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Sample records for time-of flight neutron

  1. Neutron time-of-flight spectroscopy

    International Nuclear Information System (INIS)

    Copley, J.R.D.; Udovic, T.J.

    1993-01-01

    The time-of-flight technique is employed in two of the instruments at the NIST Cold Neutron Research Facility (CNRF). A pulsed monochromatic beam strikes the sample, and the energies of scattered neutrons are determined from their times-of-flight to an array of detectors. The time-of-flight method may be used in a variety of types of experiments such as studies of vibrational and magnetic excitations, tunneling spectroscopy, and quasielastic scattering studies of diffusional behavior; several examples of experiments are discussed. The authors also present brief descriptions of the CNRF time-of-flight instruments, including their modi operandi and some of their more pertinent parameters and performance characteristics

  2. 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.

  3. 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)

  4. 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

  5. Time-of-flight neutron spectrometer for JT-60U

    International Nuclear Information System (INIS)

    Shibata, Y.; Iguchi, T.; Uritani, Akira; Kawarabayashi, Jun; Hoek, Magnus; Nishitani, T.; Morioka, A.

    2001-01-01

    We have developed a 2.45 MeV neutron Double Crystal Time-of-Flight (DC-TOF) spectrometer for Deuterium plasmas in JT-60U. The DC-TOF neutron spectrometer consists of two fast plastic scintillators (BC-408 made by Bicron, 50 cm 2 and 1800 cm 2 , thickness 2 cm), located on constant TOF spheres. The constant TOF spheres have a radius of 1 m which gives a neutron flight length of 1.64 m and a TOF of 92 ns for 2.45 MeV neutrons. The calculated spectrometer efficiency and resolution are 2.8x10 -2 cm 2 and 100 keV, respectively. The energy resolution corresponds to a time resolution of 2.0 ns. The spectrometer has been installed in the basement of JT-60U, 10 m away from the plasma center with vertical line-of-sight. Neutron energy spectra have been obtained when the neutron yield from the plasma is ∼10 15 neutrons/s. (author)

  6. 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.

  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. 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

  9. Engineering Applications of Time-of-Flight Neutron Diffraction

    Science.gov (United States)

    Clausen, Bjørn; Brown, Donald W.; Noyan, I. C.

    2012-01-01

    Time-of-flight neutron diffraction is widely used in characterizing the microstructure and mechanical response of heterogeneous systems. Microstructural characterization techniques include spatial or temporal mapping of the phases and determination of grain size, dislocation structure, and grain orientations (texture) within these phases. Mechanical response analysis utilizes the crystallographic selectivity of the diffraction process to measure the partitioning of strain within the system. The microstructural and mechanical response information is then used to develop more realistic constitutive models. In this article we review some examples of such measurements, based on our experiences at the Lujan Center of Los Alamos National Laboratory.

  10. Neutron Time-of-Flight Diffractometer HIPPO at LANSCE

    Science.gov (United States)

    Vogel, Sven; Williams, Darrick; Zhao, Yusheng; Bennett, Kristin; von Dreele, Bob; Wenk, Hans-Rudolf

    2004-03-01

    The High-Pressure Preferred Orientation (HIPPO) neutron diffractometer is the first third-generation neutron time-of-flight powder diffractometer to be constructed in the United States. It produces extremely high intensity by virtue of a short (9 m) initial flight path on a high intensity water moderator and 1380 3He detector tubes covering 4.5 m2 of detector area from 10' to 150' in scattering angles. HIPPO was designed and manufactured as a joint effort between LANSCE and University of California with the goals of attaining world-class science and making neutron powder diffractometry an accessible and available tool to the national user community. Over two decades of momentum transfer are available (0.1-30 A-1) to support studies of amorphous solids; magnetic diffraction; small crystalline samples; and samples subjected to extreme environments such as temperature, pressure, or magnetic fields. The exceptionally high data rates of HIPPO also make it useful for time-resolved studies. In addition to the standard ancillary equipment (100-position sample/texture changer, closed-cycle He refrigerator, furnace), HIPPO has unique high-pressure cells capable of achieving pressures of 30 GPA at ambient and high (2000 K) temperature with samples up to 100 mm3 in volume.

  11. A transistorized 1024-channel neutron time-of-flight analyser

    International Nuclear Information System (INIS)

    Giannelli, G.

    1962-01-01

    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 μs, 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 μs. 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) [fr

  12. 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.

  13. Data reduction for time-of-flight small-angle neutron scattering with virtual neutrons

    Science.gov (United States)

    Du, Rong; Tian, Haolai; Zuo, Taisen; Tang, Ming; Yan, Lili; Zhang, Junrong

    2017-09-01

    Small-angle neutron scattering (SANS) is an experimental technique to detect material structures in the nanometer to micrometer range. The solution of the structural model constructed from SANS strongly depends on the accuracy of the reduced data. The time-of-flight (TOF) SANS data are dependent on the wavelength of the pulsed neutron source. Therefore, data reduction must be handled very carefully to transform measured neutron events into neutron scattering intensity. In this study, reduction algorithms for TOF SANS data are developed and optimized using simulated data from a virtual neutron experiment. Each possible effect on the measured data is studied systematically, and suitable corrections are performed to obtain high-quality data. This work will facilitate scientific research and the instrument design at China Spallation Neutron Source.

  14. 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

  15. Time-of-flight neutron-correlation spectrometers and their electronics

    International Nuclear Information System (INIS)

    Tsitovich, A.P.

    1976-01-01

    The review is made of the data published on neutron-correlation time-of-flight spectrometers. The operating principle of a correlation neutron time-of-flight spectrometer implies that the neutron beam serving as an input signal is modulated by an inadvertent law, and time spectrum is found by the way of measuring the mutually correlating function of the input signal and the output signal of the neutron detector. The correlation method is grounded in brief, and the specific features of the neutron-beam choppers, pulse analyzers and time encoders used in the correlation spectrometers are given. Also considered are the main functions of the computers operating in line with the spectrometers. As compared with the ordinary time-of-flight spectrometers, the neutron-correlation ones are more effective, which explains their wide application in nuclear spectrometry

  16. Structural studies at high pressure using time-of-flight neutron powder diffraction

    International Nuclear Information System (INIS)

    Jorgensen, J.D.

    1989-07-01

    Time-of-flight neutron powder diffraction offers unique capabilities for structural studies at high pressure. Scientific applications have included studies of compression mechanisms, new high-pressure structures, and phase transitions. 11 refs., 1 fig

  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. Diffraction by the time-of-flight technique at pulsed neutron sources

    International Nuclear Information System (INIS)

    Jorgensen, J.D.

    1984-06-01

    The recent development of accelerator-based pulsed neutron sources as an alternative to reactor sources has caused a renewed interest in time-of-flight neutron diffraction techniques because the time-of-flight method can be optimally used at pulsed sources. Since neutrons have finite mass, and therefore travel at a velocity proportional to their wavelength, neutron diffraction can be done either by the conventional technique commonly used for X-rays, where a single wavelength is used, or by the time-of-flight technique, where all wavelengths are used. In a conventional diffraction experiment with monochromatic radiation, the Bragg equation d = lambda/(2 sin theta) is satisfied by varying the angle 2 theta at which the scattered radiation is detected. In a time-of-flight diffraction experiment, all wavelengths lambda are allowed to scatter from the sample and are determined by recording the times at which neutrons arrive at a detector in a fixed position. Neutron diffraction has been done by the time-of-flight technique for many years using mechanical neutron choppers at reactor sources, but found only limited application because the chopper instruments could not be properly optimized with respect to beam size, pulse width, and repetition rate. The new accelerator-based pulsed neutron sources produce neutrons in short, intense bursts, eliminating the need for mechanical choppers. The pulse width and repetition rate can be tailored to meet the requirements of a particular instrument. After only a few years of development, this has allowed time-of-flight diffraction instruments at moderately-sized pulsed neutron sources

  20. 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

  1. 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

  2. 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.

  3. 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

  4. 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.

  5. The multipurpose time-of-flight neutron reflectometer “Platypus” at Australia's OPAL reactor

    Science.gov (United States)

    James, M.; Nelson, A.; Holt, S. A.; Saerbeck, T.; Hamilton, W. A.; Klose, F.

    2011-03-01

    In this manuscript we describe the major components of the Platypus time-of-flight neutron reflectometer at the 20 MW OPAL reactor in Sydney, Australia. Platypus is a multipurpose spectrometer for the characterisation of solid thin films, materials adsorbed at the solid-liquid interface and free-liquid surfaces. It also has the capacity to study magnetic thin films using spin-polarised neutrons. Platypus utilises a white neutron beam ( λ=2-20 Å) that is pulsed using boron-coated disc chopper pairs; thus providing the capacity to tailor the wavelength resolution of the pulses to suit the system under investigation. Supermirror optical components are used to focus, deflect or spin-polarise the broad bandwidth neutron beams, and typical incident spectra are presented for each configuration. A series of neutron reflectivity datasets are presented, indicating the quality and flexibility of this spectrometer. Minimum reflectivity values of Platypus time-of-flight neutron reflectometer are presented.

  6. 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.)

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

    OpenAIRE

    Cereser, Alberto; Hall, Stephen A.; Steuwer, Axel; Strobl, Markus; Schmidt, Søren

    2016-01-01

    This thesis presents a new technique for measuring spatially resolved microstructures in crystalline materials using pulsed neutron beams. The method, called Time-of-Flight Three Dimensional Neutron Diffraction (ToF 3DND), identifies the position, shape and crystallographic orientation 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 la...

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Indian Academy of Sciences (India)

    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 > > 1.3 nm) as well as in the monochromatic ( - 2) mode with both polarized and unpolarized neutrons. AMOR is designed to perform reflectometry ...

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

    Indian Academy of Sciences (India)

    Abstract. 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 mode with both polarized and unpolarized neutrons. AMOR is designed to perform reflectometry ...

  20. DN-12 time of flight neutron spectrometer for investigation of structure and dynamics of microsamples

    International Nuclear Information System (INIS)

    Savenko, B.N.; Aksenov, V.L.; Balagurov, A.M.; Kozlenko, D.P.; Sheptyakov, D.V.

    1999-01-01

    DN-12 time of flight neutron spectrometer operating at IBR-2 high flux pulsed reactor at FLNP JINR, Dubna, Russia is described. It is designed for experiments with microsamples in wide range of temperatures and pressures. DN-12 allows to perform neutron diffraction experiments at temperatures down to 15 K and pressures up to 7 Gpa and inelastic incoherent scattering experiments (with samples which have large incoherent neutron scattering cross section) at pressures up to 5 GPa with sapphire anvil high pressure cells. The parameters of the spectrometer, recent results and future prospects are reviewed. (author)

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

    Science.gov (United States)

    Chen, J. B.; Zheng, Z. J.; 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.

    2002-10-01

    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 δ 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.

  2. 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.

  3. Status and outlook of the neutron time-of-flight facility n_TOF at CERN

    CERN Document Server

    Gunsing, F

    2007-01-01

    The neutron time-of-flight facility n_TOF at CERN, fully operational since 2002, combines a high instantaneous neutron flux with high energy resolution. The wide energy range and the high neutron flux per time-of-flight burst result in a much enhanced signal to background ratio for neutron capture of radioactive isotopes and makes this facility well suited for the measurement of high quality neutron-induced reaction cross-sections. Neutrons are created by spallation reactions induced by a pulsed 20 GeV/c proton beam impinging on a lead target. A 5 cm water slab surrounding the lead target serves as a coolant and at the same time as a moderator of the spallation neutron spectrum, providing a wide energy spectrum from 0.1 eV to about 250 MeV. By the end of 2005, a first phase of data taking has been successfully terminated. Fission and capture experiments have been performed on a variety of isotopes of interest for nuclear astrophysics, advanced nuclear technologies and for basic nuclear physics. The instrument...

  4. 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

  5. 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.

  6. 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

  7. Fusion neutron energy spectra measured by time-of-flight spectrometers

    CERN Document Server

    Elevant, T

    2002-01-01

    Evaluation of measured neutron energy spectra provides information on the central ion velocity distribution; e.g. ion temperature and fast ions induced by NBI- or ICR-heating and on impurity content in fusion grade plasmas. Two self-contained high-energy resolution time-of-flight neutron spectrometers have been used at the JET- and JT-60U tokamaks during DD-operation. In the spectrometers, each neutron undergoes (n, p) elastic scattering in two sets of hydrogen based scintillators. Elapsed time between the two scatter events is measured and the energy of the neutron is evaluated. Interpretation of acquired data together with results obtained from other diagnostics yields information on central plasma parameters. Deduced ion temperatures, fast ion fractional contributions during auxiliary NBI- and ICR-heating and impurity content is presented. In general, good agreement is obtained between neutron data and data from other diagnostics.

  8. The multipurpose time-of-flight neutron reflectometer 'Platypus' at Australia's OPAL reactor

    International Nuclear Information System (INIS)

    James, M.; Nelson, A.; Holt, S.A.; Saerbeck, T.; Hamilton, W.A.; Klose, F.

    2011-01-01

    In this manuscript we describe the major components of the Platypus time-of-flight neutron reflectometer at the 20 MW OPAL reactor in Sydney, Australia. Platypus is a multipurpose spectrometer for the characterisation of solid thin films, materials adsorbed at the solid-liquid interface and free-liquid surfaces. It also has the capacity to study magnetic thin films using spin-polarised neutrons. Platypus utilises a white neutron beam (λ=2-20 A) that is pulsed using boron-coated disc chopper pairs; thus providing the capacity to tailor the wavelength resolution of the pulses to suit the system under investigation. Supermirror optical components are used to focus, deflect or spin-polarise the broad bandwidth neutron beams, and typical incident spectra are presented for each configuration. A series of neutron reflectivity datasets are presented, indicating the quality and flexibility of this spectrometer. Minimum reflectivity values of -7 are observed; while maximum thickness values of 325 nm have been measured for single-component films and 483 nm for a multilayer system. Off-specular measurements have also been made to investigate in-plane features as opposed to those normal to the sample surface. Finally, the first published studies conducted using the Platypus time-of-flight neutron reflectometer are presented.

  9. 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

  10. 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

  11. 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.)

  12. 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.

  13. 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

  14. 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.

  15. A preliminary time-of-flight neutron diffraction study of Streptomyces rubiginosus D-xylose isomerase.

    Science.gov (United States)

    Hanson, B Leif; Langan, Paul; Katz, Amy K; Li, Xinmin; Harp, Joel M; Glusker, Jenny P; Schoenborn, Benno P; Bunick, Gerard J

    2004-02-01

    The metalloenzyme D-xylose isomerase forms well ordered crystals that diffract X-rays to ultrahigh resolution (diffraction data has as yet been unable to differentiate between several postulated mechanisms that describe the catalytic activity of this enzyme. Neutrons, with their greater scattering sensitivity to H atoms, could help to resolve this by determining the protonation states within the active site of the enzyme. As the first step in the process of investigating the mechanism of action of D-xylose isomerase from Streptomyces rubiginosus using neutron diffraction, data to better than 2.0 A were measured from the unliganded protein at the Los Alamos Neutron Science Center Protein Crystallography Station. Measurement of these neutron diffraction data represents several milestones: this is one of the largest biological molecules (a tetramer, MW approximately 160 000 Da, with unit-cell lengths around 100 A) ever studied at high resolution using neutron diffraction. It is also one of the first proteins to be studied using time-of-flight techniques. The success of the initial diffraction experiments with D-xylose isomerase demonstrate the power of spallation neutrons for protein crystallography and should provide further impetus for neutron diffraction studies of biologically active and significant proteins. Further data will be measured from the enzyme with bound substrates and inhibitors in order to provide the specific information needed to clarify the catalytic mechanism of this enzyme.

  16. 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

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

    DEFF Research Database (Denmark)

    Cereser, Alberto

    This thesis presents a new technique for measuring spatially resolved microstructures in crystalline materials using pulsed neutron beams. The method, called Time-of-Flight Three Dimensional Neutron Diffraction (ToF 3DND), identifies the position, shape and crystallographic orientation of the ind......This thesis presents a new technique for measuring spatially resolved microstructures in crystalline materials using pulsed neutron beams. The method, called Time-of-Flight Three Dimensional Neutron Diffraction (ToF 3DND), identifies the position, shape and crystallographic orientation...... measurements: a time resolved imaging detector, developed at University of Berkeley, California, was fitted in the interior of SENJU in order to record the extinction spots in the transmitted beam (i.e. areas with missing intensity due to Bragg diffraction of the individual grains). The arrangement of the two...... steps have been developed in this study. The work also shows that based on the transmission data alone the orientations are not uniquely determined; however, it is possible to find an unique solution by including diffraction signals from the imaging detector. The second version uses an existing method...

  18. 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...

  19. 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....... The reconstruction algorithms have been validated by reconstructing two stacked Co-Ni-Ga single crystals, and by comparison with a grain map obtained by post-mortem electron backscatter diffraction (EBSD)....

  20. National Ignition Facility (NIF) Neutron time-of-flight (nTOF) Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lerche, R A; Glebov, V Y; Moran, M J; McNaney, J M; Kilkenny, J D; Eckart, M; Zacharias, R A; Haslam, J J; Clancy, T J; Yeoman, M F; Warwas, D P; Sangster, T C; Stoeckl, C; Knauer, J; Horsfield, C J

    2010-05-13

    The first three of eighteen neutron time-of-flight (nTOF) channels have been installed at the National Ignition Facility (NIF). The role of these detectors includes yield, temperature, and bang time measurements. This article focuses on nTOF data analysis and quality of results obtained for the first set of experiments to use all 192 NIF beams. Targets produced up to 2 x 10{sup 10} 2.45-MeV neutrons for initial testing of the nTOF detectors. Differences in neutron scattering at the OMEGA laser facility where the detectors were calibrated and at NIF result in different response functions at the two facilities. Monte Carlo modeling shows this difference. The nTOF performance on these early experiments indicates the nTOF system with its full complement of detectors should perform well in future measurements of yield, temperature, and bang time.

  1. On the resolution and intensity of a time-of-flight neutron reflectometer

    International Nuclear Information System (INIS)

    Well, A.A. van; Fredrikze, H.

    2005-01-01

    In a neutron reflection experiment, the reflectivity is determined as a function of wave-vector transfer q=4πθ/λ, with θ the glancing angle and λ the neutron wavelength. At a continuous neutron source, it may be advantageous to use the time-of-flight technique to determine λ. Then, a chopper system is used to pulse the beam. We will discuss all contributions to both q resolution and intensity. Special attention is paid to the comparison of using a single- and double-disc chopper system. Examples of the performance of both systems are given. The double-disc chopper produces a burst time proportional to λ. By matching the different contributions to the resolution, the resulting intensity can be optimised

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

    International Nuclear Information System (INIS)

    Su, Yuhua; Oikawa, Kenichi; Harjo, Stefanus; Shinohara, Takenao; Kai, Tetsuya; Harada, Masahide; Hiroi, Kosuke; Zhang, Shuoyuan; Parker, Joseph Don; Sato, Hirotaka; Shiota, Yoshinori; Kiyanagi, Yoshiaki; Tomota, Yo

    2016-01-01

    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.

  3. 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

  4. CVD diamond detectors for current mode neutron time-of-flight spectroscopy at OMEGA/NIF

    Science.gov (United States)

    Schmid, Gregory J.; Glebov, Vladimir Y.; Friensehner, Allen V.; Hargrove, Dana R.; Hatchett, Steven P., II; Izumi, Nobuhiko; Lerche, Richard A.; Phillips, Thomas W.; Sangster, Thomas C.; Silbernagel, Christopher T.; Stoeckl, Christian

    2001-12-01

    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 100 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 (gamma) 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.

  5. 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)

  6. 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

  7. 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

    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...... 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...

  8. 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

  9. Detection system for high-resolution gamma radiation spectroscopy with neutron time-of-flight filtering

    Energy Technology Data Exchange (ETDEWEB)

    Dioszegi, Istvan; Salwen, Cynthia; Vanier, Peter

    2014-12-30

    A .gamma.-radiation detection system that includes at least one semiconductor detector such as HPGe-Detector, a position-sensitive .alpha.-Detector, a TOF Controller, and a Digitizer/Integrator. The Digitizer/Integrator starts to process the energy signals of a .gamma.-radiation sent from the HPGe-Detector instantly when the HPGe-Detector detects the .gamma.-radiation. Subsequently, it is determined whether a coincidence exists between the .alpha.-particles and .gamma.-radiation signal, based on a determination of the time-of-flight of neutrons obtained from the .alpha.-Detector and the HPGe-Detector. If it is determined that the time-of-flight falls within a predetermined coincidence window, the Digitizer/Integrator is allowed to continue and complete the energy signal processing. If, however, there is no coincidence, the Digitizer/Integrator is instructed to be clear and reset its operation instantly.

  10. Diting: A polarized time-of-flight neutron reflectometer at CMRR reactor in China

    Science.gov (United States)

    Li, Xinxi; Huang, Chaoqiang; Wang, Yan; Chen, Bo; Sun, Guang'ai; Liu, Yaoguang; Gong, Jian; Kang, Wu; Liu, Hangang

    2016-11-01

    A new time-of-flight neutron reflectometer with a polarization option is developed and tested at the Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, China. Its scattering geometry is horizontal. The constructed neutron reflectometer is a multipurpose instrument that can be used for the characterization of a stratified microstructure and hidden interfaces of solid thin films. Diting is designed for both magnetic and nonmagnetic multi-layer thin films. Spin polarization and analysis are achieved by transmission magnetized supermirrors. The sample unit is equipped with an electromagnet, which can provide a vertical magnetic field range of 0-1.2 tesla. The available neutron beam is a white beam with wavelength range of 0.15-1.25 nm, which can be cut into different wavelength resolution neutron pulses by a four-disk chopper. A two-dimensional position-sensitive detector is employed to count the specular and off-specular reflected neutron beam. A minimum reflectivity of 10-6 is measured on this instrument.

  11. 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)

  12. 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.)

  13. Integration of neutron time-of-flight single-crystal Bragg peaks in reciprocal space

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, Arthur J [ORNL; Joergensen, Mads [ORNL; Wang, Xiaoping [ORNL; Mikkelson, Ruth L [ORNL; Mikkelson, Dennis J [ORNL; Lynch, Vickie E [ORNL; Peterson, Peter F [ORNL; Green, Mark L [ORNL; Hoffmann, Christina [ORNL

    2014-01-01

    The intensity of single crystal Bragg peaks obtained by mapping neutron time-of-flight event data into reciprocal space and integrating in various ways are compared. These include spherical integration with a fixed radius, ellipsoid fitting and integrating of the peak intensity and one-dimensional peak profile fitting. In comparison to intensities obtained by integrating in real detector histogram space, the data integrated in reciprocal space results in better agreement factors and more accurate atomic parameters. Furthermore, structure refinement using integrated intensities from one-dimensional profile fitting is demonstrated to be more accurate than simple peak-minus-background integration.

  14. An archaeometallurgical study of two harquebusier breastplates using time-of-flight neutron diffraction

    Science.gov (United States)

    Leever, S.; Visser, D.; Kockelmann, W.; Dik, J.

    2006-11-01

    Neutron diffraction patterns were collected from two harquebusier breastplates: one dated round 1600-1650 AD while a second, initially bought as an object dated to the same period, showed after our analysis to be a replica from around 1850-1900 AD. Using data from the time-of-flight diffractometers GEM and ROTAX we determined the compositional variations of the plates and also investigated their manufacturing using texture analysis. The fragments and distinct positions on the breastplates shows that the iron plates are mainly ferrite with a few percent cementite. Oxidation products like wuestite and magnetite have been detected.

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

    Directory of Open Access Journals (Sweden)

    Ehlers G.

    2015-01-01

    Full Text Available 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.

  16. High temperature neutron diffraction (time-of-flight) in Si-Al-O-N compounds

    International Nuclear Information System (INIS)

    Cartz, L.; Roult, G.; Billy, M.

    1977-01-01

    The Si-Al-O-N compounds, intermediate between the Al 2 O 3 -Si 3 N 4 -AlN or SiO 2 phase, can be used as refractory compounds. The resistance to thermal shocks essentially depends on the coefficients of anisotropic thermal expansion, that explains their experimental determination for Si 2 N 2 O by time-of-flight neutron diffraction at high temperature. The nature of the anisotropies was shown to correspond to a crystal structure of Si 2 N 2 O involving Si-O-Si bounds along the x axis, and Si-N bounds in the y-z plane [fr

  17. 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

  18. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1989-10-13

    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 {times} 1 cm and time-of-flight resolution of {approximately}1 {mu}sec 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 {approximately}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.

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

    Science.gov (United States)

    Cereser, Alberto; Strobl, Markus; Hall, Stephen A; Steuwer, Axel; Kiyanagi, Ryoji; Tremsin, Anton S; Knudsen, Erik B; Shinohara, Takenao; Willendrup, Peter K; da Silva Fanta, Alice Bastos; Iyengar, Srinivasan; Larsen, Peter M; Hanashima, Takayasu; Moyoshi, Taketo; Kadletz, Peter M; Krooß, Philipp; Niendorf, Thomas; Sales, Morten; Schmahl, Wolfgang W; Schmidt, Søren

    2017-08-25

    The physical properties of polycrystalline materials depend on their microstructure, which is the nano- to centimeter scale arrangement of phases and defects in their interior. Such microstructure depends on the shape, crystallographic phase and orientation, and interfacing of the grains 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 enables studies of samples that can be both larger in size and made of heavier elements. Moreover, ToF 3DND facilitates the use of complicated sample environments. The basic ToF 3DND setup, utilizing an imaging detector with high spatial and temporal resolution, can easily be implemented at a time-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. The reconstruction algorithms have been validated by reconstructing two stacked Co-Ni-Ga single crystals, and by comparison with a grain map obtained by post-mortem electron backscatter diffraction (EBSD).

  1. Time-of-Flight Polarized Neutron Reflectometry on PLATYPUS: Status and Future Developments

    Science.gov (United States)

    Saerbeck, T.; Cortie, D. L.; Brück, S.; Bertinshaw, J.; Holt, S. A.; Nelson, A.; James, M.; Lee, W. T.; Klose, F.

    Time-of-flight (ToF) polarized neutron reflectometry enables the detailed investigation of depth-resolved magnetic structures in thin film and multilayer magnetic systems. The general advantage of the time-of-flight mode of operation over monochromatic instruments is a decoupling of spectral shape and polarization of the neutron beam with variable resolution. Thus, a wide Q-range can be investigated using a single angle of incidence, with resolution and flux well-adjusted to the experimental requirement. Our paper reviews the current status of the polarization equipment of the ToF reflectometer PLATYPUS and presents first results obtained on stratified Ni80Fe20/α-Fe2O3 films, revealing the distribution of magnetic moments in an exchange bias system. An outlook on the future development of the PLATYPUS polarization system towards the implementation of a polarized 3He cell is presented and discussed with respect to the efficiency and high Q-coverage up to 1 Å-1 and 0.15 Å-1 in the vertical and lateral momentum transfer, respectively.

  2. 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.

  3. Design of a new time-of-flight small-angle neutron scattering instrument at CPHS

    International Nuclear Information System (INIS)

    Huang, T.C.; Gong, H.; Shao, B.B.; Wang, D.; Zhang, X.Z.; Zhang, K.; Wei, J.; Wang, X.W.; Guan, X.L.; Loong, C.-K.; Tao, J.Z.; Zhou, L.; Ke, Y.B.

    2012-01-01

    A new time-of-flight (TOF) small-angle neutron scattering (SANS) diffractometer is to be built at the Compact Pulsed Hadron Source (CPHS) of Tsinghua University, China. This SANS project strives to serve two purposes: its instrumental design, fabrication and optimization will help glean valuable scientific and engineering experiences; and its utilization will help promote fruitful domestic user programs on research of large structures in advanced materials using neutrons. The design draws experiences from other TOF SANS instruments, particularly that of the long-pulse LENS of Indiana University and also considers the source features at CPHS. The design team enjoyed the guidance and assistance from experts through international collaborations. For simultaneous collection of scattering data in the Q-range (∼7×10 -3 -1 ) with reasonable Q-resolution and high efficiency, this instrument is designed to use large area detector (1×1 m 2 ) and broad wavelength bandwidth (1-10 Å) within the first frame. It also pays attention to possible use of optical devices such as neutron guides, focusing lenses and novel detectors.

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

    Science.gov (United States)

    Gunsing, F.; Aberle, O.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Bacak, M.; Balibrea-Correa, J.; Barbagallo, M.; Barros, S.; Bečvář, F.; Beinrucker, C.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brown, A.; Brugger, M.; Caamaño, M.; Calviño, F.; Calviani, M.; Cano-Ott, D.; Cardella, R.; Casanovas, A.; Castelluccio, D. M.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Colonna, N.; Cortés-Giraldo, M. A.; Cortés, G.; Cosentino, L.; Damone, L. A.; Deo, K.; Diakaki, M.; Domingo-Pardo, C.; Dressler, R.; Dupont, E.; Durán, I.; Fernández-Domínguez, B.; Ferrari, A.; Ferreira, P.; Finocchiaro, P.; Frost, R. J. W.; Furman, V.; Ganesan, S.; García, A. R.; Gawlik, A.; Gheorghe, I.; Gilardoni, S.; Glodariu, T.; Gonçalves, I. F.; González, E.; Goverdovski, A.; Griesmayer, E.; Guerrero, C.; Göbel, K.; Harada, H.; Heftrich, T.; Heinitz, S.; Hernández-Prieto, A.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Käppeler, F.; Kadi, Y.; Kalamara, A.; Katabuchi, T.; Kavrigin, P.; Ketlerov, V.; Khryachkov, V.; Kimura, A.; Kivel, N.; Kokkoris, M.; Krtička, M.; Kurtulgil, D.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Lerendegui, J.; Licata, M.; Meo, S. Lo; Lonsdale, S. J.; Losito, R.; Macina, D.; Marganiec, J.; Martínez, T.; Masi, A.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Matteucci, F.; Maugeri, E. A.; Mazzone, A.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Montesano, S.; Musumarra, A.; Nolte, R.; Negret, A.; Oprea, A.; Palomo-Pinto, F. R.; Paradela, C.; Patronis, N.; Pavlik, A.; Perkowski, J.; Porras, I.; Praena, J.; Quesada, J. M.; Radeck, D.; Rajeev, K.; Rauscher, T.; Reifarth, R.; Riego-Perez, A.; Robles, M.; Rout, P.; Rubbia, C.; Ryan, J. A.; Sabaté-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Sedyshev, P.; Smith, A. G.; Sosnin, N. V.; Stamatopoulos, A.; Suryanarayana, S. V.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tarrío, D.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Warren, S.; Weigand, M.; Weiss, C.; Wolf, C.; Woods, P. J.; Wright, T.; Žugec, P.

    2017-09-01

    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.

  5. 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.

  6. 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

  7. 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.

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

    Science.gov (United States)

    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(exp 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.

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

    Science.gov (United States)

    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 5×109 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.

