neutron flux of even high flux reactors is weak in comparison with the quantum flux of X-ray tubes and therefore in order to decrease the expense on measuring time more and more neutron diffractometers are equipped with position sensitive detectors or multidetectors. In this paper the peculiarities of the use of such detecting devices are discussed for the measurement of pole figures. A special arrangement of a multidetector is proposed which will allow one to scan the whole pole figure by rotating the sample about only one axis and considerably will save measuring time. 4 refs.; 5 figs

  13. Thin Time-Of-Flight PET project

    CERN Multimedia

    The pre-R&D aims at designing and producing a compact and thin Time-Of-Flight PET detector device with depth of interaction measurement capability, which employs layered silicon sensors as active material, with a readout consisting of a new generation of very-low noise and very fast electronics based on SiGe Heterojunction Bipolar Transistors (HBT) components.

  14. First tests of the applicability of γ-ray imaging for background discrimination in time-of-flight neutron capture measurements

    Energy Technology Data Exchange (ETDEWEB)

    Pérez Magán, D.L.; Caballero, L. [IFIC, CSIC-Universidad de Valencia, E-46071 Valencia (Spain); Domingo-Pardo, C., E-mail: domingo@ific.uv.es [IFIC, CSIC-Universidad de Valencia, E-46071 Valencia (Spain); Agramunt-Ros, J.; Albiol, F. [IFIC, CSIC-Universidad de Valencia, E-46071 Valencia (Spain); Casanovas, A. [Institut de Tècniques Energètiques – Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, 08028 Barcelona (Spain); González, A. [Institute for Instrumentation in Molecular Imaging, I3M-CSIC 46022 Valencia (Spain); Guerrero, C.; Lerendegui-Marco, J. [Dto. de Física Atómica, Molecular y Nuclear, Universidad de Sevilla, 41012 Sevilla (Spain); Tarifeño-Saldivia, A. [IFIC, CSIC-Universidad de Valencia, E-46071 Valencia (Spain); Institut de Tècniques Energètiques – Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, 08028 Barcelona (Spain)

    2016-07-01

    In this work we explore for the first time the applicability of using γ-ray imaging in neutron capture measurements to identify and suppress spatially localized background. For this aim, a pinhole gamma camera is assembled, tested and characterized in terms of energy and spatial performance. It consists of a monolithic CeBr{sub 3} scintillating crystal coupled to a position-sensitive photomultiplier and readout through an integrated circuit AMIC2GR. The pinhole collimator is a massive carven block of lead. A series of dedicated measurements with calibrated sources and with a neutron beam incident on a {sup 197}Au sample have been carried out at n-TOF, achieving an enhancement of a factor of two in the signal-to-background ratio when selecting only those events coming from the direction of the sample.

  15. Trithallium tetraselenophosphate Tl3PSe4, and trithallium tetrathioarsenate, Tl3AsS4, by neutron time-of-flight diffraction

    International Nuclear Information System (INIS)

    Alkire, R.W.; Vergamini, P.J.; Larson, A.C.; Morosin, B.

    1984-01-01

    Room-temperature (293 K) single-crystal structure determinations of the isostructural materials Tl 3 PSe 4 and Tl 3 AsS 4 were performed at the Los Alamos National Laboratory Pulsed Neutron Facility. For Tl 3 PSe 4 : Msub(r) = 959.92, Pcmn, a = 9.276 (1), b = 11.036 (2), c = 9.058 (1) A, V = 927.27 A 3 , Z = 4, Dsub(m) = 6.87 (2), Dsub(x) = 6.876 Mg m -3 , lambdasub(neutron) = 0.5 → 5.2 A, F(000) = 252.5 fm. For Tl 3 AsS 4 : Msub(r) = 816.29, Pcmn, a = 9.084 (3), b = 10.877 (3), c = 8.877 (3) A, V = 877.11 A 3 , Z = 4, Dsub(m) = 6.18 (2), Dsub(x) = 6.181 Mg m -3 , lambdasub(neutron) = 0.5 → 5.2 A, F(000) = 177.2 fm. For Tl 3 PSe 4 (Tl 3 AsS 4 ), 1929 (1013) reflections were measured with I > 3sigma(I) and refined by full-matrix least squares to R(F) = 0.061 (0.063). Results on atomic refinement from this study represent an order of magnitude increase in precision over previous single-crystal X-ray structural work using Mo Kα radiation. The PSe 4 3- (AsS 4 3- ) groups have essentially tetrahedral configurations and one Tl + ion shows large anisotropic thermal motion which is structure related. (Auth.)

  16. In situ time-of-flight neutron imaging of NiO-YSZ anode support reduction under influence of stress

    DEFF Research Database (Denmark)

    Makowska, Malgorzata Grazyna; Strobl, Markus; Lauridsen, Erik M.

    2016-01-01

    This article reports on in situ macroscopic scale imaging of NiO-YSZ (YSZ is yttria-stabilized zirconia) reduction under applied stress - a phase transition taking place in solid oxide electrochemical cells in a reducing atmosphere of a hydrogen/nitrogen mixture and at operation temperatures of u...... of applying energy-resolved neutron imaging with both approaches to the NiO-YSZ reduction investigation indicate enhancement of the reduction rate due to applied stress, which is consistent with the results of the authors’ previous research....

  17. The ARGUS time-of-flight system

    International Nuclear Information System (INIS)

    Heller, R.; Klinger, T.; Salomon, R.; Schubert, K.R.; Stiewe, J.; Waldi, R.; Weseler, S.

    1985-01-01

    The time-of-flight system of the ARGUS detector at the DORIS e + e - storage ring consists of 64 barrel scintillation counters covering 75% of 4π, and 2x48 end cap counters, covering 17% of 4π. The barrel counters are viewed by two phototubes each, while the end cap counters have one tube only. The time-of-flight system serves as a part of the fast trigger and identifies charged particles. The time resolution achieved during the first year of ARGUS operation is 210 ps for Bhabhas (which are used for the off-line monitoring of the system), and 220 ps for hadrons, both in barrel and end cap counters. This converts into a three standard deviation mass separation up to 700 MeV/c between pions and kaons and 1200 MeV/c between kaons and protons. Electrons can be separated from heavier particles up to 230 MeV/c. (orig.)

  18. SHMS Hodoscopes and Time of Flight System

    Science.gov (United States)

    Craycraft, Kayla; Malace, Simona

    2017-09-01

    As part of the Thomas Jefferson National Accelerator Facility's (Jefferson Lab) upgrade from 6 GeV to 12 GeV, a new magnetic focusing spectrometer, the Super High Momentum Spectrometer (SHMS), was installed in experimental Hall C. The detector stack consists of horizontal drift chambers for tracking, gas Cerenkov and Aerogel detectors and a lead glass calorimeter for particle identification. A hodoscope system consisting of three planes of scintillator detectors (constructed by James Madison University) and one plane of quartz bars (built by North Carolina A&T State University) is used for triggering and time of flight measurements. This presentation consists of discussion of the installation, calibration, and characterization of the detectors used in this Time of Flight system. James Madison University, North Carolina A&T State University.

  19. IPNS time-of-flight single crystal diffractometer

    International Nuclear Information System (INIS)

    Schultz, A.J.; Teller, R.G.; Williams, J.M.

    1983-01-01

    The single crystal diffractometer (SCD) at the Argonne Intense Pulsed Neutron Source (IPNS) utilizes the time-of-flight (TOF) Laue technique to provide a three-dimensional sampling of reciprocal space during each pulse. The instrument contains a unique neutron position-sensitive 6 Li-glass scintillation detector with an active area of 30 x 30 cm. The three-dimensional nature of the data is very useful for fast, efficient measurement of Bragg intensities and for the studies of superlattice and diffuse scattering. The instrument was designed to achieve a resolution of 2% or better (R = δQ/Q) with 2 THETA > 60 0 and lambda > 0.7A

  20. The TORCH time-of-flight detector

    Energy Technology Data Exchange (ETDEWEB)

    Harnew, N., E-mail: Neville.Harnew@physics.ox.ac.uk [University of Oxford, Denys Wilkinson Building, 1 Keble Road, Oxford OX1 3RH (United Kingdom); Brook, N. [University College London, Department of Physics & Astronomy, Gower Street, London WC1E 6BT (United Kingdom); Castillo García, L. [CERN, PH Department, CH-1211 Geneva 23 (Switzerland); Laboratory for High Energy Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Cussans, D. [H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom); Föhl, K.; Forty, R.; Frei, C. [CERN, PH Department, CH-1211 Geneva 23 (Switzerland); Gao, R. [University of Oxford, Denys Wilkinson Building, 1 Keble Road, Oxford OX1 3RH (United Kingdom); Gys, T.; Piedigrossi, D. [CERN, PH Department, CH-1211 Geneva 23 (Switzerland); Rademacker, J.; Ros Garcia, A.; Dijk, M. van [H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom)

    2016-07-11

    The TORCH time-of-flight detector is being developed to provide particle identification between 2 and 10 GeV/c momentum over a flight distance of 10 m. TORCH is designed for large-area coverage, up to 30 m{sup 2}, and has a DIRC-like construction. The goal is to achieve a 15 ps time-of-flight resolution per incident particle by combining arrival times from multiple Cherenkov photons produced within quartz radiator plates of 10 mm thickness. A four-year R&D programme is underway with an industrial partner (Photek, UK) to produce 53×53 mm{sup 2} Micro-Channel Plate (MCP) detectors for the TORCH application. The MCP-PMT will provide a timing accuracy of 40 ps per photon and it will have a lifetime of up to at least 5 Ccm{sup −2} of integrated anode charge by utilizing an Atomic Layer Deposition (ALD) coating. The MCP will be read out using charge division with customised electronics incorporating the NINO chipset. Laboratory results on prototype MCPs are presented. The construction of a prototype TORCH module and its simulated performance are also described.

  1. Double time-of-flight fast neutron spectrometry and study of the reaction Be{sup 9}(n,2n); Spectrometrie de neutrons rapides a double temps de vol et etude de la reaction Be{sup 9}(n,2n)

    Energy Technology Data Exchange (ETDEWEB)

    Gondrand, J C [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1964-10-01

    The interaction between 14,5 MeV neutrons and Be{sup 9} was studied by a double time-of-flight method. The energy E{sub 1} and E{sub 2} of the (n,2n) reaction was measured (over all resolution 2 ns, flight path 1,50 m), the two neutrons being in the same plane with incident neutron and the scattering angle 30 degrees (angular resolution 3 degrees): 310 (n,2n) events were identified by electronic method (with photographic control) and by the kinematics (430 'back-ground' events, 1.3*10{sup 11} incident neutrons, one (n,2n) event per hour) corresponding principally (> 90 per cent) to the formation of resonant states between 4 particles (2 {alpha} and 2 neutrons) of the final state: Be{sup 8}(0) {sigma} {approx_equal} 170 mb, Be{sup 8*} (2,9 MeV) {sigma} {approx_equal} 165 mb, Be{sup 9*} (6,76 MeV) Be{sup 8}(0) {sigma} {approx_equal} 95 mb. (author) [French] La reaction Be{sup 9}(n,2n) a ete etudiee avec des neutrons de 14,5 MeV. On a mesure simultanement l'energie E{sub 1} et E{sub 2} par deux temps-de-vol (base-de-vol 1,50 m, resolution totale 2 ns), les deux neutrons etant dans le meme plan de diffusion et a 30 degres du neutron incident (resolution angulaire 3): 310 evenements (n,2n) ont ete identifies a l'aide de criteres electroniques (controles par methode photographique) et de criteres cinematiques (430 evenements parasites et fortuits, 1,3.10{sup 11} neutrons incidents, un evenement reel par heure) et sont principalement (> 90 pour cent) groupes en amas dans un diagramme type Dalitz (plan E{sub 1} E{sub 2}) correspondant aux etats resonnants: Be{sup 8}(0) {sigma} {approx_equal} 170 mb, Be{sup 8*} (2,9 MeV) {sigma} {approx_equal} 165 mb, Be{sup 9*} (6,76 MeV) Be{sup 8}(0) {sigma} {approx_equal} 95 mb.

  2. Neutron capture studies with a short flight path

    Science.gov (United States)

    Walter, Stephan; Heil, Michael; Käppeler, Franz; Plag, Ralf; Reifarth, René

    The time of flight (TOF) method is an important tool for the experimental determination of neu- tron capture cross sections which are needed for s-process nucleosynthesis in general, and for analyses of branchings in the s-process reaction path in particular. So far, sample masses of at least several milligrams are required to compensate limitations in the currently available neutron fluxes. This constraint leads to unacceptable backgrounds for most of the relevant unstable branch point nuclei, due to the decay activity of the sample. A possible solution has been proposed by the NCAP project at the University of Frankfurt. A first step in this direction is reported here, which aims at enhancing the sensitivity of the Karlsruhe TOF array by reducing the neutron flight path to only a few centimeters. Though sample masses in the microgram regime can be used by this approach, the increase in neutron flux has to be paid by a higher background from the prompt flash related to neutron production. Test measurements with Au samples are reported.

  3. Analysis of resonances due to 'S' neutrons in experiments on transmission by time-of-flight. 1. without the interference term; Analyse des resonances dues aux neutrons 'S' dans les experiences de transmission par temps de vol. 1. sans terme d'interference

    Energy Technology Data Exchange (ETDEWEB)

    Corge, C R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    Various methods of transmission resonance analysis for 's' wave neutrons in time of flight experiments are described in this report. Only the case when the interference term can be neglected is treated in this first part. Results are given relative to a more complete partial area method and also to a new method so-called the width at half depth method. (author) [French] Le present rapport est consacre a l'expose de differentes methodes d'analyse des resonances dues aux neutrons d'ondes 's' dans les experiences de transmission par temps de vol, cette premiere partie traitant uniquement le cas ou l'on peut negliger le terme d'interference. Y figurent en particulier sous forme de reseaux de courbes, les resultats relatifs a une methode des aires partielles amelioree et ceux relatifs a une nouvelle methode dite de la largeur a mi-profondeur. (auteur)

  4. Polarisation analysis on the LET time-of-flight spectrometer

    Science.gov (United States)

    Nilsen, G. J.; Košata, J.; Devonport, M.; Galsworthy, P.; Bewley, R. I.; Voneshen, D. J.; Dalgliesh, R.; Stewart, J. R.

    2017-06-01

    We present a design for implementing uniaxial polarisation analysis on the LET cold neutron time-of-flight spectrometer, installed on the second target station at ISIS. The polarised neutron beam is to be produced by a transmission-based supermirror polariser with the polarising mirrors arranged in a “double-V” formation. This will be followed by a Mezei-type precession coil spin flipper, selected for its small spatial requirements, as well as a permanent magnet guide field to transport the beam polarisation to the sample position. The sample area will contain a set of holding field coils, whose purpose is to produce a highly homogenous magnetic field for the wide-angle 3He analyser cell. To facilitate fast cell changes and reduce the risk of cell failure, we intend to separate the cell and cryostat from the vacuum of the sample tank by installing both in a vessel at atmospheric pressure. When the instrument upgrade is complete, the performance of LET is expected to be commensurate with existing and planned polarised cold neutron spectrometers at other sources. Finally, we discuss the implications of performing uniaxial polarisation analysis only, and identify quasi-elastic neutron scattering (QENS) on ionic conducting materials as an interesting area to apply the technique.

  5. Time of flight Laue fiber diffraction studies of perdeuterated DNA

    Energy Technology Data Exchange (ETDEWEB)

    Forsyth, V.T.; Whalley, M.A.; Mahendrasingam, A.; Fuller, W. [Keele Univ. (United Kingdom)] [and others

    1994-12-31

    The diffractometer SXD at the Rutherford Appleton Laboratory ISIS pulsed neutron source has been used to record high resolution time-of-flight Laue fiber diffraction data from DNA. These experiments, which are the first of their kind, were undertaken using fibers of DNA in the A conformation and prepared using deuterated DNA in order to minimis incoherent background scattering. These studies complement previous experiments on instrument D19 at the Institute Laue Langevin using monochromatic neutrons. Sample preparation involved drawing large numbers of these deuterated DNA fibers and mounting them in a parallel array. The strategy of data collection is discussed in terms of camera design, sample environment and data collection. The methods used to correct the recorded time-of-flight data and map it into the final reciprocal space fiber diffraction dataset are also discussed. Difference Fourier maps showing the distribution of water around A-DNA calculated on the basis of these data are compared with results obtained using data recorded from hydrogenated A-DNA on D19. Since the methods used for sample preparation, data collection and data processing are fundamentally different for the monochromatic and Laue techniques, the results of these experiments also afford a valuable opportunity to independently test the data reduction and analysis techniques used in the two methods.

  6. Time-of-flight mass spectrometer

    International Nuclear Information System (INIS)

    Ivanov, M.A.; Kozlov, B.N.; Mamyrin, B.A.; Shmikk, D.V.; Shebelin, V.G.

    1981-01-01

    A time-of-flight mass spectrometer containing a pulsed ion source with an electron gun and two electrodes limiting ionization range, drift space and ion acceptor, is described. To expand functional possibilities, a slot collimator of the gas stream, two quantum generators and two diaphragms for the inlet of quantum generator radiation located on both sides of the ion source, are introduced in the ion source. The above invention enables to study details of the complex interaction process of laser radiation with molecules of the gas stream, which is actual for laser isotope separation

  7. Doppler time-of-flight imaging

    KAUST Repository

    Heide, Felix

    2015-07-30

    Over the last few years, depth cameras have become increasingly popular for a range of applications, including human-computer interaction and gaming, augmented reality, machine vision, and medical imaging. Many of the commercially-available devices use the time-of-flight principle, where active illumination is temporally coded and analyzed on the camera to estimate a per-pixel depth map of the scene. In this paper, we propose a fundamentally new imaging modality for all time-of-flight (ToF) cameras: per-pixel velocity measurement. The proposed technique exploits the Doppler effect of objects in motion, which shifts the temporal frequency of the illumination before it reaches the camera. Using carefully coded illumination and modulation frequencies of the ToF camera, object velocities directly map to measured pixel intensities. We show that a slight modification of our imaging system allows for color, depth, and velocity information to be captured simultaneously. Combining the optical flow computed on the RGB frames with the measured metric axial velocity allows us to further estimate the full 3D metric velocity field of the scene. We believe that the proposed technique has applications in many computer graphics and vision problems, for example motion tracking, segmentation, recognition, and motion deblurring.

  8. ATLAS - analysis of time-of-flight diffraction data from liquid and amorphous samples

    International Nuclear Information System (INIS)

    Soper, A.K.; Howells, W.S.; Hannon, A.C.

    1989-05-01

    The purpose of this manual is to describe a package of data analysis routines which have been developed at the Rutherford Appleton Laboratory for the analysis of time-of-flight diffraction data from liquids, gases, and amorphous materials. There is no fundamental barrier to diffraction data being accurately analysed to structure factor or even pair correlation function within a very short time of the completion of the experiment. Section 1 describes the time-of-flight neutron diffraction experiment and looks at diffraction theory. Section 2 indicates the steps in data analysis of time-of-flight diffraction data and Section 3 gives details of how to run the procedures. (author)

  9. Doppler time-of-flight imaging

    KAUST Repository

    Heidrich, Wolfgang

    2017-02-16

    Systems and methods for imaging object velocity are provided. In an embodiment, at least one Time-of-Flight camera is used to capture a signal representative of an object in motion over an exposure time. Illumination and modulation frequency of the captured motion are coded within the exposure time. A change of illumination frequency is mapped to measured pixel intensities of the captured motion within the exposure time, and information about a Doppler shift in the illumination frequency is extracted to obtain a measurement of instantaneous per pixel velocity of the object in motion. The radial velocity information of the object in motion can be simultaneously captured for each pixel captured within the exposure time. In one or more aspects, the illumination frequency can be coded orthogonal to the modulation frequency of the captured motion. The change of illumination frequency can correspond to radial object velocity.

  10. Time of flight spectroscopy with muonic hydrogen

    International Nuclear Information System (INIS)

    Marshall, G.M.; Bailey, J.M.; Beer, G.A.

    1993-01-01

    Time of flight techniques coupled with muonic deuterium and tritium atoms in vacuum can be used to measure parameters important in the understanding of muon catalyzed fusion interactions. Muonic deuterium atomic beams with energy of order 1 eV have been produced via transfer and emission from solid hydrogen containing small deuterium concentrations. Measurements of energy loss in pure deuterium are presented which test calculations of σ μd+D . Muonic tritium beams should be produced in a similar way, with an energy distribution which overlaps the predicted muonic molecular (dμt) formation resonances. The existence of resonances is crucial for high cycling rates in muon catalyzed fusion, but direct experimental verification of strengths and energies is not yet possible by other means. Results of simulations demonstrate how the resonance structure might be confirmed

  11. Time-of-flight experiments using a pseudo-statistical chopper

    International Nuclear Information System (INIS)

    Aizawa, Otohiko; Kanda, Keiji

    1975-01-01

    A ''pseudo-statistical'' chopper was manufactured and used for the experiments on neutron transmission and scattering. The characteristics of the chopper and the experimental results are discussed in comparison with those in the time-of-flight technique using a conventional chopper. Which of the two methods is superior depends on the form of the time-of-flight distribution to be measured. Pseudo-statistical pulsing may be especially advantageous for scattering experiments with single or a few-line time-of-flight spectrum. (auth.)

  12. Measurement of fast assembly spectra using time-of-flight method

    International Nuclear Information System (INIS)

    Duquesne, Henry; Rotival, Michel; Schmitt, Andre; Allard, Christian; De Keyser, Albert; Hortsmann, Henri

    1975-07-01

    Measurement of neutron spectra made in fast subcritical assemblies HUG 3 and PHUG 3 (uranium-graphite and plutonium-graphite) utilizing time-of-flight techniques are described. The matrix were excited by the pulsed neutron source from the BCMN Linac beam impinging on a target of natural uranium. Details of the experimental procedure, safety studies, detector calibration and data reduction are given [fr

  13. Assessing and minimizing contamination in time of flight based validation data

    Science.gov (United States)

    Lennox, Kristin P.; Rosenfield, Paul; Blair, Brenton; Kaplan, Alan; Ruz, Jaime; Glenn, Andrew; Wurtz, Ronald

    2017-10-01

    Time of flight experiments are the gold standard method for generating labeled training and testing data for the neutron/gamma pulse shape discrimination problem. As the popularity of supervised classification methods increases in this field, there will also be increasing reliance on time of flight data for algorithm development and evaluation. However, time of flight experiments are subject to various sources of contamination that lead to neutron and gamma pulses being mislabeled. Such labeling errors have a detrimental effect on classification algorithm training and testing, and should therefore be minimized. This paper presents a method for identifying minimally contaminated data sets from time of flight experiments and estimating the residual contamination rate. This method leverages statistical models describing neutron and gamma travel time distributions and is easily implemented using existing statistical software. The method produces a set of optimal intervals that balance the trade-off between interval size and nuisance particle contamination, and its use is demonstrated on a time of flight data set for Cf-252. The particular properties of the optimal intervals for the demonstration data are explored in detail.

  14. A transistorized 1024-channel neutron time-of-flight analyser; Selecteur transistorise de temps de vol pour neutrons, a 1024 canaux; Nejtronnyj analizator vremeni proleta s 1024 kanalami i s perevodom skhemy na tranzistory; Aparato transistorizado de 1024 canales para analizar tiempos de vuelo de neutrones

    Energy Technology Data Exchange (ETDEWEB)

    Giannelli, G [European Atomic Energy Community, CCR, Ispra (Italy)

    1962-04-15

    A transistorized 1024-channel neutron time-of-flight analyser is described. This instrument has been divided in two fully independent parts: the analogue-to-digital converter (ADC) that measures the time-of-flight and the 1024-channel ferrite-core memory. In this way the output signals coming from the ADC can be recorded on a magnetic tape together with the output from other ADCs which measure other physical quantities related to the same nuclear event, with an overall number of channels higher than the capacity of the memory. The AD converter is provided with a temporary memory that, by its regularizing action on the signals rate, (1) when the AD converter, directly connected to the 1024-channel memory, allows a dead time of only 0.5 {mu}s, and (2) when the AD converter drives a magnetic tape recorder and allows a better utilization of the magnetic tape itself. The temporary memory has a capacity of four numbers of up to sixteen bits. The channel-width of the analyser is variable from 0.5 up to 48 {mu}s. The 1024 channels can be divided in two contemporary groups of 512, each connected to two detectors. The temporary memory allows contemporary recordings of signals into the two groups. The channels can also be subdivided over the time-of-flight in two groups of which the first (of 16 channels) is used to record the true zero time of the time-of-flight, while the second group can be set in any position over the total time-of-flight interval. The number of channels used in the recording of the time-of-flight can be reduced in order to record another quantity with 1024 overall channels. The logical design of the instrument is described. In the design advantage has been taken of the possibilities offered by the transistorization and the related mechanical construction systems in order to produce a most flexible instrument and one in which future modifications or extensions, which may be required by the experimenters, are feasible. (author) [French] L'auteur decrit un

  15. Numerical analysis of resonances induced by s wave neutrons in transmission time-of-flight experiments with a computer IBM 7094 II; Methodes d'analyse des resonances induites par les neutrons s dans les experiences de transmission par temps de vol et automatisation de ces methodes sur ordinateur IBM 7094 II

    Energy Technology Data Exchange (ETDEWEB)

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

    1969-01-01

    Numerical analysis of transmission resonances induced by s wave neutrons in time-of-flight experiments can be achieved in a fairly automatic way on an IBM 7094/II computer. The involved computations are carried out following a four step scheme: 1 - experimental raw data are processed to obtain the resonant transmissions, 2 - values of experimental quantities for each resonance are derived from the above transmissions, 3 - resonance parameters are determined using a least square method to solve the over determined system obtained by equalling theoretical functions to the correspondent experimental values. Four analysis methods are gathered in the same code, 4 - graphical control of the results is performed. (author) [French] L'automatisation, sur ordinateur IBM 7094/II, de l'analyse des resonances induites par les neutrons s dans les experiences de transmission par temps de vol a ete accomplie en la decomposant selon un schema articule en quatre phases: 1 - le traitement des donnees experimentales brutes pour obtenir les transmissions interfero-resonnantes, 2 - la determination des grandeurs d'analyse a partir des transmissions precedentes, 3 - l'analyse proprement dite des resonances dont les parametres sont obtenus par la resolution d'un systeme surabondant. Quatre methodes d'analyse sont groupees en un meme programme, 4 - la procedure de verification graphique. (auteur)

  16. Numerical analysis of resonances induced by s wave neutrons in transmission time-of-flight experiments with a computer IBM 7094 II; Methodes d'analyse des resonances induites par les neutrons s dans les experiences de transmission par temps de vol et automatisation de ces methodes sur ordinateur IBM 7094 II

    Energy Technology Data Exchange (ETDEWEB)

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

    1969-01-01

    Numerical analysis of transmission resonances induced by s wave neutrons in time-of-flight experiments can be achieved in a fairly automatic way on an IBM 7094/II computer. The involved computations are carried out following a four step scheme: 1 - experimental raw data are processed to obtain the resonant transmissions, 2 - values of experimental quantities for each resonance are derived from the above transmissions, 3 - resonance parameters are determined using a least square method to solve the over determined system obtained by equalling theoretical functions to the correspondent experimental values. Four analysis methods are gathered in the same code, 4 - graphical control of the results is performed. (author) [French] L'automatisation, sur ordinateur IBM 7094/II, de l'analyse des resonances induites par les neutrons s dans les experiences de transmission par temps de vol a ete accomplie en la decomposant selon un schema articule en quatre phases: 1 - le traitement des donnees experimentales brutes pour obtenir les transmissions interfero-resonnantes, 2 - la determination des grandeurs d'analyse a partir des transmissions precedentes, 3 - l'analyse proprement dite des resonances dont les parametres sont obtenus par la resolution d'un systeme surabondant. Quatre methodes d'analyse sont groupees en un meme programme, 4 - la procedure de verification graphique. (auteur)

  17. Method for determining thermal neutron decay times of earth formations

    International Nuclear Information System (INIS)

    Arnold, D.M.

    1976-01-01

    A method is disclosed for measuring the thermal neutron decay time of earth formations in the vicinity of a well borehole. A harmonically intensity modulated source of fast neutrons is used to irradiate the earth formations with fast neutrons at three different intensity modulation frequencies. The tangents of the relative phase angles of the fast neutrons and the resulting thermal neutrons at each of the three frequencies of modulation are measured. First and second approximations to the earth formation thermal neutron decay time are derived from the three tangent measurements. These approximations are then combined to derive a value for the true earth formation thermal neutron decay time

  18. On the use of the cold time-of-flight spectrometer in Studsvik for liquid 3He measurements

    International Nuclear Information System (INIS)

    Faak, Bjoern.

    1989-01-01

    The time-of-flight spectrometer for cold neutrons at the R2 reactor in Studsvik has been reconstructed. The design and the performance of the instrument are briefly described. Improvements required for measurement of the neutron scattering function of liquid 3 He are discussed. (author)

  19. Contribution to the study of the interaction of slow neutrons with {sup 235}U using the time-of-flight method; Contribution a l'etude par la methode du temps de vol de l'interaction de neutrons lents avec l'U{sup 235}

    Energy Technology Data Exchange (ETDEWEB)

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

    1964-05-15

    This study concerns the properties of the excited levels of uranium 236 obtained by interaction of slow neutron with uranium 235. The experiments have been carried out at the Saclay linear electron accelerator by use of the time of flight method. In the first part of this paper, we examine the technical and physical conditions which rule the experiments: compromise between resolution and counting rate, time dispersion due to the slowing down of the neutrons and crystalline binding effects. In a second part the experimental results i.e. total, fission and ternary fission cross sections are given. The third part deals with the analysis of these results: the resonance parameters determination ({tau}{sub n}, {tau}{sub {gamma}}, {tau}{sub f}), the study of their statistical distribution and of their correlations. We tried some classifications of the resonances according to their parameters and compared these classifications to each other and to other results. At least the evidence of a cross section correlation with a range smaller than 100 eV seems to be confirmed. (author) [French] Cette etude porte sur les proprietes des niveaux excites de l'Uranium-236 obtenus par l'interaction de neutrons lents avec le {sup 235}U. La technique experimentale est celle de la spectrometrie par temps de vol, les experiences ayant ete realisees aupres de l'accelerateur lineaire d'electrons de Saclay, Dans une premiere partie nous examinons les donnees techniques et physiques conditionnant les experiences: compromis entre resolution et taux de comptage, dispersion en temps due au ralentissement des neutrons, effet des liaisons cristallines. Dans une deuxieme partie sont exposes les resultats experimentaux: sections efficaces totales, de fission et de fission ternaire du {sup 235}U. Une troisieme partie porte sur l'analyse de ces resultats: determination des parametres ({tau}{sub n}, {tau}{sub {gamma}}, {tau}{sub f}), etude de leurs distributions statistiques et des correlations entre ces

  20. Contribution to the study of the interaction of slow neutrons with {sup 235}U using the time-of-flight method; Contribution a l'etude par la methode du temps de vol de l'interaction de neutrons lents avec l'U{sup 235}

    Energy Technology Data Exchange (ETDEWEB)

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

    1964-05-15

    This study concerns the properties of the excited levels of uranium 236 obtained by interaction of slow neutron with uranium 235. The experiments have been carried out at the Saclay linear electron accelerator by use of the time of flight method. In the first part of this paper, we examine the technical and physical conditions which rule the experiments: compromise between resolution and counting rate, time dispersion due to the slowing down of the neutrons and crystalline binding effects. In a second part the experimental results i.e. total, fission and ternary fission cross sections are given. The third part deals with the analysis of these results: the resonance parameters determination ({tau}{sub n}, {tau}{sub {gamma}}, {tau}{sub f}), the study of their statistical distribution and of their correlations. We tried some classifications of the resonances according to their parameters and compared these classifications to each other and to other results. At least the evidence of a cross section correlation with a range smaller than 100 eV seems to be confirmed. (author) [French] Cette etude porte sur les proprietes des niveaux excites de l'Uranium-236 obtenus par l'interaction de neutrons lents avec le {sup 235}U. La technique experimentale est celle de la spectrometrie par temps de vol, les experiences ayant ete realisees aupres de l'accelerateur lineaire d'electrons de Saclay, Dans une premiere partie nous examinons les donnees techniques et physiques conditionnant les experiences: compromis entre resolution et taux de comptage, dispersion en temps due au ralentissement des neutrons, effet des liaisons cristallines. Dans une deuxieme partie sont exposes les resultats experimentaux: sections efficaces totales, de fission et de fission ternaire du {sup 235}U. Une troisieme partie porte sur l'analyse de ces resultats: determination des parametres ({tau}{sub n}, {tau}{sub {gamma}}, {tau}{sub f}), etude de leurs distributions statistiques et

  1. Integrated intensities in inverse time-of-flight technique

    International Nuclear Information System (INIS)

    Dorner, Bruno

    2006-01-01

    In traditional data analysis a model function, convoluted with the resolution, is fitted to the measured data. In case that integrated intensities of signals are of main interest, one can use an approach which does not require a model function for the signal nor detailed knowledge of the resolution. For inverse TOF technique, this approach consists of two steps: (i) Normalisation of the measured spectrum with the help of a monitor, with 1/k sensitivity, which is positioned in front of the sample. This means at the same time a conversion of the data from time of flight to energy transfer. (ii) A Jacobian [I. Waller, P.O. Froeman, Ark. Phys. 4 (1952) 183] transforms data collected at constant scattering angle into data as if measured at constant momentum transfer Q. This Jacobian works correctly for signals which have a constant width at different Q along the trajectory of constant scattering angle. The approach has been tested on spectra of Compton scattering with neutrons, having epithermal energies, obtained on the inverse TOF spectrometer VESUVIO/ISIS. In this case the width of the signal is increasing proportional to Q and in consequence the application of the Jacobian leads to integrated intensities slightly too high. The resulting integrated intensities agree very well with results derived in the traditional way. Thus this completely different approach confirms the observation that signals from recoil by H-atoms at large momentum transfers are weaker than expected

  2. Neutron radiography of aircraft composite flight control surfaces

    International Nuclear Information System (INIS)

    Lewis, W.J.; Bennett, L.G.I.; Chalovich, T.R.; Francescone, O.

    2001-01-01

    A small (20 kWth), safe, pool-type nuclear research reactor called the SLOWPOKE-2 is located at the Royal Military College of Canada (RMC). The reactor was originally installed for teaching, training, research and semi-routine analysis, specifically, neutron activation analysis. It was envisioned that the neutrons from the SLOWPOKE-2 could also be used for neutron radiography, and so a research program was initiated to develop this technology. Over a period of approximately 15 years, and through a series of successive modifications, a neutron radiography system (NRS) was developed. Once completed, several applications of the technology have been demonstrated, including the nondestructive examination of the composite flight control surfaces from the Canadian Air Force's primary jet fighter, the CF18 Hornet aircraft. An initial trial was setup to investigate the flight control surfaces of 3 aircraft, to determine the parameters for a final licensed system, and to compare the results to other nondestructive methods. Over 500 neutron radiographs were made for these first 3 aircraft, and moisture and corrosion were discovered in the honeycomb structure and hydration was found in the composite and adhesive layers. In comparison with other NDT methods, neutron radiography was the only method that could detect the small areas of corrosion and moisture entrapment. However, before examining an additional 7 aircraft, the recommended modifications to the NRS were undertaken. These modifications were necessary to accommodate the larger flight control surfaces safely by incorporating flexible conformable shielding. As well, to expedite inspections so that all flight control surfaces from one aircraft could be completed in less than two weeks, there was a need to decrease the exposure time by both faster film/conversion screen combinations and by incorporating the capability of near realtime, digital radioscopy. Finally, as there are no inspection specific image quality

  3. Material Classification Using Raw Time-of-Flight Measurements

    KAUST Repository

    Su, Shuochen; Heide, Felix; Swanson, Robin J.; Klein, Jonathan; Callenberg, Clara; Hullin, Matthias; Heidrich, Wolfgang

    2016-01-01

    We propose a material classification method using raw time-of-flight (ToF) measurements. ToF cameras capture the correlation between a reference signal and the temporal response of material to incident illumination. Such measurements encode unique

  4. A time of flight detector for high energy heavy particles

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Z; O` Connor, D J [Newcastle Univ., NSW (Australia). Dept. of Physics

    1994-12-31

    As a commonly used method to measure the energy of a particle with known mass, the flight time of the particle travelling over a certain distance is measured. A detector based on this principle is called a time-of-flight (TOF) detector which has attracted interests constantly during the last 15 years. For high energy heavy particle energy detection, TOF detector is an appropriated choice and such a system, developed recently, is described in this paper. 8 refs., 3 figs.

  5. A time of flight detector for high energy heavy particles

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Z.; O`Connor, D.J. [Newcastle Univ., NSW (Australia). Dept. of Physics

    1993-12-31

    As a commonly used method to measure the energy of a particle with known mass, the flight time of the particle travelling over a certain distance is measured. A detector based on this principle is called a time-of-flight (TOF) detector which has attracted interests constantly during the last 15 years. For high energy heavy particle energy detection, TOF detector is an appropriated choice and such a system, developed recently, is described in this paper. 8 refs., 3 figs.

  6. Monte Carlo study of the performance of a time-of-flight multichopper spectrometer

    International Nuclear Information System (INIS)

    Daemen, L.L.; Eckert, J.; Pynn, R.

    1995-01-01

    The Monte Carlo method is a powerful technique for neutron transport studies. While it has been applied for many years to the study of nuclear systems, there are few codes available for neutron transport in the optical regime. The recent surge of interest in so-called next generation spallation neutron sources and the desire to design new and optimized instruments for these facilities has led us to develop a Monte Carlo code geared toward the simulation of neutron scattering instruments. The time-of-flight multichopper spectrometer, of which IN5 at the ILL is the prototypical example, is the first spectrometer studied with the code. Some of the results of a comparison between the IN5 performance at a reactor and at a Long Pulse Spallation Source (LPSS) are summarized here

  7. Contribution to the study of 14 MeV neutron scattering by {sup 12}C using a time-of-flight spectrometer (1963); Contribution a l'etude de la diffusion des neutrons de 14 MeV par {sup 12}C, a l'aide d'un spectrometre a temps de vol (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Perrin, P [Commisariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1963-07-15

    Experimental measurements of 14 MeV fast neutrons scattering by {sup 12}C by time-flight spectrometer, with a 1.7 n. sec over-all resolution. The excitation of the 7.65 MeV level is observed. (author) [French] Etude experimentate de la diffusion par {sup 12}C des neutrons rapides de 14 MeV a l'aide d'un spectrometre de resolution totale de 17 n/s. Observation de l'excitation du niveau 0+ de 7,65 MeV. (auteur)

  8. Estimated neutron dose to embryo and foetus during commercial flight

    International Nuclear Information System (INIS)

    Chen, J.; Lewis, B. J.; Bennett, L. G. I.; Green, A. R.; Tracy, B. L.