  10. 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

  11. SENJU: a new time-of-flight single-crystal neutron diffractometer at J-PARC.

    Science.gov (United States)

    Ohhara, Takashi; Kiyanagi, Ryoji; Oikawa, Kenichi; Kaneko, Koji; Kawasaki, Takuro; Tamura, Itaru; Nakao, Akiko; Hanashima, Takayasu; Munakata, Koji; Moyoshi, Taketo; Kuroda, Tetsuya; Kimura, Hiroyuki; Sakakura, Terutoshi; Lee, Chang-Hee; Takahashi, Miwako; Ohshima, Ken-Ichi; Kiyotani, Tamiko; Noda, Yukio; Arai, Masatoshi

    2016-02-01

    SENJU is a new single-crystal time-of-flight neutron diffractometer installed at BL18 at the Materials and Life Science Experimental Facility of the Japan Accelerator Research Complex (J-PARC). The diffractometer was designed for precise crystal and magnetic structure analyses under multiple extreme sample environments such as low temperature, high pressure and high magnetic field, and for diffraction measurements of small single crystals down to 0.1 mm 3 in volume. SENJU comprises three choppers, an elliptical shape straight supermirror guide, a vacuum sample chamber and 37 scintillator area detectors. The moderator-to-sample distance is 34.8 m, and the sample-to-detector distance is 800 mm. The wavelength of incident neutrons is 0.4-4.4 Å (first frame). Because short-wavelength neutrons are available and the large solid angle around the sample position is covered by the area detectors, a large reciprocal space can be simultaneously measured. Furthermore, the vacuum sample chamber and collimator have been designed to produce a very low background level. Thus, the measurement of a small single crystal is possible. As sample environment devices, a newly developed cryostat with a two-axis (ω and φ axes) goniometer and some extreme environment devices, e.g. a vertical-field magnet, high-temperature furnace and high-pressure cell, are available. The structure analysis of a sub-millimetre size (0.1 mm 3 ) single organic crystal, taurine, and a magnetic structure analysis of the antiferromagnetic phase of MnF 2 have been performed. These results demonstrate that SENJU can be a powerful tool to promote materials science research.

  12. 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.)

  13. 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)

  14. Prompt gamma activation analysis and time of flight neutron diffraction on 'black boxes' in the 'Ancient Charm' project

    International Nuclear Information System (INIS)

    Kasztovszky, Zs.; Kis, Z.; Belgya, T.; Kirfel, A.; Biro, K.T.

    2008-01-01

    The aim of the 'Ancient Charm' project is combining neutron tomography, prompt gamma activation analysis, time of flight neutron diffraction and neutron resonance transmission to generate elemental, and phase compositions of complex museum objects in 3D. To develop a protocol for such investigations, complex test samples were constructed and then analyzed by each method. The 'black boxes' are sealed iron and aluminum walled cubes, containing 2D or 3D arrangements of materials relevant for the compositions of archaeological samples. The experimental results obtained from bulk PGAA at BNC and TOF-ND at ISIS on two selected boxes are reported. (author)

  15. A comparison of time-of-flight and Larmor modulation neutron powder diffraction at a continuous reactor source

    CERN Document Server

    Mulder, F M

    1999-01-01

    A neutron powder diffraction instrument for application at a continuous reactor source based on time-of-flight (TOF) is compared with an instrument based on Larmor modulation (LM). For instruments with a similar wave-vector resolution (delta q/q=4x10 sup - sup 3) it is found that the signal-to-noise ratios in a TOF experiment are generally better when using a wide wavelength neutron spectrum. This is caused by the fact that the noise in a LM experiment comes from the integrated neutron flux scattered in the detector, while in TOF the noise stems only from the intensity scattered into individual time channels.

  16. Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

    DEFF Research Database (Denmark)

    Jacobsen, Asger Schou; Salewski, Mirko; Eriksson, J.

    2014-01-01

    spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly...

  17. Time-of-flight neutron diffraction study of bovine γ-chymotrypsin at the Protein Crystallography Station.

    Science.gov (United States)

    Lazar, Louis M; Fisher, S Zoe; Moulin, Aaron G; Kovalevsky, Andrey; Novak, Walter R P; Langan, Paul; Petsko, Gregory A; Ringe, Dagmar

    2011-05-01

    The overarching goal of this research project is to determine, for a subset of proteins, exact hydrogen positions using neutron diffraction, thereby improving H-atom placement in proteins so that they may be better used in various computational methods that are critically dependent upon said placement. In order to be considered applicable for neutron diffraction studies, the protein of choice must be amenable to ultrahigh-resolution X-ray crystallography, be able to form large crystals (1 mm(3) or greater) and have a modestly sized unit cell (no dimension longer than 100 Å). As such, γ-chymotrypsin is a perfect candidate for neutron diffraction. To understand and probe the role of specific active-site residues and hydrogen-bonding patterns in γ-chymotrypsin, neutron diffraction studies were initiated at the Protein Crystallography Station (PCS) at Los Alamos Neutron Science Center (LANSCE). A large single crystal was subjected to H/D exchange prior to data collection. Time-of-flight neutron diffraction data were collected to 2.0 Å resolution at the PCS with ~85% completeness. Here, the first time-of-flight neutron data collection from γ-chymotrypsin is reported.

  18. 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.

  19. The multipurpose time-of-flight neutron reflectometer 'Platypus' at Australia's OPAL reactor

    Energy Technology Data Exchange (ETDEWEB)

    James, M., E-mail: mja@ansto.gov.a [Bragg Institute, Building 87, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); School of Chemistry, University of New South Wales, Kensington, NSW 2052 (Australia); Nelson, A.; Holt, S.A.; Saerbeck, T.; Hamilton, W.A.; Klose, F. [Bragg Institute, Building 87, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia)

    2011-03-11

    In this manuscript we describe the major components of the Platypus time-of-flight neutron reflectometer at the 20 MW OPAL reactor in Sydney, Australia. Platypus is a multipurpose spectrometer for the characterisation of solid thin films, materials adsorbed at the solid-liquid interface and free-liquid surfaces. It also has the capacity to study magnetic thin films using spin-polarised neutrons. Platypus utilises a white neutron beam ({lambda}=2-20 A) that is pulsed using boron-coated disc chopper pairs; thus providing the capacity to tailor the wavelength resolution of the pulses to suit the system under investigation. Supermirror optical components are used to focus, deflect or spin-polarise the broad bandwidth neutron beams, and typical incident spectra are presented for each configuration. A series of neutron reflectivity datasets are presented, indicating the quality and flexibility of this spectrometer. Minimum reflectivity values of <10{sup -7} are observed; while maximum thickness values of 325 nm have been measured for single-component films and 483 nm for a multilayer system. Off-specular measurements have also been made to investigate in-plane features as opposed to those normal to the sample surface. Finally, the first published studies conducted using the Platypus time-of-flight neutron reflectometer are presented.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. High resolution spectroscopy at FRM II: neutron resonance spin echo, back scattering and time-of-flight instrumentation

    International Nuclear Information System (INIS)

    Petry, W.

    2001-01-01

    The new German neutron source FRM II is equipped with a D 2 cold source placed in the maximum of the thermal flux in the D 2 O moderator. This cold source feeds six large neutron guides. Among others a neutron resonance spin echo (NRSE), a back scattering (BS) and a time-of-flight (TOF) spectrometer will be placed at end positions of theses guides. By detailed Monte-Carlo simulations each of the instruments is optimized for highest intensity without scarifying energy resolution. A polarized neutron guide in combination with a non magnetic wave-length selector provides high flux at the sample position of the NRSE instrument with typical spin-echo times of 30 ns at all accessible scattering angles. The BS instrument uses phase-space transformation to compress a large spread of incoming wave length to an intense monoenergetic but angular disperse beam at the sample. An intensity gain by a factor of four has been calculated without losses in energy resolution of <1 μeV (fwhm) when compared to conventional BS. The TOF spectrometer suppresses background from fast neutrons by a S-curved super-mirror guide and focusses a large incoming neutron beam onto a small sample volume, thereby increasing the flux at the sample position by a factor 3.2. Energy resolution of typical 30 μeV (fwhm) at a wave length of λ=5 A is achieved by extremely fast turning chopper discs made of carbon fiber. (author)

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

    Science.gov (United States)

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

    2013-07-01

    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.

  6. A Rietveld refinement method for angular- and wavelength-dispersive neutron time-of-flight powder diffraction data.

    Science.gov (United States)

    Jacobs, Philipp; Houben, Andreas; Schweika, Werner; Tchougréeff, Andrei L; Dronskowski, Richard

    2015-12-01

    This paper introduces a two-dimensional extension of the well established Rietveld refinement method for modeling neutron time-of-flight powder diffraction data. The novel approach takes into account the variation of two parameters, diffraction angle 2θ and wavelength λ, to optimally adapt to the varying resolution function in diffraction experiments. By doing so, the refinement against angular- and wavelength-dispersive data gets rid of common data-reduction steps and also avoids the loss of high-resolution information typically introduced by integration. In a case study using a numerically simulated diffraction pattern of Rh 0.81 Fe 3.19 N taking into account the layout of the future POWTEX instrument, the profile function as parameterized in 2θ and λ is extracted. As a proof-of-concept, the resulting instrument parameterization is then utilized to perform a typical refinement of the angular- and wavelength-dispersive diffraction pattern of CuNCN, yielding excellent residuals within feasible computational efforts. Another proof-of-concept is carried out by applying the same approach to a real neutron diffraction data set of CuNCN obtained from the POWGEN instrument at the Spallation Neutron Source in Oak Ridge. The paper highlights the general importance of the novel approach for data analysis at neutron time-of-flight diffractometers and its possible inclusion within existing Rietveld software packages.

  7. 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...

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

    OpenAIRE

    Cereser, Alberto; Strobl, Markus; Hall, Stephen; Steuwer, Axel; Kiyanagi, Ryoji; Tremsin, Anton; Knudsen, Erik Bergbäck; Shinohara, Takenao; Willendrup, Peter; Fanta, Alice Bastos da Silva; Iyengar, Srinivasan; Larsen, Peter Mahler; Hanashima, Takayasu; Moyoshi, Taketo; Kadletz, Peter M.

    2017-01-01

    The physical properties of polycrystalline materials depend on their microstructure, which is the nano- to centimeter scale arrangement of phases and defects in their interior. Such microstructure depends on the shape, crystallographic phase and orientation, and interfacing of the grains 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 ne...

  9. 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

  10. 252Cf fission-neutron spectrum using a simplified time-of-flight setup: An advanced teaching laboratory experiment

    Science.gov (United States)

    Becchetti, F. D.; Febbraro, M.; Torres-Isea, R.; Ojaruega, M.; Baum, L.

    2013-02-01

    The removal of PuBe and AmBe neutron sources from many university teaching laboratories (due to heightened security issues) has often left a void in teaching various aspects of neutron physics. We have recently replaced such sources with sealed 252Cf oil-well logging sources (nominal 10-100 μCi), and developed several experiments using them as neutron sources. This includes a fission-neutron time-of-flight experiment using plastic scintillators, which utilizes the prompt γ rays emitted in 252Cf spontaneous fission as a fast timing start signal. The experiment can be performed with conventional nuclear instrumentation and a 1-D multi-channel pulse-height analyzer, available in most advanced teaching laboratories. Alternatively, a more sophisticated experiment using liquid scintillators and n/γ pulse-shape discrimination can be performed. Several other experiments using these neutron sources are also feasible. The experiments can introduce students to the problem of detecting the dark matter thought to dominate the universe and to the techniques used to detect contraband fissionable nuclear materials.

  11. In situ deformation apparatus for time-of-flight neutron diffraction: Texture development of polycrystalline ice Ih

    International Nuclear Information System (INIS)

    McDaniel, S.; Bennett, K.; Durham, W. B.; Waddington, E. D.

    2006-01-01

    This article documents a new in situ deformation apparatus built for neutron diffraction investigations of polycrystalline materials in low-temperature environments and the first experiment in which it was used. We performed texture analysis of fine-grained polycrystalline D 2 O ice I h deformed uniaxially between 230 and 240 K using time-of-flight neutron diffraction on the high-pressure preferred orientation diffractometer at the Manuel Lujan, Jr. Neutron Scattering Center at Los Alamos National Laboratory. The new deformation apparatus operates at 1 atm of ambient pressure and over temperatures in the range of 77 K< T<298 K, and accommodates up to 667 N of uniaxially applied load. It is suitable for diffraction studies of any bulk polycrystalline material, ideally cylindrical in shape, and is adaptable to multiple neutron spectrometers, including those at other polychromatic and monochromatic neutron facilities. The first experiment on a hexagonal ice sample demonstrates development of fiber texture in the direction of the applied load. The equipment has many applications to earth science, glaciology, and ice engineering

  12. The time-of-flight small-angle scattering spectrometer SAN at the KENS pulsed cold neutron source

    International Nuclear Information System (INIS)

    Ishikawa, Y.; Furusaka, M.; Hasegawa, K.

    1986-01-01

    This paper describes the configuration and performance of a new time-of-flight (TOF) small-angle neutron scattering spectrometer SAN installed at the pulsed cold neutron source (KENS) at the National Laboratory for High Energy Physics (KEK). The spectrometer has advantages over conventional small-angle scattering apparatus: one is its capability for simultaneous measurements over a wide Q range (0.003≤Q≤4 A -1 ) and another is the new information that it provides by exploiting the wavelength dependence of the scattering. For example, the inelastic and elastic scattering can be separated without performing an energy analysis. The design principles of this type of spectrometer are also discussed. (orig.)

  13. Concept for a time-of-flight Small Angle Neutron Scattering instrument at the European Spallation Source

    Energy Technology Data Exchange (ETDEWEB)

    Jaksch, S. [ESS Design Update Programme – Germany, Forschungszentrum Jülich GmbH, Jülich (Germany); Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Forschungszentrum Jülich GmbH, Garching (Germany); Martin-Rodriguez, D. [ESS Design Update Programme – Germany, Forschungszentrum Jülich GmbH, Jülich (Germany); Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Forschungszentrum Jülich GmbH, Garching (Germany); Neutron Optics and Shielding Group, European Spallation Source AB, Lund (Sweden); Ostermann, A. [Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II) at Heinz Maier-Leibnitz Zentrum, Technische Universität Muünchen, Garching (Germany); Jestin, J. [Laboratoire Léon Brillouin, LLB, CEA—Saclay, Gif sur Yvette cedex (France); Duarte Pinto, S.; Bouwman, W.G. [Faculty of Applied Sciences, Delft University of Technology, Delft (Netherlands); Uher, J. [Amsterdam Scientific Instruments, Amsterdam (Netherlands); Engels, R. [Zentralinstitut für Elektronik (ZEA-2), Forschungszentrum Jülich GmbH, Jülich (Germany); Frielinghaus, H. [ESS Design Update Programme – Germany, Forschungszentrum Jülich GmbH, Jülich (Germany); Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Forschungszentrum Jülich GmbH, Garching (Germany)

    2014-10-21

    A new Small Angle Neutron Scattering instrument is proposed for the European Spallation Source. The pulsed source requires a time-of-flight analysis of the gathered neutrons at the detector. The optimal instrument length is found to be rather large, which allows for a polarizer and a versatile collimation. The polarizer allows for studying magnetic samples and incoherent background subtraction. The wide collimation will host VSANS and SESANS options that increase the resolution of the instrument towards µm and tens of µm, respectively. Two 1 m{sup 2} area detectors will cover a large solid angle simultaneously. The expected gains for this new instrument will lie in the range between 20 and 36, depending on the assessment criteria, when compared to up-to-date reactor based instruments. This will open new perspectives for fast kinetics, weakly scattering samples, and multi-dimensional contrast variation studies.

  14. 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.

  15. Magnetic properties of nano-scale hematite, α-Fe2O3, studied by time-of-flight inelastic neutron spectroscopy

    DEFF Research Database (Denmark)

    Hill, Adrian H.; Jacobsen, Henrik Skåret; Stewart, J. Ross

    2014-01-01

    Samples of nanoscale hematite, α-Fe2O3, 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 scatterin...

  16. Time-of-flight neutron rejection to improve prompt gamma imaging for proton range verification: a simulation study.

    Science.gov (United States)

    Biegun, Aleksandra K; Seravalli, Enrica; Lopes, Patrícia Cambraia; Rinaldi, Ilaria; Pinto, Marco; Oxley, David C; Dendooven, Peter; Verhaegen, Frank; Parodi, Katia; Crespo, Paulo; Schaart, Dennis R

    2012-10-21

    Therapeutic proton and heavier ion beams generate prompt gamma photons that may escape from the patient. In principle, this allows for real-time, in situ monitoring of the treatment delivery, in particular, the hadron range within the patient, by imaging the emitted prompt gamma rays. Unfortunately, the neutrons simultaneously created with the prompt photons create a background that may obscure the prompt gamma signal. To enhance the accuracy of proton dose verification by prompt gamma imaging, we therefore propose a time-of-flight (TOF) technique to reject this neutron background, involving a shifting time window to account for the propagation of the protons through the patient. Time-resolved Monte Carlo simulations of the generation and transport of prompt gamma photons and neutrons upon irradiation of a PMMA phantom with 100, 150 and 200 MeV protons were performed using Geant4 (version 9.2.p02) and MCNPX (version 2.7.D). The influence of angular collimation and TOF selection on the prompt gamma and neutron longitudinal profiles is studied. Furthermore, the implications of the proton beam microstructure (characterized by the proton bunch width and repetition period) are investigated. The application of a shifting TOF window having a width of ΔTOF(z) = 1.0 ns appears to reduce the neutron background by more than 99%. Subsequent application of an energy threshold does not appear to sharpen the distal falloff of the prompt gamma profile but reduces the tail that is observed beyond the proton range. Investigations of the influence of the beam time structure show that TOF rejection of the neutron background is expected to be effective for typical therapeutic proton cyclotrons.

  17. Time of flight grazing incidence small angle neutron scattering. A novel scattering technique for the investigation of nanostructured polymer films

    Science.gov (United States)

    Müller-Buschbaum, P.; Metwalli, E.; Moulin, J.-F.; Kudryashov, V.; Haese-Seiller, M.; Kampmann, R.

    2009-02-01

    Grazing incidence small angle neutron scattering (GISANS) overcomes the limitations of conventional small angle scattering with respect to extremely small sample volumes in the thin film geometry. In time of flight (TOF) mode neutrons with a broad range of wavelengths are used simultaneously and recorded as a function of their respective times of flight. The combination of both, TOF-GISANS, enables the simultaneous performance of several GISANS measurements, which differ in wavelength. As a consequence, within one measurement a full set of GISANS pattern related to different scattering vectors, different scattering depths and resolutions result. This allows the detection of nanostructures with a chemical sensitivity. The possibilities of TOF-GISANS are demonstrated by the simple example of polymer nano-dots located on top of a silicon surface. As probed with atomic force microscopy (AFM) the nano-dots exhibit a large characteristic nearest neighbour distance of 545 nm and a surface coverage of 28%. From the analysis of the wavelength dependent data in combination with AFM the mass density of the polymer nano-dots is determined to be equal to the bulk value. A comparison to common single wavelength GISANS experiments is shown.

  18. 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.

  19. Data processing workflow for time of flight polarized neutrons inelastic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Savici, Andrei T [ORNL; Zaliznyak, Igor [Brookhaven National Laboratory (BNL); Garlea, Vasile O [ORNL; Winn, Barry L [ORNL

    2017-01-01

    We discuss the data processing workflow for polarized neutron scattering measurements performed at HYSPEC spectrometer at the Spallation Neutron Source, Oak Ridge National Laboratory. The effects of the focusing Heusler crystal polarizer and the wide-angle supermirror transmission polarization analyzer are added to the data processing flow of the non-polarized case. The implementation is done using the Mantid software package.

  20. Development of the time-of-flight smaller-angle neutron scattering instrument TAIKAN

    International Nuclear Information System (INIS)

    Suzuki, Jun-ichi; Takata, Shin-ichi; Shinohara, Takenao; Oku, Takayuki; Kira, Hiroshi; Suzuya, Kentaro; Aizawa, Kazuya; Arai, Masatoshi; Otomo, Toshiya; Sugiyama, Masaaki

    2010-01-01

    The technique of small-angle neutron scattering has been used to analyze structures of size between about 1 nm and 10 μm in materials and life science. This article introduces the development of the smaller-angle neutron scattering instrument 'TAIKAN' of MLF/J-PARC, which will provide opportunity for efficient structure analysis with high spatial- and time-resolution. (author)

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

    Science.gov (United States)

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

    2016-10-01

    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 RbMnF3 and ferromagnetic iron, and the phonons in URu2Si2.

  2. 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

  3. 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

  4. 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)

  5. Neutron time-of-flight measurement techniques: new possibilities of TOF spectroscopy with NEAT at BENSC

    CERN Document Server

    Ruffle, B; Longeville, S; Lechner, R E

    2000-01-01

    A series of experiments performed on the TOF spectrometer NEAT at the Berlin Neutron Scattering Center is reported to demonstrate the versatility and some of the original possibilities offered by this instrument: continuous variation of the energy resolution over four decades, TOF diffraction using single detectors and a large range of incident neutron wavelengths, high-resolution studies in (Q, omega)-space of single crystals with a multidetector at large scattering angle, or elastic and inelastic small-angle scattering with the multidetector at zero angle.

  6. Preliminary time-of-flight neutron diffraction study on diisopropyl fluorophosphatase (DFPase) from Loligo vulgaris

    Energy Technology Data Exchange (ETDEWEB)

    Blum, Marc-Michael [Institute of Biophysical Chemistry, J. W. Goethe University Frankfurt, Max-von-Laue-Strasse 9, D-60438 Frankfurt (Germany); Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, D-80937 Munich (Germany); Koglin, Alexander [Institute of Biophysical Chemistry, J. W. Goethe University Frankfurt, Max-von-Laue-Strasse 9, D-60438 Frankfurt (Germany); Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115 (United States); Rüterjans, Heinz [Institute of Biophysical Chemistry, J. W. Goethe University Frankfurt, Max-von-Laue-Strasse 9, D-60438 Frankfurt (Germany); Schoenborn, Benno [Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Langan, Paul [Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Department of Chemistry, University of Toledo, Toledo, OH 53606 (United States); Chen, Julian C.-H., E-mail: chen@chemie.uni-frankfurt.de [Institute of Biophysical Chemistry, J. W. Goethe University Frankfurt, Max-von-Laue-Strasse 9, D-60438 Frankfurt (Germany)

    2007-01-01

    Diisopropyl fluorophosphatase (DFPase) effectively hydrolyzes a number of organophosphorus nerve agents, including sarin, cyclohexylsarin, soman and tabun. Neutron diffraction data have been collected from DFPase crystals to 2.2 Å resolution in an effort to gain further insight into the mechanism of this enzyme. The enzyme diisopropyl fluorophosphatase (DFPase) from Loligo vulgaris is capable of decontaminating a wide variety of toxic organophosphorus nerve agents. DFPase is structurally related to a number of enzymes, such as the medically important paraoxonase (PON). In order to investigate the reaction mechanism of this phosphotriesterase and to elucidate the protonation state of the active-site residues, large-sized crystals of DFPase have been prepared for neutron diffraction studies. Available H atoms have been exchanged through vapour diffusion against D{sub 2}O-containing mother liquor in the capillary. A neutron data set has been collected to 2.2 Å resolution on a relatively small (0.43 mm{sup 3}) crystal at the spallation source in Los Alamos. The sample size and asymmetric unit requirements for the feasibility of neutron diffraction studies are summarized.

  7. Preliminary time-of-flight neutron diffraction study on diisopropyl fluorophosphatase (DFPase) from Loligo vulgaris

    International Nuclear Information System (INIS)

    Blum, Marc-Michael; Koglin, Alexander; Rüterjans, Heinz; Schoenborn, Benno; Langan, Paul; Chen, Julian C.-H.

    2006-01-01

    Diisopropyl fluorophosphatase (DFPase) effectively hydrolyzes a number of organophosphorus nerve agents, including sarin, cyclohexylsarin, soman and tabun. Neutron diffraction data have been collected from DFPase crystals to 2.2 Å resolution in an effort to gain further insight into the mechanism of this enzyme. The enzyme diisopropyl fluorophosphatase (DFPase) from Loligo vulgaris is capable of decontaminating a wide variety of toxic organophosphorus nerve agents. DFPase is structurally related to a number of enzymes, such as the medically important paraoxonase (PON). In order to investigate the reaction mechanism of this phosphotriesterase and to elucidate the protonation state of the active-site residues, large-sized crystals of DFPase have been prepared for neutron diffraction studies. Available H atoms have been exchanged through vapour diffusion against D 2 O-containing mother liquor in the capillary. A neutron data set has been collected to 2.2 Å resolution on a relatively small (0.43 mm 3 ) crystal at the spallation source in Los Alamos. The sample size and asymmetric unit requirements for the feasibility of neutron diffraction studies are summarized

  8. Depth-sensitive time-of-flight small-angle neutron scattering

    OpenAIRE

    Herbel, Jörg

    2013-01-01

    Block copolymers are quiet imported in industry. A detailed knowledge of the solid-liquid boundary conditions for surface effects in their aqueous solutions supports the development of smart coatings or the understanding of the folding of proteins in the vicinity of cell membranes. In this work, data collected from small-angle neutron scattering (SANS) experiments will be evaluated. The probed material is a 20\\% (in weight) solution of the polymer Pluronic F127, which forms micelles inside th...

  9. Quasielastic and low-energy inelastic neutron scattering study of HoCrO3 by high resolution time-of-flight neutron spectroscopy.

    Science.gov (United States)

    Chatterji, Tapan Kumar; Demmel, F; Jalarvo, Niina; Podlesnyak, Andrey; Chogondalli Muniraju, Naveen Kumar; Xiao, Yinguo; Brueckel, Thomas

    2017-10-10

    n order to understand the origin of the huge quasielastic magnetic scattering observed previously with a back-scattering neutron spectrometer we have re-investigated the low energy excitations in HoCrO$_3$ by inelastic neutron scattering in a much wider energy range with time-of-flight neutron spectrometers. The inelastic signals are due to the excitations between the ground state doublet of the Ho ion. The quasielastic signal is due to the fluctuation of the disordered Ho moments. At low temperature the intensity of quasielastic scattering is small. It starts increasing as the temperature increases above 30 K. At the same temperature the elastic intensity due to Ho moment ordering decreases in a similar way. This observation strengthens the hypothesis that the quasielastic scattering is due the fluctuations of the disordered Ho moments. The time scale of fluctuations has been determine from the quasielastic scattering and was found to vary from about 22 ps at T = 70 K to about 2.5 ps at T = 160 K. The stretched exponential line shape indicates a distribution of decay rates at low temperatures. © 2017 IOP Publishing Ltd.

  10. Quasielastic and low-energy inelastic neutron scattering study of HoCrO3 by high resolution time-of-flight neutron spectroscopy

    Science.gov (United States)

    Chatterji, T.; Demmel, F.; Jalarvo, N.; Podlesnyak, A.; Kumar, C. M. N.; Xiao, Y.; Brückel, T.

    2017-11-01

    In order to understand the origin of the huge quasielastic magnetic scattering observed previously with a back-scattering neutron spectrometer, we have re-investigated the low energy excitations in HoCrO3 by inelastic neutron scattering in a much wider energy range with time-of-flight neutron spectrometers. The inelastic signals are due to the excitations between the ground state doublet of the Ho ion. The quasielastic signal is due to the fluctuation of the disordered Ho moments. At low temperature the intensity of quasielastic scattering is small. It starts increasing as the temperature increases above 30 K. At the same temperature, the elastic intensity due to Ho moment ordering decreases in a similar way. This observation strengthens the hypothesis that the quasielastic scattering is due the fluctuations of the disordered Ho moments. The time scale of fluctuations has been determine from the quasielastic scattering and was found to vary from about 22 ps at T = 70 K to about 2.5 ps at T = 160 K. The stretched exponential line shape indicates a distribution of decay rates at low temperatures.

  11. Single crystal time-of-flight neutron diffraction of Cr3Si and MnF2: Comparison with monochromatic beam techniques

    International Nuclear Information System (INIS)

    Jauch, W.; Schultz, A.J.

    1987-01-01

    Single-crystal time-of-flight (TOF) neutron diffraction data have been collected for Cr 3 Si and MnF 2 with the Argonne Intense Pulsed Neutron Source. The purpose of this study was to test the accuracy of the TOF technique by a comparison with results from recent γ-ray, X-ray and neutron diffraction experiments. The results show that for simple crystal structures the positional and thermal parameters obtained from TOF data approach those obtained by other diffraction methods. (orig.)

  12. Crystal structures of deuterated sodium molybdate dihydrate and sodium tungstate dihydrate from time-of-flight neutron powder diffraction.

    Science.gov (United States)

    Fortes, A Dominic

    2015-07-01

    Time-of-flight neutron powder diffraction data have been measured from ∼90 mol% deuterated isotopologues of Na2MoO4·2H2O and Na2WO4·2H2O at 295 K to a resolution of sin (θ)/λ = 0.77 Å(-1). The use of neutrons has allowed refinement of structural parameters with a precision that varies by a factor of two from the heaviest to the lightest atoms; this contrasts with the X-ray based refinements where precision may be > 20× poorer for O atoms in the presence of atoms such as Mo and W. The accuracy and precision of inter-atomic distances and angles are in excellent agreement with recent X-ray single-crystal structure refinements whilst also completing our view of the hydrogen-bond geometry to the same degree of statistical certainty. The two structures are isotypic, space-group Pbca, with all atoms occupying general positions, being comprised of edge- and corner-sharing NaO5 and NaO6 polyhedra that form layers parallel with (010) inter-leaved with planes of XO4 (X = Mo, W) tetra-hedra that are linked by chains of water mol-ecules along [100] and [001]. The complete structure is identical with the previously described molybdate [Capitelli et al. (2006 ▸). Asian J. Chem. 18, 2856-2860] but shows that the purported three-centred inter-action involving one of the water mol-ecules in the tungstate [Farrugia (2007 ▸). Acta Cryst. E63, i142] is in fact an ordinary two-centred 'linear' hydrogen bond.

  13. The crystal structure of lueshite at 298 K resolved by high-resolution time-of-flight neutron powder diffraction

    Science.gov (United States)

    Mitchell, Roger H.; Kennedy, Brendan J.; Knight, Kevin S.

    2018-01-01

    Refinement of time-of-flight high-resolution neutron powder diffraction data for lueshite (Na, Ca)(Nb, Ta, Ti)O3, the natural analogue of synthetic NaNbO3, demonstrates that lueshite at room temperature (298 K) adopts an orthorhombic structure with a 2 a p × 2 a p × 4 a p superlattice described by space group Pmmn [#59: a = 7.8032(4) Å; b = 7.8193(4) Å; c = 15.6156(9) Å]. This structure is analogous to that of phase S of synthetic NaNbO3 observed at 753-783 K (480-510 °C). In common with synthetic NaNbO3, lueshite exhibits a series of phase transitions with decreasing temperature from a cubic (Pm\\bar{3}m) aristotype through tetragonal ( P4/ mbm) and orthorhombic ( Cmcm) structures. However, the further sequence of phase transitions differs in that for lueshite the series terminates with the room temperature S ( Pmmn) phase, and the R ( Pmmn or Pnma) and P ( Pbcm) phases of NaNbO3 are not observed. The appearance of the S phase in lueshite at a lower temperature, relative to that of NaNbO3, is attributable to the effects of solid solution of Ti, Ta and Ca in lueshite.

  14. Absolute determination of neutron detection efficiencies of NE213 detectors using a sup 2 sup 5 sup 2 Cf source in time-of-flight measurements

    CERN Document Server

    Schmidt, D

    2001-01-01

    Neutron detection efficiencies of NE213 scintillation detectors were determined by comparison of the measured neutron time-of-flight spectrum of a sup 2 sup 5 sup 2 Cf source deposited in a parallel-plate, low-mass ionization chamber with its reference neutron energy distribution. Measurement conditions and parameters were systematically varied to study their influence on the efficiencies obtained. The efficiencies derived from the measurement were compared with well-established efficiencies of the detectors used. These efficiencies were calculated with a Monte Carlo code and corrected after comparison with a proton recoil telescope in neutron fluence measurements. Details of the measurement and the data analysis including the corrections needed are discussed.

  15. 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

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

    Science.gov (United States)

    Birch, J.; Buffet, J.-C.; Clergeau, J.-F.; Correa, J.; van Esch, P.; Ferraton, M.; Guerard, B.; Halbwachs, J.; Hall-Wilton, R.; Hultman, L.; Höglund, C.; Khaplanov, A.; Koza, M.; Piscitelli, F.; Zbiri, M.

    2014-07-01

    A neutron detector concept based on solid layers of boron carbide enriched in 10B has been in development for the last few years as an alternative for 3He by collaboration between the ILL, ESS and Linköping University. This Multi-Grid detector uses layers of aluminum substrates coated with 10B4C 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 3He detectors of IN6 at ILL. The 10B detector has an active area of 32 x 48cm2. 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 3He 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.

  17. 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

  18. 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.)

  19. Redetermination of the structure of the 80 K superconductor YBa2Cu4O8 by time-of-flight neutron powder diffraction

    International Nuclear Information System (INIS)

    Lightfoot, P.; Pei Shiyou; Jorgensen, J.D.; Yamada, Y.; Matsumoto, T.; Izumi, F.; Kodama, Y.

    1991-01-01

    M r =745.77, orthorhombic, Ammm, a=3.8402 (1), b=3.8708 (1), c=27.2309 (3) A, V=404.8 A 3 , D x =6.119 g cm -3 , Z=2, T=295 K, 912 reflections included, R wp =5.62%, R exp =3.34%. Rietveld analysis of high-resolution time-of-flight powder neutron diffraction data has been used to redetermine the structure of the 80 K superconductor YBa 2 Cu 4 O 8 (the '124 phase'). The essential features of the structure previously reported have been confirmed. This study improves upon the precision of the previously reported structural parameters, obtained by powder neutron diffraction. The compound is stoichiometric, with no occupancy of the O(5) inter-chain site. (orig.)

  20. 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.

  1. 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

  2. Ion temperature measurements of indirect-drive implosions with the neutron time-of-flight detector on SG-III laser facility

    Science.gov (United States)

    Chen, Zhongjing; Zhang, Xing; Pu, Yudong; Yan, Ji; Huang, Tianxuan; Jiang, Wei; Yu, Bo; Chen, Bolun; Tang, Qi; Song, Zifeng; Chen, Jiabin; Zhan, Xiayu; Liu, Zhongjie; Xie, Xufei; Jiang, Shaoen; Liu, Shenye

    2018-02-01

    The accuracy of the determination of the burn-averaged ion temperature of inertial confinement fusion implosions depends on the unfold process, including deconvolution and convolution methods, and the function, i.e., the detector response, used to fit the signals measured by neutron time-of-flight (nToF) detectors. The function given by Murphy et al. [Rev. Sci. Instrum. 68(1), 610-613 (1997)] has been widely used in Nova, Omega, and NIF. There are two components, i.e., fast and slow, and the contribution of scattered neutrons has not been dedicatedly considered. In this work, a new function, based on Murphy's function has been employed to unfold nToF signals. The contribution of scattered neutrons is easily included by the convolution of a Gaussian response function and an exponential decay. The ion temperature is measured by nToF with the new function. Good agreement with the ion temperature determined by the deconvolution method has been achieved.

  3. Design and performance analyses of the new time-of-flight smaller-angle neutron scattering instrument at J-PARC

    International Nuclear Information System (INIS)

    Shinohara, Takenao; Takata, Shin-ichi; Suzuki, Jun-ichi; Oku, Takayuki; Suzuya, Kentaro; Aizawa, Kazuya; Arai, Masatoshi; Otomo, Toshiya; Sugiyama, Masaaki

    2009-01-01

    The new time-of-flight smaller-angle neutron scattering (TOF-SANS) instrument HI-SANS is projected to be built in the Materials and Life Science Facility (MLF) of Japan Proton Accelerator Research Complex (J-PARC). The target of the HI-SANS is to study microstructures and hierarchical structures of nano-meter sized materials and their complexes. For the simultaneous collection of scattering data in the wide q range (∼3x10 -3 -1 ) with good q-resolution and high efficiency, this instrument is designed to use large area detectors and broad wavelength bandwidth within the first frame. For the high-quality beam transport and the efficacious utilization of pulsed neutrons, the state of the art neutron optics is installed. Moreover, a focusing device based on sextupole magnets is adopted in the TOF-SANS for the first time to make accessible minimum q value (q min ) lower with high q resolution. The design optimization and performance analyses of the HI-SANS have been performed by Monte Carlo simulations.

  4. An in situ time-of-flight neutron powder diffraction study of the humidity-induced phase transition in sodium monothiophosphate

    International Nuclear Information System (INIS)

    Takas, Nathan J.; Aitken, Jennifer A.

    2007-01-01

    Anhydrous β-Na 3 PO 3 S, obtained by rapid cooling, has been observed to convert to the more thermodynamically stable, anhydrous α-Na 3 PO 3 S upon exposure to a humid atmosphere. Though water plays a critical role in this polymorphic transformation, it is absent in both the initial and final materials. In situ time-of-flight neutron powder diffraction was used to track the progress of this transition as a function of time. Diffraction data were acquired using the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory. An empirical whole pattern fitting method was used to determine the polymorphic phase composition over time. The resulting data were evaluated using several solid-state kinetic models. The kinetics of this transition has been determined to be best described by either one- or two-dimensional diffusion. The significance of these models with respect to the physical phenomenon is discussed. - Graphical abstract: Anhydrous β-Na 3 PO 3 S has been observed to convert to anhydrous α-Na 3 PO 3 S upon exposure to a humid atmosphere. In situ neutron powder diffraction was used to monitor the transition. A whole pattern fitting method was used to determine the phase composition, as a function of time. The data were evaluated using several solid-state kinetic models

  5. 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

  6. 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.

  7. Measurement of Fission Neutron Spectrum and Multiplicity using a Gamma Tag Double Time-of-flight Setup

    Science.gov (United States)

    Blain, E.; Daskalakis, A.; Danon, Y.

    2014-05-01

    Recent efforts have been made to improve the prompt fission neutron spectrum and nu-bar measurements for Uranium and Plutonium isotopes particularly in the keV region. A system has been designed at Rensselaer Polytechnic Institute (RPI) utilizing an array of EJ-301 liquid scintillators as well as lithium glass and plastic scintillators to experimentally determine these values. An array of BaF2 detectors was recently obtained from Oak Ridge National Laboratory to be used in conjunction with the neutron detectors. The system uses a novel gamma tagging method for fission which can offer an improvement over conventional fission chambers due to increased sample mass. A coincidence requirement on the gamma detectors from prompt fission gammas is used as the fission tag for the system as opposed to fission fragments in a conventional fission chamber. The system utilizes pulse digitization using Acqiris 8 bit digitizer boards which allow for gamma/neutron pulse height discrimination on the liquid scintillators during post processing. Additionally, a 252Cf fission chamber was designed and constructed at RPI which allowed for optimization and testing of the system without the need for an external neutron source. The characteristics of the gamma tagging method such as false detection rate and detection efficiency were determined using this fission chamber and verified using MCNP Polimi modeling. Prompt fission neutron spectrum data has been taken using the fission chamber focusing on the minimum detectable neutron energy for each of the various detectors. Plastic scintillators were found to offer a significant improvement over traditional liquid scintillators allowing energy measurements down to 50 keV. Background was also characterized for all detectors and will be discussed.

  8. 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.

  9. A novel method for modeling the neutron time of flight (nTOF) detector response in current mode to inertial confinement fusion experiments.

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Alan J. [University of New Mexico, Albuquerque, NM; Cooper, Gary Wayne [University of New Mexico, Albuquerque, NM; Ruiz, Carlos L.; Chandler, Gordon Andrew; Fehl, David Lee; Hahn, Kelly Denise; Leeper, Ramon Joe; Smelser, Ruth Marie; Torres, Jose A.

    2013-09-01

    There are several machines in this country that produce short bursts of neutrons for various applications. A few examples are the Zmachine, operated by Sandia National Laboratories in Albuquerque, NM; the OMEGA Laser Facility at the University of Rochester in Rochester, NY; and the National Ignition Facility (NIF) operated by the Department of Energy at Lawrence Livermore National Laboratory in Livermore, California. They all incorporate neutron time of flight (nTOF) detectors which measure neutron yield, and the shapes of the waveforms from these detectors contain germane information about the plasma conditions that produce the neutrons. However, the signals can also be %E2%80%9Cclouded%E2%80%9D by a certain fraction of neutrons that scatter off structural components and also arrive at the detectors, thereby making analysis of the plasma conditions more difficult. These detectors operate in current mode - i.e., they have no discrimination, and all the photomultiplier anode charges are integrated rather than counted individually as they are in single event counting. Up to now, there has not been a method for modeling an nTOF detector operating in current mode. MCNPPoliMiwas developed in 2002 to simulate neutron and gammaray detection in a plastic scintillator, which produces a collision data output table about each neutron and photon interaction occurring within the scintillator; however, the postprocessing code which accompanies MCNPPoliMi assumes a detector operating in singleevent counting mode and not current mode. Therefore, the idea for this work had been born: could a new postprocessing code be written to simulate an nTOF detector operating in current mode? And if so, could this process be used to address such issues as the impact of neutron scattering on the primary signal? Also, could it possibly even identify sources of scattering (i.e., structural materials) that

  10. 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)

  11. Expanding Lorentz and spectrum corrections to large volumes of reciprocal space for single-crystal time-of-flight neutron diffraction.

    Science.gov (United States)

    Michels-Clark, Tara M; Savici, Andrei T; Lynch, Vickie E; Wang, Xiaoping; Hoffmann, Christina M

    2016-04-01

    Evidence is mounting that potentially exploitable properties of technologically and chemically interesting crystalline materials are often attributable to local structure effects, which can be observed as modulated diffuse scattering (mDS) next to Bragg diffraction (BD). BD forms a regular sparse grid of intense discrete points in reciprocal space. Traditionally, the intensity of each Bragg peak is extracted by integration of each individual reflection first, followed by application of the required corrections. In contrast, mDS is weak and covers expansive volumes of reciprocal space close to, or between, Bragg reflections. For a representative measurement of the diffuse scattering, multiple sample orientations are generally required, where many points in reciprocal space are measured multiple times and the resulting data are combined. The common post-integration data reduction method is not optimal with regard to counting statistics. A general and inclusive data processing method is needed. In this contribution, a comprehensive data analysis approach is introduced to correct and merge the full volume of scattering data in a single step, while correctly accounting for the statistical weight of the individual measurements. Development of this new approach required the exploration of a data treatment and correction protocol that includes the entire collected reciprocal space volume, using neutron time-of-flight or wavelength-resolved data collected at TOPAZ at the Spallation Neutron Source at Oak Ridge National Laboratory.

  12. BRISP, a new small-angle time-of-flight neutron spectrometer to study collective dynamics in disordered matter

    Directory of Open Access Journals (Sweden)

    A.Orecchini

    2008-03-01

    Full Text Available An outline is given of the new neutron Brillouin Spectrometer BRISP which was installed during the last years and recently became fully operational at the Institute Laue-Langevin in Grenoble (France. The main technical features are described and some of the first experimental results are presented, demonstrating the present capabilities of this new-type inelastic small-angle spectrometer. Future upgrades are foreseen and expected to further improve the instrument performances.

  13. 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.

  14. 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.

  15. 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.

  16. Glycine zinc sulfate pentahydrate: redetermination at 10 K from time-of-flight neutron Laue diffraction

    Directory of Open Access Journals (Sweden)

    A. Dominic Fortes

    2016-10-01

    Full Text Available Single crystals of glycine zinc sulfate pentahydrate [systematic name: hexaaquazinc tetraaquadiglycinezinc bis(sulfate], [Zn(H2O6][Zn(C2H5NO22(H2O4](SO42, have been grown by isothermal evaporation from aqueous solution at room temperature and characterized by single-crystal neutron diffraction. The unit cell contains two unique ZnO6 octahedra on sites of symmetry -1 and two SO4 tetrahedra with site symmetry 1; the octahedra comprise one [tetraaqua-diglycine zinc]2+ ion (centred on one Zn atom and one [hexaaquazinc]2+ ion (centred on the other Zn atom; the glycine zwitterion, NH3+CH2COO−, adopts a monodentate coordination to the first Zn atom. All other atoms sit on general positions of site symmetry 1. Glycine forms centrosymmetric closed cyclic dimers due to N—H...O hydrogen bonds between the amine and carboxylate groups of adjacent zwitterions and exhibits torsion angles varying from ideal planarity by no more than 1.2°, the smallest values for any known glycine zwitterion not otherwise constrained by a mirror plane. This work confirms the H-atom locations estimated in three earlier single-crystal X-ray diffraction studies with the addition of independently refined fractional coordinates and Uij parameters, which provide accurate internuclear X—H (X = N, O bond lengths and consequently a more accurate and precise depiction of the hydrogen-bond framework.

  17. Glycine zinc sulfate penta-hydrate: redetermination at 10 K from time-of-flight neutron Laue diffraction.

    Science.gov (United States)

    Fortes, A Dominic; Howard, Christopher M; Wood, Ian G; Gutmann, Matthias J

    2016-10-01

    Single crystals of glycine zinc sulfate penta-hydrate [systematic name: hexa-aqua-zinc tetra-aquadiglycinezinc bis-(sulfate)], [Zn(H 2 O) 6 ][Zn(C 2 H 5 NO 2 ) 2 (H 2 O) 4 ](SO 4 ) 2 , have been grown by isothermal evaporation from aqueous solution at room temperature and characterized by single-crystal neutron diffraction. The unit cell contains two unique ZnO 6 octa-hedra on sites of symmetry -1 and two SO 4 tetra-hedra with site symmetry 1; the octa-hedra comprise one [tetra-aqua-diglycine zinc] 2+ ion (centred on one Zn atom) and one [hexa-aqua-zinc] 2+ ion (centred on the other Zn atom); the glycine zwitterion, NH 3 + CH 2 COO - , adopts a monodentate coordination to the first Zn atom. All other atoms sit on general positions of site symmetry 1. Glycine forms centrosymmetric closed cyclic dimers due to N-H⋯O hydrogen bonds between the amine and carboxyl-ate groups of adjacent zwitterions and exhibits torsion angles varying from ideal planarity by no more than 1.2°, the smallest values for any known glycine zwitterion not otherwise constrained by a mirror plane. This work confirms the H-atom locations estimated in three earlier single-crystal X-ray diffraction studies with the addition of independently refined fractional coordinates and U ij parameters, which provide accurate inter-nuclear X -H ( X = N, O) bond lengths and consequently a more accurate and precise depiction of the hydrogen-bond framework.

  18. Application of profile fitting method to neutron time-of-flight protein single crystal diffraction data collected at the iBIX

    Science.gov (United States)

    Yano, Naomine; Yamada, Taro; Hosoya, Takaaki; Ohhara, Takashi; Tanaka, Ichiro; Kusaka, Katsuhiro

    2016-01-01

    We developed and employed a profile fitting method for the peak integration of neutron time-of-flight diffraction data collected by the IBARAKI Biological Crystal Diffractometer (iBIX) at the Japan Proton Accelerator Research Complex (J-PARC) for protein ribonuclease A and α-thrombin single crystals. In order to determine proper fitting functions, four asymmetric functions were evaluated using strong intensity peaks. A Gaussian convolved with two back-to-back exponentials was selected as the most suitable fitting function, and a profile fitting algorithm for the integration method was developed. The intensity and structure refinement data statistics of the profile fitting method were compared to those of the summation integration method. It was clearly demonstrated that the profile fitting method provides more accurate integrated intensities and model structures than the summation integration method at higher resolution shells. The integration component with the profile fitting method has already been implemented in the iBIX data processing software STARGazer and its user manual has been prepared. PMID:27905404

  19. 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.)

  20. TOFI: An isochronous time-of-flight mass spectrometer

    International Nuclear Information System (INIS)

    Wollnik, H.

    1987-01-01

    A time-of-flight mass spectrometer was constructed to measure the masses of neutron-rich recoils produced in proton-induced fragmentation reactions. This system consists of four sector magnets designed such that the overall flight time is independent of the velocity of the recoil ions and thus depends only on their mass-to-charge ratios. (orig.)

  1. 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.

  2. 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.)

  3. 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

  4. 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

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

    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

    2016-12-01

    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

  6. 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

  7. 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)

  8. Use of the generalized spherical harmonic model for describing crystallographic texture in polycrystalline NiTi shape-memory alloy with time-of-flight neutron powder diffraction data

    CERN Document Server

    Sitepu, H; Dreele, R B V

    2002-01-01

    We present a feasibility study to extract quantitative texture and precise crystal structure information of polycrystalline monoclinic NiTi shape-memory alloys from a simultaneous refinement of 52 time-of-flight neutron-diffraction patterns taken in 13 orientations in the diffractometer. The multiple-data-set capabilities and the generalized spherical harmonic texture model of the GSAS program system were employed. (orig.)

  9. 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

  10. 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.

  11. 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.)

  12. 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...

  13. Time-of-flight isochronous spectrometer

    International Nuclear Information System (INIS)

    Wouters, J.M.; Vieira, D.J.; Wollnik, H.

    1985-01-01

    This report is the second in a series of progress reports describing the design and construction of the time-of-flight isochronous (TOFI) spectrometer and its associated secondary beam line. TOFI, which is being constructed jointly by INC and MP Divisions, is designed to measure in a systematic fashion the ground-state masses of the light neutron-rich nuclei with A<70 that lie far from the valley of β stability. In the past year the authors ordered all the long-lead items necessary for construction of the spectrometer and installed the first half of the secondary beam line. Furthermore, a major portion of the control system for both the spectrometer and beam line was designed and installed. This annual report briefly summarizes the current status of the spectrometer and describes in some detail the design and installation of the first half of the transport line. For a summary of the scientific goals and overall design of the TOFI spectrometer, see the 1983 Progress at LAMPF report

  14. Study of neutron resonances of barium and copper isotopes by the time-of-flight method at low energies (0 to 15 keV)

    International Nuclear Information System (INIS)

    Chevillon-Pitollat, P.L.

    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 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 0 (J = 2) ≅ 2 S 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) [fr

  15. 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)

  16. 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...

  17. Time-of-Flight Elastic and Inelastic Neutron Scattering Studies on the Localized 4d Electron Layered Perovskite La5Mo4O16

    Science.gov (United States)

    Iida, Kazuki; Kajimoto, Ryoichi; Mizuno, Yusuke; Kamazawa, Kazuya; Inamura, Yasuhiro; Hoshikawa, Akinori; Yoshida, Yukihiko; Matsukawa, Takeshi; Ishigaki, Toru; Kawamura, Yukihiko; Ibuka, Soshi; Yokoo, Tetsuya; Itoh, Shinichi; Katsufuji, Takuro

    2017-06-01

    The magnetic structure and spin-wave excitations in the quasi-square-lattice layered perovskite compound La5Mo4O16 were studied by a combination of neutron diffraction and inelastic neutron scattering techniques using polycrystalline sample. Neutron powder diffraction refinement revealed that the magnetic structure is ferrimagnetic in the ab plane with antiferromagnetic stacking along the c-axis where the magnetic propagation vector is k = (0,0,1/2). The ordered magnetic moments are estimated to be 0.54(2)μB for Mo5+ (4d1) ions and 1.07(3)μB for Mo4+ (4d2) ions at 4 K, which are about half of the expected values. The inelastic neutron scattering results display strong easy-axis magnetic anisotropy along the c-axis due to the spin-orbit interaction in Mo ions evidenced by the spin gap at the magnetic zone center. The model Hamiltonian consisting of in-plane anisotropic exchange interactions, the interlayer exchange interaction, and easy-axis single-ion anisotropy can explain our inelastic neutron scattering data well. Strong Ising-like anisotropy and weak interlayer coupling compared with the intralayer exchange interaction can explain both the high-temperature magnetoresistance and long-time magnetization decay recently observed in La5Mo4O16.

  18. Time-of-flight Fourier Spectrometry with UCN

    Science.gov (United States)

    Kulin, G. V.; Frank, A. I.; Goryunov, S. V.; Geltenbort, P.; Jentschel, M.; Bushuev, V. A.; Lauss, B.; Schmidt-Wellenburg, Ph.; Panzarella, A.; Fuchs, Y.

    2016-09-01

    The report presents the first experience of using a time-of-flight Fourier spectrometer of ultracold neutrons (UCN). The description of the spectrometer design and first results of its testing are presented. The results of the first experiments show that the spectrometer may be used for obtaining UCN energy spectra in the energy range of 60÷200 neV with a resolution of about 5 neV. The application of TOF Fourier spectrometry technique allowed us to obtain the energy spectra from the diffraction of monochromatic ultracold neutrons on a moving grating. Lines of 0, +1 and +2 diffraction orders were simultaneously recorded, which had previously been impossible to be done by other methods. These results have made it possible to make a comparison with the recent theoretical calculations based on the dynamical theory of neutron diffraction on a moving phase grating.

  19. 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

  20. Preliminary time-of-flight neutron diffraction studies of Escherichia coli ABC transport receptor phosphate-binding protein at the Protein Crystallography Station.

    Science.gov (United States)

    Sippel, K H; Bacik, J; Quiocho, F A; Fisher, S Z

    2014-06-01

    Inorganic phosphate is an essential molecule for all known life. Organisms have developed many mechanisms to ensure an adequate supply, even in low-phosphate conditions. In prokaryotes phosphate transport is instigated by the phosphate-binding protein (PBP), the initial receptor for the ATP-binding cassette (ABC) phosphate transporter. In the crystal structure of the PBP-phosphate complex, the phosphate is completely desolvated and sequestered in a deep cleft and is bound by 13 hydrogen bonds: 12 to protein NH and OH donor groups and one to a carboxylate acceptor group. The carboxylate plays a key recognition role by accepting a phosphate hydrogen. PBP phosphate affinity is relatively consistent across a broad pH range, indicating the capacity to bind monobasic (H2PO4-) and dibasic (HPO4(2-)) phosphate; however, the mechanism by which it might accommodate the second hydrogen of monobasic phosphate is unclear. To answer this question, neutron diffraction studies were initiated. Large single crystals with a volume of 8 mm3 were grown and subjected to hydrogen/deuterium exchange. A 2.5 Å resolution data set was collected on the Protein Crystallography Station at the Los Alamos Neutron Science Center. Initial refinement of the neutron data shows significant nuclear density, and refinement is ongoing. This is the first report of a neutron study from this superfamily.

  1. Accurate and precise lattice parameters of H2O and D2O ice Ih between 1.6 and 270 K from high-resolution time-of-flight neutron powder diffraction data.

    Science.gov (United States)

    Fortes, A Dominic

    2018-04-01

    Accurate and precise lattice parameters for D 2 O and H 2 O varieties of hexagonal ice (ice Ih, space group P6 3 /mmc) have been obtained in the range 1.6 to 270 K. Precision of the lattice parameters (∼0.0002% in a and 0.0004% in c for D 2 O, 0.0008% in a and 0.0015% in c for H 2 O) is ensured by use of the time-of-flight method on one of the longest primary neutron flight-path instruments in the world, the High-Resolution Powder Diffractometer at the ISIS neutron source. These data provide a more precise description of the negative thermal expansion of the material at low temperatures than the previous synchrotron `gold standard' [Röttger et al. (1994). Acta Cryst. B50, 644-648], including the region below 10 K where the lattice parameters saturate. The volume expansivity of both isotopologues turns negative below 59-60 K, in excellent agreement with a recent dilatometry study. The axial expansivities are highly isotropic (differing by < 1% in D 2 O ice Ih). Furthermore, the c/a ratio of different D 2 O ice samples exhibit a statistically significant dispersion of ∼0.015% below 150 K that appears to depend on the thermal history of the sample, which disappears on warming above 150 K. Similarly, H 2 O ice exhibits a `kink' in the c/a ratio at ∼115 K. The most plausible explanation is a freezing-in of the molecular reorientation process on cooling and subsequent relaxation on warming.

  2. First tests of the applicability of $\\gamma$-ray imaging for background discrimination in time-of-flight neutron capture measurements

    CERN Document Server

    Magán, D L Pérez; Domingo-Pardo, C; Agramunt-Ros, J; Albiol, F; Casanovas, A; González, A; Guerrero, C; Lerendegui-Marco, J; Tarifeño-Saldivia, A

    2016-01-01

    In this work we explore for the first time the applicability of using $\\gamma$-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$_3$ 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 $^{197}$Au sample have been carried out at n\\_TOF, achieving an enhancement of a factor of 2 in the signal-to-background ratio when selecting only those events coming from the direction of the sample.

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

    International Nuclear Information System (INIS)

    Pérez Magán, D.L.; Caballero, L.; Domingo-Pardo, C.; Agramunt-Ros, J.; Albiol, F.; Casanovas, A.; González, A.; Guerrero, C.; Lerendegui-Marco, J.; Tarifeño-Saldivia, A.

    2016-01-01

    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 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 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.

  4. 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

    (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......, 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....

  5. Thin Time-Of-Flight PET project

    CERN Document Server

    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.

  6. 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.

  7. Time-of-flight mass spectrometer

    International Nuclear Information System (INIS)

    Managadze, G.G.

    1991-01-01

    A time-of-flight mass spectrometer comprises an ion source consisting of a grid assembly, a drift space with a focusing system, a reflector and a detector. The grid assembly has the shape of a ring with the internal diameter equal to that of the detector, whereas the focusing system consists of two cylinders coaxially mounted in the drift space whose diameters are equal, respectively, to the internal and the external diameter of the grid assembly of the ion source. The time-of-flight mass spectrometer is intended mainly for studying the mass composition of an inert gas, of a low-energy ion flux as well as of a plasma in a vacuum. (author)

  8. 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.

  9. 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.

  10. The TORCH time-of-flight detector

    Science.gov (United States)

    Harnew, N.; Brook, N.; Castillo García, L.; Cussans, D.; Föhl, K.; Forty, R.; Frei, C.; Gao, R.; Gys, T.; Piedigrossi, D.; Rademacker, J.; Ros Garcia, A.; van Dijk, M.

    2016-07-01

    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 m2, 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 mm2 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-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.

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

    International Nuclear Information System (INIS)

    Forsyth, V.T.; Whalley, M.A.; Mahendrasingam, A.; Fuller, W.

    1994-01-01

    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

  12. 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

  13. 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)

  14. 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.

  15. 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.)

  16. 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.

  17. 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

  18. 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.

  19. 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)

  20. A large acceptance lead-scintillator time-of-flight wall for neutral and charged particles

    CERN Document Server

    Kuznetsov, V E; Churikova, S; Girolami, B; Karapetiantz, D; Malyukin, Y; Nedorezov, V; Turinge, A; Vorobiev, Y; Abramov, V; D'Angelo, A; Moricciani, D; Nicoletti, L; Ranyuk, Y; Schärf, C

    2002-01-01

    A large acceptance lead-scintillator time-of-flight (TOF) wall has been developed to detect photons, neutrons, and charged particles produced in meson-photoproduction experiments on the proton and on the neutron. A TOF resolution of 600 ps and a position resolution of 11x18 cm sup 2 (full-width at half-maximum) have been achieved. The wall has been successfully used in eta and pi sup + photoproduction experiments as a photon and a neutron detector. This paper reports its design, calibration and performance.

  1. 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)

  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. 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)

  4. A new time-of-flight mass spectrometer

    International Nuclear Information System (INIS)

    Ching-Shen Su.

    1984-01-01

    A new time-of-flight mass spectrometer using a cylindrical mirror analyzer and a cylindrical sector analyzer to select ion energies was reported. The cylindrical sector acts as a flight path for ions also. An energy spread of +- 0.41% can be achieved. (orig.)

  5. TORCH: Time of Flight Identification with Cherenkov Radiation

    CERN Document Server

    Charles, M J

    2010-01-01

    TORCH is a time-of-flight detector concept using Cherenkov light to provide charged particle identification up to 10 GeV/$c$. The concept and design are described and performance in simulation is quantified.

  6. TORCH: Time of flight identification with Cherenkov radiation

    Science.gov (United States)

    Charles, M. J.; Forty, R.; LHCb Collaboration

    2011-05-01

    TORCH is a time-of-flight detector concept using Cherenkov light to provide charged particle identification up to 10 GeV/ c. The concept and design are described and performance in simulation is quantified.

  7. TORCH: Time of Flight Identification with Cherenkov Radiation

    CERN Document Server

    Charles, M J

    2011-01-01

    TORCH is a time-of-flight detector concept using Cherenkov light to provide charged particle identification up to 10 GeV/c. The concept and design are described and performance in simulation is quantified.

  8. 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.

  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. Sliding time of flight: sliding time of flight MR angiography using a dynamic image reconstruction method.

    Science.gov (United States)

    Choi, Joonsung; Seo, Hyunseok; Lim, Yongwan; Han, Yeji; Park, HyunWook

    2015-03-01

    To obtain three-dimensional (3D) MR angiography having high contrast between vessel and stationary background tissue, a novel technique called sliding time of flight (TOF) is proposed. The proposed method relies on the property that flow-related enhancement (FRE) is maximized at the blood-entering slice in an imaging slab. For the proposed sliding TOF, a sliding stack-of-stars sampling and a dynamic MR image reconstruction algorithm were developed. To verify the performance of the proposed method, in vivo study was performed and the results were compared with multiple overlapping thin 3D slab acquisition (MOTSA) and sliding interleaved ky (SLINKY). In MOTSA and SLINKY, the variation of FRE resulted in severe venetian blind (MOTSA) or ghost (SLINKY) artifacts, while the vessel-contrast increased as the flip angle of radiofrequency (RF) pulses increased. On the other hand, the proposed method could provide high-contrast angiograms with reduced FRE-related artifacts. The sliding TOF can provide 3D angiography without image artifacts even if high flip angle RF pulses with thick slab excitation are used. Although remains of subsampling artifacts can be present in the reconstructed images, they can be reduced by MIP operation and resolved further by regularization techniques. © 2014 Wiley Periodicals, Inc.

  11. 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

  12. Ion focusing procedures in time-of-flight mass spectrometry

    International Nuclear Information System (INIS)

    Ioanoviciu, D.