    2005-01-01

    A study has been carried out to assess the radiation exposure from cosmic-ray neutrons to the embryo and foetus of pregnant aircrew and air travellers in consideration of the radiation exposure from cosmic-ray neutrons to the embryo and foetus. A Monte Carlo analysis was performed to determine the equivalent dose from neutrons to the brain and body of an embryo at 8 weeks and to the foetus at the 3, 6 and 9 month periods. Neutron fluence-to-absorbed dose conversion coefficients for the foetal brain and for the entire foetal body (isotropic irradiation geometry) have been determined at the four developmental stages. The equivalent dose rate to the foetus during commercial flights has been further evaluated considering the fluence-to-absorbed dose conversion coefficients, a neutron spectrum measured at an altitude of 11.3 km and an ICRP-92 radiation-weighting factor for neutrons. This study indicates that the foetus can exceed the annual dose limit of 1 mSv for the general public after, for example, 15 round trips on commercial trans-Atlantic flights. (authors)

  9. Time-of-flight studies of multiple Bragg reflections in cylindrically bent perfect crystals

    Czech Academy of Sciences Publication Activity Database

    Mikula, Pavol; Furusaka, M.; Ohkubob, K.; Šaroun, Jan

    2012-01-01

    Roč. 45, č. 12 (2012), s. 1248-1253 ISSN 0021-8898 R&D Projects: GA AV ČR KJB100480901; GA ČR GAP204/10/0654 Institutional support: RVO:61389005 Keywords : neutron diffraction * time-of-flight method * multiple reflections * bent perfect crystals Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.343, year: 2012

  10. A time-focusing Fourier chopper time-of-flight diffractometer for large scattering angles

    International Nuclear Information System (INIS)

    Heinonen, R.; Hiismaeki, P.; Piirto, A.; Poeyry, H.; Tiitta, A.

    1975-01-01

    A high-resolution time-of-flight diffractometer utilizing time focusing principles in conjunction with a Fourier chopper is under construction at Otaniemi. The design is an improved version of a test facility which has been used for single-crystal and powder diffraction studies with promising results. A polychromatic neutron beam from a radial beam tube of the FiR 1 reactor, collimated to dia. 70 mm, is modulated by a Fourier chopper (dia. 400 mm) which is placed inside a massive boron-loaded particle board shielding of 900 mm wall thickness. A thin flat sample (5 mm x dia. 80 mm typically) is mounted on a turntable at a distance of 4 m from the chopper, and the diffracted neutrons are counted by a scintillation detector at 4 m distance from the sample. The scattering angle 2theta can be chosen between 90deg and 160deg to cover Bragg angles from 45deg up to 80deg. The angle between the chopper disc and the incident beam direction as well as the angle of the detector surface relative to the diffracted beam can be adjusted between 45deg and 90deg in order to accomplish time-focusing. In our set-up, with equal flight paths from chopper to sample and from sample to detector, the time-focusing conditions are fulfilled when the chopper and the detector are parallel to the sample-plane. The time-of-flight spectrum of the scattered neutrons is measured by the reverse time-of-flight method in which, instead of neutrons, one essentially records the modulation function of the chopper during constant periods preceding each detected neutron. With a Fourier chopper whose speed is varied in a suitable way, the method is equivalent to the conventional Fourier method but the spectrum is obtained directly without any off-line calculations. The new diffractometer is operated automatically by a Super Nova computer which not only accumulates the synthetized diffraction pattern but also controls the chopper speed according to the modulation frequency sweep chosen by the user to obtain a

  11. Focusing procedures in time-of-flight mass spectrometry

    International Nuclear Information System (INIS)

    Ioanoviciu, D.

    2002-01-01

    Time-of-flight mass spectrometry is a fast growing field due to its ability to handle very fast processes and due to its theoretically unlimited mass range. The performances of the time-of-flight mass analysers are heavily dependent on the progress in ion optics, a periodically reviewed field. In this presentation the various focusing procedures in time-of-flight mass spectrometry are reviewed. For ions of the same charge and mass flight time differences result from different potentials at the location of formation and from the initial velocity spread. There is no simultaneous space and velocity focusing in time-of-flight mass spectrometry. Space focusing of first and second order can be reached in time-of-flight mass analysers having two homogeneous electric field ion sources followed by a field free space in front of the detector. Single and double stage homogeneous electric field mirrors can focus in time ions of different energies. These different energies result when ions leaving different initial sites and arriving simultaneously to an intermediate space focus. Convenient mass dispersion can be obtained by including a mirror. Initial velocity focusing is obtained by the delayed extraction procedure in drift space and mirror time-of-flight mass analysers. Post source pulse focusing aims at the same purpose. Ion source electrodes of hyperbolic shape, operated by high voltage pulses can bring major improvements of the resolution, especially at high masses. For each focusing procedure the geometric and/or electric conditions are given as well as the aberrations allowing the mass resolution determination. The various focusing procedures are compared and a prediction of their future performances was tempted. (author)

  12. Organic scintillators response function modeling for Monte Carlo simulation of Time-of-Flight measurements

    Energy Technology Data Exchange (ETDEWEB)

    Carasco, C., E-mail: cedric.carasco@cea.fr [CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 Saint-Paul-lez-Durance (France)

    2012-07-15

    In neutron Time-of-Flight (TOF) measurements performed with fast organic scintillation detectors, both pulse arrival time and amplitude are relevant. Monte Carlo simulation can be used to calculate the time-energy dependant neutron flux at the detector position. To convert the flux into a pulse height spectrum, one must calculate the detector response function for mono-energetic neutrons. MCNP can be used to design TOF systems, but standard MCNP versions cannot reliably calculate the energy deposited by fast neutrons in the detector since multiple scattering effects must be taken into account in an analog way, the individual recoil particles energy deposit being summed with the appropriate scintillation efficiency. In this paper, the energy response function of 2 Double-Prime Multiplication-Sign 2 Double-Prime and 5 Double-Prime Multiplication-Sign 5 Double-Prime liquid scintillation BC-501 A (Bicron) detectors to fast neutrons ranging from 20 keV to 5.0 MeV is computed with GEANT4 to be coupled with MCNPX through the 'MCNP Output Data Analysis' software developed under ROOT (). - Highlights: Black-Right-Pointing-Pointer GEANT4 has been used to model organic scintillators response to neutrons up to 5 MeV. Black-Right-Pointing-Pointer The response of 2 Double-Prime Multiplication-Sign 2 Double-Prime and 5 Double-Prime Multiplication-Sign 5 Double-Prime BC501A detectors has been parameterized with simple functions. Black-Right-Pointing-Pointer Parameterization will allow the modeling of neutron Time of Flight measurements with MCNP using tools based on CERN's ROOT.

  13. Analytical properties of time-of-flight PET data

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Sanghee; Ahn, Sangtae; Quanzheng, Li; Leahy, Richard M [Signal and Image Processing Institute, University of Southern California, Los Angeles, CA 90089 (United States)], E-mail: leahy@sipi.usc.edu

    2008-06-07

    We investigate the analytical properties of time-of-flight (TOF) positron emission tomography (PET) sinograms, where the data are modeled as line integrals weighted by a spatially invariant TOF kernel. First, we investigate the Fourier transform properties of 2D TOF data and extend the 'bow-tie' property of the 2D Radon transform to the time-of-flight case. Second, we describe a new exact Fourier rebinning method, TOF-FOREX, based on the Fourier transform in the time-of-flight variable. We then combine TOF-FOREX rebinning with a direct extension of the projection slice theorem to TOF data, to perform fast 3D TOF PET image reconstruction. Finally, we illustrate these properties using simulated data.

  14. Analytical properties of time-of-flight PET data

    Science.gov (United States)

    Cho, Sanghee; Ahn, Sangtae; Li, Quanzheng; Leahy, Richard M.

    2008-06-01

    We investigate the analytical properties of time-of-flight (TOF) positron emission tomography (PET) sinograms, where the data are modeled as line integrals weighted by a spatially invariant TOF kernel. First, we investigate the Fourier transform properties of 2D TOF data and extend the 'bow-tie' property of the 2D Radon transform to the time-of-flight case. Second, we describe a new exact Fourier rebinning method, TOF-FOREX, based on the Fourier transform in the time-of-flight variable. We then combine TOF-FOREX rebinning with a direct extension of the projection slice theorem to TOF data, to perform fast 3D TOF PET image reconstruction. Finally, we illustrate these properties using simulated data.

  15. Analytical properties of time-of-flight PET data

    International Nuclear Information System (INIS)

    Cho, Sanghee; Ahn, Sangtae; Li Quanzheng; Leahy, Richard M

    2008-01-01

    We investigate the analytical properties of time-of-flight (TOF) positron emission tomography (PET) sinograms, where the data are modeled as line integrals weighted by a spatially invariant TOF kernel. First, we investigate the Fourier transform properties of 2D TOF data and extend the 'bow-tie' property of the 2D Radon transform to the time-of-flight case. Second, we describe a new exact Fourier rebinning method, TOF-FOREX, based on the Fourier transform in the time-of-flight variable. We then combine TOF-FOREX rebinning with a direct extension of the projection slice theorem to TOF data, to perform fast 3D TOF PET image reconstruction. Finally, we illustrate these properties using simulated data

  16. Analytical properties of time-of-flight PET data

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Sanghee; Ahn, Sangtae; Li Quanzheng; Leahy, Richard M [Signal and Image Processing Institute, University of Southern California, Los Angeles, CA 90089 (United States)], E-mail: leahy@sipi.usc.edu

    2008-06-07

    We investigate the analytical properties of time-of-flight (TOF) positron emission tomography (PET) sinograms, where the data are modeled as line integrals weighted by a spatially invariant TOF kernel. First, we investigate the Fourier transform properties of 2D TOF data and extend the 'bow-tie' property of the 2D Radon transform to the time-of-flight case. Second, we describe a new exact Fourier rebinning method, TOF-FOREX, based on the Fourier transform in the time-of-flight variable. We then combine TOF-FOREX rebinning with a direct extension of the projection slice theorem to TOF data, to perform fast 3D TOF PET image reconstruction. Finally, we illustrate these properties using simulated data.

  17. The statistical chopper in the time-of-flight technique

    International Nuclear Information System (INIS)

    Albuquerque Vieira, J. de.

    1975-12-01

    A detailed study of the 'statistical' chopper and of the method of analysis of the data obtained by this technique is made. The study includes the basic ideas behind correlation methods applied in time-of-flight techniques; comparisons with the conventional chopper made by an analysis of statistical errors; the development of a FORTRAN computer programme to analyse experimental results; the presentation of the related fields of work to demonstrate the potential of this method and suggestions for future study together with the criteria for a time-of-flight experiment using the method being studied [pt

  18. Rocket-borne time-of-flight mass spectrometry

    Science.gov (United States)

    Reiter, R. F.

    1976-01-01

    Theoretical and numerical analyses are made of planar, cylindrical and spherical-electrode two-field time-of-flight mass spectrometers in order to optimize their operating conditions. A method is introduced which can improve the resolving power of these instruments by a factor of 7.5. Potential barrier gating in time-of-flight mass spectrometers is also analyzed. Experimental studies of a miniature cylindrical-electrode and a hemispherical-electrode time-of-flight mass spectrometer are presented. Their sensitivity and ability to operate at D-region pressures with an open source make them ideal instruments for D-region ion composition measurements. A sounding rocket experiment package carrying a cylindrical electrode time-of-flight mass spectrometer was launched. The data indicate that essentially 100% of the positive electric charge on positive ions is carried by ions with mass-to-charge ratios greater than 500 below an altitude of 92 km. These heavy charge carriers were present at altitudes up to about 100 km.

  19. Rocket-borne time-of-flight mass spectrometry

    International Nuclear Information System (INIS)

    Reiter, R.F.

    1976-08-01

    Theoretical and numerical analyses are made of planar-, cylindrical- and spherical-electrode two-field time-of-flight mass spectrometers in order to optimize their operating conditions. A method is introduced which can improve the resolving power of these instruments by a factor of 7.5. Potential barrier gating in time-of-flight mass spectrometers is also analyzed. Experimental studies of a miniature cylindrical-electrode and a hemispherical-electrode time-of-flight mass spectrometer are presented. Their sensitivity and ability to operate at D-region pressures with an open source make them ideal instruments for D-region ion composition measurements. A sounding rocket experiment package carrying a cylindrical electrode time-of-flight mass spectrometer was launched. The data indicate that essentially 100% of the positive electric charge on positive ions is carried by ions with mass-to-charge ratios greater than 500 below an altitude of 92 km. These heavy charge carriers were present at altitudes up to about 100 km

  20. Time-of-flight positron emission tomography and associated detectors

    International Nuclear Information System (INIS)

    Vacher, J.; Allemand, R.; Campagnolo, R.

    1983-04-01

    An analysis of the timing capabilities of the detectors (scintillators and photomultipliers) in time-of-flight positron emission tomography is presented. The advantages of BaF 2 compared with CsF for the futur tomographs are evaluated [fr

  1. Highly segmented, high resolution time-of-flight system

    Energy Technology Data Exchange (ETDEWEB)

    Nayak, T.K.; Nagamiya, S.; Vossnack, O.; Wu, Y.D.; Zajc, W.A. [Columbia Univ., New York, NY (United States); Miake, Y.; Ueno, S.; Kitayama, H.; Nagasaka, Y.; Tomizawa, K.; Arai, I.; Yagi, K [Univ. of Tsukuba, (Japan)

    1991-12-31

    The light attenuation and timing characteristics of time-of-flight counters constructed of 3m long scintillating fiber bundles of different shapes and sizes are presented. Fiber bundles made of 5mm diameter fibers showed good timing characteristics and less light attenuation. The results for a 1.5m long scintillator rod are also presented.

  2. High sensitivity probe absorption technique for time-of-flight ...

    Indian Academy of Sciences (India)

    Abstract. We report on a phase-sensitive probe absorption technique with high sen- sitivity, capable of detecting a few hundred ultra-cold atoms in flight in an observation time of a few milliseconds. The large signal-to-noise ratio achieved is sufficient for reliable measurements on low intensity beams of cold atoms.

  3. Measurement and simulation of the inelastic resolution function of a time-of-flight spectrometer

    International Nuclear Information System (INIS)

    Roth, S.V.; Zirkel, A.; Neuhaus, J.; Petry, W.; Bossy, J.; Peters, J.; Schober, H.

    2002-01-01

    The deconvolution of inelastic neutron scattering data requires the knowledge of the inelastic resolution function. The inelastic resolution function of the time-of-flight spectrometer IN5/ILL has been measured by exploiting the sharp resonances of the roton and maxon excitations in superfluid 4 He for the two respective (q,ω) values. The calculated inelastic resolution function for three different instrumental setups is compared to the experimentally determined resolution function. The agreement between simulation and experimental data is excellent, allowing us in principle to extrapolate the simulations and thus to determine the resolution function in the whole accessible dynamic range of IN5 or any other time-of-flight spectrometer. (orig.)

  4. Measurement and simulation of the inelastic resolution function of a time-of-flight spectrometer

    CERN Document Server

    Roth, S V; Neuhaus, J; Petry, W; Bossy, J; Peters, J; Schober, H

    2002-01-01

    The deconvolution of inelastic neutron scattering data requires the knowledge of the inelastic resolution function. The inelastic resolution function of the time-of-flight spectrometer IN5/ILL has been measured by exploiting the sharp resonances of the roton and maxon excitations in superfluid sup 4 He for the two respective (q,omega) values. The calculated inelastic resolution function for three different instrumental setups is compared to the experimentally determined resolution function. The agreement between simulation and experimental data is excellent, allowing us in principle to extrapolate the simulations and thus to determine the resolution function in the whole accessible dynamic range of IN5 or any other time-of-flight spectrometer. (orig.)

  5. TORCH—a Cherenkov based time-of-flight detector

    Energy Technology Data Exchange (ETDEWEB)

    Dijk, M.W.U. van, E-mail: m.vandijk@bristol.ac.uk [H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Brook, N.H. [H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Castillo García, L. [European Organisation for Nuclear Research (CERN), CH-1211 Geneva 23 (Switzerland); Laboratory for High Energy Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Cowie, E.N.; Cussans, D. [H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); D' Ambrosio, C. [European Organisation for Nuclear Research (CERN), CH-1211 Geneva 23 (Switzerland); Fopma, J. [Denys Wilkinson Laboratory, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Forty, R.; Frei, C. [European Organisation for Nuclear Research (CERN), CH-1211 Geneva 23 (Switzerland); Gao, R. [Denys Wilkinson Laboratory, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Gys, T. [European Organisation for Nuclear Research (CERN), CH-1211 Geneva 23 (Switzerland); Harnew, N.; Keri, T. [Denys Wilkinson Laboratory, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Piedigrossi, D. [European Organisation for Nuclear Research (CERN), CH-1211 Geneva 23 (Switzerland)

    2014-12-01

    TORCH is an innovative high-precision time-of-flight system to provide particle identification in the difficult intermediate momentum region up to 10 GeV/c. It is also suitable for large-area applications. The detector provides a time-of-flight measurement from the imaging of Cherenkov photons emitted in a 1 cm thick quartz radiator. The photons propagate by total internal reflection to the edge of the quartz plate and are then focused onto an array of photon detectors at the periphery. A time-of-flight resolution of about 10–15 ps per incident charged particle needs to be achieved to allow a three sigma kaon-pion separation up to 10 GeV/c momentum for the TORCH located 9.5 m from the interaction point. Given ∼30 detected photons per incident charged particle, this requires measuring the time-of-arrival of individual photons to about 70 ps. This paper will describe the design of a TORCH prototype involving a number of ground-breaking and challenging techniques.

  6. Preliminary studies of microchannel plate photomultiplier tube neutron detectors for flight test applications

    International Nuclear Information System (INIS)

    Dolan, K.W.

    1978-10-01

    Electrical, mechanical, thermal, and neutron response data indicate that microchannel plate photomultiplier tubes are viable candidates as miniature, ruggedized neutron detectors for flight test applications in future weapon systems

  7. The ANTARES recoil time-of-flight spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Martin, J W; Russell, G J [New South Wales Univ., Kensington, NSW (Australia); Cohen, D D; Dytlewski, N [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1997-12-31

    The Australian National Tandem for Applied Research (ANTARES), is a 8MV FN tandem particle accelerator at the Australian Nuclear Science and Technology Organisation. Research on the accelerator is divided between two groups, Accelerator Mass Spectrometry (AMS) and lon Beam Analysis (IBA). The IBA group carries out a range of research projects from nuclear physics to materials characterisation. The major IBA project on the accelerator is a recoil time-of-flight spectrometer which consists of two electrostatic time pulse generators and an ion-implanted surface barrier detector. The spectrometer is ideally suited to the profiling of layered multi-element materials, and has been used to characterise materials such as metal-germanides, optoelectronics, superconductors and catalytic converters. This paper will describe the time-of-flight system as well as some recent materials characterisation results. 1 refs., 3 figs.

  8. UTOFIA: an underwater time-of-flight image acquisition system

    Science.gov (United States)

    Driewer, Adrian; Abrosimov, Igor; Alexander, Jonathan; Benger, Marc; O'Farrell, Marion; Haugholt, Karl Henrik; Softley, Chris; Thielemann, Jens T.; Thorstensen, Jostein; Yates, Chris

    2017-10-01

    In this article the development of a newly designed Time-of-Flight (ToF) image sensor for underwater applications is described. The sensor is developed as part of the project UTOFIA (underwater time-of-flight image acquisition) funded by the EU within the Horizon 2020 framework. This project aims to develop a camera based on range gating that extends the visible range compared to conventional cameras by a factor of 2 to 3 and delivers real-time range information by means of a 3D video stream. The principle of underwater range gating as well as the concept of the image sensor are presented. Based on measurements on a test image sensor a pixel structure that suits best to the requirements has been selected. Within an extensive characterization underwater the capability of distance measurements in turbid environments is demonstrated.

  9. The ANTARES recoil time-of-flight spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Martin, J.W.; Russell, G.J. [New South Wales Univ., Kensington, NSW (Australia); Cohen, D.D.; Dytlewski, N. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1996-12-31

    The Australian National Tandem for Applied Research (ANTARES), is a 8MV FN tandem particle accelerator at the Australian Nuclear Science and Technology Organisation. Research on the accelerator is divided between two groups, Accelerator Mass Spectrometry (AMS) and lon Beam Analysis (IBA). The IBA group carries out a range of research projects from nuclear physics to materials characterisation. The major IBA project on the accelerator is a recoil time-of-flight spectrometer which consists of two electrostatic time pulse generators and an ion-implanted surface barrier detector. The spectrometer is ideally suited to the profiling of layered multi-element materials, and has been used to characterise materials such as metal-germanides, optoelectronics, superconductors and catalytic converters. This paper will describe the time-of-flight system as well as some recent materials characterisation results. 1 refs., 3 figs.

  10. Pulse Based Time-of-Flight Range Sensing.

    Science.gov (United States)

    Sarbolandi, Hamed; Plack, Markus; Kolb, Andreas

    2018-05-23

    Pulse-based Time-of-Flight (PB-ToF) cameras are an attractive alternative range imaging approach, compared to the widely commercialized Amplitude Modulated Continuous-Wave Time-of-Flight (AMCW-ToF) approach. This paper presents an in-depth evaluation of a PB-ToF camera prototype based on the Hamamatsu area sensor S11963-01CR. We evaluate different ToF-related effects, i.e., temperature drift, systematic error, depth inhomogeneity, multi-path effects, and motion artefacts. Furthermore, we evaluate the systematic error of the system in more detail, and introduce novel concepts to improve the quality of range measurements by modifying the mode of operation of the PB-ToF camera. Finally, we describe the means of measuring the gate response of the PB-ToF sensor and using this information for PB-ToF sensor simulation.

  11. Time-of-flight detector with KBr working medium

    International Nuclear Information System (INIS)

    Arvanov, A.N.; Gavalyan, V.G.; Lorikyan, M.P.

    1983-01-01

    A detector of controlled secondary electron emission as a 3-electrode focusing electrostatic system of the photomultiplier input chamber having a microchannel electron plate herringbone assembly with the total gain of approXimately 10 7 is described. A controlled secondary emission emitter based on MgO or KBr is installed as a cathode. The detector is designed for time-of-flight spectrometers. The time resolution is < or approximately equal to 0.5 ns. The time-of-flight system realized on the base of such two detectors has 100% detection efficiency and it is ''transparent'' for an identified particle. Its characteristics for α particle, deuteron and proton detection are estimated

  12. Time of flight measurement on the SOFIA experiment

    International Nuclear Information System (INIS)

    Bail, A.; Taieb, J.; Chatillon, A.; Belier, G.; Laurent, B.; Pellereau, E.

    2011-01-01

    The SOFIA experiment, which will be held at GSI (Darmstadt (Germany)) will allow to completely determine the mass and charge numbers of fragments produced in the fission reaction of radioactive actinides in reverse kinematics. Therefore, a dedicated setup has been developed for the Time of Flight measurement of relativistic heavy ions. The studies, which led to the choice of the adequate plastic scintillators and photomultipliers, are presented. Tests have been undertaken with the ELSA laser and electron beam facility. They shown that a suitable choice would be EJ-232 plastic scintillator for the ToF wall and EJ-232Q for the start detector and Hamamatsu H6533 and H10580 photomultipliers. This was confirmed by two test experiments realized at GSI with relativistic heavy ion beam ( 56 Fe and 238 U), where a time of flight resolution better than 20 ps FWHM was reached. (authors)

  13. Time of flight measurement on the SOFIA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Bail, A.; Taieb, J.; Chatillon, A.; Belier, G.; Laurent, B.; Pellereau, E. [CEA/DAM/DIF, Arpajon (France)

    2011-07-01

    The SOFIA experiment, which will be held at GSI (Darmstadt (Germany)) will allow to completely determine the mass and charge numbers of fragments produced in the fission reaction of radioactive actinides in reverse kinematics. Therefore, a dedicated setup has been developed for the Time of Flight measurement of relativistic heavy ions. The studies, which led to the choice of the adequate plastic scintillators and photomultipliers, are presented. Tests have been undertaken with the ELSA laser and electron beam facility. They shown that a suitable choice would be EJ-232 plastic scintillator for the ToF wall and EJ-232Q for the start detector and Hamamatsu H6533 and H10580 photomultipliers. This was confirmed by two test experiments realized at GSI with relativistic heavy ion beam ({sup 56}Fe and {sup 238}U), where a time of flight resolution better than 20 ps FWHM was reached. (authors)

  14. Time of flight spectrometry in heavy ions backscattering analysis

    International Nuclear Information System (INIS)

    Chevarier, A.; Chevarier, N.

    1983-05-01

    Time of flight spectrometry for backscattering analysis of MeV heavy ions is proposed. The capabilities and limitations of this method are investigated. Depth and mass resolution obtained in measurements of oxide films thickness as well as in GaAs layers analysis are presented. The importance of minimizing pile-up without significant loss of resolution by use of an adequate absorber set just in front of the rear detector is underlined

  15. The time-of-flight detector of the DIRAC experiment

    International Nuclear Information System (INIS)

    Adeva, B.; Gallas, M.V.; Gomez, F.; Lopez-Agueera, A.; Nunez-Pardo, T.; Plo, M.; Rodriguez, A.M.; Rodriguez, X.M.; Saborido, J.J.; Santamarina, C.; Tobar, M.J.; Vazquez, P.

    2002-01-01

    The construction and performance of a large area time-of-flight detector for the DIRAC experiment at CERN is reported. With an average time resolution of 123 ps per counter at rates up to 1 MHz, it allows excellent separation of pπ - from π + π - pairs up to 4.6 GeV/c momentum, as well as of Coulomb-correlated pion pairs from accidentals. The optimization of scintillator material, photomultiplier performance and readout electronics is described

  16. KELVIN rare gas time-of-flight program

    International Nuclear Information System (INIS)

    Vernon, M.

    1981-03-01

    The purpose of this appendix is to explain in detail the procedure for performing time-of-flight (TOF) calibration measurements. The result of the calibration measurements is to assign a correct length (L) to the path the molecules travel in a particular experimental configuration. In conjunction with time information (t) a velocity distribution (L/t) can then be determined. The program KELVIN is listed

  17. Time of flight imaging through scattering environments (Conference Presentation)

    Science.gov (United States)

    Le, Toan H.; Breitbach, Eric C.; Jackson, Jonathan A.; Velten, Andreas

    2017-02-01

    Light scattering is a primary obstacle to imaging in many environments. On small scales in biomedical microscopy and diffuse tomography scenarios scattering is caused by tissue. On larger scales scattering from dust and fog provide challenges to vision systems for self driving cars and naval remote imaging systems. We are developing scale models for scattering environments and investigation methods for improved imaging particularly using time of flight transient information. With the emergence of Single Photon Avalanche Diode detectors and fast semiconductor lasers, illumination and capture on picosecond timescales are becoming possible in inexpensive, compact, and robust devices. This opens up opportunities for new computational imaging techniques that make use of photon time of flight. Time of flight or range information is used in remote imaging scenarios in gated viewing and in biomedical imaging in time resolved diffuse tomography. In addition spatial filtering is popular in biomedical scenarios with structured illumination and confocal microscopy. We are presenting a combination analytical, computational, and experimental models that allow us develop and test imaging methods across scattering scenarios and scales. This framework will be used for proof of concept experiments to evaluate new computational imaging methods.

  18. Multivariate Sensitivity Analysis of Time-of-Flight Sensor Fusion

    Science.gov (United States)

    Schwarz, Sebastian; Sjöström, Mårten; Olsson, Roger

    2014-09-01

    Obtaining three-dimensional scenery data is an essential task in computer vision, with diverse applications in various areas such as manufacturing and quality control, security and surveillance, or user interaction and entertainment. Dedicated Time-of-Flight sensors can provide detailed scenery depth in real-time and overcome short-comings of traditional stereo analysis. Nonetheless, they do not provide texture information and have limited spatial resolution. Therefore such sensors are typically combined with high resolution video sensors. Time-of-Flight Sensor Fusion is a highly active field of research. Over the recent years, there have been multiple proposals addressing important topics such as texture-guided depth upsampling and depth data denoising. In this article we take a step back and look at the underlying principles of ToF sensor fusion. We derive the ToF sensor fusion error model and evaluate its sensitivity to inaccuracies in camera calibration and depth measurements. In accordance with our findings, we propose certain courses of action to ensure high quality fusion results. With this multivariate sensitivity analysis of the ToF sensor fusion model, we provide an important guideline for designing, calibrating and running a sophisticated Time-of-Flight sensor fusion capture systems.

  19. Timing properties of a time-of-flight detector

    International Nuclear Information System (INIS)

    Nakagawa, Takahide; Yuasa-Nakagawa, Keiko.

    1989-01-01

    The time resolution of a time-of-flight (T.O.F.) detector which consists of a channel plate detector (CPD) with a central hole and a surface barrier detector (SBD) was measured. A time resolution of 80 psec fwhm was obtained for 8.78 MeV alpha particles. The influence on fast timing of the SBD of alpha particles was carefully studied. The plasma delay time and time resolution of the SBD were found to strongly depend on the electric field strength and properties of the SBD. (author)

  20. Time-of-flight range imaging for underwater applications

    Science.gov (United States)

    Merbold, Hannes; Catregn, Gion-Pol; Leutenegger, Tobias

    2018-02-01

    Precise and low-cost range imaging in underwater settings with object distances on the meter level is demonstrated. This is addressed through silicon-based time-of-flight (TOF) cameras operated with light emitting diodes (LEDs) at visible, rather than near-IR wavelengths. We find that the attainable performance depends on a variety of parameters, such as the wavelength dependent absorption of water, the emitted optical power and response times of the LEDs, or the spectral sensitivity of the TOF chip. An in-depth analysis of the interplay between the different parameters is given and the performance of underwater TOF imaging using different visible illumination wavelengths is analyzed.

  1. Molecular beam studies with a time-of-flight machine

    International Nuclear Information System (INIS)

    Beijerinck, H.C.W.

    1975-01-01

    The study concerns the development of the time-of-flight method for the velocity analysis of molecular beams and its application to the measurement of the velocity dependence of the total cross-section of the noble gases. It reviews the elastic scattering theory, both in the framework of classical mechanics and in the quantum mechanical description. Attention is paid to the semiclassical correspondence of classical particle trajectories with the partial waves of the quantum mechanical solution. The total cross-section and the small angle differential cross-section are discussed with special emphasis on their relation. The results of this chapter are used later to derive the correction on the measured total cross-section due to the finite angular resolution of the apparatus. Reviewed also is the available information on the intermolecular potential of the Ar-Ar system. Then a discussion of the measurement of total cross-sections with the molecular beam method and the time-of-flight method is compared to other methods used. It is shown that the single burst time-of-flight method can be developed into a reliable and well-calibrated method for the analysis of the velocity distribution of molecular beams. A comparison of the single burst time-of-flight method with the cross-correlation time-of-flight method shows that the two methods are complementary and that the specific experimental circumstances determine which method is to be preferred. Molecular beam sources are discussed. The peaking factor formalism is introduced and helps to compare the performance of different types of sources. The effusive and the supersonic source are treated and recent experimental results are given. The multichannel source is treated in more detail. For the opaque mode, an experimental investigation of the velocity distribution and the angular distribution of the flow pattern is presented. Comparison of these results with Monte Carlo calculations for free molecular flow in a cylindrical

  2. Results of Time-of-Flight Neutron Capture Measurements of 176,177,178,179 Hf-enriched and nat Hf samples at 10 m, 30 m and 60 m stations of GELINA

    International Nuclear Information System (INIS)

    Ware, T.C.; Dean, C.J.; Borella, A.; Kopecky, S.; Moens, A.; Schillebeeckx, P.; Janeva, N.; Moxon, M.C.

    2014-04-01

    Neutron capture measurements have been performed at the time-offlight facility GELINA to determine neutron resonance parameters for 174,176,177,178,179,180 Hf. In total, 16 distinct experiments were conducted at the 12 m, 28 m and 58 m capture stations using C 6 D 6 detectors with a moderated neutron beam and the accelerator operating at 50 Hz or 800 Hz. Measurements were performed with nat Hf metallic samples and oxide samples enriched in 176 Hf, 177 Hf, 178 Hf and 179 Hf. This report describes the experimental details required to deliver the experimental capture yields to the EXFOR data library which is maintained by the Nuclear Energy Agency of the OECD and the Nuclear Data Section of the IAEA. The experimental conditions and data reduction procedures are described. In addition, the full covariance information based on the AGS concept is given, such that resonance parameters together with their covariances can be derived in a least squares adjustment to the data. (author)

  3. A reverse time of flight analyzer facility at the ETRR-1 reactor

    Energy Technology Data Exchange (ETDEWEB)

    Maayouf, R M.A.; El-Shafey, A S; Khalil, M I [Reactor and Neutron Physics Dept., NRC, Atomic Energy Authority, Cairo (Egypt)

    1997-12-31

    The present work deals both with the theory and performance of a reverse-time-of-flight (RTOF) analyzer designed to analyze pulses emitted from a fourier chopper recently put into operation at the ETRR-1 reactor. The RTOF analyze was found to be adequate for use with pick up pulses from the fourier chopper which operates following a frequency window suitable for rotation rates from 0-9000 rpm; synchronically with neutron pulses from a {sup 6} Li glass detector set at time focusing geometry for scattering angle 20=90 degree. It was possible, with the present RTOF analyzer to obtain diffraction patterns at neutron wavelength range between 1 - 4 A within a resolution = 0.5%. 8 FIGS.

  4. Ultrasonic testing using time of flight diffraction technique (TOFD)

    International Nuclear Information System (INIS)

    Khurram Shahzad; Ahmad Mirza Safeer Ahmad; Muhammad Asif Khan

    2009-04-01

    This paper describes the ultrasonic testing using Time Flight Diffraction (TOFD) Technique for welded samples having different types and sizes of defects. TOFD is a computerized ultrasonic system, able to scan, store and evaluate indications in terms of location, through thickness and length in a more easy and convenient. Time of Flight Diffraction Technique (TOFD) is more fast and easy technique for ultrasonic testing as we can examine a weld i a single scan along the length of the weld with two probes known as D-scan. It shows the image of the complete weld with the defect information. The examinations were performed on carbon steel samples used for ultrasonic testing using 70 degree probes. The images for different type of defects were obtained. (author)

  5. Ion microtomography using ion time-of-flight

    International Nuclear Information System (INIS)

    Roberts, M.L.; Heikkinen, D.W.; Proctor, I.D.; Pontau, A.E.; Olona, G.T.; Felter, T.E.; Morse, D.H.; Hess, B.V.

    1992-01-01

    We have developed and are in the process of testing an ion time-of-flight (TOF) detector system for use in our ion microtomography measurements. Using TOF, ion energy is determined by measurement of the ion's flight time over a certain path length. For ion microtomography, the principle advantage of TOF analysis is that ion count rates of several hundred thousand counts per second can be achieved as compared to a limit of about ten thousand ions per second when using a solid-state silicon surface barrier detector and associated electronics. This greater than 10 fold increase in count rate correspondingly shortens sample analysis time or increases the amount of data that can be collected on a given sample. Details of the system and progress to date are described

  6. Time-of-flight scattering and recoiling spectrometry

    International Nuclear Information System (INIS)

    Rabalais, J.W.

    1991-01-01

    Ion scattering and recoiling spectrometry consists of directing a collimated beam of monoenergetic ions towards a surface and measuring the flux of scattered and recoiled particles from this surface. When the neutral plus ion flux is velocity selected by measuring the flight times from the sample to the detector, the technique is called time-of-flight scattering and recoiling spectrometry (TOF-SARS). TOF-SARS is capable of (1) surface elemental analysis by applying classical mechanics to the velocities of the particles, (2) surface structural analysis by monitoring the angular anisotropies in the particle flux, and (3) ion-surface electron exchange probabilities by analysis of the ion/neutral fractions in the particle flux. Examples of these three areas are presented herein

  7. A description of the equipment for time-of-flight spectrum measurements on the fast reactor ZEBRA

    International Nuclear Information System (INIS)

    Gibson, I.H.; Jakeman, D.; Sanders, J.E.

    1969-05-01

    The pulsed source for the time-of-flight equipment consists of 14 MeV S-band linear electron accelerator, drift tube and water-cooled uranium-molybdenum alloy target installed on the ZEBRA lattice. Neutrons are extracted via a probe tube inserted into the core and an evacuated flight tube with counting stations at 50 m, 97 m and 200 m from the core centre. Two types of neutron detector are described and also the Perranti Argus 500 on-line computer which is used for data collection. The equipment is used for measuring the neutron energy spectra from the lowest energies up to about 1 MeV. (author)

  8. Cluster Tracking with Time-of-Flight Cameras

    DEFF Research Database (Denmark)

    Hansen, Dan Witzner; Hansen, Mads; Kirschmeyer, Martin

    2008-01-01

    We describe a method for tracking people using a time-of-flight camera and apply the method for persistent authentication in a smart-environment. A background model is built by fusing information from intensity and depth images. While a geometric constraint is employed to improve pixel cluster...... coherence and reducing the influence of noise, the EM algorithm (expectation maximization) is used for tracking moving clusters of pixels significantly different from the background model. Each cluster is defined through a statistical model of points on the ground plane. We show the benefits of the time...

  9. The Time-of-Flight Detector for the ALICE experiment

    CERN Document Server

    Williams, M C S

    2002-01-01

    The Multigap Resistive Plate Chamber (MRPC) will be used to build a large Time-of-Flight detector for the ALICEexperiment. It will cover an area of 150 m2 consisting of 160,000 channels of 3.5 x 2.5 cm2 read-out pads. We present the results of the last 2 years of R&D during which we investigated problems associated with scaling up from single cells of 3 x 3 cm2 to strips with active area of 7 × 120 cm2 read out with 96 pads.

  10. Time-of-flight cameras principles, methods and applications

    CERN Document Server

    Hansard, Miles; Choi, Ouk; Horaud, Radu

    2012-01-01

    Time-of-flight (TOF) cameras provide a depth value at each pixel, from which the 3D structure of the scene can be estimated. This new type of active sensor makes it possible to go beyond traditional 2D image processing, directly to depth-based and 3D scene processing. Many computer vision and graphics applications can benefit from TOF data, including 3D reconstruction, activity and gesture recognition, motion capture and face detection. It is already possible to use multiple TOF cameras, in order to increase the scene coverage, and to combine the depth data with images from several colour came

  11. Material Classification Using Raw Time-of-Flight Measurements

    KAUST Repository

    Su, Shuochen

    2016-12-13

    We propose a material classification method using raw time-of-flight (ToF) measurements. ToF cameras capture the correlation between a reference signal and the temporal response of material to incident illumination. Such measurements encode unique signatures of the material, i.e. the degree of subsurface scattering inside a volume. Subsequently, it offers an orthogonal domain of feature representation compared to conventional spatial and angular reflectance-based approaches. We demonstrate the effectiveness, robustness, and efficiency of our method through experiments and comparisons of real-world materials.