    1999-01-01

    The intact ionisation of big molecules by soft ionisation methods, as matrix assisted laser desorption ionisation and fast atom bombardment, paved the way of mass spectrometry to very high mass ranges (approaching the million of Daltons). This was possible by the branch of time-of-flight mass spectrometry. However, time-of-flight mass spectrometry is lagging far behind other branches as mass resolution, the highest value recently reported being of 45 000. This is a well-documented reason why in time-of-flight mass spectrometry ion packet focusing remains a hot problem. The space focusing in time in linear drift time-of-flight mass spectrometers is discussed including first and second order focusing conditions, second and third order aberrations. The resolution of such instruments is determined and compared to the real performances of some constructed instruments. The focusing conditions for delayed ion extraction are presented and examples given for presently used time of flight mass spectrometers with matrix assisted laser desorption ionisation sources. The post source ionisation method and its effect on the spectrometer mass scale are detailed. The ion energy focusing in time to first and second order in single and double staged electric field mirrors is studied. An explanation is given why time-of-flight mass spectrometers including mirrors are able of much higher resolutions than those based on flight on drift spaces only. The major interest in careful velocity focusing is expressed by the use of the delayed extraction in time of flight mass spectrometers, which include reflectrons. Again, the focusing conditions and aberrations are detailed. A special attention is focused on the possibility to obtain high order velocity focusing for ions created on the surface of hyperbolic electrodes. Also the focusing methods with perfect time focusing by hyperbolic traps and by the so-called 'curved field' were reviewed, especially as means to focus fragment ions from

  13. 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.

  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. 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

  17. Status of the TORCH time-of-flight detector

    Science.gov (United States)

    Harnew, N.; Brook, N. H.; Castillo García, L.; Cussans, D.; van Dijk, M. W. U.; Föhl, K.; Forty, R.; Frei, C.; Gao, R.; Gys, T.; Hancock, T. H.; Piedigrossi, D.; Rademacker, J.; Ros García., A.

    2017-11-01

    The TORCH time-of-flight detector is designed for large-area coverage, up to 30 m2, to provide particle identification between 2-10 GeV/c momentum over a flight distance of 10 m. The arrival times from Cherenkov photons produced within a quartz radiator plate of 10 mm thickness are combined to achieve a 15 ps time-of-flight resolution per incident particle. Micro-Channel Plate Photomultiplier Tube (MCP-PMT) detectors of 53 × 53 mm2 active area have been developed with industrial partners for the TORCH application. The MCP-PMT is read out using charge division to give a 128 × 8 effective granularity. Laboratory results of development MCP-PMTs will be described, and testbeam studies using a small-scale TORCH prototype module will be presented.

  18. Time-of-flight estimation based on covariance models

    NARCIS (Netherlands)

    van der Heijden, Ferdinand; Tuquerres, G.; Regtien, Paulus P.L.

    We address the problem of estimating the time-of-flight (ToF) of a waveform that is disturbed heavily by additional reflections from nearby objects. These additional reflections cause interference patterns that are difficult to predict. The introduction of a model for the reflection in terms of a

  19. 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 co...

  20. Suborbital Transport Mapping with Time Of Flight (TOF)

    Science.gov (United States)

    Harris, T. H. S.

    2015-09-01

    The suborbital paradigm is examined through proxies of orbital elements eccentricity e and semi-major axis a. Time Of Flight (TOF) domain and its analytic utility emerge. Strewn/ejecta relation to impact location, etc., are examined from TOF domain.

  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)

    We report on a phase-sensitive probe absorption technique with high sensitivity, 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. We demonstrate the ...

  3. 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.

  4. The time-of-flight isochronous (TOFI) spectrometer for direct mass measurements of exotic light nuclei

    International Nuclear Information System (INIS)

    Wouters, J.M.; Vieira, D.J.; Butler, G.W.; Wollnik, H.; Kraus, R.H. Jr.; Vaziri, K.

    1987-01-01

    A new type of time-of-flight recoil spectrometer designed to measure the masses of neutron-rich light nuclei has recently been completed at LAMPF. The spectrometer relies on an isochronous design that directly correlates an ion's time-of-flight through the spectrometer with its mass-to-charge ratio. Additional measurements of the ion's velocity and energy enable the charge state of the recoil to be uniquely defined and thus permit precision mass measurements given sufficient statistics. The performance of the spectrometer has been investigated in both-off line (using alpha sources) and on-line tests. The design resolution of ΔM/M=1/2000 (fwhm) has been achieved. Initial performance results of the spectrometer are described with emphasis placed on the techniques used to achieve the overall high mass resolution and large solid angle/momentum acceptance. (orig.)

  5. 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.)

  6. 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.)

  7. TORCH: a novel time-of-flight detector concept

    CERN Document Server

    Forty, R

    2009-01-01

    A time-of-flight detector concept is described, named TORCH, that has been developed as a possible solution to the identification of low momentum hadrons in the proposed upgrade of the LHCb spectrometer. The detector consists of a quartz plate placed perpendicular to the beam axis, with photon detectors arranged around the periphery of the plate (outside the acceptance of the spectrometer). Cherenkov light produced by a charged particle traversing the plate is trapped within it by total internal reflection, and then focused onto the photodetectors. A combination of the precise measurement of the arrival time of the photons, and their position, should allow the time-of-flight of the particle to be reconstructed with a precision of ~10 ps, sufficient to satisfy the physics requirements. The R&D that would be necessary to realize this concept is outlined.

  8. TORCH-a Cherenkov based time-of-flight detector

    Science.gov (United States)

    van Dijk, M. W. U.; Brook, N. H.; Castillo García, L.; Cowie, E. N.; Cussans, D.; D`Ambrosio, C.; Fopma, J.; Forty, R.; Frei, C.; Gao, R.; Gys, T.; Harnew, N.; Keri, T.; Piedigrossi, D.

    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.

  9. TORCH - a Cherenkov-based time-of-flight detector

    CERN Document Server

    van Dijk, M W U; Cowie, E N; Cussans, D; D' Ambrosio, C; Forty, R; Frei, C; Gys, T; Piedigrossi, D; Castillo Garcia, L; Fopma, J; Gao, R; Harnew, N; Keri, T

    2014-01-01

    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, where they are 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 for 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.

  10. Comparison of statistical accuracy between the 'direct' and the 'reverse' time-of-flight techniques

    International Nuclear Information System (INIS)

    Kudryashev, V.A.; Hartung, U.

    1992-01-01

    The statistical accuracy between two neutron time-of-flight (TOF) diffraction techniques, the classic 'forward' TOF and the 'reverse' TOF technique, are compared. This problem is discussed in dependence on the diffracted spectrum, the background and some special device parameters. In general the 'reverse' TOF method yields better statistics in the spectrum's range above the medium channel content; by the classic TOF method this is achieved in the lower area. For that reason, the reverse TOF measurement is especially recommendable for structure problems and the forward TOF technique for studying the background (e.g. the inelastic scattered portion). (orig.)

  11. 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.

  12. 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

  13. 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

  14. Time of flight mass spectrometry of pharmaceutical systems

    OpenAIRE

    Armitage Nolan, Jennifer Claire

    2013-01-01

    Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a widely used surface chemical analysis technique that is traditionally employed to characterise the first few molecular layers of a material interface. The ability of this technique to accurately reflect the surface chemistry of polymers, biomaterials and many other solid materials is well documented. However, the majority of research that utilises this technique is based upon a qualitative rather than quantitative assessment of th...

  15. Development of a correction method for the time-of-flight prompt gamma-ray analysis

    Science.gov (United States)

    Huang, M.; Toh, Y.; Ebihara, M.; Kimura, A.; Nakamura, S.

    2017-03-01

    A new analytical technique, time-of-flight prompt gamma-ray analysis, has been developed at the Japan Proton Accelerator Research Complex. In order to apply it to accurate elemental analysis, a set of Fe and Au reference samples were measured to examine the several factors which affect the number of detected events. It was found that major contributing factors included attenuations of neutrons and gamma rays in the sample, live-time fraction and signal pile-up correction. A simulation model was built for the estimation of neutron and gamma-ray attenuations. A simple empirical formula was proposed to calculate the signal pile-up correction factor. The whole correction method has proven to be accurate and reliable.

  16. 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.

  17. 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)

  18. 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

  19. Time-of-flight mass spectrometry and its application

    International Nuclear Information System (INIS)

    Mamyrin, B.A.

    1979-01-01

    Discussed are an applicabilities of time-of-flight mass spectrometers in various fields of science and technology. Two types of such spectrometers are considered. Double-section electrostatic reflective fields are used in the first scheme to focus ion beams, this permits to obtain the resolution of the device of about several thousands. Such mass spectrometers called mass reflectrons are successfully used to analyze heavy molecules (ReBr 3 ) and organic compounds. Besides, mass reflectrons are used for an operative control of nickel converter production. A strong magnetic focusing of ion packets and resonance between ion cyclotron frequency and modulator frequency are provided in the second scheme of time-of-flight mass spectrometer. Such magnetic-resonance mass spectrometers (MRMS) have a high resolution (from tens of thousands to hundreds of thousands) at a relatively short length of ion flight (about 1 m). Discussed are the results obtained with MRMS while studying isotopy of natural helium and gas diffusion into crystals at superlow temperatures. Comparative data of the both types of the spectrometers are presented

  20. 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)

  1. 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

  2. Time-of-flight Extreme Environment Diffractometer at the Helmholtz-Zentrum Berlin

    Science.gov (United States)

    Prokhnenko, Oleksandr; Stein, Wolf-Dieter; Bleif, Hans-Jürgen; Fromme, Michael; Bartkowiak, Maciej; Wilpert, Thomas

    2015-03-01

    The Extreme Environment Diffractometer (EXED) is a new neutron time-of-flight instrument at the BER II research reactor at the Helmholtz-Zentrum Berlin, Germany. Although EXED is a special-purpose instrument, its early construction made it available for users as a general-purpose diffractometer. In this respect, EXED became one of the rare examples, where the performance of a time-of-flight diffractometer at a continuous source can be characterized. In this paper, we report on the design and performance of EXED with an emphasis on the unique instrument capabilities. The latter comprise variable wavelength resolution and wavelength band, control of the incoming beam divergence, the possibility to change the angular positions of detectors and their distance to the sample, and use of event recording and offline histogramming. These features combined make EXED easily tunable to the requirements of a particular problem, from conventional diffraction to small angle neutron scattering. The instrument performance is demonstrated by several reference measurements and user experiments.

  3. 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.

  4. Bakelite chambers for time-of-flight measurements

    CERN Document Server

    Cwiok, M; Górski, M; Królikowski, J

    1999-01-01

    We report on the search of composite organic materials with the volume resistivity ranging from 10 sup 8 to 10 sup 1 sup 1 OMEGA cm. Materials having resistivity in this range may be used for electrodes of thin gap Parallel Plate Avalanche Chambers. Gas detectors of such structure and operated at increased gas pressure allow, potentially, a sub-nanosecond time resolution. Using bakelite-like material with electrical properties well tuned during manufacturing opens the possibility to overcome limitations related to the semi-conductive glass employed usually for ultrafast gas detectors of parallel plate structure for time-of-flight technique.

  5. High resolution time-of-flight electronics system

    International Nuclear Information System (INIS)

    Grund, J.E.

    1979-10-01

    A new electronics system for time-of-flight measurements has been developed to meet the performance requirements of the Mark II Detector for operation at the PEP Storage Ring of the Stanford Linear Accelerator Center. This system incorporated high resolution time measurements with the capability to correct systemic errors from the scintillator and photomultiplier tubes. The correction technique involves making three measurements on each photomultiplier signal every storage ring beam interaction. Two timing measurements are made relative to the beam interaction time with different discriminator threshold level settings. The charge integral of each photomultiplier pulse is also recorded

  6. 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.

  7. 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

  8. 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)

  9. 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...

  10. 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.

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

    Directory of Open Access Journals (Sweden)

    Guerrero C.

    2017-01-01

    Full Text Available 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.

  12. IceBridge Sigma Space Prototype L0 Raw Time-of-Flight Data

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA IceBridge Sigma Space Prototype L0 Raw Time-of-Flight Data set (ILSSP0) contains time-of-flight data captured over Antarctica using the Sigma Space Photon...

  13. IceBridge Sigma Space Prototype L0 Raw Time-of-Flight Data, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA IceBridge Sigma Space Prototype L0 Raw Time-of-Flight Data set (ILSSP0) contains time-of-flight data captured over Antarctica using the Sigma Space Photon...

  14. 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....

  15. 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.

  16. 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

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

    Science.gov (United States)

    Rohrbacher, Andreas; Continetti, Robert E.

    2001-08-01

    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.

  18. 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

  19. The time-of-flight system for CLAS

    CERN Document Server

    Smith, E S; Distelbrink, J; Eckhause, M; Egiyan, H; Elouadrhiri, L; Ficenec, J; Guidal, M; Hancock, A D; Hersman, F W; Holtrop, M; Jenkins, D A; Kim, W; Loukachine, K; MacArthur, K; Marchand, C; Mecking, B; Mutchler, G S; Schutt, D; Smith, L C; Smith, T P; Taylor, S; Tung, T Y; Weisenberger, A; Welsh, R E

    1999-01-01

    The time of flight system for the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility is described. The system, covering an area of 206 m sup 2 , is composed of scintillation counters 5.08 cm thick, 15 and 22 cm wide, and lengths which vary from 32 cm at the most forward angle to 450 cm at larger angles. All of the components of the system have been designed to optimize the time resolution. Event timing, achieved by leading-edge discrimination with time-walk correction, has been measured with cosmic rays, a laser pulser, and known particle interactions. The intrinsic time resolution varies from about 80 ps for the short counters to 160 ps for the longer counters. Reconstruction of interacting particles during the first period of operation yields an average time resolution for electrons of 163 ps. (author)

  20. Highly charged ion based time of flight emission microscope

    Science.gov (United States)

    Barnes, Alan V.; Schenkel, Thomas; Hamza, Alex V.; Schneider, Dieter H.; Doyle, Barney

    2001-01-01

    A highly charged ion based time-of-flight emission microscope has been designed, which improves the surface sensitivity of static SIMS measurements because of the higher ionization probability of highly charged ions. Slow, highly charged ions are produced in an electron beam ion trap and are directed to the sample surface. The sputtered secondary ions and electrons pass through a specially designed objective lens to a microchannel plate detector. This new instrument permits high surface sensitivity (10.sup.10 atoms/cm.sup.2), high spatial resolution (100 nm), and chemical structural information due to the high molecular ion yields. The high secondary ion yield permits coincidence counting, which can be used to enhance determination of chemical and topological structure and to correlate specific molecular species.

  1. Time Of Flight Detectors: From phototubes to SiPM

    Energy Technology Data Exchange (ETDEWEB)

    Laurenti, G. [INFN of Bologna, Viale B.Pichat 4/2, 40127 Bologna (Italy); Levi, G.; Foschi, E.; Guandalini, C.; Quadrani, L. [Department of Physics and INFN, Viale B.Pichat 4/2, 40127 Bologna (Italy); Sbarra, C. [Department of Physics and INFN, Viale B.Pichat 4/2, 40127 Bologna (Italy); Enrico Fermi Research Center, Via Panisperna 89, 06100 Roma (Italy)], E-mail: cristina.sbarra@bo.infn.it; Zuffa, M. [INFN of Bologna, Viale B.Pichat 4/2, 40127 Bologna (Italy)

    2008-04-01

    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.

  2. Small-sized time-of-flight mass spectrometer

    International Nuclear Information System (INIS)

    Belov, A.S.

    1985-01-01

    A time-of-flight mass spectrometer with beam particle ionization by electron impact developed for the measurement of pulsed hydrogen beam parameters, is described. Duration of electron beam current pulses in the mass-spectrometer ionizer is varied within the 2-20 μs, interval electron pulse current is 0.6 mA, electron energy is 250 eV. Time resolution of the mass spectrometer is determined by the period of electron beam current pulse repetition and equals 40 μs. The ion drift range is 16 cm. Mass resolution ΔM/M=1/5 is sufficient for the determination of hydrogen beam composition. The mass spectrometer has 100% transparency in the direction of molecular beam particle movement. In this direction the mass spectrometer size is 7 cm

  3. The time-of-flight system for CLAS

    Energy Technology Data Exchange (ETDEWEB)

    Smith, E.S. E-mail: elton@jlab.org; Carstens, T.; Distelbrink, J.; Eckhause, M.; Egiyan, H.; Elouadrhiri, L.; Ficenec, J.; Guidal, M.; Hancock, A.D.; Hersman, F.W.; Holtrop, M.; Jenkins, D.A.; Kim, W.; Loukachine, K.; MacArthur, K.; Marchand, C.; Mecking, B.; Mutchler, G.; Schutt, D.; Smith, L.C.; Smith, T.P.; Taylor, S.; Tung, T.Y.; Weisenberger, A.; Welsh, R.E

    1999-08-11

    The time of flight system for the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility is described. The system, covering an area of 206 m{sup 2}, is composed of scintillation counters 5.08 cm thick, 15 and 22 cm wide, and lengths which vary from 32 cm at the most forward angle to 450 cm at larger angles. All of the components of the system have been designed to optimize the time resolution. Event timing, achieved by leading-edge discrimination with time-walk correction, has been measured with cosmic rays, a laser pulser, and known particle interactions. The intrinsic time resolution varies from about 80 ps for the short counters to 160 ps for the longer counters. Reconstruction of interacting particles during the first period of operation yields an average time resolution for electrons of 163 ps. (author)

  4. 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

  5. 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)

  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. 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.

  8. Neutron fluxes and spectra of the neutron guide tubes in the upgraded JRR-3

    International Nuclear Information System (INIS)

    Kawabata, Y.; Suzuki, M.; Tsuruno, A.; Onishi, N.

    1992-01-01

    A cold neutron source with two thermal and three cold neutron guide tubes has been installed in the upgraded JRR-3. Neutron fluxes, time-of-flight spectra and the gain of the cold neutron source were measured at the end of the neutron guide tubes. The neutron beam distributions were found by neutron radiography films. (orig.)

  9. Electronics for a Picosecond Time-of-flight Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, Andrew Gerhart [University of Texas, Arlington; Rijssenbeek, Michael [Stony Brook

    2014-11-03

    TITLE: Electronics for a Picosecond Time-of-flight Measurement ABSTRACT: Time-of-flight (TOF) detectors have historically been used as part of the particle identification capability of multi-purpose particle physics detectors. An accurate time measurement, combined with a momentum measurement based on the curvature of the track in a magnetic field, is often sufficient to determine the particle's mass, and thus its identity. Such detectors typically have measured the particle flight time extremely precisely, with an uncertainty of one hundred trillionths of a second (also referred to as 100 picoseconds). To put this in perspective it would be like counting all the people on the Earth and getting it right within 1 person! Another use of TOFs is to measure the vertex of the event, which is the location along the beam line where the incoming particles (typically protons) collide. This vertex positon is a well measured quantity for events where the protons collide “head on” as the outgoing particles produced when you blast the proton apart can be used to trace back to a vertex point from which they originated. More frequently the protons just strike a glancing blow and remain intact—in this case they are nearly parallel to the beam and you cannot tell their vertex without this ability to precisely measure the time of flight of the protons. Occasionally both happen in the same event, that is, a central system and two protons are produced. But are they from the same collision, or just a boring background where more than one collision in the same bunch crossing conspire to fake the signal of interest? That’s where the timing of the protons comes into play. The main idea is to measure the time it takes for the two protons to reach TOF detectors positioned equidistant from the center of the main detector. If the vertex is displaced to one side than that detector will measure a shorter time while the other side detector will measure a correspondingly longer time

  10. Possible cause of anomalies in storage time of ultra-cold neutrons

    International Nuclear Information System (INIS)

    Frank, I.M.

    Various possible causes of anomalies in the storage time of ultracold neutrons are considered. It is concluded that anomalies in extreme ultracold neutrons, at least partially, are related to surface waves and that this problem requires more detailed theoretical study

  11. 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.

  12. 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.

  13. 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

    2018-02-16

    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.

  14. 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.

  15. 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.

  16. 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...

  17. Recent developments in time-of-flight PET

    Energy Technology Data Exchange (ETDEWEB)

    Vandenberghe, S.; Mikhaylova, E.; D’Hoe, E.; Mollet, P. [ELIS-IMINDS-Medical IT-IBITECH Ghent University, De Pintelaan 185, Blok B, Gent, 9000 (Belgium); Karp, J. S. [Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania (United States)

    2016-02-16

    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. Separation of VX, RVX and GB Enantiomers Using Liquid ChromatographyTime-of-Flight Mass Spectrometry

    Science.gov (United States)

    2016-02-01

    and GB Enantiomers Using Liquid Chromatography– Time-of-Flight Mass Spectrometry 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...used for liquid chromatography–time-of-flight mass spectrometry analysis. For large-scale separation and quantitation, the UV absorbance at 210 nm (with...RVX, AND GB ENANTIOMERS USING LIQUID CHROMATOGRAPHY–TIME-OF-FLIGHT MASS SPECTROMETRY 1. INTRODUCTION Tetra-coordinate pentavalent

  19. 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.

  20. In-flight neutron spectra as an ICF diagnostic for implosion asymmetries

    Science.gov (United States)

    Cerjan, C.; Sayre, D. B.; Sepke, S. M.

    2018-02-01

    The yield and spectral shape of the neutrons produced during in-flight reactions provide stringent constraints upon the symmetry of the fully compressed fuel conditions in Inertial Confinement Fusion implosions. Neutron production from a specific deuterium gas-filled implosion is simulated in detail and compared with the experimental neutron spectra along two lines-of-sight. An approximate reactivity formulation is applied to obtain further insight into the underlying fuel configuration. This analysis suggests that the differences observed in the observed spectra correspond to angularly dependent triton velocity distributions created by an asymmetric plasma configuration.

  1. 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...

  2. 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.

  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. 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

  5. Neutron-induced single event upsets in static RAMs observed at 10 KM flight altitude

    Science.gov (United States)

    Olsen, J.; Becher, P. E.; Fynbo, P. B.; Raaby, P.; Schultz, J.

    1993-04-01

    Neutron induced single event upsets (SEUs) in static memory devices (SRAMs) have so far been seen only in laboratory environments. We report observations of 14 neutron induced SEUs at commercial aircraft flight altitudes. The observed SEU rate at 10 km flight altitude based on exposure of 160 standard 256 Kbit CMOS SRAMs is 4.8 x 10 exp -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.

  6. 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)

  7. Time-of-flight atom probe measurements on Ni3Al and Co3W

    NARCIS (Netherlands)

    Soer, W.A.; Bronsveld, P.M.; Hosson, J.Th.M. De

    2003-01-01

    In this study, a VG FIM100 was taken into operation, consisting of a field-ion microscope (FIM), a time-of-flight atom probe (TOFAP) and an imaging atom probe. A tungsten specimen was used to calibrate the conversion of flight times to m/n values. The resulting relative mass resolution of the TOFAP

  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. 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.

  10. 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...

  11. A new high resolution time-of-flight mass spectrometer with gridless reflector

    International Nuclear Information System (INIS)

    Bhowmick, A.; Korgaonkar, A.V.; Carvalho, W.C.J.; Yakhmi, J.V.; Sahni, V.C.

    2004-01-01

    High resolution in time-of-flight mass spectrometers essentially depends upon the capacity of the machine to control the initial spatial and energy distributions of the ions from the source or of any particular ionization process. In the present scenario, high resolution time-of-flight mass spectrometers are becoming more and more essential for rapid mass analysis of fairly large molecules or species e.g. large biomolecules, proteins, drugs, atomic clusters, etc. Simple mass measurements of atomic clusters have revealed major fundamental information about their electronic and geometric structures. Newer designs of time-of-flight mass spectrometers have high resolution, adaptability to multiple ionization techniques, high sensitivity, capability of addressing comparatively slower physical events etc. are, therefore, being reported regularly. A newly developed time-of-flight mass spectrometer is described

  12. 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

  13. 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

  14. 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...

  15. Climate effects on late-season flight times of Massachusetts butterflies

    Science.gov (United States)

    Zipf, L.; Williams, E. H.; Primack, R. B.; Stichter, S.

    2017-09-01

    Although the responses of living organisms to climate change are being widely investigated, little attention has been given to such effects late in the growing season. We studied the late-season flight times of 20 species of butterflies in a geographically limited region, the state of Massachusetts in the USA, by examining change in dates of flight over a 22-year period and in response to average monthly temperature and precipitation. By analyzing the last 10% of each year's observations reported by observers of the Massachusetts Butterfly Club, we found that seven species remain in flight significantly later into the fall than they did two decades earlier, while two species show reduced late-season flight. Life history characteristics of the species, particularly voltinism and average fall flight dates, influenced whether warmer fall months led to increases or decreases in fall flight. Warmer Novembers often led to later fall flight, and wetter Augusts usually extended fall flight. These results document the effects of climate on late-season flight times of butterflies, add to an understanding of how warmer autumn conditions alter the phenology of different butterfly species, and show the usefulness of citizen science data.

  16. 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)

  17. 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)

  18. Timing of arrival from spring migration is associated with flight performance in the migratory barn swallow.

    Science.gov (United States)

    Matyjasiak, Piotr

    2013-01-01

    Timing of arrival at the breeding grounds by migratory birds affects their mating success and access to superior resources, thus being a major factor associated with fitness. Much empirical work has been devoted to investigate the condition dependence of arrival sequence of migrants and characteristics of individuals that influence arrival time from migration. Surprisingly, there are no studies examining the relationship between flight performance of individual birds and their arrival time. I investigated the relative importance of direct effects of short-term flight performance, age, body condition and the degree of sexual ornamentation (tail length) on timing of spring arrival in the barn swallow (Hirundo rustica), a long-distance trans-equatorial passerine migrant. I evaluated short-term flight performance (a composite variable comprising flight manoeuvrability, velocity and acceleration) in a standardised manner using flight tunnels. Short-term flight performance was a significant and important predictor of spring arrival date. Furthermore, locomotion predicted arrival date of individual birds independently of morphological variables-the degree of sexual ornamentation (the length of the tail) and wing aspect ratio and body condition. I discuss the possible role short-term flight performance may have in determining migratory performance. This is the first time flight performance has been shown to be associated with timing of arrival from migration in a migratory bird.

  19. 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...

  20. 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

  1. Monte Carlo calculation of the neutron dose to a fetus at commercial flight altitudes

    Science.gov (United States)

    Alves, M. C.; Galeano, D. C.; Santos, W. S.; Hunt, John G.; d'Errico, Francesco; Souza, S. O.; de Carvalho Júnior, A. B.

    2017-11-01

    Aircrew members are exposed to primary cosmic rays as well as to secondary radiations from the interaction of cosmic rays with the atmosphere and with the aircraft. The radiation field at flight altitudes comprises neutrons, protons, electrons, positrons, photons, muons and pions. Generally, 50% of the effective dose to airplane passengers is due to neutrons. Care must be taken especially with pregnant aircrew members and frequent fliers so that the equivalent dose to the fetus will not exceed prescribed limits during pregnancy (1 mSv according to ICRP, and 5 mSv according to NCRP). Therefore, it is necessary to evaluate the equivalent dose to a fetus in the maternal womb. Up to now, the equivalent dose rate to a fetus at commercial flight altitudes was obtained using stylized pregnant-female phantom models. The aim of this study was calculating neutron fluence to dose conversion coefficients for a fetus of six months of gestation age using a new, realistic pregnant-female mesh-phantom. The equivalent dose rate to a fetus during an intercontinental flight was also calculated by folding our conversion coefficients with published spectral neutron flux data. The calculated equivalent dose rate to the fetus was 2.35 μSv.h-1, that is 1.5 times higher than equivalent dose rates reported in the literature. The neutron fluence to dose conversion coefficients for the fetus calculated in this study were 2.7, 3.1 and 3.9 times higher than those from previous studies using fetus models of 3, 6 and 9 months of gestation age, respectively. The differences between our study and data from the literature highlight the importance of using more realistic anthropomorphic phantoms to estimate doses to a fetus in pregnant aircrew members.

  2. A low energy, high current, pulsed electron gun for Time-of-flight mass spectrometers

    International Nuclear Information System (INIS)

    Reddy, Pratap; Rao, K.C.; Sule, Uday; Rodrigues, S.M.; Bhushan, K.G.

    2015-01-01

    A compact, low energy, high current pulsed electron gun specifically intended for use in time-of-flight mass spectrometers has been developed. The electron gun consists of a thoriated tungsten hairpin type filament, a wehnelt electrode, series of extracting electrodes, an x-y deflector and a set of pulsing electrodes, all mounted on a CF35 conflat flange. The electron gun delivers ∼ 1 mA of current at 70 eV, in the dc mode. The gun can be pulsed in nanosecond pulses with a repetition rate of upto 50 KHz which can be externally synchronized with conventional time-of-flight electronics. The design and performance of the electron gun over the energy range 20eV to 500 eV is presented along with the pulsing mode operation demonstrated in a time-of-flight mass spectrometer. (author)

  3. 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.

  4. 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

  5. Flight by night or day? Optimal daily timing of bird migration.

    Science.gov (United States)

    Alerstam, Thomas

    2009-06-21

    Many migratory bird species fly mainly during the night (nocturnal migrants), others during daytime (diurnal migrants) and still others during both night and day. Need to forage during the day, atmospheric structure, predator avoidance and orientation conditions have been proposed as explanations for the widespread occurrence of nocturnal migration. However, the general principles that determine the basic nocturnal-diurnal variation in flight habits are poorly known. In the present study optimal timing of migratory flights, giving the minimum total duration of the migratory journey, is evaluated in a schematic way in relation to ecological conditions for energy gain in foraging and for energy costs in flight. There exists a strong and fundamental advantage of flying by night because foraging time is maximized and energy deposition can take place on days immediately after and prior to the nocturnal flights. The increase in migration speed by nocturnal compared with diurnal migration will be largest for birds with low flight costs and high energy deposition rates. Diurnal migration will be optimal if it is associated with efficient energy gain immediately after a migratory flight because suitable stopover/foraging places have been located during the flight or if energy losses during flight are substantially reduced by thermal soaring and/or by fly-and-forage migration. A strategy of combined diurnal and nocturnal migration may be optimal when birds migrate across regions with relatively poor conditions for energy deposition (not only severe but also soft barriers). Predictions about variable timing of migratory flights depending on changing foraging and environmental conditions along the migration route may be tested for individual birds by analysing satellite tracking results with respect to daily travel routines in different regions. Documenting and understanding the adaptive variability in daily travel schedules among migrating animals constitute a fascinating

  6. 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.

  7. 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)

  8. 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

  9. Plane-parallel chamber as detector for time-of-flight measurements

    CERN Document Server

    Akimov, V A; Boyarinov, S V

    2002-01-01

    To arrange time-of-flight measurements in terms of the ALICE experiment one designed a system of gas detectors to record minimal-ionizing particles (MIP). Detector system is based on a plane-parallel gas-filled chamber (PPC) operating under gas intensification avalanche-type regime. One presents the results of simulation of gas discharge in PPC and evaluates the accuracy of measurement of MIP time-of-flight. One analyzes the test results of performances of PPC of various dimensions and with working gas medium various compositions. One detected correlation of flight time and of signal amplitude of PPC. One stresses, as well, positive effect of admission of electronegative additions into gas mixture. PPC time resolution constitutes 200-250 ps and MIP recording efficiency - exactly 70-90%

  10. A compact sector-type multi-turn time-of-flight mass spectrometer 'MULTUM II'

    International Nuclear Information System (INIS)

    Okumura, Daisuke; Toyoda, Michisato; Ishihara, Morio; Katakuse, Itsuo

    2004-01-01

    A new compact sector-type multi-turn time-of-flight mass spectrometer 'MULTUM II' was constructed. The ion optical system was simplified compared with former sector-type multi-turn time-of-flight mass spectrometer 'MULTUM Linear plus'. The multi-turn part of the new instruments consisted of only four toroidal electric sector fields. The mean radius of cylindrical electric sectors was 50 mm and the deflection angle was 157.1 deg. . The total flight path length of one cycle was 1.308 m. All ion optical elements were hanged on the top plate (480 mmx380 mm) of the vacuum housing. Variations of the mass resolution and ion transmission according to the number of cycles were determined. The mass resolution of 33,000 was achieved after 150 cycles

  11. Neutron Capture Reactions on Fe and Ni Isotopes for the Astrophysical s-process

    CERN Document Server

    Lederer, C; Massimi, C; Žugec, P; Barbagallo, M; Colonna, N; Domingo-Pardo, C; Guerrero, C; Gunsing, F; Käppeler, F; Tain, J L; Altstadt, S; Andrzejewski, J; Audouin, L; Bécares, V; Bečvář, F; Belloni, F; Berthoumieux, E; Billowes, J; Boccone, V; Bosnar, D; Brugger, M; Calviani, M; Calviño, F; Cano-Ott, D; Carrapiço, C; Cerutti, F; Chiaveri, E; Chin, M; Cortés, G; Cortés-Giraldo, M A; Diakaki, M; Duran, I; Dressler, R; Dzysiuk, N; Eleftheriadis, C; Ferrari, A; Fraval, K; Ganesan, S; García, A R; Gómez-Hornillos, M B; Gonçalves, I F; González-Romero, E; Griesmayer, E; Gurusamy, P; Jenkins, D G; Jericha, E; Kadi, Y; Karadimos, D; Kivel, N; Koehler, P; Kokkoris, M; Korschinek, G; Krtička, M; Kroll, J; Langer, C; Leeb, H; Leong, L S; Losito, R; Manousos, A; Marganiec, J; Martínez, T; Mastinu, P F; Mastromarco, M; Meaze, M; Mendoza, E; Mengoni, A; Milazzo, P M; Mingrone, F; Mirea, M; Mondelaers, W; Paradela, C; Pavlik, A; Perkowski, J; Pignatari, M; Plompen, A; Praena, J; Quesada, J M; Rauscher, T; Reifarth, R; Riego, A; Roman, F; Rubbia, C; Sarmento, R; Schillebeeckx, P; Schmidt, S; Schumann, D; Tagliente, G; Tarrío, D; Tassan-Got, L; Tsinganis, A; Valenta, S; Vannini, G; Variale, V; Vaz, P; Ventura, A; Versaci, R; Vermeulen, M J; Vlachoudis, V; Vlastou, R; Wallner, A; Ware, T; Weigand, M; Weiß, C; Wright, T J

    2014-01-01

    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\\_TOF at CERN focussing on the Fe/Ni mass region. Recent results and future developments in the neutron time-of-flight technique are discussed.

  12. Static real time localisation with a collinear time of flight (TOF) sonar ...

    African Journals Online (AJOL)

    Static real time localisation with a collinear time of flight (TOF) sonar triplet. Willibroad Abongwa Acho, Klaus Schilling, Radu Barza, Wolfgang Nzie. Abstract. No Abstract. Journal of the Cameroon Academy of Sciences Vol. 5(2&3) 2005: 139-160. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD ...

  13. 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...

  14. 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.

  15. Identification of Bacteria Using Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry

    Science.gov (United States)

    Kedney, Mollie G.; Strunk, Kevin B.; Giaquinto, Lisa M.; Wagner, Jennifer A.; Pollack, Sidney; Patton, Walter A.

    2007-01-01

    Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS or simply MALDI) has become ubiquitous in the identification and analysis of biomacromolecules. As a technique that allows for the molecular weight determination of otherwise nonvolatile molecules, MALDI has had a profound impact in the molecular…

  16. Design and fabrication of a time-of-flight spectrometer for studies of ...

    Indian Academy of Sciences (India)

    Ne collisions. Spectra are recorded by observing the coincidences between neon ions and simultaneously ejected electrons of all energies at 90Æ with respect to incident beam in a single collision condition. (b) Time-of-flight spectrum of Arn· ...

  17. Time-of-Flight Effects in Microwave Transmission Through a Thin Metal Slab

    DEFF Research Database (Denmark)

    Henningsen, J. O.; Falk, David S.

    1971-01-01

    A 45-GHz size-effect experiment on Ag revealed significant structure in the combined transmission and leakage signal below the first-belly-electron size effects. The oscillations, which behave differently for different field orientations, are shown to be due to the time-of-flight phase delay of e...

  18. A UV LED-based fast-pulsed photoelectron source for time-of-flight studies

    Czech Academy of Sciences Publication Activity Database

    Valerius, K.; Beck, M.; Arlinghaus, H.; Bonn, J.; Hannen, V.M.; Hein, H.; Ostrick, B.; Streubel, S.; Weinheimer, C.; Zbořil, Miroslav

    2009-01-01

    Roč. 11, - (2009), 063018/1-063018/16 ISSN 1367-2630 R&D Projects: GA MŠk LA318 Institutional research plan: CEZ:AV0Z10480505 Keywords : fast-pulsed * high-resolution * time-of-flight Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.312, year: 2009

  19. 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

  20. 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

  1. An indigenous cluster beam apparatus with a reflectron time-of-flight ...

    Indian Academy of Sciences (India)

    The design and fabrication of a Smalley-type cluster source in combination with a reflectron based time-of-flight (TOF) mass spectrometer are reported. The generation of clusters is based on supersonic jet expansion of the sampling plume. Sample cells for both liquid and solid targets developed for this purpose are ...

  2. 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...

  3. 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

  4. Neutron-emission measurements at a white neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Haight, Robert C [Los Alamos National Laboratory

    2010-01-01

    Data on the spectrum of neutrons emittcd from neutron-induced reactions are important in basic nuclear physics and in applications. Our program studies neutron emission from inelastic scattering as well as fission neutron spectra. A ''white'' neutron source (continuous in energy) allows measurements over a wide range of neutron energies all in one experiment. We use the tast neutron source at the Los Alamos Neutron Science Center for incident neutron energies from 0.5 MeV to 200 MeV These experiments are based on double time-of-flight techniques to determine the energies of the incident and emitted neutrons. For the fission neutron measurements, parallel-plate ionization or avalanche detectors identify fission in actinide samples and give the required fast timing pulse. For inelastic scattering, gamma-ray detectors provide the timing and energy spectroscopy. A large neutron-detector array detects the emitted neutrons. Time-of-flight techniques are used to measure the energies of both the incident and emitted neutrons. Design considerations for the array include neutron-gamma discrimination, neutron energy resolution, angular coverage, segmentation, detector efficiency calibration and data acquisition. We have made preliminary measurements of the fission neutron spectra from {sup 235}U, {sup 238}U, {sup 237}Np and {sup 239}Pu. Neutron emission spectra from inelastic scattering on iron and nickel have also been investigated. The results obtained will be compared with evaluated data.

  5. Ultrasonic divergent-beam scanner for time-of-flight tomography with computer evaluation

    International Nuclear Information System (INIS)

    Glover, G.H.

    1978-01-01

    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. (ORU) [de

  6. Position sensitivty with the St. George time of flight vs energy detection system

    Science.gov (United States)

    Morales, Luis; Kalkal, Sunil; Jung, Hyo Soon; Laurence, J.; Meisel, Zachary; Feltman, William; Hanner, A.; Thornton, E.-Lexis; Wiggins, B. B.; Desouza, Romualdo; Hinnefeld, Jerry; Couder, Manoel; Wiescher, Michael

    2017-09-01

    At the University of Notre Dame the St. George recoil mass separator will be used to study (α , γ) reactions of astrophysical interest. The particle identification system developed for the St. George recoil mass separator at the University of Notre Dame, in collaboration with Indiana University South Bend, utilizes time-of-flight and energy to separate reaction products from residual unreacted beam particles. The detection system uses two microchannel plate (MCP) detectors for time-of-flight, and a silicon strip detector to measure the particles kinetic energy. A position sensitive anode was designed in collaboration with Indiana University Bloomington to enhance particle identification (PID). The performance of the PID system will be presented. NSF PHY-1419765 & PHY-0959816.

  7. 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.

  8. Particle identification in the MASPIK time-of-flight magnetic spectrometer

    International Nuclear Information System (INIS)

    Azhgirej, L.S.; Zarubin, P.I.; Ivanov, V.V.; Kuznetsov, A.S.; Stoletov, G.D.

    1985-01-01

    Characteristics of the system for time-of-flight measurement in the MASPIK magnetic spectrometer with wire chambers designed for studying the nuclear reaction mechanism in extracted beams of relativistic nuclei at the JINR synchrophasotron are considered. The functional diagram of the utilized equipment and mass distribution of secondary particles detected by the spectrometer in the range of momenta of 5.7-8.5 GeV/s are presented. Pulses from two scintillation detectors placed at the distance of 21.9 m from one another are applied for determining time-of-flight of particles detected by the main arm of the spectrometer. These counters are switched also into the trigger system of the facility. The attained time resolution permits to strictly separate protons and deuterons

  9. Time-of-flight system for a heavy ion magnetic spectrometer

    International Nuclear Information System (INIS)

    Catford, W.N.; Fifield, L.K.; Hotchkis, M.A.C.; Ophel, T.R.; Orr, N.A.; Weisser, D.C.; Woods, C.L.

    1987-05-01

    A system to measure the time of flight for heavy ions around an Enge split-pole magnetic spectrometer has been developed. The system consists of a parallel plate avalanche counter at the focal plane and either a microchannel plate detector or a silicon recoil detector in the target chamber. In-beam tests under experimental conditions have demonstrated a typical resolution of 1.0 to 1.5 ns, compared to a total flight time of ∼ 100 ns. Resolution figures approaching these have been recovered, when using the 4.5 deg angular acceptance of the spectrometer, by applying calculated corrections to the raw data according to the angle and focal plane position. A description of the detectors is followed by the results of the in-beam tests. An example of an application to the study of a heavy ion reaction is also described

  10. 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)

  11. 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

  12. 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

  13. 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

  14. 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

  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. An improved laser vaporization cluster source and time-of-flight mass spectrometer

    International Nuclear Information System (INIS)

    Heer, W.A. de; Milani, P.

    1991-01-01

    We briefly describe an improved laser vaporization cluster source, which produces intense, stable and cold cluster beams, and a new time-of-flight mass spectrometer, which in several respects is more versatile and better suited for cluster studies than traditional designs. The mass spectrometer has a high resolution mode with a very large effective ionization region as well as position and velocity sensitive detection modes. (orig.)

  17. 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...... description of how a surface color intensity influences the depth measurement, and illustrate how multiple reflections influence the resulting depth measurement....

  18. 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

    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...

  19. 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

  20. 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.

  1. 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.

  2. Implementation of a new type of time-of-flight laser anemometer.

    Science.gov (United States)

    Wernet, M P; Edwards, R V

    1986-03-01

    A new time-of-flight (TOF) laser anemometer system utilizing a spatial lead-lag filter for bipolar pulse generation has been constructed and tested. This new TOF has been modified to enable measurements in turbulent flows near walls. Good results have been obtained as close as 100 microm from a surface, with a 140-mm focal length final lens. Lading's theory for the behavior of the measurement variance has been confirmed for this configuration.

  3. Timing of arrival from spring migration is associated with flight performance in the migratory barn swallow

    OpenAIRE

    Matyjasiak, Piotr

    2012-01-01

    Timing of arrival at the breeding grounds by migratory birds affects their mating success and access to superior resources, thus being a major factor associated with fitness. Much empirical work has been devoted to investigate the condition dependence of arrival sequence of migrants and characteristics of individuals that influence arrival time from migration. Surprisingly, there are no studies examining the relationship between flight performance of individual birds and their arrival time. I...

  4. 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.

  5. 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...

  6. 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.

  7. TORCH: A Large-Area Detector for Precision Time-of-Flight Measurements at LHCb

    Science.gov (United States)

    Harnew, N.

    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 of the TORCH detector for LHCb is also presented.

  8. Picosecond resolution on relativistic heavy ions' time-of-flight measurement

    Science.gov (United States)

    Ebran, A.; Taieb, J.; Belier, G.; Chatillon, A.; Laurent, B.; Martin, J.-F.; Pellereau, E.

    2013-11-01

    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.

  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. INVESTIGATIONS ON A COMBINED RGB / TIME-OF-FLIGHT APPROACH FOR CLOSE RANGE APPLICATIONS

    Directory of Open Access Journals (Sweden)

    H. Hastedt

    2012-07-01

    Full Text Available 3D surface and scene reconstruction for close range applications mainly rely on high resolution and accurate system devices and powerful algorithms. Camera systems based on the time-of-flight principle allow for real-time 3D distance measurements. Unfortunately these devices are limited in resolution and accuracy. But applying calibration models and combining with high-resolution image data offers a promising approach in order to form a multisensor system for close range applications. This article will present investigations on such a multisensor system. Different options on data fusion processing of distance information and high-resolution color information in order to generate dense 2 1/2 D and 3D point clouds will be presented. The multisensor system is calibrated with respect to its interior and exterior orientation. The time-of-flight distance information is optimized extracting best information of different data captures with a set of integration times following the principle of high dynamic range imaging. The high-resolution RGB image information is projected into object space and intersected with the object surface from the time-of-flight camera. First results of this solution on dense monoplotting and its verification will be presented.

  11. 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.)

  12. ROG, the new neutron reflectometer at IRI, Delft

    Science.gov (United States)

    van Well, A. A.; de Haan, V.-O.; Fredrikze, H.

    1994-04-01

    A description is given of the neutron reflectometer ROG, recently installed at IRI. The neutron wavelength is determined by time of flight. Wavelengths from 0.08 to 0.8 nm can be used. First experimental results are presented.

  13. 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

  14. Using convolutional neural networks to estimate time-of-flight from PET detector waveforms.

    Science.gov (United States)

    Berg, Eric; Cherry, Simon R

    2018-01-11

    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

  15. 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.)

  16. Present-day neutron diffraction at pulsed neutron sources

    International Nuclear Information System (INIS)

    Balagurov, A.M.

    1992-01-01

    The current status of neutron-diffraction experiments at pulsed neutron sources is described. The general problems in time-of-flight neutron-diffraction studies are discussed. High-resolution experiments on polycrystalline materials, structure analysis, and special experiments using single crystals are discussed, along with studies of transient processes of short duration. Special attention is paid to recent topics: very high-resolution diffractometry, neutron Fourier diffractometers, and real-time studies. 81 refs., 20 figs., 6 tabs

  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. 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.

  19. 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

  20. Neutron diffraction on pulsed sources

    Science.gov (United States)

    Aksenov, V. L.; Balagurov, A. M.

    2016-03-01

    The current capabilities of and major scientific problems solved by time-of-flight neutron diffraction are reviewed. The reasons for the rapid development of the method over the last two decades have been mainly the emergence of third-generation pulsed sources with a megawatt time-averaged power and advances in neutron optical devices and detector systems. The paper discusses some historical aspects of time-of-flight neutron diffraction and examines the contribution to this method from F L Shapiro, the centennial of whose birth was celebrated in 2015. The state of the art with respect to neutron sources for studies on extracted beams is reviewed in a special section.

  1. 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)

  2. 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.

  3. 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.

  4. 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...... 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...... for embedded applications....

  5. Improvements of the 3D images captured with Time-of-Flight cameras

    OpenAIRE

    Falie, D.

    2009-01-01

    3D Time-of-Flight camera's images are affected by errors due to the diffuse (indirect) light and to the flare light. The presented method improves the 3D image reducing the distance's errors to dark surface objects. This is achieved by placing one or two contrast tags in the scene at different distances from the ToF camera. The white and black parts of the tags are situated at the same distance to the camera but the distances measured by the camera are different. This difference is used to co...

  6. Numerical analysis of the photo-injection time-of-flight curves in molecularly doped polymers

    Science.gov (United States)

    Tyutnev, A. P.; Ikhsanov, R. Sh.; Saenko, V. S.; Nikerov, D. V.

    2018-03-01

    We have performed numerical analysis of the charge carrier transport in a specific molecularly doped polymer using the multiple trapping model. The computations covered a wide range of applied electric fields, temperatures and most importantly, of the initial energies of photo injected one-sign carriers (in our case, holes). Special attention has been given to comparison of time of flight curves measured by the photo-injection and radiation-induced techniques which has led to a problematic situation concerning an interpretation of the experimental data. Computational results have been compared with both analytical and experimental results available in literature.

  7. A time-of-flight system for the external target facility

    International Nuclear Information System (INIS)

    Zhang Xueheng; Yu Yuhong; Sun Zhiyu; Mao Ruishi; Wang Shitao; Zhou Yong; Yan Duo; Liu Longxiang

    2013-01-01

    A time-of-flight system with a plastic scintillator coupled to photomultipliers is developed for the external target facility (ETF). This system can satisfy the requirement of an ultrahigh vacuum (∼10 -9 mbar), a high counting rate (∼10 6 particles per second) and a magnetic field environment. In the beam test experiment, a total time resolution of 580 ps FWHM was obtained for the whole system, and nuclei with a mass of up to 80 could be identified using this system. (authors)

  8. Solid Phase Microextraction and Miniature Time-of-Flight Mass Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Hiller, j.m.

    1999-01-26

    A miniature mass spectrometer, based on the time-of-flight principle, has been developed for the detection of chemical warfare agent precursor molecules. The instrument, with minor modifications, could fulfill many of the needs for sensing organic molecules in various Defense Programs, including Enhanced Surveillance. The basic footprint of the instrument is about that of a lunch box. The instrument has a mass range to about 300, has parts-per-trillion detection limits, and can return spectra in less than a second. The instrument can also detect permanent gases and is especially sensitive to hydrogen. In volume, the device could be manufactured for under $5000.

  9. TORCH - Cherenkov and Time-of-Flight PID Detector for the LHCb Upgrade at CERN

    Science.gov (United States)

    Föhl, K.; Brook, N.; Castillo García, L.; Conneely, T.; Cussans, D.; Forty, R.; Frei, C.; Gao, R.; Gys, T.; Harnew, N.; Milnes, J.; Piedigrossi, D.; Rademacker, J.; Ros Garcì a, A.; van Dijk, M.

    2016-05-01

    TORCH is a large-area precision time-of-flight detector, based on Cherenkov light production and propagation in a quartz radiator plate, which is read out at its edges. TORCH is proposed for the LHCb experiment at CERN to provide positive particle identification for kaons, and is currently in the Research-and-Development phase. A brief overview of the micro-channel plate photon sensor development, the custom-made electronics, and an introduction to the current test beam activities is given. Optical readout solutions are presented for the potential use of BaBar DIRC bar boxes as part of the TORCH configuration in LHCb.

  10. Inverted time-of-flight spectrometer for mass-to-charge analysis of plasma.

    Science.gov (United States)

    Gushenets, V I; Burachevsky, Yu A; Vizir, A V; Oks, E M; Savkin, K P; Tynkov, A V; Yushkov, G Yu

    2014-02-01

    The paper describes the principle of operation, design special features, and parameters of an inverted time-of-flight spectrometer. The spectrometer is designed in such way that its deflecting plates, drift tube, and primary measuring system are at high potential with respect to the ground potential, whereas plasma is formed near grounded electrodes. This type of configuration greatly extends the application range of the device, making it possible to measure the mass-to-charge composition of plasma with wide range of parameters.

  11. 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.

  12. 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.

  13. 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.

  14. Detection area enlargement of superconducting stripline detectors for time-of-flight mass spectrometry

    International Nuclear Information System (INIS)

    Suzuki, K.; Miki, S.; Shiki, S.; Zen, N.; Wang, Z.; Ohkubo, M.

    2009-01-01

    Superconducting stripline detectors (SSLDs) have promise as fast molecule detectors for time-of-flight mass spectrometry (TOF-MS). In this study, we have prepared NbN-SSLDs consisting of a meander structure with a thickness of 10 nm and a sensor size of 200 x 200 μm 2 , which is larger than our previous sensor size of 50 x 50 μm 2 and the largest ever reported as NbN-SSLDs. Mass spectra were successfully acquired for Angiotensin I and lysozyme by using a time-to-digital converter (TDC). It was confirmed that the counting rate and hence the statistics of mass spectra were considerably improved, while the rise time of output pulse was kept to less than 1 ns by adjusting the kinetic inductance of the striplines. With the high statistics, we have investigated the bias current dependence of detection efficiency.

  15. 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. Graphical Abstract ᅟ.

  16. 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.

  17. Accurate estimation of airborne ultrasonic time-of-flight for overlapping echoes.

    Science.gov (United States)

    Sarabia, Esther G; Llata, Jose R; Robla, Sandra; Torre-Ferrero, Carlos; Oria, Juan P

    2013-11-12

    In this work, an analysis of the transmission of ultrasonic signals generated by piezoelectric sensors for air applications is presented. Based on this analysis, an ultrasonic response model is obtained for its application to the recognition of objects and structured environments for navigation by autonomous mobile robots. This model enables the analysis of the ultrasonic response that is generated using a pair of sensors in transmitter-receiver configuration using the pulse-echo technique. This is very interesting for recognizing surfaces that simultaneously generate a multiple echo response. This model takes into account the effect of the radiation pattern, the resonant frequency of the sensor, the number of cycles of the excitation pulse, the dynamics of the sensor and the attenuation with distance in the medium. This model has been developed, programmed and verified through a battery of experimental tests. Using this model a new procedure for obtaining accurate time of flight is proposed. This new method is compared with traditional ones, such as threshold or correlation, to highlight its advantages and drawbacks. Finally the advantages of this method are demonstrated for calculating multiple times of flight when the echo is formed by several overlapping echoes.

  18. A detector system for hyperon production at the COSY time-of-flight spectrometer

    International Nuclear Information System (INIS)

    Eyrich, W.; Brand, H.; Brand, S.; Cloth, P.; Brueke, V.; Eyrich, W.; Freiesleben, H.; Filges, D.; Kilian, K.; Kirsch, M.; Koch, H.; Kraft, R.A.; Krug, J.; Kuhlmann, E.; Lange, S.; Machner, H.; Matthaey, H.; Michel, P.; Mirz, R.; Moeller, K.; Morsch, H.P.; Naumann, B.; Naumann, L.; Oelert, W.; Parsch, A.; Paul, N.; Ringe, P.; Roderburg, E.; Roehrich, K.; Roeser, A.; Rogge, M.; Schmidt, G.; Schult, O.; Sefzick, T.; Steinke, M.; Stinzig, F.; Turek, P.; Werding, R.; Wirth, S.

    1993-01-01

    In an experiment at the external COSY beam associated strangeness production well be investigated by measuring total and differential cross sections as well as the polarization of the produced hyperons by means of an almost 4π time-of-flight spectrometer. In a first step we will concentrate on the reaction pp→kΛp. The apparatus will consist of an inner arrangement as start detector and highly granulated scintillator hodoscopes as stop detector. Both parts give information on multiplicity and allow to idendify the interesting reaction by means of the delayed charged decay of the Λ. Moreover the tracks of all prompt and delayed reaction products can be reconstructed with high precision. The detector allows the momentum measurement by time-of-flight. To get all this information the inner detector is composed of tiny granulated plastic scintillator detectors, silicon microstrip devices and a scintillating fibre hodoscope. The outer detector barrel with a diameter of about 3 m and a length of about 7.5 m will consist of three layers of plastic scintillator slabs, tow of them bended in helix form. The status of the experiment will be presented. Moreover the results of test measurements for the different detector components will be discussed together with Monte Carlo calculations. (orig.)

  19. 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.

  20. Time-of-flight MeV-SIMS with beam induced secondary electron trigger

    Energy Technology Data Exchange (ETDEWEB)

    Schulte-Borchers, Martina, E-mail: marschul@phys.ethz.ch; Döbeli, Max; Müller, Arnold Milenko; George, Matthias; Synal, Hans-Arno

    2016-08-01

    A new Time-of-flight MeV Secondary Ion Mass Spectrometry (MeV-SIMS) setup was developed to be used with a capillary microprobe for molecular imaging with heavy primary ions at MeV energies. Due to the low output current of the ion collimating capillary a Time-of-flight (ToF) measurement method with high duty cycle is necessary. Secondary electrons from the sample surface and transmitted ions were studied as start signals. They enable measurements with a continuous primary beam and unpulsed ToF spectrometer. Tests with various primary ion beams and sample types have shown that a secondary electron signal is obtained from 30% to 40% of incident MeV particles. This provides a ToF start signal with considerably better time resolution than the one obtained from transmitted primary ions detected in a radiation hard gas ionization detector. Beam induced secondary electrons therefore allow for MeV-SIMS measurements with reasonable mass resolution at primary ion beam currents in the low fA range.

  1. 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

  2. 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.

  3. Spectral characterisation of dairy products using photon time-of-flight spectroscopy

    DEFF Research Database (Denmark)

    Nielsen, Otto Højager Attermann; Subash, Arman Ahamed; Nielsen, Frederik Donbæk

    2013-01-01

    In this paper, we present, for the first time, the absorption and reduced scattering spectra of commercially available milk and yoghurt products, obtained using photon-time-of-flight spectroscopy. The ability of this technique to separate the contributions from absorption and scattering in the sa......In this paper, we present, for the first time, the absorption and reduced scattering spectra of commercially available milk and yoghurt products, obtained using photon-time-of-flight spectroscopy. The ability of this technique to separate the contributions from absorption and scattering......) for milk with 0.1% fat in the near infrared range, to 60 cm(-1) for yoghurt with 3.0% fat in the green wavelength regime. The absorption is within the range of 0.05-0.5cm(-1), with only small variation in the absolute value between products. Our results show that the reduced scattering clearly...... distinguishes milk and yoghurt with the same fat content and can offer a reliable way of monitoring structural formation during milk fermentation....

  4. Single-Particle Time-of-Flight Mass Spectrometry Utilizing a Femtosecond Desorption and Ionization Laser.

    Science.gov (United States)

    Zawadowicz, Maria A; Abdelmonem, Ahmed; Mohr, Claudia; Saathoff, Harald; Froyd, Karl D; Murphy, Daniel M; Leisner, Thomas; Cziczo, Daniel J

    2015-12-15

    Single-particle time-of-flight mass spectrometry has now been used since the 1990s to determine particle-to-particle variability and internal mixing state. Instruments commonly use 193 nm excimer or 266 nm frequency-quadrupled Nd:YAG lasers to ablate and ionize particles in a single step. We describe the use of a femtosecond laser system (800 nm wavelength, 100 fs pulse duration) in combination with an existing single-particle time-of-flight mass spectrometer. The goal of this project was to determine the suitability of a femtosecond laser for single-particle studies via direct comparison to the excimer laser (193 nm wavelength, ∼10 ns pulse duration) usually used with the instrument. Laser power, frequency, and polarization were varied to determine the effect on mass spectra. Atmospherically relevant materials that are often used in laboratory studies, ammonium nitrate and sodium chloride, were used for the aerosol. Detection of trace amounts of a heavy metal, lead, in an ammonium nitrate matrix was also investigated. The femtosecond ionization had a large air background not present with the 193 nm excimer and produced more multiply charged ions. Overall, we find that femtosecond laser ablation and ionization of aerosol particles is not radically different than that provided by a 193 nm excimer.

  5. 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

  6. 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.

  7. 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.

  8. Peculiarities of the modern neutron spectrometry

    Indian Academy of Sciences (India)

    Abstract. Neutron spectrometry provides many branches of science and technology with the necessary data. Usually the main part of the data is supplied by powerful neutron time-of-flight spectrometers. Nevertheless there are many other very effective but simpler and cheaper neutron spectroscopy methods on accelerators, ...

  9. 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

  10. 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

  11. 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

  12. Enhancing MALDI time-of-flight mass spectrometer performance through spectrum averaging.

    Science.gov (United States)

    Mitchell, Morgan; Mali, Sujina; King, Charles C; Bark, Steven J

    2015-01-01

    Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometers are simple and robust mass spectrometers used for analysis of biologically relevant molecules in diverse fields including pathogen identification, imaging mass spectrometry, and natural products chemistry. Despite high nominal resolution and accuracy, we have observed significant variability where 30-50% of individual replicate measurements have errors in excess of 5 parts-per-million, even when using 5-point internal calibration. Increasing the number of laser shots for each spectrum did not resolve this observed variability. What is responsible for our observed variation? Using a modern MALDI-TOF/TOF instrument, we evaluated contributions to variability. Our data suggest a major component of variability is binning of the raw flight time data by the electronics and clock speed of the analog-to-digital (AD) detection system, which requires interpolation by automated peak fitting algorithms and impacts both calibration and the observed mass spectrum. Importantly, the variation observed is predominantly normal in distribution, which implies multiple components contribute to the observed variation and suggests a method to mitigate this variability through spectrum averaging. Restarting the acquisition impacts each spectrum within the electronic error of the AD detector system and defines a new calibration function. Therefore, averaging multiple independent spectra and not a larger number of laser shots leverages this inherent binning error to mitigate variability in accurate MALDI-TOF mass measurements.

  13. Enhancing MALDI time-of-flight mass spectrometer performance through spectrum averaging.

    Directory of Open Access Journals (Sweden)

    Morgan Mitchell

    Full Text Available Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF mass spectrometers are simple and robust mass spectrometers used for analysis of biologically relevant molecules in diverse fields including pathogen identification, imaging mass spectrometry, and natural products chemistry. Despite high nominal resolution and accuracy, we have observed significant variability where 30-50% of individual replicate measurements have errors in excess of 5 parts-per-million, even when using 5-point internal calibration. Increasing the number of laser shots for each spectrum did not resolve this observed variability. What is responsible for our observed variation? Using a modern MALDI-TOF/TOF instrument, we evaluated contributions to variability. Our data suggest a major component of variability is binning of the raw flight time data by the electronics and clock speed of the analog-to-digital (AD detection system, which requires interpolation by automated peak fitting algorithms and impacts both calibration and the observed mass spectrum. Importantly, the variation observed is predominantly normal in distribution, which implies multiple components contribute to the observed variation and suggests a method to mitigate this variability through spectrum averaging. Restarting the acquisition impacts each spectrum within the electronic error of the AD detector system and defines a new calibration function. Therefore, averaging multiple independent spectra and not a larger number of laser shots leverages this inherent binning error to mitigate variability in accurate MALDI-TOF mass measurements.

  14. 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.

  15. Joint Temperature-Lasing Mode Compensation for Time-of-Flight LiDAR Sensors.

    Science.gov (United States)

    Alhashimi, Anas; Varagnolo, Damiano; Gustafsson, Thomas

    2015-12-11

    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.

  16. 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.

  17. 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

  18. 3D Indoor Positioning of UAVs with Spread Spectrum Ultrasound and Time-of-Flight Cameras.

    Science.gov (United States)

    Paredes, José A; Álvarez, Fernando J; Aguilera, Teodoro; Villadangos, José M

    2017-12-30

    This work proposes the use of a hybrid acoustic and optical indoor positioning system for the accurate 3D positioning of Unmanned Aerial Vehicles (UAVs). The acoustic module of this system is based on a Time-Code Division Multiple Access (T-CDMA) scheme, where the sequential emission of five spread spectrum ultrasonic codes is performed to compute the horizontal vehicle position following a 2D multilateration procedure. The optical module is based on a Time-Of-Flight (TOF) camera that provides an initial estimation for the vehicle height. A recursive algorithm programmed on an external computer is then proposed to refine the estimated position. Experimental results show that the proposed system can increase the accuracy of a solely acoustic system by 70-80% in terms of positioning mean square error.

  19. 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)

  20. 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.