  12. Time-of-Flight Positron Emission Tomography with Radiofrequency Phototube

    International Nuclear Information System (INIS)

    Margaryan, A.; Kakoyan, V.; Knyazyan, S.

    2011-01-01

    In this paper γ-detector, based on the radiofrequency (RF) phototube and recently developed fast and ultrafast scintillators, is considered for Time-of-Flight positron emission tomography applications. Timing characteristics of such a device has been investigated by means of a dedicated Monte Carlo code based on the single photon counting concept. Biexponential timing model for scintillators have been used. The calculations have shown that such a timing model is in a good agreement with recently measured data. The timing resolution of -detectors can be significantly improved by using the RF phototube. (authors)

  13. The ALICE Time of Flight Readout System AFRO

    CERN Document Server

    Kluge, A

    1999-01-01

    The ALICE Time of Flight Detector system comprises more than 100.000 channels and covers an area of more than 100 m2. The timing resolution should be better than 150 ps. This combination of requirements poses a major challenge to the readout system. All detector timing measurements are referenced to a unique start signal t0. This signal is generated at the time an event occurs. Timing measurements are performed using a multichannel TDC chip which requires a 40 MHz reference clock signal. The general concept of the readout system is based on a modular architecture. Detector cells are combined to modules of 1024 channels. Each of these modules can be read out and calibrated independently from each other. By distributing a reference signal, a timing relationship between the modules is established. This reference signal can either be the start signal t0 or the TDC-reference clock. The readout architecture is divided into three steps; the TDC controller, the module controller, and the time of flight controller. Th...

  14. Characterization of modulated time-of-flight range image sensors

    Science.gov (United States)

    Payne, Andrew D.; Dorrington, Adrian A.; Cree, Michael J.; Carnegie, Dale A.

    2009-01-01

    A number of full field image sensors have been developed that are capable of simultaneously measuring intensity and distance (range) for every pixel in a given scene using an indirect time-of-flight measurement technique. A light source is intensity modulated at a frequency between 10-100 MHz, and an image sensor is modulated at the same frequency, synchronously sampling light reflected from objects in the scene (homodyne detection). The time of flight is manifested as a phase shift in the illumination modulation envelope, which can be determined from the sampled data simultaneously for each pixel in the scene. This paper presents a method of characterizing the high frequency modulation response of these image sensors, using a pico-second laser pulser. The characterization results allow the optimal operating parameters, such as the modulation frequency, to be identified in order to maximize the range measurement precision for a given sensor. A number of potential sources of error exist when using these sensors, including deficiencies in the modulation waveform shape, duty cycle, or phase, resulting in contamination of the resultant range data. From the characterization data these parameters can be identified and compensated for by modifying the sensor hardware or through post processing of the acquired range measurements.

  15. In-situ time-of-flight neutron diffraction study of the structure evolution of electrode materials in a commercial battery with LiNi0.8Co0.15Al0.05O2 cathode

    Science.gov (United States)

    Bobrikov, I. A.; Samoylova, N. Yu.; Sumnikov, S. V.; Ivanshina, O. Yu.; Vasin, R. N.; Beskrovnyi, A. I.; Balagurov, A. M.

    2017-12-01

    A commercial lithium-ion battery with LiNi0.8Co0.15Al0.05O2 (NCA) cathode has been studied in situ using high-intensity and high-resolution neutron diffraction. Structure and phase composition of the battery electrodes have been probed during charge-discharge in different cycling modes. The dependence of the anode composition on the charge rate has been determined quantitatively. Different kinetics of Li (de)intercalation in the graphite anode during charge/discharge process have been observed. Phase separation of the cathode material has not been detected in whole voltage range. Non-linear dependencies of the unit cell parameters, atomic and layer spacing on the lithium content in the cathode have been observed. Measured dependencies of interatomic spacing and interlayer spacing, and unit cell parameters of the cathode structure on the lithium content could be qualitatively explained by several factors, such as variations of oxidation state of cation in oxygen octahedra, Coulomb repulsion of oxygen layers, changes of average effective charge of oxygen layers and van der Waals interactions between MeO2-layers at high level of the NCA delithiation.

  16. IceBridge Sigma Space Lidar L0 Raw Time-of-Flight Data

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA IceBridge Sigma Space Lidar L0 Raw Time-of-Flight Data (ILSIG0) contain raw time-of-flight values for Antarctica and Greenland using the Sigma Space Lidar....

  17. Structure of magnesium selenate enneahydrate, MgSeO4·9H2O, from 5 to 250 K using neutron time-of-flight Laue diffraction.

    Science.gov (United States)

    Fortes, A Dominic; Alfè, Dario; Hernández, Eduardo R; Gutmann, Matthias J

    2015-06-01

    The complete structure of MgSeO4·9H2O has been refined from neutron single-crystal diffraction data obtained at 5, 100, 175 and 250 K. It is monoclinic, space group P2₁/c, Z = 4, with unit-cell parameters a = 7.222 (2), b = 10.484 (3), c = 17.327 (4) Å, β = 109.57 (2)°, and V = 1236.1 (6) Å(3) [ρ(calc) = 1770 (1) kg m(-3)] at 5 K. The structure consists of isolated [Mg(H2O)6](2+) octahedra, [SeO4](2-) tetrahedra and three interstitial lattice water molecules, all on sites of symmetry 1. The positions of the H atoms agree well with those inferred on the basis of geometrical considerations in the prior X-ray powder diffraction structure determination: no evidence of orientational disorder of the water molecules is apparent in the temperature range studied. Six of the nine water molecules are hydrogen bonded to one another to form a unique centrosymmetric dodecamer, (H2O)12. Raman spectra have been acquired in the range 170-4000 cm(-1) at 259 and 78 K; ab initio calculations, using density functional theory, have been carried out in order to aid in the analysis of the Raman spectrum as well as providing additional insights into the geometry and thermodynamics of the hydrogen bonds. Complementary information concerning the thermal expansion, crystal morphology and the solubility are also presented.

  18. TOPLAR: Time of Flight with Larmor Precessions - or - How to extend the dynamic range of NSE spectrometers

    International Nuclear Information System (INIS)

    Van Well, A.A.; Bleuel, M.; Pappas, C.

    2011-01-01

    Neutron Spin Echo (NSE) spectrometers typically cover a dynamic range of three orders of magnitude at a given wavelength. At long Fourier times the limits are given by the homogeneity of precession fields. At short Fourier times, the quasi-elastic approximation and the NSE formalism mark a methodological limit. We propose to overcome this limitation and by combining Time Of Flight with Larmor precession to extend the capabilities of Neutron Spin Echo spectrometers towards short Fourier times. TOFLAR should be easily implemented on NSE spectrometers equipped with a chopper system such as IN15 or the planned WASP. (authors)

  19. Time-of-flight and activation experiments on 147Pm and 171Tm for astrophysics

    Science.gov (United States)

    Guerrero, C.; Lerendegui-Marco, J.; Domingo-Pardo, C.; Casanovas, A.; Dressler, R.; Halfon, S.; Heinitz, S.; Kivel, N.; Köster, U.; Paul, M.; Quesada-Molina, J. M.; Schumann, D.; Tarifeño-Saldivia, A.; Tessler, M.; Weissman, L.; Aberle, O.; Andrzejewski, J.; Audouin, L.; Bacak, M.; Balibrea, J.; Barbagallo, M.; Becvar, F.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brown, A.; Caamaño, M.; Calviño, F.; Calviani, M.; Cano-Ott, D.; Cardella, R.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Colonna, N.; Cortés, G.; Cortés-Giraldo, M. A.; Cosentino, L.; Damone, L. A.; Diakaki, M.; Dupont, E.; Durán, I.; Fernández-Domínguez, B.; Ferrari, A.; Ferreira, P.; Finocchiaro, P.; Göbel, K.; García, A. R.; Gawlik, A.; Gilardoni, S.; Glodariu, T.; Gonçalves, I. F.; González, E.; Griesmayer, E.; Gunsing, F.; Harada, H.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Käppeler, F.; Kadi, Y.; Kalamara, A.; Kavrigin, P.; Kimura, A.; Kivel, N.; Kokkoris, M.; Krticka, M.; Kurtulgil, D.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Meo, S. Lo; Lonsdale, S. J.; Macina, D.; Marganiec, J.; Martínez, T.; Masi, A.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Maugeri, E. A.; Mazzone, A.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Musumarra, A.; Negret, A.; Nolte, R.; Oprea, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Porras, I.; Praena, J.; Radeck, D.; Rauscher, T.; Reifarth, R.; Rout, P. C.; Rubbia, C.; Ryan, J. A.; Sabaté-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Smith, A. G.; Sosnin, N. V.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Warren, S.; Weiss, C.; Woods, P. J.; Wright, T.; Žugec, P.

    2017-09-01

    The neutron capture cross section of several key unstable isotopes acting as branching points in the s-process are crucial for stellar nucleosynthesis studies, but they are very challenging to measure due to the difficult production of sufficient sample material, the high activity of the resulting samples, and the actual (n,γ) measurement, for which high neutron fluxes and effective background rejection capabilities are required. As part of a new program to measure some of these important branching points, radioactive targets of 147Pm and 171Tm have been produced by irradiation of stable isotopes at the ILL high flux reactor. Neutron capture on 146Nd and 170Er at the reactor was followed by beta decay and the resulting matrix was purified via radiochemical separation at PSI. The radioactive targets have been used for time-of-flight measurements at the CERN n_TOF facility using the 19 and 185 m beam lines during 2014 and 2015. The capture cascades were detected using a set of four C6D6 scintillators, allowing to observe the associated neutron capture resonances. The results presented in this work are the first ever determination of the resonance capture cross section of 147Pm and 171Tm. Activation experiments on the same 147Pm and 171Tm targets with a high-intensity 30 keV quasi-Maxwellian flux of neutrons will be performed using the SARAF accelerator and the Liquid-Lithium Target (LiLiT) in order to extract the corresponding Maxwellian Average Cross Section (MACS). The status of these experiments and preliminary results will be presented and discussed as well.

  20. Multiple-ion-beam time-of-flight mass spectrometer

    International Nuclear Information System (INIS)

    Rohrbacher, Andreas; Continetti, Robert E.

    2001-01-01

    An innovative approach to increase the throughput of mass spectrometric analyses using a multiple-ion-beam mass spectrometer is described. Two sample spots were applied onto a laser desorption/ionization target and each spot was simultaneously irradiated by a beam of quadrupled Nd:YLF laser radiation (261.75 nm) to produce ions by laser-desorption ionization. Acceleration of the ions in an electric field created parallel ion beams that were focused by two parallel einzel lens systems. After a flight path of 2.34 m, the ions were detected with a microchannel plate-phosphor screen assembly coupled with a charge coupled device camera that showed two resolved ion beams. Time-of-flight mass spectra were also obtained with this detector. Experiments were performed using both metal atom cations (Ti + and Cr + ) produced by laser desorption/ionization and the molecular ions of two different proteins (myoglobin and lysozyme), created by matrix assisted laser desorption/ionization using an excess of nicotinic acid as matrix

  1. Avalanche photodiode based time-of-flight mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Ogasawara, Keiichi, E-mail: kogasawara@swri.edu; Livi, Stefano A.; Desai, Mihir I.; Ebert, Robert W.; McComas, David J.; Walther, Brandon C. [Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238 (United States)

    2015-08-15

    This study reports on the performance of Avalanche Photodiodes (APDs) as a timing detector for ion Time-of-Flight (TOF) mass spectroscopy. We found that the fast signal carrier speed in a reach-through type APD enables an extremely short timescale response with a mass or energy independent <2 ns rise time for <200 keV ions (1−40 AMU) under proper bias voltage operations. When combined with a microchannel plate to detect start electron signals from an ultra-thin carbon foil, the APD comprises a novel TOF system that successfully operates with a <0.8 ns intrinsic timing resolution even using commercial off-the-shelf constant-fraction discriminators. By replacing conventional total-energy detectors in the TOF-Energy system, APDs offer significant power and mass savings or an anti-coincidence background rejection capability in future space instrumentation.

  2. Time Of Flight Detectors: From phototubes to SiPM

    International Nuclear Information System (INIS)

    Laurenti, G.; Levi, G.; Foschi, E.; Guandalini, C.; Quadrani, L.; Sbarra, C.; Zuffa, M.

    2008-01-01

    A sample of Silicon Photomultipliers was tested because they looked promising for future space missions: low consumption, low weight, resistance to radiation damage and insensitivity to magnetic fields. They have been studied in laboratory by means of the same characterization methods adopted to calibrate the fine mesh photomultipliers used by the Time Of Flight of the AMS-02 experiment. A detailed simulation was made to reproduce the SiPM response to the various experimental conditions. A possible counter design has been studied with front end electronics card equipped with SiPMs and Peltier cell for thermoregulation. A proper simulation based on COMSOL Multiphysics package reproduces quite well the Peltier cell nominal cooling capability

  3. Neutron spectrum and dose-equivalent in shuttle flights during solar maximum

    Energy Technology Data Exchange (ETDEWEB)

    Keith, J E; Badhwar, G D; Lindstrom, D J [National Aeronautics and Space Administration, Houston, TX (United States). Lyndon B. Johnson Space Center

    1992-01-01

    This paper presents unambiguous measurements of the spectrum of neutrons found in spacecraft during spaceflight. The neutron spectrum was measured from thermal energies to about 10 MeV using a completely passive system of metal foils as neutron detectors. These foils were exposed to the neutron flux bare, covered by thermal neutron absorbers (Gd) and inside moderators (Bonner spheres). This set of detectors was flown on three U.S. Space Shuttle flights, STS-28, STS-36 and STS-31, during the solar maximum. We show that the measurements of the radioactivity of these foils lead to a differential neutron energy spectrum in all three flights that can be represented by a power law, J(E){approx equal}E{sup -0.765} neutrons cm{sup -2} day {sup -1} MeV{sup -1}. We also show that the measurements are even better represented by a linear combination of the terrestrial neutron albedo and a spectrum of neutrons locally produced in a aluminium by protons, computed by a previous author. We use both approximations to the neutron spectrum to produce a worst case and most probable case for the neutron spectra and the resulting dose-equivalents, computed using ICRP-51 neutron fluence-dose conversion tables. We compare these to the skin dose-equivalents due to charged particles during the same flights. (author).

  4. Characterizing subcritical assemblies with time of flight fixed by energy estimation distributions

    Science.gov (United States)

    Monterial, Mateusz; Marleau, Peter; Pozzi, Sara

    2018-04-01

    We present the Time of Flight Fixed by Energy Estimation (TOFFEE) as a measure of the fission chain dynamics in subcritical assemblies. TOFFEE is the time between correlated gamma rays and neutrons, subtracted by the estimated travel time of the incident neutron from its proton recoil. The measured subcritical assembly was the BeRP ball, a 4.482 kg sphere of α-phase weapons grade plutonium metal, which came in five configurations: bare, 0.5, 1, and 1.5 in iron, and 1 in nickel closed fitting shell reflectors. We extend the measurement with MCNPX-PoliMi simulations of shells ranging up to 6 inches in thickness, and two new reflector materials: aluminum and tungsten. We also simulated the BeRP ball with different masses ranging from 1 to 8 kg. A two-region and single-region point kinetics models were used to model the behavior of the positive side of the TOFFEE distribution from 0 to 100 ns. The single region model of the bare cases gave positive linear correlations between estimated and expected neutron decay constants and leakage multiplications. The two-region model provided a way to estimate neutron multiplication for the reflected cases, which correlated positively with expected multiplication, but the nature of the correlation (sub or superlinear) changed between material types. Finally, we found that the areal density of the reflector shells had a linear correlation with the integral of the two-region model fit. Therefore, we expect that with knowledge of reflector composition, one could determine the shell thickness, or vice versa. Furthermore, up to a certain amount and thickness of the reflector, the two-region model provides a way of distinguishing bare and reflected plutonium assemblies.

  5. Modern techniques of structural neutron diffraction

    International Nuclear Information System (INIS)

    Aksenov, V.L.; )

    1997-01-01

    Modern techniques of neutron diffraction for structural investigations are analyzed. The time-of-flight method and the reverse time-of-flight method are considered briefly. Characteristics of two-crystal and time-of-flight neutron diffractometers are compared. It is pointed that in the future, the great importance will be possessed the development of high-resolution Fourier neutron diffractometers [ru

  6. A design for a high resolution very-low-Q time-of flight diffractometer

    International Nuclear Information System (INIS)

    Hjelm, R. P.

    1998-01-01

    The design of a high resolution view low-Q time of flight diffractometer was motivated by the anticipated need to perform small-angle neutron scattering measurements at far lower momentum transfer and higher precision than currently available at either pulsed or steady state sources. In addition, it was recognized that flexibility in the configuration of the instrument and ease in which data is acquired are important. The design offers two configurations, a high intensity/very low Q geometry employing a focusing mirror and a medium to high Q-precision/low Q configuration using standard pinhole collimation geometry. The quality of the mirror optics is very important to the performance of the high intensity/very low Q configuration. We believe that the necessary technology exists to fabricate the high quality mirror optics required for the instrument

  7. RAMSES - Rapid Measurement and Special Environment time-of-flight Spectrometer

    International Nuclear Information System (INIS)

    Schober, H.; Koza, M.; Mutka, H.; Zbiri, M.; Andersen, K.

    2011-01-01

    Time-of-flight spectrometers are ideally suited to study the dynamics of complex materials as encountered in all domains of current scientific interest ranging from health care, biology, earth and environmental sciences, cultural heritage to energy storage and preservation. Complex materials are often available in samples of small amount, or the scientific questions to study require environments limiting the sample size (e.g., Paris-Edinburgh cells and levitation furnaces). The proposed instrument would be optimized for these conditions offering a very high neutron flux over a small beam cross-section in combination with good resolution and extended dynamical range. The later asks for a wavelength band extending slightly into the thermal region. This is achieved on a cold guide with super-mirror coating. (authors)

  8. Pulse processing routines for neutron time-of-flight data

    CERN Document Server

    Žugec, P; Guerrero, C; Gunsing, F; Vlachoudis, V; Sabate-Gilarte, M; Stamatopoulos, A; Wright, T; Lerendegui-Marco, J; Mingrone, F; Ryan, J A; Warren, S G; Tsinganis, A; Barbagallo, M

    2016-01-01

    A pulse shape analysis framework is described, which was developed for n_TOF-Phase3, the third phase in the operation of the n_TOF facility at CERN. The most notable feature of this new framework is the adoption of generic pulse shape analysis routines, characterized by a minimal number of explicit assumptions about the nature of pulses. The aim of these routines is to be applicable to a wide variety of detectors, thus facilitating the introduction of the new detectors or types of detectors into the analysis framework. The operational details of the routines are suited to the specific requirements of particular detectors by adjusting the set of external input parameters. Pulse recognition, baseline calculation and the pulse shape fitting procedure are described. Special emphasis is put on their computational efficiency, since the most basic implementations of these conceptually simple methods are often computationally inefficient.

  9. Chern Numbers Hiding in Time of Flight Images

    Science.gov (United States)

    Satija, Indubala; Zhao, Erhai; Ghosh, Parag; Bray-Ali, Noah

    2011-03-01

    Since the experimental realization of synthetic magnetic fields in neural ultracold atoms, transport measurement such as quantized Hall conductivity remains an open challenge. Here we propose a novel and feasible scheme to measure the topological invariants, namely the chern numbers, in the time of flight images. We study both the commensurate and the incommensurate flux, with the later being the main focus here. The central concept underlying our proposal is the mapping between the chern numbers and the size of the dimerized states that emerge when the two-dimensional hopping is tuned to the highly anisotropic limit. In a uncoupled double quantum Hall system exhibiting time reversal invariance, only odd-sized dimer correlation functions are non-zero and hence encode quantized spin current. Finally, we illustrate that inspite of highly fragmented spectrum, a finite set of chern numbers are meaningful. Our results are supported by direct numerical computation of transverse conductivity. NBA acknowledges support from a National Research Council postdoctoral research associateship.

  10. Positron Emission Tomography (PET): Towards Time of Flight

    International Nuclear Information System (INIS)

    Karp, Joel

    2004-01-01

    PET is a powerful imaging tool that is being used to study cancer, using a variety of tracers to measure physiological processes including glucose metabolism, cell proliferation, and hypoxia in tumor cells. As the utilization of PET has grown in the last several years, it has become clear that improved lesion detection and quantification are critical goals for cancer studies. Although physical performance of the current generation of PET scanners has improved recently, there are limitations especially for heavy patients where attenuation and scatter effects are increased. We are investigating new scintillation detectors, scanner designs, and image processing algorithms in order to overcome these limitations and improve performance. In particular, we are studying scanner designs that would incorporate scintillators with improved energy and timing resolution. Improved energy resolution helps to reduce scattered radiation, and improved timing resolution makes it feasible to incorporate the time-of-flight information between the two coincident gamma rays into the image reconstruction algorithm, a technique that improves signal-to-noise. Results of recent experiments and computer simulations will be shown to demonstrate these potential improvements.

  11. Distance error correction for time-of-flight cameras

    Science.gov (United States)

    Fuersattel, Peter; Schaller, Christian; Maier, Andreas; Riess, Christian

    2017-06-01

    The measurement accuracy of time-of-flight cameras is limited due to properties of the scene and systematic errors. These errors can accumulate to multiple centimeters which may limit the applicability of these range sensors. In the past, different approaches have been proposed for improving the accuracy of these cameras. In this work, we propose a new method that improves two important aspects of the range calibration. First, we propose a new checkerboard which is augmented by a gray-level gradient. With this addition it becomes possible to capture the calibration features for intrinsic and distance calibration at the same time. The gradient strip allows to acquire a large amount of distance measurements for different surface reflectivities, which results in more meaningful training data. Second, we present multiple new features which are used as input to a random forest regressor. By using random regression forests, we circumvent the problem of finding an accurate model for the measurement error. During application, a correction value for each individual pixel is estimated with the trained forest based on a specifically tailored feature vector. With our approach the measurement error can be reduced by more than 40% for the Mesa SR4000 and by more than 30% for the Microsoft Kinect V2. In our evaluation we also investigate the impact of the individual forest parameters and illustrate the importance of the individual features.

  12. Towards time-of-flight PET with a semiconductor detector

    Science.gov (United States)

    Ariño-Estrada, Gerard; Mitchell, Gregory S.; Kwon, Sun Il; Du, Junwei; Kim, Hadong; Cirignano, Leonard J.; Shah, Kanai S.; Cherry, Simon R.

    2018-02-01

    The feasibility of using Cerenkov light, generated by energetic electrons following 511 keV photon interactions in the semiconductor TlBr, to obtain fast timing information for positron emission tomography (PET) was evaluated. Due to its high refractive index, TlBr is a relatively good Cerenkov radiator and with its wide bandgap, has good optical transparency across most of the visible spectrum. Coupling an SiPM photodetector to a slab of TlBr (TlBr-SiPM) yielded a coincidence timing resolution of 620 ps FWHM between the TlBr-SiPM detector and a LFS reference detector. This value improved to 430 ps FWHM by applying a high pulse amplitude cut based on the TlBr-SiPM and reference detector signal amplitudes. These results are the best ever achieved with a semiconductor PET detector and already approach the performance required for time-of-flight. As TlBr has higher stopping power and better energy resolution than the conventional scintillation detectors currently used in PET scanners, a hybrid TlBr-SiPM detector with fast timing capability becomes an interesting option for further development.

  13. Proton Transfer Time-of-Flight Mass Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Watson, Thomas B. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-03-01

    The Proton Transfer Reaction Mass Spectrometer (PTRMS) measures gas-phase compounds in ambient air and headspace samples before using chemical ionization to produce positively charged molecules, which are detected with a time-of-flight (TOF) mass spectrometer. This ionization method uses a gentle proton transfer reaction method between the molecule of interest and protonated water, or hydronium ion (H3O+), to produce limited fragmentation of the parent molecule. The ions produced are primarily positively charged with the mass of the parent ion, plus an additional proton. Ion concentration is determined by adding the number of ions counted at the molecular ion’s mass-to-charge ratio to the number of air molecules in the reaction chamber, which can be identified according to the pressure levels in the reaction chamber. The PTRMS allows many volatile organic compounds in ambient air to be detected at levels from 10–100 parts per trillion by volume (pptv). The response time is 1 to 10 seconds.

  14. LVGEMS Time-of-Flight Mass Spectrometry on Satellites

    Science.gov (United States)

    Herrero, Federico

    2013-01-01

    NASA fs investigations of the upper atmosphere and ionosphere require measurements of composition of the neutral air and ions. NASA is able to undertake these observations, but the instruments currently in use have their limitations. NASA has extended the scope of its research in the atmosphere and now requires more measurements covering more of the atmosphere. Out of this need, NASA developed multipoint measurements using miniaturized satellites, also called nanosatellites (e.g., CubeSats), that require a new generation of spectrometers that can fit into a 4 4 in. (.10 10 cm) cross-section in the upgraded satellites. Overall, the new mass spectrometer required for the new depth of atmospheric research must fulfill a new level of low-voltage/low-power requirements, smaller size, and less risk of magnetic contamination. The Low-Voltage Gated Electrostatic Mass Spectrometer (LVGEMS) was developed to fulfill these requirements. The LVGEMS offers a new spectrometer that eliminates magnetic field issues associated with magnetic sector mass spectrometers, reduces power, and is about 1/10 the size of previous instruments. LVGEMS employs the time of flight (TOF) technique in the GEMS mass spectrometer previously developed. However, like any TOF mass spectrometer, GEMS requires a rectangular waveform of large voltage amplitude, exceeding 100 V -- that means that the voltage applied to one of the GEMS electrodes has to change from 0 to 100 V in a time of only a few nanoseconds. Such electronic speed requires more power than can be provided in a CubeSat. In the LVGEMS, the amplitude of the rectangular waveform is reduced to about 1 V, compatible with digital electronics supplies and requiring little power.

  15. Time-of-flight PET image reconstruction using origin ensembles

    Science.gov (United States)

    Wülker, Christian; Sitek, Arkadiusz; Prevrhal, Sven

    2015-03-01

    The origin ensemble (OE) algorithm is a novel statistical method for minimum-mean-square-error (MMSE) reconstruction of emission tomography data. This method allows one to perform reconstruction entirely in the image domain, i.e. without the use of forward and backprojection operations. We have investigated the OE algorithm in the context of list-mode (LM) time-of-flight (TOF) PET reconstruction. In this paper, we provide a general introduction to MMSE reconstruction, and a statistically rigorous derivation of the OE algorithm. We show how to efficiently incorporate TOF information into the reconstruction process, and how to correct for random coincidences and scattered events. To examine the feasibility of LM-TOF MMSE reconstruction with the OE algorithm, we applied MMSE-OE and standard maximum-likelihood expectation-maximization (ML-EM) reconstruction to LM-TOF phantom data with a count number typically registered in clinical PET examinations. We analyzed the convergence behavior of the OE algorithm, and compared reconstruction time and image quality to that of the EM algorithm. In summary, during the reconstruction process, MMSE-OE contrast recovery (CRV) remained approximately the same, while background variability (BV) gradually decreased with an increasing number of OE iterations. The final MMSE-OE images exhibited lower BV and a slightly lower CRV than the corresponding ML-EM images. The reconstruction time of the OE algorithm was approximately 1.3 times longer. At the same time, the OE algorithm can inherently provide a comprehensive statistical characterization of the acquired data. This characterization can be utilized for further data processing, e.g. in kinetic analysis and image registration, making the OE algorithm a promising approach in a variety of applications.

  16. Ames collaborative study of cosmic-ray neutrons. II. Low- and mid-latitude flights

    International Nuclear Information System (INIS)

    Stephens, L.D.; McCaslin, J.B.; Smith, A.R.; Thomas, R.H.; Hewitt, J.E.; Hughes, L.

    1978-01-01

    The continuing progress of the Ames Collaborative Study of Cosmic Ray Neutrons is described. Data obtained aboard flights from Hawaii at altitudes of 41,000 and 45,000 feet, and in the range of geomagnetic latitude 17 0 N less than or equal to lambda less than or equal to 21 0 N are reported. Preliminary estimates of neutron spectra were made

  17. Recent developments in time-of-flight PET

    International Nuclear Information System (INIS)

    Vandenberghe, S.; Mikhaylova, E.; D’Hoe, E.; Mollet, P.; Karp, J. S.

    2016-01-01

    While the first time-of-flight (TOF)-positron emission tomography (PET) systems were already built in the early 1980s, limited clinical studies were acquired on these scanners. PET was still a research tool, and the available TOF-PET systems were experimental. Due to a combination of low stopping power and limited spatial resolution (caused by limited light output of the scintillators), these systems could not compete with bismuth germanate (BGO)-based PET scanners. Developments on TOF system were limited for about a decade but started again around 2000. The combination of fast photomultipliers, scintillators with high density, modern electronics, and faster computing power for image reconstruction have made it possible to introduce this principle in clinical TOF-PET systems. This paper reviews recent developments in system design, image reconstruction, corrections, and the potential in new applications for TOF-PET. After explaining the basic principles of time-of-flight, the difficulties in detector technology and electronics to obtain a good and stable timing resolution are shortly explained. The available clinical systems and prototypes under development are described in detail. The development of this type of PET scanner also requires modified image reconstruction with accurate modeling and correction methods. The additional dimension introduced by the time difference motivates a shift from sinogram- to listmode-based reconstruction. This reconstruction is however rather slow and therefore rebinning techniques specific for TOF data have been proposed. The main motivation for TOF-PET remains the large potential for image quality improvement and more accurate quantification for a given number of counts. The gain is related to the ratio of object size and spatial extent of the TOF kernel and is therefore particularly relevant for heavy patients, where image quality degrades significantly due to increased attenuation (low counts) and high scatter fractions. The

  18. Multi-Reflection Time-of-Flight Mass Separation and Spectrometry

    CERN Document Server

    Kreim, Susanne; Wolf, R N

    2014-01-01

    The mass of a nucleus is one of its most fundamental ground-state properties and reveals the strength of nuclear binding. Investigating the binding energy of nuclei with respect to the number of protons and neutrons in a nucleus is important for advancing nuclear theory and increases our understanding of nucleosynthesis in supernovae and neutron stars. Precision mass measurements on radioactive nuclides belong to the state-of-the-art techniques [1, 2]. Presently, four complementary techniques are applied: isochronous and Schottky mass spectrometry in storage rings (IMS and SMS, respectively), magnetic-rigidity time-of-flight (TOF-ρ) measurements, and Penning-trap mass spectrometry (PTMS). With measurement cycles in the sub-ms range, IMS and TOF-Bρ MS are well suited for very short-lived species while offering moderate relative precision on the level of 10−6. A higher precision is achieved by SMS but with the need for measurement times on the order of several seconds. As soon as masses with a relative prec...

  19. A reflecting time-of-flight mass spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Tang, X

    1991-01-01

    The design, construction and operation of a reflecting time-of-flight mass spectrometer and the details of the ion mirror are discussed. The principle of velocity focusing with a single-stage ion mirror and the effect of the acceleration region are discussed. The performance of the reflecting instrument is described. Its detection limit is illustrated by observation of [M + H][sup +] ions from [approximately]5-35 femtomoles of various peptides. The factors that affect the resolution are discussed. The principle and operation of the reflecting instrument as a tandem mass spectrometer is described; this involves correlated detection of neutral and ionized fragments. The efficiency, resolution, sensitivity, and mass determination of daughter ions by this method are discussed. Methods of sample preparation are described. By using a nitrocellulose substrate, organic molecular ions as large as bovine insulin (MW 5733) were detected for the first time with low energy (keV) ion bombardment of a solid surface. Many daughter ion spectra resulting from metastable decay of parent ions have been studied. Secondary ions [(CsI)[sub n]Cs][sup +] with n up to [approximately]50 were detected; all clusters were found to be metastable, with most lifetimes <100 [mu]s, and for n>10 the daughter ions are dominant in the mass spectrum. Peptides of mass up to [approximately]2000 u have been studied with the correlated method; the daughter ion spectra were found to be strongly influenced by the identity of the bound cation (H[sup +], Na[sup +], K[sup +], or Ag[sup +]). Many daughter ions formed by known reactions yield structure and sequence information about the peptides. In addition, the [M + Na][sup +] and [M + Ag][sup +] ions decompose by a previously unreported pathway, namely, rearrangement of a C-terminal carboxyl oxygen onto the daughter ion containing the N-terminus. Both the reflected spectra and daughter ion spectra were found useful in peptide sequencing.

  20. Time-of-Flight Adjustment Procedure for Acoustic Measurements in Structural Timber

    Science.gov (United States)

    Danbiel F. Llana; Guillermo Iñiguez-Gonzalez; Francisco Arriaga; Xiping Wang

    2016-01-01

    The effect of timber length on time-of-flight acoustic longitudinal measurements was investigated on the structural timber of four Spanish species: radiata pine (Pinus radiata D. Don), Scots pine (Pinus sylvestris L.), laricio pine (Pinus nigra Arn.), and maritime pine (Pinus pinaster Ait.). Time-of-flight longitudinal measurements were conducted on 120 specimens of...

  1. Rules for Flight Paths and Time of Flight for Flows in Porous Media with Heterogeneous Permeability and Porosity

    Directory of Open Access Journals (Sweden)

    Lihua Zuo

    2017-01-01

    Full Text Available Porous media like hydrocarbon reservoirs may be composed of a wide variety of rocks with different porosity and permeability. Our study shows in algorithms and in synthetic numerical simulations that the flow pattern of any particular porous medium, assuming constant fluid properties and standardized boundary and initial conditions, is not affected by any spatial porosity changes but will vary only according to spatial permeability changes. In contrast, the time of flight along the streamline will be affected by both the permeability and porosity, albeit in opposite directions. A theoretical framework is presented with evidence from flow visualizations. A series of strategically chosen streamline simulations, including systematic spatial variations of porosity and permeability, visualizes the respective effects on the flight path and time of flight. Two practical rules are formulated. Rule  1 states that an increase in permeability decreases the time of flight, whereas an increase in porosity increases the time of flight. Rule  2 states that the permeability uniquely controls the flight path of fluid flow in porous media; local porosity variations do not affect the streamline path. The two rules are essential for understanding fluid transport mechanisms, and their rigorous validation therefore is merited.

  2. Study of neutron resonances of barium and copper isotopes by the time-of-flight method at low energies (0 to 15 keV); Etude des resonances de neutrons pour les isotopes du baryum et du cuivre par la methode de temps-de-vol a basse energie (0-15 kev)

    Energy Technology Data Exchange (ETDEWEB)

    Chevillon-Pitollat, P L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-01-01

    Resonance parameters of Cu (0-15 keV) and Ba (0-1000 eV) have been determined, using the time-of-flight method. Spin assignment (J = I{+-}1/2) being not possible with usual capture methods, the 'sum coincident' method was used in Ba study. A careful analysis of transmission curves including interference effects between levels of the same spin afforded to assign the J value to the most of Cu resonances. Strength function values (S{sub 0}) for those nuclei I = 3/2 confirm previous results obtained for other nuclei having the same value of spin I = 3/2, i.e. S{sub 0} (J = 2) {approx_equal} 2 S{sub 0} (J = 1). Another result has to be mentioned: total radiative width exhibits large fluctuation for different isotopes of Cu and Ba. Experimental methods, specially the 'sum coincidence' one are described in detail and results are discussed in view of theoretical predictions. (author) [French] Les parametres des resonances de {sup 63}Cu et {sup 65}Cu ont ete determines dans le domaine d'energie de zero a 15 keV et ceux du baryum dans le domaine de zero a 1000 eV. Les methodes habituelles de capture n'etant pas applicables pour trouver la valeur du spin S = I{+-}1/2, la methode 'somme coincidence' fut appliquee pour l'attribution de J aux resonances du baryum tandis qu'une analyse soigneuse des courbes de transmission, tenant compte en particulier des effets d'interference entre niveaux de meme spin permettait de determiner J pour la plupart des resonances du cuivre. Les resultats trouves pour ces differents noyaux de spin I = 3/2 confirment ceux deja trouves pour d'autres noyaux I = 3/2 c'est-a-dire que la valeur de la fonction densite S{sub 0} pour J 2 est deux fois celle pour J = 1. Un autre resultat interessant est la variation de la largeur radiative totale pour les isotopes du cuivre et du baryum. Les methodes experimentales surtout la methode 'somme coincidence' sont decrites en detail et les resultats compares aux predictions theoriques. (auteur)

  3. Inhomogeneous oscillatory electric field time-of-flight mass spectrometer

    International Nuclear Information System (INIS)

    Carrico, J.P.

    1977-01-01

    The mass-to-charge ratio of an ion can be determined from the measurement of its flight time in an inhomogeneous, oscillatory electric field produced by the potential distribution V(x, y, t) = Vsub(DC) + Vsub(AC) cos ωt) (αsub(x)X 2 + αsub(y)Y 2 + αsub(z)Z 2 ). The governing equation of motion is the Mathieu equation. The principle of operation of this novel mass spectrometer is described and results of computer calculations of the flight time and resolution are reported. An experimental apparatus and results and results demonstrating the feasibility of this mass spectrometer principle are described. (author)

  4. Measurement of the time of storage of ultracold neutrons in a magnetic trap

    International Nuclear Information System (INIS)

    Abov, Y.G.; Borovlev, S.P.; Vasil'ev, V.V.; Vladimirskii, V.V.; Mospan, E.N.

    1983-01-01

    The storage time of ultracold neutrons in an axial magnetic trap with a simple singly connected confinement region is measured. It is shown that the storage of the neutrons is due just to the magnetic field. The storage time achieved is tau = 303 +- 37 sec. In a working cycle 3.6 neutrons are accumulated

  5. First Direct Mass Measurements of Nuclides around Z =100 with a Multireflection Time-of-Flight Mass Spectrograph

    Science.gov (United States)

    Ito, Y.; Schury, P.; Wada, M.; Arai, F.; Haba, H.; Hirayama, Y.; Ishizawa, S.; Kaji, D.; Kimura, S.; Koura, H.; MacCormick, M.; Miyatake, H.; Moon, J. Y.; Morimoto, K.; Morita, K.; Mukai, M.; Murray, I.; Niwase, T.; Okada, K.; Ozawa, A.; Rosenbusch, M.; Takamine, A.; Tanaka, T.; Watanabe, Y. X.; Wollnik, H.; Yamaki, S.

    2018-04-01

    The masses of 246Es, 251Fm, and the transfermium nuclei Md-252249 and 254No, produced by hot- and cold-fusion reactions, in the vicinity of the deformed N =152 neutron shell closure, have been directly measured using a multireflection time-of-flight mass spectrograph. The masses of 246Es and 249,250,252Md were measured for the first time. Using the masses of Md,250249 as anchor points for α decay chains, the masses of heavier nuclei, up to 261Bh and 266Mt, were determined. These new masses were compared with theoretical global mass models and demonstrated to be in good agreement with macroscopic-microscopic models in this region. The empirical shell gap parameter δ2 n derived from three isotopic masses was updated with the new masses and corroborates the existence of the deformed N =152 neutron shell closure for Md and Lr.

  6. Sensitivity of peak positions to flight-path parameters in a deep-inelastic scattering neutron TOF spectrometer

    International Nuclear Information System (INIS)

    Gray, E.MacA.; Chatzidimitriou-Dreismann, C.A.; Blach, T.P.

    2012-01-01

    The effects of small changes in flight-path parameters (primary and secondary flight paths, detector angles), and of displacement of the sample along the beam axis away from its ideal position, are examined for an inelastic time-of-flight (TOF) neutron spectrometer, emphasising the deep-inelastic regime. The aim was to develop a rational basis for deciding what measured shifts in the positions of spectral peaks could be regarded as reliable in the light of the uncertainties in the calibrated flight-path parameters. Uncertainty in the length of the primary or secondary flight path has the least effect on the positions of the peaks of H, D and He, which are dominated by the accuracy of the calibration of the detector angles. This aspect of the calibration of a TOF spectrometer therefore demands close attention to achieve reliable outcomes where the position of the peaks is of significant scientific interest and is discussed in detail. The corresponding sensitivities of the position of peak of the Compton profile, J(y), to flight-path parameters and sample position are also examined, focusing on the comparability across experiments of results for H, D and He. We show that positioning the sample to within a few mm of the ideal position is required to ensure good comparability between experiments if data from detectors at high forward angles are to be reliably interpreted.

  7. Spectrometry using the PTB neutron multisphere spectrometer (NEMUS) at flight altitudes and at ground level

    CERN Document Server

    Wiegel, B; Matzke, M; Schrewe, U J; Wittstock, J

    2002-01-01

    Bonner sphere measurements are presented for flights at altitudes of up to 12 km and geomagnetic latitudes between 26 deg.N and 86 deg.N and compared with results obtained by several survey meters. As an example of the natural neutron background near sea level, results from a recent longterm measurement campaign performed at the PTB site using an extended spectrometer are presented. The dependence of neutron fluence and ambient dose equivalent on the atmospheric pressure is demonstrated.

  8. Powder neutron diffractometers

    International Nuclear Information System (INIS)

    Adib, M.

    2002-01-01

    Basic properties and applications of powder neutron Diffractometers are described for optimum use of the continuous neutron beams. These instruments are equipped with position sensitive detectors, neutron guide tubes, and both high intensity and high resolution modes of operation are possible .The principles of both direct and Fourier reverse time-of-flight neutron Diffractometers are also given

  9. Conceptual design of the time-of-flight backscattering spectrometer, MIRACLES, at the European Spallation Source

    International Nuclear Information System (INIS)

    Tsapatsaris, N.; Bordallo, H. N.; Lechner, R. E.; Markó, M.

    2016-01-01

    In this work, we present the conceptual design of the backscattering time-of-flight spectrometer MIRACLES approved for construction at the long-pulse European Spallation Source (ESS). MIRACLES’s unparalleled combination of variable resolution, high flux, extended energy, and momentum transfer (0.2–6 Å"−"1) ranges will open new avenues for neutron backscattering spectroscopy. Its remarkable flexibility can be attributed to 3 key elements: the long-pulse time structure and low repetition rate of the ESS neutron source, the chopper cascade that tailors the moderator pulse in the primary part of the spectrometer, and the bent Si(111) analyzer crystals arranged in a near-backscattering geometry in the secondary part of the spectrometer. Analytical calculations combined with instrument Monte-Carlo simulations show that the instrument will provide a variable elastic energy resolution, δ(ħ ω), between 2 and 32 μeV, when using a wavelength of λ ≈ 6.267 Å (Si(111)-reflection), with an energy transfer range, ħ ω, centered at the elastic line from −600 to +600 μeV. In addition, when selecting λ ≈ 2.08 Å (i.e., the Si(333)-reflection), δ(ħ ω) can be relaxed to 300 μeV and ħ ω from about 10 meV in energy gain to ca −40 meV in energy loss. Finally, the dynamic wavelength range of MIRACLES, approximately 1.8 Å, can be shifted within the interval of 2–20 Å to allow the measurement of low-energy inelastic excitations.

  10. Conceptual design of the time-of-flight backscattering spectrometer, MIRACLES, at the European Spallation Source

    Energy Technology Data Exchange (ETDEWEB)

    Tsapatsaris, N., E-mail: nikolaos.tsapatsaris@esss.se, E-mail: ruep.lechner@gmail.com, E-mail: bordallo@nbi.ku.dk; Bordallo, H. N., E-mail: nikolaos.tsapatsaris@esss.se, E-mail: ruep.lechner@gmail.com, E-mail: bordallo@nbi.ku.dk [Niels Bohr Institute, The University of Copenhagen, Copenhagen 2100 (Denmark); European Spallation Source ERIC, Tunavägen 24, 22100 Lund (Sweden); Lechner, R. E., E-mail: nikolaos.tsapatsaris@esss.se, E-mail: ruep.lechner@gmail.com, E-mail: bordallo@nbi.ku.dk [European Spallation Source ERIC, Tunavägen 24, 22100 Lund (Sweden); Markó, M. [Neutron Spectroscopy Department, Wigner Research Centre for Physics, H-1525 Budapest (Hungary)

    2016-08-15

    In this work, we present the conceptual design of the backscattering time-of-flight spectrometer MIRACLES approved for construction at the long-pulse European Spallation Source (ESS). MIRACLES’s unparalleled combination of variable resolution, high flux, extended energy, and momentum transfer (0.2–6 Å{sup −1}) ranges will open new avenues for neutron backscattering spectroscopy. Its remarkable flexibility can be attributed to 3 key elements: the long-pulse time structure and low repetition rate of the ESS neutron source, the chopper cascade that tailors the moderator pulse in the primary part of the spectrometer, and the bent Si(111) analyzer crystals arranged in a near-backscattering geometry in the secondary part of the spectrometer. Analytical calculations combined with instrument Monte-Carlo simulations show that the instrument will provide a variable elastic energy resolution, δ(ħ ω), between 2 and 32 μeV, when using a wavelength of λ ≈ 6.267 Å (Si(111)-reflection), with an energy transfer range, ħ ω, centered at the elastic line from −600 to +600 μeV. In addition, when selecting λ ≈ 2.08 Å (i.e., the Si(333)-reflection), δ(ħ ω) can be relaxed to 300 μeV and ħ ω from about 10 meV in energy gain to ca −40 meV in energy loss. Finally, the dynamic wavelength range of MIRACLES, approximately 1.8 Å, can be shifted within the interval of 2–20 Å to allow the measurement of low-energy inelastic excitations.

  11. BATS - Backscattering And Time-of-flight Spectrometer

    International Nuclear Information System (INIS)

    Van Eijck, L.; Seydel, T.; Frick, B.; Schober, H.

    2011-01-01

    The new backscattering spectrometer IN16b will go into commissioning end 2011, providing in its final state about ten times higher count rate than its predecessor, IN16. Here we propose to increase its dynamic range by a factor of 7 with the TOF mode extension, BATS. This will make IN16b the leading high resolution backscattering spectrometer for incoherent quasi-elastic and inelastic neutron scattering; it will be competitive to the coarser resolution inverted geometry backscattering spectrometers that are being brought online at spallation sources. The increased dynamic range will extend the scope of science addressed on IN16b, generating considerable potential in fields such as the hydrogen economy (proton conduction, fuel cells, hydrogen storage), soft matter, biology and nano-science (nano-scale confinement, functionalized polymers). Such a large impact can be achieved using only a moderate investment. (authors)

  12. Inspection of CF188 composite flight control surfaces with neutron radiography

    International Nuclear Information System (INIS)

    Lewis, W.J.; Bennett, L.G.I.; Mullin, S.K.

    1996-01-01

    At the Royal Military College of Canada's SLOWPOKE-2 Facility, a neutron radiography facility has been designed and installed using a small (20kWth), pool-type research reactor called the SLOWPOKE-2 (Safe Low Power c(K)ritical Experiment) as the neutron source. Since then, the research has continued along two fronts: developing applications and improving the quality of the neutron beam. The most interesting applications investigated to date has been the inspection of various metal ceramic composites and the inspection of the composite flight control surfaces of some of the CF188 Hornet aircraft. As part of the determination of the integrity of the aircraft, it was decided to inspect an aircraft with the highest flight house using both X- and neutron radiography. The neutron radiography and, to a lesser extent, X-radiography inspections completed at McClellan AFB revealed 93 anomalies. After returning to Canada, the component with the greatest structural significance, namely the right hand rudder from the vertical stabilizer, was removed from the aircraft and put through a rigorous program of numerous NDT inspections, including X-radiography (film and real-time), eddy current, ultrasonics (through transmission and pitch-catch), infrared thermography, and neutron radiography. Therefore, of all the techniques investigated, only through transmission ultrasonics and neutron radiography were able to identify large areas of hydration. However, only neutron radiography could identify the small areas of moisture and hydration. Given the structural significance of the flight control surfaces in modern fighter aircraft, even the smallest amounts of hydration could potentially lead to catastrophic results

  13. Physical design of time-of-flight mass spectrometer in energetic cluster impact deposition apparatus

    International Nuclear Information System (INIS)

    Yu Guoqing; Shi Ying; Chen Jingsheng; Zhu Dezhang; Pan Haochang; Xu Hongjie

    1999-01-01

    The principle and physical design of the time-of-flight mass spectrometer equipped in the energetic cluster impact deposition apparatus are introduced. Some problems existed in experiments and their solutions are also discussed

  14. Time-of-flight trigger based on the use of the time-to-amplitude converter

    International Nuclear Information System (INIS)

    Ladygin, V.P.; Man'yakov, P.K.; Reznikov, S.G.

    2000-01-01

    The method of the time-of-flight trigger realization based on the use of the time-to-amplitude converter is described. Such a trigger has a short decision time and high efficiency of the useful event selection. (author)

  15. Miniature Time of Flight Mass Spectrometer for Space and Extraterrestrial Applications, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The PI has developed a miniature time-of-flight mass spectrometer (TOF-MS), which can be op-timized for space and extraterrestrial applications, by using a...

  16. Neutron-induced single event upsets in static RAMS observed at 10 km flight altitude

    International Nuclear Information System (INIS)

    Olsen, J.; Becher, P.E.; Fynbo, P.B.; Raaby, P. Schultz, J.

    1993-01-01

    Neutron induced single event upsets (SEUs) in static memory devices (SRAMs) have so far been seen only in laboratory environments. The authors report observations of 14 neutron induced SEUs at commercial aircraft flight altitudes as well. The observed SEU rate at 10 km flight altitude based on exposure of 160 standard 256 Kbit CMOS SRAMs is 4.8 · 10 -8 upsets/bit/day. In the laboratory 117 SRAMs of two different brands were irradiated with fast neutrons from a Pu-Be source. A total of 176 SEUs have been observed, among these are two SEU pairs. The upset rates from the laboratory tests are compared to those found in the airborne SRAMS

  17. Single view reflectance capture using multiplexed scattering and time-of-flight imaging

    OpenAIRE

    Zhao, Shuang; Velten, Andreas; Raskar, Ramesh; Bala, Kavita; Naik, Nikhil Deepak

    2011-01-01

    This paper introduces the concept of time-of-flight reflectance estimation, and demonstrates a new technique that allows a camera to rapidly acquire reflectance properties of objects from a single view-point, over relatively long distances and without encircling equipment. We measure material properties by indirectly illuminating an object by a laser source, and observing its reflected light indirectly using a time-of-flight camera. The configuration collectively acquires dense angular, but l...

  18. First Isochronous Time-of-Flight Mass Measurements of Short-Lived Projectile Fragments in the ESR

    International Nuclear Information System (INIS)

    Stadlmann, J.; Geissel, H.; Hausmann, M.; Nolden, F.; Radon, T.; Schatz, H.; Scheidenberger, C.; Attallah, F.; Beckert, K.; Bosch, F.; Falch, M.; Franczak, B.; Franzke, B.; Kerscher, Th.; Klepper, O.; Kluge, H.J.; Kozhuharov, C.; Loebner, K.E.G.; Muenzenberg, G.; Novikov, Yu.N.; Steck, M.; Sun, Z.; Suemmerer, K.; Weick, H.; Wollnik, H.

    2000-01-01

    A new method for precise mass measurements of short-lived hot nuclei is presented. These nuclei were produced via projectile fragmentation, separated with the FRS and injected into the storage ring ESR being operated in the isochronous mode. The revolution time of the ions is measured with a time-of-flight detector sensitive to single particles. This new method allows access to exotic nuclei with half-lives in the microsecond region. First results from this novel method obtained with measurements on neutron-deficient fragments of a chromium primary beam with half-lives down to 50 ms are reported. A precision of deltam/m ≤ 5 · 10 -6 has been achieved

  19. A magnetic particle time-of-flight (MagPTOF) diagnostic for measurements of shock- and compression-bang time at the NIF (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Rinderknecht, H. G., E-mail: hgr@mit.edu; Sio, H.; Frenje, J. A.; Gatu Johnson, M.; Zylstra, A. B.; Sinenian, N.; Rosenberg, M. J.; Li, C. K.; Sèguin, F. H.; Petrasso, R. D. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Magoon, J.; Agliata, A.; Shoup, M.; Glebov, V. U.; Hohenberger, M.; Stoeckl, C.; Sangster, T. C. [Laboratory for Laser Energetics, Rochester, New York 14623 (United States); Ayers, S.; Bailey, C. G.; Rygg, J. R. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

    2014-11-15

    A magnetic particle time-of-flight (MagPTOF) diagnostic has been designed to measure shock- and compression-bang time using D{sup 3}He-fusion protons and DD-fusion neutrons, respectively, at the National Ignition Facility (NIF). This capability, in combination with shock-burn weighted areal density measurements, will significantly constrain the modeling of the implosion dynamics. This design is an upgrade to the existing particle time-of-flight (pTOF) diagnostic, which records bang times using DD or DT neutrons with an accuracy better than ±70 ps [H. G. Rinderknecht et al., Rev. Sci. Instrum. 83, 10D902 (2012)]. The inclusion of a deflecting magnet will increase D{sup 3}He-proton signal-to-background by a factor of 1000, allowing for the first time simultaneous measurements of shock- and compression-bang times in D{sup 3}He-filled surrogate implosions at the NIF.

  20. A magnetic particle time-of-flight (MagPTOF) diagnostic for measurements of shock- and compression-bang time at the NIF (invited).

    Science.gov (United States)

    Rinderknecht, H G; Sio, H; Frenje, J A; Magoon, J; Agliata, A; Shoup, M; Ayers, S; Bailey, C G; Gatu Johnson, M; Zylstra, A B; Sinenian, N; Rosenberg, M J; Li, C K; Sèguin, F H; Petrasso, R D; Rygg, J R; Kimbrough, J R; Mackinnon, A; Bell, P; Bionta, R; Clancy, T; Zacharias, R; House, A; Döppner, T; Park, H S; LePape, S; Landen, O; Meezan, N; Robey, H; Glebov, V U; Hohenberger, M; Stoeckl, C; Sangster, T C; Li, C; Parat, J; Olson, R; Kline, J; Kilkenny, J

    2014-11-01

    A magnetic particle time-of-flight (MagPTOF) diagnostic has been designed to measure shock- and compression-bang time using D(3)He-fusion protons and DD-fusion neutrons, respectively, at the National Ignition Facility (NIF). This capability, in combination with shock-burn weighted areal density measurements, will significantly constrain the modeling of the implosion dynamics. This design is an upgrade to the existing particle time-of-flight (pTOF) diagnostic, which records bang times using DD or DT neutrons with an accuracy better than ±70 ps [H. G. Rinderknecht et al., Rev. Sci. Instrum. 83, 10D902 (2012)]. The inclusion of a deflecting magnet will increase D(3)He-proton signal-to-background by a factor of 1000, allowing for the first time simultaneous measurements of shock- and compression-bang times in D(3)He-filled surrogate implosions at the NIF.

  1. Highly charged ion based time-of-flight emission microscope

    International Nuclear Information System (INIS)

    Hamza, Alex V.; Barnes, Alan V.; Magee, Ed; Newman, Mike; Schenkel, Thomas; McDonald, Joseph W.; Schneider, Dieter H.

    2000-01-01

    An emission microscope using highly charged ions as the excitation source has been designed, constructed, and operated. A novel ''acorn'' objective lens has been used to simultaneously image electron and secondary ion emission. A resistive anode-position sensitive detector is used to determine the x-y position and time of arrival of the secondary events at the microscope image plane. Contrast in the image can be based on the intensity of the electron emission and/or the presence of particular secondary ions. Spatial resolution of better than 1 μm and mass resolution m/Δm of better than 400 were demonstrated. Background rejection from uncorrelated events of greater than an order of magnitude is also achieved. (c) 2000 American Institute of Physics

  2. Analyzing Gait Using a Time-of-Flight Camera

    DEFF Research Database (Denmark)

    Jensen, Rasmus Ramsbøl; Paulsen, Rasmus Reinhold; Larsen, Rasmus

    2009-01-01

    An algorithm is created, which performs human gait analysis using spatial data and amplitude images from a Time-of-flight camera. For each frame in a sequence the camera supplies cartesian coordinates in space for every pixel. By using an articulated model the subject pose is estimated in the depth...... map in each frame. The pose estimation is based on likelihood, contrast in the amplitude image, smoothness and a shape prior used to solve a Markov random field. Based on the pose estimates, and the prior that movement is locally smooth, a sequential model is created, and a gait analysis is done...... on this model. The output data are: Speed, Cadence (steps per minute), Step length, Stride length (stride being two consecutive steps also known as a gait cycle), and Range of motion (angles of joints). The created system produces good output data of the described output parameters and requires no user...

  3. [Separation and identification of bovine lactoferricin by high performance liquid chromatography-matrix-assisted laser desorption/ionization time of flight/ time of flight mass spectrometry].

    Science.gov (United States)

    An, Meichen; Liu, Ning

    2010-02-01

    A high performance liquid chromatography-matrix-assisted laser desorption/ionization time of flight/time of flight mass spectrometry (HPLC-MALDI-TOF/TOF MS) method was developed for the separation and identification of bovine lactoferricin (LfcinB). Bovine lactoferrin was hydrolyzed by pepsin and then separated by ion exchange chromatography and reversed-phase liquid chromatography (RP-LC). The antibacterial activities of the fractions from RP-LC separation were determined and the protein concentration of the fraction with the highest activity was measured, whose sequence was indentified by MALDI-TOF/TOF MS. The relative molecular mass of LfcinB was 3 124.89 and the protein concentration was 18.20 microg/mL. The method of producing LfcinB proposed in this study has fast speed, high accuracy and high resolution.

  4. Potential advantages of a cesium fluoride scintillator for a time-of-flight positron camera

    International Nuclear Information System (INIS)

    Allemand, R.; Gresset, C.; Vacher, J.

    1980-01-01

    In order to improve the quality of positron tomographic imaging, a time-of-flight technique combined with a classical reconstruction method has been investigated. The decay time of NaI(Tl) and bismuth germanate (BGO) scintillators is too long for this application, and efficiency of the plastic scintillators is too low. Cesium fluoride appears to be a very promising detector material. This paper presents preliminary results obtained with a time-of-flight technique using CsF scintillators. The expected advantages were realized

  5. Computationally effective solution of the inverse problem in time-of-flight spectroscopy

    DEFF Research Database (Denmark)

    Kamran, Faisal; Abildgaard, Otto Højager Attermann; Subash, Arman Ahamed

    2015-01-01

    Photon time-of-flight (PTOF) spectroscopy enables the estimation of absorption and reduced scattering coefficients of turbid media by measuring the propagation time of short light pulses through turbid medium. The present investigation provides a comparison of the assessed absorption and reduced...

  6. Dead time of different neutron detectors associated with a pulsed electronics with current collection

    International Nuclear Information System (INIS)

    Bacconnet, Eugene; Duchene, Jean; Duquesne, Henry; Schmitt, Andre

    1968-01-01

    After having outlined that the development of fast neutron reactor physics, notably kinetics, requires highly efficient neutron detectors and pulse measurement chains able to cope with high counting rates, the authors report the measurement of dead time of various neutron detectors which are used in the experimental study of fast neutron reactors. They present the SAITB 1 electronic measurement set, its components, its general characteristics, the protected connection between the detector and the electronics. They present and report the experiment: generalities about detector location and measurements, studied detectors (fission chambers, boron counters), and report the exploitation of the obtained results (principle, data, high-threshold counting gain) [fr

  7. Neutron PSDs for the next generation of spallation neutron sources

    CERN Document Server

    Eijk, C W

    2002-01-01

    A review of R and D for neutron PSDs to be used at anticipated new spallation neutron sources: the Time-of-Flight system facility, European Spallation Source, Spallation Neutron Source and Neutron Arena, is presented. The gas-filled detectors, scintillation detectors and hybrid systems are emphasized.

  8. Observation of pulsed neutron Ramsey resonance

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, Y. [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba Ibaraki 305-0801 (Japan)]. E-mail: yasuhiro.masuda@kek.jp; Skoy, V. [Joint Institute for Nuclear Reasearch, 141980 Dubna, Moscow Region (Russian Federation); Ino, T. [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba Ibaraki 305-0801 (Japan); Jeong, S.C. [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba Ibaraki 305-0801 (Japan); Watanabe, Y. [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba Ibaraki 305-0801 (Japan)

    2007-07-15

    A Ramsey resonance for pulsed neutrons was observed. The separated oscillatory fields for nuclear magnetic resonance were synchronized with a neutron pulse, and then the Ramsey resonance was observed as a function of the neutron velocity. The phase of one of the oscillatory fields was modulated as a function of the neutron time of flight for a neutron velocity measurement.

  9. First Measurement of Reaction-in-Flight Neutrons at the National Ignition Facility

    Science.gov (United States)

    Tonchev, A.; Becker, J.; Bleuel, D.; Bionta, R.; Fortner, D.; Henry, E.; Khater, H.; Shaughnessy, D.; Schnider, D.; Stoeffl, W.; Yeamans, C.; Boswell, M.; Bredeweg, T.; Grim, G.; Jungman, G.; Fowler, M.; Hayes, A.; Obst, A.; Rundberg, R.; Schulz, A.; Wilhelmy, J.; Tornow, W.; Bhike, M.; Howell, C.; Gooden, M.; LLNL/LANL/TUNL Collaboration

    2013-10-01

    The first measurement of reaction-in-flight (RIF) neutrons, also known as tertiary neutrons, has been performed at the National Ignition Facility (NIF) using an activation technique. Thulium foils positioned at 50 cm from the burning deuterium-tritium (DT) capsule have been exposed to the characteristic DT neutron spectrum. The high-energy part of these neutrons with energies above 15.0 MeV can produce 167Tm via the 169Tm(n,3n) reaction. The 208-keV γ-ray, emitted from the decay of 167Tm with a half-life of 9.2 days, has been measured using two clover detectors. The first preliminary result implies that the ratio of RIF neutrons (En > 15.0 MeV) versus the total neutrons is 1 × 10 -4 +/- 3 × 10 -5. The important implication of these measurements on our knowledge of the charged-particle stopping power in strongly coupled quantum-degenerate plasma will be presented. This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344.

  10. A Time-of-Flight System for Low Energy Charged Particles

    Science.gov (United States)

    Giordano, Micheal; Sadwick, Krystalyn; Fletcher, Kurt; Padalino, Stephen

    2013-10-01

    A time-of-flight system has been developed to measure the energy of charged particles in the keV range. Positively charged ions passing through very thin carbon films mounted on grids generate secondary electrons. These electrons are accelerated by a -2000 V grid bias towards a grounded channeltron electron multiplier (CEM) which amplifies the signal. Two CEM detector assemblies are mounted 23.1 cm apart along the path of the ions. An ion generates a start signal by passing through the first CEM and a stop signal by passing through the second. The start and stop signals generate a time-of-flight spectrum via conventional electronics. Higher energy alpha particles from radioactive sources have been used to test the system. This time-of-flight system will be deployed to measure the energies of 15 to 30 keV ions produced by a duoplasmatron ion source that is used to characterize ICF detectors.

  11. Dual cascade time-of-flight mass spectrometer basing on electrostatic mirrors with two dimensional fields

    International Nuclear Information System (INIS)

    Glikman, L. G.; Goloskokov, Yu. V.; Karetskaya, S.P.; Mit', A.G.

    1999-01-01

    In the report [1] we have suggested the scheme of time-of-flight spectrometer containing two electrostatic mirrors with two dimensional field that doesn't depend on one of the Cartesian coordinates). In the articles [2,3] there have been found conditions for obtaining high quality of time-of-flight and spatial focusing. One of basic advantages of this scheme - is availability of intermediate stigmatic image. In the plane where this image is it's possible to place controlled diaphragm that limits ion scatter along the energy if the scatter is too large. With the help of this diaphragm at the spectrometer you can register mass spectrum with the selected energy. Good focusing quality allows reducing of initial ion energy by this increasing the time of their flight and thus analyzers resolving ability. Ion source and receiver are spaced at rather a long distances. This can be useful to solve some practical tasks

  12. Neutron scattering. Experiment manuals

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: The thermal triple axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, neutron polarization analysis with tht time-of-flight spectrometer DNS, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering with the KWS-1 and KWS-2 diffractometers, the very-small-angle neutron scattering diffractrometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  13. Neutron scattering. Experiment manuals

    International Nuclear Information System (INIS)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner

    2010-01-01

    The following topics are dealt with: The thermal triple axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, neutron polarization analysis with tht time-of-flight spectrometer DNS, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering with the KWS-1 and KWS-2 diffractometers, the very-small-angle neutron scattering diffractrometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  14. The IPNS rietveld analysis software package for TOF [time-of-flight] powder diffraction data: Recent developments

    International Nuclear Information System (INIS)

    Rotella, F.J.; Richardson, J.W. Jr.

    1987-01-01

    A system of FORTRAN programs for the analysis of time-of-flight (TOF) neutron powder diffraction data via the Rietveld method at IPNS has been modified recently, making it possible to analyze data that exhibit diffraction maxima broadened due to anisotropic strain and that can be modeled by individual atomic anharmonic thermal vibrations. The observation of noncrystalline scattering in data from some powder samples has led to the development of software to fit such scattering by a function related to a radial distribution function through Fourier-filtering techniques. The ''user friendliness'' of the IPNS Rietveld package has been enhanced by the development of ''RIETVELD,'' a menu-based VAX/VMS command language routine for interactive file manipulation and program execution

  15. Comparison of detector materials for time-of-flight positron tomography

    International Nuclear Information System (INIS)

    Derenzo, S.E.

    1982-06-01

    Knowledge of detection efficiency and timing resolution is essential when comparing detector materials for time-of-flight positron tomography. We present results of Monte Carlo calculations of the detection efficiency of plastic, lead loaded plastic, NaI(T1), liquid xenon, bismuth germanate (BGO), CsF, BaF 2 , Ge, and HgI 2 for 511 keV photons. We also use recently published values of timing resolution for these detector materials to tabulate the quantity (efficiency) 2 /(time resolution) which is a measure of the relative sensitivity for time of flight positron tomography

  16. Design, construction, characterization, and use of a detector to measure time of flight of cosmic rays

    Science.gov (United States)

    Araujo, A. C.; Felix, J.

    2017-01-01

    In the study of cosmic rays, measurements of time of flight and momentum have been used to identify incident particles from its physical properties, like mass. In this document we present the design, construction, characterization, and operation of a detector to measure time of flight of cosmic rays. The device is comprised of three small plates of plastic scintillator arranged in vertical straight line, coupled to one photomultiplier tube. The analogical output has been connected to a data acquisition system to obtain the number of digital pulses per millisecond. We present details of design, construction, operation, and preliminary results.

  17. Time of flight and range of the motion of a projectile in a constant gravitational field

    Directory of Open Access Journals (Sweden)

    P. A. Karkantzakos

    2009-01-01

    Full Text Available In this paper we study the classical problem of the motion of a projectile in a constant gravitational field under the influenceof a retarding force proportional to the velocity. Specifically, we express the time of flight, the time of fall and the range ofthe motion as a function of the constant of resistance per unit mass of the projectile. We also prove that the time of fall isgreater than the time of rise with the exception of the case of zero constant of resistance where we have equality. Finally weprove a formula from which we can compute the constant of resistance per unit mass of the projectile from time of flight andrange of the motion when the acceleration due to gravity and the initial velocity of the projectile are known.

  18. Flowering time of butterfly nectar food plants is more sensitive to temperature than the timing of butterfly adult flight.

    Science.gov (United States)

    Kharouba, Heather M; Vellend, Mark

    2015-09-01

    1. Variation among species in their phenological responses to temperature change suggests that shifts in the relative timing of key life cycle events between interacting species are likely to occur under climate warming. However, it remains difficult to predict the prevalence and magnitude of these shifts given that there have been few comparisons of phenological sensitivities to temperature across interacting species. 2. Here, we used a broad-scale approach utilizing collection records to compare the temperature sensitivity of the timing of adult flight in butterflies vs. flowering of their potential nectar food plants (days per °C) across space and time in British Columbia, Canada. 3. On average, the phenology of both butterflies and plants advanced in response to warmer temperatures. However, the two taxa were differentially sensitive to temperature across space vs. across time, indicating the additional importance of nontemperature cues and/or local adaptation for many species. 4. Across butterfly-plant associations, flowering time was significantly more sensitive to temperature than the timing of butterfly flight and these sensitivities were not correlated. 5. Our results indicate that warming-driven shifts in the relative timing of life cycle events between butterflies and plants are likely to be prevalent, but that predicting the magnitude and direction of such changes in particular cases is going to require detailed, fine-scale data. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

  19. Time-of-Flight Measurement of the Speed of Sound in a Metal Bar

    Science.gov (United States)

    Ganci, Salvatore

    2016-01-01

    A simple setup was designed for a "time-of-flight" measurement of the sound speed in a metal bar. The experiment requires low cost components and is very simple to understand by students. A good use of it is as a demonstration experiment.

  20. Four-Spot Time-Of-Flight Laser Anemometer For Turbomachinery

    Science.gov (United States)

    Wernet, Mark P.; Skoch, Gary J.

    1995-01-01

    Two-color, four-spot time-of-flight laser anemometer designed for measuring flow velocity within narrow confines of small centrifugal compressor. Apparatus well suited for measuring fast (typical speeds 160 to 700 m/s), highly turbulent gas flows in turbomachinery. Other potential applications include measurement of gas flows in pipelines and in flows from explosions.

  1. arXiv Performance of the ALICE Time-Of-Flight detector at the LHC

    CERN Document Server

    INSPIRE-00531272

    The ALICE Time-Of-Flight (TOF) detector at LHC is based on the Multigap Resistive Plate Chambers (MRPCs). The TOF performance during LHC Run 2 is here reported. Particular attention is given to the improved time resolution reached by TOF detector of $56$ ps, with the consequently improved particle identification capabilities.

  2. A fast preamplifier concept for SiPM-based time-of-flight PET detectors

    NARCIS (Netherlands)

    Huizenga, J.; Seifert, S.; Schreuder, F.; Dendooven, P.; Löhner, H.; Vinke, R.; Schaart, D. R.; van Dam, H.T.

    2012-01-01

    Silicon photomultipliers (SiPMs) offer high gain and fast response to light, making them interesting for fast timing applications such as time-of-flight (TOF) PET. To fully exploit the potential of these photosensors, dedicated preamplifiers that do not deteriorate the rise time and signal-to-noise

  3. Sub-nanosecond time-of-flight for segmented silicon detectors

    International Nuclear Information System (INIS)

    Souza, R.T. de; Alexander, A.; Brown, K.; Floyd, B.; Gosser, Z.Q.; Hudan, S.; Poehlman, J.; Rudolph, M.J.

    2011-01-01

    Development of a multichannel time-of-flight system for readout of a segmented, ion-passivated, ion-implanted silicon detector is described. This system provides sub-nanosecond resolution (δt∼370ps) even for low energy α particles which deposit E≤7.687MeV in the detector.

  4. Plant Leaf Imaging using Time of Flight Camera under Sunlight, Shadow and Room Conditions

    DEFF Research Database (Denmark)

    Kazmi, Wajahat; Foix, Sergi; Alenya, Guillem

    2012-01-01

    In this article, we analyze the effects of ambient light on Time of Flight (ToF) depth imaging for a plant's leaf in sunlight, shadow and room conditions. ToF imaging is sensitive to ambient light and we try to find the best possible integration times (IT) for each condition. This is important in...

  5. Processing of acquisition data for a time of flight positron tomograph

    International Nuclear Information System (INIS)

    Robert, G.

    1987-10-01

    After a review of basic principles concerning the time of flight positron tomography, the LETI positron tomograph is briefly described. For performance optimization (acquisition, calibration, image reconstruction), various specialized operators have been designed: the realization of the acquisition system is presented [fr

  6. Analysis of gait using a treadmill and a Time-of-flight camera

    DEFF Research Database (Denmark)

    Jensen, Rasmus Ramsbøl; Paulsen, Rasmus Reinhold; Larsen, Rasmus

    2009-01-01

    We present a system that analyzes human gait using a treadmill and a Time-of-flight camera. The camera provides spatial data with local intensity measures of the scene, and data are collected over several gait cycles. These data are then used to model and analyze the gait. For each frame...

  7. Data acquisition system for a positron tomograph using time-of-flight information

    International Nuclear Information System (INIS)

    Bertin, Francois.

    1981-12-01

    Progress in nuclear instrumentation has led to the development of scintillators much faster than the NaI crystal traditionally used in nuclear medicine. As a result it is now possible to measure time-of-flight, i.e. the time between the arrival of two γ rays emitted in coincidence on two detectors. With this extra information the β + annihilation site may be located. The introduction of time-of-flight in tomographic techniques called for research along two lines: - ''theoretical'' research leading to the creation of a new image reconstruction algorithm taking into account time-of-flight information - applied research leading to the development of an efficient measurement line and sophisticated data acquisition and processing electronics. This research has been carried out at LETI and is briefly outlined in chapter I. Chapter II shows how the introduction of time-of-flight and the modification of the reconstruction algorithm complicate the electronic and informatic equipment of the tomograph. Several acquisition and processing strategies are proposed, then the need to use an intermediate mass storage and hence to design a complex acquisition operator is demonstrated. Chapter III examines the structure of the acquisition operator and the resulting block diagram is presented in detail in chapter IV [fr

  8. BGO as a hybrid scintillator / Cherenkov radiator for cost-effective time-of-flight PET

    NARCIS (Netherlands)

    Brunner, S.E.K.; Schaart, D.R.

    2017-01-01

    Due to detector developments in the last decade, the time-of-flight (TOF) method is now commonly used to improve the quality of positron emission tomography (PET) images. Clinical TOF-PET systems based on L(Y)SO:Ce crystals and silicon photomultipliers (SiPMs) with coincidence resolving times

  9. A position-sensitive start detector for time-of-flight measurement

    International Nuclear Information System (INIS)

    Ikezoe, Hiroshi; Shikazono, Naomoto; Isoyama, Goro.

    1978-08-01

    A position-sensitive start detector for a time-of-flight measurement is described. In this detector microchannel plates were used to obtain time and position signals simultaneously. A time resolution of 121 psec FWHM and a position resolution of 0.28 mm FWHM were obtained for α-particles from an 241 Am source. (auth.)

  10. IN5 Polarisation Option (IPOP) and HIgh FIeld Magnet Option (HIFIMO) for the IN5 time-of-flight spectrometer

    International Nuclear Information System (INIS)

    Ollivier, J.; Mutka, H.

    2011-01-01

    The new secondary spectrometer for the cold neutron time-of-flight (ToF) instrument IN5 was built with non-magnetic material, keeping in mind the upgrade option of polarisation analysis (PA) and the possibility of applying high continuous magnetic fields. The refurbished instrument has a high incident flux and elevated count-rate and offers a unique opportunity for applying polarised neutron methods for high resolution inelastic scattering, including single crystal investigations. On IN5 the polarised option would use the PASTIS concept of three sets of compact perpendicular coils (see the PANTHER proposal) allowing XYZPA and a 3 He analyser banana. As for high magnetic fields: a magnet suitable for ToF instruments must place a minimal amount of material in the incoming and outgoing beams and provide a large asymmetric view towards the detectors. An homogeneous field area of about 20 mm diameter over 30 mm height is also required. There is a size constraint set by the 800 mm diameter sample chamber and the optimal angular acceptance towards the detectors is -12 degrees / +135 degrees in the equatorial plane and +/- 22 degrees in the vertical direction

  11. Time of flight diffraction technique and applications for retaining rings and turbine discs

    International Nuclear Information System (INIS)

    Ashwin, P.

    1990-01-01

    During recent times the term Time of Flight has become a popular phrase in ultrasonic terminology. It is true to say that since ultrasonic energy was first applied for NDE applications, we have used the time of flight to measure the material thickness and establish the presence of discontinuities in metals and other materials. However, as digital ultrasonic systems have evolved we have added new terminology to the field of nondestructive testing, such that phrases as Time of Flight are often misunderstood or over used. Conventional ultrasonic practice (meaning code based ultrasonic inspection) is in most reliant on the measurement of the reflected amplitude response to establish the presence and size of material discontinuities, where the time of flight is the measurement of the ultrasound as it travels to and from the reflector. This industry standard technique has on many occasions been questioned in terms of its value, especially during defect sizing applications. To address the known limitations of amplitude based sizing criteria, a new technique was developed referred to as Time Of Flight Diffraction -TOFD. Instead of using the amount of ultrasonic energy reflected by a discontinuity, TOFD relies on an aspect of ultrasonics that until more recently has been ignored or overlooked. This is the phenomena of diffracted ultrasonic energy, Using diffracted energy it is possible to more accurately measure the size of a defect. More recently the technique has been used for the detection of defects, where due to the imaging capabilities of the instrumentation used, TOFD has illustrated the presence of defects which could not be identified by other ultrasonic methods

  12. Ultrasonic divergent-beam scanner for time-of-flight tomography with computer evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Glover, G H

    1978-03-02

    The rotatable ultrasonic divergent-beam scanner is designed for time-of-flight tomography with computer evaluation. With it there can be measured parameters that are of importance for the structure of soft tissues, e.g. time as a function of the velocity distribution along a certain path of flight(the method is analogous to the transaxial X-ray tomography). Moreover it permits to perform the quantitative measurement of two-dimensional velocity distributions and may therefore be applied to serial examinations for detecting cancer of the breast. As computers digital memories as well as analog-digital-hybrid systems are suitable.

  13. Reaction-in-flight neutrons as a signature for shell mixing in National Ignition Facility capsules

    International Nuclear Information System (INIS)

    Hayes, A. C.; Bradley, P. A.; Grim, G. P.; Jungman, Gerard; Wilhelmy, J. B.