  1. Time-of-flight isotope separator for a second-generation ISOL facility

    CERN Document Server

    Jacquot, B

    2003-01-01

    We focus on the study of a low energy and a high resolving power separator dedicated for an exotic isotope accelerator facility. The approach is based on the use of a time-of-flight technique in a long isochronous section. Different ion species are bunched and then separated in time, in an energy-isochronous section. We then transform the time shift in a transverse shift by a chopper in order to eliminate the unwanted ions using slits. A mass-resolving power of R sub M =10,000 seems feasible for low energy, multi-charged or mono-charged beams with a transverse acceptance up to 50 pi mm mrad.

  2. Characterisation of fulvic acids by electrospray with quadrupole / time-of-flight mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Plancque, G. [Commissariat a l' Energie Atomique, Centre de Saclay, Direction de l' Energie Nucleaire / DPC / SECR / Lab. de Speciation des Radionucleides et des Molecules, Gif-sur-Yvette (France)

    2004-07-01

    Characterisation of fulvic and humic acids (FA and HA) - synthetic model substances M1 and M42 from FZR, FA and HA Gohy 573 from the Gorleben groundwaters from FZK and purified Aldrich HA from CTU - has been performed using a quadrupole time-of-flight (QTOF) mass spectrometer equipped with an electrospray ionisation interface. The same conclusions as for Mol fulvic acids, previously studied in the laboratory, can be drawn: molecular masses centred around 350 Da, sinusoidal spectral distributions, even and odd integral masses distributions and presence of dimmers (and possible trimmers) in negative-mode experiments have been observed for all humic substances. Tandem mass spectrometry (MS/MS) has also been used and experiments showed losses of 18 Da (H{sub 2}O), 28 Da (CO) and 44 Da (CO{sub 2}) as for Mol FA. No obvious differences, in terms of molecular structure, are observed compared to Mol FA. (orig.)

  3. Development of scalable electronics for the TORCH time-of-flight detector

    Science.gov (United States)

    Gao, R.; Brook, N.; Castillo García, L.; Cowie, E. N.; Cussans, D.; Forty, R.; Frei, C.; Gys, T.; Harnew, N.; Piedigrossi, D.; Van Dijk, M.

    2015-02-01

    The TORCH detector is proposed for the low-momentum particle identification upgrade of the LHCb experiment. It combines Time-Of-Flight and Cherenkov techniques to achieve charged particle separation up to 10 GeV/c. This requires a time resolution of 70 ps for single photons. Existing electronics has already demonstrated a 26 ps intrinsic time resolution; however the channel count and density need improvements for future micro-channel plate devices. This paper will report on a scalable design using custom ASICs (NINO-32 and HPTDC). The system provides up to 8 × 64 channels for a single micro-channel plate device. It is also designed to read out micro-channel plate tubes with charge-sharing technique.

  4. Development of precision Time-Of-Flight electronics for LHCb TORCH

    Science.gov (United States)

    Gao, R.; Cardinale, R.; Castillo Garcia, L.; Keri, T.; Gys, T.; Harnew, N.; Fopma, J.; Forty, R.; Frei, C.; Piedigrossi, D.

    2014-02-01

    The TORCH detector is proposed for the low-momentum particle identification upgrade of the LHCb experiment. It combines Time-Of-Flight and Cherenkov techniques to achieve positive π/K/p separation up to 10 GeV/c. This requires a timing resolution of 70 ps for single photons. This paper reports on the electronics developed for such measurements, using commercial Micro Channel Plate (MCP) devices and custom ASICs (NINO and HPTDC). The intrinsic timing resolution of the electronics measured with electrical test pulses is 40 ps. With the MCP photon detector and a pulsed laser, a resolution of 90 ps has been recorded in laboratory tests and 130 ps in test beams.

  5. Quantitative analysis of hydrogen in thin films using Time-of-Flight Elastic Recoil Detection Analysis

    International Nuclear Information System (INIS)

    Siketic, Zdravko; Radovic, Iva Bogdanovic; Jaksic, Milko

    2010-01-01

    Determination of atomic concentrations in thin films is one of the key problems in materials science. Time-of-Flight Elastic Recoil Detection Analysis is a powerful method for depth profiling of light and medium mass elements in near surface layers of material. However, due to poor detection efficiency those spectrometers are not commonly used for hydrogen analysis. We have performed some improvements in order to increase detection efficiency and to make spectrometer more suitable for hydrogen analysis. The spectrometer performance was tested on amorphous Si samples implanted with H - and D - and hydrogenised Si standard reference sample. Sensitivity for hydrogen in silicon matrix was found to be several tens of ppm with a surface depth resolution of ∼ 15 nm.

  6. 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

  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. Measurement of the transmission efficiency of He-jet laser time-of-flight mass spectrometer

    International Nuclear Information System (INIS)

    Cheng Hongxing; Pang Wenning; Shang Rencheng; Zhang Wei; Ta La; Xiao Yuan; Xu Sida; Zhao Zhizheng; Luo Yixiao

    1999-01-01

    A He-jet laser time-of-flight (TOF) mass spectrometer system is built. The sample atoms evaporated in the atomization chamber are used to simulated the reaction products. The sample atoms are transferred by helium gas trough a thin capillary. After passing through a skimmer, the sample atoms are formed into a neutral atom stream. A two-or three-color laser beams perpendicular to the atom jet is used to excite and ionize the atoms by multi-step. Then a pulsed electrical field pulls the ionized atoms to the TOF mass spectrometer. By this processing, the (Z, A) values of the sample atoms can be determined precisely. The efficiency of the spectrometer is studied by measuring the radioactivity of 24 Na atoms. The transmission efficiency consists of two parts, the transportation efficiency and the efficiency of laser resonance ionization. The transportation efficiency is determined to be about 17%

  9. Hard- and software complex for laser time-of-flight mass spectrometer

    International Nuclear Information System (INIS)

    Sysoev, A.A.; Kas'yanov, V.B.; Poteshin, S.S.; Sil'nikov, E.E.; Sysoev, A.A.; Trofimov, A.S.

    2007-01-01

    The two-level principle serves as a basis to design the hardware and software system for the laser time-of-flight spectrometer. At the upper level the PC ensures the on-line control of the recording and the processing of the highest priority mass spectrometers. The controllers representing the control second level are responsible for monitoring and stabilization. The exchange between the controllers and the PC takes place in the periods free from recording and processing of the mass spectrometers. The use of the hardware and software system ensures as follows: to form up to 10 ns duration short mass peaks at the half-height; to reduce the scattering of the relative sensitivity coefficients from 2-3 orders up to 1 order; to improve the dynamic range of the recorded mass spectra up to 1-1x10 9 [ru

  10. 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

  11. 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)

  12. 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

  13. 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

  14. 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

  15. Statistical model uncertainty and OPERA-like time-of-flight measurements

    CERN Document Server

    Riordan, Oliver

    2011-01-01

    Time-of-flight measurements such as the OPERA and MINOS experiments rely crucially on statistical analysis (as well as many other ingredients) for their conclusions. The nature of these experiments leads to a simple class of statistical models for the results; however, which model in the class is appropriate is not known exactly, as this depends on information obtained experimentally, which is subject to noise and other errors. To obtain robust conclusions, this problem, known as "model uncertainty," needs to be addressed, with quantitative bounds on the effect such uncertainty may have on the final result. The OPERA (and MINOS) analysis appears to take steps to mitigate the effects of model uncertainty, though without quantifying any remaining effect. We describe one of the strategies used (averaging individual probability distributions), and point out a potential source of error if this is not carried out correctly. We then argue that the correct version of this strategy is not the most effective, and sugge...

  16. TOFwave: reproducibility in biomarker discovery from time-of-flight mass spectrometry data.

    Science.gov (United States)

    Chierici, Marco; Albanese, Davide; Franceschi, Pietro; Furlanello, Cesare

    2012-11-01

    Many are the sources of variability that can affect reproducibility of disease biomarkers from time-of-flight (TOF) Mass Spectrometry (MS) data. Here we present TOFwave, a complete software pipeline for TOF-MS biomarker identification, that limits the impact of parameter tuning along the whole chain of preprocessing and model selection modules. Peak profiles are obtained by a preprocessing based on Continuous Wavelet Transform (CWT), coupled with a machine learning protocol aimed at avoiding selection bias effects. Only two parameters (minimum peak width and a signal to noise cutoff) have to be explicitly set. The TOFwave pipeline is built on top of the mlpy Python package. Examples on Matrix-Assisted Laser Desorption and Ionization (MALDI) TOF datasets are presented. Software prototype, datasets and details to replicate results in this paper can be found at http://mlpy.sf.net/tofwave/.

  17. 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.

  18. 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.

  19. 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

  20. The TORCH time-of-flight detector for particle identification and photon vertex association

    Science.gov (United States)

    Castillo García, L.; Brook, N.; Cussans, D.; Föhl, K.; Forty, R.; Frei, C.; Gao, R.; Gys, T.; Harnew, N.; Piedigrossi, D.; Rademacker, J.; Ros García, A.; van Dijk, M.

    2017-02-01

    TORCH (Time Of internally Reflected CHerenkov light) is a novel time-of-flight detector, designed to provide π /K/p particle identification up to 0~ 1 GeV/c momentum and beyond. To achieve this, a time resolution of ~ 15 ps combining information from 0~ 3 detected photons is required over a 10 m flight path. Large areas can be covered with TORCH, nominally up to 30 m2. One such application is for the LHCb experiment, to complement the particle identification capabilities of its RICH detectors. TORCH has a DIRC-like construction with 10 mm-thick synthetic amorphous fused-silica plates as a radiator. Cherenkov photons propagate by total internal reflection to the plate edges and there are focussed onto an array of position-sensitive photodetectors. Custom-built micro-channel plate photo-multipliers (MCP-PMTs) are being developed in collaboration with industry to provide the lifetime, granularity and time resolution to meet the TORCH specifications. In the present paper, laboratory tests of the MCP-PMTs developed for TORCH and its readout electronics are presented. Test beam measurements of a prototype TORCH detector in a low-momentum mixed beam of pions and protons are highlighted. Time resolutions for individual photons approaching 100 ps is achieved, after correction for dispersion effects in the quartz medium. In addition to the particle identification capabilities, the high-precision timing information that TORCH provides could be used at the high-luminosity LHC to associate high-energy photons with the correct primary interaction vertex amongst the many expected.

  1. The TORCH time-of-flight detector for particle identification and photon vertex association

    International Nuclear Information System (INIS)

    García, L. Castillo; Gao, R.; Harnew, N.; Dijk, M. van; Brook, N.; Cussans, D.; Rademacker, J.; García, A. Ros; Föhl, K.; Forty, R.; Frei, C.; Gys, T.; Piedigrossi, D.

    2017-01-01

    TORCH (Time Of internally Reflected CHerenkov light) is a novel time-of-flight detector, designed to provide π /K/p particle identification up to 0∼ 1 GeV/c momentum and beyond. To achieve this, a time resolution of ∼ 15 ps combining information from 0∼ 3 detected photons is required over a 10 m flight path. Large areas can be covered with TORCH, nominally up to 30 m 2 . One such application is for the LHCb experiment, to complement the particle identification capabilities of its RICH detectors. TORCH has a DIRC-like construction with 10 mm-thick synthetic amorphous fused-silica plates as a radiator. Cherenkov photons propagate by total internal reflection to the plate edges and there are focussed onto an array of position-sensitive photodetectors. Custom-built micro-channel plate photo-multipliers (MCP-PMTs) are being developed in collaboration with industry to provide the lifetime, granularity and time resolution to meet the TORCH specifications. In the present paper, laboratory tests of the MCP-PMTs developed for TORCH and its readout electronics are presented. Test beam measurements of a prototype TORCH detector in a low-momentum mixed beam of pions and protons are highlighted. Time resolutions for individual photons approaching 100 ps is achieved, after correction for dispersion effects in the quartz medium. In addition to the particle identification capabilities, the high-precision timing information that TORCH provides could be used at the high-luminosity LHC to associate high-energy photons with the correct primary interaction vertex amongst the many expected.

  2. High mass resolution time of flight mass spectrometer for measuring products in heterogeneous catalysis in highly sensitive microreactors

    DEFF Research Database (Denmark)

    Andersen, Thomas; Jensen, Robert; Christensen, M. K.

    2012-01-01

    We demonstrate a combined microreactor and time of flight system for testing and characterization of heterogeneous catalysts with high resolution mass spectrometry and high sensitivity. Catalyst testing is performed in silicon-based microreactors which have high sensitivity and fast thermal...... response. Gas analysis is performed with a time of flight mass spectrometer with a modified nude Bayard-Alpert ionization gauge as gas ionization source. The mass resolution of the time of flight mass spectrometer using the ion gauge as ionization source is estimated to m∕Δm > 2500. The system design...... is superior to conventional batch and flow reactors with accompanying product detection by quadrupole mass spectrometry or gas chromatography not only due to the high sensitivity, fast temperature response, high mass resolution, and fast acquisition time of mass spectra but it also allows wide mass range (0...

  3. Influence of the neutron transport tube on neutron resonance densitometry

    Directory of Open Access Journals (Sweden)

    Kitatani Fumito

    2017-01-01

    Full Text Available Neutron Resonance Densitometry (NRD is a non-destructive assay technique of nuclear materials in particle-like debris that contains various materials. An aim of NRD is to quantify nuclear materials in a melting fuel of Fukusima Daiichi plant, spent nuclear fuel and annihilation disposal fuel etc. NRD consists of two techniques of Neutron Resonance Transmission Analysis (NRTA and Neutron Resonance Capture Analysis (NRCA or Prompt Gamma-ray Analysis (PGA. A density of nuclear material isotopes is decided with NRTA. The materials absorbing a neutron in a wide energy range such as boron in a sample are identified by NRCA/PGA. The information of NRCA/PGA is used in NRTA analysis to quantify nuclear material isotopes. A neutron time of flight (TOF method is used in NRD measurements. A facility, consisting of a neutron source, a neutron flight path, and a detector is required. A short flight path and a strong neutron source are needed to downsize such a facility and put NRD into practical use. A neutron transport tube covers a flight path to prevent noises. In order to investigate the effect of neutron transport tube and pulse width of a neutron source, we carried out NRTA experiments with a 2-m short neutron transport tube constructed at Kyoto University Research Reactor Institute - Linear Accelerator (KURRI-LINAC, and impacts of shield of neutron transport tube and influence of pulse width of a neutron source were examined. A shield of the neutron transport tube reduced a background and had a good influence on the measurement. The resonance dips of 183W at 27 eV was successfully observed with a pulse width of a neutron source less than 2 μs.

  4. Influence of the neutron transport tube on neutron resonance densitometry

    Science.gov (United States)

    Kitatani, Fumito; Tsuchiya, Harufumi; Koizumi, Mitsuo; Takamine, Jun; Hori, Junichi; Sano, Tadafumi

    2017-09-01

    Neutron Resonance Densitometry (NRD) is a non-destructive assay technique of nuclear materials in particle-like debris that contains various materials. An aim of NRD is to quantify nuclear materials in a melting fuel of Fukusima Daiichi plant, spent nuclear fuel and annihilation disposal fuel etc. NRD consists of two techniques of Neutron Resonance Transmission Analysis (NRTA) and Neutron Resonance Capture Analysis (NRCA) or Prompt Gamma-ray Analysis (PGA). A density of nuclear material isotopes is decided with NRTA. The materials absorbing a neutron in a wide energy range such as boron in a sample are identified by NRCA/PGA. The information of NRCA/PGA is used in NRTA analysis to quantify nuclear material isotopes. A neutron time of flight (TOF) method is used in NRD measurements. A facility, consisting of a neutron source, a neutron flight path, and a detector is required. A short flight path and a strong neutron source are needed to downsize such a facility and put NRD into practical use. A neutron transport tube covers a flight path to prevent noises. In order to investigate the effect of neutron transport tube and pulse width of a neutron source, we carried out NRTA experiments with a 2-m short neutron transport tube constructed at Kyoto University Research Reactor Institute - Linear Accelerator (KURRI-LINAC), and impacts of shield of neutron transport tube and influence of pulse width of a neutron source were examined. A shield of the neutron transport tube reduced a background and had a good influence on the measurement. The resonance dips of 183W at 27 eV was successfully observed with a pulse width of a neutron source less than 2 μs.

  5. 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...

  6. Membrane introduction/laser photoionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Oser, Harald; Coggiola, Michael J; Young, Steven E; Crosley, David R; Hafer, Virginia; Grist, Gregory

    2007-04-01

    Two-photon resonance enhanced multiphoton ionization (REMPI) has been shown to be a unique ionization method for mass spectrometry, exhibiting both high sensitivity and chemical selectivity. Because REMPI is a gas-phase method, its applications have been limited either to direct analysis of vapor phase samples, or in conjunction with an initial laser desorption or other vaporization step. We describe here for the first time a combination of membrane introduction mass spectrometry (MIMS) and REMPI with time-of-flight mass spectrometry (TOF-MS), which allows for the direct analysis of trace amounts of organic compounds in water samples. The objective of our research was the detection of very low levels of aromatic contaminants, particularly benzene, toluene, and xylene (BTX), in aqueous solutions without interference due to the water. We have measured limits of detection (LOD) for selected aromatics in water below 1 part-per-trillion with an averaging time of less than 10 s using a continuous sample flow.

  7. Neutron scattering. Experiment manuals

    International Nuclear Information System (INIS)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner

    2014-01-01

    The following topics are dealt with: The thermal triple-axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot-single-crystal diffractometer HEiDi, the three-axis spectrometer PANDA, the backscattering spectrometer SPHERES, the DNS neutron-polarization analysis, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering at KWS-1 and KWS-2, a very-small-angle neutron scattering diffractometer with focusing mirror, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  8. Neutron scattering. Experiment manuals

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2014-07-01

    The following topics are dealt with: The thermal triple-axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot-single-crystal diffractometer HEiDi, the three-axis spectrometer PANDA, the backscattering spectrometer SPHERES, the DNS neutron-polarization analysis, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering at KWS-1 and KWS-2, a very-small-angle neutron scattering diffractometer with focusing mirror, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  9. Methods of neutron spectrometry

    International Nuclear Information System (INIS)

    Doerschel, B.

    1981-01-01

    The different methods of neutron spectrometry are based on the direct measurement of neutron velocity or on the use of suitable energy-dependent interaction processes. In the latter case the measuring effect of a detector is connected with the searched neutron spectrum by an integral equation. The solution needs suitable unfolding procedures. The most important methods of neutron spectrometry are the time-of-flight method, the crystal spectrometry, the neutron spectrometry by use of elastic collisions with hydrogen nuclei, and neutron spectrometry with the aid of nuclear reactions, especially of the neutron-induced activation. The advantages and disadvantages of these methods are contrasted considering the resolution, the measurable energy range, the sensitivity, and the experimental and computational efforts. (author)

  10. 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.

  11. Development of a monoenergetic neutron beam (Theoretical aspects, experimental developments and applications); Desarrollo de un haz de neutrones monoenergeticos (Aspectos teoricos, desarrollos experimentales y aplicaciones)

    Energy Technology Data Exchange (ETDEWEB)

    Varela G, A

    2003-07-01

    By the use of a neutron time of flight system at the Tandem Accelerator of the National Nuclear Research Institute; with neutrons provided by means of the {sup 2} H(d, n) {sup 3} He we intend to use the associated particle technique in order to have monoenergetic neutrons. This neutron beam will be used both in basic and applied research. (Author)

  12. High-speed digitization readout of silicon photomultipliers for time of flight positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Ronzhin, A.; Los, S.; Martens, M.; Ramberg, E.; /Fermilab; Kim, H.; Chen, C.; Kao, C.; /Chicago U.; Niessen, K.; /SUNY, Buffalo; Zatserklyaniy, A.; /Puerto Rico U., Mayaguez; Mazzillo, M.; Carbone, B.; /SGS Thomson, Catania

    2011-02-01

    We report on work to develop a system with about 100 picoseconds (ps) time resolution for time of flight positron emission tomography [TOF-PET]. The chosen photo detectors for the study were Silicon Photomultipliers (SiPM's). This study was based on extensive experience in studying timing properties of SiPM's. The readout of these devices used the commercial high speed digitizer DRS4. We applied different algorithms to get the best time resolution of 155 ps Guassian (sigma) for a LYSO crystal coupled to a SiPM. We consider the work as a first step in building a prototype TOF-PET module. The field of positron-emission-tomography (PET) has been rapidly developing. But there are significant limitations in how well current PET scanners can reconstruct images, related to how fast data can be acquired, how much volume they can image, and the spatial and temporal resolution of the generated photons. Typical modern scanners now include multiple rings of detectors, which can image a large volume of the patient. In this type of scanner, one can treat each ring as a separate detector and require coincidences only within the ring, or treat the entire region viewed by the scanner as a single 3 dimensional volume. This 3d technique has significantly better sensitivity since more photon pair trajectories are accepted. However, the scattering of photons within the volume of the patient, and the effect of random coincidences limits the technique. The advent of sub-nanosecond timing resolution detectors means that there is potentially much better rejection of scattered photon events and random coincidence events in the 3D technique. In addition, if the timing is good enough, then the origin of photons pairs can be determined better, resulting in improved spatial resolution - so called 'Time-of-Flight' PET, or TOF-PET. Currently a lot of activity has occurred in applications of SiPMs for TOF-PET. This is due to the devices very good time resolution, low profile

  13. Delayed-neutron fraction in a pulsed spallation neutron source

    International Nuclear Information System (INIS)

    Carpenter, J.M.

    1980-02-01

    The fraction of delayed neutrons β (with T/sub 1/2/ greater than or equal to 0.025 s) in slow-neutron beams from a 238 U pulsed spallation neutron source is 0.0053 for 300 MeV protons. This measurement appears to be the first one of this quantity. The result indicates that, for most classes of measurements, the delayed-neutron background in time-of-flight instruments will be unimportant, and places constraints on the physics description of spallation targets. The measurement was performed at the prototype pulsed spallation neutron source, ZING-P', at Argonne National laboratory. 4 figures

  14. Neutron scattering studies on soft materials

    International Nuclear Information System (INIS)

    Inoue, Rintaro; Kanaya, Toshiji

    2010-01-01

    We review recent progress of neutron scattering studies on soft matters using various techniques such as small angle neutron scattering, neutron spin echo, backscattering, time-of-flight technique, reflectivity and grazing-incident small angle neutron scattering. In the present review, we focus on functionalized polymers such as polyrotaxane, Nafion, polymer/nano composite system, and casein protein thin films, which are of great interest from both scientific and industrial viewpoints. We also state some future experiments at J-PARC. (author)

  15. Isotope determination of lead and bismuth by pulsed laser evaporation and resonance ionization time-of-flight mass spectrometry

    International Nuclear Information System (INIS)

    Mingfei Zhou; Qizong Qin

    1995-01-01

    Pulsed laser evaporation coupled with resonance ionization time-of-flight mass spectrometry has been used to measure the isotopic abundance of lead and bismuth. A pulsed Nd:YAG laser was used to evaporate the metal atoms, the evaporated atoms were then detected by one color two photon resonance ionization and time-of-flight mass spectrometry. The arrival time distributions of atoms evaporated by pulsed laser, and the isotopic abundances of Pb and Bi were measured. Our results show that this method is good enough for measuring the isotopic abundances of Pb and Bi with high sensitivity and selectivity. (author). 8 refs., 3 figs., 1 tab

  16. 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.

  17. Cold neutron radiography using low power accelerator

    International Nuclear Information System (INIS)

    Kiyanagi, Yoshiaki; Iwasa, Hirokatu

    1993-01-01

    A cold neutron source which can be adopted at a low power accelerator was studied. Time-of-flight radiography using the cold neutron source was performed. It is suggested that time-of-flight cold neutron radiography has possibility to distinguish the materials more clearly than the traditional film method since large contrast differences can be obtained by using digital data of the neutron intensity at different energies from thermal to cold region. Material will be identified at the same time by this method. (author)

  18. Development of picoseconds Time of Flight systems in Meson Test Beam Facility at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Ronzhin, A.; Albrow, M.; Demarteau, M.; Los, S.; /Fermilab; Malik, S.; /Rockefeller U.; Pronko, S.; Ramberg, E.; /Fermilab; Zatserklyaniy, A.; /Puerto Rico U., Mayaguez

    2010-11-01

    The goal of the work is to develop time of flight (TOF) system with about 10 picosecond time resolution in real beam line when start and stop counters separated by some distance. We name the distance as 'base' for the TOF. This 'real' TOF setup is different from another one when start and stop counters located next to each other. The real TOF is sensitive to beam momentum spread, beam divergence, etc. Anyway some preliminary measurements are useful with close placement of start and stop counter. We name it 'close geometry'. The work started about 2 years ago at Fermilab Meson Test Beam Facility (MTBF). The devices tested in 'close geometry' were Microchannel Plate Photomultipliers (MCP PMT) with Cherenkov radiators. TOF counters based on Silicon Photomultipliers (SiPms) with Cherenkov radiators also in 'close geometry' were tested. We report here new results obtained with the counters in the MTBF at Fermilab, including beam line data.

  19. Multi-capillary-column proton-transfer-reaction time-of-flight mass spectrometry.

    Science.gov (United States)

    Ruzsanyi, Veronika; Fischer, Lukas; Herbig, Jens; Ager, Clemes; Amann, Anton

    2013-11-05

    Proton-transfer-reaction time-of-flight mass-spectrometry (PTR-TOFMS) exhibits high selectivity with a resolution of around 5000 m/Δm. While isobars can be separated with this resolution, discrimination of isomeric compounds is usually not possible. The coupling of a multi-capillary column (MCC) with a PTR-TOFMS overcomes these problems as demonstrated in this paper for the ketone isomers 3-heptanone and 2-methyl-3-hexanone and for different aldehydes. Moreover, fragmentation of compounds can be studied in detail which might even improve the identification. LODs for compounds tested are in the range of low ppbv and peak positions of the respective separated substances show good repeatability (RSD of the peak positions <3.2%). Due to its special characteristics, such as isothermal operation, compact size, the MCC setup is suitable to be installed inside the instrument and the overall retention time for a complete spectrum is only a few minutes: this allows near real-time measurements in the optional MCC mode. In contrast to other methods that yield additional separation, such as the use of pre-cursor ions other than H3O(+), this method yields additional information without increasing complexity. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

  20. Simulation of time of flight defraction signals for reactor vessel head penetrations

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Tae Hun; Kim, Young Sik; Lee, Jeong Seok [KHNP Central Research Institute, Daejeon (Korea, Republic of)

    2016-08-15

    The simulation of nondestructive testing has been used in the prediction of the signal characteristics of various defects and in the development of the procedures. CIVA, a simulation tool dedicated to nondestructive testing, has good accuracy and speed, and provides a three-dimensional graphical user interface for improved visualization and familiar data displays consistent with an NDE technique. Even though internal validations have been performed by the CIVA software development specialists, an independent validation study is necessary for the assessment of the accuracy of the software prior to practical use. In this study, time of flight diffraction signals of ultrasonic inspection of a calibration block for reactor vessel head penetrations were simulated using CIVA. The results were compared to the experimentally inspected signals. The accuracy of the simulated signals and the possible range for simulation were verified. It was found that, there is a good agreement between the CIVA simulated and experimental results in the A-scan signal, B-scan image, and measurement of depth.

  1. 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...

  2. Time-of-flight electron energy loss spectroscopy using TM110 deflection cavities

    Directory of Open Access Journals (Sweden)

    W. Verhoeven

    2016-09-01

    Full Text Available We demonstrate the use of two TM110 resonant cavities to generate ultrashort electron pulses and subsequently measure electron energy losses in a time-of-flight type of setup. The method utilizes two synchronized microwave cavities separated by a drift space of 1.45 m. The setup has an energy resolution of 12 ± 2 eV FWHM at 30 keV, with an upper limit for the temporal resolution of 2.7 ± 0.4 ps. Both the time and energy resolution are currently limited by the brightness of the tungsten filament electron gun used. Through simulations, it is shown that an energy resolution of 0.95 eV and a temporal resolution of 110 fs can be achieved using an electron gun with a higher brightness. With this, a new method is provided for time-resolved electron spectroscopy without the need for elaborate laser setups or expensive magnetic spectrometers.

  3. Development of a picosecond time-of-flight system in the ATLAS experiment

    International Nuclear Information System (INIS)

    Grabas, Herve

    2013-01-01

    In this thesis, we present a study of the sensitivity to Beyond Standard Model physics brought by the design and installation of picosecond time-of-flight detectors in the forward region of the ATLAS experiment at the LHC. The first part of the thesis present a study of the sensitivity to the quartic gauge anomalous coupling between the photon and the W boson, using exclusive WW pair production in ATLAS. The event selection is built considering the semi-leptonic decay of WW pair and the presence of the AFP detector in ATLAS. The second part gives a description of large area picosecond photo-detectors design and time reconstruction algorithms with a special care given to signal sampling and processing for precision timing. The third part presents the design of SamPic: a custom picosecond readout integrated circuit. At the end, its first results are reported, and in particular a world-class 5 ps timing precision in measuring the delay between two fast pulses. (author) [fr

  4. Time-of-flight thermal flowrate sensor for lab-on-chip applications.

    Science.gov (United States)

    Berthet, Helene; Jundt, Jacques; Durivault, Jerome; Mercier, Bruno; Angelescu, Dan

    2011-01-21

    We describe a thermal microflowrate sensor for measuring liquid flow velocity in microfluidic channels, which is capable of providing a highly accurate response independent of the thermal and physical properties of the working liquid. The sensor consists of a rectangular channel containing a heater and several temperature detectors microfabricated on suspended silicon bridges. Heat pulses created by the heater are advected downstream by the flow and are detected using the temperature detector bridges. By injecting a pseudo-stochastic thermal signal at the heater and performing a cross correlation between the detected and the injected signals, we can measure the single-pulse response of the system with excellent signal-to-noise ratio and hence deduce the thermal signal time-of-flight from heater to detector. Combining results from several detector bridges allows us to eliminate diffusion effects, and thus calculate the flow velocity with excellent accuracy and linearity over more than two orders of magnitude. The experimental results obtained with several test fluids closely agree with data from finite element analysis. We developed a phenomenological model which supports and explains the observed sensor response. Several fully functional sensor prototypes were built and characterized, proving the feasibility and providing a critical component to microfluidic lab-on-chip applications where accurate flow measurements are of importance.

  5. Femtosecond spectroscopic imaging by time-of-flight photoemission electron microscopy

    Science.gov (United States)

    Min, Chang-Ki; Kim, Jeong Won; Park, Yongsup

    2007-10-01

    Advances in electron optics and fast-pulsed light sources have enabled the imaging of nanoscale structures with simultaneous energy and time resolutions. We present the results obtained from a time-resolved time-of-flight photoemission electron microscopy (TR-TOF-PEEM) system. This system combined the spatial resolution of conventional PEEM with the time resolution of a femtosecond-pulsed laser and the energy resolution of a TOF energy analyzer. The TOF-PEEM system consists of three electrostatic lenses in front, a drift tube for the measurement of TOF, and a delay line detector (DLD) at the end of the optics. The excitation source is femtosecond pulses from a cavity-dumped Ti:sapphire oscillator that is frequency-doubled to 400 nm using a β-barium borate (BBO) crystal. Using a pump-probe two-photon photoemission technique, we demonstrate an example of sub-100 nm space-resolved ultrafast time evolution of the electron energy spectra for the plasmon resonance of an Ag-coated Si nanostructure, which exhibited unexpectedly intense high energy photoemission signals that show different time evolution between bright and dark regions in a PEEM image.