    2010-01-01

    Analytic calculations and results from computational simulations are presented that suggest that reaction-in-flight (RIF) neutrons can be used to diagnose mixing of the ablator shell material into the fuel in deuterium-tritium (DT) capsules designed for the National Ignition Facility (NIF) [J. A. Paisner, J. D. Boyes, S. A. Kumpan, W. H. Lowdermilk, and M. S. Sorem, Laser Focus World 30, 75 (1994)]. Such mixing processes in NIF capsules are of fundamental physical interest and can have important effects on capsule performance, quenching the total thermonuclear yield. The sensitivity of RIF neutrons to hydrodynamical mixing arises through the dependence of RIF production on charged-particle stopping lengths in the mixture of DT fuel and ablator material. Since the stopping power in the plasma is a sensitive function of the electron temperature and density, it is also sensitive to mix. RIF production scales approximately inversely with the degree of mixing taking place, and the ratio of RIF to down-scattered neutrons provides a measure of the mix fraction and/or the mixing length. For sufficiently high-yield capsules, where spatially resolved RIF images may be possible, neutron imaging could be used to map RIF images into detailed mix images.

  14. Reaction-in-flight neutrons as a test of stopping power in degenerate plasmas

    Science.gov (United States)

    Hayes, A. C.; Jungman, Gerard; Schulz, A. E.; Boswell, M.; Fowler, M. M.; Grim, G.; Klein, A.; Rundberg, R. S.; Wilhelmy, J. B.; Wilson, D.; Cerjan, C.; Schneider, D.; Sepke, S. M.; Tonchev, A.; Yeamans, C.

    2015-08-01

    We present the first measurements of reaction-in-flight (RIF) neutrons in an inertial confinement fusion system. The experiments were carried out at the National Ignition Facility, using both Low Foot and High Foot drives and cryogenic plastic capsules. In both cases, the high-energy RIF ( En> 15 MeV) component of the neutron spectrum was found to be about 10-4 of the total. The majority of the RIF neutrons were produced in the dense cold fuel surrounding the burning hotspot of the capsule, and the data are consistent with a compressed cold fuel that is moderately to strongly coupled (Γ˜ 0.6) and electron degenerate (θFermi/θe˜ 4). The production of RIF neutrons is controlled by the stopping power in the plasma. Thus, the current RIF measurements provide a unique test of stopping power models in an experimentally unexplored plasma regime. We find that the measured RIF data strongly constrain stopping models in warm dense plasma conditions, and some models are ruled out by our analysis of these experiments.

  15. A passive Bonner sphere spectrometer for in-flight neutron spectrometry

    International Nuclear Information System (INIS)

    Hajek, M.; Berger, T.; Vana, N.

    2003-01-01

    The neutron energy spectrum was measured onboard a series of four return flights between Cologne (Germany) and Washington, DC (USA) during the solar minimum conditions of June/July 1996. This experiment was world-wide the first determination of the neutron spectrum by passive spectrometry methods onboard an aircraft. The project was conducted with the support of the German Airforce which reserved two seat rows in the front of an Airbus A 310-304 for the passive BSS. The count rates were computed according to the Pair Method and unfolded with MAXED. Obtained spectrum shows two relative maxima around 1 and 100 MeV, the second of which cannot be completely assessed by the applied BSS. The agreement between measurement and calculation proved to be excellent

  16. A novel time-to-pulse height converter for fast-neutron time-of-flight techniques; Nouveau convertisseur temps-amplitude d'impulsions pour les mesures du temps de vol des neutrons rapides; Novyj vremya-amplitudnyj preobrazovatel' impul'sov dlya izmereniya vremeni proleta bystrykh nejtronov; Nuevo convertidor tiempo-altura de impulsos para tecnicas de tiempo de vuelo de neutrones rapidos

    Energy Technology Data Exchange (ETDEWEB)

    Christiansen, J [Physikalisches Staatsinstitut, Hamburg, Federal Republic of Germany (Germany)

    1962-04-15

    An electronic time-to-pulse height converter is described which uses a multiplicative method instead of the usual one of adding overlapping pulses. This is achieved by a coincidence of a linear sawtooth and a sharply clipped needle-pulse. The sawtooth is fed to the grid of a beam-deflecting tube (E80T) and the needle-pulse is applied to the deflecting plates and opens the tube only during a time-interval of about 5.10{sup -9} s. The plate gets a charge proportional to the time-difference between the start of the sawtooth and the needle pulse. The plate-pulse is stretched and amplified and its height represents a measurement of the time-difference. With this method we got a time resolution of 2{tau} = 7 x 10{sup -12}s with artificial pulses, 2{tau} = 3 x 10{sup -10}s with Co{sup 60} {gamma}-coincidences by using NE 102 plastic crystals and 2{tau} = 1.4 x 10{sup -9} s with 511-keV {gamma}-coincidences using NaI(Te) crystals. The method was also used with pulsed beam techniques. In this case we got from the pulsing RF an 8-Mc, sharply-peaked pulse-sequence, which was fed to the E80T plates. We had a time-resolution of 2{tau} = 1.1 x 10{sup -9} s with 4-MeV neutrons using plastic crystals 0.7 in long. Normally the region of linear response was 30 ns but it was possible to go up to 120 ns. (author) [French] L'auteur decrit un convertisseur electronique temps en amplitude d'impulsions fonctionnant d'apres une methode de multiplication au lieu de la methode habituelle qui consiste a ajouter des impulsions qui se chevauchent. On fait coincider une impulsion lineaire en dents de scie avec une impulsion en forme d'aiguille fortement ecretee. L'impulsion en dents de scie est envoyee sur la grille d'un tube a faisceaux electroniques diriges (E80T) ; et l'impulsion en forme d'aiguille est appliquee aux plaques de deflexion et n'ouvre le tube que pendant un intervalle de temps d'environ 5 {center_dot} 10{sup -9} s. La plaque recoit une charge proportionnelle a la difference de

  17. Testing the time-of-flight model for flagellar length sensing.

    Science.gov (United States)

    Ishikawa, Hiroaki; Marshall, Wallace F

    2017-11-07

    Cilia and flagella are microtubule-based organelles that protrude from the surface of most cells, are important to the sensing of extracellular signals, and make a driving force for fluid flow. Maintenance of flagellar length requires an active transport process known as intraflagellar transport (IFT). Recent studies reveal that the amount of IFT injection negatively correlates with the length of flagella. These observations suggest that a length-dependent feedback regulates IFT. However, it is unknown how cells recognize the length of flagella and control IFT. Several theoretical models try to explain this feedback system. We focused on one of the models, the "time-of-flight" model, which measures the length of flagella on the basis of the travel time of IFT protein in the flagellar compartment. We tested the time-of-flight model using Chlamydomonas dynein mutant cells, which show slower retrograde transport speed. The amount of IFT injection in dynein mutant cells was higher than that in control cells. This observation does not support the prediction of the time-of-flight model and suggests that Chlamydomonas uses another length-control feedback system rather than that described by the time-of-flight model. © 2017 Ishikawa and Marshall. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  18. Neutron resonance spectroscopy at n-TOF at CERN

    International Nuclear Information System (INIS)

    Gunsing, F.; Abbondanno, U.; Aerts, G.; Alvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Becvar, F.; Berthoumieux, E.; Calvino, F.; Calviani, M.; Cano-Ott, D.; Capote, R.; Carrapic, C.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fujii, K.; Furman, W.; Goncalves, I.; Gonzalez-Romero, E.; Gramegna, F.; Guerrero, C.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Jericha, E.; Kappeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Kerveno, M.; Koehler, P.; Kossionides, E.; Krticka, M.; Lampoudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marrone, S.; Martinez, T.; Massimi, C.; Mastinu, P.; Mengoni, A.; Milazzo, P.M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M.T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tagliente, G.; Tain, J.L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M.C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wiescher, M.; Wisshak, K.

    2008-01-01

    Neutron resonance spectroscopy plays an important role in the investigation of neutron induced reaction cross sections and nuclear structure in the MeV excitation range. Neutron time-of-flight facilities are the most used installations to explore neutron resonances. In this paper we describe the basic features of neutron resonance spectroscopy together with recent results from the time-of-flight facility n-TOF at CERN. (authors)

  19. Monte-Carlo studies of the performance of scintillator detectors for time-of-flight measurements

    International Nuclear Information System (INIS)

    Yang, X.H.

    1995-01-01

    In this paper we report on a Monte-Carlo program, SToF, developed to evaluate the performance of scintillator-based Time-of-Flight (TOF) detectors. This program has been used in the design of the TOF system for the PHENIX experiment at RHIC. The program was used to evaluate the intrinsic time-of-flight resolution of various scintillator and light-guide geometries, and the results of these simulations are presented here. The simulation results agree extremely well with measured pulse-height and time distributions with one adjustable parameter. These results, thus, explain also the reduced quantities, such as the position dependence of the time resolution, etc, implying that SToF will be generally useful for estimating the performance of TOF detectors. ((orig.))

  20. Particle identification by time-of-flight measurement in the SAPHIR

    International Nuclear Information System (INIS)

    Hoffmann-Rothe, P.

    1993-02-01

    Using photoproduction data which have been measured with the SAPHIR-detector with different target materials (C H 2 solid , H 2 liquid , D 2 liquid ) a detailed investigation and discussion of the detectors performance to measure the time of flight of charged particles and to separate between particles of different mass has been accomplished. A FORTRAN program has been written which provides a calibration of the scintillator panels of the TOF hodoscopes, calculates correction factors for the time-walk effect an finally, by combining the time of flight with track momentum measurement, determines particle masses. The current configuration of the detector makes it possible to separate between proton and pion up to a particle momentum of 1.6 GeV/c. Proton and kaon can be separated up to a momentum of 1.3 GeV/c, kaon and pion up to a momentum of 0.85 GeV/c. (prog.) [de

  1. The time-of-flight TOFW detector of the HARP experiment: construction and performance

    International Nuclear Information System (INIS)

    Baldo-Ceolin, M.; Barichello, G.; Bobisut, F.; Bonesini, M.; De Min, A.; Ferri, A.F.; Gibin, D.; Guglielmi, A.; Laveder, M.; Menegolli, A.; Mezzetto, M.; Paganoni, M.; Paleari, F.; Pepato, A.; Tonazzo, A.; Vascon, M.

    2004-01-01

    The construction and performance of a large area scintillator-based time-of-flight detector for the HARP experiment at CERN are reported. An intrinsic counter time resolution of ∼160 ps was achieved. The precision on the time calibration and monitoring of the detector was maintained at better than 100 ps by using dedicated cosmic rays runs, a fast laser-based system and calibrations with beam particles. The detector was operated on the T9 PS beamline during 2001 and 2002. A time-of-flight resolution of ∼200 ps was obtained, providing π/p discrimination at more than 3σ up to 4.0 GeV/c momentum

  2. The Dubna double-arm time-of-flight spectrometer for heavy-ion reaction products

    International Nuclear Information System (INIS)

    Schilling, K.D.; Gippner, P.; Seidel, W.; Stary, F.; Will, E.; Heidel, K.; Lukyanov, S.M.; Penionzhkevich, Yu.E.; Salamatin, V.S.; Sodan, H.; Chubarian, G.G.

    1986-05-01

    The double-arm time-of-flight spectrometer DEMAS designed for the detection and identification of heavy-ion reaction products at incident energies below 10 MeV/amu is presented. Based on the kinematic coincidence method, the relevant physical information is obtained from the measurement of the two correlated velocity vectors of the binary fragments. Construction and performance of the different detector systems applied to measure the time-of-flight values, the position coordinates and the kinetic energies of both fragments are presented in detail. The description of the data acquisition and analysing procedures is followed by the discussion of some experimental examples to demonstrate the spectrometer performance. A mass resolution of typically 4 - 5 amu (fwhm) is routinely achieved. (author)

  3. A new method of detection for a positron emission tomograph using a time of flight method

    International Nuclear Information System (INIS)

    Gresset, Christian.

    1981-05-01

    In the first chapter, it is shown the advantages of positron radioemitters (β + ) of low period, and the essential characteristics of positron tomographs realized at the present time. The second chapter presents the interest of an original technique of image reconstruction: the time of flight technique. The third chapter describes the characterization methods which were set for verifying the feasibility of cesium fluoride in tomography. Chapter four presents the results obtained by these methods. It appears that the cesium fluoride constitute presently the best positron emission associated to time of flight technique. The hypotheses made on eventual performances of such machines are validated by experiments with phantom. The results obtained with a detector (bismuth germanate) conserves all its interest in skull tomography [fr

  4. High-throughput shotgun lipidomics by quadrupole time-of-flight mass spectrometry

    DEFF Research Database (Denmark)

    Ståhlman, Marcus; Ejsing, Christer S.; Tarasov, Kirill

    2009-01-01

    Technological advances in mass spectrometry and meticulous method development have produced several shotgun lipidomic approaches capable of characterizing lipid species by direct analysis of total lipid extracts. Shotgun lipidomics by hybrid quadrupole time-of-flight mass spectrometry allows...... the absolute quantification of hundreds of molecular glycerophospholipid species, glycerolipid species, sphingolipid species and sterol lipids. Future applications in clinical cohort studies demand detailed lipid molecule information and the application of high-throughput lipidomics platforms. In this review...... we describe a novel high-throughput shotgun lipidomic platform based on 96-well robot-assisted lipid extraction, automated sample infusion by mircofluidic-based nanoelectrospray ionization, and quantitative multiple precursor ion scanning analysis on a quadrupole time-of-flight mass spectrometer...

  5. Beam derived trigger system for multibunch time-of-flight measurement

    International Nuclear Information System (INIS)

    Fox, J.; Pellegrin, J.L.

    1981-01-01

    Particle time-of-flight measurement requires accurate triggers in synchronism with each bunch, and occurring in a sequence which depends on the position of the observer around the storage ring. A system has been devised for tagging the colliding bunches at each interaction point; it allows one to record which pair of bunches is colliding at any time and any location around the machine. Besides bunch identification, the time-of-flight triggers are also expected to have a time stability better than the bunch length itself. A system is presented here which exhibits time variations of less than 80 psec over a 20 to 1 range of beam current, while the jitter is at least an order of magnitude smaller. 4 refs., 4 figs

  6. Time of flight measurements of unirradiated and irradiated nuclear graphite under cyclic compressive load

    Energy Technology Data Exchange (ETDEWEB)

    Bodel, W., E-mail: william.bodel@hotmail.com [Nuclear Graphite Research Group, The University of Manchester (United Kingdom); Atkin, C. [Health and Safety Laboratory, Buxton (United Kingdom); Marsden, B.J. [Nuclear Graphite Research Group, The University of Manchester (United Kingdom)

    2017-04-15

    The time-of-flight technique has been used to investigate the stiffness of nuclear graphite with respect to the grade and grain direction. A loading rig was developed to collect time-of-flight measurements during cycled compressive loading up to 80% of the material's compressive strength and subsequent unloading of specimens along the axis of the applied stress. The transmission velocity (related to Young's modulus), decreased with increasing applied stress; and depending on the graphite grade and orientation, the modulus then increased, decreased or remained constant upon unloading. These tests were repeated while observing the microstructure during the load/unload cycles. Initial decreases in transmission velocity with compressive load are attributed to microcrack formation within filler and binder phases. Three distinct types of behaviour occur on unloading, depending on the grade, irradiation, and loading direction. These different behaviours can be explained in terms of the material microstructure observed from the microscopy performed during loading.

  7. A compact time-of-flight mass spectrometer for ion source characterization

    International Nuclear Information System (INIS)

    Chen, L.; Wan, X.; Jin, D. Z.; Tan, X. H.; Huang, Z. X.; Tan, G. B.

    2015-01-01

    A compact time-of-flight mass spectrometer with overall dimension of about 413 × 250 × 414 mm based on orthogonal injection and angle reflection has been developed for ion source characterization. Configuration and principle of the time-of-flight mass spectrometer are introduced in this paper. The mass resolution is optimized to be about 1690 (FWHM), and the ion energy detection range is tested to be between about 3 and 163 eV with the help of electron impact ion source. High mass resolution and compact configuration make this spectrometer useful to provide a valuable diagnostic for ion spectra fundamental research and study the mass to charge composition of plasma with wide range of parameters

  8. Cross-correlation time-of-flight analysis of molecular beam scattering

    International Nuclear Information System (INIS)

    Nowikow, C.V.; Grice, R.

    1979-01-01

    The theory of the cross-correlation method of time-of-flight analysis is presented in a form which highlights its formal similarity to the conventional method. A time-of-flight system for the analysis of crossed molecular beam scattering is described, which is based on a minicomputer interface and can operate in both the cross-correlation and conventional modes. The interface maintains the synchronisation of chopper disc rotation and channel advance indefinitely in the cross-correlation method and can acquire data in phase with the beam modulation in both methods. The shutter function of the cross-correlation method is determined and the deconvolution analysis of the data is discussed. (author)

  9. Digitizing data acquisition and time-of-flight pulse processing for ToF-ERDA

    Energy Technology Data Exchange (ETDEWEB)

    Julin, Jaakko, E-mail: jaakko.julin@jyu.fi; Sajavaara, Timo

    2016-01-01

    A versatile system to capture and analyze signals from multi channel plate (MCP) based time-of-flight detectors and ionization based energy detectors such as silicon diodes and gas ionization chambers (GIC) is introduced. The system is based on commercial digitizers and custom software. It forms a part of a ToF-ERDA spectrometer, which has to be able to detect recoil atoms of many different species and energies. Compared to the currently used analogue electronics the digitizing system provides comparable time-of-flight resolution and improved hydrogen detection efficiency, while allowing the operation of the spectrometer be studied and optimized after the measurement. The hardware, data acquisition software and digital pulse processing algorithms to suit this application are described in detail.

  10. Invited Article: Characterization of background sources in space-based time-of-flight mass spectrometers

    International Nuclear Information System (INIS)

    Gilbert, J. A.; Gershman, D. J.; Gloeckler, G.; Lundgren, R. A.; Zurbuchen, T. H.; Orlando, T. M.; McLain, J.; Steiger, R. von

    2014-01-01

    For instruments that use time-of-flight techniques to measure space plasma, there are common sources of background signals that evidence themselves in the data. The background from these sources may increase the complexity of data analysis and reduce the signal-to-noise response of the instrument, thereby diminishing the science value or usefulness of the data. This paper reviews several sources of background commonly found in time-of-flight mass spectrometers and illustrates their effect in actual data using examples from ACE-SWICS and MESSENGER-FIPS. Sources include penetrating particles and radiation, UV photons, energy straggling and angular scattering, electron stimulated desorption of ions, ion-induced electron emission, accidental coincidence events, and noise signatures from instrument electronics. Data signatures of these sources are shown, as well as mitigation strategies and design considerations for future instruments

  11. Computational imaging with multi-camera time-of-flight systems

    KAUST Repository

    Shrestha, Shikhar

    2016-07-11

    Depth cameras are a ubiquitous technology used in a wide range of applications, including robotic and machine vision, human computer interaction, autonomous vehicles as well as augmented and virtual reality. In this paper, we explore the design and applications of phased multi-camera time-of-flight (ToF) systems. We develop a reproducible hardware system that allows for the exposure times and waveforms of up to three cameras to be synchronized. Using this system, we analyze waveform interference between multiple light sources in ToF applications and propose simple solutions to this problem. Building on the concept of orthogonal frequency design, we demonstrate state-of-the-art results for instantaneous radial velocity capture via Doppler time-of-flight imaging and we explore new directions for optically probing global illumination, for example by de-scattering dynamic scenes and by non-line-of-sight motion detection via frequency gating. © 2016 ACM.

  12. Design of microcomputer-based data acquisition system for the time-of-flight ion scattering spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Lo, H; Su, C [National Tsing Hua Univ., Hsinchu (Taiwan). Inst. of Nuclear Engineering

    1981-07-15

    A microcomputer-based data aquisition system used on a time-of-flight ion scattering spectrometer is described. The flight time of 90/sup 0/-scattered ions from target atom determined directly with a 30 MHz crystal-controlled oscillator and its associated circuit. The ion intensity is detected by a channel multiplier, and its output signal pulse is converted from the analog form into digital form by an ADC. Both flight time and ion intensity are stored in the microcomputer.

  13. Design of microcomputer-based data acquisition system for the time-of-flight ion scattering spectrometer

    International Nuclear Information System (INIS)

    Lo, H.; Su, C.

    1981-01-01

    A microcomputer-based data aquisition system used on a time-of-flight ion scattering spectrometer is described. The flight time of 90 0 -scattered ions from target atom determined directly with a 30 MHz crystal-controlled oscillator and its associated circuit. The ion intensity is detected by a channel multiplier, and its output signal pulse is converted from the analog form into digital form by an ADC. Both flight time and ion intensity are stored in the microcomputer. (orig.)

  14. A Unique Outside Neutron and Gamma Ray Instrumentation Development Test Facility at NASA's Goddard Space Flight Center

    Science.gov (United States)

    Bodnarik, J.; Evans, L.; Floyd, S.; Lim, L.; McClanahan, T.; Namkung, M.; Parsons, A.; Schweitzer, J.; Starr, R.; Trombka, J.

    2010-01-01

    An outside neutron and gamma ray instrumentation test facility has been constructed at NASA's Goddard Space Flight Center (GSFC) to evaluate conceptual designs of gamma ray and neutron systems that we intend to propose for future planetary lander and rover missions. We will describe this test facility and its current capabilities for operation of planetary in situ instrumentation, utilizing a l4 MeV pulsed neutron generator as the gamma ray excitation source with gamma ray and neutron detectors, in an open field with the ability to remotely monitor and operate experiments from a safe distance at an on-site building. The advantage of a permanent test facility with the ability to operate a neutron generator outside and the flexibility to modify testing configurations is essential for efficient testing of this type of technology. Until now, there have been no outdoor test facilities for realistically testing neutron and gamma ray instruments planned for solar system exploration

  15. Influence of absorption on the time of flight of the light going through a complex medium

    Directory of Open Access Journals (Sweden)

    M. Kervella

    2011-09-01

    Full Text Available The aim of this work is to evaluate the influence of absorption processes on the time of flight of light going through an absorbing and scattering thick medium (clouds, paints, gas cell, etc. In order to study statistical scattering and absorbing processes, we use a Monte-Carlo simulation code with temporal phase function and Debye modes. The main result is that absorption inside particles induces a decrease of the global time delay.

  16. History and current status of PET development based on time of flight

    International Nuclear Information System (INIS)

    Yun Mingkai; Li Ting; Zhang Zhiming; Zhang Yubao; Shan Baoci; Wei Long

    2012-01-01

    The principle of time of flight (TOF) positron emission tomography (PET) and a brief review of the history of TOF-PET are introduced. The factors influencing the time resolution of a TOF-PET scanner are presented, especially focus on the intrinsic properties of scintillators and front-end electronics. Challenges and achievements of the structure of data organization and image reconstruction are reviewed. Finally, the benefits of TOF-PET on image quality improvement and tumor detection are emphasized. (authors)

  17. Identification of microorganisms using superconducting tunnel junctions and time-of-flight mass spectrometry

    Science.gov (United States)

    Ullom, J. N.; Frank, M.; Horn, J. M.; Labov, S. E.; Langry, K.; Benner, W. H.

    2000-04-01

    We present time-of-flight measurements of biological material ejected from bacterial spores following laser irradiation. Ion impacts are registered on a microchannel plate detector and on a Superconducting Tunnel Junction (STJ) detector. We compare mass spectra obtained with the two detectors. The STJ has better sensitivity to massive ions and also measures the energy of each ion. We show evidence that spores of different bacillus species produce distinctive mass spectra and associate the observed mass peaks with coat proteins.

  18. Identification of microorganisms using superconducting tunnel junctions and time-of-flight mass spectrometry

    International Nuclear Information System (INIS)

    Ullom, J.N.; Frank, M.; Horn, J.M.; Labov, S.E.; Langry, K.; Benner, W.H.

    2000-01-01

    We present time-of-flight measurements of biological material ejected from bacterial spores following laser irradiation. Ion impacts are registered on a microchannel plate detector and on a Superconducting Tunnel Junction (STJ) detector. We compare mass spectra obtained with the two detectors. The STJ has better sensitivity to massive ions and also measures the energy of each ion. We show evidence that spores of different bacillus species produce distinctive mass spectra and associate the observed mass peaks with coat proteins

  19. Analysis of phosphatidylcholine oxidation products in human plasma using quadrupole time-of flight mass spectrometry

    OpenAIRE

    Adachi, Junko; Asano, Migiwa; Yoshioka, Naoki; Nushida, Hideyuki; Ueno, Yasuhiro

    2006-01-01

    We report here an application of the previous method for the analysis ofphosphatidylcholine (PC) and lysophosphatidylcholine (lysoPC) oxidation products inhuman plasma using quadrupole time of flight (Q-TOF) mass spectrometry withelectrospray ionization. We separated these products using an HPLC C8 column witha gradient of methanol and 10 mM aqueous ammonium acetate. Monohydroperoxides,epoxyhydroxy derivatives, oxo derivatives, and trihydroxides of palmitoyl-linoleoyl(C16:0/C18:2) PC and stea...

  20. Development of a hand-portable photoionization time-of-flight mass spectrometer

    International Nuclear Information System (INIS)

    Dieckman, S.L.; Bostrom, G.A.; Waterfield, L.G.; Jendrzejczyk, J.A.; Raptis, A.C.

    1996-01-01

    ANL is currently developing a portable chemical sensor system based on laser desorption photoionization time-of-flight mass spectrometry. It will incorporate direct sampling, a cryocooler base sample adsorption and concentration, and direct surface multiphoton ionization. All components will be in a package 9 x 11 x 4 in., weighing 15-18 lbs. A sample spectrum is given for a NaCl sample

  1. The advantages of orthogonal acceleration in ICP time-of-flight mass spectrometry

    International Nuclear Information System (INIS)

    Gaal, Andrew

    2004-01-01

    The OptiMass 8000 incorporates an orthogonal acceleration time-of-flight mass spectrometer. A general schematic of the instrument is given. The continuous ion beam is chopped by an orthogonal accelerator. A push out pulse supply is coupled to the accelerator for providing repetitive push-out voltages at a frequency of 30 kHz. The ion packets that are sliced out of the beam then travel within the field free space towards the SMARTGATE ion blanker. Orthogonal accelerator parameters are set to enable temporal-spatial focusing at the SMARTGATE ion blanker, so that iso-mass ion packets are resolved in time. Any ion packets of unwanted specie are ejected from the direction of travel by supplying pulsed voltages onto the deflection plates of the SMARTGATE. The ions to be measured are let through SMARTGATE and travel further down the field free space, to enter the ion reflectron. The ion reflectron increases the resolution of the mass spectrometer by means of temporal-energy focussing. After reflection, the ions travel within the field free space towards the discrete-dynode detector. In comparison to other acceleration geometries used in elemental time-of-flight mass spectrometry the OptiMass 8000 orthogonal acceleration geometry ultimately leads to superior resolution. As the energy spread is about 3 orders of magnitude lower in the time-of-flight direction for an oaTOFMS in comparison to an on-axis system, aberration acquired in the initial stages of acceleration are much lower. As a result the orthogonal acceleration scheme provides superior resolution at the first spatial focus point and the detector. The orthogonal acceleration time-of-flight analyzer of the OptiMass 8000 is able to provide resolution of at least 1800 at mass 238. (author)

  2. Timing performances of a data acquisition system for Time of Flight PET

    International Nuclear Information System (INIS)

    Morrocchi, Matteo; Marcatili, Sara; Belcari, Nicola; Bisogni, Maria G.; Collazuol, Gianmaria; Ambrosi, Giovanni; Corsi, Francesco; Foresta, Maurizio; Marzocca, Cristoforo; Matarrese, Gianvito; Sportelli, Giancarlo; Guerra, Pedro; Santos, Andres; Del Guerra, Alberto

    2012-01-01

    We are investigating the performances of a data acquisition system for Time of Flight PET, based on LYSO crystal slabs and 64 channels Silicon Photomultipliers matrices (1.2 cm 2 of active area each). Measurements have been performed to test the timing capability of the detection system (SiPM matices coupled to a LYSO slab and the read-out electronics) with both test signal and radioactive source.

  3. Timing performances of a data acquisition system for Time of Flight PET

    Energy Technology Data Exchange (ETDEWEB)

    Morrocchi, Matteo, E-mail: matteo.morrocchi@pi.infn.it [University of Pisa and INFN Sezione di Pisa, I 56127 Pisa (Italy); Marcatili, Sara; Belcari, Nicola; Bisogni, Maria G. [University of Pisa and INFN Sezione di Pisa, I 56127 Pisa (Italy); Collazuol, Gianmaria [University of Padova and INFN Sezione di Padova (Italy); Ambrosi, Giovanni [INFN Sezione di Perugia, I 06100 Perugia (Italy); Corsi, Francesco; Foresta, Maurizio; Marzocca, Cristoforo; Matarrese, Gianvito [Politecnico di Bari and INFN Sezione di Bari, I 70100 Bari (Italy); Sportelli, Giancarlo; Guerra, Pedro; Santos, Andres [Universidad Politecnica de Madrid, E 28040 Madrid (Spain); Centro de Investigacion Biomedica en Red en Bioingenieria, Biomateriales y Nanomedicina (CIBER-BBN) (Spain); Del Guerra, Alberto [University of Pisa and INFN Sezione di Pisa, I 56127 Pisa (Italy)

    2012-12-11

    We are investigating the performances of a data acquisition system for Time of Flight PET, based on LYSO crystal slabs and 64 channels Silicon Photomultipliers matrices (1.2 cm{sup 2} of active area each). Measurements have been performed to test the timing capability of the detection system (SiPM matices coupled to a LYSO slab and the read-out electronics) with both test signal and radioactive source.

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

    International Nuclear Information System (INIS)

    Hunter, S.D.

    1991-01-01

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

  5. Energy measurement using a resonator based time-of-flight system

    International Nuclear Information System (INIS)

    Pardo, R.C.; Clifft, B.; Johnson, K.W.; Lewis, R.N.

    1983-01-01

    A resonant pick-up time-of-flight system has been developed for the precise measurement of beam energy at the Argonne Tandem-Linac Accelerator System (ATLAS). The excellent timing characteristics available with ATLAS beams make it desirable to design the beam transport system to be isochronous. The advantages of the resonant time-of-flight system over other energy analysis systems such as the dispersive magnet system are numerous. The system is non-interceptive and non-destructive and preserves the beam phase space. It is non-dispersive. Path length variations are not introduced into the beam which would reduce the timing resolution. It has a large signal-to-noise ratio when compared to non-resonant beam pick-up techniques. It provides the means to precisely set the linac energy and potentially to control the energy in a feedback loop. Finally, the resonant pick-up time-of-flight system is less expensive than an equivalent magnetic system. It consists of two beam-excited resonators, associated electronics to decode the information, a computer interface to the linac PDP 11/34 control computer, and software to analyze the information and deduce the measured beam energy. This report describes the system and its components and gives a schematic overview

  6. TORCH: A Large-Area Detector for Precision Time-of-Flight Measurements at LHCb

    CERN Document Server

    Harnew, N

    2012-01-01

    The TORCH (Time Of internally Reflected CHerenkov light) is an innovative high-precision time-of-flight detector which is suitable for large areas, up to tens of square metres, and is being developed for the upgraded LHCb experiment. The TORCH provides a time-of-flight measurement from the imaging of photons emitted in a 1 cm thick quartz radiator, based on the Cherenkov principle. The photons propagate by total internal reflection to the edge of the quartz plane and are then focused onto an array of Micro-Channel Plate (MCP) photon detectors at the periphery of the detector. The goal is to achieve a timing resolution of 15 ps per particle over a flight distance of 10 m. This will allow particle identification in the challenging momentum region up to 20 GeV/c. Commercial MCPs have been tested in the laboratory and demonstrate the required timing precision. An electronics readout system based on the NINO and HPTDC chipset is being developed to evaluate an 8×8 channel TORCH prototype. The simulated performance...

  7. Determining the Time of Flight and Speed of Sound on Different types of Edible Oil

    Science.gov (United States)

    Azman, N. A.; Hamid, S. B. Abd

    2017-11-01

    Edible oil is most often plant-based oils that have been extracted from various seeds. There are cases where the fully virgin edible oil was found to be a fraud. The adulterated edible oil indicates the intentional, fraudulent addition of extraneous, improper or cheaper ingredients puts into the oil or the dilution or removal of some valuable ingredient of the oil in order to increase profits. Hence, decrease the reliability of the Malaysian food product quality. This research was done by using the method of time of flight obtained using the Texas Instrument board, TDC1000-TDC7200 EVM connected to an ultrasonic transducer with 1 MHz frequency. The authors measured the time of flight and temperatures controlled from 20°C to 40°C of five vegetable oils (olive oil, sunflower oil, corn oil, coconut oil, and mustard oil). The value is observed and compared with other research from the literature review. From the study, time of flight values decreases exponentially while speed of sound value increases. This relationship will be useful in spectrum unfolding method to investigate the adulteration in different type of edible oil.This research outcome is to investigate the quality value of the different type of edible oil while eliminates the issues where the quality of Malaysian food product is not reliable.

  8. Picosecond resolution on relativistic heavy ions' time-of-flight measurement

    Energy Technology Data Exchange (ETDEWEB)

    Ebran, A., E-mail: adeline.ebran@cea.fr; Taieb, J., E-mail: julien.taieb@cea.fr; Belier, G.; Chatillon, A.; Laurent, B.; Martin, J.-F.; Pellereau, E.

    2013-11-11

    We developed a time-of-flight measurement system for relativistic heavy ions with a requested resolution of 40 ps Full Width Half Maximum. Such a resolution is mandatory to assign the correct mass number to every fission fragment, identified using the Bρ-ToF-ΔE method with the recoil spectrometer designed for the SOFIA experiment—which hold very recently at GSI. To achieve such a performance, fast plastic scintillators read-out by dedicated photomultiplier tubes were chosen among other possible options. We have led several test-measurements from 2009 to 2011, in order to investigate: the effect of the addition of a quenching molecule in the scintillator's matrix, the influence of the detector's size and the impact of the photomultiplier tube. The contribution of the dedicated electronics is also characterized. Time-of-flight measurements were performed realized with electron pulses and relativistic heavy ions, respectively provided by the LASER driven electron–accelerator (ELSA) at CEA–DAM Ile-de-France and by the SIS18/FRS facility at GSI. The reported results exhibit a time resolution better than 20 ps Full Width Half Maximum reached with the last prototype at GSI with an Uranium beam. These results confirm that the SOFIA experiment should enable the measurement of the relativistic fission fragments' time-of-flight with the requested resolution.

  9. Picosecond resolution on relativistic heavy ions' time-of-flight measurement

    International Nuclear Information System (INIS)

    Ebran, A.; Taieb, J.; Belier, G.; Chatillon, A.; Laurent, B.; Martin, J.-F.; Pellereau, E.

    2013-01-01

    We developed a time-of-flight measurement system for relativistic heavy ions with a requested resolution of 40 ps Full Width Half Maximum. Such a resolution is mandatory to assign the correct mass number to every fission fragment, identified using the Bρ-ToF-ΔE method with the recoil spectrometer designed for the SOFIA experiment—which hold very recently at GSI. To achieve such a performance, fast plastic scintillators read-out by dedicated photomultiplier tubes were chosen among other possible options. We have led several test-measurements from 2009 to 2011, in order to investigate: the effect of the addition of a quenching molecule in the scintillator's matrix, the influence of the detector's size and the impact of the photomultiplier tube. The contribution of the dedicated electronics is also characterized. Time-of-flight measurements were performed realized with electron pulses and relativistic heavy ions, respectively provided by the LASER driven electron–accelerator (ELSA) at CEA–DAM Ile-de-France and by the SIS18/FRS facility at GSI. The reported results exhibit a time resolution better than 20 ps Full Width Half Maximum reached with the last prototype at GSI with an Uranium beam. These results confirm that the SOFIA experiment should enable the measurement of the relativistic fission fragments' time-of-flight with the requested resolution

  10. Neutron Capture Reactions on Fe and Ni Isotopes for the Astrophysical s-process

    Energy Technology Data Exchange (ETDEWEB)

    Lederer, C., E-mail: claudia.lederer@ed.ac.uk [University of Vienna, Faculty of Physics, 1090 Vienna (Austria); Johann-Wolfgang-Goethe Universität, 60438 Frankfurt (Germany); Giubrone, G. [Instituto de Física Corpuscular, CSIC-Universidad de Valencia, 46071 Valencia (Spain); Massimi, C. [Dipartimento di Fisica, Università di Bologna, and Sezione INFN di Bologna, 40100 Bologna (Italy); Žugec, P. [Department of Physics, Faculty of Science, University of Zagreb, 10002 Zagreb (Croatia); Barbagallo, M.; Colonna, N. [Istituto Nazionale di Fisica Nucleare, 70125 Bari (Italy); Domingo-Pardo, C. [Instituto de Física Corpuscular, CSIC-Universidad de Valencia, 46071 Valencia (Spain); Guerrero, C. [European Organization for Nuclear Research (CERN), CH-1211 Geneva (Switzerland); Gunsing, F. [Commissariat à l' Énergie Atomique (CEA) Saclay – Irfu, 91191 Gif-sur-Yvette (France); Käppeler, F. [Karlsruhe Institute of Technology, Campus Nord, Institut für Kernphysik, 76021 Karlsruhe (Germany); Tain, J.L. [Instituto de Física Corpuscular, CSIC-Universidad de Valencia, 46071 Valencia (Spain); Altstadt, S. [Johann-Wolfgang-Goethe Universität, 60438 Frankfurt (Germany); Andrzejewski, J. [Uniwersytet Łódzki, 90131 Lodz (Poland); Audouin, L. [Centre National de la Recherche Scientifique/IN2P3 – IPN, 91406 Orsay (France); Bécares, V. [Centro de Investigaciones Energeticas Medioambientales y Tecnológicas (CIEMAT), 28040 Madrid (Spain); Bečvář, F. [Faculty of Mathematics and Physics, Charles University, CZ-180 00 Prague (Czech Republic); and others

    2014-06-15

    Neutron capture cross sections in the keV neutron energy region are the key nuclear physics input to study the astrophysical slow neutron capture process. In the past years, a series of neutron capture cross section measurements has been performed at the neutron time-of-flight facility n{sub T}OF at CERN focussing on the Fe/Ni mass region. Recent results and future developments in the neutron time-of-flight technique are discussed.

  11. Using convolutional neural networks to estimate time-of-flight from PET detector waveforms

    Science.gov (United States)

    Berg, Eric; Cherry, Simon R.

    2018-01-01

    Although there have been impressive strides in detector development for time-of-flight positron emission tomography, most detectors still make use of simple signal processing methods to extract the time-of-flight information from the detector signals. In most cases, the timing pick-off for each waveform is computed using leading edge discrimination or constant fraction discrimination, as these were historically easily implemented with analog pulse processing electronics. However, now with the availability of fast waveform digitizers, there is opportunity to make use of more of the timing information contained in the coincident detector waveforms with advanced signal processing techniques. Here we describe the application of deep convolutional neural networks (CNNs), a type of machine learning, to estimate time-of-flight directly from the pair of digitized detector waveforms for a coincident event. One of the key features of this approach is the simplicity in obtaining ground-truth-labeled data needed to train the CNN: the true time-of-flight is determined from the difference in path length between the positron emission and each of the coincident detectors, which can be easily controlled experimentally. The experimental setup used here made use of two photomultiplier tube-based scintillation detectors, and a point source, stepped in 5 mm increments over a 15 cm range between the two detectors. The detector waveforms were digitized at 10 GS s-1 using a bench-top oscilloscope. The results shown here demonstrate that CNN-based time-of-flight estimation improves timing resolution by 20% compared to leading edge discrimination (231 ps versus 185 ps), and 23% compared to constant fraction discrimination (242 ps versus 185 ps). By comparing several different CNN architectures, we also showed that CNN depth (number of convolutional and fully connected layers) had the largest impact on timing resolution, while the exact network parameters, such as convolutional

  12. Novel time-of-flight spectrometer for the analysis of positron annihilation induced Auger electrons

    International Nuclear Information System (INIS)

    Hugenschmidt, Christoph; Legl, Stefan

    2006-01-01

    Positron annihilation induced Auger-electron spectroscopy (PAES) has several advantages over conventional Auger-electron spectroscopy such as extremely high surface sensitivity and outstanding signal-to-noise ratio at the Auger-transition energy. In order to benefit from these prominent features a low-energy positron beam of high intensity is required for surface sensitive PAES studies. In addition, an electron energy analyzer is required, which efficiently detects the Auger electrons with acceptable energy resolution. For this reason a novel time-of-flight (TOF) spectrometer has been developed at the intense positron source NEPOMUC that allows PAES studies within short measurement time. This TOF-PAES setup combines a trochoidal filter and a flight tube in a Faraday cage in order to achieve an improved energy resolution of about 1 eV at high electron energies up to E≅1000 eV. The electron flight time is the time between the annihilation radiation at the sample and when the electron hits a microchannel plate detector at the end of the flight tube

  13. A novel particle time of flight diagnostic for measurements of shock- and compression-bang times in D3He and DT implosions at the NIF.

    Science.gov (United States)

    Rinderknecht, H G; Johnson, M Gatu; Zylstra, A B; Sinenian, N; Rosenberg, M J; Frenje, J A; Waugh, C J; Li, C K; Sèguin, F H; Petrasso, R D; Rygg, J R; Kimbrough, J R; MacPhee, A; Collins, G W; Hicks, D; Mackinnon, A; Bell, P; Bionta, R; Clancy, T; Zacharias, R; Döppner, T; Park, H S; LePape, S; Landen, O; Meezan, N; Moses, E I; Glebov, V U; Stoeckl, C; Sangster, T C; Olson, R; Kline, J; Kilkenny, J

    2012-10-01

    The particle-time-of-flight (pTOF) diagnostic, fielded alongside a wedge range-filter (WRF) proton spectrometer, will provide an absolute timing for the shock-burn weighted ρR measurements that will validate the modeling of implosion dynamics at the National Ignition Facility (NIF). In the first phase of the project, pTOF has recorded accurate bang times in cryogenic DT, DT exploding pusher, and D(3)He implosions using DD or DT neutrons with an accuracy better than ±70 ps. In the second phase of the project, a deflecting magnet will be incorporated into the pTOF design for simultaneous measurements of shock- and compression-bang times in D(3)He-filled surrogate implosions using D(3)He protons and DD-neutrons, respectively.

  14. Ion optics of a time-of-flight mass spectrometer with electrostatic sector analyzers

    International Nuclear Information System (INIS)

    Sakurai, T.; Ito, H.; Matsuo, T.

    1995-01-01

    The ion optics for a high resolution time-of-flight mass spectrometer with electrostatic sector analyzers have been investigated. The multiple focusing (triple isochronous focusing and triple spacial focusing) conditions can be achieved by using a symmetrical arrangement of the sectors in a mass spectrometer. Both high mass resolution and high ion transmission can be accomplished simultaneously. The principles of MS/MS and MS/MS/MS analyses using a TOF mass spectrometer with electrostatic sector analyzers have been proposed. Product ion spectra can be obtained by measuring the total flight times and the kinetic energy of the products without any additional separation processes, any coincidence techniques or any special timing circuits. In an experiment, MS/MS and MS/MS/MS mass spectra have been obtained. The first generation product ions have been produced by a metastable decay, and the second generation products have been produced by a sequential decay. (orig.)

  15. An improvement of isochronous mass spectrometry: Velocity measurements using two time-of-flight detectors

    International Nuclear Information System (INIS)

    Shuai, P.; Xu, X.; Zhang, Y.H.; Xu, H.S.; Litvinov, Yu. A.; Wang, M.

    2016-01-01

    Isochronous mass spectrometry (IMS) in storage rings is a powerful tool for mass measurements of exotic nuclei with very short half-lives down to several tens of microseconds, using a multicomponent secondary beam separated in-flight without cooling. However, the inevitable momentum spread of secondary ions limits the precision of nuclear masses determined by using IMS. Therefore, the momentum measurement in addition to the revolution period of stored ions is crucial to reduce the influence of the momentum spread on the standard deviation of the revolution period, which would lead to a much improved mass resolving power of IMS. One of the proposals to upgrade IMS is that the velocity of secondary ions could be directly measured by using two time-of-flight (double TOF) detectors installed in a straight section of a storage ring. In this paper, we outline the principle of IMS with double TOF detectors and the method to correct the momentum spread of stored ions.

  16. Quasi-dynamic mode of nanomembranes for time-of-flight mass spectrometry of proteins.

    Science.gov (United States)

    Park, Jonghoo; Kim, Hyunseok; Blick, Robert H

    2012-04-21

    Mechanical resonators realized on the nano-scale by now offer applications in mass-sensing of biomolecules with extraordinary sensitivity. The general idea is that perfect mechanical biosensors should be of extremely small size to achieve zeptogram sensitivity in weighing single molecules similar to a balance. However, the small scale and long response time of weighing biomolecules with a cantilever restrict their usefulness as a high-throughput method. Commercial mass spectrometry (MS) such as electro-spray ionization (ESI)-MS and matrix-assisted laser desorption/ionization (MALDI)-time of flight (TOF)-MS are the gold standards to which nanomechanical resonators have to live up to. These two methods rely on the ionization and acceleration of biomolecules and the following ion detection after a mass selection step, such as time-of-flight (TOF). Hence, the spectrum is typically represented in m/z, i.e. the mass to ionization charge ratio. Here, we describe the feasibility and mass range of detection of a new mechanical approach for ion detection in time-of-flight mass spectrometry, the principle of which is that the impinging ion packets excite mechanical oscillations in a silicon nitride nanomembrane. These mechanical oscillations are henceforth detected via field emission of electrons from the nanomembrane. Ion detection is demonstrated in MALDI-TOF analysis over a broad range with angiotensin, bovine serum albumin (BSA), and an equimolar protein mixture of insulin, BSA, and immunoglobulin G (IgG). We find an unprecedented mass range of operation of the nanomembrane detector.

  17. Time-of-flight position-sensitive x-ray detection

    International Nuclear Information System (INIS)

    Mowat, J.W.

    1981-01-01

    A new method for recording beam-foil time-of-flight data is described. A stationary, side-window, position-senstive proportional counter, oriented with anode wire parallel to the ion beam, views the decay in flight of excited ions through a Soller slit x-ray collimator. In contrast to the standard method, the exciter foil, placed within or upstream from the field of view, is not moved during the acquisition of a decay curve. Each point on the anode acts like an independent detector seeing a unique segment of the ion beam. The correspondence between the downstream distance at which an ion decays and the position along the anode at which the x-ray is detected makes a pulse-height spectrum of position pulses equivalent to a time-of-flight decay curve. Thus an entire decay curve can now be acquired without moving the foil. Increased efficiency is the most significant improvement over the standard method in which the radiation detector views only a small segment of the flight path at any one time. Experiments using translating foils are subject to a spurious dependence of x-ray intensity on foil position if the foil is non-uniform (or non-uniformly aged) and wobbles as it moves. This effect is eliminated here. Foil aging effects which influence excitation rates and introduce a slowly varying time dependence of the x-ray intensity are automatically normalized by this multichannel technique. The application of this method to metastable x-ray emitting states of low-Z ions are discussed

  18. Electric field measurement in the ionosphere using the time-of-flight technique

    International Nuclear Information System (INIS)

    Nakamura, Masato; Hayakawa, Hajime; Tsuruda, Koichiro

    1989-01-01

    The first successful electric field measurement in the ionosphere using the time-of-flight technique with a lithium ion beam was carried out on a S-520 sounding rocket launched from Kagoshima Space Center, Japan on January 15, 1987. The purpose of this experiment was to prove the validity of the time-of-flight technique when it is applied to the measurement of the dc electric field in the ionosphere. A time-coded ion beam was ejected from the rocket in the direction perpendicular to the Earth's magnetic field. The beam returned to the rocket twice per rocket spin when the initial beam direction was nearly perpendicular to the electric field. The electric field and the magnetic field were derived from the travel time of these return lithium ions. The accuracy of the electric field determination was ± 0.3 mV/m. The direction of the electric field was obtained from the direction of the returning ion beam after about one ion gyration. The main constituent of the measured electric field was a V x B field due to the rocket motion across the geomagnetic field. The ambient field was less than 1 mV/m. The magnetic field was measured with an accuracy of ± 2.7 nT in this experiment

  19. Fully automatic and precise data analysis developed for time-of-flight mass spectrometry.

    Science.gov (United States)

    Meyer, Stefan; Riedo, Andreas; Neuland, Maike B; Tulej, Marek; Wurz, Peter

    2017-09-01

    Scientific objectives of current and future space missions are focused on the investigation of the origin and evolution of the solar system with the particular emphasis on habitability and signatures of past and present life. For in situ measurements of the chemical composition of solid samples on planetary surfaces, the neutral atmospheric gas and the thermal plasma of planetary atmospheres, the application of mass spectrometers making use of time-of-flight mass analysers is a technique widely used. However, such investigations imply measurements with good statistics and, thus, a large amount of data to be analysed. Therefore, faster and especially robust automated data analysis with enhanced accuracy is required. In this contribution, an automatic data analysis software, which allows fast and precise quantitative data analysis of time-of-flight mass spectrometric data, is presented and discussed in detail. A crucial part of this software is a robust and fast peak finding algorithm with a consecutive numerical integration method allowing precise data analysis. We tested our analysis software with data from different time-of-flight mass spectrometers and different measurement campaigns thereof. The quantitative analysis of isotopes, using automatic data analysis, yields results with an accuracy of isotope ratios up to 100 ppm for a signal-to-noise ratio (SNR) of 10 4 . We show that the accuracy of isotope ratios is in fact proportional to SNR -1 . Furthermore, we observe that the accuracy of isotope ratios is inversely proportional to the mass resolution. Additionally, we show that the accuracy of isotope ratios is depending on the sample width T s by T s 0.5 . Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  20. A high-resolution, multi-stop, time-to-digital converter for nuclear time-of-flight measurements

    International Nuclear Information System (INIS)

    Spencer, D.F.; Cole, J.; Drigert, M.; Aryaeinejad, R.

    2006-01-01

    A high-resolution, multi-stop, time-to-digital converter (TDC) was designed and developed to precisely measure the times-of-flight (TOF) of incident neutrons responsible for induced fission and capture reactions on actinide targets. The minimum time resolution is ±1 ns. The TDC design was implemented into a single, dual-wide CAMAC module. The CAMAC bus is used for command and control as well as an alternative data output. A high-speed ECL interface, compatible with LeCroy FERA modules, was also provided for the principle data output path. An Actel high-speed field programmable gate array (FPGA) chip was incorporated with an external oscillator and an internal multiple clock phasing system. This device implemented the majority of the high-speed register functions, the state machine for the FERA interface, and the high-speed counting circuit used for the TDC conversion. An external microcontroller was used to monitor and control system-level changes. In this work we discuss the performance of this TDC module as well as its application

  1. A high performance Time-of-Flight detector applied to isochronous mass measurement at CSRe

    International Nuclear Information System (INIS)

    Mei Bo; Tu Xiaolin; Wang Meng; Xu Hushan; Mao Ruishi; Hu Zhengguo; Ma Xinwen; Yuan Youjin; Zhang Xueying; Geng Peng; Shuai Peng; Zang Yongdong; Tang Shuwen; Ma Peng; Lu Wan; Yan Xinshuai; Xia Jiawen; Xiao Guoqing; Guo Zhongyan; Zhang Hongbin

    2010-01-01

    A high performance Time-of-Flight detector has been designed and constructed for isochronous mass spectrometry at the experimental Cooler Storage Ring (CSRe). The detector has been successfully used in an experiment to measure the masses of the N∼Z∼33 nuclides near the proton drip-line. Of particular interest is the mass of 65 As. A maximum detection efficiency of 70% and a time resolution of 118±8 ps (FWHM) have been achieved in the experiment. The dependence of detection efficiency and signal average pulse height (APH) on atomic number Z has been studied. The potential of APH for Z identification has been discussed.

  2. Improved measurement linearity and precision for AMCW time-of-flight range imaging cameras.

    Science.gov (United States)

    Payne, Andrew D; Dorrington, Adrian A; Cree, Michael J; Carnegie, Dale A

    2010-08-10

    Time-of-flight range imaging systems utilizing the amplitude modulated continuous wave (AMCW) technique often suffer from measurement nonlinearity due to the presence of aliased harmonics within the amplitude modulation signals. Typically a calibration is performed to correct these errors. We demonstrate an alternative phase encoding approach that attenuates the harmonics during the sampling process, thereby improving measurement linearity in the raw measurements. This mitigates the need to measure the system's response or calibrate for environmental changes. In conjunction with improved linearity, we demonstrate that measurement precision can also be increased by reducing the duty cycle of the amplitude modulated illumination source (while maintaining overall illumination power).

  3. A time-of-flight array for 1 to 2 GeV/c particles

    International Nuclear Information System (INIS)

    Sum, V.; Berdoz, A.R.; Davis, C.A.

    1992-09-01

    A time-of-flight detector array has been developed for an experiment searching for the strangeness -2 H-particle. The array consists of 40 logs of plastic scintillator with dimensions 2.00 x 0.085 x 0.050 m 3 . The photomultiplier tubes are coupled to the scintillators without the use of light guides, and the mounting of the bars is designed for easy adjustment and servicing. The average intrinsic time resolution was found to be 110 ps σ. 8 refs., 9 figs., 1 tab

  4. Indoor and Outdoor Depth Imaging of Leaves With Time-of-Flight and Stereo Vision Sensors

    DEFF Research Database (Denmark)

    Kazmi, Wajahat; Foix, Sergi; Alenya, Guilliem

    2014-01-01

    In this article we analyze the response of Time-of-Flight (ToF) cameras (active sensors) for close range imaging under three different illumination conditions and compare the results with stereo vision (passive) sensors. ToF cameras are sensitive to ambient light and have low resolution but deliver...... poorly under sunlight. Stereo vision is comparatively more robust to ambient illumination and provides high resolution depth data but is constrained by texture of the object along with computational efficiency. Graph cut based stereo correspondence algorithm can better retrieve the shape of the leaves...

  5. Time-of-flight camera via a single-pixel correlation image sensor

    Science.gov (United States)

    Mao, Tianyi; Chen, Qian; He, Weiji; Dai, Huidong; Ye, Ling; Gu, Guohua

    2018-04-01

    A time-of-flight imager based on single-pixel correlation image sensors is proposed for noise-free depth map acquisition in presence of ambient light. Digital micro-mirror device and time-modulated IR-laser provide spatial and temporal illumination on the unknown object. Compressed sensing and ‘four bucket principle’ method are combined to reconstruct the depth map from a sequence of measurements at a low sampling rate. Second-order correlation transform is also introduced to reduce the noise from the detector itself and direct ambient light. Computer simulations are presented to validate the computational models and improvement of reconstructions.

  6. Neutral particle time-of-flight analyzer for the Tandem Mirror Experiment Upgrade (TMX-U)

    International Nuclear Information System (INIS)

    Hibbs, S.M.; Carter, M.R.; Coutts, G.W.

    1985-01-01

    We describe the design and performance of a time-of-flight (ToF) analyzer being built for installation on the east end cell of the Tandem Mirror Experiment Upgrade (TMX-U). Its primary purpose is to measure the velocity distribution of escaping charge exchange neutral particles having energies between 20 and 5000 electron volts (eV). It also enables direct determination of the thermal barrier potential when used in conjunction with the plasma potential diagnostic and the end loss ion spectrometer. In addition, it can measure the velocity distribution of passing ions leaving the central cell and of ions trapped in the thermal barrier

  7. High resolution time-of-flight spectrometer for crossed molecular beam study of elementary chemical reactions

    International Nuclear Information System (INIS)

    Qiu Minghui; Che Li; Ren Zefeng; Dai Dongxu; Wang Xiuyan; Yang Xueming

    2005-01-01

    In this article, we describe an apparatus in our laboratory for investigating elementary chemical reactions using the high resolution time-of-flight Rydberg tagging method. In this apparatus, we have adopted a rotating source design so that collision energy can be changed for crossed beam studies of chemical reactions. Preliminary results on the HI photodissociation and the F atom reaction with H 2 are reported here. These results suggest that the experimental apparatus is potentially a powerful tool for investigating state-to-state dynamics of elementary chemical reactions

  8. New development for the reverse time of flight analysis of spectra measured using Fourier Diffractometer Facilities

    CERN Document Server

    Maayouf, R M A

    2002-01-01

    The present work introduces a new design to replace the (Finnish make) reverse time of flight (RTOF) analyzer used for the Fourier diffractometer facilities. The new design applies a data acquisition system, a special interface card and software program installed in a PC computer, to perform the cross-correlation functions between signals received from the chopper-decoder and detector. It has been found from test measurements performed with the Cairo Fourier diffractometer facility (CFDF) and the similar high resolution one at JINR (Dubna-Russia) that the new design can successfully replace the Finnish make RTOF analyzer.

  9. Timing Calibration for Time-of-Flight PET Using Positron-Emitting Isotopes and Annihilation Targets

    Science.gov (United States)

    Li, Xiaoli; Burr, Kent C.; Wang, Gin-Chung; Du, Huini; Gagnon, Daniel

    2016-06-01

    Adding time-of-flight (TOF) technology has been proven to improve image quality in positron emission tomography (PET). In order for TOF information to significantly reduce the statistical noise in reconstructed PET images, good timing resolution is needed across the scanner field of view (FOV). This work proposes an accurate, robust, and practical crystal-based timing calibration method using 18F - FDG positron-emitting sources together with a spatially separated annihilation target. We calibrated a prototype Toshiba TOF PET scanner using this method and then assessed its timing resolution at different locations in the scanner FOV.

  10. New developments in molecular imaging: positron emission tomography time-of-flight (TOF-PET)

    International Nuclear Information System (INIS)

    Aguilar, P.; Couce, B.; Iglesias, A.; Lois, C.

    2011-01-01

    Positron Emission tomography (PET) in increasingly being used in oncology for the diagnosis and staging of disease, as well as in monitoring response to therapy. One of the last advances in PET is the incorporation of Time-of-Flight (TOF) information, which improves the tomographic reconstruction process and subsequently the quality of the final image. In this work, we explain the principles of PET and the fundamentals of TOF-PET. Clinical images are shown in order to illustrate how TOF-PET improves the detectability of small lesions, particularly in patients with high body mass index. (Author) 20 refs

  11. A study of aging effects of barrel Time-Of-Flight system in the BESIII experiment

    Science.gov (United States)

    Liu, Huan-Huan; Sun, Sheng-Sen; Fang, Shuang-Shi; Wu, Zhi; Dai, Hong-Liang; Heng, Yue-Kun; Zhou, Ming; Deng, Zi-Yan; Liu, Huai-Min

    2018-02-01

    The Time-Of-Flight system consisting of plastic scintillation counters plays an important role for particle identification in the BESIII experiment at the BEPCII double ring e+e- collider. Degradation of the detection efficiency of the barrel TOF system has been observed since the start of physical data taking and this effect has triggered intensive and systematic studies about aging effects of the detector. The aging rates of the attenuation lengths and relative gains are obtained based on the data acquired in past several years. This study is essential for ensuring an extended operation of the barrel TOF system in optimal conditions.

  12. Energy measurement using a resonator-based time-of-flight system

    International Nuclear Information System (INIS)

    Pardo, R.C.; Lewis, R.N.; Johnson, K.W.; Clifft, B.

    1983-01-01

    The resonant time-of-flight system which has been developed has several advantages over other potential approaches. The system is non-interceptive and nondestructive. The beam phase space is preserved. It is non-dispersive. Path length variations are not introduced into the beam transport which would reduce the timing resolution. It has a large signal-to-noise ratio when compared to non-resonant beam pick-up techniques. It provides the means to precisely set the linac energy and, potentially, to control the energy in a feedback loop is desired. It is less expensive than an equivalent magnetic system

  13. Double-arm time-of-flight mass-spectrometer of nuclear fragments

    International Nuclear Information System (INIS)

    Ajvazian, G.M.; Astabatyan, R.A.

    1995-01-01

    A double-arm time-of-flight spectrometer of nuclear fragments for the investigation of heavy nuclei photofission in the intermediate energy range is described. The calibration results and working characteristics of the spectrometer, obtained using 252 Cf as a source of spontaneous fission, are presented. A mass resolution of σ m ∼2-3 a.m.u. was obtained within the registered fragments mass range of 80-160 a.m.u. The spectrometer was tested in the experiment on the investigation of 238 U nuclei fission by Bremsstahlung photons with Eγ max=1.75 GeV

  14. Environmental Effects on Measurement Uncertainties of Time-of-Flight Cameras

    DEFF Research Database (Denmark)

    Gudmundsson, Sigurjon Arni; Aanæs, Henrik; Larsen, Rasmus

    2007-01-01

    In this paper the effect the environment has on the SwissRanger SR3000 Time-Of-Flight camera is investigated. The accuracy of this camera is highly affected by the scene it is pointed at: Such as the reflective properties, color and gloss. Also the complexity of the scene has considerable effects...... on the accuracy. To mention a few: The angle of the objects to the emitted light and the scattering effects of near objects. In this paper a general overview of known such inaccuracy factors are described, followed by experiments illustrating the additional uncertainty factors. Specifically we give a better...

  15. A mechanical nanomembrane detector for time-of-flight mass spectrometry.

    Science.gov (United States)

    Park, Jonghoo; Qin, Hua; Scalf, Mark; Hilger, Ryan T; Westphall, Michael S; Smith, Lloyd M; Blick, Robert H

    2011-09-14

    We describe here a new principle for ion detection in time-of-flight (TOF) mass spectrometry in which an impinging ion packet excites mechanical vibrations in a silicon nitride (Si(3)N(4)) nanomembrane. The nanomembrane oscillations are detected by means of time-varying field emission of electrons from the mechanically oscillating nanomembrane. Ion detection is demonstrated in the MALDI-TOF analysis of proteins varying in mass from 5729 (insulin) to 150,000 (Immunoglobulin G) daltons. The detector response agrees well with the predictions of a thermomechanical model in which the impinging ion packet causes a nonuniform temperature distribution in the nanomembrane, exciting both fundamental and higher order oscillations.

  16. Gas Time-of-Flight Cherenkov Detector with Radiofrequency Phototube for FP420

    International Nuclear Information System (INIS)

    Margaryan, A.

    2011-01-01

    In this paper, the gas Cherenkov detector with radiofrequency phototube is considered as a fast-timing detector for FP420 project. The detector serves for precise Time-of-Flight measurements of forward going protons, capable of accurate vertex reconstruction and background rejection at high luminosities. The proposed technique is a high resolution (∼ 5 ps FWHM for a single proton), high rate (∼ MHz) and highly stable (less than 1 ps) timing technique capable to detect up to several tens events in a short (∼ 1 ns) time interval. (author)

  17. A time-of-flight array for 1 to 2 GeV/c particles

    Energy Technology Data Exchange (ETDEWEB)

    Sum, V; Berdoz, A R; Davis, C A [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Physics; and others

    1992-09-01

    A time-of-flight detector array has been developed for an experiment searching for the strangeness -2 H-particle. The array consists of 40 logs of plastic scintillator with dimensions 2.00 x 0.085 x 0.050 m{sup 3}. The photomultiplier tubes are coupled to the scintillators without the use of light guides, and the mounting of the bars is designed for easy adjustment and servicing. The average intrinsic time resolution was found to be 110 ps {sigma}. 8 refs., 9 figs., 1 tab.

  18. A time-of-flight system for precise measurements of a relativistic charged particle beam momentum

    International Nuclear Information System (INIS)

    Avramenko, S.A.; Belikov, Yu.A.; Golokhvastov, A.I.; Lukstin'sh, Yu.; Man'yakov, P.K.; Rukoyatkin, P.A.; Khorozov, S.A.

    1996-01-01

    A time-of-flight system with a time resolution (σ) about 100 ps is described. The methods for the calibration, stability verification and the method for the time resolution evaluation in conditions of a nonmonochromatic beam are discussed especially. The system was applied in charge exchange ( 3 H, 3 He) experiments with the GIBS spectrometer for a measurement of 3 H-nuclei momenta at 2 GeV/c per nucleon with a precision about 0.2%. (author). 4 refs., 7 figs., 1 tab

  19. Clock-transport synchronisation for neutrino time-of-flight measurements

    International Nuclear Information System (INIS)

    Field, J.H.

    2012-01-01

    A method to synchronise, at the sub-nanosecond level, clocks used for neutrino time-of-flight measurements is proposed. Clocks situated near the neutrino source and target are compared with a moveable clock that is transported between them. The general-relativistic theory of the procedure was tested and verified in an experiment performed by Hafele and Keating in 1972. It is suggested that use of such a synchronisation method may contribute to a precise test of the Sagnac effect - a measured velocity greater than c - for neutrinos of the proposed LBNE beam between Fermilab and the Homestake mine. (orig.)

  20. A compact time-of-flight SANS instrument optimised for measurements of small sample volumes at the European Spallation Source

    Energy Technology Data Exchange (ETDEWEB)

    Kynde, Søren, E-mail: kynde@nbi.ku.dk [Niels Bohr Institute, University of Copenhagen (Denmark); Hewitt Klenø, Kaspar [Niels Bohr Institute, University of Copenhagen (Denmark); Nagy, Gergely [SINQ, Paul Scherrer Institute (Switzerland); Mortensen, Kell; Lefmann, Kim [Niels Bohr Institute, University of Copenhagen (Denmark); Kohlbrecher, Joachim, E-mail: Joachim.kohlbrecher@psi.ch [SINQ, Paul Scherrer Institute (Switzerland); Arleth, Lise, E-mail: arleth@nbi.ku.dk [Niels Bohr Institute, University of Copenhagen (Denmark)

    2014-11-11

    The high flux at European Spallation Source (ESS) will allow for performing experiments with relatively small beam-sizes while maintaining a high intensity of the incoming beam. The pulsed nature of the source makes the facility optimal for time-of-flight small-angle neutron scattering (ToF-SANS). We find that a relatively compact SANS instrument becomes the optimal choice in order to obtain the widest possible q-range in a single setting and the best possible exploitation of the neutrons in each pulse and hence obtaining the highest possible flux at the sample position. The instrument proposed in the present article is optimised for performing fast measurements of small scattering volumes, typically down to 2×2×2 mm{sup 3}, while covering a broad q-range from about 0.005 1/Å to 0.5 1/Å in a single instrument setting. This q-range corresponds to that available at a typical good BioSAXS instrument and is relevant for a wide set of biomacromolecular samples. A central advantage of covering the whole q-range in a single setting is that each sample has to be loaded only once. This makes it convenient to use the fully automated high-throughput flow-through sample changers commonly applied at modern synchrotron BioSAXS-facilities. The central drawback of choosing a very compact instrument is that the resolution in terms of δλ/λ obtained with the short wavelength neutrons becomes worse than what is usually the standard at state-of-the-art SANS instruments. Our McStas based simulations of the instrument performance for a set of characteristic biomacromolecular samples show that the resulting smearing effects still have relatively minor effects on the obtained data and can be compensated for in the data analysis. However, in cases where a better resolution is required in combination with the large simultaneous q-range characteristic of the instrument, we show that this can be obtained by inserting a set of choppers.

  1. Quasielastic high-resolution time-of-flight spectrometers employing multi-disk chopper cascades for spallation sources

    International Nuclear Information System (INIS)

    Lechner, R.E.

    2001-01-01

    The design of multi-disk chopper time-of-flight (MTOF) spectrometers for high-resolution quasielastic and low-energy inelastic neutron scattering at spallation sources is discussed in some detail. A continuously variable energy resolution (1 μeV to 10 meV), and a large dynamic range (1 μeV to 100 meV), are outstanding features of this type of instrument, which are easily achieved also at a pulsed source using state-of-the-art technology. The method of intensity-resolution optimization of MTOF spectrometers at spallation sources is treated on the basis of the requirement of using (almost) 'all the neutrons of the pulse', taking into account the constant, but wavelength-dependent duration of the source pulse. It follows, that the optimization procedure (which is slightly different from that employed in the steady-state source case) should give priority to the highest resolution, whenever such a choice becomes necessary. This leads to long monochromator distances (L l2 ) of the order of 50 m, for achieving resolutions now available at reactor sources. A few examples of spectrometer layout and corresponding design parameters for large-angle and for small-angle quasielastic scattering instruments are given. In the latter case higher energy resolution than for large-angle scattering is required and achieved. The use of phase-space transformers, neutron wavelength band-pass filters and multichromatic operation for the purpose of intensity-resolution optimization are discussed. This spectrometer can be designed to make full use of the pulsed source peak flux. Therefore, and because of a number of improvements, high resolution will be available at high intensity: for any given resolution the total intensity at the detectors, when placed at one of the planned new spallation sources (SNS, JSNS, ESS, AUSTRON) will be larger by at least three orders of magnitude than the total intensity of any of the presently existing instruments of this type in routine operation at steady

  2. Time-frequency energy density precipitation method for time-of-flight extraction of narrowband Lamb wave detection signals

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y., E-mail: thuzhangyu@foxmail.com; Huang, S. L., E-mail: huangsling@tsinghua.edu.cn; Wang, S.; Zhao, W. [State Key Laboratory of Power Systems, Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China)

    2016-05-15

    The time-of-flight of the Lamb wave provides an important basis for defect evaluation in metal plates and is the input signal for Lamb wave tomographic imaging. However, the time-of-flight can be difficult to acquire because of the Lamb wave dispersion characteristics. This work proposes a time-frequency energy density precipitation method to accurately extract the time-of-flight of narrowband Lamb wave detection signals in metal plates. In the proposed method, a discrete short-time Fourier transform is performed on the narrowband Lamb wave detection signals to obtain the corresponding discrete time-frequency energy density distribution. The energy density values at the center frequency for all discrete time points are then calculated by linear interpolation. Next, the time-domain energy density curve focused on that center frequency is precipitated by least squares fitting of the calculated energy density values. Finally, the peak times of the energy density curve obtained relative to the initial pulse signal are extracted as the time-of-flight for the narrowband Lamb wave detection signals. An experimental platform is established for time-of-flight extraction of narrowband Lamb wave detection signals, and sensitivity analysis of the proposed time-frequency energy density precipitation method is performed in terms of propagation distance, dispersion characteristics, center frequency, and plate thickness. For comparison, the widely used Hilbert–Huang transform method is also implemented for time-of-flight extraction. The results show that the time-frequency energy density precipitation method can accurately extract the time-of-flight with relative error of <1% and thus can act as a universal time-of-flight extraction method for narrowband Lamb wave detection signals.

  3. Time-frequency energy density precipitation method for time-of-flight extraction of narrowband Lamb wave detection signals

    International Nuclear Information System (INIS)

    Zhang, Y.; Huang, S. L.; Wang, S.; Zhao, W.

    2016-01-01

    The time-of-flight of the Lamb wave provides an important basis for defect evaluation in metal plates and is the input signal for Lamb wave tomographic imaging. However, the time-of-flight can be difficult to acquire because of the Lamb wave dispersion characteristics. This work proposes a time-frequency energy density precipitation method to accurately extract the time-of-flight of narrowband Lamb wave detection signals in metal plates. In the proposed method, a discrete short-time Fourier transform is performed on the narrowband Lamb wave detection signals to obtain the corresponding discrete time-frequency energy density distribution. The energy density values at the center frequency for all discrete time points are then calculated by linear interpolation. Next, the time-domain energy density curve focused on that center frequency is precipitated by least squares fitting of the calculated energy density values. Finally, the peak times of the energy density curve obtained relative to the initial pulse signal are extracted as the time-of-flight for the narrowband Lamb wave detection signals. An experimental platform is established for time-of-flight extraction of narrowband Lamb wave detection signals, and sensitivity analysis of the proposed time-frequency energy density precipitation method is performed in terms of propagation distance, dispersion characteristics, center frequency, and plate thickness. For comparison, the widely used Hilbert–Huang transform method is also implemented for time-of-flight extraction. The results show that the time-frequency energy density precipitation method can accurately extract the time-of-flight with relative error of <1% and thus can act as a universal time-of-flight extraction method for narrowband Lamb wave detection signals.

  4. Isobar Separation in a Multiple-Reflection Time-of-Flight Mass Spectrometer by Mass-Selective Re-Trapping

    Science.gov (United States)

    Dickel, Timo; Plaß, Wolfgang R.; Lippert, Wayne; Lang, Johannes; Yavor, Mikhail I.; Geissel, Hans; Scheidenberger, Christoph

    2017-06-01

    A novel method for (ultra-)high-resolution spatial mass separation in time-of-flight mass spectrometers is presented. Ions are injected into a time-of-flight analyzer from a radio frequency (rf) trap, dispersed in time-of-flight according to their mass-to-charge ratios and then re-trapped dynamically in the same rf trap. This re-trapping technique is highly mass-selective and after sufficiently long flight times can provide even isobaric separation. A theoretical treatment of the method is presented and the conditions for optimum performance of the method are derived. The method has been implemented in a multiple-reflection time-of-flight mass spectrometer and mass separation powers (FWHM) in excess of 70,000, and re-trapping efficiencies of up to 35% have been obtained for the protonated molecular ion of caffeine. The isobars glutamine and lysine (relative mass difference of 1/4000) have been separated after a flight time of 0.2 ms only. Higher mass separation powers can be achieved using longer flight times. The method will have important applications, including isobar separation in nuclear physics and (ultra-)high-resolution precursor ion selection in multiple-stage tandem mass spectrometry. [Figure not available: see fulltext.

  5. Polymer Analysis by Liquid Chromatography/Electrospray Ionization Time-of-Flight Mass Spectrometry.

    Science.gov (United States)

    Nielen, M W; Buijtenhuijs, F A

    1999-05-01

    Hyphenation of liquid chromatography (LC) techniques with electrospray ionization (ESI) orthogonal acceleration time-of-flight (oa-TOF) mass spectrometry (MS) provides both MS-based structural information and LC-based quantitative data in polymer analysis. In one experimental setup, three different LC modes are interfaced with MS:  size-exclusion chromatography (SEC/MS), gradient polymer elution chromatography (GPEC/MS), and liquid chromatography at the critical point of adsorption (LCCC/MS). In SEC/MS, both absolute mass calibration of the SEC column based on the polymer itself and determination of monomers and end groups from the mass spectra are achieved. GPEC/MS shows detailed chemical heterogeneity of the polymer and the chemical composition distribution within oligomer groups. In LCCC/MS, the retention behavior is primarily governed by chemical heterogeneities, such as different end group functionalities, and quantitative end group calculations can be easily made. The potential of these methods and the benefit of time-of-flight analyzers in polymer analysis are discussed using SEC/MS of a polydisperse poly(methyl methacrylate) sample, GPEC/MS of dipropoxylated bisphenol A/adipic acid polyester resin, LCCC/MS of alkylated poly(ethylene glycol), and LCCC/MS of terephthalic acid/neopentyl glycol polyester resin.

  6. Barrel time-of-flight detector for the PANDA experiment at FAIR

    Science.gov (United States)

    Gruber, L.; Brunner, S. E.; Marton, J.; Orth, H.; Suzuki, K.; PANDA Tof Group

    2016-07-01

    The barrel time-of-flight detector for the PANDA experiment at FAIR is foreseen as a Scintillator Tile (SciTil) Hodoscope based on several thousand small plastic scintillator tiles read-out with directly attached Silicon Photomultipliers (SiPMs). The main tasks of the system are an accurate determination of the time origin of particle tracks to avoid event mixing at high collision rates, relative time-of-flight measurements as well as particle identification in the low momentum regime. The main requirements are the use of a minimum material amount and a time resolution of σ < 100 ps. We have performed extensive optimization studies and prototype tests to prove the feasibility of the SciTil design and finalize the R&D phase. In a 2.7 GeV/c proton beam at Forschungszentrum Jülich a time resolution of about 80 ps has been achieved using SiPMs from KETEK and Hamamatsu with an active area of 3 × 3mm2. Employing the Digital Photon Counter from Philips a time resolution of about 30 ps has been reached.

  7. TOFPET 2: A high-performance circuit for PET time-of-flight

    Energy Technology Data Exchange (ETDEWEB)

    Di Francesco, Agostino, E-mail: agodifra@lip.pt [LIP, Lisbon (Portugal); Bugalho, Ricardo [LIP, Lisbon (Portugal); PETsys Electronics, Oeiras (Portugal); Oliveira, Luis [CTS-UNINOVA, DEE FCT-UNL, Caparica (Portugal); Rivetti, Angelo [INFN - sez. Torino (Italy); Rolo, Manuel [LIP, Lisbon (Portugal); INFN - sez. Torino (Italy); Silva, Jose C.; Varela, Joao [LIP, Lisbon (Portugal); PETsys Electronics, Oeiras (Portugal)

    2016-07-11

    We present a readout and digitization ASIC featuring low-noise and low-power for time-of flight (TOF) applications using SiPMs. The circuit is designed in standard CMOS 110 nm technology, has 64 independent channels and is optimized for time-of-flight measurement in Positron Emission Tomography (TOF-PET). The input amplifier is a low impedance current conveyor based on a regulated common-gate topology. Each channel has quad-buffered analogue interpolation TDCs (time binning 20 ps) and charge integration ADCs with linear response at full scale (1500 pC). The signal amplitude can also be derived from the measurement of time-over-threshold (ToT). Simulation results show that for a single photo-electron signal with charge 200 (550) fC generated by a SiPM with (320 pF) capacitance the circuit has 24 (30) dB SNR, 75 (39) ps r.m.s. resolution, and 4 (8) mW power consumption. The event rate is 600 kHz per channel, with up to 2 MHz dark counts rejection.