  6. 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.

  7. Time of flight secondary ion mass spectrometry: A powerful high throughput screening tool

    International Nuclear Information System (INIS)

    Smentkowski, Vincent S.; Ostrowski, Sara G.

    2007-01-01

    Combinatorial materials libraries are becoming more complicated; successful screening of these libraries requires the development of new high throughput screening methodologies. Time of flight secondary ion mass spectrometry (ToF-SIMS) is a surface analytical technique that is able to detect and image all elements (including hydrogen which is problematic for many other analysis instruments) and molecular fragments, with high mass resolution, during a single measurement. Commercial ToF-SIMS instruments can image 500 μm areas by rastering the primary ion beam over the region of interest. In this work, we will show that large area analysis can be performed, in one single measurement, by rastering the sample under the ion beam. We show that an entire 70 mm diameter wafer can be imaged in less than 90 min using ToF-SIMS stage (macro)rastering techniques. ToF-SIMS data sets contain a wealth of information since an entire high mass resolution mass spectrum is saved at each pixel in an ion image. Multivariate statistical analysis (MVSA) tools are being used in the ToF-SIMS community to assist with data interpretation; we will demonstrate that MVSA tools provide details that were not obtained using manual (univariate) analysis

  8. Diffuse mirrors: 3D reconstruction from diffuse indirect illumination using inexpensive time-of-flight sensors

    KAUST Repository

    Heide, Felix

    2014-06-01

    The functional difference between a diffuse wall and a mirror is well understood: one scatters back into all directions, and the other one preserves the directionality of reflected light. The temporal structure of the light, however, is left intact by both: assuming simple surface reflection, photons that arrive first are reflected first. In this paper, we exploit this insight to recover objects outside the line of sight from second-order diffuse reflections, effectively turning walls into mirrors. We formulate the reconstruction task as a linear inverse problem on the transient response of a scene, which we acquire using an affordable setup consisting of a modulated light source and a time-of-flight image sensor. By exploiting sparsity in the reconstruction domain, we achieve resolutions in the order of a few centimeters for object shape (depth and laterally) and albedo. Our method is robust to ambient light and works for large room-sized scenes. It is drastically faster and less expensive than previous approaches using femtosecond lasers and streak cameras, and does not require any moving parts.

  9. The development of a gas-filled time-of-flight detector

    International Nuclear Information System (INIS)

    Guan Yongjing; He Ming; Ruan Xiangdong; Wang Huijuan; Wu Shaoyong; Dong Kejun; Lin Min; Yuan Jian; Jiang Shan

    2007-01-01

    A gas-filled time-of-flight (GF-TOF) detector system for isobaric identification has been developed at the AMS facility of the China Institute of Atomic Energy (CIAE). The newly built GF-TOF detector was tested by using a 36 Cl standard sample ( 36 Cl/Cl = 2.88 x 10 -11 ) with the 36 Cl ion energies of 64, 49 and 33 MeV. Time resolutions of 350 ps, 580 ps and 920 ps were obtained for 64, 49 and 33 MeV 36 S, respectively, without gas. 36 Cl and 36 S particles were successfully separated in the TOF spectra from the GF-TOF detector at the three different incident energies. The dependence of time resolution and separation power of GF-TOF method on the incidence energy and the residual energy is discussed. The comparison of separation power for isobars between the GF-TOF method and the ΔE-E method is described. A combination of GF-TOF method and ΔE-E method may further improve the separation power for isobars. The results show that the sensitivity for 36 Cl AMS measurements is 10 -14 at the energy of 33 MeV. Some results obtained with the GF-TOF method are given

  10. 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.

  11. Shock tube/time-of-flight mass spectrometer for high temperature kinetic studies

    International Nuclear Information System (INIS)

    Tranter, Robert S.; Giri, Binod R.; Kiefer, John H.

    2007-01-01

    A shock tube (ST) with online, time-of-flight mass spectrometric (TOF-MS) detection has been constructed for the study of elementary reactions at high temperature. The ST and TOF-MS are coupled by a differentially pumped molecular beam sampling interface, which ensures that the samples entering the TOF-MS are not contaminated by gases drawn from the cold end wall thermal boundary layer in the ST. Additionally, the interface allows a large range of postshock pressures to be used in the shock tube while maintaining high vacuum in the TOF-MS. The apparatus and the details of the sampling system are described along with an analysis in which cooling of the sampled gases and minimization of thermal boundary layer effects are discussed. The accuracy of kinetic measurements made with the apparatus has been tested by investigating the thermal unimolecular dissociation of cyclohexene to ethylene and 1,3-butadiene, a well characterized reaction for which considerable literature data that are in good agreement exist. The experiments were performed at nominal reflected shock wave pressures of 600 and 1300 Torr, and temperatures ranging from 1260 to 1430 K. The rate coefficients obtained are compared with the earlier shock tube studies and are found to be in very good agreement. As expected no significant difference is observed in the rate constant between pressures of 600 and 1300 Torr

  12. Identification of organic xenobiotics in urban aquatic environments using time-of-flight mass spectrometry.

    Science.gov (United States)

    Jernberg, Joonas; Pellinen, Jukka; Rantalainen, Anna-Lea

    2013-04-15

    Qualitative non-target and post-target analysis methods using gas chromatography-time-of-flight mass spectrometry were applied for analysing neutral and acidic organic xenobiotics in urban and suburban water samples. Ten water samples representing wastewater, stormwater and surface water matrices were collected and concentrated using solid phase extraction. Compound identification was performed using a spectral deconvolution program, accurate mass measurements and comparisons with library spectra. The non-target and post-target analyses identified 36 and 18 compounds, respectively. The identification of 10 compounds was afterwards confirmed with standard compounds. Organophosphate esters were the most abundant compound group detected. The combination of non-target and post-target analyses proved a useful tool in the tentative identification of xenobiotics in water samples. Post-target analysis can complement non-target analysis results at low analyte concentrations. Results showed that several organic xenobiotics originate in urban areas and accumulate in the environment. The wastewater sample produced the highest number of identified compounds, but most of these compounds were also found in stormwater samples from the city centre. Nearly all the compounds present in wastewater were additionally detected in the surface water sample taken 3 km downstream from the wastewater effluent discharge point. Only a few xenobiotics were otherwise detected in the surface water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Development of a Portable Single Photon Ionization-Photoelectron Ionization Time-of-Flight Mass Spectrometer

    Directory of Open Access Journals (Sweden)

    Yunguang Huang

    2015-01-01

    Full Text Available A vacuum ultraviolet lamp based single photon ionization- (SPI- photoelectron ionization (PEI portable reflecting time-of-flight mass spectrometer (TOFMS was designed for online monitoring gas samples. It has a dual mode ionization source: SPI for analyte with ionization energy (IE below 10.6 eV and PEI for IE higher than 10.6 eV. Two kinds of sampling inlets, a capillary inlet and a membrane inlet, are utilized for high concentration and trace volatile organic compounds, respectively. A mass resolution of 1100 at m/z 64 has been obtained with a total size of 40 × 31 × 29 cm, the weight is 27 kg, and the power consumption is only 70 W. A mixture of benzene, toluene, and xylene (BTX, SO2, and discharging products of SF6 were used to test its performance, and the result showed that the limit of quantitation for BTX is as low as 5 ppbv (S/N = 10 : 1 with linear dynamic ranges greater than four orders of magnitude. The portable TOFMS was also evaluated by analyzing volatile organic compounds from wine and decomposition products of SF6 inside of a gas-insulated switchgear.

  14. Five years of testing using the simi-automated ultrasonic time of flight diffraction system

    International Nuclear Information System (INIS)

    Webber, S.A.

    2002-01-01

    This paper provides a brief description of the Time of Flight Diffraction (TOFD) test system and also describes a couple of case histories where the system has been successfully applied. The T.O.F.D. system has been contrasted with the conventional manual ultrasonic technique. Whilst the T.O.F.D. system has proven potential, and is without doubt a valuable tool that will continue to gain market share in the inspection industry, conventional manual ultrasonics still has its part to play and will survive for some time to come. One of the outstanding issues facing the T.O.F.D. systems is the question of acceptance testing which is still the predominant convention specified in most standards. Training for a T.O.F.D. system technician is particularly important and the author suggests there are more traps for the unwary than with the conventional manual ultrasonic systems. The overall judgement of the T.O.F.D. system is that it is a most welcome and powerful tool in the hands of the right operator and will do much to boost the prominence of Non-Destructive Testing

  15. A time-of-flight spectrometer for detection of low energetic hydrogen atoms

    International Nuclear Information System (INIS)

    Toledo, W. van; Bree, A.R. de; Buuren, R. van; Kluiver, H. de; Donne, A.J.H.

    1989-01-01

    Low energetic neutral hydrogen atoms that are released from wall and limiters of a tokamak as well as Franck-Condon neutrals may undergo charge exchange with plasma ions. The resulting fast neutrals are not confined to the magnetic field and thus contribute to energy losses, including those due to impurity radiation when the fast atoms sputter impurity ions from the wall. These processes determine the particle and energy transport from the plasma center and quantities as the sputtering coefficient, the reflection coefficient of the wall and the diffusivity of H or D in the wall material play a decisive role here. By detecting especially the cold neutrals from the boundary layer one gains information on the hydrogen or deuterium recycling and hence on the energy balance of the plasma. This paper shall be concerned with a time-of-flight method, that requires direct detection of hydrogen atoms and is able to detect hydrogen or deuterium atoms with an energy down to 10 eV. (author) 6 refs., 4 figs

  16. Application of lidar techniques to time-of-flight range imaging.

    Science.gov (United States)

    Whyte, Refael; Streeter, Lee; Cree, Michael J; Dorrington, Adrian A

    2015-11-20

    Amplitude-modulated continuous wave (AMCW) time-of-flight (ToF) range imaging cameras measure distance by illuminating the scene with amplitude-modulated light and measuring the phase difference between the transmitted and reflected modulation envelope. This method of optical range measurement suffers from errors caused by multiple propagation paths, motion, phase wrapping, and nonideal amplitude modulation. In this paper a ToF camera is modified to operate in modes analogous to continuous wave (CW) and stepped frequency continuous wave (SFCW) lidar. In CW operation the velocity of objects can be measured. CW measurement of velocity was linear with true velocity (R2=0.9969). Qualitative analysis of a complex scene confirms that range measured by SFCW is resilient to errors caused by multiple propagation paths, phase wrapping, and nonideal amplitude modulation which plague AMCW operation. In viewing a complicated scene through a translucent sheet, quantitative comparison of AMCW with SFCW demonstrated a reduction in the median error from -1.3  m to -0.06  m with interquartile range of error reduced from 4.0 m to 0.18 m.

  17. Development of a Portable Single Photon Ionization-Photoelectron Ionization Time-of-Flight Mass Spectrometer

    Science.gov (United States)

    Huang, Yunguang; Li, Jinxu; Tang, Bin; Zhu, Liping; Hou, Keyong; Li, Haiyang

    2015-01-01

    A vacuum ultraviolet lamp based single photon ionization- (SPI-) photoelectron ionization (PEI) portable reflecting time-of-flight mass spectrometer (TOFMS) was designed for online monitoring gas samples. It has a dual mode ionization source: SPI for analyte with ionization energy (IE) below 10.6 eV and PEI for IE higher than 10.6 eV. Two kinds of sampling inlets, a capillary inlet and a membrane inlet, are utilized for high concentration and trace volatile organic compounds, respectively. A mass resolution of 1100 at m/z 64 has been obtained with a total size of 40 × 31 × 29 cm, the weight is 27 kg, and the power consumption is only 70 W. A mixture of benzene, toluene, and xylene (BTX), SO2, and discharging products of SF6 were used to test its performance, and the result showed that the limit of quantitation for BTX is as low as 5 ppbv (S/N = 10 : 1) with linear dynamic ranges greater than four orders of magnitude. The portable TOFMS was also evaluated by analyzing volatile organic compounds from wine and decomposition products of SF6 inside of a gas-insulated switchgear. PMID:26587023

  18. A compact time-of-flight mass-spectrometer with electrostatic mirrors

    International Nuclear Information System (INIS)

    Wilken, B.; Stuedemann, W.

    1984-01-01

    A compact low-weight time-of-flight/solid state detector ion mass-spectrometer is described in detail. The two time-zero detectors for the TOF-measurement use secondary electron emission and microchannelplates. A symmetric dual electrostatic mirror is used to deflect both the 'START' and 'STOP' electrons by 90 0 . The crosstalk in the mirror system is measured as a function of the potential applied to the center grid. It is found that 'START' electrons dominate the 'STOP' rate for mirror voltages 0 0 . The primary source for this contamination are backscattered electrons. For Usub(CG) exceeding a critical limit the isolation between the 'START' and 'STOP' system is sufficient. Characteristic background signatures in the two-dimensional pulse height distribution of such a mass-spectrometer are discussed. With some limitations molecular particles can be identified even on an event by event basis. The described TOF spectrometer has particular advantages for ion composition measurements in space plasma research. (orig.)

  19. A surface flaw sizing study by time-of-flight ultrasonic technique

    International Nuclear Information System (INIS)

    Lamy, C.A.

    1990-07-01

    In this work, sizing of inclined slits and surface cracks in ferritic steel using the ultrasonic time-of-flight technique was studied. The surface cracks were vertical and inclined, nut the slits were only inclined. It was surface Rayleigh wave that was converted to shear wave mode in the material. The specimens with surface crack were submitted to a three four point loading fracture mechanics tests, so that the region of the crack tip became under an increasing tensile stress. Thus, the ultrasonic crack sizing could be compared to the material stress intensity factor (K) of the material for different loadings. Results show that the greater the slope and/or lenght of the slits the greater its subsizing. Vertical cracks int he parent metal are reliably and accuratly sized; in the weld the same remark held if one increases the gain of ultrasonic flaw detector to compensate for the weld attenuation phenomenon. Sizing of inclined cracks in the parent metal shows the same trends of the inclined slits, differing only in slopes over 30 sup(0) where the sizing in surface cracks is no longer reliable. A new appraisal procedure here proposed made reliable these results. The techniques employed in this work lead to reliable and accurate results for sizing of different slits and cracks. It should be noted however that good results are only obtained if a tensile stress state exists in the neighbourhood of the c rack tip. (author)

  20. Determination of triacetone triperoxide using ultraviolet femtosecond multiphoton ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Ezoe, Ryota; Imasaka, Tomoko; Imasaka, Totaro

    2015-01-01

    Triacetone triperoxide (TATP), an explosive compound, was measured using gas chromatography combined with multiphoton ionization time-of-flight mass spectrometry (GC/MPI-TOFMS). By decreasing the pulse width of a femtosecond laser from 80 to 35 fs, a molecular ion was drastically enhanced and was measured as one of the major ions in the mass spectrum. The detection limits obtained using the molecular (M(+)) and fragment (C2H3O(+)) ions were similar or slightly superior to those obtained using conventional mass spectrometry based on electron and chemical ionization. In order to improve the reliability, an isotope of TATP, i.e., TATP-d18, was synthesized and used as an internal standard in the trace analysis of TATP in a sample of human blood. TATP could be identified in a two-dimensional display, even though numerous interfering compounds were present in the sample. Acetone, which is frequently used as a solvent in sampling TATP, produced a chemical species with a retention time nearly identical to that of TATP and provided a C2H3O(+) fragment ion that was employed for measuring a chromatogram of TATP in conventional MS. This compound, the structure of which was assigned as phorone, was clearly differentiated from TATP based on a molecular ion observable in MPI-TOFMS. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Design of the multi-reflection time-of-flight mass spectrometer for the RAON facility

    International Nuclear Information System (INIS)

    Yoon, J.W.; Park, Y.H.; Park, S.J.; Kim, G.D.; Kim, Y.K.

    2014-01-01

    A multi-reflection time-of-flight mass spectrometer (MR-TOF-MS) has been proposed for high precision mass measurements on the future Korean heavy ion accelerator called RAON. MR-TOF-MS will allow us to reach very high mass resolving power (> 10 5 ) with extremely short measurement times (several ms) in a compact device. The MR-TOF-MS is composed of two electrostatic ion mirrors in combination with einzel lenses. The principle is that the injected ions travel for hundreds of revolutions inside MR-TOF-MS and ions with different masses are temporally separated. When temporal separation becomes larger than the ion bunch width, ions are extracted from the MR-TOF-MS by switching off the mirror voltages, and then arrive at a detector plane located at time focus, where an MCP detector for the mass measurement or an ion gate for the isobar separation is deployed. In this paper, simulation results for the MR-TOF-MS design using SIMION code are presented. Temporal broadenings, caused by the kinetic energy spread and the transverse emittance, were minimized by optimization of the electrode potentials, and it was demonstrated that the mass resolving power of 10 5 is achievable for the condition of an energy spread of ±30 eV and an emittance of 0.75 π*mm*mrad

  2. Multiple-reflection time-of-flight mass spectrometry for in situ applications

    International Nuclear Information System (INIS)

    Dickel, T.; Plaß, W.R.; Lang, J.; Ebert, J.; Geissel, H.; Haettner, E.; Jesch, C.; Lippert, W.; Petrick, M.; Scheidenberger, C.; Yavor, M.I.

    2013-01-01

    Highlights: • MR-TOF-MS: huge potential in chemistry, medicine, space science, homeland security. • Compact MR-TOF-MS (length ∼30 cm) with very high mass resolving powers (10 5 ). • Combination of high resolving power (>10 5 ), mobility, API for in situ measurements. • Envisaged applications of mobile MR-TOF-MS. -- Abstract: Multiple-reflection time-of-flight mass spectrometers (MR-TOF-MS) have recently been installed at different low-energy radioactive ion beam facilities. They are used as isobar separators with high ion capacity and as mass spectrometers with high mass resolving power and accuracy for short-lived nuclei. Furthermore, MR-TOF-MS have a huge potential for applications in other fields, such as chemistry, biology, medicine, space science, and homeland security. The development, commissioning and results of an MR-TOF-MS is presented, which serves as proof-of-principle to show that very high mass resolving powers (∼10 5 ) can be achieved in a compact device (length ∼30 cm). Based on this work, an MR-TOF-MS for in situ application has been designed. For the first time, this device combines very high mass resolving power (>10 5 ), mobility, and an atmospheric pressure inlet in one instrument. It will enable in situ measurements without sample preparation at very high mass accuracy. Envisaged applications of this mobile MR-TOF-MS are discussed

  3. Monoacylglycerol Analysis Using MS/MSALL Quadruple Time of Flight Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Fei Gao

    2016-08-01

    Full Text Available Monoacylglycerols (MAGs are structural and bioactive metabolites critical for biological function. Development of facile tools for measuring MAG are essential to understand its role in different diseases and various pathways. A data-independent acquisition method, MS/MSALL, using electrospray ionization (ESI coupled quadrupole time of flight mass spectrometry (MS, was utilized for the structural identification and quantitative analysis of individual MAG molecular species. Compared with other acylglycerols, diacylglycerols (DAG and triacylglycerols (TAG, MAG characteristically presented as a dominant protonated ion, [M + H]+, and under low collision energy as fatty acid-like fragments due to the neutral loss of the glycerol head group. At low concentrations (<10 pmol/µL, where lipid-lipid interactions are rare, there was a strong linear correlation between ion abundance and MAG concentration. Moreover, using the MS/MSALL method the major MAG species from human plasma and mouse brown and white adipose tissues were quantified in less than 6 min. Collectively, these results demonstrate that MS/MSALL analysis of MAG is an enabling strategy for the direct identification and quantitative analysis of low level MAG species from biological samples with high throughput and sensitivity.

  4. Analysis of sample composition using resonant ionization and time-of-flight techniques

    International Nuclear Information System (INIS)

    Luz, A. de la; Ortiz, M.; Campos, J.

    1995-01-01

    This paper describes the setting up of a linear time-of-flight mass spectrometer that uses a tunable laser to produce resonant ionization of atoms and molecules in a pulsed supersonic beam. The ability of this kind of systems to produce time resolved signals for each species present in the samples allows quantitative analysis of its composition. By using a tunable laser beam of high spectral resolution to produce ionization, studies based on the structure of the photoionization spectra obtained are possible. In the present work several isotopic species of ordinary and deuterated benzene have been studies. special care has been dedicated to the influence of the presence of a ''13 C in the ring. In this way values for spectroscopic constants and isotopic shifts have been obtained. Another system based in a homemade proportional counter has been designed and used as an auxiliary system. The results obtained with it are independent of these mentioned above and compatible with them. This system is of great utility for laser wavelength tuning to produce ionization in the mass spectrometer

  5. Analysis of sample composition using resonant ionization and time-of-flight techniques

    International Nuclear Information System (INIS)

    Cruz, A. de la; Ortiz, M.; Campos, J.

    1995-01-01

    This paper describes the setting up of a linear time-of-flight mass spectrometer that uses a tunable laser to produce resonant ionization of atoms and molecules in a pulsed supersonic beam. The ability of this kind of systems to produce time resolved signals for each species present in the sample allows quantitative analysis of its composition. By using a tunable laser beam of high spectral resolution to produce ionization, studies based on the structure of the photoionization spectra obtained are possible. In the present work several isotopic species of ordinary and deuterated benzene have been studied. Special care has been dedicated to the influence of the presence of a 13C in the ring. In this way values for spectroscopic constants and isotopic shifts have been obtained. Another system based in a homemade proportional counter has been designed and used is an auxiliary system. The results obtained with it are independent of these mentioned above and compatible with them. This system is of great utility for laser wavelength tuning to produce ionization in the mass spectrometer. (Author) 98 refs

  6. Tandem Mass Spectrometry on a Miniaturized Laser Desorption Time-of-Flight Mass Spectrometer

    Science.gov (United States)

    Li, Xiang; Cornish, Timothy; Getty, Stephanie A.; Brinckerhoff, William B.

    2016-01-01

    Tandem mass spectrometry (MSMS) is a powerful and widely-used technique for identifying the molecular structure of organic constituents of a complex sample. Application of MSMS to the study of unknown planetary samples on a remote space mission would contribute to our understanding of the origin, evolution, and distribution of extraterrestrial organics in our solar system. Here we report on the realization of MSMS on a miniaturized laser desorption time-of-flight mass spectrometer (LD-TOF-MS), which is one of the most promising instrument types for future planetary missions. This achievement relies on two critical components: a curved-field reflectron and a pulsed-pin ion gate. These enable use of the complementary post-source decay (PSD) and laser-assisted collision induced dissociation (L-CID) MSMS methods on diverse measurement targets with only modest investment in instrument resources such as volume and weight. MSMS spectra of selected molecular targets in various organic standards exhibit excellent agreement when compared with results from a commercial, laboratory-scale TOF instrument, demonstrating the potential of this powerful technique in space and planetary environments.

  7. Bayesian Time-of-Flight for Realtime Shape, Illumination and Albedo.

    Science.gov (United States)

    Adam, Amit; Dann, Christoph; Yair, Omer; Mazor, Shai; Nowozin, Sebastian

    2017-05-01

    We propose a computational model for shape, illumination and albedo inference in a pulsed time-of-flight (TOF) camera. In contrast to TOF cameras based on phase modulation, our camera enables general exposure profiles. This results in added flexibility and requires novel computational approaches. To address this challenge we propose a generative probabilistic model that accurately relates latent imaging conditions to observed camera responses. While principled, realtime inference in the model turns out to be infeasible, and we propose to employ efficient non-parametric regression trees to approximate the model outputs. As a result we are able to provide, for each pixel, at video frame rate, estimates and uncertainty for depth, effective albedo, and ambient light intensity . These results we present are state-of-the-art in depth imaging. The flexibility of our approach allows us to easily enrich our generative model. We demonstrate this by extending the original single-path model to a two-path model, capable of describing some multipath effects. The new model is seamlessly integrated in the system at no additional computational cost. Our work also addresses the important question of optimal exposure design in pulsed TOF systems. Finally, for benchmark purposes and to obtain realistic empirical priors of multipath and insights into this phenomena, we propose a physically accurate simulation of multipath phenomena.

  8. Gas-phase pesticide measurement using iodide ionization time-of-flight mass spectrometry

    Science.gov (United States)

    Murschell, Trey; Fulgham, S. Ryan; Farmer, Delphine K.

    2017-06-01

    Volatilization and subsequent processing in the atmosphere are an important environmental pathway for the transport and chemical fate of pesticides. However, these processes remain a particularly poorly understood component of pesticide lifecycles due to analytical challenges in measuring pesticides in the atmosphere. Most pesticide measurements require long (hours to days) sampling times coupled with offline analysis, inhibiting observation of meteorologically driven events or investigation of rapid oxidation chemistry. Here, we present chemical ionization time-of-flight mass spectrometry with iodide reagent ions as a fast and sensitive measurement of four current-use pesticides. These semi-volatile pesticides were calibrated with injections of solutions onto a filter and subsequently volatilized to generate gas-phase analytes. Trifluralin and atrazine are detected as iodide-molecule adducts, while permethrin and metolachlor are detected as adducts between iodide and fragments of the parent analyte molecule. Limits of detection (1 s) are 0.37, 0.67, 0.56, and 1.1 µg m-3 for gas-phase trifluralin, metolachlor, atrazine, and permethrin, respectively. The sensitivities of trifluralin and metolachlor depend on relative humidity, changing as much as 70 and 59, respectively, as relative humidity of the sample air varies from 0 to 80 %. This measurement approach is thus appropriate for laboratory experiments and potentially near-source field measurements.

  9. Gas-phase pesticide measurement using iodide ionization time-of-flight mass spectrometry

    Directory of Open Access Journals (Sweden)

    T. Murschell

    2017-06-01

    Full Text Available Volatilization and subsequent processing in the atmosphere are an important environmental pathway for the transport and chemical fate of pesticides. However, these processes remain a particularly poorly understood component of pesticide lifecycles due to analytical challenges in measuring pesticides in the atmosphere. Most pesticide measurements require long (hours to days sampling times coupled with offline analysis, inhibiting observation of meteorologically driven events or investigation of rapid oxidation chemistry. Here, we present chemical ionization time-of-flight mass spectrometry with iodide reagent ions as a fast and sensitive measurement of four current-use pesticides. These semi-volatile pesticides were calibrated with injections of solutions onto a filter and subsequently volatilized to generate gas-phase analytes. Trifluralin and atrazine are detected as iodide–molecule adducts, while permethrin and metolachlor are detected as adducts between iodide and fragments of the parent analyte molecule. Limits of detection (1 s are 0.37, 0.67, 0.56, and 1.1 µg m−3 for gas-phase trifluralin, metolachlor, atrazine, and permethrin, respectively. The sensitivities of trifluralin and metolachlor depend on relative humidity, changing as much as 70 and 59, respectively, as relative humidity of the sample air varies from 0 to 80 %. This measurement approach is thus appropriate for laboratory experiments and potentially near-source field measurements.

  10. Time of flight measurements based on FPGA using a breast dedicated PET

    International Nuclear Information System (INIS)

    Aguilar, A; García-Olcina, R; Martos, J; Soret, J; Torres, J; Benlloch, J M; González, A J; Sánchez, F

    2014-01-01

    In this work the implementation of a Time-to-Digital Converter (TDC) using a Nutt delay line FPGA-based and applied on a Positron Emission Tomography (PET) device is going to be presented in order to check the system's suitability for Time of Flight (TOF) measurements. In recent years, FPGAs have shown great advantages for precise time measurements in PET. The architecture employed for these measurements is described in detail. The system developed was tested on a dedicated breast PET prototype, composed of LYSO crystals and Positive Sensitive Photomultipliers (PSPMTs). Two distinct experiments were carried out for this purpose. In the first test, system linearity was evaluated in order to calibrate the time measurements, providing a linearity error of less than 2% and an average time resolution of 1.4 ns FWHM. The second set of measurements tested system resolution, resulting in a FWHM as good as 1.35 ns. The results suggest that the coincidence window for the current PET can be reduced in order to minimize the random events and thus, achieve better image quality

  11. Time-based MRPC detector response simulations for the CBM time-of-flight system

    Energy Technology Data Exchange (ETDEWEB)

    Simon, Christian; Herrmann, Norbert [Physikalisches Institut und Fakultaet fuer Physik und Astronomie, Ruprecht-Karls-Universitaet Heidelberg (Germany); Collaboration: CBM-Collaboration

    2016-07-01

    The design goal of the future Compressed Baryonic Matter (CBM) experiment is to measure rare probes of dense strongly interacting matter with an unprecedented accuracy. Target interaction rates of up to 10 MHz need to be processed by the detector. The time-of-flight (TOF) wall of CBM which should provide hadron identification at particle fluxes of up to a few tens of kHz/cm{sup 2} is composed of high-resolution timing multi-gap resistive plate chambers (MRPCs). Due to the self-triggered digitization and readout scheme of CBM comprising online event reconstruction preparatory Monte Carlo (MC) transport and response simulations including the MRPC array need to be carried out in a time-based fashion. While in an event-based simulation mode interference between MC tracks in a detector volume owing to rate effects or electronics dead time is confined to a single event, time-based response simulations need to take into account track pile-up and interference across events. A proposed time-based digitizer class for CBM-TOF within the CbmRoot software framework is presented.

  12. Time-of-flight secondary ion mass spectrometry of fatty acids in rat retina

    Energy Technology Data Exchange (ETDEWEB)

    Gong, H.; Amemiya, T.; Takaya, K.; Tozu, M.; Ohashi, Y

    2003-01-15

    The retina consists of many kinds of central nervous cells, and some cells contain fatty acids such as palmitic acid, stearic acid and oleic acid. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) has a possibility to detect kinds and quantity of materials in relation to the cell or tissue. We applied TOF-SIMS to detect the palmitic acid, stearic acid and oleic acid in the visual cell of the rat retina. We used 4- and 18-month-old normal Wistar Kyoto rats. After pentobarbital anesthesia, the eyes were enucleated, and immediately put into liquid nitrogen without any fixation and then cut into semithin sections (10 {mu}m) with a cryo-ultramicrotome, and laid it on a silicon wafer plate and air-dried. Ion images were detected with TOF-SIMS. Positive ion images were examined with a Ga{sup +} source at an acceleration voltage of 15 keV. The secondary ion acceleration voltage was 4.5 keV. In the 4-month-old rat, palmitic and stearic acid were detected in the photoreceptor outer segment and nuclear parts, but not in the inner segment. In the 18-month-old rat, the oleic acid is significantly decreased compared to that in the 4-month-old rat. TOF-SIMS is a useful tool to detect the changes of fatty acids corresponding to changes of physiological conditions in relation to the histological features.

  13. Combining endoscopic ultrasound with Time-Of-Flight PET: The EndoTOFPET-US Project

    CERN Document Server

    Frisch, Benjamin

    2013-01-01

    The EndoTOFPET-US collaboration develops a multimodal imaging technique for endoscopic exams of the pancreas or the prostate. It combines the benefits of high resolution metabolic imaging with Time-Of-Flight Positron Emission Tomography (TOF PET) and anatomical imaging with ultrasound (US). EndoTOFPET-US consists of a PET head extension for a commercial US endoscope and a PET plate outside the body in coincidence with the head. The high level of miniaturization and integration creates challenges in fields such as scintillating crystals, ultra-fast photo-detection, highly integrated electronics, system integration and image reconstruction. Amongst the developments, fast scintillators as well as fast and compact digital SiPMs with single SPAD readout are used to obtain the best coincidence time resolution (CTR). Highly integrated ASICs and DAQ electronics contribute to the timing performances of EndoTOFPET. In view of the targeted resolution of around 1 mm in the reconstructed image, we present a prototype dete...

  14. Development of a monoenergetic neutron beam (Theoretical aspects, experimental developments and applications)

    International Nuclear Information System (INIS)

    Varela G, A.

    2003-01-01

    By the use of a neutron time of flight system at the Tandem Accelerator of the National Nuclear Research Institute; with neutrons provided by means of the 2 H(d, n) 3 He we intend to use the associated particle technique in order to have monoenergetic neutrons. This neutron beam will be used both in basic and applied research. (Author)

  15. Investigation of time-of-flight lifetime measurement methods of charged π mesons at the Phasotron of JINR

    International Nuclear Information System (INIS)

    Evtukhovich, P.G.; Kallies, W.; Kononenko, G.A.; Samojlov, V.N.; Sapogov, A.S.

    2003-01-01

    The methods of time-of-flight lifetime measurement of charged π mesons that have been realized at the Phasotron of the Laboratory of Nuclear Problems (LNP) of JINR are described. The distinguishing feature of the given methods consists in the use of the following technique: 1) time-of-flight investigation of particle beam composition for relatively long flight path (base); 2) an optimal choice (for the given base) of beam geometry under investigation; 3) monitoring of π-meson momentum along the whole explored trajectory; 4) the use of high resolution scintillation detectors. This technique together with correct mathematical calculations provided a possibility of controlling the influence of main systematic factors on the precision of the data obtained. These methods allow one to compute an amount of sampling that requisites a given precision based on preliminary evaluations of random and systematic errors of charged π-mesons measured lifetime

  16. Timing and Spectroscopy Requirements for a Plastic Scintillating Fiber Bundle Time-of-Flight Neutron Spectrometer

    Science.gov (United States)

    2013-12-01

    reflections in- volves two different methods. The first is pulse height discrimination and the the second is time discrimination. For pulse height ...noise. All acquired data requires pulse height discrimination in the post-processing of the data. The time discrimination method involves calculating... discrimination , the majority of scin- tillation photons that are totally internally reflected down the scintillator toward the ends will exit and escape the

  17. Identification of molecules in graphite furnace by laser ionization time-of-flight mass spectrometry: sulfur and chlorine containing compounds

    CSIR Research Space (South Africa)

    Raseleka, RM

    2004-01-01

    Full Text Available An electro thermal vaporizer (ETV) coupled to a time-of-flight mass spectrometer (TOF-MS) with laser ionization (LI) was applied to the identification of molecules from sulphur and chlorine matrices in the furnace. An interface was developed...

  18. Broadband photon time of flight spectroscopy: advanced spectroscopic analysis for ensuring safety and performance of pharmaceutical tablets

    DEFF Research Database (Denmark)

    Kamran, Faisal; Nielsen, Otto Højager Attermann; Andersson-Engels, Stefan

    2013-01-01

    We report on extended spectroscopic analysis of pharmaceutical tablets performed with broadband photon time-of-flight absorption/scaring spectroscopy. Precise monitoring of absorption and scattering spectra enables cost-efficient monitoring of key safety and performance parameters of the drugs....

  19. Electrospray ionization quadrupole time-of-flight tandem mass spectrometric analysis of hexamethylenediamine-modified maltodextrin and dextran

    NARCIS (Netherlands)

    Sisu, E.; Bosker, W.T.E.; Norde, W.; Slaghek, T.M.; Timmermans, J.W.; Peter-Katalinić, J.; Cohen-Stuart, M.A.; Zamfir, A.D.

    2006-01-01

    A combined methodology for obtaining at the preparative scale and characterization by nanoelectrospray ionization (nanoESI) quadrupole time-of-flight (QTOF) mass spectrometry (MS) and tandem MS (MS/MS) of linear polysaccharides modified at the reducing end is presented. Two polydisperse

  20. Gas chromatographic quadrupole time-of-flight full scan high resolution mass spectrometric screening of human urine in antidoping analysis

    NARCIS (Netherlands)

    Abushareeda, Wadha; Lyris, Emmanouil; Kraiem, Suhail; Wahaibi, Aisha Al; Alyazidi, Sameera; Dbes, Najib; Lommen, Arjen; Nielen, Michel; Horvatovich, Peter L.; Alsayrafi, Mohammed; Georgakopoulos, Costas

    2017-01-01

    This paper presents the development and validation of a high-resolution full scan (FS) electron impact ionization (EI) gas chromatography coupled to quadrupole Time-of-Flight mass spectrometry (GC/QTOF) platform for screening anabolic androgenic steroids (AAS) in human urine samples. The World

  1. Characterisation of Stevia Rebaudiana by comprehensive two-dimensional liquid chromatography time-of-flight mass spectrometry

    Czech Academy of Sciences Publication Activity Database

    Pól, Jaroslav; Hohnová, B.; Hyötyläinen, T.

    2007-01-01

    Roč. 1150, 1-2 (2007), s. 85-92 ISSN 0021-9673 R&D Projects: GA AV ČR KJB4031405 Institutional research plan: CEZ:AV0Z40310501 Keywords : comprehensive two-dimensional liquid chromatography * time-of-flight mass spectrometry * Stevia rebaudiana Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.641, year: 2007

  2. Gas chromatographic quadrupole time-of-flight full scan high resolution mass spectrometric screening of human urine in antidoping analysis

    NARCIS (Netherlands)

    Abushareeda, Wadha; Lyris, Emmanouil; Kraiem, Suhail; Wahaibi, Aisha Al; Alyazidi, Sameera; Dbes, Najib; Lommen, Arjen; Nielen, Michel; Horvatovich, Peter L.; Alsayrafi, Mohammed; Georgakopoulos, Costas

    2017-01-01

    This paper presents the development and validation of a high-resolution full scan (FS) electron impact ionization (EI) gas chromatography coupled to quadrupole Time-of-Flight mass spectrometry (GC/QTOF) platform for screening anabolic androgenic steroids (AAS) in human urine samples. The World

  3. Phenotypic identification of Porphyromonas gingivalis validated with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

    NARCIS (Netherlands)

    Rams, Thomas E; Sautter, Jacqueline D; Getreu, Adam; van Winkelhoff, Arie J

    OBJECTIVE: Porphyromonas gingivalis is a major bacterial pathogen in human periodontitis. This study used matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry to assess the accuracy of a rapid phenotypic identification scheme for detection of cultivable P.

  4. Time of flight spectrometer DEPIL and its use for high protein mass measurement greater than 5000 u

    International Nuclear Information System (INIS)

    Della-Negra, S.; Deprun, C.; Le Beyec, Y.

    1986-01-01

    A new time-of-flight mass spectrometer has been built at the Institut to measure high mass molecules. The mass range is between 1 and 20.000 u. We discuss briefly the apparatus and give results on high mass measurements [fr

  5. A pre-processing strategy for liquid chromatography time-of-flight mass spectrometry metabolic fingerprinting data

    DEFF Research Database (Denmark)

    Nielsen, Nikoline Juul; Tomasi, Giorgio; Frandsen, Rasmus John Normand

    2010-01-01

    A series of simple and robust operations for handling large chromatographic time-of-flight mass spectrometry fingerprinting data has been established and applied to data from extracts of Fusarium graminearum genotypes modified in a non-ribosomal peptide synthase gene by over-expression and deleti...

  6. Variations of High-Latitude Geomagnetic Pulsation Frequencies: A Comparison of Time-of-Flight Estimates and IMAGE Magnetometer Observations

    Science.gov (United States)

    Sandhu, J. K.; Yeoman, T. K.; James, M. K.; Rae, I. J.; Fear, R. C.

    2018-01-01

    The fundamental eigenfrequencies of standing Alfvén waves on closed geomagnetic field lines are estimated for the region spanning 5.9≤L relatively simplistic mass density model. An assessment of the implications of using different mass density models in the time-of-flight calculations is presented. The calculated frequencies exhibit dependences on field line footprint magnetic latitude and MLT, which are attributed to both magnetic field configuration and spatial variations in mass density. In order to assess the validity of the time-of-flight calculated frequencies, the estimates are compared to observations of FLR (Field Line Resonance) frequencies. Using IMAGE (International Monitor for Auroral Geomagnetic Effects) ground magnetometer observations obtained between 2001 and 2012, an automated FLR identification method is developed, based on the cross-phase technique. The average FLR frequency is determined, including variations with footprint latitude and MLT, and compared to the time-of-flight analysis. The results show agreement in the latitudinal and local time dependences. Furthermore, with the use of the realistic mass density model in the time-of-flight calculations, closer agreement with the observed FLR frequencies is obtained. The study is limited by the latitudinal coverage of the IMAGE magnetometer array, and future work will aim to extend the ground magnetometer data used to include additional magnetometer arrays.

  7. Development of analytically capable time-of-flight mass spectrometer with continuous ion introduction

    Science.gov (United States)

    Hárs, György; Dobos, Gábor

    2010-03-01

    The present article describes the results and findings explored in the course of the development of the analytically capable prototype of continuous time-of-flight (CTOF) mass spectrometer. Currently marketed pulsed TOF (PTOF) instruments use ion introduction with a 10 ns or so pulse width, followed by a waiting period roughly 100 μs. Accordingly, the sample is under excitation in 10-4 part of the total measuring time. This very low duty cycle severely limits the sensitivity of the PTOF method. A possible approach to deal with this problem is to use linear sinusoidal dual modulation technique (CTOF) as described in this article. This way the sensitivity of the method is increased, due to the 50% duty cycle of the excitation. All other types of TOF spectrometer use secondary electron multiplier (SEM) for detection, which unfortunately discriminates in amplification in favor of the lighter ions. This discrimination effect is especially undesirable in a mass spectrometric method, which targets high mass range. In CTOF method, SEM is replaced with Faraday cup detector, thus eliminating the mass discrimination effect. Omitting SEM is made possible by the high ion intensity and the very slow ion detection with some hundred hertz detection bandwidth. The electrometer electronics of the Faraday cup detector operates with amplification 1010 V/A. The primary ion beam is highly monoenergetic due to the construction of the ion gun, which made possible to omit any electrostatic mirror configuration for bunching the ions. The measurement is controlled by a personal computer and the intelligent signal generator Type Tabor WW 2571, which uses the direct digital synthesis technique for making arbitrary wave forms. The data are collected by a Labjack interface board, and the fast Fourier transformation is performed by the software. Noble gas mixture has been used to test the analytical capabilities of the prototype setup. Measurement presented proves the results of the mathematical

  8. A high-resolution time-of-flight spectrometer for fission fragments and ion beams

    International Nuclear Information System (INIS)

    Kosev, Krasimir Milchev

    2007-01-01

    For the purpose of fission-fragment detection a double time-of-flight (TOF) spectrometer has been developed. The key component of the TOF spectrometer is a TOF detector consisting of multichannel-plate (MCP) detectors with a position-sensitive readout, a foil for secondary electron (SE) production and an electrostatic mirror. The fission fragments are detected by measuring the SEs impinging on the position-sensitive anode after emission from the foil, acceleration and deflection by the electrostatic mirror. The functionality of the different detector components is proven in detail. Optimised schemes for the high-voltage supplies of the MCP detectors have been implemented successfully. In order to process the multichannel-plate detector signals optimally, a new state-of-the-art constant-fraction discriminator based on the amplitude and rise time compensated technique with very low threshold capabilities and optimised walk properties has been developed and incorporated into the setup. In a setup consisting of two mirror MCP detectors, we could successfully observe the TOF spectrum of a mixed ( 226 Ra, 222 Rn, 210 Po, 218 Po, 214 Po) α-source. Testing photo-fission experiments were performed at the bremsstrahlung facility at the ELBE accelerator. The setup consisted of two mirror detectors (first arm) and a 80 mm diameter MCP detector (second arm) with a 238 U target positioned in between. TOF measurements with two bremsstrahlung end-point energies of 12.9 and 16.0 MeV were carried out. A clear cut separation of the TOF peaks for the medium-mass and heavy fission fragments was observed. (orig.)

  9. Novel pixel architecture with inherent background suppression for 3D time-of-flight imaging

    Science.gov (United States)

    Oggier, Thierry; Kaufmann, Rolf; Lehmann, Michael; Buttgen, Bernhard; Neukom, Simon; Richter, Michael; Schweizer, Matthias; Metzler, Peter; Lustenberger, Felix; Blanc, Nicolas

    2005-01-01

    The time-of-flight (TOF) principle is a well known technology to acquire a scene in all three dimensions. The advantages of the knowledge of the third dimension are obvious for many kinds of applications. The distance information within the scene renders automatic information-processing systems more robust and much less complex or even enables completely new solutions. A solid-state image sensor containing 124x160 pixels and the corresponding 3D-camera, the so-called SwissRanger camera has already been presented in detail. It has been shown that the SwissRanger camera achieves depth resolutions in the sub-centimeter range, corresponding to a measured time resolution of a few tens of picoseconds with respect to the speed of light. However, one main drawback of these so-called lock-in TOF pixels is their limited capacity to handle background illumination. Keeping in mind that in outdoor applications the optical power on the sensor originating from background illumination such as sunlight may be up to a few 100 times higher than the power of the modulated illumination, the sensor requires new pixel structures eliminating or at least reducing the currently experienced restrictions in terms of background illumination. Based on a custom 0.6um CMOS/CCD technology, a new pixel architecture suppressing background illumination and/or improving the ratio of modulated signal to background signal at the pixel-output level was developed and will be presented in this paper. The theoretical principle of operation and the expected performance measures are described. Furthermore, test results obtained in a laboratory setup are published. The sensor structure is characterized in a high background-light environment. This in-depth evaluation leads to a comparison of the background suppression approach with the traditional pixel structure in order to highlight the benefits of the new approach.

  10. In-home hierarchical posture classification with a time-of-flight 3D sensor.

    Science.gov (United States)

    Diraco, Giovanni; Leone, Alessandro; Siciliano, Pietro

    2014-01-01

    A non-invasive technique for posture classification suitable to be used in several in-home scenarios is proposed and preliminary validation results are presented. 3D point cloud sequences were acquired using a single time-of-flight sensor working in a privacy preserving modality and they were processed with a low power embedded PC. In order to satisfy different application requirements (e.g. covered distance range, processing speed and discrimination capabilities), a twofold discrimination approach was investigated in which features were hierarchically arranged from coarse to fine by exploiting both topological and volumetric representations. The topological representation encoded the intrinsic topology of the body's shape using a skeleton-based structure, thus guaranteeing invariance to scale, rotations and postural changes and achieving a high level of detail with a moderate computational cost. On the other hand, using the volumetric representation features were described in terms of 3D cylindrical histograms working within a wider range of distances in a faster way and also guaranteeing good invariance properties. The discrimination capabilities were evaluated in four different real-home scenarios related with the fields of ambient assisted living and homecare, namely "dangerous event detection", "anomalous behaviour detection", "activities recognition" and "natural human-ambient interaction". For each mentioned scenario, the discrimination capabilities were evaluated in terms of invariance to viewpoint changes, representation capabilities and classification performance, achieving promising results. The two feature representation approaches exhibited complementary characteristics showing high reliability with classification rates greater than 97%. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Time-of-flight MR angiography in cerebral venous sinus thrombosis.

    Science.gov (United States)

    Renard, Dimitri; Le Bars, Emmanuelle; Arquizan, Caroline; Gaillard, Nicolas; de Champfleur, Nicolas Menjot; Mourand, Isabelle

    2017-12-01

    Recently, time-of-flight (TOF) and gadolinium-enhanced MR angiography (MRA) imaging have been used to demonstrate subacute intramural hematoma in cervical artery dissection and to detect intraplaque haemorrhage. Our aim was to perform an exploratory study to analyse if venous thrombus-related signal changes (potentially showing iso- or hyperintensity) in cerebral venous sinus thrombosis (CVST) could be observed on 3D-TOF MRA imaging. We analysed retrospectively MRIs of CVST patients in whom both contrast-enhanced MR venography (CEMRV) and 3D-TOF sequences were performed in the acute/subacute phase (i.e. < 31 days after symptom onset). The occluded sinus segments were defined on CEMRV. First, analyses of signal changes in occluded venous sinuses segments (defined by and unblinded to CEMRV) on native 3D-TOF images and morphological MRI sequences were performed. Second, a blinded (to CEMRV and other morphological MRI sequences) analysis was performed on 3D-TOF imaging assessing signal changes on 3D-TOF considering all sinus segments. Twenty-five CVST patients were included. 3D-TOF imaging showed signal changes (most often hyperintensity and less often isointensity) in 84% of the occluded sinus segments. Signal changes were observed in 91% of the occluded sinus segments on T1-weighted imaging, in 69% on T2-weighted imaging, in 68% on FLAIR, in 32% on DWI, and in 55% on T2*-weighted imaging. On blinded analysis, sensitivity of 3D-TOF sequences decreased to 80%, whereas specificity was only 65%. Abnormal signal in the venous sinuses on 3D-TOF may possibly help to suspect CVST, especially when CEMRV sequences lack.

  12. Optimization of time-of-flight reconstruction on Philips GEMINI TF

    International Nuclear Information System (INIS)

    Vandenberghe, Stefaan; Clementel, Enrico; Verhaeghe, Jeroen; Lemahieu, Ignace; Elmbt, Larry van; Bol, Anne; Lonneux, Max; Guerchaft, Michel

    2009-01-01

    The aim of this study is to optimize different parameters in the time-of-flight (TOF) reconstruction for the Philips GEMINI TF. The use of TOF in iterative reconstruction introduces additional variables to be optimized compared to conventional PET reconstruction. The different parameters studied are the TOF kernel width, the kernel truncation (used to reduce reconstruction time) and the scatter correction method. These parameters are optimized using measured phantom studies. All phantom studies were acquired with a very high number of counts to limit the effects of noise. A high number of iterations (33 subsets and 3 iterations) was used to reach convergence. The figures of merit are the uniformity in the background, the cold spot recovery and the hot spot contrast. As reference results we used the non-TOF reconstruction of the same data sets. It is shown that contrast recovery loss can only be avoided if the kernel is extended to more than 3 standard deviations. To obtain uniform reconstructions the recommended scatter correction is TOF single scatter simulation (SSS). This also leads to improved cold spot recovery and hot spot contrast. While the daily measurements of the system show a timing resolution in the range of 590-600 ps, the optimal reconstructions are obtained with a TOF kernel full-width at half-maximum (FWHM) of 650-700 ps. The optimal kernel width seems to be less critical for the recovered contrast but has an important effect on the background uniformity. Using smaller or wider kernels results in a less uniform background and reduced hot and cold contrast recovery. The different parameters studied have a large effect on the quantitative accuracy of the reconstructed images. The optimal settings from this study can be used as a guideline to make an objective comparison of the gains obtained with TOF PET versus PET reconstruction. (orig.)

  13. Quadrupole-time-of-flight mass spectrometry screening for synthetic cannabinoids in herbal blends.

    Science.gov (United States)

    Ibáñez, María; Bijlsma, Lubertus; van Nuijs, Alexander L N; Sancho, Juan V; Haro, Gonzalo; Covaci, Adrian; Hernández, Félix

    2013-06-01

    'Legal highs' are novel substances which are intended to elicit a psychoactive response. They are sold from 'head shops', the internet and from street suppliers and may be possessed without legal restriction. Several months ago, a 19-year-old woman came searching for medical treatment as she had health problems caused by smoking legal highs. The substances were sold as herbal blends in plastic bags under four different labels. In this work, samples of these herbal blends have been analysed to investigate the presence of psychoactive substances without any reference standard being available at the laboratory. A screening strategy for a large number of synthetic and natural cannabinoids has been applied based on the use of ultra-high pressure liquid chromatography coupled to quadrupole-time of flight mass spectrometry (UHPLC-QTOF MS) under MS(E) mode. A customized home-made database containing literature-based exact masses for parent and product ions of around 200 synthetic and natural cannabinoids was compiled. The presence of the (de)protonated molecule measured at its accurate mass was evaluated in the samples. When a peak was detected, collision-induced dissociation fragments and characteristic isotopic ions were also evaluated and used for tentative identification. After this tentative identification, four synthetic cannabinoids (JWH-081, JWH-250, JWH-203 and JWH-019) were unequivocally confirmed by subsequent acquisition of reference standards. The presence in the herbal blends of these synthetic cannabinoids might explain the psychotic and catatonic symptoms observed in the patient, as JWH compounds could act as potent agonists of CB1 and CB2 receptors located in the Limbic System and Basal ganglia of the human brain. Copyright © 2013 John Wiley & Sons, Ltd.

  14. High-performance electronics for time-of-flight PET systems

    International Nuclear Information System (INIS)

    Choong, W-S; Peng, Q; Vu, C Q; Turko, B T; Moses, W W

    2013-01-01

    We have designed and built a high-performance readout electronics system for time-of-flight positron emission tomography (TOF PET) cameras. The electronics architecture is based on the electronics for a commercial whole-body PET camera (Siemens/CPS Cardinal electronics), modified to improve the timing performance. The fundamental contributions in the electronics that can limit the timing resolution include the constant fraction discriminator (CFD), which converts the analog electrical signal from the photo-detector to a digital signal whose leading edge is time-correlated with the input signal, and the time-to-digital converter (TDC), which provides a time stamp for the CFD output. Coincident events are identified by digitally comparing the values of the time stamps. In the Cardinal electronics, the front-end processing electronics are performed by an Analog subsection board, which has two application-specific integrated circuits (ASICs), each servicing a PET block detector module. The ASIC has a built-in CFD and TDC. We found that a significant degradation in the timing resolution comes from the ASIC's CFD and TDC. Therefore, we have designed and built an improved Analog subsection board that replaces the ASIC's CFD and TDC with a high-performance CFD (made with discrete components) and TDC (using the CERN high-performance TDC ASIC). The improved Analog subsection board is used in a custom single-ring LSO-based TOF PET camera. The electronics system achieves a timing resolution of 60 ps FWHM. Prototype TOF detector modules are read out with the electronics system and give coincidence timing resolutions of 259 ps FWHM and 156 ps FWHM for detector modules coupled to LSO and LaBr 3 crystals respectively.

  15. A high-resolution time-of-flight spectrometer for fission fragments and ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Kosev, Krasimir Milchev

    2007-07-01

    For the purpose of fission-fragment detection a double time-of-flight (TOF) spectrometer has been developed. The key component of the TOF spectrometer is a TOF detector consisting of multichannel-plate (MCP) detectors with a position-sensitive readout, a foil for secondary electron (SE) production and an electrostatic mirror. The fission fragments are detected by measuring the SEs impinging on the position-sensitive anode after emission from the foil, acceleration and deflection by the electrostatic mirror. The functionality of the different detector components is proven in detail. Optimised schemes for the high-voltage supplies of the MCP detectors have been implemented successfully. In order to process the multichannel-plate detector signals optimally, a new state-of-the-art constant-fraction discriminator based on the amplitude and rise time compensated technique with very low threshold capabilities and optimised walk properties has been developed and incorporated into the setup. In a setup consisting of two mirror MCP detectors, we could successfully observe the TOF spectrum of a mixed ({sup 226}Ra,{sup 222}Rn,{sup 210}Po,{sup 218}Po,{sup 214}Po) {alpha}-source. Testing photo-fission experiments were performed at the bremsstrahlung facility at the ELBE accelerator. The setup consisted of two mirror detectors (first arm) and a 80 mm diameter MCP detector (second arm) with a {sup 238}U target positioned in between. TOF measurements with two bremsstrahlung end-point energies of 12.9 and 16.0 MeV were carried out. A clear cut separation of the TOF peaks for the medium-mass and heavy fission fragments was observed. (orig.)

  16. High Energy Collisions on Tandem Time-of-Flight Mass Spectrometers

    Science.gov (United States)

    Cotter, Robert J.

    2013-05-01

    Long before the introduction of matrix-assisted laser desorption/ionization (MALDI), electrospray ionization (ESI), Orbitraps, and any of the other tools that are now used ubiquitously for proteomics and metabolomics, the highest performance mass spectrometers were sector instruments, providing high resolution mass measurements by combining an electrostatic energy analyzer (E) with a high field magnet (B). In its heyday, the four sector mass spectrometer (or EBEB) was the crown jewel, providing the highest performance tandem mass spectrometry using single, high energy collisions to induce fragmentation. During a time in which quadrupole and tandem triple quadrupole instruments were also enjoying increased usage and popularity, there were, nonetheless, some clear advantages for sectors over their low collision energy counterparts. Time-of-flight (TOF) mass spectrometers are high voltage, high vacuum instruments that have much in common with sectors and have inspired the development of tandem instruments exploiting single high energy collisions. In this retrospective, we recount our own journey to produce high performance TOFs and tandem TOFs, describing the basic theory, problems, and the advantages for such instruments. An experiment testing impulse collision theory (ICT) underscores the similarities with sector mass spectrometers where this concept was first developed. Applications provide examples of more extensive fragmentation, side chain cleavages, and charge-remote fragmentation, also characteristic of high energy sector mass spectrometers. Moreover, the so-called curved-field reflectron has enabled the design of instruments that are simpler, collect and focus all of the ions, and may provide the future technology for the clinic, for tissue imaging, and the characterization of microorganisms.

  17. Determination of triacetone triperoxide using ultraviolet femtosecond multiphoton ionization time-of-flight mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Ezoe, Ryota [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Imasaka, Tomoko [Laboratory of Chemistry, Graduate School of Design, Kyushu University, 4-9-1, Shiobaru, Minami-ku, Fukuoka 815-8540 (Japan); Imasaka, Totaro, E-mail: imasaka@cstf.kyushu-u.ac.jp [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Division of Optoelectronics and Photonics, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan)

    2015-01-01

    Highlights: • A UV ultrashort laser pulse was useful for ionization of triacetone triperoxide. • A molecular ion was strongly enhanced in multiphoton ionization mass spectrometry. • Triacetone triperoxide in the human blood was measured without any interferences. • An organic compound of phorone was formed in the human blood from acetone. - Abstract: Triacetone triperoxide (TATP), an explosive compound, was measured using gas chromatography combined with multiphoton ionization time-of-flight mass spectrometry (GC/MPI-TOFMS). By decreasing the pulse width of a femtosecond laser from 80 to 35 fs, a molecular ion was drastically enhanced and was measured as one of the major ions in the mass spectrum. The detection limits obtained using the molecular (M·{sup +}) and fragment (C{sub 2}H{sub 3}O{sup +}) ions were similar or slightly superior to those obtained using conventional mass spectrometry based on electron and chemical ionization. In order to improve the reliability, an isotope of TATP, i.e., TATP-d18, was synthesized and used as an internal standard in the trace analysis of TATP in a sample of human blood. TATP could be identified in a two-dimensional display, even though numerous interfering compounds were present in the sample. Acetone, which is frequently used as a solvent in sampling TATP, produced a chemical species with a retention time nearly identical to that of TATP and provided a C{sub 2}H{sub 3}O{sup +} fragment ion that was employed for measuring a chromatogram of TATP in conventional MS. This compound, the structure of which was assigned as phorone, was clearly differentiated from TATP based on a molecular ion observable in MPI-TOFMS.

  18. Time-Of-Flight Camera, Optical Tracker and Computed Tomography in Pairwise Data Registration.

    Directory of Open Access Journals (Sweden)

    Bartlomiej Pycinski

    Full Text Available A growing number of medical applications, including minimal invasive surgery, depends on multi-modal or multi-sensors data processing. Fast and accurate 3D scene analysis, comprising data registration, seems to be crucial for the development of computer aided diagnosis and therapy. The advancement of surface tracking system based on optical trackers already plays an important role in surgical procedures planning. However, new modalities, like the time-of-flight (ToF sensors, widely explored in non-medical fields are powerful and have the potential to become a part of computer aided surgery set-up. Connection of different acquisition systems promises to provide a valuable support for operating room procedures. Therefore, the detailed analysis of the accuracy of such multi-sensors positioning systems is needed.We present the system combining pre-operative CT series with intra-operative ToF-sensor and optical tracker point clouds. The methodology contains: optical sensor set-up and the ToF-camera calibration procedures, data pre-processing algorithms, and registration technique. The data pre-processing yields a surface, in case of CT, and point clouds for ToF-sensor and marker-driven optical tracker representation of an object of interest. An applied registration technique is based on Iterative Closest Point algorithm.The experiments validate the registration of each pair of modalities/sensors involving phantoms of four various human organs in terms of Hausdorff distance and mean absolute distance metrics. The best surface alignment was obtained for CT and optical tracker combination, whereas the worst for experiments involving ToF-camera.The obtained accuracies encourage to further develop the multi-sensors systems. The presented substantive discussion concerning the system limitations and possible improvements mainly related to the depth information produced by the ToF-sensor is useful for computer aided surgery developers.

  19. Analysis of Marine Aerosol Polysaccharides by Pyrolysis Time-of-Flight Mass Spectrometry

    Science.gov (United States)

    Lawler, M. J.; Grieman, M. M.; Sengur, I.; Saltzman, E. S.

    2017-12-01

    The relationship between surface ocean biological productivity and marine cloud formation and properties has been explored for decades, but the impacts of marine biogenic emissions on cloudiness and climate remain highly uncertain. This is in part due to the challenge of directly linking biogenic materials in the surface ocean with cloud-forming aerosol. It has been shown that polysaccharide gel-forming materials, also known as transparent exopolymers, may be mechanically ejected from the sea surface during air bubble bursting (Leck and Bigg, 2005). Existing analysis methods for such aerosols require considerable sample mass and sample preparation. As part of the multi-year seasonal North Atlantic Aerosols and Marine Ecosystems Study (NAAMES), ambient submicron marine aerosol was collected in November 2015 and May 2016 from the R/V Atlantis at using a Particle into Liquid Sampler (PILS). These samples of roughly 15 minute time resolution were frozen and returned to UC Irvine for analysis. A new technique has been developed to attempt to quantify polysaccharide material in these ambient samples. A small subsample (1- 5 µL) is taken from the PILS vial samples and allowed to dry on a Pt ribbon filament in the chemical ionization source region of a time-of-flight mass spectrometer. The sample then undergoes a two-step heating process, in which volatilizable molecules are first desorbed and then non-volatilizable large molecules such as polysaccharides are pyrolyzed. These desorbed molecules and decomposition products are ionized using either O2- or H3O+ reagent ion and are directly sampled into the mass spectrometer. The resulting spectra can then be compared to standards of known polysaccharide materials for quantification and potentially structural and/or compositional information.

  20. PNG-300 a nanosecond pulsed neutron generator

    International Nuclear Information System (INIS)

    Sztaricskai, T.; Vasvary, L.; Petoe, G.C.; Devkin, B.V.

    1985-01-01

    The design and operation of a nanosecond-pulse neutron generator is reported. It was constructed for the measurement of prompt neutron and gamma radiation in experimental studies of fast neutron reactions by time of flight techniques. The acceleration voltage is 300 kV and the total resolution of the generator-neutron spectrometer system is 2 ns. The ion-optical system, the vacuum system and the control of the neutron generator is described in detail. The equipment was used for prompt neutron and gamma radiation induced in construction materials. (R.P.)