  8. Laser desorption and time-of-flight mass spectrometry. Fundamentals .Applications

    International Nuclear Information System (INIS)

    Chaurand, P.

    1994-11-01

    Time-of-flight mass spectrometry is a very powerful technique for the analysis of heavy molecular ions (100 000 u and more). The ejection in the gas phase and the ionization of these molecules is now possible through the MALDI technique (Matrix Assisted Laser Desorption Ionization). This technique consists in mixing the heavy molecules to be analysed with a organic matrix which absorbs at the wavelength of the laser. The necessary irradiance are of the order of 10 6 W/cm 2 . In these conditions we have shown that the mass resolutions are optimum and that the relative mass accuracies are of the order of 10 -4 . We have also demonstrated that the emission angle of the molecular ions in MALDI depends on the incident angle of the laser light. During the desorption process, the molecular ions are emitted in the opposite direction of the incident laser light. This effect is particularly important for the design of the accelerating stage of the time-of-flight spectrometers. Problems relative to the detection of these heavy molecular ions have been studied in details between 0.5 10 4 m/s and 10 5 m/s. The velocity threshold of the electronic emission is lower than the value of 0.5 10 4 m/s. The relation between the electronic emission and the projectile velocity is complex. Finally, examples on mass identification of C 60 molecules and derivated C 60 are presented. Desorption methods are compared. (author). 32 refs., 34 figs

  9. Studying time of flight imaging through scattering media across multiple size scales (Conference Presentation)

    Science.gov (United States)

    Velten, Andreas

    2017-05-01

    Light scattering is a primary obstacle to optical imaging in a variety of different environments and across many size and time scales. Scattering complicates imaging on large scales when imaging through the atmosphere when imaging from airborne or space borne platforms, through marine fog, or through fog and dust in vehicle navigation, for example in self driving cars. On smaller scales, scattering is the major obstacle when imaging through human tissue in biomedical applications. Despite the large variety of participating materials and size scales, light transport in all these environments is usually described with very similar scattering models that are defined by the same small set of parameters, including scattering and absorption length and phase function. We attempt a study of scattering and methods of imaging through scattering across different scales and media, particularly with respect to the use of time of flight information. We can show that using time of flight, in addition to spatial information, provides distinct advantages in scattering environments. By performing a comparative study of scattering across scales and media, we are able to suggest scale models for scattering environments to aid lab research. We also can transfer knowledge and methodology between different fields.

  10. Contribution of time-of-flight information to limited-angle positron tomography

    International Nuclear Information System (INIS)

    Macdonald, B.; Perez-Mendez, V.; Tam, K.C.

    1981-10-01

    Limited-angle emission tomography was investigated using a two-dimensional phantom to generate positron events simulating a camera with two opposed parallel position-sensitive detectors collecting data within a 90 0 cone. The data, backprojected onto lines passing through the phantom volume, is used with a matrix reconstruction method to provide two-dimensional images. Image quality was measured using the standard deviation of the reconstructions with respect to the original phantom. The application of Phillips-Twomey smoothing to the deconvolution matrices has substantially improved the original reconstructions, a factor of 1.9 in signal to noise ratio, giving S/N = 3.4 for a phantom having an average of 150 events/pixel. Using photon time-of-flight to restrict the reconstruction volume a further considerable improvement is made. When the time-of-flight limited the contributing volume to 4 lines out of 11 the improvement was another factor of 1.9 giving S/N = 6.0 for the same phantom. Comparable increases in signal to noise ratios are expected for three-dimensional reconstructions

  11. Laser ionization time of flight mass spectrometer for isotope mass detection and elemental analysis of materials

    Science.gov (United States)

    Ahmed, Nasar; Ahmed, Rizwan; Umar, Z. A.; Aslam Baig, M.

    2017-08-01

    In this paper we present the construction and modification of a linear time-of-flight mass spectrometer to improve its mass resolution. This system consists of a laser ablation/ionization section based on a Q-switched Nd:YAG laser (532 nm, 500 mJ, 5 ns pulse duration) integrated with a one meter linear time-of-flight mass spectrometer coupled with an electric sector and a magnetic lens and outfitted with a channeltron electron multiplier for ion detection. The resolution of the system has been improved by optimizing the accelerating potential and inserting a magnetic lens after the extraction region. The isotopes of lithium, lead and cadmium samples have been resolved and detected in accordance with their natural abundance. The capability of the system has been further exploited to determine the elemental composition of a brass alloy, having a certified composition of zinc and copper. Our results are in excellent agreement with its certified composition. This setup is found to be extremely efficient and convenient for fast analyses of any solid sample.

  12. Modeling of a 3D CMOS sensor for time-of-flight measurements

    Science.gov (United States)

    Kuhla, Rico; Hosticka, Bedrich J.; Mengel, Peter; Listl, Ludwig

    2004-02-01

    A solid state 3D-CMOS camera system for direct time-of-flight image acquisition consisting of a CMOS imaging sensor, a laser diode module for active laser pulse illumination and all optics for image forming is presented, including MDSI & CDS algorithms for time-of-flight evaluation from intensity imaging. The investigation is carried out using ideal and real signals. For real signals the narrow infrared laser pulse of the laser diode module and the shutter function of the sensors column circuit were sampled by a new sampling procedure. A discrete sampled shutter function was recorded by using the impulse response of a narrow pulse of FWHM=50ps and an additional delay block with step size of Δτ = 0.25ns. A deterministic system model based on LTI transfer functions was developed. The visual shutter windows give a good understanding of differences between ideal and real output functions of measurement system. Simulations of shutter and laser pulse brought out an extended linear delay domain from MDSI. A stochastic model for the transfer function and photon noise in time domain was developed. We used the model to investigate noise in variation the laser pulse shutter configuration.

  13. TOF plotter - a program to perform routine analysis time-of-flight mass spectral data

    International Nuclear Information System (INIS)

    Knippel, Brad C.; Padgett, Clifford W.; Marcus, R. Kenneth

    2004-01-01

    The main article discusses the operation and application of the program to mass spectral data files. This laboratory has recently reported the construction and characterization of a linear time-of-flight mass spectrometer (ToF-MS) utilizing a radio frequency glow discharge ionization source. Data acquisition and analysis was performed using a digital oscilloscope and Microsoft Excel, respectively. Presently, no software package is available that is specifically designed for time-of-flight mass spectral analysis that is not instrument dependent. While spreadsheet applications such as Excel offer tremendous utility, they can be cumbersome when repeatedly performing tasks which are too complex or too user intensive for macros to be viable. To address this situation and make data analysis a faster, simpler task, our laboratory has developed a Microsoft Windows-based software program coded in Microsoft Visual Basic. This program enables the user to rapidly perform routine data analysis tasks such as mass calibration, plotting and smoothing on x-y data sets. In addition to a suite of tools for data analysis, a number of calculators are built into the software to simplify routine calculations pertaining to linear ToF-MS. These include mass resolution, ion kinetic energy and single peak identification calculators. A detailed description of the software and its associated functions is presented followed by a characterization of its performance in the analysis of several representative ToF-MS spectra obtained from different GD-ToF-MS systems

  14. Satellite-borne time-of-flight particle spectrometer and its response to protons

    International Nuclear Information System (INIS)

    Shino, T.

    1994-01-01

    One of the purposes of the high energy particle (HEP) experiment of the GEOTAIL satellite launched in 1992 is the elucidation of plasma dynamics in the tail region of planetary magnetosphere. For that purpose, a low energy particle detector (LD) was on board, which mainly observed relatively low energy particles up to a few MeV. The LD is the particle spectrometer based on time of flight technique. In order to confirm further its sensitivity to high energy protons, the beam experiment was carried out at Waseda University using the engineering model of the LD spectrometer that is exactly the same as the launched one. The LD spectrometer is shown, and its functions are explained. The LD was designed to identify electrons of 30 - 400 keV, protons of 30 - 1500 keV, helium ions of 80 - 4000 keV, and heavy ions (mainly C, N and O) of 160 - 1500 keV. The relation of measured time of flight signals with energy signals is shown. There are several factors that determine the detection efficiency of the spectrometer, which are discussed. The experiment and the results are reported. (K.I.)

  15. Calculations of neutron spectra after neutron-neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, B E [Gettysburg College, Box 405, Gettysburg, PA 17325 (United States); Stephenson, S L [Gettysburg College, Box 405, Gettysburg, PA 17325 (United States); Howell, C R [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Mitchell, G E [North Carolina State University, Raleigh, NC 27695-8202 (United States); Tornow, W [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Furman, W I [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Lychagin, E V [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Muzichka, A Yu [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Nekhaev, G V [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Strelkov, A V [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Sharapov, E I [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Shvetsov, V N [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)

    2004-09-01

    A direct neutron-neutron scattering length, a{sub nn}, measurement with the goal of 3% accuracy (0.5 fm) is under preparation at the aperiodic pulsed reactor YAGUAR. A direct measurement of a{sub nn} will not only help resolve conflicting results of a{sub nn} by indirect means, but also in comparison to the proton-proton scattering length, a{sub pp}, shed light on the charge-symmetry of the nuclear force. We discuss in detail the analysis of the nn-scattering data in terms of a simple analytical expression. We also discuss calibration measurements using the time-of-flight spectra of neutrons scattered on He and Ar gases and the neutron activation technique. In particular, we calculate the neutron velocity and time-of-flight spectra after scattering neutrons on neutrons and after scattering neutrons on He and Ar atoms for the proposed experimental geometry, using a realistic neutron flux spectrum-Maxwellian plus epithermal tail. The shape of the neutron spectrum after scattering is appreciably different from the initial spectrum, due to collisions between thermal-thermal and thermal-epithermal neutrons. At the same time, the integral over the Maxwellian part of the realistic scattering spectrum differs by only about 6 per cent from that of a pure Maxwellian nn-scattering spectrum.

  16. COINTOF mass spectrometry: design of a time-of-flight analyzer and development of the analysis method

    International Nuclear Information System (INIS)

    Teyssier, C.

    2012-01-01

    DIAM (Device for the irradiation of molecular clusters) is a newly designed experimental setup to investigate processes resulting from the irradiation of molecular nano-systems by 20-150 keV protons. One of its specificities relies on the original technique of mass spectrometry named COINTOF (Correlated Ion and Neutral Time Of Flight) consisting in correlated measurements of the time of flight of charged and neutral fragments produced by the dissociation of a single molecular ion parent. A strategy of treatment and analysis of the detection signals was developed to distinguish two fragments close in time ( 3 O + and two water molecules. The distribution of the time of flight difference between the two neutral fragments is measured providing an estimate of the kinetic energy release of a few eV. In parallel, a second time-of-flight mass spectrometer was designed. It associates a linear time-of-flight and an orthogonal time-of-flight and integrates position detectors (delay line anode). Simulations demonstrate the potentials of the new analyzer. Finally, research works were led at the laboratory R.-J. A. Levesque (Universite de Montreal) on the imaging capabilities of the multi-pixel detectors of the MPX-ATLAS collaboration. (author)

  17. Time-of-flight measurements of the plasma density in the T-11M tokamak

    International Nuclear Information System (INIS)

    Petrov, V. G.; Petrov, A. A.; Malyshev, A. Yu.; Markov, V. K.; Babarykin, A. V.

    2006-01-01

    The average plasma density in the T-11M tokamak is determined by means of an O-mode time-of-flight refractometer measuring the propagation time τ of microwave pulses through the plasma. Since the front duration τ fr of these pulses is shorter than 2 ns, filtering the measured signal cannot reduce the signal-to-noise ratio below a certain level. This circumstance impedes the use of this diagnostics in larger devices, where the signals may be substantially attenuated because of the larger chamber size and larger waveguide losses. There are several ways to overcome these difficulties: to raise the microwave power, to increase the sensitivity of the receivers, etc. In this paper, a technique is described that is based on the differential method for determining the propagation time of a microwave signal through the plasma. In this method, the plasma is probed by two continuous microwaves with close frequencies and the phase difference between them Δφ 12 is measured. As long as the condition Δφ 12 < 2π is satisfied, the measurements are unambiguous, because there are no phase jumps by a value multiple of 2π, as is usually the case in conventional interferometers at an increased level of MHD activity, in regimes with a rapid density growth, etc. This method allows the signal to be filtered, thereby ensuring an appreciable improvement in the signal-to-noise ratio in comparison with the pulsed methods. The first measurements of the average density along the +3-cm chord were performed with the help of this new differential time-of-flight refractometer in the T-11M tokamak. The refractometry data agree well with the interferometric data and are used to recover the plasma-density profile

  18. Neutron nuclear physics under the neutron science project

    Energy Technology Data Exchange (ETDEWEB)

    Chiba, Satoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-11-01

    The concept of fast neutron physics facility in the Neutron Science Research project is described. This facility makes use of an ultra-short proton pulse (width < 1 ns) for fast neutron time-of-flight works. The current design is based on an assumption of the maximum proton current of 100 {mu}A. Available neutron fluence and energy resolution are explained. Some of the research subjects to be performed at this facility are discussed. (author)

  19. Development of grazing incidence devices for space-borne time of flight mass spectrometry

    Science.gov (United States)

    Cadu, A.; Devoto, P.; Louarn, P.; Sauvaud, J.-A.

    2012-04-01

    Time of flight mass spectrometer is widely used to study space plasmas in planetary and solar missions. This space-borne instrument selects ions in function of their energy through an electrostatic analyzer. Particles are then post-accelerated to energies in the range of 20 keV to cross a carbon foil. At the foil exit, electrons are emitted and separated from ion beam in the time of flight section. A first detector (a Micro-Channel Plate or MCP) emits a start signal at electron arrival and a second one emits a stop signal at incident ion end of path. The time difference gives the speed of the particle and its mass can be calculated, knowing its initial energy. However, current instruments suffer from strong limitations. The post acceleration needs very high voltage power supplies which are heavy, have a high power consumption and imply technical constraints for the development. A typical instrument weighs from 5 to 6 kg, includes a 20 kV power supply, consumes a least 5 W and encounters corona effect and electrical breakdown problems. Moreover, despite the particle high energy range, scattering and straggling phenomena in the carbon foil significantly reduce the instrument overall resolution. Some methods, such as electrostatic focus lenses or reflectrons, really improve mass separation but global system efficiency remains very low because of the charge state dependence of such devices. The main purpose of our work is to replace carbon foil by grazing incidence MCP's - also known as MPO's, for Micro Pore Optics - for electron emission. Thus, incident particles would back-scatter onto the channel inner surface with an angle of a few degrees. With this solution, we can decrease dispersion sources and lower the power supplies to post accelerate ions. The result would be a lighter and simpler instrument with a substantial resolution improvement. We have first simulated MPO's behavior with TRIM and MARLOWE Monte-Carlo codes. Energy scattering and output angle computed

  20. Quantitative myocardial blood flow imaging with integrated time-of-flight PET-MR.

    Science.gov (United States)

    Kero, Tanja; Nordström, Jonny; Harms, Hendrik J; Sörensen, Jens; Ahlström, Håkan; Lubberink, Mark

    2017-12-01

    The use of integrated PET-MR offers new opportunities for comprehensive assessment of cardiac morphology and function. However, little is known on the quantitative accuracy of cardiac PET imaging with integrated time-of-flight PET-MR. The aim of the present work was to validate the GE Signa PET-MR scanner for quantitative cardiac PET perfusion imaging. Eleven patients (nine male; mean age 59 years; range 46-74 years) with known or suspected coronary artery disease underwent 15 O-water PET scans at rest and during adenosine-induced hyperaemia on a GE Discovery ST PET-CT and a GE Signa PET-MR scanner. PET-MR images were reconstructed using settings recommended by the manufacturer, including time-of-flight (TOF). Data were analysed semi-automatically using Cardiac VUer software, resulting in both parametric myocardial blood flow (MBF) images and segment-based MBF values. Correlation and agreement between PET-CT-based and PET-MR-based MBF values for all three coronary artery territories were assessed using regression analysis and intra-class correlation coefficients (ICC). In addition to the cardiac PET-MR reconstruction protocol as recommended by the manufacturer, comparisons were made using a PET-CT resolution-matched reconstruction protocol both without and with TOF to assess the effect of time-of-flight and reconstruction parameters on quantitative MBF values. Stress MBF data from one patient was excluded due to movement during the PET-CT scanning. Mean MBF values at rest and stress were (0.92 ± 0.12) and (2.74 ± 1.37) mL/g/min for PET-CT and (0.90 ± 0.23) and (2.65 ± 1.15) mL/g/min for PET-MR (p = 0.33 and p = 0.74). ICC between PET-CT-based and PET-MR-based regional MBF was 0.98. Image quality was improved with PET-MR as compared to PET-CT. ICC between PET-MR-based regional MBF with and without TOF and using different filter and reconstruction settings was 1.00. PET-MR-based MBF values correlated well with PET-CT-based MBF values and

  1. Measurement of the Slowing-Down and Thermalization Time of Neutrons in Water

    Energy Technology Data Exchange (ETDEWEB)

    Moeller, E [AB Atomenergi, Nykoeping (Sweden); Sjoestrand, N G [Chalmers Univ. of Technology, Goeteborg (Sweden)

    1963-11-15

    The experimental equipment for the study of the time behaviour of neutrons during slowing-down and thermalization in a moderator by the use of a pulsed van de Graaff accelerator as a neutron source is described. Information on the change with time of the neutron spectrum is obtained from its reaction with spectrum indicators, the reaction rate being observed by the detection of capture gamma rays. The time resolution may be chosen in the range 0.01 to 5 {mu}s. Measurements have been made for water with cadmium, gadolinium and samarium as indicators dissolved in the medium. A slowing- down time to 0.2 eV of 2.7 {+-} 0.4 {mu}s and a total thermalization time of 25 - 30 {mu}s were obtained. From 9 {mu}s after the injection, the results are well described by the assumption of the flux as a Maxwell distribution cooling down to the moderator temperature with a thermalization time constant of 4.1 {+-} 0.4 {mu}s.

  2. High precision mass measurements of thermalized relativistic uranium projectile and fission fragments with a multiple-reflection time-of-flight mass spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Ayet San Andres, Samuel [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Justus Liebig Universitaet, Giessen (Germany); Collaboration: FRS Ion Catcher-Collaboration

    2016-07-01

    At the FRS Ion Catcher at GSI, a relativistic beam of {sup 238}U at 1GeV/u was used to produce fission and projectile fragments on a beryllium target. The ions were separated in-flight at the FRS, thermalized in a cryogenic stopping cell and transferred to a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) where high precision mass measurements were performed. The masses of several fission and projectile fragments were measured (including short-lived nuclei with half-lives down to 18 ms) and the possibility of tailoring an isomerically clean beam for other experiments was demonstrated. With the demonstrated performance of the MR-TOF-MS and the expected production rates of exotic nuclei far from stability at the next-generation facilities such as FAIR, novel mass measurements of nuclei close to the neutron drip line will be possible and key information for understanding the r-process will be available. The results from the last experiment and an outlook of possible future mass measurements close to the neutron drip line at FAIR with the MR-TOF-MS are presented.

  3. Time-frequency energy density precipitation method for time-of-flight extraction of narrowband Lamb wave detection signals.

    Science.gov (United States)

    Zhang, Y; Huang, S L; Wang, S; Zhao, W

    2016-05-01

    The time-of-flight of the Lamb wave provides an important basis for defect evaluation in metal plates and is the input signal for Lamb wave tomographic imaging. However, the time-of-flight can be difficult to acquire because of the Lamb wave dispersion characteristics. This work proposes a time-frequency energy density precipitation method to accurately extract the time-of-flight of narrowband Lamb wave detection signals in metal plates. In the proposed method, a discrete short-time Fourier transform is performed on the narrowband Lamb wave detection signals to obtain the corresponding discrete time-frequency energy density distribution. The energy density values at the center frequency for all discrete time points are then calculated by linear interpolation. Next, the time-domain energy density curve focused on that center frequency is precipitated by least squares fitting of the calculated energy density values. Finally, the peak times of the energy density curve obtained relative to the initial pulse signal are extracted as the time-of-flight for the narrowband Lamb wave detection signals. An experimental platform is established for time-of-flight extraction of narrowband Lamb wave detection signals, and sensitivity analysis of the proposed time-frequency energy density precipitation method is performed in terms of propagation distance, dispersion characteristics, center frequency, and plate thickness. For comparison, the widely used Hilbert-Huang transform method is also implemented for time-of-flight extraction. The results show that the time-frequency energy density precipitation method can accurately extract the time-of-flight with relative error of wave detection signals.

  4. Time-of-flight spectroscopy of metastable photodissociation fragments in vacuum-UV

    International Nuclear Information System (INIS)

    Fisher, C.H.; Welge, K.H.

    1974-01-01

    Photofragment time-of-flight experiments carried out at photon energies > approximately 11.8eV (1050A) is reported. Processes of the kind AB+hν→A*+B have been investigated where A* is an electronically excited species in a metastable state that can be detected by Auger electron emission from metal surfaces. The present work has been concerned with the identification of dissociation processes from N 2 O, CO 2 , and OCS, measurement of recoil energies and, for the first time, also angular dependent experiments. One objective of the work was to further explore the potential of such studies in the vacuum uv. Their feasibility was demonstrated previously in preliminary experiments

  5. Pose estimation and tracking of non-cooperative rocket bodies using Time-of-Flight cameras

    Science.gov (United States)

    Gómez Martínez, Harvey; Giorgi, Gabriele; Eissfeller, Bernd

    2017-10-01

    This paper presents a methodology for estimating the position and orientation of a rocket body in orbit - the target - undergoing a roto-translational motion, with respect to a chaser spacecraft, whose task is to match the target dynamics for a safe rendezvous. During the rendezvous maneuver the chaser employs a Time-of-Flight camera that acquires a point cloud of 3D coordinates mapping the sensed target surface. Once the system identifies the target, it initializes the chaser-to-target relative position and orientation. After initialization, a tracking procedure enables the system to sense the evolution of the target's pose between frames. The proposed algorithm is evaluated using simulated point clouds, generated with a CAD model of the Cosmos-3M upper stage and the PMD CamCube 3.0 camera specifications.

  6. Heavy ion time-of-flight ERDA of high dose metal implanted germanium

    Energy Technology Data Exchange (ETDEWEB)

    Dytlewski, N.; Evans, P.J.; Noorman, J.T. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Wielunski, L.S. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics; Bunder, J. [New South Wales Univ., Wollongong, NSW (Australia). Wollongong Univ. Coll

    1996-12-31

    With the thick Ge substrates used in ion implantation, RBS can have difficulty in resolving the mass-depth ambiguities when analysing materials composed of mixtures of elements with nearly equal masses. Additional, and complimentary techniques are thus required. This paper reports the use of heavy ion time-of-flight elastic recoil detection analysis (ToF- ERDA), and conventional RBS in the analysis of Ge(100) implanted with high dose Ti and Cu ions from a MEWA ion source . Heavy ion ToF ERDA has been used to resolve, and profile the implanted transition metal species, and also to study any oxygen incorporation into the sample resulting from the implantation, or subsequential reactions with air or moisture. This work is part of a study on high dose metal ion implantation of medium atomic weight semiconductor materials. 13 refs., 6 figs.

  7. Stochastic calculus analysis of optical time-of-flight range imaging and estimation of radial motion.

    Science.gov (United States)

    Streeter, Lee

    2017-07-01

    Time-of-flight range imaging is analyzed using stochastic calculus. Through a series of interpretations and simplifications, the stochastic model leads to two methods for estimating linear radial velocity: maximum likelihood estimation on the transition probability distribution between measurements, and a new method based on analyzing the measured correlation waveform and its first derivative. The methods are tested in a simulated motion experiment from (-40)-(+40)  m/s, with data from a camera imaging an object on a translation stage. In tests maximum likelihood is slow and unreliable, but when it works it estimates the linear velocity with standard deviation of 1 m/s or better. In comparison the new method is fast and reliable but works in a reduced velocity range of (-20)-(+20)  m/s with standard deviation ranging from 3.5 m/s to 10 m/s.

  8. Heavy ion time-of-flight ERDA of high dose metal implanted germanium

    Energy Technology Data Exchange (ETDEWEB)

    Dytlewski, N; Evans, P J; Noorman, J T [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Wielunski, L S [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics; Bunder, J [New South Wales Univ., Wollongong, NSW (Australia). Wollongong Univ. Coll

    1997-12-31

    With the thick Ge substrates used in ion implantation, RBS can have difficulty in resolving the mass-depth ambiguities when analysing materials composed of mixtures of elements with nearly equal masses. Additional, and complimentary techniques are thus required. This paper reports the use of heavy ion time-of-flight elastic recoil detection analysis (ToF- ERDA), and conventional RBS in the analysis of Ge(100) implanted with high dose Ti and Cu ions from a MEWA ion source . Heavy ion ToF ERDA has been used to resolve, and profile the implanted transition metal species, and also to study any oxygen incorporation into the sample resulting from the implantation, or subsequential reactions with air or moisture. This work is part of a study on high dose metal ion implantation of medium atomic weight semiconductor materials. 13 refs., 6 figs.

  9. Ion-induced particle desorption in time-of-flight medium energy ion scattering

    Science.gov (United States)

    Lohmann, S.; Primetzhofer, D.

    2018-05-01

    Secondary ions emitted from solids upon ion impact are studied in a time-of-flight medium energy ion scattering (ToF-MEIS) set-up. In order to investigate characteristics of the emission processes and to evaluate the potential for surface and thin film analysis, experiments employing TiN and Al samples were conducted. The ejected ions exhibit a low initial kinetic energy of a few eV, thus, requiring a sufficiently high acceleration voltage for detection. Molecular and atomic ions of different charge states originating both from surface contaminations and the sample material are found, and relative yields of several species were determined. Experimental evidence that points towards a predominantly electronic sputtering process is presented. For emitted Ti target atoms an additional nuclear sputtering component is suggested.

  10. Energy and time of flight measurements of REX-ISOLDE stable beams using Si detectors

    CERN Document Server

    Cantero, E D; Fraser, M A; Lanaia, D; Sosa, A; Voulot, D; Zocca, F

    2014-01-01

    In this paper we present energy and time spectroscopy measurements for the stable beams of REX-ISOLDE obtained using Si detectors. By using an alpha source as a calibration reference, the absolute energy E of stable beam particles (A/q = 4) was determined in spectroscopy mode in the energy range 1 MeV < E < 8 MeV (0.30 MeV/u < E/A < 1.87 MeV/u). The time of flight of the beam particles (2.18 MeV/u < E/A < 2.27 MeV/u) was determined by installing identical Si detectors in two diagnostic boxes separated by 7.7 m. The results obtained with these two techniques are compared with the values obtained by dipole scans using a bending magnet. The measurements took place between January and February of 2013.

  11. Development of time-of-flight RBS system using multi microchannel plates

    International Nuclear Information System (INIS)

    Nguyen, N.V.; Abo, S.; Lohner, T.; Sawaragi, H.; Wakaya, F.; Takai, M.

    2007-01-01

    A new time-of-flight Rutherford backscattering spectroscopy (TOF-RBS) system with two circular microchannel plates (MCPs) installed at a distance of 140 mm from a sample holder and a scattering angle of 125 o and a 100 kV focused ion beam column having a liquid metal ion source (LMIS) of AuSiBe alloy has been assembled to obtain high counting rate and enhanced mass resolution. The possible influence of the two MCPs by logical summation of the output signals on the time resolution was investigated by measuring dedicated thin deposited metallic samples. And, the time resolution was found in the range of 1.5-2 ns

  12. Laser Time-of-Flight Mass Spectrometry for Future In Situ Planetary Missions

    Science.gov (United States)

    Getty, S. A.; Brinckerhoff, W. B.; Cornish, T.; Ecelberger, S. A.; Li, X.; Floyd, M. A. Merrill; Chanover, N.; Uckert, K.; Voelz, D.; Xiao, X.; hide

    2012-01-01

    Laser desorption/ionization time-of-flight mass spectrometry (LD-TOF-MS) is a versatile, low-complexity instrument class that holds significant promise for future landed in situ planetary missions that emphasize compositional analysis of surface materials. Here we describe a 5kg-class instrument that is capable of detecting and analyzing a variety of analytes directly from rock or ice samples. Through laboratory studies of a suite of representative samples, we show that detection and analysis of key mineral composition, small organics, and particularly, higher molecular weight organics are well suited to this instrument design. A mass range exceeding 100,000 Da has recently been demonstrated. We describe recent efforts in instrument prototype development and future directions that will enhance our analytical capabilities targeting organic mixtures on primitive and icy bodies. We present results on a series of standards, simulated mixtures, and meteoritic samples.

  13. System architecture for high speed reconstruction in time-of-flight positron tomography

    International Nuclear Information System (INIS)

    Campagnolo, R.E.; Bouvier, A.; Chabanas, L.; Robert, C.

    1985-06-01

    A new generation of Time Of Flight (TOF) positron tomograph with high resolution and high count rate capabilities is under development in our group. After a short recall of the data acquisition process and image reconstruction in a TOF PET camera, we present the data acquisition system which achieves a data transfer rate of 0.8 mega events per second or more if necessary in list mode. We describe the reconstruction process based on a five stages pipe line architecture using home made processors. The expected performance with this architecture is a time reconstruction of six seconds per image (256x256 pixels) of one million events. This time could be reduce to 4 seconds. We conclude with the future developments of the system

  14. Low-pressure, multistep, multiwire proportional counter for the time-of-flight isochronous spectrometer

    International Nuclear Information System (INIS)

    Vieira, D.J.

    1985-01-01

    A low-pressure, multistep, multiwire proportional counter (MSMWPC) has been developed for the characterization and testing of the time-of-flight isochronous (TOFI) spectrometer and its associated secondary-beam transport line. This type of counter was selected because of its high sensitivity, large dynamic range, and good position (0.2 mm FWHM) and timing (180 ps FWHM) resolution. Furthermore, because the counter operates at low gas pressures (1-10 torr) and high electric-field strengths, which enable short collection times, it can be used as a transmission counter with thin gas-isolation windows and it can operate at high counting rates. Here the authors discuss the basic operating principle of the MSMWPC, describe the technical details of the detector and signal processing, and report on the performance they have measured for alpha particles and fission fragments

  15. Ion optics of a new time-of-flight mass spectrometer for quantitative surface analysis

    International Nuclear Information System (INIS)

    Veryovkin, Igor V.; Calaway, Wallis F.; Pellin, Michael J.

    2004-01-01

    A new time-of-flight instrument for quantitative surface analysis was developed and constructed at Argonne National Laboratory. It implements ion sputtering and laser desorption for probing analyzed samples and can operate in regimes of secondary neutral mass spectrometry with laser post-ionization and secondary ion mass spectrometry. The instrument incorporates two new ion optics developments: (1) 'push-pull' front end ion optics and (2) focusing and deflecting lens. Implementing these novel elements significantly enhance analytical capabilities of the instrument. Extensive three-dimensional computer simulations of the instrument were conducted in SIMION 3D (c) to perfect its ion optics. The operating principles of the new ion optical systems are described, and a scheme of the new instrument is outlined together with its operating modes

  16. An Improvement on Space Focusing Resolution in Two-Field Time-of-Flight Mass Spectrometers

    International Nuclear Information System (INIS)

    Yildirim, M.; Aydin, R.; Akin, U.; Kilic, H. S.; Sise, O.; Ulu, M.; Dogan, M.

    2007-01-01

    Time-of-Flight Mass Spectrometer (TOFMS) is a sophisticated device for the mass selective analysis of a variety of samples. The main limitation on TOFMS technique is the obtainable resolution where the two main limiting factors are the initial space and energy spread of particles created in ionization region. Similar charged particles starting at different points will reach the detector at different times. So, this problem makes space focusing is very important subject. We have presented principles of two-fields TOFMS with second-order space focusing both using analytical methods and ray-tracing simulation. This work aims understanding of ion optical system clearly and gives hint of expectation for future developments

  17. Deconvolution based attenuation correction for time-of-flight positron emission tomography

    Science.gov (United States)

    Lee, Nam-Yong

    2017-10-01

    For an accurate quantitative reconstruction of the radioactive tracer distribution in positron emission tomography (PET), we need to take into account the attenuation of the photons by the tissues. For this purpose, we propose an attenuation correction method for the case when a direct measurement of the attenuation distribution in the tissues is not available. The proposed method can determine the attenuation factor up to a constant multiple by exploiting the consistency condition that the exact deconvolution of noise-free time-of-flight (TOF) sinogram must satisfy. Simulation studies shows that the proposed method corrects attenuation artifacts quite accurately for TOF sinograms of a wide range of temporal resolutions and noise levels, and improves the image reconstruction for TOF sinograms of higher temporal resolutions by providing more accurate attenuation correction.

  18. Acoustic tweezers via sub-time-of-flight regime surface acoustic waves.

    Science.gov (United States)

    Collins, David J; Devendran, Citsabehsan; Ma, Zhichao; Ng, Jia Wei; Neild, Adrian; Ai, Ye

    2016-07-01

    Micrometer-scale acoustic waves are highly useful for refined optomechanical and acoustofluidic manipulation, where these fields are spatially localized along the transducer aperture but not along the acoustic propagation direction. In the case of acoustic tweezers, such a conventional acoustic standing wave results in particle and cell patterning across the entire width of a microfluidic channel, preventing selective trapping. We demonstrate the use of nanosecond-scale pulsed surface acoustic waves (SAWs) with a pulse period that is less than the time of flight between opposing transducers to generate localized time-averaged patterning regions while using conventional electrode structures. These nodal positions can be readily and arbitrarily positioned in two dimensions and within the patterning region itself through the imposition of pulse delays, frequency modulation, and phase shifts. This straightforward concept adds new spatial dimensions to which acoustic fields can be localized in SAW applications in a manner analogous to optical tweezers, including spatially selective acoustic tweezers and optical waveguides.

  19. Study on time of flight property of electron optical systems by differential algebraic method

    International Nuclear Information System (INIS)

    Cheng Min; Tang Tiantong; Yao Zhenhua

    2002-01-01

    Differential algebraic method is a powerful and promising technique in computer numerical analysis. When applied to nonlinear dynamics systems, the arbitrary high-order transfer properties of the systems can be computed directly with high precision. In this paper, the principle of differential algebra is applied to study on the time of flight (TOF) property of electron optical systems and their arbitrary order TOF transfer properties can be numerically calculated out. As an example, TOF transfer properties of a uniform magnetic sector field analyzer have been studied by differential algebraic method. Relative errors of the first-order and second-order TOF transfer coefficients of the magnetic sector field analyzer are of the order 10 -11 or smaller compared with the analytic solutions. It is proved that differential algebraic TOF method is of high accuracy and very helpful for high-order TOF transfer property analysis of electron optical systems. (author)

  20. Precise Time-of-Flight Calculation For 3-D Synthetic Aperture Focusing

    DEFF Research Database (Denmark)

    Andresen, Henrik; Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2009-01-01

    in elevation can be achieved by applying synthetic aperture (SA) focusing to the beamformed in-plane RF-data. The proposed method uses a virtual source (VS) placed at the elevation focus for postbeamforming. This has previously been done in two steps, in plane focusing followed by SA post-focusing in elevation......, because of a lack of a simple expression for the exact time of flight (ToF). This paper presents a new method for calculating the ToF for a 3D case in a single step using a linear array. This method is more flexible than the previously proposed method and is able to beamform a fewer number of points much...

  1. A new beam profile monitor and time of flight system for CologneAMS

    Energy Technology Data Exchange (ETDEWEB)

    Pascovici, G. [CologneAMS, University of Cologne (Germany); Dewald, A., E-mail: dewald@ikp.uni-koeln.de [CologneAMS, University of Cologne (Germany); Institute of Nuclear Physics, University of Cologne (Germany); Heinze, S., E-mail: heinze@ikp.uni-koeln.de [CologneAMS, University of Cologne (Germany); Fink, L.; Mueller-Gatermann, C.; Schiffer, M.; Feuerstein, C. [CologneAMS, University of Cologne (Germany); Pfeiffer, M.; Jolie, J.; Thiel, S.; Zell, K.O.; Arnopolina, O. [Institute of Nuclear Physics, University of Cologne (Germany); Blanckenburg, F. von [GFZ, German Research Centre for Geosciences, Potsdam (Germany)

    2013-01-15

    A complex beam detector consisting of a high-resolution beam profile monitor (BPM) and a time of flight (TOF) spectrometer with tracking capabilities was designed especially for the special needs of the Cologne center for accelerator mass spectrometry (CologneAMS). The beam detector assembly is designed to match the beam specifications of the 6 MV Tandetron AMS setup and its data acquisition system. It will have a reconfigurable structure, either as a fast TOF subsystem with a ca. 10 cm{sup 2} equivalent active area, or as a more complex BPM-TOF detector with beam tracking capabilities and a larger active area (16 cm{sup 2}). The purpose of this detector is to suppress background during spectrometry of heavy ions (U, Cm, Pu, Am etc.) and to suppress isobaric interferences such as {sup 36}S in {sup 36}Cl spectra.

  2. Physical properties of the TOF (time of flight) scintillation counters of DELPHI

    International Nuclear Information System (INIS)

    Benlloch, J.M.; Castillo, M.V.; Ferrer, A.; Fuster, J.; Higon, E.; Llopis, A.; Salt, J.; Sanchez, E.; Sanchis, E.; Silvestre, E.; Cuevas, J.

    1990-01-01

    In this paper we report the physical properties of the time of flight (TOF) scintillator counters used for the DELPHI Experiment at CERN. We discuss the different choices studied for the wrapping of the counters in order to obtain best efficiencies for light transmission. A very good agreement of the performances of the counters has been found with the results of an original Monte Carlo program. The main characteristics of the TOF counters of DELPHI are: an effective light attenuation length of 135 cm, effective light speed of 15.91 cm/ns, a time resolution of 1.2 ns, and an efficiency for detection of minimum ionizing particles of 99.9%. (orig.)

  3. Time-of-flight analysis of charge-exchange neutral particles from the TORTUR II plasma

    International Nuclear Information System (INIS)

    Brocken, H.J.B.M.

    1981-10-01

    A disc chopper for time-of-flight analysis of fast neutral particles was constructed for the determination of the ion energy spectrum at lower energies than can be obtained by conventional electro-magnetic analyzers. The method has been applied to the TORTUR II tokamak. The chopper and detection system are described and the measurements are presented. For the interpretation of the results of the measurements a data analysis procedure was developed. The influence of reflections of neutrals at the liner wall showed to be important in the calculations of the neutral density profile at the plasma edge. The neutral energy spectrum in the lower energy range is strongly pronounced by this effect

  4. Activity on improving performance of time-of-flight detector at CDF

    International Nuclear Information System (INIS)

    Menzione, A.; Cerri, C.; Vataga, E.; Prokoshin, F.; Tokar, S.

    2002-01-01

    The paper describes activity on improving the time resolution of the Time-of-Flight detector at CDF. The main goal of the detector is the identification of kaons and pions for b-quark (B-meson) flavour tagging. Construction of the detector has been described as well as proposals on detector design changes to improve its time resolution. Monte Carlo simulation of the detector response to MIP was performed. The results of the simulation showed that the proposed modifications (at least with currently available materials) bring modest or no improvement of the detector time resolution. An automated set-up was assembled to test and check out the changes in the electronic readout system of the detector. Sophisticated software has been developed for this set-up to provide control of the system as well as processing and presentation of data from the detector. This software can perform various tests using different implementations of the hardware set-up

  5. Design of combined magnetic field system for magnetic-bottle time-of-flight spectrometer

    International Nuclear Information System (INIS)

    Wang Chao; Tian Jinshou; Zhang Meizhi; Kang Yifan

    2011-01-01

    Based on the primary requirement for the magnetic field system in magnetic-bottle time-of-flight spectrometer, an appropriate combined inhomogeneous magnetic field system is designed. The inhomogeneous higher magnetic field part, with the highest field of 1.2 T, is produced by the combination of a permanent magnet and a pole piece with optimized shape. The magnet,known as NdFeB magnet,is one of rare earth permanent magnets in N52. The guiding uniform magnetic field of 1.0 x 10 -3 T is provided by solenoid, with length of 3 m and radius of 3 cm. The pitch between the pole piece and the near end of used solenoid is determined to be 5 cm, which can satisfy the actual engineering needs. (authors)

  6. Radiofrequency glow discharge time of flight mass spectrometry: pulsed vs. continuous mode

    International Nuclear Information System (INIS)

    Lobo, L.; Pereiro, R.; Sanz-Medel, A.; Bordel, N.; Tempez, A.; Chapon, P.; Hohl, M.; Michler, J.

    2009-01-01

    Full text: Glow discharge (GD) is a well established tool for the direct analysis of solids. The application field of the original direct current GD, restricted to conductive samples, has been extended by radiofrequency powered GDs that can be applied for conductive and non-conductive samples. Moreover, the introduction of pulsed GD has opened the possibility of applying higher instantaneous powers that can improve the atomization-ionization processes and therefore the sensitivity. Furthermore, pulsed-GD may enable temporal separation of discharge gas species from the sample ions. In this work the analytical performances of radiofrequency and pulsed radiofrequency glow discharges are evaluated by using a time of flight mass analyzer (TOFMS). (author)

  7. A novel ion cooling trap for multi-reflection time-of-flight mass spectrograph

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Y., E-mail: yito@riken.jp [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Schury, P. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); New Mexico State University, Department Chemistry and Biochemistry, Las Cruces, NM 88003 (United States); Wada, M.; Naimi, S. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Smorra, C. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Sonoda, T. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Mita, H. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Takamine, A. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Aoyama Gakuin University, 4-4-25 Shibuya, Shibuya-ku, Tokyo 150-8366 (Japan); Okada, K. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan); Ozawa, A. [University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Wollnik, H. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); New Mexico State University, Department Chemistry and Biochemistry, Las Cruces, NM 88003 (United States)

    2013-12-15

    Highlights: • Fast cooling time: 2 ms. • High efficiency: ≈27% for {sup 23}Na{sup +} and ≈5.1% for {sup 7}Li{sup +}. • 100% Duty cycle with double trap system. -- Abstract: A radiofrequency quadrupole ion trap system for use with a multi-reflection time-of-flight mass spectrograph (MRTOF) for short-lived nuclei has been developed. The trap system consists of two different parts, an asymmetric taper trap and a flat trap. The ions are cooled to a sufficient small bunch for precise mass measurement with MRTOF in only 2 ms cooling time in the flat trap, then orthogonally ejected to the MRTOF for mass analysis. A trapping efficiency of ≈27% for {sup 23}Na{sup +} and ≈5.1% for {sup 7}Li{sup +} has been achieved.

  8. Time-of-flight mass spectrometer using an imaging detector and a rotating electric field

    International Nuclear Information System (INIS)

    Katayama, Atsushi; Kameo, Yutaka; Nakashima, Mikio

    2008-01-01

    A new technique for minor isotope analysis that uses a rotating electric field and an imaging detector is described. The rotating electric field is generated by six cylindrically arranged plane electrodes with multi-phase sinusoidal wave voltage. When ion packets that are discriminated by time-of-flight enter the rotating electric field, they are circularly deflected, rendering a spiral image on the fluorescent screen of the detector. This spiral image represents m/z values of ions as the position and abundance of ions as brightness. For minor isotopes analyses, the micro channel plate detector under gate control operation is used to eliminate the influence of high intensity of major isotopes. (author)

  9. Optical Time-of-Flight and Absorbance Imaging of Biologic Media

    Science.gov (United States)

    Benaron, David A.; Stevenson, David K.

    1993-03-01

    Imaging the interior of living bodies with light may assist in the diagnosis and treatment of a number of clinical problems, which include the early detection of tumors and hypoxic cerebral injury. An existing picosecond time-of-flight and absorbance (TOFA) optical system has been used to image a model biologic system and a rat. Model measurements confirmed TOFA principles in systems with a high degree of photon scattering; rat images, which were constructed from the variable time delays experienced by a fixed fraction of early-arriving transmitted photons, revealed identifiable internal structure. A combination of light-based quantitative measurement and TOFA localization may have applications in continuous, noninvasive monitoring for structural imaging and spatial chemometric analysis in humans.

  10. Time-of-Flight Measurements as a Possible Method to Observe Anyonic Statistics

    Science.gov (United States)

    Umucalılar, R. O.; Macaluso, E.; Comparin, T.; Carusotto, I.

    2018-06-01

    We propose a standard time-of-flight experiment as a method for observing the anyonic statistics of quasiholes in a fractional quantum Hall state of ultracold atoms. The quasihole states can be stably prepared by pinning the quasiholes with localized potentials and a measurement of the mean square radius of the freely expanding cloud, which is related to the average total angular momentum of the initial state, offers direct signatures of the statistical phase. Our proposed method is validated by Monte Carlo calculations for ν =1 /2 and 1 /3 fractional quantum Hall liquids containing a realistic number of particles. Extensions to quantum Hall liquids of light and to non-Abelian anyons are briefly discussed.

  11. High resolution time-of-flight measurements in small and large scintillation counters

    International Nuclear Information System (INIS)

    D'Agostini, G.; Marini, G.; Martellotti, G.; Massa, F.; Rambaldi, A.; Sciubba, A.

    1981-01-01

    In a test run, the experimental time-of-flight resolution was measured for several different scintillation counters of small (10 x 5 cm 2 ) and large (100 x 15 cm 2 and 75 x 25 cm 2 ) area. The design characteristics were decided on the basis of theoretical Monte Carlo calculations. We report results using twisted, fish-tail, and rectangular light- guides and different types of scintillator (NE 114 and PILOT U). Time resolution up to approx. equal to 130-150 ps fwhm for the small counters and up to approx. equal to 280-300 ps fwhm for the large counters were obtained. The spatial resolution from time measurements in the large counters is also reported. The results of Monte Carlo calculations on the type of scintillator, the shape and dimensions of the light-guides, and the nature of the external wrapping surfaces - to be used in order to optimize the time resolution - are also summarized. (orig.)

  12. Joint Temperature-Lasing Mode Compensation for Time-of-Flight LiDAR Sensors

    Directory of Open Access Journals (Sweden)

    Anas Alhashimi

    2015-12-01

    Full Text Available We propose an expectation maximization (EM strategy for improving the precision of time of flight (ToF light detection and ranging (LiDAR scanners. The novel algorithm statistically accounts not only for the bias induced by temperature changes in the laser diode, but also for the multi-modality of the measurement noises that is induced by mode-hopping effects. Instrumental to the proposed EM algorithm, we also describe a general thermal dynamics model that can be learned either from just input-output data or from a combination of simple temperature experiments and information from the laser’s datasheet. We test the strategy on a SICK LMS 200 device and improve its average absolute error by a factor of three.

  13. The multigap RPC detector and the ALICE time-of-flight

    CERN Document Server

    Zichichi, A

    2003-01-01

    One of the new detectors invented within the LAA project is the Multigap Resistive Plate Chamber (MRPC). The MRPC has been selected as the Time-of-Flight detector of choice for the ALICE experiment. The R and D program to optimise the MRPC for this application has now been completed, resulting in a device with 10 gas gaps of 250 mu m in width; a summary is given in this paper. Concerning the front-end electronics, there is an on-going development of an ASIC using 0.25 micron CMOS; the excellent performance of the ASIC is evident from the initial tests; some results will be shown here. Finally the timing properties of this detector open up other applications such as for Positron Electron Tomography. (author)

  14. A method for calibration and test of the time-of-flight detectors for DELPHI

    International Nuclear Information System (INIS)

    Benlloch, J.M.; Castillo, M.V.; Ferrer, A.; Fuster, J.; Higon, E.; Lozano, J.; Salt, J.; Sanchez, E.; Sanchis, E.; Cuevas, J.

    1990-01-01

    We describe a method for calibration and test of large-area TOF counters using cosmic radiation. We applied the method to the time-of-flight system of the DELPHI detector at the LEP e + e - storage ring, made of scintillation (NE110) counters (20x350 cm 2 ). The photomultipliers used (EMI 9902KB) reach an average gain of 5x10 8 at 1700 V and the time resolution achieved is 1.2 ns. Using this method we measured the counter efficiencies as a function of the position; we obtained 135 cm for the effective attenuation length and 40 photoelectrons for a minimum-ionizing particle crossing the center of the counter. (orig.)

  15. Efficient and Fast Implementation of Embedded Time-of-Flight Ranging System Based on FPGAs

    DEFF Research Database (Denmark)

    Zhou, Weiguo; Lyu, Congyi; Jiang, Xin

    2017-01-01

    Time-of-flight cameras perceive depth information about the surrounding environment with an amplitude-modulated near-infrared light source. The distance between the sensor and objects is calculated through measuring the time the light needs to travel. To be used in fast and embedded applications......, such as 3-D reconstruction, visual SLAM, human-robot interactions, and object detection, the 3-D imaging must be performed at high frame rates and accuracy. Thus, this paper presents a real-time field programmable gate arrays platform that calculates the phase shift and then the distance. Experimental...... results shown that the platform can acquire ranging images at the maximum frame rate of 131fps with a fine measurement precision (appropriately 5.1mm range error at 1.2m distance with the proper integration time). Low resource utilization and power consumption of the proposed system make it very suitable...

  16. Neutron scattering. Experiment manuals

    International Nuclear Information System (INIS)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner

    2012-01-01

    The following topics are dealt with: The thermal triple-axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, the neutron polarization analyzer DNS, the neutron spin-echo spectrometer J-NSE, the small-angle neutron diffractometers KWS-1/-2, the very-small-angle neutron diffractometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  17. First flux measurement in a SINQ supermirror neutron guide

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, S.; Schlumpf, N.; Bauer, G. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    On Dec. 3, 1996, the Swiss spallation neutron source SINQ was taken into operation and produced its first neutrons successfully. The neutron spectrum within one of the supermirror guides was estimated by a chopper Time-of-Flight method. The result shows a 30% higher neutron intensity at the flux maximum than expected from previous Monte-Carlo simulations. (author) 1 fig., 4 refs.

  18. Precision measurements with the multi-reflection time-of-flight mass spectrometer of ISOLTRAP at ISOLDE/CERN

    Energy Technology Data Exchange (ETDEWEB)

    Atanasov, Dinko; Ascher, Pauline; Borgmann, Christopher; Boehm, Christine; Eliseev, Sergey; Eronen, Tommi; George, Sebastian; Kisler, Dmitry; Naimi, Sarah [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Beck, Dietrich; Herfurth, Frank; Litvinov, Yuri; Minaya Ramirez, Enrique; Neidherr, Dennis [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Planckstr. 1, 64291 Darmstadt (Germany); Breitenfeldt, Martin [Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200d - bus 2418, 3001 Heverlee (Belgium); Cakirli, Burcu [University of Istanbul, Department of Physics, 34134 Istanbul (Turkey); Cocolios, Thomas Elias [University of Manchester, Manchester (United Kingdom); Herlert, Alexander Josef [FAIR GmbH, Planckstr. 1, D-64291 Darmstadt (Germany); Kowalska, Magdalena [CERN, Geneva 23, 1211 Geneva (Switzerland); Kreim, Susanne [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); CERN, Geneva 23, 1211 Geneva (Switzerland); Lunney, David; Manea, Vladimir [CSNSM-IN2P3-CNRS, 91405 Orsay Campus, Bat. 104, 108 (France); Rosenbusch, Marco; Schweikhard, Lutz; Wienholtz, Frank; Wolf, Robert [Ernst-Moritz-Arndt-Universitaet, Institut fuer Physik, Felix-Hausdorff-Str. 6, 17487 Greifswald (Germany); Stanja, Juliane; Zuber, Kai [Institut fuer Kern- und Teilchenphysik, Technische Universitaet Dresden, Zellescher Weg 19, 01069 Dresden (Germany)

    2014-07-01

    The masses of exotic nuclides are among the most important input parameters for modern nuclear theory and astrophysical models. At the high-precision Penning-trap mass spectrometer ISOLTRAP at ISOLDE/CERN, a multi-reflection time-of-flight mass spectrometer (MR-ToF-MS) in combination with a Bradbury-Nielsen gate (BNG) can be used to achieve high-resolution isobar purification with mass-resolving powers of 105 in a few tens of milliseconds. Furthermore, the MR-ToF device can be used as a spectrometer to determine the masses of nuclides with very low yields and short half-lives, where a Penning-trap mass measurement becomes impractical due to the lower transport efficiency and decay losses during the purification and measurement cycles. Recent cross-check experiments show that the MR-ToF MS allows mass measurements with uncertainties in the sub-ppm range. In a first application the mass measurements of the nuclides 53,54Ca was performed, delivered with production rates as low as 10/s and half-lives of only 90(6) ms. The nuclides serve as important benchmarks for testing modern chiral effective theory with realistic 3-body forces. The contribution presents the on-line mass spectrometer ISOLTRAP focusing on the new applications, which became possible after the implementation of the MR-ToF MS into the current setup. In particular, the mass measurements of the neutron-rich calcium isotopes up to A=54 are discussed. In addition, measurements of the isotonic potassium isotopes are reported.

  19. Investigation of a Multi-Anode Microchannel Plate PMT for Time-of-Flight PET

    Science.gov (United States)

    Choong, Woon-Seng

    2010-10-01

    We report on an investigation of a mulit-anode microchannel plate PMT for time-of-flight PET detector modules. The primary advantages of an MCP lie in its excellent timing properties (fast rise time and low transit time spread), compact size, and reasonably large active area, thus making it a good candidate for TOF applications. In addition, the anode can be segmented into an array of collection electrodes with fine pitch to attain good position sensitivity. In this paper, we investigate using the Photonis Planacon MCP-PMT with a pore size of 10 μm to construct a PET detector module, specifically for time-of-flight applications. We measure the single electron response by exciting the Planacon with pulsed laser diode. We also measure the performance of the Planacon as a PET detector by coupling a 4 mm×4 mm×10 mm LSO crystal to individual pixel to study its gain uniformity, energy resolution, and timing resolution. The rise time of the Planacon is 440 ps with pulse duration of about 1 ns. A transit time spread of 120 ps FWHM is achieved. The gain is fairly uniform across the central region of the Planacon, but drops off by as much as a factor of 2.5 around the edges. The energy resolution is fairly uniform across the Planacon with an average value of 18.6 ± 0.7% FWHM. While the average timing resolution of 252 ± 7 ps FWHM is achieved in the central region of the Planacon, it degrades to 280 ± 9 ps FWHM for edge pixels and 316 ± 15 ps FWHM for corner pixels. We compare the results with measurements performed with a fast timing conventional PMT (Hamamatsu R-9800). We find that the R9800, which has significantly higher PDE, has a better timing resolution than the Planacon. Furthermore, we perform detector simulations to calculate the improvement that can be achieved with a higher PDE Planacon. The calculation shows that the Planacon can achieve significantly better timing resolution if it can attain the same PDE as the R-9800, while only a 30% improvement is

  20. Switching Transient Generation in Surface Interrogation Scanning Electrochemical Microscopy and Time-of-Flight Techniques.

    Science.gov (United States)

    Ahn, Hyun S; Bard, Allen J

    2015-12-15

    In surface interrogation scanning electrochemical microscopy (SI-SECM), fine and accurate control of the delay time between substrate generation and tip interrogation (tdelay) is crucial because tdelay defines the decay time of the reactive intermediate. In previous applications of the SI-SECM, the resolution in the control of tdelay has been limited to several hundreds of milliseconds due to the slow switching of the bipotentiostat. In this work, we have improved the time resolution of tdelay control up to ca. 1 μs, enhancing the SI-SECM to be competitive in the time domain with the decay of many reactive intermediates. The rapid switching SI-SECM has been implemented in a substrate generation-tip collection time-of-flight (SG-TC TOF) experiment of a solution redox mediator, and the results obtained from the experiment exhibited good agreement with that obtained from digital simulation. The reaction rate constant of surface Co(IV) on oxygen-evolving catalyst film, which was inaccessible thus far due to the lack of tdelay control, has been measured by the rapid switching SI-SECM.

  1. Time-of-flight measurement in the DZero Central Fiber Tracker

    International Nuclear Information System (INIS)

    Juan Estrada

    2003-01-01

    We continue evaluation of the new electronics developed for the Central Fiber Tracker and Preshower detectors. With the custom TriP chip and MCM II we have measured the position of the hits along the fiber by comparing the time of arrival of the photons at the VLPC with the expected timing relative to the beam. The measured rms resolution at the center of the fibers is 46cm for hits with more than 8 photo-electrons and is dominated by the statistics of photon arrival time. The corresponding resolution near the ends of the fibers (where more photoelectrons are collected) is calculated to be of order 27cm. With a second submission of the TriP chip to add the time-of-flight measuring capability we will effectively double the number of channels in the central fiber tracker. This capability will increase the maximum luminosity at which D0 can do tracking from ∼ 100 · 10 30 cm -2 s -1 to ∼ 200 · 10 30 cm -2 s -1 (at a bench mark tracking specification). The cost of replacing the electronics is of order $500K and the necessary lead time is 1.5 years

  2. Design of the TORCH detector: A Cherenkov based Time-of-Flight system for particle identification

    CERN Document Server

    AUTHOR|(CDS)2078663; Rademacker, Jonas

    The LHCb detector at the LHC collider has been very successfully operated over the past years, providing new and profound insights into the Standard Model, in particular through study of $b$-hadrons to achieve a better understanding of CP violation. One of the key components of LHCb is its particle identification system, comprised of two RICH detectors, which allow for high precision separation of particle species over a large momentum range. In order to retain and improve the performance of the particle identification system in light of the LHCb upgrade, the TORCH detector has been proposed to supplement the RICH system at low momentum (2-10 GeV/c). The TORCH detector provides (charged) particle identification through precision timing of particles passing through it. Assuming a known momentum from the tracking, it is possible to derive the species of a particle from the time of flight from its primary vertex. This measurement is achieved by timing and combining photons generated in a solid radiator. The geom...

  3. ASIC for time-of-flight measurements with picosecond timing resolution

    Energy Technology Data Exchange (ETDEWEB)

    Stankova, Vera; Shen, Wei; Harion, Tobias [Kirchhoff-Institute for Physics, Heidelberg Univ. (Germany)

    2015-07-01

    The Positron Emission Tomography (PET) images are especially affected by a high level of noise. This noise affects the potential to detect and discriminate the tumor in relation to the background. Including Time-of-Flight information, with picosecond time resolution, within the conventional PET scanners will improve the signal-to-noise ratio (SNR) and in sequence the quality of the medical images. A mix-mode ASIC (STIC3) has been developed for high precision timing measurements with Silicon Photomultipliers (SiPM). The STiC3 is 64-channel chip, with fully differential analog front-end for crosstalk and electronic noise immunity. It integrates Time to Digital Converters (TDC) with time binning of 50.2 ps for time and energy measurements. Measurements of the of the analog front-end show a time jitter less than 20 ps and jitter of the TDC together with the digital part is around 37 ps. Further the timing of a channel has been tested by injecting a pulse into two channels and measuring the time difference of the recorded timestamps. A Coincidence Time Resolution (CTR) of 215 ps FWHM has been obtained with 3.1 x 3.1 x 15 mm{sup 2} LYSO:Ce scintillator crystals and Hamamatsu SiPM matric (S12643-050CN(x)). Characterization measurements with the chip and its performances are presented.

  4. A fast preamplifier concept for SiPM-based time-of-flight PET detectors

    Energy Technology Data Exchange (ETDEWEB)

    Huizenga, J., E-mail: j.huizenga@tudelft.nl [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands); Seifert, S. [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands); Schreuder, F. [Kernfysisch Versneller Instituut, University of Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands); Dam, H.T. van [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands); Dendooven, P.; Loehner, H.; Vinke, R. [Kernfysisch Versneller Instituut, University of Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands); Schaart, D.R. [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands)

    2012-12-11

    Silicon photomultipliers (SiPMs) offer high gain and fast response to light, making them interesting for fast timing applications such as time-of-flight (TOF) PET. To fully exploit the potential of these photosensors, dedicated preamplifiers that do not deteriorate the rise time and signal-to-noise ratio are crucial. Challenges include the high sensor capacitance, typically >300 pF for a 3 mm Multiplication-Sign 3 mm SiPM sensor, as well as oscillation issues. Here we present a preamplifier concept based on low noise, high speed transistors, designed for optimum timing performance. The input stage consists of a transimpedance common-base amplifier with a very low input impedance even at high frequencies, which assures a good linearity and avoids that the high detector capacitance affects the amplifier bandwidth. The amplifier has a fast timing output as well as a 'slow' energy output optimized for determining the total charge content of the pulse. The rise time of the amplifier is about 300 ps. The measured coincidence resolving time (CRT) for 511 keV photon pairs using the amplifiers in combination with 3 mm Multiplication-Sign 3 mm SiPMs (Hamamatsu MPPC-S10362-33-050C) coupled to 3 mm Multiplication-Sign 3 mm Multiplication-Sign 5 mm LaBr{sub 3}:Ce and LYSO:Ce crystals equals 95 ps FWHM and 138 ps FWHM, respectively.

  5. A fast preamplifier concept for SiPM-based time-of-flight PET detectors

    International Nuclear Information System (INIS)

    Huizenga, J.; Seifert, S.; Schreuder, F.; Dam, H.T. van; Dendooven, P.; Löhner, H.; Vinke, R.; Schaart, D.R.

    2012-01-01

    Silicon photomultipliers (SiPMs) offer high gain and fast response to light, making them interesting for fast timing applications such as time-of-flight (TOF) PET. To fully exploit the potential of these photosensors, dedicated preamplifiers that do not deteriorate the rise time and signal-to-noise ratio are crucial. Challenges include the high sensor capacitance, typically >300 pF for a 3 mm×3 mm SiPM sensor, as well as oscillation issues. Here we present a preamplifier concept based on low noise, high speed transistors, designed for optimum timing performance. The input stage consists of a transimpedance common-base amplifier with a very low input impedance even at high frequencies, which assures a good linearity and avoids that the high detector capacitance affects the amplifier bandwidth. The amplifier has a fast timing output as well as a ‘slow’ energy output optimized for determining the total charge content of the pulse. The rise time of the amplifier is about 300 ps. The measured coincidence resolving time (CRT) for 511 keV photon pairs using the amplifiers in combination with 3 mm×3 mm SiPMs (Hamamatsu MPPC-S10362-33-050C) coupled to 3 mm×3 mm×5 mm LaBr 3 :Ce and LYSO:Ce crystals equals 95 ps FWHM and 138 ps FWHM, respectively.

  6. Pulsed neutron sources for epithermal neutrons

    International Nuclear Information System (INIS)

    Windsor, C.G.

    1978-01-01

    It is shown how accelerator based neutron sources, giving a fast neutron pulse of short duration compared to the neutron moderation time, promise to open up a new field of epithermal neutron scattering. The three principal methods of fast neutron production: electrons, protons and fission boosters will be compared. Pulsed reactors are less suitable for epithermal neutrons and will only be briefly mentioned. The design principle of the target producing fast neutrons, the moderator and reflector to slow them down to epithermal energies, and the cell with its beam tubes and shielding will all be described with examples taken from the new Harwell electron linac to be commissioned in 1978. A general comparison of pulsed neutron performance with reactors is fraught with difficulties but has been attempted. Calculation of the new pulsed source fluxes and pulse widths is now being performed but we have taken the practical course of basing all comparisons on extrapolations from measurements on the old 1958 Harwell electron linac. Comparisons for time-of-flight and crystal monochromator experiments show reactors to be at their best at long wavelengths, at coarse resolution, and for experiments needing a specific incident wavelength. Even existing pulsed sources are shown to compete with the high flux reactors in experiments where the hot neutron flux and the time-of-flight methods can be best exploited. The sources under construction can open a new field of inelastic neutron scattering based on energy transfer up to an electron volt and beyond

  7. Design and relevant sample calculations for a neutral particle energy diagnostic based on time of flight

    Energy Technology Data Exchange (ETDEWEB)

    Cecconello, M

    1999-05-01

    Extrap T2 will be equipped with a neutral particles energy diagnostic based on time of flight technique. In this report, the expected neutral fluxes for Extrap T2 are estimated and discussed in order to determine the feasibility and the limits of such diagnostic. These estimates are based on a 1D model of the plasma. The input parameters of such model are the density and temperature radial profiles of electrons and ions and the density of neutrals at the edge and in the centre of the plasma. The atomic processes included in the model are the charge-exchange and the electron-impact ionization processes. The results indicate that the plasma attenuation length varies from a/5 to a, a being the minor radius. Differential neutral fluxes, as well as the estimated power losses due to CX processes (2 % of the input power), are in agreement with experimental results obtained in similar devices. The expected impurity influxes vary from 10{sup 14} to 10{sup 11} cm{sup -2}s{sup -1}. The neutral particles detection and acquisition systems are discussed. The maximum detectable energy varies from 1 to 3 keV depending on the flight distances d. The time resolution is 0.5 ms. Output signals from the waveform recorder are foreseen in the range 0-200 mV. An 8-bit waveform recorder having 2 MHz sampling frequency and 100K sample of memory capacity is the minimum requirement for the acquisition system 20 refs, 19 figs.

  8. Neutron resonance parameters of CM isotopes

    International Nuclear Information System (INIS)

    Belanova, T.S.; Kolesov, A.G.; Poruchikov, V.A.

    1977-01-01

    The total neutron cross sections of isotopes 244, 245, 246, 248 Curium have been measured on reactor CM-2 using the time-of-flight method. Single-level Breit-Wigner resonance parameters: energy E 0 , neutron width 2g GITAn, total width GITA, total neutron cross section in resonance sigma 0 have been obtained by the shape and area methods

  9. On the timing of foraging flights by oystercatchers, haematopus ostralegus, on tidal mudflats

    Science.gov (United States)

    Daan, Serge; Koene, Paul

    The tidal movements of flocks of oystercatchers foraging on mudflats at low tide and roosting inland behind a dike at high tide were studied and the effects of day-to-day variations in the time of mudflat exposure by ebb analysed. High mean water levels and short low tides led to reduced intake during low water due to increased bird densities in addition to temporal constraints (Fig. 4). Increased feeding around the roost apparently compensated for some of the reduced intake (Figs 6 ad 7) although accurate intake measurements could be made for foraging on the tidal flats only. It is argued that optimal timing of foraging flights to coincide with exposure of the mussel banks would contribute to exploitation of this tidal food source. The median departure time from the roosts relative to the time of mudflat exposure was early on days when the tide went out late and late when the tide was early (Figs 8 and 9). Daily variations in departure time were predicted by the daily variations in tabulated high water times, but not by variations in mudflat exposure or coverage (Fig. 10). The conclusion is drawn that the birds employ a timing mechanism not directly associated with the tidal water movements. In some pilot experiments in caged oystercatchers, feeding schedules elicitated feeling attempts in anticipation of expected food. The anticipatory patterns were different for fixed and tidally shifting daily food schedules, and moreover differed between the two feeding times per day (Figs 12 and 13). Five possible mechanisms for tidal anticipation are discussed, making use either of unknown exogenous cues, or of—likewise unknown—endogenous timers of hourglass type of rhythmic with circatidal, circalunadian or circadian period. Experimental tests for these possibilities are outlined.

  10. Electrostatic mirror of time-of-flight focusing of charged particles and its application to mass spectrometry

    International Nuclear Information System (INIS)

    Berger, C.

    1985-01-01

    This invention is more particularly aimed at the electrostatic devices used in time-of-flight mass spectrometers. To obtain a better resolution and a maximum transmission, the mirror is characterized by three annular electrodes with same radius R: - having at least an inner conductor surface related to an electric source, - delimiting by their facing ends cross-sections, - spaced successively with coaxial arrangement, - having an axial length for the center electrode equal to 0,9 R and for the end electrodes a length enough to give to them a behaviour equivalent to a infinite length tube cylinder. Ion beams are reflected by the mirror which in the same time realizes the time-of-flight unicity for ion. TOF unicity means that time of flight will be the same for equal mass ions [fr

  11. High resolution neutron spectroscopy for helium isotopes

    International Nuclear Information System (INIS)

    Abdel-Wahab, M.S.; Klages, H.O.; Schmalz, G.; Haesner, B.H.; Kecskemeti, J.; Schwarz, P.; Wilczynski, J.

    1992-01-01

    A high resolution fast neutron time-of-flight spectrometer is described, neutron time-of-flight spectra are taken using a specially designed TDC in connection to an on-line computer. The high time-of-flight resolution of 5 ps/m enabled the study of the total cross section of 4 He for neutrons near the 3/2 + resonance in the 5 He nucleus. The resonance parameters were determined by a single level Breit-Winger fit to the data. (orig.)

  12. Application of a digital data acquisition system for time of flight Positron annihilation-induced Auger Electron Spectroscopy

    Science.gov (United States)

    Gladen, R. W.; Chirayath, V. A.; McDonald, A. D.; Fairchild, A. J.; Chrysler, M. D.; Imam, S. K.; Koymen, A. R.; Weiss, A. H.

    We describe herein a digital data acquisition system for a time-of-flight Positron annihilation-induced Auger Electron Spectrometer. This data acquisition system consists of a high-speed digitizer collecting signals induced by Auger electrons and annihilation gammas in a multi-channel plate electron detector and a BaF2 gamma detector, respectively. The time intervals between these two signals is used to determine the times of flight of the Auger electrons, which are analyzed by algorithms based on traditional nuclear electronics methods. Ultimately, this digital data acquisition system will be expanded to incorporate the first coincidence measurements of Auger electron and annihilation gamma energies.

  13. SiPM photosensors and fast timing readout for the Barrel Time-of-Flight detector in bar PANDA

    Science.gov (United States)

    Suzuki, K.

    2018-03-01

    The Barrel Time-of-Flight detector system will be installed in the upcoming bar PANDA experiment at FAIR in Germany. The detector has a barrel shape of phi=0.5 m and 1.8 m long, covering about 5 m2, which corresponds to the laboratory polar angle coverage of 22oPANDA Barrel Time-of-Flight detector are presented. The test shows that the current design fulfils satisfactorily the required timing performance (σt~ 56 ps) and the timing performance depends little on the hit position on the surface.

  14. Position sensitive detection coupled to high-resolution time-of-flight mass spectrometry: Imaging for molecular beam deflection experiments

    International Nuclear Information System (INIS)

    Abd El Rahim, M.; Antoine, R.; Arnaud, L.; Barbaire, M.; Broyer, M.; Clavier, Ch.; Compagnon, I.; Dugourd, Ph.; Maurelli, J.; Rayane, D.

    2004-01-01

    We have developed and tested a high-resolution time-of-flight mass spectrometer coupled to a position sensitive detector for molecular beam deflection experiments. The major achievement of this new spectrometer is to provide a three-dimensional imaging (X and Y positions and time-of-flight) of the ion packet on the detector, with a high acquisition rate and a high resolution on both the mass and the position. The calibration of the experimental setup and its application to molecular beam deflection experiments are discussed

  15. Characterization studies of Silicon Photomultipliers and crystals matrices for a novel time of flight PET detector

    CERN Document Server

    Auffray, Etiennette; Cortinovis, Daniele; Doroud, Katayoun; Garutti, Erika; Lecoq, Paul; Liu, Zheng; Martinez, Rosana; Paganoni, Marco; Pizzichemi, Marco; Silenzi, Alessandro; Xu, Chen; Zvolský, Milan

    2015-01-01

    This paper describes the characterization of crystal matrices and silicon photomultiplier arrays for a novel Positron Emission Tomography (PET) detector, namely the external plate of the EndoTOFPET-US system. The EndoTOFPET-US collaboration aims to integrate Time-Of-Flight PET with ultrasound endoscopy in a novel multimodal device, capable to support the development of new biomarkers for prostate and pancreatic tumors. The detector consists in two parts: a PET head mounted on an ultrasound probe and an external PET plate. The challenging goal of 1 mm spatial resolution for the PET image requires a detector with small crystal size, and therefore high channel density: 4096 LYSO crystals individually readout by Silicon Photomultipliers (SiPM) make up the external plate. The quality and properties of these components must be assessed before the assembly. The dark count rate, gain, breakdown voltage and correlated noise of the SiPMs are measured, while the LYSO crystals are evaluated in terms of light yield and en...

  16. Monitoring of railway embankment settlement with fiber-optic pulsed time-of-flight radar.

    Science.gov (United States)

    Kilpelä, Ari; Lyöri, Veijo; Duan, Guoyong

    2012-12-01

    This paper deals with a fiber-optic pulsed time-of-flight (PTOF) laser radar used for monitoring the settlement of a railway embankment. The operating principle is based on evaluating the changes in the lengths of the fiber-optic cables embedded in the embankment by measuring the time separation of the optical pulses reflected from both ends of the sensor fiber. The advantage of this method is that it integrates the elongation of the whole sensor, and many sensor fibers can be connected in series. In a field test, seven polyurethane-coated optical cables were installed in a railway embankment and used as 20-m long sensors. The optical timing pulses were created using specially polished optical connectors. The measured precision was 0.28 ps, which corresponds 1.8 μstrain elongation using a 20 m long sensor fiber, using an averaged value of 10,000 pulses for a single measurement value. The averaged elongation value of all sensors was used for cancelling out the effect of temperature variation on the elongation value of each individual sensor. The functionality of the method was tested by digging away a 7.5 m long and approximately 18 mm high section of sand below one sensor. It was measured as a +3 mm change in the length of the sensor fiber, which matched well with the theoretically calculated elongation value, 2.9 mm. The sensor type proved to be strong but flexible enough for this type of use.

  17. Time of flight spectra of electrons emitted from graphite after positron annihilation

    International Nuclear Information System (INIS)

    Gladen, R W; Chirayath, V A; Chrysler, M D; Mcdonald, A D; Fairchild, A J; Shastry, K; Koymen, A R; Weiss, A H

    2017-01-01

    Low energy (∼2 eV) positrons were deposited onto the surface of highly oriented pyrolytic graphite (HOPG) using a positron beam equipped with a time of flight (TOF) spectrometer. The energy of the electrons emitted as a result of various secondary processes due to positron annihilation was measured using the University of Texas at Arlington’s (UTA) TOF spectrometer. The positron annihilation-induced electron spectra show the presence of a carbon KLL Auger peak at ∼263 eV. The use of a very low energy beam allowed us to observe a new feature not previously seen: a broad peak which reached to a maximum intensity at ∼4 eV and extended up to a maximum energy of ∼15 eV. The low energy nature of the peak was confirmed by the finding that the peak was eliminated when a tube in front of the sample was biased at -15 V. The determination that the electrons in the peak are leaving the surface with energies up to 7 times the incoming positron energy indicates that the electrons under the broad peak were emitted as a result of a positron annihilation related process. (paper)

  18. Time-of-flight positron emission tomography (T.O.F. P.E.T.)

    International Nuclear Information System (INIS)

    Allemand, R.

    1984-10-01

    A new important step has been made in the performances of the time-of-flight positron imaging for the two last years. It has been proved that a high spatial resolution can be obtained with the T.O.F. technique. It has also been shown that the overall sensitivity (taking into account the sensitivity gain and BaF2 detection characteristics) is quite close to the one of conventional methods. On the other hand, the basic advantages related to the high counting rate capability, the random coincidences rejection etc... of course remain. It is probably safe to assume that significant improvements can be expected if new technological efforts are invested. Unfortunately, P.E.T. is a complex and expensive tool which has been only used up to now in the research groups (about 50 centers in the world). The justification of new technical developments will be quite clear when this modality will be considered in the assessment of diseases and in clinical diagnostic applications

  19. A new time-of-flight instrument for quantitative surface analysis

    International Nuclear Information System (INIS)

    Veryovkin, Igor V.; Calaway, Wallis F.; Moore, Jerry F.; Pellin, Michael J.; Burnett, Donald S.

    2004-01-01

    A new generation of time-of-flight mass spectrometers that implement ion sputtering and laser desorption for probing solid samples and can operate in regimes of laser post-ionization secondary neutral mass spectrometry and secondary ion mass spectrometry is being developed at Argonne National Laboratory. These new instruments feature novel ion optical systems for efficient extraction of ions from large laser post-ionization volumes and for lossless transport of these ions to detectors. Another feature of this design is a new in-vacuum all-reflecting optical microscope with 0.5-μm resolution. Advanced ion and light optics and three ion sources, including a liquid metal ion gun (focusable to 50 nm) and a low energy ion gun, give rise to an instrument capable of quantitative analyses of samples for the most challenging applications, such as determining elemental concentrations in shallow implants at ultra-trace levels (for example, solar wind samples delivered by NASA Genesis mission) and analyzing individual sub-micrometer particles on a sample stage (such as, interstellar dust delivered by NASA Stardust mission). Construction of a prototype instrument has been completed and testing is underway. A more advanced instrument of similar design is under construction. The overall design of the new instrument and the innovations that make it unique are outlined. Results of the first tests to characterize its analytical capabilities are presented also

  20. Defocus Deblurring and Superresolution for Time-of-Flight Depth Cameras

    KAUST Repository

    Xiao, Lei

    2015-06-07

    Continuous-wave time-of-flight (ToF) cameras show great promise as low-cost depth image sensors in mobile applications. However, they also suffer from several challenges, including limited illumination intensity, which mandates the use of large numerical aperture lenses, and thus results in a shallow depth of field, making it difficult to capture scenes with large variations in depth. Another shortcoming is the limited spatial resolution of currently available ToF sensors. In this paper we analyze the image formation model for blurred ToF images. By directly working with raw sensor measurements but regularizing the recovered depth and amplitude images, we are able to simultaneously deblur and super-resolve the output of ToF cameras. Our method outperforms existing methods on both synthetic and real datasets. In the future our algorithm should extend easily to cameras that do not follow the cosine model of continuous-wave sensors, as well as to multi-frequency or multi-phase imaging employed in more recent ToF cameras.